Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S50/00—Arrangements for controlling solar heat collectors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B1/00—Methods of steam generation characterised by form of heating method
  • F22B1/006—Methods of steam generation characterised by form of heating method using solar heat
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B35/00—Control systems for steam boilers
  • F22B35/007—Control systems for waste heat boilers
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B37/00—Component parts or details of steam boilers
  • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
  • F22B37/38—Determining or indicating operating conditions in steam boilers, e.g. monitoring direction or rate of water flow through water tubes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
  • F22D5/00—Controlling water feed or water level; Automatic water feeding or water-level regulators
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
  • F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
  • F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
  • F24S23/74—Arrangements for concentrating solar-rays for solar heat collectors with reflectors with trough-shaped or cylindro-parabolic reflective surfaces
• • 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
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/40—Solar thermal energy, e.g. solar towers

Definitions

• the invention relates to a method for operating a directly heated, solar thermal steam generator, wherein a device for adjusting the feedwater mass flow M, a set value Ms for the feedwater mass flow M is supplied. It also relates to a directly heated solar thermal steam generator with a device for adjusting the feedwater mass flow M, and a solar thermal ⁇ parabolic trough power plant with a directly heated solar thermal steam generator.
• Solar thermal power plants are an alternative to conventional electricity generation ago ⁇ .
• running solar thermal power plants with parabolic trough collectors and indirect evaporation A future option is the direct ⁇ te evaporation in parabolic trough collectors or Fresnel collectors.
• a solar thermal power plant with parabolic ⁇ trough collectors or Fresnel collectors and direct expansion consists of a solar panel in which the feed water is preheated, evaporated and superheated, and a kon ⁇ conventional power plant part in which the thermal energy of the steam is converted into electric energy.
• the evaporator In today's parabolic trough power plants with direct evaporation, the evaporator is over-fed. Via a corresponding pre ⁇ direction (water-steam separator), the excess at the evaporator outlet, not yet evaporated water is separated from the steam. The steam flows into the following superheater collectors. The excess water is collected either in the separator itself or in a downstream bottle (Wasserammei ⁇ vessel), later discharged via a Abschlämmar ⁇ matur and in the best case at the evaporator inlet the main stream again mixed (circulated).
• a so-called three-phase system is usually used to regulate the required evaporator flow.
• Used components control which nach ceremonit depending on the he generated ⁇ steam mass flow in the most favorable case exactly the same amount of feed water.
• a correction controller which, for example, the water level in Wassersammeigefäß re ⁇ gel, corrects the feed water quantity thus determined, should the tatsachliche water level from the predetermined desired value deviate ⁇ chen (eg for dynamic processes and any necessary discharge mass flows during blow).
• the advantage of this method lies in the low-fluctuation medium temperature at the evaporator outlet, since this corresponds to the saturation ⁇ tion temperature.
• a more stable flow pattern to Errei ⁇ chen are not taken additional flow-stabilizing measures for the run concept.
• the evaporation end point is fixed in place on the evaporator outlet, eliminating the advantage of operating flexibi ⁇ formality of a once-through steam generator with variable Ver ⁇ dampfungsend Vietnamese as to ensure, for example, as constant as possible live steam ⁇ temperatures over a wide load range.
• the object of the invention is to provide a method of operating a direct solar heated once-through steam generator be ⁇ riding observed, which is characterized in particular in transient processes by a particularly high reliability and Quality ⁇ formality of controllability. Furthermore, a particularly suitable for carrying out the process solar thermal steam generator should be specified.
• the object of the invention directed to a method is solved by the features of claim 1.
• the invention is based on the idea to apply a concept of predictive or predictive mass flow control for a directly heated, solar thermal steam generator to improve the control quality in the setting of the feedwater mass flow M. It is the essence of the invention to consistently consider as relevant recognized correction values in the determination of a suitable desired value M for the feedwater mass flow M. By taking account of a correction value K T , it is possible to compensate for thermal storage effects which occur in particular in the case of transient processes in the form of injection or withdrawal of thermal energy.
• the thermal storage effects of stored or stored thermal energy of the tube walls of the evaporator of the solar thermal steam generator are corrected by the correction value K T, the thermal storage effects of stored or stored thermal energy of the tube walls of the evaporator of the solar thermal steam generator.
