A pyrolysis gas cooling system and method for a pyrolysis furnace in a thermal power plant

Abstract

The present invention discloses a pyrolysis gas cooling system and method for a thermal power plant pyrolysis furnace, comprising a power plant boiler and its air supply system, a steam turbine and its steam-water system, and a pyrolysis furnace and its pyrolysis gas cooling, purification and separation device, wherein a heat exchange device is provided in the pyrolysis gas cooling, purification and separation device, wherein the heat exchange device is an air-cooled heat exchanger and / or a water-cooled heat exchanger, wherein the cooling medium in the air-cooled heat exchanger and / or the water-cooled heat exchanger cools the pyrolysis gas in the pyrolysis gas cooling, purification and separation device, wherein the cooling medium heated at the outlet of the air-cooled heat exchanger can be transported into a power plant boiler or a powder making system, and wherein the cooling medium heated at the outlet of the water-cooled heat exchanger can be transported into a boiler water supply pipeline or a deaerator water supply pipeline or a heat network circulating water supply pipeline. The present invention has a simple structure, can fully utilize the heat released during the cooling of the pyrolysis gas to heat the wind and / or water required to be heated in the thermal power plant system, reduce its energy consumption, and significantly improve energy utilization.

Description

Technical Field

[0001] The invention relates to the technical field of pyrolysis, and in particular to a pyrolysis gas cooling system and method for a pyrolysis furnace in a thermal power plant. Background Art

[0002] Research has found that coal contains high levels of oil and gas resources. Therefore, coal pyrolysis technology can improve the utilization efficiency of coal, and the pyrolysis products, coal tar and pyrolysis gas, can serve as a supplement to oil and natural gas. In addition, the steel industry consumes a large amount of coke every year, and high-quality coke is produced through coal coking furnaces. In recent years, my country's coke production has accounted for more than half of the world's total production, and it has become the world's largest coke producer and exporter. This has stimulated the rapid development of coking technology, the number of new and renovated coke ovens has risen sharply, and the proportion of large-scale coke ovens has increased significantly; a number of new technologies such as waste heat utilization of waste gas, dry heat degassing cooling, ramming coking, and coking production automation have been promoted and applied.

[0003] Biomass is a clean renewable energy source. Biomass rapid pyrolysis technology is an important way to utilize biomass. The so-called pyrolysis is the process of using heat energy to break the molecular bonds of large molecular weight organic matter and hydrocarbons, and transform them into low molecular weight substances with a small number of carbon atoms. Biomass pyrolysis is a biomass thermal degradation process in which biomass produces three products: liquid (bio-oil), gas (combustible gas), and solid (coke) under completely anaerobic conditions.

[0004] In addition, with the development of industry and cities, the amount of urban garbage and sludge, as well as industrial oil sludge, is increasing, and urban environmental protection has put forward higher requirements for the treatment of garbage and sludge. As garbage and sludge landfills occupy and pollute a large amount of land, the use of pyrolysis technology for harmless treatment of garbage or sludge will become the only option in the future.

[0005] In the above-mentioned pyrolysis process of coal, biomass, garbage or sludge, the heat carried by the pyrolysis gas accounts for more than 30%. How to cool the pyrolysis gas and utilize the heat therein, and then extract tar, coal gas, biomass gas, oil gas and other combustible gases from the pyrolysis gas, has become the key to improving the economy and energy efficiency of the pyrolysis project. The conventional cooling method currently used is water cooling or air cooling, but generally after the cooling water or cooling air exchanges heat with the pyrolysis gas, the heat is dissipated into the atmosphere through a cooling tower or an air-cooled radiator, and the heat is completely wasted, making the overall energy efficiency of the pyrolysis furnace low. Summary of the invention

[0006] The problem solved by the present invention is that the heat released by cooling pyrolysis gas in a pyrolysis gas cooling purification and separation device is not fully utilized.

[0007] To solve the above problems, the present invention provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant, comprising a power plant boiler and its air supply system, a steam turbine and its steam-water system, and a pyrolysis furnace and its pyrolysis gas cooling, purification and separation device. The pyrolysis gas cooling, purification and separation device is provided with a heat exchange device, and the heat exchange device is an air-cooled heat exchanger and / or a water-cooled heat exchanger. The cooling medium in the air-cooled heat exchanger and / or the water-cooled heat exchanger cools the pyrolysis gas in the pyrolysis gas cooling, purification and separation device. The cooling medium heated at the outlet of the air-cooled heat exchanger can be transported into a power plant boiler or a pulverizing system, and the cooling medium heated at the outlet of the water-cooled heat exchanger can be transported into a boiler water supply pipeline or a deaerator water supply pipeline or a heat network circulating water supply pipeline.

[0008] The raw material decomposed by the pyrolysis furnace can be any one or more of raw coal, biomass, garbage, and sludge. The pyrolysis gas cooling system of the pyrolysis furnace in the thermal power plant utilizes the heat released by the cooling of the pyrolysis gas to heat the cooling medium in the heat exchange device. The cooling medium heated by the pyrolysis gas can be wind and / or water. The hot air can be sent to the power station boiler to assist the combustion of coal in the furnace, saving its own energy consumption. The hot water can be sent to the boiler water supply pipeline or the deaerator water supply pipeline or the heat network circulating water supply pipeline, reducing the energy consumption of heating cold water in the water supply system or the condensate water system or the heat network circulating water system, and making full use of the heat released by the cooling of the pyrolysis gas.

[0009] Furthermore, the heat exchange device is an air-cooled heat exchanger, and the cooling medium flowing inside the air-cooled heat exchanger is cold primary air or secondary air of a power station boiler.

