CN110950733A - Separation device and method for methanol-to-olefin gas - Google Patents
Separation device and method for methanol-to-olefin gas Download PDFInfo
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- CN110950733A CN110950733A CN201811130571.1A CN201811130571A CN110950733A CN 110950733 A CN110950733 A CN 110950733A CN 201811130571 A CN201811130571 A CN 201811130571A CN 110950733 A CN110950733 A CN 110950733A
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- 238000000926 separation method Methods 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims description 22
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims abstract description 114
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims abstract description 114
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims abstract description 78
- 239000005977 Ethylene Substances 0.000 claims abstract description 78
- 238000011084 recovery Methods 0.000 claims abstract description 63
- 230000002745 absorbent Effects 0.000 claims abstract description 46
- 239000002250 absorbent Substances 0.000 claims abstract description 46
- 239000002904 solvent Substances 0.000 claims abstract description 37
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 claims abstract description 24
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 claims abstract description 24
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 128
- 239000007789 gas Substances 0.000 claims description 69
- 239000012071 phase Substances 0.000 claims description 49
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 46
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 45
- 150000001336 alkenes Chemical class 0.000 claims description 27
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 claims description 27
- 239000001294 propane Substances 0.000 claims description 24
- 239000000047 product Substances 0.000 claims description 22
- 238000005406 washing Methods 0.000 claims description 20
- 238000010791 quenching Methods 0.000 claims description 18
- 239000002699 waste material Substances 0.000 claims description 17
- 239000003513 alkali Substances 0.000 claims description 16
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims description 14
- 239000007795 chemical reaction product Substances 0.000 claims description 12
- 230000000171 quenching effect Effects 0.000 claims description 12
- 239000002737 fuel gas Substances 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 239000007788 liquid Substances 0.000 claims description 8
- 239000007791 liquid phase Substances 0.000 claims description 8
- 238000009835 boiling Methods 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- 239000003518 caustics Substances 0.000 claims 2
- 238000005265 energy consumption Methods 0.000 abstract description 9
- 238000005191 phase separation Methods 0.000 abstract description 2
- 229910052799 carbon Inorganic materials 0.000 description 14
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 13
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 12
- 239000003507 refrigerant Substances 0.000 description 8
- 230000008569 process Effects 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- -1 ethylene, propylene Chemical group 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000008213 purified water Substances 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 238000005057 refrigeration Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000004523 catalytic cracking Methods 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
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- 239000011521 glass Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000004230 steam cracking Methods 0.000 description 1
- 229930195735 unsaturated hydrocarbon Natural products 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
- 239000002918 waste heat Substances 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
- C07C7/11—Purification; Separation; Use of additives by absorption, i.e. purification or separation of gaseous hydrocarbons with the aid of liquids
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/005—Processes comprising at least two steps in series
-
- 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
-
- 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
- Y02P30/00—Technologies relating to oil refining and petrochemical industry
- Y02P30/40—Ethylene production
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- Oil, Petroleum & Natural Gas (AREA)
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a separation device and a separation method for methanol-to-olefin gas, wherein the methanol-to-olefin gas is pretreated by a pretreatment component (1), phase separation is carried out in a separator (2), condensate is sent to a condensate dryer (3), gas phase is sent to a first gas phase dryer (4), the gas phase is sent to a deethanizer (5) after being dried, the gas phase at the top of the deethanizer (5) is separated by a demethanizer (6), a solvent recovery tower (7), an acetylene converter (8) and an ethylene rectifying tower (9) to obtain ethylene, and the gas phase at the bottom of the deethanizer (5) is separated by a depropanizer (10) and a propylene rectifying tower (11) to obtain propylene. The circulating loop of the absorbent is a demethanizer (6), a solvent recovery tower (7) and a demethanizer (6), the circulating loop is short, a deethanizer (5) and a propylene rectifying tower (11) are not involved, and the load, the energy consumption and the equipment investment of the deethanizer (5) and the propylene rectifying tower (11) are effectively reduced.
Description
Technical Field
The invention relates to the technical field of petrochemical industry, in particular to a device and a method for separating methanol-to-olefin gas.
Background
In recent years, although the olefin production at home and abroad shows a trend of diversification, a non-steam cracking hydrocarbon production method represented by Methanol To Olefin (MTO) is still an important method for producing olefins. The methanol-to-olefin is a chemical process technology for producing low-carbon olefin by using coal-based or natural gas-based synthetic methanol as a raw material and by means of a fluidized bed reaction form similar to a catalytic cracking device, and main products of the technology are ethylene, propylene and the like.
The separation scheme currently used most extensively for MTO gases is the rums depropanization process scheme. In the process, reaction gas enters a depropanizing tower from an MTO reactor, a bottom material flow of the depropanizing tower is sent to a debutanizing tower to separate out mixed C4The component, the overhead of the depropanizing tower flows through a demethanizer to remove the H component and C1Sending the components to a deethanizer, sending the tower top material stream of the deethanizer to an ethylene rectifying tower to separate ethylene, and sending the tower bottom material stream of the deethanizer to propyleneThe rectifying tower separates out propylene. The process is characterized in that: propylene is used as refrigerant, the method for absorbing the intercooled oil is utilized at the top of the demethanizer, and the tower bottom C of a partial deethanizer is adopted3The distillate and the propane at the bottom of the propylene rectifying tower are used as an absorbent to reduce the loss of ethylene.
In the process of implementing the invention, the inventor finds that at least the following problems exist in the prior art:
because the absorption method of the intercooled oil utilized at the top of the demethanizer in the gas separation process in the prior art adopts the tower bottom C of part of the deethanizer3The fraction and the propane at the bottom of the propylene rectifying tower are used as an absorbent to recover ethylene, and the absorbent is separated from the bottom of the demethanizer and then sent to a deethanizer, and is separated from the bottom of the deethanizer and sent to the propylene rectifying tower, and is finally separated from the bottom of the propylene rectifying tower and then returned to the top of the demethanizer, that is, the circulation loop of the absorbent is the demethanizer-deethanizer-propylene rectifying tower-demethanizer, and the circulation loop is long, so that the load and energy consumption of the demethanizer, the deethanizer and the propylene rectifying tower are increased, and the operation of a separation unit in the circulation loop is easy to be unstable.
