CN109321285B - Energy-saving low-temperature methanol washing device and method - Google Patents
Energy-saving low-temperature methanol washing device and method Download PDFInfo
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- CN109321285B CN109321285B CN201811288498.0A CN201811288498A CN109321285B CN 109321285 B CN109321285 B CN 109321285B CN 201811288498 A CN201811288498 A CN 201811288498A CN 109321285 B CN109321285 B CN 109321285B
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- 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
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- 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
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- 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
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
Abstract
The invention provides an energy-saving low-temperature methanol washing device and method. In the process of the low-temperature methanol washing process, the conversion gas to be treated by the low-temperature methanol washing is subjected to advanced freezing liquefaction to separate part of carbon dioxide, and simultaneously part of hydrogen sulfide in the conversion gas is taken out by the liquid carbon dioxide, so that the amount of methanol used for washing in the low-temperature methanol washing process is reduced. The shift gas is cooled and frozen before entering methanol washing, and part of carbon dioxide and hydrogen sulfide in the shift gas are liquefied and separated, so that the using amount of methanol in the washing process can be reduced, the energy consumption for conveying the methanol is reduced, the using amount of low-temperature cold energy in the process is reduced, and the purposes of saving energy and reducing consumption in the purification process are achieved.
Description
Technical Field
The invention belongs to the field of gas purification, and particularly relates to energy conservation and consumption reduction of a low-temperature methanol washing purification process.
Background
Coal gasification has a certain proportion in the field of energy utilization and tends to expand gradually. The subsequent treatment of coal gasification has a gas purification process.
The low-temperature methanol washing purification process is a common choice for gas purification in the current coal chemical industry due to good selectivity and high purification degree of gas components.
The shift gas treated by the low-temperature methanol washing has the characteristic of being rich in carbon dioxide, and the carbon dioxide has the characteristic of low-temperature liquefaction and can be frozen, liquefied and separated to obtain part of the carbon dioxide in the shift gas; hydrogen sulfide has the property of dissolving in liquid carbon dioxide, and part of hydrogen sulfide in the converted gas is separated simultaneously with the separation of liquid carbon dioxide.
Disclosure of Invention
The invention aims to provide an energy-saving low-temperature methanol washing device and method, which are used for freezing and cooling a process gas needing methanol washing and purification in advance and liquefying part of carbon dioxide and hydrogen sulfide in the process gas so as to reduce the consumption of methanol in the washing process and achieve the purposes of saving energy and reducing consumption in the low-temperature methanol washing process.
The technical conception of the invention is as follows:
the change gas contains a certain amount of carbon dioxide, and the carbon dioxide has the property of low-temperature liquefaction, so that part of the carbon dioxide in the change gas is separated by freezing liquefaction, and the purpose of reducing the amount of methanol for washing the carbon dioxide can be achieved;
the amount of hydrogen sulfide dissolved in liquid carbon dioxide can be reduced by liquefying and separating carbon dioxide in the shift gas and separating part of hydrogen sulfide in the shift gas, thereby reducing the amount of methanol used for washing hydrogen sulfide.
Based on the above conception, the invention provides an energy-saving low-temperature methanol washing device, wherein a methanol liquid pipeline and a conversion gas pipeline are connected with a first process heat exchanger, the first process heat exchanger is connected with a first separating tank, the first separating tank is connected with a second process heat exchanger, the second process heat exchanger is connected with a third process heat exchanger, the third process heat exchanger is connected with a second separating tank, and the second separating tank is connected with a process gas washing tower.
And the second separation tank is connected with the third separation tank, the bottom of the third separation tank is connected with the third process heat exchanger through a pipeline, and the top of the third separation tank is connected to the circulating gas compressor through a pipeline.
And the third process heat exchanger is respectively connected with pipelines to different hydrogen sulfide concentration towers.
The bottom of the separation tank is connected to a methanol/water separation column through a pipeline.
The specific method comprises the following steps:
step S1: separating part of carbon dioxide in the process gas by freezing, cooling and liquefying the process gas treated by low-temperature methanol washing;
step S2: the liquefied and separated liquid carbon dioxide is heated and flashed to provide cold energy for cooling the process gas.
