A two-stage steam extraction type medium-temperature medium-pressure garbage incineration power generation system and its use method

Abstract

A two-stage heat recovery medium-temperature, medium-pressure waste-to-energy system includes a waste incinerator, a waste incineration waste heat furnace, and a steam turbine generator. The steam inlet of the steam turbine generator is connected to the water outlet of the waste incineration waste heat furnace via a main steam pipeline, and the steam exhaust of the steam turbine generator is connected to the water inlet of the waste incineration waste heat furnace via a steam-water circulation pipeline. The main steam pipeline is connected to an auxiliary steam cooling and pressure reduction pipe, which is connected to a deaerator via a first pipeline and a third pipeline in sequence. The auxiliary steam cooling and pressure reduction pipe is equipped with an auxiliary steam cooling and pressure reduction valve, and the third pipeline is equipped with a deaerator inlet steam regulating valve. This system uses fewer heat recovery steam extraction stages and enables continuous operation of the deaerator and low-pressure steam air preheater, effectively improving the waste heat utilization efficiency of waste-to-energy power generation.

Description

Technical Field

[0001] This patent relates to a steam turbine heat recovery system for waste incineration power generation. It can be widely applied to the optimized design of steam turbine heat recovery systems for newly built waste incineration power generation projects. The invention is also applicable to heat recovery systems with smaller unit capacities and simple systems, such as biomass power generation and blast furnace gas waste heat power generation. The two-stage heat recovery medium-temperature, medium-pressure waste power generation system proposed in this invention has a small number of heat extraction stages and a simple system. It can meet the heating steam requirements of the low-pressure steam air preheater and ensure safe and reliable operation of the deaerator under full-load conditions. This effectively improves the waste heat utilization efficiency of waste power generation and enhances the thermal economic benefits of the unit, promising broad prospects for promotion and application. Background Art

[0002] Conventional medium-temperature and medium-pressure waste incineration power generation system steam air preheater is generally divided into high-pressure steam air preheater and low-pressure steam air preheater. The heating steam of high-pressure air preheater is saturated steam of boiler drum, and the heating steam of low-pressure air preheater is the first stage extraction steam of turbine. For medium-temperature and medium-pressure waste power generation system, the saturated steam temperature of boiler drum is generally around 255℃, so the temperature of heated primary and secondary air generally does not exceed 240℃. In order to reasonably distribute the temperature rise of primary and secondary air, the low-pressure air preheater generally heats the air temperature from 20℃ to about 155℃. At present, the heating steam pressure of low-pressure air preheater in waste power generation project is greater than 1.5MPa, and the steam temperature is as high as 300℃. Obviously, the pressure energy and temperature energy of heating steam have not been reasonably utilized in a cascade manner, which greatly reduces the waste heat utilization efficiency of waste incineration power generation project and causes unreasonable waste of energy.

[0003] To address this problem, the typical waste incineration power generation system is optimized. The present invention proposes a two-stage heat recovery medium-temperature medium-pressure waste power generation system with a small number of heat recovery steam extraction stages and a simple system. It can not only meet the steam heating needs of the low-pressure steam air preheater, but also meet the safe and reliable operation of the deaerator under full load conditions, effectively improving the waste heat utilization efficiency of waste power generation and the thermal economic benefits of the unit, and has broad prospects for promotion and application. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to achieve the matching of the steam heated by the steam air preheater of the waste incineration power generation with the temperature of the primary and secondary air, realize the cascade utilization of energy, and improve the thermal economy of the operation of the waste power generation unit. A two-stage heat recovery medium-temperature medium-pressure waste power generation system is proposed. The number of steam turbine extraction stages is reduced by one stage, and the low-pressure steam air preheater extraction steam is combined with the deaerator heating extraction steam. The thermal system is simple and can meet the heating steam demand of the low-pressure steam air preheater and the safe and reliable operation of the deaerator under full load conditions. It effectively improves the waste heat utilization efficiency of waste power generation and the thermal economic benefits of the unit, and has a broad prospect for promotion and application. In order to solve the above problems, a two-stage heat recovery medium-temperature medium-pressure waste power generation system is provided.

