CN118562536A - Low temperature methanol washing rich liquid desorption system and method - Google Patents
Low temperature methanol washing rich liquid desorption system and method Download PDFInfo
- Publication number
- CN118562536A CN118562536A CN202410766253.3A CN202410766253A CN118562536A CN 118562536 A CN118562536 A CN 118562536A CN 202410766253 A CN202410766253 A CN 202410766253A CN 118562536 A CN118562536 A CN 118562536A
- Authority
- CN
- China
- Prior art keywords
- section
- flash evaporation
- liquid
- gas
- phase
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
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
- C10K1/165—Purifying combustible gases containing carbon monoxide by washing with liquids; Reviving the used wash liquors with non-aqueous liquids at temperatures below zero degrees Celsius
-
- 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
- B01D3/065—Multiple-effect flash distillation (more than two traps)
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/50—Carbon dioxide
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Inorganic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to the technical field of low-temperature methanol washing processes, and particularly relates to a desorption system and a desorption method for a low-temperature methanol washing rich liquid. The system comprises a decompression regeneration tower and a rectifying tower, wherein the decompression regeneration tower is divided into a first flash evaporation section, a second flash evaporation section and a thermal regeneration section, the first flash evaporation section is used for flashing a lower base solution from a medium-pressure recovery device, the second flash evaporation section is used for flashing a first liquid phase, the thermal regeneration section is used for regenerating a second liquid phase, and gas-phase materials from the first flash evaporation section, the second flash evaporation section and the thermal regeneration section respectively independently enter a gas-liquid separation device; the rectifying tower is divided into a third flash evaporation section and a rectifying section, one part of upper base liquid from the medium-pressure recovery device enters the third flash evaporation section to be subjected to flash evaporation, and the other part of upper base liquid from the medium-pressure recovery device, a liquid phase part from the third flash evaporation section and a gas phase from the gas-liquid separation device enter the rectifying section to be subjected to rectification. The process can realize that the low-temperature methanol washing system directly produces the CO 2 product with high concentration.
Description
Technical Field
The invention relates to the technical field of low-temperature methanol washing processes, in particular to a low-temperature methanol washing rich liquid desorption system and a method.
Background
For the traditional low-temperature methanol washing process, the main purpose is to remove acid gases including CO 2,H2 S, COS and the like in the synthesis gas of the coal gas. FIG. 1 is a typical low temperature methanol wash process, consisting essentially of eight columns, each with a function. The absorption tower (C01) is responsible for absorbing and purifying acid gases such as CO 2, H 2 S and the like; the CO 2 desorption tower (C02) is responsible for desorbing carbon dioxide; the N 2 stripper (C03) is responsible for further desorbing carbon dioxide to relatively concentrate hydrogen sulfide; the methanol heat regeneration tower (C04) is responsible for resolving the methanol-rich solution into a methanol-lean solution so as to realize the methanol heat regeneration; the methanol-water separation tower (C05) is responsible for separating methanol and water; the tail gas water scrubber (C06) is responsible for removing methanol in the tail gas; the normal temperature N 2 stripping tower (C07) is responsible for desorbing CO 2 under normal temperature conditions; the medium pressure flash column (C08) is responsible for recovering the useful gas under medium pressure conditions. The following details of the first 6 columns are provided below:
(1) The water component in the raw material gas is easy to freeze at low temperature, so that a pipeline is blocked, the raw material gas is contacted with a small amount of methanol before entering a system, then the raw material gas exchanges heat with purified gas and CO 2 product gas, the primarily recovered cold energy reaches about minus 25 ℃ and then enters a separation tank (V01), and the gas with the water removed from the top of the V01 tank enters the absorption tower C01. The C01 tower is divided into 4 sections, namely a desulfurization section, a coarse decarburization section, a main decarburization section and a fine decarburization section from bottom to top. The gas phase flow from the top of the V01 tank enters a desulfurizing section at the lower section of the C01, and H 2 S in the raw material gas is removed by using cold methanol solution, so that the purpose of purifying sulfide is achieved. And then the top gas of the desulfurization section sequentially enters a coarse decarburization section, a main decarburization section and a fine decarburization section, the circulating lean methanol solution and the circulating semi-lean methanol solution from the subsequent process are utilized to absorb CO 2 in the raw gas, the problem of stream temperature rise caused by the absorption of impurity gas by methanol is solved between two adjacent sections by utilizing a heat exchanger, and the cooled stream returns to the adjacent rectification section. Finally, a purified air flow meeting the purification requirement is obtained at the top of the absorption tower and is sent out of the system after heat exchange. And (3) obtaining a sulfur-containing methanol-rich solution at the bottom of the desulfurization section and a sulfur-free methanol-rich solution at the bottom of the crude decarburization section, sending the sulfur-containing methanol-rich solution to a flash tower (C08), realizing recovery of useful gases such as CO, H 2 and the like, and returning the useful gases to the feed gas. The bottom liquid phase of C08 enters a CO 2 resolving tower (C02) to be used as an absorbent.
