CN116694370A - Low-temperature methanol washing system and method for treating unconverted air - Google Patents
Low-temperature methanol washing system and method for treating unconverted air Download PDFInfo
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- CN116694370A CN116694370A CN202310841015.XA CN202310841015A CN116694370A CN 116694370 A CN116694370 A CN 116694370A CN 202310841015 A CN202310841015 A CN 202310841015A CN 116694370 A CN116694370 A CN 116694370A
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- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 title claims abstract description 1308
- 238000005406 washing Methods 0.000 title claims abstract description 79
- 238000000034 method Methods 0.000 title claims abstract description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 100
- 230000008929 regeneration Effects 0.000 claims abstract description 70
- 238000011069 regeneration method Methods 0.000 claims abstract description 70
- 238000000926 separation method Methods 0.000 claims abstract description 62
- 230000008569 process Effects 0.000 claims abstract description 12
- 239000007789 gas Substances 0.000 claims description 386
- 239000007788 liquid Substances 0.000 claims description 86
- 238000003795 desorption Methods 0.000 claims description 61
- 229910052717 sulfur Inorganic materials 0.000 claims description 56
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 55
- 239000011593 sulfur Substances 0.000 claims description 55
- 238000001704 evaporation Methods 0.000 claims description 34
- 230000008020 evaporation Effects 0.000 claims description 31
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 28
- 238000010992 reflux Methods 0.000 claims description 27
- 238000005262 decarbonization Methods 0.000 claims description 25
- 238000001816 cooling Methods 0.000 claims description 24
- 238000006477 desulfuration reaction Methods 0.000 claims description 24
- 230000023556 desulfurization Effects 0.000 claims description 24
- 230000015572 biosynthetic process Effects 0.000 claims description 21
- 238000003786 synthesis reaction Methods 0.000 claims description 21
- 239000002994 raw material Substances 0.000 claims description 20
- 239000002351 wastewater Substances 0.000 claims description 20
- 239000012071 phase Substances 0.000 claims description 18
- 239000000463 material Substances 0.000 claims description 17
- 238000005261 decarburization Methods 0.000 claims description 16
- 229910052757 nitrogen Inorganic materials 0.000 claims description 14
- 238000011084 recovery Methods 0.000 claims description 14
- 239000004973 liquid crystal related substance Substances 0.000 claims description 12
- 239000007791 liquid phase Substances 0.000 claims description 12
- 238000005201 scrubbing Methods 0.000 claims description 12
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 claims description 7
- 229910000037 hydrogen sulfide Inorganic materials 0.000 claims description 7
- 238000001914 filtration Methods 0.000 claims description 6
- 230000009467 reduction Effects 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000007710 freezing Methods 0.000 claims description 3
- 230000008014 freezing Effects 0.000 claims description 3
- 229910052739 hydrogen Inorganic materials 0.000 claims description 3
- 238000010926 purge Methods 0.000 claims description 3
- 239000001257 hydrogen Substances 0.000 claims description 2
- 238000005192 partition Methods 0.000 claims description 2
- 238000004064 recycling Methods 0.000 claims description 2
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims 1
- 239000012808 vapor phase Substances 0.000 claims 1
- 238000000746 purification Methods 0.000 abstract description 12
- 230000007613 environmental effect Effects 0.000 abstract description 4
- 239000003245 coal Substances 0.000 description 8
- 238000010521 absorption reaction Methods 0.000 description 6
- 239000002253 acid Substances 0.000 description 5
- 238000002309 gasification Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 4
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 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
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- -1 S and the like Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000011278 co-treatment Methods 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- GBMDVOWEEQVZKZ-UHFFFAOYSA-N methanol;hydrate Chemical compound O.OC GBMDVOWEEQVZKZ-UHFFFAOYSA-N 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/08—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors
- C10K1/16—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with non-aqueous liquids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/06—Flash distillation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
- B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
- B01D3/322—Reboiler specifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
- B01D3/38—Steam distillation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
- B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
- B01D5/006—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes with evaporation or distillation
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/002—Removal of contaminants
- C10K1/003—Removal of contaminants of acid contaminants, e.g. acid gas removal
- C10K1/004—Sulfur containing contaminants, e.g. hydrogen sulfide
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/002—Removal of contaminants
- C10K1/003—Removal of contaminants of acid contaminants, e.g. acid gas removal
- C10K1/005—Carbon dioxide
Abstract
The invention discloses a low-temperature methanol washing system and a method for treating unconverted air, wherein the low-temperature methanol washing system comprises a first lean methanol pipe, a circulating gas pipe, a raw gas cooler, a raw gas separating tank, a washing tower, a medium-pressure flash tower and H 2 S concentration tower, semi-lean solution stripping tower, normal temperature stripping tower, heat regeneration tower, lean methanol tank and third lean methanolPipe, CO 2 The device comprises a flash tank, a methanol/water separation tower, a first tail gas pipe, a second tail gas pipe and a tail gas water washing tower. The process flow for independently treating the non-converted air is reasonable in design, meets the requirements of purification indexes and environmental protection, and fills the blank of independently treating the non-converted air by low-temperature methanol washing.
Description
Technical Field
The invention belongs to the technical field of gas purification of coal chemical equipment, and relates to a low-temperature methanol washing system and method for treating non-converted gas, which are used for solving the problem of directly treating the non-converted gas by low-temperature methanol washing.
Background
The raw material gas of the coal chemical plant often contains CO 2 、H 2 S, etc., which are required to be removed by a low temperature methanol scrubbing process to obtain a clean synthesis gas meeting downstream requirements. The low-temperature methanol washing and purifying method is a physical absorption method, and uses methanol to carry out CO treatment under the low-temperature condition (-70 to minus 30 ℃) 2 、H 2 The physical characteristics of high solubility and high selectivity of acid gas such as S and the like, and methanol is used as a solvent to remove the acid gas from raw material gas, and the method has the advantages of strong absorption capacity, high purification degree, good selectivity and the like, and is widely applied to modern large-scale coal chemical equipment.
Low-temperature methanol eluting and absorbing to eliminate acid medium CO from raw material gas 2 、H 2 S, COS A physical absorption process, the gas-liquid equilibrium relation accords withHenry's law, the content of absorbed components in a solution is essentially proportional to its partial pressure in the gas phase. Therefore, the raw gas subjected to low-temperature methanol washing treatment is often shift gas obtained by a shift process of coal gasification process gas. For the change-over gas (CO 2 Content of 35-45 mol%) due to gas phase CO 2 Is high in partial pressure and is rich in CO in methanol in liquid phase of an absorption tower 2 The concentration is also high. At low pressure desorption, CO in methanol 2 The concentration will decrease to a lower level, CO 2 Large desorption gradient due to CO 2 The desorption endothermic effect can reduce the temperature of the rich methanol to minus 60 ℃ to minus 70 ℃ to provide cold for the system, the low-temperature rich methanol is transferred to the lean methanol after heat exchange, and the obtained low-temperature lean methanol (-50 ℃ to minus 60 ℃) is removed from the top of the washing tower to absorb the acidic medium, thereby ensuring the purification index, saving the consumption of the methanol and reducing the consumption. So there is enough CO in the raw material gas 2 The content can reduce the system to enough low temperature during low pressure desorption, and is an important condition for normal operation of low-temperature methanol washing.
