A combined cycle dual flue gas recirculation cooling and heating integrated system and operation method

Abstract

The present invention relates to the technical field of cold and heat integrated systems, and provides a cold and heat integrated system with dual flue gas recirculation in a combined cycle and an operating method. The system comprises at least: a gas turbine; a waste heat boiler, which is arranged downstream of the gas turbine, and an exhaust port is provided at the downstream end of the waste heat boiler; a dryer; a first vaporizer, wherein the first inlet of the first vaporizer is connected to the second branch; and a liquid oxygen-rich gas storage tank, wherein the first outlet of the liquid oxygen-rich gas storage tank is connected to the second inlet of the first vaporizer. The characteristics of the dual flue gas circulation system are that the vaporized oxygen-rich gas is used as the intake air of the gas turbine, thereby increasing the pressure and oxygen content of the circulating flue gas of the gas turbine, while the flue gas in the circulating flue gas of the waste heat boiler is oxygen-poor, thereby preventing high-temperature oxidation corrosion; after drying the circulating flue gas, the circulating flue gas physical properties of the steam cycle and the gas cycle in the waste heat boiler are matched, thereby avoiding changes in the back pressure of the gas turbine when the unit is operated at partial load.

Description

Technical Field

[0001] The present invention relates to the technical field of cooling and heating integration systems, and in particular to a cooling and heating integration system with combined cycle and dual flue gas recirculation and an operation method thereof. Background Art

[0002] Carbon dioxide (CO2) constitutes the largest portion of greenhouse gases and is widely considered the primary contributor to climate change. NOx is also believed to indirectly exacerbate the greenhouse effect through ozone production. Carbon capture, compression and transportation, and reduction of nitrogen oxide emissions are considered potential means to mitigate global warming. However, as power plant efficiency increases and combustion temperatures rise, NOx emissions increase, exacerbating oxidative corrosion of high-temperature heat exchanger materials. Gas turbine flue gas contains approximately 4% CO2 by volume (approximately 4.5% on a dry basis) at near-atmospheric pressure. The low flue gas pressure and density require large piping and equipment, resulting in higher floor space and overall installation costs. To offset this effect, exhaust gas recirculation (EGR) technology has been proposed. This method reduces the total amount of exhaust gas emitted and increases CO2 concentration, thereby reducing power consumption in the CO2 capture and separation systems, increasing capture efficiency, and reducing nitrogen in the flue gas, effectively eliminating NOx emissions.

[0003] However, the current combined cycle flue gas recirculation technology has some problems that need to be solved. On the one hand, for systems that use separate gas turbine flue gas recirculation, the oxygen-depleted flue gas returned to the gas turbine inlet reduces the oxygen content in the intake air, which will lead to incomplete combustion and high CO emissions. In addition, the flue gas temperature is too high, and the ability to compress air is weakened. On the other hand, for systems that use separate waste heat boiler flue gas recirculation, after the CO2 content in the waste heat boiler increases, the flue gas humidity increases and the heat transfer coefficient changes. Therefore, the flue gas volume required for the steam cycle in the waste heat boiler and the flue gas volume of the gas turbine cannot match, resulting in frequent changes in the back pressure of the gas turbine when the unit is operated at partial load. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is that for a system using a separate gas turbine flue gas recirculation, the oxygen-depleted flue gas returned to the compressor inlet reduces the oxygen content in the intake air, which will lead to incomplete combustion and high CO emissions, and the flue gas temperature is too high, which weakens the ability to compress air; for a system using a separate waste heat boiler flue gas recirculation, after the CO2 content in the waste heat boiler increases, the flue gas humidity increases and the heat transfer coefficient changes. Therefore, the flue gas volume required for the steam cycle in the waste heat boiler and the flue gas volume of the gas turbine cannot match, resulting in frequent changes in the back pressure of the gas turbine when the unit is operating at partial load, thereby providing a combined cycle dual flue gas recirculation cold and hot integrated system and operation method.

[0005] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0006] A combined cycle double flue gas recirculation cold and heat integrated system, comprising at least: a gas turbine; a waste heat boiler, arranged downstream of the gas turbine, the outlet of the gas turbine being connected to the inlet of the waste heat boiler, and an exhaust port being provided at the downstream end of the waste heat boiler; a dryer, the inlet of the dryer being connected to the exhaust port of the waste heat boiler, the outlet of the dryer being divided into a first branch and a second branch, the first branch being connected to the inlet of the waste heat boiler; a first gasifier, the first inlet of the first gasifier being connected to the second branch; a liquid oxygen-rich gas storage tank, the first outlet of the liquid oxygen-rich gas storage tank being connected to the second inlet of the first gasifier; wherein the first outlet and the second outlet of the first gasifier are connected to the inlet of the gas turbine after merging.

[0007] Furthermore, the combined cycle dual flue gas recirculation cold and hot integrated system also includes a second gasifier, the first inlet of the second gasifier is connected to the second outlet of the liquid oxygen-rich gas storage tank; the outlet of the waste heat boiler is connected to the second inlet of the second gasifier, and the second outlet of the second gasifier is suitable for connection to the CO2 capture device.

