Subcritical waste energy and waste heat recovery power generation system for steel plant and its working method

Abstract

The present invention proposes a subcritical waste energy and waste heat recovery power generation system for a steel plant and a working method thereof, which are used to recover the waste heat steam with utilization value generated by the boiler of the steel plant to a supplementary condensing steam turbine unit for power generation, wherein the boiler comprises a blast furnace gas boiler that generates subcritical ultra-high temperature steam, a medium-pressure waste heat boiler that generates medium-pressure superheated steam, and a low-pressure waste heat boiler that generates low-pressure superheated steam or low-pressure saturated steam; the subcritical ultra-high temperature steam generated by the blast furnace gas boiler of the present invention is sent to the high-pressure cylinder of the steam turbine and becomes medium-pressure superheated steam after doing work; the medium-pressure superheated steam discharged from the high-pressure cylinder of the steam turbine and the medium-pressure steam generated by the medium-pressure waste heat boiler are reheated and then enter the low-pressure cylinder of the steam turbine, and the low-pressure steam is heated and then sent to the steam supplement port of the low-pressure cylinder of the steam turbine. The present invention can reduce the number of generator sets, improve the unit parameters, and improve the power generation efficiency of the waste energy and waste heat of the entire steel plant.

Description

Technical Field

[0001] The invention relates to the technical field of power generation, in particular to a subcritical waste energy and waste heat recovery power generation system for a steel plant and a working method thereof. Background Art

[0002] The existing waste energy and waste heat recovery and power generation methods of steel enterprises are relatively scattered. The high parameters are blast furnace gas power generation, the low parameters (including medium pressure and low pressure) superheated steam are sintering waste heat power generation, dry coke quenching waste heat power generation, waste heat power generation from waste gas, rotary hearth furnace waste heat power generation, pelletizing waste heat power generation, and saturated steam is converter and heating furnace saturated steam power generation. This configuration has the following problems: first, the saturated steam fluctuates greatly, and steam is sometimes released, causing energy loss; second, saturated steam power generation has low unit efficiency and prominent blade safety issues; third, the unit layout is scattered and the investment is high; all of the above are technical problems that need to be solved. Summary of the invention

[0003] The present invention proposes a subcritical waste energy and waste heat recovery power generation system for a steel plant and a working method thereof. Based on the technical principles of "overall power generation, energy level matching, high energy and high use, and temperature matching", the present invention can solve the problems of low heat-to-work conversion efficiency, high kilowatt investment, large footprint, and large number of operating personnel in the existing distributed waste energy and waste heat power generation in steel plants.

[0004] The present invention adopts the following technical solutions.

[0005] The subcritical waste energy and waste heat recovery power generation system of the steel plant is used to recover the waste heat steam with utilization value generated by the boiler of the steel plant to the supplementary condensing steam turbine unit for power generation. The boiler includes a blast furnace gas boiler that generates subcritical ultra-high temperature steam, a medium-pressure waste heat boiler that generates medium-pressure superheated steam, and a low-pressure waste heat boiler that generates low-pressure superheated steam or low-pressure saturated steam;

[0006] The steam turbine in the supplementary condensing steam turbine unit includes a supplementary condensing steam turbine including a high-pressure cylinder and a supplementary condensing low-pressure cylinder; the main steam output end of the blast furnace gas boiler is connected to the high-pressure cylinder of the supplementary condensing steam turbine;

[0007] The blast furnace gas boiler is provided with a medium-pressure reheater and a low-pressure superheater;

[0008] The input end of the medium-pressure reheater is connected to the medium-pressure superheated steam output end of the medium-pressure waste heat boiler and the exhaust end of the high-pressure cylinder of the supplementary steam condensing steam turbine to receive steam; the steam input to the medium-pressure reheater is sent to the low-pressure cylinder of the steam turbine after reheating treatment;

[0009] The input end of the low-pressure superheater is connected to the output end of the low-pressure waste heat boiler for outputting low-pressure superheated steam or the output end of low-pressure saturated steam; the steam input to the low-pressure superheater is sent to the steam inlet of the steam turbine after heat treatment;

[0010] The steam output end of the supplementary steam condensing steam turbine is connected to the steam inlet end of the condenser; the condensate pipe of the condenser is connected to the medium-pressure waste heat boiler and the blast furnace gas boiler through the feed water pipe; the feed water pipe is provided with a low-pressure heater and a high-pressure heater for heating the water flow in the pipe.