[0005] The object of the present invention is achieved in the following manner:

[0006] A two-stage heat recovery medium-temperature medium-pressure waste power generation system includes a waste incinerator, a waste incineration waste heat furnace, and a steam turbine generator. The steam inlet of the steam turbine generator is connected to the water outlet of the waste incineration waste heat furnace through a main steam pipeline, and the steam exhaust port of the steam turbine generator is connected to the water inlet of the waste incineration waste heat furnace through a steam-water circulation pipeline. A condenser, a condensate pump, a steam seal heater, a low-pressure heater, a deaerator, and a boiler feed water pump are arranged in sequence on the steam-water circulation pipeline along the direction of condensed water flow. An auxiliary steam cooling and pressure reducing pipe is connected to the main steam pipeline, and the auxiliary steam cooling and pressure reducing pipe is connected to the deaerator through a first pipeline and a third pipeline in sequence. An auxiliary steam cooling and pressure reducing valve is provided on the auxiliary steam cooling and pressure reducing pipe, and a deaerator inlet steam regulating valve is provided on the third pipeline.

[0007] The steam turbine generator is connected to a first-stage steam extraction pipeline and a second-stage steam extraction pipeline. A first-stage steam extraction port is provided at the connection between the steam turbine generator and the first-stage steam extraction pipeline, and a second-stage steam extraction port is provided at the connection between the steam turbine generator and the second-stage steam extraction pipeline. A steam extraction outlet electric isolation valve is provided on the first-stage steam extraction pipeline close to the first-stage steam extraction port.

[0008] The port of the first stage steam extraction pipeline is connected to the interfaces of the first pipeline and the third pipeline, and the second stage steam extraction pipeline is connected to the low-pressure heater.

[0009] The connecting port of the auxiliary steam temperature and pressure reduction pipeline connected to the first pipeline is connected to the second pipeline, the second pipeline is connected to the low-pressure steam air preheater, and a low-pressure steam air preheater inlet electric isolation valve is provided on the second pipeline.

[0010] The main steam pipe connecting the water outlet of the waste incineration waste heat furnace and the auxiliary steam temperature and pressure reduction pipe is connected to the bypass pipe, the bypass pipe is connected to the condenser, and a bypass valve is provided on the bypass pipe.

[0011] A method for using a two-stage regenerative medium-temperature and medium-pressure waste-to-energy power generation system, including a normal operating state of a steam turbine generator and a fault-induced shutdown state of the steam turbine generator. In the normal operating state of the steam turbine generator, the electric isolation valve at the superheater outlet is opened, the auxiliary steam temperature and pressure reducing valve is opened and closed, the electric isolation valve at the turbine inlet is opened, the bypass valve is closed, the electric isolation valve at the extraction steam outlet is closed, the electric isolation valve at the low-pressure steam air preheater inlet is opened, the steam regulating valve at the deaerator inlet is opened, the steam generated by the waste incineration waste heat boiler enters the steam turbine generator via a main steam pipe, the first part of the steam discharged from the steam turbine generator is condensed into water via a condenser, and the water is supplied to the waste incineration waste heat boiler via a steam-water circulation pipe, the second part of the steam discharged from the steam turbine generator enters a section of the extraction steam pipe, and the deaerator and the low-pressure steam air preheater are in operation;

[0012] When the steam turbine generator stops running due to a fault, the superheater outlet electric isolation valve opens, the auxiliary steam cooling and pressure reducing valve opens, the turbine inlet steam electric isolation valve closes, the bypass valve opens, the extraction steam outlet electric isolation valve opens, the low-pressure steam air preheater inlet electric isolation valve opens, the deaerator inlet steam regulating valve opens, part of the steam generated by the waste incineration waste heat boiler enters the auxiliary steam cooling and pressure reducing pipeline, the deaerator and the low-pressure steam air preheater operate, and another part of the steam generated by the waste incineration waste heat boiler enters the bypass pipeline. The condenser condenses the steam into water, and the water is supplied to the waste incineration waste heat boiler through the steam-water circulation pipeline.