Disclosure of Invention
In view of the above, the invention provides a separation device and a separation method for methanol-to-olefin gas, so as to solve the problem of long absorbent circulation loop in the prior art, and reduce the load, energy consumption and equipment investment of a deethanizer and a propylene rectifying tower.
Specifically, the method comprises the following technical scheme:
in one aspect, an embodiment of the present invention provides a Methanol To Olefin (MTO) gas separation apparatus, where the apparatus includes: a pretreatment component, a separator, a condensate dryer, a first gas phase dryer, a deethanizer, a demethanizer, a solvent recovery tower, an acetylene converter, an ethylene rectifying tower, a depropanizer, a propylene rectifying tower and a debutanizer, wherein,
the pretreatment assembly is communicated with an inlet of the separator, a gas phase outlet of the separator is communicated with an inlet of the first gas phase dryer, a condensate outlet of the separator is communicated with an inlet of the condensate dryer, the condensate dryer is communicated with a liquid phase inlet of the deethanizer, an outlet of the first gas phase dryer is communicated with a gas phase inlet of the deethanizer, a tower top outlet of the deethanizer is communicated with a tower body inlet of the demethanizer, and a tower top outlet of the demethanizer is communicated with a fuel gas collector;
a tower bottom outlet of the demethanizer is communicated with an inlet of the solvent recovery tower, a tower bottom outlet of the solvent recovery tower is communicated with a tower top inlet of the demethanizer, a tower top outlet of the solvent recovery tower is communicated with an inlet of the acetylene converter, an outlet of the acetylene converter is communicated with an inlet of the ethylene rectifying tower, a tower top outlet of the ethylene rectifying tower is communicated with an ethylene collector, and a tower bottom outlet of the ethylene rectifying tower is communicated with an ethane collector;
the outlet at the bottom of the deethanizer is communicated with the inlet of the depropanizer, the outlet at the top of the depropanizer is communicated with the inlet of the propylene rectifying tower, the outlet at the top of the propylene rectifying tower is communicated with the propylene collector, and the outlet at the bottom of the propylene rectifying tower is communicated with the propane collector;
the tower bottom outlet of the depropanizer is communicated with the inlet of the debutanizer, the tower top outlet of the debutanizer is communicated with a component collector of C4, and the tower bottom outlet of the debutanizer is communicated with a component collector above C5 and C5.
Optionally, the pretreatment component comprises a quench tower, a water stripper, a methanol recovery tower, a first compressor section, a second compressor section, a water washing tower, a third compressor section, an alkaline washing tower and a waste lye pretreatment tower;
the inlet of the quench tower is communicated with the methanol-to-olefin reactor, the outlet of the top of the quench tower is communicated with the inlet of the methanol recovery tower, the outlet of the top of the methanol recovery tower is communicated with the inlet of the first section of the compressor, the outlet of the first section of the compressor is communicated with the inlet of the second section of the compressor, the outlet of the second section of the compressor is communicated with the inlet of the water washing tower, the outlet of the water washing tower is communicated with the inlet of the third section of the compressor, the outlet of the third section of the compressor is communicated with the inlet of the alkaline washing tower, and the outlet of the top of the alkaline washing tower is communicated with the inlet of the separator;
the outlet of the tower bottom of the alkaline washing tower is communicated with the inlet of the waste alkali liquor pretreatment tower, and the outlet of the waste alkali liquor pretreatment tower is communicated with a waste alkali liquor collector;
the outlet at the bottom of the quenching tower is communicated with the inlet of the water stripping tower, the outlet at the bottom of the methanol recovery tower is communicated with the inlet of the water stripping tower, and the outlet of the water stripping tower is communicated with a water collector;
optionally, the depropanizer comprises a high pressure depropanizer and a low pressure depropanizer;
the tower bottom outlet of the deethanizer is communicated with the inlet of the high-pressure depropanizer, and the tower top outlet of the high-pressure depropanizer is communicated with the inlet of the propylene rectifying tower;
the tower bottom outlet of the high-pressure depropanizing tower is communicated with the inlet of the low-pressure depropanizing tower, and the tower bottom outlet of the low-pressure depropanizing tower is communicated with the inlet of the debutanizing tower.
Optionally, the apparatus further comprises: a heat exchanger;
the tower bottom outlet of the high-pressure depropanizing tower is communicated with the inlet of the low-pressure depropanizing tower through the heat exchanger;
and the tower top outlet of the low-pressure depropanizing tower is communicated with the inlet of the high-pressure depropanizing tower through the heat exchanger.
Optionally, the propylene rectification column comprises a first propylene rectification column and a second propylene rectification column;
the tower top outlet of the high-pressure depropanizing tower is communicated with the inlet of the first propylene rectifying tower, and the tower top outlet of the first propylene rectifying tower is communicated with the propylene collector;
the tower bottom outlet of the first propylene rectifying tower is communicated with the inlet of the second propylene rectifying tower, and the tower bottom outlet of the second propylene rectifying tower is communicated with the propane collector;
and the tower top outlet of the second propylene rectifying tower is communicated with the inlet of the first propylene rectifying tower.
Optionally, the apparatus further comprises: a compressor four section;
the compressor four sections are arranged between the deethanizer and the demethanizer.
Optionally, the apparatus further comprises: a second gas phase dryer;
the second gas phase dryer is disposed between the acetylene converter and the ethylene rectification column.
Optionally, a middle boiler and a reboiler are arranged in the ethylene rectifying tower;
the middle boiling device is arranged at the theoretical plate of 80-110 th layer from the top to the bottom of the ethylene rectifying tower;
the reboiler is arranged at the bottom of the ethylene rectifying tower.
Optionally, the ethylene rectifying tower is provided with a side line on theoretical plates at 2-10 th layers from the top to the bottom of the tower, and the side line is communicated with the ethylene collector.