At present, along with the enrichment of the requirements of subsequent products and simultaneously for meeting the requirements of carbon emission reduction, after the coal chemical industry optimizing process, the raw material gas can be transformed no longer, CO is produced by coal gasification, and simultaneously, the raw material gas is coupled with new energy, so that H can be generated 2 The device is supplied by green hydrogen so as to prepare a device for synthesizing methanol from raw material gas with proper hydrocarbon ratio. However, the low-temperature methanol washing raw gas is generally converted gas, or partially converted gas, or converted gas and unconverted gas, and is not specially suitable for a low-temperature methanol washing device for treating the raw gas of the unconverted gas.
In these purification apparatuses, when the raw gas to be fed into the purification apparatus is the non-converted gas that has not undergone the conversion step, the CO of the raw gas is used as a CO 2 Low content (e.g. non-converted gas CO of pulverized coal gasification process) 2 The content is 6 to 8 mol percent, and the gasification process of the coal water slurry does not change CO of the gas 2 15-20 mol percent), the partial pressure is low, for example, a purification device adopts a conventional low-temperature methanol washing process flow, a high-concentration washing rich solution can not be obtained, and during low-pressure desorption, enough cold energy and low temperature can not be provided for the system, namely It is difficult to achieve the purified gas index. At the same time, the temperature can not be reduced to be lower, and H in the tail gas 2 The S content also exceeds design criteria.
Therefore, a reasonably designed low temperature methanol scrubbing system and method for independent treatment of unconverted gas is needed to rationally dispose of CO 2 And the desorption and heat exchange network reduces the temperature of the system to meet the requirements of purification indexes and environmental protection, and simultaneously, the investment and the consumption are as low as possible.
Disclosure of Invention
In view of the shortcomings of the prior art, the invention aims to provide a low-temperature methanol washing system and a method for treating unconverted gas, so as to meet the purification index and environmental protection requirements of the unconverted gas after being directly treated by the low-temperature methanol washing system.
In order to achieve the above object, the present invention adopts the following technical scheme:
a cryogenic methanol wash system for processing unconverted gas, comprising:
a first methanol-lean pipe configured to feed methanol-lean into a feed gas to be fed into a feed gas cooler to prevent the feed gas from freezing when the feed gas is subjected to heat exchange and temperature reduction in the feed gas cooler;
a recycle gas line configured to return the first flash gas and the second flash gas as recycle gas to the feed gas to be fed to the feed gas cooler;
A raw gas cooler configured to convert the non-converted gas as the raw gas and the purified gas and CO as the cold source 2 The heat exchange and the cooling of the product gas and the tail gas are carried out;
a feed gas separation tank for separating gas and liquid from the feed gas cooled by the feed gas cooler to separate aqueous methanol in a liquid phase;
the washing tower is sequentially provided with a desulfurization section, a first decarburization section and a second decarburization section which are communicated with each other from bottom to top; wherein, the liquid crystal display device comprises a liquid crystal display device,
the second decarbonization section is configured to sequentially scrub the first decarbonized gas from the first decarbonizing section with semi-lean methanol from the semi-lean stripper and lean methanol from the lean methanol tank to further remove the sameCO 2 Obtaining a second decarbonized gas and CO-containing gas as the purge gas 2 Methanol solution;
the first decarbonization section is configured to utilize the cooled CO-containing 2 Methanol liquid washes the desulfurization gas from the desulfurization section to remove CO 2 Obtaining a first decarbonized gas and rich in CO 2 Methanol solution;
the desulfurization section is configured to utilize a portion of the enriched CO 2 Methanol liquid washes the feed gas from the feed gas separation tank V-001 to remove H therefrom 2 S, obtaining a desulfurization gas and a sulfur-containing methanol rich solution;
the medium-pressure flash tower comprises a first synthesis gas flash evaporation section and a second synthesis gas flash evaporation section which are arranged from top to bottom; wherein, the liquid crystal display device comprises a liquid crystal display device,
The first syngas flash stage is configured to recover a portion of the CO-enriched stream after exiting the first decarbonization stage via refrigeration recovery 2 Dissolved H in methanol solution 2 Flashing CO to obtain the first flash gas and sulfur-free methanol liquid;
the second synthesis gas flash evaporation section is configured to dissolve H in the sulfur-containing methanol rich liquid which is recovered by cold energy after flowing out of the desulfurization section 2 Flashing the CO to obtain the second flash gas and a sulfur-containing methanol solution;
H 2 s concentration tower, said H 2 The S concentration tower is sequentially provided with CO from top to bottom 2 The device comprises a flash evaporation section, a desorption section and a stripping section, wherein the desorption section is communicated with the stripping section in a gas phase manner, so that the stripping gas of the lower stripping section rises to enter the upper desorption section to wash and remove sulfur;
the CO 2 The flash stage is configured to reject CO in the cooled sulfur-free methanol liquid after exiting the first syngas flash stage 2 Reduced pressure desorption is carried out to obtain desorbed methanol from the bottom and the CO from the top 2 Product gas;
the desorption stage is configured to reject CO in the cooled sour methanol solution after exiting the second syngas flash stage 2 Reduced pressure desorption is carried out and is introduced at the upper part thereof for the desorption stage Washing the gas phase to remove sulfur and part of the desorbed methanol to obtain desorption liquid and sulfur-free desorption gas discharged from the top;
the stripping section is configured to recover residual CO in the desorption liquid after the cooling quantity after the stripping section 2 Stripping and desorbing to obtain sulfur-rich methanol at the bottom and stripping gas to be fed into the desorbing section at the top;
a semi-lean liquid stripper configured to utilize nitrogen to flow out of the CO 2 Partial desorption of CO from methanol in flash section 2 Stripping to obtain sulfur-free stripping gas and the semi-lean methanol, and feeding the obtained semi-lean methanol into a second decarburization section of the washing tower after cold recovery;
a normal temperature stripping tower configured to utilize nitrogen to counter flow residual CO in the sulfur-enriched methanol recovered by cold after the stripping section 2 Stripping to obtain a stripping gas rich in methanol and sulfur and feeding the obtained stripping gas into the stripping section to recover sulfur;
the thermal regeneration tower is configured to thermally regenerate the rich methanol which is recovered by cold energy after flowing out of the normal-temperature stripping tower, so as to obtain hydrogen sulfide-containing gas at the top of the tower and lean methanol from which hydrogen sulfide is removed at the bottom of the tower; the tower bottom of the thermal regeneration tower is provided with a matched thermal regeneration tower reboiler, the tower top is provided with a matched thermal regeneration tower top condenser and a thermal regeneration tower top reflux tank, and the thermal regeneration tower top reflux tank is used for carrying out gas-liquid separation on materials from the thermal regeneration tower top condenser and sending out separated liquid phase as a tower top reflux and separated gas phase material;
A methanol-lean tank configured to receive a portion of the methanol-lean from the thermal regeneration tower and deliver the methanol-lean to the feed gas through the first methanol-lean pipe and the methanol-lean to the second decarbonization section through a second methanol-lean pipe;
a third lean methanol pipe for cooling part of lean methanol from the thermal regeneration tower and sending the cooled lean methanol to the methanol/water separation tower as the top reflux;
CO 2 a flash tank configured to recover the cold energy of the feedstock after exiting the feed gas separation tankCO in aqueous methanol 2 Flash evaporating and distilling the CO-containing material 2 Gas is fed into the H 2 The stripping section of the S concentration tower and the residual water-containing methanol are sent to the methanol/water separation tower;
a methanol/water separation column configured to separate the CO from the water 2 Rectifying and separating the water-containing methanol in the flash tank and the methanol in the methanol-containing washing water in the tail gas water scrubber to obtain methanol steam at the top of the tower and waste water from which the methanol is removed at the bottom of the tower; the bottom of the methanol/water separation tower is provided with a matched methanol/water separation tower reboiler;
the first tail gas pipe is used for sending the sulfur-free stripping gas and part of the sulfur-free stripping gas serving as tail gas to the raw material gas cooler, and sending the tail gas into a tail gas water scrubber after cold energy recovery;
The second tail gas pipe is used for recycling cold energy from the other part of the sulfur-free stripping gas and sending the other part of the sulfur-free stripping gas into a tail gas water scrubber;
and the tail gas water washing tower is configured to utilize part of cooled wastewater after flowing out of the methanol/water separation tower and desalted water from the outside to wash the mixed gas of the gas sent by the first tail gas pipe and the gas sent by the second tail gas pipe in sequence so as to obtain the dischargeable tail gas and the methanol-containing washing water.
