CN112827322B - Method for recycling and recycling tail gas FTrPSA of chlorine-based SiC-CVD (silicon carbide-chemical vapor deposition) epitaxial process by reacting ethylene with silane - Google Patents
Method for recycling and recycling tail gas FTrPSA of chlorine-based SiC-CVD (silicon carbide-chemical vapor deposition) epitaxial process by reacting ethylene with silane Download PDFInfo
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- CN112827322B CN112827322B CN202011544297.XA CN202011544297A CN112827322B CN 112827322 B CN112827322 B CN 112827322B CN 202011544297 A CN202011544297 A CN 202011544297A CN 112827322 B CN112827322 B CN 112827322B
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- 238000000034 method Methods 0.000 title claims abstract description 273
- 230000008569 process Effects 0.000 title claims abstract description 244
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 title claims abstract description 108
- 229910000077 silane Inorganic materials 0.000 title claims abstract description 97
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 title claims abstract description 88
- 239000005977 Ethylene Substances 0.000 title claims abstract description 88
- 238000004064 recycling Methods 0.000 title claims abstract description 53
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 title claims description 23
- 239000000460 chlorine Substances 0.000 title claims description 23
- 229910052801 chlorine Inorganic materials 0.000 title claims description 23
- 238000005229 chemical vapour deposition Methods 0.000 title abstract description 16
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title description 7
- 229910052710 silicon Inorganic materials 0.000 title description 7
- 239000010703 silicon Substances 0.000 title description 7
- 239000007789 gas Substances 0.000 claims abstract description 303
- 238000001179 sorption measurement Methods 0.000 claims abstract description 207
- 239000005046 Chlorosilane Substances 0.000 claims abstract description 154
- KOPOQZFJUQMUML-UHFFFAOYSA-N chlorosilane Chemical compound Cl[SiH3] KOPOQZFJUQMUML-UHFFFAOYSA-N 0.000 claims abstract description 149
- 239000001257 hydrogen Substances 0.000 claims abstract description 143
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 143
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 130
- 238000010521 absorption reaction Methods 0.000 claims abstract description 106
- 238000000926 separation method Methods 0.000 claims abstract description 64
- 238000009833 condensation Methods 0.000 claims abstract description 59
- 230000005494 condensation Effects 0.000 claims abstract description 59
- 238000000746 purification Methods 0.000 claims abstract description 57
- 238000007906 compression Methods 0.000 claims abstract description 55
- 230000006835 compression Effects 0.000 claims abstract description 55
- 238000007670 refining Methods 0.000 claims abstract description 37
- 238000001704 evaporation Methods 0.000 claims abstract description 33
- 230000008020 evaporation Effects 0.000 claims abstract description 33
- 238000000605 extraction Methods 0.000 claims abstract description 26
- 239000007788 liquid Substances 0.000 claims description 106
- 238000001816 cooling Methods 0.000 claims description 46
- 239000000047 product Substances 0.000 claims description 43
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 42
- 238000003795 desorption Methods 0.000 claims description 29
- 239000012530 fluid Substances 0.000 claims description 27
- 239000002994 raw material Substances 0.000 claims description 27
- 238000011084 recovery Methods 0.000 claims description 21
- 239000002250 absorbent Substances 0.000 claims description 15
- 230000002745 absorbent Effects 0.000 claims description 15
- 238000004821 distillation Methods 0.000 claims description 15
- 238000006243 chemical reaction Methods 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 14
- 239000004215 Carbon black (E152) Substances 0.000 claims description 13
- 150000002431 hydrogen Chemical class 0.000 claims description 13
- 239000012535 impurity Substances 0.000 claims description 12
- 239000002737 fuel gas Substances 0.000 claims description 10
- 229910052751 metal Inorganic materials 0.000 claims description 10
- 239000002184 metal Substances 0.000 claims description 10
- 239000012466 permeate Substances 0.000 claims description 10
- 239000012528 membrane Substances 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 8
- 238000011010 flushing procedure Methods 0.000 claims description 7
- 239000002245 particle Substances 0.000 claims description 7
- 238000012546 transfer Methods 0.000 claims description 7
- 239000006227 byproduct Substances 0.000 claims description 6
- 230000008929 regeneration Effects 0.000 claims description 6
- 238000011069 regeneration method Methods 0.000 claims description 6
- 239000011259 mixed solution Substances 0.000 claims description 5
- 238000005507 spraying Methods 0.000 claims description 5
- 239000000428 dust Substances 0.000 claims description 4
- 238000001914 filtration Methods 0.000 claims description 4
- 239000003595 mist Substances 0.000 claims description 4
- 239000003921 oil Substances 0.000 claims description 4
- 125000004122 cyclic group Chemical group 0.000 claims description 3
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 3
- 238000010992 reflux Methods 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 2
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 claims 1
- 239000003507 refrigerant Substances 0.000 claims 1
- 239000004065 semiconductor Substances 0.000 abstract description 10
- 239000000463 material Substances 0.000 abstract description 9
- 238000005516 engineering process Methods 0.000 abstract description 4
- 230000007613 environmental effect Effects 0.000 abstract description 4
- 238000002360 preparation method Methods 0.000 abstract description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 107
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 102
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 102
- 239000012071 phase Substances 0.000 description 21
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 13
- 239000003463 adsorbent Substances 0.000 description 13
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 11
- 229910002091 carbon monoxide Inorganic materials 0.000 description 11
- 229910010271 silicon carbide Inorganic materials 0.000 description 11
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 10
- 229910052799 carbon Inorganic materials 0.000 description 10
- 229930195733 hydrocarbon Natural products 0.000 description 9
- 150000002430 hydrocarbons Chemical class 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- 238000000407 epitaxy Methods 0.000 description 8
- 229910004298 SiO 2 Inorganic materials 0.000 description 7
- 229910002092 carbon dioxide Inorganic materials 0.000 description 7
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 6
- 150000001348 alkyl chlorides Chemical class 0.000 description 6
- 238000009835 boiling Methods 0.000 description 5
- 239000002808 molecular sieve Substances 0.000 description 5
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 5
- 239000012159 carrier gas Substances 0.000 description 4
- NEHMKBQYUWJMIP-UHFFFAOYSA-N chloromethane Chemical compound ClC NEHMKBQYUWJMIP-UHFFFAOYSA-N 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000002912 waste gas Substances 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- -1 firstly Substances 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052763 palladium Inorganic materials 0.000 description 3
- 239000000741 silica gel Substances 0.000 description 3
- 229910002027 silica gel Inorganic materials 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 2
- YKTSYUJCYHOUJP-UHFFFAOYSA-N [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] Chemical compound [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] YKTSYUJCYHOUJP-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000002156 adsorbate Substances 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical compound [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 2
- 238000004880 explosion Methods 0.000 description 2
- 239000002360 explosive Substances 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 150000003376 silicon Chemical class 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- SCYULBFZEHDVBN-UHFFFAOYSA-N 1,1-Dichloroethane Chemical compound CC(Cl)Cl SCYULBFZEHDVBN-UHFFFAOYSA-N 0.000 description 1
- WSLDOOZREJYCGB-UHFFFAOYSA-N 1,2-Dichloroethane Chemical compound ClCCCl WSLDOOZREJYCGB-UHFFFAOYSA-N 0.000 description 1
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 description 1
- 229910003902 SiCl 4 Inorganic materials 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000007084 catalytic combustion reaction Methods 0.000 description 1
- 238000005660 chlorination reaction Methods 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- SLLGVCUQYRMELA-UHFFFAOYSA-N chlorosilicon Chemical compound Cl[Si] SLLGVCUQYRMELA-UHFFFAOYSA-N 0.000 description 1
- 238000009841 combustion method Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- BUMGIEFFCMBQDG-UHFFFAOYSA-N dichlorosilicon Chemical compound Cl[Si]Cl BUMGIEFFCMBQDG-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 238000007038 hydrochlorination reaction Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 238000000259 microwave plasma-assisted chemical vapour deposition Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000001451 molecular beam epitaxy Methods 0.000 description 1
- 150000003961 organosilicon compounds Chemical class 0.000 description 1
- 230000005622 photoelectricity Effects 0.000 description 1
- 239000002574 poison Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 239000005049 silicon tetrachloride Substances 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 239000011863 silicon-based powder Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000000859 sublimation Methods 0.000 description 1
- 230000008022 sublimation Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- ZDHXKXAHOVTTAH-UHFFFAOYSA-N trichlorosilane Chemical compound Cl[SiH](Cl)Cl ZDHXKXAHOVTTAH-UHFFFAOYSA-N 0.000 description 1
- 239000005052 trichlorosilane Substances 0.000 description 1
- 238000005292 vacuum distillation Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
- B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
- B01D53/047—Pressure swing adsorption
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D1/00—Evaporating
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/18—Absorbing units; Liquid distributors therefor
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
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- Chemical Kinetics & Catalysis (AREA)
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- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Silicon Compounds (AREA)
Abstract
The invention discloses a method for recycling and recycling tail gas FTrPSA of a chloro-SiC-CVD (chemical vapor deposition) epitaxial process by reacting ethylene with silane, belongs to the field of environmental protection of semiconductor materials and semiconductor processes, and aims to solve the problems that the existing SiC-CVD epitaxial process is high in preparation cost and cannot be recycled from the tail gas, and the method not only realizes the recycling and recycling of all components of the tail gas, but also reduces the emission of the tail gas and fills the blank of tail gas treatment technology of the chloro-SiC-CVD epitaxial process by pretreatment, shallow-cold chlorosilane absorption, shallow-cold pressure swing adsorption concentration, adsorption purification, pressure swing adsorption hydrogen extraction, hydrogen purification, multistage evaporation/compression/condensation, HCl refining, shallow-cold rectification in the chlorosilane, ethylene/silane separation, silane purification and ethylene refining processes, and recycling of high-purity and high-yield H 2、HCl、SiH4、C2H4 is recycled as raw gas.
Description
Technical Field
The invention discloses a recycling method of chlorine-based SiC-CVD epitaxial process tail gas FTrPSA reacted by ethylene and silane, belongs to the technical field of semiconductor materials and environmental protection in semiconductor process, and particularly relates to the technical field of treatment of SiC-CVD epitaxial process tail gas.
