CN115636393A - Low-quality gas conversion system and method - Google Patents
Low-quality gas conversion system and method Download PDFInfo
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- CN115636393A CN115636393A CN202211214832.4A CN202211214832A CN115636393A CN 115636393 A CN115636393 A CN 115636393A CN 202211214832 A CN202211214832 A CN 202211214832A CN 115636393 A CN115636393 A CN 115636393A
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Abstract
The invention discloses a low-quality gas conversion system and a low-quality gas conversion method, wherein the conversion system comprises a pretreatment unit, a conversion unit, a carbon dioxide liquefaction unit and a PSA hydrogen production unit; the invention fully recycles each component in the low-quality gas aiming at the characteristic that each effective component and each ineffective component in the low-quality gas account for nearly half, thereby realizing the technical route of high-efficiency and energy-saving low-quality gas utilization.
Description
Technical Field
The invention relates to the technical field of low-quality gas utilization, in particular to a conversion system and method of low-quality gas.
Background
In coal chemical industry, such as coal gasification and coal coking, coal gas is generally processed by a conventional process route, i.e. a technical route of firstly preprocessing and then transforming, and then starting desulfurization, decarburization and hydrogen extraction. The conversion adopts a combination mode of high temperature, medium temperature and low temperature, each stage of conversion needs to be provided with a series of water spraying and cooling equipment, so that the operation enables invalid components in the coal gas, particularly in low-quality coal gas, to go all the way through the process, the volume content of the effective components (hydrogen and CO) in the low-quality coal gas is low, for example, the content is lower than 60vol%, for example, the volumes of the effective components and the invalid components are nearly half, the equipment capacity in the process is enabled, the energy consumption is increased by times, and zero-row treatment is not carried out on the components such as carbon dioxide, nitrogen and the like.
Disclosure of Invention
The invention provides a conversion system and a conversion method of low-quality coal gas for making up the defects of the prior art, aiming at the characteristic that the effective components and the ineffective components in the low-quality coal gas respectively account for nearly half, all the components in the low-quality coal gas are fully recycled, so that a technical route for utilizing the low-quality coal gas with high efficiency and energy saving is realized.
In order to achieve one aspect of the above object, the invention adopts the following technical scheme:
a low-quality gas conversion system, comprising:
the pretreatment unit is used for removing ineffective components in the raw material low-quality gas to obtain clean gas;
the pretreatment unit comprises a TSA impurity removal unit, a PSA nitrogen removal unit and an acid gas removal unit which are sequentially connected, wherein the TSA impurity removal unit is used for carrying out temperature swing adsorption treatment on raw material low-quality coal gas to remove impurities in the raw material low-quality coal gas and obtain first purified gas; the PSA denitrification unit is used for carrying out pressure swing adsorption treatment on the first purified gas to remove nitrogen in the raw low-quality gas to obtain a second purified gas; the acid gas removal unit is used for absorbing and removing carbon dioxide and hydrogen sulfide gas in the second purified gas to obtain purified gas;
the conversion unit is used for performing conversion treatment on the clean gas to obtain a mixed gas flow of hydrogen and carbon dioxide;
the shift unit comprises a first adjusting unit, a shift reactor and a water vapor removing unit, wherein the first adjusting unit is used for adjusting the temperature and/or pressure of the clean coal gas so as to facilitate shift treatment; the shift reactor is used for shifting carbon monoxide in the clean gas from the first adjusting unit to obtain shift gas; the water vapor removal unit is used for removing water in the conversion gas to obtain a hydrogen and carbon dioxide mixed gas flow;
a carbon dioxide liquefaction unit for preparing a liquid carbon dioxide product from the mixed gas stream of hydrogen and carbon dioxide;
the carbon dioxide liquefaction unit comprises a liquefier and a rectifying tower with a reboiler, wherein the liquefier is used for cooling part of the mixed gas flow of hydrogen and carbon dioxide from the water vapor removal unit and subjected to heat exchange and temperature reduction by the reboiler and the rest of the mixed gas flow of hydrogen and carbon dioxide from the water vapor removal unit so as to liquefy the carbon dioxide in the mixed gas flow of hydrogen and carbon dioxide and obtain a separation raw material to be rectified; the rectifying tower is used for rectifying and separating the raw materials to be rectified and separated from the liquefier so as to obtain a crude hydrogen product stream at the tower top and a liquid carbon dioxide product at the tower bottom;
a PSA hydrogen production unit for performing pressure swing adsorption separation on impurities in the crude hydrogen product stream from the carbon dioxide liquefaction unit to obtain a hydrogen product;
the PSA hydrogen production unit comprises a second regulating unit, a hydrogen production pressure swing adsorption unit and an optional hydrogen compressor; wherein the second conditioning unit is used to condition the temperature and/or pressure of the crude hydrogen product stream from the carbon dioxide liquefaction unit for subsequent pressure swing adsorption processing; the hydrogen production pressure swing adsorption unit is used for carrying out pressure swing adsorption separation on impurities in the crude hydrogen product flow from the second regulating unit to obtain a hydrogen product; the hydrogen compressor is used for pressurizing the hydrogen product from the hydrogen production pressure swing adsorption unit.
In the present invention, low-quality gas refers to gas in which the content of active ingredient (hydrogen + CO) is low, such as less than 60vol%, for example 40-60vol%, for example, the volume of active ingredient and inactive ingredient is nearly half, such as 45vol%, 50vol% or 55vol%; in one embodiment, the low-grade gas contains H 2 The content is 22.5-28 vol%, and the content of CO is 15-24 vol%.
According to the conversion system of the present invention, in one embodiment, the pretreatment unit further comprises a gas holder and a low-quality gas compressor for pressurizing the raw low-quality gas from the gas holder and sending the pressurized raw low-quality gas to the TSA impurity removal unit.
According to the conversion system of the present invention, in one embodiment, the TSA impurity removal unit comprises a first regeneration gas inlet pipe, a second regeneration gas inlet pipe, a temperature swing adsorption unit, a first desorption gas exhaust pipe, and a second desorption gas exhaust pipe; the first regeneration gas inlet pipe and the second regeneration gas inlet pipe are arranged in parallel, a heater is arranged on the first regeneration gas inlet pipe and used for heating the desorption gas from the hydrogen-production pressure-swing adsorption unit and then sending the desorption gas to the temperature-swing adsorption unit as a first regeneration gas, and the second regeneration gas inlet pipe is used for sending the desorption gas from the hydrogen-production pressure-swing adsorption unit to the temperature-swing adsorption unit as a second regeneration gas; the temperature swing adsorption unit is used for carrying out temperature swing adsorption treatment on the raw material low-quality coal gas to remove impurities in the raw material low-quality coal gas to obtain first purified gas, and the first purified gas is regenerated by using the desorption gas from the hydrogen-production pressure swing adsorption unit after adsorption saturation; the first desorption gas exhaust pipe and the second desorption gas exhaust pipe are arranged in parallel, the first desorption gas exhaust pipe is used for sending out a first regeneration desorption gas discharged by the temperature swing adsorption unit through the first regeneration gas regeneration as a fuel after the first regeneration desorption gas exchanges heat and is cooled through the second adjusting unit, and the second desorption gas exhaust pipe is used for sending out a second regeneration desorption gas discharged by the temperature swing adsorption unit through the second regeneration gas regeneration as a fuel;
preferably, the second conditioning unit comprises a second heat exchanger for cooling the first regenerated cracked gas by heat exchange with the crude hydrogen from the rectifying tower, which is heated by heat exchange with the liquefier.
