Gasification system for flexible operation of coal-fired unit

Abstract

The utility model provides a gasification system for flexible operation of a coal-fired unit, and relates to the technical field of coal-fired power generation, the gasification system comprises a gasification furnace, a first steam pipeline, a second steam pipeline, a flue gas pipeline and an air pipeline, an outlet of the first steam pipeline is communicated to a steam inlet of the gasification furnace, an inlet of the second steam pipeline is communicated to the reheat steam pipeline, an outlet of the second steam pipeline is communicated to the first steam pipeline, at least one group of furnace wall inlets are formed in the furnace wall of the gasification furnace, and each group of furnace wall inlets comprises a smoke inlet and an air inlet. High-temperature flue gas is injected into the gasification furnace through the flue gas pipeline, and hot air is injected into the gasification furnace through the air pipeline. The flue gas inlet and the air inlet are formed in the furnace wall of the gasification furnace to inject high-temperature flue gas and hot air into the gasification furnace, so that gasification reaction conditions in the gasification furnace are optimized.

Description

Technical Field

[0001] This utility model relates to the technical field of coal-fired power generation, and in particular to a gasification system for flexible operation of coal-fired units. Background Technology

[0002] When coal-fired power units participate in grid peak shaving and need to rapidly reduce power supply load, the boiler steam heat load is difficult to respond synchronously due to system inertia, leading to a prominent supply-demand imbalance. To solve this problem, existing technologies propose using excess main steam as a gasifying agent for the gasification reaction of biomass, coal, and other raw materials. This allows for flexible adjustment of the unit's power supply load by maintaining stable boiler heat load. However, this process has significant technical bottlenecks: the main steam temperature is usually low, and the heat it carries is insufficient to support the high temperature required for the gasification reaction. Air needs to be introduced to promote the combustion and heat release of the gasification feedstock to maintain the continuous gasification reaction. Furthermore, the air is introduced into the gasifier through a single inlet, resulting in excessively high oxygen levels at the air inlet. The gasification feedstock is mainly consumed by combustion, and the heat generated by combustion is gradually consumed in the gasification reaction, causing the furnace temperature to gradually decrease. This results in insufficient temperature for the later stages of the reaction, inhibiting the depth of the gasification reaction. Utility Model Content

[0003] In view of this, this application provides a gasification system for flexible operation of coal-fired power units. By setting flue gas inlets and air inlets on the furnace wall of the gasifier, high-temperature flue gas and hot air are injected into the gasifier to increase the temperature of each area inside the furnace and provide oxygen, aiming to optimize the gasification reaction conditions inside the gasifier.

[0004] The gasification system provided in this application for flexible operation of a coal-fired power unit includes a gasifier, a first steam pipeline, a second steam pipeline, a flue gas pipeline, and an air pipeline. The inlet of the first steam pipeline is connected to the main steam pipeline of the coal-fired power unit, and the outlet of the first steam pipeline is connected to the steam inlet of the gasifier. The inlet of the second steam pipeline is connected to the reheat steam pipeline of the coal-fired power unit, and the outlet of the second steam pipeline is connected to the first steam pipeline. The gasifier has at least one set of furnace wall inlets, each set including a flue gas inlet and an air inlet. The flue gas inlet is connected to the flue gas pipeline to inject high-temperature flue gas into the gasifier, and the air inlet is connected to the air pipeline to inject hot air into the gasifier.

[0005] Preferably, the coal-fired unit includes: an air preheater, the outlet of the air pipeline being connected to the air inlet of the gasifier so as to inject hot air output from the air preheater into the gasifier through the air pipeline, and the inlet of the air pipeline being connected between the secondary air outlet of the air preheater and the secondary air box pipeline.

[0006] Preferably, the air preheater is located downstream of the SCR denitrification system of the coal-fired unit, and is used to obtain hot air by exchanging heat between the hot flue gas flowing out of the SCR denitrification system and the secondary air.

[0007] Preferably, the inlet of the flue gas pipeline is connected to the horizontal flue outlet of the boiler furnace, so as to inject the high-temperature flue gas in the horizontal flue outlet of the furnace furnace into the gasifier through the flue gas pipeline.

