A solid oxide electrolysis cell system for hydrogen production using steel mill waste heat

Abstract

The application provides a solid oxide electrolytic cell system for hydrogen production by utilizing steel plant waste heat, and belongs to the technical field of hydrogen production, and solves the problems of low utilization rate of steel plant waste heat and large energy loss in the prior art. The system comprises an air blower, an electric three-way ball valve, a first heat exchanger, a three-way valve, a solid oxide electrolytic cell stack, a waste heat boiler, a steam turbine generator and an AC / DC converter. A branch of the first heat exchanger is connected with high-temperature gas or solid generated by the steel plant, and an output end of the branch is sequentially connected with electrodes of the solid oxide electrolytic cell stack through the waste heat boiler, the steam turbine generator and the AC / DC converter. An input end of the electric three-way ball valve is connected with the air blower, an output end one of the electric three-way ball valve is connected with an input end one of the three-way valve through a branch two of the first heat exchanger, and an output end two of the electric three-way ball valve is directly connected with an input end two of the three-way valve. An output end of the three-way valve is connected with an air side inlet of the solid oxide electrolytic cell stack. The steel plant waste heat is utilized to provide preheated air and power supply for the electrolytic cell stack.

Description

TECHNICAL FIELD

[0001] The present application relates to the hydrogen production technology field, and particularly relates to a solid oxide electrolysis cell system for hydrogen production by using steel plant waste heat. BACKGROUND

[0002] The steel industry is an important foundation of the national economy and also an energy-consuming industry, and energy consumption accounts for about 15% of the total industrial energy consumption in China. A large amount of high-temperature exhaust gas and slag generated in the production process of steel has good utilization value. The high-temperature flue gas and slag can enter a waste heat recovery system, and medium and low pressure steam can be generated by a waste heat boiler and then be introduced into a steam pipe network or drive a steam turbine set to generate power, but there is a big problem of energy waste, and the medium and low pressure steam cannot be effectively utilized.

[0003] In addition, the steam production of the steel industry varies seasonally by region. The demand for steam in the heating period in winter is obviously higher than that in the non-heating period, and the waste heat recovery system is continuously operated throughout the year, and the steam demand is small in summer, which causes huge energy waste. SUMMARY

[0004] In view of the above analysis, the embodiments of the present application aim to provide a solid oxide electrolysis cell system for hydrogen production by using steel plant waste heat, so as to solve the problems of low utilization rate of steel plant waste heat and large energy loss in the prior art.

[0005] In one aspect, the embodiments of the present application provide a solid oxide electrolysis cell system for hydrogen production by using steel plant waste heat, comprising an air blower, an electric three-way ball valve, a first heat exchanger, a three-way valve, a solid oxide electrolysis cell stack, a waste heat boiler, a steam turbine generator, and an AC / DC converter; wherein,

[0006] Branch 1 of the first heat exchanger is connected to the high-temperature gas or solid generated in the steel plant, and the output end of the branch 1 is sequentially connected to the electrodes of the solid oxide electrolysis cell stack through the waste heat boiler, the steam turbine generator and the AC / DC converter, so as to provide power for the electrolysis cell stack by using the steel plant waste heat;

[0007] The input end of the electric three-way ball valve is connected to the air blower, one of the output ends is connected to one of the input ends of the three-way valve through branch 2 of the first heat exchanger, the other of the output ends is directly connected to the other of the input ends of the three-way valve, and the output end of the three-way valve is connected to the air side inlet of the solid oxide electrolysis cell stack as an air side temperature adjusting branch of the electrolysis cell stack, so as to provide preheated air for the electrolysis cell stack by using the steel plant waste heat.

[0008] The beneficial effects of the above technical solutions are as follows: The high-temperature solid oxide fuel cell generates hydrogen and oxygen by electrolyzing high-temperature water vapor, and the working temperature is generally 600-1000℃. By arranging the first heat exchanger, the high-temperature gas or solid generated by the steel plant is converted into low-temperature waste heat products, and then the waste heat is converted into electric energy for electrolysis through the waste heat boiler, steam turbine generator and AC / DC converter. At the same time, by arranging the air side temperature adjusting branch, the high-temperature waste heat of the steel plant can be effectively utilized to heat the air entering the stack and preheat the inside of the high-temperature solid oxide electrolysis cell stack. The system combines the high-temperature waste heat of the steel plant with the high-temperature solid oxide electrolysis cell stack, which can not only improve the electrolysis efficiency of the high-temperature solid oxide electrolysis cell system, but also solve the problem of energy waste in the steel plant, and the generated hydrogen can improve the efficiency of the steel plant. The whole system is safe, reliable and efficient.

[0009] Based on the further improvement of the above system, the solid oxide electrolysis cell system further comprises a system controller and a steam accumulator and a pressure reducing valve connected in sequence; wherein,

[0010] The high-temperature water vapor generated by the steel plant enters the fuel electrode side inlet of the solid oxide electrolysis cell stack through the steam accumulator and the pressure reducing valve in sequence, as the first electrolyte supply branch of the electrolysis cell stack, so that the high-temperature water vapor enters the electrolysis cell stack to generate electrolysis reaction;

[0011] The system controller is used to adjust the opening degree of the electric three-way ball valve according to the obtained air temperature entering the stack and the air temperature at one place of the input end of the three-way valve, so that the air temperature entering the stack reaches the set temperature; and adjust the opening degree of the pressure reducing valve according to the obtained water vapor pressure entering the stack, so that the water vapor pressure entering the stack reaches the set pressure.

