Double-loop system for producing hydrogen through CO conversion

Abstract

The utility model provides a double-loop CO conversion hydrogen production system which comprises an adiabatic conversion loop and an isothermal conversion loop, and the isothermal conversion loop and the isothermal conversion loop respectively and independently comprise a medium-low pressure steam generator for generating low-pressure saturated steam. An isothermal conversion furnace loop is used in normal production, and an adiabatic conversion furnace loop is used as a standby loop. When the isothermal conversion furnace leaks, the isothermal conversion furnace can be switched to a heat insulation conversion loop for continuous production. When the isothermal shift catalyst and the adiabatic shift catalyst are both partially inactivated and the CO concentration out of the device exceeds the standard, the isothermal shift loop and the adiabatic shift loop are put into use at the same time, and the CO concentration does not exceed the standard by reducing the use space velocity of the catalyst, so that the service life of the catalyst is prolonged, and the operation cost of the device is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of coal chemical industry, and in particular relates to a double-loop CO conversion hydrogen production system. Background Art

[0002] The coal chemical industry has entered a stage of rapid development, and technologies such as the production of synthetic ammonia, urea, synthetic methanol, ethylene glycol, and synthetic natural gas using coal as raw materials have been vigorously developed. Representative coal gasification technologies include pulverized coal pressurized gasification technology (SHELL, Aerospace Furnace, GSP, SE-Oriental Furnace, etc.) and water-coal slurry gasification technology (Texaco, multi-nozzle, multi-element slurry, etc.), and the water-gas ratio of the produced raw coal gas is 0.6-1.7, and the carbon monoxide content (V% dry basis) is as high as 40%-75%.

[0003] The carbon monoxide shift process is an indispensable part of modern coal chemical technology and plays a connecting role. The purpose of CO shift is to convert CO into H 2 , to meet the production requirements of downstream processes.

[0004] The CO conversion reaction is an exothermic reaction. The traditional CO conversion hydrogen production process mostly adopts the "multi-stage adiabatic reaction + indirect heat recovery" method to set up the process. This process has a series of problems such as long process, multiple equipment, large investment, high energy consumption, large system pressure drop, and short catalyst life.

[0005] In the isothermal shift hydrogen production process developed in recent years, whether it is an adiabatic shift series isothermal shift process, an isothermal shift series adiabatic shift process, or a dual isothermal shift furnace series process, each shift furnace is connected in series, and it is a single-loop shift process without a spare production line. When an isothermal shift furnace leaks and needs to be repaired or the isothermal shift catalyst is deactivated and needs to be replaced, the device needs to be stopped, affecting the continuous production of the device and causing certain economic losses to the enterprise.

[0006] The investigation found that during the operation of the built isothermal conversion device, the isothermal conversion furnaces of multiple devices leaked, resulting in unplanned shutdown of the device and causing great economic losses to the company. As described in the article "Internal Leakage and Maintenance of Isothermal Conversion Furnace", when the isothermal conversion furnace leaked, the maintenance process took more than a month, seriously affecting the long-term operation of the device.

[0007] In the prior art, Ma Ming's article "Exploration of Isothermal Conversion Technology to Replace Traditional Conversion Process" proposed a transformation plan to add an isothermal conversion system on the basis of the original conversion process flow, which solved the problems of rapid deactivation of the catalyst in the conversion device and excessive CO content in the conversion gas. During normal production, the isothermal conversion furnace is used in series between two medium-temperature adiabatic conversion furnaces and two low-temperature conversion furnaces. When the isothermal conversion furnace fails, the isothermal conversion furnace is cut out of the system and the original adiabatic conversion circuit is used to continue production. Existing problems: When the isothermal conversion furnace is put into use, although there is no reaction in the two low-temperature conversion furnaces, the conversion gas still has to flow through the two low-temperature conversion furnaces. The pressure drop of each low-temperature conversion furnace is calculated as 0.03MPa, totaling 0.06MPa, resulting in a larger consumption of medium-pressure steam in the ammonia synthesis gas compressor, which increases the energy consumption of the device. Another example is the "Adiabatic series isothermal conversion process for high-concentration CO raw gas" disclosed in the Chinese invention patent application with application number 201410439881.7, whose process flow is set as: adiabatic + isothermal conversion process, adiabatic + isothermal + adiabatic conversion process. Problem: When the isothermal conversion furnace leaks, the device can only be stopped to repair the isothermal conversion furnace. Another example is the "Water transfer heat conversion process for energy-saving deep conversion of by-product high-grade steam" disclosed in the Chinese invention patent application with application number 201210185731.9, whose process flow is set as: double isothermal conversion furnace series process, adiabatic + isothermal conversion process, adiabatic + isothermal + adiabatic conversion process. The "Isothermal conversion hydrogen production method and isothermal conversion furnace for matching pulverized coal gasification device" disclosed in the Chinese patent application with application number 201911014621.4, whose process flow is set as adiabatic conversion + isothermal conversion hydrogen production. Problem: When the isothermal conversion furnace leaks, the device can only be stopped to repair the isothermal conversion furnace. For example, the "CO conversion process and isothermal conversion furnace for co-production of synthesis gas and hydrogen" disclosed in the Chinese patent application with application number 201911014653.4 has a process flow set as adiabatic conversion parallel isothermal conversion to produce hydrogen and synthesis gas. The adiabatic conversion loop + non-conversion loop is used to produce synthesis gas, and the isothermal conversion loop is used to produce hydrogen. Problem: When the isothermal conversion furnace leaks, the isothermal conversion system is cut out, and the device can only produce synthesis gas but not hydrogen. There is also the "CO conversion device system matched with a water-coal slurry gasification device" disclosed in the Chinese patent application with application number 201020291829.9, whose process flow is set as multi-stage adiabatic conversion reaction + indirect heat recovery. This process has only one adiabatic conversion loop and is not equipped with an isothermal conversion loop.

