A waste incineration power generation coupling system

Abstract

The present invention discloses a waste incineration power generation coupling system, including: a waste incineration boiler; a power generation unit, which uses steam from the waste incineration boiler to generate power; a flue gas purification unit, which purifies the flue gas from the waste incineration boiler; a waste heat recovery unit, which recovers the waste heat of the purified flue gas and then discharges the flue gas; an air preheating unit, including a preheater body configured as a low-temperature section and a high-temperature section along the air flow direction, the high-temperature section of the preheater body uses the extraction steam from the power generation unit and the extraction steam from the waste incineration boiler to heat the cold air, and the low-temperature section of the preheater body uses the high-temperature section condensate from the high-temperature section to preheat the cold air, so as to obtain hot air that can be sent to the waste incineration boiler and condensate that can be directly sent to the deaerator in the power generation unit and the temperature meets the requirements of the deaerator. The present invention can recover the waste heat of the tail flue gas and can directly discharge the condensate of the air preheater to the deaerator, which is conducive to improving the thermal efficiency and environmental protection indicators of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of waste incineration treatment, and more particularly to a waste incineration power generation coupling system. Background Art

[0002] With the improvement of people's living standards, the output of urban domestic waste has increased sharply, and the trend of garbage siege has continued to expand. Traditional treatment methods such as landfill and composting will pollute the atmosphere, soil, water sources, etc. and threaten the health of the people. The best way to deal with garbage is to treat it as a resource, harmless and reduced. The waste incineration power generation technology represented by grates and CFB boilers has developed into the mainstream technology for harmless waste treatment due to its advantages of small footprint, significant reduction and high resource utilization.

[0003] The existing waste incineration power generation technology has the following problems:

[0004] 1) The flue gas temperature at the dust collector outlet is 40-70°C higher than the acid dew point. In the prior art, the flue gas is directly discharged into the chimney from the dust collector outlet without waste heat recovery, which affects the thermal efficiency of the system.

[0005] 2) Waste incinerators are often equipped with steam air preheaters for preheating primary and secondary air, which is beneficial to the drying and combustion of waste. The outlet condensate temperature of the air preheater is about 200°C. The existing technology directly introduces condensate into the deaerator or into the drain header. The former is prone to cause local overheating of the deaerator and affect the deoxidation performance, and the latter does not recycle the waste heat of condensate and affects the thermal efficiency of the system.

[0006] 3) The flue gas purification systems of the currently operated waste power plants usually do not have SCR systems, and only use SNCR in the flue area for denitrification, which cannot meet more stringent environmental protection standards such as ultra-clean emissions in the future. On the other hand, because the deacidification system has a certain temperature drop, the inlet flue gas temperature of the SCR system is around 155°C, which is not in the optimal reaction range of conventional catalysts, affecting the denitrification efficiency. Summary of the invention

[0007] In view of the above problems existing in the prior art, the present invention provides a waste incineration power generation coupling system which can recover the waste heat of tail flue gas and directly discharge the condensate of air preheater to the deaerator, thereby improving the thermal efficiency and environmental protection index of the system.

[0008] To this end, the present invention provides a waste incineration power generation coupling system, the system comprising:

[0009] Waste incineration boilers;

[0010] A power generation unit, wherein the power generation unit utilizes steam from a waste incineration boiler to generate electricity;

[0011] A flue gas purification unit, wherein the flue gas purification unit purifies the flue gas from the waste incineration boiler;

[0012] A waste heat recovery unit, wherein the waste heat recovery unit recovers the waste heat of the purified flue gas and then discharges the flue gas;

[0013] An air preheating unit, the air preheating unit includes a preheater body configured as a low-temperature section and a high-temperature section along the air flow direction, the high-temperature section of the preheater body utilizes the extraction steam from the power generation unit and the extraction steam from the waste incineration boiler to heat the cold air, and the low-temperature section of the preheater body utilizes the high-temperature section condensate from the high-temperature section to preheat the cold air, thereby obtaining hot air that can be delivered to the waste incineration boiler and condensate that can be directly delivered to the deaerator in the power generation unit and the temperature of which meets the requirements of the deaerator.