According to the conversion system of the present invention, in one embodiment, the acid gas removal unit comprises an absorption tower, a regeneration tower, a desulfurization unit, and a carbon dioxide conveyor; the absorption tower is used for removing carbon dioxide in the first purified gas by using an N-methyl glycol amine solution as an absorbent to obtain carbon dioxide-removed coal gas; the regeneration tower is used for stripping the absorbent from the absorption tower through a stripping method to separate out carbon dioxide and sending the regenerated absorbent back to the absorption tower; the desulfurization device is used for removing hydrogen sulfide in the decarbonized gas from the absorption tower to obtain clean gas; the carbon dioxide conveyor is used for conveying the carbon dioxide from the regeneration tower to the water vapor removal unit to recover the carbon dioxide.
In the present invention, desulfurization apparatuses for removing hydrogen sulfide are well known in the art, such as desulfurization apparatuses for removing hydrogen sulfide from a gas by a physical absorption method or a chemical absorption method, for example, a chemical absorption method using sodium carbonate or potassium hydroxide as a desulfurization absorbing liquid. In one embodiment, the desulfurization unit is a supergravity desulfurization unit that utilizes supergravity technology for hydrogen sulfide removal.
According to the conversion system of the invention, in one embodiment, the water vapor removal unit comprises a waste pot, a water cooler, a liquid separation tank and an adsorption drying tank; wherein the spent pot is used to recover heat from the shift gas of the shift reactor; the water cooler is used for further cooling the shift gas from the waste boiler; the liquid separation tank is used for carrying out gas-liquid separation on the materials from the water cooler and the carbon dioxide conveyor; the adsorption drying tank is used for carrying out adsorption drying and water removal on the gas-phase material from the liquid separation tank to obtain a hydrogen and carbon dioxide mixed gas flow;
preferably, the carbon dioxide conveyor is an ejector, and the ejector is used for facilitating partial conversion gas from the water cooler to be used as ejection flow for feeding the carbon dioxide from the regeneration tower into the liquid separation tank.
According to the conversion system of the invention, in one embodiment, the first conditioning unit comprises a clean gas compressor and a first heat exchanger; wherein the purified gas compressor is used for pressurizing the purified gas; the first heat exchanger is used for exchanging heat and heating the pressurized clean coal gas and the converted gas leaving the conversion reactor, and sending the converted gas after exchanging heat and cooling to the water vapor removing unit.
According to the conversion system of the invention, in one embodiment, a deoxidation reaction catalyst bed layer, a first shift reaction catalyst bed layer and a second shift reaction catalyst bed layer are arranged in the shift reactor at intervals from top to bottom; the deoxidation reaction catalyst bed layer is provided with a clean gas inlet and a hydrogen inlet which are used for eliminating oxygen in the clean gas in a reaction way; the first shift reaction catalyst bed layer is provided with a steam inlet for shift reaction so as to reduce the content of carbon monoxide in reaction gas from the deoxidation reaction catalyst bed layer; the second shift reaction catalyst bed is used for catalyzing shift reaction to further reduce the content of carbon monoxide in the reaction gas from the second shift reaction catalyst bed;
a first heat remover is arranged between the deoxidation reaction catalyst bed layer and the first shift reaction catalyst bed layer and is used for exchanging heat between the reaction gas from the deoxidation reaction catalyst bed layer and the clean gas from the first adjusting unit so as to remove part of heat;
the first shift reaction catalyst bed layer is internally provided with a second heat remover which is used for heating the clean gas from the first heat remover so as to remove the heat in the first shift reaction catalyst bed layer and sending the heated clean gas to the clean gas inlet;
preferably, the hydrogen gas fed through the hydrogen inlet comes from the hydrogen compressor.
In order to achieve another aspect of the above object, the present invention also provides a method for low-quality gas conversion by using the above conversion system.
In one embodiment of the present invention, one or more of the adsorbents CNA-421 type, CNA-316 type and CNA-213 type used in the temperature swing adsorption process using the TSA desaturation unit are common adsorbents known in the art, such as CNA-421 type, CNA-316 type and CNA-213 type, which are packed in series along the gas flow direction; in one embodiment, the three adsorbents are used in volume amounts that differ by no more than 10%, such as in an equal volume pack.
In one embodiment of the invention, the adsorbent used for the PSA denitrification unit to perform the pressure swing adsorption treatment is a 5A molecular sieve and a HX-CO adsorbent which are sequentially stacked along the gas flow direction; in one embodiment, the two volume dosages do not differ by more than 10%, such as equal volumes.
In one embodiment of the invention, the adsorbent/filler used for the PSA hydrogen production unit to perform the pressure swing adsorption treatment is AS adsorbent, HXBC-15B, HX5A-98H, HXNA-CO adsorbent and inert ceramic balls which are sequentially stacked along the gas flow direction; in one embodiment, the volume dosages of the five materials differ by no more than 10%, such as equal volume packing.
In one embodiment of the present invention, the catalyst used in the deoxidation reaction catalyst bed layer is a deoxidation catalyst, such as a HT type palladium catalyst deoxidation catalyst, which uses hydrogen to remove oxygen in the clean gas to obtain deoxygenated gas, such deoxygenation catalyst is well known in the art, and below the deoxidation catalyst bed layer, a horizontally arranged tubular heat exchanger, i.e. a first heat remover, is arranged to exchange heat between the clean gas and the deoxygenated gas, the temperature at the lower end of the first heat remover is maintained at 210 to 220 ℃, and the CO concentration in the deoxygenated gas reaches 33% to 39%.