Background
Silicon carbide (SiC) is used as a third generation semiconductor material, and has excellent characteristics of wide forbidden band, high temperature and high voltage resistance, high frequency and high power, radiation resistance and the like, so that the silicon carbide (SiC) is widely applied to power switches, frequency conversion and voltage transformation, power electronic components such as UPS and the like in fields of IT and electronic consumer products, automobiles, photovoltaic photoelectricity, nuclear reactors, aerospace and military with harsh system working conditions, and the like, wherein epitaxy is a key production step in which SiC materials are widely applied.
The SiC epitaxial process includes high temperature sublimation (PVT), chemical Vapor Deposition (CVD), liquid phase growth epitaxy (LPE), molecular Beam Epitaxy (MBE), electron cyclotron resonance plasma chemical vapor deposition (ECR-MPCVD), etc., but CVD processes are generally used in industry, which have the characteristics of low epitaxial growth temperature, large production lot, good uniformity of epitaxial films, and easy control of operation, wherein the SiC-CVD epitaxial process can be classified into chlorine-free, chlorine-containing (chlorine-based) and organosilicon compounds containing C/Si sources according to different silicon (Si) sources and carbon (C) sources (referred to as "reaction precursors"), and further, the tail gas composition produced by different epitaxial processes is different, and the processing method is also different accordingly.
The chlorine-based SiC-CVD epitaxial process based on the reaction of ethylene and silane is characterized in that ethylene (C 2H4) is used as a carbon (C) source, silane is used as a silicon (Si) source, hydrogen (H 2) or argon (Ar) is used as carrier gas, and hydrogen chloride (HCl) gas is added into a CVD reaction cavity (furnace) at the same time, and chemical vapor deposition reaction is carried out at a certain temperature and pressure. HCl is added into an epitaxial system, so that generation of silicon clusters in an epitaxial gas phase in a chlorine-free epitaxial process can be effectively inhibited, and further, the use efficiency of a silicon source is improved, namely the epitaxial growth rate is improved. Thus, in a CVD reaction chamber, an epitaxial film produced by the chlorine-based SiC-CVD reaction of ethylene and silane forms a film, i.e., an epitaxial layer, on a suitable substrate or base (typically Si or SiC material) which is processed to yield a qualified SiC epitaxial wafer, while the main products involved in the reaction, which are H 2, HCl, chlorosilane (SiHmCln), a small amount of methane (CH 4), Chloralkane (CHmCln), chloralkene (VCM), light hydrocarbon component (C 2 +) with more than two carbon atoms, and trace Si powder or Si cluster or C powder and other solid tiny particles, wherein the main components which are not reacted are HCl and C 2H4、SiH4, carrier gas H 2 or Ar which does not participate in the reaction, and trace amounts or trace amounts of other impurities such as carbon monoxide (CO), carbon dioxide (CO 2), water (H 2 O), and the like. h 2 is commonly used as carrier gas in commerce, so that the epitaxial efficiency can be effectively improved. Because the tail gas contains toxic, harmful, flammable and explosive chlorosilane/silane, hydrogen, ethylene and HCl components which are extremely strong in corrosiveness and not easy to burn, the tail gas treatment method is special, for example, the treatment process which is commonly adopted in industry and is used for the tail gas combustion method of the conventional chlorine-free SiC-CVD epitaxial process cannot be applied because the tail gas contains more nonflammable HCl. At present, aiming at the development and popularization and application of high breakdown voltage SiC power electronic components, more and more chlorine-based SiC-CVD epitaxial systems are put into use, and become the main stream process of SiC-CVD epitaxy. therefore, the method for treating the tail gas of the chloro-SiC-CVD epitaxial process based on the reaction of ethylene and silane or the recovery and recycling of the effective components greatly reduces the raw material cost or the treatment cost of the tail gas of the chloro-SiC-CVD epitaxial process, and becomes an important development content in the field.
The existing common methods for treating tail gas of the chlorine-based SiC-CVD epitaxial process mainly comprise a dry adsorption type method and a water washing type method.
Firstly, in the tail gas treater of dry adsorption, besides the adsorbent filled with silane, silicon clusters, ethylene or C 2+ as adsorbates, the adsorbent is additionally provided with adsorbents such as HCl and chlorosilane (SiHmCln) with stronger polarity, such as silicon tetrachloride (SiCl 4), trichlorosilane (SiHCl 3), dichlorosilane (SiH 2Cl2), high-chlorosilane, chloroalkane (CHmCln), chloroolefin (VCM) and the like, and the non-adsorbates mainly comprise H 2、CH4 and a small amount of C 2H4/C2+, silane and the like, and the components are directly discharged after testing, wherein the adsorbents after adsorption saturation are replaced periodically, generally by non-regenerable disposable adsorption, or by temperature-variable adsorption (TSA) with on-line regeneration of the adsorbents, the adsorbents are regenerated at a relatively low temperature, and the cyclic operation is performed, wherein the adsorbents subjected to adsorption saturation are discharged from the adsorbent tower by using water vapor with relatively high temperature as regenerated carrier gas, and cooled or condensed, washed and the like, and the mixed solution of SiO 2, HCl and the coarse mixed solution is obtained. The adsorption method only carries out harmless purification treatment, the adsorbent is easy to poison, the adsorption method is suitable for the working condition that the contents of HCl, silane/chlorosilane and ethylene/C 2+ in the tail gas are low, a large amount of H 2 is almost completely wasted, the subsequent treatment of SiO 2 slurry, crude HCl and chlorosilane solution is also very complicated, the emission of adsorption waste gas still can generate greenhouse effect, or the adsorption waste gas has light hydrocarbon components exceeding standards and can reach the standard by further catalytic combustion, thereby increasing the cost of tail gas treatment.
Secondly, the water washing method is suitable for working conditions with higher contents of HCl, chlorosilane and the like in the tail gas, firstly, air and water are introduced according to the amount, silane in the tail gas is directly oxidized into SiO 2 to be discharged, chlorosilane and water are hydrolyzed and react under the action of the air to generate SiO 2 and HC1, siO 2 to be directly discharged, HCl waste solution is also discharged to a waste acid treatment unit, simultaneously, partial components such as ethylene/C 2+ and the like are subjected to hydrochlorination or oxychlorination reaction with HCl under the action of air oxygen or water to generate chloroalkanes (such as dichloroethane (EDC), chloromethane) or chloroalkene (such as chloroethylene VCM), the chloroalkane is output with the rest of inert gas or H 2、CH4 and trace ethylene/C 2+/silane and the like as noncondensable gas, and then the generated incineration waste gas often contains substandard chlorides including VCM and the like, so that secondary pollution is caused, and further treatment is needed. The water washing method has stronger corrosiveness of a system because of the introduction of water, most of chlorosilane is decomposed into HCl and SiO 2, hydrocarbon impurities such as C 2H4/C2+ and the like are still contained in a gas phase or a liquid phase, and the investment cost is increased for the treatment of hydrochloric acid waste liquid or the combustion treatment of non-condensable gas. In addition, because oxygen-containing compounds such as air and water are directly introduced, the safety problems such as explosion limit exist for inflammable and explosive components such as H 2, silane/chlorosilane/siloxane/chloromethane and the like, and therefore, a large amount of air or water is required to be introduced to dilute H 2 or silane/siloxane beyond the explosion limit range, for example, H 2 is less than 4%, the energy consumption is further increased, and the effective components such as H 2 and the like can not be recovered.
SiC is a third generation semiconductor material, and has a wide application prospect in the future. However, due to the high cost, the silicon carbide material still cannot compete with the traditional Si-based material in many fields, wherein a large amount of ultra-high purity H 2, silane/chlorosilane and ethylene which are consumed in the SiC-CVD epitaxial process are high in preparation cost, and cannot be recycled from tail gas.
Disclosure of Invention
The invention aims at: the method for recycling and recycling the tail gas FTrPSA of the chloro-SiC-CVD epitaxial process by reacting ethylene with silane is provided, so that the problems that a large amount of ultra-high-purity H 2, silane/chlorosilane and ethylene which are consumed in the conventional SiC-CVD epitaxial process are high in preparation cost and cannot be recycled from the tail gas are solved.