The invention also provides a method for treating the unconverted air by using the low-temperature methanol washing system.
Compared with the prior art, the invention has the following advantages:
1. the invention relates to a novel low-temperature methanol washing system suitable for independently treating the non-converted gas, which can be realized in a practical device.
2. CO in unconverted gas 2 The content is low, the temperature rise in the washing tower is small, the washing tower is three sections, the flow is simplified, and the investment is reduced.
3. The semi-lean liquid stripping tower is arranged to more effectively desorb CO dissolved in the semi-lean methanol liquid 2 The gas and semi-lean solution has strong absorption capacity, reduces the consumption of lean methanol solution, ensures the index of purified gas and reduces consumption.
4. The temperature of the semi-lean methanol liquid is reduced to minus 60 ℃ to minus 70 ℃ after gas stripping, a low-temperature cold source equivalent to the conventional flow is obtained, and the semi-lean liquid exchanges heat with the lean methanol liquid, so that the lean methanol with low temperature at the top of the washing tower is obtained, and the purification index is ensured.
5. CO-free 2 The desorber has simplified flow and reduced investment.
6. The temperature of the propylene evaporated at the temperature of minus 45 ℃ is reduced before desorption of the rich methanol, and the temperature of the propylene after desorption of the rich methanol is also reduced, so that the temperature of the whole system is reduced, and the purification index and the sulfur content index in the tail gas are ensured.
7. The medium pressure flash evaporation is carried out on the rich methanol, and then the cooling is carried out by using a cryocooler, so that the medium pressure flash evaporation temperature is high, the solubility of CO in the methanol is small, the CO flash evaporation amount is large, and the CO recovery rate is ensured.
Drawings
FIG. 1 is a schematic diagram of one embodiment of a cryogenic methanol scrubbing system of the present invention.
The reference numerals are explained as follows:
a T-001 scrubber; a T-002 medium pressure flash column; T-003H 2 S, concentrating the tower; t-004 thermal regeneration tower; t-005 methanol/water separation column; t-006 tail gas water scrubber; t-007 atmospheric gas stripping tower; t-008 semi-lean liquid stripper;
v-001 raw material gas separator; v-004 lean methanol tank; V-005H 2 S gas separation tank; v-006 thermal regeneration overhead reflux drum; v-008CO 2 A flash tank;
s-001 lean methanol filter; s-002 # 1 methanol-rich filter; s-003 # 2 methanol-rich filter;
p-001 # 1 methanol pump; p-002 # 2 methanol pump; p-003 # 3 methanol pump; p-004 lean methanol liquid pump; a P-005 thermal regenerator bottom pump; p-006 thermal regeneration overhead reflux pump; p-007 water washing tower bottom pump; p-008 semi-lean methanol liquid pump;
a C-001 recycle gas compressor;
an E-001 feed gas cooler; e-002 circulating gas compressor outlet water cooler; e-003 sulfur-containing methanol chiller; e004 sulfur-free methanol chiller; e-005 lean methanol chiller; e-006 scrubber sectionA indirect chiller; e-007 washing tower methanol-rich heat exchanger; e-008 # 2 lean methanol cooler; e-009 # 1 lean methanol cooler; e-010 thermal regeneration tower feed heater; e-011 a thermal regenerator reboiler; e-012 thermal regeneration overhead condenser; E-013H 2 S fraction deep cooler; E-014H 2 S fraction heat exchanger; e-015 methanol/water separation column reboiler; e-016 methanol/water separation tower feeding heater; e-017 purified gas/methanol-rich heat exchanger; e-018 lean methanol water cooler; e-019 tail gas/nitrogen heat exchanger; e-020 waste water heat exchanger; e-021 lean methanol/semi-lean heat exchanger;
a desulfurization section A; b, a first decarburization section; a second decarburization section; d, a first synthesis gas flash evaporation section; e a second synthesis gas flash section; f CO 2 A flash evaporation section; a G desorption section; an H stripping section;
1 a first methanol lean pipe; 2 a second methanol-lean pipe; 3 a third methanol-lean pipe; 4 circulating pipes; 5 a first tail gas pipe; 6, a second tail gas pipe; a fourth lean methanol pipe; 8, a partition board; 9 a first backup pipe; 10 a second backup pipe; 11CO 2 A discharge pipe.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe the embodiments of the invention herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Fig. 1 shows a schematic diagram of an embodiment of a low temperature methanol washing system provided by the invention, the low temperature methanol washing system comprising:
a first methanol-lean pipe 1 configured to feed methanol to a feed gas to be fed into a feed gas cooler E-001 to prevent the feed gas from freezing when the feed gas is subjected to heat exchange and temperature reduction in the feed gas cooler E-001;
a recycle gas pipe 4 configured to return the first flash gas and the second flash gas as recycle gas to the feed gas to be fed into the feed gas cooler E-001;
a raw gas cooler E-001 configured to convert the non-converted gas as the raw gas and the purified gas and CO as the cold source 2 The heat exchange and the cooling of the product gas and the tail gas are carried out;
a feed gas separation tank V-001 for separating gas and liquid of the feed gas cooled by the feed gas cooler E-001 to separate aqueous methanol in a liquid phase;
the washing tower T-001 is provided with a desulfurization section A, a first decarburization section B and a second decarburization section C which are communicated in a gas phase manner from bottom to top in sequence; wherein, the liquid crystal display device comprises a liquid crystal display device,
the second decarbonization section C is configured to sequentially wash the first decarbonization gas from the first decarbonization section B with semi-lean methanol from the semi-lean stripper T-008 and lean methanol from the lean methanol tank V-004 to further remove CO therefrom 2 Obtaining a second decarbonized gas and CO-containing gas as the purge gas 2 Methanol solution;
the first decarbonization section B is configured to utilize the cooled CO-containing 2 Methanol liquid washes the desulfurization gas from the desulfurization section A to remove CO 2 Obtaining a first decarbonized gas and rich in CO 2 Methanol solution;
the desulfurization section A is configured to utilize a portion of the CO-enriched stream 2 Methanol liquid washes the feed gas from the feed gas separation tank V-001 to remove H therefrom 2 S, obtaining a desulfurization gas and a sulfur-containing methanol rich solution;
the medium-pressure flash tower T-002 comprises a first synthetic gas flash section D and a second synthetic gas flash section E which are arranged from top to bottom; wherein, the liquid crystal display device comprises a liquid crystal display device,
the first synthesis gas flash stage D is configured to recover a portion of the cold recovered CO-enriched stream after exiting the first decarbonization stage B 2 Dissolved H in methanol solution 2 Flashing CO to obtain the first flash gas and sulfur-free methanol liquid;
the second synthesis gas flash evaporation section E is configured to recycle the dissolved H in the sulfur-containing methanol rich liquid after flowing out of the desulfurization section A 2 Flashing the CO to obtain the second flash gas and a sulfur-containing methanol solution;
H 2 s concentrating tower T-003, said H 2 The S concentration tower is sequentially provided with CO from top to bottom 2 The device comprises a flash evaporation section F, a desorption section G and a stripping section H, wherein the desorption section G is communicated with the stripping section H in a gas phase manner, so that the stripping gas of a lower stripping section rises to enter an upper desorption section to wash and remove sulfur;
