CN113521785A - Thermally coupled methanol rectification method of side line and partition recovery tower - Google Patents
Thermally coupled methanol rectification method of side line and partition recovery tower Download PDFInfo
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- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 title claims abstract description 156
- 238000000034 method Methods 0.000 title claims abstract description 48
- 238000011084 recovery Methods 0.000 title claims abstract description 10
- 238000005192 partition Methods 0.000 title abstract description 5
- 238000010992 reflux Methods 0.000 claims abstract description 77
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 43
- 238000000926 separation method Methods 0.000 claims description 13
- 239000007788 liquid Substances 0.000 claims description 12
- 230000010354 integration Effects 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 230000008878 coupling Effects 0.000 claims description 5
- 238000010168 coupling process Methods 0.000 claims description 5
- 238000005859 coupling reaction Methods 0.000 claims description 5
- 239000002351 wastewater Substances 0.000 claims description 5
- 238000009833 condensation Methods 0.000 claims description 4
- 230000005494 condensation Effects 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 3
- 230000011218 segmentation Effects 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 5
- 238000005265 energy consumption Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000000498 cooling water Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000009835 boiling Methods 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 239000001760 fusel oil Substances 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 238000010977 unit operation Methods 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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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
- B01D3/143—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step
- B01D3/146—Multiple effect distillation
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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
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
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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
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
- B01D3/322—Reboiler specifications
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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
- B01D3/42—Regulation; Control
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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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
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
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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
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
本发明公开了侧线及隔壁回收塔热耦合甲醇精馏方法，基于一种五塔三效甲醇精馏装置，包括如下设备：预塔T1，预塔再沸器H1，预塔冷凝器C1；高压塔T2，高压塔再沸器H2，高压塔回流罐V1；中压塔T3，中压塔再沸器H3，中压塔回流罐V2；常压塔T4，常压塔再沸器H4，常压塔冷凝器C2；水塔T5，水塔冷凝器C3；其中，高压塔T2塔顶蒸汽管道和中压塔再沸器H3相连；中压塔T3塔顶蒸汽和常压塔再沸器H4相连。该精馏方法安全性好，在节能的同时也能保持良好的操作性，开车难度低；末塔采用水塔并取消再沸器的使用，进一步降低了外界蒸汽的消耗同时改进方法进一步降低了外界蒸汽的消耗。
The invention discloses a thermally coupled methanol rectification method for a sideline and a partition wall recovery tower, based on a five-column three-effect methanol rectification device, comprising the following equipment: a pre-column T1, a pre-column reboiler H1, a pre-column condenser C1; Column T2, high pressure column reboiler H2, high pressure column reflux tank V1; medium pressure column T3, medium pressure column reboiler H3, medium pressure column reflux tank V2; atmospheric column T4, atmospheric column reboiler H4, normal pressure column T4 The pressure tower condenser C2; the water tower T5, the water tower condenser C3; wherein, the high pressure tower T2 tower top steam pipeline is connected with the medium pressure tower reboiler H3; the medium pressure tower T3 tower top steam is connected with the atmospheric pressure tower reboiler H4. The rectification method has good safety, can maintain good operability while saving energy, and has low start-up difficulty; the last tower adopts a water tower and cancels the use of a reboiler, which further reduces the consumption of external steam and the improved method further reduces the external consumption of steam.
Description
Technical Field
The invention belongs to the field of chemical separation processes, and particularly relates to a thermal coupling methanol rectification method of a side line and bulkhead recovery tower.
Background
Rectification is an important unit operation directly affecting product quality, accounts for about 90% -95% of the separation process of the whole device, can consume 3% of energy in the whole world and 40% of energy in the whole chemical industry, and is a typical energy-intensive process. The reduction of the energy consumption in the rectification process has important significance for optimizing the energy structure of the whole chemical industry.
Rectification heat integration is one of the main means for improving the energy utilization rate, and the basic idea is to exchange heat of cold and hot streams in the process to recover heat. Such as multi-effect distillation, the energy levels between different columns can be varied by controlling the operating pressures of the different columns. Because the boiling point of the material flow can be raised along with the raising of the pressure, the separated overhead steam can supply heat to the reboiler of the lower pressure tower, and the purposes of steam condensation and liquid vaporization in the reboiler are realized. Compared with the common rectifying sequence, the middle rectifying device can not supply heat and cool additionally except for the rectifying towers at the two ends.