[0011] The medium-pressure waste heat boiler includes the waste heat boiler configured for the sintering equipment, rotary hearth furnace and dry quenching process of the steel plant; the low-pressure waste heat boiler includes the waste heat boiler configured for the sintering ring cooler, converter, vaporization heating furnace and pelletizing process of the steel plant.

[0012] The steam turbine unit is used to drive a generator;

[0013] When the steam turbine is a steam-injection condensing steam turbine, the power output shafts of the high-pressure cylinder and the low-pressure cylinder for driving the generator are coaxial;

[0014] When the steam turbine unit also includes a subcritical steam turbine, the high-pressure cylinder of the subcritical steam turbine and the supplementary steam condensing steam turbine have separate shafts, and the high-pressure cylinder of the subcritical steam turbine and the supplementary steam condensing steam turbine drive different generators respectively.

[0015] The water supply pipe includes a low-pressure water supply pipe and a high-pressure water supply pipe; a low-pressure water supply pipe is provided with a low-pressure water supply pump, and the low-pressure water supply pipe is connected to the water inlet end of the low-pressure waste heat boiler and the water inlet end of the medium-pressure waste heat boiler; a high-pressure water supply pipe is provided with a high-pressure water supply pump, and the high-pressure water supply pipe is connected to the water inlet end of the blast furnace gas boiler.

[0016] A condensate pump is provided at the condensate pipe of the condenser, and a low-pressure heater, a low-pressure deaerator, a high-pressure deaerator and a high-pressure heater are sequentially provided on the condensate pipe in the direction of water flow.

[0017] The condenser is a water-cooled condenser, the cooling water outlet pipe of the water-cooled condenser is connected to the water inlet end of the cooling tower, and the water outlet end of the cooling tower is connected to the cooling water inlet pipe of the water-cooled condenser via a circulating water pump.

[0018] Working method of the subcritical waste energy and waste heat recovery power generation system of a steel plant. The working method of the subcritical waste energy and waste heat recovery power generation system of the steel plant described above includes the following steps;

[0019] Step A1, set the steam parameters of the blast furnace gas boiler to a subcritical ultra-high temperature boiler, that is, the steam pressure of the blast furnace gas boiler output steam reaches 17.4MPa or above, and the steam temperature reaches 571℃ or above; set the exhaust pressure of the high-pressure cylinder of the steam turbine to be consistent with the steam pressure generated by the medium-pressure waste heat boiler of the steel plant; set the steam pressure output by the medium-pressure waste heat boiler to be close to or equal to 20% of the steam pressure output by the blast furnace gas boiler;

[0020] Step A2, the subcritical ultra-high temperature steam of the blast furnace gas boiler is sent to the high-pressure cylinder of the steam turbine, and after driving the steam turbine to work, it is converted into superheated medium-pressure steam and sent to the reheater of the blast furnace gas boiler; the superheated medium-pressure steam generated by the medium-pressure waste heat boiler is sent to the medium-pressure reheater of the blast furnace gas boiler, and the medium-pressure steam after reheating treatment in the medium-pressure reheater is transported to the low-pressure condensing steam turbine;

[0021] Step A3, if the pressure of the low-pressure steam generated by the low-pressure waste heat boiler reaches the pressure range of 0.3~1.0MPa, this part of the low-pressure steam is sent to the low-pressure superheater of the blast furnace gas boiler, and after heat treatment, it is sent to the steam supplement port of the low-pressure cylinder of the steam turbine;

[0022] Step A4, the medium-pressure steam and low-pressure steam sent to the low-pressure cylinder of the steam turbine drive the low-pressure cylinder to do work, and then are converted into exhaust steam and sent to the condenser. The exhaust steam is cooled after passing through the condenser to form condensed water, and the condensed water is sent to the thermal deaerator by the condensate pump; the exhaust steam at the condenser is cooled by circulating water cooling, and the low-temperature water required for the circulating water cooling is sent to the condenser by the circulating water pump, and after absorbing the latent heat of the exhaust steam, it becomes high-temperature water and is sent to the cooling tower for cooling;

[0023] Step A5, the hot water formed after the condensate is deoxygenated by the low-pressure thermal deaerator is output in two ways; one way is sent to the medium-pressure waste heat boiler and the low-pressure waste heat boiler by the low-pressure feed water pump; the other way is sent to the high-pressure deaerator for treatment by the relay water pump, and then sent to the blast furnace gas boiler by the high-pressure feed water pump.

