A waste heat cascade recovery system for a waste incineration power plant

Abstract

The present invention relates to the field of waste heat recovery technology, and in particular to a waste heat cascade recovery system for a waste incineration power plant, including a waste heat recovery system in the power plant, a large temperature difference heat transmission and distribution network, and a low-temperature heat exchange system in an energy station. The waste heat recovery system in the power plant and the low-temperature heat exchange system in the energy station are connected through the heat network water of the large temperature difference heat transmission and distribution network to form a heat supply cycle. Compared with the prior art, the present invention effectively recovers the heat of flue gas in the waste power plant and the heat released by the cooling circulating water to the cooling tower in a cascade manner to meet the heating needs of cities and towns. It is necessary to optimize the system from the heat source supply, heat network transmission and distribution, heat storage and heat users to achieve deep recovery of waste heat from the waste power plant, which can reduce the energy consumption of the thermal power plant, improve the total thermal efficiency of the power plant, and reasonably use energy, and can also reduce the water consumption, electricity consumption and heat loss caused by cooling water or air cooling islands.

Description

Technical Field

[0001] The invention relates to the technical field of waste heat recovery, and in particular to a waste heat cascade recovery system for a waste incineration power plant. Background Art

[0002] With the steady growth of my country's population, urbanization and economic development, the amount of domestic waste generated in my country continues to increase, and the demand for treatment is growing. Waste incineration has the advantages of obvious reduction effect, small footprint, and relatively small impact on the environment. It is the fastest growing way to treat waste harmlessly. From 2008 to 2020, the number of urban domestic waste incineration plants in my country increased from 74 to 658. The daily processing capacity increased from 51,600 tons to 735,800 tons. The waste incineration boiler converts the chemical energy contained in the garbage into high-temperature steam, which drives the turbine to rotate and the generator to generate electricity. The flue gas produced by combustion is treated and discharged into the atmosphere. This not only achieves the harmless treatment of domestic waste, but also achieves the goal of green power generation.

[0003] However, the installed capacity of garbage power plants is small, and the power generation efficiency is only 20-30%. There are also about 60-70% of the exhaust steam and flue gas waste heat dissipated to the atmosphere, and the loss of waste heat causes a waste of energy resources. Among them, the exhaust steam of the steam turbine is cooled into condensed water through an air-cooled or water-cooled heat exchanger and then returned to the garbage incinerator, resulting in a large amount of waste heat loss; the furnace temperature of the existing garbage incinerator is generally around 850℃, and the temperature of the flue gas treated after combustion is about 150℃. In addition, the water content of the garbage is as high as 20% to 30%, the moisture content in the exhaust flue gas is high, and the sensible heat and latent heat of the flue gas waste heat are large. There is still a large amount of waste heat in the flue gas that can be recycled. In terms of the heating technology of garbage cogeneration, some power plants use a combination of extraction condensation heating and low vacuum heating to heat towns. The quality of the extracted steam is high, which does not match the heating temperature requirement, and the deep utilization of the flue gas waste heat is not achieved, resulting in a waste of energy quality and sacrificing part of the power generation.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a waste heat cascade recovery system for a waste incineration power plant to solve the problems mentioned in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A waste heat cascade recovery system for a waste incineration power plant comprises a waste heat recovery system in the power plant, a large temperature difference heat transmission and distribution network and a low-temperature heat exchange system in an energy station. The waste heat recovery system in the power plant and the low-temperature heat exchange system in the energy station are connected through the hot network water of the large temperature difference heat transmission and distribution network to form a heat supply cycle.