In one embodiment of the invention, the first shift catalyst bed employs a copper-based shift catalyst to convert CO and water to hydrogen and carbon dioxide by a shift reaction, such shift catalysts being well known in the art, such as CNB-1 type copper-based shift catalysts having a catalyst composition: copper oxide is more than or equal to 38 percent, and zinc oxide is more than or equal to 40 percent; 6-8% alumina, such as 38-52%/40-54%/6-8% copper oxide/zinc oxide/alumina, e.g., a CNB-1 type copper-based shift catalyst available from the southwest institute of chemical industry; controlling the temperature of the reaction gas leaving the first shift reaction catalyst bed to be 200-210 ℃ and the CO concentration to be lower than 3% (in the invention, the gas content is volume content if not specifically stated);
in one embodiment of the invention, the second shift reaction catalyst bed employs a catalyst of type B207; the temperature of the reaction gas leaving the second shift reaction catalyst bed layer is controlled to be 230-250 ℃, and the CO concentration is lower than 0.12%.
In the present invention, unless otherwise specified, the concentration refers to mass concentration, and the percentage is mass percentage.
Compared with the prior art, the invention has the following advantages:
the technology aims at the characteristic that the low-quality coal gas is low in effective components and low in ineffective components, naphthalene, dust and oil substances are removed before conversion, nitrogen, sulfide and carbon dioxide in the low-quality coal gas are removed firstly and can be respectively prepared into industrial nitrogen, sulfur and liquid carbon dioxide, and the low-quality coal gas is concentrated into high-quality coal gas, so that the capacity and the energy consumption of subsequent equipment are reduced by half.
In addition, the shift technology completes deoxidation, one shift and two shifts in a shift reactor, and well realizes the heat exchange process of two-stage reaction heat and high-quality coal gas. The two-stage transformation adopts a low-temperature transformation technology, and the low steam ratio transformation technology is applied to the second transformation. And finally, separating hydrogen while obtaining a liquid carbon dioxide product by adopting a low-temperature method, and performing pressure swing adsorption to obtain a final hydrogen product.
The invention fully recycles each component in the low-quality coal gas, changes waste into valuable, realizes zero emission and achieves the technical route of high-efficiency and energy-saving low-quality coal gas hydrogen production.
Specifically, aiming at the characteristic that the low-quality coal gas is low in effective components and half of ineffective components, for example, the content of carbon monoxide is 19%, naphthalene, dust and oil in the low-quality coal gas are removed, nitrogen and acid gas (carbon dioxide and hydrogen sulfide gas) are removed, so that the content of carbon monoxide is concentrated to 36-38%, the scale of subsequent equipment is reduced by nearly 50%, and the subsequent energy consumption is reduced by half. The conversion technology adopts a high-efficiency conversion reactor, the pure gas is subjected to deoxidization, primary conversion and secondary conversion sequentially from top to bottom, and the exchange of the pure gas, the deoxidization and the primary conversion reaction heat is realized inside the reactor. The two-stage conversion adopts a low-temperature conversion technology, steam is added at one time, the two-stage conversion adopts a low-temperature low-steam-ratio technology, CO at the CO conversion outlet is 0.12%, the conversion rate is improved by 99.88%, and compared with the traditional conversion technology, the conversion rate is improved, and zero emission of the conversion technology is achieved. In the aspect of energy consumption, the water-carbon ratio is optimized to be 2.75 and the outlet gas-steam ratio is 0.3 from 3.5 and the outlet gas-steam ratio of 1.0-1.1 of the common conversion technology; the steam can be saved by 20-24%, and the annual energy saving is considerable. The converted carbon dioxide and the crude hydrogen are separated from the low temperature by utilizing a carbon dioxide liquefaction technology, industrial nitrogen, sulfur and liquid carbon dioxide are respectively obtained in the technical process, and zero emission is realized in the whole process. The recovery rate of the product hydrogen is above 98.3%, and the purity is above 99.9%.
Drawings
FIG. 1 is a schematic flow diagram of one embodiment of the conversion system of the present invention.
Detailed Description
The present invention will be further described with reference to the following examples and the accompanying drawings, but the present invention is not limited to the examples listed, and shall include equivalent modifications and variations of the technical solutions defined in the claims appended to the present application.
As shown in figure 1, the low-quality coal gas conversion system comprises a pretreatment unit, a transformation unit, a carbon dioxide liquefaction unit and a PSA hydrogen production unit.
The pretreatment unit is used for removing ineffective components in the raw material low-quality coal gas to obtain clean coal gas; the pretreatment unit comprises a TSA impurity removal unit, a PSA nitrogen removal unit 4 and an acid gas removal unit which are sequentially connected, wherein the TSA impurity removal unit is used for carrying out temperature swing adsorption treatment on the raw material low-quality gas to remove impurities in the raw material low-quality gas and obtain first purified gas; the PSA denitrification unit 4 is used for performing pressure swing adsorption treatment on the first purified gas to remove nitrogen in the raw low-quality gas to obtain a second purified gas; and the acid gas removal unit is used for absorbing and removing carbon dioxide and hydrogen sulfide gas in the second purified gas to obtain purified gas. In one embodiment, the pretreatment unit further comprises a gas holder 1 and a low-quality gas compressor 2, wherein the low-quality gas compressor 2 is used for pressurizing raw low-quality gas from the gas holder 1 and sending the pressurized raw low-quality gas to the TSA impurity removal unit.
Wherein, the gas holder 1 can be a floating top type gas holder, a dry type gas holder, can be provided with nitrogen and fire protection facilities, and the condition for storing the low-quality gas can be as follows: the temperature is 40 ℃ and the pressure is 0.05Mpa.
In one embodiment, the TSA dehazing unit comprises a first regeneration gas inlet line 28, a second regeneration gas inlet line 29, a temperature swing adsorption unit 3, a first desorption gas exhaust line 30, and a second desorption gas exhaust line 31; the first regeneration gas inlet pipe 28 and the second regeneration gas inlet pipe 29 are arranged in parallel, a heater 32 is arranged on the first regeneration gas inlet pipe 28, and is used for heating the desorption gas from the hydrogen production pressure swing adsorption unit 26 and then sending the desorption gas to the temperature swing adsorption unit 3 as the first regeneration gas, and the second regeneration gas inlet pipe 29 is used for sending the desorption gas from the hydrogen production pressure swing adsorption unit 26 to the temperature swing adsorption unit 3 as the second regeneration gas; the temperature swing adsorption unit 3 is used for performing temperature swing adsorption treatment on the raw material low-quality gas to remove impurities in the raw material low-quality gas to obtain a first purified gas, and the first purified gas is regenerated by using the desorption gas from the hydrogen production pressure swing adsorption unit 26 after adsorption saturation; the first desorption gas exhaust pipe 30 and the second desorption gas exhaust pipe 31 are arranged in parallel, the first desorption gas exhaust pipe 30 is used for sending out a first regenerated desorption gas discharged by the temperature swing adsorption unit 3 through the first regenerated gas regeneration after heat exchange and temperature reduction through the second adjusting unit as a fuel, and the second desorption gas exhaust pipe 31 is used for sending out a second regenerated desorption gas discharged by the temperature swing adsorption unit through the second regenerated gas regeneration as a fuel; the second conditioning unit comprises a second heat exchanger 25, and the second heat exchanger 25 is used for cooling the first regenerated analyzed gas in a heat exchange manner with the crude hydrogen from the rectifying tower 23, which is subjected to heat exchange warming through the liquefier 21.
