Gas turbine waste heat boiler steam temperature whole-process automatic control system and control method thereof

Abstract

The invention discloses a gas turbine waste heat boiler steam temperature whole-course automatic control system and a control method thereof.The gas turbine waste heat boiler steam temperature whole-course automatic control system comprises a waste heat boiler utilizing waste gas waste heat, a steam pipeline generating steam is arranged in the waste heat boiler, a steam turbine utilizing steam to do work is arranged beside the waste heat boiler, and a temperature reduction water tank used for storing temperature reduction water is arranged on the rear side of the steam turbine; a high-pressure steam temperature control system and a reheat steam temperature control system are arranged in the waste heat boiler, the steam output end of the high-pressure steam temperature control system is connected with the first steam input end of the steam turbine through an arranged pipeline, and the steam input end of the high-pressure steam temperature control system is connected with the output end of the steam pipeline through an arranged pipeline. The steam output end of the steam turbine is connected with the steam input end of the reheat steam temperature control system through an arranged pipeline. The problem that in the prior art, the deviation between the steam temperature in the waste heat boiler and the set value is too large in the unit starting and running process is solved. The method has the advantage of stable temperature rise rate change.

Description

Technical Field

[0001] The present invention relates to the field of boiler main steam temperature control, and more specifically, to a full-range automatic control system for steam temperature of a gas turbine waste heat boiler and a control method thereof. Background Art

[0002] The vigorous development of gas-steam combined cycle units for power generation has become a trend because of their clean, efficient, fast start-up and shutdown advantages, as well as their great advantages in energy saving, consumption reduction and emission reduction. Combined cycle units have stricter requirements on the degree of automation and automatic control effects. The steam temperature of the waste heat boiler of the gas turbine needs to be fully automatically controlled from the start-up of the gas turbine, cold support, purge, ignition, speed increase, full speed no-load, grid connection with load, and meeting the parameters of the steam turbine start-up. Further improving the quality of automatic regulation is a key task in the commissioning process of the gas-steam combined cycle unit.

[0003] The steam temperature of the boiler of a conventional thermal power unit is generally manually controlled by the operator after the boiler is ignited and coal is added, and the operation is stable. The steam temperature needs to be adjusted according to the start-up and operation of the steam turbine. Large-scale gas-steam combined cycle units are different from conventional thermal power units. In order to meet the rapid start-up and shutdown and peak-shaving functions of the gas turbine, high requirements for automatic control are required. The drum water level, steam temperature and bypass need to be fully automatically controlled during the unit start-up, load increase and decrease, and shutdown process. At the same time, as the rated capacity of combined cycle units continues to increase with technological development, the demand for automatic control is also increasing. The full automatic control of the steam temperature of the gas turbine waste heat boiler is very necessary.

[0004] At present, a waste heat boiler main steam temperature control device is disclosed on the Chinese patent website, with the announcement number CN108518671A. The temperature control device is an existing superheated steam temperature control system with a waste heat boiler main steam temperature control loop dominated by the gas turbine flue gas temperature added; the waste heat boiler main steam temperature control loop dominated by the gas turbine flue gas temperature includes a plurality of groups of flue gas temperature measuring devices respectively arranged at different positions in the gas turbine exhaust flue and the waste heat boiler inlet, and a gas turbine combustion state observation device, a data processing module and an adder. The plurality of groups of flue gas temperature measuring devices at different positions in the gas turbine exhaust flue and the waste heat boiler inlet are respectively connected to the gas turbine combustion state observation device, the gas turbine combustion state observation device is connected to the input end of the data processing module, the output end of the data processing module is connected to the input end of the adder, the input end of the adder is also connected to the output end of the superheated main steam temperature control system, and the output end of the adder is connected to the cooling water valve.

[0005] Although the waste heat boiler main steam temperature control device in the above patent has the advantage of overcoming the interference of the exhaust temperature of the gas turbine and the flue gas temperature fluctuations of the waste heat boiler inlet on the main steam temperature, the patent does not provide a technical solution to the problem of excessive deviation between the steam temperature of the waste heat boiler of the gas-steam combined cycle unit and the set value during the startup and operation of the unit, resulting in a large deviation between the steam temperature of the waste heat boiler of the gas-steam combined cycle unit and the set value during the startup and operation of the unit. Summary of the invention

[0006] In order to overcome the problem in the prior art that the steam temperature of a waste heat boiler of a gas-steam combined cycle unit deviates too much from a set value during the startup and operation of the unit, the present invention provides a full-range automatic control system for the steam temperature of a waste heat boiler of a gas turbine, which has the function of strictly controlling the rate of change of the steam temperature in the waste heat boiler and a control method thereof.

[0007] The invention discloses a full-range automatic control system for the steam temperature of a waste heat boiler of a combustion engine and a control method thereof, comprising a waste heat boiler utilizing waste heat of exhaust gas, wherein a steam pipe for generating steam is arranged in the waste heat boiler, a steam turbine utilizing steam for working is arranged beside the waste heat boiler, a cooling water tank for storing cooling water is arranged at the rear side of the steam turbine, a high-pressure steam temperature control system and a reheat steam temperature control system are arranged in the waste heat boiler respectively, a steam output end of the high-pressure steam temperature control system is connected to a No. 1 steam input end of the steam turbine by arranging a pipe, and ... The inlet end is connected to the output end of the steam pipeline by setting a pipeline, the steam output end of the steam turbine is connected to the steam input end of the reheat steam temperature control system by setting a pipeline, the steam output end of the reheat steam temperature control system is connected to the No. 2 steam input end of the steam turbine by setting a pipeline, the output end of the cooling water tank is respectively connected to the cooling water input end of the high-pressure steam temperature control system and the cooling water input end of the reheat steam temperature control system by setting pipelines, and the control end of the high-pressure steam temperature control system and the control end of the reheat steam temperature control system are electrically connected to the PID controller respectively.

[0008] Preferably, the high-pressure steam temperature control system includes a high-pressure first-level regulation system for performing first-level temperature regulation on steam input into the steam pipeline, and a high-pressure second-level regulation system is provided next to the high-pressure first-level regulation system for use in conjunction with the high-pressure first-level regulation system. The control end of the high-pressure first-level regulation system and the high-pressure second-level regulation system are electrically connected to the PID controller respectively.

