Novel SOFC-GT cycle energy system for coupling reforming hydrogen production and control method

Abstract

The invention discloses a novel SOFC-GT cycle energy system for coupling reforming hydrogen production and a control method. By arranging the front combustion chamber and the high-temperature heat exchanger, flexible temperature control of an SOFC inlet working medium is achieved, and the SOFC load response speed and variable load operation stability are improved; the flue gas temperature of the hot side outlet end of the high-temperature heat exchanger and the working medium temperature of the cold side outlet end of the high-temperature heat exchanger are controlled by adjusting the fuel quantity in a front combustion chamber and controlling the flue gas temperature of an outlet of the front combustion chamber, meanwhile, heat exchanger assemblies are arranged around the SOFC, and part of the flue gas of the hot side outlet end of the high-temperature heat exchanger is introduced into the heat exchanger assemblies around the SOFC; therefore, the working temperature of the SOFC in the variable load process is adjusted; by adjusting the methane flow control valve and the flue gas flow control valve, the flue gas temperature and the flue gas flow for heat exchange with the SOFC are controlled, and therefore it is guaranteed that when the load of the SOFC changes, the working temperature is kept stable, and the operation stability of the overall variable load of the coupling energy system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coupling power generation technology, and in particular to a novel SOFC-GT cycle energy system coupled with reforming hydrogen production and a control method. BACKGROUND

[0002] As a kind of high-temperature fuel cell, the working temperature of solid oxide fuel cell (SOFC) is usually about 950 DEG C. Higher working temperature can make hydrocarbon fuel realize reforming in the interior of the cell, so as to simplify the whole power generation system, reduce initial cost, improve power generation efficiency, and the tail gas waste heat temperature of SOFC is high, which can be combined with other power devices to form a combined power cycle, so as to further improve power generation capacity and efficiency. SOFC has the advantage of high efficiency, but the load response is slow, while gas turbine has the characteristics of flexible load response, but the efficiency is lower than that of SOFC of the same power level. SOFC-gas turbine coupling cycle power generation system (SOFC-GT) can improve the response flexibility and efficiency. However, the current SOFC-GT coupling cycle system is still in the research and development stage, and there are problems that the two subsystems are difficult to couple control in energy flow and mass flow, and difficult to respond in time. SUMMARY

[0003] The present application aims to at least solve one of the technical problems in the related art to some extent.

[0004] To this end, an embodiment of the present application proposes a novel SOFC-GT cycle energy system coupled with reforming hydrogen production and a control method.

[0005] In one aspect, the present application proposes a novel SOFC-GT cycle energy system coupled with reforming hydrogen production, comprising:

[0006] A pre-combustion chamber, in which methane and hot compressed air are burned to form high-temperature flue gas;

[0007] A pre-reformer, in which pre-reforming reaction is carried out on methane and turbine exhaust gas heated by the high-temperature flue gas to produce hydrogen;

[0008] A SOFC, in which internal reforming reaction is carried out on hydrogen and hot compressed air to produce electric energy, and part of the high-temperature flue gas after heat exchange is led to the SOFC to adjust the temperature of the SOFC;

[0009] A post-combustion chamber, in which tail gas of the SOFC enters the post-combustion chamber for hydrogen supplement combustion;

[0010] A turbine, in which outlet flue gas of the post-combustion chamber enters the turbine for expansion work, and turbine exhaust gas provides heat source for compressed air;

[0011] The controller controls the flow rates of methane, hydrogen, and high-temperature flue gas after heat exchange based on the temperature of the SOFC.

[0012] In some embodiments, a regenerator is also included, wherein compressed air entering the cold side of the regenerator exchanges heat with turbine exhaust entering the hot side of the regenerator.

[0013] In some embodiments, the hot air from the cold-side outlet of the regenerator is divided into three paths and enters the pre-combustion chamber, the post-combustion chamber, and the SOFC, respectively.

[0014] In some embodiments, a first high-temperature heat exchanger is further included, wherein the turbine exhaust gas at the hot side outlet end of the regenerator enters the cold side of the first heat exchanger and exchanges heat with the high-temperature flue gas entering the hot side of the first high-temperature heat exchanger.

[0015] In some embodiments, a second high-temperature heat exchanger is further included, wherein methane enters the cold side of the second high-temperature heat exchanger and exchanges heat with the high-temperature flue gas entering the hot side of the second high-temperature heat exchanger.