[0008] Preferably, the waste heat recovery system in the power plant includes a first garbage boiler, a second garbage boiler, a third garbage boiler, a first steam turbine, a second steam turbine, a third steam turbine, a high-temperature exhaust steam heat exchanger, a medium-temperature exhaust steam heat exchanger, a low-temperature exhaust steam heat exchanger, a flue gas processor, a flue gas partition heat exchanger, a flue gas spray heat exchanger and a chimney; the high-temperature steam outlet of the first garbage boiler is connected to the steam inlet of the first steam turbine, the exhaust steam outlet of the first steam turbine is connected to the high-temperature side exhaust steam inlet of the high-temperature exhaust steam heat exchanger, and the high-temperature side water outlet of the high-temperature exhaust steam heat exchanger is connected to the upper water inlet of the first garbage boiler; the high-temperature steam outlet of the second garbage boiler is connected to the steam inlet of the second steam turbine, and the exhaust steam outlet of the second steam turbine is connected to the exhaust steam outlet of the second steam turbine. The outlet is connected to the high-temperature side exhaust steam inlet of the medium-temperature exhaust steam heat exchanger, and the high-temperature side water outlet of the medium-temperature exhaust steam heat exchanger is connected to the upper water inlet of the second garbage boiler; the high-temperature steam outlet of the third garbage boiler is connected to the steam inlet of the third steam turbine, the exhaust steam outlet of the third steam turbine is connected to the high-temperature side exhaust steam inlet of the low-temperature exhaust steam heat exchanger, and the high-temperature side water outlet of the low-temperature exhaust steam heat exchanger is connected to the upper water inlet of the third garbage boiler; the flue gas generated by the first garbage boiler, the second garbage boiler, and the third garbage boiler enters the flue gas partition wall heat exchanger, the flue gas partition wall heat exchanger is connected to the flue gas processor, the flue gas processor is connected to the flue gas spray heat exchanger, and the flue gas spray heat exchanger is connected to the chimney.

[0009] Preferably, the low-temperature heat exchange system of the energy station includes a plate heat exchanger, a high evaporation temperature electric heat pump, a medium evaporation temperature electric heat pump, a water source heat pump, primary heating network water, and a primary heating network main circulation water pump;

[0010] The primary heat network water passes through the primary heat network main circulation water pump, flue gas spray heat exchanger, low-temperature exhaust steam heat exchanger, medium-temperature exhaust steam heat exchanger, high-temperature exhaust steam heat exchanger, flue gas partition heat exchanger, plate heat exchanger, high evaporation temperature electric heat pump, medium evaporation temperature electric heat pump, and water source heat pump in turn to form the system's thermal cycle.

[0011] Preferably, the energy station low-temperature heat exchange system also includes heat users, cold and hot users, secondary heat network water and secondary heat network main circulation water pump;

[0012] The first branch of the secondary heat network water passes through the secondary heat network main circulation water pump, the plate heat exchanger, the heat user or the cold and hot user in sequence to form the first heat cycle of the terminal energy station;

[0013] The second branch of the secondary heat network water passes through the secondary heat network main circulation water pump, water source heat pump, medium evaporation temperature electric heat pump, high evaporation temperature electric heat pump in sequence, and then mixes with the hot water flowing out of the plate heat exchanger to form the second heat cycle of the terminal energy station.

[0014] Preferably, the low-temperature heat exchange system of the energy station includes a plate heat exchanger, an absorption heat pump, a water source heat pump, primary heat network water, and a primary heat network main circulation water pump;

[0015] A biomass boiler is also provided between the flue gas inter-wall heat exchanger and the plate heat exchanger;

[0016] The primary heat network water passes through the primary heat network main circulation water pump, flue gas spray heat exchanger, low-temperature exhaust steam heat exchanger, medium-temperature exhaust steam heat exchanger, high-temperature exhaust steam heat exchanger, flue gas partition heat exchanger, biomass boiler, plate heat exchanger, absorption heat pump, and water source heat pump in turn to form the system's thermal cycle.