[0009] Preferably, the high-pressure primary regulation system includes a No. 1 high-pressure superheater for primary heating of steam, a No. 2 high-pressure superheater for secondary heating of steam is provided on the left side of the No. 1 high-pressure superheater, a high-pressure steam drum is provided on the front side of the waste heat boiler, and a high-pressure feed water pump for conveying cooling water is provided on the right side of the high-pressure steam drum, the steam input end of the No. 1 high-pressure superheater is connected to the output end of the steam pipeline by setting a pipeline, the steam output end of the No. 1 high-pressure superheater is connected to the steam input end of the No. 2 high-pressure superheater by setting a No. 1 bridge pipe, a No. 1 cooling water nozzle for spraying and cooling the input steam is installed on the top of the pipe in the No. 1 bridge pipe, a high-pressure steam outlet isolation valve for controlling the flow rate of the output steam is provided on the steam output end of the waste heat boiler, and the steam output end of the No. 2 high-pressure superheater is connected to the steam input end of the high-pressure steam outlet isolation valve by setting The control end of the high-pressure feed water pump, the control end of the high-pressure superheater, the control end of the high-pressure superheater, the control end of the high-pressure feed water pump, the control end of the No. 1 cooling water nozzle, the high-pressure steam drum and the cooling water input end of the high-pressure secondary regulating system are respectively connected through the provision of pipelines. The No. 1 steam input end of the steam turbine is connected with the output end of the high-pressure steam outlet isolation valve through the provision of pipelines. A high-pressure first-level cooling water regulating valve for regulating the flow of cooling water is installed in the pipeline between the No. 1 cooling water nozzle and the high-pressure feed water pump. A high-pressure first-level cooling water isolation valve for blocking the transportation of cooling water is installed in the pipeline on the right side of the high-pressure first-level cooling water regulating valve. The control end of the No. 1 high-pressure superheater, the control end of the No. 2 high-pressure superheater, the control end of the high-pressure feed water pump, the control end of the No. 1 cooling water nozzle, the control end of the high-pressure first-level cooling water regulating valve and the control end of the high-pressure first-level cooling water isolation valve are electrically connected to the PID controller respectively.

[0010] Preferably, a high-pressure temperature detector for detecting the temperature of steam after being heated by the No. 2 high-pressure superheater is provided on the pipeline between the steam output end of the No. 2 high-pressure superheater and the input end of the high-pressure steam outlet isolation valve, and a waste heat temperature detector for detecting the temperature of steam after leaving the waste heat boiler is provided on the pipeline between the No. 1 steam input end of the steam turbine and the output end of the high-pressure steam outlet isolation valve, and the control end of the high-pressure temperature detector and the control end of the waste heat temperature detector are electrically connected to the PID controller respectively.

[0011] Preferably, the high-pressure secondary regulation system includes a No. 2 cooling water nozzle arranged at the top of the pipeline between the high-pressure steam outlet isolation valve and the No. 1 steam input end of the turbine, the input end of the No. 2 cooling water nozzle is connected to the output end of the high-pressure feed water pump through a pipeline, a high-pressure secondary cooling water regulating valve is installed in the pipeline between the No. 2 cooling water nozzle and the high-pressure feed water pump, and a high-pressure secondary cooling water isolation valve for blocking the delivery of cooling water is installed in the pipeline on the right side of the high-pressure secondary cooling water regulating valve, and the control end of the No. 2 cooling water nozzle, the control end of the high-pressure secondary cooling water regulating valve and the control end of the high-pressure secondary cooling water isolation valve are electrically connected to the PID controller respectively.

[0012] Preferably, the reheat steam temperature control system includes a reheat first-level regulation system for performing first-level regulation on the steam output from the steam turbine, and a reheat second-level regulation system is provided next to the reheat first-level regulation system for use in conjunction with the reheat first-level regulation system. The control end of the reheat first-level regulation system and the control end of the reheat second-level regulation system are electrically connected to the PID controller respectively.

[0013] Preferably, the reheating primary regulation system comprises a No. 1 reheater for primary heating of steam, a No. 2 reheater for secondary heating of steam is arranged on the left side of the No. 1 reheater, a medium-pressure steam drum is arranged on the front side of the waste heat boiler, a medium-pressure feed water pump for conveying cooling water is arranged on the right side of the medium-pressure steam drum, the steam input end of the No. 1 reheater is connected to the steam output end of the steam turbine by setting a pipeline, the steam output end of the No. 1 reheater is connected to the steam input end of the No. 2 reheater by setting a No. 2 bridge pipe, a No. 3 cooling water nozzle for spraying and cooling the input steam is installed on the top of the pipe in the No. 2 bridge pipe, the steam output end of the No. 2 reheater is connected to the No. 2 steam input end of the steam turbine by setting a pipeline, The input end of the medium-pressure feed water pump is connected to the output end of the cooling water tank by setting a pipeline, and the output end of the medium-pressure feed water pump is respectively connected to the cooling water input end of the No. 3 cooling water nozzle, the medium-pressure steam drum and the medium-pressure secondary regulation system by setting a pipeline, and a reheating first-stage cooling water regulating valve for adjusting the cooling water flow rate is installed in the pipeline between the No. 3 cooling water nozzle and the medium-pressure feed water pump, and a reheating first-stage cooling water isolation valve for blocking the cooling water delivery is installed in the pipeline located on the right side of the reheating first-stage cooling water regulating valve, and the control end of the No. 1 reheater, the control end of the No. 2 reheater, the control end of the medium-pressure feed water pump, the control end of the No. 3 cooling water nozzle, the control end of the reheating first-stage cooling water regulating valve and the control end of the reheating first-stage cooling water isolation valve are electrically connected to the PID controller respectively.

[0014] Preferably, a reheat temperature detector for detecting the temperature of steam after heating by the No. 2 reheater is provided on the pipeline between the steam output end of the No. 2 reheater and the No. 2 steam input end of the turbine, and the control end of the reheat temperature detector is electrically connected to the PID controller.

[0015] Preferably, the reheat two-stage regulation system includes a No. 4 cooling water nozzle arranged at the top of the pipeline between the steam output end of the No. 2 reheater and the No. 2 steam input end of the turbine, the input end of the No. 4 cooling water nozzle is connected to the output end of the medium-pressure feed water pump through a pipeline, a reheat two-stage cooling water regulating valve is installed in the pipeline between the No. 4 cooling water nozzle and the medium-pressure feed water pump, and a reheat two-stage cooling water isolation valve for blocking the transportation of cooling water is installed in the pipeline on the right side of the reheat two-stage cooling water regulating valve, and the control end of the No. 4 cooling water nozzle, the control end of the reheat two-stage cooling water regulating valve and the control end of the reheat two-stage cooling water isolation valve are electrically connected to the PID controller respectively.