[0012] Further, the solid oxide electrolysis cell system further comprises a steam pipe network for heating; wherein,

[0013] The high-temperature water vapor generated by the steel plant enters the steam pipe network, and the output of the steam pipe network is connected in parallel with the output of the steam accumulator and then enters the fuel electrode side inlet of the solid oxide electrolysis cell stack through the pressure reducing valve;

[0014] The system controller is further used to open the output of the steam pipe network when the water vapor pressure in the accumulator is lower than the set value, so as to supplement the water vapor pressure entering the stack.

[0015] Further, the solid oxide electrolysis cell system further comprises a water vapor flow controller and an electric heater; wherein,

[0016] The water vapor generated by the steel plant enters the fuel electrode side inlet of the solid oxide electrolysis cell stack through the steam accumulator, the pressure reducing valve, the water vapor flow controller and the electric heater in sequence;

[0017] An electric heater is used to start when the steam temperature of the water entering the stack is higher or lower than the target temperature, and to regulate the temperature of the steam entering the stack at a set cooling rate or heating rate, so as to maintain the steam entering the stack within the target temperature range at all times.

[0018] Further, the solid oxide electrolysis cell system further comprises a two-stream heat exchanger; wherein,

[0019] The two-stream heat exchanger is provided with three heat exchange branches; the input end of the first heat exchange branch is connected to the output end of the steam flow controller, and the output end of the first heat exchange branch is connected to the inlet of the electric heater; the input end of the second heat exchange branch is connected to the air side tail gas outlet of the solid oxide electrolysis cell stack; the input end of the third heat exchange branch is connected to the fuel side tail gas outlet of the solid oxide electrolysis cell stack, and the output end of the third heat exchange branch is connected to the external hydrogen storage bottle.

[0020] Further, the solid oxide electrolysis cell system further comprises a gas-water separator and a dryer; wherein,

[0021] The output end of the third heat exchange branch of the two-stream heat exchanger is connected to the external hydrogen storage bottle in sequence through the gas-water separator and the dryer.

[0022] Further, the solid oxide electrolysis cell system further comprises a steam flow controller and a second heat exchanger; wherein,

[0023] The steam generated by the steel plant is divided into two paths in sequence through the steam accumulator, the pressure reducing valve and the steam flow controller, one path enters the fuel electrode side inlet of the solid oxide electrolysis cell stack through the first branch of the second heat exchanger, and the other path enters the first branch of the first heat exchanger;

[0024] The second branch of the second heat exchanger is connected to a second fluid, and the temperature of the second fluid is set to 650-1100℃;

[0025] The system controller is also used to adjust the temperature of the second fluid according to the obtained steam temperature entering the stack and the gas temperature at the input end of the first heat exchange branch of the second heat exchanger, so that the steam temperature entering the stack reaches the set temperature.

[0026] Further, the solid oxide electrolysis cell system further comprises a water tank storing deionized water, a water pump and a water flow controller; wherein,

[0027] The first heat exchanger is provided with three heat exchange branches; the first branch is connected to the high-temperature gas or solid generated by the steel plant, and the output end of the first branch is connected to the electrode of the solid oxide electrolysis cell stack through the waste heat boiler, the steam turbine generator and the AC / DC converter in sequence; the second branch is connected to the output end one of the electric three-way ball valve, and the output end of the second branch is connected to the input end one of the three-way valve; the third branch is connected to the water tank through the water flow controller and the water pump in sequence, and the output end of the third branch is connected to the fuel electrode side inlet of the solid oxide electrolysis cell stack, serving as the second electrolyte supply branch of the electrolysis cell stack to pass the heated deionized water into the electrolysis cell stack to generate electrolysis reaction.

[0028] The water flow controller is used to obtain the target water flow into the stack according to the target current, the pre-labeled fuel utilization rate and the number of stack sheets, and then control the deionized water with the target water flow into the solid oxide electrolysis cell stack.

[0029] Further, the solid oxide electrolysis cell system further comprises a third heat exchanger; wherein,

[0030] The first branch of the third heat exchanger is connected to the second fluid with adjustable temperature; the input end of the second branch is connected to the output end of the third branch of the first heat exchanger, and the output end of the second branch is connected to the fuel electrode side inlet of the solid oxide electrolysis cell stack.

[0031] Further, the system controller executes the following program:

[0032] Start the air blower and the electric three-way ball valve.

[0033] Obtain the air temperature into the stack and the air temperature at the input end one of the three-way valve, and then adjust the opening of the electric three-way ball valve to make the air temperature into the stack reach the set temperature, so as to preheat the inside of the solid oxide electrolysis cell stack.

[0034] Start the electric heater, the pressure reducing valve and the water vapor flow controller.

[0035] Control the mixed gas of nitrogen and hydrogen to pass through the fuel electrode side of the solid oxide electrolysis cell stack, and control the electric heater to heat the electrolysis cell stack to the target temperature at the set heating rate.

[0036] After the heating is completed, control the high-temperature water vapor generated by the steel plant to pass through the fuel electrode side of the solid oxide electrolysis cell stack, and start the waste heat boiler and the steam turbine generator to perform electrolysis.

