A method for multi-stage parallel start-up control of a two-to-one gas-steam combined cycle unit

Abstract

This invention discloses a multi-stage parallel start-up control method for a two-to-one gas-steam combined cycle unit. The method involves identifying the energy-saving space for parallel operation of each system device and implementing the most energy-efficient and time-saving control throughout the entire operation process. It fully utilizes the start-up allowances of the two gas turbines, two waste heat boilers, and various auxiliary systems, breaking away from the traditional control method that requires sequential start-up according to design requirements. This achieves efficient start-up and operation of the two-to-one gas-steam combined cycle unit. This invention enables efficient start-up of two-to-one gas-steam combined cycle units.

Description

Technical Field

[0001] This invention belongs to the field of intelligent control of two-to-one gas-steam combined cycle units, specifically relating to a multi-stage parallel start-up control method for two-to-one gas-steam combined cycle units. Background Technology

[0002] The control process of a two-to-one gas-steam combined cycle unit typically involves complex systems and multiple decision-making methods. Because the gas turbine and steam turbine are usually arranged on separate shafts, the steam turbine needs to undergo processes such as turbine start-up, turbine warm-up, turbine grid connection, and unit load increase. Furthermore, the steam from two waste heat boilers is integrated into one turbine, making the control of its steam thermal system more complex and requiring more decision-making conditions compared to a one-to-one single-shaft unit. At the same time, domestic experience in controlling and operating two-to-one gas-steam combined cycle units is relatively scarce. Implementing multi-stage parallel start-up and shutdown control for two-to-one gas-steam combined cycle units can effectively shorten the unit start-up time, enable parallel intelligent operation of multiple system devices, and achieve efficient and rapid start-up and shutdown operation of the two-to-one gas-steam combined cycle unit. Summary of the Invention

[0003] To address the above problems, the present invention aims to provide a multi-stage parallel start-up control method for a two-to-one gas-steam combined cycle unit.

[0004] The present invention is achieved using the following technical solution:

[0005] A multi-stage parallel start-up control method for a two-to-one gas-steam combined cycle unit includes:

[0006] This method finds the energy-saving space for parallel operation of each system device, and implements the most energy-efficient and time-saving control method throughout the entire operation process. It makes full use of the start-up allowable release space of the two gas turbines, two waste heat boilers and various auxiliary systems, breaking away from the traditional control method that requires starting one by one according to design requirements, and realizing the efficient start-up and operation of the two-on-one gas-steam combined cycle unit.

[0007] A further improvement of the present invention is that the method specifically includes the following implementation steps:

[0008] The first step is for the operator to manually click to confirm the "Multi-stage parallel start-up control of two-to-one gas-steam combined cycle units" function;

[0009] The second step is to simultaneously start the circulating water system and the demineralized water system.

[0010] The third step is to simultaneously start both the open water system and the closed water system.

[0011] Fourth step: Simultaneously start the air compressor switching and start the boiler;

[0012] Fifth step: simultaneously start the pre-pump system and the auxiliary steam system, then start the condensate system, then start the shaft seal system, and finally start the vacuum system and switch the small circulation pump to the large circulation pump in sequence.

[0013] Step 6: First, start the relevant systems and equipment of Unit 1, and start the water supply to the low-pressure steam drum of Unit 1;

[0014] Step 7: Simultaneously start the water supply to the intermediate-pressure steam drum of Unit 1 and the water supply to the high-pressure steam drum of Unit 1.

[0015] Step 8: The operator clicks "APS Start Unit 1 Gas Turbine";

[0016] Step 9: Simultaneously start the low-pressure and high-pressure circulation of Unit 1 boiler, the low-pressure steam system of Unit 1 boiler, the medium-pressure system of Unit 1 boiler, the reheat system of Unit 1 boiler, and the high-pressure system of Unit 1 boiler.

[0017] Step 10: Simultaneously start the low-pressure system steam connection valve of Unit 1 boiler, start the intermediate-pressure system steam connection valve of Unit 1 boiler, start the high-pressure system steam connection valve of Unit 1 boiler, then start the high-pressure, medium-pressure and low-pressure system steam connection function of Unit 1 boiler, and start the turbine start-up and generator unit grid connection.