[0016] The control method is: 1) When the steam turbine is working, the high-temperature exhaust gas is first passed into the waste heat boiler; 2) Then, the water used to generate steam is input into the steam pipe to generate steam through heat exchange with the high-temperature exhaust gas; 3) The steam generated in the steam pipe then flows into the high-pressure steam temperature control system along the pipe; 4) When the steam is working in the high-pressure steam temperature control system, the PID controller will set the corresponding steam temperature required for the steam turbine to work, that is, the final temperature value that the steam needs to reach before entering the steam turbine. According to the steam turbine startup operation curve and the steam turbine startup steam temperature parameter requirements, and combined with the current waste heat boiler operating temperature parameters, the corresponding values ​​of the steam turbine and waste heat boiler temperature setting values ​​are corrected; 5) In order to achieve the disturbance-free switching between the temperature setting value change rate preset by the PID controller and the actual temperature variable of the steam in the waste heat boiler and ensure that the steam temperature setting value can change smoothly to the set final temperature value at the allowable temperature rise rate of the waste heat boiler; 6) The temperature setting value change rate in the PID controller is switched from the initial fixed value of 100℃ / s to the maximum allowable rate of temperature rise of the waste heat boiler; at the same time, in order to avoid excessive deviation between the setting value and the actual temperature, which may cause valve adjustment lag or over-adjustment, when the deviation between the setting value output and the actual temperature value is greater than 5℃, the maximum allowable rate of boiler temperature rise will be switched to the minimum temperature change rate. Under the minimum temperature rise rate limit, when the deviation between the setting value output and the actual temperature value is less than 3℃, the rate limit will be reset; 7) The PID controller collects the actual temperature value of the steam in the waste heat boiler by controlling the high-pressure temperature detector and the waste heat temperature detector, and controls the flow of the cooling water in the pipeline by controlling the high-pressure feed water pump, the No. 1 cooling water nozzle, the No. 2 cooling water nozzle, the high-pressure secondary cooling water regulating valve, and the high-pressure secondary cooling water isolation valve. By limiting the flow of cooling water in the pipeline, the heating rate of the steam by the cooling water is achieved until the steam is heated to the final temperature value required by the steam turbine at a reasonable temperature change rate; 8) When the steam reaches the final temperature value, the steam will flow through the pipeline from the No. 1 steam input end of the steam turbine to work; 9) After the steam has finished its work in the steam turbine, it will go through the pipeline and enter the waste heat boiler again. The reheat steam temperature control system in the waste heat boiler will reheat the steam. 10) The working principle of the reheat steam temperature control system is the same as that of the high-pressure steam temperature control system. The PID controller collects the actual temperature value of the steam entering the waste heat boiler for the second time by controlling the reheat temperature detector, and limits the temperature rise rate of the steam entering the waste heat boiler for the second time by controlling the medium-pressure feed water pump, No. 3 cooling water nozzle, No. 4 cooling water nozzle, reheat secondary cooling water regulating valve, and reheat secondary cooling water isolation valve respectively, until the steam is heated up again to the final temperature value required by the steam turbine at a reasonable temperature change rate; 11) The steam after reheating will enter the steam turbine again for work, completing the recycling of steam.

[0017] The high-pressure steam temperature control system includes primary and secondary cooling water control. The cooling water from the high-pressure feed water pump passes through the high-pressure primary cooling water isolation valve and the regulating valve and then is sprayed into the connecting pipe between the two high-pressure superheaters through the cooling water nozzle to adjust the heating rate of the steam by the high-pressure superheater. The cooling water from the high-pressure feed water pump passes through the high-pressure secondary cooling water isolation valve and the regulating valve and then is sprayed into the pipe behind the high-pressure steam outlet isolation valve to control the high-pressure steam temperature to meet the high-pressure steam temperature parameter requirements for turbine start-up and operation.

[0018] The reheat steam temperature control system includes primary and secondary cooling water control. The cooling water from the medium-pressure feed water pump is sprayed into the connecting pipes of the two reheaters through the medium-pressure primary cooling water isolation valve and the regulating valve to control the heating rate of the steam in the reheater. The cooling water from the medium-pressure feed water pump is sprayed into the reheater outlet pipe after passing through the medium-pressure secondary cooling water isolation valve and the regulating valve to control the reheat steam temperature to meet the reheat steam temperature parameter requirements for turbine start-up and operation.

[0019] The control ends of the first-stage and second-stage desuperheating water regulating valves in the high-pressure steam temperature control system and the control ends of the first-stage and second-stage desuperheating water regulating valves in the reheat steam temperature control system are respectively electrically connected to the PID regulator. The present invention adjusts the desuperheating water flow rate by adjusting the opening of the first-stage and second-stage desuperheating water regulating valves to achieve precise control of the steam temperature of the waste heat boiler.

[0020] The present invention designs the corresponding function between the gas turbine load and the waste heat boiler steam temperature according to the operating characteristics of the gas-steam combined cycle unit, combined with the waste heat boiler temperature rise curve and the steam temperature requirements for turbine startup and operation. The gas-steam combined cycle unit is designed to have a gas turbine with fire and the flue gas three-way damper is closed and disappears, judging the waste heat boiler heat input as an important automatic control judgment signal. At the same time, the temperature setting value is controlled at a rate of change, thereby ensuring that the desuperheating water control system can switch without disturbance and automatically adjust smoothly under different operating conditions such as starting, running and stopping of the waste heat boiler steam temperature, thereby achieving full automatic control of the steam temperature of the gas turbine waste heat boiler. The full automatic control strategy of the first and second desuperheating water of the high-pressure steam temperature of the gas turbine waste heat boiler is consistent with the full automatic control principle of the first and second desuperheating water of the reheat steam temperature. The full automatic control principle of the first and second desuperheating water is as follows: For the temperature setting value of the first-stage cooling water, it is designed that when the first-stage cooling water regulating valve is in the automatic position and there is exhaust gas input to the waste heat boiler, the setting value is switched from tracking the actual steam temperature to the steam temperature corresponding to the current gas turbine load. According to the gas turbine startup operation curve and the steam turbine startup steam temperature parameter requirements, combined with the actual waste heat boiler operating temperature parameters, the corresponding amount of the gas turbine load and the waste heat boiler temperature setting value is corrected.