When in operation, the TSA removes impurities and adopts a temperature swing adsorption process to remove high boiling point impurity components such as hydrocarbons, naphthalene, tar, sulfide and the like in the low-quality coal gas. The regeneration of the adsorbent in the temperature swing adsorption unit 3 is divided into 4 steps: reducing pressure, heating, cooling and pressurizing. The device consists of three towers, runs for 8 hours, and regenerates for 16 hours. After regeneration, the first regenerated analysis gas and the second heat exchanger 25 exchange heat to 40 ℃, and then are merged into a decarburizing furnace together with the second regenerated analysis gas to be used as fuel.
Wherein, PSA denitrogenation unit 4 adopts pressure swing adsorption nitrogen generation, adopts the model: the 5A molecular sieve (spherical) and the HX-CO adsorbent can produce a nitrogen product with the purity of 90-95 percent, and the nitrogen product is sent to a cryogenic liquid nitrogen system to prepare liquid nitrogen. The resolved gas is purified low-quality gas called first purified gas (short for high-quality gas), and enters the acid gas removal unit.
In one embodiment, the acid gas removal unit comprises an absorption tower 5, a regeneration tower 8, a desulfurization unit 9, and a carbon dioxide conveyor 10; the absorption tower 5 is used for removing carbon dioxide in the first purified gas by using an N-methyl glycol amine solution as an absorbent to obtain carbon dioxide-removed coal gas; the regeneration tower 8 is used for stripping the absorbent from the absorption tower 5 by a stripping method to separate out carbon dioxide and sending the regenerated absorbent back to the absorption tower 5; the desulfurization device 9 is used for removing hydrogen sulfide in the decarbonized gas from the absorption tower to obtain clean gas; the carbon dioxide conveyor 10 is used to send the carbon dioxide from the regeneration column 8 to the moisture removal unit for recovery of carbon dioxide.
During operation, the absorption tower 5 absorbs carbon dioxide by using active MDEA (N-methyl ethylene glycol amine) as an absorbent, the temperature of the top of the regeneration tower 8 is controlled at 60 ℃, the absorbent from the absorption tower 5 is stripped by a stripping method to separate carbon dioxide, the regenerated absorbent is returned to the absorption tower 5 for recycling, the carbon dioxide-removed gas is sent to a desulfurization device 9 to remove hydrogen sulfide therein to obtain clean gas, and the sulfur-containing compounds obtained by desulfurization of the desulfurization device 9 can be subsequently recovered by a sulfur-removing recovery system to prepare sulfur.
The conversion unit is used for performing conversion treatment on the clean gas to obtain a mixed gas flow of hydrogen and carbon dioxide; the shift conversion unit comprises a first adjusting unit, a shift conversion reactor 13 and a water vapor removing unit, wherein the first adjusting unit is used for adjusting the temperature and/or pressure of the clean gas so as to facilitate shift conversion treatment; the shift reactor 13 is used for shifting carbon monoxide in the clean gas from the first regulating unit to obtain shift gas; the water vapor removing unit is used for removing water in the conversion gas to obtain a mixed gas flow of hydrogen and carbon dioxide.
In one embodiment, the water vapor removal unit comprises a waste boiler 11, a water cooler 12, a liquid separation tank 19 and an adsorption drying tank 20; wherein the spent pot 11 is used to recover heat from the shift gas of the shift reactor 13; the water cooler 12 is used for further cooling and reducing the temperature of the shift gas from the waste boiler 11; the liquid separation tank 19 is used for carrying out gas-liquid separation on the materials from the water cooler 12 and the carbon dioxide conveyer 10; the adsorption drying tank 20 is used for carrying out adsorption drying and water removal on the gas-phase material from the liquid separation tank 19 to obtain a hydrogen and carbon dioxide mixed gas flow;
the carbon dioxide conveyor 10 is an ejector which is used for facilitating partial conversion gas from the water cooler to be used as ejection flow to send the carbon dioxide from the regeneration tower 8 into the liquid separation tank 10.
The first adjusting unit comprises a purified gas compressor 6 and a first heat exchanger 7; wherein, the purified gas compressor 6 is used for pressurizing the purified gas; the first heat exchanger 7 is used for exchanging heat and heating the pressurized clean coal gas and the conversion gas leaving the conversion reactor 13, and sending the conversion gas after exchanging heat and cooling the temperature into the water vapor removing unit.
In one embodiment, a deoxygenation reaction catalyst bed layer 14, a first shift reaction catalyst bed layer 15 and a second shift reaction catalyst bed layer 16 are arranged in the shift reactor 13 at intervals from top to bottom; the deoxidation reaction catalyst bed layer 14 is provided with a clean gas inlet and a hydrogen inlet which are used for eliminating oxygen in the clean gas in a reaction way; the first shift reaction catalyst bed 15 is provided with a steam inlet for performing a shift reaction to reduce the content of carbon monoxide in the reaction gas from the deoxygenation reaction catalyst bed 14; the second shift reaction catalyst bed 16 is used for catalyzing shift reaction to further reduce the content of carbon monoxide in the reaction gas from the first shift reaction catalyst bed 15;
a first heat remover 17 is arranged between the deoxidation reaction catalyst bed layer 14 and the first shift reaction catalyst bed layer 15 and is used for exchanging heat between the reaction gas from the deoxidation reaction catalyst bed layer 14 and the clean gas from the first adjusting unit so as to remove part of heat;
the first shift reaction catalyst bed layer 15 is provided with a second heat remover 18 for heating the clean gas from the first heat remover 17 so as to remove the heat in the first shift reaction catalyst bed layer 18, and sending the heated clean gas to the clean gas inlet;
the hydrogen fed through the hydrogen inlet comes from a hydrogen compressor 27.
When the reactor is in operation, the upper section of the shift reactor 13 is a deoxidation reaction zone, and the oxygen content of an air source is as follows: less than 2%, and when deoxidizing, deoxidizing by using the reaction of hydrogen and oxygen, wherein the deoxidation depth (PPm) is as follows: the water is less than 1PPm; the minimum hydrogen distribution amount (v/v) is more than 2 to 3 times of the oxygen content. The outlet temperature of the deoxidation reaction zone is 280-300 ℃, a first heat remover 17 is arranged below the deoxidation reaction catalyst, clean coal gas and deoxidation gas exchange heat, the temperature of the lower end of the first heat remover 17 is maintained at 210-220 ℃, and the CO concentration in the deoxidation gas reaches 33-39%.