[0017] Preferably, the energy station low-temperature heat exchange system also includes heat users, secondary heat network water and secondary heat network main circulation water pump;

[0018] The first branch of the secondary heat network water passes through the secondary heat network main circulation water pump, the plate heat exchanger, and the heat user in sequence to form the third heat cycle of the terminal energy station;

[0019] The second branch of the secondary heat network water passes through the secondary heat network main circulation water pump, the water source heat pump, and the absorption heat pump in sequence, and is mixed with the hot water flowing out of the plate heat exchanger to form the fourth heat cycle of the terminal energy station.

[0020] Compared with the prior art, the waste heat cascade recovery system of a waste incineration power plant proposed in the present invention has the beneficial effect of effectively recovering the heat of the flue gas in the waste power plant and the heat released by the cooling circulating water to the cooling tower in a cascade manner to meet the heating needs of the town. It is necessary to optimize the system from the heat source supply, heat network transmission and distribution, heat storage and heat users to achieve deep recovery of waste heat from the waste power plant, which can reduce the energy consumption of the thermal power plant, improve the total thermal efficiency of the power plant, and reasonably use energy. It can also reduce the water loss caused by evaporation, wind blowing, etc. in the cooling water tower, and reduce the waste of water resources. At the same time, the flue gas is deeply treated, further reducing pollutant emissions, and the exhaust temperature is reduced to below 25-40°C to achieve the "whitening" effect. The utilization of waste heat from waste power generation flue gas is an integrated project integrating energy saving, emission reduction, water saving and whitening. The waste power plant uses the waste heat of exhaust steam and waste heat of flue gas for heating, which can achieve "low-carbon heating", which is in line with the environmental protection concept of "green development, circular development, low-carbon development, energy saving and emission reduction".

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 This is a structural schematic diagram of a waste heat cascade recovery system for a waste incineration power plant proposed in Example 1 of the present invention.

[0024] Figure 2 This is a structural schematic diagram of a waste heat cascade recovery system for a waste incineration power plant proposed in Example 2 of the present invention.

[0025] Figure 3 This is a control point diagram of a waste heat cascade recovery system for a waste incineration power plant proposed in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0027] like Figure 1 As shown, the present embodiment 1 provides a waste heat cascade recovery system for a waste incineration power plant, comprising a waste heat recovery system in the power plant, a large temperature difference heat transmission and distribution network, and a low-temperature heat exchange system in an energy station. The waste heat recovery system in the power plant and the low-temperature heat exchange system in the energy station are connected through the hot network water of the large temperature difference heat transmission and distribution network to form a heat supply cycle.

[0028] The waste heat recovery system in the power plant includes a first garbage boiler 1, a second garbage boiler 4, a third garbage boiler 7, a first steam turbine 2, a second steam turbine 5, a third steam turbine 8, a high-temperature exhaust steam heat exchanger 3, a medium-temperature exhaust steam heat exchanger 6, and a low-temperature exhaust steam heat exchanger 9; a flue gas processor 11, a flue gas partition heat exchanger 10; a flue gas spray heat exchange tower 12 and a chimney 13. The high-temperature steam outlet of the first garbage boiler 1 is connected to the steam inlet of the first steam turbine 2, the exhaust steam outlet of the first steam turbine 2 is connected to the high-temperature side exhaust steam inlet of the high-temperature exhaust steam heat exchanger 3, and the high-temperature side water outlet of the high-temperature exhaust steam heat exchanger 3 is connected to the upper water inlet of the first garbage boiler 1; the high-temperature steam outlet of the second garbage boiler 4 is connected to the steam inlet of the second steam turbine 5, the exhaust steam outlet of the second steam turbine 5 is connected to the high-temperature side exhaust steam inlet of the medium-temperature exhaust steam heat exchanger 6, and the high-temperature side water outlet of the medium-temperature exhaust steam heat exchanger 6 is connected to the upper water inlet of the second garbage boiler 4; the high-temperature steam outlet of the third garbage boiler 7 is connected to the steam inlet of the third steam turbine 8, and the high-temperature steam outlet of the third steam turbine 8 is connected to the steam inlet of the third steam turbine 8. The exhaust steam outlet of the turbine 8 is connected to the high-temperature side exhaust steam inlet of the low-temperature exhaust steam heat exchanger 9, and the high-temperature side water outlet of the low-temperature exhaust steam heat exchanger 9 is connected to the upper water inlet of the third garbage boiler 7; the flue gas generated by the combustion of garbage in the first garbage boiler 1, the second garbage boiler 4, and the third garbage boiler 7 enters the flue gas inter-wall heat exchanger 10, and performs sensible heat exchange with the hot network water. At this time, the flue gas temperature is reduced to about 100°C, and the flue gas enters the flue gas processor 11. After dust removal and other smoke purification measures, the flue gas enters the spray heat exchanger 12, and performs latent heat exchange with the low-temperature hot network water. The flue gas temperature is reduced to about 25°C, and the moisture content is reduced to about 20g / kg before entering the chimney for discharge.

