Multi-stream small-temperature-difference regenerator and application thereof

Abstract

The application provides a multi-flow small-temperature-difference regenerator and an application thereof, the multi-flow small-temperature-difference regenerator is arranged in a flue; the multi-flow small-temperature-difference regenerator comprises a mixed gas pipeline, a mixed gas merging channel, a header, a cooling gas pipeline and a cooling gas merging channel; the mixed gas merging channel, the header and the cooling gas merging channel are sequentially arranged; the mixed gas pipeline is connected in series with the mixed gas merging channel; the cooling gas pipeline and the cooling gas merging channel are connected in series; the number of the mixed gas pipelines close to the side of the cooling gas merging channel of the header is less than the number of the mixed gas pipelines far from the side of the cooling gas merging channel; the header is provided with a flow guide vane; the multi-flow small-temperature-difference regenerator is provided with a rib with a flow guide function. The mixed gas is uniformly distributed in the header through the arrangement of the header, and the flow balance in each mixed gas pipeline is ensured.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, and in particular to a multi-flow small temperature difference regenerator and its application. Background Technology

[0002] The direct-fired supercritical CO2 power generation system utilizes the characteristics of supercritical CO2, such as high specific heat and low compressibility near the critical point, and employs direct combustion of hydrocarbon fuels to obtain high-temperature, high-pressure flue gas exceeding 1000°C to drive a turbine. Since the system's circulating working fluid is CO2, the main components of the flue gas are CO2 and water vapor. After reheating in a regenerator, the flue gas finally enters a condenser to remove water vapor. Excess CO2 is collected by a carbon capture device to maintain the balance of circulating CO2 within the system.

[0003] Multi-flow regenerators are key equipment in direct-fired supercritical CO2 power generation systems. They are used to recover waste heat from the exhaust gas of the gas turbine and to heat the O2 / CO2 mixture entering the combustion chamber, as well as the CO2 cooling gas entering the gas turbine, thereby improving the system's power generation efficiency. However, in existing multi-flow regenerators, after the gas turbine cooling gas leaves the regenerator, the cold stream in the high-temperature zone of the regenerator consists only of the O2 / CO2 mixture, resulting in a reduction in the overall mass flow rate. Meanwhile, the number of pipes and the flow area of ​​the flue remain unchanged. If not properly addressed, this can lead to uneven distribution and flow rate of the O2 / CO2 mixture in the heat exchange pipes of the high-temperature zone. This can easily cause the temperature of the O2 / CO2 mixture leaving the high-temperature zone to deviate from the design value, thus affecting the overall performance of the system.

[0004] CN111102026A discloses a cascaded supercritical carbon dioxide power cycle system, comprising a direct-fired supercritical carbon dioxide cycle subsystem and an indirect-fired supercritical carbon dioxide cycle subsystem. It consists of a carbon dioxide pump, an intercooler, a high- and low-temperature regenerator, a combustion chamber, a high- and low-temperature turbine, a generator, a cooler, a water separator, a condenser, a carbon dioxide collection device, and a high-temperature heat exchanger. The exhaust heat from the turbine of the direct-fired supercritical carbon dioxide cycle subsystem is used as the heat source for the main heater of the indirect-fired supercritical carbon dioxide cycle subsystem, achieving complementary advantages between the two systems.

[0005] CN109723557A discloses an integrated solar-powered methane dry reforming oxygen-enriched combustion carbon dioxide power generation system. The system mainly consists of a solar-powered reforming reactor, a multi-flow heat exchanger, a compressor, a combustion chamber, a turbine, a regenerator, and an air separator. In this system, concentrated high-temperature solar energy provides heat for the methane-carbon dioxide catalytic reforming reaction. The resulting syngas is directly heated by oxygen-enriched combustion to drive supercritical carbon dioxide power generation, and the combustion products can be separated from the exhaust gas. The carbon dioxide generated by the thermal power generation can be used for fuel synthesis and resource utilization. The system achieves efficient heat and pressure recovery by adding a multi-flow heat exchanger and a low-pressure turbine. By integrating solar energy on the fuel side, the system can reduce the impact of solar energy fluctuations on the power cycle; simultaneously, through the supercritical carbon dioxide power cycle directly heated by oxygen-enriched combustion, it achieves zero emissions from carbon-based fuel power generation.