The middle section of the shift reactor 13 is a shift reaction zone, and a shift catalyst (the short term of the shift reaction zone) adopts a copper-based shift catalyst; the first reaction condition may be: airspeed: less than 5000 (h) -1 ) (ii) a The pressure is 0.1-5.5 Mpa; temperature: the temperature is 200-250 ℃; the first-change reaction is carried out at low temperature under the action of a catalyst. The second heat remover 18 is arranged in the first change catalyst to maintain the temperature of the bottom layer of the first change catalyst within the range of 210-220 ℃, and the reaction gas after the first change enters the second change after exchanging heat with clean gas. The CO conversion rate is more than 98% and the outlet CO concentration is less than 3%. The first-changing outlet enters into a second-changing reaction at the temperature of 200-210 ℃.
The lower section of the shift reactor 13 is a second shift reaction zone, and a second shift (short for second-stage shift, also called second shift reaction zone) can adopt a B207 type shift catalyst to catalyze the reaction gas from the first shift so as to further convert CO; the operating conditions may be: space velocity: less than 5000 (h) -1 ) (ii) a The pressure is 1-3.5 Mpa; temperature: 200 ℃ to 220 ℃, inlet CO concentration: is less than 3 percent.
The secondary change gas is cooled through the first heat exchanger 7, then cooled through the waste boiler 11, then exchanges heat with the water cooler 12, is led out of a branch line to enter an ejector nozzle opening of the carbon dioxide conveyor 10, carbon dioxide of the acid gas regeneration system is ejected into the liquid separation tank 19 for gas-liquid separation, and then enters the adsorption drying tank 20 for dehydration and drying.
Wherein the carbon dioxide liquefaction unit is used for preparing a liquid carbon dioxide product from the mixed gas stream of hydrogen and carbon dioxide; the carbon dioxide liquefaction unit comprises a liquefier 21 and a rectifying tower 23 with a reboiler 24, wherein the liquefier 21 is used for cooling part of the mixed gas flow of hydrogen and carbon dioxide from the water vapor removal unit and subjected to heat exchange and temperature reduction by the reboiler 24 and the rest of the mixed gas flow of hydrogen and carbon dioxide from the water vapor removal unit so as to liquefy carbon dioxide in the mixed gas flow of hydrogen and carbon dioxide and obtain a separation raw material to be rectified; the rectifying tower 23 is used for rectifying and separating the raw material to be rectified and separated from the liquefier 21 so as to obtain a crude hydrogen product stream at the tower top and a liquid carbon dioxide product at the tower bottom.
When the device is in operation, a branch line of the mixed gas flow of hydrogen and carbon dioxide from the water vapor removal unit is led into a reboiler 24 at the bottom of the rectifying tower 23, liquid carbon dioxide at the bottom of the rectifying tower is heated and evaporated and then is merged into the liquefier 21 with the main line for cooling, then the cooled gas flow enters the rectifying tower 23 to separate the carbon dioxide and the hydrogen, the top of the rectifying tower 23 is controlled to be-30 ℃, the hydrogen at the top of the rectifying tower is decompressed to 0.8-1.6 Mpa through a decompression valve to keep the cold quantity at the top of the rectifying tower, the non-condensable gas (hydrogen) separated from the top of the rectifying tower enters the liquefier 21 to be used as a cold source for heat exchange and then enters the PSA hydrogen production unit, the temperature at the bottom of the rectifying tower is controlled to be-36-38 ℃, CO is controlled to be-38 DEG, and 2 the food grade with the purity of 99.9 percent is sent to a tank field for storage.
The cold source of the liquefier 21 can be an ice maker system 22 which comprises an ammonia press, an oil separator, a condenser, an ammonia storage device, an ammonia-liquid separation tank and the like, wherein the ice maker system produces liquid ammonia which is CO 2 The liquefier 21 provides refrigeration.
Wherein the PSA hydrogen production unit is used for performing pressure swing adsorption separation on impurities in a crude hydrogen product stream from the carbon dioxide liquefaction unit to obtain a hydrogen product; the PSA hydrogen production unit comprises a second conditioning unit, a hydrogen production pressure swing adsorption unit 26, and an optional hydrogen compressor 27; wherein the second conditioning unit is used to condition the temperature and/or pressure of the crude hydrogen product stream from the carbon dioxide liquefaction unit for subsequent pressure swing adsorption processing; the hydrogen production pressure swing adsorption unit is used for carrying out pressure swing adsorption separation on impurities in the crude hydrogen product flow from the second adjusting unit to obtain a hydrogen product; the hydrogen compressor 27 is used for pressurizing the hydrogen product from the hydrogen-producing pressure swing adsorption unit. The desorption gas from the hydrogen-production pressure swing adsorption unit is heated and then is sent to the temperature swing adsorption unit 3 as a first regeneration gas, and the unheated desorption gas from the hydrogen-production pressure swing adsorption unit is sent to the temperature swing adsorption unit 3 as a second regeneration gas; the adsorption tower of the hydrogen production pressure swing adsorption unit 26 in the PSA hydrogen production unit adopts 9 towers combination, wherein 3 towers run, 6 towers regenerate, and hydrogen production is sent to a hydrogen pipe network by a hydrogen compressor.
Examples
Low quality coal gas flow rate of 200000Nm 3 Low quality gas composition% vol (dry basis): h 2 ：22.5～28；CH 4 ：1～3；CO：15～24；CO 2 ：4～9；N 2 ：40～46；H 2 S：≤1200mg/Nm 3 。
The low-quality coal gas is lifted to the pressure of 0.45Mpa and the temperature of 50 ℃ through a screw compressor, enters a TSA temperature swing adsorption unit, and hydrocarbon, naphthalene, tar, sulfide and other high-boiling-point impurity components in the low-quality coal gas are removed through sequentially packed adsorbents 1-3, wherein the type of the adsorbent 1 is as follows: CNA-421; appearance: white spherical particles; the crushing strength (N/grain) is more than or equal to 80.2; bulk density (g/ml): 0.68 to 0.72; water absorption (%) of 43 to 51; specific surface area (m) 2 (iv)/g): 251 to 306; particle size (mm): phi is 3 to 5; the water content (%) of the product is less than or equal to 2.0; pore volume (cm) 3 (iv)/g): 0.4 to 0.5; adsorbent 2 type CNA-316: appearance: a pale yellow transparent or translucent spherical shape; water adsorption RH =20%>8.2；RH＝50％>20.4；RH＝90％>30.3; the granularity (mm) phi is 1-3; abrasion Rate (%)<5.0; heating loss (%)<2.0 of the total weight of the mixture; bulk density (g/ml): 0.75 to 0.80; siO 2 2 Content (%)>98.5 of the total weight of the mixture; percent pass of particle size (%)>90.0 of the total weight of the alloy; percent of pass of spherical pellets (%)>84.0; type 3 of the adsorbent: CNA-213; external form size Φ (mm): columnar particles, 4.0 ± 0.2; bulk density (g/ml): 0.61 to 0.65; strength: (%) is more than or equal to 96; ash content: the percentage is less than or equal to 7; water content: the percentage is less than or equal to 1.5.
