An optimization method and device for unit hot start and a storage medium

Abstract

This invention discloses an optimized method, device, and storage medium for hot start-up of a power unit, relating to the field of power energy conservation technology. To address the technical problems of long hot start-up time and high fuel consumption in existing technologies, the method includes the following aspects: starting the gas turbine to 3000 rpm, then increasing the load to 135 MW at 20 MW / min after grid connection, taking 38 minutes; maintaining the gas turbine at 135 MW, while the boiler begins to heat and pressurize until the main steam parameters reach the turbine's required start-up parameters, taking 10-15 minutes; starting the turbine at 3000 rpm, with the turbine start-up steam temperature referenced at a mismatch greater than 10°C, and increasing the load at 7 MW / min after grid connection, taking 12 minutes; maintaining the gas turbine load at 135 MW, and opening the turbine control valve at 15% / min to full opening; ensuring that all unit parameters and adjustment operations meet safety standards, shortening the combined cycle's low thermal efficiency operating time, allowing the power plant more high-load power generation time, reducing energy consumption, and improving economic efficiency.

Description

Technical Field

[0001] This invention relates to the field of power energy conservation technology, and in particular to an optimized method, apparatus and storage medium for hot start-up of generating units. Background Technology

[0002] A gas turbine-steam combined cycle (GTCB) generator set is a cycle system composed of a gas turbine, a generator, a waste heat boiler, and a steam turbine. It's a combined system that recovers the high-temperature flue gas discharged from the gas turbine after it has generated electricity, converts it into steam through a waste heat boiler, and then feeds it into the steam turbine for power generation. GTCBs offer advantages such as high thermal efficiency, clean and environmentally friendly operation, and rapid start-up and shutdown. Compared to high efficiency and low emissions, rapid start-up and shutdown determine that GTCBs primarily play a peak-shaving role in the power grid. Day-on-night operation is a common mode, and how to achieve rapid and safe startup in the shortest possible time is a key area of ​​exploration and improvement for every gas turbine power plant.

[0003] Hot start-up, as the main start-up method for units that start during the day and stop at night, involves a high gas turbine load (around 130MW) and full expansion of the turbine cylinder. Studying the hot start-up process, optimizing the hot start-up process, and shortening the hot start-up time can effectively reduce fuel waste, allow power plants to generate more power at high loads, and improve the economic efficiency of power plants.

[0004] In the first year of operation of the first phase of the project, the plant's units started and stopped 212 times. The hot start time of the units was between 90 and 130 minutes, which was slightly higher than the scheduling requirement of 90 minutes. Therefore, efforts were made to reduce the hot start time of the units, reduce energy consumption, and improve economic efficiency. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems of long hot start-up time and high fuel consumption in the prior art. Moreover, the heat of the gas turbine exhaust is lost in the circulating water of the condenser through the turbine bypass for a long time, which causes a certain degree of waste. The purpose is to explore a suitable hot start-up method for the unit under the condition that the various parameters of the unit and the adjustment operation meet the safety specifications, which can effectively reduce the time, reduce energy consumption and improve economic efficiency.

[0006] An optimized method for hot start-up of a power unit includes increasing the load of the gas turbine by 20 MW / min and the steam turbine by 7 MW / min. The steam turbine is started when the steam temperature before bypass is measured with reference to a mismatch degree greater than 10℃.

[0007] An optimized method for hot start-up of a generating unit includes hot start-up, which encompasses the process from gas turbine startup to the unit's AGC (Automatic Generative Control) activation, and includes the following specific steps:

[0008] S1: The gas turbine starts at 3000 rpm, and the gas turbine is connected to the grid and the load is increased to 135 MW at 20 MW / min. The whole process takes 38 minutes.

[0009] S2: The gas turbine maintains 135MW, and the boiler begins to heat up and pressurize until the main steam parameters reach the turbine's required start-up parameters. The entire process takes 10-15 minutes.

[0010] S3: The turbine is started at 3000 rpm. The steam temperature for turbine start-up is referenced by the measuring point before the bypass and the start-up is based on a mismatch of more than 10℃. The turbine is connected to the grid at a load increase of 7MW / min. The whole process takes 12 minutes.

[0011] S4: The gas turbine load is maintained at 135MW, and the steam turbine control valve position command is from 15% / min to fully open;

[0012] S5: After the unit is connected to the grid, the total load increases from 200MW to 270MW. The turbine control valve is put into pressure control, and the unit is put into CCS and AGC.

