Classifications

• • 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
  • F01K15/00—Adaptations of plants for special use
• • 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
• • 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
  • F01K23/101—Regulating means specially adapted therefor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B35/00—Control systems for steam boilers
  • F22B35/06—Control systems for steam boilers for steam boilers of forced-flow type
  • F22B35/10—Control systems for steam boilers for steam boilers of forced-flow type of once-through type
• • 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]

Definitions

• the invention relates to a method for operating a combined cycle power plant with a gas turbine and with one of the gas turbine exhaust or heating gas after ⁇ connected heat recovery steam generator according to the preamble of claim 1.
• the invention further relates to a prepared for carrying out the method gas and Steam turbine ⁇ plant and a corresponding control device.
• a heat recovery steam generator is a heat exchanger that recovers heat from a hot gas stream.
• Heat recovery steam generators are used, among other things, in gas and steam turbine (GUD) plants, which are predominantly used for power generation.
• GUID gas and steam turbine
• a modern combined cycle gas turbine usually includes one to four gas turbines and at least one steam turbine, either each turbine drives a generator (multi-shaft system) or a gas turbine with the steam turbine to ⁇ together on a common shaft drives a single generator (single-shaft system).
• the hot exhaust gases of Gasturbi ⁇ ne (s) are used in the heat recovery steam generator for generating water vapor.
• the steam is then fed to the steam turbine.
• about two-thirds of the electrical power is accounted for by the gas turbine and a third by the steam turbine.
• the so-called evaporator which can preferably be designed as a forced-circulation evaporator and in particular as a so-called BENSON evaporator.
• the flow medium is then present as a vapor or water-steam mixture, wherein any residual moisture is separated in a separating device placed there.
• the forwarded steam is subsequently heated further in the superheater. Thereafter, the superheated steam flows into the high pressure part of the steam turbine, where it is expanded and fed to the subsequent pressure stage of the steam generator. There it is overheated again and then introduced into the next pressure stage of the steam turbine.
• the feedwater mass flow is regulated in the feedwater circuit and in particular in the evaporator.
• load ⁇ changes the evaporator flow should be changed as synchronously as possible to the heat input into the heating surfaces of the evaporator, because otherwise a deviation of the specific enthalpy of the flow medium at the outlet of the evaporator can not be reliably avoided by a desired value.
• Such an undesired deviation of the specific enthalpy makes it difficult to regulate the temperature of the steam produced by the steam generator. Tenden live steam and also leads to high Mate ⁇ rialbelastieux and thus shorten the service life of the steam generator.
• the feedwater flow control in the form of a so-called predictive or predictive design configured be.
• the required feedwater mass flow setpoint values should also be provided during load changes as a function of the current operating state or the operating state expected for the next future.
• This additional power can be released in a relatively short time, so that the delayed power increase by the gas turbine (limited by their design and operation-related maximum load change speed) can be ⁇ at least partially compensated.
• the entire force ⁇ plant block makes this measure immediately a leap in performance and can hold by a subsequent performance platforms ⁇ tion of the gas turbine even this level of performance permanently or even exceed, provided that the plant was located at the time of additionally required power reserves in the partial load range.
• ferzeugers of the above type where necessary, a power reserve reserve is releasable, and in which the normal operating efficiency of the system is not unduly impaired.
• the rapid increase in performance should be made possible regardless of the design of the heat recovery steam generator at the overall system without major structural invasive Mo ⁇ dberichten.
• a further object of the invention is to specify a gas and steam turbine installation which is particularly suitable for carrying out the method and a corresponding control device.
• Main steam is converted with a specific thermodynamic state.
• a so-called superheat setpoint is specified at the evaporator outlet.
• the temperature of the steam at said outlet should therefore be a desired difference above the boiling point of the medium.
• a characteristic value is determined which characterizes the heat flow into the evaporator. Considering the cached in the components of the evaporator heat amounts, this results in the standing for the feed water to Availability checked ⁇ supply thermal energy. From this, in turn, the amount of feed water can be calculated, which can be converted by means of the heat supply in steam with a temperature increase according to specification.
• the superheat setpoint is lowered from a normal value designed for standard operation of the gas and steam turbine plant with comparatively high efficiency to a smaller activation value.
• This results in an increase of the feedwater mass flow through the control system.
• This has at approximately constant heat supply of the flue gas un ⁇ indirectly, a reduction in overheating respectively the temperature of the flow medium at the evaporator outlet result.
• the material temperatures are also reduced the affected heating surfaces, ie the evaporator and the downstream superheater.
• thermal energy from the heating surfaces of the evaporator and the superheater is finally stored on ⁇ due to the increased flow of the medium with reduced medium temperature and released in the steam turbine in the form of additional power.