• the Ge ⁇ felieremenge Q of the solar thermal steam generator is further taken into ⁇ into account when setting the target value M.
• a correction value K F in the setting of the target value wherein corrected in a first approach by the correction value K F water-steam side and flow-medium side memory effects of the evaporator of the solar thermal steam generator.
• the correction value K F additionally corrects the injected or withdrawn amounts of feedwater in a economizer upstream of the evaporator in a second batch.
• thermodynamic state values generally change in the evaporator on the flow medium side, such as, for example, the evaporator outlet temperature, the pressure (thus also the boiling temperature of the flow medium for the subcritical case) and the evaporator inlet temperature.
• the material temperature of the evaporator tubes is not constant and is larger or smaller depending on the direction. Consequently, thermal energy is expelled into or out of the tube walls of the evaporator.
• a differentiating element of the first order (DTI element)
• this physical effect can be reproduced by control technology.
• an input signal of the differentiating element is a mean temperature of all material evaporator tubes to processin ⁇ ren and use.
• the average material temperature can be determined, for example, via the variables known from the process, evaporator outlet temperature, system pressure, evaporator inlet temperature and possibly even taking into account maximum possible heat flow densities. Now changes this average material temperature and the output of the differentiating circuit is multiplied by the mass of the entire evaporator tubes and the specific heat capacity of the Ver ⁇ liner material can turn into the pipe wall or be stored out of the tube wall amounts of heat to be quantified.
• thermodynamic state values such as pressure and temperature inevitably involve changes in the specific volume or density of the flow medium in each collector heating surface. Taking for example due to load ⁇ change the specific volume of the flow medium across the evaporator from (density increases), the ⁇ se temporarily absorb more fluid (mass storing).
• the density distribution in the evaporator tube is significantly characterized by the beginning of the evaporation. This is very strongly linked to the evaporator inlet subcooling. Once the evaporation in the evaporator tube has been used, the mixture density is greatly reduced downstream. If the entry subcooling changes due to transient processes, the start of evaporation and thus the entire density distribution in the tube are simultaneously shifted. Bulk input and output effects are the result. Increasing inlet subcooling results in the short term in an increase in the enthalpy of the evaporator. This can be explained by the fact that with increasing inflow subcooling the beginning of evaporation slides towards the evaporator outlet (the evaporator is fed with colder fluid).
• ver ⁇ strengthens fluid is stored and reduces conversely the outlet mass flow, which must result in associated heating in an increased Verdampferaustrittsenthalpie immediately.
• ver ⁇ strengthens fluid is stored and reduces conversely the outlet mass flow, which must result in associated heating in an increased Verdampferaustrittsenthalpie immediately.
• the evaporator inlet subcooling is reduced, the reverse process occurs. If an additional first-order differentiator is used in the feed water setpoint determination, the choice of suitable input signal (for example inlet supercooling, evaporator inlet temperature or evaporator inlet enthalpy), a suitable time constant and appropriate gain can effectively reduce enthalpy variations at the evaporator outlet.
• Differentiating member of the first order can be detected quantitatively. Is a suitable gain (preferably the entire volume of the economizer collector tubes) and a ge ⁇ suitable time constant (preferably half the flow time of the flow medium through the Economizerkollektorrohre
• the correction value K f is now obtained depending on Anlagenkonfigu ⁇ ration (with or without economizer) from either the sole determination of the fluid-side extended or stored amounts of fluid in the evaporator or the sum of the fluid-side extended or stored amounts of fluid in the evaporator and economizer.
• the solar thermal steam generator is integrated in a solar thermal parabolic trough power plant with a number of parabolic troughs with direct evaporation.
• the feed water setpoint determination invention is used in solar thermal steam generators with direct evaporation, can also strongly transient operating conditions, as they occur in solarbelik ⁇ th power plants increased (eg clouds swipe) constant steam temperatures can be ensured.
• the inventive concept is also suitable for modular use in several solar-heated steam generators of a single parabolic trough power plant. Zusharm ⁇ Lich the concept can also be used without significant changes in combination with other components such as injection cooler.
• the possibility of a modular control of individual collector strands Since in a solar thermal power plant trough collectors with parabolic or Fresnel collectors, the number of parallel collector Trost ranks is kept to a manageable level, the feedwater flow rate of each individual ⁇ a strand could individu- ally by the described concept be regulated so that for each strand an equivalent Re ⁇ gelamba exists.