[0029] The energy station process includes plate heat exchanger 14, high evaporation temperature electric heat pump 15, medium evaporation temperature electric heat pump 16, water source heat pump 17, heat user 18, cold and hot user 19, secondary heat network pipeline 21, secondary heat network main circulation water pump 23, etc. The large temperature difference heat transmission and distribution pipeline connects the power plant and the terminal energy station, improves the energy efficiency of the heat source of the waste power plant and realizes long-distance transmission, mainly including primary heat network pipeline 20 and primary heat network main circulation water pump 22.

[0030] The temperature of the primary heat network water after absorbing the waste heat of the power plant is about 80-90°C. At this time, the primary heat network water enters the terminal energy station and enters the plate heat exchanger 14 to exchange heat with the secondary heat network water. The primary heat network water coming out of the plate heat exchanger 14 enters the three-stage electric heat pump in series in sequence: high evaporation temperature electric heat pump 15, medium evaporation temperature electric heat pump 16, and water source heat pump 17. Here, the low-temperature water (about 15°C) after heat exchange with the secondary heat network water passes through the primary heat network main circulation water pump 22 and returns to the flue gas spray heat exchanger 12, exchanges heat with the latent heat of the flue gas, recovers the waste heat of the flue gas, and after heating, enters the low-temperature exhaust steam heat exchanger 9, the medium-temperature exhaust steam heat exchanger 6, and the high-temperature exhaust steam heat exchanger 3 in sequence to complete the heat cycle in the power plant. After the secondary heat network water is heated up by the water source heat pump 17, the medium evaporation temperature electric heat pump 16, and the high evaporation temperature electric heat pump 15, it is mixed with the hot water flowing out of the plate heat exchanger 14 and supplied to the heat user 18 or the cold and hot user 19. The low-temperature water from the heat user 18 or the cold and hot user 19 returns to the plate heat exchanger 14 through the secondary heat network main circulation water pump 23 to complete the heat cycle of the terminal energy station. In summer, the three-stage electric heat pump in the terminal energy station absorbs heat from the indoor air through reverse circulation to achieve cooling.

[0031] In this embodiment, the waste heat of flue gas in the heating season in the power plant bears the basic load. According to the heat load demand, the back pressure of the high-temperature exhaust steam heat exchanger is gradually increased during the severe cold period, and the exhaust steam back pressure of each level is reduced in the early and late cold periods. When there is excess load, the high-temperature and medium-temperature exhaust steam heat exchangers are sequentially exited; when a biomass steam boiler is set for peak regulation, the waste heat of flue gas and exhaust steam bear the basic load, and the exhaust steam back pressure of each level is reduced in the early and late cold periods. When there is excess load, the high-temperature and medium-temperature exhaust steam heat exchangers are sequentially exited to reduce the impact of high exhaust steam temperature on the power generation of the power plant.