[0008] Preferably, the at least one set of furnace wall inlets includes multiple sets, which are evenly arranged on the furnace wall along the flow direction of the main steam, and / or, the multiple sets of furnace wall inlets are arranged circumferentially on the furnace wall. The flue gas pipeline includes a main flue gas pipeline and multiple branch flue gas pipelines, the number of which is the same as the number of which are the multiple flue gas inlets. The inlet of the main flue gas pipeline is connected to the horizontal flue at the furnace outlet, the outlet of the main flue gas pipeline is connected to the inlet of each branch flue gas pipeline, and the outlet of each branch flue gas pipeline is connected to the corresponding flue gas inlet. A valve for controlling the flow rate is installed on each branch flue gas pipeline. The air pipeline includes a main air pipeline and multiple branch air pipelines, the number of which is the same as the number of which are the multiple air inlets. The inlet of the main air pipeline is used to receive hot air, the outlet of the main air pipeline is connected to the inlets of all branch air pipelines, and the outlet of each branch air pipeline is connected to the corresponding air inlet. A valve for controlling the flow rate is installed on each branch air pipeline.

[0009] Preferably, the gasification system further includes: a high-temperature superheater, disposed in the horizontal flue at the furnace outlet of the boiler of the coal-fired unit, wherein the inlet of the main steam pipeline is connected to the outlet of the high-temperature superheater; and a high-temperature reheater, disposed in the horizontal flue at the furnace outlet of the boiler of the coal-fired unit, wherein the inlet of the reheat steam pipeline is connected to the outlet of the high-temperature reheater.

[0010] Preferably, the gasification system further includes: a first valve, disposed on the first steam pipeline, for controlling the main steam flow rate entering the gasifier; and a second valve, disposed on the second steam pipeline, for controlling the reheat steam flow rate entering the first steam pipeline.

[0011] Preferably, the gasification system further includes: a cyclone separator, the inlet of which is connected to the outlet of the gasifier; a tar cooling collector, the first inlet of which is connected to the first outlet of the cyclone separator, and the second inlet of which is used to receive secondary air; a scrubbing tower, the inlet of which is connected to the first outlet of the tar cooling collector; and a gas storage tank, the gas storage tank being connected to the outlet of the scrubbing tower.

[0012] Preferably, the gasification system further includes: a dryer, the inlet of which is used to receive the gasification feedstock so that the gasification feedstock enters the gasification furnace from the outlet of the dryer, the dryer including a hot air pipeline for drying the gasification feedstock, the inlet of the hot air pipeline being connected to the air pipeline outlet of the tar cooling collector, and the outlet of the hot air pipeline being connected to the secondary air inlet of the air preheater.

[0013] Preferably, the gasification system further includes: a secondary air duct, the inlet of which is connected to the atmosphere, and air is drawn in by a fan and enters the second inlet of the tar cooling collector; and a secondary air fan, which is located between the inlet of the secondary air duct and the second inlet of the tar cooling collector, for drawing secondary air from the secondary air box.

[0014] This application provides a gasification system for flexible operation of coal-fired power units, relating to the technical field of coal-fired power generation. The gasification system includes a gasifier, a first steam pipeline, a second steam pipeline, a flue gas pipeline, and an air pipeline. The inlet of the first steam pipeline is connected to the main steam pipeline, and the outlet of the first steam pipeline is connected to the steam inlet of the gasifier. The inlet of the second steam pipeline is connected to the reheat steam pipeline, and the outlet of the second steam pipeline is connected to the first steam pipeline. The gasifier has at least one set of furnace wall inlets, each set including a flue gas inlet and an air inlet. High-temperature flue gas is injected into the gasifier through the flue gas pipeline, and hot air is injected into the gasifier through the air pipeline. This application aims to optimize the gasification reaction conditions within the gasifier by providing flue gas inlets and air inlets on the gasifier wall to inject high-temperature flue gas and hot air.

[0015] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This illustration shows one of the structural schematic diagrams of a gasification system for flexible operation of a coal-fired power unit provided in an embodiment of this application;

[0018] Figure 2 This is a second schematic diagram of the gasification system for flexible operation of coal-fired power units provided in an embodiment of this application.

