Method and system for starting steam turbine of IGCC (integrated gasification combined cycle) unit gas turbine under synthesis gas working condition

Abstract

The invention provides a method and a system for starting a steam turbine of a gas turbine of an IGCC (integrated gasification combined cycle) unit under a synthetic gas working condition, which comprises the following steps: starting the gas turbine under a fuel working condition, and grid-connecting at a preset rotating speed of the gas turbine; increasing the load of the gas turbine to a switching load, and switching the gas turbine to a synthesis gas working condition for operation; the turbine exhaust gas temperature and the flue gas flow of the gas turbine are reduced, so that the main steam parameter reaches the rated impulse rotation parameter of the steam turbine; the steam turbine executes a running operation, and grid connection is carried out at a preset steam turbine rotating speed; the load of the gas turbine is increased, and the steam turbine is warmed up; the fuel working condition operation time of the gas turbine is shortened, the gas turbine is switched to the synthesis gas working condition mode as soon as possible, fuel consumption is reduced, waste caused by the fact that synthesis gas produced by a gasification furnace is diffused to a torch for combustion at the initial starting stage is avoided, meanwhile, the NOX standard-exceeding emission time is shortened, the starting cost is saved, and the starting efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of IGCC (integrated gasification combined cycle power generation system) gas turbine-steam turbine combined cycle power generation, and in particular to a method and system for starting a steam turbine of an IGCC unit gas turbine under syngas working conditions. Background Art

[0002] Before switching to the syngas operating condition, the power part of the IGCC unit is started in a similar way to other gas turbine units. Ignition gas (propane) is introduced into the left and right combustion chambers to ignite No. 0 diesel to provide heat energy for the gas turbine. The gas turbine continues to increase its speed to the grid-connected speed. After the operator confirms the grid-connected operation, the gas turbine generator is automatically connected to the grid at the same time. The hot flue gas at the tail of the gas turbine enters the waste heat boiler to provide a heat source for the waste heat boiler. During the unit startup process, the temperature and pressure increase rate of the boiler heating surface is controlled to ensure safe operation. After the main steam parameters meet the requirements, the main steam is led to the front of the steam turbine to perform turbine run-up, warm-up, and grid-connected operations. After the steam turbine is connected to the grid, continue to increase the gas turbine load to 70% of the rated load. After the syngas parameters produced by the gasifier meet the switching conditions, the gas turbine is switched from fuel oil operation to syngas operation. However, the overall startup time from the ignition of the self-ignition engine to the operation of the synthesis gas condition is about 300 minutes. This startup method consumes a lot of fuel during the unit ignition startup and low-load combustion stage, which seriously hinders the improvement of the unit efficiency. The combustion mode of the SGT5-2000EX (LC) type gas engine of the IGCC unit is diffusion combustion, with high flame temperature and NO under fuel condition. X A large amount of output will be released.

[0003] In view of this, the present invention proposes a method and system for starting a gas turbine of an IGCC unit under syngas working conditions, which shortens the fuel working condition operation time of the gas turbine and switches to the syngas working mode as early as possible, reduces fuel consumption, avoids the waste of syngas output from the gasifier being released to the flare in the initial start-up period, and shortens NO X The time of excessive emission is reduced, which saves startup cost and improves startup efficiency. Summary of the invention

[0004] The object of the present invention is to provide a method for starting a gas turbine of an IGCC unit under syngas conditions, comprising: starting the gas turbine under fuel oil conditions and connecting to the grid at a preset gas turbine speed; increasing the load of the gas turbine to a switching load, and switching the gas turbine to syngas conditions; reducing the turbine exhaust temperature and flue gas flow of the gas turbine so that the main steam parameters reach the rated start-up parameters of the turbine; the steam turbine performs a start-up operation and connects to the grid at a preset turbine speed; increasing the load of the gas turbine and warming up the steam turbine.

[0005] Furthermore, the preset engine speed is 3000 rpm.

[0006] Furthermore, the gas turbine comprises a left combustion chamber and a right combustion chamber; the gas turbine is started under fuel working condition by introducing fire into the left and right combustion chambers to ignite the diesel.

[0007] Furthermore, the preset turbine speed is 3000 rpm.

[0008] Furthermore, the reducing the turbine exhaust temperature and flue gas flow of the gas turbine includes: reducing the load of the gas turbine; and adjusting the opening of the compressor inlet guide vanes when the load of the gas turbine is reduced to a preset stable operating load.

[0009] Furthermore, the preset stable operating load is 70MW; the rated run-up parameters include exhaust temperature, high-pressure main steam pressure, high-pressure main steam temperature, reheat main steam pressure and reheat main steam temperature; the exhaust temperature is 380°C; the high-pressure main steam pressure is 3.08MPa; the high-pressure main steam temperature is 380°C; the reheat main steam pressure is 1MPa; and the reheat main steam temperature is 379°C.