• the generated live steam of each individual strand would be combined in a steam bus at ent ⁇ speaking pressure level and the turbine provided for relaxation. Under these circumstances, each individual strand generates the maximum possible amount of steam with the desired live steam temperature and thus the highest possible efficiency in accordance with the heat supply by the sun.
• FIG. 1 shows a schematic representation of a direct heated ⁇ th solar thermal steam generator 3 with feed ⁇ water flow control for stationary operation.
• FIG. 2 shows a schematic representation of a directly heated solar thermal steam generator 3 for the in ⁇ stationary operation with predictive feedwater setpoint determination.
• a schematic representation of a deve ⁇ winding of a direct fired solar thermal steam generator 3 with predictive feedwater target ⁇ value determination taking into account additional Economi zerdividing surfaces 1 shows a schematic control diagram of a feed ⁇ water set point determination for the stationary operation of a solar thermal steam generator 3 in a parabolic trough nenkraftwerk 1.
• the parabolic trough power plant 1 is not shown in detail.
• the solar thermal steam generator is only shown schematically.
• Solar thermal steam generators usually comprise a number of parabolic trough collectors 13 (or Fresnel collectors), which can be used as evaporator collectors 14, as superheater collectors 9, or as economizer collectors 10.
• the solar thermal steam generator 3 shown in FIG. 1 comprises only evaporator collectors 14 and superheater collectors 9.
• the evaporator collectors 14 are connected to a feedwater supply line 15 for the supply of feed water.
• the illustrated in FIG 1 solar thermal steam generator 3 ⁇ be found also in the forced circulation operation, is completely vaporized in the evaporator in the collectors 13, the feed water by solar thermal direct heating and superheated in the connector.
• the solar thermal steam generator 3 is designed for a controlled admission with feed water.
• a feedwater pump 17 is provided in the feedwater supply line 15. on.
• a throttle valve 19 is further connected, that is controlled by a servomotor 18.
• Throttle valve 19 and actuator 18 are Be ⁇ part of a device for adjusting the feedwater mass flow 5, which further includes a control element 21, which is provided for driving the servomotor 18, and a measuring device 20 which determines the feedwater mass flow M in the feedwater supply line 15 ,
• the control element 21 is input side to a tung a lei- 22 supplied desired value M for the feed-water mass flow M with the detected via the measuring device 20 the current actual value of the feed-water mass flow M beauf ⁇ beat.
• the data line 22 is connected on the input side to the feedwater flow rate control 11 designed to specify the desired value M for the feedwater mass flow M.
• the set value M is lenthalpieerhöhung using a heat flow balance of the encryption steamer of the solar thermal steam generator 3 via the Ver ⁇ ratio from the currently transmitted in the evaporator of the solar thermal steam generator 3 to the feed water heat flow on the one hand and a desired view to the predetermined Enthalpiesollwert at the evaporator outlet Sol- of the feedwater, on the other hand.
• the feedwater flow control 11 has a divider 23.
• the counter is provided to the divider 23 by a function module 24.
• the function module 24 determines in the evaporator of the solar thermal steam generator 3, and the transferred to the evaporator collector array Wär ⁇ me antique Q.
• each evaporator collector 14 of the so-called Larthermischen steam generator 3 equipped with a corresponding measuring device.
• the measured data from the individual evaporator collectors 14 are summed up in a function module 25 and delayed in time due to the transient heat conduction in the tube walls, for example, over a PT3 element.
• the dividing member 23 is supplied with the warm-up period or the enthalpy difference of the flow medium in the evaporator collectors 14.
• the enthalpy difference is formed from the Enthalpiesollwert at the outlet of the evaporator ⁇ collectors 14 and the current enthalpy at the entrance of the evaporator panels 14, which is determined by conversion over the measured variables pressure and temperature.
• the actual value of the current enthalpy of the feedwater before entering the so ⁇ larthermischen steam generator 3 is determined by an evaluation unit 33, and transmitted to the function module 32.
• the evaluation unit 33 is connected to a pressure measuring device 35 and to a temperature measuring device 36, which are each connected in the feed water supply line 15.
• the set enthalpy at the outlet of the evaporator of the solar thermal mixer 3 is selected as a function of the state of the system and of the evaporator design and predetermined as the setpoint.
• the desired enthalpy is supplied to the functional module 32 via a signal generator 34.
• a Differenzbil ⁇ tion in the function module 32 thus required depending on the desired evaporator outlet
• Enthal ⁇ pieerhöhung of the flow medium in the evaporator of the solar thermal steam generator 3 is determined, which is used as a denominator in Divi ⁇ dierglied 23.
• the divider 23 calculates the required mass flow signal.