The CO 2 The flash evaporation section F is configured to cool CO in the sulfur-free methanol liquid after exiting the first synthesis gas flash evaporation section D 2 Reduced pressure desorption is carried out to obtain desorbed methanol from the bottom and the CO from the top 2 Product gas;
the desorption section G is configured to reject CO in the cooled sulfur-containing methanol solution after exiting the second syngas flash section E 2 Performing reduced pressure desorption and introducing at an upper portion thereof a portion of said desorbed methanol for scrubbing and sulfur removal of the gas phase in said desorption zone G to obtain a desorption liquid and a sulfur-free desorption gas discharged from the top;
the stripping section H is configured to recover residual CO in the desorption liquid after flowing out of the stripping section G 2 Stripping and desorbing to obtain sulfur-rich methanol at the bottom and stripping gas to be fed into the desorbing section G at the top;
a semi-lean liquid stripper T-008 configured to utilize nitrogen to flow out of the CO 2 Partial desorption of CO from methanol in flash section 2 Stripping to obtain sulfur-free stripping gas and the semi-lean methanol, and feeding the obtained semi-lean methanol into a second decarbonization section C of the washing tower T-001 after cold energy recovery;
a normal temperature stripping tower T-007 configured to utilize nitrogen to counter flow residual CO in the sulfur-enriched methanol after cold recovery after exiting the stripping section H 2 Stripping to obtain a stripping gas rich in methanol and sulfur and feeding the obtained stripping gas containing sulfur into the stripping section H to recover sulfur;
the thermal regeneration tower T-004 is configured to thermally regenerate the rich methanol which is recovered by cold energy after flowing out of the normal temperature stripping tower T-007 so as to obtain hydrogen sulfide-containing gas at the top of the tower and lean methanol from which hydrogen sulfide is removed at the bottom of the tower; the bottom of the thermal regeneration tower T-004 is provided with a matched thermal regeneration tower reboiler E-011, the top of the thermal regeneration tower is provided with a matched thermal regeneration tower top condenser E-012 and a thermal regeneration tower top reflux tank V-006, and the thermal regeneration tower top reflux tank V-006 is used for carrying out gas-liquid separation on the materials from the thermal regeneration tower top condenser E-012 and sending the separated liquid phase as a tower top reflux and separated gas phase material;
a methanol-lean tank V-004 configured to receive a part of the methanol-lean from the thermal regeneration tower T-004, and to deliver the methanol-lean to the raw gas through the first methanol-lean pipe 1, and to deliver the methanol-lean to the second decarbonization section C through the second methanol-lean pipe 2;
a third lean methanol pipe 3 for feeding part of lean methanol from the thermal regeneration tower T-004 into the methanol/water separation tower T-005 as top reflux after cooling;
CO 2 A flash tank V-008 configured to recover CO in the aqueous methanol after the cold recovery from the raw gas separation tank V-001 2 Flash evaporating and distilling the CO-containing material 2 Gas is fed into the H 2 The stripping section of the S concentration tower T-003 and the residual water-containing methanol are sent to the methanol/water separation tower T-005;
a methanol/water separation column T-005 configured to separate the CO from the catalyst 2 Aqueous methanol from flash tank V-008 and methanol from methanol-containing wash water from tail gas water scrubber T-006 are refinedDistilling and separating to obtain methanol steam at the top of the tower and waste water after methanol removal at the bottom of the tower; the bottom of the methanol/water separation tower T-005 is provided with a matched methanol/water separation tower reboiler E-015;
the first tail gas pipe 5 is used for sending the sulfur-free stripping gas and part of the sulfur-free stripping gas as tail gas to the raw gas cooler E-001, and sending the tail gas after cold energy recovery to the tail gas water scrubber T-006;
the second tail gas pipe 6 is used for feeding the other part of the sulfur-free stripping gas into a tail gas water scrubber T-006 after cold energy recovery;
the tail gas water scrubber T-006 is configured to sequentially scrub the mixed gas of the gas sent from the first tail gas pipe 5 and the second tail gas pipe 6 by using the cooled wastewater and desalted water from the outside after partially flowing out of the methanol/water separator T-005, so as to obtain the dischargeable tail gas and the methanol-containing scrubbing water.
In some embodiments, the cryogenic methanol wash system further comprises H 2 S fraction heat exchanger E-014, H 2 S fraction chiller E-013 and H 2 S gas separation tank V-005; wherein the H is 2 An S gas separation tank is configured to feed the H gas from the thermal regeneration overhead reflux tank in sequence 2 S fraction heat exchangers E-014 and H 2 The gas phase material cooled by the S fraction chiller E-013 is subjected to gas-liquid separation, and the separated liquid phase is sent to the stripping section and separated H 2 S gas is sent to the H 2 S fraction heat exchanger E-014 recovers cold by exchanging heat with the gaseous material.
In some embodiments, the cryogenic methanol washing system further comprises a methanol-lean pump P-004 and a methanol-lean water cooler E-018 for pressurizing and water-cooling the methanol-lean from the methanol-lean tank V-004 in sequence before the methanol-lean enters the first methanol-lean pipe 1 and the second methanol-lean pipe 2;
a 1# lean methanol cooler E-009, a lean methanol cryocooler E-005 for further cooling lean methanol in the second lean methanol pipe, a 2# lean methanol cooler E-008 and a lean methanol/semi-lean methanol heat exchanger E-021 are sequentially arranged on the second lean methanol pipe 2 along the material flow direction;
wherein the 1# lean methanol cooler E-009 is configured to heat exchange and raise the temperature of the sulfur-rich methanol from the stripping section H with the lean methanol in the second lean methanol pipe 2 before entering the normal temperature stripper T-007;
The 2# lean methanol cooler E-008 is configured to heat the desorption liquid from the desorption section G and lean methanol in the second lean methanol pipe 2 in a heat exchange way;
the lean methanol/semi-lean methanol heat exchanger E-021 is configured to exchange heat semi-lean methanol to be fed into the second decarbonization section with lean methanol in the second lean methanol pipe to cool the lean methanol.
In some embodiments, the cryogenic methanol wash system further comprises a 3# methanol liquid pump P-003 and a 1# methanol rich filter S-002 for pressurizing and filtering the sulfur-rich methanol from the stripping section H in sequence before it enters the 1# lean methanol cooler E-009;
a 1# methanol liquid pump P-002, a 2# methanol rich filter S-003 and a heat regeneration tower feeding heater E-010 are sequentially arranged on a pipeline for feeding the rich methanol from the normal temperature stripping tower T-007 into the heat regeneration tower T-004 along the flow direction, wherein the 1# methanol liquid pump P-002 and the 2# methanol rich filter S-003 are used for sequentially pressurizing, conveying and filtering the rich methanol before the rich methanol enters the heat regeneration tower feeding heater E-010; the thermal regeneration tower feed heater E-010 is used to heat exchange and raise the temperature of the rich methanol and the lean methanol to be fed into the lean methanol tank V-004.