[0010] The pyrolysis gas cooling, purification and separation device is used to heat part of the primary air or secondary air, thereby reducing the heat consumption of the air preheater in the power station boiler for preheating the primary air or secondary air.

[0011] Furthermore, the air supply system is connected to the air preheater and the air-cooled heat exchanger, and is provided with at least one flow splitter and at least one flow merging device, and the flow splitter and flow merging device can control the flow in each air duct.

[0012] Part of the air delivered by the air supply system enters the air preheater inside the power station boiler for preheating, and part enters the pyrolysis gas cooling, purification and separation device for heat exchange. The pyrolysis air is combined and then enters the power station boiler or the powder making system. At the same time, the setting of the adjustable diversion device and the converging device can control the air volume entering the air preheater and the pyrolysis gas cooling system, so that the pyrolysis gas cooling system is in a heat exchange equilibrium state.

[0013] Furthermore, the inlet of the diversion device is connected to cold primary air, and the outlet thereof is connected to the cold air duct of the air preheater and the air-cooled heat exchanger. The inlet of the combining device is connected to the hot air duct of the air preheater and the air-cooled heat exchanger, and the outlet thereof is connected to the powder making system, and the outlet of the powder making system is connected to the power station boiler burner.

[0014] After the primary air enters the diversion device, it enters the air preheater and the air-cooled heat exchanger from its outlet for heating. The heated primary air is merged by the combining device and enters the pulverizing system, carrying the pulverized coal in the pulverizing system into the burner of the power station boiler. The hot primary air can ensure that the pulverized coal has a certain temperature when entering the power station boiler, which is convenient for its full combustion and improves energy utilization.

[0015] Furthermore, the inlet of the diversion device is connected to the cold air duct of the air preheater and the air-cooled heat exchanger, and the inlet of the merging device is connected to the hot air duct of the air preheater and the air-cooled heat exchanger, and the outlet is connected to the power station boiler burner.

[0016] After the secondary air enters the diversion device, it enters the air preheater and the air-cooled heat exchanger from its outlet for heating. The heated secondary air is combined by the merging device and then enters the power station boiler. The secondary air used by the power station boiler is usually high-temperature air, and its usage is the largest. Heating it only by the air preheater will consume a lot of heat in the power station boiler, affecting the energy utilization rate. Heating part of the secondary air by the pyrolysis gas cooling purification and separation device can significantly improve the energy utilization rate in the power station boiler. In addition, when the power station boiler of the thermal power plant is running at low load, the air inlet of the air preheater can be closed, and the pyrolysis gas cooling heat can be fully utilized to replace the heat absorbed by the air preheater, so as to maintain the SCR inlet flue gas temperature above 310 degrees under the low load of the boiler, and ensure the normal operation of the SCR system under low load.

[0017] Furthermore, a water-cooled heat exchanger is provided in the heat exchange device, and the cooling medium flowing inside the water-cooled heat exchanger is any one of boiler feed water, condensed water or heat network circulating return water.

[0018] The pyrolysis gas cooling, purification and separation device is used to heat part of the boiler feed water or condensate or heat network circulating return water, thereby reducing the coal consumption of the power station boiler and improving the circulation efficiency of the steam-water system of the thermal power unit.

[0019] Furthermore, the cold water pipeline of the water-cooled heat exchanger is connected to any one of the water supply pipelines of the power station boiler of the thermal power plant or the condensate water supply pipeline or the circulating water return pipeline of the heating network, and the hot water pipeline of the water-cooled heat exchanger is connected to any one of the water supply pipelines of the power station boiler or the deaerator of the thermal power plant or the circulating water return pipeline of the heating network. A control valve is provided in the steam-water system to control the inlet and outlet and flow rate of the cooling medium.

[0020] A portion of boiler feed water or condensate or heat network circulating water return water in the steam-water system enters the pyrolysis gas cooling purification separation device for heat exchange, and the depyrogenic water enters the power station boiler or deaerator water supply pipeline or the heat network circulating water supply pipeline, thereby reducing the energy consumption for heating it. At the same time, the setting of the adjustable control valve can control the amount of water entering the pyrolysis gas cooling system, so that the pyrolysis gas cooling system is in a heat exchange equilibrium state.

[0021] Furthermore, the air-cooled heat exchanger or water-cooled heat exchanger is a surface-type spaced heat exchange coil, and the coil is any one of a plain tube, an inner finned tube, an outer finned tube, or a heat exchange tube with fins inside and outside.

[0022] Furthermore, an airflow control valve is provided on the pyrolysis gas pipeline at the outlet of the pyrolysis furnace, and the airflow control valve can control a part of the pyrolysis gas to be sent to the pyrolysis gas cooling, purification and separation device, and at the same time, another part of the pyrolysis gas can be directly sent to the power station boiler.

[0023] A portion of the pyrolysis gas is directly sent to the power plant boiler to become the direct energy source of the power plant boiler, reducing the consumption of other fuels. At the same time, the hot pyrolysis gas does not need to be preheated, which can save a lot of energy. The flue gas can be harmlessly treated by the flue gas treatment device of the power plant boiler, saving some equipment investment.

[0024] Furthermore, the combustible gas purified and separated by the pyrolysis gas cooling purification and separation device is subsequently treated or introduced into a power station boiler, the waste gas generated by the pyrolysis furnace or the pyrolysis gas cooling purification and separation device is sent to the power station boiler, and the waste slag and waste liquid generated by the pyrolysis furnace or the pyrolysis gas cooling purification and separation device are sent to the thermal power plant treatment facilities.