[0008] Furthermore, the dryer is a rotary adsorption dryer, the first outlet of the second vaporizer is connected to the inlet of the rotary adsorption dryer, and is suitable for using the dry gas discharged from the first outlet of the second vaporizer to dehumidify the adsorbent in the rotary adsorption dryer.

[0009] Furthermore, the combined cycle dual flue gas recirculation cold and heat integrated system also includes a heat reservoir, the first branch is connected to the inlet of the heat reservoir, the outlet of the heat reservoir is connected to the inlet of the waste heat boiler, and the heat reservoir is suitable for heating the flue gas returning to the waste heat boiler.

[0010] Furthermore, a damper is provided at the exhaust port of the waste heat boiler, and the damper can adjust the flow rate of the flue gas extracted from the waste heat boiler.

[0011] Furthermore, the combined cycle dual flue gas recirculation cold and heat integrated system also includes a blower, which is arranged between the outlet of the waste heat boiler and the second inlet of the second gasifier, and the blower can adjust the flue gas flow rate entering the second gasifier.

[0012] Furthermore, a first pump body is provided on the pipeline connected to the first outlet of the liquid oxygen-rich gas storage tank, and the first pump body can adjust the flow rate of the oxygen-rich gas entering the first vaporizer; a second pump body is provided on the pipeline connected to the second outlet of the liquid oxygen-rich gas storage tank, and the second pump body can adjust the flow rate of the oxygen-rich gas entering the second vaporizer.

[0013] Furthermore, a pressure monitoring sensor is provided at the inlet of the gas turbine; a temperature monitoring sensor is provided at the inlet of the waste heat boiler; and a CO2 monitoring sensor is provided at the outlet of the waste heat boiler.

[0014] A method for operating a combined cycle dual flue gas recirculation cold and heat integrated system comprises any one of the above-mentioned combined cycle dual flue gas recirculation cold and heat integrated systems, and the specific operating method is as follows: drying the circulating flue gas flowing out of the waste heat boiler; dividing the dried circulating flue gas into two parts, one part of the dried circulating flue gas flowing into the inlet of the gas turbine, and the other part of the dried circulating flue gas flowing into the inlet of the waste heat boiler; before the dried circulating flue gas flows into the inlet of the gas turbine, utilizing the heat carried by the circulating flue gas to vaporize the liquid oxygen-rich gas, and then mixing the heat-released circulating flue gas with the vaporized oxygen-rich gas and transporting them to the inlet of the gas turbine.

[0015] Furthermore, the dried circulating flue gas is heated before flowing into the inlet of the waste heat boiler.

[0016] Furthermore, when the CO2 content in the circulating flue gas in the waste heat boiler exceeds the limit, the circulating flue gas is discharged from the outlet of the waste heat boiler; the circulating flue gas to be subjected to CO2 capture is cooled; and CO2 is fractionated from the cooled circulating flue gas and made into dry ice.

[0017] Furthermore, the mixed gas of nitrogen and oxygen contained in the circulating flue gas after CO2 capture is transported to the inlet of the gas turbine.

[0018] Furthermore, cooling the circulating flue gas to be captured by CO2 specifically includes the following steps: using liquid oxygen-rich gas to cool the circulating flue gas to be captured by CO2; using the oxygen-rich gas after endothermic vaporization to dehumidify the adsorbent in the dryer; and passing the oxygen-rich gas used to dehumidify the adsorbent in the dryer into the inlet of the gas turbine.

[0019] Furthermore, the CO2 concentration in the flue gas downstream of the waste heat boiler is monitored in real time; when the CO2 concentration in the flue gas is higher than the limit, the flow rate of the circulating flue gas output from the exhaust port of the waste heat boiler is reduced, and the flow rate of the circulating flue gas used for CO2 capture in the waste heat boiler is increased.

[0020] Furthermore, the steam temperature in the superheater of the waste heat boiler is monitored in real time; when the steam temperature is higher than the upper limit or lower than the lower limit, the recirculated flue gas flow delivered to the waste heat boiler is reduced or suspended, and the recirculated flue gas flow delivered to the gas turbine is increased.

[0021] Furthermore, the intake pressure of the gas turbine compressor is monitored in real time; when the intake pressure is higher than the upper limit, the flow rate of the gasified oxygen-rich gas entering the gas turbine is reduced, and the flow rate of the normal-pressure ambient air entering the gas turbine is increased, and correction is performed by adjusting the ratio of the two.