(2) The CO 2 desorber C02C 02 tower consists of three sections, the lower section of the tower flash-flashes the liquid phase stream from the N 2 stripping tower (C03), the gas phase at the top of the tower enters the middle section, and the liquid phase at the bottom of the tower is sent to the C03 tower. The middle section of the tower utilizes the bottom liquid phase of C08 to analyze CO 2, and the bottom liquid phase of the middle section enters the C03 tower. The upper tower section flash flashes the stream from the medium pressure flash, and the high purity CO 2 product gas is obtained at the top of the tower. Thus completing the preliminary analysis of CO 2 in the methanol-rich solution and laying a foundation for the subsequent process.
(3) The upper section of the N 2 stripping tower C03N 2 flash distillation is carried out on a liquid phase flow from the C08 tower, gas phase at the top is mixed with gas phase at the top of the middle section and then enters a tail gas water scrubber (C06), and semi-lean methanol liquid at the bottom is returned to the C01 tower, so that the cyclic utilization of methanol is realized. The liquid phase discharged material flowing out of the middle section has the lowest temperature in the whole flow, and the cold energy of the partial flow is fully utilized through multiple heat exchange. The lower section carries out CO 2 desorption process on the methanol-rich solution discharged from the liquid phase at the bottom of the C02 tower under the combined action of N 2 and gas at the top of a normal-temperature N 2 stripping tower (C07), and the liquid phase at the bottom of the tower enters the C07 tower to improve Jie Xineng force, so that the relative concentration of hydrogen sulfide is realized. The methanol-rich liquid containing substantially all sulfides obtained at the bottom of the C07 column is fed into a methanol thermal regeneration column C04.
(4) In order to fully utilize methanol and reduce the input amount of the methanol, the methanol heat regeneration tower C04-24 regenerates the methanol-rich solution flowing through the flow path. And heating the methanol solution in the C04 tower by using a reboiler to realize methanol vaporization operation, further completing the regeneration of rising methanol steam, returning one part of the lean methanol solution at the bottom of the tower to the absorption tower after heat exchange to be used as spraying methanol for recycling, and entering the other part of the lean methanol solution into the methanol-water separation tower for subsequent treatment. Because there is some methanol vaporization loss in the whole system, a small amount of fresh methanol is fed into the system at the bottom of the column and mixed with the lean methanol solution that completes the thermal regeneration. The gas phase discharge from the top of the C04 tower is rich in sulfides, and the acid gas stream is sent to a sulfur recovery system after flash evaporation.
(5) The methanol-water separation tower C05 has higher water content in a part of lean methanol solution from the bottom of the methanol-heat regeneration tower, a liquid phase flow from the bottom of the separation tank V01 and a liquid phase discharge from the bottom of the methanol-water washing tower (C06), and influences the recycling of methanol in the system, so that the methanol-water separation operation is carried out through the methanol-water separation tower (C05). Methanol steam obtained in the C05 tower through the rectification process returns to the C04 tower again, enters a system for recycling after thermal regeneration, and participates in gas purification. The methanol content of the liquid phase at the bottom of the C05 tower meets the discharge standard requirement, and part of the liquid phase after heat exchange and cold recovery is used as a wastewater discharge system, and the other part of the liquid phase enters the C06 tower to wash tail gas. The tower ensures that the water content in the recycled methanol is maintained at a lower level, and ensures the desulfurization and decarbonization capacity of the methanol.
(6) Because the methanol content in the gas phase flow from the top of the C03 tower does not meet the process standard and is harmful to the environment, the flow is sent to the tail gas water scrubber C05 after heat exchange, and the desalted water and the water from the bottom of the C05 tower, which contains a very small amount of methanol, are utilized to remove the methanol in the tail gas through rectification. The tail gas after washing meets the requirement of emission standard and can be directly discharged into the atmosphere. Meanwhile, because the design ensures that the system runs at low temperature as an important factor to be considered, a plurality of heat exchangers exist in the process to meet the energy requirement of the system in order to ensure that the developed process meets the purification requirement and process index.
However, the main disadvantage of this process is that nitrogen stripping causes dilution of the CO 2 concentration, with nearly 80% of the CO 2 concentration, which is often directly vented to the atmosphere during chemical processes, which is undesirable in the carbon neutral context.
Disclosure of Invention
The invention aims to overcome the problems that the existing low-temperature methanol washing mainly adopts nitrogen gas stripping to realize desorption of CO 2 and simultaneously dilute the concentration of CO 2, nearly half of the concentration of CO 2 is only 80 percent, and the CO 2 is always directly discharged into the atmosphere in the chemical process, and provides a low-temperature methanol washing rich liquid desorption system and a method.