In some embodiments, in the low-temperature methanol washing system, a purified gas/rich methanol heat exchanger E-017 is arranged on a pipeline for conveying the rich sulfur-containing methanol solution from the desulfurization section A to the second synthesis gas flash evaporation section E, and is used for heat exchanging and heating the rich sulfur-containing methanol solution and purified gas to be fed into the raw gas cooler E-001;
in the first decarbonizing stage, the carbon monoxide is enriched 2 A washing tower methanol-rich heat exchanger E-007 is arranged on a pipeline for conveying the methanol liquid to the first synthesis gas flash evaporation section D and is used for enabling the methanol liquid to be rich in CO 2 Methanol liquidHeat exchange and temperature rising are carried out on desorption liquid which enters the stripping section H;
a tail gas/nitrogen heat exchanger E-019 is arranged on the second tail gas pipe 6 and is used for heat exchanging and heating the sulfur-free stripping gas to be fed into the tail gas water scrubber T-006 and the nitrogen to be fed into the semi-lean liquid stripper T-008;
a methanol/water separation tower feeding heater E-016 is arranged on the third lean methanol pipe 3 and is used for enabling the CO to enter 2 The water-containing methanol in the flash tank V-008 exchanges heat with lean methanol to be fed into the methanol/water separation tower T-005 as top reflux to raise the temperature;
and a waste water heat exchanger E-020 is arranged on a pipeline for sending the waste water into the tail gas water washing tower T-006 and is used for heat exchanging and heating the washing water containing methanol to be sent into the methanol/water separation tower T-005 and the waste water to be sent into the tail gas water washing tower T-006.
In the process of introducing the CO-containing gas into the reactor 2 The pipeline for conveying the methanol liquid from the second decarburization section C to the first decarburization section B is provided with a device for cooling the CO-containing liquid 2 A scrubber E-006 for methanol solution;
a sulfur-containing methanol chiller E-003 for cooling the sulfur-containing methanol is arranged on a pipeline for conveying the sulfur-containing methanol from the second synthesis gas flash evaporation section E to the desorption section G;
after passing the sulfur-free methanol from the first syngas flash stage D to the CO 2 A pipeline of the flash evaporation section F is provided with a sulfur-free methanol cryocooler E-004 for cooling the sulfur-free methanol;
in the invention, each chiller adopts liquid-phase propylene as a chiller cold source.
In some embodiments, as shown in FIG. 1, the bottom of the thermal regeneration column T-004 is provided with a baffle 8, thereby dividing the bottom of the thermal regeneration column T-004 into a first region of relatively smaller area volume and a second region of relatively larger area volume; wherein the lean methanol tank V-004 is connected to the first zone through a fourth methanol pipe 7 to receive lean methanol cooled by the thermal regeneration tower feed heater E-010, the third lean methanol pipe 3 is connected to the second zone, and the third lean methanol pipe 3 is further provided with a thermal regeneration tower bottom pump P-005 and a lean methanol filter S-001 for sequentially pressurizing, conveying and filtering lean methanol to be fed into the methanol/water separation tower feed heater E-016;
The fourth methanol-lean pipe 7 is connected with a methanol-lean inlet of the reboiler E-011 of the thermal regeneration tower through a first standby pipe 9, and is connected with a methanol-lean inlet of the feed heater E-016 of the methanol/water separation tower through a second standby pipe 10.
In some embodiments, the cryogenic methanol wash system further comprises:
the semi-lean methanol liquid pump P-008 is used for pressurizing and conveying the semi-lean methanol to be fed into the lean methanol/semi-lean methanol heat exchanger E-021;
a 1# methanol liquid pump P-001 for pressurizing and conveying the desorption liquid to be fed into the 2# lean methanol cooler E-008;
a thermal regeneration overhead reflux pump P-006 for pressurizing and delivering the overhead reflux liquid from the thermal regeneration overhead reflux tank V-006;
and a water washing tower bottom pump P-007 for pressurizing and conveying the washing water containing methanol to be fed into the waste water heat exchanger E-020.
In some embodiments, in the low-temperature methanol washing system, a circulating gas compressor C-001 and a circulating gas compressor outlet cooler E-002 are sequentially arranged on the circulating gas pipe along the material flow direction, and are used for sequentially compressing and water-cooling the circulating gas.
In some embodiments, the cryogenic methanol scrubbing system further comprises a CO2 bleed line 11 for feeding CO2 product gas from the feed gas cooler E-001 as off-gas to be vented to the off-gas water scrubber T-006.
The operation method of the low temperature methanol system shown in fig. 1 is as follows:
raw material gas fed into the low-temperature methanol washing system is firstly washed by boiler water supply to enable NH in the raw material gas to be in 3 Reducing the content to below 2 ppm. Raw gas entering a low-temperature methanol washing system is mixed with compressed recycle gas and injected with a small amount of lean methanol for anti-icing, and the lean methanol is purified gas, tail gas and CO through a raw gas cooler E-001 2 Product gas exchangeAnd after the water (aqueous methanol) is separated out from the raw material gas separation tank V-001, the raw material gas is cooled and enters a desulfurization section of a lower tower of the washing tower T-001.
In the desulfurization section A, the feed gas is enriched in CO with a portion from the first decarbonization section B 2 Methanol liquid washing and H removal 2 S, COS and part of CO 2 After the components are equal, the components enter a first decarburization section B and the CO containing components from a second decarburization section C are utilized 2 The methanol solution is further washed and the gas entering the first decarbonization section B is free of sulfur. The first decarbonizing gas from the first decarbonizing section B is washed in the second decarbonizing section C of the washing tower T-001 by lean methanol liquid and half lean methanol after stripping so as to meet the purifying requirement. The purified gas is led out from the top of the tower, and is sent out from the system after heat exchange with the rich methanol and the raw gas through the purified gas/rich methanol heat exchanger E-017 and the raw gas cooler E-001 to recover the cold energy. CO-containing to be fed into the first decarbonization section B 2 The methanol liquid flows through a scrubber section inter-cooler E-006 to reduce the content of CO 2 The temperature of the methanol liquid can improve the absorption capacity of the methanol liquid.
Absorbs H 2 S and CO 2 After the sulfur-containing methanol rich solution from the desulfurization section A of the washing tower T-001 is subjected to heat exchange and temperature reduction by a purified gas/rich methanol heat exchanger E-017, the dissolved H is flashed out in a second synthetic gas flash section E of the medium-pressure flash tower T-002 2 CO gas and a small amount of CO 2 、H 2 S, etc. Likewise, CO-enriched effluent from the first decarbonizing section B of the scrubber T-001 2 After the methanol liquid is subjected to heat exchange and temperature reduction through a washing tower methanol-rich heat exchanger E-007, dissolved H is flashed in a first synthetic gas flash section D of a medium-pressure flash tower T-002 2 CO gas and a small amount of CO 2 A first flash of an isogas. After the two parts of flash gas are converged, the two parts of flash gas are pressurized by a circulating gas compressor C-001 and cooled by a circulating gas compressor outlet water cooler E-002, and then are returned to the raw gas as circulating gas to recycle the useful gas.
The sulfur-containing methanol liquid from the second synthetic gas flash evaporation section E of the medium pressure flash evaporation tower T-002 is cooled by a sulfur-containing methanol chiller E-003 and then is sent into H 2 S concentration tower T-003 tower desorption section G lower part, decompression desorption dissolved CO 2 Simultaneously dissolved H 2 S also partially flashes off. The sulfur-free methanol liquid from the first synthetic gas flash evaporation section D of the medium pressure flash evaporation tower T-002 is cooled by a sulfur-free methanol deep cooler E-004 and then enters into H 2 CO at the top of S concentration tower T-003 2 Flash evaporation section F, decompressing and flashing out CO 2 Product gas. CO 2 The product gas is sent out of the boundary zone after heat exchange by a raw material gas cooler E-001, and is subjected to CO when not used 2 The exhaust pipe 11 is combined with the tail gas and is washed and emptied by water. Warp H 2 S concentration tower T-003 tower top CO 2 Part of desorbed methanol after flash evaporation in the flash evaporation section F is stripped by a semi-lean liquid stripping tower T-008 tower to obtain semi-lean methanol, and the other part is returned to H 2 And a desorption section G of the S concentration tower T-003 is used for washing and desulfurizing the gas phase in the desorption section G so as to obtain desorption liquid and sulfur-free desorption gas discharged from the top.