[0008] Therefore, leakage in the isothermal shift furnace affecting the continuous production of the device is an issue that cannot be avoided in the design of the CO shift process. Utility Model Content

[0009] In order to solve the above-mentioned problems in the prior art, the utility model proposes a dual-circuit CO conversion hydrogen production system suitable for multiple working conditions. The isothermal conversion furnace circuit is put into use for normal production, and the adiabatic conversion furnace circuit is used as a backup circuit. When the isothermal conversion furnace leaks, it can be switched to the adiabatic conversion circuit to continue production. When the isothermal conversion catalyst and the adiabatic conversion catalyst are both partially deactivated and the CO concentration of the device exceeds the standard, the isothermal conversion circuit and the adiabatic conversion circuit are put into use at the same time. By reducing the space velocity of the catalyst, the CO concentration is ensured not to exceed the standard, thereby extending the service life of the catalyst and reducing the operating cost of the device.

[0010] The utility model proposes a double-loop CO2 conversion hydrogen production system, characterized in that the system comprises an adiabatic conversion loop and an isothermal conversion loop; the adiabatic conversion loop and the isothermal conversion loop share a first conversion furnace, a low-pressure steam generator, and a medium-pressure boiler water preheater;

[0011] The adiabatic conversion loop and the isothermal conversion loop each independently include a medium-low pressure steam generator I; the medium-low pressure steam generator I generates medium-low pressure saturated steam.

[0012] As a specific implementation mode of the utility model, the isothermal conversion circuit also includes an isothermal conversion furnace and a steam drum; the isothermal conversion furnace is connected to the steam drum upstream to take away the reaction heat and generate low-pressure saturated steam; wherein the isothermal conversion furnace is connected in series with the medium and low pressure steam generator I and shares the upstream medium and low pressure steam superheater, and the medium and low pressure saturated steam is superheated and sent to downstream users.

[0013] As a specific embodiment of the utility model, the isothermal conversion circuit also includes a crude gas separator, a crude gas heater, a detoxification tank, a first conversion furnace, medium and low pressure steam superheaters, a medium pressure boiler water preheater, and a low pressure steam generator.

[0014] As a specific implementation of the utility model, the raw gas heater and the medium and low pressure steam generator I are each independently provided with a temperature regulating sub-line.

[0015] As a specific implementation of the utility model, a temperature control valve is provided on the temperature regulating sub-line.

[0016] As a specific implementation of the utility model, the adiabatic conversion circuit also includes a second conversion furnace and a low-temperature conversion furnace; the low-temperature conversion furnace is used in series downstream of the isothermal conversion furnace or the low-temperature conversion furnace and the isothermal conversion furnace are used in parallel.

[0017] As a specific embodiment of the utility model, the adiabatic conversion circuit also includes a crude gas separator, a crude gas heater, a detoxification tank, a first conversion furnace, a medium and low pressure steam superheater, a medium and low pressure steam generator I, a medium and low pressure steam generator II, a medium pressure boiler water preheater, and a low pressure steam generator.

[0018] As a specific implementation of the utility model, the raw gas heater and the medium and low pressure steam generator II are each independently provided with a temperature regulating sub-line.

[0019] As a specific implementation of the utility model, a temperature control valve is provided on the temperature regulating sub-line.

[0020] As a specific implementation of the utility model, the system also includes valve one, valve two, valve three, valve four, valve five, valve six, valve seven, and valve eight.

[0021] As a specific implementation mode of the utility model, when the valves one, three, five and seven are closed and the valves two, four, six and eight are opened, the first conversion furnace and the isothermal conversion furnace are used in series; under normal working conditions, the isothermal conversion circuit operates alone.

[0022] When valves 2, 3, 4, 6 and 8 are closed and valves 1, 5 and 7 are opened, the first conversion furnace, the second conversion furnace and the low-temperature conversion furnace are used in series; they are applied to isothermal conversion furnace accident conditions, and the adiabatic conversion circuit operates alone.

[0023] When the valves one, four and seven are closed and the valves two, three, five, six and eight are opened, the first conversion furnace, the isothermal conversion furnace and the low-temperature conversion furnace are used in series; it is applied to the condition of partial deactivation of the isothermal conversion catalyst, the isothermal conversion circuit operates alone, and the low-temperature conversion furnace is used in series downstream of the isothermal conversion furnace.

[0024] When the valve 3 is closed and the valves 1, 2, 4, 5, 6, 7 and 8 are opened, the isothermal shift furnace is used in parallel with the second shift furnace and the low-temperature shift furnace. It is applied to the condition where the isothermal shift catalyst and the adiabatic shift catalyst are partially deactivated at the same time, and the two shift circuits are operated simultaneously.

[0025] As a specific implementation of the present utility model, a crossover line is provided between the isothermal conversion furnace and the low-temperature conversion furnace.

[0026] As a specific embodiment of the present invention, the working process of the double-loop CO conversion hydrogen production system of the present invention includes:

[0027] The raw coal gas 1 with a temperature of 180℃~260℃ and 3.0~6.5MPa(G) from the water-coal slurry gasification device enters the raw coal gas separator 2. After the condensate is separated, the raw coal gas is heated to 230℃~280℃ by the raw coal gas heater 3 and then enters the detoxification tank 4. After the dust and other impurities are removed by the detoxification tank 4, the raw coal gas enters the first conversion furnace 5. The first conversion gas with a temperature of 400℃~480℃ out of the first conversion furnace 5 enters the medium-low pressure steam superheater 6, superheats the medium-low pressure saturated steam of 1.3~2.0MPa(G) to 250℃~300℃, and the temperature of the first conversion gas is reduced to 360℃~410℃. Then, it enters the raw coal gas heater 3 to heat the raw coal gas, and the temperature of the first conversion gas is reduced to 310℃~370℃. Then, it enters the medium-low pressure steam generator Ⅰ7, and produces medium-low pressure saturated steam of 1.3~2.0MPa(G) as a byproduct. The temperature of the first conversion gas is reduced to 230℃~270℃ and then enters the isothermal conversion furnace 11 through the flow control valve 2. The CO concentration of the fourth conversion gas at the outlet of the isothermal conversion furnace 11 is reduced to 0.3%~0.5% (V%), and the temperature is 200℃~230℃, and then it is divided into two streams. The first stream of the fourth conversion gas 21 enters the medium-pressure boiler water preheater 13, preheats the boiler water of 100℃~110℃ and 2.5~3.5MPa(G) to 160℃~200℃, and then is sent to the medium-low pressure steam generator Ⅰ7, the medium-low pressure steam generator Ⅱ9 and the steam drum 12 respectively to produce 1.3~2.0MPa(G) of medium-low pressure saturated steam. The temperature of the first stream of the fourth conversion gas is reduced to 150℃~200℃. The second fourth conversion gas 22 enters the low-pressure steam generator 14, and produces 0.4-1.0 MPa (G) of low-pressure saturated steam as a by-product. The temperature of the second fourth conversion gas is reduced to 150°C-200°C, and is mixed with the first fourth conversion gas 21 to obtain crude hydrogen.