[0022] The technical solution of the present invention has the following advantages:

[0023] The combined cycle dual flue gas recirculation cold and hot integrated system provided by the present invention dries the circulating flue gas flowing out of the waste heat boiler; the dried circulating flue gas is divided into two parts, one part of the dried circulating flue gas flows into the inlet of the gas turbine, and the other part of the dried circulating flue gas flows into the inlet of the waste heat boiler; before the dried circulating flue gas flows into the inlet of the gas turbine, the heat carried by the circulating flue gas is used to vaporize the liquid oxygen-rich gas, and then the circulating flue gas after heat release is mixed with the vaporized oxygen-rich gas and transported to the inlet of the gas turbine. In such a dual-cycle setting, the gasified oxygen-rich gas serves as the intake air for the gas turbine, which increases the pressure and oxygen content of the gas turbine fuel gas. CO reacts more easily with oxygen to form CO2, reducing the CO content in the flue gas. However, the flue gas circulation of the waste heat boiler ensures that the flue gas in the waste heat boiler is oxygen-poor, preventing high-temperature metal oxidation corrosion; moreover, the reduced oxygen content in the waste heat boiler can prevent oxidation corrosion of the heat exchanger material; moreover, after the CO2 concentration increases, the volume flow of the flue gas in the waste heat boiler and the volume flow through the CO2 capture device decreases, and the lower volume flow also reduces the pressure drop of the system, which is beneficial to the overall performance of the combined cycle and allows the use of smaller and cheaper heat exchange equipment; moreover, after the circulating flue gas is dried, the humidity of the circulating flue gas is reduced, so that the flue gas volume required for the steam cycle in the waste heat boiler and the flue gas volume of the gas turbine can match, avoiding frequent changes in the back pressure of the gas turbine when the unit is operating at partial load. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 Schematic diagram of a combined cycle dual flue gas recirculation cooling and heating integrated system in an embodiment of the present invention;

[0026] Figure 2 Schematic diagram of a rotary adsorption dryer in a combined cycle dual flue gas recirculation cold and hot integrated system in an embodiment of the present invention.

[0027] 1. Compressor; 2. Combustion chamber; 3. Turbine; 4. Waste heat boiler; 41. Superheater; 42. Evaporator; 43. Preheater; 44. Chimney; 5. Oxygen-enriched liquid gas storage tank; 6. First pump body; 7. First vaporizer; 8. Second pump body; 9. Second vaporizer; 10. Fractionator; 11. Blower; 12. Rotary adsorption dryer; 13. Heat storage tank; 14. Pressure monitoring point; 15. Temperature monitoring point; 16. CO2 monitoring point; 17. Adsorbent. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0031] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Figure 1 Schematic diagram of a combined cycle dual flue gas recirculation cooling and heating integrated system in an embodiment of the present invention; Figure 1As shown, it should be noted that Figure 1 In the figure, the dotted line represents air (or oxygen) and the solid line represents flue gas.

[0033] The present embodiment provides a combined cycle dual flue gas recirculation cold and heat integrated system, which at least includes: a gas turbine; a waste heat boiler 4, which is arranged downstream of the gas turbine, the outlet of the gas turbine is connected to the inlet of the waste heat boiler 4, and the downstream end of the waste heat boiler 4 is provided with an exhaust port; a dryer, the inlet of the dryer is connected to the exhaust port of the waste heat boiler 4, and the outlet of the dryer is divided into a first branch and a second branch, and the first branch is connected to the inlet of the waste heat boiler 4; a first vaporizer 7, the first inlet of the first vaporizer 7 is connected to the second branch; a liquid oxygen-rich gas storage tank, the first outlet of the liquid oxygen-rich gas storage tank is connected to the second inlet of the first vaporizer 7; wherein the first outlet and the second outlet of the first vaporizer 7 are connected to the inlet of the gas turbine after merging.

[0034] The combined cycle dual flue gas recirculation cold and hot integrated system provided in this embodiment dries the circulating flue gas flowing out of the waste heat boiler 4; the dried circulating flue gas is divided into two parts, one part of the dried circulating flue gas flows into the inlet of the gas turbine, and the other part of the dried circulating flue gas flows into the inlet of the waste heat boiler 4; before the dried circulating flue gas flows into the inlet of the gas turbine, the heat carried by the circulating flue gas is used to vaporize the liquid oxygen-rich gas, and then the circulating flue gas after releasing heat is mixed with the vaporized oxygen-rich gas and transported to the inlet of the gas turbine. In such a dual-circulation setting, the gasified oxygen-rich gas serves as the intake air for the gas turbine, which increases the pressure and oxygen content of the gas turbine fuel gas. CO reacts more easily with oxygen to form CO2, reducing the CO content in the flue gas. However, the flue gas circulation of the waste heat boiler ensures that the flue gas in the waste heat boiler is oxygen-poor, preventing high-temperature metal oxidation corrosion; moreover, the oxygen content in the waste heat boiler 4 is reduced, which can prevent oxidation corrosion of the heat exchanger material; moreover, after the CO2 concentration increases, the volume flow of the flue gas in the waste heat boiler 4 and the volume flow through the CO2 capture device is reduced, and the lower volume flow also reduces the pressure drop of the system, which is beneficial to the overall performance of the combined cycle and allows the use of smaller and cheaper heat exchange equipment; moreover, after the circulating flue gas is dried, the humidity of the circulating flue gas is reduced, so that the flue gas volume required for the steam cycle in the waste heat boiler 4 and the flue gas volume of the gas turbine can match, avoiding frequent changes in the back pressure of the gas turbine when the unit is operating at partial load.