In order to achieve the above object, the present invention provides in one aspect a low-temperature methanol-rich liquid desorption system comprising a reduced pressure regeneration column and a rectification column,
The pressure reduction regeneration tower is divided into a first flash evaporation section, a second flash evaporation section and a thermal regeneration section from top to bottom, wherein the first flash evaporation section is used for flashing a lower bottom liquid from the medium pressure recovery device, the second flash evaporation section is used for flashing a first liquid phase from the first flash evaporation section, the thermal regeneration section is used for regenerating a second liquid phase from the second flash evaporation section, and gas-phase materials from the first flash evaporation section, the second flash evaporation section and the thermal regeneration section respectively independently enter a gas-liquid separation device for gas-liquid separation;
The rectifying tower is divided into a third flash evaporation section and a rectifying section from top to bottom, one part of upper base liquid from the medium-pressure recovery device enters the third flash evaporation section for flash evaporation, and the other part of upper base liquid from the medium-pressure recovery device, the liquid phase part from the third flash evaporation section and the gas phase part from the gas-liquid separation device enter the rectifying section for rectification independently.
Preferably, the thermal regeneration section regenerates in a manner of reboiling heating.
Preferably, the heat source for reboiling heating is a vapor source or exchanges heat with other streams inside the low temperature methanol wash to recover refrigeration.
Preferably, the system further comprises pressurizing means for pressurizing the gas phase fraction from the gas-liquid separation means.
Preferably, the liquid phase fraction from the thermal regeneration section is withdrawn from the bottom and passed to a methanol thermal regeneration column for treatment.
Preferably, the liquid phase part from the gas-liquid separation device enters a methanol thermal regeneration tower for treatment.
Preferably, the liquid phase material from the bottom of the rectifying section is returned to the second flash section for flash evaporation.
Preferably, the decompression regeneration tower and the rectifying tower are arranged in series or in a split type.
In a second aspect the present invention provides a low temperature methanol wash rich solution desorption process carried out in a system as hereinbefore described, the process comprising the steps of:
(1) Performing first adiabatic flash evaporation on lower base liquid from a medium-pressure recovery device to obtain a first gas phase and a first liquid phase, performing second adiabatic flash evaporation on the obtained first liquid phase to obtain a second gas phase and a second liquid phase, performing thermal regeneration on the obtained second liquid phase to obtain a third gas phase and a third liquid phase, and performing gas-liquid separation on the first gas phase, the second gas phase and the third gas phase to obtain a fourth gas phase and a fourth liquid phase;
(2) And (3) carrying out third adiabatic flash evaporation on a part of the upper base liquid from the medium-pressure recovery device to obtain a fifth gas phase and a fifth liquid phase, and rectifying the other part of the upper base liquid from the medium-pressure recovery device, the fifth liquid phase and the fourth gas phase.
Preferably, in step (1), the pressure of the first adiabatic flash is 0.2 to 0.21MPa.
Preferably, the pressure of the second adiabatic flash evaporation is 0.1-0.11 MPa.
Preferably, the pressure of the thermal regeneration is 0.1-0.11 MPa, and the temperature of the tower kettle is 43-53 ℃.
Preferably, the pressure of the third adiabatic flash evaporation is 0.28-0.3 MPa.
Preferably, the pressure of the rectification is 0.28-0.3 MPa, and the temperature is-34 to-39 ℃.
Preferably, in the step (2), the content of CO 2 in the fifth gas phase obtained by the third adiabatic flash distillation and the rectification is 99 to 99.5mol% and the content of H 2 S is 10 to 20ppm.
Preferably, the refrigeration capacity lost by the original low-temperature methanol washing system is supplemented by a refrigerator due to the system modification.
Compared with the prior art, the invention has at least the following advantages:
(1) The system adopts a decompression regeneration tower with a first flash evaporation section, a second flash evaporation section and a thermal regeneration section to replace a CO 2 desorption tower and an N 2 stripping tower in the original process, firstly, the lower base liquid of a medium-pressure recovery device rich in CO 2 and H 2 S is pretreated to obtain a gas-phase material rich in CO 2 and H 2 S, and then the upper base liquid from the medium-pressure recovery device is adopted in the rectification tower to absorb H 2 S in the gas-phase material obtained by pretreatment, so that the efficient recovery of CO 2 is realized, meanwhile, the CO 2 gas with high purity is obtained, the carbon emission in a chemical process system is effectively reduced, and the low carbonization and sustainable development of the booster chemical industry are realized.
(2) According to the method, the secondary flash evaporation and the thermal regeneration are carried out on the lower base solution of the medium-pressure recovery device, so that gas and liquid can be well separated, a gas-phase material rich in CO 2 and H 2 S can be obtained, then the gas-phase material and the upper base solution of the medium-pressure recovery device are rectified, H 2 S in the gas-phase material can be absorbed, and therefore efficient recovery of CO 2 is achieved, and meanwhile high-purity CO 2 gas is obtained.
