CN114736093A - Process for separating naphtha - Google Patents
Process for separating naphtha Download PDFInfo
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- CN114736093A CN114736093A CN202110026202.3A CN202110026202A CN114736093A CN 114736093 A CN114736093 A CN 114736093A CN 202110026202 A CN202110026202 A CN 202110026202A CN 114736093 A CN114736093 A CN 114736093A
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- 238000000034 method Methods 0.000 title claims abstract description 43
- QWTDNUCVQCZILF-UHFFFAOYSA-N isopentane Chemical compound CCC(C)C QWTDNUCVQCZILF-UHFFFAOYSA-N 0.000 claims abstract description 204
- AFABGHUZZDYHJO-UHFFFAOYSA-N dimethyl butane Natural products CCCC(C)C AFABGHUZZDYHJO-UHFFFAOYSA-N 0.000 claims abstract description 102
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical compound CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 claims abstract description 68
- 238000000926 separation method Methods 0.000 claims abstract description 55
- 238000010992 reflux Methods 0.000 claims abstract description 54
- 239000007791 liquid phase Substances 0.000 claims description 104
- 239000007788 liquid Substances 0.000 claims description 35
- 238000000605 extraction Methods 0.000 claims description 31
- 239000002994 raw material Substances 0.000 claims description 23
- 238000001816 cooling Methods 0.000 claims description 18
- 238000002156 mixing Methods 0.000 claims description 16
- 238000005192 partition Methods 0.000 claims description 14
- 239000012071 phase Substances 0.000 claims description 13
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 12
- 239000005977 Ethylene Substances 0.000 claims description 12
- 238000001833 catalytic reforming Methods 0.000 claims description 12
- 238000005336 cracking Methods 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 10
- 238000005086 pumping Methods 0.000 claims description 8
- 238000012546 transfer Methods 0.000 claims description 7
- 238000004821 distillation Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 238000005265 energy consumption Methods 0.000 abstract description 11
- 238000012856 packing Methods 0.000 description 11
- 239000000203 mixture Substances 0.000 description 9
- 239000000945 filler Substances 0.000 description 8
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 7
- 238000011160 research Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 238000009835 boiling Methods 0.000 description 4
- 238000011049 filling Methods 0.000 description 3
- RGSFGYAAUTVSQA-UHFFFAOYSA-N Cyclopentane Chemical compound C1CCCC1 RGSFGYAAUTVSQA-UHFFFAOYSA-N 0.000 description 2
- 150000001335 aliphatic alkanes Chemical class 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 238000004517 catalytic hydrocracking Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000284 extract Substances 0.000 description 2
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 150000001993 dienes Chemical class 0.000 description 1
- DMEGYFMYUHOHGS-UHFFFAOYSA-N heptamethylene Natural products C1CCCCCC1 DMEGYFMYUHOHGS-UHFFFAOYSA-N 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000001282 iso-butane Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G7/00—Distillation of hydrocarbon oils
- C10G7/12—Controlling or regulating
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- Water Supply & Treatment (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
The application discloses a process for separating naphtha, and belongs to the technical field of petrochemical industry. The embodiment of the application provides a process for separating naphtha, and the process can separate an isopentane component, an n-pentane component and heavy naphtha from naphtha by only one dividing wall tower, and compared with a two-tower separation process, the process reduces one tower and a tower top condenser, a reflux tank and a tower bottom reboiler which are matched with the tower top condenser, so that the equipment number and the occupied area are reduced, the investment cost is further reduced, and the energy consumption is reduced.
Description
Technical Field
The application relates to the technical field of petrochemical industry. In particular to a process for separating naphtha.
Background
The stable naphtha produced by the hydrocracking unit is traditionally sent to a naphtha separation tower to be cut into light naphtha and heavy naphtha, wherein the light naphtha is mainly C5-C6 alkane (the content of C5 is more than or equal to 60wt percent). The research octane number of isopentane in light naphtha reaches 92, and the light naphtha can be used as a gasoline blending component. The research octane number of n-pentane is only 62, but the yield of "diene" (ethylene + propylene) as cracking raw material is far higher than that of isopentane, and the n-pentane can be used as ethylene cracking raw material, and heavy naphtha can be used as catalytic reforming raw material. Since naphtha obtained in a hydrocracking apparatus is a mixture, before the above components are fully utilized, an isopentane component, an n-pentane component, and heavy naphtha need to be separated from naphtha.
In the related art, naphtha is distilled through a naphtha separation tower to obtain light naphtha and heavy naphtha respectively. Then separating the light naphtha by an isopentane removing tower to respectively obtain an n-pentane component and an isopentane component. In the separation process, the isopentane component is condensed and refluxed through a tower top condenser and a reflux tank, and heavy naphtha is heated through a tower bottom reboiler.
