CN113202570A - Cold-state starting method and equipment for gas-steam combined cycle unit - Google Patents
Cold-state starting method and equipment for gas-steam combined cycle unit Download PDFInfo
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- CN113202570A CN113202570A CN202110425762.6A CN202110425762A CN113202570A CN 113202570 A CN113202570 A CN 113202570A CN 202110425762 A CN202110425762 A CN 202110425762A CN 113202570 A CN113202570 A CN 113202570A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
- F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
- F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
- F01K23/10—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle with exhaust fluid of one cycle heating the fluid in another cycle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D13/00—Combinations of two or more machines or engines
- F01D13/02—Working-fluid interconnection of machines or engines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
- F01D15/10—Adaptations for driving, or combinations with, electric generators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D17/00—Regulating or controlling by varying flow
- F01D17/10—Final actuators
- F01D17/12—Final actuators arranged in stator parts
- F01D17/14—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits
- F01D17/141—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by means of shiftable members or valves obturating part of the flow path
- F01D17/145—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by means of shiftable members or valves obturating part of the flow path by means of valves, e.g. for steam turbines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K13/00—General layout or general methods of operation of complete plants
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
- F01K13/00—General layout or general methods of operation of complete plants
- F01K13/02—Controlling, e.g. stopping or starting
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/16—Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
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Abstract
The invention discloses a cold-state starting method and equipment of a gas-steam combined cycle unit, wherein the method is applied to the combined cycle unit comprising a steam turbine, a condenser, a steam turbine low-pressure system, a steam turbine medium-pressure system and a steam turbine high-pressure system, and comprises the following steps: when the combined cycle unit starts to vacuumize, opening the middle bypass adjusting valve to a first preset opening degree, opening the high bypass adjusting valve to a second preset opening degree, and closing the low bypass adjusting valve; and when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is greater than the first preset pressure, the low bypass adjusting valve is opened to a third preset opening degree, so that the cold starting time of the gas and steam combined cycle unit is shortened, and the energy consumption is reduced.
Description
Technical Field
The invention relates to the technical field of control of a gas-steam combined cycle unit, in particular to a cold-state starting method and equipment of the gas-steam combined cycle unit.
Background
The survival and development of the power plant depend on the benefit of the power plant, fuel is one of the important costs of the power plant, the benefit of the power plant needs to be improved by saving energy, and meanwhile, compared with a coal-electricity unit, the gas-steam combined cycle unit is more suitable for peak shaving of a power grid, so that the starting times of the unit are relatively more.
At present, during the operation of a vacuum system started by a gas-steam combined cycle unit in a cold state, high, medium and low pressure bypasses need to be opened to a specified opening degree, and the high, medium and low pressure systems of a steam turbine need to be vacuumized. Because the steam side of the gas turbine waste heat boiler flows to the fixed-row flash tank (the continuous-row flash tank flows to the fixed-row flash tank), when the drains of the waste heat boiler pipeline are opened, especially before the boiler pipeline is not opened, the atmosphere is sucked back into the vacuum system through the fixed-row flash tank, so that the vacuum of the system is slowly established, and the vacuum is difficult to stably maintain. Unstable vacuum inevitably causes water level fluctuation of a condenser and a steam drum, particularly a low-pressure system of a steam turbine, the evaporation capacity is relatively small, the pressure starting is slow, the pressure starting can still not be started even a long time after the combustion engine is ignited, and the time from the starting of the combustion engine to the grid connection of the combustion engine is seriously influenced.
Therefore, how to reduce the cold start time of the gas-steam combined cycle unit and reduce the energy consumption is a technical problem to be solved at present.