Besides the research on the process, a method for energy conservation and emission reduction of equipment, such as application of a dividing wall tower, is also developed. The vertical partition plate is arranged in the rectifying tower, so that the mass transfer and heat transfer processes in the rectifying tower are realized on the premise of setting a material flow distribution method. The partition wall tower combines two rectifying towers together, so that the investment of the rectifying towers can be reduced, and the investment of a reboiler and a condenser can be saved. In addition, the dividing wall tower can effectively avoid the back mixing effect of the intermediate components, so that the energy consumption is further saved.
The currently commonly used methanol synthesis method takes coal as a source, and finally obtains a methanol product through gasification, low-temperature methanol washing, gas separation and methanol refining units. The methanol rectification unit is used as a core unit for methanol refining, and the reduction of the process energy consumption is of great significance for optimizing the whole methanol manufacturing process. The traditional three-tower process for separating the methanol has the advantages of convenient operation and short process. The process uses a pre-tower, a pressurizing tower and an atmospheric tower to separate methanol, the pre-tower separates methanol oil and light component gas, the pressurizing tower and the atmospheric tower simultaneously separate refined methanol at the top of the tower, and the side line and the bottom of the atmospheric tower respectively separate fusel oil and wastewater.
After long-term use and research, the three-tower process has steam consumption of 1.1-1.2 tons/methanol even if an advanced heat integration method is adopted. The traditional three-tower flow methanol rectification process has high energy consumption, the product can hardly meet the product quality requirement of the current downstream products on the raw materials, and the recovery rate of the methanol gradually tends to be the limit. Based on this, there is a need to develop new energy-saving methods to optimize the methanol rectification process.
Disclosure of Invention
In order to solve the technical problem of the conventional methanol rectification, the invention provides a thermal coupling methanol rectification method of a side line and bulkhead recovery tower.
The technical scheme of the invention is a thermal coupling methanol rectification method of a lateral line and bulkhead recovery tower, which is based on a five-tower triple-effect methanol rectification device and comprises the following equipment: a pre-column T1, a pre-column reboiler H1, a pre-column condenser C1; high pressure column T2, high pressure column reboiler H2, high pressure column reflux drum V1; medium pressure column T3, medium pressure column reboiler H3, medium pressure column reflux drum V2; atmospheric tower T4, atmospheric tower reboiler H4, atmospheric tower condenser C2; water column T5, water column condenser C3;
wherein, the steam pipeline at the top of the high pressure tower T2 is connected with a medium pressure tower reboiler H3; the medium pressure column T3 overhead vapor was connected to the atmospheric column reboiler H4. The rest reboilers are connected with steam pipelines with different pressures, and the condensers are connected with process cooling water pipelines.
(1) Raw material crude methanol flows into a pre-tower T1, the top steam is partially condensed by a pre-tower condenser C1 to separate methanol oil and light component non-condensable gas, the reflux part of the bottom stream of the pre-tower T1 flows into a pre-tower reboiler, is vaporized by a steam heating part and then flows into a pre-tower T1, and the other part of the bottom stream flows into a high-pressure tower T2 to be separated;
(2) after the steam at the top of the high-pressure tower T2 is condensed into liquid by a medium-pressure tower reboiler H3, the reflux part flows into the high-pressure tower T2 through a high-pressure tower reflux tank V1, the product part is a refined methanol outflow boundary area, the reflux part of the bottom stream of the high-pressure tower T2 flows into a high-pressure tower reboiler H2, is vaporized by a steam heating part and then flows into a high-pressure tower T2, and the other part flows into a medium-pressure tower T3 for separation;
(3) after steam at the top of the medium pressure tower T3 is condensed into liquid by a constant pressure tower reboiler H4, a reflux part enters the medium pressure tower T3 through a medium pressure tower reflux tank V2, a product part is a refined methanol outflow boundary area, a reflux part of a tower bottom stream of the medium pressure tower T3 flows into a medium pressure tower reboiler H3, is heated and vaporized by steam at the top of a high pressure tower T2, flows into a medium pressure tower T3, and the other part flows into the constant pressure tower T4 for separation;
(4) the steam at the top of the atmospheric tower T4 is condensed by an atmospheric tower condenser C2 and then partially flows back, part of the steam is taken as a refined methanol product to flow out of a boundary region, the side stream of the atmospheric tower T4 is discharged and enters a water tower T5 to be separated, the reflux part of the tower bottom stream flows into an atmospheric tower reboiler H4 and flows into an atmospheric tower T4 after being heated and vaporized by the steam at the top of a medium pressure tower T3, and the other part of the reflux part of the tower bottom stream is taken as waste water to flow out of the boundary region;
(5) the vapor from the top of the water tower T5 is partially refluxed after being condensed by a water tower condenser C3, the other part is fusel liquid flowing out of a boundary zone, and the bottom stream of the water tower T5 flows into an atmospheric tower T4 without passing through a reboiler.