[0028] The isothermal conversion furnace 11 is provided with a heat exchange tube bundle, and the boiler water in the drum 12 enters the isothermal conversion furnace 11 through natural circulation to take away the reaction heat, while producing 1.3-2.0 MPa (G) medium and low pressure saturated steam as a by-product.

[0029] The medium and low pressure saturated steam with a by-product of 1.3-2.0 MPa (G) from the medium and low pressure steam generator Ⅰ7 and the steam drum 12 is mixed and sent to the medium and low pressure steam superheater 6, and is superheated to 250℃-300℃ and then sent to downstream users.

[0030] The crude gas heater 3 is connected in parallel with a temperature regulating sub-line, on which a temperature control valve 8 is provided for regulating the temperature of the crude gas leaving the crude gas heater 3 .

[0031] A temperature regulating sub-line is connected in parallel to the medium and low pressure steam generator Ⅰ7, and a temperature control valve 19 is provided on the temperature regulating sub-line for regulating the temperature of the first conversion gas output from the medium and low pressure steam generator Ⅰ7.

[0032] A temperature regulating sub-line is connected in parallel to the medium and low pressure steam generator II9, and a temperature control valve 20 is provided on the temperature regulating sub-line for regulating the temperature of the second conversion gas out of the medium and low pressure steam generator II9.

[0033] The first conversion gas from the medium and low pressure steam generator Ⅰ7 is divided into two streams. The first conversion gas 15 to the isothermal conversion furnace 11 is provided with a flow meter and a flow control valve 2 for distributing the flow of the first conversion gas. The second conversion gas 16 to the second conversion furnace 8 is provided with a valve 1 on its pipeline.

[0034] A valve three is provided on the pipeline of the third fourth conversion gas 17 from the outlet of the isothermal conversion furnace 11 to the low-temperature conversion furnace.

[0035] Compared with the prior art, the beneficial effects of the utility model are:

[0036] 1. The isothermal shift furnace and the adiabatic shift furnace are organically combined to form a dual-loop CO shift hydrogen production system, namely: an adiabatic shift furnace loop and an isothermal shift furnace loop. The two CO shift loops can be flexibly switched during the production process according to the production conditions of the device, are easy to operate, and are suitable for a variety of working conditions.

[0037] 2. The isothermal conversion furnace circuit is put into use for normal production, and the adiabatic conversion furnace circuit is used as a backup circuit. When the isothermal conversion furnace leaks, the production line will be switched to the adiabatic conversion furnace circuit. The inspection and maintenance of the isothermal conversion furnace will not affect the continuous operation of the device.

[0038] 3. When the activity of the isothermal shift catalyst decreases and the CO concentration out of the device exceeds the standard, the low-temperature shift furnace is connected in series downstream of the isothermal shift furnace to extend the service life of the isothermal shift catalyst while ensuring the CO conversion rate.

[0039] 4. When the isothermal shift catalyst is completely deactivated, the ordering, production, transportation and loading of new catalysts all take time. During this period, the isothermal shift furnace can be removed from the system and the adiabatic shift loop can be used to maintain normal production of the device.

[0040] 5. When the activities of the isothermal shift catalyst and the adiabatic shift catalyst are reduced and the CO concentration out of the device exceeds the standard, the isothermal shift loop and the adiabatic shift loop are put into use at the same time, with each loop taking 50% of the load. The CO conversion rate is increased by reducing the space velocity of the catalyst to ensure that the CO concentration does not exceed the standard, thereby extending the service life of the catalyst and reducing the operating costs of the device.

[0041] 6. When the coal gasification, acid gas removal, ammonia synthesis and other devices are expanded and transformed, and the production capacity is increased by 40% to 60%, the CO conversion device does not need to be modified at all, and the production requirements can be met by putting the two conversion loops into use at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of a double-loop CO conversion hydrogen production system in Example 1 of the utility model;

[0043] Among them, 1-crude coal gas, 2-crude coal gas separator, 3-crude coal gas heater; 4-detoxification tank; 5-first shift furnace, 6-medium and low pressure steam superheater, 7-medium and low pressure steam generator I, 8-second shift furnace, 9-medium and low pressure steam generator II, 10-low temperature shift furnace, 11-isothermal shift furnace, 12-steam drum, 13-medium pressure boiler water preheater, 14-low pressure steam generator, 15-first first shift gas, 16-second first shift gas 16, 17-third fourth shift gas, 18-temperature control valve, 19-temperature control valve, 20-temperature control valve, 21-first fourth shift gas, 22-second fourth shift gas;

[0044] Valve 1 to valve 8 are cut-off valve control valves. DETAILED DESCRIPTION

[0045] The present invention is further described below in conjunction with specific embodiments, but does not constitute any limitation to the present invention.

[0046] Embodiments 1-4 of the present invention correspond to four working conditions, as shown in Table 1:

[0047] Table 1

[0048]

[0049]

[0050] Example 1

[0051] Combination Figure 1 As shown, close valve 1, valve 3, valve 5, and valve 7. Open valve 2, valve 4, valve 6, and valve 8.