[0013] The steam generated by the steam turbine generator is divided into a first part of steam, a second part of steam, and a third part of steam. The first part of steam enters the condenser, the second part of steam enters a first steam extraction pipeline, and the third part of steam enters a second steam extraction pipeline.

[0014] Compared with the existing technology, the present invention sets an auxiliary steam cooling and pressure reduction pipeline, and uses the steam parameters after the main steam is cooled and reduced in pressure to be equivalent to the extraction parameters of the first stage under the lowest stable combustion load condition of the incinerator; electric isolation valves are respectively set on the turbine extraction side and the low-pressure steam air preheater inlet for effective switching between the two steam supply modes of turbine extraction and main steam cooling and pressure reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a process flow chart of the present invention.

[0016] Among them, 1 is the waste incineration waste heat furnace; 2 is the steam turbine generator; 3 is the condenser; 4 is the condensate pump; 5 is the steam seal heater; 6 is the low-pressure heater; 7 is the deaerator; 8 is the boiler feed water pump; 9 is the low-pressure steam air preheater; 10 is the high-pressure steam air preheater; 11 is the superheater outlet electric isolation valve; 12 is the auxiliary steam cooling and pressure reducing valve; 13 is the bypass valve; 14 is the sob outlet electric isolation valve; 15 is the low-pressure steam air preheater inlet electric isolation valve; 16 is the deaerator inlet steam regulating valve; 17 is the turbine inlet steam electric isolation valve; 18 is the main steam pipeline; 19 is the auxiliary steam cooling and pressure reducing pipeline; 20 is the bypass pipeline; 21 is the first stage steam extraction pipeline; 22 is the second stage steam extraction pipeline; 23 is the first pipeline; 24 is the second pipeline; 25 is the third pipeline; 26 is the first stage steam extraction port; 27 is the second stage steam extraction port. DETAILED DESCRIPTION

[0017] The two-stage heat recovery medium-temperature medium-pressure waste power generation system of the present invention is suitable for the waste heat recovery system of medium-temperature medium-pressure waste incineration power generation. The number of steam turbine extraction stages is reduced by one stage, and the low-pressure steam air preheater extraction steam and the deaerator heating extraction steam are combined. The thermal system is simple and can meet the heating steam demand of the low-pressure steam air preheater and the safe and reliable operation of the deaerator under full load conditions, effectively improving the waste heat utilization efficiency of waste power generation and improving the thermal economic benefits of the unit.

[0018] In order to ensure that the steam quality of the first stage extraction steam can meet the safe and reliable operation of the deaerator 7 and the low-pressure steam air preheater under the minimum stable combustion load of the incinerator and above, the connection position of the first stage extraction steam port on the turbine cylinder must be determined according to the following requirements: 1) Pressure determination: Under the minimum stable combustion load of the incinerator, the first stage extraction steam pressure should be greater than the deaerator working pressure and a certain margin should be reserved; 2) Temperature determination: Under the minimum stable combustion load of the incinerator, the first stage extraction steam temperature should be higher than the primary and secondary air heating air temperature, and a temperature difference margin of 20 to 50°C should be reserved.

[0019] In order to ensure the reliable operation of the deaerator and low-pressure steam air preheater under the working condition below the minimum stable combustion load of the incinerator, an auxiliary steam cooling and pressure reduction pipeline and an auxiliary steam cooling and pressure reduction isolation valve 12 are set, and the steam parameters after the main steam is cooled and reduced in pressure are the same as the extraction parameters under the working condition of the minimum stable combustion load of the incinerator; an electric extraction outlet electric isolation valve 14 and a low-pressure steam air preheater inlet electric isolation valve 15 are respectively set on the turbine extraction side and the low-pressure steam air preheater 9 inlet, which are used for effective switching between the two steam supply modes of turbine extraction and main steam cooling and pressure reduction.

[0020] The present invention is further described below with reference to the accompanying drawings, but the present invention is not limited in any way. Any changes or improvements made based on the present invention fall within the scope of protection of the present invention.