[0037] Obtain the water vapor pressure in the regenerator, and when the water vapor pressure in the regenerator is lower than the set value, open the output of the steam pipe network to supplement the water vapor pressure into the stack, otherwise, close the output of the steam pipe network.

[0038] The water vapor pressure entering the stack is obtained, and the pressure reducing valve opening degree is adjusted according to the obtained water vapor pressure entering the stack, so that the water vapor pressure entering the stack reaches the set pressure.

[0039] The fuel electrode outlet gas of the solid oxide electrolysis cell stack is subjected to gas-water separation, drying, and hydrogen storage.

[0040] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0041] 1. The water vapor generated by the steel plant is changed into sustainable steam after passing through the steam accumulator.

[0042] 2. In order to further utilize the exhaust heat of the stack, the stack air side exhaust gas and the fuel gas side exhaust gas pass through two flow heat exchangers to increase the temperature of the water vapor entering the stack.

[0043] 3. The electric heater works in the heating / cooling stage, and is raised / lowered to the working temperature according to the temperature rise / fall speed of the stack; in the discharging heat absorption stage of the solid oxide fuel cell stack, the electric heater works to maintain the working temperature of the stack; in the heat release stage, the temperature of the stack air side exhaust gas and the fuel gas side exhaust gas is high and the flow is large, and the electric heater can not work.

[0044] 4. The air side is provided with air flow by the air blower, and exchanges heat with the high-temperature gas or solid of the steel plant; after heat exchange, the high-temperature flue gas is discharged into the waste heat boiler to generate steam to drive the steam turbine generator to generate electricity.

[0045] 5. The grid or steam turbine generator generates electricity to provide electrolysis power for the high-temperature solid oxide electrolysis cell stack.

[0046] 6. The electric heater is omitted to adjust the temperature of the high-temperature water vapor through the second fluid.

[0047] 7. The high-temperature water vapor can also not be used, and the high-temperature flue gas and waste heat of the steel plant are directly used to provide heat for air and water, the water is changed into high-temperature superheated water vapor, and the air is changed into high-temperature air, the electric heater is omitted, and the safety hazard can be eliminated.

[0048] 8. The high-temperature waste heat and the high, medium and low temperature waste heat steam of the steel plant can be effectively utilized to improve the waste heat utilization of the steel plant, and the generated hydrogen can improve the efficiency of the steel plant.

[0049] The summary section is provided to introduce a selection of concepts in a simplified form, which will be further described in the detailed description below. The summary section is not intended to identify key or essential features of the disclosure, nor is it intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0050] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like parts throughout the several views.

[0051] Figure 1 A solid oxide electrolysis cell system configuration schematic diagram for utilizing steel plant waste heat to produce hydrogen is shown in Example 1;

[0052] Figure 2 A solid oxide electrolysis cell system configuration schematic diagram for utilizing steel plant waste heat to produce hydrogen is shown in Example 2;

[0053] Figure 3 A solid oxide electrolysis cell system configuration schematic diagram for utilizing steel plant waste heat to produce hydrogen is shown in Example 3;

[0054] Figure 4 A solid oxide electrolysis cell system configuration schematic diagram for utilizing steel plant waste heat to produce hydrogen is shown in Example 4.

[0055] Reference Signs:

[0056] T1 - air temperature at one of the input ends of the three-way valve; T2 - air temperature entering the stack;

[0057] T3 - temperature at the input end of the branch of the second heat exchanger; T4 - steam temperature entering the stack. DETAILED DESCRIPTION

[0058] Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0059] As used herein, the term "includes" and its variants are meant to be construed as encompassing rather than excluding other items. Unless specifically stated otherwise, the term "or" as used herein refers to "and / or". The term "based on" means "based, at least in part, on". The term "one example embodiment" and "an embodiment" means "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", and the like, do not imply significance or order, but rather are used to distinguish one element from another. Other explicit or implicit definitions can also be included below.

[0060] Example 1

[0061] One embodiment of the present disclosure discloses a solid oxide electrolysis cell system for utilizing steel plant waste heat to produce hydrogen, as shown in Figure 1The system shown includes an air blower, an electric three-way ball valve, a first heat exchanger, a three-way valve, a solid oxide electrolysis cell stack, a waste heat boiler, a steam turbine generator, and an AC / DC converter.

[0062] The branch of the first heat exchanger is connected to high-temperature gas or solid generated in a steel plant (i.e. high-temperature exhaust gas and slag, and the steel plant has a large amount of high-temperature flue gas and solid waste heat, with a temperature of 650-1100℃), and the output end of the branch is sequentially connected to the electrode of the solid oxide electrolysis cell stack via the waste heat boiler, the steam turbine generator, and the AC / DC converter, so as to provide power for the electrolysis cell stack by using the waste heat of the steel plant.

[0063] The input end of the electric three-way ball valve is connected to the air blower, the output end one of the electric three-way ball valve is connected to the input end one of the three-way valve via the branch two of the first heat exchanger, the output end two of the electric three-way ball valve is directly connected to the input end two of the three-way valve, and the output end of the three-way valve is connected to the air side inlet of the solid oxide electrolysis cell stack, as an air side temperature adjusting branch of the electrolysis cell stack, so as to provide preheated air for the electrolysis cell stack by using the waste heat of the steel plant.