[0032] At the energy station, the water source heat pump 17 and the medium evaporating temperature heat pump 16 are started in sequence in the early and late cold periods, and the high evaporating temperature heat pump 15 is started in the severe cold period to reduce the return water temperature of the heating network and improve the heating capacity; as the outdoor temperature rises, the water source electric heat pump, the medium temperature electric heat pump and the high temperature electric heat pump are shut down in sequence to reduce the power consumption of the heat pump.

[0033] like Figure 3As shown in the figure, monitoring points are set up in the power plant: flue gas inlet and outlet temperatures ty1-4, flue gas humidity meter d1-2, flue gas component analyzer a, flue gas dioxin analyzer b, flue gas spray heat exchanger condensate water meter Q1, heat network outlet heat meter Q2, energy station inlet heat meter Q3, secondary heat network step-by-step heat network supply and return water temperature T1-8, primary heat network step-by-step supply and return water temperature T9-16, flue gas partition wall heat exchanger inlet and outlet water temperature meter T17-18, high temperature exhaust steam heat exchanger inlet and outlet water temperature meter T19-20, T27-28, medium temperature exhaust steam heat exchanger inlet and outlet water temperature meter T21-22, T29-30, low temperature exhaust steam heat exchanger inlet and outlet water temperature meter T23-T24, T31-32, flue gas The inlet and outlet water temperature meters T25-26 of the air spray heat exchanger, the temperature and pressure meters p1-2 of the supply and return water pipes are set in the valve wells along the heat network, the supply and return water pressure meters p3-4 of the first-level heat network, the supply and return water pressure meters p5-6 of the second-level heat network, the water flow meter F of the second-level heat network, the flue gas spray tower meter M1, the flue gas fan meter M2, the first-level heat network main circulation water pump meter M3, the second-level heat network main circulation water pump meter M4, the high evaporation temperature electric heat pump heat meter M5, the medium evaporation temperature electric heat pump heat meter M6, the water source heat pump heat meter M7, according to the outdoor temperature tw, the first-level heat network heat load quality adjustment curve to obtain the required first-level heat network supply and return water temperature, the heat network flow and the temperature T at each level to obtain the heat exchange at each level, and optimize the control operation method. The heat user's second-level heat network heat load quality adjustment curve obtains the required second-level heat network supply and return water temperature, and optimizes the control operation method. Based on the temperature pressure, heat and power consumption of the primary and secondary heating networks, the heat loss and energy efficiency of transmission and distribution are obtained. Based on the measurement of the heat pump meter, the hourly operating energy efficiency of the heat pump is obtained.

[0034] like Figure 2 As shown, the second embodiment provides a waste heat cascade recovery system for a waste incineration power plant, including a waste heat recovery system in the power plant, a large temperature difference heat distribution network and a low-temperature heat exchange system in an energy station. The waste heat recovery system in the power plant and the low-temperature heat exchange system in the energy station are connected through the hot network water of the large temperature difference heat distribution network to form a heat supply cycle.

[0035] The waste heat recovery system in the power plant uses flue gas inter-wall heat exchangers and flue gas spray heat exchangers to recover flue gas waste heat, and uses exhaust steam heat exchangers to heat the primary return water of the heat network in stages. A biomass steam boiler 24 is added to the waste heat recovery system in the power plant to heat the 80-90°C heat network water to 110-130°C for peak load regulation, thereby improving the heating capacity. The electric heat pump 17 and the absorption heat pump 25 are used at the end of the low-temperature heat exchange system of the energy station to reduce the return water temperature, further improving the system COP.

[0036] The main inventive points of the waste heat cascade recovery system for a waste incineration power plant provided in the present invention include:

[0037] First, in view of the high exhaust temperature of existing garbage power plants, which brings about low efficiency and energy waste, it is proposed to use flue gas spray heat exchangers (electric heat pump water does not directly contact the flue gas, and the flue gas spray heat exchanger is an integration of flue gas direct contact spray tower + partition heat exchanger (placed at the bottom of the tower)) and flue gas partition heat exchangers to transfer the waste heat of flue gas to the hot water of the primary network of centralized heating, fully recover the sensible heat and latent heat in the flue gas, reduce the exhaust temperature to below 25°C, and reduce the moisture content to below 20g / kg;

[0038] Secondly, in response to the waste heat from exhaust gas, that is, the heat dissipation problem of conventional low-temperature cooling circulating water, a cascade recovery of waste heat from exhaust gas is proposed. Multi-stage exhaust gas heat exchangers are used to further introduce heat into the water in the heating network, thereby increasing the water temperature of the heating network in stages.