Disclosure of Invention
The invention provides a cold-state starting method of a gas-steam combined cycle unit, which is used for solving the technical problem that the cold-state starting time of the gas-steam combined cycle unit cannot be reduced in the prior art, and is applied to the combined cycle unit comprising a steam turbine, a condenser, a steam turbine low-pressure system, a steam turbine medium-pressure system and a steam turbine high-pressure system, wherein,
a low bypass regulating valve is arranged between the turbine low-pressure system and the condenser, a middle bypass regulating valve is arranged between the turbine medium-pressure system and the condenser, and a high bypass regulating valve is arranged between the turbine high-pressure system and the condenser, and the method comprises the following steps:
when the combined cycle unit starts to vacuumize, opening the middle bypass adjusting valve to a first preset opening degree, opening the high bypass adjusting valve to a second preset opening degree, and closing the low bypass adjusting valve;
when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is greater than a first preset pressure, opening the low bypass adjusting valve to a third preset opening degree;
when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is not greater than a first preset pressure, the steam of the low-pressure system of the steam turbine is discharged through a low-pressure drain valve.
In some embodiments, the method further comprises:
and when the gas turbine of the combined cycle unit is connected to the grid, increasing the load of the gas turbine to a first preset load.
In some embodiments, the method further comprises:
and when the steam turbine completes grid connection, the load of the gas turbine is increased to a second preset load, and steam compensation parameters of the steam turbine are adjusted according to the opening degrees of the low bypass regulating valve and the middle bypass regulating valve.
In some embodiments, adjusting steam turbine steam supply parameters based on the opening of the low bypass regulator valve and the intermediate bypass regulator valve comprises:
when the pressure before the medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is smaller than a second preset pressure or the medium-pressure steam supplementing valve is closed and the pressure difference between the pressure before the medium-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening of the middle bypass regulating valve;
and when the front pressure of a medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is greater than a third preset pressure, the opening degree of the medium-pressure bypass regulating valve is increased.
In some embodiments, adjusting steam turbine steam supply parameters according to the opening degrees of the low bypass regulating valve and the middle bypass regulating valve further comprises:
when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is smaller than a fourth preset pressure or the low-pressure steam supplementing valve is closed and the pressure difference between the pressure in front of the low-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening degree of the low bypass adjusting valve;
and when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is greater than a fifth preset pressure, improving the opening degree of the low bypass adjusting valve.
Correspondingly, the application also provides cold-state starting equipment of the gas-steam combined cycle unit, which is applied to the combined cycle unit comprising a steam turbine, a condenser, a steam turbine low-pressure system, a steam turbine medium-pressure system and a steam turbine high-pressure system, wherein,
the steam turbine low pressure system with be provided with the other transfer valve of low between the condenser, steam turbine middling pressure system with be provided with the other transfer valve of well between the condenser, steam turbine high pressure system with be provided with the other transfer valve of high between the condenser, equipment includes:
the first adjusting module is used for opening the middle bypass adjusting valve to a first preset opening degree, opening the high bypass adjusting valve to a second preset opening degree and closing the low bypass adjusting valve when the combined cycle unit starts to vacuumize;
the second adjusting module is used for opening the low bypass adjusting valve to a third preset opening degree when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is greater than a first preset pressure;
when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is not greater than a first preset pressure, the steam of the low-pressure system of the steam turbine is discharged through a low-pressure drain valve.
In some embodiments, the apparatus further comprises:
and the third adjusting module is used for increasing the load of the combustion engine to a first preset load when the combustion engine of the combined cycle unit completes grid connection.
In some embodiments, the apparatus further comprises:
and the fourth adjusting module is used for increasing the load of the gas turbine to a second preset load when the steam turbine completes grid connection, and adjusting steam supplement parameters of the steam turbine according to the opening degrees of the low bypass regulating valve and the middle bypass regulating valve.
In some embodiments, the fourth adjusting module is specifically configured to:
when the pressure before the medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is smaller than a second preset pressure or the medium-pressure steam supplementing valve is closed and the pressure difference between the pressure before the medium-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening of the middle bypass regulating valve;
and when the front pressure of a medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is greater than a third preset pressure, the opening degree of the medium-pressure bypass regulating valve is increased.