The technical scheme adopted by the invention is as follows:
The method for recycling and recycling tail gas FTrPSA of the chlorine-based SiC-CVD epitaxial process by reacting ethylene with silane comprises the following steps:
Step 1, pretreatment of raw gas, namely sequentially removing dust, particles, oil mist, part of high-chlorosilane, high-chloralkane and high-hydrocarbon impurities;
Step 2, shallow cold chlorosilane is absorbed, purified raw material gas from a pretreatment process enters from the bottom of a shallow cold chlorosilane absorption tower, chlorosilane liquid is adopted as an absorbent, reverse mass transfer exchange is carried out on the raw material gas and the purified raw material gas downwards by spraying from the top of the shallow cold chlorosilane absorption tower, absorption liquid flowing out from the bottom of the shallow cold chlorosilane absorption tower enters a subsequent multistage evaporation/compression/condensation process, non-condensable gas 1 flows out from the top of the absorption tower, and after compression, condensation and gas-liquid separation, the formed non-condensable gas 2 enters the next process, namely shallow cold pressure swing adsorption concentration, and the formed liquid is conveyed to a subsequent HCl refining process;
Step 3, shallow-cooling pressure swing adsorption concentration, namely, enabling the non-condensable gas 2 to enter a shallow-cooling pressure swing adsorption concentration process consisting of more than 4 adsorption towers, adopting vacuumizing for desorption, enabling non-adsorbed phase hydrogen-rich gas to flow out of the top of the adsorption tower in an adsorption state, directly entering adsorption purification, enabling the non-adsorbed phase hydrogen-rich gas to flow out of the bottom of the adsorption tower in a desorption vacuumizing state, desorbing the gas from the adsorption phase flowing out of the bottom of the adsorption tower in a desorption vacuumizing state, taking the gas as concentrated gas, carrying out cold and heat exchange, and returning the concentrated gas to be mixed with the non-condensable gas 1 to enter compression, condensation and gas-liquid separation of the shallow-cooling chlorosilane absorption process;
step 4, adsorption purification, namely, carrying out precise filtration on the hydrogen-rich gas, and then enabling the hydrogen-rich gas to enter an adsorption purification process consisting of 2 or 3 adsorption towers to form purified hydrogen-rich gas;
step 5, hydrogen is extracted by pressure swing adsorption, purified hydrogen rich gas from an adsorption purification process enters a multi-tower pressure swing adsorption hydrogen purification process consisting of at least 4 towers, at least one adsorption tower is in an adsorption step, the rest adsorption towers are in a desorption regeneration step, the formed non-adsorption phase gas is ultra-high purity hydrogen, a flushing or flushing and vacuumizing mode is adopted during desorption, desorption gas is methane rich gas, and the methane rich gas can be directly used as fuel gas to return to a cold and heat exchange system for tail gas recovery, or enter a membrane separation system for further recovery of H 2;
step 6, purifying the hydrogen, namely directly reducing the pressure of the ultra-high purity hydrogen from the pressure swing adsorption hydrogen extraction process to the pressure required by hydrogen for the SiC-CVD epitaxial process at the temperature of 50-500 ℃ or through a reducing valve, entering the hydrogen purification process, removing trace impurities, and obtaining a final electronic grade hydrogen product, and storing or directly returning the final electronic grade hydrogen product to a working section of the hydrogen required by the SiC-CVD epitaxial process;
Step 7, multistage evaporation/compression/condensation, wherein the absorption liquid from the shallow-cooling chlorosilane absorption process enters multistage evaporation and then enters a condenser to obtain gas-phase crude HCl gas, the crude HCl liquid formed after condensation is mixed with the liquid formed after compression, condensation and gas-liquid separation from the shallow-cooling chlorosilane absorption process, the formed crude HCl mixed liquid enters the next process, namely HCl refining, crude chlorosilane liquid flows out of the condenser and enters the subsequent shallow-cooling distillation of chlorosilane;
Step 8, refining the HCl, namely enabling the crude HCl mixed solution to enter an HCl refining process consisting of an HCl rectifying tower and a vacuum rectifying tower, enabling HCl product gas to flow out from the top of the rectifying tower, returning to an epitaxial process for recycling, enabling bottom effluent to enter the vacuum rectifying tower, enabling top gas flowing out from the top of the vacuum rectifying tower to be directly sent to an incinerator for incineration treatment and discharge, or sending out heavy components flowing out from the bottom of the vacuum rectifying tower to be extracted into VCM and chloralkane, or returning to a multistage evaporation/compression/condensation process, or returning to a next process, namely a shallow cold rectifying process in chlorsilane;
Step 9, shallow cold rectification is carried out in the chlorosilane, crude chlorosilane liquid from a multistage evaporation/compression/condensation process is mixed with recombinant fluid from the bottom of a vacuum rectification column of an HCl refining process, then enters the shallow cold rectification process in the chlorosilane, non-condensable gas 3 flows out from the top of the rectification column, and chlorosilane liquid flowing out from the bottom of the rectification column is used as an absorbent and returned to the shallow cold chlorosilane absorption process for recycling;
Step 10, separating ethylene/silane, namely, enabling non-condensable gas 3 to enter a rectifying tower in an ethylene/silane separation process, enabling silane-rich gas to flow out from the top of the rectifying tower, enabling ethylene-rich fluid flowing out from the bottom of the rectifying tower to enter a subsequent ethylene refining process;
Step 11, purifying silane, namely enabling silane-enriched gas to enter a silane purification process consisting of two rectifying towers, wherein the silane purification process comprises a rectifying tower 1, enabling low-boiling-point hydrogen-enriched non-condensable gas 4 to flow out of the top of the rectifying tower 1, mixing the low-boiling-point hydrogen-enriched non-condensable gas with shallow-cooling pressure swing adsorption-enriched gas after cold-heat exchange, further recycling hydrogen, enabling the bottom effluent of the rectifying tower 1 to enter a rectifying tower 2, enabling SiH 4 flowing out of the top of the rectifying tower 2 to be more than 95%, enabling the SiH 4 to be directly or further purified and then be used as raw material gas required by an SiC-CVD epitaxial process for recycling, enabling a part of heavy component flow flowing out of the bottom of the rectifying tower 2 to return to an ethylene/silane separation process for further recycling effective components, and enabling a part of the recovered effective components to be directly discharged after treatment;
And 12, refining ethylene, namely enabling ethylene-rich fluid from the bottom of a rectifying tower in an ethylene/silane separation process to flow out of ethylene product gas from the top of the rectifying tower through the ethylene rectifying tower, or returning the ethylene-rich fluid to a SiC-CVD epitaxial process, and discharging the recombinant fluid flowing out of the bottom of the rectifying tower after treatment or using the recombinant fluid as fuel gas.
Specific:
Step 1, pretreatment of raw gas, namely sequentially removing dust, particles, oil mist, part of high-chlorosilane, high-chloralkane and high-hydrocarbon impurities; raw material gas, which takes ethylene (C 2H4) as a main carbon (C) source, silane (SiH 4) as a silicon (Si) source and hydrogen chloride (HCl) are added to carry out Chemical Vapor Deposition (CVD) to prepare tail gas in a silicon carbide (SiC) based chlorine-based epitaxial growth process, wherein the main composition of the raw material gas is hydrogen (H 2）、HCl、C2H4, silane (SiH 4)/chlorosilane (SiHmCln), a small amount of methane (CH 4), chloroalkane (CHmCln), chloroolefin (VCM), and trace amounts of carbon monoxide (CO), carbon dioxide (CO 2), light hydrocarbon components of ethane and carbon more than two and high hydrocarbon (C 2+), water (H 2 O) and silicon dioxide (SiO 2) and Si/C fine particles, the pressure is normal pressure or low pressure, the temperature is normal temperature;
step 2, pressurizing the purified raw material gas from the pretreatment process to 1.0-2.0 MPa, carrying out cold-heat exchange to 5-20 ℃, then entering from the bottom of a shallow cooling chlorosilane absorption tower, adopting chlorosilane liquid as an absorbent, spraying from the top of the shallow cooling chlorosilane absorption tower, carrying out reverse mass transfer exchange with the purified raw material gas, flowing out an absorption liquid enriched with chlorosilane and most HCl from the bottom of the shallow cooling chlorosilane absorption tower, entering a subsequent multistage evaporation/compression/condensation process, simultaneously outputting a small amount of residual particles, high chlorosilane, high chloralkane and high hydrocarbon impurities from the bottom of the tower for environmental protection treatment, flowing out non-condensable gas 1 from the top of the absorption tower, carrying out compression, condensation and gas-liquid separation, and then entering the formed non-condensable gas 2 into the next process, namely shallow cooling pressure swing adsorption concentration, and conveying the formed liquid to the subsequent HCl refining process;
Step 3, shallow cold pressure swing adsorption concentration, namely, enabling non-condensable gas 2 formed after compression, condensation and gas-liquid separation from a shallow cold chlorosilane absorption process to enter a shallow cold pressure swing adsorption concentration process consisting of more than 4 adsorption towers, wherein the adsorption temperature is 5-20 ℃, the adsorption pressure is 1.0-2.0 MPa, vacuumizing is adopted for desorption, enabling non-adsorbed phase hydrogen-rich gas to flow out of the top of the adsorption tower in an adsorption state to directly enter the next process, namely, adsorbing and purifying, enabling the adsorbed phase flowing out of the bottom of the adsorption tower in a desorption vacuumizing state to be desorbed, enabling the condensed gas to be used as concentrated gas, and returning to be mixed with the non-condensable gas 1 after cold heat exchange to enter the compression, condensation and gas-liquid separation of the shallow cold chlorosilane absorption process, and further recycling effective components;
Step 4, adsorption purification, namely, carrying out precise filtration on hydrogen-rich gas from a shallow-cooling pressure swing adsorption concentration process, then, carrying out an adsorption purification process consisting of 2 or 3 adsorption towers, carrying out adsorption at an operating temperature of 5-30 ℃ and an operating pressure of 1.0-2.0 MPa, further purifying and removing a small amount of SiH 4、HCl、C2H4、C2+、CO2 and chlorosilane/chloralkene/chloralkane in the hydrogen-rich gas to form purified hydrogen-rich gas, and carrying out the next process, namely, pressure swing adsorption hydrogen extraction;
Step 5, pressure swing adsorption hydrogen extraction, namely, purifying hydrogen-rich gas from an adsorption purification process, directly or after being pressurized to 1.0-3.0 MPa, entering a multi-tower pressure swing adsorption hydrogen purification process consisting of at least 4 towers, wherein the operating pressure of the adsorption towers is 2.0-3.0 MPa, the operating temperature is 5-40 ℃, at least one adsorption tower is in an adsorption step, the rest adsorption towers are in a desorption regeneration step, the formed non-adsorption phase gas is ultra-high purity hydrogen with the purity of more than or equal to 99.999-99.9999% (v/v), entering the next process, namely, hydrogen purification, wherein an adsorbent in the pressure swing adsorption hydrogen extraction process adopts one or more combinations of activated alumina, silica gel, activated carbon, aluminum silicate molecular sieve and carbon molecular sieve, and is subjected to flushing or flushing and vacuumizing to desorption to form methane-rich gas, and can be directly used as fuel gas to return to a cold-heat exchange system for tail gas recovery, or enter a membrane separation system for further recovery of H 2;