However, in the related art, the isopentane component, the n-pentane component and the heavy naphtha can be separated from the naphtha by two towers, namely a naphtha separation tower and an isopentane removal tower, and matched equipment, so that the number of the used equipment is large, the occupied area is large, and the investment cost is high.
Disclosure of Invention
The embodiment of the application provides a process for separating naphtha, which can reduce the investment cost. The specific technical scheme is as follows:
the embodiment of the application provides a process for separating naphtha, which comprises the following steps:
introducing naphtha into a bulkhead tower, controlling the tower top operating temperature of the bulkhead tower to be 50-60 ℃, the operating pressure to be 0.2-0.3 MPa, and the tower bottom operating temperature of the bulkhead tower to be 130-160 ℃, and separating the naphtha through the bulkhead tower at the tower top operating temperature, the operating pressure and the tower bottom operating temperature; the dividing wall column comprises: the separation section and the extraction section are separated by a vertical partition plate; the naphtha comprises: an isopentane component, an n-pentane component, and a heavy naphtha;
separating an isopentane component from the top of the common rectification section, cooling to obtain a liquid-phase isopentane component, refluxing a part of the liquid-phase isopentane component to the common rectification section, outputting the other part of the liquid-phase isopentane component as a gasoline blending component, and allowing the part of the liquid-phase isopentane component to be in contact with a gas phase in the common rectification section for mass transfer;
the n-pentane component is extracted from a side line extraction port of the extraction section, and is cooled and then output as an ethylene cracking raw material;
and separating liquid-phase heavy naphtha from the bottom of the common stripping section, heating a part of the liquid-phase heavy naphtha, returning the heated part of the liquid-phase heavy naphtha to the tower bottom of the bulkhead tower, cooling the other part of the liquid-phase heavy naphtha, and outputting the cooled part of the liquid-phase heavy naphtha as a catalytic reforming raw material.
In a possible implementation manner, the separating the isopentane component from the top of the common rectification section, cooling to obtain an isopentane component in a liquid phase, refluxing a portion of the isopentane component in the liquid phase to the common rectification section, and outputting another portion of the isopentane component in the liquid phase as a gasoline blending component includes:
the isopentane component enters a condenser through an overhead distillation pipeline, and the isopentane component is cooled through the condenser to obtain the liquid-phase isopentane component;
when the temperature of the isopentane component in the liquid phase is not greater than a first temperature set value, introducing the isopentane component in the liquid phase into a reflux tank;
and pumping out the isopentane component of the liquid phase in the reflux tank through a first reflux pump, after pressurization, refluxing the isopentane component of one part of the liquid phase to the public rectification section through a first reflux pipeline, and outputting the isopentane component of the other part of the liquid phase as a gasoline blending component.
In another possible implementation, the process further includes:
detecting a first temperature at the top of the dividing wall column;
controlling a first flow rate of the portion of the liquid phase of the isopentane component refluxed to the common rectification section based on the first temperature.
In another possible implementation, the process further includes:
and pumping out the isopentane component of the liquid phase at the bottom of the public rectification section through a second reflux pump, and respectively returning the isopentane component of the liquid phase to the separation section and the extraction section through a second reflux pipeline and a third reflux pipeline according to the ratio of 0.5: 1-1: 1.
In another possible implementation, the process further includes:
detecting a first liquid level at the bottom of the common rectification section;
controlling a second flow of isopentane component back to the liquid phase in the separation section and a third flow of isopentane component back to the liquid phase in the withdrawal section according to the first liquid level.
In another possible implementation manner, the separating the liquid-phase heavy naphtha from the bottom of the common stripping section, heating a part of the liquid-phase heavy naphtha, returning the heated part of the liquid-phase heavy naphtha to the bottom of the dividing wall column, cooling another part of the liquid-phase heavy naphtha, and outputting the cooled part of the liquid-phase heavy naphtha as the catalytic reforming raw material includes:
separating liquid-phase heavy naphtha from the bottom of the common stripping section, heating a part of the liquid-phase heavy naphtha by a reboiler to obtain gas-liquid two-phase mixed heavy naphtha, and returning the gas-liquid two-phase mixed heavy naphtha to the tower bottom of the dividing wall tower;
pumping the other part of the liquid-phase heavy naphtha by a tower bottom pump, introducing the heavy naphtha into a heat exchanger, using the heavy naphtha as a heat source to heat the naphtha which does not enter the partition tower to a second temperature set value, and outputting the naphtha as a catalytic reforming raw material after cooling;
said passing naphtha to a divided wall column comprising:
and introducing the naphtha with the second temperature set value heated by the heat exchanger into the dividing wall tower.