In another aspect, an embodiment of the present invention further provides a method for separating methanol to olefin gas, where the method includes:
pretreating a reaction product of a methanol-to-olefin reactor, and then sending the pretreated reaction product into a separator for gas-liquid separation to obtain a gas-phase product and a condensate product;
feeding the gas-phase product into a first gas-phase dryer for drying, and then feeding the gas-phase product into a deethanizer to obtain components below C2 and C2 at the top of the tower and components above C3 and C3 at the bottom of the tower;
feeding the components with the carbon number of 2 and the carbon number of 2 at the top of the tower and the absorbent into a demethanizer to obtain a mixture of fuel gas at the top of the tower and C2 components and the absorbent at the bottom of the tower;
feeding the mixture of the C2 component and the absorbent at the bottom of the tower into a solvent recovery tower to obtain the C2 component at the top of the tower and the absorbent at the bottom of the tower, and returning the absorbent at the bottom of the tower to the demethanizer again;
feeding the C2 component at the tower top into an acetylene converter for conversion, and then feeding the C2 component into an ethylene rectifying tower to obtain ethylene at the tower top and ethane at the tower bottom;
feeding the components with the C3 and the components with the C3 or more at the bottom of the tower into a depropanizing tower to obtain the components with the C3 at the top of the tower and the components with the C4 and the components with the C4 or more at the bottom of the tower;
feeding the C3 component at the top of the tower into a propylene rectifying tower to obtain propylene at the top of the tower and propane at the bottom of the tower;
and C4 grade components with the purity higher than C4 at the bottom of the tower are sent to a debutanizer to obtain C4 components at the top of the tower and C5 and components with the purity higher than C5 at the bottom of the tower.
Alternatively, the absorbent is propane.
Optionally, the overhead gauge pressure of the deethanizer is 1.6-2.2MPa, and the overhead temperature is-30 to-39 ℃.
Optionally, the top gauge pressure of the demethanizer is 2.5-3.5MPa, and the top temperature is-30 to-39 ℃.
Optionally, the tower top gauge pressure of the solvent recovery tower is 2.0-3.0MPa, and the tower top temperature is-10 to-30 ℃.
Optionally, the gauge pressure of the top of the ethylene rectifying tower is 1.0-2.0MPa, and the temperature of the top of the ethylene rectifying tower is-30 to-39 ℃.
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:
1. after the methanol-to-olefin gas is pretreated by the pretreatment component, phase separation is carried out in the separator, condensate is sent to the condensate dryer, gas phase is sent to the first gas phase dryer and is sent to the deethanizer after being dried, the gas phase at the top of the deethanizer is separated by the demethanizer, the solvent recovery tower, the acetylene converter and the ethylene rectifying tower to obtain ethylene, and the bottom of the deethanizer is separated by the depropanizer and the propylene rectifying tower to obtain propylene, so that the separation of the methanol-to-olefin gas is realized;
2. by arranging the solvent recovery tower, when the absorbent used in the demethanizer can be mixed with the C2 component at the bottom of the tower and enter the solvent recovery tower, the C2 component and the absorbent are separated in the solvent recovery tower, the C2 component is obtained at the top of the tower, the absorbent is obtained at the bottom of the tower, and the absorbent at the bottom of the tower can flow back to the demethanizer from the solvent recovery tower after being cooled, so that the recycling of the absorbent is realized.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a separation apparatus for methanol to olefin gas according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of another methanol-to-olefin gas separation apparatus according to an embodiment of the present invention;
fig. 3 is a flow chart of a method for separating methanol to olefin gas according to an embodiment of the present invention.
The reference numerals in the figures are denoted respectively by:
1-pretreatment component, 101-quench tower, 102-water stripper, 103-methanol recovery tower, 104-compressor first section, 105-compressor second section, 106-water washing tower, 107-compressor third section, 108-alkali washing tower, 109-waste lye pretreatment tower,
2-a separator is arranged in the middle of the device,
3-a condensate dryer, wherein the condensate dryer is connected with a condensate dryer,
4-a first gas-phase dryer,
5-a de-ethanizer, wherein,
6-a demethanizer, which is connected with a gas-liquid separator,
7-a solvent recovery tower, wherein the solvent recovery tower is connected with a solvent recovery tower,
an 8-acetylene converter, a reactor for converting acetylene,
9-a rectifying tower of ethylene, wherein,
10-depropanizer, 1001-high pressure depropanizer, 1002-low pressure depropanizer,
11-a propylene rectifying tower, 1101-a first propylene rectifying tower, 1102-a second propylene rectifying tower,
12-a debutanizer tower, wherein,
13-a collector of fuel gas, and,
14-an ethylene collector, wherein the ethylene collector is a hollow glass,
a 15-ethane collector, wherein the ethane collector is arranged on the lower portion of the methane tank,
16-a propylene collector, wherein the propylene collector is arranged on the upper portion of the propylene tank,
a 17-propane collector, wherein the propane is collected,
an 18-C4 component collector, wherein,
19-C5 and component collectors above C5,
a reactor for preparing olefin from 20-methanol,
21-a waste alkali liquor collector, wherein,
22-a water collector, wherein the water collector is arranged on the water tank,
23-a heat exchanger, the heat exchanger,
24-the four sections of the compressor are,
25-second gas phase dryer.
Detailed Description
Unless defined otherwise, all technical terms used in the examples of the present invention have the same meaning as commonly understood by one of ordinary skill in the art. In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
In a first aspect, an embodiment of the present invention provides a methanol to olefin (methanol to olefin) gas separation apparatus, as shown in fig. 1, the apparatus includes: the device comprises a pretreatment component 1, a separator 2, a condensate dryer 3, a first gas phase dryer 4, a deethanizer 5, a demethanizer 6, a solvent recovery tower 7, an acetylene converter 8, an ethylene rectifying tower 9, a depropanizer 10, a propylene rectifying tower 11 and a debutanizer 12.
The pretreatment component 1 is communicated with an inlet of a separator 2, a gas phase outlet of the separator 2 is communicated with an inlet of a first gas phase dryer 4, a condensate outlet of the separator 2 is communicated with an inlet of a condensate dryer 3, an outlet of the condensate dryer 3 is communicated with a liquid phase inlet of a deethanizer 5, an outlet of the first gas phase dryer 4 is communicated with a gas phase inlet of the deethanizer 5, a tower top outlet of the deethanizer 5 is communicated with a tower body inlet of a demethanizer 6, and a tower top outlet of the demethanizer 6 is communicated with a fuel gas collector 13;
the outlet at the bottom of the demethanizer 6 is communicated with the inlet of the solvent recovery tower 7, the outlet at the bottom of the solvent recovery tower 7 is communicated with the inlet at the top of the demethanizer 6, the outlet at the top of the solvent recovery tower 7 is communicated with the inlet of the acetylene converter 8, the outlet of the acetylene converter 8 is communicated with the inlet of the ethylene rectifying tower 9, the outlet at the top of the ethylene rectifying tower 9 is communicated with the ethylene collector 14, and the outlet at the bottom of the ethylene rectifying tower 9 is communicated with the ethane collector 15;
the outlet at the bottom of the deethanizer 5 is communicated with the inlet of the depropanizer 10, the outlet at the top of the depropanizer 10 is communicated with the inlet of the propylene rectifying tower 11, the outlet at the top of the propylene rectifying tower 11 is communicated with the propylene collector 16, and the outlet at the bottom of the propylene rectifying tower 11 is communicated with the propane collector 17;
the outlet of the bottom of the depropanizer 10 is communicated with the inlet of the debutanizer 12, the outlet of the top of the debutanizer 12 is communicated with the component collector 18 of C4, and the outlet of the bottom of the debutanizer 12 is communicated with the component collector 19 above C5 and C5.