In some embodiments, the fourth adjusting module is further specifically configured to:
when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is smaller than a fourth preset pressure or the low-pressure steam supplementing valve is closed and the pressure difference between the pressure in front of the low-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening degree of the low bypass adjusting valve;
and when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is greater than a fifth preset pressure, improving the opening degree of the low bypass adjusting valve.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a cold-state starting method and equipment of a gas-steam combined cycle unit, wherein the method is applied to the combined cycle unit comprising a steam turbine, a condenser, a steam turbine low-pressure system, a steam turbine medium-pressure system and a steam turbine high-pressure system, and comprises the following steps: when the combined cycle unit starts to vacuumize, opening the middle bypass adjusting valve to a first preset opening degree, opening the high bypass adjusting valve to a second preset opening degree, and closing the low bypass adjusting valve; and when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is greater than the first preset pressure, the low bypass adjusting valve is opened to a third preset opening degree, so that the cold starting time of the gas and steam combined cycle unit is shortened, and the energy consumption is reduced.
Drawings
FIG. 1 is a schematic structural diagram of a gas-steam combined cycle unit according to an embodiment of the present disclosure;
FIG. 2 is a schematic flow chart of a cold start method of a gas-steam combined cycle unit according to an embodiment of the present disclosure;
FIG. 3 is a schematic flow chart illustrating a cold start-up method of a gas-steam combined cycle plant according to another embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of a cold start-up device of a gas-steam combined cycle unit according to an embodiment of the present application.
Description of the reference symbols
1. The low-pressure steam trap 2, the low-pressure steam supplementing valve 3, the medium-pressure steam supplementing valve 4, the high-pressure steam supplementing valve 5, the steam turbine 6, the low bypass adjusting valve 7, the medium bypass adjusting valve 8, the high bypass adjusting valve 9, the condenser 10, the medium-pressure steam trap 11 and the high-pressure steam trap.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present application.
The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless otherwise specified.
In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.
As described in the background art, in the prior art, when each drain of the waste heat boiler pipe is opened, especially before the boiler pipe is not opened, the atmosphere is sucked back into the vacuum system through the fixed discharge flash tank, so that the vacuum of the system is slowly established, and the vacuum is difficult to stably maintain. Unstable vacuum inevitably causes water level fluctuation of a condenser and a steam drum, particularly a low-pressure system of a steam turbine, the evaporation capacity is relatively small, the pressure starting is slow, the pressure starting can still not be started even a long time after the combustion engine is ignited, and the time from the starting of the combustion engine to the grid connection of the combustion engine is seriously influenced.
In order to solve the above problems, the present application proposes a cold start method of a gas-steam combined cycle plant, as shown in fig. 1, which is applied to a combined cycle plant including a steam turbine 5, a condenser 9, a steam turbine low pressure system, a steam turbine medium pressure system, and a steam turbine high pressure system, wherein,
a low bypass adjusting valve 6 is arranged between the turbine low-pressure system and the condenser, a middle bypass adjusting valve 7 is arranged between the turbine medium-pressure system and the condenser, and a high bypass adjusting valve 8 is arranged between the turbine high-pressure system and the condenser; as shown in fig. 2, the method includes:
s101, when the combined cycle unit starts to vacuumize, the middle bypass adjusting valve is opened to a first preset opening degree, the high bypass adjusting valve is opened to a second preset opening degree, and the low bypass adjusting valve is closed.
In this step, vacuum is one of the important conditions for the normal ignition operation of the combustion engine, and therefore, maintaining the system vacuum is an important operation. Considering that the evaporation capacity of a low-pressure system of a steam turbine is relatively small, the influence on the pressure starting time is the greatest, when the combined cycle unit starts to vacuumize, a middle bypass regulating valve of the medium-pressure system of the steam turbine is opened to a first preset opening degree, a high bypass regulating valve of a high-pressure system of the steam turbine is opened to a second preset opening degree, and a low bypass regulating valve of the low-pressure system of the steam turbine is closed, so that when the combined unit establishes vacuum, the combined unit is not influenced by the low-pressure system of the steam turbine, and the speed and the stability for establishing the vacuum system are improved. Optionally, the first preset opening and the second preset opening may be obtained through experiments, and preferably, the first preset opening is set to 65%, and the second preset opening is set to 75%, and those skilled in the art may also adjust the parameter as needed, which all belong to the protection scope of the present application.
And S102, when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is greater than a first preset pressure, opening the low bypass adjusting valve to a third preset opening degree.