Drawings
FIG. 1 is a flow chart of a typical low temperature methanol wash process in the prior art.
Fig. 2 is a schematic diagram of a low temperature methanol wash rich solution desorption system in accordance with one embodiment of the present invention.
Fig. 3 is a schematic diagram of a low temperature methanol wash rich solution desorption system in accordance with another embodiment of the present invention.
Description of the reference numerals
A T-201 decompression regeneration tower; a T-202 rectifying tower; 1a first flash stage; 2a second flash stage; 3a thermal regeneration section; 4, a gas-liquid separation device; 5a third flash stage; 6, rectifying section; 7, a heat source; 8 supercharging device.
Detailed Description
The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
In a first aspect of the present invention, there is provided a low temperature methanol-rich liquid desorption system, as shown in fig. 2 and 3, which comprises a reduced pressure regeneration column T-201 and a rectification column T-202,
The pressure-reducing regeneration tower T-201 is divided into a first flash evaporation section 1, a second flash evaporation section 2 and a thermal regeneration section 3 from top to bottom, wherein the first flash evaporation section 1 is used for flashing a lower bottom liquid from a medium-pressure recovery device, the second flash evaporation section 2 is used for flashing a first liquid phase from the first flash evaporation section 1, the thermal regeneration section 3 is used for regenerating a second liquid phase from the second flash evaporation section 2, and gas-phase materials from the first flash evaporation section 1, the second flash evaporation section 2 and the thermal regeneration section 3 respectively independently enter a gas-liquid separation device 4 for gas-liquid separation;
The rectifying tower T-202 is divided into a third flash evaporation section 5 and a rectifying section 6 from top to bottom, one part of the upper bottom liquid from the medium-pressure recovery device enters the third flash evaporation section 5 for flash evaporation, the other part of the upper bottom liquid from the medium-pressure recovery device, the liquid phase part from the third flash evaporation section 5 and the gas phase part from the gas-liquid separation device 4 enter the rectifying section 6 for rectification independently.
In the system according to the invention, the lower bottoms from the medium pressure recovery unit (medium pressure flash column C08 in fig. 1) is methanol rich in CO 2 and H 2 S. The upper bottoms from the medium pressure recovery unit is methanol containing CO 2 and H 2 S, with a lower content of CO 2、H2 S relative to the lower bottoms from the medium pressure recovery unit, CO 2 and H 2 S.
The working flow of the system of the invention is as follows: the lower bottom liquid from the medium-pressure recovery device is subjected to flash evaporation in a first flash evaporation section 1, CO 2、H2 S is desorbed from methanol, a first gas phase material containing CO 2、H2 S and a small amount of methanol is discharged from the top of the first flash evaporation section 1 and enters a gas-liquid separation device 4 for gas-liquid separation, methanol containing CO 2 is subjected to flash evaporation in a second flash evaporation section 2, CO 2 is desorbed from methanol, a second gas phase material containing CO 2 and a small amount of methanol is discharged from the upper part of the second flash evaporation section 2 and enters the gas-liquid separation device 4 for gas-liquid separation, methanol containing CO 2 enters the thermal regeneration section 3 for regeneration, CO 2 is desorbed from methanol, a third gas phase material containing CO 2 and a small amount of methanol is discharged from the upper part of the thermal regeneration section 3 and enters the gas-liquid separation device 4 for gas-liquid separation, methanol is discharged from the bottom of the thermal regeneration section 3, and the first gas phase material, the second gas phase material and the third gas phase material are discharged from the gas-liquid separation device 4 for gas-liquid separation, and the gas phase material is liquefied in the rectification section 6; in the rectifying tower T-202, part of the upper base liquid from the medium-pressure recovery device is flashed in the third flash evaporation section 5, high-purity carbon dioxide gas-phase products are discharged from the top of the third flash evaporation section 5, a liquid phase obtained by flashing enters the rectifying section 6, the other part of the upper base liquid from the medium-pressure recovery device enters the rectifying section 6, H 2 S of the gas-phase products from the gas-liquid separation device 4 is absorbed, concentration of sulfide components is achieved, a methanol liquid-phase material rich in H 2 S is further obtained, the methanol liquid-phase material is discharged from the bottom of the rectifying section 6, and high-purity carbon dioxide gas-phase products are discharged from the top of the third flash evaporation section 5.
In the present invention, the system further comprises a methanol thermal regeneration column.
In a specific embodiment, the liquid phase fraction from the thermal regeneration section 3 is withdrawn from the bottom and fed into a methanol thermal regeneration column for treatment according to conventional operations.
In a specific embodiment, the liquid phase part from the gas-liquid separation device 4 enters a methanol thermal regeneration tower for treatment according to the conventional operation.