[0064] The high-temperature solid oxide fuel cell system further includes a nitrogen gas supply system and a hydrogen gas supply system, which are not involved in the improvement of the present application, Figure 1 which are not shown and can be understood by those skilled in the art.

[0065] In implementation, the steel plant generates a large amount of high-temperature gas or solid, and the waste heat mainly includes dry quenching waste heat (application product of dry quenching technology), sintering ring cooling waste heat (application product of sintering ring cooling waste heat power generation technology), converter gas waste heat (application product of converter gas vaporization cooling system), electric furnace flue gas waste heat (application product of electric furnace flue gas waste heat recovery system), and heating furnace flue gas waste heat (application product of heating furnace vaporization cooling system). After the first heat exchanger, the temperature of the high-temperature gas or solid is generally 175-450℃, and the pressure is 0.8MPa-3.82MPa. The high-temperature flue gas generated in the steel production process is used to generate medium and low pressure superheated steam through the waste heat boiler, to drive the steam turbine generator to generate power and provide power for the electrolysis cell stack, and the electric three-way ball valve is used to distribute the flow into the first heat exchanger (high-temperature heat exchanger), so that the air after heat exchange is mixed with the normal temperature air, so as to adjust the temperature at the outlet of the three-way valve (air temperature entering the stack).

[0066] Compared with the prior art, the solid oxide electrolysis cell system provided by the embodiment combines the high-temperature waste heat of the steel plant with the high-temperature solid oxide electrolysis cell stack, can improve the electrolysis efficiency of the solid oxide electrolysis cell system, can solve the problem of energy waste of the steel plant, and can improve the efficiency of the steel plant by using the generated hydrogen. The whole system is safe, reliable and efficient. The high-temperature solid oxide fuel electrolysis cell generates hydrogen and oxygen by electrolyzing high-temperature steam, and the working temperature is generally 600-1000℃. By arranging the first heat exchanger, the high-temperature gas or solid generated by the steel plant is converted into low-temperature waste heat, and then the waste heat is converted into electric energy for electrolysis by the waste heat boiler, the steam turbine generator and the AC / DC converter. At the same time, by arranging the air side temperature adjusting branch, the high-temperature waste heat of the steel plant can be effectively utilized to heat the air entering the stack and preheat the inside of the high-temperature solid oxide electrolysis cell stack.

[0067] Embodiment 2

[0068] On the basis of embodiment 1, the solid oxide electrolysis cell system is further provided with a power grid system interface.

[0069] One end of the power grid system interface is connected to an external power grid system, and the other end is connected to the electrode of the solid oxide electrolysis cell stack through an AC / DC converter. The electricity in the power grid and the electricity generated by the steam turbine generator are all converted into direct current by the AC / DC converter and then applied to the stack, and the stack electrolyzes water into oxygen and hydrogen.

[0070] Preferably, the solid oxide electrolysis cell system further comprises a steam accumulator, a steam pipe network, a pressure reducing valve, a water vapor flow controller, an electric heater, a two-stream heat exchanger, as shown in Figure 2 , and a system controller.

[0071] The high-temperature steam generated by the steel plant is introduced into the steam pipe network for heating users. The steam pipe network can be arranged at a place where heating is needed.

[0072] The high-temperature steam generated by the steel plant is sequentially introduced into the steam accumulator, connected in parallel with the output of the steam pipe network, sequentially passes through the pressure reducing valve, the water vapor flow controller, the heat exchanger branch one of the two-stream heat exchanger and the electric heater, and then enters the fuel electrode side inlet of the solid oxide electrolysis cell stack as the first electrolyte supply branch of the electrolysis cell stack, so as to introduce the high-temperature steam into the electrolysis cell stack to generate electrolysis reaction.

[0073] It should be noted that the high-temperature steam generated by the steel plant includes dry quenching coke waste heat steam, sinter ring cooling waste heat steam, converter gas waste heat steam, electric furnace flue gas waste heat steam and heating furnace flue gas waste heat steam.

[0074] a system controller, for adjusting the opening of the electric three-way ball valve according to the obtained inlet air temperature T2 and the air temperature T1 at one of the input ends of the three-way valve, so that the inlet air temperature T2 reaches the set temperature; and for adjusting the opening of the pressure reducing valve according to the obtained inlet water vapor pressure, so that the inlet water vapor pressure reaches the set pressure; and for monitoring the water vapor pressure in the regenerator, and when the water vapor pressure in the regenerator is lower than the set value, opening the output of the steam pipe network to supplement the inlet water vapor pressure.

[0075] an electric heater, for starting when the inlet water vapor temperature T4 is higher or lower than the target temperature, and for temperature regulation of the inlet water vapor at a set temperature decreasing rate or temperature increasing rate, so that the inlet water vapor is always within the target temperature range. In the electric pile temperature increasing stage, the electric heater increases the inlet water vapor to the working temperature at a set temperature increasing rate, and in the electric pile temperature decreasing stage, the electric heater decreases the inlet water vapor to the working temperature at a set temperature decreasing rate.