[0016] In some embodiments, a methane cylinder is also included, wherein the methane at the outlet end of the methane cylinder enters the cold side of the second high-temperature heat exchanger and the pre-combustion chamber, respectively, and a methane flow control valve is provided on the outlet pipeline of the methane cylinder.

[0017] In some embodiments, a portion of the high-temperature flue gas after heat exchange in the first and second high-temperature heat exchangers is used for heating, and a portion is introduced into the SOFC. A flue gas flow control valve is installed on the main pipeline where the hot-side outlet flow path of the first and second high-temperature heat exchangers intersects.

[0018] In some embodiments, hydrogen from the outlet of the pre-reformer enters the hydrogen storage cylinder and the SOFC via pipelines, respectively, and a hydrogen flow control valve is provided at the outlet of the pre-reformer.

[0019] In some embodiments, a temperature sensor is provided in the SOFC, and the temperature sensor, the methane flow control valve, the flue gas flow control valve, and the hydrogen flow control valve are all electrically connected to the controller.

[0020] On the other hand, this invention proposes a control method for a novel SOFC-GT cycle energy system coupled with reforming for hydrogen production, comprising the following steps:

[0021] When the SOFC load increases or decreases, the controller adjusts the methane flow control valve to increase or decrease the methane flow into the pre-combustion chamber and determines whether the SOFC operating temperature is stable. If the SOFC operating temperature is stable, the adjustment ends. If the SOFC operating temperature is unstable, the controller continues to increase or decrease the methane flow into the pre-combustion chamber and determines whether the methane flow control valve has reached its limit.

[0022] If the methane flow control valve does not reach its limit, the flow rate of methane entering the pre-combustion chamber will continue to increase or decrease until the SOFC operating temperature stabilizes. If the SOFC operating temperature is unstable when the methane flow control valve reaches its limit, the controller will adjust the flue gas flow control valve to decrease or increase the flow rate of flue gas entering the SOFC until the SOFC operating temperature stabilizes.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] The system of the present invention improves the overall response speed, overall operational stability and efficiency of the system, while also having heating capacity.

[0025] This invention achieves flexible temperature control of the SOFC inlet working fluid by setting up a pre-combustion chamber and a high-temperature heat exchanger, thereby improving the SOFC load response speed and variable load operation stability.

[0026] This invention controls the flue gas temperature at the outlet of the pre-combustion chamber by adjusting the amount of fuel in the pre-combustion chamber, thereby controlling the flue gas temperature at the hot side outlet of the high-temperature heat exchanger and the working fluid temperature at the cold side outlet. At the same time, a heat exchanger assembly is set around the SOFC, and a portion of the flue gas at the hot side outlet of the high-temperature heat exchanger is introduced into the heat exchanger assembly around the SOFC, thereby adjusting the operating temperature of the SOFC during the variable load process.

[0027] This invention controls the flue gas temperature and the flow rate of the flue gas exchanging heat with the SOFC by adjusting the methane flow control valve and the flue gas flow control valve, thereby ensuring that the SOFC maintains a stable operating temperature when the load changes, and improving the overall operational stability of the coupled energy system under varying loads. Attached Figure Description

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0029] Figure 1 This is a schematic diagram of the novel SOFC-GT cycle energy system for hydrogen production coupled with reforming according to the present invention.

[0030] Figure 2 This is a flowchart of the control method for the novel SOFC-GT cycle energy system coupled with reforming for hydrogen production according to the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Compressor; 2. Turbine; 3. Regenerator; 4. First high-temperature heat exchanger; 5. Pre-combustion chamber; 6. Methane cylinder; 7. Second high-temperature heat exchanger; 8. Pre-reformer; 9. SOFC; 10. Hydrogen storage cylinder; 11. Post-combustion chamber; 12. Methane flow control valve; 13. Flue gas flow control valve; 14. Hydrogen flow control valve. Detailed Implementation

[0033] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0034] The following description, with reference to the accompanying drawings, describes a novel SOFC-GT cycle energy system and control method for coupled reforming hydrogen production according to embodiments of the present invention.

[0035] like Figure 1 As shown, the novel SOFC-GT cycle energy system for coupled reforming hydrogen production of the present invention includes a compressor 1, a turbine 2, a regenerator 3, a first high-temperature heat exchanger 4, a pre-combustion chamber 5, a second high-temperature heat exchanger 7, a pre-reformer 8, an SOFC 9, a post-combustion chamber 11, and a controller.