In the present invention, the flash apparatuses of the first flash stage 1, the second flash stage 2 and the third flash stage 5 may be conventional choices in the art, and may be flash tanks, for example.
In the present invention, the mode of regenerating methanol in the thermal regeneration section 3 is reboiling heating. In particular, the heat source 7 for reboiling heating can be a vapor source, the vapor parameter depends on specific working conditions, or the vapor can exchange heat with other streams in the low-temperature methanol wash to recover cold.
In the system of the invention, the liquid phase material discharged from the bottom of the rectifying section 6 is rich in hydrogen sulfide, and can be returned to the second flash evaporation section 2 for flash evaporation treatment.
In the present invention, the system further comprises a pressurizing device 8 for pressurizing the gas phase portion from the gas-liquid separation device 4 and feeding the gas phase portion into the rectifying section 6. In a specific embodiment, the pressurizing device 8 may be a pressurizing pump.
In the present invention, the installation positions of the pressure reducing and regenerating column T-201 and the rectifying column T-202 are not limited as long as they can be carried out according to the aforementioned streams.
In one embodiment, as shown in FIG. 2, the pressure reducing regeneration column T-201 and the rectification column T-202 may be provided as separate units. In another embodiment, as shown in FIG. 3, the pressure reduction regeneration column T-201 and the rectification column T-202 may be arranged in series.
In the invention, the refrigeration capacity lost by the original low-temperature methanol washing system is supplemented by the refrigerator due to the system transformation.
In a second aspect the present invention provides a low temperature methanol wash rich solution desorption process carried out in a system as hereinbefore described, the process comprising the steps of:
(1) Performing first adiabatic flash evaporation on lower base liquid from a medium-pressure recovery device to obtain a first gas phase and a first liquid phase, performing second adiabatic flash evaporation on the obtained first liquid phase to obtain a second gas phase and a second liquid phase, performing thermal regeneration on the obtained second liquid phase to obtain a third gas phase and a third liquid phase, and performing gas-liquid separation on the first gas phase, the second gas phase and the third gas phase to obtain a fourth gas phase and a fourth liquid phase;
(2) And (3) carrying out third adiabatic flash evaporation on a part of the upper base liquid from the medium-pressure recovery device to obtain a fifth gas phase and a fifth liquid phase, and rectifying the other part of the upper base liquid from the medium-pressure recovery device, the fifth liquid phase and the fourth gas phase.
In the process according to the invention, the lower bottoms from the medium pressure recovery unit (medium pressure flash column C08 in FIG. 1) is methanol rich in CO 2 and H 2 S. The upper bottoms from the medium pressure recovery unit is methanol containing CO 2 and H 2 S, with a lower content of CO 2、H2 S relative to the lower bottoms from the medium pressure recovery unit, CO 2 and H 2 S.
In the method, a lower base liquid from a medium-pressure recovery device is subjected to first adiabatic flash evaporation, CO 2、H2 S is desorbed from methanol, first gas phase containing CO 2、H2 S and a small amount of methanol obtained by the first adiabatic flash evaporation is subjected to gas-liquid separation successively, methanol (first liquid phase) containing CO 2 obtained by the first adiabatic flash evaporation is subjected to second adiabatic flash evaporation, CO 2 in a first liquid phase is desorbed from the methanol, second gas phase containing CO 2 and a small amount of methanol obtained by the second adiabatic flash evaporation is subjected to gas-liquid separation successively, methanol (second liquid phase) containing CO 2 obtained by the second adiabatic flash evaporation is regenerated, CO 2 in the second liquid phase is desorbed from the methanol, a third gas phase containing CO 2 and a small amount of methanol obtained by the regeneration is continuously subjected to gas-liquid separation, the third liquid phase obtained by the regeneration is discharged from the bottom of the thermal regeneration section 3, the first gas phase, the second gas phase and the third gas phase are separated, the methanol contained in the gas phase is liquefied and discharged, and a gas phase product obtained by the gas-liquid separation is rectified; and (3) carrying out third adiabatic flash evaporation on one part of the upper base liquid from the medium-pressure recovery device to obtain a high-purity carbon dioxide gas-phase product, rectifying the liquid phase obtained by the third adiabatic flash evaporation and the gas-phase product obtained by gas-liquid separation with the other part of the upper base liquid from the medium-pressure recovery device, absorbing H 2 S in the gas-phase product obtained by gas-liquid separation of the liquid phase obtained by the third adiabatic flash evaporation and the other part of the upper base liquid from the medium-pressure recovery device, and concentrating sulfide components to obtain a methanol liquid-phase material rich in H 2 S and a high-purity carbon dioxide gas-phase product.
In a specific embodiment, in step (1), the pressure of the first adiabatic flash is 0.2 to 0.21MPa.
In a specific embodiment, the pressure of the second adiabatic flash is 0.1 to 0.11MPa.