[0025] The combustible gas purified and separated by the pyrolysis gas cooling purification and separation device is introduced into the power station boiler burner for combustion support, thereby saving hot air usage and reducing energy consumption. The waste gas generated by the pyrolysis furnace or the pyrolysis gas cooling purification and separation device is sent to the power station boiler and can be harmlessly treated by its flue gas treatment device. The waste slag and waste liquid generated by the pyrolysis furnace or the pyrolysis gas cooling purification and separation device can be sent to the thermal power plant treatment facilities for harmless treatment.

[0026] The present invention also provides a method for cooling a pyrolysis gas cooling system of a pyrolysis furnace in a thermal power plant according to any one of the above methods. The pyrolysis gas cooling system of the pyrolysis furnace is designed according to the following method:

[0027] S1. According to the type and scale of the pyrolysis furnace, calculate the total amount of heat that needs to be removed by cooling the hot pyrolysis gas. The calculation formula is:

[0028] Q 总 =M 热解气 *Cp 热解气 *(T 热气 -T 冷气);

[0029] Q 总 is the total heat dissipation of hot pyrolysis gas in the pyrolysis gas cooling, purification and separation device, kJ / h; M 热解气 is the mass of pyrolysis gas involved in heat exchange, kg / h; Cp 热解气 is the specific heat capacity of pyrolysis gas, kJ / kg℃; T 热气 T is the temperature of hot pyrolysis gas entering the pyrolysis gas cooling, purification and separation device, ℃; 冷气 is the temperature of the cold pyrolysis gas discharged from the pyrolysis gas cooling, purification and separation device, °C;

[0030] S2. Designing the heat exchange surface area of ​​the heat exchange device arranged in the pyrolysis gas cooling, purification and separation device and the required cooling air and / or water volume, flow rate, inlet temperature and outlet temperature according to the total heat dissipation of the hot pyrolysis gas in the pyrolysis gas cooling, purification and separation device;

[0031] S3. Design the amount and temperature of air and / or water delivered to the pyrolysis gas cooling, purification and separation device according to the conditions of the air supply system and steam-water system of the thermal power plant and the ambient temperature;

[0032] The heat balance equation for heat exchange between pyrolysis gas and cooling air and / or water is:

[0033] Q 总 =M 风 *Cp 风 *(T 热风 -T 冷风 )+M 水 *Cp 水 *(T 热水 -T 冷水 )+Q 损失 ;

[0034] Q 总 is the total heat dissipation of hot pyrolysis gas from the pyrolysis gas cooling, purification and separation device, kJ / h; Q 损失 Heat loss from heat exchange and heat dissipation of pyrolysis gas cooling, purification and separation device, kJ / h; M 风 is the cooling air volume involved in cooling, kg / h; Cp 风 is the specific heat capacity of primary air or secondary air, kJ / kg℃; M 水 is the amount of cooling water involved in cooling, kg / h; Cp 水 is the specific heat capacity of water, kJ / kg℃; T 热风 T is the temperature of the hot air after heating in the pyrolysis gas cooling, purification and separation device, ℃; 冷风 T is the cold air temperature entering the pyrolysis gas cooling, purification and separation device, ℃; 热水 is the temperature of hot water after heating in the pyrolysis gas cooling, purification and separation device, ℃; T 冷水is the temperature of cold water entering the pyrolysis gas cooling, purification and separation device, °C;

[0035] S4. Complete the installation and connection of the pyrolysis gas cooling system of the thermal power plant pyrolysis furnace according to the design results of S2 and S3;

[0036] S5. Utilize the flow dividing device, the flow combining device and / or the control valve on the steam-water system on the air supply system to control the amount of air and / or water sent to the pyrolysis gas cooling purification separation device for absorbing heat, and then control the outlet temperature of the hot air and / or hot water pipeline of the pyrolysis gas cooling purification separation device, so that the system reaches the heat balance described in S3.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] 1. Using cold air and / or water in the production system of a thermal power plant to cool the hot pyrolysis gas, thereby realizing a pyrolysis gas cooling process with intermittent heat exchange, wherein the cold air is primary air or secondary air;

[0039] 2. Use the heat recovered from pyrolysis gas cooling to heat the cold air and / or water in the production system, reduce the energy consumption of preheating the air and / or water in the original system, and improve production efficiency;

[0040] 3. When the boiler of a thermal power plant is running at low load, the heat from the pyrolysis gas cooling can be used to replace the heat absorbed by the air preheater, maintaining the SCR inlet flue gas temperature above 310 degrees under low boiler load, thus ensuring the normal operation of the SCR system under low load. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of a pyrolysis gas cooling system of a pyrolysis furnace in a thermal power plant according to Example 1 of the present application;

[0042] Figure 2 is a schematic diagram of an air-cooled pyrolysis gas cooling heat exchange system according to Example 2 of the present application;

[0043] Figure 3 It is a schematic diagram of heating the primary air separately in Example 3 of the present application;

[0044] Figure 4 is a schematic diagram of heating the secondary air separately in Example 4 of the present application;

[0045] Figure 5 It is a schematic diagram of the water-cooled pyrolysis gas cooling heat exchange in Example 5 of the present application.

[0046] Description of reference numerals:

[0047] 1. Power station boiler; 2. Air supply system; 201. Diverter; 202. Combiner; 3. Steam turbine; 4. Steam-water system; 401. Control valve; 5. Pyrolysis furnace; 501. Air flow control valve; 6. Pyrolysis gas cooling, purification and separation device; 7. Heat exchange device; 701. Air-cooled heat exchanger; 702. Water-cooled heat exchanger; 8. Air preheater; 9. Pulverizing system; 10. Power station boiler burner. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same reference numerals are marked on the components with the same structure or function, and their repeated description is omitted. The described embodiments are only illustrative of the concept of the present invention and do not limit the scope of the present invention. The implementation methods of this application are described in detail below in conjunction with the drawings.