Step 6, purifying the hydrogen, namely purifying the ultra-high purity hydrogen from a pressure swing adsorption hydrogen extraction process, or directly carrying out heat exchange after passing through an intermediate product storage tank, directly reducing the pressure to the pressure required by hydrogen for an SiC-CVD (semiconductor industry) epitaxial process at 50-500 ℃, or directly reducing the pressure through a reducing valve, entering a hydrogen purification process coupled by a metal getter or a palladium membrane-metal getter, purifying the hydrogen at the operating temperature of 50-500 ℃ and the operating pressure of normal pressure or the pressure required by hydrogen used in the SiC-CVD epitaxial process, removing trace impurities to obtain a final electronic grade hydrogen product, wherein the purity of the final electronic grade hydrogen product reaches the product standard of electronic grade hydrogen specified by the national and international semiconductor industry association (SEMI), the purity of the hydrogen is more than or equal to 7-8N grade, and is subjected to heat exchange temperature reduction or pressure reduction, or is sent into the electronic grade hydrogen product tank for storage, or is directly returned to a section requiring hydrogen for the SiC-CVD epitaxial process through a hydrogen product buffer tank, wherein the operating temperature of the hydrogen purification process is determined by the process of the metal getter or the palladium membrane, the service life of the metal getter or the palladium membrane is at least 2 years; the yield of the electronic grade hydrogen product is 75-85%;
Step 7, multistage evaporation/compression/condensation, namely enabling the absorption liquid from the shallow cooling chlorosilane absorption process to enter multistage evaporation, directly or decompressing to 0.6-1.0 MPa, then enabling the absorption liquid to enter a condenser, obtaining gas-phase crude HCl gas from the absorption liquid, mixing the crude HCl liquid formed after condensation with the liquid formed after compression, condensation and gas-liquid separation from the shallow cooling chlorosilane absorption process, enabling the formed crude HCl mixed liquid to enter the next process, namely HCl refining, enabling the crude chlorosilane liquid to flow out of the condenser, and enabling the crude HCl liquid to enter the subsequent shallow cooling rectification of chlorosilane;
HCl refining, namely mixing crude HCl liquid from a multistage evaporation/compression/condensation process with liquid obtained by compression condensation and gas-liquid separation in a shallow cooling chlorosilane absorption process to form crude HCl mixed liquid, and entering an HCl refining process consisting of an HCl rectifying tower and a vacuum rectifying tower, wherein the operating pressure of the rectifying tower is 0.3-1.0 MPa, the operating temperature is 60-120 ℃, the operating pressure of the vacuum rectifying tower is-0.08-0.1 MPa, the operating temperature is 60-120 ℃, HCl product gas with the purity of more than 99.9% flows out of the top of the rectifying tower, the HCl product gas returns to an epitaxial process for recycling, the tower top gas flowing out of the top of the rectifying tower mainly contains VCM and chloralkane, or directly enters an incinerator for incineration treatment and discharge, or is sent out to extract VCM and chloralkane, heavy components flowing out of the bottom of the vacuum rectifying tower, or returns to the multistage evaporation/compression/condensation process, or returns to the shallow cooling rectifying process in the next process;
Step 8, refining HCl, namely mixing crude HCl liquid from a multistage evaporation/compression/condensation process with liquid obtained by compression condensation and gas-liquid separation in a shallow cold chlorosilane absorption process to form crude HCl mixed liquid, and entering an HCl refining process consisting of an HCl rectifying tower and a vacuum rectifying tower, wherein the operating pressure of the rectifying tower is 0.3-1.0 MPa, the operating temperature is 60-120 ℃, the operating pressure of the vacuum rectifying tower is-0.08-0.1 MPa, the operating temperature is 60-120 ℃, HCl product gas with the purity of more than 99.9% flows out of the top of the rectifying tower, returns to an epitaxial process for recycling, enters a vacuum rectifying tower from a tower bottom effluent, mainly contains VCM and chloralkane from the top of the vacuum rectifying tower, or directly enters an incinerator for incineration treatment and discharge, or sends out to extract the VCM and chloralkane, and heavy components flowing out of the bottom of the vacuum rectifying tower, or returns to the multistage evaporation/compression/condensation process, or returns to the shallow cold rectifying process in the next process-chlorosilane;
Step 9, shallow cold rectification in chlorosilane, namely, mixing crude chlorosilane liquid from a multistage evaporation/compression/condensation process with recombinant fluid from the bottom of a vacuum rectification column of an HCl refining process, and then entering the shallow cold rectification process in chlorosilane, wherein the operating temperature is-35-10 ℃, the operating pressure is 0.6-2.0 MPa, non-condensable gas 3 flowing out of the top of a rectification column enters the next process, namely, an ethylene/silane separation process, and the chlorosilane liquid flowing out of the bottom of the rectification column is returned to the shallow cold chlorosilane absorption process as an absorbent for recycling
Step 10, separating ethylene/silane, namely, feeding non-condensable gas 3 from a shallow cold rectifying process in chlorosilane into a rectifying tower in the ethylene/silane separating process, enabling the operating temperature to be-10-60 ℃ and the operating pressure to be 0.6-2.0 MPa, enabling silane-rich gas to flow out from the top of the rectifying tower, feeding into a next process, namely, silane purification, and feeding ethylene-rich fluid flowing out from the bottom of the rectifying tower into a subsequent ethylene refining process;
Step 11, purifying silane, namely, introducing silane-rich gas from an ethylene/silane separation process into a silane purification process consisting of two rectifying towers, wherein the operating temperature of the rectifying tower 1 is-35 to-30 ℃, the operating pressure is 2.0-2.5 MPa, low-boiling-point hydrogen-rich non-condensable gas 4 flows out of the top of the rectifying tower 1, the low-boiling-point hydrogen-rich non-condensable gas 4 is mixed with shallow cooling/shallow cooling pressure swing adsorption-enriched hydrogen-rich gas after cold exchange, hydrogen is further recovered, the bottom effluent of the rectifying tower 1 enters the rectifying tower 2 again, the operating temperature is-37 to-35 ℃, the operating pressure is 1.6-2.0 MPa, siH 4 with the purity of 99.99% or more flows out of the top of the rectifying tower 2, the yield is more than 95%, and the SiH 4% or more is directly purified by a SiH 4 metal getter purifier (with the purity of 99.999%) and is used as raw gas for recycling needed by SiC-CVD epitaxial preparation, and a part of the heavy component material flow flowing out of the bottom of the rectifying tower 2 is returned to the ethylene/silane separation process for further recovery of effective components, and a part of the active components is discharged after treatment;
And 12, refining ethylene, namely, directly or through an ethylene rectifying tower with the temperature of 20-120 ℃ and the pressure of 0.6-2.0 MPa, wherein an ethylene product gas flows out from the top of the rectifying tower through cold and heat exchange, the purity is more than or equal to 99.99%, the yield is more than or equal to 95%, and a recombinant fluid containing C 2+/CO2 flows out from the bottom of the rectifying tower is discharged after being treated or used as fuel gas.
In the technical scheme of the application, various conventional separation methods including adsorption, rectification, absorption and the like are coupled to realize the recovery of active components (H 2、HCl、SiH4、C2H4 and chlorosilane) in the pressure swing adsorption (FTrPSA) of the chloro-SiC-CVD epitaxy process Cheng Weiqi Quan Wencheng and the recycling of the active components (H 2、HCl、SiH4、C2H4 and chlorosilane) as CVD feed gas to a chloro-SiC epitaxial furnace or a tail gas recovery system, and the application can recover H 2、HCl、SiH4、C2H4 from the tail gas of the chloro-SiC-CVD epitaxy process based on the reaction of ethylene and silane and recycle the tail gas as raw material to the chloro-SiC-CVD epitaxy process, thereby realizing the recycling of the whole components of the tail gas, reducing the tail gas emission and compensating the blank of the tail gas treatment technology of the chloro-SiC epitaxy process.
Preferably, the raw gas comprises waste gas or tail gas containing hydrogen, hydrogen chloride, silane, ethylene, chlorosilane and chloroolefin (VCM) as main components generated in the rest of the semiconductor process.
Preferably, in the shallow cold chlorosilane absorption process, under the working condition that the concentration of HCl and chlorosilane/chloroolefin contained in the purified raw material gas is higher, a secondary medium temperature chlorosilane absorption process is additionally arranged, namely, non-condensable gas 1 from the shallow cold chlorosilane absorption process is directly or pressurized to 0.2-1.0 MPa after being compressed, condensed and gas-liquid separated, and enters from the bottom of the additionally arranged secondary medium temperature chlorosilane absorption process after cold and heat exchange to 60-120 ℃, a mixed liquid containing chlorosilane/HCl is adopted as an absorbent, the secondary medium temperature chlorosilane absorption tower is sprayed from the top of the secondary medium temperature chlorosilane absorption tower and then carries out reverse mass transfer exchange with the non-condensable gas 1 ', the absorption liquid enriched with chlorosilane and HCl flows out from the bottom of the absorption tower, the non-condensable gas 2 flows out from the bottom of the absorption tower and then enters into the next step of multi-stage evaporation/compression/condensation process, or the formed non-condensable gas 2' enters into the next step of shallow cold pressure swing adsorption concentration after being compressed, condensed and gas-liquid separation, or the shallow cold swing adsorption concentration operation temperature range is expanded to 20 ℃ to enable the energy-saving operation temperature range of the follow-up operation of the secondary medium temperature chlorosilane absorption process to be more convenient, and the HCl can be recovered from the top of the absorption tower, and the HCl can be further recovered from the secondary medium temperature absorption process, and the HCl can be recovered and the product is more conveniently and recovered.
Preferably, the liquid generated by condensing the tower top gas flowing out of the HCl rectifying tower in the HCl refining process is directly used as reflux or is mixed with the crude HCl mixed solution and then returned into the HCl rectifying tower, and the non-condensable gas is used as HCl product gas, so that the purity is more than 99.99%.
Preferably, in the shallow-cooling pressure swing adsorption concentration process, non-condensable gas 2 formed by compression, condensation and gas-liquid separation in the shallow-cooling chlorosilane absorption process or the secondary medium-temperature chlorosilane absorption process enters the shallow-cooling pressure swing adsorption concentration process in a blower pressurization mode, wherein the process consists of a two-stage PSA system, namely, the non-condensable gas 2 is pressurized to 0.2-0.3 MPa, enters from the bottom of a 1-stage PSA adsorption tower, and the non-adsorbed phase gas flowing out from the top of the 1-stage PSA adsorption tower is hydrogen-rich gas and enters the next process, namely adsorption purification; the desorption gas desorbed (reversely discharged, flushed or vacuumized) from the bottom of the 1-section PSA adsorption tower is pressurized and sent to the bottom of a second PSA adsorption tower (2-section PSA adsorption tower), enriched non-adsorption phase hydrogen-enriched mixed intermediate gas flows out from the top of the 2-section PSA adsorption tower, methane hydrogen gas is further recovered by feeding gas, namely non-condensable gas 2, to the 1-section PSA adsorption tower, adsorption phase gas flowing out from the bottom of the 2-section PSA adsorption tower is concentrated gas containing SiH 4, chlorosilane, C 2H4, VCM and H 2, and the concentrated gas is mixed with the non-condensable gas 1 and returned to compression, condensation and gas-liquid separation of the shallow cold chlorosilane absorption process, and effective components are further recovered.
