A gas turbine exhaust afterburner recirculation system

Abstract

The utility model discloses a kind of gas turbine exhaust afterburning recirculation systems, belong to gas turbine technical field, including gas turbine and the waste heat boiler connected in the gas turbine exhaust end by flue, the supplementary combustion subassembly is arranged in the flue, the supplementary combustion subassembly is connected with the fuel inlet of the gas turbine by recirculation pipeline, the flue outside is connected with combustion-supporting subassembly.The utility model improves flue gas heat grade and steam production by exhaust afterburning recirculation technology, and energy efficiency is improved and environmental protection is considered;Recirculation flue gas is used to dynamically adjust combustion temperature, support multi-fuel mixed combustion and eliminate switching risk;Adopt double mode intelligent regulation and control and shutdown independent energy supply mechanism, rapidly respond demand fluctuation;Integrated design significantly reduces equipment volume and structural complexity, greatly saves cost, help to promote the sustained development of gas turbine technology.

Description

Technical Field

[0001] This utility model relates to the field of gas turbine technology, and in particular to a gas turbine exhaust gas afterburning and recirculation system. Background Technology

[0002] Gas turbines, due to their high efficiency and cleanliness, have been widely used against the backdrop of increasing energy demand and the need for improved energy efficiency. In recent years, their development has focused on reducing energy consumption and emissions, and improving thermal efficiency. To further optimize performance, improve fuel utilization, and ultimately achieve zero carbon emissions and energy self-sufficiency, exhaust gas afterburning and recycling technologies have become a research hotspot.

[0003] In the prior art, the invention patent with publication number CN119412719B entitled "A Hydrogen Supplementation Combustion Control System and Method in a Gas Turbine Waste Heat Boiler" discloses a hydrogen supplementation combustion control system. In this system, hydrogen supplementation combustion needs to coordinate multiple subsystems such as natural gas and hydrogen supply, natural gas and hydrogen supplementation combustion ratio, loop control, and combustion module, which significantly increases the system complexity and equipment cost.

[0004] Based on the system complexity and high cost challenges of the existing technologies, a novel gas turbine exhaust afterburning and recirculation system is proposed. Utility Model Content

[0005] The purpose of this invention is to provide a gas turbine exhaust gas recirculation system to solve the problems in the background art.

[0006] To achieve the above objectives, this utility model provides a gas turbine exhaust gas afterburning and recirculation system, including a gas turbine and a waste heat boiler connected to the exhaust end of the gas turbine via a flue. An afterburning component is installed in the flue, and the afterburning component is connected to the fuel inlet of the gas turbine via a recirculation pipe. An auxiliary combustion component is connected to the outside of the flue.

[0007] Preferably, the gas turbine includes a main shaft and a generator, a compressor, and a turbine sequentially arranged on the main shaft. The output end of the generator is connected to a power grid, a combustion chamber is provided between the compressor and the turbine, and the exhaust end of the turbine is connected to the flue.

[0008] Preferably, the afterburning assembly includes an afterburning burner, an afterburning valve group, and a flue valve. The afterburning valve group is connected to the fuel inlet of the afterburning burner via a fuel pipeline, and the flue valve is disposed on the flue between the afterburning burner and the turbine.

[0009] Preferably, one end of the recirculation pipe is connected to the exhaust port of the exhaust valve, and the other end of the recirculation pipe is connected to the fuel inlet of the combustion chamber.

[0010] Preferably, the combustion-supporting component includes a combustion-supporting pipe and a combustion-supporting fan, a combustion-supporting air valve, and a combustion-supporting burner arranged sequentially within the combustion-supporting pipe. The tail end of the combustion-supporting pipe is connected to the flue between the exhaust valve and the combustion-supporting burner, and the fuel inlet of the combustion-supporting burner is connected to a combustion-supporting valve assembly through the fuel pipe.

[0011] Therefore, the gas turbine exhaust gas afterburning and recirculation system of the present invention, which adopts the above-described structure, has the following beneficial effects:

[0012] (1) By using exhaust gas re-burning and recirculation technology, the high-temperature exhaust gas from the gas turbine is reintroduced into the combustion chamber and re-burning components for secondary combustion, which significantly improves the heat quality of the flue gas, reduces the heat loss of the exhaust gas, and greatly increases the steam output of the waste heat boiler, thus improving both energy efficiency and environmental performance.

[0013] (2) By dynamically adjusting the combustion temperature through recirculated flue gas, the risk of combustion oscillation or flameout during fuel switching is eliminated, supporting the mixed combustion of multiple fuels and increasing the stability of system operation; in the gas turbine shutdown mode, the supplementary combustion component, the combustion-supporting component and the waste heat boiler are combined into an independent gas boiler, which directly burns to generate heat and supply steam, realizing the integration of energy supply equipment and the diversification of energy supply, ensuring the safe and stable operation of the energy supply system under extreme conditions, and significantly reducing the risk of production restriction.

[0014] (3) Based on the dual-mode intelligent control of electricity-driven heat and heat-driven electricity, the system can quickly respond to fluctuations in production demand. When the demand for electricity or steam changes, the system can achieve precise matching of steam production by starting the supplementary combustion component and the combustion-supporting component in stages.