[0019] Reference numerals: 100-Boiler; 101-Main steam pipeline; 102-First steam pipeline; 103-Gasifier; 104-Reheat steam pipeline; 201-Flue gas pipeline; 202-Air pipeline; 203-Furnace wall inlet; 2031-Flue gas inlet; 2032-Air inlet; 204-Air preheater; 205-Reheater; 206-Second steam pipeline; 2071-First valve; 2072-Second valve; 208-Cyclone separator; 209-Tar cooling collector; 210-Scrubber; 211-Air storage tank; 212-Dryer; 213-Secondary air fan; 214-Secondary air pipeline. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] In the description of the embodiments of this application, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. They are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the utility model. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0022] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0023] In the description of the embodiments of this application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0024] When coal-fired power units need to rapidly reduce power supply load to participate in grid peak shaving, the boiler steam heat load is difficult to adjust synchronously due to problems such as large system thermal inertia and slow response, resulting in limited peak shaving capacity of the units. To address this contradiction, existing technologies propose using excess main steam as a gasifying agent, coupled with biomass or coal as raw materials for gasification reactions, to achieve flexible adjustment of power supply load by maintaining stable boiler heat load. However, this technology has the following significant drawbacks in practical applications: the main steam temperature is generally below 630℃, and its enthalpy value cannot meet the high-temperature conditions required for gasification reactions. To maintain the reaction temperature, excess air needs to be introduced to promote the combustion and heat release of the gasification feedstock. Some processes even use the secondary combustion of gasification by-product coke as a supplementary heat source. In this mode, some gasification feedstock is directly consumed by combustion instead of being converted into high-value products, resulting in a significant reduction in gasification efficiency and additional CO2 emissions, which contradicts the low-carbon goal. In addition, existing gasification systems use a single air inlet design, and the concentrated injection of oxygen leads to excessively high oxygen concentration in the inlet area, forming a reaction zone dominated by combustion. Although the heat released by combustion can briefly raise the furnace temperature, as the gasification feedstock flows toward the outlet, the oxygen is gradually depleted, and the heat is rapidly consumed by the gasification endothermic reaction, causing the reaction temperature in the later stage to drop sharply to below 600°C. This temperature gradient, which is high at the beginning and low at the end, severely inhibits the depth of the gasification reaction.

[0025] like Figure 1 As shown in the figure, this application provides one of the gasification systems for flexible operation of coal-fired power units, including: a first steam pipeline 102, a second steam pipeline 206, a flue gas pipeline 201 and an air pipeline 202.

[0026] The inlet of the first steam pipe 102 is connected to the main steam pipe 101 of the boiler of the coal-fired unit, and the outlet of the first steam pipe 102 is connected to the steam inlet of the boiler. The inlet of the second steam pipe 206 is connected to the reheat steam pipe 104, and the outlet of the second steam pipe 206 is connected in parallel to the first steam pipe 102. Multiple sets of furnace wall inlets 203 are formed on the furnace wall of the gasifier 103. Each set of furnace wall inlets 203 includes a flue gas inlet 2031 and an air inlet 2032. The flue gas inlet 2031 is used to transport high-temperature flue gas into the gasifier 103 through the flue gas pipe 201, and the air inlet 2032 is used to transport hot air into the gasifier 103 through the air pipe 202. The multiple sets of furnace wall inlets are evenly arranged on the furnace wall along the flow direction of the main steam, or they can be arranged along the flow direction of the main steam, and / or the multiple sets of furnace wall inlets are arranged on the furnace wall circumferentially.

[0027] Here, the number of furnace wall inlets 203 can be 3-7 groups. The interval between the flue gas inlet 2031 and the air inlet 2032 in each group of furnace wall inlets 203 can be set to 1 meter-3 meters. Each flue gas inlet 2031 and each air inlet 2032 is provided with a nozzle. On the one hand, the high-temperature flue gas supplements a large amount of heat to provide the required heat for the gasification reaction. On the other hand, the high-temperature flue gas dilutes the oxygen content of the hot air, further preventing the combustion of the gasification raw materials from participating in the gasification reaction. Compared with the traditional gasification process, the gasifier 103 in this application is no longer divided into a combustion zone and a gasification reaction zone. Instead, multiple high-temperature, extremely low-oxygen gasification reaction zones are formed in the gasifier 103, which greatly improves the conversion rate of gasification raw materials to gasification products.

[0028] In addition, this application can also adjust the high-temperature flue gas and hot air for the real-time feedback parameters of the gasification reaction in each area of ​​the gasifier 103, thereby adjusting the reaction temperature and oxygen concentration in real time, realizing fine control of the gasification reaction, and further ensuring the efficient gasification reaction. This application is also compatible with traditional gasification processes, and on this basis, it can improve the gasification quality by adjusting the gasification parameters in the furnace through the injection of high-temperature flue gas and hot air.