In another possible implementation manner, the reflux ratio is 3-15.
In another possible implementation, the side draw is located at a height of 15% to 35% of the withdrawal section.
In another possible implementation manner, the ratio of the cross-sectional areas of the separation section and the extraction section is 1:1 to 2: 1.
In another possible implementation manner, the common rectification section comprises 10-16 theoretical plates, the separation section comprises 44-73 theoretical plates, the extraction section comprises 44-73 theoretical plates, and the common stripping section comprises 7-11 theoretical plates.
The technical scheme provided by the embodiment of the application has the following beneficial effects:
the embodiment of the application provides a process for separating naphtha, and the process can separate an isopentane component, an n-pentane component and heavy naphtha from naphtha by only one dividing wall tower, and compared with a two-tower separation process, the process reduces one tower and a tower top condenser, a reflux tank and a tower bottom reboiler which are matched with the tower top condenser, the reflux tank and the tower bottom reboiler, so that the number of equipment and the occupied area are reduced, and the investment cost is further reduced.
Drawings
FIG. 1 is a flow diagram of a process for separating naphtha as provided in an embodiment of the present application;
fig. 2 is a schematic diagram of an apparatus for separating naphtha according to an embodiment of the present application.
The reference numerals denote:
1-a partition tower, 2-a condenser, 3-a reflux tank, 4-a control system, 5-a first reflux pump,
6-a second reflux pump, 7-a side pump, 8-a reboiler, 9-a tower bottom pump, 10-a heat exchanger,
101-common rectification section, 102-common stripping section, 103-separation section, 104-extraction section,
105-vertical partition, 401-temperature-flow cascade control loop,
402-a first level-flow cascade control loop, 403-a second level-flow cascade control loop,
404-pressure control loop, 405-third level-flow cascade control loop.
Detailed Description
In order to make the technical solutions and advantages of the present application more clear, the following describes the embodiments of the present application in further detail.
The present application provides a process for separating naphtha, referring to fig. 1, the process comprising:
step 101: introducing naphtha into a bulkhead tower, controlling the tower top operating temperature of the bulkhead tower to be 50-60 ℃, the operating pressure to be 0.2-0.3 MPa, and the tower bottom operating temperature of the bulkhead tower to be 130-160 ℃, and separating the naphtha through the bulkhead tower at the tower top operating temperature, the operating pressure and the tower bottom operating temperature.
In the examples of the present application, the naphtha mainly comprises an isopentane component, an n-pentane component and a heavy naphtha, wherein the isopentane component, the n-pentane component and the heavy naphtha are all mixtures, and the isopentane component mainly comprises isopentane and possibly comprises small amounts of isobutane, n-butane and n-pentane. The n-pentane component comprises primarily n-pentane, and may also include minor amounts of cyclopentane and the isomeric carbon six. Heavy naphtha comprises mainly paraffins with a number of carbon atoms greater than 7 and may also include small amounts of cyclohexane and the isomeric six carbon atoms.
In the embodiment of the present application, the dividing wall column 1 includes: a common rectification section 101 at the top of the divided wall column 1, a common stripping section 102 at the bottom of the divided wall column 1, and a separation section 103 and a withdrawal section 104 at the middle of the divided wall column 1, the separation section 103 and the withdrawal section 104 being separated by a vertical partition 105.
In one possible implementation, the naphtha is first fed into the separation section 103 of the divided wall column 1 and is pre-separated in the separation section 103.
In one possible implementation, the naphtha entering the divided wall column 1 is naphtha heated by the heat exchanger 10 and brought to the second temperature setpoint. The second temperature setting value may be set and changed as needed, and is not particularly limited in the embodiment of the present application. For example, the second temperature setting is 115 ℃ to 125 ℃.
In a possible implementation manner, the cross-sectional areas of the separation section 103 and the extraction section 104 separated by the vertical partition 105 can be set and modified as required, and are not particularly limited in the embodiment of the present application. For example, the ratio of the cross-sectional areas of the separation section 103 and the withdrawal section 104 is 1:1 to 2: 1.
It should be noted that in the examples of the present application, the operation pressure at the top of the column was absolute pressure.
Step 102: and separating the isopentane component from the top of the common rectification section, cooling to obtain a liquid-phase isopentane component, refluxing a part of the liquid-phase isopentane component to the common rectification section, and outputting the other part of the liquid-phase isopentane component as a gasoline blending component.
In the step, the public rectification section 101 comprises 10-16 theoretical plates, namely, 17-27 float valve trays or 3.4-4.4 m high packing can be adopted as an internal part.