In this step, when the combined cycle unit starts to ignite, the pressure of the turbine low-pressure system starts to be increased, when the pressure of the turbine low-pressure system is greater than the first preset pressure, the low bypass adjusting valve of the turbine low-pressure system is opened to a third preset opening degree at the moment, because the vacuum of the condenser and the turbine high-pressure and medium-pressure systems is established before vacuumizing, and when the pressure of the turbine low-pressure system is determined to be greater than the first preset pressure, the pressure of the low-pressure system is relatively higher, and at the moment, the low bypass adjusting valve is opened to the third preset opening degree, so that the turbine low-pressure system is communicated with the condenser through the low-pressure bypass, the vacuumizing of the turbine low-pressure system can be completed quickly, and the starting time of the combined cycle unit is saved. Optionally, the third preset opening degree may be obtained through experiments, preferably, the third preset opening degree is set to 65%, the first preset pressure may also be set according to specific situations, and generally, the first preset pressure is 0.02-0.03 MPa.
It should be noted that, after the combined cycle unit starts to be vacuumized, the low-pressure drain valve is always in an open state for draining water of the low-pressure system of the steam turbine, the water drainage of the pipeline is ensured to be sufficient, and the water hammer phenomenon does not occur.
To further increase the startup speed of the combined cycle plant, in some embodiments, the method further comprises:
and when the gas turbine of the combined cycle unit is connected to the grid, increasing the load of the gas turbine to a first preset load.
Specifically, the prior gas turbine grid-connected load-increasing operation is conservative, and the load of the gas turbine is increased basically when the main steam temperature of the steam turbine is stable or basically stable. On one hand, the method avoids large thermal shock to the waste heat boiler and the steam turbine pipeline caused by rapid increase of high-pressure steam parameters, and accelerates the damage of the pipeline and equipment. On the other hand, when low load is considered, the gas consumption of the combustion engine is less, and the natural gas consumption of unit starting can be saved. However, the actual operation shows that the steam parameter rises slowly due to the lower load of the combustion engine, and the cold-state starting time is longer, so that more natural gas is consumed. And the load-increasing rate of the gas turbine system has the highest rate limit, under the condition of the load-increasing rate, the gas turbine exhaust temperature rising rate is 10 ℃/min at the fastest, and the intervention of temperature-reducing water is added, so that the actual main steam temperature and pressure change rate is not large, and the situations of temperature rise, pressure rise and overspeed of a waste heat boiler and a steam turbine pipeline can not occur. Meanwhile, the high-temperature components of the steam turbine are inspected during multiple unit overhaul periods, and obvious damage is not found. Therefore, when the gas engine of the combined cycle unit is connected to the grid, the load of the gas engine is directly increased to the first preset load, the cold-state starting time of the combined cycle unit can be reduced under the condition of ensuring the safety of pipelines and equipment, and the gas consumption is saved. Optionally, the first preset load is set to 25 MW.
It should be noted that the above solution of the preferred embodiment is only one specific implementation solution proposed in the present application, and those skilled in the art can set the magnitude of the first preset load as required, which all belong to the protection scope of the present application.
To further reduce the cold start-up time of the combined cycle plant and improve the environmental friendliness of the plant start-up, in some embodiments, the method further comprises:
and when the steam turbine completes grid connection, the load of the gas turbine is increased to a second preset load, and steam compensation parameters of the steam turbine are adjusted according to the opening degrees of the low bypass regulating valve and the middle bypass regulating valve.
Specifically, the combined cycle unit adopts a mode of gradually improving the combustion engine and paying attention to whether the steam supplement condition is met all the time, but the operation needs longer time, in addition, the load of the combustion engine meeting the steam supplement condition does not reach the APCL input condition of the combustion engine, and the NOX emission at the starting stage exceeds the standard. Therefore, when the steam turbine completes grid connection, the load of the gas turbine is increased to a second preset load, the second preset load is the steam supplementing load of the combined cycle unit, preferably, the second preset load is 110MW, and the steam supplementing pressure is adjusted by utilizing the opening degree of the high bypass regulating valve and the middle bypass regulating valve, so that the unit can reach the steam supplementing condition of the steam turbine more quickly, the time from starting the gas turbine to APCL input of the gas turbine is shortened, the NOx standard exceeding emission time is shortened, and the environmental protection property of unit starting is improved.