In step S1, the process gas treated by the low-temperature methanol washing is subjected to a low-temperature methanol washing process after being frozen, liquefied, and separated into carbon dioxide. The process gas treated by the low-temperature methanol washing is frozen, and the low-temperature cold energy of the process gas comes from the flash evaporation of the liquid carbon dioxide. In the flash evaporation process of the liquid carbon dioxide, the lower the pressure is, the lower the temperature is, the better the temperature reduction degree is, the larger the proportion of the carbon dioxide subjected to the process gas liquefaction separation and treated by the low-temperature methanol washing is, and the more energy conservation and consumption reduction are facilitated. Hydrogen sulfide is dissolved in carbon dioxide subjected to liquefaction separation by process gas treated by low-temperature methanol washing, and the carbon dioxide is treated by the low-temperature methanol washing process. Methanol and water which are relatively difficult to gasify are carried in carbon dioxide subjected to process gas-liquid separation and treated by low-temperature methanol washing, and residual liquid in the flash evaporation process needs to be treated by the low-temperature methanol washing procedure;
in step S2, the process gas treated by the low-temperature methanol washing is subjected to a low-temperature cold source for freezing and cooling to come from the flash evaporation of the liquid carbon dioxide.
In the above process steps, the shift gas is mixed with liquid methanol for preventing icing, the mixed medium is cooled by a heat exchanger E1 to liquefy the moisture therein, the cooled medium enters a gas-liquid separation tank V1 for gas-liquid separation, and the liquid medium separated by the gas-liquid separation tank V1 is sent to a methanol/water separation tower washed by low-temperature methanol for treatment; the gas separated by the gas-liquid separation tank V1 is frozen and cooled by heat exchangers E2 and E3, the cooled medium enters the gas-liquid separation tank V2 for gas-liquid separation, and the gas separated by the gas-liquid separation tank V2 is sent to a methanol washing tower for low-temperature methanol washing for treatment; the liquid separated by the gas-liquid separation tank V2 enters a reduced-pressure flash tank V3 for a flash process of reducing pressure, effective gas dissolved in liquid carbon dioxide is flashed out, and the flashed-out effective gas is sent to a circulating gas compressor of low-temperature methanol washing for treatment; the liquid medium at the bottom of the reduced-pressure flash tank V3 is subjected to flash evaporation gasification through a heat exchanger E3, the pressure of the flash evaporation process is controlled by a valve F, the flash evaporation temperature is controlled at the same time, the flash evaporation gas phase medium is sent to a hydrogen sulfide concentration tower washed by low-temperature methanol for treatment, and the residual liquid medium in the heat exchanger E3 is sent to the hydrogen sulfide concentration tower washed by the low-temperature methanol for treatment; the pressure of the flash process of the heat exchanger E3 is controlled by a valve F, and the temperature is controlled while controlling the pressure.
In the conversion gas, H2Is 40-60% by volume, and CO is present in a volume fraction of0.1-25%，CO2In a volume fraction of 20-45%, H2The volume fraction of S is 0.05-0.5%, and the volume fraction of COS is 0.0003-0.01%.
In the step (1), the transformed gas is mixed with the liquid methanol and then cooled by a heat exchanger E1 until the moisture in the transformed gas is liquefied as much as possible without carbon dioxide liquefaction.
And (3) freezing and cooling the gas separated by the gas-liquid separation tank V1 in the step (2) through heat exchangers E2 and E3 until carbon dioxide is liquefied as much as possible under the condition that the low-temperature cold quantity is met.
The conversion gas to be treated in the low-temperature methanol washing process is cooled and liquefied through the heat exchangers E2 and E3, and is liquefied through liquid carbon dioxide in the gas-liquid separation tank, so that part of carbon dioxide in the conversion gas is reduced, and the methanol consumption of new carbon dioxide required in the low-temperature methanol washing process is reduced, thereby reducing the power consumption of methanol delivery in the low-temperature methanol washing process, reducing the amount of conversion of mechanical energy of the methanol delivery in the low-temperature methanol washing process into heat energy, and reducing the demand for cold energy in the low-temperature methanol washing process.
The technical solution of the invention is as follows:
in the process of the low-temperature methanol washing process, the conversion gas to be treated by the low-temperature methanol washing is subjected to advanced freezing liquefaction to separate part of carbon dioxide, and simultaneously part of hydrogen sulfide in the conversion gas is taken out by the liquid carbon dioxide, so that the amount of methanol used for washing in the low-temperature methanol washing process is reduced. The low-temperature methanol washing purification process is a common choice for gas purification in the current coal chemical industry due to good selectivity and high purification degree of gas components. However, in the process, the methanol needs to consume a certain power and bring heat with corresponding thermal power equivalent to the system, so that the consumption of low-temperature cold energy of the system is increased. The shift gas is cooled and frozen before entering methanol washing, and part of carbon dioxide and hydrogen sulfide in the shift gas are liquefied and separated, so that the using amount of methanol in the washing process can be reduced, the energy consumption for conveying the methanol is reduced, the using amount of low-temperature cold energy in the process is reduced, and the purposes of saving energy and reducing consumption in the purification process are achieved.