This step can be realized by the following steps (1) to (3), including:
(1) and (3) allowing the isopentane component to enter a condenser through an overhead distillation pipeline, and cooling the isopentane component through the condenser to obtain a liquid-phase isopentane component.
In this step, referring to fig. 2, naphtha is fed into the separation section 103 of the dividing wall column 1, pre-separated in the separation section 103, and the isopentane component in gas phase is separated from the top of the common rectification section 101, and fed into the condenser 2 through the overhead line, and cooled in the condenser 2 to obtain the isopentane component in liquid phase.
The condensing medium may be set and modified as needed, and is not particularly limited in the embodiments of the present application. For example, the condensing medium may be water.
(2) And when the temperature of the isopentane component in the liquid phase is not greater than the first temperature set point, introducing the isopentane component in the liquid phase into the reflux drum.
In this step, the first temperature setting value may be set and changed as needed, and this is not particularly limited in the embodiment of the present application. For example, the first temperature set point is 45 ℃.
In a possible implementation, the volume of the reflux drum 3 can be set and modified as required, and in the embodiment of the present application, this is not particularly limited.
(3) And pumping the isopentane component of the liquid phase in the reflux tank through a first reflux pump, after pressurization, refluxing a part of the isopentane component of the liquid phase to a public rectification section through a first reflux pipeline, and outputting the other part of the isopentane component of the liquid phase as a gasoline blending component.
In this step, the isopentane component of the liquid phase is used to contact the gas phase in the common rectification section for mass transfer. The research octane number of the isopentane component of the other part of the gasoline blending component is not less than 90. The reflux ratio may be set and changed as needed, and is not particularly limited in the embodiments of the present application. For example, the reflux ratio is 3 to 15.
In one possible implementation, a first temperature at the top of the divided wall column 1 can be detected;
a first flow rate of a portion of the liquid phase of the isopentane component refluxed to the common rectification section 101 is controlled based on the first temperature.
In this implementation, a temperature-flow cascade control loop 401 may be provided between the top of the next-door column 1 and the first return line, the first flow being controlled by the control system 4 in dependence on the first temperature. The first flow rate may be increased when the first temperature is greater than the third temperature set point and may be decreased when the first temperature is less than the third temperature set point.
In one possible implementation, the isopentane component can be output through a first output line as a gasoline blending component. In this implementation, a second level of the isopentane component in reflux drum 3 can be detected;
controlling a fourth flow of the isopentane component output for the gasoline blending component based on the second level.
In this implementation, a second liquid level flow cascade control loop 403 may be provided between the reflux tank 3 and the first output line, and the control system 4 controls the fourth flow according to the second liquid level. And when the second liquid level is smaller than the second liquid level set value, the fourth flow is reduced.
In one possible implementation, a first liquid level at the bottom of common rectification section 101 may be detected;
a second flow rate of the isopentane component back to the liquid phase in separation section 103 and a third flow rate of the isopentane component back to the liquid phase in production section 104 are controlled based on the first liquid level.
In this implementation, a first level-flow cascade control loop 402 may be provided between the bottom of the common rectification section, the second return line, and the third return line, with the second flow and the third flow being controlled by the control system according to the first level. And when the first liquid level is less than the first liquid level set value, the second flow and the third flow are reduced.
In a possible implementation manner, the isopentane component in the liquid phase in the common rectification section 101 can be pumped out by the second reflux pump 6, and the isopentane component in the liquid phase is respectively returned to the separation section 103 and the extraction section 104 through the second reflux line and the third reflux line according to a ratio of 0.5: 1-1: 1.
In this implementation, the liquid phase of the common rectification section 101 is respectively refluxed to the separation section 103 and the extraction section 104. Wherein, the separation section 103 and the extraction section 104 both adopt a multi-section filling mode, the upper part of each section of filling is provided with a liquid distributor, and a liquid collector is arranged between the two sections of filling. The liquid distributor can uniformly distribute liquid in the filler layer, and the mass transfer efficiency of the filler is improved. The liquid collector can collect liquid after mass transfer.
In one possible implementation, a pressure control loop 404 may be provided between the top of the dividing wall column and the reflux drum, the pressure control loop 404 being made up of two parts, a pressure control valve and a differential pressure control valve. Wherein, the pressure control valve is positioned on the overhead distillation outlet line and between the condenser 2 and the overhead, and the differential pressure control valve is positioned on the overhead distillation pipeline secondary line. A first pressure of the isopentane component entering the condenser 2 is detected by a pressure control valve, and the amount of the isopentane component entering the overhead line side-line is controlled in accordance with the first pressure to increase or decrease the pressure in the reflux drum 3.