In order to accurately adjust the steam supplementing parameters of the steam turbine, in some embodiments, the adjusting the steam supplementing parameters of the steam turbine according to the opening degrees of the low bypass regulating valve and the middle bypass regulating valve comprises the following steps:
when the pressure before the medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is smaller than a second preset pressure or the medium-pressure steam supplementing valve is closed and the pressure difference between the pressure before the medium-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening of the middle bypass regulating valve;
and when the front pressure of a medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is greater than a third preset pressure, the opening degree of the medium-pressure bypass regulating valve is increased.
Specifically, the steam supplementing input of the steam turbine matched with the combined cycle unit needs to meet the condition that the pressure before the medium-pressure steam supplementing valve is within the medium-pressure set range, and when the medium-pressure steam supplementing valve is closed, the pressure difference between the pressure before the medium-pressure steam supplementing valve and the pressure at the steam supplementing position is larger than the preset pressure difference, so that when the pressure before the medium-pressure steam supplementing valve of the steam turbine medium-pressure system is smaller than the second preset pressure or the medium-pressure steam supplementing valve is closed and the pressure difference between the pressure before the medium-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than the preset pressure difference, the opening degree of the medium-side regulating valve is reduced, and when the pressure before the medium-pressure steam supplementing valve of the steam turbine medium-pressure system is larger than the third preset pressure, the opening degree of the medium-side regulating valve is increased. Optionally, the second preset pressure is set to 0.3MP, the third preset pressure is set to 1.5MP, and the preset pressure difference is set to 0.05MP, and of course, those skilled in the art may set the second preset pressure, the third preset pressure, and the preset pressure difference to other values as needed, which all belong to the protection scope of the present application.
It should be noted that the solution of the above preferred embodiment is only one specific implementation solution proposed in the present application, and other methods for adjusting the steam compensation parameter of the steam turbine according to the opening degree of the intermediate bypass adjusting valve all belong to the protection scope of the present application.
In order to further accurately adjust the steam supplementing parameter of the steam turbine, in some embodiments, the adjusting the steam supplementing parameter of the steam turbine according to the opening degrees of the low bypass adjusting valve and the middle bypass adjusting valve further comprises:
when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is smaller than a fourth preset pressure or the low-pressure steam supplementing valve is closed and the pressure difference between the pressure in front of the low-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening degree of the low bypass adjusting valve;
and when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is greater than a fifth preset pressure, improving the opening degree of the low bypass adjusting valve.
Specifically, the steam supplementing input of the steam turbine matched with the combined cycle unit needs to meet the condition that the pressure before the low-pressure steam supplementing valve is within a low-pressure set range, when the low-pressure steam supplementing valve is closed, the pressure difference between the pressure before the low-pressure steam supplementing valve and the pressure at the steam supplementing position is larger than a preset pressure difference, when the pressure before the low-pressure steam supplementing valve of the low-pressure steam turbine system is larger than a fifth preset pressure, the opening degree of the low bypass adjusting valve is increased at the moment, and the pressure before the low-pressure steam supplementing valve of the low-pressure steam turbine system can be reduced by increasing the speed of low-pressure bypass steam flowing to the condenser. And when the low-pressure steam supplementing valve front pressure of the steam turbine low-pressure system is smaller than a fourth preset pressure or the low-pressure steam supplementing valve is closed and the pressure difference between the low-pressure steam supplementing valve front pressure and the steam supplementing position pressure is smaller than the preset pressure difference, reducing the opening of the low bypass regulating valve to improve the low-pressure steam supplementing valve front pressure of the steam turbine low-pressure system. Alternatively, the fourth preset pressure may be set to 0.08MP and the fifth preset pressure may be set to 0.4 MP.
It should be noted that the solution of the above preferred embodiment is only one specific implementation solution proposed in the present application, and other methods for adjusting the steam compensation parameter of the steam turbine according to the opening degree of the low bypass adjusting valve all belong to the protection scope of the present application.