Energy matching is formed among the three towers by adjusting the working pressure and temperature of the high-pressure tower T1, the medium-pressure tower T2 and the normal-pressure tower T3, so that triple-effect rectification is formed;
the method comprises the following steps:
1) on the basis of a light component segmentation forward heat integration five-tower process, a pre-tower T1, a high-pressure tower T2, a medium-pressure tower T3, a normal-pressure tower T4 and a water tower T5 are adopted to separate crude methanol;
2) the heat matching among the rectifying towers is realized by adjusting the operating pressure of the high-pressure tower T2, the medium-pressure tower T3 and the normal-pressure tower T4, so that the steam at the top of the high-pressure tower T2 just supplies heat to the medium-pressure tower reboiler H3, and the steam at the top of the medium-pressure tower T3 just supplies heat to the normal-pressure tower reboiler H4;
3) triple-effect rectification is adopted among the high-pressure tower T2, the medium-pressure tower T3 and the atmospheric tower T4, steam of the overhead material flow of the high-pressure tower T2 supplies heat to a medium-pressure tower reboiler H3, and steam of the overhead material flow of the medium-pressure tower T3 supplies heat to an atmospheric tower reboiler H4;
4) the last tower of the process adopts a water tower T5, the use of a reboiler is eliminated, and water and fusel are separated from the tower at the same time of a normal pressure tower T4;
the operating pressure range of the pre-tower T1 is 120kPa and 180kPa, and the reflux ratio is between 0.3 and 0.7;
the operating pressure range of the high-pressure tower T2 is 1200-1600kPa, and the reflux ratio is between 3 and 5;
the operating pressure range of the medium-pressure tower T3 is 500kPa and 700kPa, and the reflux ratio is between 1.5 and 3; a medium-pressure tower reboiler H3 is arranged at the bottom of the medium-pressure tower T3, and steam at the top of the high-pressure tower T2 is used as a heat source;
the operating pressure range of the atmospheric tower T4 is 50-150kPa, and the reflux ratio is 1.2-2.5; the bottom of the atmospheric tower T4 is provided with an atmospheric tower reboiler H4, and the steam at the top of the medium pressure tower T3 is used as a heat source;
the water column T5 is operated at a pressure in the range of 50 to 150kPa with a reflux ratio in the range of 2 to 18.
Further, the method of the invention also comprises the following steps:
1) combining atmospheric column T4 and water column T5 into dividing wall column T6;
2) a first condenser C4A of the dividing wall tower, a second condenser C4B of the dividing wall tower and a reboiler H5 of the dividing wall tower respectively replace a condenser C2 of the normal pressure tower, a condenser C3 of the water tower and a reboiler H4 of the normal pressure tower;
3) the steam at the top of the medium-pressure tower T3 is connected with a partition tower reboiler H5, and the condensed liquid is connected with a medium-pressure tower reflux tank V2;
4) one of the vapor streams at the top of the dividing wall tower T6 is connected with a first condenser C4A of the dividing wall tower, and the other vapor stream is connected with a second condenser C4B of the dividing wall tower;
the reflux portion of the bottom stream of dividing wall column T6 was connected to dividing wall column reboiler H5.