Preferably, the desorption gas of the pressure swing adsorption hydrogen extraction process is compressed to a pressure of more than 1.5MPa and then sent to a first-stage or second-stage membrane separation hydrogen recovery system, hydrogen-enriched permeate gas flows out from the permeate side, or is mixed with hydrogen-enriched gas from the shallow cold pressure swing adsorption concentration process to enter the adsorption purification process, or is mixed with purified hydrogen-enriched gas to enter the pressure swing adsorption hydrogen extraction process, H 2 is further recovered, the product gas yield is more than 90%, methane-enriched gas flows out from the non-permeate side, or is directly used as fuel gas, or is subjected to low-temperature rectification to obtain ultra-pure methane byproduct external transportation, and non-condensable gas obtained from the low-temperature rectification is returned to the pressure swing adsorption hydrogen extraction process, so that the yield of the H 2 product is more than 95%.
Preferably, the shallow cold rectifying process in chlorosilane is composed of rectifying towers 1 and-2, crude chlorosilane liquid flowing out from the multistage evaporation/compression/condensation process is mixed with recombinant fluid flowing out from the bottom of a vacuum rectifying tower in the HCl refining process, the mixture enters a middle-shallow cold rectifying tower 1 with the operating temperature of minus 35 ℃ to minus 10 ℃ and the operating pressure of 1.0-2.5 MPa, non-condensable gas 3' of light components flowing out from the top of the rectifying tower 1 is mainly H 2 and a small amount of CH 4, or the mixture is mixed with purified hydrogen-rich gas from the adsorption purification process by a cold heat exchanger to the temperature of 5-40 ℃ and then enters a pressure swing adsorption hydrogen extraction process to further recover H 2 or/and CH 4, or/and the non-condensable gas 2 formed by compression, condensation and gas-liquid separation of the shallow cold chlorosilane absorption process is mixed and then enters a shallow cold pressure swing adsorption concentration process to further recover H 2, the yield of the product gas is further improved, heavy component fluid flowing out from the bottom of the rectifying tower 1 enters the shallow cold rectifying tower 2 in chlorosilane with the operating temperature of minus 35 to minus 10 ℃ and the operating pressure of 1.0-2.5 MPa, chlorosilane liquid flows out from the bottom of the shallow cold rectifying tower and returns to the shallow cold chlorosilane absorption process as an absorbent, or is mixed with HCl to be recycled as an absorbent of the secondary medium-temperature chlorosilane absorption process, noncondensable gas 3 flowing out from the top of the rectifying tower 2 enters the next process, namely an ethylene/silane separation process, so that the subsequent silane purification process only consists of one rectifying tower, siH 4 with the purity of more than or equal to 99.99% flows out from the top of the rectifying tower, no noncondensable gas 4 appears, and the ethylene/silane separation load is reduced.
Preferably, the silane purification process adopts cryogenic separation, namely a low-temperature rectifying tower replaces the silane purification process consisting of two towers, the operation temperature of the cryogenic separation is-180 to-110 ℃, siH 4 liquid with the purity of more than 99.99% directly flows out from the bottom of the low-temperature rectifying tower, non-condensable gas 4 escapes from the top of the rectifying tower, and the non-condensable gas 4 is mixed with hydrogen-rich gas from a shallow-cooling pressure swing adsorption concentration process after cold and heat exchange and pressurization, and then enters an adsorption purification process to further recover effective components.
Preferably, the rectifying tower 2 in the silane purifying process can be replaced by a pressure swing adsorption tower, that is, fluid flowing out from the bottom of the rectifying tower 1 in the silane purifying process is subjected to cold and heat exchange to 20-40 ℃ and reduced pressure to less than 1.0MPa, and then is sent to the pressure swing adsorption tower which is 20-40 ℃ in operation temperature and less than 1.0MPa in operation pressure and consists of at least 2 adsorption towers, one or more combined adsorbents of diatomite, silica gel, active carbon and molecular sieves are filled in the adsorption towers, silane (SiH 4) product gas with purity of more than or equal to 99.99% flows out from the top of the adsorption tower, the yield is more than or equal to 90-95%, the product gas is directly purified or further purified by an SiH 4 metal getter purifier (purity of more than or equal to 99.999%) and then is recycled as raw material gas required by SiC-CVD epitaxial process, and the desorption gas which is desorbed by vacuum pumping and flows out from the bottom of the adsorption tower is mixed with non-condensable gas 3 generated in the shallow cold rectifying process in the chlorosilane, and then returns to enter ethylene/silane separation step after exchange and pressure regulation, and further the product gas is subjected to recovery to the yield of 4% to corresponding recovery of more than or equal to 4% of heat and cold and heat.
Preferably, the pressure change of the pressure swing adsorption towers in the processes of shallow-cooling pressure swing adsorption concentration, pressure swing adsorption hydrogen extraction, adsorption purification and silane purification is controlled by a program control valve and a regulating valve on a pipeline connected between the adsorption towers under the operation condition that the adsorption pressure is more than or equal to 0.6MPa, so that slow and uniform control is realized, and the air flow scouring the adsorption tower bed and the pulverization of the adsorbent caused by overlarge system pressure change is prevented, so that the operation of the process system is stable and safe.
The full-temperature pressure swing adsorption (English full name: full Temperature Range-Pressure Swing Adsorption, abbreviated as FTrPSA) is a method based on Pressure Swing Adsorption (PSA) and capable of being coupled with various separation technologies, and utilizes the adsorption separation coefficient and the physical and chemical properties of different material components under different pressures and temperatures, and adopts the cyclic operation that adsorption and desorption are easy to match and balance in the middle-temperature or shallow-cold pressure swing adsorption process to separate and purify main effective components (H 2 (purity is greater than or equal to 99.9995% (v/v)) and SiH 4 (purity is greater than or equal to 99.99%), and meanwhile, ethylene (greater than or equal to 99.9%), HCl (greater than or equal to 99.9-99.99%) and chlorosilane can be produced as byproducts.
In summary, due to the adoption of the technical scheme, the beneficial effects of the invention are as follows:
1. In the invention, H 2、HCl、SiH4、C2H4 can be recovered from the tail gas of the chlorine-based SiC-CVD epitaxial process based on the reaction of ethylene and silane, and the recovered H 2、HCl、SiH4、C2H4 is returned to the chlorine-based SiC-CVD epitaxial process as a raw material for recycling, thereby realizing the recycling of the whole components of the tail gas, reducing the emission of the tail gas and making up the blank of the tail gas treatment technology of the SiC chlorine-based epitaxial process;
2. The invention utilizes the physical chemistry and relative separation coefficient characteristics of tail gas components, adopts organic coupling of separation methods such as absorption, condensation, adsorption and rectification, extracts effective component H 2/HCl/SiH4/C2H4 in sequence and can return to the chlorine-based epitaxy process for recycling, and meanwhile, byproduct chlorosilane can be used as an absorbent for recycling in a tail gas recovery system, thereby solving the technical bottleneck that H 2、HCl、SiH4、C2H4 is difficult to recover and recycle simultaneously in the traditional adsorption separation process;
3. The invention realizes the recycling of main effective components (H 2、HCl、SiH4/C2H4 is the main component) without bringing the SiC-CVD chlorine-based epitaxial process and sensitive oxygen-containing compounds thereof, especially O2, H 2 O, CO and the like into the system, so that the whole recycling process is stable, and the influence on the SiC epitaxial quality is reduced to zero degree;
4. Aiming at the fluctuation of the concentration of byproduct chlorosilane/HCl caused by the fluctuation of the epitaxial chlorination amount and the epitaxial operation, the invention adopts the processes of primary shallow cooling, secondary medium-temperature chlorosilane differential temperature absorption and different absorbents, thereby greatly improving the tail gas recovery efficiency and reducing the load and difficulty of the subsequent extraction of hydrogen chloride, silane and ethylene;
5. The invention adopts the coupling of the shallow cooling chlorosilane absorption and the shallow cooling PSA concentration process, the complex tail gas composition is cut into high boiling point and low boiling point components by taking HCl component as main cutting point, after absorption, multistage evaporation, compression, condensation and gas-liquid separation, HCl is firstly high boiling point component and then low boiling point component, thus avoiding the increase of the separation difficulty of silane, methane, hydrogen, CO and other low boiling point components, simultaneously preventing HCl and ethylene from reacting at high temperature to generate excessive VCM which is useless for the epitaxial process and influencing the yield of HCl/ethylene;
6. The invention utilizes the difference of the operation temperature of each procedure, and makes full use of the cold and heat quantity of the whole operation system by arranging a reasonable cold and heat quantity exchange system;
7. The invention ensures that the recovery rate of recovered H 2 is more than 75 percent and can reach more than 95 percent at maximum by coupling the non-condensable gas of the procedures of light cold or medium temperature absorption, medium and light cold rectification, multistage evaporation/compression/condensation and the procedures of light cold/light cold pressure swing adsorption concentration, adsorption purification and pressure swing adsorption hydrogen extraction, and the recovery rates of HCl, silane and ethylene are more than 90 percent.