[0076] The two-stream heat exchanger is provided with three heat exchange branches; the input end of the heat exchange branch one is connected to the output end of the water vapor flow controller, and the output end of the heat exchange branch one is connected to the inlet of the electric heater; the input end of the heat exchange branch two is connected to the air side tail gas outlet of the solid oxide electrolysis cell stack, and the input end of the heat exchange branch three is connected to the fuel gas side tail gas outlet of the solid oxide electrolysis cell stack, and the output end of the heat exchange branch three is connected to the external hydrogen storage bottle. The high-temperature tail gas discharged from the electric pile air side and fuel gas side is further used to increase the temperature of the water vapor through the two-stream heat exchanger, thereby improving the efficiency of the system.

[0077] a water vapor flow controller, for calculating the required water vapor flow according to the target current, the fuel utilization rate calibrated in advance and the number of electric pile pieces, so as to control the output of the water vapor flow to meet the electrolysis demand.

[0078] Preferably, the solid oxide electrolysis cell system further comprises a gas-water separator and a dryer. The output end of the heat exchange branch three of the two-stream heat exchanger is sequentially connected to the external hydrogen storage bottle through the gas-water separator and the dryer.

[0079] Preferably, the system controller executes the following program:

[0080] S1. Start the air blower and the electric three-way ball valve;

[0081] S2. Obtain the inlet air temperature T2 and the air temperature T1 at one of the input ends of the three-way valve, and then adjust the opening of the electric three-way ball valve, so that the inlet air temperature T2 reaches the set temperature, and the internal part of the solid oxide electrolysis cell stack is preheated (since the working temperature of the solid oxide fuel electrolysis cell stack is high, it needs to be preheated first);

[0082] S3. Start the electric heater, the pressure reducing valve and the water vapor flow controller;

[0083] S4. Control the fuel electrode side of the solid oxide electrolysis cell stack to pass in a mixed gas of nitrogen and hydrogen, and control the electric heater to heat the electrolysis cell stack to a target temperature at a set heating rate;

[0084] S5. After heating is completed, control the fuel electrode side of the solid oxide electrolysis cell stack to pass in high-temperature steam generated by the steel plant, and start the waste heat boiler and steam turbine generator to perform electrolysis (the electrolysis stage directly uses the waste heat steam generated by the steel plant, and the discontinuous steam is converted into continuous saturated superheated steam through the steam accumulator to output);

[0085] S6. Obtain the water vapor pressure in the accumulator, and when the water vapor pressure in the accumulator is lower than a set value, open the output of the steam pipe network to supplement the water vapor pressure into the stack, otherwise close the output of the steam pipe network (so that when the accumulator pressure is too low, it can be supplemented through the steam pipe network);

[0086] S7. Obtain the water vapor pressure into the stack, and adjust the opening degree of the pressure reducing valve according to the obtained water vapor pressure T4 into the stack to make the water vapor pressure into the stack reach a set pressure (reduce the steam pressure through the pressure reducing valve);

[0087] S8. Perform gas-water separation, drying, and hydrogen storage on the fuel electrode outlet gas of the solid oxide electrolysis cell stack.

[0088] Preferably, when the stack tail gas outlet temperature reaches the stack operating temperature, the electric heater does not need to work, and when the stack tail gas outlet temperature is lower than the stack operating temperature, the electric heater works.

[0089] In implementation, the gas at the fuel side outlet of the stack is exchanged with the two-flow exchanger, and then is subjected to gas-water separation, drying, and storage, and the stored hydrogen can be used as clean energy to improve the economic benefits of the steel plant. In order to control the heating / cooling rate, the flow is divided at the electric three-way ball valve in the air side, a part of the flow is exchanged with the waste heat of the steel plant, and the other part of the flow is mixed at the three-way valve to adjust the inlet temperature of the air side of the stack, and the opening degree of the electric three-way ball valve is adjusted through the change of T2 temperature, when T2 temperature is high, the electric three-way ball valve flow direction and the side of the high-temperature source exchange are reduced, and when T2 temperature is low, the electric three-way ball valve flow direction and the side of the high-temperature source exchange are increased. High-temperature waste flue gas or high-temperature solid is used to generate steam through the waste heat boiler, and the steam drives the steam turbine generator to generate electricity. The electricity in the power grid is converted into direct current through the AC / DC converter to act on the stack, and the stack electrolyzes water into oxygen and hydrogen. The steam of the steel plant is used to provide continuous fuel for the solid oxide fuel cell, and the waste heat of the steel plant can be used to preheat the air, so that the air side electric heater is omitted, the energy consumption is reduced, and the efficiency is improved.

[0090] Compared with the prior art, the solid oxide electrolysis cell system provided by the embodiment has the following beneficial effects:

[0091] 1. The water vapor generated by the steel plant becomes sustainable steam after passing through the steam accumulator.

[0092] 2. In order to further utilize the heat discharged by the stack tail gas, the stack air side tail gas and the fuel gas side tail gas pass through two flow exchangers to increase the temperature of the water vapor entering the stack.

[0093] 3. The electric heater is controlled to work in the temperature rising / dropping stage, and is raised / lowered to the working temperature according to the temperature rising / dropping speed requirement of the stack; in the discharging heat absorption stage of the solid oxide fuel cell stack, the electric heater works to maintain the working temperature of the stack; in the discharging heat stage, the electric heater can not work because the temperature of the stack air side tail gas and the fuel gas side tail gas is high and the flow is large.