[0049] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present application.

[0050] A pyrolysis gas cooling system and method for a pyrolysis furnace in a thermal power plant according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0051] Example 1

[0052] This embodiment provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant, such as Figure 1 As shown, the pyrolysis gas cooling system of the pyrolysis furnace of the thermal power plant includes a power station boiler 1 and its air supply system 2, a steam turbine 3 and its steam-water system 4, and also includes a pyrolysis furnace 5 and its pyrolysis gas cooling, purification and separation device 6. The pyrolysis gas cooling, purification and separation device 6 is provided with a heat exchange device 7, and the heat exchange device 7 includes an air-cooled heat exchanger 701 and a water-cooled heat exchanger 702.

[0053] The air supply system 2 includes a cold air duct and a hot air duct, wherein the cold air duct is connected to the cold air ducts of the air preheater 8 and the air-cooled heat exchanger 701 respectively, and a diverter 201 is provided at the connection, and the diverter 201 can adjust the flow in each cold air duct, and the hot air duct of the air supply system 2 is connected to the hot air duct of the air preheater 8 and the air-cooled heat exchanger 701, and a confluence device 202 is provided at the connection, and the confluence device 202 can adjust the flow in each hot air duct. The air supply system 2 can deliver cold primary air or secondary air of the power station boiler 1.

[0054] The cold water pipeline of the water-cooled heat exchanger 702 is connected to any one of the water supply pipelines of the thermal power plant or the condensate water supply pipeline or the circulating water return pipeline of the heating network. The hot water pipeline of the water-cooled heat exchanger 702 is connected to any one of the water supply pipelines of the boiler or the deaerator of the thermal power plant or the circulating water return pipeline of the heating network. The water-cooled heat exchanger 702 is provided with an adjustable flow control valve 401 at the connection with the water channel to adjust the water flow in each pipeline.

[0055] The air-cooled heat exchanger 701 and the water-cooled heat exchanger 702 heat the air and water inside them through the heat released during the cooling process of the pyrolysis gas, and input the heated air and water into the production system of the thermal power plant. The hot air can be sent to the power station boiler 1 to assist the combustion of coal in the furnace, saving its own energy consumption. The hot water can be sent to the boiler water supply pipeline or the deaerator water supply pipeline or the heat network circulating water supply pipeline, reducing the energy consumption of heating cold water in the water supply system or the condensate water system or the heat network circulating water system, and making full use of the heat released by the cooling of the pyrolysis gas.

[0056] In this system, the raw material decomposed by the pyrolysis furnace 5 can be any one or more of raw coal, biomass, garbage, and sludge. The pyrolysis gas generated by the heating and decomposition of the pyrolysis furnace 5 is discharged into the pyrolysis gas cooling, purification and separation device 6, and tar and combustible gas can be generated after cooling. The combustible gas is introduced into the hot air duct of the air supply system 2 and finally enters the power station boiler 1 for combustion assistance; the waste gas generated by the pyrolysis furnace 5 or the pyrolysis gas cooling, purification and separation device 6 is sent to the power station boiler 1 and its flue gas treatment device can be used for harmless treatment. The waste slag and waste liquid generated by the pyrolysis furnace 5 or the pyrolysis gas cooling, purification and separation device 6 can be sent to the thermal power plant treatment facilities for harmless treatment.

[0057] The air supply system 2 delivers cold air. After the cold air passes through the diversion device 201, a part of it enters the air preheater 8 arranged in the power station boiler 1 for preheating, and a part of it enters the pyrolysis gas cooling, purification and separation device 6. It is heated by the pyrolysis gas in the pyrolysis gas cooling, purification and separation device 6 through the air-cooled heat exchanger 701. The hot air heated by the air preheater 8 and the air-cooled heat exchanger 701 is combined through the converging device 202 and enters the hot air duct of the air supply system 2. The air supply system 2 may deliver primary air. At this time, the outlet of the hot air duct of the air supply system 2 is connected to the pulverizing system 9. The outlet of the pulverizing system 9 is connected to the power station boiler burner 10. The heated primary air carries the pulverized coal produced in the pulverizing system 9 into the power station boiler burner 10. The hot primary air can ensure that the pulverized coal has a certain temperature when it enters the power station boiler 1, which is convenient for its full combustion and improves the energy utilization rate. The air supply system 2 may deliver secondary air. At this time, the hot air duct of the air supply system 2 is directly connected to the power station boiler burner 10. The power station boiler 1 The secondary air used is usually high-temperature air, and its usage is the largest. Heating only through the air preheater 8 will consume a lot of heat in the power station boiler 1, affecting the energy utilization rate. Heating part of the secondary air through the pyrolysis gas cooling purification separation device 6 can significantly improve the energy utilization rate in the power station boiler 1. In addition, when the power station boiler 1 of the thermal power plant is running at a low load, the air inlet of the air preheater 8 can be closed, and the pyrolysis gas cooling heat can be fully utilized to replace the heat absorbed by the air preheater 8, maintaining the SCR inlet flue gas temperature above 310 degrees under the low load of the boiler, and ensuring the normal operation of the SCR system under low load.