Drawings
FIG. 1 is a schematic flow chart of an embodiment 1 of the present invention;
FIG. 2 is a schematic flow chart of embodiment 2 of the present invention;
FIG. 3 is a schematic flow chart of embodiment 3 of the present invention;
FIG. 4 is a schematic flow chart of embodiment 4 of the present invention;
FIG. 5 is a schematic flow chart of embodiment 5 of the present invention;
fig. 6 is a schematic flow chart of embodiment 6 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Example 1
As shown in fig. 1, the method for recycling and recycling tail gas FTrPSA of a chloro-SiC-CVD epitaxial process in which ethylene reacts with silane comprises the following steps:
Step 1, pretreatment of raw gas, namely sequentially removing dust, particles, oil mist, part of high-chlorosilane, high-chloralkane and high-hydrocarbon impurities; raw material gas, which takes ethylene (C 2H4) as a main carbon (C) source, silane (SiH 4) as a silicon (Si) source and hydrogen chloride (HCl) are added to carry out Chemical Vapor Deposition (CVD) to prepare tail gas in a silicon carbide (SiC) based chlorine-based epitaxial growth process, wherein the main composition of the raw material gas is hydrogen (H 2）、HCl、C2H4, silane (SiH 4)/chlorosilane (SiHmCln), a small amount of methane (CH 4), chloroalkane (CHmCln), chloroolefin (VCM), and trace amounts of carbon monoxide (CO), carbon dioxide (CO 2), light hydrocarbon components of ethane and carbon more than two and high hydrocarbon (C 2+), water (H 2 O) and silicon dioxide (SiO 2) and Si/C fine particles, the pressure is normal pressure or low pressure, the temperature is normal temperature;
Step 2, shallow cold chlorosilane is absorbed, purified raw material gas from a pretreatment process is pressurized to 1.0-2.0 MPa, and enters from the bottom of a shallow cold chlorosilane absorption tower after cold and heat exchange to 5-20 ℃, chlorosilane liquid is adopted as an absorbent, reverse mass transfer exchange is carried out on the raw material gas and the raw material gas after spraying from the top of the shallow cold chlorosilane absorption tower, absorption liquid enriched with chlorosilane and most of HCl flows out from the bottom of the shallow cold chlorosilane absorption tower, the raw material gas enters a subsequent multistage evaporation/compression/condensation process, meanwhile, a small amount of residual particles, high chlorosilane, high chloralkane and high hydrocarbon impurities flowing out from the bottom of the tower are output for environmental protection treatment, non-condensable gas 1 flows out from the top of the absorption tower, the formed non-condensable gas 2 enters a shallow cold pressure swing adsorption concentration process after compression, condensation and gas-liquid separation, and the formed liquid is conveyed to an HCl rough distillation process;
Step 3, shallow cold pressure swing adsorption concentration, namely, enabling non-condensable gas 2 formed after compression, condensation and gas-liquid separation from a shallow cold chlorosilane absorption process to enter a shallow cold pressure swing adsorption concentration process consisting of 5 adsorption towers, wherein the adsorption temperature is 5-20 ℃, the adsorption pressure is 1.0-2.0 MPa, vacuumizing is adopted for desorption, enabling non-adsorbed phase hydrogen-rich gas to flow out of the top of the adsorption tower in an adsorption state, directly entering an adsorption purification process, enabling the adsorbed phase desorption gas flowing out of the bottom of the adsorption tower in the desorption vacuumizing state to serve as concentrated gas, and returning to be mixed with the non-condensable gas 1 after cold and heat exchange to enter compression, condensation and gas-liquid separation of the shallow cold chlorosilane absorption process, so as to further recover effective components;
Step 4, adsorption purification, namely, carrying out precise filtration on hydrogen-rich gas from a shallow-cooling pressure swing adsorption concentration process, then, carrying out adsorption purification process consisting of 2 adsorption towers, carrying out adsorption at an operating temperature of 5-30 ℃ and an operating pressure of 1.0-2.0 MPa, further purifying and removing a small amount of SiH 4、HCl、C2H4、C2+、CO2 and chlorosilane/chloroalkene/chloroalkane to form purified hydrogen-rich gas, and carrying out pressure swing adsorption hydrogen extraction process;
Step 5, pressure swing adsorption hydrogen extraction, namely, the purified hydrogen rich gas from the adsorption purification step enters a pressure swing adsorption hydrogen purification step consisting of 5 towers, the operating pressure of the adsorption towers is 2.0-3.0 MPa, the operating temperature is 5-40 ℃, one adsorption tower is in an adsorption step, the other adsorption towers are in a desorption regeneration step, the formed non-adsorption phase gas is ultra-high purity hydrogen with the purity of more than or equal to 99.999-99.9999% (v/v), the ultra-high purity hydrogen enters a hydrogen purification step, the adsorbent of the pressure swing adsorption hydrogen extraction step adopts various combinations of activated alumina, silica gel, activated carbon, aluminum silicate molecular sieves and carbon molecular sieves, and the desorption gas is methane rich gas in a flushing and vacuumizing mode during desorption, and can be directly used as fuel gas to return to a cold and hot exchange system for tail gas recovery;
Step 6, purifying hydrogen, namely heating ultra-high purity hydrogen from a pressure swing adsorption hydrogen extraction process to 400-450 ℃ through heat exchange, then entering a hydrogen purification process consisting of a metal getter, purifying under the conditions that the operating temperature is 400-450 ℃ and the operating pressure is 2.0-3.0 MPa, removing trace impurities, and obtaining a final electronic grade hydrogen product, wherein the purity of the final electronic grade hydrogen product reaches the product standard of electronic grade hydrogen specified by national semiconductor industry association (SEMI), the purity of the hydrogen is 7-8N or more, and directly returning the hydrogen to a section requiring hydrogen in a SiC-CVD (chemical vapor deposition) epitaxial process through heat exchange cooling and a hydrogen product buffer tank, wherein the service life of the metal getter is longer than 2 years, regeneration is not needed, and the yield of the obtained electronic grade hydrogen product is higher than 85%;
Step 7, multistage evaporation/compression/condensation, wherein the absorption liquid from the shallow cooling chlorosilane absorption process enters multistage evaporation, is depressurized to 0.6-1.0 MPa, and then enters a condenser to obtain gas phase crude HCl gas, the crude HCl liquid formed after condensation is mixed with the liquid formed after compression, condensation and gas-liquid separation from the shallow cooling chlorosilane absorption process, the formed crude HCl mixed liquid enters an HCl refining process, and the crude chlorosilane liquid flows out of the condenser to enter chlorosilane for shallow cooling rectification;
Step 8, refining HCl, namely mixing crude HCl liquid from a multistage evaporation/compression/condensation process with liquid obtained by compression condensation and gas-liquid separation in a shallow cooling chlorosilane absorption process to form crude HCl mixed liquid, and entering an HCl refining process consisting of an HCl rectifying tower and a vacuum rectifying tower, wherein the operating pressure of the rectifying tower is 0.3-1.0 MPa, the operating temperature is 60-120 ℃, the operating pressure of the vacuum rectifying tower is-0.08-0.1 MPa, the operating temperature is 60-120 ℃, HCl product gas with the purity of more than 99.9% flows out of the top of the rectifying tower and returns to an epitaxial process for recycling, tower top gas flowing out of the top of the rectifying tower mainly contains VCM and chloralkane, the tower top gas is directly burnt and discharged from the bottom of the vacuum rectifying tower, one part (20-40%) of the heavy components flowing out of the bottom of the vacuum rectifying tower returns to the multistage evaporation/compression/condensation process, and one part (60-80%) of the heavy components flowing out of the bottom of the vacuum rectifying tower enters the shallow cooling rectifying process in the chlorosilane;
Step 9, shallow cold rectification in chlorosilane, namely, mixing crude chlorosilane liquid from a multistage evaporation/compression/condensation process with recombinant fluid from the bottom of a vacuum rectification column in an HCl refining process, and then entering the shallow cold rectification process in chlorosilane, wherein the operation temperature is-35-10 ℃, the operation pressure is 0.6-2.0 MPa, non-condensable gas 3 flowing out of the top of a rectification column enters an ethylene/silane separation process, and chlorosilane liquid flowing out of the bottom of the rectification column is returned to the shallow cold chlorosilane absorption process as an absorbent for recycling;
Step 10, separating ethylene/silane, namely feeding non-condensable gas 3 from a shallow cold rectifying process in chlorosilane into a rectifying tower in the ethylene/silane separating process, enabling the operating temperature to be-10-60 ℃ and the operating pressure to be 0.6-2.0 MPa, enabling silane-enriched gas to flow out from the top of the rectifying tower, feeding into a silane purifying process, and feeding ethylene-enriched fluid flowing out from the bottom of the rectifying tower into an ethylene refining process;
Step 11, purifying silane, namely, introducing silane-rich gas from an ethylene/silane separation process into a silane purification process consisting of two rectifying towers, wherein the operating temperature of the rectifying tower 1 is-35 to-30 ℃, the operating pressure is 2.0-2.5 MPa, low-boiling-point hydrogen-rich non-condensable gas 4 flows out of the top of the rectifying tower 1, the low-boiling-point hydrogen-rich non-condensable gas is mixed with shallow-cooling pressure swing adsorption-concentrated hydrogen-rich gas after cold and heat exchange, hydrogen is further recovered, the bottom effluent of the rectifying tower 1 enters the rectifying tower 2, the operating temperature is-37 to-35 ℃, the operating pressure is 1.6-2.0 MPa, siH 4 with the purity of 99.99% or more flows out of the top of the rectifying tower 2, the yield is more than 95%, the SiH 4 metal getter purifier is used as raw material gas required by SiC-CVD epitaxial process after further purification, a part (60-80%) of the heavy component flow flowing out of the bottom of the rectifying tower 2 is returned to the ethylene/silane separation process for further effective component recovery, and a part (20-40%) is directly discharged after treatment;
and 12, refining ethylene, namely, cooling and heating an ethylene-rich fluid from the bottom of a rectifying tower in an ethylene/silane separation process to an ethylene rectifying tower with the temperature of 20-120 ℃ and the pressure of 0.6-2.0 MPa, wherein an ethylene product gas flows out from the top of the ethylene rectifying tower, the purity is more than or equal to 99.99%, the yield is more than or equal to 95%, and a recombinant fluid containing C 2+/CO2 flowing out from the bottom of the ethylene/silane separation process is treated and decarbonized and then used as fuel gas.