[0036] Air is compressed by compressor 1 to become compressed air. In regenerator 3, the compressed air is heated to hot air by turbine exhaust. Specifically, the inlet of compressor 1 is connected to the atmosphere, and the outlet of compressor 1 is connected to the cold side inlet of regenerator 3. The compressed air enters the cold side of regenerator 3 through the cold side inlet. The outlet of turbine 2 is connected to the hot side inlet of regenerator 3. The turbine exhaust from the outlet of turbine 2 enters the hot side of regenerator 3 through the hot side inlet. In regenerator 3, the turbine exhaust on the hot side exchanges heat with the compressed air on the cold side. The compressed air, as a cold source, is heated to hot air by the turbine exhaust, which is a heat source.

[0037] After the hot air flows out from the cold side outlet of the regenerator 3, it splits into three paths and enters the pre-combustion chamber 5, the post-combustion chamber 11 and the SOFC respectively. The hot air enters the pre-combustion chamber 5 and the post-combustion chamber 11 for combustion, and the hot air enters the SOFC to participate in the chemical reaction to generate electricity.

[0038] In the pre-combustion chamber 5, methane and hot air burn to produce high-temperature flue gas, which serves as a heat source and enters the first high-temperature heat exchanger 4 and the second high-temperature heat exchanger 7. Methane comes from a methane cylinder 6, and the outlet of the methane cylinder 6 is connected to the second high-temperature heat exchanger 7 and the pre-combustion chamber 5 via pipelines. A methane flow control valve 12 is installed on the outlet pipeline of the methane cylinder 6 to regulate the flow rate of methane entering the pre-combustion chamber 5.

[0039] Specifically, the hot-side outlet of the regenerator 3 is connected to the cold-side inlet of the first high-temperature heat exchanger 4. The turbine exhaust gas from the hot-side outlet of the regenerator 3 enters the first high-temperature heat exchanger 4 through the cold-side inlet of the first high-temperature heat exchanger 4. A portion of the high-temperature flue gas generated by the pre-combustion chamber 5 enters the first high-temperature heat exchanger 4 through the hot-side inlet of the first high-temperature heat exchanger 4. The high-temperature flue gas in the first high-temperature heat exchanger 4 heats the turbine exhaust gas from the hot-side outlet of the regenerator 3. A portion of the methane from the outlet of the methane cylinder 6 enters the pre-combustion chamber 5 to participate in combustion, and a portion enters the second high-temperature heat exchanger 7 through the cold-side inlet of the second high-temperature heat exchanger 6. Another portion of the high-temperature flue gas generated by the pre-combustion chamber 5 enters the second high-temperature heat exchanger 7 through the hot-side inlet of the second high-temperature heat exchanger 7. The high-temperature flue gas in the second high-temperature heat exchanger 7 heats the methane.

[0040] Methane and turbine exhaust gas, which are heated by high-temperature flue gas respectively, undergo a pre-reforming reaction in pre-reformer 8 to produce hydrogen.

[0041] Specifically, the cold-side outlet of the first high-temperature heat exchanger 4 is connected to the inlet of the pre-reformer 8, and the cold-side outlet of the second heat exchanger is also connected to the inlet of the pre-reformer 8. Turbine exhaust gas flowing from the cold-side outlet of the first high-temperature heat exchanger 4 and methane flowing from the cold-side outlet of the second high-temperature heat exchanger 7 enter the pre-reformer 8 for a reforming reaction to produce gases including hydrogen, water vapor, methane, carbon monoxide, and carbon dioxide, with hydrogen being the primary product. The hydrogen from the outlet of the pre-reformer 8 is piped to a hydrogen storage cylinder 10 and an SOFC (SO2-to-Fuel Cell). The hydrogen undergoes internal reforming in the SOFC, where it reacts chemically with oxygen in the air to generate electricity. The hydrogen is then stored in the hydrogen storage cylinder 10 for use as supplementary fuel. A hydrogen flow control valve 14 is installed at the outlet of the pre-reformer 8 to control the flow rate of hydrogen entering the SOFC.