[0014] Furthermore, the power generation unit includes a steam turbine and a motor connected to the steam turbine, the steam turbine includes a cylinder, a condenser, a deaerator and a heater, the steam from the waste incineration boiler enters the cylinder to do work, the exhaust steam enters the condenser to become condensed water and then passes through the heater and deaerator in sequence before returning to the waste incineration boiler for circulation.

[0015] Furthermore, the waste heat recovery unit is a tubular heat exchanger, the heat exchange tube inlet of the waste heat recovery unit is connected to the condenser and the heat exchange tube outlet is connected to the deaerator, and the condensate inlet and outlet temperatures of the waste heat recovery unit match the inlet and outlet temperatures of the heater.

[0016] Furthermore, the air purification unit includes a deacidification subunit, an activated carbon injection subunit, a dust removal subunit, a steam heating subunit and an SCR subunit which are connected in sequence, and the steam heating subunit utilizes extraction steam from a power generation unit and / or extraction steam from a waste incineration boiler to heat the flue gas to a preset temperature range of a catalyst in the SCR subunit.

[0017] Furthermore, the steam heating subunit is a tubular heat exchanger, and the condensate outlet of the steam heating subunit is connected to the air preheating unit, so that the obtained condensate is sent to the air preheating unit to mix with the high-temperature section condensate to preheat the cold air.

[0018] Furthermore, the high temperature section of the preheater body includes a low-pressure steam extraction section and a high-pressure steam extraction section arranged in sequence along the air flow direction, the steam source of the low-pressure steam extraction section comes from the power generation unit, and the steam source of the high-pressure steam extraction section comes from the waste incineration boiler.

[0019] Furthermore, the air preheating unit also includes a flash tank connected to the preheater body, the condensate outlet of the high-pressure steam extraction section is connected to the flash tank through a first pipeline, the condensate outlet of the low-pressure steam extraction section is connected to the low-temperature section through a second pipeline, and the condensate outlet of the low-temperature section is connected to the deaerator.

[0020] Furthermore, the high-pressure condensate from the high-pressure steam extraction section is reduced in pressure in a flash tank and then mixed with the low-pressure condensate from the low-pressure steam extraction section to obtain the high-temperature section condensate as the heat source of the low-temperature section and sent to the low-temperature section to heat the cold air. The high-temperature section condensate is cooled to 125-135°C and then sent to the deaerator.

[0021] Furthermore, the condensate outlet of the steam heating subunit is connected to the first pipeline or the second pipeline through a pipeline so as to merge the condensate of the steam heating subunit into the high-pressure condensate or the low-pressure condensate generated by the preheater body.

[0022] Furthermore, a chimney is provided downstream of the waste heat recovery unit.

[0023] Compared with the existing conventional waste-to-energy system, the present invention has the following advantages:

[0024] 1) This system is equipped with a waste heat recovery unit to recover the waste heat of the tail flue gas while ensuring that low-temperature corrosion is controllable, thereby improving the thermal efficiency of the system;

[0025] 2) This system adds a low-temperature section in the air preheating unit to recover the waste heat of the condensate in the high-temperature section, which can further improve the thermal efficiency of the system. On the other hand, the condensate at the outlet of the preheater releases heat and cools down to about 130°C, which can be directly returned to the steam turbine deaerator without affecting the performance of the deaerator.

[0026] 3) The system may be further provided with an SCR subunit and a steam heating subunit. The steam heating subunit heats the flue gas to the optimal temperature range of the SCR reaction, thereby ensuring the denitrification efficiency of the SCR and achieving ultra-low NOx emissions. In addition, the condensate of the steam heating subunit may be incorporated into the high-temperature section condensate of the air preheating unit at an appropriate location, thereby realizing waste heat recovery using the existing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic structural diagram of a waste incineration power generation coupling system according to an exemplary embodiment of the present invention is shown.