[0006] CN106437904A discloses a coal-based supercritical carbon dioxide power generation system with solar medium-temperature preheating, including a boiler, a turbine, a main compressor, a re-compressor, a generator, a precooler, a low-temperature regenerator, a high-temperature regenerator, and a solar medium-temperature preheater. The turbine outlet is divided into two paths after passing through the hot side of the high-temperature regenerator and the hot side of the low-temperature regenerator. One path is connected to the cold-side inlet of the low-temperature regenerator via the precooler and the main compressor. The other path is divided into two paths after passing through the re-compressor. One path is connected to the inlet of the solar medium-temperature preheater, and the other path is connected to the cold-side inlet of the high-temperature regenerator via a pipe. The cold-side outlet of the high-temperature regenerator and the outlet of the solar medium-temperature preheater are connected to the working fluid inlet of the boiler via a pipe. The boiler outlet is connected to the turbine inlet.

[0007] However, none of the above-mentioned carbon dioxide power generation systems have solved the problem of uneven distribution and flow of the O2 / CO2 mixture in the heat exchange pipeline of the high-temperature zone of the regenerator. Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention provides a multi-stream small temperature difference regenerator and its application. By setting up a header, the oxygen and carbon dioxide mixture is collected in the header. Under the action of the guide vanes set in the header, the flow rate is distributed to ensure that the flow rate entering each mixture pipe is balanced, so that the temperature of the mixture flowing out of the high temperature area of ​​the regenerator matches the design value.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a multi-flow small temperature difference regenerator, wherein the multi-flow small temperature difference regenerator is disposed in a flue.

[0011] The multi-stream small temperature difference regenerator includes a mixed gas pipeline, a mixed gas merging channel, a header, a cooling gas pipeline, and a cooling gas merging channel;

[0012] The mixed gas merging channel, header, and cooling gas merging channel are arranged sequentially; the mixed gas pipeline is connected in series with the mixed gas merging channel; the cooling gas pipeline is connected in series with the cooling gas merging channel.

[0013] The number of mixed gas pipes on the side of the manifold closer to the cooling gas confluence channel is less than the number on the side farther from the cooling gas confluence channel;

[0014] The manifold is equipped with flow guide vanes; the multi-flow small temperature difference regenerator is equipped with fins that have flow guiding function.

[0015] The multi-stream small temperature difference regenerator of this invention is installed in the flue. By sequentially setting up a mixed gas merging channel, a header, and a cooling gas merging channel, the header solves the problem of uneven mixed gas flow distribution caused by the reduction in the total flow of cold stream in the high-temperature region after the cooling gas from the gas turbine flows out of the medium-temperature region of the regenerator. Under the action of the guide vanes in the header, the mixed gas is evenly distributed, which enables the mixed gas to be heated to the temperature required by the flue gas from the gas turbine in the flue to meet the design value.

[0016] The gas flowing in the gas mixing pipeline of this invention is a mixture of oxygen and carbon dioxide, while the gas flowing in the cooling gas pipeline is carbon dioxide. The carbon dioxide flows out from the mid-temperature zone via the cooling gas pipeline and the cooling gas merging channel, serving as cooling gas for the combustion turbine. The oxygen and carbon dioxide mixture enters the header via the gas mixing pipeline in the mid-temperature zone, undergoes flow distribution, and then flows out via the gas mixing pipeline and the gas merging channel in the high-temperature zone before entering the combustion chamber. Therefore, the number of gas mixing pipelines connected to the header on the side closer to the cooling gas merging channel is less than the number on the side farther from the cooling gas merging channel.

[0017] The arrangement of the guide vanes in the manifold described in this invention is determined through numerical simulation calculations or experiments.

[0018] Preferably, the mixed gas pipe and the cooling gas pipe pass through ribs with a flow guiding function.

[0019] Preferably, the mixed gas pipe and the cooling gas pipe are evenly distributed on the ribs with the flow guiding function.

[0020] Preferably, the rib with the flow guiding function is provided with flue gas passage holes.

[0021] Preferably, the flue gas through-holes are evenly distributed along the mixed gas pipe and the cooling gas pipe, so that the flue gas flow of the gas turbine is evenly distributed.

[0022] Preferably, the gas-mixture channel is connected to the combustion chamber via a first pipe.

[0023] Preferably, the cooling gas merging channel is connected to the gas turbine via a second pipe.