[0029] In a preferred embodiment of this application, the inlet of the flue gas pipeline 201 is connected to the inlet of the horizontal flue outlet of the boiler of the coal-fired unit, so as to transport the high-temperature flue gas in the horizontal flue outlet of the boiler to the gasifier 103 through the flue gas pipeline 201.

[0030] The flue gas pipeline 201 includes a main flue gas pipeline and multiple branch flue gas pipelines. The number of branch flue gas pipelines is the same as the number of flue gas inlets 2031. The inlet of the main flue gas pipeline is connected to the inlet of the horizontal flue gas duct at the furnace outlet of the boiler. The outlet of the main flue gas pipeline is connected to the inlet of all the branch flue gas pipelines. The outlet of each branch flue gas pipeline is connected to the corresponding flue gas inlet 2031. Each branch flue gas pipeline is equipped with a valve to control the flow rate of high-temperature flue gas in that branch flue gas pipeline.

[0031] Air duct 202 includes a main air duct and multiple branch air ducts. The number of branch air ducts is the same as the number of air inlets 2032. The outlet of the main air duct is connected to the inlet of all branch air ducts. The outlet of each branch air duct is connected to the corresponding air inlet 2032. Each branch air duct is equipped with a valve to control the flow rate of hot air in that branch air duct.

[0032] Among them, multiple sets of furnace wall inlets 203 are evenly arranged on the furnace wall along the flow direction of the main steam.

[0033] The gasification system layout described in this application improves the peak-shaving flexibility and gasification reaction efficiency of coal-fired power units through multi-level media coordinated supply and spatial distribution optimization.

[0034] like Figure 2 As shown in the embodiment of this application, a second gasification system for flexible operation of a coal-fired unit is also provided, including: an air preheater 204, a reheater 205, a first valve 2071, a second valve 2072, a cyclone separator 208, a tar cooling collector 209, a scrubbing tower 210, a gas storage tank 211, a dryer 212, a secondary air duct 214, and a secondary air fan 213.

[0035] The secondary air outlet of the air preheater 204 is connected to the inlet of the air duct 202 to deliver hot air into the gasifier 103 through the air duct 202. At the same time, the air preheater 204 can also receive heat from the primary air and flue gas for heat exchange. The inlet of the air duct 202 is connected between the secondary air outlet of the air preheater 204 and the secondary air box duct.

[0036] As an example, the air preheater 204 is located downstream of the SCR denitrification system of the coal-fired unit, and is used to exchange heat with the secondary air by recovering the heat of the hot flue gas flowing through the SCR denitrification system to obtain hot air.

[0037] The reheater 205 is installed in the horizontal flue at the furnace outlet of the boiler of the coal-fired unit. The reheat steam pipeline 104 is connected to the reheater 205, specifically at the boiler furnace outlet (at the horizontal flue after the flame deflector).

[0038] The first valve 2071 is installed on the first steam pipeline 102 to control the main steam flow rate entering the gasifier 103, and the second valve 2072 is installed on the second steam pipeline 206 to control the reheat steam flow rate entering the first steam pipeline 102.

[0039] As an example, the high-temperature superheater is installed in the horizontal flue at the furnace outlet, and the inlet of the main steam pipeline is connected to the outlet of the high-temperature superheater.

[0040] The high-temperature reheater is located in the horizontal flue at the furnace outlet, and the inlet of the reheat steam pipeline is connected to the outlet of the high-temperature reheater.

[0041] The inlet of the cyclone separator 208 is connected to the outlet of the gasifier 103, the first inlet of the tar cooling collector 209 is connected to the first outlet of the cyclone separator 208, the second inlet of the tar cooling collector 209 is used to receive secondary air, the inlet of the scrubbing tower 210 is connected to the first outlet of the tar cooling collector 209, and the gas storage tank 211 is connected to the outlet of the scrubbing tower 210.

[0042] The first inlet of the dryer 212 is connected to the second outlet of the cyclone separator 208, the first outlet of the dryer 212 is connected to the raw material inlet of the gasifier 103, the second inlet of the dryer 212 is connected to the second outlet of the tar cooling collector 209, and the second outlet of the dryer 212 is connected to the secondary air inlet of the air preheater 204.

[0043] The inlet of the secondary air duct 214 is connected to the secondary air box of the coal-fired unit. The secondary air duct 214 is connected in sequence to the second inlet of the tar cooling collector 209. The secondary air fan 213 is installed on the secondary air duct 214 to draw secondary air from the secondary air box.