[0039] Third, in response to the problems of high return water temperature, small temperature difference, low transportation capacity and short transportation radius of the primary network of the heating system, and the inability to recover waste heat due to the lack of a low-temperature cold source, resulting in low overall energy utilization efficiency of the system, it is proposed to use heat pumps to fully recover the heat of the heating network water, reduce the return water temperature, and distribute the heating pipeline network with a large temperature difference (supply and return water temperature 90 / 15℃), improve the waste heat recovery rate and the heating network distribution efficiency, and solve the problem of the long distance between the garbage power plant and the urban heat load transportation.

[0040] Fourth, different forms of heat pumps are selected according to the heating parameters, operating conditions, application scenarios, and seasons. If only winter heating is considered, the heat source is supplied with high-temperature hot water by the peak-shaving heat source, and the energy station can use electric heat pumps and absorption heat pumps for cascade cooling, using the driving force of high-temperature hot water to reduce the return water temperature, reduce power consumption, and further increase the system COP. If both winter heating and summer cooling are considered, a multi-stage electric heat pump can be used. In winter, the heat pump recovers the exhaust gas and flue gas waste heat of the thermal power plant for heating, and in summer, it absorbs heat from the indoor air for cooling.

[0041] Fifth, considering the winter heating and straw disposal issues in areas rich in biomass resources, as well as the volatility of garbage volume and calorific value, additional biomass steam boilers can be added to the garbage power plant to heat the 80-90°C hot network water to 110-130°C for peak regulation, and multiple heat sources to ensure and improve the heating capacity of the power plant. Biomass can achieve multiple fuels for power plants, maintain the flexibility of garbage and biomass fuel supply, ensure power generation, and strengthen the safety and security of heating. Biomass energy heating collects raw materials on-site, processes and transforms on-site, and consumes nearby, building a distributed clean heating system in towns and cities, directly replacing fossil energy use on the user side, which not only reduces the open-air burning of straw in rural areas, but also provides clean heat, which can drive the transformation and upgrading of biomass energy.

[0042] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0043] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only 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.

[0044] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention. It should be noted that similar numbers and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

Claims

1. A waste heat cascade recovery system for a waste incineration power plant, characterized in that: It includes a waste heat recovery system in a power plant, a large temperature difference heat transmission and distribution pipeline network and a low-temperature heat exchange system in an energy station. The waste heat recovery system in the power plant and the low-temperature heat exchange system in the energy station are connected through the hot network water of the large temperature difference heat transmission and distribution pipeline network to form a heat supply cycle; The waste heat recovery system in the power plant includes a first garbage boiler, a second garbage boiler, a third garbage boiler, a first steam turbine, a second steam turbine, a third steam turbine, a high-temperature exhaust steam heat exchanger, a medium-temperature exhaust steam heat exchanger, a low-temperature exhaust steam heat exchanger, a flue gas processor, a flue gas partition heat exchanger, a flue gas spray heat exchanger and a chimney; the high-temperature steam outlet of the first garbage boiler is connected to the steam inlet of the first steam turbine, the exhaust steam outlet of the first steam turbine is connected to the high-temperature side exhaust steam inlet of the high-temperature exhaust steam heat exchanger, and the high-temperature side water outlet of the high-temperature exhaust steam heat exchanger is connected to the upper water inlet of the first garbage boiler; the high-temperature steam outlet of the second garbage boiler is connected to the steam inlet of the second steam turbine, and the exhaust steam outlet of the second steam turbine is connected to the exhaust steam outlet of the second steam turbine. The high-temperature side exhaust steam inlet of the medium-temperature exhaust steam heat exchanger is connected, and the high-temperature side water outlet of the medium-temperature exhaust steam heat exchanger is connected to the upper water inlet of the second garbage boiler; the high-temperature steam outlet of the third garbage boiler is connected to the steam inlet of the third steam turbine, the exhaust steam outlet of the third steam turbine is connected to the high-temperature side exhaust steam inlet of the low-temperature exhaust steam heat exchanger, and the high-temperature side water outlet of the low-temperature exhaust steam heat exchanger is connected to the upper water inlet of the third garbage boiler; the flue gas generated by the first garbage boiler, the second garbage boiler, and the third garbage boiler enters the flue gas partition wall heat exchanger, the flue gas partition wall heat exchanger is connected to the flue gas processor, the flue gas processor is connected to the flue gas spray heat exchanger, and the flue gas spray heat exchanger is connected to the chimney.