[0021] like Figure 1 As shown, the present invention discloses a two-stage heat recovery medium-temperature, medium-pressure waste-to-energy system comprising a waste incinerator, a waste incineration waste heat boiler 1, and a steam turbine generator 2, which are sequentially connected by pipelines. The pipelines include a steam circulation pipeline and a steam-water circulation pipeline. The steam circulation pipeline includes a main steam pipeline, an auxiliary steam temperature and pressure reduction pipeline, a bypass pipeline, a first pipeline, a second pipeline, a third pipeline, a first steam extraction pipeline, and a second steam extraction pipeline.

[0022] The steam inlet of the steam turbine generator 2 is connected to the superheater outlet of the waste incineration waste heat furnace 1 through a steam-water circulation pipeline. The condenser 3, condensate pump 4, steam seal heater 5, low-pressure heater 6, deaerator 7, and boiler feed water pump 10 are arranged in sequence on the steam-water circulation pipeline.

[0023] The air inlet of the steam turbine generator 2 is connected to the exhaust outlet of the waste incineration waste heat furnace 1 through the main steam pipe. The main steam pipe is provided with a superheater outlet electric isolation valve 11 and a turbine inlet steam electric isolation valve 17.

[0024] The main steam pipeline connecting the superheater outlet electric isolation valve 11 to the steam turbine generator 2 is connected to a bypass auxiliary steam desuperheating and pressure reduction pipeline. Auxiliary steam desuperheating and pressure reduction valve 12 is installed on the auxiliary steam desuperheating and pressure reduction pipeline. The auxiliary steam desuperheating and pressure reduction pipeline connects to the steam inlet of the deaerator 7 through the first pipeline and the third pipeline, respectively. A deaerator inlet steam regulating valve 16 is installed on the third pipeline. The main steam pipeline connecting the auxiliary steam desuperheating and pressure reduction pipeline to the superheater outlet electric isolation valve 11 is connected to a bypass pipeline. The bypass pipeline connects to the condenser 3 and is equipped with a bypass valve 13. A turbine inlet steam electric isolation valve 17 is installed on the main steam pipeline connecting the bypass pipeline to the steam turbine generator 2.

[0025] The interface of the auxiliary steam temperature and pressure reduction pipeline and the first steam pipeline is connected to the port of the second steam pipeline. The other port of the second pipeline is connected to the steam inlet of the low-pressure steam air preheater 9. The low-pressure steam air preheater inlet electric isolation valve 15 is set on the second pipeline.

[0026] The steam turbine generator 2 is provided with a first-stage steam extraction port, a second-stage steam extraction port, a first-stage steam extraction pipe, a second-stage steam extraction pipe, a first-stage steam extraction pipe port is connected to the interface of the first pipe and the third pipe, a second-stage steam extraction pipe port is connected to the steam inlet of the low-pressure heater 6, the interface between the first-stage steam extraction pipe and the steam turbine generator 2 is the first-stage steam extraction port, and the interface between the second-stage steam extraction pipe and the steam turbine generator 2 is the second-stage steam extraction port.

[0027] The steam from the high-pressure steam air preheater 10 and the low-pressure steam air preheater 9 is used to heat the cold air to continuously provide combustion conditions for the garbage combustion in the garbage incinerator. The hydrophobicity generated by the high-pressure steam air preheater 10 and the low-pressure steam air preheater 9 is discharged into the deaerator 7. When the deaerator 7 is in working condition, the oxygen and other gases in the water inside it are removed, thereby ensuring the quality of the water and continuously supplying water to the garbage incineration waste heat furnace 1.