[0024] The feed water pipe and the condensate water pipe are provided with a turbine heat recovery system; the turbine heat recovery system can evaluate the utilization of the turbine heat recovery and use the high-pressure heater and the low-pressure heater to increase the return water temperature of the feed water pipe.

[0025] Compared with the prior art, the present invention has the following beneficial effects: according to the working principle of the subcritical waste energy and waste heat recovery power generation system of the steel plant of the present invention, the subcritical ultra-high temperature steam generated by the blast furnace gas boiler is sent to the high-pressure cylinder of the steam turbine, and becomes medium-pressure superheated steam after doing work; the medium-pressure superheated steam discharged from the high-pressure cylinder of the steam turbine and the medium-pressure steam generated by the medium-pressure waste heat boiler enter the low-pressure cylinder of the steam turbine after reheating, and the low-pressure steam is sent to the steam supplement port of the low-pressure cylinder of the steam turbine after being heated. Compared with the existing waste energy and waste heat power generation system, the number of generator sets is reduced, the unit parameters are improved, and the power generation efficiency of the waste energy and waste heat of the entire steel plant is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0027] Attached Figure 1 is a schematic diagram of the present invention;

[0028] In the figure: 1-blast furnace gas boiler; 2-medium pressure waste heat boiler; 3-low pressure waste heat boiler; 4-medium pressure reheater; 5-low pressure superheater; 6-high pressure cylinder of steam turbine; 7-low pressure cylinder of steam turbine; 8-generator; 9-condenser; 10-condensate pump; 11-cooling tower; 12-circulating water pump; 13-low pressure heater; 14-low pressure deaerator; 15-low pressure feed water pump; 16-relay water pump; 17-high pressure deaerator; 18-high pressure feed water pump; 19-high pressure heater. DETAILED DESCRIPTION

[0029] like Figure 1 As shown, the subcritical waste energy and waste heat recovery power generation system of the steel plant is used to recover the waste heat steam with utilization value generated by the boiler of the steel plant to the supplementary condensing steam turbine unit for power generation, and the boiler includes a blast furnace gas boiler 1 for generating subcritical ultra-high temperature steam, a medium-pressure waste heat boiler 2 for generating medium-pressure superheated steam, and a low-pressure waste heat boiler 3 for generating low-pressure superheated steam or low-pressure saturated steam;

[0030] The steam turbine in the supplementary condensing steam turbine unit includes a supplementary condensing steam turbine including a high-pressure cylinder and a supplementary condensing low-pressure cylinder; the main steam output end of the blast furnace gas boiler is connected to the high-pressure cylinder 6 of the supplementary condensing steam turbine;

[0031] The blast furnace gas boiler is provided with a medium-pressure reheater 4 and a low-pressure superheater 5;

[0032] The input end of the medium-pressure reheater is connected to the medium-pressure superheated steam output end of the medium-pressure waste heat boiler and the exhaust end of the high-pressure cylinder of the supplementary steam condensing steam turbine to receive steam; the steam input to the medium-pressure reheater is sent to the low-pressure cylinder 7 of the steam turbine after reheating treatment;

[0033] The input end of the low-pressure superheater is connected to the output end of the low-pressure waste heat boiler for outputting low-pressure superheated steam or the output end of low-pressure saturated steam; the steam input to the low-pressure superheater is sent to the steam inlet of the steam turbine after heat treatment;

[0034] The steam output end of the supplementary steam condensing steam turbine is connected to the steam inlet end of the condenser 9; the condensate pipe of the condenser is connected to the medium-pressure waste heat boiler and the blast furnace gas boiler through the feed water pipe; the feed water pipe is provided with a low-pressure heater and a high-pressure heater for heating the water flow in the pipe.

[0035] The medium-pressure waste heat boiler includes the waste heat boiler configured for the sintering equipment, rotary hearth furnace and dry quenching process of the steel plant; the low-pressure waste heat boiler includes the waste heat boiler configured for the sintering ring cooler, converter, vaporization heating furnace and pelletizing process of the steel plant.