Step 103: and (3) extracting the n-pentane component from a side line extraction port of the extraction section, cooling and outputting the n-pentane component as an ethylene cracking raw material.
In the step, the extraction section 104 comprises 44-73 theoretical plates, namely, 73-122 floating valve trays or 15.2-32 m-high packing can be adopted as an internal part. In the step, the product output as the ethylene cracking raw material also comprises other substances besides the n-pentane, and the purity of the n-pentane in the product is more than 70 wt%.
The position of the side draw-out port on the withdrawal section 104 may be set and changed as needed, and is not particularly limited in the embodiment of the present application. For example, the side draw is located at 15% to 35% of the height of the withdrawal section 104.
It should be noted that when the side draw-off port is located within the height range, the content of n-pentane is high and the purity is high.
In a possible implementation mode, naphtha enters the separation section 103 to be pre-separated, liquid phase at the bottom of the common rectification section 101 flows back to the separation section 103 and the extraction section 104 according to a certain proportion, and all liquid phase at the bottom of the separation section 103 and the extraction section 104 enters the common stripping section 102. As can be seen from step 101, the temperature at the bottom of the column is higher than the temperature at the top of the column, and therefore the temperature in the common stripping section 102 is higher than the temperature in the common rectifying section 101. Because the temperature at the bottom of the tower is higher, light components (less than or equal to C6) in the common stripping section 102 respectively enter the separation section 103 and the extraction section 104, the concentration of n-pentane in the liquid phase at a certain height is the highest after the mass transfer and heat transfer between the gas phase entering the extraction section 104 and the liquid phase reflowing to the extraction section 104, the n-pentane is extracted from a side-draw outlet through a side-draw pump 7 and is output as an ethylene cracking raw material after being cooled.
It should be noted that the separation section 103 also includes 44 to 73 theoretical plates, i.e., 73 to 122 trays with float valves or 15.2 to 32 meters height packing can be used as the internal member.
Step 104: separating liquid-phase heavy naphtha from the bottom of the common stripping section, heating a part of the liquid-phase heavy naphtha, returning the heated part of the liquid-phase heavy naphtha to the bottom of the dividing wall tower, cooling the other part of the liquid-phase heavy naphtha, and outputting the cooled part of the liquid-phase heavy naphtha as a catalytic reforming raw material.
In this step, the common stripping section 102 comprises 7 to 11 theoretical plates, i.e., 12 to 18 float valve trays or 2.4 to 5 meters high packing can be used as internals.
This step can be realized by the following steps (1) to (2), including:
(1) separating liquid-phase heavy naphtha from the bottom of the common stripping section 102, heating a part of the liquid-phase heavy naphtha by a reboiler 8 to obtain gas-liquid two-phase mixed heavy naphtha, and returning the gas-liquid two-phase mixed heavy naphtha to the bottom of the dividing wall column.
In this step, the heavy naphtha in which the gas phase and the liquid phase are mixed is returned to the column bottom, the gas phase moves upward, and the liquid phase falls to the bottom of the column.
In a possible implementation manner, the type of the reboiler 8 may be set and changed as needed, and in the embodiment of the present application, this is not particularly limited. For example, the reboiler 8 is a thermosyphon reboiler. The thermosiphon reboiler may be vertical or horizontal, and is not particularly limited thereto.
(2) And pumping the other part of the liquid-phase heavy naphtha by a tower bottom pump 9, introducing the heavy naphtha into a heat exchanger 10, using the heavy naphtha as a heat source to heat the naphtha which does not enter the partition tower 1 to a second temperature set value, cooling the naphtha and outputting the naphtha as a catalytic reforming raw material.
In the step, the other part of liquid-phase heavy naphtha is pumped out through the tower bottom pump 9 and enters the heat exchanger 10, and the part of heavy naphtha has higher temperature, so that the part of heavy naphtha can be used as a heat source to heat the naphtha to a second temperature set value, and meanwhile, the part of heavy naphtha has a cooling effect on the naphtha, and the energy consumption is saved.
Accordingly, prior to passing the naphtha to the divided wall column 1, the naphtha is passed to a heat exchanger 10 and, while the other portion of the liquid phase heavy naphtha is heated in the heat exchanger 10 to a second temperature setpoint, the naphtha at the second temperature setpoint is passed to the divided wall column 1.
In the examples of this application, the cooled heavy naphtha has a first boiling point greater than 80 ℃.
In one possible implementation, a third liquid level at the bottom of the common stripping section 102 may be detected;
a fifth flow of heavy naphtha into heat exchanger 10 is controlled based on the third level.