[0018] Step 11: Unit 1 starts its load ramp-up function;

[0019] Step 12: Restart the relevant systems and equipment of Unit 2, and start the water supply to the low-pressure steam drum of Unit 2;

[0020] Step 13: Simultaneously start the water supply to the intermediate pressure steam drum of Unit 2 and the water supply to the high pressure steam drum of Unit 2.

[0021] Step 14: The operator clicks "APS Start Unit 2 Gas Turbine";

[0022] Step 15: Simultaneously start the low-pressure and high-pressure circulation of Unit 2 boiler, the low-pressure steam system of Unit 2 boiler, the medium-pressure system of Unit 2 boiler, the reheat system of Unit 2 boiler, and the high-pressure system of Unit 2 boiler.

[0023] Step 16: Simultaneously start the steam connection valves of the low-pressure system, the intermediate-pressure system, and the high-pressure system of Unit 2 boilers, and then start the steam connection function of the high-pressure, medium-pressure, and low-pressure systems of Unit 2 boilers.

[0024] Step 17: Unit 2 starts its load ramp-up function;

[0025] Step 18: The load of the two-to-one gas-steam combined cycle unit continues to increase and meets the grid dispatch requirements.

[0026] A further improvement of the present invention is that the method first ensures that cold steam does not flow into the steam turbine.

[0027] A further improvement of the present invention is that the method pre-sets the temperature difference between the two start-up boilers to meet the start-up allowable conditions.

[0028] A further improvement of this invention is that the method incorporates the condensate temperature before and after the valve during steam connection into the judgment of the start-up allowable conditions, thereby ensuring the safety of the steam connection process.

[0029] A further improvement of this invention lies in the specific control strategy for the simultaneous steam connection process of high-pressure and medium-pressure units, which includes: Unit 2 successfully connects to the grid; the unit load increases to the target steam connection load; the load of the starting boilers is controlled to be the same as the steam connection load; when the load deviation of the two starting boilers is set to not exceed the set power, the turbine operation non-bypass control mode switches from minimum pressure control to steam connection control mode; when the pressure ratio of the two starting boilers is not less than the set value, the automatic steam connection control program is initiated; after both high-pressure and medium-pressure steam connection valves are fully open, the turbine bypass is adjusted and controlled according to the steam connection valve status; the high-pressure and medium-pressure bypasses are simultaneously closed; the cold reheat valve is automatically opened according to the setting; the turbine pressure control system controls the opening of each valve to ensure pressure stability; this state is the unit steam connection state; when the turbine high-pressure and medium-pressure bypasses are fully closed, and the cold reheat valves of the two starting boilers are fully open, the steam connection control program is completed.

[0030] A further improvement of this invention is that the load deviation between the two start-up boilers must not exceed 15MW.

[0031] A further improvement of the present invention is that the pressure of the two boilers waiting to start is not less than 0.05 MPa compared with the pressure of the main pipe.

[0032] The present invention has at least the following beneficial technical effects:

[0033] This invention provides a multi-stage parallel start-up control method for a two-to-one gas-steam combined cycle unit. This invention enables the simultaneous and parallel start-up of various systems and equipment functional groups during the start-up process of the two-to-one gas-steam combined cycle unit, optimizing the steam-steam start-up control mode. This ensures that there is no risk to the safety of the unit when the two start-up boilers are connected, achieving the goal of full-process automated control and realizing the efficient start-up of the two-to-one gas-steam combined cycle unit. Attached Figure Description

[0034] Figure 1This is a flowchart of a multi-stage parallel start-up control method for a two-to-one gas-steam combined cycle unit according to the present invention.

[0035] Figure 2 This is a schematic diagram illustrating the application of an embodiment of the present invention.

[0036] Figure 3 This is a rendering of an embodiment of the present invention. Detailed Implementation

[0037] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] This invention provides a multi-stage parallel start-up control method for a two-to-one gas-steam combined cycle unit. It further enriches the energy-saving space by finding the parallel operation space of each system equipment, and implements the most energy-saving and time-saving control method throughout the entire operation process. It makes full use of the start-up allowable release space of the two gas turbines, two waste heat boilers and various auxiliary systems, and breaks away from the traditional control method that requires starting one by one according to the design requirements, so as to realize the efficient start-up and operation of the two-to-one gas-steam combined cycle unit.

[0039] like Figure 1 As shown, the present invention provides a multi-stage parallel start-up control method for a two-to-one gas-steam combined cycle unit, comprising the following steps:

[0040] The first step is for the operator to manually click to confirm the "Multi-stage parallel start-up control of two-to-one gas-steam combined cycle units" function;

[0041] The second step is to simultaneously start the circulating water system and the demineralized water system.