Drawings
Fig. 1 is a device for energy-saving low-temperature methanol washing, wherein, E1: process heat exchanger one, E2: process heat exchanger two, E3: process heat exchanger three, V1: separation tank one, V2: separation tank two, V3: and a third separating tank, F: and (4) a valve.
Detailed Description
As shown in the apparatus structure of FIG. 1
The E1: the first process heat exchanger is used for reducing the temperature of the converted gas and separating moisture in the converted gas;
e2: the process heat exchanger II is used for supplementing the cold quantity required by the freezing in the process;
e3: the process heat exchanger III is used for flash evaporation of gasified liquid carbon dioxide and providing cold energy for cooling the process gas;
v1: the first separating tank is used for separating liquid, mainly moisture, in the process gas;
v2: the second separation tank is used for separating liquid in the process gas, mainly carbon dioxide;
v3: the third separating tank is used for decompressing and flashing liquid carbon dioxide and recovering the dissolved effective gas;
f: and the valve is used for controlling the pressure of the liquid carbon dioxide flash evaporation so as to control the temperature.
Example 1
Take the conversion gas of coal water slurry gasification producing 90 ten thousand tons of methanol per year as an example
The conversion gas (01) parameters are: 17574Kmol/H, 5.6MPa, 40 deg.C, 46% H2、0.23%N2、21.55%CO、0.1%Ar、0.08%CH4、31.56%CO2、0.24%H2S、0.00055%COS、0.24%H2O。
Mixing the shift gas (01) with 55Kmol/h liquid methanol (02) for preventing icing, precooling the mixed gas (03) by a heat exchanger E1 to cool to-12 ℃ (04) and then feeding the cooled gas into a separation tank V1 for gas-liquid separation, separating a liquid medium (06) mainly containing 49.26Kmol/h water and 50.14Kmol/h from the bottom of the separation tank V1, and sending the liquid medium to a methanol/water separation tower for low-temperature methanol washing for treatment; h with the concentration of 17527.1Kmol/H, 5.6Mpa, 40 ℃ and 8084.03Kmol/H is separated from the top of a separation tank V1240.41999Kmol/h of N2、3778.401Kmol/h CO, 17.57366Kmol/h Ar, 14.05972Kmol/h CH45544.086Kmol/h CO241.96074Kmol/H of H2S, 0.0965466Kmol/H COS, 5.736484Kmol/H CH3OH, 0.7318047Kmol/H H2O gas (05); cooling the gas (05) to-52 deg.C (08) by heat exchangers E2 and E3, separating gas and liquid in a separating tank V2, separating H of 14081.36 Kmol/H, 5.56Mpa, -52 deg.C and 8047.163Kmol/H from the top of the separating tank V2239.58613Kmol/h of N23701.666Kmol/h CO, 16.65562Kmol/h Ar, 13.43605Kmol/h CH42247.389Kmol/h CO215.4369Kmol/H of H2S, 0.0134047Kmol/H COS, 0.00422159Kmol/H CH3OH, 0.00827517Kmol/H H2The gas (09) of O is sent to a methanol washing tower of low-temperature methanol washing for treatment; h of 3445.742Kmol/H, 5.56Mpa, 52 ℃ below zero and 36.86863Kmol/H separated from the bottom of a separating tank V220.8338698Kmol/h of N276.73609Kmol/h CO, 0.9180444Kmol/h Ar, 0.6236771Kmol/h CH43296.699Kmol/h CO226.52385Kmol/H of H2S, 0.0831418Kmol/H COS, 5.732264Kmol/H CH3OH, 0.7235297Kmol/H H2The liquid medium gas (10) of O enters a separation tank V3 for decompression flash evaporation, part of effective gas (11) dissolved in the liquid carbon dioxide is flashed, and 186.8444Kmol/H, 1.3Mpa, -52 ℃ and 34.28095Kmol/H of flash evaporation are H255.68148Kmol/h CO, 94.85209Kmol/h CO2The gas (11) is sent to a circulating gas compressor of low-temperature methanol washing for treatment;