Regeneration of the adsorbent in a TSA temperature swing adsorption unit is divided into 4 steps: reducing pressure, heating, cooling and pressurizing. Consists of three towers, each tower runs for 8 hours, and the regeneration lasts for 16 hours. The regenerated gas comprises a second regenerated gas and a first regenerated gas, the first regenerated gas and the second regenerated gas are merged into a carbonization furnace to be used as fuel after heat exchange with the heat exchanger 2 is carried out to 40 ℃, the regenerated gas of the PSA hydrogen production unit is provided with an electric heater, the regenerated gas is heated to 150 ℃, high-temperature desorption is carried out on TSA, and the desorbed gas is sent to the carbonization furnace to be used as fuel.
The low-quality gas from the TSA enters a PSA denitrification unitAdopting PSA pressure swing adsorption nitrogen production system, adopting 5A molecular sieve (spherical) and HX-CO adsorbent, in which the 5A molecular sieve is calcium sodium type aluminosilicate, and the pore size of crystal is
(0.5 nm); diameter (mm): 1.6 to 2.5; static water adsorption (more than or equal to%): 21.5; bulk density (. Gtoreq.g/ml): 0.68; compressive strength (N/grain): 82; the abrasion rate (less than or equal to percent): 0.1; packaging water content (less than or equal to%): 1.5.HX-CO adsorbent: mCuCl nNa 2 O·Al 2 O 3 ·xSiO 2 Wherein the content of CuCl (wt%) is more than or equal to 20; appearance: off-white, appearance: cylindrical phi (1.8-2.2) x (3-8); compressive strength (N/grain): 20; the abrasion rate (less than or equal to percent): 1.5; bulk density (. Gtoreq.g/ml): 0.82; packaging water content (less than or equal to%): 1.5; and producing a nitrogen product with the purity of 90-95 percent, and sending the nitrogen product to a cryogenic liquid nitrogen system for preparing liquid nitrogen. The decomposed gas is purified low-quality gas which is called clean gas and enters an acid gas removal unit for removing acid gas. 8 sets of PSA pressure swing adsorption nitrogen making towers are used in parallel, two pressure equalizations are adopted, and desorption gas is used for regeneration and blowing.
Absorbing carbon dioxide in first purified gas by using active MDEA (N-methyl ethylene glycol amine) as an absorbent in an absorption tower, controlling the temperature of the top of a regeneration tower to be 60 ℃, stripping the absorbent from the absorption tower 5 by using a stripping method to separate out the carbon dioxide, returning the regenerated absorbent to the absorption tower 5 for recycling, sending the separated carbon dioxide to an inlet of an ejector receiving chamber, sending the carbon dioxide-removed gas to a desulfurization device 9 to remove hydrogen sulfide therein to obtain purified gas (for example, sodium carbonate is used as a desulfurization absorption liquid in a super-gravity separation device, the concentration of the sodium carbonate is 12g/l, and the vapor-liquid ratio is 18.84l/m 3 Supergravity factor: 94.44, the desulfurization rate is more than 96 percent, PDS is adopted as a desulfurization catalyst), and the sulfur-containing compound obtained by desulfurization of the desulfurization device 9 can be subsequently recovered by a sulfur removal and recovery system to prepare sulfur.
The desulfurized and decarbonized low-quality coal gas enters a clean coal gas compressor to be pressurized to 1.25Mpa and the temperature is 80-100 ℃, then the low-quality coal gas exchanges heat with the shift gas at the secondary shift outlet to 120 ℃, the low-quality coal gas enters a shift reactor, the shift reactor is in a square column shape, and the clean coal gas sequentially carries out deoxidation reaction, primary shift reaction and secondary shift reaction from top to bottom.
In the deoxidation reaction zone, a HT type palladium catalyst deoxidation catalyst is adopted, and the particle size (mm): phi 3 to phi 5; palladium content (%): 0.02 to 5; mechanical strength (N/grain): 50; bulk specific gravity (g/ml): 0.8 plus or minus 0.05; oxygen content of an air source: less than 2 percent; deoxygenation depth (PPm): below < 1PPm; the minimum hydrogen blending amount (v/v) is more than 2-3 times of the oxygen content. The deoxidation reaction zone is at 220 ℃,1.25Mpa, space velocity: 2500h -1 Reacting with hydrogen under the condition that the outlet temperature is 280-300 ℃, and a first heat transfer device consisting of a plurality of tube bundles is arranged below the deoxidation catalyst, so that the heat exchange between clean coal gas and the deoxidation gas is realized, the temperature of the bottom layer of the deoxidation catalyst is maintained at 210-220 ℃, the CO concentration in the deoxidized oxygen is concentrated to 33-39 percent and the deoxidized oxygen enters a variable reaction zone.
The first-stage shift (first-stage shift) catalyst adopts a copper-based CNB-1 type shift catalyst (purchased from southwest chemical research institute), and the bulk density (g/ml) of the catalyst is 1.2+0.5; radial strength: greater than 250N/cm; abrasion: less than 8%; size: phi 5 x (3 to 4) nm; bulk density (g/ml) 0.75. The conversion rate of the first transformation is more than 90 percent, the CO concentration at the outlet is less than 3 percent, and the reaction gas at the 240 ℃ of the first transformation outlet enters a second transformation reaction zone after heat exchange. The first catalyst is provided with a second heat transfer device which is arranged by a plurality of transverse tube bundles from top to bottom according to the linear rule of exothermic reaction of the first catalyst, so that the purposes of heat exchange and temperature equalization of reaction heat of a gas-changing and clean gas are fulfilled, and the temperature of the bottom layer of the first catalyst is maintained at 210-220 ℃. The first change gas enters the second change reaction area.