[0010] Furthermore, it also includes: before the gas turbine is switched to the synthesis gas operation mode, saturated steam produced by the gasifier is injected into the synthesis gas.

[0011] Furthermore, it also includes: when the gas turbine is switched to the synthesis gas operation mode, the excess nitrogen produced by the air separation device of the unit is mixed into the synthesis gas.

[0012] Furthermore, it also includes: during the turbine run-up process, reducing the load of the gas turbine to 60MW, reducing the exhaust temperature to 360°C, and extending the turbine's stay time at 2100rpm during the run-up process, so that the turbine can be fully warmed up before continuing to be connected to the grid at the speed of sound.

[0013] The object of the present invention is to provide a system for starting a gas turbine of an IGCC unit under syngas working conditions, comprising a gas turbine starting module, a gas turbine switching module, a main steam parameter adjustment module, a steam turbine starting module and a warm-up module; the gas turbine starting module is used to start the gas turbine under fuel working conditions and connect to the grid at a preset gas turbine speed; the gas turbine switching module is used to increase the load of the gas turbine to the switching load and switch the gas turbine to syngas working conditions; the main steam parameter adjustment module is used to reduce the turbine exhaust temperature and flue gas flow of the gas turbine so that the main steam parameters reach the rated start-up parameters of the steam turbine; the steam turbine starting module is used to perform the start-up operation of the steam turbine and connect to the grid at a preset turbine speed; the warm-up module is used to increase the load of the gas turbine and warm up the steam turbine.

[0014] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

[0015] The present invention can significantly shorten the fuel operation time of the gas turbine after the gas turbine is connected to the grid, reduce the fuel consumption during the startup process, effectively reduce the waste of venting the syngas produced by the gasifier in the initial startup period, and successfully reduce NO X The time of excessive emissions. Under the premise of maintaining the reliability of the unit, the startup cost is effectively reduced by changing the startup mode.

[0016] The present invention saves steam discharged from the gasifier at the initial start-up stage and nitrogen discharged from the air separation system, thereby reducing the switching load of the gas turbine and saving fuel. At the same time, the combustion of the gas turbine is more stable and the means of adjusting the combustion conditions are more diversified. X The time of exceeding the standard was further reduced, and the amount of ammonia injection was reduced; and by adjusting the turbine run-up method, the safe start-up and safe operation of the turbine were guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 An exemplary flow chart of a method for starting a steam turbine of an IGCC unit combustion engine under syngas conditions provided in some embodiments of the present invention;

[0018] Figure 2 An exemplary module diagram of a system for starting a steam turbine of an IGCC unit combustion engine under syngas conditions is provided for some embodiments of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0020] Figure 1 The present invention provides an exemplary flow chart of a method for starting a steam turbine of an IGCC unit under syngas conditions. In some embodiments, process 100 can be performed by system 200. Figure 1 As shown, process 100 may include the following contents:

[0021] Step 110 : The gas turbine is started in fuel oil operation mode and connected to the grid at a preset engine speed. In some embodiments, step 110 may be performed by the gas turbine startup module 210 .

[0022] In some embodiments, the gas turbine includes a left combustion chamber and a right combustion chamber; the gas turbine is started in a fuel oil condition by introducing fire gas into the left and right combustion chambers to ignite the diesel. The preset engine speed may refer to the preset engine speed required for the gas turbine to be connected to the grid. In some embodiments, the preset engine speed is 3000 rpm. The ambient temperature when the unit is started may be greater than or equal to 6°C.

[0023] In some embodiments, it also includes: before the gas turbine is switched to the synthesis gas operation mode, saturated steam produced by the gasifier is injected into the synthesis gas.

[0024] In some embodiments of the present invention, saturated steam is injected into the syngas to reduce the calorific value of the syngas and the proportion of H2 in the syngas. The first purpose is to reduce the proportion of H2, reduce the combustion activity, reduce the risk of flashback during the switching of the syngas working condition, and reduce the switching load of the gas turbine from 70% to 60%; the second purpose is to reduce the NO produced by the tail flue gas during the syngas working condition. X content, which improves the denitrification efficiency and greatly reduces the amount of ammonia injection. Thirdly, it reduces the waste caused by steam venting in the gasifier during the initial startup and recovers this part of heat.

[0025] Step 120 , increasing the load of the gas turbine to the switching load, and switching the gas turbine to the syngas operation mode. In some embodiments, step 120 may be performed by the gas turbine switching module 220 .

[0026] The switching load may refer to the load to be achieved when the gas turbine switches from the fuel operating condition to the synthesis gas operating condition.