[0028] The working process of the present invention is as follows:

[0029] Minimum stable combustion load and above

[0030] This operating condition is a long-term stable operating condition for the waste-to-energy system, and the waste-to-energy turbine operates normally. The heat generated by waste incineration is heated by the waste incineration waste heat furnace 1 to heat the feed water. The saturated steam formed in the boiler drum enters the high-pressure steam air preheater. The heat of the saturated steam is absorbed by the heat sink in the high-pressure steam air preheater, heating the air and continuously providing combustion conditions for waste incineration. The waste incineration waste heat furnace 1 generates steam through waste heat recovery. The electric isolation valve 11 at the superheater outlet is opened, the bypass valve 13 is closed, the auxiliary steam temperature and pressure reducing valve 12 is closed, and the deaerator inlet steam regulating valve 16 is in the regulated open state. Steam enters the main steam pipeline. At this time, the steam turbine steam electric isolation valve 17 automatically opens, and the steam enters the steam turbine generator 2. The steam turbine generator 2 converts the thermal energy of the steam into electrical energy, and the steam turbine generator 2 starts;

[0031] After the steam turbine generator 2 starts to operate, the steam generated by the steam turbine generator 2 is divided into the first part of steam, the second part of steam, and the third part of steam. The electric isolation valve 14 of the steam extraction outlet is opened, and the third part of steam enters the first steam extraction pipeline 21, the second part of steam enters the second steam extraction pipeline 22, and the first part of steam enters the condenser 3 through the steam-water circulation pipeline.

[0032] The deaerator inlet steam regulating valve 16 on the third pipeline 25 is in an open state, and the steam turbine generator 2 extracts steam from the first extraction port 26. After the third part of the steam is extracted through the first extraction port 25, a third part of the steam with a lowered temperature and a lowered pressure is formed. The third part of the steam with a lowered temperature and a lowered pressure enters the first pipeline 23 and the third pipeline 25 respectively. When the parameters of the third part of the steam entering the first pipeline 23 meet the parameters of the low-pressure steam air preheater 9, the low-pressure steam air preheater inlet electric isolation valve 15 is in an open state, and the low-pressure steam air preheater 9 operates; the third part of the steam entering the third pipeline is depressurized through the deaerator inlet steam regulating valve 16. When the parameters of the steam after decompression meet the parameters of the deaerator 7, the deaerator 7 operates at a constant pressure.

[0033] After the steam turbine generator 2 is in operation, the first part of the steam discharged by the steam turbine generator 2 enters the condenser 3 through the condensation pipe. The condensate pump transports the condensate in the condenser 3 to the steam seal heater 5. The steam seal heater 5 uses the waste heat to heat the steam, so that the temperature of the condensate is increased. The condensate then enters the low-pressure heater 6. The steam turbine generator 2 extracts steam from the second-stage steam extraction port 27. The temperature and pressure of the second part of the steam generated by the steam turbine generator 2 are reduced. The second part of the steam with reduced temperature and pressure enters the second-stage steam extraction pipe 22. The second part of the steam entering the second-stage steam extraction pipe is extracted to the low-pressure Inside the heater 6, the temperature of the water in the low-pressure heater 6 is increased, the amount of steam discharged from the steam turbine generator to the condenser 3 is reduced, and the water flows into the deaerator 7. Due to the normal operation of the deaerator 7, the oxygen and other gases in the water inside the deaerator 7 are removed, ensuring the quality of the water entering the boiler feed water pump 8. The boiler feed water pump 8 continues to supply water to the waste incineration waste heat furnace 1. At the same time, the low-pressure steam air preheater 9 and the high-pressure steam air preheater 10 heat the air to continuously provide combustion conditions for the waste incinerator. The entire waste incineration power generation system operates in a cycle, thereby improving the preheating utilization efficiency of the system.

[0034] Operating conditions below the minimum stable combustion load

[0035] This operating condition refers to the abnormal operating condition of the waste-to-energy system, such as unit startup and accident shutdown. The turbine accident shutdown is used as an example here.

[0036] When the steam turbine generator 2 stops working due to a fault, the superheater outlet electric isolation valve 11 is opened, the turbine inlet steam electric isolation valve 17 is closed, the extraction steam outlet electric isolation valve 14 is closed, the auxiliary steam temperature and pressure reducing valve 12 is opened, the bypass valve 13 is opened, and the deaerator inlet steam regulating valve 16 is in a regulated open state. The flue gas generated by the waste incineration enters the waste incineration waste heat furnace 1 through the pipeline, and the flue gas enters the high-pressure steam air preheater 10. The heat of the flue gas is absorbed by the heat sink in the high-pressure steam air preheater. The high-pressure steam air preheater operates to transfer the heat to the cold air entering the combustion boiler, providing conditions for waste incineration.