[0021] In order to achieve the non-disturbance switching between the temperature set value and the actual temperature variable and ensure that the steam temperature set value can change smoothly to the set target value at the allowable temperature rise rate of the waste heat boiler, a temperature set value rate control loop is designed. When the heat input of the waste heat boiler exists and the steam temperature desuperheating water regulating valve is in the automatic position, the temperature set value change rate is switched from 100℃ / s to the maximum allowable rate of boiler temperature rise, and the temperature set value changes from the tracked actual temperature value to the set target value according to the rate controller rate. At the same time, in order to avoid the valve adjustment lag or over-adjustment caused by the large deviation between the set value and the actual temperature, a rate limit is designed. When the deviation between the set value output and the actual temperature value is greater than 5℃, the maximum allowable rate of boiler temperature rise will be cut to the minimum temperature change rate. This rate is obtained after correction based on the boiler cold start temperature rise curve and the actual operating temperature rise rate. Under the minimum temperature rise rate limit, when the deviation value is less than 3℃, the rate limit is reset, and the deviation between the waste heat boiler steam temperature and the set value is effectively controlled.

[0022] For the temperature setting value of the secondary cooling water, it is designed that when the secondary cooling water valve is in the automatic position and there is heat input to the waste heat boiler, the setting value is switched from tracking the actual steam temperature to the steam temperature demand value of the turbine. In the early stage of commissioning, the steam turbine DEH control system is required to design and output the steam temperature demand value of the turbine to the waste heat boiler control system. The signal is output after calculation on the DEH side according to the different startup states and operating conditions of the steam turbine. The temperature signal can be directly used as the temperature setting value of the secondary cooling water regulating valve. The non-disturbance switching and rate control of the temperature setting value of the secondary cooling water are consistent with the design of the primary cooling water. The heat input of the waste heat boiler and the regulating valve in the automatic position are used as the conditions for the actual steam temperature value to be switched to the steam temperature demand value of the turbine. At the same time, the rate limit value is also switched to the maximum allowable value of the boiler temperature rise rate. The minimum temperature change switching control design is consistent with the primary cooling water control, so that the steam temperature of the gas turbine waste heat boiler always meets the steam temperature parameter requirements of the turbine operation.

[0023] The high-pressure steam temperature control system includes primary and secondary cooling water control. The cooling water from the high-pressure feed water pump is sprayed to the inlet of the high-pressure superheater of the waste heat boiler through the high-pressure primary cooling water isolation valve and the regulating valve to control the outlet temperature of the high-pressure superheater of the waste heat boiler. The cooling water from the high-pressure feed water pump is sprayed to the high-pressure steam isolation valve of the waste heat boiler through the high-pressure secondary cooling water isolation valve and the regulating valve to control the high-pressure steam temperature of the waste heat boiler to meet the high-pressure steam temperature parameter requirements for the turbine run-up and operation; the reheat steam temperature control system includes primary and secondary cooling water control. The cooling water from the medium-pressure feed water pump is sprayed to the inlet of the waste heat boiler reheater through the medium-pressure primary cooling water isolation valve and the regulating valve to control the outlet temperature of the waste heat boiler reheater. The cooling water from the medium-pressure feed water pump is sprayed to the reheat steam outlet pipeline of the waste heat boiler through the medium-pressure secondary cooling water isolation valve and the regulating valve to control the reheat steam temperature of the waste heat boiler to meet the reheat steam temperature parameter requirements for the turbine run-up and operation. The present invention connects the primary and secondary desuperheating water regulating valves to a PID regulator, and adjusts the opening of the primary and secondary desuperheating water regulating valves to adjust the desuperheating water flow rate so as to control the steam temperature of the waste heat boiler.

[0024] The present invention designs the heat input signal of the waste heat boiler as the automatic control and set value switching condition of the waste heat boiler steam temperature, designs the steam temperature set value change rate control loop, and the steam temperature set value can realize disturbance-free switching and change to the set target value under reliable rate limit. During the operation of the gas-steam combined cycle, the steam temperature of the waste heat boiler is automatically controlled by the first-level cooling water and the second-level cooling water. The steam temperature demand value of the steam turbine is designed to make the first-level automatic cooling and the second-level automatic cooling control targets clearer. The first-level cooling water controls the outlet temperature of the waste heat boiler superheater to ensure the output of the boiler while preventing the steam temperature from overheating. The second-level cooling water controls the outlet temperature of the waste heat boiler superheater to meet the start-up and operation requirements of the steam turbine. Through the present invention, the full-process automatic control of the steam temperature of the waste heat boiler of the gas-steam combined cycle unit is fully realized, the automatic switching is disturbance-free, and the automatic set value is stable and reliable, meeting the design requirements of the unit.

[0025] The present invention has the following beneficial effects: the temperature rise rate changes stably and is safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Attached Figure 1 It is a schematic diagram of the main structure of the high-pressure steam temperature control of the present invention.

[0027] Attached Figure 2 It is a schematic diagram of the main structure of the reheat steam temperature control of the present invention.

[0028] Attached Figure 3 This is a schematic diagram of the primary cooling water set point switching and rate control principle of the present invention.

[0029] Attached Figure 4 This is a schematic diagram of the secondary cooling water set point switching and rate control principle of the present invention.

[0030] PID controller 1, steam pipeline 2, No. 1 high-pressure superheater 3, No. 2 high-pressure superheater 4, high-pressure steam drum 5, high-pressure feed water pump 6, No. 1 bridge pipeline 7, No. 1 cooling water nozzle 8, high-pressure steam outlet isolation valve 9, high-pressure first-stage cooling water regulating valve 10, high-pressure first-stage cooling water isolation valve 11, high-pressure temperature detector 12, waste heat temperature detector 13, No. 2 cooling water nozzle 14, high-pressure second-stage cooling water regulating valve 15, high-pressure second-stage cooling water isolation valve 16, No. 1 reheater 17, No. 2 reheater 18, medium-pressure steam drum 19, medium-pressure feed water pump 20, No. 2 bridge pipeline 21, No. 3 cooling water nozzle 22, reheat first-stage cooling water regulating valve 23, reheat first-stage cooling water isolation valve 24, reheat temperature detector 25, No. 4 cooling water nozzle 26, reheat second-stage cooling water regulating valve 27, reheat second-stage cooling water isolation valve 28. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0032] Embodiment: According to the attached Figure 1 , Attachment Figure 2 , Attachment Figure 3 and attached Figure 4 To further illustrate, a full-range automatic control system for steam temperature of a waste heat boiler of a gas turbine and a control method thereof, comprising a waste heat boiler utilizing waste heat of exhaust gas and a PID controller 1, wherein a steam pipe 2 for generating steam is arranged in the waste heat boiler, a steam turbine utilizing steam for working is arranged next to the waste heat boiler, a cooling water tank for storing cooling water is arranged at the rear side of the steam turbine, a high-pressure steam temperature control system and a reheat steam temperature control system are arranged in the waste heat boiler respectively, a steam output end of the high-pressure steam temperature control system is connected to a steam input end of the steam turbine by setting a pipeline, and the high-pressure steam temperature control system The steam input end of the system is connected to the output end of the steam pipe 2 by setting a pipeline, the steam output end of the steam turbine is connected to the steam input end of the reheat steam temperature control system by setting a pipeline, the steam output end of the reheat steam temperature control system is connected to the second steam input end of the steam turbine by setting a pipeline, the output end of the cooling water tank is respectively connected to the cooling water input end of the high-pressure steam temperature control system and the cooling water input end of the reheat steam temperature control system by setting pipelines, and the control end of the high-pressure steam temperature control system and the control end of the reheat steam temperature control system are respectively electrically connected to the PID controller 1.