[0052] The raw coal gas 1 with a temperature of 217°C and 3.86MPa(G) from the water-coal slurry gasification device enters the raw coal gas separator 2. After the condensate is separated, the raw coal gas is heated to 265°C by the raw coal gas heater 3 and then enters the detoxification tank 4. After the dust and other impurities are removed by the detoxification tank 4, the raw coal gas enters the first conversion furnace 5. The first conversion gas with a temperature of 450°C from the first conversion furnace 5 enters the medium-low pressure steam superheater 6, superheats the medium-low pressure saturated steam of 1.6MPa(G) to 280°C, and the temperature of the first conversion gas is reduced to 395°C. It then enters the raw coal gas heater 3 to heat the raw coal gas, and the temperature of the first conversion gas is reduced to 340°C. It then enters the medium-low pressure steam generator Ⅰ7, and produces 1.6MPa(G) medium-low pressure saturated steam as a byproduct. After the temperature of the first conversion gas is reduced to 250°C, it enters the isothermal conversion furnace 11 through the flow control valve 2. The CO concentration of the fourth shift gas at the outlet of the isothermal shift furnace 11 is reduced to 0.4% (V%), and the temperature is 215°C, and then it is divided into two streams. The first stream of the fourth shift gas 21 enters the medium-pressure boiler water preheater 13, preheats the boiler water of 104°C and 3.0MPa (G) to 180°C, and then is sent to the medium-low pressure steam generator Ⅰ7, the medium-low pressure steam generator Ⅱ9 and the steam drum 12 respectively to produce 1.6MPa (G) of medium-low pressure saturated steam, and the temperature of the first stream of the fourth shift gas is reduced to 175°C. The second stream of the fourth shift gas 22 enters the low-pressure steam generator 14, and produces 0.5MPa (G) of low-pressure saturated steam, and the temperature of the second stream of the fourth shift gas is reduced to 175°C, and is mixed with the first stream of the fourth shift gas 21 to obtain crude hydrogen.

[0053] The isothermal conversion furnace 11 is provided with a heat exchange tube bundle, and the boiler water in the drum 12 enters the isothermal conversion furnace 11 through natural circulation to take away the reaction heat, while producing 1.6MPa(G) medium and low pressure saturated steam as a by-product.

[0054] The medium and low pressure saturated steam of 1.6 MPa (G) produced by the medium and low pressure steam generator Ⅰ7 and the steam drum 12 is mixed and sent to the medium and low pressure steam superheater 6, and then sent to the downstream users after being superheated to 280℃.

[0055] The crude gas heater 3 is connected in parallel with a temperature regulating sub-line, on which a temperature control valve 8 is provided for regulating the temperature of the crude gas leaving the crude gas heater 3 .

[0056] A temperature regulating sub-line is connected in parallel to the medium and low pressure steam generator Ⅰ7, and a temperature control valve 19 is provided on the temperature regulating sub-line for regulating the temperature of the first conversion gas output from the medium and low pressure steam generator Ⅰ7.

[0057] Example 2

[0058] Combination Figure 1 As shown, close valve 2, valve 3, valve 4, valve 6, and valve 8. Open valve 1, valve 5, and valve 7.

[0059] The raw gas 1 at 217°C and 3.86MPa(G) from the water-coal slurry gasification device enters the raw gas separator 2. After the condensate is separated, the raw gas is heated to 265°C by the raw gas heater 3 and then enters the detoxification tank 4. After the dust and other impurities are removed by the detoxification tank 4, the raw gas enters the first conversion furnace 5. The first conversion gas at a temperature of 450°C exiting the first conversion furnace 5 enters the medium-low pressure steam superheater 6, superheating the medium-low pressure saturated steam of 1.6MPa(G) to 280°C, and the temperature of the first conversion gas is reduced to 395°C. The raw gas enters the raw gas heater 3 to heat the raw gas, and the temperature of the first conversion gas is reduced to 340°C. The raw gas enters the medium-low pressure steam generator I7, and produces 1.6MPa(G) of medium-low pressure saturated steam as a by-product. After the temperature of the first conversion gas drops to 250°C, it enters the second conversion furnace 8 through valve 1. The second conversion gas with a temperature of 265°C at the second conversion furnace 8 enters the medium-low pressure steam generator II9, and produces 1.6MPa (G) of medium-low pressure saturated steam. After the temperature of the second conversion gas drops to 215°C, it enters the low-temperature conversion furnace 10. The CO concentration of the conversion gas at the outlet of the low-temperature conversion furnace 10 is reduced to 0.4% (V%), and the temperature is 220°C. It is then divided into two streams. The first stream, the fourth conversion gas 21, enters the medium-pressure boiler water preheater 13, preheats the boiler water of 104°C and 3.0MPa (G) to 180°C, and then is sent to the medium-low pressure steam generator I7, the medium-low pressure steam generator II9, and the steam drum 12 to produce 1.6MPa (G) of medium-low pressure saturated steam. The temperature of the first stream, the fourth conversion gas 21, drops to 175°C. The second fourth conversion gas 22 enters the low-pressure steam generator 14, and produces 0.5 MPa (G) of low-pressure saturated steam as a by-product. The temperature of the second fourth conversion gas 22 drops to 175°C, and is mixed with the first fourth conversion gas 21 to obtain crude hydrogen.

[0060] The medium and low pressure saturated steam with a by-product of 1.6 MPa (G) from medium and low pressure steam generators Ⅰ7 and Ⅱ9 is mixed and sent to medium and low pressure steam superheater 6, and then sent to downstream users after being superheated to 280℃.

[0061] The crude gas heater 3 is connected in parallel with a temperature regulating sub-line, on which a temperature control valve 8 is provided for regulating the temperature of the crude gas leaving the crude gas heater 3 .

[0062] A temperature regulating sub-line is connected in parallel to the medium and low pressure steam generator Ⅰ7, and a temperature control valve 19 is provided on the temperature regulating sub-line for regulating the temperature of the first conversion gas output from the medium and low pressure steam generator Ⅰ7.