[0042] The third step is to simultaneously start both the open water system and the closed water system.

[0043] Fourth step: Simultaneously start the air compressor switching and start the boiler;

[0044] Fifth step: simultaneously start the pre-pump system and the auxiliary steam system, then start the condensate system, then start the shaft seal system, and finally start the vacuum system and switch the small circulation pump to the large circulation pump in sequence.

[0045] Step 6: First, start the relevant systems and equipment of Unit 1, and start the water supply to the low-pressure steam drum of Unit 1;

[0046] Step 7: Simultaneously start the water supply to the intermediate-pressure steam drum of Unit 1 and the water supply to the high-pressure steam drum of Unit 1.

[0047] Step 8: The operator clicks "APS Start Unit 1 Gas Turbine";

[0048] Step 9: Simultaneously start the low-pressure and high-pressure circulation of Unit 1 boiler, the low-pressure steam system of Unit 1 boiler, the medium-pressure system of Unit 1 boiler, the reheat system of Unit 1 boiler, and the high-pressure system of Unit 1 boiler.

[0049] Step 10: Simultaneously start the low-pressure system steam connection valve of Unit 1 boiler, start the intermediate-pressure system steam connection valve of Unit 1 boiler, start the high-pressure system steam connection valve of Unit 1 boiler, then start the high-pressure, medium-pressure and low-pressure system steam connection function of Unit 1 boiler, and start the turbine start-up and generator unit grid connection.

[0050] Step 11: Unit 1 starts its load ramp-up function;

[0051] Step 12: Restart the relevant systems and equipment of Unit 2, and start the water supply to the low-pressure steam drum of Unit 2;

[0052] Step 13: Simultaneously start the water supply to the intermediate pressure steam drum of Unit 2 and the water supply to the high pressure steam drum of Unit 2.

[0053] Step 14: The operator clicks "APS Start Unit 2 Gas Turbine";

[0054] Step 15: Simultaneously start the low-pressure and high-pressure circulation of Unit 2 boiler, the low-pressure steam system of Unit 2 boiler, the medium-pressure system of Unit 2 boiler, the reheat system of Unit 2 boiler, and the high-pressure system of Unit 2 boiler.

[0055] Step 16: Simultaneously start the steam connection valves of the low-pressure system, the intermediate-pressure system, and the high-pressure system of Unit 2 boilers, and then start the steam connection function of the high-pressure, medium-pressure, and low-pressure systems of Unit 2 boilers.

[0056] Step 17: Unit 2 starts its load ramp-up function;

[0057] Step 18: The load of the two-to-one gas-steam combined cycle unit continues to increase and meets the grid dispatch requirements.

[0058] This invention requires a comprehensive understanding of the control strategies and methods when two-to-one gas-steam combined cycle units are connected to the steam turbine. First, it is necessary to ensure that cold steam does not flow into the steam turbine. The temperature deviation between the two start-up boilers is set in advance to meet the start-up allowable conditions. The condensate temperature before and after the valve is added to the judgment of the start-up allowable conditions to achieve safety in the connection process.

[0059] The specific control strategy for the simultaneous high-pressure and medium-pressure steam connection process includes: Unit 2 successfully connects to the grid; the unit load increases to the target steam connection load; the load of the starting boilers is controlled to be the same as the steam connection load; when the load deviation between the two starting boilers is set to not exceed 15MW, the turbine operation non-bypass control mode switches from minimum pressure control to steam connection control mode; when the pressure ratio of the two starting boilers is not less than 0.05MPa compared to the main pipe pressure, the automatic steam connection control program is initiated; after both high-pressure and medium-pressure steam connection valves are fully open, the turbine bypass is adjusted and controlled according to the steam connection valve status; the high-pressure and medium-pressure bypasses are simultaneously closed; the cold reheat valve opens automatically according to the settings; the turbine pressure control system ensures pressure stability and controls the opening of each valve. This state is the unit steam connection state; when the turbine high-pressure and medium-pressure bypasses are fully closed, and the cold reheat valves of the two starting boilers are fully open, the steam connection control program is completed.

[0060] Examples, such as Figure 2 The figure shows the statistics of the application process of this invention, demonstrating the application of this technology in practical engineering. For example... Figure 3 As shown, the temperature of the high-pressure main steam remains stable during the application of this invention.