It will be appreciated that the various components within the device communicate with one another via conduits.
The ethylene obtained in the ethylene rectifying column 9 is polymer-grade ethylene, and the propylene obtained in the propylene rectifying column 11 is polymer-grade propylene.
The operation principle of the methanol-to-olefin gas separation apparatus according to the embodiment of the present invention is described below:
the olefin mixed gas obtained by the reaction in the methanol-to-olefin reactor 20 is pretreated and then enters the separator 2 for gas-liquid separation to obtain a gas-phase component and a condensate component;
the gas phase components enter a first gas phase dryer 4 from an upper outlet of a separator 2 for gas drying, and then enter a deethanizer 5 to obtain components below C2 and C2 at the top of the tower and components above C3 and C3 at the bottom of the tower; the components below C2 and C2 at the top of the tower enter a demethanizer 6 from an outlet at the top of the deethanizer 5, an absorbent is added while the components below C2 and C2 are injected into the demethanizer 6, methane is removed by using an intercooled oil absorption method, fuel gas (hydrogen and methane) is obtained at the top of the demethanizer 6 and is collected by a fuel gas collector 13, and a mixture of the components below C2 and the absorbent is obtained at the bottom of the demethanizer 6;
the mixture of the C2 component and the absorbent at the bottom of the demethanizer 6 flows out from the outlet at the bottom of the demethanizer 6 and enters the solvent recovery tower 7, the C2 component and the absorbent are separated in the solvent recovery tower 7, the absorbent returns to the demethanizer 6 after being cooled at the bottom of the solvent recovery tower 7 and enters the demethanizer 6 from the inlet at the top of the demethanizer 6, the methane is removed by continuously utilizing an intercooled oil absorption method, and the recycling of the absorbent is realized;
the C2 component obtained from the top of the solvent recovery tower 7 enters an acetylene converter 8 for hydrotreating, then enters an ethylene rectifying tower 9 for separating ethylene, ethylene is obtained from the top of the ethylene rectifying tower 9 and is collected by an ethylene collector 14, and ethane is obtained from the bottom of the ethylene rectifying tower 9 and is collected by an ethane collector 15;
the components of C3 and above C3 at the bottom of the deethanizer 5 enter a depropanizer 9 to obtain a component of C3 at the top of the tower and a component of C4 and above C4 at the bottom of the tower, the component of C3 at the top of the tower enters a propylene rectifying tower 11, separated propylene is obtained from the top of the propylene rectifying tower 11 through the propylene rectifying tower 11 and is collected through a propylene collector 16, and separated propane is obtained at the bottom of the propylene rectifying tower 11 and is collected through a propane collector 17;
the components with the carbon number of 4 and more than carbon number of 4 obtained from the bottom of the depropanizing tower 9 enter a debutanizing tower, the components with the carbon number of 4 are obtained from the top of the debutanizing tower 12 and are collected by a component collector 18 with the carbon number of 4, and the components with the carbon number of 5 and more than carbon number of 5 obtained from the bottom of the debutanizing tower 12 and are collected by a component collector 19 with the carbon number of 5 and more than carbon number of 5.
The intercooled oil absorption process referred to herein is the use of a-40 c propylene refrigerant refrigeration in combination with a propane absorbent to reduce the loss of ethylene.
The absorbent can be one or more of C3, C4 or C5, preferably propane, and absorbs ethylene by a gas-liquid equilibrium principle so as to improve the recovery rate of ethylene; the propylene refrigerant is provided with three temperature grades of 7 ℃, 24 ℃ and 40 ℃.
Therefore, in the separation apparatus for methanol to olefin gas according to the embodiment of the present invention, the pretreatment module 1, the separator 2, the condensate dryer 3, the first gas phase dryer 4, the deethanizer 5, the demethanizer 6, the solvent recovery tower 7, the acetylene converter 8, the ethylene rectifying tower 9, the depropanizer 10, the propylene rectifying tower 11, and the debutanizer 12 are used to separate the methanol to olefin gas, and the circulation loop of the absorbent used in the demethanizer 6 is changed to the demethanizer 6, the solvent recovery tower 7, and the demethanizer 6, so that the circulation loop is shortened, the deethanizer 5 and the propylene rectifying tower 11 are not involved, and therefore, the load, the energy consumption, and the equipment investment of the deethanizer 5 and the propylene rectifying tower 11 can be effectively reduced, and the stability of the apparatus can be improved.
The following describes the structure of each part of the methanol to olefin gas separation apparatus according to the embodiment of the present invention:
the pretreatment module 1 is used for pretreating mixed gas obtained by preparing methanol into olefin, and specifically, the pretreatment module 1 comprises a quenching tower 101, a water stripping tower 102, a methanol recovery tower 103, a compressor first section 104, a compressor second section 105, a water washing tower 106, a compressor third section 107, an alkaline washing tower 108 and a waste lye pretreatment tower 109, as shown in fig. 2.
