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
  • F01K21/00—Steam engine plants not otherwise provided for
  • F01K21/04—Steam engine plants not otherwise provided for using mixtures of steam and gas; Plants generating or heating steam by bringing water or steam into direct contact with hot gas

Definitions

• the present invention relates to a thermal power process according to the preamble of claim 1. It also relates to a device suitable for realizing the cycle process, and to a power plant which uses a device operating according to the process according to the invention.
• the essence of the invention is therefore to recuperate at least part of the heat to be dissipated after relaxation in a power generation plant which primarily works with a gaseous process fluid which is heated in the heat exchange prior to the relaxation process and to recycle it into the cycle, this also with consideration to the given limitation of the upper process temperature not by increasing the specific enthalpy of the compressed process gas, but by supplying a further enthalpy flow in the form of a medium heated by the process waste heat.
• the primary process fluid does not undergo a phase change during any of the changes in state, while the additional medium undergoes a two-phase process in such a way that it condenses after expansion and is thus separated from the gaseous primary process fluid.
• the liquefied additional medium is brought back to a high pressure, heated by the process waste heat to be extracted, evaporated, and possibly overheated, taking up heat as a coolant in a heat sink of the process, and the compressed primary process fluid before the expansion, depending on the present States of the media either upstream or downstream of the primary process fluid heater, admixed. Both media are subsequently relaxed, preferably by submitting technical work.
• the process that the primary circulating medium goes through is initially a compression from a first state to a second state, a change in state from the second state to one third state during which heat is supplied to the primary process medium, a change in state from the third state to a fourth state during which the primary process medium is relaxed, and a state change in which the process medium is returned to the first state by heat dissipation.
• no statement has yet been made about the course of the changes in state which in fact is not primarily essential to the invention, but is determined by the special process control during the technical implementation.
• the compression and expansion at least of the theoretical cycle, for example, isothermal or quasi-isothermal, or also isentropic or approximately isentropic, and the heat supply and removal is isochoric or isobaric; in reality, the process control will depend on the choice of the respective technical means and will not perfectly understand any of the courses of theoretical changes of state cited.
• the pressures of the process fluid are the same in the first and fourth states and in the second and third states; in reality, of course, flow pressure losses occur when flowing through lines and heat transfer devices, as well as pressure losses due to the supply of heat to the flowing fluid. It goes without saying that these are not targeted total pressure changes such as those caused by relaxation or compression, but rather real unavoidable pressure changes and in particular total pressure losses.
• the generated steam is either fed to the primary process fluid after the heat supply, but still before the expansion, or completely or partially before or during the heat supply to the primary process fluid, this steam heat is supplied together with the primary process fluid.
• this steam heat is supplied together with the primary process fluid.
• at least part of the steam could be supplied to the primary process medium during the expansion from the third to the fourth state.
• the process fluid is cooled during the compression.
• heat is added to the process fluid during the expansion.
• the primary process fluid and steam preferably perform technical work during the expansion from the third to the fourth state, in particular in an engine.
• the completely closed process control enables the process fluids to be freely selected; nevertheless, the process is particularly easy to handle in practice if non-toxic media are used and air is used in particular as the primary process fluid and water as the two-phase additional fluid.
• a device for carrying out the thermal power process there is arranged at least one compression means for the primary working fluid, downstream of this at least one means for supplying heat, in particular a heat exchanger through which process fluid flows on the secondary side, at least one expansion means downstream thereof, and at least one steam generator arranged downstream of the expansion means as the first heat sink.
• the primary side of the steam generator is flowed through by the process fluid, which cools down in the process.
• the condensation of the steam does not take place isobarically and isothermally, but at a temperature corresponding to the partial pressure of the steam.
• This offers the advantage that the heat of condensation of the condensate separated at a higher partial pressure occurs at a temperature level at which this heat can be used to preheat the condensate returned to the secondary side of the steam generator.
• at least one further heat sink is arranged downstream of the first heat sink, in particular to lower the temperature in the first state as much as possible, and also to lower the residual vapor content contained in the primary process fluid as far as possible.
• the second heat sink for defining a process temperature is to be arranged in a particularly suitable manner in order to define the lowest process temperature at this point, which is caused by the temperature of the coolant used, for example
• Cooling water is given. Downstream of the heat sink or sinks or in their flow path for the primary process fluid, devices for separating the condensate are provided. Furthermore, means, in particular a feed pump, for conveying the condensate to the secondary side of the steam generator are arranged, and means for introducing the steam generated in this way downstream of the compression means and upstream of at least one expansion means.