[0015] (4) By integrating the design of the combustion supplement components, combustion aid components and flue, the volume and structural complexity of the power supply equipment are significantly reduced. Compared with the traditional solution that requires coordination of multiple subsystems, this system reduces construction and maintenance costs from the source.

[0016] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model;

[0018] Figure 2 This is a schematic diagram of the structure of the gas turbine, afterburner assembly, and combustion-supporting assembly according to an embodiment of the present invention;

[0019] Figure label:

[0020] 1. Gas turbine; 11. Main shaft; 12. Generator; 13. Compressor; 14. Turbine; 15. Combustion chamber; 2. Flue; 3. Waste heat boiler; 4. Afterburner assembly; 41. Afterburner burner; 42. Afterburner valve assembly; 43. Exhaust valve; 5. Recirculation pipeline; 6. Combustion support assembly; 61. Combustion support pipeline; 62. Combustion support fan; 63. Combustion support air valve; 64. Combustion support burner; 65. Combustion support valve assembly; 7. Power grid; 8. Fuel pipeline. Detailed Implementation

[0021] The technical solution of this utility model will be further described below with reference to the accompanying drawings and embodiments.

[0022] Unless otherwise defined, the technical or scientific terms used in this utility model shall have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar terms used in this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0023] Generally, to ensure that the steam-water system of an internally supplemented combustion waste heat boiler is the same as that of a non-supplemented combustion waste heat boiler, the temperature of the gas after supplemented combustion should not exceed 800℃~900℃; otherwise, a water-cooled tube wall-type heat radiant surface needs to be added. Practice shows that when the gas temperature after supplemented combustion is 750℃, the heat exchange of the economizer inside the waste heat boiler can be in optimal condition.

[0024] Example

[0025] like Figures 1-2 As shown, this utility model discloses a gas turbine exhaust gas afterburning and recirculation system, including a gas turbine 1 and a waste heat boiler 3 connected to the exhaust end of the gas turbine 1 via a flue 2. An afterburning component 4 is installed in the flue 2, which utilizes the residual oxygen in the exhaust gas of the gas turbine 1 for afterburning. The afterburning component 4 is connected to the fuel inlet of the gas turbine 1 via a recirculation pipe 5, and an auxiliary combustion component 6 is installed outside the flue 2 to ensure that the exhaust gas temperature entering the waste heat boiler 3 after afterburning and auxiliary combustion is less than 750°C. The waste heat boiler 3 utilizes the residual heat in the high-temperature exhaust gas to heat water and generate steam.

[0026] In this embodiment, the gas turbine 1 is a commercially available conventional product, including a main shaft 11 and a generator 12, a compressor 13 and a turbine 14 arranged sequentially on the main shaft 11. A combustion chamber 15 is provided between the compressor 13 and the turbine 14. The output end of the generator 12 is connected to the power grid 7 through a conventional line. The exhaust end of the turbine 14 is connected to one end of the flue 2.

[0027] The gas turbine 1 converts the chemical energy of fuel into mechanical energy. Specifically, the compressor 13 draws in and compresses air, increasing its pressure and temperature to prepare for combustion. The combustion chamber 15 mixes the compressed air with the fuel and burns it, generating high-temperature and high-pressure gas that drives the turbine 14 to rotate. The turbine 14 supplies energy to the compressor 13 and the generator 12 through the main shaft 11. Finally, the generator 12 converts the mechanical energy transmitted from the main shaft 11 into electrical energy, which is then input into the power grid 7.

[0028] The afterburning assembly 4 is used to add additional fuel combustion in the flue 2, significantly increasing the exhaust gas temperature and steam output. The afterburning assembly 4 includes an afterburner 41, an afterburner valve assembly 42, and an exhaust valve 43. The afterburner valve assembly 42 is connected to the fuel inlet of the afterburner 41 via a fuel pipe 8 and is used to control the fuel flow rate supplied to the afterburner 41. The exhaust valve 43 is installed on the flue 2 between the afterburner 41 and the turbine 14.

[0029] One end of the recirculation pipe 5 is connected to the exhaust port of the exhaust valve 43, and the other end is connected to the fuel inlet of the combustion chamber 15. Through exhaust gas re-combustion recirculation technology, the exhaust valve 43 and the recirculation pipe 5 reintroduce part of the high-temperature exhaust gas into the combustion chamber 15 and the re-combustion assembly 4 in the gas turbine 1, where it mixes with the newly added fuel for secondary combustion, thereby improving the heat grade of the flue gas, reducing exhaust heat loss, and increasing the steam output of the waste heat boiler 3 by 15%-30%.

[0030] Recirculated flue gas can also dilute the oxygen concentration in the combustion zone, suppress the generation of nitrogen oxides, and achieve ultra-low emissions and environmental protection in synergy; at the same time, it can regulate the combustion temperature, avoid combustion oscillation or flameout during fuel switching, support the mixed combustion of multiple fuels, and maintain combustion stability by increasing the proportion of recirculated flue gas under low load conditions, so that the gas turbine can still operate efficiently even when the minimum load drops to 20% of the rated load.