[0037] The waste heat incinerator 1 converts water into steam using heat. The steam enters the main steam pipeline through the electric isolation valve at the superheater inlet. Since the electric isolation valve at the turbine inlet is closed, part of the main steam in the main steam pipeline enters the auxiliary steam cooling and pressure reduction pipeline, and the other part of the main steam enters the condenser 3 through the bypass pipeline.

[0038] The steam entering the bypass pipe enters the condenser 3 through the bypass valve 13, where it is condensed into water. The condensate pump 4 transports the condensate in the condenser 3 to the steam seal heater 5. The steam seal heater 5 uses waste heat to heat the steam, raising the temperature of the condensate. The condensate then enters the low-pressure heater 6, which transports the condensate to the deaerator 7. At this time, the low-pressure heater 6 only serves to transport the condensate.

[0039] After the main steam entering the auxiliary steam temperature reduction and pressure reduction pipeline passes through the auxiliary steam temperature reduction and pressure reduction valve, part of the steam after temperature reduction and pressure reduction enters the second pipeline, and the other part after temperature reduction and pressure reduction enters the first pipeline and the third pipeline in sequence. When the parameters of the steam after temperature reduction and pressure reduction entering the second pipeline meet the parameters of the low-pressure steam air preheater 9, the low-pressure steam air preheater inlet electric isolation valve 15 is opened, and the low-pressure steam air preheater 9 is operated to heat the air, and the high-pressure steam air preheater continues to heat the air, continuously providing sufficient conditions for waste incineration; the drain generated during the operation of the low-pressure steam air preheater 9 and the high-pressure steam air preheater 10 is discharged into the deaerator 7; the steam after temperature reduction and pressure reduction entering the third pipeline is regulated by the deaerator inlet steam regulating valve 16, so that the steam parameters are adjusted to meet the parameters of the deaerator 7, and the deaerator 7 operates at a constant pressure;

[0040] The deaerator 7 removes oxygen and other gases from the water inside the deaerator 7, continuously supplies water to the waste incineration waste heat furnace 1, and the waste incineration power generation system continues to operate. The deaerator 7 and the low-pressure steam air preheater 9 and the high-pressure steam air preheater 10 continue to operate, so that the waste heat generated by the waste incineration power generation is fully utilized, thereby improving the waste heat utilization efficiency of the system.

[0041] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, and these should also be regarded as the scope of protection of the present invention.