[0036] The steam turbine unit is used to drive the generator 8;

[0037] When the steam turbine is a steam-injection condensing steam turbine, the power output shafts of the high-pressure cylinder and the low-pressure cylinder for driving the generator are coaxial;

[0038] When the steam turbine unit also includes a subcritical steam turbine, the high-pressure cylinder of the subcritical steam turbine and the supplementary steam condensing steam turbine have separate shafts, and the high-pressure cylinder of the subcritical steam turbine and the supplementary steam condensing steam turbine drive different generators respectively.

[0039] The water supply pipe includes a low-pressure water supply pipe and a high-pressure water supply pipe; a low-pressure water supply pipe is provided with a low-pressure water supply pump 15, and the low-pressure water supply pipe is connected to the water inlet end of the low-pressure waste heat boiler and the water inlet end of the medium-pressure waste heat boiler; a high-pressure water supply pipe is provided with a high-pressure water supply pump 18, and the high-pressure water supply pipe is connected to the water inlet end of the blast furnace gas boiler.

[0040] A condensate pump is provided at the condensate pipe of the condenser, and a low-pressure heater 13, a low-pressure deaerator 14, a high-pressure deaerator 17 and a high-pressure heater 19 are sequentially provided on the condensate pipe in the direction of water flow.

[0041] The condenser is a water-cooled condenser, the cooling water outlet pipe of the water-cooled condenser is connected to the water inlet end of the cooling tower 11, and the water outlet end of the cooling tower is connected to the cooling water inlet pipe of the water-cooled condenser via a circulating water pump 12.

[0042] Working method of the subcritical waste energy and waste heat recovery power generation system of a steel plant. The working method of the subcritical waste energy and waste heat recovery power generation system of the steel plant described above includes the following steps;

[0043] Step A1, set the steam parameters of the blast furnace gas boiler to a subcritical ultra-high temperature boiler, that is, the steam pressure of the blast furnace gas boiler output steam reaches 17.4MPa or above, and the steam temperature reaches 571℃ or above; set the exhaust pressure of the high-pressure cylinder of the steam turbine to be consistent with the steam pressure generated by the medium-pressure waste heat boiler of the steel plant; set the steam pressure output by the medium-pressure waste heat boiler to be close to or equal to 20% of the steam pressure output by the blast furnace gas boiler;

[0044] Step A2, the subcritical ultra-high temperature steam of the blast furnace gas boiler is sent to the high-pressure cylinder of the steam turbine, and after driving the steam turbine to work, it is converted into superheated medium-pressure steam and sent to the reheater of the blast furnace gas boiler; the superheated medium-pressure steam generated by the medium-pressure waste heat boiler is sent to the medium-pressure reheater of the blast furnace gas boiler, and the medium-pressure steam after reheating treatment in the medium-pressure reheater is transported to the low-pressure condensing steam turbine;

[0045] Step A3, if the pressure of the low-pressure steam generated by the low-pressure waste heat boiler reaches the pressure range of 0.3~1.0MPa, this part of the low-pressure steam is sent to the low-pressure superheater of the blast furnace gas boiler, and after heat treatment, it is sent to the steam supplement port of the low-pressure cylinder of the steam turbine;

[0046] Step A4, the medium-pressure steam and low-pressure steam sent to the low-pressure cylinder of the steam turbine drive the low-pressure cylinder to do work, and then are converted into exhaust steam and sent to the condenser. The exhaust steam is cooled after passing through the condenser to form condensed water, and the condensed water is sent to the thermal deaerator by the condensate pump; the exhaust steam at the condenser is cooled by circulating water cooling, and the low-temperature water required for the circulating water cooling is sent to the condenser by the circulating water pump, and after absorbing the latent heat of the exhaust steam, it becomes high-temperature water and is sent to the cooling tower for cooling;

[0047] Step A5, the hot water formed after the condensate is deoxygenated by the low-pressure thermal deaerator is output in two ways; one way is sent to the medium-pressure waste heat boiler and the low-pressure waste heat boiler by the low-pressure feed water pump; the other way is sent to the high-pressure deaerator for treatment by the relay water pump, and then sent to the blast furnace gas boiler by the high-pressure feed water pump.