[0058] The water-cooled heat exchanger 702 can be connected to the water supply system of the thermal power plant. The feed water from the deaerator is pressurized by the feed water pump and sent to the cold water pipeline of the water-cooled heat exchanger 702 of the pyrolysis gas cooling, purification and separation device 6. The hot water pipeline of the pyrolysis gas cooling, purification and separation device 6 is connected to the power station boiler 1. The pyrolysis gas in the pyrolysis gas cooling, purification and separation device 6 is used to heat the feed water. When it meets the boiler water accumulation temperature requirement, it is input into the power station boiler 1. The water-cooled heat exchanger 702 can also be connected to the condensate system. The condensate from the condenser is pressurized by the condensate pump and sent to the cold water pipeline of the water-cooled heat exchanger 702 of the pyrolysis gas cooling, purification and separation device 6. The hot water pipeline of the water-cooled heat exchanger 702 is connected to the deaerator. The pyrolysis gas in the pyrolysis gas cooling, purification and separation device 6 is used to heat the feed water. When it meets the boiler water accumulation temperature requirement, it is input into the power station boiler 1. The condensate is heated in a certain amount, and when the condensate meets the temperature requirement, it is pumped into the deaerator; the water-cooled heat exchanger 702 can also be connected to the heat network circulation system of the heating network, and the heat network return water returned from the heating network is sent to the cold water pipeline of the water-cooled heat exchanger 702 of the pyrolysis gas cooling purification separation device 6, and the hot water pipeline of the water-cooled heat exchanger 702 is connected to the heating network, and the heat of the pyrolysis gas cooling is used to heat the heat network circulating water, and the heated heat network circulating water that meets the temperature requirement is pumped into the heating network; the heat released by the pyrolysis gas cooling is used to heat the cold water in the water circuit, thereby reducing the energy consumption specifically for heating it. At the same time, the setting of the adjustable control valve 401 can control the amount of water entering the pyrolysis gas cooling system, so that the pyrolysis gas cooling system is in a heat exchange equilibrium state.

[0059] Example 2

[0060] The present embodiment provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant, the pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant comprises a power station boiler 1 and an air supply system 2 thereof, a steam turbine 3 and a steam-water system 4 thereof, and also comprises a pyrolysis furnace 5 and a pyrolysis gas cooling, purification and separation device 6 thereof, wherein a heat exchange device 7 is provided in the pyrolysis gas cooling, purification and separation device 6, and the heat exchange device 7 comprises an air-cooled heat exchanger 701.

[0061] like Figure 2 As shown, compared with Example 1, this embodiment only includes an air-cooled heat exchanger 701. After the cold air delivered by the air supply system 2 passes through the diversion device 201, a part of it enters the air preheater 8 arranged in the power station boiler 1 for preheating, and a part of it enters the pyrolysis gas cooling, purification and separation device 6. The pyrolysis gas in the pyrolysis gas cooling, purification and separation device 6 is heated by the air-cooled heat exchanger 701. The hot air heated by the air preheater 8 and the air-cooled heat exchanger 701 is merged through the merging device 202 and enters the hot air duct of the air supply system 2. The merged hot air is finally transported into the power station boiler burner 10, saving the energy consumption of preheating part of the cold air of the power station boiler 1.

[0062] Example 3

[0063] The present embodiment provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant, the pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant comprises a power station boiler 1 and an air supply system 2 thereof, a steam turbine 3 and a steam-water system 4 thereof, and also comprises a pyrolysis furnace 5 and a pyrolysis gas cooling, purification and separation device 6 thereof, wherein a heat exchange device 7 is provided in the pyrolysis gas cooling, purification and separation device 6, and the heat exchange device 7 comprises an air-cooled heat exchanger 701.

[0064] like Figure 3 As shown, the air supply system 2 delivers cold primary air. After the cold primary air passes through the diversion device 201, a part of it enters the air preheater 8 arranged in the power station boiler 1 for preheating, and a part of it enters the pyrolysis gas cooling, purification and separation device 6, and is heated by the pyrolysis gas in the pyrolysis gas cooling, purification and separation device 6 through the air-cooled heat exchanger 701. The hot primary air heated by the air preheater 8 and the air-cooled heat exchanger 701 is combined through the merging device 202 and enters the hot air duct of the air supply system 2. The hot air duct of the air supply system 2 is directly connected to the power station boiler burner 10. Since the secondary air used by the power station boiler 1 is usually high-temperature air and its usage is the largest, heating it only through the air preheater 8 will consume a large amount of heat in the power station boiler 1, affecting the energy utilization rate. Heating part of the secondary air through the pyrolysis gas cooling purification and separation device 6 can significantly improve the energy utilization rate in the power station boiler 1. In addition, when the power station boiler 1 of the thermal power plant is running at a low load, the air inlet of the air preheater 8 can be closed, and the pyrolysis gas cooling heat can be fully utilized to replace the heat absorbed by the air preheater 8, so as to maintain the SCR inlet flue gas temperature above 310 degrees under the low load of the boiler, and ensure the normal operation of the SCR system under low load.

[0065] Example 4

[0066] The present embodiment provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant, the pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant comprises a power station boiler 1 and an air supply system 2 thereof, a steam turbine 3 and a steam-water system 4 thereof, and also comprises a pyrolysis furnace 5 and a pyrolysis gas cooling, purification and separation device 6 thereof, wherein a heat exchange device 7 is provided in the pyrolysis gas cooling, purification and separation device 6, and the heat exchange device 7 comprises an air-cooled heat exchanger 701.

