System and method for improving response capability of SOFC-GT coupling power generation system

Abstract

The invention discloses a system and a method for improving response capability of an SOFC-GT coupling power generation system. According to the system, in the electric load trough period, a tail gas distribution valve of a turbine is adjusted, part of tail gas passes through a waste heat boiler of a steam turbine to generate steam, in this way, the steam amount can be reduced, the electric power of the steam turbine can be reduced, and minimum-power operation is achieved; on the contrary, in the electric load crest period, the feed water is heated and evaporated into steam through the heat storage fluid, the steam is sent to a medium-pressure cylinder or a low-pressure cylinder of the steam turbine to do work, the electric power of the combined cycle unit can be rapidly improved, and rapid peak regulation is achieved. In addition, if the unit undertakes a heat supply task at the moment, heat storage of the electric pile can be utilized for heat supply, so that the stability of heat load is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of coupled power generation, and in particular to a system and method for improving the response capability of a SOFC-GT coupled power generation system. Background Art

[0002] The impact load problem is common in distributed power generation systems. In the face of impact loads, the coupled power generation system is required to have the ability to quickly adjust the output electric power. However, the combustion mechanism of the gas turbine causes its output mechanical power to change slowly. This slow responsiveness cannot meet the requirements of the application object. Therefore, the system power balance problem caused, that is, the output power of the gas turbine does not match the rapidly changing load power, resulting in a large fluctuation in the DC bus voltage, which in turn causes the oscillation of the power conversion system, which is not conducive to the stable operation of the system. In addition, the large fluctuation of the bus voltage deteriorates the power supply quality of the system. The occurrence of such problems is related to various factors such as other power generation systems of the load power grid and its own regulation.

[0003] From the output characteristics of the SOFC stack, it can be seen that the power output from the stack is direct current, and it will fluctuate greatly due to the temperature, inlet pressure and flow of the stack, and cannot directly meet the load requirements. When using this system to generate electricity, a stable direct current is first obtained through a DC regulator DC / DC, and then the inverter DC / AC is used to convert the alternating current required by the load. The control of the working environment of the stack is mainly achieved through the control of the system auxiliary machine. When the load changes and the internal environment changes, the auxiliary machine working state is adjusted in time to meet the dynamic response of the stack.

[0004] To ensure the life of SOFC, the general design principle is to keep it running smoothly as much as possible, and the task of dynamic response is given to the gas turbine. When the gas turbine is started, it takes about ten to twenty minutes to reach the rated load, but due to the influence of metal thermal stress, the waste heat boiler takes up to two or three hours (cold start) to reach the rated load. In order to reduce the thermal stress inside the metal in the waste heat boiler, the flow rate of gas turbine exhaust steam entering the waste heat boiler must be controlled during the startup process. During the startup process, about three-quarters of the exhaust steam is discharged into the atmosphere, which can last up to 20-30 minutes, resulting in energy loss.

[0005] Due to the impact condition, the power generation unit is in a transient operating environment. When the generator trips, the fuel valve and the shut-off valve must be activated in a very short time to prevent the shaft speed from exceeding its limit. Therefore, the dynamic response speed depends largely on the closing and response speed of the valve. Summary of the invention

[0006] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0007] To this end, an embodiment of the present invention provides a system and method for improving the response capability of a SOFC-GT coupled power generation system.

[0008] In one aspect, the present invention provides a system for improving the responsiveness of a SOFC-GT coupled power generation system, comprising:

[0009] A thermal storage stack, wherein the thermal storage stack comprises a plurality of thermal storage stack modules, wherein the thermal storage stack modules comprise a microfluidic porous plate, wherein the microfluidic porous plate has a thermal storage channel for allowing a thermal storage fluid to pass through;

[0010] An afterburner chamber, which is arranged downstream of the thermal storage stack, and the unreacted fuel and air in the thermal storage stack enter the afterburner chamber for combustion;

[0011] A turbine, the turbine being arranged downstream of the afterburner, and the combustion products of the afterburner enter the turbine to perform work;

[0012] Steam turbine, part of the exhaust gas of the turbine enters the waste heat boiler of the steam turbine to generate steam or the heat storage stack to recover waste heat. During the peak period of electric load, the heat storage fluid heats the feed water to generate steam that enters the steam turbine to do work.