[0063] A temperature regulating sub-line is connected in parallel to the medium and low pressure steam generator II9, and a temperature control valve 20 is provided on the temperature regulating sub-line for regulating the temperature of the second conversion gas out of the medium and low pressure steam generator II9.

[0064] Example 3

[0065] Combination Figure 1As shown, close valve 1, valve 4, and valve 7. Open valve 2, valve 3, valve 5, valve 6, and valve 8.

[0066] The raw coal gas 1 with a temperature of 217°C and 3.86MPa(G) from the water-coal slurry gasification device enters the raw coal gas separator 2. After the condensate is separated, the raw coal gas is heated to 265°C by the raw coal gas heater 3 and then enters the detoxification tank 4. After the dust and other impurities are removed by the detoxification tank 4, the raw coal gas enters the first conversion furnace 5. The temperature of the first conversion gas out of the first conversion furnace 5 is 450°C. The first conversion gas enters the medium-low pressure steam superheater 6, superheating the medium-low pressure saturated steam of 1.6MPa(G) to 280°C, and the temperature of the first conversion gas is reduced to 395°C. Then, the raw coal gas enters the raw coal gas heater 3 to heat the raw coal gas, and the temperature of the first conversion gas is reduced to 340°C. Then, the raw coal gas enters the medium-low pressure steam generator Ⅰ7, and the medium-low pressure saturated steam of 1.6MPa(G) is produced as a byproduct. After the temperature of the first conversion gas is reduced to 250°C, it enters the isothermal conversion furnace 11 through the flow control valve 2. The temperature of the fourth shift gas at the outlet of the isothermal shift furnace 11 is 215°C. It enters the low-temperature shift furnace 10 through the shift gas pipeline 17 and the valve 3. The CO concentration of the third shift gas at the outlet of the low-temperature shift furnace 10 is reduced to 0.4% (V%) and the temperature is 220°C. It is then divided into two streams. The first stream of the fourth shift gas 21 enters the medium-pressure boiler water preheater 13, preheats the boiler water of 104°C and 3.0MPa (G) to 180°C, and then is sent to the medium-low pressure steam generator I7, the medium-low pressure steam generator II9 and the drum 12 to produce 1.6MPa (G) medium-low pressure saturated steam. The temperature of the first stream of the fourth shift gas 21 is reduced to 175°C. The second stream of the fourth shift gas 22 enters the low-pressure steam generator 14, produces 0.5MPa (G) low-pressure saturated steam as a by-product, and the temperature of the second stream of the fourth shift gas is reduced to 175°C. After mixing with the first stream of the fourth shift gas 21, crude hydrogen is obtained.

[0067] The isothermal conversion furnace 11 is provided with a heat exchange tube bundle, and the boiler water in the drum 12 enters the isothermal conversion furnace 11 through natural circulation to take away the reaction heat, while producing 1.6MPa(G) medium and low pressure saturated steam as a by-product.

[0068] The medium and low pressure saturated steam of 1.6 MPa (G) produced by the medium and low pressure steam generator Ⅰ7 and the steam drum 12 is mixed and sent to the medium and low pressure steam superheater 6, and then sent to the downstream users after being superheated to 280℃.

[0069] The crude gas heater 3 is connected in parallel with a temperature regulating sub-line, on which a temperature control valve 8 is provided for regulating the temperature of the crude gas leaving the crude gas heater 3 .

[0070] A temperature regulating sub-line is connected in parallel to the medium and low pressure steam generator Ⅰ7, and a temperature control valve 19 is provided on the temperature regulating sub-line for regulating the temperature of the first conversion gas output from the medium and low pressure steam generator Ⅰ7.

[0071] Example 4

[0072] Combination Figure 1 As shown, close valve three, and open valves one, two, four, five, six, seven, and eight.

[0073] The raw coal gas 1 with a temperature of 217°C and 3.86MPa(G) from the water-coal slurry gasification device enters the raw coal gas separator 2. After the condensate is separated, the raw coal gas is heated to 265°C by the raw coal gas heater 3 and then enters the detoxification tank 4. After the dust and other impurities are removed by the detoxification tank 4, the raw coal gas enters the first conversion furnace 5. The first conversion gas with a temperature of 450°C from the first conversion furnace 5 enters the medium-low pressure steam superheater 6, superheats the medium-low pressure saturated steam of 1.6MPa(G) to 280°C, and the temperature of the first conversion gas is reduced to 395°C. It then enters the raw coal gas heater 3 to heat the raw coal gas, and the temperature of the first conversion gas is reduced to 340°C. It then enters the medium-low pressure steam generator Ⅰ7, and produces 1.6MPa(G) medium-low pressure saturated steam as a byproduct. The first conversion gas is divided into two streams after the temperature drops to 250°C. The first stream of the first conversion gas enters the isothermal conversion furnace 11 through the flow control valve 2. The CO concentration of the fourth shift gas at the outlet of the isothermal shift furnace 11 is reduced to 0.4% (V%) and the temperature is 220°C.

[0074] The second first conversion gas enters the second conversion furnace 8 through valve 1. The second conversion gas with a temperature of 265°C at the second conversion furnace 8 enters the medium-low pressure steam generator II9, and produces 1.6MPa (G) of medium-low pressure saturated steam. The second conversion gas temperature drops to 215°C and enters the low-temperature conversion furnace 10. The CO concentration of the third conversion gas at the outlet of the low-temperature conversion furnace 10 is reduced to 0.4% (V%) and the temperature is 220°C. The third conversion gas is mixed with the fourth conversion gas and then divided into two streams. The first fourth conversion gas 21 enters the medium-pressure boiler water preheater 13, preheats the boiler water of 104°C and 3.0MPa (G) to 180°C, and then is sent to the medium-low pressure steam generator I7, the medium-low pressure steam generator II9, and the steam drum 12 to produce 1.6MPa (G) of medium-low pressure saturated steam. The temperature of the first fourth conversion gas drops to 175°C. The second fourth conversion gas 22 enters the low-pressure steam generator 14, and produces 0.5 MPa (G) of low-pressure saturated steam as a by-product. The temperature of the second fourth conversion gas is reduced to 175°C, and is mixed with the first fourth conversion gas 21 to obtain crude hydrogen.