In a specific embodiment, the pressure of the thermal regeneration is 0.1-0.11 MPa, and the temperature of the tower kettle is 43-53 ℃.
In a specific embodiment, the pressure of the third adiabatic flash is 0.28 to 0.3MPa.
In specific embodiments, the pressure of the rectification is 0.28-0.3 MPa, and the temperature is-34 to-39 ℃.
In a specific embodiment, in the step (2), the content of CO 2 in the fifth gas phase obtained by the third adiabatic flash distillation and the rectification is 99 to 99.5mol% and the content of H 2 S is 10 to 20ppm.
In a specific embodiment, the low-temperature methanol washing rich liquid desorption system is modified to cause the missing cold energy of the original low-temperature methanol washing system, and the cold energy is supplemented by a refrigerator.
The present invention will be described in detail by way of examples, but the scope of the present invention is not limited thereto.
The following examples are carried out in a system as shown in fig. 1, which includes a reduced pressure regeneration column T-201 and a rectification column T-202,
The pressure reduction regeneration tower T-201 is divided into a first flash evaporation section 1, a second flash evaporation section 2 and a thermal regeneration section 3 from top to bottom, the first flash evaporation section 1 is used for flashing a lower bottom liquid from the medium pressure recovery device, the second flash evaporation section 2 is used for flashing a first liquid phase from the first flash evaporation section 1, the thermal regeneration section 3 is used for regenerating a second liquid phase from the second flash evaporation section 2, gas phase materials from the first flash evaporation section 1, the second flash evaporation section 2 and the thermal regeneration section 3 respectively independently enter a gas-liquid separation device 4 for gas-liquid separation, a gas phase part of the gas-liquid separation device 4 enters the rectification section 6 for rectification after being pressurized by a booster pump, the thermal regeneration section 3 is regenerated in a way of reboiling and heating, a heat source 7 is a vapor source, a liquid phase part from the thermal regeneration section 3 is discharged from the bottom and enters the methanol thermal regeneration tower for treatment, and a liquid phase part from the gas-liquid separation device 4 enters the methanol thermal regeneration tower for treatment;
The rectifying tower T-202 is divided into a third flash evaporation section 5 and a rectifying section 6 from top to bottom, a part of upper base liquid from the medium-pressure recovery device enters the third flash evaporation section 5 for flash evaporation, another part of upper base liquid from the medium-pressure recovery device, a liquid phase part from the third flash evaporation section 5 and a gas phase part from the gas-liquid separation device 4 respectively enter the rectifying section 6 for rectification, liquid phase materials from the bottom of the rectifying section 6 return to the second flash evaporation section 2 for flash evaporation, and the refrigeration capacity lost by the original low-temperature methanol washing system is supplemented by a refrigerator due to system transformation.
In the following examples of the present invention,
The lower base fluid of the medium-pressure recovery device is a methanol solution containing CO 2 and H 2 S, wherein the content of CO 2 is 10.7mol percent, and the content of H 2 S is 0.08mol percent;
The upper base liquid of the medium-pressure recovery device is a methanol solution containing CO 2 and H 2 S, wherein the content of CO 2 is 10.17mol percent, and the content of H 2 S is 0.16ppm.
Examples simulations were performed using Aspen.
Example 1
(1) Performing first adiabatic flash on the lower base solution from the medium-pressure recovery device in a first flash section 1, wherein the pressure of the first adiabatic flash is 0.2MPa, so as to obtain a first gas phase and a first liquid phase, then performing second adiabatic flash on the obtained first liquid phase in a second flash section 2, wherein the pressure of the second adiabatic flash is 0.1MPa, so as to obtain a second gas phase and a second liquid phase, then performing thermal regeneration on the obtained second liquid phase in a thermal regeneration section 3, wherein the pressure of the thermal regeneration is 0.1MPa, the temperature is 43 ℃, so as to obtain a third gas phase and a third liquid phase, and performing gas-liquid separation on the first gas phase, the second gas phase and the third gas phase in a gas-liquid separation device 4, so as to obtain a fourth gas phase and a fourth liquid phase;
(2) And (3) carrying out third adiabatic flash evaporation on a part of the upper base liquid from the medium-pressure recovery device in a third flash evaporation section 5, wherein the pressure of the third adiabatic flash evaporation is 0.28MPa, so as to obtain high-purity carbon dioxide and a fifth liquid phase, and rectifying the other part of the upper base liquid from the medium-pressure recovery device, the fifth liquid phase and a fourth gas phase in a rectifying section 6, wherein the pressure of the rectifying is 0.28MPa, and the temperature is-34 to-39 ℃ so as to obtain the high-purity carbon dioxide.
The high purity carbon dioxide discharged from the top of the third flash stage 5 had a CO 2 content of 99.19mol% and a H 2 S content of 14ppm.