[0033] The high-pressure steam temperature control system includes a high-pressure primary regulation system for performing primary temperature regulation on the steam input into the steam pipe 2. A high-pressure secondary regulation system is provided next to the high-pressure primary regulation system and is used in conjunction with the high-pressure primary regulation system. The control end of the high-pressure primary regulation system and the high-pressure secondary regulation system are electrically connected to the PID controller 1 respectively.

[0034] The high-pressure primary regulation system includes a No. 1 high-pressure superheater 3 for primary heating of steam, a No. 2 high-pressure superheater 4 for secondary heating of steam is provided on the left side of the No. 1 high-pressure superheater 3, a high-pressure steam drum 5 is provided on the front side of the waste heat boiler, and a high-pressure feed water pump 6 for conveying cooling water is provided on the right side of the high-pressure steam drum 5, the steam input end of the No. 1 high-pressure superheater 3 is connected to the output end of the steam pipe 2 by setting a pipeline, the steam output end of the No. 1 high-pressure superheater 3 is connected to the steam input end of the No. 2 high-pressure superheater 4 by setting a No. 1 bridge pipe 7, and a No. 1 cooling water nozzle 8 for spraying and cooling the input steam is installed on the top of the pipeline in the No. 1 bridge pipe 7, a high-pressure steam outlet isolation valve 9 for controlling the flow rate of the output steam is provided on the steam output end of the waste heat boiler, and the steam output end of the No. 2 high-pressure superheater 4 is connected to the steam input end of the high-pressure steam outlet isolation valve 9 by setting a pipeline The input end of the high-pressure feed water pump 6 is connected to the output end of the cooling water tank by setting a pipeline, and the output end of the high-pressure feed water pump 6 is respectively connected to the cooling water input end of the No. 1 cooling water nozzle 8, the high-pressure steam drum 5 and the high-pressure secondary regulation system by setting a pipeline, the No. 1 steam input end of the steam turbine is connected to the output end of the high-pressure steam outlet isolation valve 9 by setting a pipeline, and a high-pressure first-level cooling water regulating valve 10 for regulating the cooling water flow is installed in the pipeline between the No. 1 cooling water nozzle 8 and the high-pressure feed water pump 6, and a high-pressure first-level cooling water isolation valve 11 for blocking the cooling water delivery is installed in the pipeline located on the right side of the high-pressure first-level cooling water regulating valve 10, and the control end of the No. 1 high-pressure superheater 3, the control end of the No. 2 high-pressure superheater 4, the control end of the high-pressure feed water pump 6, the control end of the No. 1 cooling water nozzle 8, the control end of the high-pressure first-level cooling water regulating valve 10 and the control end of the high-pressure first-level cooling water isolation valve 11 are electrically connected to the PID controller 1 respectively.

[0035] A high-pressure temperature detector 12 for detecting the temperature of steam after being heated by the No. 2 high-pressure superheater 4 is provided on the pipeline between the steam output end of the No. 2 high-pressure superheater 4 and the input end of the high-pressure steam outlet isolation valve 9, and a waste heat temperature detector 13 for detecting the temperature of steam after leaving the waste heat boiler is provided on the pipeline between the No. 1 steam input end of the steam turbine and the output end of the high-pressure steam outlet isolation valve 9. The control end of the high-pressure temperature detector 12 and the control end of the waste heat temperature detector 13 are electrically connected to the PID controller 1 respectively.

[0036] The high-pressure secondary regulation system includes a No. 2 cooling water nozzle 14 arranged at the top of the pipeline between the high-pressure steam outlet isolation valve 9 and the No. 1 steam input end of the turbine. The input end of the No. 2 cooling water nozzle 14 is connected to the output end of the high-pressure feed water pump 6 by setting a pipeline. A high-pressure secondary cooling water regulating valve 15 is installed in the pipeline between the No. 2 cooling water nozzle 14 and the high-pressure feed water pump 6. A high-pressure secondary cooling water isolation valve 16 for blocking the transmission of cooling water is installed in the pipeline on the right side of the high-pressure secondary cooling water regulating valve 15. The control end of the No. 2 cooling water nozzle 14, the control end of the high-pressure secondary cooling water regulating valve 15 and the control end of the high-pressure secondary cooling water isolation valve 16 are electrically connected to the PID controller 1 respectively.

[0037] The reheat steam temperature control system includes a reheat primary regulation system for performing primary regulation on the steam output from the steam turbine. A reheat secondary regulation system is provided next to the reheat primary regulation system for use in conjunction with the reheat primary regulation system. The control end of the reheat primary regulation system and the control end of the reheat secondary regulation system are electrically connected to the PID controller 1 respectively.