• thermodynamic supply state of the live steam is provided in a further improved variant of the process, not to deposit the boiling point than fes ⁇ th value in a memory, but indirectly to determine a preferably permanent pressure measurement at the evaporator inlet or outlet of the evaporator.
• the calculation of the primary set point for the Lucaswas ⁇ sermassenstrom by quotient formation is provided in consideration of the data latched in the components of the evaporator heat amounts.
• the denominator in turn is calculated from the difference between a Enthalpiesollwert of the medium at the evaporator outlet, characterized by the corresponding superheat setpoint as well as the measured pressure at the evaporator outlet, and the determined enthalpy of the medium at the evaporator inlet, which in turn are determined by a ent ⁇ speaking temperature and pressure measurement can, formed.
• a basic set value of the feed water mass flow is given, which also produces in the adjusted state of the Sys ⁇ tems in the best case the required setpoints permanently. That is by definition 100 -% - Allowance stood or output state of the corresponding load case see is ⁇ . This applies regardless of whether the system of heat recovery steam generator and steam turbine is in partial or full load operation.
• the overall control system which works particularly effective ty ⁇ pisch be in a limited range of values is thus always held in exactly this value ⁇ area.
• a preferred control system for implementing the method according to the invention is in addition to the predictive loop, a second loop parallel working see pre ⁇ .
• a seconding ⁇ därsollwert for the feed-water mass flow is determined.
• a difference is formed from the determined enthalpy of the medium at the evaporator outlet and the corresponding enthalpy setpoint.
• the secondary target value serves as a kind of correction value to further increase the accuracy of the control, and in cases where the primary target value having high error due to the system or fluctuates, korrigie ⁇ rend or stabilizing engages.
• an enthalpy desired value can also be predefined in the control system, which is either determined by characteristic variables or acts on these in a determinative manner.
• the change between the corresponding normal value and the associated activation value should cause the heat supply to be redistributed to a larger amount of feed water.
• control device When returning the system to standard operation, it may be advantageous not to jump back from the activation value to the normal value, but to reset it continuously and thus with a time delay. This can be done at ⁇ play in synchronism with the increase in performance of the gas turbine, when a continuous performance of the entire power plant ⁇ is desired during this time.
• the control device may be equipped at a suitable location with corresponding delay elements.
• a procedurefortsreserve free ⁇ enforce is preferably used in a combined gas and steam turbine plant.
• this power ⁇ immediately reserve serves primarily as quickly available Leis ⁇ processing buffer because the extra power in a relatively short time can be released.
• the power buffer can be used to bridge a limited period of time sufficient to allow for the delayed power increase by the gas turbine (limited by its design and operating conditions). te maximum load change speed) at least partially compensate.
• the entire power plant block makes by this measure immediately a jump in performance and can also keep this level of performance permanently through the parallel increase in power output of the gas turbine or even over ⁇ stride.
• the invention shown SSE method is to reali ⁇ Sieren without invasive physical measures. It can be implemented solely by implementing additional building blocks in the control system. Thus, a higher plant flexibility and a higher plant ⁇ gennutzen be achieved without additional costs.
• the method is independent of other measures, so that, for example, throttled turbine ⁇ valves can be additionally opened to increase the power ⁇ increase the steam turbine yet.
• a simultaneous regulation of the injection mass flows of injection coolers or the like provided in the heat recovery steam generator can take place with the same control target. The effectiveness of the method is not affected largely by these parallel measures ⁇ men.
• the inventive method is used in the embodiment for operating a combined cycle gas turbine plant (GUD plant).
• GUI plant combined cycle gas turbine plant
• a steam turbine DT with only one pressure stage is considered. Egg ⁇ ne expansion to multiple printing stages and corresponding interim rule is overheating stages in this connection for the competent specialist possible problems.
• the steam turbine of the combined cycle plant DT is integrated into a feed water circuit 1. Starting from a feed water reservoir ⁇ R, the feed water is conveyed by means of the pump 2 in a once-through evaporator. 3 This is usually preceded by a not illustrated economizer for preheating the feedwater here in addition.
• the feedwater mass flow into the forced-circulation evaporator 3 can be varied via a control valve 4 whose valve position is set by an associated positioning motor M.
• evaporator 3 In forced-circulation evaporator 3, hereinafter also called evaporator 3 for short, several heating surfaces are provided.
• this can be in their sequence
• Jardinwas ⁇ water circuit 1 according to the economizer 5 6 denote evaporator and superheater.
• the feed water is transferred into its gas phase and is further heated as steam with the aid of downstream superheater heating surfaces 8.
• the superheated steam serves to obtain electrical energy in a steam turbine DT and condenses in the downstream condenser K again to feed water, which is returned to the feedwater reservoir R.
• All heating surfaces of the feedwater circuit 1 are arranged in a hot gas channel 9.