[0094] 4. The air side is provided with air flow by the air blower, and the air flow exchanges heat with the high-temperature gas or solid of the steel plant; after the heat exchange, the high-temperature flue gas is discharged into the waste heat boiler to generate steam to drive the steam turbine generator to generate electricity.

[0095] 5. The grid or the steam turbine generator generates electricity to provide electrolysis power for the high-temperature solid oxide electrolysis cell stack.

[0096] Embodiment 3

[0097] On the basis of Embodiment 1, the solid oxide electrolysis cell system further includes a steam accumulator, a steam pipe network, a pressure reducing valve, a water vapor flow controller, a second heat exchanger, and a system controller, in addition to the grid system interface in Embodiment 2, as shown in Figure 3 .

[0098] The high-temperature water vapor generated by the steel plant passes through the steam accumulator in sequence, is connected in parallel with the output of the steam pipe network, and then passes through the pressure reducing valve, the water vapor flow controller, and the heat exchange branch one of the second heat exchanger in sequence to enter the fuel electrode side inlet of the solid oxide electrolysis cell stack, as the first electrolyte supply branch of the electrolysis cell stack, for passing the high-temperature water vapor into the electrolysis cell stack to generate electrolysis reaction.

[0099] Preferably, the output of the water vapor flow controller is divided into two paths, one of which enters the electrolyte inlet of the solid oxide electrolysis cell stack through the branch one of the second heat exchanger, and the other of which enters the branch one of the first heat exchanger.

[0100] The branch two of the second heat exchanger is connected to the second fluid, and the temperature of the second fluid is set to 650-1100℃. By controlling the flow and temperature of the second fluid, the inlet temperature of the fuel gas side of the stack is adjusted through heat exchange with the water vapor, and the system safety is improved because there is no electric heater in the whole system.

[0101] The system controller is configured to adjust the opening of the electric three-way ball valve according to the obtained air temperature T2 at the inlet of the stack and the air temperature T1 at one end of the three-way valve, so that the air temperature T2 at the inlet of the stack reaches the set temperature; adjust the opening of the pressure reducing valve according to the obtained steam pressure at the inlet of the stack, so that the steam pressure at the inlet of the stack reaches the set pressure; monitor the steam pressure in the regenerator, and when the steam pressure in the regenerator is lower than the set value, open the output of the steam pipe network to supplement the steam pressure at the inlet of the stack; and adjust the temperature and flow rate of the second fluid according to the obtained steam temperature T4 at the inlet of the stack and the gas temperature T3 at the input end of the heat exchange branch of the second heat exchanger, so that the steam temperature T4 at the inlet of the stack reaches the set temperature.

[0102] Preferably, the solid oxide electrolysis cell system further comprises an electric heater. It is worth noting that the electric heater is a non-essential component of the system.

[0103] The electric heater is configured to be started when the steam temperature T4 at the inlet of the stack is higher or lower than the target temperature, and to adjust the temperature of the steam at the inlet of the stack at a set temperature decreasing rate or increasing rate, so as to maintain the steam at the inlet of the stack within the target temperature range. In the heating stage of the electric pile, the electric heater increases the steam at the inlet of the stack to the working temperature at a set increasing rate, and in the cooling stage of the electric pile, the electric heater decreases the steam at the inlet of the stack to the working temperature at a set decreasing rate.

[0104] Preferably, the solid oxide electrolysis cell system further comprises a gas-water separator and a dryer. The output end of the heat exchange branch three of the two-stream heat exchanger is sequentially connected to the gas-water separator, the dryer, and then to the external hydrogen storage bottle.

[0105] Compared with the prior art, the system of the embodiment has the following beneficial effects:

[0106] 1. The steam generated by the steel plant becomes sustainable steam after passing through the steam regenerator.

[0107] 2. The electric heater is omitted, and the temperature of the high-temperature steam is adjusted by the second fluid.

[0108] 3. An electric heater can also be added, and the electric heater is controlled to work in the heating / cooling stage to increase / decrease to the working temperature according to the temperature increasing / decreasing rate of the electric pile; in the discharging heat absorption stage of the solid oxide fuel cell electric pile, the electric heater works to maintain the working temperature of the electric pile; in the heat release stage, the tail gas temperature on the air side and the tail gas temperature on the gas side are high and the flow rate is large, and the electric heater can not work.

[0109] 4. The air side is provided with air flow by a blower, and the air flow exchanges heat with the high-temperature gas or solid of the steel plant; after the heat exchange, the high-temperature flue gas is discharged into the waste heat boiler to generate steam to drive the steam turbine generator to generate electricity.

[0110] 5. The power grid or steam turbine generator generates electricity to provide electrolysis power for the solid oxide electrolysis cell stack.

[0111] Embodiment 4

[0112] The solid oxide electrolysis cell system is improved on the basis of Embodiment 1, and further comprises a water tank storing deionized water, a water pump, a water flow controller, a third heat exchanger, and a system controller.

[0113] The first heat exchanger is provided with three heat exchange branches; among them, the branch one is connected to the high-temperature gas or solid generated by the steel plant, and the output end of the branch one is connected to the electrode of the solid oxide electrolysis cell stack in sequence through the waste heat boiler, the steam turbine generator, and the AC / DC converter; the branch two is connected to the output end one of the electric three-way ball valve at the input end, and the input end one of the three-way valve at the output end; the branch three is connected to the water tank through the water flow controller and the water pump at the input end, and is connected to the fuel electrode side inlet of the solid oxide electrolysis cell stack at the output end, serving as the second electrolyte supply branch of the electrolysis cell stack to pass the heated deionized water into the electrolysis cell stack for electrolysis reaction.