[0035] Among them, the combined cycle dual flue gas recirculation cold and hot integrated system also includes a second gasifier 9, the first inlet of the second gasifier 9 is connected to the second outlet of the liquid oxygen-rich gas storage tank; the outlet of the waste heat boiler 4 is connected to the second inlet of the second gasifier 9, and the second outlet of the second gasifier 9 is suitable for connection to the CO2 capture device.

[0036] Figure 2Schematic diagram of a rotary adsorption dryer in a combined cycle dual flue gas recirculation cold and hot integrated system in an embodiment of the present invention; Figure 2 As shown, the dryer is a rotary adsorption dryer 12, and the first outlet of the second vaporizer 9 is connected to the inlet of the rotary adsorption dryer 12, which is suitable for using the dry gas discharged from the first outlet of the second vaporizer 9 to dehumidify the adsorbent 17 in the rotary adsorption dryer 12.

[0037] Among them, the combined cycle dual flue gas recirculation cold and heat integrated system also includes a heat reservoir 13, the first branch is connected to the inlet of the heat reservoir 13, and the outlet of the heat reservoir 13 is connected to the inlet of the waste heat boiler 4. The heat reservoir 13 is suitable for heating the flue gas returning to the waste heat boiler 4.

[0038] Among them, a damper is provided at the exhaust port of the waste heat boiler 4, and the damper can adjust the flow rate of the flue gas extracted from the waste heat boiler 4.

[0039] Among them, the combined cycle dual flue gas recirculation cold and hot integrated system also includes a blower 11, which is arranged between the outlet of the waste heat boiler 4 and the second inlet of the second gasifier 9. The blower 11 can adjust the flue gas flow rate entering the second gasifier 9.

[0040] Among them, a first pump body 6 is provided on the pipeline connected to the first outlet of the liquid oxygen-rich gas storage tank, and the first pump body 6 can adjust the flow rate of the oxygen-rich gas entering the first vaporizer 7; a second pump body 8 is provided on the pipeline connected to the second outlet of the liquid oxygen-rich gas storage tank, and the second pump body 8 can adjust the flow rate of the oxygen-rich gas entering the second vaporizer 9.

[0041] Among them, a pressure monitoring sensor is provided at the inlet position of the gas turbine; a temperature monitoring sensor is provided at the inlet position of the waste heat boiler 4; and a CO2 monitoring sensor is provided at the outlet position of the waste heat boiler 4.

[0042] Another embodiment provides an operating method of a combined cycle dual flue gas recirculation cold and heat integrated system, including any of the above-mentioned combined cycle dual flue gas recirculation cold and heat integrated systems, and the specific operating method is as follows: drying the circulating flue gas flowing out of the waste heat boiler 4; dividing the dried circulating flue gas into two parts, one part of the dried circulating flue gas flows into the inlet of the gas turbine, and the other part of the dried circulating flue gas flows into the inlet of the waste heat boiler 4; before the dried circulating flue gas flows into the inlet of the gas turbine, utilizing the heat carried in the circulating flue gas to vaporize the liquid oxygen-rich gas, and then mixing the heat-released circulating flue gas with the vaporized oxygen-rich gas and transporting them to the inlet of the gas turbine.

[0043] Here, before the dried circulating flue gas flows into the inlet of the waste heat boiler 4, the circulating flue gas is heated and heated.

[0044] Among them, when the CO2 content in the circulating flue gas in the waste heat boiler 4 exceeds the limit, the circulating flue gas is discharged from the outlet of the waste heat boiler 4; the circulating flue gas to be used for CO2 capture is cooled; CO2 is fractionated from the cooled circulating flue gas and made into dry ice.

[0045] The mixed gas of nitrogen and oxygen contained in the circulating flue gas after CO2 capture is transported to the inlet of the gas turbine.

[0046] Among them, cooling the circulating flue gas to be captured by CO2 specifically includes the following steps: using liquid oxygen-rich gas to cool the circulating flue gas to be captured by CO2; using the oxygen-rich gas after endothermic vaporization to dehumidify the adsorbent 17 in the dryer; and passing the oxygen-rich gas used to dehumidify the adsorbent 17 in the dryer into the inlet of the gas turbine.

[0047] Among them, the CO2 concentration in the flue gas downstream of the waste heat boiler 4 is monitored in real time; when the CO2 concentration in the flue gas is higher than the limit, the flow rate of the circulating flue gas output from the exhaust port of the waste heat boiler 4 is reduced, and the flow rate of the circulating flue gas used for CO2 capture by the waste heat boiler 4 is increased.