Two-stage conversion (two-stage conversion) adopts low steam ratio catalyst (type: B207; pore volume (cm) 3 (iv)/g): 0.42; specific surface area (m) 2 (iv)/g): 256.53; pore diameter: 2.3nm; the crushing strength (N/particle) is more than or equal to 180; bulk density (g/ml) 1.4; ) At space velocity of 4500 (h) -1 ) (ii) a 1.2Mpa, 200-220 ℃,2.75 water-carbon ratio; inlet CO concentration: 3 percent, and the outlet concentration reaches 0.12 percent; secondly, changing the steam-gas ratio of the outlet: 0.3. the secondary change gas is 240 ℃, the temperature of 1.2Mpa is reduced to 180 ℃ through heat exchange, the temperature is reduced to 135 ℃ through a waste boiler, a branch line is led out to enter a nozzle opening of a carbon dioxide ejector after the heat exchange with a water cooler, and carbon dioxide from a flash tank is led to a branch lineIn the liquid tank, gas-liquid separation is carried out in the liquid separating tank together with the main line conversion gas.
Then the mixture enters an adsorption drying tank, and a JK-K2 composite active alumina adsorbent is adopted in the tank: particle size (mm): phi 3 to phi 5; bulk specific gravity (g/ml): 0.68 to 0.7; compressive strength (N/particle): more than 110; the abrasion rate (less than or equal to percent): 0.3; specific surface area (m) 2 (iv)/g): 360; the static water adsorption is more than or equal to 20 percent. After the shifted gas is removed and dried, part of the shifted gas firstly enters a reboiler at the bottom of a rectifying tower, the liquid carbon dioxide is heated and evaporated and then is merged with a main line into a liquefier to be cooled to minus 38 ℃ and then enters the rectifying tower to be rectified with the carbon dioxide, the top of the rectifying tower is controlled to be minus 30 ℃, hydrogen at the top of the rectifying tower is stripped to 0.8 to 1.6MPa through a pressure reducing valve to keep the cold quantity at the top of the rectifying tower, and non-condensable gas (hydrogen) separated from the top of the rectifying tower enters the liquefier to be used as a cold source to exchange heat and then enters a PSA hydrogen production unit. Temperature control of the tower bottom is carried out at minus 36 to minus 38 ℃, and CO is carried out 2 The food grade with the purity of 99.9 percent is sent to a tank field for storage. The system cold energy is provided by an ice machine system, the crude hydrogen cold energy of the rectifying tower and the gas carbon dioxide exchange heat normally, and the insufficient cold energy is provided by the ice machine.
The hydrogen production pressure swing adsorption unit of the PSA hydrogen production unit is formed by combining 9 towers, operating 3 towers and regenerating 6 towers, wherein the adsorbent is filled with an AS adsorbent, HXBC-15B adsorbent, HX5A-98H adsorbent and HXNA-CO adsorbent in equal volume from the bottom of the tower to the top in sequence. The hydrogen production purity of the PSA hydrogen production unit is 99.6 percent, and the hydrogen is sent to a hydrogen pipe network.
The devices or elements related in the present invention may adopt processing facilities, devices or elements with corresponding functions in the prior art, which is not described in detail herein. Those skilled in the art will understand or know what is not described herein, and will not be described in detail.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. Not all embodiments are exhaustive. All obvious changes and modifications of the technical solution of the present invention are included in the spirit of the present invention.
For example, (1) the shift reactor may be an isothermal shift reactor, and is within the scope of the present patent; (2) It is within the scope of this patent that the hot potassium process may be used instead of the active MEDA process.
Claims (10)
1. A low-quality gas conversion system, comprising:
the pretreatment unit is used for removing ineffective components in the raw material low-quality gas to obtain clean gas;
the pretreatment unit comprises a TSA impurity removal unit, a PSA denitrification unit and an acid gas removal unit which are sequentially connected, wherein the TSA impurity removal unit is used for carrying out temperature swing adsorption treatment on raw low-quality coal gas so as to remove impurities in the raw low-quality coal gas and obtain first purified gas; the PSA denitrification unit is used for carrying out pressure swing adsorption treatment on the first purified gas to remove nitrogen in the raw material low-quality coal gas to obtain a second purified gas; the acid gas removal unit is used for absorbing and removing carbon dioxide and hydrogen sulfide gas in the second purified gas to obtain purified gas;
the conversion unit is used for performing conversion treatment on the clean gas to obtain a mixed gas flow of hydrogen and carbon dioxide;
the shift conversion unit comprises a first adjusting unit, a shift conversion reactor and a water vapor removing unit, wherein the first adjusting unit is used for adjusting the temperature and/or pressure of the clean gas so as to facilitate shift conversion treatment; the shift reactor is used for shifting carbon monoxide in the clean gas from the first adjusting unit to obtain shift gas; the water vapor removal unit is used for removing water in the conversion gas to obtain a hydrogen and carbon dioxide mixed gas flow;
a carbon dioxide liquefaction unit for preparing a liquid carbon dioxide product from the mixed gas stream of hydrogen and carbon dioxide;
the carbon dioxide liquefaction unit comprises a liquefier and a rectifying tower with a reboiler, wherein the liquefier is used for cooling part of the hydrogen and carbon dioxide mixed gas flow which comes from the water vapor removal unit and is subjected to heat exchange and temperature reduction through the reboiler and the rest of the hydrogen and carbon dioxide mixed gas flow which comes from the water vapor removal unit so as to liquefy carbon dioxide in the hydrogen and carbon dioxide mixed gas flow, and thus the raw material to be rectified and separated is obtained; the rectifying tower is used for rectifying and separating the raw materials to be rectified and separated from the liquefier so as to obtain a crude hydrogen product stream at the tower top and a liquid carbon dioxide product at the tower bottom;
the PSA hydrogen production unit is used for carrying out pressure swing adsorption separation on impurities in the crude hydrogen product stream from the carbon dioxide liquefaction unit to obtain a hydrogen product;
the PSA hydrogen production unit comprises a second regulating unit, a hydrogen production pressure swing adsorption unit and an optional hydrogen compressor; wherein the second conditioning unit is used to condition the temperature and/or pressure of the crude hydrogen product stream from the carbon dioxide liquefaction unit for subsequent pressure swing adsorption treatment; the hydrogen production pressure swing adsorption unit is used for carrying out pressure swing adsorption separation on impurities in the crude hydrogen product flow from the second regulating unit to obtain a hydrogen product; the hydrogen compressor is used for pressurizing the hydrogen product from the hydrogen production pressure swing adsorption unit.
2. The conversion system of claim 1, wherein said pretreatment unit further comprises a gas holder and a low-quality gas compressor for pressurizing raw low-quality gas from said gas holder and sending the pressurized raw low-quality gas to said TSA dehazing unit.