[0061] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for multi-stage parallel start-up control of a two-on-one gas-steam combined cycle unit, characterized in that, The method comprises the following steps: The method comprises the following steps: Firstly, an operator manually clicks to confirm the "two-by-one gas-steam combined cycle unit multi-stage parallel starting control" function; Secondly, the circulating water system and the desalted water system are started simultaneously; Thirdly, the open water system and the closed water system are started simultaneously; Fourthly, the air compressor switching and the starting boiler are started simultaneously; Fifthly, the pre-pump system and the auxiliary steam system are started, then the condensate water system is started, the shaft seal system is started, and finally the vacuum system and the small circulating pump switching to the large circulating pump are started; Sixthly, the systems and devices related to the first unit are started, and the first unit low-pressure steam drum is filled with water; Seventhly, the first unit medium-pressure steam drum and the first unit high-pressure steam drum are filled with water simultaneously; Eighthly, the operator clicks "APS starts the first unit gas turbine"; Ninthly, the first unit low-pressure circulating system, the first unit low-pressure steam system, the first unit medium-pressure system, the first unit reheating system, and the first unit high-pressure system are started simultaneously; Tenthly, the first unit low-pressure system, the first unit medium-pressure system, and the first unit high-pressure system are started, and the turbine is started, the generator is connected to the grid, and the load is increased; Eleventhly, the second unit systems and devices are started, and the second unit low-pressure steam drum is filled with water; Twelfthly, the second unit medium-pressure steam drum and the second unit high-pressure steam drum are filled with water simultaneously; Thirteenthly, the operator clicks "APS starts the second unit gas turbine"; Fourteenthly, the second unit low-pressure circulating system, the second unit low-pressure steam system, the second unit medium-pressure system, the second unit reheating system, and the second unit high-pressure system are started simultaneously; Fifteenthly, the second unit low-pressure system, the second unit medium-pressure system, and the second unit high-pressure system are started; Sixteenthly, the second unit low-pressure system, the second unit medium-pressure system, and the second unit high-pressure system are started; Seventeenthly, the load of the two-by-one gas-steam combined cycle unit is continuously increased to meet the power grid scheduling requirements. The method first ensures that cold steam does not flow into the steam turbine.

2. The multi-stage parallel starting control method for a two-on-one gas-steam combined cycle unit according to claim 1, characterized in that, The method pre-sets the temperature deviation of the two starting boilers to meet the starting allowance conditions.

3. The multi-stage parallel starting control method for a two-on-one gas-steam combined cycle unit according to claim 1, characterized in that, The method adds the pre-and post-steam gate drain temperature to the starting allowance conditions to ensure the safety of the steam gate process.

4. The multi-stage parallel starting control method for a two-on-one gas-steam combined cycle unit according to claim 3, characterized in that, ​ 5. The method according to claim 1, wherein, The specific control strategy of the high pressure and medium pressure simultaneous parallel steam process includes: the unit 2 is completed and connected to the grid, the unit load is increased to the target parallel steam load, the control operation starting boiler load is the same as the parallel steam load, the setting operation two starting boiler load deviation cannot exceed the setting power, the turbine operation is not bypass control mode from the minimum pressure control to the parallel steam control mode, waiting for the parallel steam control program to be started when the two starting boilers' pressure is not less than the setting value of the mother pipe pressure, the high pressure and medium pressure parallel steam valves are opened and need to be fully opened, the turbine bypass is adjusted and controlled in the parallel steam valve state, the high and medium bypass is closed synchronously, the cold re-adjusting valve is automatically opened according to the setting, the turbine pressure control is to ensure the pressure stability and control the opening of each valve, this state is the unit parallel steam state, waiting for the high pressure and medium pressure bypass of the turbine to be fully closed and the two starting boilers' cold re-adjusting valves to be fully opened, then the parallel steam control program is completed.

6. The multi-stage parallel starting control method for a two-on-one gas-steam combined cycle unit according to claim 5, characterized in that, The setting operation two starting boiler load deviation cannot exceed 15 MW.

7. The multi-stage parallel starting control method for a two-on-one gas-steam combined cycle unit according to claim 5, characterized in that, Waiting for the two starting boilers' pressure to be not less than 0.05 MPa of the mother pipe pressure.

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