[0024] Secondly, the present invention also provides an application of the multi-stream small temperature difference regenerator as described in the first aspect, wherein the multi-stream small temperature difference regenerator is applied to the high-temperature region and the medium-temperature region of the heat exchanger flue of a direct-fired supercritical carbon dioxide power generation system.

[0025] Preferably, the temperature of the high-temperature zone is 400-500℃, for example, it can be 400℃, 420℃, 440℃, 450℃, 470℃ or 500℃.

[0026] Preferably, the temperature of the medium temperature zone is 300-350℃, for example, it can be 300℃, 310℃, 320℃, 330℃, 340℃ or 350℃, etc.

[0027] Preferably, the flue gas flows through the flue gas through-holes on the fins with the flow guiding function into the multi-flow small temperature difference regenerator, and exchanges heat with the oxygen and carbon dioxide mixture in the mixed gas pipeline and the gas turbine cooling gas in the cooling gas pipeline in a counter-current contact.

[0028] In the medium-temperature zone, the gas turbine cooling gas exchanges heat with the flue gas and then enters the gas turbine through the cooling gas merging channel. The oxygen and carbon dioxide mixture exchanges heat with the flue gas and then enters the header. In the high-temperature zone, the oxygen and carbon dioxide mixture continues to exchange heat with the flue gas and then enters the combustion chamber through the mixture merging channel.

[0029] The multi-stream small temperature difference regenerator described in this invention is applied to the high-temperature and medium-temperature regions of the heat exchanger flue in a direct-fired supercritical carbon dioxide power generation system. By using a header to distribute the flow of the oxygen and carbon dioxide mixture entering the high-temperature region from the medium-temperature region, it solves the problem of uneven flow distribution caused by the reduction in the total flow of cold stream in the high-temperature region due to the cooling gas from the gas turbine flowing out of the medium-temperature region of the regenerator. This ensures that the oxygen and carbon dioxide mixture at the outlet of the multi-stream small temperature difference regenerator is heated to the design temperature.

[0030] As a preferred technical solution of the present invention, the multi-stream small temperature difference regenerator is applied to the high temperature region of 400-500℃ and the medium temperature region of 300-350℃ in the heat exchange device of the direct-fired supercritical carbon dioxide power generation system.

[0031] Flue gas flows through the flue gas through-holes on the fins with flow guiding function into the multi-flow small temperature difference regenerator, where it undergoes counter-current contact heat exchange with the oxygen and carbon dioxide mixture in the mixed gas pipeline and the cooling gas of the gas turbine in the cooling gas pipeline. In the medium temperature region, the carbon dioxide gas flowing through the cooling gas pipeline exchanges heat with the flue gas and then enters the gas turbine as cooling gas through the cooling gas merging channel. The oxygen and carbon dioxide mixture flowing through the mixed gas pipeline exchanges heat with the flue gas and then enters the header. In the high temperature region, the oxygen and carbon dioxide mixture continues to exchange heat with the flue gas and then enters the combustion chamber through the mixed gas merging channel.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] The multi-stream small temperature difference regenerator provided by this invention has a simple structure and reasonable design. By setting up a header to buffer and distribute the flow of the oxygen and carbon dioxide mixture, the oxygen and carbon dioxide mixture is heated to the design temperature value without affecting the overall performance of the direct-fired supercritical carbon dioxide power generation system. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the multi-stream small temperature difference regenerator in Embodiment 1 of the present invention.

[0035] Figure 2 This is a cross-sectional view (AA) of the multi-stream small temperature difference regenerator in Embodiment 1 of the present invention.

[0036] Figure 3 This is a schematic diagram of the connection between the manifold and the mixed gas pipeline in Embodiment 1 of the present invention.

[0037] Figure 4 This is a schematic diagram of the regenerator in Comparative Example 1.

[0038] In the diagram: 1-Mixed gas pipeline; 2-Mixed gas merging channel; 3-Manipulator; 4-Cooling gas pipeline; 5-Cooling gas merging channel; 6-Guide plate; 7-Flat plate with guiding function; 8-Fluorite through hole; 9-First pipeline; 10-Second pipeline; 11-High temperature zone heat exchanger; 12-Medium temperature zone heat exchanger; 13-Fluorite pipeline. Detailed Implementation

[0039] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0040] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0041] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0042] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] Those skilled in the art should understand that the present invention necessarily includes the necessary pipelines, conventional valves and general pump equipment for achieving process integrity, but the above content is not the main inventive point of the present invention. Those skilled in the art can add layouts based on process flow and equipment structure selection, and the present invention does not make any special requirements or specific limitations in this regard.