[0042] After heat exchange, a portion of the high-temperature flue gas is directed to the SOFC to regulate its temperature. Specifically, part of the high-temperature flue gas after heat exchange in the first high-temperature heat exchanger 4 and the second high-temperature heat exchanger 7 is used for heating, while a portion is directed to the SOFC to exchange heat with the SOFC through heat exchanger assemblies arranged around the SOFC, thereby regulating the SOFC's temperature so that it operates at a stable temperature.

[0043] A temperature sensor is installed in the SOFC to monitor the operating temperature of the SOFC in real time. A flue gas flow control valve 13 is installed on the main pipeline where the hot side outlet flow path of the first high-temperature heat exchanger 4 and the hot side outlet flow path of the second high-temperature heat exchanger 7 intersect to control the flow rate of flue gas entering the SOFC.

[0044] The exhaust gas from the SOFC enters the post-combustion chamber 11 and is supplemented by hydrogen combustion. Specifically, the outlet of the SOFC is connected to the inlet of the post-combustion chamber 11, and the outlet of the hydrogen storage cylinder 10 is connected to the inlet of the post-combustion chamber 11. In the post-combustion chamber 11, the combustion operation is performed with reference to the fuel utilization rate of the SOFC.

[0045] The flue gas from the outlet of the post-combustion chamber 11 enters the turbine 2 for expansion and does work. Specifically, the outlet end of the post-combustion chamber 11 is connected to the inlet end of the turbine 2. The flue gas generated by the combustion of SOFC exhaust gas, hydrogen and hot air in the post-combustion chamber 11 enters the turbine 2 for expansion and does work.

[0046] The temperature sensor, methane flow control valve 12, flue gas flow control valve 13, and hydrogen flow control valve 14 are all electrically connected to the controller, and the controller centrally controls the opening and closing degrees of the methane flow control valve 12, flue gas flow control valve 13, and hydrogen flow control valve 14. The controller controls the methane flow, flue gas flow, and hydrogen flow based on the temperature data from the temperature sensor. All of the above valve components are centrally controlled by the control system, and electric regulating valves are selected as the flow control valve group.

[0047] like Figure 2 As shown, the control method for a novel SOFC-GT cycle energy system coupled with reforming for hydrogen production, utilizing the system of the present invention, includes the following steps:

[0048] When the SOFC load increases or decreases, the controller adjusts the methane flow control valve 12 to increase or decrease the methane flow into the pre-combustion chamber 5 accordingly and determines whether the SOFC operating temperature is stable. If the SOFC operating temperature is stable, the adjustment ends. If the SOFC operating temperature is unstable, the controller continues to increase or decrease the methane flow into the pre-combustion chamber 5 and determines whether the methane flow control valve 12 has reached its limit.

[0049] If the methane flow control valve 12 does not reach its limit, the flow rate of methane entering the pre-combustion chamber 5 will continue to increase or decrease until the SOFC operating temperature stabilizes. If the SOFC operating temperature is unstable when the methane flow control valve 12 reaches its limit, the controller will adjust the flue gas flow control valve 13 to decrease or increase the flow rate of flue gas entering the SOFC until the SOFC operating temperature stabilizes.

[0050] Specifically, when the external load of the SOFC-GT system decreases or increases, the SOFC's operating temperature will fluctuate due to the load change. Without control, this will lead to a decrease in SOFC efficiency and lifespan. The decrease / increase in SOFC load causes a corresponding decrease / increase in SOFC operating temperature, which is transmitted by the temperature sensor to the controller. The controller receives this data signal and controls the methane flow control valve 12 to increase / decrease the methane flow into the pre-combustion chamber 5. Due to the increased / decreased fuel quantity, the flue gas temperature at the outlet of the pre-combustion chamber 5 increases / decreases. This increase / decrease in flue gas temperature at the outlet of the pre-combustion chamber 5 leads to an increase / decrease in the flue gas temperature at the hot end of the high-temperature heat exchanger and the working fluid temperature at the cold side outlet. This increase / decrease in the working fluid temperature entering the pre-reformer 8 results in increased fuel utilization during the pre-reformation process and an increased hydrogen flow at the outlet of the pre-reformer 8. The temperature of the flue gas at the outlet of the high-temperature heat exchanger increases or decreases, and it is then introduced into the SOFC for heat exchange, thereby increasing or decreasing the SOFC's operating temperature and maintaining its stability during load increases or decreases. When the methane flow control valve 12 reaches its adjustment limit and still cannot guarantee a stable SOFC operating temperature, the flue gas flow control valve 13 is adjusted to increase or decrease the flow rate of the flue gas exchanging heat with the SOFC, further stabilizing the SOFC's operating temperature.