The operating pressure range of the pre-tower T1 is 120kPa and 180kPa, and the reflux ratio is between 0.3 and 0.7;
the operating pressure range of the high-pressure tower T2 is 1200-1600kPa, and the reflux ratio is between 3 and 5'
The operating pressure range of the medium-pressure tower T3 is 500kPa and 700kPa, and the reflux ratio is between 1.5 and 3; a medium-pressure tower reboiler H3 is arranged at the bottom of the medium-pressure tower T3, and steam at the top of the high-pressure tower T2 is used as a heat source;
the operating pressure range of the atmospheric tower T4 is 50-150kPa, and the reflux ratio is 1.2-2.5; the bottom of the atmospheric tower T4 is provided with an atmospheric tower reboiler H4, and the steam at the top of the medium pressure tower T3 is used as a heat source;
the water column T5 is operated at a pressure in the range of 50 to 150kPa with a reflux ratio in the range of 2 to 18.
The invention has the following characteristics:
(1) on the basis of a light component segmentation forward heat integration five-tower process, a pre-tower T1, a high-pressure tower T2, a medium-pressure tower T3, a normal-pressure tower T4 and a water tower T5 are adopted to separate crude methanol;
(2) the heat matching among the rectifying towers is realized by adjusting the operating pressure of the high-pressure tower T2, the medium-pressure tower T3 and the normal-pressure tower T4, so that the steam at the top of the high-pressure tower T2 just supplies heat to the medium-pressure tower reboiler H3, and the steam at the top of the medium-pressure tower T3 just supplies heat to the normal-pressure tower reboiler H4;
(3) triple-effect rectification is adopted among a high-pressure tower T2, a medium-pressure tower T3 and a normal-pressure tower T4, steam of material flow at the top of the high-pressure tower T2 supplies heat to a medium-pressure tower reboiler H3, and steam at the top of the medium-pressure tower T3 supplies heat to a normal-pressure tower reboiler H4;
(4) the last tower of the flow adopts a water tower T5, the use of a reboiler is eliminated, and water and fusel are simultaneously separated from the normal pressure tower T4.
Advantageous effects
1. Through the triple-effect rectification technology, heat integration among different operating pressure towers is realized by utilizing steam at the top of the rectification tower, and the consumption of external steam in the whole process is reduced to a greater extent.
2. The method has good safety, can save energy and keep good operability at the same time, and has low driving difficulty.
3. The last tower adopts a water tower and the use of a reboiler is eliminated, thereby further reducing the consumption of external steam.
4. In the improved process, a divided wall column, an inverse cis-penta column, triple/double effect process may be used.
Drawings
FIG. 1 is a schematic diagram of a five-tower three-effect methanol rectification separation process based on a multi-effect rectification technology;
FIG. 2 is a schematic diagram of a modified triple effect methanol rectification process based on a dividing wall column-multiple effect rectification;
wherein: t1-pretower, H1-pretower reboiler, C1-pretower condenser; t2-high pressure column, H2-high pressure column reboiler, V1-high pressure column reflux tank; t3-medium pressure column, H3-medium pressure column reboiler, V2-medium pressure column reflux drum; t4-atmospheric tower, H4-atmospheric tower reboiler, C2-atmospheric tower condenser; t5-water tower, C3-water tower condenser; t6-bulkhead column, H5-bulkhead column reboiler, C4A-bulkhead column first condenser, C4B-bulkhead column second condenser.
Detailed Description
The invention is described in further detail below with reference to the following figures and specific examples:
example 1
As shown in figure 1, the five-tower three-effect methanol rectification device based on the multi-effect rectification technology has the following connection mode: wherein, the steam pipeline at the top of the high pressure tower T2 is connected with a medium pressure tower reboiler H3; the medium pressure column T3 overhead vapor was connected to the atmospheric column reboiler H4. The rest reboilers are connected with steam pipelines with different pressures, and the condensers are connected with process cooling water pipelines.