[0048] The feed water pipe and the condensate water pipe are provided with a turbine heat recovery system; the turbine heat recovery system can evaluate the utilization of the turbine heat recovery and use the high-pressure heater and the low-pressure heater to increase the return water temperature of the feed water pipe.

[0049] In this example, the low-pressure heater 13 and the high-pressure heater 18 can be configured in one or more stages to meet the needs of heating the feed water.

[0050] The steam pressure in this example is generally set to three types: one is the main steam generated by blast furnace gas, with parameters of subcritical ultra-high temperature (and above); the second is medium-pressure steam, which is mainly the exhaust steam of the high-pressure cylinder of the steam turbine and the medium-pressure steam generated by the medium-pressure boiler, and the parameter is the medium-pressure steam generated by the waste heat boiler with the main steam pressure, and the pressure is about 20% of the main steam pressure; the third is low-pressure steam, which is mainly low-pressure steam generated by the low-pressure waste heat boiler, with a pressure of 0.3-1.0MPa. After the subcritical ultra-high temperature steam enters the high-pressure cylinder of the steam turbine, the exhaust steam and the medium-pressure steam generated by the medium-pressure boiler are reheated in the blast furnace gas boiler and sent to the low-pressure cylinder of the steam turbine to continue to work. After being superheated, the low-pressure steam is sent to the low-pressure cylinder of the steam turbine in the form of supplementary steam.

[0051] Therefore, heat engine combinations such as waste heat boilers with different pressure levels, reheaters and superheaters with different pressure levels, and steam turbines with different pressures fed with main steam or supplementary steam, derived from the above-mentioned invention, all fall within the scope of protection of the present invention.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of "overall power generation, energy level matching, high energy and high use, and temperature matching" of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. The subcritical waste energy and waste heat recovery power generation system of the steel plant is used to recover the valuable waste heat steam generated by the boiler of the steel plant to the supplementary condensing steam turbine unit for power generation, and its characteristics are: The boilers include blast furnace gas boilers that produce subcritical ultra-high temperature steam, medium-pressure waste heat boilers that produce medium-pressure superheated steam, and low-pressure waste heat boilers that produce low-pressure superheated steam or low-pressure saturated steam; The steam turbine in the supplementary condensing steam turbine unit includes a supplementary condensing steam turbine including a high-pressure cylinder and a supplementary condensing low-pressure cylinder; the main steam output end of the blast furnace gas boiler is connected to the high-pressure cylinder of the supplementary condensing steam turbine; The blast furnace gas boiler is provided with a medium-pressure reheater and a low-pressure superheater; The input end of the medium-pressure reheater is connected to the medium-pressure superheated steam output end of the medium-pressure waste heat boiler and the exhaust end of the high-pressure cylinder of the supplementary steam condensing steam turbine to receive steam; the steam input to the medium-pressure reheater is sent to the low-pressure cylinder of the steam turbine after reheating treatment; The input end of the low-pressure superheater is connected to the output end of the low-pressure waste heat boiler for outputting low-pressure superheated steam or the output end of low-pressure saturated steam; the steam input to the low-pressure superheater is sent to the steam inlet of the steam turbine after heat treatment; The steam output end of the supplementary steam condensing steam turbine is connected to the steam inlet end of the condenser; the condensate pipe of the condenser is connected to the medium-pressure waste heat boiler and the blast furnace gas boiler through the feed water pipe; the feed water pipe is provided with a low-pressure heater and a high-pressure heater for heating the water flow in the pipe; The medium-pressure waste heat boiler includes the waste heat boiler configured for the sintering equipment, rotary hearth furnace and dry coke quenching process of the steel plant; the low-pressure waste heat boiler includes the waste heat boiler configured for the sintering ring cooler, converter, vaporization heating furnace and pelletizing process of the steel plant; The steam turbine unit is used to drive a generator; When the steam turbine is a steam-injection condensing steam turbine, the power output shafts of the high-pressure cylinder and the low-pressure cylinder for driving the generator are coaxial; When the steam turbine unit also includes a subcritical steam turbine, the high-pressure cylinder of the subcritical steam turbine and the supplementary steam condensing steam turbine have separate shafts, and the high-pressure cylinder of the subcritical steam turbine and the supplementary steam condensing steam turbine drive different generators respectively.