[0075] The isothermal conversion furnace 11 is provided with a heat exchange tube bundle, and the boiler water in the drum 12 enters the isothermal conversion furnace 11 through natural circulation to take away the reaction heat, while producing 1.6MPa(G) medium and low pressure saturated steam as a by-product.

[0076] The medium and low pressure saturated steam of 1.6 MPa (G) produced by the medium and low pressure steam generator Ⅰ7 and the steam drum 12 is mixed and sent to the medium and low pressure steam superheater 6, and then sent to the downstream users after being superheated to 280℃.

[0077] The crude gas heater 3 is connected in parallel with a temperature regulating sub-line, on which a temperature control valve 8 is provided for regulating the temperature of the crude gas leaving the crude gas heater 3 .

[0078] A temperature regulating sub-line is connected in parallel to the medium and low pressure steam generator Ⅰ7, and a temperature control valve 19 is provided on the temperature regulating sub-line for regulating the temperature of the first conversion gas output from the medium and low pressure steam generator Ⅰ7.

[0079] A temperature regulating sub-line is connected in parallel to the medium and low pressure steam generator II9, and a temperature control valve 20 is provided on the temperature regulating sub-line for regulating the temperature of the second conversion gas out of the medium and low pressure steam generator II9.

[0080] The flow rates of the two first conversion gases are distributed by adjusting the opening of the second flow control valve.

[0081] Comparative Example 1

[0082] Taking CN 111115574 B as a comparative example, it adopts water-coal slurry gasification to produce gas, and the supporting ammonia synthesis device has a production capacity of 1600 tons of ammonia / day. The effective gas (H 2 +CO) is about 132,800 Nm 3 / h, pressure 3.86MPaG, temperature 217℃, CO concentration 49.5% (dry basis V%). Under this benchmark, the CO conversion hydrogen production technology supporting water-coal slurry gasification is compared, see Table 2.

[0083] Table 2

[0084]

[0085]

[0086] Compared with Comparative Example 1, when the isothermal conversion loop is used alone, Example 1 is used to produce hydrogen.

[0087] The comparative example uses a double-drum isothermal conversion furnace, which is equivalent to a medium-temperature conversion furnace and a low-temperature conversion furnace in series. Only one isothermal conversion furnace is needed to meet the production requirements. The isothermal conversion furnace of Example 1 is equivalent to a low-temperature conversion furnace. Therefore, a medium-temperature conversion furnace needs to be added before the isothermal conversion furnace.

[0088] Compared with comparative example 1, the adiabatic shift loop of comparative example 2 can only produce synthesis gas. The adiabatic shift loop of embodiment 2 is used to produce hydrogen.

[0089] The comparative isothermal conversion process is adopted to produce hydrogen to produce synthetic ammonia. When the isothermal conversion furnace leaks and causes the device to shut down, for a device with a production capacity of 1,600 tons / day of synthetic ammonia, the average price of ammonia per ton is calculated at 3,500 yuan (average price in 2023). The economic loss of the device being shut down for one day is 1,600×3,500 / 10,000=5.6 million yuan / day.

[0090] Compared with Comparative Example 1, in Example 3, since only one isothermal shift furnace is provided in the comparative example, when the isothermal shift catalyst is partially deactivated, causing the CO concentration at the outlet of the device to increase from 0.4% to more than 0.5%, there are two solutions: one is to replace the isothermal shift catalyst to ensure that the CO concentration does not exceed the standard; the other is to continue production and allow the CO concentration to exceed the standard.

[0091] Example 3: The low-temperature shift furnace is switched to the isothermal shift furnace loop and connected in series downstream of the isothermal shift furnace for production. Under the premise that the isothermal shift furnace does not replace the catalyst, the outlet CO concentration can still be guaranteed to be less than 0.4%.

[0092] Isothermal shift catalyst loading 165m 3 The average price of catalyst is RMB 60,000 / m 3 The design service life is 4 years, the catalyst purchase cost is 9.9 million yuan, and the average annual cost is 2.475 million yuan. By switching the low-temperature conversion furnace to the isothermal conversion furnace loop for production, the service life of the isothermal conversion catalyst can be extended to 5 years, and the average annual cost is 1.98 million yuan, which is equivalent to saving 495,000 yuan in catalyst usage fees each year.

[0093] Without replacing the catalyst of the isothermal shift furnace, the CO concentration in the shift gas leaving the shift device is reduced from 0.5% (V%) to the design value of 0.4% (V%). When the CO concentration is reduced by 0.1% (V%), the ammonia synthesis loop can increase ammonia production by 2.97 tons per day. The annual operation time of the device is calculated as 333 days, and the price of ammonia per ton is calculated as 3,500 yuan (the average price in 2023), the annual efficiency increase is 2.97×333×3500 / 10,000=3.4615 million yuan.

[0094] Compared with Comparative Example 1, the isothermal shift loop of Example 4 is used to produce hydrogen, and the adiabatic shift loop is used to produce synthesis gas. Both the isothermal shift loop and the adiabatic shift loop of Example 4 are used to produce hydrogen.

[0095] The catalyst loading amount of each shift converter of the CO shift unit supporting the 1600 tons / day ammonia synthesis unit is shown in Table 3:

[0096] Table 3

[0097] Serial number Device Name <![CDATA[Catalyst loading amount (m 3 )]]> 1 Isothermal conversion furnace 165 2 First conversion furnace 92 3 Second conversion furnace 64 4 Low temperature conversion furnace 80

[0098] When the isothermal shift catalyst, the second shift catalyst and the low-temperature shift catalyst have reached the end of their service life and are partially deactivated, and the CO outlet concentration of the single-loop production exceeds the standard, the two shift loops are put into use at the same time, and the CO conversion rate is guaranteed by reducing the space velocity of the catalyst to meet the production requirements and extend the service life of the catalyst.