The invention adopts a triple-effect rectification technology, and the process flow comprises the following steps: 1) raw material crude methanol flows into a pre-tower T1, the steam at the top of the tower is partially condensed by a pre-tower condenser C1, methanol oil and light component non-condensable gas are separated, and the effluent part of the tower bottom stream of the pre-tower T1 flows into a high-pressure tower T2 for separation; 2) after the steam at the top of the high pressure tower T2 is condensed into liquid by a medium pressure tower reboiler H3, the reflux part flows into the high pressure tower T2 through a high pressure tower reflux tank V1, the product part is a refined methanol outflow boundary area, and the outflow part of the bottom stream of the high pressure tower T2 flows into a medium pressure tower T3 for separation; after steam at the top of the medium pressure tower T3 is condensed into liquid by a constant pressure tower reboiler H4, a reflux part enters the medium pressure tower T3 through a medium pressure tower reflux tank V2, a product part is a refined methanol outflow boundary area, a reflux part of a tower bottom stream of the medium pressure tower T3 flows into a medium pressure tower reboiler H3, is heated and vaporized by steam at the top of a high pressure tower T2, flows into a medium pressure tower T3, and the other part flows into the constant pressure tower T4 for separation; the steam at the top of the atmospheric tower T4 is condensed by an atmospheric tower condenser C2 and then partially flows back, part of the steam is taken as a refined methanol product to flow out of a boundary region, the side stream of the atmospheric tower T4 is discharged and enters a water tower T5 to be separated, the reflux part of the tower bottom stream flows into an atmospheric tower reboiler H4 and flows into an atmospheric tower T4 after being heated and vaporized by the steam at the top of a medium pressure tower T3, and the other part of the reflux part of the tower bottom stream is taken as waste water to flow out of the boundary region; 3) the vapor from the top of the water tower T5 is partially refluxed after being condensed by a water tower condenser C3, the other part is fusel liquid flowing out of a boundary zone, and the bottom stream of the water tower T5 flows into an atmospheric tower T4 without passing through a reboiler.
The average operating pressure of the whole pre-tower T1 is 150kPa, and the reflux ratio of the tower top is 0.3; the average operating pressure of the whole high-pressure tower T2 is 1400kPa, and the reflux ratio of the tower top is 3; the average operation pressure of the medium-pressure tower T3 in the whole tower is 600kPa, and the reflux ratio of the tower top is 1.5; the average operating pressure of the whole atmospheric tower T4 is 100kPa, and the reflux ratio of the top of the tower is 1.2; the average operating pressure of the whole water tower T5 is 100kPa, and the reflux ratio of the tower top is 2;
the steam consumption per monomer product of this process scheme is 0.86, which is about 28.33% lower than currently operating plants, compared to existing industrial processes.
Example 2
The average operating pressure of the whole pre-tower T1 is 120kPa, and the reflux ratio of the tower top is 0.4; the average operating pressure of the whole high-pressure tower T2 is 1200kPa, and the reflux ratio of the tower top is 4; the average operation pressure of the whole medium-pressure tower T3 is 500kPa, and the reflux ratio of the tower top is 2; the average operating pressure of the whole atmospheric tower T4 is 50kPa, and the reflux ratio of the top of the tower is 1.2; the average operating pressure of the whole water tower T5 is 50kPa, and the reflux ratio of the tower top is 3; the other steps are the same as the step 1.
Example 3
The average operating pressure of the whole pre-tower T1 is 180kPa, and the reflux ratio of the tower top is 0.7; the average operating pressure of the whole high-pressure tower T2 is 1600kPa, and the reflux ratio of the tower top is 5; the average operation pressure of the whole medium-pressure tower T3 is 700kPa, and the reflux ratio of the tower top is 3; the average operating pressure of the whole atmospheric tower T4 is 150kPa, and the reflux ratio of the top of the tower is 2.5; the average operating pressure of the whole water tower T5 is 150kPa, and the reflux ratio of the tower top is 18; the other steps are the same as the step 1.