[0013] In some embodiments, an air compressor is also included. The air compressor is coaxially arranged with the turbine. The inlet end of the air compressor is connected to the atmosphere, and the outlet end of the air compressor is respectively connected to the cathode inlet end of the thermal storage stack and the combustion chamber inlet end.

[0014] In some embodiments, an air preheater is provided on the pipeline between the outlet of the air compressor and the cathode inlet of the thermal storage stack.

[0015] In some embodiments, the exhaust gas of the turbine is the hot side medium of the air preheater.

[0016] In some embodiments, the outlet end of the afterburner is connected to the inlet end of the air compressor via a pipeline.

[0017] In some embodiments, part of the tail gas of the thermal storage stack enters the waste heat boiler of the steam turbine to generate steam for work.

[0018] In some embodiments, the microfluidic multi-well plate comprises:

[0019] An upper cover plate and a lower cover plate are respectively arranged at the top and the bottom;

[0020] The steam flow channel and the heat storage flow channel are arranged between the upper cover plate and the lower cover plate, and the steam flow channel is connected to the exhaust end of the steam turbine.

[0021] In some embodiments, the thermal storage stack module further includes:

[0022] A plurality of ceramic-based material stacks, wherein the ceramic-based material stacks are sleeved on the microfluidic channel porous plate;

[0023] A housing, wherein the microfluidic channel porous plate is accommodated in the housing;

[0024] A heat storage fluid inlet, the heat storage fluid inlet is arranged on one side of the shell and connected to the heat storage flow channel;

[0025] A heat storage fluid outlet is arranged on one side of the shell and is connected to the heat storage channel.

[0026] In some embodiments, the heat storage fluid is one of molten salt, thermal oil, ionic liquid or high-temperature inert gas.

[0027] On the other hand, the present invention provides a method for improving the response capability of a SOFC-GT coupled power generation system, comprising the following steps:

[0028] During the low-load period of electricity consumption, the turbine exhaust is adjusted so that a part of the exhaust gas enters the thermal storage stack to store heat, and another part of the exhaust gas enters the waste heat boiler of the steam turbine to generate steam;

[0029] During periods of high electricity load, the high-temperature heat storage fluid heats the feed water to generate steam which enters the intermediate pressure cylinder or the low pressure cylinder of the steam turbine to perform work.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] During the trough period of the electric load, the system of the present invention adjusts the exhaust gas distribution valve of the turbine to allow a part of the exhaust gas to pass through the waste heat boiler of the steam turbine to generate steam, so that the amount of steam will be reduced, the electric power of the steam turbine will decrease, and the minimum power operation will be achieved; on the contrary, during the peak period of the electric load, the feed water is heated by the heat storage fluid, evaporated into steam and sent to the medium pressure cylinder or low pressure cylinder of the steam turbine to do work, which can quickly increase the electric power of the combined cycle unit and achieve rapid peak regulation. In addition, if the unit undertakes the task of heating at this time, the heat storage of the stack can be used for heating to ensure the stability of the thermal load.