Claims

1. A two-stage heat recovery type medium-temperature medium-pressure waste power generation system, comprising a waste incinerator, a waste incineration waste heat furnace (1), and a steam turbine generator (2), wherein the steam inlet of the steam turbine generator (2) is connected to the water outlet of the waste incineration waste heat furnace (1) through a main steam pipe (18), and the steam exhaust port of the steam turbine generator (2) is connected to the water inlet of the waste incineration waste heat furnace (1) through a steam-water circulation pipe, and a condenser (3), a condensate pump (4), a steam seal heater (5), a low-pressure heater (6), a deaerator (7), and a boiler feed water pump (8) are arranged in sequence on the steam-water circulation pipe along the direction of condensed water flow, characterized in that: The main steam pipe (18) is connected to an auxiliary steam cooling and pressure reducing pipe (19), which is connected to the deaerator (7) through the first pipe (23) and the third pipe (25) in sequence. The auxiliary steam cooling and pressure reducing pipe (19) is provided with an auxiliary steam cooling and pressure reducing valve (12), and the third pipe (25) is provided with a deaerator inlet steam regulating valve (16); The steam turbine generator (2) is connected to a first-stage steam extraction pipeline (21) and a second-stage steam extraction pipeline (22); a first-stage steam extraction port (26) is provided at the connection between the steam turbine generator (2) and the first-stage steam extraction pipeline (21); a second-stage steam extraction port (27) is provided at the connection between the steam turbine generator (2) and the second-stage steam extraction pipeline; and a steam extraction outlet electric isolation valve (14) is provided on the first-stage steam extraction pipeline near the first-stage steam extraction port; The connection position of the first stage extraction port (26) on the turbine cylinder: 1) pressure determination: under the lowest stable combustion load condition of the incinerator, the first stage extraction pressure should be greater than the deaerator working pressure and a certain margin should be reserved; 2) temperature determination: under the lowest stable combustion load condition of the incinerator, the first stage extraction temperature should be higher than the primary and secondary air heating air temperatures, and a temperature difference margin of 20 to 50°C should be reserved; The communication port of the auxiliary steam temperature reduction and pressure reduction pipe (19) and the first pipe (23) is connected to the second pipe (24), the second pipe (24) is connected to the low-pressure steam air preheater (9), and the low-pressure steam air preheater inlet electric isolation valve (15) is provided on the second pipe (24); A method for using a two-stage heat recovery medium-temperature medium-pressure garbage power generation system, comprising a normal operation state of a steam turbine generator (2) and a failure-induced stop operation state of the steam turbine generator (2); When the steam turbine generator (2) is in normal operation, the electric isolation valve (11) at the outlet of the superheater is opened, the auxiliary steam temperature reduction and pressure reducing valve (12) is closed, the electric isolation valve (17) at the inlet of the steam turbine is opened, the bypass valve (13) is closed, the electric isolation valve (14) at the outlet of the extraction steam is closed, the electric isolation valve (15) at the inlet of the low-pressure steam air preheater is opened, the steam regulating valve (16) at the inlet of the deaerator is opened, the steam generated by the waste incineration waste heat furnace (1) enters the steam turbine generator (2) through the main steam pipe, the first part of the steam discharged from the steam turbine generator (2) is condensed into water through the condenser (3), and the water is supplied to the waste incineration waste heat furnace (1) through the steam-water circulation pipe, the second part of the steam discharged from the steam turbine generator (2) enters a section of the extraction steam pipe (21), and the deaerator (7) and the low-pressure steam air preheater (9) are in operation; When the turbine generator stops operating due to a fault, the electric isolation valve (11) at the outlet of the superheater is opened, the auxiliary steam temperature reduction and pressure reduction valve (12) is opened, the electric isolation valve (17) at the inlet of the turbine is closed, the bypass valve (13) is opened, the electric isolation valve (14) at the outlet of the extraction steam is opened, the electric isolation valve (15) at the inlet of the low-pressure steam air preheater is opened, the steam regulating valve (16) at the inlet of the deaerator is opened, part of the steam generated by the waste incineration waste heat furnace (1) enters the auxiliary steam temperature reduction and pressure reduction pipe (19), the deaerator (7) and the low-pressure steam air preheater (9) operate, and another part of the steam generated by the waste incineration waste heat furnace (1) enters the bypass pipe (20), and the condenser (3) condenses the steam into water, which is supplied to the waste incineration waste heat furnace (1) through the steam-water circulation pipe.

2. The two-stage heat recovery medium-temperature medium-pressure waste-to-energy system according to claim 1, characterized in that: The port of the first stage steam extraction pipeline (21) is connected to the interfaces of the first pipeline (23) and the third pipeline (25), and the second stage steam extraction pipeline (22) is connected to the low-pressure heater (6).

3. The two-stage heat recovery medium-temperature medium-pressure waste-to-energy system according to claim 1, characterized in that: The main steam pipe (18) connecting the water outlet of the waste incineration waste heat furnace (1) and the auxiliary steam temperature reduction and pressure reduction pipe (19) is connected to the bypass pipe (20), and the bypass pipe (20) is connected to the condenser (3). A bypass valve (13) is provided on the bypass pipe (20).

4. The two-stage heat recovery medium-temperature medium-pressure waste-to-energy system according to claim 1, characterized in that: The steam generated by the steam turbine generator (2) is divided into a first portion of steam, a second portion of steam, and a third portion of steam. The first portion of steam enters the condenser (3), the second portion of steam enters the first stage steam extraction pipeline (21), and the third portion of steam enters the second stage steam extraction pipeline (22).

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