• a feed pump for conveying the condensate to the secondary side of the steam generator
• means for introducing the steam generated in this way downstream of the compression means and upstream of at least one expansion means are arranged.
• the compression means are provided with at least one intercooler, or with means for supplying liquid drops into the process fluid flowing through the compression means, these drops providing internal cooling of the compression means by evaporation during the compression process; both measures are suitable in each case for realizing at least approximately isothermal or quasi-isothermal compression.
• means for Heat supply to the process fluid can be arranged within the expansion means or between at least two expansion means; with an appropriate design, an at least approximately isothermal control of the relaxation process can be realized.
• any condensation of residual moisture contained in the primary working medium at the compressor inlet must be taken into account, and this must be taken into account if necessary.
• the described supply of heat to the working fluid is of interest in order, if necessary, for the steam generation available at a high pressure ratio of the process and a limited upper process temperature
• the steam is supplied to the primary process fluid after partial relaxation of the primary process fluid at a reduced pressure.
• an engine is arranged as at least one expansion means, in which the primary process fluid and at least part of the vapor are expanded while performing technical work;
• an engine acting as a relaxation means is preferably arranged on a common shaft with at least one work machine acting as a compression means and / or a power consumer.
• a means for supplying heat to the process fluid is preferably a heat exchanger which is operatively connected to a heat generator on the primary side or through which the exhaust gas of a gas turbine flows through on the primary side.
• a charged firing device operating under excess pressure is particularly suitable as a heat generator. The size can be reduced by charging and the primary heat transfer in the heat exchanger can be intensified.
• the device has means with which the pressure level of the entire process and thus the circulated amount of fluid can be changed.
• This represents a particularly expedient possibility for varying the output of a machine operating according to the thermal power process according to the invention, in which, for example, the pressure ratio of the process remains essentially constant, which is why all machine components are operated close to the design point even at partial load.
• the back pressure of the expansion agent i.e. the process low pressure, can be set so that the steam is not wet even during the expansion process if there is only a comparatively low upper process temperature.
• a shut-off and / or throttling shunt line is advantageously arranged downstream of the compression means, via which compressed working fluid can be conducted directly into the low-pressure part of the device according to the invention. This comes into play when one
• Power consumer which is coupled to an engine acting as a relaxation device, has rapid load reductions, such as the load shedding of a generator.
• the compressed process fluid is then immediately discarded in the low-pressure part of the thermal power plant.
• Turbocompressors for example, are used as compression means and turbines are used as expansion means, in particular when high mass flows and thus continuously operating machines are required for high unit outputs.
• screw compressors and expanders or piston machines and other types familiar to those skilled in the art can also be used without further notice; In particular, it proves to be a suitable one at very high pressure ratios Series connection of flow and displacement machines as extremely practical.
• a preferred embodiment of a thermal power plant for realizing the process according to the invention is a gas turbine group with a closed circuit, at least one heat recovery steam generator being arranged as a first heat sink downstream of a last turbine, and one or more further heat sinks downstream of the latter, in which steam contained in the process fluid condenses and is deposited.
• a boiler feed pump conveys the resulting condensate into the
• Heat recovery steam generator where a preferably superheated steam quantity or a saturated steam quantity is generated.
• the steam generated is then fed back to the working fluid on the high-pressure side of the closed gas turbine, expanded in the turbine, cooled, and condensed.
• STIG machine is similar to a conventional STIG machine known per se.
• previously known STIG machines work in an open circuit with a correspondingly large amount of water.
• the closed gas turbine according to the invention recirculates the water. This is easily possible if the low-pressure part of the thermal power plant is operated under superatmospheric pressure; A substantial part of the contained steam is then separated from the gas cycle even above the ambient temperature.
• the pressure in the low-pressure part of the thermal power plant is above 5 bar, for example 10 bar.
• a low pressure in the range from 5 bar to 10 bar proves to be particularly advantageous with regard to the condensation temperatures, the power density, and the required dimensioning of the components: the smaller flow cross sections required are favorable on the one hand in terms of strength, but on the other hand increasing process pressures also require a correspondingly stronger dimensioning to ensure the necessary strength.
• the specified pressure range also proves to be more favorable here Compromise.
• the increased temperature level of the condensation enables the heat of condensation to be used in the steam generator.