[0099] The average price of catalyst is RMB 60,000 / m 3 The loading amounts of isothermal shift catalyst, second shift catalyst and low temperature shift catalyst are 165m3 respectively. 3 、64m 3 、80m 3 The design service life is 4 years, the total purchase cost of the catalyst is 18.54 million yuan, and the average annual cost is 4.635 million yuan. When the service life of the isothermal shift catalyst, the second shift catalyst and the low-temperature shift catalyst is extended to 5 years, the average annual cost is 3.708 million yuan, which is equivalent to an annual cost saving of 927,000 yuan.

[0100] For a synthetic ammonia plant with a production capacity of 1,600 tons / day, when the coal gasification, acid gas removal, ammonia synthesis and other plants are expanded and modified, and the production capacity is increased by 40% to 60%, the CO conversion unit does not need to be modified at all, and the production requirements can be met by putting the two conversion loops into use at the same time.

[0101] In summary, the functions described in Examples 1-4 of the present invention are not available in Comparative Example 1.

[0102] Comparative Example 2

[0103] Taking the "Exploration of Isothermal Shift Technology to Replace Traditional Shift Process" as a comparative example, it uses water-coal slurry gasification to make gas, and the supporting synthetic ammonia unit has a production capacity of 1,600 tons of ammonia / day. The effective gas (H 2 +CO) is about 132,800 Nm 3 / h, pressure 3.86MPaG, temperature 217℃, CO concentration 49.5% (dry basis V%). Under this benchmark, the CO conversion hydrogen production technology supporting water-coal slurry gasification is compared, see Table 4.

[0104] Table 4

[0105]

[0106]

[0107] Example 1 compared with Comparative Example 2

[0108] Similarities: When the isothermal conversion loop is put into use, it is used to produce hydrogen. When an isothermal conversion furnace has an accident, the isothermal conversion furnace can be cut out of the system and replaced by the adiabatic conversion loop for production. The device will not be shut down due to an accident in the isothermal conversion furnace, affecting the continuous production of the device.

[0109] Differences: In comparative example 2, the isothermal conversion furnace is connected in series between the medium temperature conversion and the low temperature conversion, and the process flow is set as double medium temperature conversion + isothermal conversion + double low temperature conversion. When the isothermal conversion furnace is cut out of the system, the process flow becomes double medium temperature conversion + double low temperature conversion.

[0110] Comparative Example 2 Disadvantages: When the isothermal shift furnace is put into use, although there is no reaction in the two low-temperature shift furnaces, the shift gas still has to pass through the two low-temperature shift furnaces. The pressure drop of each low-temperature shift furnace is calculated as 0.03MPa, and the pressure drop of the two low-temperature shift furnaces is 0.06MPa in total. For a synthetic ammonia device with a production capacity of 1,600 tons / day, for every 0.1MPa reduction in the pressure drop of the CO shift device, the medium-pressure steam consumption of the ammonia synthesis gas compressor is reduced by about 0.29 tons per hour. The annual operation time of the device is calculated as 8,000 hours, and 1,392 tons of medium-pressure steam is saved each year. The medium-pressure steam is calculated at 230 yuan / ton. The annual operating cost of the ammonia synthesis gas compressor due to the extra consumption of medium-pressure steam is about 320,200 yuan.

[0111] In Example 1, when the isothermal conversion furnace is put into use, the process flow is set as one medium-temperature conversion + one isothermal conversion, which is three fewer conversion furnaces than in Comparative Example 2. The device investment is relatively small, and the annual operating cost is reduced by at least 320,200 yuan, with obvious energy-saving and consumption-reducing effects.

[0112] Example 2 compared with Comparative Example 2

[0113] In Comparative Example 2, when the isothermal conversion furnace is cut out from the system, the process flow becomes double medium-temperature conversion + double low-temperature conversion.

[0114] In Example 2, when the isothermal conversion furnace is cut out of the system, the process flow becomes double medium temperature conversion + low temperature conversion. There is one less conversion furnace than in Comparative Example 2. The device investment is small and the system pressure drop is low.

[0115] Example 3 compared with Comparative Example 2

[0116] In Example 3, only when the activity of the isothermal conversion catalyst decreases and the CO concentration at the outlet of the device exceeds the standard, the low-temperature conversion furnace is connected in series downstream of the isothermal conversion furnace for use, which can not only ensure that the CO concentration exceeds the standard, but also extend the service life of the isothermal conversion catalyst. The low-temperature conversion furnace can freely switch between the isothermal conversion loop and the adiabatic conversion loop according to the use of the isothermal conversion catalyst, and has good operational flexibility. The process flow of Comparative Example 2 does not have this function.

[0117] Example 4 compared with Comparative Example 2

[0118] Since the process flow of Comparative Example 2 is a single conversion loop, it does not have the function of using two loops at the same time.

[0119] Compared with Comparative Example 2, Example 4 has the following advantages:

[0120] The isothermal shift loop and the adiabatic shift loop of Example 4 are both used to produce hydrogen.

[0121] The catalyst loading amount of each shift converter of the CO shift unit supporting the 1600 tons / day ammonia synthesis unit is shown in Table 5:

[0122] Table 5

[0123] Serial number Device Name <![CDATA[Catalyst loading amount (m 3 )]]> 1 Isothermal conversion furnace 165 2 First conversion furnace 92 3 Second conversion furnace 64 4 Low temperature conversion furnace 80

[0124] When the isothermal shift catalyst, the second shift catalyst and the low-temperature shift catalyst have reached the end of their service life and are partially deactivated, and the CO outlet concentration of the single-loop production exceeds the standard, the two shift loops are put into use at the same time, and the CO conversion rate is guaranteed by reducing the space velocity of the catalyst to meet the production requirements and extend the service life of the catalyst.