[0038] The reheating primary regulation system includes a No. 1 reheater 17 for primary heating of steam, a No. 2 reheater 18 for secondary heating of steam is arranged on the left side of the No. 1 reheater 17, a medium-pressure steam drum 19 is arranged on the front side of the waste heat boiler, and a medium-pressure feed water pump 20 for conveying cooling water is arranged on the right side of the medium-pressure steam drum 19, the steam input end of the No. 1 reheater 17 is connected to the steam output end of the steam turbine by setting a pipeline, the steam output end of the No. 1 reheater 17 is connected to the steam input end of the No. 2 reheater 18 by setting a No. 2 bridge pipe 21, and a No. 3 cooling water nozzle 22 for spraying and cooling the input steam is installed on the top of the pipeline in the No. 2 bridge pipe 21, the steam output end of the No. 2 reheater 18 is connected to the No. 2 steam input end of the steam turbine by setting a pipeline, and the medium-pressure The input end of the feed water pump 20 is connected to the output end of the cooling water tank by setting a pipeline, and the output end of the medium-pressure feed water pump 20 is respectively connected to the No. 3 cooling water nozzle 22, the medium-pressure steam drum 19 and the cooling water input end of the medium-pressure secondary regulation system by setting a pipeline, and a reheating first-stage cooling water regulating valve 23 for adjusting the cooling water flow rate is installed in the pipeline between the No. 3 cooling water nozzle 22 and the medium-pressure feed water pump 20, and a reheating first-stage cooling water isolation valve 24 for blocking the cooling water delivery is installed in the pipeline located on the right side of the reheating first-stage cooling water regulating valve 23. The control end of the No. 1 reheater 17, the control end of the No. 2 reheater 18, the control end of the medium-pressure feed water pump 20, the control end of the No. 3 cooling water nozzle 22, the control end of the reheating first-stage cooling water regulating valve 23 and the control end of the reheating first-stage cooling water isolation valve 24 are electrically connected to the PID controller 1 respectively.

[0039] A reheat temperature detector 25 for detecting the temperature of steam heated by the No. 2 reheater 18 is provided on the pipeline between the steam output end of the No. 2 reheater 18 and the No. 2 steam input end of the steam turbine. The reheat temperature detector 25 is electrically connected to the PID controller 1 through its control end.

[0040] The reheating secondary regulation system includes a No. 4 cooling water nozzle 26 arranged at the top of the pipeline between the steam output end of the No. 2 reheater 18 and the No. 2 steam input end of the turbine. The input end of the No. 4 cooling water nozzle 26 is connected to the output end of the medium-pressure feed water pump 20 through a pipeline. A reheating secondary cooling water regulating valve 27 is installed in the pipeline between the No. 4 cooling water nozzle 26 and the medium-pressure feed water pump 20. A reheating secondary cooling water isolation valve 28 for blocking the transportation of cooling water is installed in the pipeline on the right side of the reheating secondary cooling water regulating valve 27. The control end of the No. 4 cooling water nozzle 26, the control end of the reheating secondary cooling water regulating valve 27 and the control end of the reheating secondary cooling water isolation valve 28 are electrically connected to the PID controller 1 respectively.

[0041] The control method is: When the steam turbine is working, the high-temperature exhaust gas is first passed into the waste heat boiler; Then, water for generating steam is input into the steam pipe 2 to generate steam through heat exchange with the high-temperature exhaust gas; Then the steam generated in the steam pipe 2 enters the high-pressure steam temperature control system along the pipe; When the steam is working in the high-pressure steam temperature control system, the PID controller 1 will set the corresponding steam temperature required for the steam turbine to work, that is, the final temperature value that the steam needs to reach before entering the steam turbine, and according to the steam turbine startup operation curve and the steam turbine startup steam temperature parameter requirements, and combined with the current waste heat boiler operating temperature parameters, the corresponding amount of the steam turbine and waste heat boiler temperature setting values ​​is corrected; In order to achieve the disturbance-free switching between the temperature setting value change rate preset by the PID controller 1 and the actual temperature variable of the steam in the waste heat boiler and ensure that the steam temperature setting value can change smoothly to the set final temperature value at the allowable temperature rise rate of the waste heat boiler; The temperature setting value change rate in PID controller 1 is switched from the initial fixed value of 100℃ / s to the maximum allowable rate of temperature rise of the waste heat boiler; at the same time, in order to avoid excessive deviation between the setting value and the actual temperature, which may cause valve adjustment lag or over-adjustment, when the deviation between the setting value output and the actual temperature value is greater than 5℃, the maximum allowable rate of boiler temperature rise will be switched to the minimum temperature change rate. Under the minimum temperature rise rate limit, when the deviation between the setting value output and the actual temperature value is less than 3℃, the rate limit will be reset; The PID controller 1 collects the actual temperature value of the steam in the waste heat boiler by controlling the high-pressure temperature detector 12 and the waste heat temperature detector 13, and controls the flow of the cooling water in the pipeline by respectively controlling the high-pressure feed water pump 6, the first cooling water nozzle 8, the second cooling water nozzle 14, the high-pressure secondary cooling water regulating valve 15, and the high-pressure secondary cooling water isolation valve 16. The heating rate of the steam by the cooling water is controlled by limiting the flow of the cooling water in the pipeline until the steam is heated to the final temperature value required by the steam turbine at a reasonable temperature change rate; When the steam reaches the final temperature value, the steam will flow through the pipeline from the No. 1 steam input end of the steam turbine to work in the steam turbine; After the steam has finished its work in the steam turbine, it will go through the pipeline and enter the waste heat boiler again. The reheat steam temperature control system in the waste heat boiler will reheat the steam. The working principle of the reheat steam temperature control system is the same as that of the high-pressure steam temperature control system. The PID controller 1 collects the actual temperature value of the steam entering the waste heat boiler for the second time by controlling the reheat temperature detector 25, and limits the temperature rise rate of the steam entering the waste heat boiler for the second time by controlling the medium-pressure feed water pump 20, the No. 3 cooling water nozzle 22, the No. 4 cooling water nozzle 26, the reheat secondary cooling water regulating valve 27, and the reheat secondary cooling water isolation valve 28 respectively, until the steam is heated up again to the final temperature value required by the steam turbine at a reasonable temperature change rate; The steam after reheating treatment will enter the steam turbine again for work, completing the recycling of steam.

[0042] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A full-range automatic control system for the steam temperature of a waste heat boiler of a gas turbine, comprising a waste heat boiler utilizing waste heat of exhaust gas and a PID controller (1), wherein a steam pipe (2) for generating steam is provided in the waste heat boiler, a steam turbine utilizing steam for operation is provided next to the waste heat boiler, and a cooling water tank for storing cooling water is provided at the rear of the steam turbine, wherein: The waste heat boiler is provided with a high-pressure steam temperature control system and a reheat steam temperature control system, respectively. The steam output end of the high-pressure steam temperature control system is connected to the No. 1 steam input end of the steam turbine by means of a pipeline, the steam input end of the high-pressure steam temperature control system is connected to the output end of the steam pipeline (2) by means of a pipeline, the steam output end of the steam turbine is connected to the steam input end of the reheat steam temperature control system by means of a pipeline, the steam output end of the reheat steam temperature control system is connected to the No. 2 steam input end of the steam turbine by means of a pipeline, the output end of the cooling water tank is connected to the cooling water input end of the high-pressure steam temperature control system and the cooling water input end of the reheat steam temperature control system by means of pipelines, and the control end of the high-pressure steam temperature control system and the control end of the reheat steam temperature control system are electrically connected to the PID controller (1) respectively.