[0028] Figure 2 The structure and flow chart of an air preheater in a waste incineration power generation coupling system according to an exemplary embodiment of the present invention is shown.

[0029] Description of reference numerals:

[0030] 1-waste incineration boiler, 2-steam turbine, 3-motor, 4-flue gas purification unit, 5-waste heat recovery unit, 6-chimney, 7-air preheating unit, 71-preheater body, 72-flash tank, 8-steam heating subunit, 9-SCR subunit. DETAILED DESCRIPTION

[0031] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0032] Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0033] Based on the problems in the prior art, the present invention proposes a waste incineration power generation coupling system, which is provided with a flue gas purification unit, which preferably includes processes such as deacidification, activated carbon injection, dust removal, SCR denitrification, etc., to ensure that the acid dew point of the purified flue gas is below 120°C; the system is provided with a waste heat recovery unit at the tail end of the flue gas purification unit, which reduces the flue gas temperature to about 125°C before discharging it into the chimney, and the recovered heat is used to heat the turbine condensate, and the condensate flow rate can be calculated based on the flue gas heat release and the condensate enthalpy increase; the system also improves the structure of the air preheating unit, and adds a low-temperature section to the preheater body at the inlet section of the cold air, and uses the high-temperature section condensate to preheat the cold air. The condensate releases heat and is cooled to 130°C before being sent to the turbine deaerator.

[0034] Furthermore, the system may also be equipped with an SCR subunit to further remove NOx, and a steam heating subunit is arranged between the dust removal subunit and the SCR subunit. The steam heating subunit extracts part of the steam to heat the flue gas to about 180°C, and the heated flue gas then enters the SCR subunit for denitrification. The condensate of the steam heating subunit can be incorporated into the condensate of the air preheating unit at an appropriate position according to the steam extraction parameters.

[0035] The waste incineration power generation coupling system of the present invention will be described in detail below.

[0036] Figure 1 A schematic structural diagram of a waste incineration power generation coupling system according to an exemplary embodiment of the present invention is shown.

[0037] like Figure 1 As shown, according to an exemplary embodiment of the present invention, the waste incineration power generation coupling system includes a waste incineration boiler 1, a power generation unit, a flue gas purification unit 4, a waste heat recovery unit 5, an air preheating unit 7, etc. Among them, the flue gas purification unit 4 can further include a steam heating subunit 8 and an SCR subunit 9, but the steam heating subunit 8 and the SCR subunit 9 can also be omitted according to the working conditions.

[0038] The waste incineration boiler 1 is a boiler that recovers the calorific value of waste by incinerating waste, and can adopt existing mechanical grate furnaces, CFB waste furnaces and other boiler types in the prior art. The waste is fed from the boiler feed port and burned in the furnace, and the generated high-temperature flue gas exchanges heat with the heating surface of the boiler, transferring the heat to the feed water on the working medium side. The feed water absorbs the heat of the high-temperature flue gas in the boiler to generate main steam with specific parameters, which is then used to generate power.

[0039] The power generation unit utilizes the steam from the waste incineration boiler to generate electricity, which specifically includes a steam turbine 2 and a motor 3 connected to the steam turbine 2. The steam turbine 2 includes a cylinder, a condenser, a deaerator and a heater. The steam from the waste incineration boiler enters the cylinder to perform work, and the exhaust steam enters the condenser to become condensed water and then passes through the heater and the deaerator in sequence before returning to the waste incineration boiler to continue the steam cycle.