[0125] The average price of catalyst is RMB 60,000 / m 3 The loading amounts of isothermal shift catalyst, second shift catalyst and low temperature shift catalyst are 165m3 respectively. 3 、64m 3 、80m 3 The design service life is 4 years, the total purchase cost of the catalyst is 18.54 million yuan, and the average annual cost is 4.635 million yuan. When the service life of the isothermal shift catalyst, the second shift catalyst and the low-temperature shift catalyst is extended to 5 years, the average annual cost is 3.708 million yuan, which is equivalent to an annual cost saving of 927,000 yuan.

[0126] For a synthetic ammonia plant with a production capacity of 1,600 tons / day, when the coal gasification, acid gas removal, ammonia synthesis and other plants are expanded and modified, and the production capacity is increased by 40% to 60%, the CO conversion unit does not need to be modified at all, and the production requirements can be met by putting the two conversion loops into use at the same time.

[0127] In summary, the functions described in Examples 1-4 of the present invention are not available in Comparative Example 2 either.

[0128] In summary, in the dual-loop CO conversion hydrogen production process of the utility model, the isothermal conversion furnace loop is put into use in normal production, and the adiabatic conversion furnace loop is used as a backup loop. When the isothermal conversion furnace leaks, it can switch to the adiabatic conversion loop to continue production. When the isothermal conversion catalyst and the adiabatic conversion catalyst are both partially deactivated and the CO concentration out of the device exceeds the standard, the isothermal conversion loop and the adiabatic conversion loop are put into use at the same time, and the CO concentration is ensured not to exceed the standard by reducing the space velocity of the catalyst, thereby extending the service life of the catalyst and reducing the operating cost of the device.

[0129] The above is only a preferred embodiment of the utility model. All equivalent changes and modifications made according to the scope of the patent application of the utility model shall be within the scope of the patent of the utility model. Any numerical value mentioned in the utility model, if there is only an interval of two units between any minimum value and any maximum value, includes all values ​​that increase by one unit each time from the minimum value to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is declared to be 50-90, in this specification it means that 51-89, 52-88... and 69-71 and 70-71 are specifically listed. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 can be appropriately considered as a unit. These are just some specially specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0130] It should be noted that the embodiments described above are only used to explain the utility model and do not constitute any limitation to the utility model. The utility model is described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The utility model may be modified as specified within the scope of the claims of the utility model, and the utility model may be revised without departing from the scope and spirit of the utility model. Although the utility model described therein involves specific methods, materials and embodiments, it does not mean that the utility model is limited to the specific examples disclosed therein. On the contrary, the utility model can be extended to all other methods and applications with the same functions.

Claims

1. A dual-loop CO2 shift hydrogen production system, characterized in that: The system comprises an adiabatic conversion circuit and an isothermal conversion circuit; the adiabatic conversion circuit and the isothermal conversion circuit share a first conversion furnace (5), a low-pressure steam generator (14), and a medium-pressure boiler water preheater (13); The adiabatic conversion circuit and the isothermal conversion circuit each independently include a medium-low pressure steam generator I (7); the medium-low pressure steam generator I (7) generates medium-low pressure saturated steam.

2. The system according to claim 1, characterized in that The isothermal conversion circuit further comprises an isothermal conversion furnace (11) and a steam drum (12); the isothermal conversion furnace is connected upstream to the steam drum to remove the reaction heat and generate medium-low pressure saturated steam; wherein the isothermal conversion furnace (11) is connected in series with the medium-low pressure steam generator I (7) and shares an upstream medium-low pressure steam superheater (6), superheating the medium-low pressure saturated steam and delivering it to downstream users.

3. The system according to claim 2, characterized in that The isothermal conversion circuit further comprises a raw gas separator (2), a raw gas heater (3), a detoxification tank (4), a first conversion furnace (5), a medium- and low-pressure steam superheater (6), a medium- and low-pressure steam generator I (7), a medium-pressure boiler water preheater (13), and a low-pressure steam generator (14).

4. The system according to claim 3, characterized in that The raw coal gas heater (3) and the medium and low pressure steam generator I (7) are each independently provided with a temperature regulating sub-line; and a temperature control valve is provided on the temperature regulating sub-line.

5. The system according to claim 2, characterized in that The adiabatic conversion circuit further comprises a second conversion furnace (8) and a low-temperature conversion furnace (10); The low-temperature conversion furnace (10) is used in series downstream of the isothermal conversion furnace (11), or the low-temperature conversion furnace (10) and the isothermal conversion furnace (11) are used in parallel.

6. The system according to claim 5, characterized in that The adiabatic conversion circuit further comprises a raw gas separator (2), a raw gas heater (3), a detoxification tank (4), a first conversion furnace (5), a medium-low pressure steam superheater (6), a medium-low pressure steam generator I (7), a medium-low pressure steam generator II (9), a medium-pressure boiler water preheater (13), and a low pressure steam generator (14).

7. The system according to claim 6, characterized in that The raw coal gas heater (3) and the medium and low pressure steam generator II (9) are each independently provided with a temperature regulating sub-line; and a temperature control valve is provided on the temperature regulating sub-line.

8. The system according to claim 5, characterized in that The system also includes valve one, valve two, valve three, valve four, valve five, valve six, valve seven, and valve eight.

9. The system according to claim 8, characterized in that When the valves 1, 3, 5 and 7 are closed and the valves 2, 4, 6 and 8 are opened, the first conversion furnace (5) and the isothermal conversion furnace (11) are used in series; When the valves 2, 3, 4, 6 and 8 are closed and the valves 1, 5 and 7 are opened, the first shift converter (5), the second shift converter (8) and the low-temperature shift converter (10) are used in series; When the valves 1, 4 and 7 are closed and the valves 2, 3, 5, 6 and 8 are opened, the first shift converter (5), the isothermal shift converter (11) and the low-temperature shift converter (10) are used in series; When the valve three is closed and the valves one, two, four, five, six, seven and eight are opened, the isothermal conversion furnace (11) is used in parallel with the second conversion furnace (8) and the low-temperature conversion furnace (10).

10. The system according to claim 5, characterized in that A crossover line (17) is provided between the isothermal conversion furnace (11) and the low-temperature conversion furnace (10).

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