A split-flow recompression supercritical CO2 cycle power generation system and method

Abstract

The invention discloses a split-flow recompression type supercritical CO 2 A cycle power generation system and method, the power generation system includes a combustion chamber, a medium-pressure turbine, a regenerator, a cooler, a separator, a recompression compressor, a high-pressure turbine and a multi-stage compressor; the present invention increases the flow rate and temperature of the cold fluid at the hot end of the regenerator by diverting a part of the gas flowing out of the separator, and adding a recompression compressor for recompression, and mixing it with the exhaust gas of the high-pressure turbine before entering the regenerator for reheating, which can effectively reduce the heat exchange temperature difference at the hot end. In addition, after adding the recompression compressor, there is no need to set up a reheating device, which can avoid the inlet temperature of the logistics at the hot end of the regenerator being too high.

Description

Technical Field

[0001] The present invention belongs to the technical field of power generation, and in particular relates to a split-flow recompression supercritical CO2 cycle power generation system and method. Background Art

[0002] Reducing CO2 emissions from fossil fuel power plants plays a vital role in alleviating global warming and is one of the important issues of concern in the current energy field. The technical routes for reducing CO2 emissions from fossil fuel power plants generally include pre-combustion capture, post-combustion capture, and oxygen combustion. However, regardless of the technical route, the introduction of CO2 capture will result in a significant reduction in efficiency and a substantial increase in costs. Improving the technical economy and competitiveness of carbon capture power plants requires the development of key technologies on the one hand and system innovation on the other.

[0003] Conventional energy power systems usually use air or water as circulating fluids. In recent years, using CO2 as a power cycle working fluid has received more and more attention and has become a research hotspot. CO2 is an inert substance with good thermal and chemical stability. It is less corrosive than water vapor and is easy to reach a critical state (7.4MPa, 31°C). It has a high fluid density and significantly reduces the footprint of the impeller. The cycle with supercritical CO2 as the working fluid can be divided into two types: closed cycle and semi-closed cycle. The closed cycle is based on external indirect heating. The CO2 in the cycle is generally supercritical. Its main purpose of development is to improve the efficiency of heat-to-work conversion. It is mostly used in nuclear energy, solar concentrating thermal power generation, medium and low temperature waste heat recovery and other fields. In recent years, it has also developed towards the application of fossil fuel combustion power plants. The semi-closed cycle is an internal combustion oxygen combustion cycle. The cycle is directly heated by the combustion of pure oxygen fuel. The CO2 produced by the combustion directly participates in the cycle, which can easily achieve complete zero emission of CO2 while maintaining high efficiency. For the sake of efficiency and specific work, the internal combustion cycle is mostly a transcritical cycle.

[0004] Using natural gas as fuel, domestic and foreign scholars have proposed a variety of internal combustion supercritical CO2 cycles in the past two decades. The two most representative cycles are the Matiant cycle and the Allam cycle. The Matiant cycle adopts a high-pressure, medium-temperature supercritical CO2 turbine followed by a two-stage medium-low pressure, high-temperature combustion and a two-stage heat recovery cycle, which avoids the simultaneous occurrence of high pressure and high temperature. The Allam cycle adopts a one-stage high-pressure, high-temperature combustion chamber and a one-stage heat recovery structure. Due to the simultaneous occurrence of high pressure and high temperature, the technical challenges are great, but the efficiency is higher than the Matiant cycle. The existing internal combustion supercritical CO2 cycle uses two-stage combustion or reheating, which makes the inlet temperature of the logistics at the hot end of the recuperator too high, bringing greater technical difficulties and risks. Summary of the invention

[0005] The purpose of the present invention is to provide a split-flow recompression supercritical CO2 cycle power generation system and method to solve the problem in the prior art that the inlet temperature of the hot fluid in the regenerator is increased by reheating, which makes the inlet temperature of the hot end logistics of the regenerator too high, posing a great technical risk.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a split-flow recompression supercritical CO2 cycle power generation system, comprising a combustion chamber, a medium-pressure turbine, a regenerator, a cooler, a separator, a recompression compressor, a high-pressure turbine and a multi-stage compressor;

[0008] The logistics outlet of the combustion chamber is connected to the logistics inlet of the medium-pressure turbine, and the logistics outlet of the medium-pressure turbine is connected to the first logistics inlet of the regenerator for releasing heat in the regenerator; the first logistics outlet of the regenerator is connected to the cooler and the separator in sequence;