[0040] The flue gas purification unit of the present invention purifies the flue gas from the waste incineration boiler, and preferably includes a deacidification subunit (not shown), an activated carbon injection subunit (not shown), a dust removal subunit (not shown), a steam heating subunit and an SCR subunit connected in sequence. The deacidification subunit is used to remove acidic components (HCL, SO 2 etc.); the activated carbon injection subunit injects activated carbon to remove dioxins and heavy metals in the flue gas; the dust removal subunit is used to remove dust in the flue gas, and a bag filter can be used; the steam heating subunit 8 uses the extraction steam from the power generation unit and / or the extraction steam from the waste incineration boiler 1 to heat the flue gas to a preset temperature range of the catalyst in the SCR subunit 9; the SCR subunit is used to denitrify the flue gas, and the SCR system in the prior art can be used.

[0041] The waste heat recovery unit 5 is arranged downstream of the flue gas purification unit, and is used to recover the waste heat of the flue gas after purification and then discharge the flue gas, which is beneficial to improve the thermal efficiency of the system. A chimney 6 is also arranged downstream of the waste heat recovery unit 5 for discharging the flue gas. The waste heat recovery unit 5 is preferably a tubular heat exchanger, and the heat exchange tube inlet of the tubular heat exchanger is connected to the condenser and the heat exchange tube outlet is connected to the deaerator, that is, the medium in the tube is the condensate of the steam turbine and the outlet condensate can be directly incorporated into the deaerator of the steam turbine without affecting the deoxygenation performance or thermal efficiency. In addition, the inlet and outlet temperatures of the condensate of the tubular heat exchanger are controlled to match the inlet and outlet temperatures of the steam turbine heater.

[0042] Figure 2 The structure and flow chart of an air preheater in a waste incineration power generation coupling system according to an exemplary embodiment of the present invention is shown.

[0043] The air preheating unit extracts steam from appropriate positions of the waste incineration boiler 1 and the steam turbine 2 of the power generation unit to preheat the primary air and the secondary air. The preheated air is sent into the waste incineration boiler 1 to help dry and burn the waste.

[0044] like Figure 2 As shown, the air preheating unit of the present invention includes a preheater body configured as a low-temperature section and a high-temperature section along the air flow direction. The high-temperature section of the preheater body uses the extraction steam from the power generation unit and the extraction steam from the waste incineration boiler 1 to heat the cold air. The low-temperature section of the preheater body uses the high-temperature section condensate from the high-temperature section to preheat the cold air, thereby obtaining hot air that can be sent to the waste incineration boiler and condensate that can be directly sent to the deaerator in the power generation unit and whose temperature meets the requirements of the deaerator. Therefore, this system adds a low-temperature section to the preheater body to recover the waste heat of the high-temperature section condensate, which can further improve the thermal efficiency of the system; and the condensate at the outlet of the preheater body has released heat and cooled to about 130°C, and can be directly returned to the deaerator of the steam turbine without affecting the performance of the deaerator.

[0045] The steam heating subunit 8 is a tubular heat exchanger structure, and the medium in the tube is the extraction steam from the appropriate position of the waste incineration boiler 1 or the steam turbine. According to the extraction parameters, the condensed water after the steam is cooled is added to the appropriate position of the air preheating unit 8. Preferably, the condensed water outlet of the steam heating subunit 8 is connected to the air preheating unit, so that the obtained condensed water is sent to the air preheating unit to be mixed with the high-temperature section condensed water to preheat the cold air, and further recover the waste heat.

[0046] like Figure 2 As shown, the high temperature section of the preheater body in the present invention actually includes a low-pressure steam extraction section and a high-pressure steam extraction section arranged in sequence along the air flow direction, that is, the low-pressure steam extraction section and the high-pressure steam extraction section are also collectively referred to as the high-temperature section. The steam source of the low-pressure steam extraction section comes from the steam turbine of the power generation unit, and the steam source of the high-pressure steam extraction section comes from the waste incineration boiler 1. The air preheating unit also includes a flash tank connected to the preheater body, the condensate outlet of the high-pressure steam extraction section is connected to the flash tank through a first pipeline, the condensate outlet of the low-pressure steam extraction section is connected to the low-temperature section through a second pipeline, and the condensate outlet of the low-temperature section is connected to the deaerator.