2. The full-range automatic control system for steam temperature of a waste heat boiler of a gas turbine according to claim 1 is characterized in that: The high-pressure steam temperature control system comprises a high-pressure primary regulating system for performing primary temperature regulation on steam input into a steam pipe (2); a high-pressure secondary regulating system for use in conjunction with the high-pressure primary regulating system is disposed adjacent to the high-pressure primary regulating system; a control end of the high-pressure primary regulating system and the high-pressure secondary regulating system are electrically connected to a PID controller (1) respectively.

3. The full-range automatic control system for steam temperature of a waste heat boiler of a gas turbine according to claim 2 is characterized in that: The high-pressure primary regulation system comprises a No. 1 high-pressure superheater (3) for primary heating of steam, a No. 2 high-pressure superheater (4) for secondary heating of steam is arranged on the left side of the No. 1 high-pressure superheater (3), a high-pressure drum (5) is arranged on the front side of the waste heat boiler, a high-pressure feed water pump (6) for conveying cooling water is arranged on the right side of the high-pressure drum (5), the steam input end of the No. 1 high-pressure superheater (3) is connected to the output end of the steam pipeline (2) by means of a pipeline, the steam output end of the No. 1 high-pressure superheater (3) is connected to the steam input end of the No. 2 high-pressure superheater (4) by means of a No. 1 bridge pipeline (7), a No. 1 cooling water nozzle (8) for spraying and cooling the input steam is installed on the top of the pipeline in the No. 1 bridge pipeline (7), a high-pressure steam outlet isolation valve (9) for controlling the flow rate of the output steam is arranged on the steam output end of the waste heat boiler, the steam output end of the No. 2 high-pressure superheater (4) is connected to the steam input end of the high-pressure steam outlet isolation valve (9) by means of a pipeline, The input end of the high-pressure feed water pump (6) is connected to the output end of the cooling water tank by means of a pipeline, the output end of the high-pressure feed water pump (6) is respectively connected to the No. 1 cooling water nozzle (8), the high-pressure steam drum (5) and the cooling water input end of the high-pressure secondary regulating system by means of pipelines, the No. 1 steam input end of the steam turbine is connected to the output end of the high-pressure steam outlet isolation valve (9) by means of pipelines, and a high-pressure valve for adjusting the cooling water flow rate is installed in the pipeline between the No. 1 cooling water nozzle (8) and the high-pressure feed water pump (6). A first-stage cooling water regulating valve (10) is provided with a high-pressure first-stage cooling water isolation valve (11) for blocking the transmission of cooling water in a pipeline located on the right side of the high-pressure first-stage cooling water regulating valve (10). The control end of the No. 1 high-pressure superheater (3), the control end of the No. 2 high-pressure superheater (4), the control end of the high-pressure water feed pump (6), the control end of the No. 1 cooling water nozzle (8), the control end of the high-pressure first-stage cooling water regulating valve (10) and the control end of the high-pressure first-stage cooling water isolation valve (11) are respectively electrically connected to the PID controller (1).

4. The full-range automatic control system for steam temperature of a waste heat boiler of a gas turbine according to claim 3 is characterized in that: A high-pressure temperature detector (12) for detecting the temperature of steam heated by the No. 2 high-pressure superheater (4) is provided on a pipeline between the steam output end of the No. 2 high-pressure superheater (4) and the input end of the high-pressure steam outlet isolation valve (9). A waste heat temperature detector (13) for detecting the temperature of steam after leaving the waste heat boiler is provided on a pipeline between the No. 1 steam input end of the steam turbine and the output end of the high-pressure steam outlet isolation valve (9). The control end of the high-pressure temperature detector (12) and the control end of the waste heat temperature detector (13) are electrically connected to the PID controller (1) respectively.

5. The full-range automatic control system for steam temperature of a waste heat boiler of a gas turbine according to claim 3 is characterized in that: The high-pressure secondary regulation system comprises a No. 2 cooling water nozzle (14) arranged at the top of the pipeline between the high-pressure steam outlet isolation valve (9) and the No. 1 steam input end of the steam turbine, the input end of the No. 2 cooling water nozzle (14) is connected to the output end of the high-pressure feed water pump (6) by means of a pipeline, a high-pressure secondary cooling water regulating valve (15) is installed in the pipeline between the No. 2 cooling water nozzle (14) and the high-pressure feed water pump (6), a high-pressure secondary cooling water isolation valve (16) for blocking the transmission of cooling water is installed in the pipeline located on the right side of the high-pressure secondary cooling water regulating valve (15), and the control end of the No. 2 cooling water nozzle (14), the control end of the high-pressure secondary cooling water regulating valve (15) and the control end of the high-pressure secondary cooling water isolation valve (16) are respectively electrically connected to the PID controller (1).

6. The full-range automatic control system for steam temperature of a waste heat boiler of a gas turbine according to claim 1 is characterized in that: The reheat steam temperature control system comprises a reheat primary regulating system for performing primary regulation on steam output from a steam turbine, a reheat secondary regulating system is provided next to the reheat primary regulating system for use in conjunction with the reheat primary regulating system, and a control end of the reheat primary regulating system and a control end of the reheat secondary regulating system are electrically connected to a PID controller (1) respectively.