In this implementation, the heavy naphtha may be passed to heat exchanger 10 through a second output line. Accordingly, a third level-flow cascade control loop 405 may be provided between the bottom of the common stripping section 102 and the second output line, with the fifth flow being controlled by the control system 4 according to the third level. And increasing the fifth flow when the third liquid level is greater than the third liquid level set value, and decreasing the fifth flow when the third liquid level is less than the third liquid level set value.
The embodiment of the application provides a process for separating naphtha, and the process can separate an isopentane component, an n-pentane component and heavy naphtha from naphtha by only one partition tower 1, and compared with a two-tower separation process, the process reduces one tower and a tower top condenser, a reflux tank and a tower bottom reboiler which are matched with the tower top condenser, the reflux tank and the tower bottom reboiler, so that the number of equipment and the occupied area are reduced, and the investment cost is further reduced.
In addition, because one tower and a tower top condenser, a reflux tank and a tower bottom reboiler which are matched with the tower are reduced, the process provided by the embodiment of the application can also reduce energy consumption.
The technical solution of the present invention will be described in detail by specific examples.
For the naphtha composition and flow rates shown in table 1, the following separations were performed by different process parameters in example 1 and example 2.
TABLE 1 naphtha composition and flow
Example 1
Step 1: heating naphtha to 119 ℃ by a heat exchanger, introducing the heated naphtha into a partition wall tower, controlling the operation temperature of the top of the partition wall tower to be 56 ℃, the operation pressure to be 0.25MPa, and the operation temperature of the bottom of the partition wall tower to be 147 ℃, and separating the naphtha by the partition wall tower at the operation temperature of the top of the tower, the operation pressure and the operation temperature of the bottom of the tower.
The total column of the dividing wall column has 80 theoretical plates, and the internals adopt M352Y structured packing. Wherein, the height of the filler of the public rectification section is 4400mm, the height of the filler of the public stripping section is 3000mm, the separation section and the extraction section adopt 4 sections of fillers, and the height of each section of fillers is 4800 m. Meanwhile, the upper part of each section of the filler is provided with a liquid distributor, and a liquid collector is arranged between the two sections of the filler.
The diameter of the dividing wall tower is 3200mm, the tangent height of the tower is about 50000mm, and the ratio of the cross-sectional areas of the separation section and the extraction section is 1.56: 1.
Step 2: and separating the isopentane component from the top of the common rectification section, feeding the isopentane component into a condenser through an overhead distillation pipeline, cooling to 44.6 ℃ to obtain a liquid-phase isopentane component, and introducing the liquid-phase isopentane component into a reflux tank. After the pressure is pumped out by the first reflux pump and is increased, part of the isopentane component in the liquid phase returns to the public rectification section as reflux, and the other part of the isopentane component in the liquid phase is output as a gasoline blending component.
In this step, the reflux ratio was 7.16. The research octane number of the isopentane component output as a gasoline blending component was 90.37.
The isopentane component of the liquid phase in the common rectification section is pumped out by a second reflux pump and respectively returned to the liquid distributor of the separation section and the liquid distributor of the extraction section according to the ratio of 0.72: 1.
And 3, step 3: a side-draw outlet is arranged at the position of 25 percent of the height of the extraction section, and the n-pentane component is drawn out from the side-draw outlet through a side-draw pump and is used as an ethylene cracking raw material after being cooled.
In the step, the purity of the n-pentane in the n-pentane component serving as the raw material for cracking the ethylene is 90.27 wt%.
And 4, step 4: separating liquid-phase heavy naphtha from the bottom of the common stripping section, heating a part of the liquid-phase heavy naphtha, returning the heated part of the liquid-phase heavy naphtha to the tower bottom of the dividing wall tower, cooling the other part of the liquid-phase heavy naphtha, and outputting the cooled part of the liquid-phase heavy naphtha as a catalytic reforming raw material.
In this step, the initial boiling point of the heavy naphtha fed as a raw material for catalytic reforming is 82 ℃.
In this example, the composition and flow rate of each component obtained by separating naphtha by the process provided in the present application can be seen in table 2. As can be seen from table 2: the purity of the isopentane in the isopentane component output as the gasoline blending component is 87.11, and the purity of the n-pentane in the n-pentane component output as the ethylene cracking raw material is 90.27.
TABLE 2 compositions and flow rates of the components obtained by separation of naphtha
Referring to table 3, table 3 shows the energy consumption comparison between the process of this example and the two-column separation process of the related art under the same product and the same separation effect. Wherein, naphtha knockout tower among the relevant art totally 80 theoretical boards, remove isopentane tower totally 80 theoretical boards.