[0009] The carbon dioxide outlet of the separator is divided into two routes, the first route outlet is connected to the logistics inlet of the multi-stage compressor, the logistics outlet of the multi-stage compressor is connected to the second logistics inlet of the regenerator, and the logistics discharged by the multi-stage compressor absorbs the heat in the regenerator; the second logistics outlet of the regenerator is connected to the high-pressure turbine, and the logistics discharged by the multi-stage compressor absorbs the heat of the regenerator to drive the high-pressure turbine;

[0010] The second route of the separator's carbon dioxide outlet is connected to the logistics inlet of the recompression compressor, and the logistics outlet of the recompression compressor and the logistics outlet of the high-pressure turbine are commonly connected to the third logistics inlet of the regenerator, so as to reheat the logistics discharged from the recompression compressor and the high-pressure turbine in the regenerator.

[0011] Optionally, a fuel compressor and an oxygen compressor are also included, and the feed inlet of the combustion chamber is connected to the compressed fuel outlet and compressed oxygen outlet of the fuel compressor and the oxygen compressor.

[0012] Optionally, the fuel compressed by the fuel compressor is methane, or a mixture of carbon monoxide and hydrogen.

[0013] Optionally, the water outlet of the separator is connected to a water recovery pipeline.

[0014] Optionally, the condensate outlet of the multi-stage compressor is connected to a condensate recovery pipeline.

[0015] Optionally, the logistics outlet of the multi-stage compressor is also connected to a carbon dioxide storage tank.

[0016] Optionally, the third logistics outlet of the regenerator is connected to the combustion chamber to allow the logistics discharged from the recompression compressor and the high-pressure turbine to participate in the circulation after being reheated.

[0017] The second aspect of the present invention provides a split-flow recompression supercritical CO2 cycle power generation method, based on the split-flow recompression supercritical CO2 cycle power generation system, comprising the following steps:

[0018] The flow S8 discharged from the combustion chamber enters the medium-pressure turbine to perform work and obtains the flow S9, which then enters the hot side of the regenerator to recover heat;

[0019] The stream S10 discharged from the regenerator enters the cooler for further cooling to obtain stream S11, and the stream S11 enters the separator to separate the water therein to obtain stream S1;

[0020] Logistics S1 is divided into two streams: Logistics S1-1 and Logistics S1-2;

[0021] Logistics S1-1 is compressed to the highest cycle pressure in the multi-stage compressor to obtain logistics S2; a portion of logistics S3 is extracted from logistics S2 exiting the multi-stage compressor, and is recompressed and sealed, and the remaining logistics S4 enters the regenerator to absorb the heat of logistics S9 for reheating to obtain logistics S5;

[0022] Logistics S1-2 enters the recompression compressor for recompression into logistics S6-2;

[0023] The reheated logistics S5 enters the high-pressure turbine to perform work to obtain logistics S6-1. Logistics S6-1 is mixed with S6-2 and enters the reheater for further reheating. Logistics S7 exiting the reheater circulates back to the combustion chamber to participate in the cycle again.

[0024] The beneficial effects of the present invention are as follows:

[0025] The split-flow recompression supercritical CO2 cycle power generation system provided in the embodiment of the present invention increases the flow rate and temperature of the cold fluid at the hot end of the regenerator by splitting a portion of the gas flow S1-2 out of the separator, and adding a recompression compressor for recompression, and mixing it with the exhaust gas S6-1 of the high-pressure turbine and entering the regenerator for reheating, which can effectively reduce the heat exchange temperature difference at the hot end. In addition, after adding the recompression compressor, there is no need to set up a reheating device, which can avoid the inlet temperature of the flow at the hot end of the regenerator being too high. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0027] Figure 1Schematic diagram of a split-flow recompression supercritical CO2 cycle power generation system provided in an embodiment of the present invention.

[0028] Figure 2 Schematic diagram of a split-flow recompression supercritical CO2 cycle power generation system provided in a preferred embodiment of the present invention.

[0029] Among them: 1 fuel compressor; 2 oxygen compressor; 3 combustion chamber; 4 medium pressure turbine; 5 recuperator; 6 cooler; 7 separator; 8 recompression compressor; 9 high pressure turbine; 10 multi-stage compressor. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0031] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit exemplary embodiments according to the present invention.

[0032] Example 1

[0033] like Figure 1 As shown, the first aspect of the present invention provides a split-flow recompression supercritical CO2 cycle power generation system, comprising a combustion chamber 3, a medium-pressure turbine 4, a regenerator 5, a cooler 6, a separator 7, a recompression compressor 8, a high-pressure turbine 9 and a multi-stage compressor 10;

[0034] The logistics outlet of the combustion chamber 3 is connected to the logistics inlet of the medium-pressure turbine 4, and the logistics outlet of the medium-pressure turbine 4 is connected to the first logistics inlet of the regenerator 5 for releasing heat in the regenerator 5; the first logistics outlet of the regenerator 5 is connected to the cooler 6 and the separator 7 in sequence;

[0035] As an example, the medium-pressure turbine 4 is a gas turbine.