7. The full-range automatic control system for steam temperature of a waste heat boiler of a gas turbine according to claim 6 is characterized in that: The reheating primary regulation system comprises a No. 1 reheater (17) for performing primary heating of steam, a No. 2 reheater (18) for performing secondary heating of steam is arranged on the left side of the No. 1 reheater (17), a medium-pressure steam drum (19) is arranged on the front side of the waste heat boiler, a medium-pressure feed water pump (20) for conveying cooling water is arranged on the right side of the medium-pressure steam drum (19), the steam input end of the No. 1 reheater (17) is connected to the steam output end of the steam turbine by means of a pipeline, the steam output end of the No. 1 reheater (17) is connected to the steam input end of the No. 2 reheater (18) by means of a No. 2 bridge pipe (21), a No. 3 cooling water nozzle (22) for spraying and cooling the input steam is installed on the top of the pipe in the No. 2 bridge pipe (21), the steam output end of the No. 2 reheater (18) is connected to the No. 2 steam input end of the steam turbine by means of a pipeline, and the medium-pressure feed water pump (20) for conveying cooling water is arranged on the right side of the medium-pressure steam drum (19), the steam input end of the No. 1 reheater (17) is connected to the steam output end of the steam turbine by means of a pipeline, the steam output end of the No. 1 reheater (17) is connected to the steam input end of the No. 2 reheater (18) by means of a No. 2 bridge pipe (21), the steam output end of the No. 2 reheater (18) is connected to the No. 2 steam input end of the steam turbine by means of a pipeline, The input end of the medium-pressure feed water pump (20) is connected to the output end of the cooling water tank by setting a pipeline, and the output end of the medium-pressure feed water pump (20) is connected to the cooling water input end of the No. 3 cooling water nozzle (22), the medium-pressure drum (19) and the medium-pressure secondary regulating system by setting a pipeline, and a reheating first-stage cooling water regulating valve (23) for regulating the cooling water flow is installed in the pipeline between the No. 3 cooling water nozzle (22) and the medium-pressure feed water pump (20). A first-stage reheat water isolation valve (24) for blocking the delivery of cooling water is installed in the pipeline on the right side of the water regulating valve (23). The control end of the No. 1 reheater (17), the control end of the No. 2 reheater (18), the control end of the medium-pressure feed water pump (20), the control end of the No. 3 cooling water nozzle (22), the control end of the first-stage reheat water regulating valve (23) and the control end of the first-stage reheat water isolation valve (24) are electrically connected to the PID controller (1) respectively.

8. The full-range automatic control system for steam temperature of a waste heat boiler of a gas turbine according to claim 6 is characterized in that: A reheat temperature detector (25) for detecting the temperature of steam heated by the No. 2 reheater (18) is provided on a pipeline between the steam output end of the No. 2 reheater (18) and the No. 2 steam input end of the steam turbine. The reheat temperature detector (25) is electrically connected to the PID controller (1).

9. The full-range automatic control system for steam temperature of a waste heat boiler of a gas turbine according to claim 6 is characterized in that: The reheating secondary regulating system comprises a No. 4 cooling water nozzle (26) arranged at the top of the pipeline between the steam output end of the No. 2 reheater (18) and the No. 2 steam input end of the steam turbine, the input end of the No. 4 cooling water nozzle (26) is connected to the output end of the medium-pressure feed water pump (20) by means of a pipeline, a reheating secondary cooling water regulating valve (27) is installed in the pipeline between the No. 4 cooling water nozzle (26) and the medium-pressure feed water pump (20), a reheating secondary cooling water isolation valve (28) for blocking the transmission of cooling water is installed in the pipeline on the right side of the reheating secondary cooling water regulating valve (27), and the control end of the No. 4 cooling water nozzle (26), the control end of the reheating secondary cooling water regulating valve (27) and the control end of the reheating secondary cooling water isolation valve (28) are respectively electrically connected to the PID controller (1).

10. A control method applicable to a full-process automatic control system of steam temperature of a waste heat boiler of a gas turbine as claimed in claim 1, characterized in that: The control method is: When the steam turbine is working, the high-temperature exhaust gas is first passed into the waste heat boiler; Then, water for generating steam is input into the steam pipe (2) to generate steam through heat exchange with the high-temperature exhaust gas; The steam generated in the steam pipe (2) then flows along the pipe into the high-pressure steam temperature control system; When the steam is working in the high-pressure steam temperature control system, the PID controller (1) will set the steam temperature corresponding to the steam turbine operation, that is, the final temperature value that the steam needs to reach before entering the steam turbine, and correct the corresponding amount of the steam turbine and waste heat boiler temperature setting value according to the steam turbine startup operation curve and the steam turbine startup steam temperature parameter requirements, and combined with the current waste heat boiler operating temperature parameters; In order to achieve a disturbance-free switching between the change rate of the temperature set value preset by the PID controller (1) and the actual temperature variable of the steam in the waste heat boiler and to ensure that the steam temperature set value can change smoothly to the set final temperature value at the allowable temperature rise rate of the waste heat boiler; The temperature setting value change rate in the PID controller (1) is switched from the initial fixed value of 100°C / s to the maximum allowable rate of temperature rise of the waste heat boiler. At the same time, in order to avoid excessive deviation between the setting value and the actual temperature, which may cause valve adjustment lag or over-adjustment, when the deviation between the setting value output and the actual temperature value is greater than 5°C, the maximum allowable rate of boiler temperature rise will be switched to the minimum temperature change rate. Under the minimum temperature rise rate limit, when the deviation between the setting value output and the actual temperature value is less than 3°C, the rate limit is reset. The PID controller (1) collects the actual temperature value of the steam in the waste heat boiler by controlling the high-pressure temperature detector (12) and the waste heat temperature detector (13), and controls the flow rate of the cooling water in the pipeline by respectively controlling the high-pressure feed water pump (6), the first cooling water nozzle (8), the second cooling water nozzle (14), the high-pressure secondary cooling water regulating valve (15), and the high-pressure secondary cooling water isolation valve (16). By limiting the flow rate of the cooling water in the pipeline, the heating rate of the steam by the cooling water is controlled until the steam is heated to the final temperature value required by the steam turbine at a reasonable temperature change rate; When the steam reaches the final temperature value, the steam will flow through the pipeline from the No. 1 steam input end of the steam turbine to work in the steam turbine; After the steam has finished its work in the steam turbine, it will go through the pipeline and enter the waste heat boiler again. The reheat steam temperature control system in the waste heat boiler will reheat the steam. The working principle of the reheat steam temperature control system is the same as that of the high-pressure steam temperature control system. The PID controller (1) collects the actual temperature value of the steam entering the waste heat boiler for the second time by controlling the reheat temperature detector (25), and limits the temperature rise rate of the steam entering the waste heat boiler for the second time by controlling the medium-pressure feed water pump (20), the third cooling water nozzle (22), the fourth cooling water nozzle (26), the reheat secondary cooling water regulating valve (27), and the reheat secondary cooling water isolation valve (28) respectively, until the steam is heated again to the final temperature value required by the steam turbine at a reasonable temperature change rate; The steam after reheating treatment will enter the steam turbine again for work, completing the recycling of steam.

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