3258.896Kmol/H, 1.3Mpa, -52 ℃ and 2.587657Kmol/H of H at the bottom of a separation tank V320.2308858Kmol/h of N221.05457Kmol/h CO, 0.4753823Kmol/h Ar, 0.2908161Kmol/h CH43201.845Kmol/h CO225.874Kmol/H of H2S, 0.0826114Kmol/H COS, 5.732133Kmol/H CH3OH, 0.7232327Kmol/H H2The liquid medium of O enters a heat exchanger E3 for flash evaporation, the pressure of flash evaporation gas (13) is controlled by a valve F, meanwhile, the temperature of the gas (13) is controlled, and the gas (14) is sent to a hydrogen sulfide concentration tower of low-temperature methanol washing for treatment after passing through the valve F; heat exchangeThe residual liquid medium (15) in the device E3 is sent to a low-temperature methanol-washed hydrogen sulfide concentration tower for treatment; the pressure of the valve F gas (13) is 0.5Mpa, the temperature of the flash-evaporated gas is-56.31 ℃, and the gas (14): 3077.604Kmol/H, 0.5MPa, -56.31 deg.C, 2.587461Kmol/H H20.2307794Kmol/h of N221.04548Kmol/h CO, 0.4747267Kmol/h Ar, 0.2904988Kmol/h CH43028.694Kmol/h CO224.09811Kmol/H of H2S, 0.0643607Kmol/H COS, 0.0379618Kmol/H CH3OH, 0.0815292Kmol/H H2Sending the O to a hydrogen sulfide concentration tower washed by low-temperature methanol for treatment; residual liquid (15): 181.2956Kmol/h, 0.5Mpa, -56.31 deg.C, 173.1557Kmol/h CO21.775317Kmol/H of H2S, 0.0182507Kmol/H COS, 5.694179Kmol/H CH3OH, 0.6417044Kmol/H H2And sending the O to a low-temperature methanol-washed hydrogen sulfide concentration tower for treatment. The heat exchanger E3 flashes liquid carbon dioxide to provide cold for freezing and cooling the process gas.
After the carbon dioxide is separated by freezing, cooling, liquefying and reducing the carbon dioxide in the process gas by 3201.849Kmol/h and 57.731 percent and the hydrogen sulfide by 25.87342Kmol/h and 61.5234 percent, the process gas is sent to low-temperature methanol washing for purification treatment, and the amount of methanol required for washing the carbon dioxide and the hydrogen sulfide is correspondingly reduced, so that the power consumption of methanol conveying in the low-temperature methanol washing process is reduced, the amount of conversion of mechanical energy of the methanol conveying in the low-temperature methanol washing process to thermal energy is reduced, and the demand of cold energy in the low-temperature methanol washing process is reduced.
Example 2
Taking the conversion gas of coal water slurry gasification for annual 50 ten thousand tons of synthetic ammonia as an example
The conversion gas (01) parameters are: 10634.35Kmol/H, 5.6MPa, 40 deg.C, 5901Kmol/H H212.21Kmol/h of N242.65Kmol/h CO, 5.31Kmol/h Ar, 4.25Kmol/h CH44631.8Kmol/h CO212.74Kmol/H of H2S, 0.02922Kmol/H COS, 24.36Kmol/H H2O。
The shift gas (01) is mixed with 33Kmol/h liquid methanol (02) for preventing icing, and the mixed gas (03) is pre-cooled and cooled by a heat exchanger E1The (04) with the temperature of-12 ℃ enters a separation tank V1 for gas-liquid separation, a liquid medium (06) mainly containing 23.92Kmol/h water and 29.35Kmol/h is separated from the bottom of the separation tank V1 and is sent to a methanol/water separation tower washed by low-temperature methanol for treatment; h with the concentration of 10611.3Kmol/H, 5.6Mpa, 40 ℃ and 5900.962Kmol/H is separated from the top of a separation tank V1212.20984Kmol/h of N242.64965Kmol/h CO, 5.309825Kmol/h Ar, 4.249865Kmol/h CH44629.138Kmol/h CO212.6611Kmol/H of H2S, 0.0291709Kmol/H COS, 3.648714Kmol/H CH3OH, 0.4429028Kmol/H H2O gas (05); cooling the gas (05) to-52 deg.C (08) by heat exchangers E2 and E3, separating gas and liquid in a separating tank V2, separating H of 6928.873Kmol/H, 5.56Mpa, -52 deg.C and 5847.997Kmol/H from the top of the separating tank V2211.6915Kmol/h of N240.86792Kmol/h CO, 4.744049Kmol/h Ar, 3.86459Kmol/h CH41017.247Kmol/h CO22.456736Kmol/H of H2S, 0.00172575Kmol/H COS, 0.0008736Kmol/H CH3OH, 0.0018247Kmol/H H2The gas (09) of O is sent to a methanol washing tower of low-temperature methanol washing for treatment;