The low-temperature semi-lean methanol obtained by the semi-lean liquid stripping tower T-008 is pressurized and then is sent to a second decarbonization section C of the washing tower after heat exchange with the lean methanol in a lean methanol/semi-lean heat exchanger E-021. H 2 And the desorption section of the S concentration tower T-003 tower obtains sulfur-free desorption gas, the tail gas enters the tail gas water washing tower T-006 tower to be washed by waste water and desalted water after the temperature is raised by heat exchange of a raw gas cooler E-001, and the tail gas reaching the emission standard after water washing is sent to a high chimney to be discharged. The washing water containing a small amount of methanol and containing methanol at the bottom of the tail gas washing tower T-006 is sent to a methanol/water separation tower T-005 after heat exchange by a waste water heat exchanger E-020, and the methanol is recovered.
From H 2 The sulfur-containing desorption liquid coming out from the lower part of the desorption section of the S concentration tower T-003 is used as a low-temperature cold source to enter H after being subjected to heat exchange and temperature rise in a 2# lean methanol cooler E-008 and a washing tower rich methanol heat exchanger E-007 in sequence 2 The stripping section of the S concentration tower T-003 tower is used for fully desorbing CO dissolved in the methanol-rich liquid 2 Low pressure nitrogen is introduced to carry out stripping. After nitrogen stripping, H 2 The bottom of the stripping section of the S concentration tower T-003 is used for obtaining CO 2 Sulfur-rich methanol with low content and low temperature, and the sulfur-rich methanol contains a small amount of CO 2 And basically all sulfides in the raw material gas are subjected to pressure boosting, filtered by a 1# methanol rich filter S-002 and subjected to heat exchange by a 1# methanol lean cooler E-009, and then enter a normal temperature stripping tower T-007 for normal temperature gas stripping. The methanol rich at the bottom of the normal temperature stripping tower T-007 passes through a 2# methanol rich filter S-003Filtering, and feeding the mixture into a heat regeneration tower T-004 after the heat exchange between a heater E-010 of the heat regeneration tower and lean methanol from the heat regeneration tower T-004.
The bottom of the thermal regeneration tower T-004 is provided with lean methanol, and the top of the thermal regeneration tower T-004 is provided with rich H 2 S is a hydrogen sulfide-containing gas. And after the lean methanol comes out of the bottom of the thermal regeneration tower T-004, cooling the lean methanol by a feeding heater E-010 of the thermal regeneration tower, feeding the lean methanol into a lean methanol tank V-004, pumping the lean methanol out and pressurizing the lean methanol by a lean methanol pump P-004, and cooling the lean methanol by heat exchange of a lean methanol cooler E-018, a first lean methanol cooler E-009, a lean methanol cryocooler E-005, a second lean methanol cooler E-008 and a lean methanol/semi-lean heat exchanger E-021, and then conveying the lean methanol/semi-lean heat exchanger to a second decarburization section C of a washing tower T-001 to complete methanol circulation. H obtained from the top of the thermal regeneration tower T-004 2 The gas containing hydrogen sulfide with higher S concentration is cooled by a thermal regeneration tower top condenser E-012, then liquid phase is separated in a thermal regeneration tower top reflux tank V-006 to be used as tower top reflux, and the separated gas phase material is sent out to pass through the H 2 S fraction heat exchangers E-014 and H 2 S fraction chiller E-013 cooled, then cooled in H 2 S gas separation tank V-006 is used for gas-liquid separation, and separated sulfur-containing methanol liquid returns to H 2 S concentrating tower T-003 stripping section and separating high H 2 Acid gas with S concentration as H 2 S gas products are sent to a sulfur recovery process; part H if necessary 2 S gas can also be recycled to H 2 S concentration tower T-003 is used for improving H in acid gas product 2 S concentration.
The aqueous methanol separated from the raw material gas separation tank V-001 also contains CO 2 The mixture enters CO after exchanging heat by a feeding heater E-016 of a methanol/water separation tower 2 Flash tank V-008 flash evaporation, and the flash gas phase is sent to H 2 And the liquid phase is sent to the middle part of the methanol/water separation tower T-005 in the stripping section H of the S concentration tower T-003. The methanol-containing washing water containing a small amount of methanol, which is discharged from the bottom of the tail gas washing tower T-006, also enters the middle part of a methanol/water separation tower T-005; a small amount of lean methanol from the bottom of the thermal regeneration tower T-004 is subjected to heat exchange through a feeding heater E-016 of the methanol/water separation tower and then is used as the tower top reflux of the methanol/water separation tower T-005. The methanol steam at the top of the methanol/water separation tower T-005 returns to the middle part of the thermal regeneration tower T-004, and the methanol/water separation tower T And (3) obtaining wastewater with the methanol content reaching the discharge standard at the bottom of the tower, and discharging the wastewater out of the system after heat exchange and cooling.
The low-temperature methanol washing system is used for recovering cold energy and ensuring necessary process conditions through a heat exchange network formed by a plurality of heat exchangers, and adopts the propylene evaporated at-45 ℃ as a cold source of a refrigerator; the outside is sent into low-pressure nitrogen as stripping gas, and then sent into desalted water for washing tail gas.
The invention is further illustrated below with reference to examples.
Example 1
Feeding the unconverted gas serving as the raw gas into a low-temperature methanol washing system shown in fig. 1, and treating the raw gas according to the operation method; wherein, the composition of the raw material gas is shown in Table 1, and the treatment results are shown in tables 2-3.
TABLE 1 composition and flow rate of feed gas (unconverted gas)
TABLE 2 gas and wastewater discharge index
TABLE 3 consumption guarantee value
According to the embodiment, the system for independently treating the non-converted gas is designed, the CO2 desorption and heat exchange network is reasonably configured, the temperature of the semi-lean methanol liquid is reduced to minus 60 ℃ to minus 70 ℃ after gas stripping, and the semi-lean methanol liquid exchanges heat with the lean methanol liquid, so that the lean methanol at the low temperature at the top of the washing tower is ensured, the purification index and the environmental protection requirement are met, the consumption is reduced, and the blank of independently treating the non-converted gas by washing the low-temperature methanol is filled.
The devices or elements of the present invention may be processing apparatuses, devices or elements having corresponding functions, which are known in the art, and will not be described in detail. Not specifically described herein, those skilled in the art will know or understand the present technology, and detailed description thereof will not be given. In order to highlight the idea of the invention, many necessary devices such as pumps, meters, valves, control elements etc. are omitted from the figures for industrial application.
It is to be readily understood that the above-described embodiments are merely examples for clarity of illustration and are not meant to limit the invention thereto. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (10)
1. A cryogenic methanol scrubbing system for treating unconverted gas, comprising:
a first methanol-lean pipe (1) configured to feed methanol-lean into a feed gas to be fed into a feed gas cooler (E-001) to prevent the feed gas from freezing when the feed gas is subjected to heat exchange and temperature reduction in the feed gas cooler (E-001);
A recycle gas line (4) configured to return the first flash gas and the second flash gas as recycle gas to the feed gas to be fed to the feed gas cooler (E-001);
a raw gas cooler (E-001) configured to convert the non-converted gas as the raw gas and the purified gas and CO as the cold source 2 The heat exchange and the cooling of the product gas and the tail gas are carried out;
a raw material gas separation tank (V-001) for separating gas and liquid of the raw material gas cooled by the raw material gas cooler (E-001) to separate out liquid phase aqueous methanol;
the washing tower (T-001) is provided with a desulfurization section (A), a first decarburization section (B) and a second decarburization section (C) which are communicated in a gas phase manner from bottom to top in sequence; wherein, the liquid crystal display device comprises a liquid crystal display device,
the second decarbonization section (C) is configured to sequentially scrub the first decarbonization gas from the first decarbonization section (B) with semi-lean methanol from a semi-lean stripper (T-008) and lean methanol from a lean methanol tank (V-004) to further remove CO therefrom 2 Obtaining a second decarbonized gas and CO-containing gas as the purge gas 2 Methanol solution;
the first decarbonization section (B) is configured to utilize the cooled CO-containing 2 Methanol liquid washes the desulfurization gas from the desulfurization section (a) to remove CO 2 Obtaining a first decarbonized gas and rich in CO 2 Methanol solution;
the desulfurization section (B) is configured to utilize a portion of the CO-enriched stream 2 Methanol liquid washes the feed gas from the feed gas separation tank (V-001) to remove H therefrom 2 S, obtaining a desulfurization gas and a sulfur-containing methanol rich solution;
a medium pressure flash column (T-002) comprising a first synthesis gas flash section (D) and a second synthesis gas flash section (E) arranged from top to bottom; wherein, the liquid crystal display device comprises a liquid crystal display device,
the first synthesis gas flash stage (D) is configured to recover a portion of the cold recovered CO-enriched stream after exiting the first decarbonization stage (B) 2 Dissolved H in methanol solution 2 Flashing CO to obtain the first flash gas and sulfur-free methanol liquid;
the second synthesis gas flash evaporation section (E) is configured to recover dissolved H in the sulfur-containing methanol rich liquid after flowing out of the desulfurization section (A) 2 Flashing the CO to obtain the second flash gas and a sulfur-containing methanol solution;
H 2 s concentration column (T-003), said H 2 The S concentration tower is sequentially provided with CO from top to bottom 2 The device comprises a flash evaporation section (F), a desorption section (G) and a stripping section (H), wherein the desorption section (G) is communicated with the stripping section (H) in a gas phase manner, so that the stripping gas of a lower stripping section rises to enter an upper desorption section to wash and remove sulfur;
the CO 2 A flash stage (F) is configured to cool the cooled first synthesis gas after exiting the first synthesis gas flash stage (D) CO in sulfur-free methanol solutions 2 Reduced pressure desorption is carried out to obtain desorbed methanol from the bottom and the CO from the top 2 Product gas;
the desorbing section (G) is configured to reject CO in the cooled sour methanol solution after exiting the second syngas flash section (E) 2 Performing reduced pressure desorption and introducing at an upper portion thereof a portion of said desorbed methanol for scrubbing the vapor phase in said desorption stage (G) to remove sulfur to obtain a desorption liquid and a sulfur-free desorption gas exiting from the top;
the stripping section (H) is configured to recover residual CO in the stripping liquid after the cooling capacity is recovered after the stripping section (G) 2 Stripping and desorbing to obtain sulfur-rich methanol at the bottom and stripping gas to be fed into the desorbing section (G) at the top;
a semi-lean liquid stripper (T-008) configured to utilize nitrogen to flow out of the CO 2 Partial desorption of CO from methanol in flash section (F) 2 Stripping to obtain a sulfur-free stripping gas and the semi-lean methanol and feeding the obtained semi-lean methanol to a second decarbonization section (B) of the scrubber (T-001) after cold recovery;
a normal temperature stripping tower (T-007) configured to utilize nitrogen to recycle CO remained in the sulfur-enriched methanol after flowing out of the stripping section (H) through cold recovery 2 Stripping to obtain a stripping gas rich in methanol and sulfur and feeding the obtained stripping gas containing sulfur to the stripping section (H) to recover sulfur;
a thermal regeneration tower (T-004) configured to thermally regenerate the cold recovered rich methanol after exiting the normal temperature stripping tower (T-007) to obtain hydrogen sulfide-containing gas at the top of the tower and hydrogen sulfide-removed lean methanol at the bottom of the tower; the tower bottom of the thermal regeneration tower (T-004) is provided with a matched thermal regeneration tower reboiler (E-011), the tower top is provided with a matched thermal regeneration tower top condenser (E-012) and a thermal regeneration tower top reflux tank (V-006), and the thermal regeneration tower top reflux tank is used for carrying out gas-liquid separation on materials from the thermal regeneration tower top condenser and sending out separated liquid phase as tower top reflux and separated gas phase materials;
a methanol-lean tank (V-004) configured to receive part of the methanol-lean from the thermal regeneration tower (T-004) and to deliver the methanol-lean to the feed gas through the first methanol-lean pipe (1) and to deliver the methanol-lean to the second decarbonization section (C) through the second methanol-lean pipe (2);
a third lean methanol pipe (3) for feeding part of lean methanol from the thermal regeneration tower (T-004) into the methanol/water separation tower (T-005) as top reflux after cooling;
CO 2 A flash tank (V-008) configured to recover CO in the aqueous methanol after cold recovery from the feed gas separation tank (V-001) 2 Flash evaporating and distilling the CO-containing material 2 Gas is fed into the H 2 Feeding the stripping section (H) of the S concentration tower (T-003) and the residual water-containing methanol into the methanol/water separation tower (T-005);
a methanol/water separation column (T-005) configured to separate the CO from the water 2 The method comprises the steps that (1) the methanol containing water in a flash tank (V-008) and the methanol in the methanol containing washing water in a tail gas water scrubber (T-006) are subjected to rectification separation, so that methanol steam is obtained at the top of the tower, and wastewater after methanol removal is obtained at the bottom of the tower; the bottom of the methanol/water separation tower (T-005) is provided with a matched methanol/water separation tower reboiler (E-015);
the first tail gas pipe (5) is used for sending the sulfur-free stripping gas and part of the sulfur-free stripping gas serving as tail gas to the raw gas cooler (E-001) for cold energy recovery and then sending the tail gas into a tail gas water scrubber (T-006);
the second tail gas pipe (6) is used for recycling the cold energy of the other part of the sulfur-free stripping gas and sending the other part of the sulfur-free stripping gas into a tail gas water scrubber (T-006);
and the tail gas water washing tower (T-006) is configured to wash the mixed gas of the gas sent by the first tail gas pipe (5) and the second tail gas pipe (6) by utilizing part of cooled wastewater after flowing out of the methanol/water separation tower (T-005) and desalted water from the outside in sequence so as to obtain the dischargeable tail gas and the methanol-containing washing water.
2. The cryogenic methanol scrubbing system of claim 1 further comprising H 2 S fraction heat exchanger (E-014), H 2 S fraction chiller (E-013)And H 2 S gas separation tank (V-005); wherein the H is 2 An S gas separation tank is configured to feed the heat regeneration overhead reflux drum (V-006) sequentially through the H 2 S fraction heat exchanger (E-014) and H 2 The gas phase material cooled by the S fraction cryocooler (E-013) is subjected to gas-liquid separation, and the separated liquid phase is sent to the stripping section and separated H 2 S gas is sent to the H 2 An S fraction heat exchanger (E-014) for recovering cold by exchanging heat with the gas phase material.