[0067] like Figure 4As shown, the air supply system 2 delivers cold secondary air. After the cold secondary air passes through the diversion device 201, a part of it enters the air preheater 8 arranged in the power station boiler 1 for preheating, and a part of it enters the pyrolysis gas cooling, purification and separation device 6, and is heated by the pyrolysis gas in the pyrolysis gas cooling, purification and separation device 6 through the air-cooled heat exchanger 701. The hot secondary air heated by the air preheater 8 and the air-cooled heat exchanger 701 is combined through the merging device 202 and enters the hot air duct of the air supply system 2. The hot air duct of the air supply system 2 is directly connected to the power station boiler burner 10. Since the secondary air used by the power station boiler 1 is usually high-temperature air and its usage is the largest, heating it only through the air preheater 8 will consume a large amount of heat in the power station boiler 1, affecting the energy utilization rate. Heating part of the secondary air through the pyrolysis gas cooling purification and separation device 6 can significantly improve the energy utilization rate in the power station boiler 1. In addition, when the power station boiler 1 of the thermal power plant is running at a low load, the air inlet of the air preheater 8 can be closed, and the pyrolysis gas cooling heat can be fully utilized to replace the heat absorbed by the air preheater 8, so as to maintain the SCR inlet flue gas temperature above 310 degrees under the low load of the boiler, and ensure the normal operation of the SCR system under low load.

[0068] Example 5

[0069] The present embodiment provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant, wherein the pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant includes a power station boiler 1 and an air supply system 2, a steam turbine 3 and a steam-water system 4, and also includes a pyrolysis furnace 5 and a pyrolysis gas cooling, purification and separation device 6. A heat exchange device 7 is provided in the pyrolysis gas cooling, purification and separation device 6, and the heat exchange device 7 includes a water-cooled heat exchanger 702.

[0070] like Figure 5 As shown, the cold water pipeline of the water-cooled heat exchanger 702 is connected to any one of the water supply pipeline of the power station boiler 1 of the thermal power plant or the condensate water supply pipeline or the circulating water return pipeline of the heat network, and the hot water pipeline of the water-cooled heat exchanger 702 is connected to any one of the water supply pipeline of the power station boiler 1 of the thermal power plant or the deaerator or the circulating water supply pipeline of the heat network. The steam-water system 4 is provided with a control valve 401 to control the inlet and outlet and flow rate of the cooling medium. A part of the boiler feed water or condensate water or the circulating water return water of the heat network in the steam-water system 4 enters the pyrolysis gas cooling purification separation device 6 for heat exchange, and the water after pyrolysis enters the power station boiler 1 or the deaerator water supply pipeline or the circulating water supply pipeline of the heat network, reducing the energy consumption of heating it. At the same time, the setting of the adjustable control valve 401 can control the amount of water entering the pyrolysis gas cooling system, so that the pyrolysis gas cooling system is in a heat exchange equilibrium state.

[0071] Example 6

[0072] The present embodiment provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant, wherein the pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant includes a power station boiler 1 and an air supply system 2, a steam turbine 3 and a steam-water system 4, and also includes a pyrolysis furnace 5 and a pyrolysis gas cooling, purification and separation device 6. A heat exchange device 7 is provided in the pyrolysis gas cooling, purification and separation device 6, and the heat exchange device 7 includes a water-cooled heat exchanger 702.

[0073] In this embodiment, the heat from the pyrolysis gas cooling is used to heat the feed water for the power station boiler 1. The feed water coming out of the deaerator and pressurized by the feed water pump is sent to the cold water pipeline of the water-cooled heat exchanger 702 of the pyrolysis gas cooling, purification and separation device 6. The heat from the pyrolysis gas cooling is used to heat the feed water, and the heated feed water that meets the boiler feed water temperature requirement is pumped into the power station boiler 1.

[0074] Example 7

[0075] The present embodiment provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant. The present embodiment provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant. The pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant includes a power station boiler 1 and an air supply system 2, a steam turbine 3 and a steam-water system 4, and also includes a pyrolysis furnace 5 and a pyrolysis gas cooling, purification and separation device 6. A heat exchange device 7 is provided in the pyrolysis gas cooling, purification and separation device 6, and the heat exchange device 7 includes a water-cooled heat exchanger 702.

[0076] In this embodiment, the heat from the pyrolysis gas cooling is used to heat the condensate of the thermal power unit. The condensate coming out of the condenser and pressurized by the condensate pump is sent to the cold water pipeline of the water-cooled heat exchanger 702 of the pyrolysis gas cooling, purification and separation device 6. The condensate is heated by the heat from the pyrolysis gas cooling, and the heated condensate that meets the temperature requirements is pumped into the deaerator.

[0077] Example 8

[0078] The present embodiment provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant. The present embodiment provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant. The pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant includes a power station boiler 1 and an air supply system 2, a steam turbine 3 and a steam-water system 4, and also includes a pyrolysis furnace 5 and a pyrolysis gas cooling, purification and separation device 6. A heat exchange device 7 is provided in the pyrolysis gas cooling, purification and separation device 6, and the heat exchange device 7 includes a water-cooled heat exchanger 702.

[0079] In this embodiment, the heat from the pyrolysis gas cooling is used to heat the hot network circulating water of the heating network of the thermal power plant. The hot network return water returned from the heating network is sent to the cold water pipeline of the water-cooled heat exchanger 702 of the pyrolysis gas cooling, purification and separation device 6. The heat from the pyrolysis gas cooling is used to heat the hot network circulating water, and the heated hot network circulating water that meets the temperature requirements is pumped into the heating network.