[0036] The carbon dioxide outlet of the separator 7 is divided into two routes, the first route outlet is connected to the logistics inlet of the multi-stage compressor 10, the logistics outlet of the multi-stage compressor 10 is connected to the second logistics inlet of the regenerator 5, and the logistics discharged from the multi-stage compressor 10 absorbs the heat in the regenerator 5; the second logistics outlet of the regenerator 5 is connected to the high-pressure turbine 9, and the logistics discharged from the multi-stage compressor 10 absorbs the heat of the regenerator 5 and then drives the high-pressure turbine 9;

[0037] The second route of the carbon dioxide outlet of the separator 7 is connected to the logistics inlet of the recompression compressor 8, and the logistics outlet of the recompression compressor 8 and the logistics outlet of the high-pressure turbine 9 are commonly connected to the third logistics inlet of the reheater 5, so as to reheat the logistics discharged from the recompression compressor 8 and the high-pressure turbine 9 in the reheater 5.

[0038] The third logistics outlet of the regenerator 5 is connected to the combustion chamber 3, and is used to allow the logistics discharged from the recompression compressor 8 and the high-pressure turbine 9 to reheat and participate in the circulation, and the temperature of the combustion chamber 3 is controlled by the reflux logistics.

[0039] As an example, the reflux stream S7 is CO2 working fluid.

[0040] The water outlet of the separator 7 is connected to a water recovery pipeline, and the condensate outlet of the multi-stage compressor 10 is connected to a condensate recovery pipeline for recovering excess water at the separation point.

[0041] The logistics outlet of the multi-stage compressor 10 is also connected to a carbon dioxide storage tank, from which a portion of the carbon dioxide is extracted for recompression and storage.

[0042] Example 2

[0043] Based on Example 1, the present invention proposes a preferred Example 2, which further includes a fuel compressor 1 and an oxygen compressor 2, and the feed port of the combustion chamber 3 is connected to the compressed fuel outlet and the compressed oxygen outlet of the fuel compressor 1 and the oxygen compressor 2. By providing compressed oxygen and compressed fuel, the power generation efficiency of the system can be improved.

[0044] As an example, the fuel compressed by the fuel compressor 1 is methane, or a mixture of carbon monoxide and hydrogen.

[0045] The second aspect of the present invention provides a split-flow recompression supercritical CO2 cycle power generation method, based on the above-mentioned split-flow recompression supercritical CO2 cycle power generation system, comprising the following steps:

[0046] The fuel and oxygen are compressed by the fuel compressor 1 and the oxygen compressor 2 respectively and then enter the combustion chamber 3 for combustion. The flow S8 discharged from the combustion chamber 3 enters the medium-pressure turbine 4 to perform work to obtain the flow S9, and the flow S9 enters the hot side of the regenerator 5 to recover most of the heat therein; as an example, the flow S8 is high-temperature fuel gas; the flow S9 is high-temperature flue gas.

[0047] The stream S10 discharged from the regenerator 5 enters the cooler 6 for further cooling to obtain the stream S11, and the stream S11 enters the separator 7 to separate the water therein to obtain the stream S1;

[0048] After the water is separated, the logistics S1 is divided into two streams, logistics S1-1 and logistics S1-2;

[0049] As an example, the stream S1 is carbon dioxide.

[0050] Logistics S1-1 is compressed to the highest cycle pressure in the multi-stage compressor 10 to obtain logistics S2; a portion of logistics S3 is extracted from logistics S2 exiting the multi-stage compressor 10, and is recompressed and sealed, and the remaining logistics S4 enters the regenerator 5 to absorb the heat of logistics S9 for reheating to obtain logistics S5;

[0051] Logistics S1-2 enters the recompression compressor 8 to be recompressed into logistics S6-2;

[0052] The reheated logistics S5 enters the high-pressure turbine 9 to perform work to obtain logistics S6-1. The logistics S6-1 after work is mixed with S6-2 to obtain S6 and enters the reheater 5 for further reheating. The logistics S7 out of the reheater circulates back to the combustion chamber 3 to participate in the cycle again.