The invention discloses a cold-state starting method of a gas and steam combined cycle unit, which is applied to the combined cycle unit comprising a steam turbine, a condenser, a steam turbine low-pressure system, a steam turbine medium-pressure system and a steam turbine high-pressure system, and comprises the following steps: when the combined cycle unit starts to vacuumize, opening the middle bypass adjusting valve to a first preset opening degree, opening the high bypass adjusting valve to a second preset opening degree, and closing the low bypass adjusting valve; and when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is greater than the first preset pressure, the low bypass regulating valve is opened to a third preset opening degree, so that the cold starting time and the starting natural gas consumption of the combined cycle unit are greatly reduced, the single-start power generation gas consumption of the unit is reduced, and the cold starting economy is obviously improved. Meanwhile, the invention accelerates the load-lifting speed of the unit, and shortens the time from the starting of the gas turbine to the APCL investment of the gas turbine, thereby shortening the time of the NOx emission exceeding during the starting of the gas turbine, and obviously improving the environmental protection performance during cold starting.
In order to further illustrate the technical idea of the present invention, in combination with a specific application scenario, another embodiment of the present invention provides a schematic flow chart of a cold start method for a gas-steam combined cycle unit, where the method is applied to a combined cycle unit including a steam turbine, a condenser, a low pressure system of the steam turbine, a medium pressure system of the steam turbine, and a high pressure system of the steam turbine, wherein,
a low bypass adjusting valve is arranged between the turbine low-pressure system and the condenser, a middle bypass adjusting valve is arranged between the turbine medium-pressure system and the condenser, and a high bypass adjusting valve is arranged between the turbine high-pressure system and the condenser; as shown in fig. 3, the method comprises the following specific steps:
s201, when the combined cycle unit starts to vacuumize, the middle bypass adjusting valve is opened to a first preset opening degree, the high bypass adjusting valve is opened to a second preset opening degree, and the low bypass adjusting valve is closed.
In this step, when the combined cycle unit starts to be vacuumized, the middle bypass adjusting valve is opened to 75%, the high bypass adjusting valve is opened to 65%, and the low bypass adjusting valve is closed.
S202, when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is greater than a first preset pressure, the low bypass adjusting valve is opened to a third preset opening degree.
In this step, when the combined cycle unit starts to ignite and the pressure of the low pressure system of the steam turbine is greater than 0.02MP, the low bypass adjusting valve is opened to 65%.
S203, when the combustion engine of the combined cycle unit is connected to the grid, the load of the combustion engine is increased to a first preset load.
In the step, when the gas turbine of the combined cycle unit is connected to the grid, the load of the gas turbine is increased to 25 MW.
And S204, when the steam turbine completes grid connection, the load of the gas turbine is increased to a second preset load, and steam supplement parameters of the steam turbine are adjusted according to the opening degrees of the low bypass regulating valve and the middle bypass regulating valve.
In this step, when the steam turbine completes grid connection, the load of the gas turbine is increased to a second preset load, the second preset load is generally between 65 and 85MW, and the steam compensation parameters of the steam turbine are adjusted according to the opening degrees of the low bypass adjusting valve and the middle bypass adjusting valve. Optionally, the steam supplementing parameter needs to meet the conditions including: the steam temperature before the middle and low pressure steam supply valves is 11 ℃ higher than the saturation temperature, when the steam supply valves are closed, the pressure difference between the pressure before the steam supply valves and the pressure at the steam supply positions is more than 0.05MPa, the pressure before the middle pressure steam supply valves is within the range of 0.3-1.5MPa, the pressure before the low pressure steam supply valves is within the range of 0.08-0.4MPa, and the difference between the steam before the steam supply valves and the temperature of the steam supply port cylinder wall is not more than +/-56 ℃.