[0032] The present invention can effectively improve the fuel utilization rate and can be flexibly adjusted according to the terminal energy consumption situation. On the basis of ensuring the efficient operation of the gas turbine, it can make full use of the gas turbine exhaust, combustion chamber, afterburner waste heat and the heat capacity of the SOFC stack during the startup, load change and shutdown processes for heating, greatly improving the flexible adjustment capability of conventional coupled cycle units. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0034] Figure 1 A schematic diagram of a system for improving the response capability of a SOFC-GT coupled power generation system according to the present invention;

[0035] Figure 2 A schematic diagram of a system for improving the response capability of a SOFC-GT coupled power generation system according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the integrated layout of the thermal storage stack;

[0037] Figure 4 It is a schematic diagram of the configuration of the thermal storage stack module;

[0038] Figure 5 It is a schematic diagram of the configuration of the thermal storage stack module;

[0039] Figure 6 Schematic diagram of the microfluidic porous plate structure;

[0040] Description of reference numerals:

[0041] Air compressor 1, turbine 2, steam turbine 3, heat storage stack 4, combustion chamber 5, afterburning chamber 6, heat storage stack module 7, ceramic stack 8, shell 9, microchannel porous plate 10, heat storage fluid inlet 11, heat storage fluid outlet 12, heat storage channel 13, steam channel 14, heat storage medium tank 15, pipeline one 16, pipeline two 17, pipeline three 18, pipeline four 19, pipeline five 20, pipeline six 21, pipeline seven 22, pipeline eight 23, pipeline nine 24, pipeline ten 25, pipeline eleven 26, pipeline twelve 27, pipeline thirteen 28, pipeline fourteen 29, upper cover plate 30, lower cover plate 31, generator 32. DETAILED DESCRIPTION

[0042] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0043] The following describes a system and method for improving the response capability of a SOFC-GT coupled power generation system according to an embodiment of the present invention with reference to the accompanying drawings.

[0044] like Figure 1 As shown, the system for improving the response capability of the SOFC-GT coupled power generation system of the present invention includes a heat storage stack 4, a post-combustion chamber 6, a turbine 2, a steam turbine 3, an air compressor 1 and a combustion chamber 5.

[0045] The air compressor 1 is coaxially arranged with the turbine 2, the inlet end of the air compressor 1 is connected to the atmosphere, and the outlet end of the air compressor 1 is respectively connected to the cathode inlet end of the thermal storage stack 4 and the inlet end of the combustion chamber 5. The air in the atmosphere is compressed by the air compressor 1 and is divided into two paths, one path enters the combustion chamber 5 through pipeline 1 16 to assist combustion, and the other path enters the cathode of the thermal storage stack 4 through pipeline 2 17 and pipeline 3 18 as a reactant for the electrochemical reaction.

[0046] With the pressure guarantee of the air compressor 1, the pipeline can use a universal mass flow controller to control the air flow entering the thermal storage stack 4, and the subsystem can also adopt a relatively complex flow channel and gas distribution structure design.

[0047] The fuel F1 is respectively introduced into the anode inlet of the thermal storage stack 4 through pipeline four 19 and into the combustion chamber 5 through pipeline five 20. The fuel introduced into the combustion chamber 5 and the compressed air introduced into the combustion chamber 5 are burned in the combustion chamber 5, and the combustion products are introduced into the anode inlet of the thermal storage stack 4 through pipeline six 21, that is, the combustion products of the combustion chamber 5 and part of the F1 fuel are introduced into the anode inlet of the thermal storage stack 4 as electrochemical reactants.

[0048] In some embodiments, an air preheater is provided on the pipeline between the outlet of the air compressor 1 and the cathode inlet of the thermal storage stack 4. The air preheater is used to preheat the air so that the temperature of the air entering the thermal storage stack 4 is close to the operating temperature of the thermal storage stack 4, thereby increasing the electrochemical reaction rate.

[0049] In some embodiments, the exhaust gas A3 of the turbine 2 is the hot side medium of the air preheater, that is, the exhaust gas of the turbine 2 is used to preheat the air. On the one hand, the effect of preheating the air is achieved, and on the other hand, the exhaust gas of the turbine 2 is recycled to avoid energy waste.