[0114] The water flow controller is used to derive the target water flow into the stack according to the target current, the fuel utilization rate calibrated in advance, and the number of stack sheets, and further control the deionized water with the target water flow into the solid oxide electrolysis cell stack.

[0115] The branch one of the third heat exchanger is connected to the second fluid with adjustable temperature; the input end of the branch two is connected to the output end of the branch three of the first heat exchanger, and the output end of the branch two is connected to the fuel electrode side inlet of the solid oxide electrolysis cell stack.

[0116] The system controller is used to control the start of the water pump, the water flow controller, the air blower, the electric three-way ball valve, the waste heat boiler, and the steam turbine generator.

[0117] Preferably, the solid oxide electrolysis cell system can further comprise the water vapor supply branch of Embodiment 2 or 3 into the stack to make the temperature rising speed faster.

[0118] The system controller is used to adjust the opening of the electric three-way ball valve according to the obtained air temperature T2 into the stack and the air temperature T1 at the input end one of the three-way valve, so that the air temperature into the stack reaches the set temperature; and adjust the temperature of the second fluid (which can be determined by laboratory calibration) according to the obtained temperature at the input end of the branch two of the third heat exchanger and the temperature of the deionized water into the stack.

[0119] In implementation, the water pump delivers the deionized water in the water tank into the pipeline, the water flow controller obtains the target water flow into the stack (the required water flow) according to the target current, the fuel utilization rate calibrated in advance, and the number of stack sheets, and becomes superheated steam after heat exchange with the high-temperature waste heat of the steel plant, and reaches the working temperature of the stack after heat exchange by the second fluid regulating temperature.

[0120] Compared with the prior art, the system of the embodiment has the following beneficial effects:

[0121] 1. The air side is provided with air flow by the air blower, and heat exchanged with the high-temperature gas or solid of the steel plant, and the high-temperature flue gas after heat exchange is discharged into the waste heat boiler to generate steam to drive the steam turbine generator to generate electricity.

[0122] 2. The power grid or the steam turbine generator generates electricity to provide electrolysis power for the high-temperature solid oxide electrolysis cell stack.

[0123] 3. The high-temperature water vapor can not be used, and the high-temperature flue gas and waste heat of the steel plant can be directly used to provide heat for air and water, the water is changed into high-temperature superheated steam, and the air is changed into high-temperature air, the electric heater is omitted, and the safety hazard can be eliminated.

[0124] The above has described the embodiments of the present disclosure, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical application, or improvement of the prior art of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A solid oxide electrolytic cell system for producing hydrogen using waste heat from a steel plant, characterized in that, This includes an air blower, an electric three-way ball valve, a first heat exchanger, a three-way valve, a solid oxide electrolysis cell stack, a waste heat boiler, a steam turbine generator, an AC / DC converter, and an electric heater; among which, The first branch of the heat exchanger is connected to the high-temperature gas or solid generated by the steel plant. The output end of the first branch is connected to the electrodes of the solid oxide electrolytic cell stack via the waste heat boiler, the steam turbine generator, and the AC / DC converter in sequence, so as to use the waste heat of the steel plant to provide power to the electrolytic cell stack. The input end of the electric three-way ball valve is connected to the air blower. Its output end one is connected to the input end one of the three-way valve via the branch two of the first heat exchanger. Its output end two is directly connected to the input end two of the three-way valve. The output end of the three-way valve is connected to the air-side inlet of the solid oxide electrolytic cell stack, serving as the air-side temperature regulating branch of the electrolytic cell stack. The electric heater is used to start when the temperature of the steam entering the reactor is higher or lower than the target temperature, and to regulate the temperature of the steam entering the reactor according to the set cooling or heating rate, so as to keep the steam entering the reactor always within the target temperature range.

2. The solid oxide electrolytic cell system for producing hydrogen using waste heat from a steel plant according to claim 1, characterized in that, It also includes a system controller and a steam accumulator and a pressure reducing valve connected in sequence; among which, The high-temperature steam generated by the steel plant enters the fuel electrode side inlet of the solid oxide electrolytic cell stack via a steam accumulator and a pressure reducing valve, serving as the first electrolyte supply branch of the electrolytic cell stack to allow the high-temperature steam to be introduced into the electrolytic cell stack to undergo an electrolytic reaction. The system controller is used to adjust the opening of the electric three-way ball valve according to the acquired feed air temperature and the air temperature at one input terminal of the three-way valve so that the feed air temperature reaches the set temperature; and to adjust the opening of the pressure reducing valve according to the acquired feed steam pressure so that the feed steam pressure reaches the set pressure.

3. The solid oxide electrolytic cell system for producing hydrogen using waste heat from a steel plant according to claim 2, characterized in that, It also includes a steam network for heating; among which, High-temperature steam generated by the steel plant is fed into the steam pipeline network. The output of the steam pipeline network is connected in parallel with the output of the steam accumulator and then enters the fuel electrode side inlet of the solid oxide electrolytic cell stack through a pressure reducing valve. The system controller is also used to open the output of the steam network to supplement the steam pressure entering the reactor when the steam pressure in the accumulator is lower than the set value.