Wherein, the inlet of the quench tower 101 is communicated with the methanol-to-olefin reactor 20, the outlet of the top of the quench tower 101 is communicated with the inlet of the methanol recovery tower 103, the outlet of the top of the methanol recovery tower 103 is communicated with the inlet of the first section 104 of the compressor, the outlet of the first section 104 of the compressor is communicated with the inlet of the second section 105 of the compressor, the outlet of the second section 105 of the compressor is communicated with the inlet of the water scrubber 106, the outlet of the water scrubber 106 is communicated with the inlet of the third section 107 of the compressor, the outlet of the third section 107 of the compressor is communicated with the inlet of the alkaline tower 108, and the outlet of the top of the alkaline tower 108 is communicated;
the outlet of the tower bottom of the alkaline tower 108 is communicated with the inlet of the waste alkali liquor pretreatment tower 109, and the outlet of the waste alkali liquor pretreatment tower 109 is communicated with the waste alkali liquor collector 21;
the outlet of the bottom of the quenching tower 101 is communicated with the inlet of the water stripping tower 102, the outlet of the bottom of the methanol recovery tower 103 is communicated with the inlet of the water stripping tower 102, and the outlet of the water stripping tower 102 is communicated with the water collector 22;
according to the arrangement, olefin mixed gas obtained by reaction in the methanol-to-olefin reactor 20 enters the quenching tower 101 for heat recovery, then enters the methanol recovery tower 103 from the outlet of the top of the quenching tower 101 for methanol recovery, is compressed by the first section of compressor 104 and the second section of compressor 105, and then enters the water scrubber 106 for water washing to remove oxide impurities such as methanol, dimethyl ether and the like, and then enters the third section of compressor 107 for primary compression, and then enters the alkaline tower 108 to remove acidic gas such as carbon dioxide;
the waste alkali liquor in the alkaline tower 108 enters the waste alkali liquor pretreatment tower 109 through a tower bottom outlet of the alkaline tower 108, and is collected into the waste alkali liquor collector 21 after being pretreated by the waste alkali liquor pretreatment tower 109 for subsequent treatment or use;
the liquid phase cooled by the quenching tower 101 enters the water stripper 102 through the outlet at the bottom of the quenching tower 101, and the water stripper 102 strips out the hydrocarbon components in the water to obtain purified water, so that the outlet of the water stripper 102 can be communicated with the water collector 22 to collect the water.
It is understood that after the methanol recovery tower 103 recovers methanol, the liquid phase component can be further recovered, and purified water can also be obtained by communicating the outlet at the bottom of the methanol recovery tower 103 with the inlet of the water stripping tower 102.
The gas after cooling, compression, water washing and alkali washing, i.e. the pretreated gas, can be further separated.
As for the separator 2, the separator 2 functions to separate the components of the respective phases, and in the present embodiment, the separator 2 is a gas-liquid-water three-phase separator.
For the depropanizer 10, the depropanizer 10 functions to separate C3 from components above C4 and C4, and specifically, the depropanizer 10 includes a high pressure depropanizer 1001 and a low pressure depropanizer 1002, as shown in fig. 2.
Wherein, the outlet of the tower bottom of the deethanizer 5 is communicated with the inlet of the high-pressure depropanizer 1001, and the outlet of the tower top of the high-pressure depropanizer 1001 is communicated with the inlet of the propylene rectifying tower 11;
the outlet at the bottom of the high-pressure depropanizer 1001 is communicated with the inlet of the low-pressure depropanizer 1002, and the outlet at the bottom of the low-pressure depropanizer 1002 is communicated with the inlet of the debutanizer 12.
The temperature distribution and the refrigerant matching in the demethanizer 6 can be more reasonable by arranging the high-pressure depropanizer 1001 and the low-pressure depropanizer 1002; compared with a single depropanizing tower 10, the total load of the high-pressure depropanizing tower 1001 and the low-pressure depropanizing tower 1002 is lower, liquid phase discharging is not needed at the top of the high-pressure depropanizing tower 1001, the low-pressure steam consumption in a reboiler at the bottom of the low-pressure depropanizing tower 1002 is obviously reduced, and the energy consumption can be saved to a certain degree; in addition, the combination of the high-pressure depropanizer 1001 and the low-pressure depropanizer 1002 can reduce the problems of low separation efficiency and high separation load caused by polymer generation of unsaturated hydrocarbons (such as butadiene) with C4 and more than C4 in the depropanizer 10 and tower plate blockage due to scaling, thereby prolonging the operation period of the device.
Based on the high-pressure depropanizer 1001 and the low-pressure depropanizer 1002, the separation apparatus for methanol to olefin gas according to the embodiment of the present invention further includes: a heat exchanger 23.
Wherein, the outlet of the tower bottom of the high-pressure depropanizing tower 1001 is communicated with the inlet of the low-pressure depropanizing tower 1002 through a heat exchanger 23; the overhead outlet of the low pressure depropanizer 1002 communicates with the inlet of the high pressure depropanizer 1001 through heat exchanger 23 as shown in figure 2.
By arranging the heat exchanger 23, the hot stream at the bottom of the high-pressure depropanizer 1001 and the cold stream at the top of the low-pressure depropanizer 1002 can exchange heat with each other to meet the process requirements in the respective towers.
For the propylene rectification column 11, in order to better separate propylene from propane, the propylene rectification column 11 includes a first propylene rectification column 1101 and a second propylene rectification column 1102.
Wherein, the outlet of the high pressure depropanizing tower 1001 is communicated with the inlet of the first propylene rectifying tower 1101, and the outlet of the first propylene rectifying tower 1101 is communicated with the propylene collector 16;
the tower bottom outlet of the first propylene rectifying tower 1101 is communicated with the inlet of the second propylene rectifying tower 1102, and the tower bottom outlet of the second propylene rectifying tower 1102 is communicated with the propane collector 17;
the top outlet of the second propylene rectification column 1102 is in communication with the inlet of the first propylene rectification column 1101, as shown in fig. 2.
By arranging the first propylene rectifying tower 1101 and the second propylene rectifying tower 1102, the recovery rate of propylene can be improved after two times of rectification.
It will be appreciated that the propane obtained at the bottom of the second propylene rectification column 1102 may be sent to the propane recovery stage 17 or to the solvent recovery column 7 to make up for losses of absorbent.
In order to better realize the removal of methane, the separation device for methanol to olefin gas according to the embodiment of the present invention further includes: compressor four-stage 24, compressor four-stage 24 is disposed between deethanizer 5 and demethanizer 6, as shown in fig. 2.
The components of C2 and C2 flowing out of the top outlet of the deethanizer 5 can be compressed by the compressor four-stage 24 and then enter the demethanizer 6 for further demethanization.
In order to better separate ethylene and ethane, since the acetylene converter 8 performs conversion by hydrotreating, and the recovery rate of ethylene is improved, the separation apparatus for methanol to olefin gas according to the embodiment of the present invention further includes: a second gas phase dryer 25;
the second gas phase dryer 25 is disposed between the acetylene converter 8 and the ethylene rectifying column 9, as shown in fig. 2.