Example 2
(1) Performing first adiabatic flash on the lower base solution from the medium-pressure recovery device in a first flash section 1, wherein the pressure of the first adiabatic flash is 0.21MPa, so as to obtain a first gas phase and a first liquid phase, then performing second adiabatic flash on the obtained first liquid phase in a second flash section 2, wherein the pressure of the second adiabatic flash is 0.11MPa, so as to obtain a second gas phase and a second liquid phase, then performing thermal regeneration on the obtained second liquid phase in a thermal regeneration section 3, wherein the pressure of the thermal regeneration is 0.11MPa, the temperature is 53 ℃, so as to obtain a third gas phase and a third liquid phase, and performing gas-liquid separation on the first gas phase, the second gas phase and the third gas phase in a gas-liquid separation device 4, so as to obtain a fourth gas phase and a fourth liquid phase;
(2) And (3) carrying out third adiabatic flash evaporation on a part of the upper base liquid from the medium-pressure recovery device in a third flash evaporation section 5, wherein the pressure of the third adiabatic flash evaporation is 0.3MPa, so as to obtain high-purity carbon dioxide and a fifth liquid phase, and rectifying the other part of the upper base liquid from the medium-pressure recovery device, the fifth liquid phase and a fourth gas phase in a rectifying section 6, wherein the pressure of the rectifying is 0.3MPa, and the temperature is-35 to-39 ℃, so as to obtain the high-purity carbon dioxide.
The high purity carbon dioxide discharged from the top of the third flash stage 5 had a CO 2 content of 99.2mol% and a H 2 S content of 13.6ppm.
Comparative example 1
The process is carried out according to the conventional process, namely, the low-temperature methanol washing process flow shown in figure 1 is adopted.
The obtained CO 2 is divided into two streams, one stream is a CO 2 product produced from the top of the C02 tower, the content of CO 2 is 94-98 mol%, and the content of H 2 S is about 10ppm; the other stream is the tail gas produced from the top of the C03 tower, the content of CO 2 is 77-80 mol%, and the content of H 2 S is about 20ppm, and the tail gas is usually directly discharged.
It can be seen from examples and comparative examples that the implementation of the technical scheme according to the invention significantly improves the content of the obtained carbon dioxide, and reduces the content of H 2 S, i.e. the purity of the obtained carbon dioxide is significantly improved.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (11)
1. A low-temperature methanol rich liquid desorption system is characterized by comprising a decompression regeneration tower (T-201) and a rectifying tower (T-202),
The pressure reduction regeneration tower (T-201) is divided into a first flash evaporation section (1), a second flash evaporation section (2) and a thermal regeneration section (3) from top to bottom, the first flash evaporation section (1) is used for flashing a lower bottom liquid from the medium pressure recovery device, the second flash evaporation section (2) is used for flashing a first liquid phase from the first flash evaporation section (1), the thermal regeneration section (3) is used for regenerating a second liquid phase from the second flash evaporation section (2), and gas phase materials from the first flash evaporation section (1), the second flash evaporation section (2) and the thermal regeneration section (3) respectively independently enter a gas-liquid separation device (4) for gas-liquid separation;
The rectifying tower (T-202) is divided into a third flash evaporation section (5) and a rectifying section (6) from top to bottom, one part of upper bottom liquid from the medium-pressure recovery device enters the third flash evaporation section (5) for flash evaporation, the other part of upper bottom liquid from the medium-pressure recovery device, the liquid phase part from the third flash evaporation section (5) and the gas phase part from the gas-liquid separation device (4) enter the rectifying section (6) for rectification independently.
2. The system according to claim 1, characterized in that the thermal regeneration section (3) is regenerated by reboiling;
Preferably, the heat source (7) for reboiling and heating is a vapor source or exchanges heat with other streams in the low-temperature methanol wash to recover cold.
3. The system according to claim 1 or 2, characterized in that the system further comprises pressurizing means (8) for pressurizing the gas phase fraction from the gas-liquid separation means (4).
4. A system according to any one of claims 1-3, characterized in that the liquid phase fraction from the thermal regeneration section (3) is withdrawn from the bottom and passed into a methanol thermal regeneration column for treatment;
Preferably, the liquid phase part from the gas-liquid separation device (4) enters a methanol thermal regeneration tower for treatment.
5. A system according to any of claims 1-4, characterized in that the liquid phase material from the bottom of the rectifying section (6) is returned to the second flash section (2) for flash evaporation.
6. The system according to any one of claims 1-5, characterized in that the depressurization regeneration column (T-201) and the rectification column (T-202) are provided in a split type or in series.