[0027] In some embodiments, it also includes: after the gas turbine is switched to the synthesis gas operation mode, the excess nitrogen produced by the air separation device of the unit is mixed into the synthesis gas.

[0028] Some embodiments of the present invention reduce the amount of steam injected into the synthesis gas by utilizing nitrogen, so that this part of steam can be recovered to the medium-pressure drum to perform work in the steam turbine. At the same time, the hum of the combustion chamber of the gas turbine can be suppressed by adjusting the amount of nitrogen injection. Especially during the winter startup process, when the hum is large, the hum of the combustion chamber of the gas turbine can be reduced by adjusting the flow rate of the injected nitrogen (for example, increasing or decreasing the nitrogen content) and adjusting the composition of the synthesis gas.

[0029] In some embodiments, due to the low ambient temperature, after the switching is successful, the hum in the gas turbine combustion chamber is large and close to the alarm value. The hum in the combustion chamber of the gas turbine can be controlled to the optimal value by adjusting the opening of the secondary air valve in the combustion chamber and preferentially adjusting the turbine exhaust temperature. Then, the temperature drop rate of the high-pressure main steam and reheat main steam of the waste heat boiler is used as a benchmark, and the gas turbine load and the turbine exhaust temperature are reduced at the same time.

[0030] Step 130 , reducing the turbine exhaust temperature and flue gas flow rate of the gas turbine so that the main steam parameters reach the rated start-up parameters of the steam turbine. In some embodiments, step 130 may be performed by the main steam parameter adjustment module 230 .

[0031] The rated start-up parameters may refer to the values ​​of the main steam parameters when the steam turbine performs a start-up.

[0032] In some embodiments, the reducing the turbine exhaust temperature and flue gas flow rate of the gas turbine includes: reducing the load of the gas turbine; when the load of the gas turbine is reduced to a preset stable operating load, adjusting the opening of the compressor inlet guide vane. When the rated start-up parameters of the steam turbine are reached or approached under the main steam parameters produced by the waste heat boiler, the steam turbine performs a start-up operation. The preset stable operating load may refer to the minimum load at which the gas turbine can operate stably under syngas conditions.

[0033] In some embodiments, the preset stable operating load is 70MW; the rated run-up parameters include exhaust temperature, high-pressure main steam pressure, high-pressure main steam temperature, reheat main steam pressure and reheat main steam temperature; the exhaust temperature is 380°C; the high-pressure main steam pressure is 3.08MPa; the high-pressure main steam temperature is 380°C; the reheat main steam pressure is 1MPa and the reheat main steam temperature is 379°C.

[0034] In step 140 , the steam turbine performs a start-up operation and is connected to the grid at a preset steam turbine speed. In some embodiments, step 140 may be performed by the steam turbine startup module 240 .

[0035] The preset steam turbine speed may refer to a preset speed required for the steam turbine to be connected to the grid. In some embodiments, the preset steam turbine speed is 3000 rpm.

[0036] In some embodiments, the method further includes: during the turbine run-up process, reducing the load of the gas turbine to 60MW, reducing the exhaust gas temperature to 360°C, and extending the time the turbine stays at 2100rpm during the run-up process, so that the turbine is fully warmed up before continuing to increase the speed and connect to the grid, so as to overcome the situation where the temperature difference between the inner and outer walls of the turbine flange is large due to the increase in the turbine run-up parameters, resulting in startup failure.

[0037] Step 150 , increasing the load of the gas turbine to warm up the steam turbine. In some embodiments, step 150 may be performed by a warm-up module 250 .

[0038] For example, the steam turbine is started up. After the steam turbine is connected to the grid, the steam turbine warm-up rate is controlled, the gas turbine first increases the load to ensure stable combustion in the combustion chamber of the gas turbine, and then increases the load and turbine exhaust temperature to normal load at the same time, and the overall startup of the unit is completed.

[0039] In some embodiments of the present invention, after the gas turbine is connected to the grid, the warm-up operation and the start-up operation of the steam turbine are not performed temporarily, so that the load of the gas turbine can be increased as soon as possible and the gas turbine can be switched to the synthesis gas operation mode.

[0040] Figure 2 An exemplary module diagram of a system for starting a steam turbine of an IGCC unit under syngas conditions is provided for some embodiments of the present invention. Figure 2 As shown, the system 200 may include a gas turbine startup module, a gas turbine switching module, a main steam parameter adjustment module, a steam turbine startup module and a warm-up module.

[0041] The gas turbine startup module 210 is used to start the gas turbine under fuel oil conditions and connect to the grid at a preset engine speed. For more information about the gas turbine startup module 210, see Figure 1 and its related description.