The product water converted by the acetylene converter 8 can be removed by the second gas phase dryer 25.
In order to further reduce the energy consumption of the apparatus, in the embodiment of the present invention, an intermediate boiler (not shown in the figure) and a reboiler (not shown in the figure) are provided in the ethylene rectification column 9.
Wherein, the middle boiling device is arranged at the theoretical plates of 80 th to 110 th layers from the top to the bottom in the ethylene rectifying tower 9, and the reboiler is arranged at the bottom of the ethylene rectifying tower 9.
By adopting the propylene refrigerant for heat supply in the middle boiling device and the reboiler, the waste heat can be effectively recovered, the using amount of the propylene refrigerant is reduced, the power consumption of the propylene refrigeration compressor is reduced, and the reduction of the energy consumption of the device is further realized.
For more convenient ethylene collection, the ethylene rectifying tower 9 is provided with a side line from the tower top to the theoretical plates at the 2 nd to 10 th layers at the tower bottom, and the side line is communicated with an ethylene collector 14, so that the ethylene can be collected.
In a second aspect, an embodiment of the present invention further provides a method for separating methanol to olefin gas, where a flow chart of the method is shown in fig. 3, and the method includes:
step 301: the reaction product of the methanol-to-olefin reactor 20 is pretreated and then sent to the separator 2 for gas-liquid separation to obtain a gas-phase product and a condensate product.
Specifically, the pretreatment of the reaction product of the methanol-to-olefin reactor 20 mainly comprises feeding the reaction product into a quenching tower 101 and a methanol recovery tower 103 for heat recovery and methanol recovery, compressing the reaction product by a first compressor section 104 and a second compressor section 105, feeding the reaction product into a water scrubber 106 for removing oxide impurities, compressing the reaction product by a third compressor section 107, and feeding the reaction product into an alkaline scrubber 108 for removing acid gases.
The separator 2 is a gas-liquid-water three-phase separator, and three phases can be separated in the separator 2.
Step 302: and respectively feeding the condensate product and the gas-phase product into a condensate dryer 3 and a first gas-phase dryer 4 for drying, and then feeding into a deethanizer 5 to obtain components below C2 and C2 at the top of the tower and components above C3 and C3 at the bottom of the tower.
Specifically, the overhead gauge pressure of the deethanizer 5 is 1.6-2.2MPa and the overhead temperature is-30 to-39 ℃ in the pressure and temperature settings, and preferably, the overhead gauge pressure of the deethanizer 5 is 1.6-2MPa and the overhead temperature is-30 to-38 ℃ so as to separate components below C2 and C2 and components above C3 and C3.
Step 303: the components with the top of C2 and the components with the bottom of C2 and the absorbent are sent to the demethanizer 6, so that the mixture of fuel gas at the top of the tower and the components with the bottom of C2 and the absorbent is obtained.
Specifically, in the pressure and temperature settings, the gauge pressure of the top of the demethanizer 6 is 2.5-3.5MPa, the temperature of the top of the demethanizer 6 is-30 to-39 ℃, and preferably, the gauge pressure of the top of the demethanizer 6 is 2.6-3.2MPa, and the temperature of the top of the demethanizer is-30 to-38 ℃.
The propane absorbent with the temperature of minus 30 ℃ to minus 38 ℃ is added at the top of the tower, and the ethylene is absorbed by utilizing the gas-liquid equilibrium principle.
Step 304: the mixture of the C2 component and the absorbent at the bottom is sent to the solvent recovery column 7 to obtain the C2 component at the top and the absorbent at the bottom, and the absorbent at the bottom is sent back to the demethanizer 6 again.
Specifically, in the pressure and temperature settings, the gauge pressure of the tower top of the solvent recovery tower 7 is 2.0-3.0MPa, the temperature of the tower top is-10 to-30 ℃, preferably, the gauge pressure of the tower top is 2.2-2.8MPa, the temperature of the tower top is-16 to-26 ℃, and the absorbent material flow recovered from the tower bottom is cooled to-30 to-38 ℃ and then is completely returned to the tower top of the demethanizer 6.
Step 305: c2 components at the top of the tower are sent into an acetylene converter 8 for conversion, and then sent into an ethylene rectifying tower 9 to obtain ethylene at the top of the tower and ethane at the bottom of the tower.
Specifically, the C2 component stream at the top of the column is hydrotreated by an acetylene converter 8 and then sent to an ethylene rectifying column 9 for separation of ethylene and ethane.
In the pressure and temperature settings, the gauge pressure of the top of the ethylene rectifying tower 9 is 1.0-2.0MPa, the temperature of the top of the tower is-30 to-39 ℃, preferably, the gauge pressure of the top of the tower is 1.2-1.8MPa, and the temperature of the top of the tower is-30 to-38 ℃.
In the structural arrangement, a polymerization-grade ethylene product is withdrawn through a side line at a theoretical plate of 2-10 layers which is inverted from the top to the bottom of the tower, and an ethane stream at the bottom of the tower is used as an ethane product or sent to a fuel gas system; the ethylene rectifying tower 9 is provided with a middle boiling device at the theoretical plate of 80 th-110 th layer from the top to the bottom of the tower, the material flow temperature of the position of the middle boiling device is-26 ℃ to-35 ℃, and a refrigerant of-24 ℃ is adopted for supplying heat; a reboiler at the bottom of the ethylene rectifying tower 9 adopts a refrigerant with the temperature of 7 ℃ for heat supply.
Step 306: the components of C3 and above C3 at the bottom are fed into a depropanizer 10 to obtain components of C3 at the top of the tower and components of C4 and above C4 at the bottom of the tower.
Specifically, since the depropanizer 10 comprises a high-pressure depropanizer 1001 and a low-pressure depropanizer 1002, the overhead gauge pressure of the high-pressure depropanizer 1001 is 1.8-2.3MPa, the overhead temperature is 40-80 ℃, preferably, the overhead pressure is 1.8-2.2MPa, and the overhead temperature is 40-60 ℃ in the settings of pressure and temperature; the pressure at the top of the low-pressure depropanizer 1002 is 0.5-1.0MPa, the temperature at the top of the tower is 8-30 ℃, preferably, the pressure at the top of the tower is 0.6-0.9MPa, and the temperature at the top of the tower is 10-20 ℃.