7. A low temperature methanol wash rich liquid desorption method, which is carried out in the system as claimed in any one of claims 1 to 6, characterized in that the method comprises the steps of:
(1) Performing first adiabatic flash evaporation on lower base liquid from a medium-pressure recovery device to obtain a first gas phase and a first liquid phase, performing second adiabatic flash evaporation on the obtained first liquid phase to obtain a second gas phase and a second liquid phase, performing thermal regeneration on the obtained second liquid phase to obtain a third gas phase and a third liquid phase, and performing gas-liquid separation on the first gas phase, the second gas phase and the third gas phase to obtain a fourth gas phase and a fourth liquid phase;
(2) And (3) carrying out third adiabatic flash evaporation on a part of the upper base liquid from the medium-pressure recovery device to obtain a fifth gas phase and a fifth liquid phase, and rectifying the other part of the upper base liquid from the medium-pressure recovery device, the fifth liquid phase and the fourth gas phase.
8. The process of claim 7, wherein in step (1), the pressure of the first adiabatic flash is from 0.2 to 0.21MPa;
preferably, the pressure of the second adiabatic flash evaporation is 0.1-0.11 MPa;
preferably, the pressure of the thermal regeneration is 0.1-0.11 MPa, and the temperature of the tower kettle is 43-53 ℃.
9. The process according to claim 7 or 8, wherein the pressure of the third adiabatic flash is 0.28 to 0.3MPa;
Preferably, the pressure of the rectification is 0.28-0.3 MPa, and the temperature is-34 to-39 ℃.
10. The process according to any one of claims 7 to 9, wherein in step (2), the third adiabatic flash and the rectification result in a fifth gas phase having a CO 2 content of 99 to 99.5mol% and a H 2 S content of 10 to 20ppm.
11. The method according to any one of claims 7-10, characterized in that the refrigeration lost in the original cryogenic methanol wash system due to the retrofitting of the system is supplemented by a refrigerator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410766253.3A CN118562536A (en) | 2024-06-14 | 2024-06-14 | Low temperature methanol washing rich liquid desorption system and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410766253.3A CN118562536A (en) | 2024-06-14 | 2024-06-14 | Low temperature methanol washing rich liquid desorption system and method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118562536A true CN118562536A (en) | 2024-08-30 |
Family
ID=92477947
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410766253.3A Pending CN118562536A (en) | 2024-06-14 | 2024-06-14 | Low temperature methanol washing rich liquid desorption system and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN118562536A (en) |
-
2024
- 2024-06-14 CN CN202410766253.3A patent/CN118562536A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111303945B (en) | A process and device for low-temperature methanol washing with low energy consumption and high carbon capture rate | |
| US4305733A (en) | Method of treating natural gas to obtain a methane rich fuel gas | |
| CN105664671B (en) | A kind of zero carbon emission technique gas purifying method and device | |
| CN102491269A (en) | Method for extracting hydrogen gas from coke oven gas | |
| CN201439518U (en) | System for purifying crude synthetic gas with low-temperature methanol | |
| CN105523524A (en) | Apparatus and method for producing highly pure hydrogen sulfide | |
| CN114736719A (en) | Device and method for producing ethylene glycol and co-producing LNG and dimethyl carbonate | |
| CN105542876A (en) | Method for using low temperature methanol washing apparatus for removal of impurities in shift gas | |
| CN220758035U (en) | High-efficient ammonia stripping device of transform lime set single tower | |
| CN212560126U (en) | Low-temperature methanol washing process device with low energy consumption and high carbon capture rate | |
| CN113731117A (en) | Novel process for high-efficiency low-temperature methanol elution and pure recovery of carbon dioxide | |
| CN113368663B (en) | Treatment method of Fischer-Tropsch synthesis decarbonized tail gas and equipment system for implementing method | |
| CN107138025B (en) | Low-temperature methanol washing process for efficiently recycling pressure energy and cold energy | |
| CN112138421B (en) | Oil gas treatment device and method | |
| CN1356158A (en) | Physical process for removing sulfur and carbon by solvent | |
| CN220827260U (en) | Coal gasification ammonia-containing wastewater high-efficiency comprehensive recovery device | |
| CN118562536A (en) | Low temperature methanol washing rich liquid desorption system and method | |
| CN112210407A (en) | Pressurized raw coke oven gas purification system and process | |
| CN110791327A (en) | Device and process for deeply removing purified gas sulfide of low-temperature methanol washing system | |
| CN209940921U (en) | Device for treating low-temperature methanol-washed hydrocarbon-containing exhaust gas | |
| CN108014598B (en) | Non-methane alkane in low-temperature methanol washing tail gas of crushed coal is removed and C is recovered2+Hydrocarbon system and method | |
| CN111004082A (en) | System and method for removing carbon dioxide from C2 fraction | |
| CN113019071A (en) | High CO2Recycled semi-barren solution circulation low-temperature methanol washing process | |
| CN222694354U (en) | Device for removing acid gas | |
| CN222694353U (en) | Device for removing acid gas and recovering food-grade product gas |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |