CN-121976879-A - Gas turbine waste heat step energy storage and starting auxiliary system and control method thereof

CN121976879ACN 121976879 ACN121976879 ACN 121976879ACN-121976879-A

Abstract

The application relates to the technical field of gas turbine power generation, in particular to a gas turbine waste heat step energy storage and starting auxiliary system and a control method thereof. The system comprises a fused salt phase-change energy storage module, steam, a fused salt heat exchange network module and an intelligent control system, wherein the fused salt phase-change energy storage module is arranged in a flue gas channel between an economizer and a superheater of a waste heat boiler, the steam and fused salt heat exchange network module comprises a three-stage heat exchanger and is connected with a cylinder assembly and a pneumatic jigger device of a steam turbine through a main steam pipeline, and is connected with a shaft seal steam supply subsystem and a natural gas preheating module through a shaft seal steam pipeline, and is connected with the fused salt phase-change energy storage module through a pipeline and a steam loop in the superheater so as to respectively receive high-temperature fused salt heat energy and steam. The technical problems of waste of residual heat energy of flue gas, long starting time, serious waste of natural gas energy and electric power energy, high purchase cost, installation cost and high maintenance cost of starting equipment are solved.

Inventors

FU XUFENG
LU JIANLIN
CHEN CHENG
LI WEI
ZHANG GUILIN
LONG YANCHANG
LI JIELONG

Assignees

华电电力科学研究院有限公司

Dates

Publication Date: 20260505
Application Date: 20260313

Claims (10)

1. The gas turbine waste heat cascade energy storage and starting auxiliary system is characterized by comprising a fused salt phase change energy storage module, a fused salt phase change energy storage module and a control module, wherein the fused salt phase change energy storage module is arranged in a flue gas channel between an economizer and a superheater of a waste heat boiler and is used for recovering flue gas waste heat after the gas turbine is stopped and storing the flue gas waste heat into fused salt heat energy when the gas turbine is stopped; The steam and molten salt heat exchange network module comprises a three-stage heat exchanger consisting of a low-pressure heat exchanger, a medium-pressure heat exchanger and a high-pressure heat exchanger, is connected with a cylinder assembly and a pneumatic jigger device of the steam turbine through a main steam pipeline, is connected with a shaft seal steam supply subsystem and a natural gas preheating module through a shaft seal steam pipeline, and is also connected with the molten salt phase change energy storage module through a pipeline and is connected with a steam loop in the superheater through a pipeline so as to respectively receive high-temperature molten salt heat energy stored by the molten salt phase change energy storage module and steam provided by the steam loop; And The intelligent control system is in control connection with the fused salt phase change energy storage module, the steam and fused salt heat exchange network module, the waste heat boiler and all connecting pipelines.
2. The gas turbine waste heat step energy storage and starting auxiliary system according to claim 1, further comprising a three-way valve and three passages respectively connected with the three interfaces, wherein the three passages are respectively a first passage, a second passage and a third passage, and the intelligent control system is in control connection with the three-way valve; The first passage is fixedly connected with the steam loop in the superheater, the second passage is switchably connected with the three-stage heat exchanger of the steam and molten salt heat exchange network module, and the third passage is switchably connected with the main steam pipeline; when the intelligent control system starts heating, the intelligent control system controls the three-way valve to be connected to the second passage in a switching mode, so that the first passage and the second passage are communicated; When conventional power generation is performed, the intelligent control system controls the three-way valve to be connected to the third passage in a switching mode, so that the first passage and the third passage are communicated.
3. The gas turbine waste heat step energy storage and start-up assistance system of claim 2, wherein the steam circuit in the superheater comprises a low pressure steam circuit, a medium pressure steam circuit and a high pressure steam circuit; When starting up heat, the low pressure steam circuit, the medium pressure steam circuit and the high pressure steam circuit are respectively communicated with the low pressure heat exchanger, the medium pressure heat exchanger and the high pressure heat exchanger of the steam and molten salt heat exchange network module to provide low pressure steam, medium pressure steam and high pressure steam; When conventional power generation is performed, the low pressure steam circuit, the medium pressure steam circuit and the high pressure steam circuit are respectively communicated with the low pressure cylinder, the medium pressure cylinder and the high pressure cylinder of the steam turbine to respectively provide low pressure high temperature steam, medium pressure high temperature steam and high pressure high temperature steam.
4. The gas turbine waste heat step energy storage and starting auxiliary system according to claim 3, wherein low-pressure high-temperature steam, medium-pressure high-temperature steam and high-pressure high-temperature steam generated by the steam and molten salt heat exchange network module are respectively supplied to a low-pressure cylinder, a medium-pressure cylinder and a high-pressure cylinder of the steam turbine through the main steam pipeline, and the high-pressure high-temperature steam is also simultaneously supplied to the pneumatic jigger device through the main steam pipeline, and the medium-pressure high-temperature steam is also simultaneously supplied to the shaft seal steam supply subsystem and the natural gas preheating module through the shaft seal steam pipeline; And the shaft seal steam supply subsystem and the natural gas preheating module are started synchronously with the shaft seal steam pipeline.
5. The gas turbine waste heat step energy storage and starting auxiliary system according to claim 4, wherein, The pneumatic turning device comprises a rotor pushing device and a rotor high-speed driving device, low-pressure high-temperature steam provided by the low-pressure heat exchanger is supplied to the low-pressure cylinder to drive the rotor pushing device to drive the turbine rotor to slowly rotate, medium-pressure high-temperature steam provided by the medium-pressure heat exchanger is supplied to the medium-pressure cylinder to drive the gas turbine to ignite and simultaneously supplied to the natural gas preheating module to heat the natural gas, and high-pressure high-temperature steam provided by the high-pressure heat exchanger is supplied to the high-pressure cylinder and the rotor high-speed driving device to push the ignition rotating speed of the gas turbine rotor to rise to the grid-connected rotating speed, so that the quick start of the gas turbine is completed.
6. The gas turbine waste heat step energy storage and starting auxiliary system according to claim 1, wherein, The molten salt phase-change energy storage module comprises a molten salt hot tank for storing high-temperature molten salt and a molten salt cold tank for storing low-temperature molten salt, wherein the temperature of the high-temperature molten salt is at least 560 ℃, the temperature of the low-temperature molten salt is at least 290 ℃, and the temperature of the flue gas waste heat is between 250 and 500 ℃; When the gas turbine is stopped, the low-temperature molten salt in the molten salt cooling tank and the flue gas waste heat in the flue gas pipeline are directly subjected to heat exchange and recovery, and the molten salt is pumped to the molten salt heating tank for storage after the temperature is increased to 560 ℃ Cheng Gaowen; And the molten salt phase change energy storage module is provided with a molten salt pump at the output end side of a pipeline connected with the steam and molten salt heat exchange network module, the intelligent control system is also in control connection with the molten salt pump, and when the molten salt pump is started, the molten salt pump is controlled to be started, and high-temperature molten salt heat energy stored by the molten salt phase change energy storage module is pumped into the three-stage heat exchanger.
7. The gas turbine waste heat step energy storage and starting auxiliary system according to claim 1, wherein, The shaft seal steam supply subsystem comprises a special heater, a steam buffer tank, a temperature and pressure reduction device and a temperature control system, wherein the input end of the special heater is connected with the shaft seal steam pipeline, the output end of the special heater is connected with the shaft seal pipeline of the gas turbine through the steam buffer tank and the temperature and pressure reduction device, and the temperature control system monitors the steam temperature in real time through a sensor and/or The natural gas preheating module is arranged into a shell-and-tube heat exchanger, a shell side is communicated with the shaft seal steam pipeline, a tube side is communicated with a natural gas inlet pipeline of the gas turbine, and the shaft seal steam flow is regulated through the intelligent control system to heat the natural gas to 50-80 ℃.
8. The gas turbine waste heat step energy storage and starting auxiliary system according to claim 1, wherein, The turbine is also in driving connection with a generator to drive the generator to generate electric energy, and/or The exhaust pipe of the steam turbine is connected with the steam loop of the superheater through a condenser and a water supply pump, so that exhaust steam exhausted by the exhaust pipe of the steam turbine enters the condenser, and is condensed into water and then is pumped back to the steam loop of the superheater through the water supply pump for circulation.
9. A control method of a gas turbine waste heat cascade energy storage and starting auxiliary system, characterized by being applied to the gas turbine waste heat cascade energy storage and starting auxiliary system according to any one of claims 1 to 8, the control method comprising: And (3) stopping the machine to store energy: When the gas turbine receives a shutdown instruction, the intelligent control system is switched to a shutdown heat storage state, and the molten salt pump is controlled to be started, so that the flue gas waste heat after the gas turbine is shut down and the low-temperature molten salt in the molten salt phase-change energy storage module exchange heat and are heated to high-temperature molten salt and then are stored in the molten salt hot tank; When the temperature of the flue gas is reduced to below 250 ℃ and lasts for 30 seconds, the molten salt pump is turned off, the intelligent control system is switched to a standby state, and the shutdown energy storage is completed; A hot stage for start-up: When the gas turbine receives a starting instruction, the intelligent control system is switched to a hot state for starting, the molten salt pump is controlled to be started, so that high-temperature molten salt in the molten salt phase change energy storage module is pumped into a three-stage heat exchanger of the steam and molten salt heat exchange network module, a three-way valve is controlled to be switched and connected with a steam loop in a superheater of the waste heat boiler to be communicated with the three-stage heat exchanger of the steam and molten salt heat exchange network module, steam enters the three-stage heat exchanger in the steam and molten salt heat exchange network module, after the steam is heated by the high-temperature molten salt, low-pressure high-temperature steam, medium-pressure high-temperature steam and high-pressure high-temperature steam are respectively output by a low-pressure heat exchanger, a medium-pressure heat exchanger and a high-pressure heat exchanger of the gas turbine, and are transmitted to a low-pressure cylinder, a medium-pressure cylinder, a high-pressure cylinder and a pneumatic jigger device of the steam turbine and a shaft seal steam supply subsystem and a natural gas preheating module of the gas turbine in a grading manner, so that the gas turbine is ignited from a low-speed jigger to a high-speed jigger to the gas turbine and then the gas turbine is raised to a grid-connected speed, and the gas turbine is started rapidly; When the gas turbine is accelerated to the grid-connected rotating speed, the intelligent control system is switched to a conventional power generation state, the molten salt pump is stopped gradually, and the starting heat utilization is completed.
10. The method for controlling a gas turbine waste heat step energy storage and start-up assist system of claim 9, further comprising: Conventional power generation stage: When the gas turbine is in stable operation at the grid-connected rotation speed and the exhaust temperature is more than 500 ℃, the intelligent control system is switched to a conventional power generation state, the three-way valve is controlled to be switched and connected with a steam loop in a superheater of the waste heat boiler to be directly connected with a main steam pipeline, high-temperature steam is directly supplied to the turbine, the molten salt pump stops rotating, and the molten salt phase-change energy storage module enters a standby state; The high-temperature flue gas discharged by the gas turbine enters the waste heat boiler, sequentially passes through the superheater and the economizer, firstly heats water of the steam loop to generate low-pressure high-temperature steam, medium-pressure high-temperature steam and high-pressure high-temperature steam, supplies the low-pressure cylinder, the medium-pressure cylinder and the high-pressure cylinder which enter the gas turbine, drives the gas turbine to operate and simultaneously drives the generator to generate electricity; after the exhaust steam of the steam turbine enters a condenser to be condensed, the exhaust steam is sent back to a steam loop of a superheater of the waste heat boiler for circulation through a water supply pump; The shaft seal steam supply subsystem continuously works, and the pneumatic jigger device and the natural gas preheating module stop working.