[0053] The present invention increases the flow rate and temperature of the cold fluid at the hot end of the regenerator by diverting a portion of the gas from the separator 7 to the flow S1-2, and adding a recompression compressor 8 for recompression, and mixing it with the exhaust gas S6-1 of the high-pressure turbine 9 before entering the regenerator 5 for reheating, which can effectively reduce the heat exchange temperature difference at the hot end. In addition, after adding the recompression compressor, there is no need to set up a reheating device, which can avoid the inlet temperature of the flow at the hot end of the regenerator being too high.

[0054] The present invention eliminates the reheat device, adds the diversion and recompression process, and increases the flow rate of the hot end logistics on the cold side of the regenerator. On the one hand, it can reduce the inlet temperature of the hot logistics at the hot end of the regenerator to avoid technical risks. On the other hand, it can reduce the heat exchange temperature difference at the hot end of the regenerator, improve the heat recovery efficiency, and thus improve the net efficiency of the system.

[0055] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A split-flow recompression supercritical CO2 cycle power generation system, characterized in that: It includes a combustion chamber (3), a medium-pressure turbine (4), a regenerator (5), a cooler (6), a separator (7), a recompression compressor (8), a high-pressure turbine (9) and a multi-stage compressor (10); The logistics outlet of the combustion chamber (3) is connected to the logistics inlet of the medium-pressure turbine (4), and the logistics outlet of the medium-pressure turbine (4) is connected to the first logistics inlet of the regenerator (5) for releasing heat in the regenerator (5); the first logistics outlet of the regenerator (5) is connected to the cooler (6) and the separator (7) in sequence; The carbon dioxide outlet of the separator (7) is divided into two outlets, the first outlet being connected to the logistics inlet of the multi-stage compressor (10), the logistics outlet of the multi-stage compressor (10) being connected to the second logistics inlet of the regenerator (5), so that the logistics discharged from the multi-stage compressor (10) absorbs the heat in the regenerator (5); the second logistics outlet of the regenerator (5) is connected to the high-pressure turbine (9), so that the logistics discharged from the multi-stage compressor (10) absorbs the heat of the regenerator (5) and then drives the high-pressure turbine (9); The second path of the carbon dioxide outlet of the separator (7) is connected to the logistics inlet of the recompression compressor (8), and the logistics outlet of the recompression compressor (8) and the logistics outlet of the high-pressure turbine (9) are connected together to the third logistics inlet of the regenerator (5), so as to reheat the logistics discharged from the recompression compressor (8) and the high-pressure turbine (9) in the regenerator (5); It also includes a fuel compressor (1) and an oxygen compressor (2), wherein the feed port of the combustion chamber (3) is connected to the compressed fuel outlet and the compressed oxygen outlet of the fuel compressor (1) and the oxygen compressor (2); The fuel compressed by the fuel compressor (1) is methane, or a mixture of carbon monoxide and hydrogen; The water outlet of the separator (7) is connected to a water recovery pipeline; The condensate outlet of the multi-stage compressor (10) is connected to a condensate recovery pipeline; The logistics outlet of the multi-stage compressor (10) is also connected to a carbon dioxide storage tank; The third stream outlet of the regenerator (5) is connected to the combustion chamber (3) and is used to reheat the streams discharged from the recompression compressor (8) and the high-pressure turbine (9) and then participate in the circulation.

2. A split-flow recompression supercritical CO2 cycle power generation method, based on the split-flow recompression supercritical CO2 cycle power generation system according to claim 1, characterized in that: The steps include: The material flow S8 discharged from the combustion chamber (3) enters the medium-pressure turbine (4) to perform work to obtain material flow S9, and the material flow S9 enters the regenerator (5) to recover heat on the hot side; The stream S10 discharged from the regenerator (5) enters the cooler (6) for cooling to obtain the stream S11, and the stream S11 enters the separator (7) to separate the water therein to obtain the stream S1; Logistics S1 is divided into two streams: Logistics S1-1 and Logistics S1-2; Logistics S1-1 is compressed to the maximum cycle pressure in the multi-stage compressor (10) to obtain logistics S2; a portion of logistics S3 is extracted from logistics S2 exiting the multi-stage compressor (10), and is recompressed and sealed, and the remaining logistics S4 enters the regenerator (5) to absorb heat from logistics S9 to obtain logistics S5; Logistics S1-2 enters the recompression compressor (8) to be recompressed into logistics S6-2; After the heat recovery, the material flow S5 enters the high-pressure turbine (9) to perform work, thereby obtaining material flow S6-1. The material flow S6-1 is mixed with S6-2 and then enters the regenerator (5) for heat recovery. The material flow S7 exiting the regenerator is circulated back to the combustion chamber (3) to participate in the cycle again.

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