4. The solid oxide electrolytic cell system for producing hydrogen from waste heat in a steel plant according to claim 2 or 3, characterized in that, It also includes a steam flow controller; among which, The steam generated by the steel plant passes through a steam accumulator, a pressure reducing valve, a steam flow controller, and an electric heater before entering the fuel electrode inlet of the solid oxide electrolytic cell stack.

5. The solid oxide electrolytic cell system for producing hydrogen using waste heat from a steel plant according to claim 4, characterized in that, It also includes a two-stream heat exchanger; among which, The two-stream heat exchanger has three heat exchange branches; the input end of heat exchange branch one is connected to the output end of the steam flow controller, and the output end of heat exchange branch one is connected to the inlet of the electric heater; the input end of heat exchange branch two is connected to the air-side exhaust gas outlet of the solid oxide electrolysis cell stack; the input end of heat exchange branch three is connected to the gas-side exhaust gas outlet of the solid oxide electrolysis cell stack, and the output end of heat exchange branch three is connected to the external hydrogen storage cylinder.

6. The solid oxide electrolytic cell system for producing hydrogen using waste heat from a steel plant according to claim 5, characterized in that, It also includes gas-liquid separators and dryers; among which, The output end of heat exchange branch three of the two-stream heat exchanger passes through a gas-liquid separator and a dryer in sequence before being connected to an external hydrogen storage cylinder.

7. The solid oxide electrolytic cell system for producing hydrogen from waste heat in a steel plant according to claim 3, characterized in that, It also includes a steam flow controller and a second heat exchanger; among which, The steam generated in the steel plant passes through a steam accumulator, a pressure reducing valve, and a steam flow controller in sequence, and is then divided into two paths. One path enters the fuel electrode side inlet of the solid oxide electrolysis cell stack through the branch of the second heat exchanger, and the other path enters the branch of the first heat exchanger. The second heat exchanger is connected to a second fluid in its second branch, and the temperature of the second fluid is set to 650~1100℃. The system controller is also used to adjust the temperature of the second fluid based on the acquired steam temperature entering the reactor and the gas temperature at the input end of the heat exchange branch of the second heat exchanger, so that the steam temperature entering the reactor reaches the set temperature.

8. The solid oxide electrolytic cell system for producing hydrogen from waste heat in a steel plant according to any one of claims 1, 2, 3, 5, 6, and 7, characterized in that, It also includes a water tank for storing deionized water, a water pump, and a water flow controller; among which, The first heat exchanger has three heat exchange branches. Branch one is connected to the high-temperature gas or solid generated by the steel plant, and its output is connected to the electrode of the solid oxide electrolytic cell stack via a waste heat boiler, a steam turbine generator, and an AC / DC converter. Branch two is connected to the output of an electric three-way ball valve and the input of a three-way valve. Branch three is connected to a water tank via a water flow controller and a water pump, and its output is connected to the fuel electrode inlet of the solid oxide electrolytic cell stack, serving as the second electrolyte supply branch for the electrolytic cell stack, so that heated deionized water can be introduced into the electrolytic cell stack to undergo an electrolytic reaction. A water flow controller is used to determine the target feed water flow rate based on the target current, pre-calibrated fuel utilization rate, and number of stack plates, and then controls the output of deionized water at the target feed water flow rate to the solid oxide electrolyzer stack.

9. The solid oxide electrolytic cell system for producing hydrogen from waste heat in a steel plant according to claim 8, characterized in that, It also includes a third heat exchanger; among which, The third heat exchanger has a branch line 1 through which a second fluid with adjustable temperature is introduced; the input end of its branch line 2 is connected to the output end of the branch line 3 of the first heat exchanger, and the output end of its branch line 2 is connected to the fuel electrode side inlet of the solid oxide electrolytic cell stack.

10. The solid oxide electrolysis cell system for producing hydrogen from waste heat in a steel plant according to claim 5 or 6, characterized in that, The system controller executes the following program: Start the air blower and the electric three-way ball valve; The temperature of the incoming air and the air temperature at one input end of the three-way valve are obtained, and then the opening of the electric three-way ball valve is adjusted so that the temperature of the incoming air reaches the set temperature, so as to preheat the inside of the solid oxide electrolytic cell stack. Start the electric heater, pressure reducing valve, and steam flow controller; A mixture of nitrogen and hydrogen gas is introduced into the fuel electrode side of the solid oxide electrolytic cell stack, and the electric heater is controlled to heat the electrolytic cell stack to the target temperature at a set heating rate. After heating is completed, high-temperature steam generated by the steel plant is introduced into the fuel electrode side of the solid oxide electrolysis cell stack, and the waste heat boiler and steam turbine generator are started to carry out electrolysis. The steam pressure inside the accumulator is obtained. When the steam pressure inside the accumulator is lower than the set value, the output of the steam pipeline is turned on to supplement the steam pressure entering the reactor; otherwise, the output of the steam pipeline is turned off. Obtain the incoming steam pressure and adjust the opening of the pressure reducing valve according to the obtained incoming steam pressure so that the incoming steam pressure reaches the set pressure; The gas exiting the fuel electrode of a solid oxide electrolytic cell stack is subjected to gas-water separation, drying, and hydrogen storage.

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