[0048] The steam temperature in the superheater 41 of the waste heat boiler 4 is monitored in real time. When the steam temperature is higher than the upper limit or lower than the lower limit, the flow of recirculated flue gas delivered to the waste heat boiler 4 is reduced or suspended, and the flow of recirculated flue gas delivered to the gas turbine is increased.

[0049] Among them, the intake pressure of the compressor 1 of the gas turbine is monitored in real time; when the intake pressure is higher than the upper limit, the flow rate of the gasified oxygen-rich gas entering the gas turbine is reduced, and the flow rate of the ambient air at normal pressure entering the gas turbine is increased, and correction is performed by adjusting the ratio of the two.

[0050] Specifically, the combined cycle dual flue gas recirculation integrated cooling and heating system provided in this embodiment includes a gas turbine and a waste heat boiler (HRSG) 4 downstream of the gas turbine. The gas turbine comprises a compressor 1, a combustion chamber 2, and a turbine 3; the HRSG 4 includes at least one superheater 41, an evaporator 42, and a preheater 43. The flue gas recirculation pipeline of the HRSG 4 is equipped with an air extraction port within the HRSG 4. Multiple controllable dampers adapted to the air extraction port can regulate the extraction rate of the circulating flue gas.

[0051] The recirculated flue gas flow flowing out from the exhaust port downstream of the waste heat boiler 4 passes through a rotary flue gas drying device to remove water vapor, and is then split into two parts. The first part of the flow is returned to the inlet of the gas turbine through a recirculation pipeline, and the second part of the flow is directed back to the inlet of the waste heat boiler 4.

[0052] The recirculated flue gas from the gas turbine then flows into the first gasifier 7, is cooled by the low-temperature liquid oxygen-rich gas, mixed with the high-pressure gas formed by the vaporization of the liquid oxygen-rich gas and the ambient air, and then enters the compressor 1 at a relatively low temperature and high pressure.

[0053] The recycled flue gas of the waste heat boiler 4 then flows into the heat storage tank 13 and is heated by the heat storage medium in the liquid storage tank, and the high-temperature air enters the upstream air outlet of the waste heat boiler 4.

[0054] For example, heat reservoir 13 could be a shell-and-shell heat exchanger, with an inner shell storing volcanic rock and an outer shell circulating gas. Baffles are used between the inner and outer shells to increase the heat exchange area. The solid heat storage material within heat reservoir 13 could be approximately 1,000 tons of volcanic rock, capable of heating the entire power plant's flue gas to a temperature of up to 500°C.

[0055] The gas output from the liquid oxygen-rich gas storage tank is divided into two parts. One part enters the first vaporizer 7 to cool the circulating flue gas from the gas turbine. The vaporized high-pressure gas is then mixed with the intake air of compressor 1 and can also be discharged into the atmosphere. The other part enters the carbon capture device to cool the flue gas from the chimney 44 of the waste heat boiler 4. Then, through compression and fractionation, dry ice is captured. The resulting nitrogen and oxygen mixture, after carbon dioxide is removed, has high pressure and low temperature characteristics and can be returned to compressor 1 to mix with the intake air of compressor 1.

[0056] From the cold start of the combined cycle power plant to the full load state, the waste heat boiler 4 flue gas with high CO2, low nitrogen and low oxygen content is generated through flue gas recirculation carbon capture.

[0057] A CO2 monitoring sensor capable of monitoring CO2 concentration is installed at the flue gas outlet of waste heat boiler 4, responding to and adjusting the impact of increased carbon dioxide content and decreased nitrogen content in the recirculated flue gas. When the amount of CO2 in the exhaust gas circulating in waste heat boiler 4 exceeds the limit, the flue gas, which has passed through the pollutant treatment in chimney 44, needs to be regularly subjected to CO2 capture treatment. The flue gas is liquefied by the heat-absorbing and vaporizing cold energy of the liquid oxygen-rich gas, and the CO2 is then low-temperature distilled in fractionator 10 to produce dry ice (the freezing point of CO2 is -78.5°C). The remaining low-temperature, oxygen-enriched oxygen and nitrogen mixture, which does not contain CO2, is transported via a pipeline to the inlet of compressor 1 as the gas turbine intake air.

[0058] For example, captured carbon dioxide dry ice could be used as a raw material for food processing or transported and injected into storage caverns. Captured and fractionated argon could also be used as a raw material for chemical plants.

[0059] For example, the liquid oxygen-rich gas can be liquid air or liquid pure oxygen. When the liquid air comes from a liquid air source, the liquid air can be produced outside the power plant and transported to the liquid oxygen-rich gas storage tank within the power plant via tanker trucks, thus eliminating the need for an additional liquefaction unit.

[0060] Among them, the amount of gas in the liquid oxygen-rich gas storage tank increases as the liquid air energy storage system is charged and decreases as the energy storage system releases energy.