Example 4
As shown in figure 2, the technological process of the triple-effect methanol rectification improved flow method based on the dividing wall tower-multiple-effect rectification is basically consistent with that of the embodiment 1. The dividing wall tower T6 replaces the normal pressure tower T4 and the water tower T5 in the example 1; the first condenser C4A of the dividing wall tower, the second condenser C4B of the dividing wall tower and the reboiler H5 of the dividing wall tower respectively replace the condenser C2 of the normal pressure tower, the condenser C3 of the water tower and the reboiler H4 of the normal pressure tower in the embodiment 1; the overhead steam of the medium pressure tower T3 is condensed into liquid by a bulkhead tower reboiler H5, then enters the medium pressure tower T3 through the reflux part of a medium pressure tower reflux tank V2, the product part is a refined methanol outflow boundary area, the reflux part of the bottom stream of the medium pressure tower T3 flows into a medium pressure tower reboiler H3, is heated and vaporized by the overhead steam of a high pressure tower T2, then flows into the medium pressure tower T3, and the other part flows into the bulkhead tower T6 for separation; one steam flow at the top of the dividing wall tower T6 enters a first condenser C4A of the dividing wall tower, after condensation, part of the steam flow partially refluxes and is used as a refined methanol outflow boundary area, and the other steam flow enters a second condenser C4B of the dividing wall tower, after condensation, part of the steam flow refluxes and is used as a fusel outflow boundary area; the reflux part of the bottom stream of the dividing wall tower T6 flows into a dividing wall tower reboiler H5, is heated and vaporized by the top steam of the intermediate pressure tower T3 and then flows into a dividing wall tower T6, and the other part of the reflux part is a wastewater outflow boundary area. The remaining flow charts show the connection method in accordance with case 1.
The average operating pressure of the whole pre-tower T1 is 150kPa, and the reflux ratio of the tower top is 0.3; the average operating pressure of the whole high-pressure tower T2 is 1400kPa, and the reflux ratio of the tower top is 3; the average operation pressure of the medium-pressure tower T3 in the whole tower is 600kPa, and the reflux ratio of the tower top is 1.5; the average operation pressure of the whole dividing wall tower T6 is 100kPa, and the reflux ratio of the tower top is 1 and 2;
the steam consumption per monomer product of this process scheme is 0.86, which is about 28.33% lower than currently operating plants, compared to existing industrial processes.
Claims (3)
1. A thermal coupling methanol rectification method of a side line and bulkhead recovery tower is characterized in that based on a five-tower triple-effect methanol rectification device, the rectification method comprises the following equipment:
a pre-column (T1), a pre-column reboiler (H1), a pre-column condenser (C1);
a high pressure column (T2), a high pressure column reboiler (H2), a high pressure column reflux drum (V1);
medium pressure column (T3), medium pressure column reboiler (H3), medium pressure column reflux drum (V2);
atmospheric tower (T4), atmospheric tower reboiler (H4), atmospheric tower condenser (C2);
water column (T5), water column condenser (C3);
wherein, the overhead steam pipeline of the high pressure tower (T2) is connected with the middle pressure tower reboiler (H3), and the overhead steam of the middle pressure tower (T3) is connected with the atmospheric tower reboiler (H4);
1) raw material crude methanol flows into a pre-tower (T1), overhead steam is partially condensed by a pre-tower condenser (C1) to separate methanol oil and light component non-condensable gas, while the reflux part of the bottom stream of the pre-tower (T1) flows into a pre-tower reboiler to be vaporized by a steam heating part and then flows into the pre-tower (T1), and the other part of the bottom stream flows into a high-pressure tower (T2) to be separated;
2) condensing the top steam of the high-pressure tower (T2) into liquid through a medium-pressure tower reboiler (H3), wherein the reflux part flows into the high-pressure tower (T2) through a high-pressure tower reflux tank (V1), the product part is a refined methanol outflow boundary area, the reflux part of the bottom stream of the high-pressure tower (T2) flows into the high-pressure tower reboiler (H2) and flows into the high-pressure tower (T2) after being heated and vaporized by steam, and the other part flows into the medium-pressure tower (T3) for separation;
3) after the steam at the top of the medium pressure tower (T3) is condensed into liquid by a constant pressure tower reboiler (H4), the reflux part enters the medium pressure tower (T3) through a medium pressure tower reflux tank (V2), the product part is a refined methanol outflow boundary area, the reflux part of the bottom stream of the medium pressure tower (T3) flows into the medium pressure tower reboiler (H3) and flows into the medium pressure tower (T3) after being heated and vaporized by the steam at the top of the high pressure tower (T2), and the other part flows into the constant pressure tower (T4) for separation;
4) the top steam of the atmospheric tower (T4) is condensed by an atmospheric tower condenser (C2) and then partially flows back, part of the top steam is taken as a refined methanol product to flow out of a boundary region, the side discharge of the atmospheric tower (T4) enters a water tower (T5) for separation, the reflux part of the bottom stream flows into an atmospheric tower reboiler (H4) and flows into the atmospheric tower (T4) after being heated and vaporized by the top steam of the intermediate pressure tower (T3), and the other part of the bottom stream is taken as a waste water outflow boundary region;
5) the overhead vapor from water column (T5) is partially refluxed after condensation by water column condenser (C3), another part is fusel effluent boundary zone, and the bottom stream from water column (T5) flows into atmospheric column (T4) without reboiler.