TABLE 3 energy consumption comparison of the Process used in this example with the Process used in the related art
As can be seen from table 3: the condenser duty and reboiler duty are lower in this example compared to the two column separation process. Therefore, on the premise of separating the same product and obtaining the same separation effect, the energy consumption of the embodiment is lower, and the production cost is lower.
Example 2
In the embodiment, the total column of the dividing wall column has 80 theoretical plates, and M352Y and a float valve tray are adopted as internals. Wherein, 22 layers of floating valve trays are adopted in the public rectifying section, M352Y regular packing is adopted in the public stripping section, the height of the packing is 3000mm, 4 sections of packing are adopted in the separation section and the extraction section, and the height of each section of packing is 4800 mm. And the upper part of each section of the packing is provided with a liquid distributor, and a liquid collector is arranged between the two sections of the packing.
The operating temperature at the bottom of the column was 136 ℃ and the reflux ratio was 6.48. The diameter of the dividing wall tower is 3200mm, the tangent height of the tower is 55000mm, the ratio of the cross-sectional areas of the separation section and the extraction section is 1.61:1, and the ratio of the isopentane components of the liquid phase returned to the separation section and the extraction section is 0.71: 1.
The remaining parameters are the same as those in embodiment 1, and are not described again here.
The compositions and flow rates of the components obtained in this example are shown in Table 4. As can be seen from table 4: the research octane number of the isopentane component obtained according to the process parameters in the embodiment reaches 90.34, the purity of n-pentane in the n-pentane component serving as the ethylene cracking raw material is 71.93 wt%, and the initial boiling point of heavy naphtha is 82 ℃.
TABLE 4 compositions and flow rates of the components obtained by separation of naphtha
Referring to table 5, table 5 shows the comparison of energy consumption of the two-tower separation process in the present embodiment and the related art under the same product and the same separation effect. Wherein, naphtha knockout tower among the relevant art totally 80 theoretical boards, remove isopentane tower totally 80 theoretical boards.
TABLE 5 energy consumption comparison of the Process used in this example with the Process used in the related art
As can be seen from table 5: the condenser duty and reboiler duty are lower in this example compared to the two column separation process. Therefore, on the premise of separating the same product and obtaining the same separation effect, the energy consumption of the embodiment is lower, and the production cost is lower.
To sum up, the process flow of naphtha separation through the next door tower that this application embodiment provided is simple, only needs a next door tower, sets up vertical baffle in the tower, and the naphtha lets in the separation section, then extracts isopentane component at the top of the tower, and its research octane number reaches more than 90, can regard as high octane number gasoline blending component. The side line of the extraction section extracts n-pentane component, wherein the content of n-pentane is not less than 70 wt%, and the n-pentane component can be used as an ethylene cracking raw material. Heavy naphtha components are extracted from the bottom of the tower, the initial boiling point of the heavy naphtha components is more than 80 ℃, the heavy naphtha components can be used as catalytic reforming raw materials, the naphtha components are optimized and utilized in hydrocarbon composition, and the purposes of oil, alkene and arene are achieved.
Compared with a two-tower separation process, the method reduces one rectifying tower, reduces the number of matched tower top condensation and tower bottom reboiling system equipment, reduces the investment of fixed equipment by about 15-30%, reduces the floor area by about 20-35%, and reduces the energy consumption in the production process by about 7-15%. The higher the C5 alkane content in the naphtha, the more the energy consumption is reduced.
The above description is only for facilitating the understanding of the technical solutions of the present application by those skilled in the art, and is not intended to limit the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A process for separating naphtha, the process comprising:
introducing naphtha into a bulkhead tower, controlling the tower top operating temperature of the bulkhead tower to be 50-60 ℃, the operating pressure to be 0.2-0.3 MPa, and the tower bottom operating temperature of the bulkhead tower to be 130-160 ℃, and separating the naphtha through the bulkhead tower at the tower top operating temperature, the operating pressure and the tower bottom operating temperature; the dividing wall column comprises: the separation section and the extraction section are separated by a vertical partition plate; the naphtha comprises: an isopentane component, an n-pentane component, and a heavy naphtha;
separating an isopentane component from the top of the common rectification section, cooling to obtain a liquid-phase isopentane component, refluxing a part of the liquid-phase isopentane component to the common rectification section, outputting the other part of the liquid-phase isopentane component as a gasoline blending component, and allowing the part of the liquid-phase isopentane component to be in contact with a gas phase in the common rectification section for mass transfer;
the n-pentane component is extracted from a side line extraction port of the extraction section, and is cooled and then output as an ethylene cracking raw material;
and separating liquid-phase heavy naphtha from the bottom of the common stripping section, heating part of the liquid-phase heavy naphtha, returning the heated part of the liquid-phase heavy naphtha to the tower bottom of the dividing wall tower, cooling the other part of the liquid-phase heavy naphtha, and outputting the cooled part of the liquid-phase heavy naphtha as a catalytic reforming raw material.