• the largely free adjustment of the back pressure of the turbine allows conditions to be set which allow the exergetic potential of the steam to be optimally used without generating substantial moisture inside the turbine, even with an approximately constant pressure ratio and a widely varying heat supply and different upper process temperatures .
• the working media can be chosen freely, on the one hand with regard to the working gas as the primary process medium, and also with regard to the medium used for steam generation, which in the closed process does not have to be water. In this way, a gas turbine operating according to the process according to the invention can be optimally adapted to a wide variety of boundary conditions and can also be used very cheaply for low-temperature use.
• the process according to the invention can advantageously be used to implement a power plant in which a gas turbine group operating in the open circuit is followed by a thermal power plant operating according to the process according to the invention.
• a system can generally be constructed much more simply than a water-steam cycle conventionally used for waste heat recovery and, as explained above, is also particularly suitable for dealing with a strongly fluctuating waste heat supply.
• Figure 1 shows a first power plant, which works according to the thermal power process according to the invention
• Figure 2 shows an example of the use of the process according to the invention for using the waste heat of an open gas turbine system.
• the exemplary embodiments shown represent only a small instructive section of the invention characterized in the claims.
• FIG. 1 A first embodiment of a power generation system, which works according to the thermal power process according to the invention, is shown in FIG.
• the starting point of the illustrated embodiment is a closed gas turbine group.
• a compressor 1, a turbine 2, and a power consumer 3 are arranged on a common shaft 4.
• the compressor 1 as a compression means compresses a gaseous primary process fluid, in the simplest case air, but also any other gas in the closed process, whereby, for example, the realization of helium cycles offers advantages and has been carried out for a long time to an upper process pressure.
• Process fluids since it is a closed system, deviate significantly upwards and downwards from the ambient pressure, and in particular are a multiple of the ambient pressure.
• the compressed process fluid flows through means for supplying heat, in particular a heat exchanger, heater, 6 on the secondary side. This is operatively connected on the primary side to a charged firing system. Air is conveyed from the compressor of an exhaust gas charging group 10 under pressure through the secondary side of a preheater 9 to a combustion medium, burner 7. There, when a fuel is burned, a hot flue gas is produced which initially flows over the primary-side heat exchange surfaces 8 of the heater 6 and in the process releases heat to the process fluid flowing on the secondary side.
• the cooled flue gas continues to flow through the preheater 9 on the primary side and heats it Combustion air before it flows out into the environment through the turbine of the exhaust gas charging group 10; Residual heat could also be used, at least in part, for fuel preheating. Charging the combustion device reduces its size and also enables smaller heat exchangers.
• the heated and tensioned process fluid flows through the turbine 2 under relaxation and performance of technical work, which acts as a relaxation agent and power machine and drives the compressor 1 and the power consumer, generator 3, via the shaft 4.
• the relaxed primary process fluid flows through two heat sinks 11 and 13, and is completely fed back to the compressor, whereby the circuit closes.
• the first heat sink 11 is designed as a heat recovery steam generator.
• a feed water mass flow 12 brought up by a feed pump 18 is heated, evaporated, and at least slightly overheated.
• This steam 26 is introduced into the compressed primary process fluid upstream of the secondary side of the heater 6, and flows through the heater 6 together with the process fluid. Depending on the temperature of the live steam 26, this can of course also be introduced into the primary process fluid downstream or within the means for supplying heat , The steam also flows through the turbine 2 with the performance of technical work. Downstream of the turbine, at least some of the heat contained in the relaxed fluid is used in the waste heat steam generator for steam production.
• condensation of the steam sets in even at a comparatively high temperature, in such a way that the heat of condensation of the condensate separated at high partial pressure can be used again directly in the heat recovery steam generator.
• the partial pressure of the steam and the dew point temperature also decrease.
• Downstream of the heat recovery steam generator is a second heat sink 13, through which cooling water 19 flows on the secondary side and in which the process fluid is further dehumidified.
• the second heat sink defines the lower process temperature of the Thermal power process.
• Condensate 14 is fed back into the feed pump 18 through a filter 16 or a treatment mechanism that may otherwise be necessary, which also closes the water cycle.
• a condensate store 17 serves as an intermediate store for water.
• the dehumidified primary process fluid 24 is fed back to the compressor via an additional droplet separator, cyclone 5; any condensate 15 which has been separated there again is likewise returned to the water-steam cycle.
• the process according to the invention thus also makes it possible to use media other than water to generate steam, in particular also toxic media.