• a hot gas duct 9 the exhaust gases of a gas turbine GT are introduced. These first overflow the superheater 7, 8, then the evaporator 6 and finally the economizer heating surfaces 5 and, if present, the heating surfaces of the economizer.
• a heat recovery steam generator is realized with, can be used for the production of electrical energy due to the combination with the steam turbine DT, the heat stored in the From ⁇ gases of the gas turbine GT at least partially stabilized.
• the feedwater mass flow in the feedwater circuit 1 must be regulated and any fluctuations in the hot gas feed be adapted by the gas turbine GT.
• a corresponding control system 10 is provided, which controls the servomotor M and thus adapts the position of the control valve 4.
• the said control system 10 is essentially composed of so-called function blocks FB 01... FB 10. These units can process measurement signals, access data stored in a memory, and convert these signals or data into function values via logical links , which are then either passed on to further function blocks FB 01 ... FB 10 or serve as a command code for controlling downstream devices, such as the servomotor M.
• the control commands for the servomotor M are generated by the function block FB 01.
• As a data base or input signals thus two by two setpoints parallel determined ar ⁇ beitende control loops are used, which are linked together via a multiplier. 11
• One of the two control loops is designed as a so-called predictive or anticipatory control loop.
• This subsequently primary circuit loop mentioned the system response is to be expected calculated under consideration Be ⁇ with which feed water mass flow in a subsequent time interval in principle safe operation having in addition a particularly high efficiency can be achieved.
• the corresponding quantity representing a mass flow rate of the dimension forth is, as the primary target value be distinguished ⁇ and corresponds in enem subsequent time interval the first of the two reference values, which are linked together by the multiplier.
• the size A determined by means of a function block FB 02, represents the heat available for the medium of water, that is, the heat discharged from the exhaust gas of the gas turbine GT and stored in the evaporator 3 minus the temperature in the Heating surfaces of the evaporator 5, 6, 7 cached amounts. Exactly this heat supply should be used to cause a certain enthalpy change B of the medium in the evaporator 3. Those enthalpy B obtained by forming the difference at the adder 13 between the desired enthalpy of the medium at the evaporator outlet and the Ent ⁇ halpiewert the medium at the evaporator inlet.
• the ⁇ value enthalpy of the medium at the evaporator inlet is in this calculation regarded as given but variable and determined via a function block FB 03, accesses the measurement signals of a tempera ⁇ tursensors 14 and a pressure sensor 14a.
• the thermodynamic state of the medium and, consequently, the enthalpy value at the evaporator outlet should be specified.
• an overheating setpoint is stored in the function block FB 04. Accordingly, the temperature of the vapor at the evaporator outlet should be a predetermined amount, the normal value, above the boiling temperature of the medium, which in turn is determined with the aid of the data of a pressure sensor 15 at the evaporator outlet.
• the ensuing enthalpy desired value of the medium at the evaporator outlet is supplied by the function block FB 04 to the subtracting element 13.
• a corresponding correction term is determined by a functional element FB 05 and then added to an adder 16 connected downstream of the divider 12.
• the second, also called secondary circuit, control loop is designed as a responsive control loop and should further increase the accuracy of the entire control system 10 by a kind of fine-tuning. This is done by means of a setpoint-actual value adjustment to a subtractor 17. As a setpoint is the subtractor 17 via the function block FB 06 of the function block FB 04 calculated enthalpy desired value of the medium supplied to the evaporator output. The corresponding enthalpy actual value is based on the measurement signals of a temperature tursensors 18 and the pressure sensor 15 at the evaporator output and is determined by a function block FB 07.
• the here above calculated setpoint-actual value deviation is finally fed to a PI controller member 19 which provides the output side the second set value or target value for the secondary multi ⁇ plizierglied 11 available.
• This target value is a dimensionless relative size un ⁇ depending on whether the combined cycle power plant is in full-load or in partial load operation, is close to the value of the first Since the components of a control loop operate particularly effectively only in a limited range of values, it can be ensured by referring back to such a relative variable that the expected value range largely coincides with the value range which is favorable relative to the components, independent of absolute values.
• the change in the superheat setpoint is performed abruptly. Therefore, this change can be effected by applying a switch 22, 23 in each control loop.
• Each switch is controlled via an associated function block FB 08, FB 09, wherein the switching of the two switches 22, 23 takes place substantially simultaneously.
• the function blocks FB 08, FB 09 take on a comple ⁇ asking us for task.
• the function blocks FB 08, FB 09 depend on a measured frequency disturbance in the power supply. federozo an adjusted overheating setpoint, which lies in a stored value range, independently before.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Engine Equipment That Uses Special Cycles (AREA)
• Control Of Turbines (AREA)

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• 2010
  • 2010-10-14 DE DE102010042458A patent/DE102010042458A1/de not_active Withdrawn
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