2. The waste heat cascade recovery system of a waste incineration power plant according to claim 1 is characterized in that: The low-temperature heat exchange system of the energy station includes a plate heat exchanger, a high evaporation temperature electric heat pump, a medium evaporation temperature electric heat pump, a water source heat pump, primary heat network water, and a primary heat network main circulation water pump; The primary heat network water passes through the primary heat network main circulation water pump, flue gas spray heat exchanger, low-temperature exhaust steam heat exchanger, medium-temperature exhaust steam heat exchanger, high-temperature exhaust steam heat exchanger, flue gas partition heat exchanger, plate heat exchanger, high evaporation temperature electric heat pump, medium evaporation temperature electric heat pump, and water source heat pump in turn to form the system's thermal cycle.

3. The waste heat cascade recovery system of a waste incineration power plant according to claim 2 is characterized in that: The energy station low temperature heat exchange system also includes heat users, cold and hot users, secondary heat network water and secondary heat network main circulation water pump; The first branch of the secondary heat network water passes through the secondary heat network main circulation water pump, the plate heat exchanger, the heat user or the cold and hot user in sequence to form the first heat cycle of the terminal energy station; The second branch of the secondary heat network water passes through the secondary heat network main circulation water pump, water source heat pump, medium evaporation temperature electric heat pump, high evaporation temperature electric heat pump in sequence, and then mixes with the hot water flowing out of the plate heat exchanger to form the second heat cycle of the terminal energy station.

4. The waste heat cascade recovery system of a waste incineration power plant according to claim 1 is characterized in that: The low-temperature heat exchange system of the energy station includes a plate heat exchanger, an absorption heat pump, a water source heat pump, primary heat network water, and a primary heat network main circulation water pump; A biomass boiler is also provided between the flue gas inter-wall heat exchanger and the plate heat exchanger; The primary heat network water passes through the primary heat network main circulation water pump, flue gas spray heat exchanger, low-temperature exhaust steam heat exchanger, medium-temperature exhaust steam heat exchanger, high-temperature exhaust steam heat exchanger, flue gas partition heat exchanger, biomass boiler, plate heat exchanger, absorption heat pump, and water source heat pump in turn to form the system's thermal cycle.

5. The waste heat cascade recovery system of a waste incineration power plant according to claim 4 is characterized in that: The energy station low temperature heat exchange system also includes heat users, secondary heat network water and secondary heat network main circulation water pump; The first branch of the secondary heat network water passes through the secondary heat network main circulation water pump, the plate heat exchanger, and the heat user in sequence to form the third heat cycle of the terminal energy station; The second branch of the secondary heat network water passes through the secondary heat network main circulation water pump, the water source heat pump, and the absorption heat pump in sequence, and is mixed with the hot water flowing out of the plate heat exchanger to form the fourth heat cycle of the terminal energy station.

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