[0047] Through the above structure, the high-pressure condensate from the high-pressure steam extraction section is reduced in pressure by the flash tank and then mixed with the low-pressure condensate from the low-pressure steam extraction section to obtain the high-temperature section condensate as the heat source of the low-temperature section and sent to the low-temperature section to heat the cold air. After the cold air exchanges heat with the high-temperature section condensate in the low-temperature section, it enters the high-temperature section and continues to be heated by the steam extraction until it becomes hot air and is sent to the waste incineration boiler 1. The high-temperature section condensate is cooled to 125-135°C after heat exchange and is directly sent to the deaerator.

[0048] Based on this, the condensate outlet of the steam heating subunit is connected to the first pipeline or the second pipeline through a pipeline to merge the condensate of the steam heating subunit into the high-pressure condensate or the low-pressure condensate generated by the preheater body.

[0049] Among them, the condensate flow rate of the waste heat recovery unit 5, the steam extraction rate of the steam heating subunit, and the steam extraction rate of the air preheating unit can be calculated according to the heat balance equation.

[0050] The flue gas flow of this system is as follows: garbage is fed in from the feed port and burned in the garbage incineration boiler. The high-temperature flue gas generated exchanges heat with the heating surface in the garbage incineration boiler 1, and the heat is transferred to the working medium side. The cooled flue gas enters the flue gas purification unit 4 for deacidification, activated carbon injection, dust removal, SCR denitrification and other treatments, and is sent to the chimney 6 after the waste heat is recovered by the waste heat recovery unit 5, and finally discharged into the atmosphere.

[0051] The steam-water process of this system is as follows: the feed water in the waste incineration boiler 1 absorbs the heat of the high-temperature flue gas to generate main steam with specific parameters, which is introduced into the cylinder of the steam turbine through the steam connecting pipe to do work, thereby driving the motor 3 to generate electricity. The exhaust steam enters the condenser of the steam turbine and turns into water, passes through the heater and deaerator in turn, and finally returns to the waste incineration boiler 1 through the feed water pump to continue the steam cycle.

[0052] Through the above measures, a waste incineration power generation coupling system can be obtained which has the advantages of high thermal efficiency, excellent environmental protection indicators, and full recovery of waste heat compared with existing solutions.

[0053] The present invention will be further described below in conjunction with specific embodiments.

[0054] Embodiment 1:

[0055] System structure Figure 1 As shown, it includes a waste incineration boiler 1, a steam turbine 2, a motor 3, a flue gas purification unit 4, a waste heat recovery unit 5, a chimney 6 and an air preheating unit 7, etc.

[0056] The flue gas purification unit 4 includes a deacidification subunit, an activated carbon injection subunit, a dust removal subunit, a steam heating subunit 8 and an SCR subunit 9. The steam turbine 2 includes components such as a cylinder, a condenser, a deaerator, and a heater. The waste heat recovery unit 5 is placed between the flue gas purification unit 4 and the chimney 6.

[0057] The high-temperature flue gas generated by the burning of garbage in the garbage incineration boiler 1 is cooled by the heating surface and enters the flue gas purification system 4 for deacidification, activated carbon injection, dust removal, SCR denitrification, etc. The acid dew point of the purified flue gas is lower than 120°C. After the waste heat is recovered by the waste heat recovery unit 5, it is sent to the chimney 6 and finally discharged into the atmosphere. The main steam of the boiler 1 is introduced into the cylinder of the steam turbine 2 through the connecting pipe to do work, and then drives the motor 3 to generate electricity. The exhaust steam enters the condenser of the steam turbine 2 and becomes water. The condensed water passes through the heater, deaerator and feed water pump in turn and finally returns to the garbage incineration boiler 1 to continue the steam cycle.