[0013] In a further preferred embodiment of the present invention, in the above steps, the gas turbine has a maximum load increase rate limit, the boiler increases its load at the maximum load increase rate, and the maximum load increase rate of the steam turbine is determined by the blade strength.

[0014] In a further preferred embodiment of the present invention, the gas turbine is started up to 3000 rpm, and the gas turbine is connected to the grid and the load is increased to 135 MW at a rate of 20 MW / min, with the entire process taking 38 minutes.

[0015] In a further preferred embodiment of the present invention, in step S2 above, the boiler begins to heat up and pressurize until the main steam parameters reach the turbine's required start-up parameters, and the entire process takes 10-15 minutes.

[0016] In a further preferred embodiment of the present invention, in step S3 above, the turbine is started to 3000 rpm, the steam temperature of the turbine is referenced by the measuring point before the bypass and the turbine starts to start with a mismatch degree greater than 10°C, the turbine is connected to the grid at a load increase of 7 MW / min, and the whole process takes 12 minutes.

[0017] In a further preferred embodiment of the present invention, in step S3 above, when the unit is started, the steam inlet mismatch of the turbine is sequentially set at 40°C, 30°C, 20°C, 10°C and 0°C to start the turbine, based on the premise that the turbine expansion difference, axial displacement and vibration parameters are within a safe range.

[0018] In a further preferred embodiment of the present invention, when the unit is shut down, the gas turbine is shut down sequentially according to the loads of 140MW, 130MW, 120MW, 110MW, and 100MW, based on the premise that the turbine expansion difference, axial displacement, and vibration parameters are within a safe range.

[0019] A further preferred embodiment of the present invention includes, when the unit is shut down, reducing the load of the gas turbine to 120MW first, and then reducing it to 100MW after 5 minutes to shut down the steam turbine, in order to reduce the turbine shutdown cylinder temperature.

[0020] An optimization device for hot start of a generating unit includes a processor containing a computer-executable program that can implement any of the above-described optimization methods for hot start of a generating unit.

[0021] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the optimized method for hot start-up of a unit as described above.

[0022] The beneficial effects of this invention are as follows: By determining that the gas turbine load is increased at 20MW / min and the steam turbine load is increased at 7MW / min, based on the steam turbine expansion differential, axial displacement, and vibration parameters being within safe ranges, and increasing the maximum power within the safe range, this invention ensures the rapid operation and reliable safety of the entire system. It effectively avoids affecting the safety of the operating unit, controls the stress changes on the inner wall of the steam turbine expansion differential, and increases the boiler temperature and pressure to meet the turbine start-up parameter requirements before hot-starting the turbine to connect to the grid and carry the load. Compared with the prior art, this application ensures that the parameter requirements and adjustment operations of the unit meet safety standards. At the same time, it shortens the low thermal efficiency operation time of the combined cycle, allowing the power plant more high-load power generation time, reducing energy consumption, improving economic efficiency, and enhancing the economics of the power plant. Finally, during the boiler shutdown phase, the gas turbine load is first reduced to 120MW, and then reduced to 100MW after 5 minutes to shut down the steam turbine, thereby reducing the turbine shutdown cylinder temperature. The steam temperature for turbine start-up is referenced by the measurement point before bypass, and start-up begins when the mismatch is greater than 10℃. Implementation

[0023] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in conjunction with the description.

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, not all embodiments. All features disclosed in this specification, or steps in all disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

[0025] Therefore, the following detailed description of embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0027] The common practice in existing technologies is as follows:

[0028] If the gas turbine load is increased at 15MW / min, and the difference between the flue gas temperature at the waste heat boiler inlet and the main steam temperature is greater than 50℃, the load increase should be temporarily suspended until the steam temperature rises before continuing to increase the load.

[0029] When the gas turbine is shut down, the load is reduced to 135MW and maintained. The steam turbine starts to close the main control valve to reduce the load. After the steam turbine is shut down, the cylinder temperature is close to the rated temperature. When it is started the next day, the steam turbine cylinder temperature is 520℃.

[0030] The steam turbine is started when the inlet steam temperature is at least 50°C higher than the cylinder temperature (if it is higher than the rated temperature, the rated temperature is used). After grid connection, the load is increased to 3MW / min until the control valve is fully open.

[0031] This is a relatively conventional and safe approach. However, this approach does not take full advantage of the gas-steam combined cycle unit. The entire hot start-up time is generally between 90 and 130 minutes. Therefore, under the premise of fully ensuring the safety of the unit, the applicant has optimized the hot start-up process of the unit and proposed Implementation Case 1.