The invention discloses a cold-state starting method of a gas-steam combined cycle unit, which comprises the following steps: when the combined cycle unit starts to vacuumize, opening the middle bypass adjusting valve to a first preset opening degree, opening the high bypass adjusting valve to a second preset opening degree, and closing the low bypass adjusting valve; when the combined cycle machine is usedWhen the group starts to ignite and the pressure of the low-pressure system of the steam turbine is greater than a first preset pressure, opening the low bypass regulating valve to a third preset opening; when the gas turbine of the combined cycle unit is connected to the grid, the load of the gas turbine is increased to a first preset load; when the steam turbine completes grid connection, the load of the gas turbine is increased to a second preset load, and steam supplement parameters of the steam turbine are adjusted according to the opening degrees of the low bypass regulating valve and the middle bypass regulating valve; therefore, the cold-state starting time and the starting natural gas consumption of the combined cycle unit are greatly reduced, the single-start power generation gas consumption of the unit is reduced, and the cold-state starting economy is obviously improved. By adopting the method disclosed by the invention through experiments, the single cold-state starting time of the combined cycle unit can be shortened by about 20 minutes, the natural gas can be saved by about 1.65 ten thousand squares, the power generation benefit can be increased by about 5.5 ten thousand kWh, and the NO can be reducedXThe emission is about 0.12 ton, and remarkable economic benefit and ecological benefit are created.
Corresponding to the cold-state starting method of the gas-steam combined cycle unit in the embodiment of the application, the embodiment of the application also provides cold-state starting equipment of the gas-steam combined cycle unit, the equipment is applied to the combined cycle unit comprising a steam turbine, a condenser, a low-pressure system of the steam turbine, a medium-pressure system of the steam turbine and a high-pressure system of the steam turbine, wherein,
a low bypass adjusting valve is arranged between the turbine low-pressure system and the condenser, a middle bypass adjusting valve is arranged between the turbine medium-pressure system and the condenser, and a high bypass adjusting valve is arranged between the turbine high-pressure system and the condenser; as shown in fig. 4, the apparatus includes:
the first adjusting module 401 is configured to open the middle bypass adjusting valve to a first preset opening degree, open the high bypass adjusting valve to a second preset opening degree, and close the low bypass adjusting valve when the combined cycle unit starts to perform vacuum pumping;
the second adjusting module 402 is configured to open the low bypass adjusting valve to a third preset opening degree when the combined cycle unit starts to ignite and the pressure of the low pressure system of the steam turbine is greater than a first preset pressure;
when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is not greater than a first preset pressure, the steam of the low-pressure system of the steam turbine is discharged through a low-pressure drain valve.
In a specific application scenario of the present application, the apparatus further includes:
and the third adjusting module is used for increasing the load of the combustion engine to a first preset load when the combustion engine of the combined cycle unit completes grid connection.
In a specific application scenario of the present application, the apparatus further includes:
and the fourth adjusting module is used for increasing the load of the gas turbine to a second preset load when the steam turbine completes grid connection, and adjusting steam supplement parameters of the steam turbine according to the opening degrees of the low bypass regulating valve and the middle bypass regulating valve.
In a specific application scenario of the present application, the fourth adjusting module is specifically configured to:
when the pressure before the medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is smaller than a second preset pressure or the medium-pressure steam supplementing valve is closed and the pressure difference between the pressure before the medium-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening of the middle bypass regulating valve;
and when the front pressure of a medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is greater than a third preset pressure, the opening degree of the medium-pressure bypass regulating valve is increased.
In a specific application scenario of the present application, the fourth adjusting module is further specifically configured to:
when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is smaller than a fourth preset pressure or the low-pressure steam supplementing valve is closed and the pressure difference between the pressure in front of the low-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening degree of the low bypass adjusting valve;
and when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is greater than a fifth preset pressure, improving the opening degree of the low bypass adjusting valve.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not necessarily depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (10)
1. A cold-state starting method of a gas-steam combined cycle unit is characterized in that the method is applied to the combined cycle unit comprising a steam turbine, a condenser, a steam turbine low-pressure system, a steam turbine medium-pressure system and a steam turbine high-pressure system, wherein,
a low bypass adjusting valve is arranged between the turbine low-pressure system and the condenser, a middle bypass adjusting valve is arranged between the turbine medium-pressure system and the condenser, and a high bypass adjusting valve is arranged between the turbine high-pressure system and the condenser;
the method comprises the following steps:
when the combined cycle unit starts to vacuumize, opening the middle bypass adjusting valve to a first preset opening degree, opening the high bypass adjusting valve to a second preset opening degree, and closing the low bypass adjusting valve;
when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is greater than a first preset pressure, opening the low bypass adjusting valve to a third preset opening degree;
when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is not greater than a first preset pressure, the steam of the low-pressure system of the steam turbine is discharged through a low-pressure drain valve.