h of 3682.437Kmol/H, 5.56Mpa, 52 ℃ and 52.97Kmol/H separated from the bottom of a separating tank V220.5183527Kmol/h of N21.781763Kmol/h CO, 0.5657809Kmol/h Ar, 0.385279Kmol/h CH43611.895Kmol/h CO210.20437Kmol/H of H2S, 0.0274451Kmol/H COS, 3.647843Kmol/H CH3OH, 0.4410785Kmol/H H2The liquid medium gas (10) of O enters a separation tank V3 for decompression flash evaporation, part of effective gas (11) dissolved in the liquid carbon dioxide is flashed, and 92.30528Kmol/H, 1.3Mpa, -52.9 ℃ and 45.66579Kmol/H of flash evaporation are added20.9771716Kmol/h CO, 44.96976Kmol/h CO2The gas (11) is sent to a circulating gas compressor of low-temperature methanol washing for treatment; 3590.135Kmol/H, 1.3Mpa, -52.9 ℃ and 7.304248Kmol/H of H at the bottom of a separation tank V320.235834Kmol/h of N20.8045929Kmol/h CO, 0.3972259Kmol/h Ar, 0.2533787Kmol/h CH43566.928Kmol/h CO2、10.09497Kmol/H of H2S, 0.0273714Kmol/H COS, 3.647815Kmol/H CH3OH, 0.4410061Kmol/H H2The liquid medium of O enters a heat exchanger E3 for flash evaporation, the pressure of flash evaporation gas (13) is controlled by a valve F, meanwhile, the temperature of the gas (13) is controlled, and the gas (14) is sent to a hydrogen sulfide concentration tower of low-temperature methanol washing for treatment after passing through the valve F; the residual liquid medium (15) of the heat exchanger E3 is sent to a low-temperature methanol-washed hydrogen sulfide concentration tower for treatment; valve F gas (13) pressure at 0.5MPa, flash evaporation gas temperature of-56.46 ℃, gas (14): 3408.963Kmol/H, 0.5MPa, -56.46 ℃, 7.303698Kmol/H of H20.235732Kmol/h of N20.8042609Kmol/h CO, 0.3967214Kmol/h Ar, 0.2531206Kmol/h CH43390.365Kmol/h CO29.490459Kmol/H of H2S, 0.02182Kmol/H COS, 0.0294123Kmol/H CH3OH, 0.0623625Kmol/H H2Sending the O to a hydrogen sulfide concentration tower washed by low-temperature methanol for treatment; residual liquid (15): 181.1673Kmol/h, 0.5Mpa, -56.46 ℃, 176.5585Kmol/h of CO20.6044986Kmol/H of H2S, 0.00555134Kmol/H COS, 3.618398Kmol/H CH3OH, 0.378643Kmol/H H2And sending the O to a low-temperature methanol-washed hydrogen sulfide concentration tower for treatment. The heat exchanger E3 flashes liquid carbon dioxide to provide cold for freezing and cooling the process gas.
After the carbon dioxide is separated by freezing, cooling, liquefying and reducing the carbon dioxide in the process gas by 3611.895Kmol/h and 77.98 percent and the hydrogen sulfide by 10.20437Kmol/h and 80.097 percent, the process gas is sent to low-temperature methanol washing for purification treatment, and the amount of methanol required for washing the carbon dioxide and the hydrogen sulfide is correspondingly reduced, so that the power consumption of methanol conveying in the low-temperature methanol washing process is reduced, the amount of conversion of mechanical energy of the methanol conveying in the low-temperature methanol washing process to thermal energy is reduced, and the demand of cold energy in the low-temperature methanol washing process is reduced.