3. Cryogenic methanol washing system according to claim 1 or 2, further comprising a methanol-lean pump (P-004) and a methanol-lean water cooler (E-018) for pressurizing and water-cooling the methanol-lean in sequence before the methanol-lean from the methanol-lean tank (V-004) enters the first methanol-lean pipe (1) and the second methanol-lean pipe (2);
a 1# lean methanol cooler (E-009), a lean methanol cryocooler (E-005) for further cooling lean methanol in the second lean methanol pipe, a 2# lean methanol cooler (E-008) and a lean methanol/semi-lean methanol heat exchanger (E-021) are sequentially arranged on the second lean methanol pipe along the material flow direction;
Wherein the # 1 lean methanol cooler (E-009) is configured to heat exchange and raise the temperature of the sulfur-rich methanol from the stripping section (H) with the lean methanol in the second lean methanol pipe before entering the normal temperature stripper column (T-007);
the 2# lean methanol cooler (E-008) is configured to heat the desorption liquid from the desorption section (G) with lean methanol in the second lean methanol pipe;
the lean methanol/semi-lean methanol heat exchanger (E-021) is configured to exchange heat semi-lean methanol to be fed into the second decarbonization section (C) with lean methanol in the second lean methanol pipe to cool the lean methanol.
4. A cryogenic methanol washing system according to claim 3, further comprising a 3# methanol liquid pump (P-003) and a 1# methanol rich filter (S-002) for pressurizing and filtering the sulfur-rich methanol from the stripping section (H) in sequence before it enters the 1# methanol lean cooler (E-009);
a 1# methanol liquid pump (P-002), a 2# methanol rich filter (S-003) and a heat regeneration tower feeding heater (E-010) are sequentially arranged on a pipeline for feeding rich methanol from the normal temperature stripping tower (T-007) into the heat regeneration tower (T-004) along the flow direction, wherein the 1# methanol liquid pump (P-002) and the 2# methanol rich filter (S-003) are used for sequentially pressurizing, conveying and filtering the rich methanol before the rich methanol enters the heat regeneration tower feeding heater (E-010); the thermal regeneration column feed heater (E-01) 0 is used to heat up the rich methanol in heat exchange with the lean methanol to be fed into the lean methanol tank (V-004).
5. The low temperature methanol washing system as in claim 4 wherein,
a purified gas/methanol-rich heat exchanger (E-017) is arranged on a pipeline for conveying the sulfur-containing methanol rich liquid from the desulfurization section (A) to the second synthesis gas flash evaporation section (E) and is used for heat exchanging and heating the sulfur-containing methanol rich liquid and purified gas to be fed into the raw gas cooler (E-001);
in the first decarbonization section (B) to be rich in CO 2 A scrubber methanol-rich heat exchanger (E-007) is arranged on the pipeline for conveying the methanol liquid to the first synthesis gas flash evaporation section (D) and is used for enriching the CO 2 The methanol liquid exchanges heat with the desorption liquid to be fed into the stripping section (H) and is heated;
a tail gas/nitrogen heat exchanger (E-019) is arranged on the second tail gas pipe (6) and is used for heat exchanging and heating the sulfur-free stripping gas to be fed into the tail gas water scrubber (T-006) and the nitrogen to be fed into the semi-lean liquid stripper (T-008);
a methanol/water separation tower feeding heater (E-016) is arranged on the third methanol-lean pipe (3) for enabling the CO to enter 2 The heat exchange and temperature rise of the aqueous methanol in the flash tank (V-008) and the lean methanol which is to enter the methanol/water separation tower (T-005) as the top reflux;
and a waste water heat exchanger (E-020) is arranged on a pipeline for feeding the waste water into the tail gas water scrubber (T-006) and is used for heat exchange and temperature rise of the washing water containing methanol to be fed into the methanol/water separator (T-005) and the waste water to be fed into the tail gas water scrubber (T-006).
In the process of introducing the CO-containing gas into the reactor 2 The pipeline for conveying the methanol solution from the second decarburization section (C) to the first decarburization section (B) is provided with a device for cooling the CO-containing gas 2 A scrubber section inter-column chiller for methanol solution (E-006);
a sulfur-containing methanol chiller (E-003) for cooling the sulfur-containing methanol is arranged on a pipeline for conveying the sulfur-containing methanol from the second synthesis gas flash evaporation section (E) to the desorption section (G);
after passing the sulfur-free methanol from the first syngas flash stage (D) to the CO 2 The pipeline of the flash evaporation section (F) is provided with a sulfur-free methanol chiller (E-004) for cooling the sulfur-free methanol.
6. The cryogenic methanol washing system according to claim 5, characterized in that the bottom of the thermal regeneration column (T-004) is provided with a partition (8) dividing the bottom of the thermal regeneration column (T-004) into a first zone of relatively smaller zone volume and a second zone of relatively larger zone volume; wherein the lean methanol tank (V-004) is connected to the first zone through a fourth methanol pipe (7) to receive lean methanol cooled by the thermal regeneration tower feed heater (E-010), the third lean methanol pipe (3) is connected to the second zone, and a thermal regeneration tower bottom pump (P-005) and a lean methanol filter (S-001) are further arranged on the third lean methanol pipe, and are used for sequentially pressurizing, conveying and filtering lean methanol to be fed into the methanol/water separation tower feed heater (E-016);
The fourth lean methanol pipe (4) is connected with a lean methanol inlet of the reboiler (E-011) of the thermal regeneration tower through a first standby pipe (9), and is connected with a lean methanol inlet of the feed heater (E-016) of the methanol/water separation tower through a second standby pipe (10).
7. The cryogenic methanol scrubbing system of claim 6 further comprising:
a semi-lean methanol liquid pump (P-008) for pressurizing and conveying the semi-lean methanol to be fed into the lean methanol/semi-lean methanol heat exchanger (E-021);
a 1# methanol liquid pump (P-001) for pressurizing and conveying the desorption liquid to be fed into the 2# lean methanol cooler (E-008);
a thermal regeneration overhead reflux pump (P-006) for pressurizing and delivering an overhead reflux liquid from the thermal regeneration overhead reflux drum (V-006);
and the water washing tower bottom pump (P-007) is used for pressurizing and conveying the washing water containing methanol to be fed into the waste water heat exchanger (E-020).
8. The low-temperature methanol washing system according to claim 1 or 7, wherein a circulating gas compressor (C-001) and a circulating gas compressor outlet cooler (E-002) are sequentially arranged on the circulating gas pipe (4) in the flow direction, and are used for sequentially compressing and water-cooling the circulating gas.
9. Cryogenic methanol scrubbing system according to claim 1 or 8, further comprising a CO2 discharge pipe (11) for feeding CO2 product gas from the feed gas cooler (E-001) as off-gas to be discharged into the off-gas water scrubber (T-006).
10. A method of treating unconverted gas using the cryogenic methanol scrubbing system of any one of claims 1-9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310841015.XA CN116694370A (en) | 2023-07-10 | 2023-07-10 | Low-temperature methanol washing system and method for treating unconverted air |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310841015.XA CN116694370A (en) | 2023-07-10 | 2023-07-10 | Low-temperature methanol washing system and method for treating unconverted air |
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| CN116694370A true CN116694370A (en) | 2023-09-05 |
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| CN202310841015.XA Pending CN116694370A (en) | 2023-07-10 | 2023-07-10 | Low-temperature methanol washing system and method for treating unconverted air |
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2023
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