[0061] For example, a liquid air energy storage system consists of insulated tanks maintained at one or more atmospheric pressures. A cryogenic liquid can be stored in separate tanks and integrated into a single system. Although evaporation losses occur due to heat transfer from the environment, the cryogenic liquid (approximately -180°C) can be stored for long periods of time, making it convenient for storing energy on weekends, at night, or when electricity is cheap.

[0062] For example, both the first pump body 6 and the second pump body 8 can be variable frequency pumps. After vaporization, the liquid air becomes gaseous and its volume increases. The necessary pressure is maintained by one or more first pump bodies 6 or second pump bodies 8, and the air can be pumped to a pressure of about 35 bar. The air output by the first vaporizer 7 and the second vaporizer 9 can reach a pressure of about 35 bar and a temperature of -173°C. The heat of the dry flue gas is sufficient to provide auxiliary heat for the process of evaporating the liquid air into gas in the first vaporizer 7. The vaporized air and flue gas are mixed, and the flue gas temperature drops to room temperature, which is suitable as the intake air of the compressor 1.

[0063] For example, the low-temperature solidification fractionation carbon dioxide system of air is also applicable to a mixture of nitrogen and oxygen as the main components, which defaults to the proportion of natural air.

[0064] The CO2 concentration in the recycled flue gas is proportional to the recirculation rate, which is limited by the minimum oxygen concentration required to operate the gas turbine. To increase operational flexibility and further increase the CO2 concentration in the flue gas, liquid oxygen (oxygen or an oxygen-enriched air mixture) can be used instead of liquid air as the medium for the cold energy storage system, enriching the gas at the inlet of Compressor 1.

[0065] For example, the solid heat storage material in heat reservoir 13 can be volcanic rock, a cheap and environmentally friendly heat storage solution that can be contained in the heat storage core and intermittently heated using excess electricity from the grid. Other forms of heat storage materials, such as ceramics, sand, glass, molten salt, or molten aluminum, can also be used. Liquids can also be used.

[0066] The rotary adsorption dryer 12 in the present application is made of an adsorbent 17 and a metal frame having a honeycomb inner structure and a disc-shaped outer structure. As air flows through the rotary adsorption dryer 12 and contacts the adsorbent 17, moisture in the air is absorbed and oil is adsorbed, significantly increasing the moisture content of the adsorbent 17. The rotary adsorption dryer 12 can rotate continuously at a relatively low speed. Air is guided by the blower 11 through a portion of the rotary adsorption dryer 12, while another portion is exposed to dry, hot air. The hot, dry air removes moisture from the rotary adsorption dryer 12. Because the combined cycle exhaust gas is approximately 90-110°C, the liquefied air vaporizes and absorbs heat to form dry air, which is sufficient to dehumidify the moisture-containing adsorbent 17 in the rotary adsorption dryer 12.

[0067] During use, wet flue gas at 80-110 degrees Celsius is sucked in by the fan. A series of honeycomb porous metal structures are installed in the device to increase the area of the adsorbent 17 in contact with water vapor. The wet flue gas and dry air are both sucked in and sent out from the same side, each passing through half of the disc drying device, allowing half of the disc to have adsorbent 17. The adsorbent 17 can be solid silica gel, which can dry the flowing wet flue gas and absorb the moisture content in the air. When the moisture content of this half of the disc drying device is too high to dry, the disc slowly rotates around the axis, and the disc receives the flowing dry air, and the adsorbent 17 discharges moisture.

[0068] Among them, at least one pressure monitoring point 14 needs to be set at the inlet position of the gas turbine and a pressure monitoring sensor needs to be installed; at least one temperature monitoring point 15 needs to be set at the inlet position of the waste heat boiler 4 and a temperature monitoring sensor needs to be installed; at least one CO2 monitoring point 16 needs to be set at the outlet position of the waste heat boiler 4.

[0069] During operation, once it is monitored that the CO2 emission in the flue gas downstream of the waste heat boiler 4 rises above the threshold, the damper at the exhaust port of the waste heat boiler 4 is closed to reduce the amount of recirculated flue gas at the exhaust port downstream of the waste heat boiler 4, and increase the flow rate of flue gas delivered to the carbon capture device by the blower 11.

[0070] During operation, if it is detected that the intake air pressure of the compressor 1 is too high, which may affect the normal operation of the compressor 1 and the combustion chamber 2, the flow rate of the oxygen-enriched gas fed into the first gasifier 7 is reduced (the reduced gas is discharged to the atmosphere), and then the ambient air at normal pressure is increased as the intake air of the compressor 1. Proportional control can be used for correction.

[0071] During operation, once the steam measurement temperature of the superheater 41 is monitored to be higher than the upper threshold or lower than the lower threshold, indicating that the heat storage device 13 cannot operate normally, the recirculated flue gas flow of the waste heat boiler 4 is reduced or shut down, and the recirculated flue gas flow delivered to the inlet of the compressor 1 is increased.

[0072] During operation, if the liquid oxygen-rich gas in the liquid oxygen-rich gas storage tank is insufficient, the carbon capture device will be shut down.