[0032] Implementation Case 1: An optimized method for unit hot start-up, including hot start-up from gas turbine startup to unit AGC activation, comprising the following specific steps:

[0033] S1: The gas turbine starts at 3000 rpm, and the gas turbine is connected to the grid and the load is increased to 135 MW at 20 MW / min. The whole process takes 38 minutes.

[0034] S2: The gas turbine maintains 135MW, and the boiler begins to heat up and pressurize until the main steam parameters reach the turbine's required start-up parameters. The entire process takes 10-15 minutes.

[0035] S3: The turbine is started at 3000 rpm. The steam temperature for turbine start-up is referenced by the measuring point before the bypass and the start-up is based on a mismatch of more than 10℃. The turbine is connected to the grid at a load increase of 7MW / min. The whole process takes 12 minutes.

[0036] S4: The gas turbine load is maintained at 135MW, and the steam turbine control valve position command is from 15% / min to fully open;

[0037] S5: After the unit is connected to the grid, the total load increases from 200MW to 270MW. The turbine control valve is put into pressure control, and the unit is put into CCS and AGC.

[0038] The entire unit startup time is between 66 and 75 minutes. Before optimization, the boiler heating and pressurization stage took a relatively long time, about 35 minutes. At this time, the gas turbine was carrying a 135MW load, and all the flue gas heat was lost to the atmosphere through the circulating water. The gas turbine's natural gas flow rate at this time was approximately 42,000 Nm³. 3 / h, with a cycle thermal efficiency of 30%, the average time saved after hot start-up optimization is 20 minutes; the additional power generation after optimization is (270-135) MW×20min÷60min=45MW·h; the additional natural gas consumption is (49500-42000) Nm³. 3 / h×20min÷60min=2500Nm 3 Based on a natural gas price of 2.2 yuan / Nm3 and an electricity price of 0.56 yuan / kW·h, the economic benefit generated is: 45×1000×0.56-2500×2.2=19,700 yuan / time.

[0039] Implementation Case 2: An optimized method for hot start-up of a generating unit, including the following specific steps:

[0040] S1: The gas turbine starts at 3000 rpm, and the gas turbine is connected to the grid and the load is increased to 135 MW at 20 MW / min. The whole process takes 38 minutes.

[0041] S2: The gas turbine maintains 135MW. When the steam temperature at the outlet of the superheater and reheater is greater than the steam inlet requirements of the high-pressure cylinder and the intermediate and low-pressure cylinder of the turbine and is 10℃ lower than the steam inlet temperature of the high-pressure cylinder of the turbine, the high-pressure cylinder and the intermediate and low-pressure cylinder of the turbine start to accelerate. The whole process takes 10-15 minutes.

[0042] S3: The turbine is brought to 3000 rpm, and the turbine is connected to the grid at a load increase of 7 MW / min. The entire process takes 12 minutes.

[0043] S4: The gas turbine load is maintained at 135MW. The high-pressure cylinder and the medium- and low-pressure cylinder of the steam turbine are increased at 6MW / min until the high-pressure main control valve and the medium-pressure main control valve are fully open. At the same time, the opening of the high-pressure bypass valve and the medium-pressure bypass valve is gradually reduced. After the high-pressure bypass valve and the medium-pressure bypass valve are fully closed;

[0044] S5: The gas turbine continues to increase to full load at 20MW / min. After the unit is connected to the grid, the total load increases from 200MW to 270MW. The turbine control valve is put into pressure control, and the unit is put into CCS and AGC.

[0045] S6: When the unit is shut down, the gas turbine load is first reduced to 120MW, and then reduced to 100MW after 5 minutes to shut down the steam turbine, in order to reduce the turbine cylinder temperature during shutdown.

[0046] Implementation Case 3: Further extending the above implementation case, in the above steps, the gas turbine has a maximum load increase rate limit, the boiler increases the load at the maximum load increase rate, and the maximum load increase rate of the steam turbine is determined by the blade strength.

[0047] Implementation Case 4:

[0048] S1: The gas turbine starts using TCS sequential control. Fuel and air enter the gas turbine for combustion, producing high-temperature and high-pressure flue gas. The flue gas does work inside the gas turbine. Before the gas turbine generator is connected to the grid, part of the energy of the flue gas is converted into mechanical energy to drive the gas turbine to increase its speed. The flue gas that has done work enters the waste heat boiler to heat the feedwater and steam. After heat exchange, the flue gas is finally discharged into the atmosphere. The gas turbine speed reaches 3000 rpm. The gas turbine starts at 3000 rpm and is connected to the grid. The load is increased to 135 MW at 20 MW / min. The whole process takes 38 minutes.