[0050] The afterburner chamber 6 is arranged downstream of the heat storage stack 4. The fuel and air that have not reacted completely in the heat storage stack 4 are introduced into the afterburner chamber 6 through pipeline seven 22 for combustion. In order to achieve better combustion, fuel F2 is passed into the afterburner chamber 6. The combustion products after combustion in the afterburner chamber 6 enter the turbine 2 arranged downstream of the afterburner chamber 6 through pipeline eight 23 to perform work. The turbine 2 drives the air compressor 1 and the generator 32 arranged coaxially therewith to work.

[0051] It can be understood that the fuel F1 and the fuel F2 can be a single component or a mixture including pure hydrogen, carbon monoxide or any hydrocarbon fuel, and the two can be fuels of the same or different components.

[0052] The tail gas of turbine 2 is a high-temperature gas. Part of the tail gas of turbine 2 is passed through pipeline nine 24 to the waste heat boiler of steam turbine 3 to heat the feed water to generate steam to do work, thereby recovering the waste heat of the tail gas of turbine 2; part of the tail gas of turbine 2 enters the thermal storage stack 4 through pipeline ten 25 to store heat. The specific heat storage method can be to extract the heat in the tail gas of turbine 2 through a heat exchanger and store it in the heat storage fluid of the thermal storage stack 4, thereby diverting the tail gas of turbine 2, thereby reducing the power generation of steam turbine 3 and achieving peak load regulation. It is understandable that the excess tail gas of turbine 2 is directly discharged.

[0053] In some embodiments, Figure 2 As shown, the outlet of the afterburning chamber 6 is connected to the inlet of the air compressor 1 through the pipeline 14 29, that is, the air is first heated by the combustion products of the afterburning chamber 6, and then the air is compressed by the air compressor 1. The specific method of heating the air by the combustion products of the afterburning chamber 6 is to set a heat exchanger on the pipeline between the outlet of the afterburning chamber 6 and the inlet of the air compressor 1, and pass the air into the cold side of the heat exchanger. The combustion products of the afterburning chamber 6 pass through the hot side of the heat exchanger through the pipeline 14 29, so that the combustion products on the hot side exchange heat with the air on the cold side, which heats the air. At the same time, the heat of the combustion products of the afterburning chamber 6 is used to avoid energy waste. The combustion products of the afterburning chamber 6 are used to preheat the air, so that the preheating temperature of the air is close to the working temperature of the thermal storage stack 4, which ensures that the thermal storage stack 4 starts quickly and stably during the loading process.

[0054] like Figure 3-5 As shown, the thermal storage stack 4 includes a plurality of thermal storage stack modules 7, and the plurality of thermal storage stack modules 7 are arranged in a set number of stacking, parallel connection, series connection or other methods to form a thermal storage stack 4, and are placed in a heat preservation box.

[0055] The heat storage stack module 7 includes a microchannel porous plate 10, a shell 9, a heat storage fluid inlet 11, a heat storage fluid outlet 12 and multiple ceramic stacks 8, wherein the ceramic stack 8 can be a single cell sheet of any shape electrically connected together, the ceramic stack 8 is sleeved on the microchannel porous plate 10, the microchannel porous plate 10 is accommodated in the shell 9, the heat storage fluid inlet 11 and the heat storage fluid outlet 12 are arranged on one side of the shell 9 and connected to the heat storage channel 13, that is, the heat storage fluid enters the heat storage stack module 7 through the heat storage fluid inlet 11, and flows out from the heat storage fluid outlet 12 after heat exchange.