[0058] The waste heat recovery unit 5 is a tubular heat exchanger used to recover the waste heat of the tail flue gas. Its inlet and outlet flue gas temperatures are 185°C and 125°C respectively. The medium in the tube is the condensate of the turbine 2. The inlet and outlet temperatures of the condensate match the inlet and outlet temperatures of the turbine heater. The condensate at the outlet of the waste heat recovery unit 5 is incorporated into the deaerator of the turbine 2. The amount of condensate required by the waste heat recovery unit 5 needs to be calculated based on the heat balance equation.

[0059] The air preheating unit 7 is a tubular heat exchanger, such as Figure 2 As shown, it includes a preheater body, a flash tank and related connecting pipelines. The preheater body is divided into a low-temperature section, a low-pressure steam extraction section and a high-pressure steam extraction section along the air flow direction. The low-pressure steam extraction section and the high-pressure steam extraction section are collectively referred to as the high-temperature section. The steam sources of the high-pressure and low-pressure steam extraction sections come from the drum of the waste incineration boiler 1 and the cylinder of the steam turbine 2, respectively. The high-pressure condensate at the outlet of the high-pressure steam extraction section is reduced in pressure by the flash tank and mixed with the low-pressure condensate of the low-pressure steam extraction section to become high-temperature section condensate, which is used as a heat source for the low-temperature section to heat the cold air. The high-temperature section condensate is cooled to about 130°C after heat exchange with the cold air and is directly led to the deaerator of the steam turbine 2. Furthermore, the air preheating unit 7 also receives condensate at the outlet of the steam heating subunit 8. For detailed process, see Figure 2 The amount of steam extraction required by the air preheating unit 7 is calculated based on the heat balance equation.

[0060] The steam heating subunit 8 is a tubular heat exchanger, which extracts steam from the low-pressure cylinder outlet of the steam turbine 2 to control the inlet flue gas temperature of the SCR subunit 9 within the optimal temperature range for the catalytic reaction (~185°C). The amount of steam extracted by the steam heating subunit 8 needs to be calculated based on the heat balance equation. The condensate at the outlet of the steam heating subunit 8 is incorporated into the low-pressure condensate of the air preheating unit 7 to further recover waste heat.

[0061] Taking a 2*400t / d, 2000Kcal / kg medium-temperature and sub-high-pressure waste power plant as an example, the heat recovery unit 5 recovers about 4000KW, and the low-temperature section of the air preheating unit 7 recovers an additional heat of about 350KW. The heat consumption of the steam turbine is expected to be reduced by 200KJ / kw.h, and the annual power generation will increase by about 3.3 million KW. In addition, the 130℃ condensate at the outlet of the air preheating unit is directly introduced into the deaerator, which does not affect the performance of the deaerator. At the same time, the inlet flue gas temperature of the SCR subunit is in the optimal reaction range of the catalyst, the denitrification efficiency is high, and ultra-low NOx emissions can be achieved.

[0062] Embodiment 2:

[0063] The structure of this embodiment is basically the same as that of Embodiment 1. The difference from Embodiment 1 is that the steam heating subunit 8 is changed to extract steam from the drum of the waste incineration boiler 1, and the condensate at the outlet of the steam heating subunit 8 is merged into the high-pressure condensate of the air preheating unit 7, and after being reduced in pressure by the flash tank, it is mixed with the low-pressure condensate of the low-pressure extraction section to become high-temperature section condensate, which serves as a heat source for the low-temperature section.

[0064] Embodiment 3:

[0065] The structure of this embodiment is basically the same as that of the embodiment 1. The difference from the embodiment 1 is that the flue gas purification unit 4 does not contain the steam heating subunit 8 and the SCR subunit 9. The flue gas at the economizer outlet directly enters the waste heat recovery unit 5 after being treated with deacidification, activated carbon injection, dust removal, etc., and the inlet flue gas temperature is about 155° C. This embodiment is suitable for power plants with low NOx emission requirements.

[0066] The waste-to-energy coupling system of the present invention is obtained through the system configuration of the above embodiment. The effects of the present invention and the prior art are compared as shown in Table 1 below.