[0080] Example 9

[0081] The present embodiment provides a pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant, and its structure is basically the same as that described in any one of Embodiments 1-8, except that an airflow control valve 501 is provided on the pyrolysis gas pipeline at the outlet of the pyrolysis furnace 5, and the airflow control valve 501 can control a part of the pyrolysis gas to be sent into the pyrolysis gas cooling, purification and separation device 6 for cooling, and at the same time, another part of the pyrolysis gas can be directly sent into the power station boiler 1, so that it directly becomes the heat source of the power station boiler 1, saving intermediate links and reducing energy consumption. The airflow control valve 501 can be provided in Embodiments 1-8.

[0082] Example 10

[0083] This embodiment provides a method for cooling a pyrolysis gas cooling system of a pyrolysis furnace in a thermal power plant. The pyrolysis gas cooling system of the pyrolysis furnace is designed according to the following method:

[0084] S1. According to the type and scale of the pyrolysis furnace 5, the total amount of heat required to be removed by cooling the hot pyrolysis gas is calculated. The calculation formula is:

[0085] Q 总 =M 热解气 *Cp 热解气 *(T 热气 -T 冷气 );

[0086] Q 总 is the total heat dissipation of hot pyrolysis gas in the pyrolysis gas cooling, purification and separation device 6, kJ / h; M 热解气 is the mass of pyrolysis gas involved in heat exchange, kg / h; Cp 热解气 is the specific heat capacity of pyrolysis gas, kJ / kg℃; T 热气 is the temperature of the hot pyrolysis gas entering the pyrolysis gas cooling, purification and separation device 6, °C; T 冷气 is the temperature of the cold pyrolysis gas discharged from the pyrolysis gas cooling, purification and separation device 6, °C;

[0087] S2. According to the total heat dissipation of the hot pyrolysis gas of the pyrolysis gas cooling, purification and separation device 6, the heat exchange surface area of ​​the heat exchange device arranged in the pyrolysis gas cooling, purification and separation device 6 and the required cooling air and / or water volume, flow rate, inlet temperature and outlet temperature are designed;

[0088] S3. Design the amount and temperature of air and / or water delivered to the pyrolysis gas cooling, purification and separation device 6 according to the conditions of the thermal power plant air supply system 2 and the steam-water system 4 and the ambient temperature;

[0089] The heat balance equation for heat exchange between pyrolysis gas and cooling air and / or water is:

[0090] Q 总 =M 风 *Cp风 *(T 热风 -T 冷风 )+M 水 *Cp 水 *(T 热水 -T 冷水 )+Q 损失 ;

[0091] Q 总 is the total heat dissipation of hot pyrolysis gas from the pyrolysis gas cooling, purification and separation device 6, kJ / h; Q 损失 Heat loss from heat exchange and heat dissipation of the pyrolysis gas cooling, purification and separation device 6, kJ / h; M 风 is the cooling air volume involved in cooling, kg / h; Cp 风 is the specific heat capacity of primary air or secondary air, kJ / kg℃; M 水 is the amount of cooling water involved in cooling, kg / h; Cp 水 is the specific heat capacity of water, kJ / kg℃; T 热风 is the temperature of the hot air after heating in the pyrolysis gas cooling, purification and separation device 6, ℃; T 冷风 T is the cold air temperature entering the pyrolysis gas cooling, purification and separation device 6, °C; 热水 is the temperature of the hot water after heating in the pyrolysis gas cooling, purification and separation device 6, °C; T 冷水 is the temperature of the cold water entering the pyrolysis gas cooling, purification and separation device 6, °C;

[0092] S4. Complete the installation and connection of the pyrolysis gas cooling system of the thermal power plant pyrolysis furnace according to the design results of S2 and S3;

[0093] S5. Utilize the flow dividing device 201, the flow combining device 202 on the air supply system 2 and / or the control valve 401 on the steam-water system 4 to control the amount of air and / or water sent to the pyrolysis gas cooling, purification and separation device 6 for absorbing heat, and further control the outlet temperature of the hot air and / or hot water pipeline of the pyrolysis gas cooling, purification and separation device 6, so that the system reaches the heat balance described in S3.

[0094] The above specific embodiments further explain the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant, comprising a power plant boiler (1) and its air supply system (2), a steam turbine (3) and its steam-water system (4), characterized in that: It also includes a pyrolysis furnace (5) and a pyrolysis gas cooling, purification and separation device (6) thereof, wherein the pyrolysis gas cooling, purification and separation device (6) is provided with a heat exchange device (7), wherein the heat exchange device (7) is an air-cooled heat exchanger (701) and a water-cooled heat exchanger (702), wherein the cooling medium in the air-cooled heat exchanger (701) and the water-cooled heat exchanger (702) cools the pyrolysis gas in the pyrolysis gas cooling, purification and separation device (6), wherein the cooling medium heated at the outlet of the air-cooled heat exchanger (701) can be transported to a power station boiler (1) or a pulverizing system (9), and wherein the cooling medium heated at the outlet of the water-cooled heat exchanger (702) can be transported to a boiler water supply pipeline, a deaerator water supply pipeline or a heat network circulating water supply pipeline; The air supply system (2) is connected to the air preheater (8) and the air-cooled heat exchanger (701), and the air supply system (2) is also provided with at least one flow dividing device (201) and at least one flow combining device (202); the steam-water system (4) is connected to the water-cooled heat exchanger (702); In addition, the flow dividing device (201) and the flow combining device (202) can adjust the flow in each air duct; the combustible gas purified and separated by the pyrolysis gas cooling purification separation device (6) is subsequently treated or introduced into the power station boiler burner (10); the waste gas generated by the pyrolysis gas cooling purification separation device (6) is sent into the power station boiler (1); the waste residue and waste liquid generated by the pyrolysis furnace (5) or the pyrolysis gas cooling purification separation device (6) are sent to the thermal power plant treatment facility; The inlet of the flow dividing device (201) is introduced with cold primary air, and the outlet thereof is connected to the cold air duct of the air preheater (8) and the air-cooled heat exchanger (701); the inlet of the flow combining device (202) is connected to the hot air duct of the air preheater (8) and the air-cooled heat exchanger (701), and the outlet thereof is connected to the powder making system (9); and the outlet of the powder making system (9) is connected to the power station boiler burner (10); Or the inlet of the flow dividing device (201) is connected to cold secondary air, and its outlet is connected to the cold air duct of the air preheater (8) and the air-cooled heat exchanger (701); the inlet of the flow combining device (202) is connected to the hot air duct of the air preheater (8) and the air-cooled heat exchanger (701), and its outlet is connected to the power station boiler burner (10).