Wherein, the bottom stream of the high-pressure depropanizing tower 1001 and the top stream of the low-pressure depropanizing tower 1002 exchange heat through a heat exchanger 23, and the heat-exchanged streams are sent to the 2 nd to 12 th theoretical plates from the top to the bottom of the low-pressure depropanizing tower 1002, preferably the 3 rd to 10 th theoretical plates.
Step 307: the C3 component at the top of the column is sent to a propylene rectifying column 11 to obtain propylene at the top of the column and propane at the bottom of the column.
Specifically, because the propylene rectifying tower 11 comprises a first propylene rectifying tower 1101 and a second propylene rectifying tower 1102, in terms of pressure and temperature settings, the tower top gauge pressure of the second propylene rectifying tower 1002 is 1.5-2.0MPa, the tower top temperature is 40-50 ℃, polymerization-grade propylene is extracted from a tower top liquid phase, and a tower bottom stream is sent to the first propylene rectifying tower 1101. The first propylene rectification column 1101 overhead stream is returned to the second propylene rectification column 1102 and the bottoms propane stream is sent out of the plant or make up for absorbent losses in the solvent recovery column 7.
Step 308: the C4 grade components with the content of more than C4 at the bottom of the tower are sent to a debutanizer 12 to obtain C4 components at the top of the tower and C5 and components with the content of more than C5 at the bottom of the tower.
Specifically, in the settings of pressure and temperature, the gauge pressure at the top of the debutanizer 12 is 0.1-0.6MPa, the temperature at the top of the debutanizer is 40-50 ℃, the mixed C4 component of the liquid phase at the top of the debutanizer is sent out of a device or is sent into a subsequent C4 cracking unit, and the mixed components of C5 and more than C5 at the bottom of the debutanizer are sent out of the device.
According to verification, the method can reduce the comprehensive energy consumption by 3-5% compared with the prior general MTO olefin separation technology (mainly demethanization in an intermediate cooling oil absorption mode) on the premise of not increasing the equipment investment.
The ethylene product obtained by the invention conforms to the national standard GB/T7715-2014, the propylene product conforms to the national standard GB/T7716-2014, and the recovery rates of the ethylene and the propylene can be more than 99.6 percent.
In the separation method of the methanol-to-olefin gas, the reaction product of the methanol-to-olefin reactor 20 is pretreated and then sent to the separator 2 for gas-liquid separation, so that a gas-phase product and a condensate product are obtained; respectively feeding the condensate product and the gas-phase product into a condensate dryer 3 and a first gas-phase dryer 4 for drying, and then feeding into a deethanizer 5 to obtain components below C2 and C2 at the top of the tower and components above C3 and C3 at the bottom of the tower; feeding the components with the carbon number of 2 and the carbon number of 2 at the top of the tower and the absorbent into a demethanizer 6 to obtain a mixture of fuel gas at the top of the tower and the components with the carbon number of 2 and the absorbent at the bottom of the tower; sending the mixture of the C2 component and the absorbent at the bottom of the tower into a solvent recovery tower 7 to obtain the C2 component at the top of the tower and the absorbent at the bottom of the tower, and sending the absorbent at the bottom of the tower back to the demethanizer 6 again; c2 components at the top of the tower are sent into an acetylene converter 8 for conversion, and then sent into an ethylene rectifying tower 9 to obtain ethylene at the top of the tower and ethane at the bottom of the tower; feeding the components with the C3 and the components with the C3 and above into a depropanizer 10 at the bottom of the tower to obtain the components with the C3 at the top of the tower and the components with the C4 and the components with the C4 and above at the bottom of the tower; feeding the C3 component at the top of the tower into a propylene rectifying tower 11 to obtain propylene at the top of the tower and propane at the bottom of the tower; the components of C4 grade and above C4 at the bottom of the tower are sent into a debutanizer 12 to obtain C4 components at the top of the tower and C5 and above C5 components at the bottom of the tower, so that the separation of the olefin gas prepared from methanol is realized, meanwhile, a circulation loop of an absorbent used in a demethanizer 6 is changed into the demethanizer 6, a solvent recovery tower 7 and the demethanizer 6, the circulation loop is shortened, the deethanizer 5 and a propylene rectifying tower 11 are not involved, the load, the energy consumption and the equipment investment of the deethanizer 5 and the propylene rectifying tower 11 can be effectively reduced, and the stability of the device is improved.
The above description is only for facilitating the understanding of the technical solutions of the present invention by those skilled in the art, and is not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A separation apparatus for methanol to olefin gas, comprising: a pretreatment component (1), a separator (2), a condensate dryer (3), a first gas phase dryer (4), a deethanizer (5), a demethanizer (6), a solvent recovery tower (7), an acetylene converter (8), an ethylene rectifying tower (9), a depropanizer (10), a propylene rectifying tower (11) and a debutanizer (12), wherein,
the pretreatment assembly (1) is communicated with an inlet of the separator (2), a gas phase outlet of the separator (2) is communicated with an inlet of the first gas phase dryer (4), a condensate outlet of the separator (2) is communicated with an inlet of the condensate dryer (3), the condensate dryer (3) is communicated with a liquid phase inlet of the deethanizer (5), an outlet of the first gas phase dryer (4) is communicated with a gas phase inlet of the deethanizer (5), a tower top outlet of the deethanizer (5) is communicated with a tower body inlet of the demethanizer (6), and a tower top outlet of the demethanizer (6) is communicated with a fuel gas collector (13);
the bottom outlet of the demethanizer (6) is communicated with the inlet of the solvent recovery tower (7), the bottom outlet of the solvent recovery tower (7) is communicated with the top inlet of the demethanizer (6), the top outlet of the solvent recovery tower (7) is communicated with the inlet of the acetylene converter (8), the outlet of the acetylene converter (8) is communicated with the inlet of the ethylene rectifying tower (9), the top outlet of the ethylene rectifying tower (9) is communicated with an ethylene collector (14), and the bottom outlet of the ethylene rectifying tower (9) is communicated with an ethane collector (15);
the tower bottom outlet of the deethanizer (5) is communicated with the inlet of the depropanizer (10), the tower top outlet of the depropanizer (10) is communicated with the inlet of the propylene rectifying tower (11), the tower top outlet of the propylene rectifying tower (11) is communicated with the propylene collector (16), and the tower bottom outlet of the propylene rectifying tower (11) is communicated with the propane collector (17);
the tower bottom outlet of the depropanization tower (10) is communicated with the inlet of the debutanization tower (12), the tower top outlet of the debutanization tower (12) is communicated with a component collector (18) of C4, and the tower bottom outlet of the debutanization tower (12) is communicated with a component collector (19) of more than C5 and C5.