Example 3
Taking the conversion gas of gasification of pulverized coal producing 90 ten thousand tons of methanol per year as an example
The conversion gas (01) parameters are: 17574.41Kmol/H, 3.35MPa, 40 deg.C, 8084.96Kmol/H H226.36Kmol/h of N2、3787.63Kmol/h CO, 15.3Kmol/h Ar, 5577.34Kmol/h CO242.18Kmol/H of H2S, COS at 0.22Kmol/H, H at 40.42Kmol/H2O。
Mixing the shift gas (01) with 55Kmol/h liquid methanol (02) for preventing icing, precooling the mixed gas (03) by a heat exchanger E1 to cool to-15 ℃ (04) and then feeding the cooled gas into a separation tank V1 for gas-liquid separation, separating a liquid medium (06) mainly containing 39.7155Kmol/h water and 49.04444Kmol/h from the bottom of the separation tank V1, and sending the liquid medium to a methanol/water separation tower for low-temperature methanol washing for treatment; 17538.4Kmol/H, 3.35Mpa, 15 ℃ and 8084.949Kmol/H of H are separated from the top of a separation tank V1226.35987Kmol/h of N23787.621Kmol/h CO, 15.29977Kmol/h Ar, 5575.298Kmol/h CO241.99794Kmol/H of H2S, 0.2197549Kmol/H COS, 5.955527Kmol/H CH3OH, 0.70448Kmol/H H2O gas (05); cooling the gas (05) to-52 deg.C (08) by heat exchangers E2 and E3, separating gas and liquid in a separating tank V2, separating H of 15471.4Kmol/H, 3.31Mpa, -52 deg.C and 8073.312Kmol/H from the top of the separating tank V2226.17587Kmol/h of N23761.604Kmol/h CO, 15.06169Kmol/h Ar, 3569.911Kmol/h CO225.24853Kmol/H of H2S, 0.0627692Kmol/H COS, 0.00918828Kmol/H CH3OH, 0.0180223Kmol/H H2The gas (09) of O is sent to a methanol washing tower of low-temperature methanol washing for treatment; h of 2066.997Kmol/H, 3.31Mpa, 52 ℃ below zero and 11.63414Kmol/H separated from the bottom of a separating tank V220.1839917Kmol/h of N226.0161Kmol/h CO, 0.2380728Kmol/h Ar, 2005.386Kmol/h CO216.7494Kmol/H of H2S, 0.1569856Kmol/H COS, 5.946337Kmol/H CH3OH, 0.6864574Kmol/H H2The liquid medium gas (10) of O enters a separation tank V3 for decompression flash evaporation, part of effective gas (11) dissolved in the liquid carbon dioxide is flashed, and 66.82792Kmol/H, 1.0Mpa, -54.78 ℃ and 10.63494Kmol/H of H are flashed217.41256Kmol/h CO, 38.27465Kmol/h CO2The gas (11) is sent to a circulating gas compressor of low-temperature methanol washing for treatment; 2000.172Kmol/H, 1.0Mpa, -54.78 deg.C, 0.9992099Kmol/H H at the bottom of the separation tank V320.0613475Kmol/h of N28.603571Kmol/h CO, 0.1283712Kmol/h Ar, 1967.114Kmol/h CO216.47688Kmol/H of H2S, 0.1563439Kmol/H COS, 5.946276Kmol/H CH3OH, 0.6863Kmol/H H2The liquid medium of O enters a heat exchanger E3 for flash evaporation, the pressure of flash evaporation gas (13) is controlled by a valve F, meanwhile, the temperature of the gas (13) is controlled, and the gas (14) is sent to a hydrogen sulfide concentration tower of low-temperature methanol washing for treatment after passing through the valve F; the residual liquid medium (15) of the heat exchanger E3 is sent to a low-temperature methanol-washed hydrogen sulfide concentration tower for treatment; the pressure of the valve F gas (13) is 0.5Mpa, the temperature of the flash-evaporated gas is-56.11 ℃, and the gas (14): 1903.78Kmol/H, 0.5MPa, -56.11 deg.C, 1.032482Kmol/H H20.0633551Kmol/h of N28.88557Kmol/h CO, 0.1324531Kmol/h Ar, 1878.107Kmol/h CO215.36325Kmol/H of H2S, 0.1146209Kmol/H COS, 0.027342Kmol/H CH3OH, 0.0538375Kmol/H H2Sending the O to a hydrogen sulfide concentration tower washed by low-temperature methanol for treatment; residual liquid (15): 163.2196Kmol/h, 0.5Mpa, -56.11 deg.C, 154.7297Kmol/h CO21.664141Kmol/H of H2S, 0.0469465Kmol/H COS, 6.117605Kmol/H CH3OH, 0.6553925Kmol/H H2And sending the O to a low-temperature methanol-washed hydrogen sulfide concentration tower for treatment. The heat exchanger E3 flashes liquid carbon dioxide to provide cold for freezing and cooling the process gas.