2. The process of claim 1, wherein the separating the isopentane component from the top of the common rectification section, cooling to obtain a liquid-phase isopentane component, refluxing a portion of the liquid-phase isopentane component to the common rectification section, and outputting another portion of the liquid-phase isopentane component as a gasoline blending component comprises:
the isopentane component enters a condenser through an overhead distillation pipeline, and the isopentane component is cooled through the condenser to obtain the liquid-phase isopentane component;
when the temperature of the isopentane component in the liquid phase is not greater than a first temperature set value, introducing the isopentane component in the liquid phase into a reflux tank;
and pumping out the isopentane component of the liquid phase in the reflux tank through a first reflux pump, after pressurization, refluxing the isopentane component of one part of the liquid phase to the public rectification section through a first reflux pipeline, and outputting the isopentane component of the other part of the liquid phase as a gasoline blending component.
3. The process of claim 2, further comprising:
detecting a first temperature at the top of the dividing wall column;
controlling a first flow rate of the portion of the liquid phase of the isopentane component refluxed to the common rectification section based on the first temperature.
4. The process of claim 1, further comprising:
and pumping out the isopentane component of the liquid phase at the bottom of the public rectification section through a second reflux pump, and respectively returning the isopentane component of the liquid phase to the separation section and the extraction section through a second reflux pipeline and a third reflux pipeline according to the ratio of 0.5: 1-1: 1.
5. The process of claim 4, further comprising:
detecting a first liquid level at the bottom of the common rectification section;
controlling a second flow of isopentane component back-flowed to the liquid phase in the separation section and a third flow of isopentane component back-flowed to the liquid phase in the withdrawal section according to the first liquid level.
6. The process of claim 1, wherein the separating the liquid phase heavy naphtha from the bottom of the common stripping section, heating a portion of the liquid phase heavy naphtha and returning it to the bottom of the divided wall column, cooling another portion of the liquid phase heavy naphtha and outputting it as a catalytic reforming feedstock comprises:
separating liquid-phase heavy naphtha from the bottom of the common stripping section, heating a part of the liquid-phase heavy naphtha by a reboiler to obtain gas-liquid two-phase mixed heavy naphtha, and returning the gas-liquid two-phase mixed heavy naphtha to the tower bottom of the dividing wall tower;
pumping the other part of the liquid-phase heavy naphtha by a tower bottom pump, introducing the heavy naphtha into a heat exchanger, taking the heavy naphtha as a heat source to heat naphtha which does not enter the partition wall tower to a second temperature set value, and outputting the naphtha as a catalytic reforming raw material after cooling;
said passing naphtha to a divided wall column comprising:
and introducing the naphtha with the second temperature set value heated by the heat exchanger into the dividing wall tower.
7. The process according to claim 2, wherein the reflux ratio is 3 to 15.
8. The process according to claim 1, characterized in that the side draw is located at a height of 15-35% of the withdrawal section.
9. The process of claim 1, wherein the ratio of the cross-sectional areas of the separation section and the production section is from 1:1 to 2: 1.
10. The process of claim 1, wherein the common rectification section comprises 10 to 16 theoretical plates, the separation section comprises 44 to 73 theoretical plates, the withdrawal section comprises 44 to 73 theoretical plates, and the common stripping section comprises 7 to 11 theoretical plates.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109401779A (en) * | 2018-08-09 | 2019-03-01 | 天津大学 | A kind of method and apparatus using next door tower cutting F- T synthesis light oil |
| CN209113783U (en) * | 2018-11-26 | 2019-07-16 | 山东海成石化工程设计有限公司 | A kind of separation system using divided wall column separating high-purity isopentane and pentane |
-
2021
- 2021-01-08 CN CN202110026202.3A patent/CN114736093A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109401779A (en) * | 2018-08-09 | 2019-03-01 | 天津大学 | A kind of method and apparatus using next door tower cutting F- T synthesis light oil |
| CN209113783U (en) * | 2018-11-26 | 2019-07-16 | 山东海成石化工程设计有限公司 | A kind of separation system using divided wall column separating high-purity isopentane and pentane |
Non-Patent Citations (2)
| Title |
|---|
| 何玉樵等: "《化工过程控制及仪表》", vol. 1, 31 July 1991, 成都科技大学出版社, pages: 194 * |
| 南京林业大学主编: "《林产化工自动化及仪表》", vol. 1, 31 January 1990, 中国林业出版社, pages: 222 - 223 * |
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