3. The conversion system of claim 1 or 2, wherein the TSA dehazing unit comprises a first regeneration gas inlet line, a second regeneration gas inlet line, a temperature swing adsorption unit, a first desorption gas exhaust line, and a second desorption gas exhaust line; the first regenerated gas inlet pipe and the second regenerated gas inlet pipe are arranged in parallel, a heater is arranged on the first regenerated gas inlet pipe and used for heating the desorption gas from the hydrogen production pressure swing adsorption unit and then sending the desorption gas to the temperature swing adsorption unit as a first regenerated gas, and the second regenerated gas inlet pipe is used for sending the desorption gas from the hydrogen production pressure swing adsorption unit to the temperature swing adsorption unit as a second regenerated gas; the temperature swing adsorption unit is used for carrying out temperature swing adsorption treatment on the raw material low-quality coal gas to remove impurities in the raw material low-quality coal gas to obtain first purified gas, and the first purified gas is regenerated by using the desorption gas from the hydrogen production pressure swing adsorption unit after adsorption saturation; the first desorption gas exhaust pipe and the second desorption gas exhaust pipe are arranged in parallel, the first desorption gas exhaust pipe is used for sending out a first regeneration desorption gas discharged by the temperature swing adsorption unit through the first regeneration gas regeneration as a fuel after the first regeneration desorption gas exchanges heat and is cooled through the second adjusting unit, and the second desorption gas exhaust pipe is used for sending out a second regeneration desorption gas discharged by the temperature swing adsorption unit through the second regeneration gas regeneration as a fuel;
preferably, the second conditioning unit comprises a second heat exchanger for cooling down the first regenerated cracked gas by heat exchange with the crude hydrogen from the rectification column, which is heated up by heat exchange with the liquefier.
4. The conversion system of any one of claims 1-3, wherein the acid gas removal unit comprises an absorption tower, a regeneration tower, a desulfurization unit, and a carbon dioxide conveyor; the absorption tower is used for removing carbon dioxide in the first purified gas by using an N-methyl glycol amine solution as an absorbent to obtain carbon dioxide-removed coal gas; the regeneration tower is used for stripping the absorbent from the absorption tower through a stripping method to separate out carbon dioxide and sending the regenerated absorbent back to the absorption tower; the desulfurization device is used for removing hydrogen sulfide in the decarbonized gas from the absorption tower to obtain clean gas; the carbon dioxide conveyor is used for conveying the carbon dioxide from the regeneration tower to the water vapor removal unit to recover the carbon dioxide.
5. The conversion system of claim 4, wherein the moisture removal unit comprises a waste boiler, a water cooler, a liquid separation tank, and an adsorption drying tank; wherein the spent pot is used to recover heat from the shift gas of the shift reactor; the water cooler is used for further cooling the shift gas from the waste boiler; the liquid separation tank is used for carrying out gas-liquid separation on the materials from the water cooler and the carbon dioxide conveyor; the adsorption drying tank is used for carrying out adsorption drying and water removal on the gas-phase material from the liquid separation tank to obtain a hydrogen and carbon dioxide mixed gas flow;
preferably, the carbon dioxide conveyor is an ejector, and the ejector is used for facilitating partial conversion gas from the water cooler to be used as ejection flow for feeding the carbon dioxide from the regeneration tower into the liquid separation tank.
6. The conversion system according to any one of claims 1 to 5, wherein the first conditioning unit comprises a clean gas compressor and a first heat exchanger; the clean gas compressor is used for pressurizing the clean gas; the first heat exchanger is used for exchanging heat and heating the pressurized clean gas and the converted gas leaving the conversion reactor, and sending the converted gas after exchanging heat and cooling to the water vapor removal unit.
7. The conversion system according to any one of claims 1 to 6, wherein a deoxidation reaction catalyst bed layer, a first shift reaction catalyst bed layer and a second shift reaction catalyst bed layer are arranged at intervals in the shift reactor from top to bottom in sequence; a clean gas inlet and a hydrogen inlet are formed in the deoxidation reaction catalyst bed layer and are used for eliminating oxygen in the clean gas in a reaction manner; the first shift reaction catalyst bed layer is provided with a steam inlet for shift reaction so as to reduce the content of carbon monoxide in reaction gas from the deoxidation reaction catalyst bed layer; the second shift reaction catalyst bed is used for catalyzing shift reaction so as to further reduce the content of carbon monoxide in the reaction gas from the second shift reaction catalyst bed;
a first heat remover is arranged between the deoxidation reaction catalyst bed layer and the first shift reaction catalyst bed layer and used for exchanging heat between the reaction gas from the deoxidation reaction catalyst bed layer and the clean gas from the first adjusting unit so as to remove part of heat;
the first shift reaction catalyst bed layer is internally provided with a first heat remover for heating the clean gas from the first heat remover so as to remove the heat in the first shift reaction catalyst bed layer and sending the heated clean gas to the clean gas inlet;
preferably, the hydrogen gas fed through the hydrogen inlet comes from the hydrogen compressor.
8. Method for low quality gas conversion using a conversion system according to any of claims 1-7.
9. The method of claim 8, wherein the adsorbents used for the temperature swing adsorption process using said TSA desaturation unit are CNA-421 type, CNA-316 type and CNA-213 type adsorbents packed in order along the gas flow direction;
the PSA denitrification unit is used for pressure swing adsorption treatment, and the adopted adsorbents are a 5A molecular sieve and a HX-CO adsorbent which are sequentially stacked along the airflow direction;
the adsorbent used for the PSA hydrogen production unit to carry out pressure swing adsorption treatment is AS adsorbent, HXBC-15B, HX5A-98H, HXNA-CO adsorbent and inert ceramic balls which are sequentially stacked along the airflow direction.
10. The method according to claim 8 or 9, characterized in that the catalyst used in the deoxidation reaction catalyst bed layer is HT-2 type deoxidation catalyst, and the deoxidation reaction is carried out at 220 ℃ and 1.25Mpa; space velocity: 2500h -1 Reacting with hydrogen, wherein the outlet temperature is 280-300 ℃, a shell and tube heat exchanger is arranged below a deoxidation catalyst, clean gas exchanges heat with the deoxidation gas, the bottom temperature of the deoxidation catalyst is maintained at 210-220 ℃, and the CO concentration of the clean gas reaches 33-39%;
the first shift reaction catalyst bed layer adopts a copper system CNB-1 type catalyst; the catalyst comprises the following components: the ratio of copper oxide/zinc oxide/aluminum oxide is 38%/40%/6-8%; controlling the temperature of reaction gas leaving the first shift reaction catalyst bed layer to be 200-210 ℃ and the CO concentration to be lower than 3 percent;
the second shift reaction catalyst bed layer adopts a B207 type catalyst; the temperature of the reaction gas leaving the second shift reaction catalyst bed layer is controlled to be 230-250 ℃, and the CO concentration is lower than 0.12%.
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| CN211284269U (en) * | 2019-09-26 | 2020-08-18 | 中国神华煤制油化工有限公司 | Raw coke oven gas purification system |
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