[0044] Example 1

[0045] This embodiment provides a multi-flow, small-temperature-difference regenerator, the schematic diagram of which is shown below. Figure 1 As shown; AA sectional view as shown Figure 2 As shown.

[0046] The multi-stream small temperature difference regenerator is installed inside the flue; the multi-stream small temperature difference regenerator includes a mixed gas pipeline 1, a mixed gas merging channel 2, a header 3, a cooling gas pipeline 4, and a cooling gas merging channel 5; the mixed gas merging channel 2, the header 3, and the cooling gas merging channel 5 are arranged sequentially; the mixed gas pipeline 1 and the mixed gas merging channel 2 are connected in series; the cooling gas pipeline 4 and the cooling gas merging channel 5 are connected in series.

[0047] The number of mixing gas pipes on the side of the manifold 3 closer to the cooling gas merging channel 5 is less than the number on the side farther from the cooling gas merging channel 5. A schematic diagram of the connection between the manifold and the mixing gas pipes 1 is shown below. Figure 3 As shown.

[0048] The manifold 3 is equipped with a flow guide plate 6; the multi-flow small temperature difference regenerator is equipped with a fin 7 with a flow guiding function.

[0049] The mixed gas pipe 1 and the cooling gas pipe 4 pass through the rib 7, which has a flow guiding function.

[0050] The mixed gas pipe 1 and the cooling gas pipe 4 are evenly distributed on the ribs 7 with the flow guiding function.

[0051] The rib 7 with the flow guiding function is provided with flue gas passage holes 8.

[0052] The flue gas through-holes 8 are evenly distributed along the mixed gas pipe 1 and the cooling gas pipe 4.

[0053] The gas-mixture channel 2 is connected to the combustion chamber via the first pipe 9.

[0054] The cooling gas merging channel 5 is connected to the gas turbine via the second pipe 10.

[0055] The multi-stream small temperature difference regenerator described in this embodiment is applied to the high-temperature region of 450°C and the medium-temperature region of 320°C in the heat exchange device of a direct-fired supercritical carbon dioxide power generation system.

[0056] Flue gas flows through flue gas through holes 8 on fins 7 with flow guiding function to multi-flow small temperature difference regenerator, and exchanges heat with oxygen and carbon dioxide mixture in mixed gas pipeline 1 and gas turbine cooling gas in cooling gas pipeline 4 in counter-current contact.

[0057] In the medium-temperature region, carbon dioxide gas flowing through cooling gas pipe 4 exchanges heat with flue gas and then enters the gas turbine as cooling gas through cooling gas merging channel 5. Oxygen and carbon dioxide mixture flowing through mixed gas pipe 1 exchanges heat with flue gas and then enters header 3. In the high-temperature region, oxygen and carbon dioxide mixture continues to exchange heat with flue gas and then enters the combustion chamber through mixed gas merging channel 2.

[0058] The multi-stream small temperature difference regenerator provided in this embodiment uses headers and guide vanes to buffer and distribute the flow of the oxygen and carbon dioxide mixture, which enables the oxygen and carbon dioxide mixture to be heated to the design temperature value without affecting the overall performance of the direct-fired supercritical carbon dioxide power generation system.

[0059] Comparative Example 1

[0060] This comparative example provides a regenerator, the schematic diagram of which is shown below. Figure 4 As shown.

[0061] The regenerator includes a high-temperature zone heat exchanger 11 and a medium-temperature zone heat exchanger 12 arranged sequentially; the number of heat exchange tubes in the high-temperature zone heat exchanger 11 and the medium-temperature zone heat exchanger 12 is the same.

[0062] The mixed gas pipeline 1 is connected in sequence to the medium temperature zone heat exchanger 12 and the high temperature zone heat exchanger 11, and then enters the combustion chamber.

[0063] Cooling gas pipe 4 is connected to the medium-temperature zone heat exchanger 12, and then enters the gas turbine.