2. The method for rectifying the thermally coupled methanol by the side line and the bulkhead recovery tower according to claim 1, wherein the three towers form energy matching by adjusting the working pressure and temperature of the high pressure tower (T1), the medium pressure tower (T2) and the normal pressure tower (T3) so as to form three-effect rectification;
the method comprises the following steps:
1) on the basis of a light component segmentation forward heat integration five-tower flow, a pre-tower (T1), a high-pressure tower (T2), a medium-pressure tower (T3), an atmospheric tower (T4) and a water tower (T5) are adopted to separate crude methanol;
2) the heat matching among the rectifying towers is realized by adjusting the operating pressure of the high-pressure tower (T2), the medium-pressure tower (T3) and the normal-pressure tower (T4), so that the top steam of the high-pressure tower (T2) just supplies heat to a medium-pressure tower reboiler (H3), and the top steam of the medium-pressure tower (T3) just supplies heat to a normal-pressure tower reboiler (H4);
3) triple-effect rectification is adopted among the high-pressure tower (T2), the medium-pressure tower (T3) and the atmospheric tower (T4), steam of the tower top material flow of the high-pressure tower (T2) supplies heat to a reboiler (H3) of the medium-pressure tower, and steam of the tower top of the medium-pressure tower (T3) supplies heat to a reboiler (H4) of the atmospheric tower;
4) the last tower of the process adopts a water tower (T5), the use of a reboiler is eliminated, and water and fusel are separated from the atmospheric tower (T4);
the operating pressure range of the pre-tower (T1) is 120-180kPa, and the reflux ratio is between 0.3 and 0.7;
the operating pressure range of the high-pressure tower (T2) is 1200-1600kPa, and the reflux ratio is between 3 and 5;
the operating pressure range of the medium-pressure tower (T3) is 500-700kPa, and the reflux ratio is between 1.5 and 3; a medium-pressure tower reboiler (H3) is arranged at the bottom of the medium-pressure tower (T3), and the steam at the top of the high-pressure tower (T2) is used as a heat source;
the operating pressure range of the atmospheric tower (T4) is 50-150kPa, and the reflux ratio is 1.2-2.5; the bottom of the atmospheric tower (T4) is provided with an atmospheric tower reboiler (H4), and the steam at the top of the medium-pressure tower (T3) is used as a heat source;
the water column (T5) is operated at a pressure in the range of 50 to 150kPa with a reflux ratio in the range of 2 to 18.
3. The thermally coupled methanol rectification method with a side line and bulkhead recovery tower of claim 1, characterized in that,
1) combining an atmospheric tower (T4) and a water tower (T5) into a divided wall tower (T6);
2) a first condenser (C4A) of the dividing wall tower, a second condenser (C4B) of the dividing wall tower and a reboiler (H5) of the dividing wall tower respectively replace a condenser (C2) of the normal pressure tower, a condenser (C3) of the water tower and a reboiler (H4) of the normal pressure tower;
3) the steam at the top of the medium-pressure tower (T3) is connected with a reboiler (H5) of a dividing wall tower, and the condensed liquid is connected with a reflux tank (V2) of the medium-pressure tower;
4) one of the vapor streams at the top of the dividing wall column (T6) is connected with a first condenser (C4A) of the dividing wall column, and the other vapor stream is connected with a second condenser (C4B) of the dividing wall column;
5) the reflux portion of the bottom stream of the dividing wall column (T6) was connected to a dividing wall column reboiler (H5).
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| CN202110948839.8A CN113521785A (en) | 2021-08-18 | 2021-08-18 | Thermally coupled methanol rectification method of side line and partition recovery tower |
| LU502636A LU502636B1 (en) | 2021-08-18 | 2022-08-09 | Methanol distillation apparatus and method of side draw and dividing wall recovery tower thermal coupling |
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