Example 2
As shown in fig. 2, based on embodiment 1, under the working condition that the concentration of HCl and chlorosilane/chloroolefin contained in the purified raw material gas is higher, for example, the concentration of chlorine is greater than 3-6%, the shallow cold chlorosilane absorption process is additionally provided with a secondary medium temperature chlorosilane absorption process, namely, non-condensable gas 1 ' from the shallow cold chlorosilane absorption process is compressed, condensed and separated from gas-liquid, the formed non-condensable gas 1 ' is pressurized to 0.6-0.8 mpa, and is subjected to cold-heat exchange to 60-120 ℃, then enters from the bottom of the additionally provided secondary medium temperature chlorosilane absorption process, adopts a mixed liquid containing chlorosilane/HCl as an absorbent, is sprayed from the top of the secondary medium temperature chlorosilane absorption tower and is subjected to reverse mass transfer exchange with the non-condensable gas 1 ', and flows out of the absorption liquid enriched with chlorosilane and HCl from the bottom of the absorption tower, then enters into a subsequent multistage evaporation/compression/condensation process, the non-condensable gas 2 ' flows out of the top of the absorption tower, and then enters into the shallow pressure swing adsorption concentration, the formed non-condensable gas 2 ' directly or is subjected to compression, condensation and gas-liquid separation, the formed non-condensable gas 2 ' enters the pressure swing adsorption process, and the temperature range of the formed non-condensable gas 2 ' is expanded from the top of the absorption tower is further expanded to the pressure swing adsorption process, the energy-saving operation range is further, the energy-saving operation is carried out, and the energy is further, the absorption process is carried out, and the absorption of the energy is further, and the absorption process is more easily and the can be recovered, and the absorption and the HCl is recovered.
Example 3
As shown in fig. 3, based on examples 1 and 2, non-condensable gas 2/2' formed by compression, condensation and gas-liquid separation in the shallow cold chlorosilane absorption process or the secondary medium temperature chlorosilane absorption process enters a shallow cold pressure swing adsorption concentration process consisting of a two-stage PSA system in a blower pressurization mode, namely, non-condensable gas 2 is pressurized to 0.2-0.3 mpa, enters from the bottom of a 1-stage PSA adsorption tower, and non-adsorbed phase gas flowing out from the top of the 1-stage PSA adsorption tower is hydrogen-rich gas, and enters the next process, namely adsorption purification; the desorption gas desorbed (reversely discharged, flushed or vacuumized) from the bottom of the 1-section PSA adsorption tower is pressurized and sent to the bottom of a second PSA adsorption tower (2-section PSA adsorption tower), enriched non-adsorption phase hydrogen-enriched mixed intermediate gas flows out from the top of the 2-section PSA adsorption tower, methane hydrogen gas is further recovered by feeding gas, namely non-condensable gas 2, to the 1-section PSA adsorption tower, adsorption phase gas flowing out from the bottom of the 2-section PSA adsorption tower is concentrated gas containing SiH 4, chlorosilane, C 2H4, VCM and H 2, and the concentrated gas is mixed with the non-condensable gas 1 and returned to compression, condensation and gas-liquid separation of the shallow cold chlorosilane absorption process, and effective components are further recovered.
Example 4
As shown in FIG. 4, on the basis of example 1, the desorbed gas from the pressure swing adsorption hydrogen extraction process is compressed to a pressure of more than 1.5MPa, and then sent to a first-stage membrane separation hydrogen recovery system, the hydrogen-enriched permeate gas flows out from the permeate side and is mixed with purified hydrogen-enriched gas to enter the pressure swing adsorption hydrogen extraction process, H 2 is further recovered, the product gas yield is more than 90%, the methane-enriched gas flows out from the non-permeate side, ultra-pure methane byproduct is obtained by low-temperature rectification for export, and the non-condensable gas obtained by low-temperature rectification is returned to the pressure swing adsorption hydrogen extraction process, so that the yield of the H 2 product is more than 95%.
Example 5
As shown in fig. 5, based on examples 1 and 2, the shallow cold distillation process of chlorosilane is composed of distillation columns 1 and-2, the crude chlorosilane liquid flowing out of the multistage evaporation/compression/condensation process is mixed with the recombinant fluid flowing out of the bottom of the vacuum distillation column in the HCl refining process, the mixture enters the shallow cold distillation column 1 with the operating temperature of-35 to-10 ℃ and the operating pressure of 1.0 to 2.5mpa, the non-condensable gas 3 'of the light component flowing out of the top of the distillation column 1 is mainly composed of H 2 and a small amount of CH 4, the mixture is mixed with the purified hydrogen-rich gas from the adsorption purification process through a cold heat exchanger to the temperature of 5 to 40 ℃ and then enters the pressure swing adsorption hydrogen extraction process to further recover H 2 or/and CH 4, the yield of the product gas is further improved, the heavy component fluid flowing out of the bottom of the distillation column 1 enters the distillation column 2 with the operating temperature of-35 to-10 ℃ and the operating pressure of 1.0 to 2.5mpa, the non-condensable gas 3' of the light component flows out of the distillation column as a part of the top of the distillation column, the mixture flows out of the gas as the gas from the top of the distillation column as the absorption column and is not condensed gas from the top of the distillation column 2, and the gas is returned to the absorption process is not equal to 99.34% of the heavy component, and the product gas is not condensed gas is separated from the top of the distillation process and the absorption process is condensed gas, and the heavy gas is separated from the top of the distillation process is not condensed gas.
Example 6
As shown in FIG. 6, based on the embodiment 1, the silane purification process is composed of cryogenic separation, namely a low-temperature rectifying tower replaces the two-tower rectifying process, the operation temperature of the cryogenic separation is-180 to-110 ℃, siH 4 liquid with purity higher than 99.99% directly flows out from the bottom of the low-temperature rectifying tower, non-condensable gas 4 escapes from the top of the rectifying tower, and the non-condensable gas 4 is mixed with hydrogen-rich gas from the shallow-cooling pressure swing adsorption concentration process after cold exchange and pressurization, and then enters the adsorption purification process to further recover effective components.
Example 7
On the basis of the embodiment 1, liquid generated by condensing the tower top gas flowing out of the HCl rectifying tower in the HCl refining process is directly used as reflux or is mixed with crude HCl mixed liquid and then returns to the HCl rectifying tower, and non-condensable gas is used as HCl product gas, wherein the purity of the non-condensable gas is more than 99.99%.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (8)
1. The method for recycling and recycling tail gas FTrPSA of the chlorine-based SiC-CVD epitaxial process by reacting ethylene with silane is characterized by comprising the following steps of:
Step 1, pretreatment of raw gas, namely sequentially removing dust, particles, oil mist, part of high-chlorosilane, high-chloralkane and high-hydrocarbon impurities;
Step 2, shallow cold chlorosilane is absorbed, purified raw material gas from a pretreatment process enters from the bottom of a shallow cold chlorosilane absorption tower, chlorosilane liquid is adopted as an absorbent, reverse mass transfer exchange is carried out on the raw material gas and the purified raw material gas downwards by spraying from the top of the shallow cold chlorosilane absorption tower, absorption liquid flowing out from the bottom of the shallow cold chlorosilane absorption tower enters a subsequent multistage evaporation/compression/condensation process, non-condensable gas 1 flows out from the top of the absorption tower, and after compression, condensation and gas-liquid separation, the formed non-condensable gas 2 enters the next process, namely shallow cold pressure swing adsorption concentration, and the formed liquid is conveyed to a subsequent HCl refining process;
Step 3, shallow-cooling pressure swing adsorption concentration, namely, enabling the non-condensable gas 2 to enter a shallow-cooling pressure swing adsorption concentration process consisting of more than 4 adsorption towers, adopting vacuumizing for desorption, enabling non-adsorbed phase hydrogen-rich gas to flow out of the top of the adsorption tower in an adsorption state, directly entering adsorption purification, enabling the non-adsorbed phase hydrogen-rich gas to flow out of the bottom of the adsorption tower in a desorption vacuumizing state, desorbing the gas from the adsorption phase flowing out of the bottom of the adsorption tower in a desorption vacuumizing state, taking the gas as concentrated gas, carrying out cold and heat exchange, and returning the concentrated gas to be mixed with the non-condensable gas 1 to enter compression, condensation and gas-liquid separation of the shallow-cooling chlorosilane absorption process;
step 4, adsorption purification, namely, carrying out precise filtration on the hydrogen-rich gas, and then enabling the hydrogen-rich gas to enter an adsorption purification process consisting of 2 or 3 adsorption towers to form purified hydrogen-rich gas;
Step 5, hydrogen is extracted by pressure swing adsorption, purified hydrogen rich gas from an adsorption purification process enters a multi-tower pressure swing adsorption hydrogen purification process consisting of at least 4 towers, at least one adsorption tower is in an adsorption step, the rest adsorption towers are in a desorption regeneration step, the formed non-adsorption phase gas is ultra-high purity hydrogen, a flushing or flushing and vacuumizing mode is adopted during desorption, desorption gas is methane rich gas, and the methane rich gas is directly used as fuel gas to be returned to a cold and heat exchange system for tail gas recovery, or enters a membrane separation system for further recovery of H 2;
step 6, purifying the hydrogen, namely directly reducing the pressure of the ultra-high purity hydrogen from the pressure swing adsorption hydrogen extraction process to the pressure required by hydrogen for the SiC-CVD epitaxial process at the temperature of 50-500 ℃ or through a reducing valve, entering the hydrogen purification process, removing trace impurities, and obtaining a final electronic grade hydrogen product, and storing or directly returning the final electronic grade hydrogen product to a working section of the hydrogen required by the SiC-CVD epitaxial process;
Step 7, multistage evaporation/compression/condensation, wherein the absorption liquid from the shallow-cooling chlorosilane absorption process enters multistage evaporation and then enters a condenser to obtain gas-phase crude HCl gas, the crude HCl liquid formed after condensation is mixed with the liquid formed after compression, condensation and gas-liquid separation from the shallow-cooling chlorosilane absorption process, the formed crude HCl mixed liquid enters the next process, namely HCl refining, crude chlorosilane liquid flows out of the condenser and enters the subsequent shallow-cooling distillation of chlorosilane;
Step 8, refining the HCl, namely enabling the crude HCl mixed solution to enter an HCl refining process consisting of an HCl rectifying tower and a vacuum rectifying tower, enabling HCl product gas to flow out from the top of the rectifying tower, returning to an epitaxial process for recycling, enabling bottom effluent to enter the vacuum rectifying tower, enabling top gas flowing out from the top of the vacuum rectifying tower to be directly sent to an incinerator for incineration treatment and discharge, or sending out heavy components flowing out from the bottom of the vacuum rectifying tower to be extracted into VCM and chloralkane, or returning to a multistage evaporation/compression/condensation process, or returning to a next process, namely a shallow cold rectifying process in chlorsilane;
Step 9, shallow cold rectification is carried out in the chlorosilane, crude chlorosilane liquid from a multistage evaporation/compression/condensation process is mixed with recombinant fluid from the bottom of a vacuum rectification column of an HCl refining process and then enters the shallow cold rectification process in the chlorosilane, non-condensable gas 3 flows out from the top of the rectification column, and chlorosilane liquid flowing out from the bottom of the rectification column is used as an absorbent and returned to the shallow cold chlorosilane absorption process for recycling;
Step 10, separating ethylene/silane, namely, enabling non-condensable gas 3 to enter a rectifying tower in an ethylene/silane separation process, enabling silane-rich gas to flow out from the top of the rectifying tower, enabling ethylene-rich fluid flowing out from the bottom of the rectifying tower to enter a subsequent ethylene refining process;
Step 11, purifying silane, namely enabling silane-enriched gas to enter a silane purification process consisting of two rectifying towers, wherein the silane purification process comprises a rectifying tower 1, enabling low-boiling-point hydrogen-enriched non-condensable gas 4 to flow out of the top of the rectifying tower 1, mixing the low-boiling-point hydrogen-enriched non-condensable gas with shallow-cooling pressure swing adsorption-enriched gas after cold-heat exchange, further recycling hydrogen, enabling the bottom effluent of the rectifying tower 1 to enter a rectifying tower 2, enabling SiH 4 flowing out of the top of the rectifying tower 2 to be more than 95%, enabling the SiH 4 to be directly or further purified and then be used as raw material gas required by an SiC-CVD epitaxial process for recycling, enabling a part of heavy component flow flowing out of the bottom of the rectifying tower 2 to return to an ethylene/silane separation process for further recycling effective components, and enabling a part of the recovered effective components to be directly discharged after treatment;
And 12, refining ethylene, namely enabling ethylene-rich fluid from the bottom of a rectifying tower in an ethylene/silane separation process to flow out of ethylene product gas from the top of the rectifying tower through the ethylene rectifying tower, or returning the ethylene-rich fluid to a SiC-CVD epitaxial process, and discharging the recombinant fluid flowing out of the bottom of the rectifying tower after treatment or using the recombinant fluid as fuel gas.