[0031] The combustion-supporting assembly 6 provides the necessary air for the afterburner 41 to ensure complete combustion of the fuel. The combustion-supporting assembly 6 includes a combustion-supporting pipe 61 and a combustion-supporting fan 62 (which provides pressurized air for combustion), a combustion-supporting air valve 63, and a combustion-supporting burner 64 (which helps to increase the exhaust temperature) installed sequentially in the combustion-supporting pipe 61. The end of the combustion-supporting pipe 61 is connected to the flue 2 between the exhaust valve 43 and the afterburner 41. The fuel inlet of the combustion-supporting burner 64 is connected to the combustion-supporting valve assembly 65 through the fuel pipe 8.

[0032] When gas turbine 1 is running, the steam fluctuations are regulated by the afterburner assembly 4 and the combustion aid assembly 6. The operating mode is as follows:

[0033] (1) Electricity-driven heating mode: When the power consumption is greater than the power generation of gas turbine 1, gas turbine 1 operates at full load, specifically in the following situations:

[0034] ① When the steam demand exceeds the steam production from the waste heat of the gas turbine 1's own flue gas: the auxiliary combustion component 4 starts, and the gas temperature entering the waste heat boiler 3 is less than 750℃. If the auxiliary combustion burner 41 can meet the steam demand in real time, the auxiliary combustion component 6 does not start; if the auxiliary combustion component 4 cannot meet the steam demand in real time, the auxiliary combustion component 6 starts and adjusts its opening according to the real-time steam demand.

[0035] ② When the amount of steam used is less than the amount of steam generated by the waste heat of the flue gas of the gas turbine 1: the auxiliary combustion component 4 and the combustion-supporting component 6 are not in operation, and the excess flue gas is introduced into the combustion chamber 15 through the exhaust valve 43 to meet the real-time steam demand on site.

[0036] (2) Heat-driven power generation mode: When the power consumption is less than the power generation of gas turbine 1, gas turbine 1 operates under partial load, specifically in the following situations:

[0037] ① When the steam demand exceeds the steam production from the waste heat of the gas turbine 1's own flue gas: the auxiliary combustion component 4 starts, and the gas temperature entering the waste heat boiler 3 is less than 750℃. If the auxiliary combustion burner 41 can meet the steam demand in real time, the auxiliary combustion component 6 does not start; if the auxiliary combustion component 4 cannot meet the steam demand in real time, the auxiliary combustion component 6 starts and adjusts its opening according to the real-time steam demand.

[0038] ② When the amount of steam used is less than the amount of steam generated by the waste heat of the flue gas of the gas turbine 1: the auxiliary combustion component 4 and the combustion-supporting component 6 are not in operation, and the excess flue gas is introduced into the combustion chamber 15 through the exhaust valve 43 to meet the real-time steam demand on site.

[0039] When gas turbine 1 is shut down for maintenance, the afterburner assembly 4, combustion aid assembly 6, and waste heat boiler 3 combine to form a conventional gas boiler, enabling independent steam supply. At this time, the afterburner assembly 4 acts as the main combustion component, directly feeding a large amount of fuel into the afterburner burner 41. With the air distribution of the combustion aid system, the fuel is directly combusted and heat generated in the flue 2, achieving a more flexible energy supply method and production guarantee. The operation mode is as follows:

[0040] ① When the fluctuation range of steam consumption is within the adjustment capacity range of the supplementary combustion component 4, the combustion-supporting burner 64 and combustion-supporting valve group 65 will not start, while the combustion-supporting fan 62 and combustion-supporting air valve 63 will start running, and the real-time steam demand will be met by the adjustment of the supplementary combustion component 4.

[0041] ② When the fluctuation range of steam consumption exceeds the adjustment capacity of the supplementary combustion component 4, the supplementary combustion burner 41 operates at full power, the auxiliary combustion burner 64 and the auxiliary combustion valve group 65 are started, and the real-time steam demand is met by the adjustment of the auxiliary combustion burner 64.

[0042] Therefore, this utility model discloses a gas turbine exhaust gas combustion recirculation system with the above-mentioned structure. Utilizing exhaust gas combustion recirculation technology, it enhances the calorific value of the flue gas through secondary combustion of high-temperature exhaust gas, significantly increasing steam production from the waste heat boiler while simultaneously reducing flue gas losses and suppressing nitrogen oxide generation. By dynamically adjusting the combustion temperature through recirculated flue gas, it supports multi-fuel mixed combustion and eliminates switching risks. Combining the gas turbine's operation and independent power supply modes during shutdown, it achieves uninterrupted steam supply by integrating the combustion recirculation components with the waste heat boiler. Based on an intelligent control mechanism that determines heat supply based on electricity and electricity supply based on heat, it stages the start-up and shutdown of the combustion recirculation and combustion-supporting components to precisely match steam demand. The integrated design significantly simplifies the equipment structure, requiring only conventional materials to improve power supply reliability and significantly reduce construction and maintenance costs, providing crucial technical support for the optimization and upgrading of exhaust gas combustion recirculation systems.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solution of this utility model, and these modifications or equivalent substitutions cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of this utility model.

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