After the carbon dioxide is separated by freezing, cooling, liquefying and reducing the carbon dioxide in the process gas by 2005.386Kmol/h and the proportion of carbon dioxide is 35.96 percent, and the hydrogen sulfide is 16.7494Kmol/h and the proportion of hydrogen sulfide is 39.71 percent, the carbon dioxide is sent to the low-temperature methanol washing to be purified, and the amount of the methanol required for washing the carbon dioxide and the hydrogen sulfide is correspondingly reduced, so that the power consumption of methanol conveying in the low-temperature methanol washing process is reduced, the amount of the mechanical energy transferred by the methanol in the low-temperature methanol washing process is reduced, and the cold quantity required in the low-temperature methanol washing process is reduced.
Example 4
Taking the conversion gas of pulverized coal gasification for annual production of 50 ten thousand tons of synthetic ammonia as an example
The conversion gas (01) parameters are: 11088.812KH at mol/H, 3.35MPa, 40 ℃ and 5897Kmol/H2445Kmol/h of N245Kmol/h CO, 18Kmol/h Ar, 4631Kmol/h CO226Kmol/H of H2S, COS at 0.062Kmol/H, H at 26.75Kmol/H2O。
Mixing the shift gas (01) with 36Kmol/h liquid methanol (02) for preventing icing, precooling the mixed gas (03) by a heat exchanger E1 to cool to-15 ℃ (04) and then feeding the cooled gas into a separation tank V1 for gas-liquid separation, separating a liquid medium (06) mainly containing 26.29255Kmol/h water and 32.23412Kmol/h from the bottom of the separation tank V1, and sending the liquid medium to a methanol/water separation tower for low-temperature methanol washing for treatment; 11064.34Kmol/H, 3.35Mpa, 15 ℃ and 5896.995Kmol/H of H are separated from the top of a separation tank V12444.9979Kmol/h of N244.99991Kmol/h CO, 17.99972Kmol/h Ar, 4629.181Kmol/h CO225.88059Kmol/H of H2S, 0.0619255Kmol/H COS, 3.765877Kmol/H CH3OH, 0.4574539Kmol/H H2O gas (05);
cooling the gas (05) to-52 deg.C (08) by heat exchangers E2 and E3, separating gas and liquid in a separating tank V2, separating H of 8221.76Kmol/H, 3.31Mpa, -52 deg.C and 5875.834Kmol/H from the top of the separating tank V22437.1439Kmol/h of N244.21641Kmol/h CO, 17.29481Kmol/h Ar, 1837.974Kmol/h CO29.282587Kmol/H of H2S, 0.00781274Kmol/H COS, 0.00197217Kmol/H CH3OH, 0.00422823Kmol/H H2The gas (09) of O is sent to a methanol washing tower of low-temperature methanol washing for treatment; h of 2842.54Kmol/H, 3.31Mpa, 52 ℃ below zero and 21.13982Kmol/H separated from the bottom of a separating tank V227.852396Kmol/h of N20.7833385Kmol/h CO, 0.7048441Kmol/h Ar, 2791.191Kmol/h CO216.59791Kmol/H of H2S, 0.0541125Kmol/H COS, 3.763891Kmol/H CH3OH, 0.453224Kmol/H H2The liquid medium gas (10) of O enters a separation tank V3 for decompression flash evaporation, part of effective gas (11) dissolved in the liquid carbon dioxide is flashed, and the flash evaporated H with the concentration of 59.18065Kmol/H, 1.0Mpa, -53.62 ℃ and 18.39658Kmol/H20.4408285Kmol/h CO, 35.51561Kmol/h CO2The gas (11) is sent to low temperature methanol washingThe circulating gas compressor is used for processing; 2783.359Kmol/H, 1.0Mpa, -53.62 ℃ and 2.743241Kmol/H of H at the bottom of a separation tank V323.455358Kmol/h of N20.3425098Kmol/h CO, 0.4552838Kmol/h Ar, 2755.675Kmol/h CO216.41712Kmol/H of H2S, 0.05396534Kmol/H COS, 3.76386Kmol/H CH3OH, 0.4531506Kmol/H H2The liquid medium of O enters a heat exchanger E3 for flash evaporation, the pressure of flash evaporation gas (13) is controlled by a valve F, meanwhile, the temperature of the gas (13) is controlled, and the gas (14) is sent to a hydrogen sulfide concentration tower of low-temperature methanol washing for treatment after passing through the valve F; the residual liquid medium (15) of the heat exchanger E3 is sent to a low-temperature methanol-washed hydrogen sulfide concentration tower for treatment; valve F gas (13) pressure 0.5Mpa, flash post gas temperature-56.39 ℃, gas (14): 2616.821Kmol/H, 0.5MPa, -56.39 deg.C, 2.743002Kmol/H H23.453589Kmol/h of N20.342343Kmol/h CO, 0.4547326Kmol/h Ar, 2594.469Kmol/h CO215.23921Kmol/H of H2S, 0.0413354Kmol/H COS, 0.0248038Kmol/H CH3OH, 0.0529968Kmol/H H2Sending the O to a hydrogen sulfide concentration tower washed by low-temperature methanol for treatment; residual liquid (15): 166.5387Kmol/h, 0.5Mpa, -56.39 deg.C, 161.2062Kmol/h CO21.17791Kmol/H of H2S, 0.0126298Kmol/H COS, 3.739057Kmol/H CH3OH, 0.4001538Kmol/H H2And sending the O to a low-temperature methanol-washed hydrogen sulfide concentration