2. A pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant according to claim 1, characterized in that: The cooling medium circulating in the air-cooled heat exchanger (701) is the cold primary air or secondary air of the power station boiler (1).

3. A pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant according to claim 1, characterized in that: The heat exchange device (7) is provided with a water-cooled heat exchanger (702), and the cooling medium flowing inside the water-cooled heat exchanger (702) is any one of the feed water of the power station boiler (1), condensate water or heat network circulating return water.

4. A pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant as claimed in claim 3, characterized in that: The cold water pipeline of the water-cooled heat exchanger (702) is connected to any one of the water supply pipelines of the power station boiler (1) of the thermal power plant or the condensate water supply pipeline or the heat network circulating water return pipeline, and the hot water pipeline of the water-cooled heat exchanger (702) is connected to any one of the water supply pipelines of the power station boiler (1) of the thermal power plant or the deaerator or the heat network circulating water supply pipeline. A control valve (401) is provided in the steam-water system (4) to control the inlet and outlet and flow rate of the cooling medium.

5. A pyrolysis gas cooling system for a pyrolysis furnace in a thermal power plant as claimed in claim 4, characterized in that: The air-cooled heat exchanger (701) or the water-cooled heat exchanger (702) is a surface-type spaced heat exchange coil, and the coil is any one of a plain tube, an inner finned tube, an outer finned tube, or a heat exchange tube with fins inside and outside.

6. A method for cooling a pyrolysis gas system of a pyrolysis furnace in a thermal power plant, characterized in that: The method is applied to a pyrolysis gas cooling system of a pyrolysis furnace in a thermal power plant according to any one of claims 1 to 5, and the pyrolysis gas cooling system of the pyrolysis furnace is designed according to the following method: S1. According to the type and scale of the pyrolysis furnace (5), the total amount of heat required to be removed by cooling the hot pyrolysis gas is calculated. The calculation formula is: Q 总 =M 热解气 *Cp 热解气 *(T 热气 -T 冷气 ); Q 总 is the total heat dissipation of hot pyrolysis gas in the pyrolysis gas cooling, purification and separation device (6), kJ / h; M 热解气 is the mass of pyrolysis gas involved in heat exchange, kg / h; Cp 热解气 is the specific heat capacity of pyrolysis gas, kJ / kg℃; T 热气 T is the temperature of the hot pyrolysis gas entering the pyrolysis gas cooling, purification and separation device (6), °C; 冷气 is the temperature of the cold pyrolysis gas discharged from the pyrolysis gas cooling, purification and separation device (6), °C; S2. Designing the heat exchange surface area of ​​the heat exchange device (7) arranged in the pyrolysis gas cooling, purification and separation device (6) and the required cooling air and water volume, flow rate, inlet temperature and outlet temperature according to the total heat dissipation of the hot pyrolysis gas in the pyrolysis gas cooling, purification and separation device (6); S3. According to the conditions of the air supply system (2) and the steam-water system (4) of the thermal power plant and the ambient temperature, the amount and temperature of air and water supplied to the pyrolysis gas cooling, purification and separation device (6) are designed; The heat balance equation for heat exchange between pyrolysis gas and cooling wind and water is: Q 总 =M 风 *Cp 风 *(T 热风 -T 冷风 )+M 水 *Cp 水 *(T 热水 -T 冷水 )+Q 损失 ； Q 总 is the total heat dissipation of hot pyrolysis gas from the pyrolysis gas cooling, purification and separation device (6), kJ / h; Q 损失 The heat loss of heat exchange and heat dissipation in the pyrolysis gas cooling, purification and separation device (6), kJ / h; M 风 is the cooling air volume involved in cooling, kg / h; Cp 风 is the specific heat capacity of primary air or secondary air, kJ / kg℃; M 水 is the amount of cooling water involved in cooling, kg / h; Cp 水 is the specific heat capacity of water, kJ / kg℃; T 热风 Cooling, purifying and separating device for pyrolysis gas (6) Hot air temperature after internal heating, ℃; T 冷风 T is the temperature of the cold air entering the pyrolysis gas cooling, purification and separation device (6), °C; 热水 is the temperature of the hot water after heating in the pyrolysis gas cooling, purification and separation device (6), °C; T 冷水 is the temperature of the cold water entering the pyrolysis gas cooling, purification and separation device (6), °C; S4, complete the installation and connection of the pyrolysis gas cooling system of the thermal power plant pyrolysis furnace (5) according to the design results of S2 and S3; S5. Utilizing the flow dividing device (201) and the flow combining device (202) on the air supply system (2) and the control valve (401) on the steam-water system (4), the amount of air and water supplied to the pyrolysis gas cooling, purification and separation device (6) for absorbing heat is controlled, thereby controlling the outlet temperature of the hot air and hot water pipes of the pyrolysis gas cooling, purification and separation device (6), so that the system reaches the heat balance described in S3.

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