[0051] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms may refer to different embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0053] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A novel SOFC-GT cycle energy system coupled with reforming hydrogen production, characterized in that, The system comprises: a front combustion chamber, in which methane and hot compressed air are combusted to form high-temperature flue gas; a pre-reformer, in which pre-reformed methane and turbine exhaust gas heated by the high-temperature flue gas are subjected to a pre-reforming reaction to produce hydrogen; a SOFC, in which the hydrogen and hot compressed air are subjected to an internal reforming reaction to produce electric energy, and part of the high-temperature flue gas after heat exchange is introduced into the SOFC to adjust the temperature of the SOFC; a rear combustion chamber, into which the tail gas of the SOFC is introduced for hydrogen supplement combustion; a turbine, into which the flue gas from the rear combustion chamber outlet is introduced for expansion work, and the turbine exhaust gas provides a heat source for compressed air; a controller, which controls the flow of methane, hydrogen and the high-temperature flue gas after heat exchange according to the temperature of the SOFC.

2. The system of claim 1, wherein, The system further comprises a regenerator, into which compressed air is introduced into the cold side of the regenerator and the turbine exhaust gas introduced into the hot side of the regenerator is subjected to heat exchange.

3. The system of claim 2, wherein, The hot air from the outlet end of the cold side of the regenerator is divided into three paths and introduced into the front combustion chamber, the rear combustion chamber and the SOFC, respectively.

4. The system of claim 1, wherein, The system further comprises a first high-temperature heat exchanger, into which the turbine exhaust gas from the outlet end of the hot side of the regenerator is introduced into the cold side of the first heat exchanger and subjected to heat exchange with the high-temperature flue gas introduced into the hot side of the first high-temperature heat exchanger.

5. The system of claim 1, wherein, The system further comprises a second high-temperature heat exchanger, into which methane is introduced into the cold side of the second high-temperature heat exchanger and subjected to heat exchange with the high-temperature flue gas introduced into the hot side of the second high-temperature heat exchanger.

6. The system of claim 5, wherein, The system further comprises a methane gas cylinder, into which methane from the outlet end of the methane gas cylinder is introduced into the cold side of the second high-temperature heat exchanger and the front combustion chamber, respectively, and a methane flow control valve is arranged on the outlet pipeline of the methane gas cylinder.

7. The system of claim 6, wherein, Part of the high-temperature flue gas after heat exchange in the first high-temperature heat exchanger and the second high-temperature heat exchanger is used for heating, and part of the high-temperature flue gas is introduced into the SOFC, and a flue gas flow control valve is arranged on the main pipeline where the outlet flow path of the hot side of the first high-temperature heat exchanger intersects with the outlet flow path of the hot side of the second high-temperature heat exchanger.

8. The system of claim 7, wherein, The hydrogen from the outlet end of the pre-reformer is introduced into a hydrogen storage cylinder and the SOFC through pipelines, respectively, and a hydrogen flow control valve is arranged at the outlet end of the pre-reformer.

9. The system of claim 8, wherein, A temperature sensor is arranged in the SOFC, and the temperature sensor, the methane flow control valve, the flue gas flow control valve and the hydrogen flow control valve are electrically connected to the controller.

10. A control method of a novel SOFC-GT cycle energy system coupled with a hydrogen reforming, characterized by, The system as claimed in any one of claims 1-9 comprises the following steps: When the load of the SOFC increases or decreases, the controller adjusts the methane flow control valve to increase or decrease the flow of methane into the front combustion chamber and determines whether the operating temperature of the SOFC is stable, if the operating temperature of the SOFC is stable, the adjustment is ended, if the operating temperature of the SOFC is not stable, the flow of methane into the front combustion chamber is continuously increased or decreased and it is determined whether the methane flow control valve reaches the limit; If the methane flow control valve has not reached its limit, then the methane flow into the precombustion chamber is increased or decreased until the SOFC operating temperature stabilizes. If the methane flow control valve has reached its limit and the SOFC operating temperature does not stabilize, then the controller adjusts the flue gas flow control valve to decrease or increase the flue gas flow into the SOFC until the SOFC operating temperature stabilizes.

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