[0073] During operation, the thresholds for pressure, temperature and CO2 concentration or the correction of flue gas flow rate depend on the operating load of the unit.

[0074] The combined cycle dual flue gas recirculation cold and hot integrated system in this application utilizes the low-temperature, high-pressure gas vaporized from the oxygen-rich liquid gas as the intake air for compressor 1, maintaining the low temperature and high pressure of the intake air for compressor 1, and maximizing the CO2 content in the gas turbine exhaust and reducing the NOx content when there is sufficient oxygen required for the fuel.

[0075] The combined cycle dual flue gas recirculation integrated cold and heat system in this application utilizes the peak-shaving characteristics to draw electricity to supply heat to the heat storage device 13 during low electricity consumption, and uses the stored heat to heat the recirculated flue gas from the waste heat boiler 4 during peak electricity consumption, thereby maximizing the CO2 content while keeping the flue gas from the waste heat boiler 4 high temperature and dry.

[0076] The combined cycle dual flue gas recirculation cold and heat integrated system in this application utilizes flue gas recirculation technology to improve the ability of the carbon capture device to absorb CO2, and utilizes the cold energy of the oxygen-rich liquid gas to reduce the operating temperature of the flue gas carbon capture device of the waste heat boiler 4, thereby achieving efficient solidification and fractionation of dry ice. The remaining low-temperature oxygen and nitrogen return to the air system of compressor 1 to form oxygen-rich intake air.

[0077] The combined cycle dual flue gas recirculation cold and heat integrated system in this application organically combines liquid air, heat storage system and combined cycle flue gas recirculation system, and uses renewable energy to reduce CO2 emissions from combined cycle power plants.

[0078] In the combined cycle dual flue gas recirculation integrated cold and hot system of the present application, the nitrogen content in the flue gas recirculation system of the waste heat boiler 4 is reduced, the formation of nitrogen oxides is reduced, and the capture and storage of exhaust carbon dioxide are promoted to obtain a commercial product in the form of dry ice.

[0079] In the combined cycle dual flue gas recirculation integrated cooling and heating system of the present application, the oxygen content (about 12% by volume) in the flue gas of the waste heat boiler 4 is reduced, which can prevent oxidation corrosion of the heater material.

[0080] In the combined cycle dual flue gas recirculation cold and hot integrated system of the present application, liquefied air is vaporized as the air intake of compressor 1, which increases the pressure of the fuel gas and can reduce the CO in the flue gas. Under high pressure, CO is more likely to react with oxygen to form CO2, but the flue gas circulation of the waste heat boiler ensures that the flue gas in the waste heat boiler is oxygen-poor, preventing high-temperature metal oxidation corrosion.

[0081] In the combined cycle dual flue gas recirculation cold and hot integrated system of the present application, a higher recirculation rate of the waste heat boiler 4 will not only increase the CO2 concentration, but also reduce the volume flow of the flue gas in the waste heat boiler 4 and the volume flow through the CO2 capture system. The lower volume flow also reduces the pressure drop of the system, which is beneficial to the overall performance of the combined cycle and allows the use of smaller and cheaper heat exchange equipment.

[0082] The combined cycle dual flue gas recirculation cold and heat integrated system in this application combines the daily start and stop peak regulation of the combined cycle power plant with renewable energy power generation to improve power generation efficiency and power, and uses renewable energy to produce liquid air and high-temperature solid heat storage materials, which can improve the performance and flexibility of the power plant.

[0083] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A combined cycle dual flue gas recirculation cooling and heating integrated system, characterized in that: At least: gas turbine; A waste heat boiler is arranged downstream of the gas turbine, the outlet of the gas turbine is connected to the inlet of the waste heat boiler, and an exhaust port is provided at the downstream end of the waste heat boiler; a dryer, wherein the inlet of the dryer is connected to the exhaust port of the waste heat boiler, and the outlet of the dryer is divided into a first branch and a second branch, and the first branch is connected to the inlet of the waste heat boiler; a first gasifier, wherein a first inlet of the first gasifier is connected to the second branch; a liquid oxygen-rich gas storage tank, wherein a first outlet of the liquid oxygen-rich gas storage tank is connected to a second inlet of the first vaporizer; The first outlet and the second outlet of the first gasifier are connected to the inlet of the gas turbine after merging; Also included is a second vaporizer, wherein a first inlet of the second vaporizer is connected to a second outlet of the liquid oxygen-rich gas storage tank; The outlet of the waste heat boiler is connected to the second inlet of the second gasifier, and the second outlet of the second gasifier is suitable for being connected to the CO2 capture device; The dryer is a rotary adsorption dryer, the first outlet of the second vaporizer is connected to the inlet of the rotary adsorption dryer, and is suitable for using the dry gas discharged from the first outlet of the second vaporizer to dehumidify and regenerate the adsorbent in the rotary adsorption dryer; It also includes a heat reservoir, the first branch is connected to the inlet of the heat reservoir, the outlet of the heat reservoir is connected to the inlet of the waste heat boiler, and the heat reservoir is suitable for heating the flue gas returning to the waste heat boiler.