• thermodynamic state values change, such as the live steam temperature, the pressure (thus in the subcritical case, the boiling temperature of the flow medium) and the feedwater temperature.
• the material temperature of the steam generator tubes is not constant and is larger or smaller depending on the direction. Consequently, thermal energy in the tube walls on or out of the tube ⁇ walls expelled. Accordingly, compared with the thermal heat of the thermal oil, more or less heat is temporarily available for the steam generation process of the flow medium, depending on the direction of the material temperature change. This is observed both for systems with under and überkriti ⁇ rule steam parameters.
• correction value K T is a characteristic heat flow characteristic value by means of which the injection and withdrawal effects of the evaporator tubes can be determined equally for subcritical and supercritical systems.
• the correction value K T is shown in FIG 2, a subtracter provided in extension to FIG 1 40, that between the functional module 24 and the dividing member 23 is ge ⁇ on.
• the differentiator 40 forms the difference between the introduced into the evaporator heat output Q (total heat absorption), which is provided by the functional module 24, and the correction value K T, and passes the He ⁇ result as the corrected introduced amount of heat to the divider 23.
• the correction value K T is provided to the subtracter 40 by a differentiator 41.
• For the differentiator ⁇ member 41 is to define and use as input a middle material Tempe ⁇ temperature of all the evaporator tubes.
• the mean material temperature can be determined via the variables known from the process, namely, the live steam temperature, the system pressure, and the feedwater temperature. Now changes this average material temperature and this temporal change (evaluated member via the differentiating 41) to the mass of the entire steam generator tubes and the specific heat capacity of the evaporator material mul ⁇ plied, the amounts of heat once in the tube wall or keptspei ⁇ cherten can in Form of the correction value K T quantifi ⁇ be adorned.
• an appropriate time constant of the differentiating circuit 41 to the timing of the memory-described effects can be replicated relatively accurately so that it based on transient operations, additional effect of the input or Ausriesns heat of Me ⁇ tallmassen can be calculated directly.
• FIG. 3 shows a schematic diagram of a directly heated ⁇ be solar thermal steam generator 3 in a further development of Figure 2 in additional consideration of the correction value K F.
• an adder 42 which is connected in the data line 22, and the setpoint value Ms are corrected by the correction value K F.
• the correction value K F is supplied to the adder 42 via a differentiating element 43.
• the differentiator 43 into account ⁇ Untitled data such as inlet supercooling of the evaporator, whosenthalpie of the evaporator or the Lucaswassertem ⁇ temperature itself.
• the differentiator 43 is parameterized with a pas ⁇ send time constants and an appropriate gain to the Enthalpieschwankeptept at the evaporator outlet of the solar thermal steam generator 3 effectively diminish.
• the differentiating circuit 43 receives the input side of play at ⁇ the inlet supercooling by the evaluation unit 48.
• the evaluation unit 48 is connected to the pressure measuring device 35 and the temperature measuring device 36, which already provide the evaluation unit 33 with measurement data.
• FIG. 4 shows, in comparison with FIG. 3, an extended interconnection of the solar thermal steam generator 3 with additional economizer collectors 10.
• the differentiating element 44 is connected on the input side to a functional element 51, in which an average density of the fluid is determined.
• a functional element 51 in which an average density of the fluid is determined.
• the functional module 49 is connected to a pressure measuring device 55 and a temperature measuring device 56, which are connected in the feedwater line 15 before the first economizer collector 10 enters.
• the functional module 50 is connected to the pressure measuring device 35 and the temperature measuring device 36, which already supply the evaluation unit 33 with measurement data.
• Function module 49 and function module 50 calculate the fluid densities at the respective measuring points from the pressure and temperature information.
• the functional element 51 is calculated via a suitable conversion a representative Dichtemit ⁇ tel.
• a change of this sealant is necessarily an indicator of the fluid side injection and Aus Grandeskyskyskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinskyinsky

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Energy (AREA)
• Sustainable Development (AREA)
• Engine Equipment That Uses Special Cycles (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=45569639

Family Applications (1)

Country Status (6)

Families Citing this family (7)

Family Cites Families (10)

• 2011
  • 2011-02-17 DE DE102011004277A patent/DE102011004277A1/de not_active Ceased
• 2012
  • 2012-02-03 CN CN201280018777.XA patent/CN103620303B/zh not_active Expired - Fee Related
  • 2012-02-03 WO PCT/EP2012/051834 patent/WO2012110328A2/fr active Application Filing
  • 2012-02-03 US US13/985,974 patent/US9568216B2/en not_active Expired - Fee Related
  • 2012-02-03 EP EP12703080.7A patent/EP2673562A2/fr not_active Withdrawn
  • 2012-02-03 AU AU2012217271A patent/AU2012217271B2/en not_active Ceased

Also Published As

Similar Documents

Legal Events