2. The method of claim 1, wherein the method further comprises:
and when the gas turbine of the combined cycle unit is connected to the grid, increasing the load of the gas turbine to a first preset load.
3. The method of claim 1, wherein the method further comprises:
and when the steam turbine completes grid connection, the load of the gas turbine is increased to a second preset load, and steam compensation parameters of the steam turbine are adjusted according to the opening degrees of the low bypass regulating valve and the middle bypass regulating valve.
4. The method of claim 3, wherein adjusting steam turbine steam supplement parameters based on the opening of the low and medium bypass modulating valves comprises:
when the pressure before the medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is smaller than a second preset pressure or the medium-pressure steam supplementing valve is closed and the pressure difference between the pressure before the medium-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening of the middle bypass regulating valve;
and when the front pressure of a medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is greater than a third preset pressure, the opening degree of the medium-pressure bypass regulating valve is increased.
5. The method of claim 3, wherein adjusting steam turbine steam supplement parameters based on the opening of the low and medium bypass modulating valves further comprises:
when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is smaller than a fourth preset pressure or the low-pressure steam supplementing valve is closed and the pressure difference between the pressure in front of the low-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening degree of the low bypass adjusting valve;
and when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is greater than a fifth preset pressure, improving the opening degree of the low bypass adjusting valve.
6. A cold-state starting device of a gas-steam combined cycle unit is characterized in that the device is applied to the combined cycle unit comprising a steam turbine, a condenser, a steam turbine low-pressure system, a steam turbine medium-pressure system and a steam turbine high-pressure system, wherein,
a low bypass adjusting valve is arranged between the turbine low-pressure system and the condenser, a middle bypass adjusting valve is arranged between the turbine medium-pressure system and the condenser, and a high bypass adjusting valve is arranged between the turbine high-pressure system and the condenser;
the apparatus comprises:
the first adjusting module is used for opening the middle bypass adjusting valve to a first preset opening degree, opening the high bypass adjusting valve to a second preset opening degree and closing the low bypass adjusting valve when the combined cycle unit starts to vacuumize;
the second adjusting module is used for opening the low bypass adjusting valve to a third preset opening degree when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is greater than a first preset pressure;
when the combined cycle unit starts to ignite and the pressure of the low-pressure system of the steam turbine is not greater than a first preset pressure, the steam of the low-pressure system of the steam turbine is discharged through a low-pressure drain valve.
7. The apparatus of claim 6, wherein the apparatus further comprises:
and the third adjusting module is used for increasing the load of the combustion engine to a first preset load when the combustion engine of the combined cycle unit completes grid connection.
8. The apparatus of claim 6, wherein the apparatus further comprises:
and the fourth adjusting module is used for increasing the load of the gas turbine to a second preset load when the steam turbine completes grid connection, and adjusting steam supplement parameters of the steam turbine according to the opening degrees of the low bypass regulating valve and the middle bypass regulating valve.
9. The device of claim 8, wherein the fourth adjustment module is specifically configured to:
when the pressure before the medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is smaller than a second preset pressure or the medium-pressure steam supplementing valve is closed and the pressure difference between the pressure before the medium-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening of the middle bypass regulating valve;
and when the front pressure of a medium-pressure steam supplementing valve of the medium-pressure system of the steam turbine is greater than a third preset pressure, the opening degree of the medium-pressure bypass regulating valve is increased.
10. The device of claim 8, wherein the fourth adjustment module is further specifically configured to:
when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is smaller than a fourth preset pressure or the low-pressure steam supplementing valve is closed and the pressure difference between the pressure in front of the low-pressure steam supplementing valve and the pressure at the steam supplementing position is smaller than a preset pressure difference, reducing the opening degree of the low bypass adjusting valve;
and when the pressure in front of a low-pressure steam supplementing valve of the low-pressure system of the steam turbine is greater than a fifth preset pressure, improving the opening degree of the low bypass adjusting valve.
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