[0056] like Figure 6As shown, the microchannel porous plate 10 includes an upper cover plate 30, a lower cover plate 31, a heat storage channel 13 and a steam channel 14, wherein the upper cover plate 30 and the lower cover plate 31 are respectively arranged at the top and the bottom, the heat storage channel 13 and the steam channel 14 are arranged between the upper cover plate 30 and the lower cover plate 31, and the heat storage channel 13 and the steam channel 14 are arranged in layers, that is, the upper layer and the lower layer are both heat storage channels 13, and the middle layer is the steam channel 14. The heat storage channel 13 is a channel for the heat storage fluid. When the heat storage fluid flows through the heat storage stack 4, it absorbs the sensible heat of the heat storage stack 4 and stores the heat energy in the heat storage fluid. The steam channel 14 is connected to the exhaust end of the steam turbine 3. The low-temperature steam discharged from the steam turbine 3 enters the heat storage stack 4 through the pipeline 11 26, and is heated to high-temperature steam by the sensible heat of the heat storage stack 4, and then enters the steam turbine 3 again to do work.

[0057] The thermal storage stack modules 7 in the thermal storage stack 4 are interconnected via a single or multiple thermal storage fluid inlets 11 and thermal storage fluid outlets 12, and a thermal storage medium tank 15 is disposed in the box where each pipeline converges into and out of.

[0058] It is understandable that, when the flow resistance loss is negligible, the heat storage medium tank 15 can also be separately provided outside the heat storage stack module 7 .

[0059] It can be understood that there can be one or more heat storage medium tanks 15. When multiple heat storage medium tanks 15 are provided, the high-temperature heat storage fluid and the low-temperature heat storage fluid are stored in different heat storage medium tanks 15 respectively. When one heat storage medium tank 15 is provided, the high-temperature heat storage fluid and the low-temperature heat storage fluid are stored in the same heat storage medium tank 15. The heat storage medium tanks 15 are separated by insulation partitions and divided into cold and hot zones.

[0060] The heat storage fluid is molten salt or heat transfer oil. In some embodiments, the heat storage fluid may also be an inert gas, liquid metal, ionic liquid, organic matter, water or other suitable fluids.

[0061] Part of the exhaust gas A2 of the thermal storage stack 4 enters the waste heat boiler of the steam turbine 3 to generate steam to do work, that is, when the electricity load is high, the heat storage fluid heats the feed water to generate high-temperature steam and enters the medium-pressure cylinder or low-pressure cylinder of the steam turbine 3 through pipeline twelve 27 to do work. At the same time, in some embodiments, part of the exhaust gas of the thermal storage stack 4 can also be heated by the heat exchanger on pipeline thirteen 28 to generate steam to do work.

[0062] The present invention releases the heat stored in the high-temperature fluid to quickly increase the electric power of the steam turbine 3 when the power load is at a peak, and can also use the heat storage stack 4 to provide heat, greatly improving the flexible adjustment capability of conventional coupled cycle units.

[0063] A method for improving the response capability of a SOFC-GT coupled power generation system, using the system of the present invention, comprises the following steps:

[0064] During the period of low electricity load, the exhaust gas distribution of turbine 2 is adjusted so that part of the exhaust gas enters the thermal storage stack 4 to store heat, and the other part of the exhaust gas enters the waste heat boiler of the steam turbine 3 to generate steam; during the period of high electricity load, the high-temperature heat storage fluid heats the feed water to generate steam that enters the medium-pressure cylinder or low-pressure cylinder of the steam turbine 3 to perform work.

[0065] Specifically, during the period of low electricity load, the exhaust gas of the turbine 2 is adjusted so that part of the exhaust gas enters the thermal storage stack 4 for heat storage, while the other part of the exhaust gas enters the waste heat boiler of the steam turbine 3 to generate steam, so that the amount of steam will be reduced, and the electric power of the steam turbine 3 will decrease, and the minimum power operation can be achieved; at the same time, the output of the thermal storage stack 4 is adjusted. When the thermal storage stack 4 completes the hot start, the temperature of the thermal storage stack 4 will increase with the voltage change during this process. By controlling the air flow entering the thermal storage stack 4, the temperature of the thermal storage stack 4 is controlled within the operating temperature range. During the period of high electricity load, the low-temperature heat storage fluid flows out through the heat storage medium storage tank 15 and flows into the thermal storage stack 4, receiving the sensible heat of the thermal storage stack 4 to become a high-temperature heat storage fluid. The high-temperature heat storage fluid heats the feed water through the heat exchanger to generate steam and enters the medium-pressure cylinder or low-pressure cylinder of the steam turbine 3 to perform work, which can quickly increase the electric power of the combined cycle unit and achieve rapid peak regulation. If the unit is responsible for heating at this time, the heat stored in the thermal storage stack 4 can be used for heating to ensure the stability of the thermal load; at the same time, in the high load mode, the fuel utilization rate of the stack is high and the gas flow rate is large, which is conducive to the distribution of waste heat from the thermal storage stack 4.