2. The combined cycle dual flue gas recirculation cooling and heating integrated system according to claim 1, characterized in that: The exhaust port of the waste heat boiler is provided with an air damper, which can adjust the flow rate of the flue gas extracted from the waste heat boiler.

3. The combined cycle dual flue gas recirculation cooling and heating integrated system according to claim 1, characterized in that: The system further includes a blower, which is disposed between the outlet of the waste heat boiler and the second inlet of the second gasifier. The blower can adjust the flow rate of the flue gas entering the second gasifier.

4. The combined cycle dual flue gas recirculation cooling and heating integrated system according to claim 1, characterized in that: A first pump body is provided on a pipeline connected to the first outlet of the liquid oxygen-rich gas storage tank, and the first pump body is capable of adjusting the flow rate of the oxygen-rich gas entering the first vaporizer; A second pump body is provided on the pipeline connected to the second outlet of the liquid oxygen-rich gas storage tank. The second pump body can adjust the flow rate of the oxygen-rich gas entering the second gasifier.

5. The combined cycle dual flue gas recirculation cooling and heating integrated system according to claim 1, characterized in that: A pressure monitoring sensor is provided at the inlet of the gas turbine; A temperature monitoring sensor is provided at the inlet of the waste heat boiler; A CO2 monitoring sensor is provided at the outlet of the waste heat boiler.

6. A method for operating a combined cycle dual flue gas recirculation cooling and heating integrated system, characterized in that: The cold and heat integrated system comprising the combined cycle dual flue gas recirculation according to any one of claims 1 to 5, wherein the specific operation method is as follows: Drying the circulating flue gas flowing out of the waste heat boiler; The dried circulating flue gas is divided into two parts, one part of the dried circulating flue gas flows into the inlet of the gas turbine, and the other part of the dried circulating flue gas flows into the inlet of the waste heat boiler; Before the dried circulating flue gas flows into the inlet of the gas turbine, the heat carried by the circulating flue gas is used to vaporize the liquid oxygen-rich gas, and then the circulating flue gas after releasing heat is mixed with the vaporized oxygen-rich gas and transported to the inlet of the gas turbine.

7. The method for operating a combined cycle dual flue gas recirculation cooling and heating integrated system according to claim 6, characterized in that: Before the dried circulating flue gas flows into the inlet of the waste heat boiler, the circulating flue gas is heated to increase its temperature.

8. The method for operating a combined cycle dual flue gas recirculation cooling and heating integrated system according to claim 6, characterized in that: When the CO2 content in the circulating flue gas in the waste heat boiler exceeds the limit, the circulating flue gas is discharged from the outlet of the waste heat boiler; Cooling the circulating flue gas to be captured by CO2; CO2 is fractionated from the cooled circulating flue gas and made into dry ice.

9. The method for operating a combined cycle dual flue gas recirculation cooling and heating integrated system according to claim 8, characterized in that: The mixed gas of nitrogen and oxygen contained in the circulating flue gas after CO2 capture is transported to the inlet of the gas turbine.

10. The method for operating a combined cycle dual flue gas recirculation cooling and heating integrated system according to claim 8, characterized in that: Cooling the circulating flue gas to be captured by CO2 specifically includes the following steps: Liquid oxygen-rich gas is used to cool the circulating flue gas to be captured for CO2; The oxygen-rich gas after endothermic vaporization is used to dehumidify the adsorbent in the dryer; The oxygen-rich gas used to dehumidify the adsorbent in the dryer is introduced into the inlet of the gas turbine.

11. The method for operating a combined cycle dual flue gas recirculation cooling and heating integrated system according to any one of claims 8 to 10, characterized in that: Real-time monitoring of CO2 concentration in the flue gas downstream of the waste heat boiler; When the CO2 concentration in the flue gas is higher than the limit, the flow rate of the circulating flue gas output from the exhaust port of the waste heat boiler is reduced, and the flow rate of the circulating flue gas used for CO2 capture in the waste heat boiler is increased.

12. The method for operating a combined cycle dual flue gas recirculation cooling and heating integrated system according to any one of claims 8 to 10, characterized in that: Real-time monitoring of steam temperature in the superheater of the waste heat boiler; When the steam temperature is higher than the upper limit or lower than the lower limit, the recirculating flue gas flow delivered to the waste heat boiler is reduced or suspended, and the recirculating flue gas flow delivered to the gas turbine is increased.

13. The method for operating a combined cycle dual flue gas recirculation cooling and heating integrated system according to any one of claims 8 to 10, characterized in that: Real-time monitoring of the gas turbine compressor inlet pressure; When the intake pressure is higher than the upper limit, the flow of the gasified oxygen-rich gas entering the gas turbine is reduced, and the flow of the ambient air at normal pressure entering the gas turbine is increased, and correction is performed by adjusting the ratio of the two.

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