tower for treatment. The heat exchanger E3 flashes liquid carbon dioxide to provide cold for freezing and cooling the process gas. After the carbon dioxide is separated by freezing, cooling, liquefying and reducing the carbon dioxide in the process gas by 2791.191Kmol/h and 60.27 percent and the hydrogen sulfide by 16.59791Kmol/h and 63.84 percent, and sending the process gas to low-temperature methanol washing for purification treatment correspondingly reduces the amount of methanol required for washing the carbon dioxide and the hydrogen sulfide, thereby reducing the power consumption of methanol delivery in the low-temperature methanol washing process, reducing the amount of conversion of mechanical energy of the methanol delivery in the low-temperature methanol washing process into thermal energy and reducing the amount of cold required in the low-temperature methanol washing process.
Claims (7)
1. The process of the energy-saving low-temperature methanol washing device is characterized by comprising the following steps of:
(1) after being mixed with liquid methanol, the shift gas is cooled and liquefied by a first pass heat exchanger (E1), and then enters a first separating tank (V1) for gas-liquid separation, and the liquid separated by the first separating tank (V1) is sent to a methanol/water separation tower washed by low-temperature methanol for treatment;
(2) the gas separated by the first separating tank (V1) is frozen and cooled to-50 to-60 ℃ through a second process heat exchanger (E2) and a third process heat exchanger (E3), the cooled medium enters a second separating tank (V2) for gas-liquid separation, and the gas separated by the second separating tank (V2) is sent to a methanol washing tower for low-temperature methanol washing for treatment;
(3) the liquid separated in the second separating tank (V2) enters a third separating tank (V3), the effective gas dissolved in the liquid carbon dioxide is flashed out, and the effective gas is sent to a circulating gas compressor of the low-temperature methanol washing for treatment;
(4) and liquid medium at the bottom of the third separating tank (V3) is subjected to flash evaporation gasification through a third process heat exchanger (E3), the flash-evaporated gas phase medium is sent to a hydrogen sulfide concentration tower washed by low-temperature methanol for treatment, and the residual liquid medium in the third process heat exchanger (E3) is sent to another hydrogen sulfide concentration tower washed by low-temperature methanol for treatment.
2. The process of claim 1, wherein the shift gas is H2The volume fraction of (A) is 40-60%, the volume fraction of CO is 0.1-25%, and CO2In a volume fraction of 20-45%, H2The volume fraction of S is 0.05-0.5%, and the volume fraction of COS is 0.0003-0.01%.
3. The process carried out by the energy-saving low-temperature methanol washing device according to claim 1, wherein the temperature of the mixed gas in the step (1) is reduced to-10 to-15 ℃ through a first process heat exchanger (E1).
4. The process carried out by the energy-saving cryogenic methanol washing plant of claim 1, wherein the methanol liquid line and the shift gas line are connected to process heat exchanger one (E1), process heat exchanger one (E1) is connected to knockout drum one (V1), knockout drum one (V1) is connected to process heat exchanger two (E2), process heat exchanger two (E2) is connected to process heat exchanger three (E3), process heat exchanger three (E3) is connected to knockout drum two (V2), knockout drum two (V2) is connected to the process gas wash column.
5. The process carried out by the energy-saving low-temperature methanol washing device according to claim 1, wherein a second separation tank (V2) is connected with a third separation tank (V3), the bottom of the third separation tank (V3) is connected with a third process heat exchanger (E3) through a pipeline, and the top of the third separation tank (V3) is connected with a circulating gas compressor through a pipeline.
6. The process of the energy-saving low-temperature methanol washing device according to claim 1, wherein a process heat exchanger III (E3) is respectively connected with pipelines to different hydrogen sulfide concentration towers.
7. The process of the energy-saving low-temperature methanol washing device as claimed in claim 1, wherein the bottom of the first separation tank (V1) is connected to a methanol/water separation tower through a pipeline.
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