[0066] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms may be for different embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0067] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0068] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A system for improving the responsiveness of a SOFC-GT coupled power generation system, characterized in that: include: A thermal storage stack, wherein the thermal storage stack comprises a plurality of thermal storage stack modules, wherein the thermal storage stack modules comprise a microfluidic porous plate, wherein the microfluidic porous plate has a thermal storage channel for allowing a thermal storage fluid to pass through; An afterburner chamber, which is arranged downstream of the thermal storage stack, and the unreacted fuel and air in the thermal storage stack enter the afterburner chamber for combustion; A turbine, the turbine being arranged downstream of the afterburner, and the combustion products of the afterburner enter the turbine to perform work; Steam turbine, part of the exhaust gas of the turbine enters the waste heat boiler of the steam turbine to generate steam or the heat storage stack to recover waste heat. During the peak period of electric load, the heat storage fluid heats the feed water to generate steam that enters the steam turbine to do work.

2. The system according to claim 1, characterized in that It also includes an air compressor, which is coaxially arranged with the turbine, the inlet end of the air compressor is connected to the atmosphere, and the outlet end of the air compressor is respectively connected to the cathode inlet end of the thermal storage stack and the combustion chamber inlet end.

3. The system according to claim 2, characterized in that An air preheater is arranged on the pipeline between the outlet end of the air compressor and the cathode inlet end of the thermal storage stack.

4. The system according to claim 3, characterized in that The exhaust gas of the turbine is the hot side medium of the air preheater.

5. The system according to claim 2, characterized in that The outlet end of the afterburning chamber is connected to the inlet end of the air compressor through a pipeline.

6. The system according to claim 1, characterized in that Part of the tail gas from the thermal storage stack enters the waste heat boiler of the steam turbine to generate steam for work.

7. The system according to claim 1, characterized in that The microfluidic multi-well plate comprises: An upper cover plate and a lower cover plate are respectively arranged at the top and the bottom; The steam flow channel and the heat storage flow channel are arranged between the upper cover plate and the lower cover plate, and the steam flow channel is connected to the exhaust end of the steam turbine.

8. The system according to claim 7, characterized in that The thermal storage stack module also includes: A plurality of ceramic-based material stacks, wherein the ceramic-based material stacks are sleeved on the microfluidic channel porous plate; A housing, wherein the microfluidic channel porous plate is accommodated in the housing; A heat storage fluid inlet, the heat storage fluid inlet is arranged on one side of the shell and connected to the heat storage flow channel; A heat storage fluid outlet is arranged on one side of the shell and is connected to the heat storage channel.

9. The system according to claim 1, characterized in that The heat storage fluid is one of molten salt, heat transfer oil, ionic liquid or high-temperature inert gas.

10. A method for improving the response capability of a SOFC-GT coupled power generation system, characterized in that: Using the system as described in any one of claims 1 to 9, comprising the following steps: During the low-load period of electricity consumption, the turbine exhaust is adjusted so that a part of the exhaust gas enters the thermal storage stack to store heat, and another part of the exhaust gas enters the waste heat boiler of the steam turbine to generate steam; During periods of high electricity load, the high-temperature heat storage fluid heats the feed water to generate steam which enters the intermediate pressure cylinder or the low pressure cylinder of the steam turbine to perform work.

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