2. The subcritical waste energy and waste heat recovery power generation system of a steel plant according to claim 1 is characterized in that: The water supply pipe includes a low-pressure water supply pipe and a high-pressure water supply pipe; a low-pressure water supply pipe is provided with a low-pressure water supply pump, and the low-pressure water supply pipe is connected to the water inlet end of the low-pressure waste heat boiler and the water inlet end of the medium-pressure waste heat boiler; a high-pressure water supply pipe is provided with a high-pressure water supply pump, and the high-pressure water supply pipe is connected to the water inlet end of the blast furnace gas boiler.

3. The subcritical waste energy and waste heat recovery power generation system of a steel plant according to claim 1 is characterized in that: A condensate pump is provided at the condensate pipe of the condenser, and a low-pressure heater, a low-pressure deaerator, a high-pressure deaerator and a high-pressure heater are sequentially provided on the condensate pipe in the direction of water flow.

4. The subcritical waste energy and waste heat recovery power generation system of a steel plant according to claim 3 is characterized in that: The condenser is a water-cooled condenser, the cooling water outlet pipe of the water-cooled condenser is connected to the water inlet end of the cooling tower, and the water outlet end of the cooling tower is connected to the cooling water inlet pipe of the water-cooled condenser via a circulating water pump.

5. The working method of the subcritical waste energy and waste heat recovery power generation system of a steel plant is characterized by: The subcritical waste energy and waste heat recovery power generation system for a steel plant according to claim 3, the working method thereof comprises the following steps; Step A1, set the steam parameters of the blast furnace gas boiler to a subcritical ultra-high temperature boiler, that is, the steam pressure of the blast furnace gas boiler output steam reaches 17.4MPa or above, and the steam temperature reaches 571℃ or above; set the exhaust pressure of the high-pressure cylinder of the steam turbine to be consistent with the steam pressure generated by the medium-pressure waste heat boiler of the steel plant; set the steam pressure output by the medium-pressure waste heat boiler to be close to or equal to 20% of the steam pressure output by the blast furnace gas boiler; Step A2, the subcritical ultra-high temperature steam of the blast furnace gas boiler is sent to the high-pressure cylinder of the steam turbine, and after driving the steam turbine to work, it is converted into superheated medium-pressure steam and sent to the reheater of the blast furnace gas boiler; the superheated medium-pressure steam generated by the medium-pressure waste heat boiler is sent to the medium-pressure reheater of the blast furnace gas boiler, and the medium-pressure steam after reheating treatment in the medium-pressure reheater is transported to the low-pressure condensing steam turbine; Step A3, if the pressure of the low-pressure steam generated by the low-pressure waste heat boiler reaches the pressure range of 0.3~1.0MPa, this part of the low-pressure steam is sent to the low-pressure superheater of the blast furnace gas boiler, and after heat treatment, it is sent to the steam supplement port of the low-pressure cylinder of the steam turbine; Step A4, the medium-pressure steam and low-pressure steam sent to the low-pressure cylinder of the steam turbine drive the low-pressure cylinder to do work, and then are converted into exhaust steam and sent to the condenser. The exhaust steam is cooled after passing through the condenser to form condensed water, and the condensed water is sent to the thermal deaerator by the condensate pump; the exhaust steam at the condenser is cooled by circulating water cooling, and the low-temperature water required for the circulating water cooling is sent to the condenser by the circulating water pump, and after absorbing the latent heat of the exhaust steam, it becomes high-temperature water and is sent to the cooling tower for cooling; Step A5, the hot water formed after the condensate is deoxygenated by the low-pressure thermal deaerator is output in two ways; one way is sent to the medium-pressure waste heat boiler and the low-pressure waste heat boiler by the low-pressure feed water pump; the other way is sent to the high-pressure deaerator for treatment by the relay water pump, and then sent to the blast furnace gas boiler by the high-pressure feed water pump.

6. The working method of the subcritical waste energy and waste heat recovery power generation system of a steel plant according to claim 5 is characterized by: The feed water pipe and the condensate water pipe are provided with a turbine heat recovery system; the turbine heat recovery system can evaluate the utilization of the turbine heat recovery and use the high-pressure heater and the low-pressure heater to increase the return water temperature of the feed water pipe.

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