2. The methanol-to-olefin gas separation device according to claim 1, wherein the pretreatment module (1) comprises a quenching tower (101), a water stripper (102), a methanol recovery tower (103), a first compressor section (104), a second compressor section (105), a water washing tower (106), a third compressor section (107), a caustic washing tower (108) and a spent caustic pretreatment tower (109);
the inlet of the quenching tower (101) is communicated with a methanol-to-olefin reactor (20), the top outlet of the quenching tower (101) is communicated with the inlet of the methanol recovery tower (103), the top outlet of the methanol recovery tower (103) is communicated with the inlet of the first compressor section (104), the outlet of the first compressor section (104) is communicated with the inlet of the second compressor section (105), the outlet of the second compressor section (105) is communicated with the inlet of the water washing tower (106), the outlet of the water washing tower (106) is communicated with the inlet of the third compressor section (107), the outlet of the third compressor section (107) is communicated with the inlet of the alkaline washing tower (108), and the top outlet of the alkaline washing tower (108) is communicated with the inlet of the separator (2);
the tower bottom outlet of the alkaline tower (108) is communicated with the inlet of the waste alkali liquor pretreatment tower (109), and the outlet of the waste alkali liquor pretreatment tower (109) is communicated with a waste alkali liquor collector (21);
the outlet of the quenching tower (101) is communicated with the inlet of the water stripping tower (102), the outlet of the methanol recovery tower (103) is communicated with the inlet of the water stripping tower (102), and the outlet of the water stripping tower (102) is communicated with the water collector (22).
3. The methanol to olefin gas separation apparatus according to claim 1, wherein the depropanizer (10) comprises a high pressure depropanizer (1001) and a low pressure depropanizer (1002);
the outlet at the bottom of the deethanizer (5) is communicated with the inlet of the high-pressure depropanizer (1001), and the outlet at the top of the high-pressure depropanizer (1001) is communicated with the inlet of the propylene rectifying tower (11);
the outlet at the tower bottom of the high-pressure depropanizing tower (1001) is communicated with the inlet of the low-pressure depropanizing tower (1002), and the outlet at the tower bottom of the low-pressure depropanizing tower (1002) is communicated with the inlet of the debutanizing tower (12).
4. The methanol to olefin gas separation device according to claim 3, further comprising: a heat exchanger (23);
the tower bottom outlet of the high-pressure depropanizing tower (1001) is communicated with the inlet of the low-pressure depropanizing tower (1002) through the heat exchanger (23);
the outlet of the tower top of the low-pressure depropanizing tower (1002) is communicated with the inlet of the high-pressure depropanizing tower (1001) through the heat exchanger (23).
5. The methanol-to-olefin gas separation apparatus according to claim 3, wherein the propylene rectification column (11) comprises a first propylene rectification column (1101) and a second propylene rectification column (1102);
the top outlet of the high-pressure depropanizer (1001) is communicated with the inlet of the first propylene rectifying tower (1101), and the top outlet of the first propylene rectifying tower (1101) is communicated with the propylene collector (16);
the bottom outlet of the first propylene rectifying tower (1101) is communicated with the inlet of the second propylene rectifying tower (1102), and the bottom outlet of the second propylene rectifying tower (1102) is communicated with the propane collector (17);
the tower top outlet of the second propylene rectifying tower (1102) is communicated with the inlet of the first propylene rectifying tower (1101).
6. The methanol to olefin gas separation device according to claim 1, further comprising: a compressor four section (24);
the compressor four section (24) is arranged between the deethanizer (5) and the demethanizer (6).
7. The methanol to olefin gas separation device according to claim 1, further comprising: a second gas phase dryer (25);
the second gas phase dryer (25) is arranged between the acetylene converter (8) and the ethylene rectification column (9).
8. The methanol-to-olefin gas separation apparatus according to claim 1, wherein an intermediate boiler and a reboiler are provided in the ethylene rectification column (9);
the middle boiling device is arranged at the theoretical plates of 80-110 th layer from the top to the bottom of the ethylene rectifying tower (9);
the reboiler is arranged at the bottom of the ethylene rectifying tower (9).
9. The methanol-to-olefin separation apparatus according to claim 1, wherein the ethylene rectification column (9) is provided with a side line from the top to the bottom of the theoretical plates at 2 to 10 th levels, and the side line is communicated with the ethylene collector (14).
10. A method for separating methanol-to-olefin gas, comprising:
pretreating a reaction product of the methanol-to-olefin reactor (20), and then sending the pretreated reaction product into a separator (2) for gas-liquid separation to obtain a gas-phase product and a condensate product;
feeding the gas-phase product into a first gas-phase dryer (4) for drying, and then feeding the gas-phase product into a deethanizer (5) to obtain components with the C2 and the C2 at the top of the tower and components with the C3 and the C3 at the bottom of the tower;
feeding the components with the C2 and the C2 and the absorbent at the top of the tower into a demethanizer (6) to obtain a fuel gas at the top of the tower and a mixture of the components with the C2 and the absorbent at the bottom of the tower;
feeding the mixture of the C2 component and the absorbent at the bottom of the tower into a solvent recovery tower (7) to obtain a C2 component at the top of the tower and the absorbent at the bottom of the tower, and feeding the absorbent at the bottom of the tower back to the demethanizer (6) again;
c2 components at the tower top are sent into an acetylene converter (8) for conversion, and then sent into an ethylene rectifying tower (9) to obtain ethylene at the tower top and ethane at the tower bottom;
feeding the components with the C3 and the components with the C3 or more at the bottom of the tower into a depropanizing tower (10) to obtain components with the C3 at the top of the tower and components with the C4 and the components with the C4 or more at the bottom of the tower;
feeding the C3 component at the top of the tower into a propylene rectifying tower (11) to obtain propylene at the top of the tower and propane at the bottom of the tower;
and C4 grade components with the content of more than C4 at the bottom of the tower are sent to a debutanizer (12) to obtain C4 components at the top of the tower and C5 and components with the content of more than C5 at the bottom of the tower.
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