[0044] As an example, the first outlet of the cyclone separator 208 is located at the bottom, and the solid product at the first outlet is gasified carbon. The second outlet of the cyclone separator 208 is connected to the shell side of the tar cooling and collection device. The pipe side of the tar cooling device is cold secondary air. The cold secondary air absorbs heat from the gasification products on the shell side and is heated, while simultaneously cooling and collecting the tar, which is discharged from the bottom of the cooling device. The secondary air heated by the tar cooling device passes through the dryer 212 to heat and dry the gasification feedstock. The gasification feedstock includes, but is not limited to, coal, biomass, sludge, and other organic solid waste.

[0045] Here, the gasification feedstock is connected to the feedstock inlet of gasifier 103 via dryer 212. The outlet of gasifier 103 is connected to the inlet of cyclone separator 208. The upper gas outlet of cyclone separator 208 is connected to the inlet of tar cooling and collection device. The outlet of tar cooling and collection device is connected to the inlet of scrubbing tower 210. The outlet of scrubbing tower 210 is connected to gas storage tank 211. The particulate matter separated from the lower part of cyclone separator 208 is solid carbon produced by gasification, which can be further processed to prepare activated carbon and other products. The liquid product collected at the bottom of the capture device is gasified tar, which can be further processed into chemical products such as aviation fuel; the gas collected in the gas storage tank 211 is gasified gas, which can be used for low-load auxiliary stable combustion of boiler 100, or to replace coal during normal operation; in the tar cooling device, cold secondary air is used to cool and collect the tar. After being heated, the cold secondary air enters the dryer 212 to dry and preheat the gasification raw material, and then enters the air preheater 204 for heating. One path enters the furnace, and the other path enters the gasifier 103 as combustion air.

[0046] Compared with the prior art, this application has the following advantages:

[0047] This application significantly improves the flexibility and gasification efficiency of coal-fired power units through multi-level coordinated control. When the unit needs to rapidly reduce load, the amount of main steam and reheat steam entering the turbine is reduced first, and the excess steam is introduced into the gasifier for biomass, coal, or solid waste gasification to maintain stable boiler heat load. After the power supply load is adjusted, the amount of coal is gradually reduced to avoid safety risks caused by sudden changes in boiler heat load. Conversely, when the load needs to be rapidly increased, the steam supply to the gasifier is reduced, and more steam is directed to the turbine to achieve agile response to power generation load. This dynamic steam redistribution effectively solves the timing contradiction between the coordinated regulation of power supply load and boiler heat load, improving the unit's peak-shaving response speed. At the same time, the gasification system adopts high-temperature flue gas and hot air multi-point coordinated injection technology: 3-7 sets of nozzles are arranged along the flow direction of gasification feedstock, each set including one hot air nozzle and one high-temperature flue gas nozzle. High-temperature flue gas not only provides heat for the gasification reaction, but also reduces the oxygen concentration and inhibits the combustion loss of raw materials, creating a homogeneous reaction environment with high temperature and low oxygen throughout the gasifier. The flow rate of the medium at each nozzle can be dynamically adjusted to achieve millimeter-level precision control of temperature gradient and oxygen concentration. While realizing the resource utilization of solid waste, it also has the advantages of frequency regulation performance improvement and circular economy value.

[0048] Based on this application, the final products can be gasified carbon, gasified oil, and gasified gas. Gasified carbon can be used to produce activated carbon and other products, gasified oil can be used to produce asphalt, aviation fuel, and other products, and gasified gas can directly assist in deep peak shaving of boilers, maintaining stable combustion and replacing coal. Simultaneously, the main steam, high-temperature flue gas from the boiler, and hot air used in the gasification reaction can also serve as a buffer for boiler heat load adjustment after the unit's power supply load is adjusted, promoting a rapid and stable reduction or increase in boiler heat load, which is beneficial for coal saving, carbon reduction, and improving the operational flexibility of coal-fired units. Furthermore, the gasification feedstock can be biomass, coal, sludge, and other solid waste, enabling the efficient and clean utilization of coal, renewable zero-carbon fuels, and solid waste.

[0049] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the claims.