Description

Gas turbine waste heat step energy storage and starting auxiliary system and control method thereof Technical Field The application relates to the technical field of gas turbine power generation, in particular to a gas turbine waste heat step energy storage and starting auxiliary system and a control method thereof. Background In a gas and steam combined cycle power plant, air is compressed in multiple stages by a gas compressor and then mixed with natural gas in a combustion chamber to generate high-temperature and high-pressure gas to drive a gas turbine impeller to rotate so as to drive a generator to generate power, and at the moment, the flue gas exhausted by the gas turbine still has a large amount of waste heat, the temperature can reach about 600 ℃, the high-temperature flue gas exhausted by the gas turbine enters a waste heat boiler to heat water in the waste heat boiler so as to change the water into high-temperature and high-pressure steam, and then the high-temperature and high-pressure steam is utilized to drive the steam turbine to rotate so as to drive the generator to generate power, so that the secondary utilization of the waste heat of the flue gas is realized. However, after the gas turbine is normally stopped, the waste heat of the flue gas at 250-500 ℃ is still remained in the waste heat boiler, and the waste heat of the flue gas is generally discharged from an outlet of the waste heat boiler directly or partially recovered, but the waste heat recovery rate is less than 40%, so that waste of waste heat energy of the flue gas is caused. In addition, the starting of the existing peak regulation type gas and steam combined cycle unit completely depends on the starting of an independent starting boiler system, and comprises an electric jigger and an electric gas turbine variable frequency starting device. The independent starting boiler system is high in equipment purchase cost and installation cost, high in initial investment, long in starting time, at least 60 minutes are required from ignition to completion of cold starting of a unit, quick peak regulation of a power grid is difficult to respond, a large amount of natural gas and electric energy are consumed during starting, natural gas energy and electric energy are seriously wasted, a large amount of plant power is consumed, electricity consumption cost is high, the starting boiler burns natural gas to generate carbon dioxide, the starting emission is about 400kg each time, the starting is 50-60 times in a year, accumulated emission is large, environmental protection benefits are poor, the operation and maintenance cost of the independent starting boiler system is high, the number of times of annual maintenance is at least 12, single maintenance cost is at least 5 ten thousands yuan, and the equipment failure risk is high. Disclosure of Invention The application aims to provide a gas turbine waste heat step energy storage and starting auxiliary system and a control method thereof, which are used for solving the technical problems of waste of the existing flue gas waste heat energy, long starting time of starting equipment, serious waste of natural gas energy and electric power energy, high purchase cost, high installation cost and high maintenance cost of the starting equipment and the like. The application provides a gas turbine waste heat cascade energy storage and starting auxiliary system, which comprises a fused salt phase change energy storage module, a gas turbine waste heat energy storage module and a gas turbine waste heat energy storage module, wherein the fused salt phase change energy storage module is arranged in a flue gas channel between an economizer and a superheater of a waste heat boiler and is used for recovering flue gas waste heat after the gas turbine is stopped and storing fused salt heat energy when the gas turbine is stopped; The steam and molten salt heat exchange network module comprises a three-stage heat exchanger consisting of a low-pressure heat exchanger, a medium-pressure heat exchanger and a high-pressure heat exchanger, is connected with a cylinder assembly and a pneumatic jigger device of the steam turbine through a main steam pipeline, is connected with a shaft seal steam supply subsystem and a natural gas preheating module through a shaft seal steam pipeline, and is also connected with the molten salt phase change energy storage module through a pipeline and is connected with a steam loop in the superheater through a pipeline so as to respectively receive high-temperature molten salt heat energy stored by the molten salt phase change energy storage module and steam provided by the steam loop; And The intelligent control system is in control connection with the fused salt phase change energy storage module, the steam and fused salt heat exchange network module, the waste heat boiler and all connecting pipelines. Further, the gas turbine waste heat step energy storage and starting auxiliary system f