[0067] Table 1 Comparison of the effects of the present invention and the prior art

[0068]

[0069]

[0070] It can be seen from the data in Table 1 that the system of the present invention has the advantages of high thermal efficiency, excellent environmental protection index, and sufficient recovery of waste heat compared with the existing solutions.

[0071] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A waste incineration power generation coupling system, characterized in that: The system comprises: Waste incineration boilers; A power generation unit, wherein the power generation unit utilizes steam from a waste incineration boiler to generate electricity; A flue gas purification unit, wherein the flue gas purification unit purifies the flue gas from the waste incineration boiler; A waste heat recovery unit, wherein the waste heat recovery unit recovers the waste heat of the purified flue gas and then discharges the flue gas; An air preheating unit, the air preheating unit comprising a preheater body configured as a low-temperature section and a high-temperature section along the air flow direction, the high-temperature section of the preheater body utilizing extraction steam from the power generation unit and the extraction steam from the waste incineration boiler to heat cold air, the low-temperature section of the preheater body utilizing high-temperature section condensate from the high-temperature section to preheat cold air, obtaining hot air that can be delivered to the waste incineration boiler and condensate that can be directly delivered to the deaerator in the power generation unit and whose temperature meets the requirements of the deaerator; The power generation unit includes a steam turbine and a motor connected to the steam turbine. The steam turbine includes a cylinder, a condenser, a deaerator and a heater. The steam from the waste incineration boiler enters the cylinder to do work, and the exhaust steam enters the condenser to become condensed water and then passes through the heater and the deaerator in sequence before returning to the waste incineration boiler for circulation. The waste heat recovery unit is a tubular heat exchanger, the heat exchange tube inlet of the waste heat recovery unit is connected to the condenser and the heat exchange tube outlet is connected to the deaerator, and the condensate inlet and outlet temperatures of the waste heat recovery unit match the inlet and outlet temperatures of the heater; The flue gas purification unit comprises a deacidification subunit, an activated carbon injection subunit, a dust removal subunit, a steam heating subunit and an SCR subunit connected in sequence, wherein the steam heating subunit utilizes extraction steam from a power generation unit and / or extraction steam from a waste incineration boiler to heat the flue gas to a preset temperature range of a catalyst in the SCR subunit; The steam heating subunit is a tubular heat exchanger, and the condensate outlet of the steam heating subunit is connected to the air preheating unit, so that the obtained condensate is sent to the air preheating unit to be mixed with the high-temperature section condensate to preheat the cold air; The high temperature section of the preheater body includes a low-pressure steam extraction section and a high-pressure steam extraction section arranged in sequence along the air flow direction. The steam source of the low-pressure steam extraction section comes from the power generation unit, and the steam source of the high-pressure steam extraction section comes from the waste incineration boiler.

2. The waste incineration power generation coupling system according to claim 1, characterized in that: The air preheating unit also includes a flash tank connected to the preheater body, the condensate outlet of the high-pressure steam extraction section is connected to the flash tank through a first pipeline, the condensate outlet of the low-pressure steam extraction section is connected to the low-temperature section through a second pipeline, and the condensate outlet of the low-temperature section is connected to a deaerator.

3. The waste incineration power generation coupling system according to claim 2, characterized in that: The high-pressure condensate from the high-pressure steam extraction section is reduced in pressure in a flash tank and then mixed with the low-pressure condensate from the low-pressure steam extraction section to obtain the high-temperature section condensate as the heat source of the low-temperature section and sent to the low-temperature section to heat the cold air. The high-temperature section condensate is cooled to 125~135℃ and then sent to the deaerator.

4. The waste incineration power generation coupling system according to claim 2, characterized in that: The condensate outlet of the steam heating subunit is connected to the first pipeline or the second pipeline through a pipeline to merge the condensate of the steam heating subunit into the high-pressure condensate or the low-pressure condensate generated by the preheater body.

5. The waste incineration power generation coupling system according to claim 1, characterized in that: A chimney is also provided downstream of the waste heat recovery unit.

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