Claims

1. A gasification system for flexible operation of a coal-fired unit, characterized in that, The gasification system comprises a gasification furnace, a first steam pipeline, a second steam pipeline, a flue gas pipeline and an air pipeline, wherein the inlet of the first steam pipeline is connected to the main steam pipeline of the coal-fired unit, the outlet of the first steam pipeline is connected to the steam inlet of the gasification furnace, the inlet of the second steam pipeline is connected to the reheat steam pipeline of the coal-fired unit, the outlet of the second steam pipeline is connected to the first steam pipeline, The furnace wall of the gasification furnace has at least one group of furnace wall inlets, each group of furnace wall inlets comprises a flue gas inlet and an air inlet, the flue gas inlet is connected to the flue gas pipeline to inject high-temperature flue gas into the gasification furnace through the flue gas pipeline, and the air inlet is connected to the air pipeline to inject hot air into the gasification furnace through the air pipeline.

2. The gasification system of claim 1, wherein, The coal-fired unit comprises: An air preheater, the outlet of the air pipeline is connected to the air inlet of the gasification furnace to inject the hot air output by the air preheater into the gasification furnace through the air pipeline, and the inlet of the air pipeline is connected between the secondary air outlet of the air preheater and the secondary air plenum pipeline.

3. The gasification system of claim 2, wherein, The air preheater is arranged on the downstream side of the SCR denitration system of the coal-fired unit, and is used for exchanging heat between the heat of the flue gas flowing out of the SCR denitration system and the secondary air to obtain the hot air.

4. The gasification system of claim 1, wherein, The inlet of the flue gas pipeline is connected to the furnace outlet horizontal flue of the boiler to inject the high-temperature flue gas in the furnace outlet horizontal flue into the gasification furnace through the flue gas pipeline.

5. The gasification system of claim 4, wherein, The at least one group of furnace wall inlets comprises a plurality of groups, and the plurality of groups of furnace wall inlets are uniformly arranged on the furnace wall along the flow direction of the main steam, and / or, the plurality of groups of furnace wall inlets are arranged on the furnace wall along the circumference of the furnace wall, The flue gas pipeline comprises a flue gas main pipeline and a plurality of flue gas branch pipelines, the number of the plurality of flue gas branch pipelines is the same as the number of the plurality of flue gas inlets, the inlet of the flue gas main pipeline is connected to the furnace outlet horizontal flue, the outlet of the flue gas main pipeline is connected to the inlet of each flue gas branch pipeline, the outlet of each flue gas branch pipeline is connected to the corresponding flue gas inlet, and a valve for controlling the flow is arranged on each flue gas branch pipeline, The air pipeline comprises an air main pipeline and a plurality of air branch pipelines, the number of the plurality of air branch pipelines is the same as the number of the plurality of air inlets, the inlet of the air main pipeline is used for receiving the hot air, the outlet of the air main pipeline is connected to the inlet of all the air branch pipelines, the outlet of each air branch pipeline is connected to the corresponding air inlet, and a valve for controlling the flow is arranged on each air branch pipeline.

6. The gasification system of claim 1, wherein, The gasification system further comprises: A high-temperature superheater arranged in the furnace outlet horizontal flue of the boiler of the coal-fired unit, and the inlet of the main steam pipeline is connected to the outlet of the high-temperature superheater; A high-temperature reheater arranged in the furnace outlet horizontal flue of the boiler of the coal-fired unit, and the inlet of the reheat steam pipeline is connected to the outlet of the high-temperature reheater.

7. The gasification system of claim 6, wherein, The gasification system further comprises: a first valve disposed on the first steam line for controlling the flow of main steam into the gasifier; a second valve disposed on the second steam line for controlling the flow of reheat steam into the first steam line.

8. The gasification system of claim 1, wherein, The gasification system further comprises: a cyclone separator having an inlet in communication with an outlet of the gasifier; a tar cooling trap having a first inlet in communication with a first outlet of the cyclone separator and a second inlet for receiving secondary air; a scrubber tower having an inlet in communication with a first outlet of the tar cooling trap; a gas holder in communication with an outlet of the scrubber tower.

9. The gasification system of claim 8, wherein, The gasification system further comprises: a dryer having an inlet for receiving gasification feedstock for entry from an outlet of the dryer into the gasifier, the dryer comprising a hot air line for drying the gasification feedstock, the hot air line having an inlet connected to an air line outlet of the tar cooling trap and an outlet in communication with a secondary air inlet of an air preheater.

10. The gasification system of claim 8, wherein, The gasification system further comprises: a secondary air line having an inlet in communication with the atmosphere for drawing air through a fan into the second inlet of the tar cooling trap; a secondary air fan disposed between the inlet of the secondary air line and the second inlet of the tar cooling trap for drawing secondary air in the secondary air plenum.

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