[0064] The flue gas duct 13 is connected in sequence to the high temperature zone heat exchanger 11 and the medium temperature zone heat exchanger 12. The flue gas undergoes countercurrent contact heat exchange with the oxygen and carbon dioxide mixture flowing through the mixed gas duct 1 and the carbon dioxide working fluid flowing through the cooling gas duct 4.

[0065] In this comparative example, the carbon dioxide working fluid in the cooling gas pipe exchanges heat with the flue gas and leaves the regenerator. The overall mass flow rate of the oxygen and carbon dioxide mixture entering the high-temperature zone heat exchanger is reduced, while the number of heat exchange tubes and the flow area remain the same in both the high-temperature and medium-temperature zone heat exchangers. This results in uneven distribution and flow rate of the oxygen and carbon dioxide mixture in the heat exchange tubes of the high-temperature zone heat exchanger. Consequently, the temperature of the oxygen and carbon dioxide mixture leaving the high-temperature zone heat exchanger deviates from the design value, thus affecting the overall system performance.

[0066] In summary, the multi-stream small temperature difference regenerator provided by this invention has a simple structure and reasonable design. It utilizes the header to buffer and distribute the flow of the oxygen and carbon dioxide mixture, so that the oxygen and carbon dioxide mixture is heated to the design temperature value, ensuring the normal and stable operation of the direct-fired supercritical carbon dioxide power generation system.

[0067] The present invention is described in detail through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0068] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A multi-stream small temperature difference regenerator, characterized in that, The multi-stream small temperature difference regenerator is installed inside the flue; The multi-stream small temperature difference regenerator includes a mixed gas pipeline, a mixed gas merging channel, a header, a cooling gas pipeline, and a cooling gas merging channel; The mixed gas merging channel, header, and cooling gas merging channel are arranged sequentially; the mixed gas pipeline is connected in series with the mixed gas merging channel; the cooling gas pipeline is connected in series with the cooling gas merging channel. The number of mixed gas pipes on the side of the manifold closer to the cooling gas confluence channel is less than the number on the side farther from the cooling gas confluence channel; The manifold is equipped with flow guide vanes; the multi-flow small temperature difference regenerator is equipped with fins that have flow guiding function.

2. The multi-stream small temperature difference regenerator according to claim 1, characterized in that, The mixed gas pipe and the cooling gas pipe pass through ribs with a flow guiding function.

3. The multi-stream small temperature difference regenerator according to claim 1, characterized in that, The mixed gas pipes and cooling gas pipes are evenly distributed on the ribs with flow guiding function.

4. The multi-stream small temperature difference regenerator according to claim 1, characterized in that, The rib with the flow guiding function is provided with flue gas passage holes.

5. The multi-stream small temperature difference regenerator according to claim 4, characterized in that, The flue gas vents are evenly distributed along the mixed gas pipe and the cooling gas pipe.

6. The multi-stream small temperature difference regenerator according to claim 1, characterized in that, The gas-mixture channel is connected to the combustion chamber via a first pipe.

7. The multi-stream small temperature difference regenerator according to claim 1, characterized in that, The cooling gas merging channel is connected to the gas turbine via a second pipeline.

8. An application of the multi-stream small temperature difference regenerator as described in any one of claims 1-7, characterized in that, The multi-stream small temperature difference regenerator is applied to the high-temperature and medium-temperature regions of the heat exchanger flue in a direct-fired supercritical carbon dioxide power generation system.

9. The application according to claim 8, characterized in that, The temperature in the high-temperature zone is 400-500℃; The temperature in the medium-temperature zone is 300-350℃.

10. The application according to claim 8, characterized in that, Flue gas flows through the flue gas through holes on the fins with flow guiding function into the multi-flow small temperature difference regenerator, where it exchanges heat with the oxygen and carbon dioxide mixture flowing through the mixed gas pipe and the carbon dioxide gas flowing through the cooling gas pipe in a counter-current contact. In the medium-temperature zone, carbon dioxide gas flowing through the cooling gas pipe exchanges heat with the flue gas and then enters the gas turbine as cooling gas through the cooling gas merging channel. Oxygen and carbon dioxide mixture flowing through the mixed gas pipe exchanges heat with the flue gas and then enters the header. In the high-temperature zone, oxygen and carbon dioxide mixture continues to exchange heat with the flue gas and then enters the combustion chamber through the mixed gas merging channel.

Images