[0042] The gas turbine switching module 220 is used to increase the load of the gas turbine to the switching load and switch the gas turbine to the synthetic gas operation. For more information about the gas turbine switching module 220, see Figure 1 and its related description.

[0043] The main steam parameter adjustment module 230 is used to reduce the turbine exhaust temperature and flue gas flow rate of the gas turbine so that the main steam parameters reach the rated run parameters of the steam turbine. For more information about the main steam parameter adjustment module 230, see Figure 1 and its related description.

[0044] The steam turbine startup module 240 is used to perform a start-up operation on the steam turbine and connect to the grid at a preset steam turbine speed. For more information about the steam turbine startup module 240, see Figure 1 and its related description.

[0045] The warm-up module 250 is used to increase the load of the gas turbine and warm up the steam turbine. For more information about the warm-up module 250, see Figure 1 and its related description.

[0046] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for starting a steam turbine of an IGCC unit under syngas conditions, characterized in that: include: The gas turbine is started under fuel oil condition and connected to the grid at the preset gas turbine speed; Increasing the load of the gas turbine to a switching load, and switching the gas turbine to a synthesis gas operating condition; reducing the turbine exhaust temperature and flue gas flow rate of the gas turbine so that the main steam parameters reach the rated running parameters of the steam turbine; The steam turbine performs a run-up operation and is connected to the grid at a preset steam turbine speed; The load of the gas turbine is increased to warm up the steam turbine.

2. The method for starting a steam turbine of an IGCC unit gas engine under syngas conditions according to claim 1, characterized in that: The preset engine speed is 3000 rpm.

3. The method for starting a steam turbine of an IGCC unit gas engine under syngas conditions according to claim 1, characterized in that: The gas turbine comprises a left combustion chamber and a right combustion chamber. The gas turbine is started under the fuel working condition by introducing fire gas into the left combustion chamber and the right combustion chamber to ignite the diesel.

4. The method for starting a steam turbine of an IGCC unit gas engine under syngas conditions according to claim 1, characterized in that: The preset turbine speed is 3000 rpm.

5. The method for starting a steam turbine of an IGCC unit gas engine under syngas conditions according to claim 1, characterized in that: The step of reducing the turbine exhaust temperature and flue gas flow rate of the gas turbine comprises: reducing a load on the gas turbine; When the load of the gas turbine is reduced to a preset stable operating load, the opening of the compressor inlet guide vanes is adjusted.

6. The method for starting a steam turbine of an IGCC unit gas engine under syngas conditions according to claim 5, characterized in that: The preset stable operating load is 70MW; The rated run-up parameters include exhaust gas temperature, high-pressure main steam pressure, high-pressure main steam temperature, reheat main steam pressure and reheat main steam temperature; The exhaust gas temperature is 380°C; The high-pressure main steam pressure is 3.08MPa; The high-pressure main steam temperature is 380°C; The reheat main steam pressure is 1MPa; The reheated main steam temperature is 379°C.

7. The method for starting a steam turbine of an IGCC unit gas engine under syngas conditions according to claim 1, characterized in that: Also includes: Before the gas turbine is switched to the synthesis gas operation mode, saturated steam produced by the gasifier is injected into the synthesis gas.

8. The method for starting a steam turbine of an IGCC unit gas engine under syngas conditions according to claim 1, characterized in that: Also includes: When the gas turbine is switched to the synthesis gas mode, excess nitrogen produced by the air separation device of the unit is mixed into the synthesis gas.

9. The method for starting a steam turbine of an IGCC unit gas engine under syngas conditions according to claim 1, characterized in that: Also includes: During the turbine run-up, the load of the gas turbine is reduced to 60MW, the exhaust gas temperature is reduced to 360°C, and the time the turbine stays at 2100rpm is extended during the run-up to allow the turbine to be fully warmed up before continuing to be connected to the grid at sonic speed.

10. A system for starting a gas turbine of an IGCC unit under syngas conditions, characterized in that: It includes gas turbine start-up module, gas turbine switching module, main steam parameter adjustment module, steam turbine start-up module and warm-up module; The gas turbine starting module is used to start the gas turbine under fuel oil working conditions and connect to the grid at a preset gas turbine speed; The gas turbine switching module is used to increase the load of the gas turbine to the switching load and switch the gas turbine to the synthesis gas operating state; The main steam parameter adjustment module is used to reduce the turbine exhaust temperature and flue gas flow rate of the gas turbine so that the main steam parameters reach the rated running parameters of the steam turbine; The steam turbine starting module is used for the steam turbine to perform a start-up operation and connect to the grid at a preset steam turbine speed; The warm-up module is used to increase the load of the gas turbine and warm up the steam turbine.

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