[0049] S2: The gas turbine maintains 135MW, and the boiler begins to heat up and pressurize until the main steam parameters reach the turbine's required start-up parameters. The entire process takes 10-15 minutes.

[0050] S3: The turbine is started up at a fixed rate of 3000 rpm. The steam temperature for turbine start-up is referenced by the measuring point before the bypass and the start-up is based on a mismatch of more than 10℃. The turbine is connected to the grid at a load increase of 7MW / min. The whole process takes 12 minutes.

[0051] S4: The gas turbine load is maintained at 135MW, and the steam turbine control valve position command is from 15% / min to fully open;

[0052] S5: After the unit is connected to the grid, the total load increases from 200MW to 270MW. The turbine control valve is put into pressure control, and the unit is put into CCS and AGC.

[0053] S6: When the unit is shut down, the gas turbine is shut down in sequence according to the load of 140MW, 130MW, 120MW, 110MW and 100MW. Based on the fact that the turbine expansion difference, axial displacement and vibration parameters are within the safe range, the appropriate configuration parameters are adjusted.

[0054] Implementation Case 5: An optimization device for hot start of a generating unit, comprising a processor containing a computer-executable program that can implement any of the above-described optimization methods for hot start of a generating unit.

[0055] Implementation Case Six: A computer-readable storage medium storing a computer program that, when executed by a processor, implements the optimized method for hot start-up of a unit as described above.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An optimized method for hot start-up of a generating unit, characterized in that, The gas turbine is increased to a load of 20 MW / min, and the steam turbine is increased to a load of 7 MW / min. The steam turbine start-up steam temperature is referenced at the pre-bypass measuring point, and start-up begins when the mismatch degree is greater than 10℃. The hot start-up procedure, from gas turbine start-up to unit AGC, includes the following specific steps: S1: The gas turbine starts at 3000 rpm, and when the gas turbine is connected to the grid, the load is increased to 135 MW at a rate of 20 MW / min; S2: The gas turbine maintains 135MW, and the boiler begins to heat up and pressurize until the main steam parameters reach the turbine's required start-up parameters; S3: The turbine is started at 3000 rpm. The steam temperature for turbine start-up is referenced by the measurement point before the bypass and the start-up is based on a mismatch greater than 10℃. The turbine is connected to the grid at a load increase of 7MW / min. During unit startup, the turbine inlet steam mismatch is sequentially set at 40℃, 30℃, 20℃, 10℃, and 0℃, based on the turbine expansion difference, axial displacement, and vibration parameters being within safe ranges. During unit shutdown, the gas turbine is sequentially shut down at loads of 140MW, 130MW, 120MW, 110MW, and 100MW, based on the turbine expansion difference, axial displacement, and vibration parameters being within safe ranges. S4: The gas turbine load is maintained at 135MW, and the steam turbine control valve position command is from 15% / min to fully open; S5: After the unit is connected to the grid, the total load increases from 200MW to 270MW. The turbine control valve is put into pressure control, and the unit is put into CCS and AGC.

2. The optimized method for hot start-up of a unit according to claim 1, characterized in that, In step S1 above, the gas turbine starts at 3000 rpm, and the gas turbine is connected to the grid and the load is increased to 135 MW at 20 MW / min. The whole process takes 38 minutes.

3. The optimized method for hot start-up of a unit according to claim 1, characterized in that, In step S2 above, the boiler begins to heat up and pressurize until the main steam parameters reach the turbine's required start-up parameters, which takes 10 to 15 minutes.

4. The optimized method for hot start-up of a unit according to claim 1, characterized in that, In step S3 above, the turbine is started up to 3000 rpm. The steam temperature of the turbine is referenced by the measuring point before the bypass and the turbine starts up when the mismatch is greater than 10℃. The turbine is connected to the grid and the load is increased at 7MW / min. The whole process takes 12 minutes.

5. The optimized method for hot start-up of a generating unit according to claim 1, characterized in that, It also includes a unit shutdown and cooling process, which involves reducing the gas turbine load to 120MW when the unit is shut down, and then reducing it to 100MW after 5 minutes to shut down the steam turbine, in order to reduce the turbine shutdown cylinder temperature.

6. An optimization device for hot start of a generator unit, comprising a processor, wherein the processor contains a computer-executable program, characterized in that, The program can implement the optimized method for hot start-up of a unit as described in any one of claims 1 to 5.

7. A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, it is characterized in that, An optimized method for hot start-up of a generating unit as described in any one of claims 1 to 5.