2. The method for recycling and reusing the tail gas FTrPSA of the chloro-SiC-CVD epitaxial process for the reaction of ethylene and silane according to claim 1, wherein the shallow cold chlorosilane absorption process is additionally provided with a secondary medium temperature chlorosilane absorption process under the working condition that the concentration of HCl and chlorosilane/chloroolefin contained in purified raw material gas is higher, namely, the non-condensable gas 1 ' formed after the non-condensable gas 1 ' from the shallow cold chlorosilane absorption process is compressed, condensed and separated from gas liquid, enters from the bottom of the additionally provided secondary medium temperature chlorosilane absorption process, adopts mixed liquid containing chlorosilane/HCl as an absorbent, performs reverse mass transfer exchange with the non-condensable gas 1 ' after spraying from the top of the secondary medium temperature chlorosilane absorption tower, flows out of the absorption liquid of the chlorosilane and HCl from the bottom of the absorption tower, enters into a subsequent multi-stage evaporation/compression/condensation process, flows out of the non-condensable gas 2 from the top of the absorption tower, directly or after the non-condensable gas 2' formed after the compression, condensation and gas liquid separation, enters into a next process, namely, shallow cold absorption and concentration, and then forms a part of the non-condensable gas 2' after the compression and condensed liquid and is separated from the absorption liquid, and returns to the subsequent liquid to the subsequent absorption process, and the HCl is recovered, and the HCl is further used for recycling the product.
3. The method for recycling and reusing tail gas FTrPSA of chloro-SiC-CVD epitaxial process by reacting ethylene with silane according to claim 1, wherein the liquid produced by condensing the top gas flowing out of the HCl rectifying tower in the HCl refining process is used as reflux and is returned to the HCl rectifying tower directly or after being mixed with crude HCl mixed liquid, and the noncondensable gas is used as HCl product gas.
4. The method for recycling and recycling tail gas FTrPSA of a chlorine-based SiC-CVD epitaxial process for reacting ethylene with silane according to claim 2, wherein non-condensable gas 2 or non-condensable gas 2' formed in the secondary medium-temperature chlorosilane absorption process enters a shallow-cooling pressure swing adsorption concentration process in a blower pressurization mode, the process consists of a two-stage PSA system, namely, the non-condensable gas 2 is pressurized to 0.2-0.3 MPa, enters from the bottom of a 1-stage PSA adsorption tower, and non-adsorbed phase gas flowing out from the top of the 1-stage PSA adsorption tower is hydrogen-rich gas, and enters the next process, namely, adsorption purification; the desorption gas desorbed from the bottom of the 1-section PSA adsorption tower is sent to the bottom of the 2-section PSA adsorption tower through pressurization, enriched non-adsorption phase hydrogen-rich mixed intermediate gas flows out from the top of the 2-section PSA adsorption tower, and returns to the feed gas of the 1-section PSA adsorption tower, namely, non-condensable gas 2, so as to further recover methane and hydrogen gas, and the concentrated gas flowing out from the bottom of the 2-section PSA adsorption tower is mixed with the non-condensable gas 1 and returns to the compression, condensation and gas-liquid separation of the shallow cold chlorosilane absorption process, so that the effective components are further recovered.
5. The method for recycling and reusing tail gas FTrPSA of chlorine-based SiC-CVD epitaxial process for reacting ethylene with silane according to claim 1, wherein the desorbed gas from the pressure swing adsorption hydrogen extraction process is compressed to a pressure of more than 1.5MPa and then sent to a membrane separation recovery hydrogen system of one or two stages, the permeate gas is flowed out from the permeate side, or the permeate gas is mixed with the hydrogen-rich gas from the shallow cold pressure swing adsorption concentration process to enter the adsorption purification process, or the purified hydrogen-rich gas is mixed with the purified hydrogen-rich gas to enter the pressure swing adsorption hydrogen extraction process, H 2 is further recovered, the methane-rich gas is flowed out from the non-permeate side, or the methane-rich gas is directly used as fuel gas, or ultra-pure methane byproduct is obtained through cryogenic rectification, and the noncondensable gas obtained through cryogenic rectification is returned to the pressure swing adsorption hydrogen extraction process.
6. The method for recycling and cyclic reutilization of tail gas FTrPSA of chlorine-based SiC-CVD epitaxial process of ethylene and silane according to claim 2, wherein the in-chlorosilane shallow-cold rectifying process comprises a shallow-cold rectifying tower 1 and a shallow-cold rectifying tower 2, crude chlorosilane liquid flowing out of the multistage evaporation/compression/condensation process is mixed with recombinant fluid flowing out of the bottom of a vacuum rectifying tower in the HCl refining process, the mixture enters the shallow-cold rectifying tower 1, noncondensable gas 3' of light components flows out of the top of the middle-shallow-cold rectifying tower 1, or the mixture of the gas and purified hydrogen-rich gas from the adsorption purifying process is cooled to 5-40 ℃ through a cold heat exchanger and then enters the pressure swing adsorption hydrogen extraction process, or/or the mixture of the gas 2 of noncondensable gas formed after direct or reduced pressure to 0.5-1.5 mpa and gas-liquid separation of the middle-shallow-cold chlorosilane absorbing process is then enters the shallow-cold pressure swing adsorption concentration process, the recombinant fluid flowing out of the bottom of the middle-shallow-cold rectifying tower 1 is then enters the in the chlorosilane, the chlorine gas 2, the chloro silane flows out of the bottom of the middle-shallow-cold rectifying tower as a chlorine liquid, and the mixture of the gas from the top of the middle-shallow-cold rectifying tower 1 is returned to the middle-cold rectifying tower 2 as the refrigerant, and the mixture of the gas is recycled from the middle-cold rectifying tower and the next to the absorption process is used as the absorption process.
7. The method for recycling and reusing tail gas FTrPSA of chloro-SiC-CVD epitaxial process by reacting ethylene with silane according to claim 1, wherein the silane purification process adopts cryogenic separation, namely a low-temperature rectifying tower replaces the silane purification process consisting of two towers, siH 4 liquid directly flows out from the bottom of the low-temperature rectifying tower, non-condensable gas 4 escapes from the top of the rectifying tower, and the non-condensable gas 4 is mixed with hydrogen-rich gas from a shallow-cooling pressure swing adsorption concentration process after cold-heat exchange and pressurization, and then enters an adsorption purification process to further recover effective components.
8. The method for recycling and reusing tail gas FTrPSA of a chloro-SiC-CVD epitaxial process for reacting ethylene with silane according to claim 1, wherein the rectifying tower 2 of the silane purifying process is replaced by a pressure swing adsorption tower, namely, fluid flowing out from the bottom of the rectifying tower 1 of the silane purifying process is sent to the pressure swing adsorption tower which is composed of at least 2 adsorption towers with the operating temperature of 20-40 ℃ and the operating pressure of less than 1.0MPa after being subjected to cold-heat exchange to 20-40 ℃ and reduced pressure to less than 1.0MPa, silane product gas flows out from the top of the adsorption tower, is directly or further purified by an SiH 4 metal getter purifier and is recycled as raw material gas required by the SiC-CVD epitaxial process, and desorption gas flowing out from the bottom of the adsorption tower is mixed with noncondensable gas 3 generated in the shallow cold rectifying process in the chlorosilane, and returns to the ethylene/silane separating process after being subjected to cold-heat exchange and pressure regulation.
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| CN109574786A (en) * | 2018-12-26 | 2019-04-05 | 四川天采科技有限责任公司 | Preparing propylene by dehydrogenating propane reaction mixture gas cold oil absorbs the separation method coupled with PSA |
| CN110201487B (en) * | 2019-06-24 | 2021-06-25 | 浙江天采云集科技股份有限公司 | Method for purifying and recycling high-purity high-yield methane-induced stable gas in ethylene process for preparing ethylene oxide |
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| CN102438728A (en) * | 2009-03-26 | 2012-05-02 | 依卡贝尔技术有限公司 | method for separating gases |
| CN108658042A (en) * | 2018-05-29 | 2018-10-16 | 四川天采科技有限责任公司 | A kind of LED-MOCVD processing procedures tail gas warm journey pressure-variable adsorption full constituent recycling method entirely |
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