• Organic refrigerants for example Frigen, Freon, or ammonia, which are particularly suitable for pronounced low-temperature use, should be mentioned in particular. In such a case, however, it is important to prevent the medium, which is optionally also under superatmospheric pressure, from escaping on the low-pressure side.
• Shaft seals 31 are supplied with sealing air 25 during operation from a tap 32 of the compressor; in the case of a primary process fluid other than air and / or a toxic or otherwise harmful medium in the two-phase process, an independent barrier media system must also be provided here, even when it is at a standstill.
• the circuit is filled in accordance with the required output from an air reservoir 20 via a throttle element 21.
• the air reservoir is charged with ambient air via a compressor 22.
• compressed air is either via a backflow throttle 28 and a backflow cooler 29 drained back into the storage 20 or via a shut-off and throttling member 27 into the environment. Due to the variable circuit filling, which manifests itself in a variation of the low-pressure side pressure of the circuit, a very efficient power control is possible, in which the system is also designed in part-load operation with a design
• Pressure ratio is operated while the mass flow of the circulating medium varies in proportion to the gas density.
• the container 17 is therefore equipped with a level control, which opens a drain valve 23 when a certain fill level is exceeded.
• a power generation system of the type shown must of course be able to react quickly to sudden losses in the load in order to avoid harmful overspeeds.
• a speed measuring point 39 is therefore arranged, which acts on a shunt member 30 when a certain speed is exceeded, and discards part or all of the compressed process fluid directly into the low-pressure part.
• shut-off and throttling elements 27 and / or 30 can also be opened, which has an immediate influence on the system performance, in comparison to the intervention in the fuel supply to the burner 7, which is only effectively delayed by the slow heater 6 comes into play.
• the process according to the invention can of course also be implemented with a multi-shaft gas turbine group. Cooling during the compression process or supplying heat during expansion can of course also be readily provided in a manner known per se.
• FIG. 2 shows a power plant which uses a power plant operating according to the process according to the invention to use waste heat from an open gas turbine plant.
• a gas turbine group 100 drives a generator 3. It is without depicting a limitation a gas turbine group with sequential combustion, as is well known from EP 620 362 and numerous publications based thereon. Without going into details, their basic function will be explained shortly.
• a compressor 101 and two turbines 103 and 105 are arranged on a common shaft. The compressor 101 draws in an amount of air 106 from the environment. In the compressed air, fuel is mixed in the first combustion chamber 102 and burned there. The flue gas is partially expanded in the first turbine 103, for example with a pressure ratio of 2.
• the flue gas which still has a high residual oxygen content of typically over 15%, flows into a second combustion chamber 104, where further fuel is burned.
• This reheated flue gas is expanded in the second turbine 105 to approximately ambient pressure - apart from pressure losses in the exhaust gas tract - and flows out of the gas turbine group as hot exhaust gas 107, at temperatures which are, for example, 550-600 ° C. under high load from.
• means for using waste heat, heat exchanger 6 are arranged, in which the exhaust gas cools further before it flows into the atmosphere as cooled exhaust gas 108.
• the heat exchanger 6 arranged as a means of utilizing waste heat transfers what heat from the exhaust gas of the open gas turbine group 100 to the circuit of a closed one
• the compressor of the closed gas turbine group which conveys a gaseous primary process fluid to an upper process pressure, is divided into several partial compressors 1 a, 1 b, 1 c connected in series.
• An intermediate cooler 41 with a downstream condensate separator 42 is arranged downstream of the first compressor; condensate accumulating there is led into a condensate store 17.
• An injection cooler 44 for further cooling of the partially compressed primary process fluid is arranged between the partial compressors 1b and 1c. If a sufficiently large amount of liquid is injected here, drops penetrate into the partial compressor 1c and provide further continuous internal cooling there.
• Compressed process fluid flows in counterflow with the exhaust gases 107, 108 of the open gas turbine group through a first partial heat exchanger 6a of the means 6 for waste heat utilization. Downstream of the first partial heat exchanger 6a, the primary process fluid is mixed with a quantity of steam 26, and together with this flows through the second partial heat exchanger 6b.
• the point of supply for the amount of steam 26 is selected at a temperature-appropriate point such that the steam temperature is not higher than the temperature of the exhaust gas from which heat is to be transferred.
• the entire amount of fluid heated in the heat exchanger 6b flows into a turbine 2, and is relaxed there with the output of shaft power, the turbine 2 is arranged with the partial compressors 1 a, 1 b, 1 c on a common shaft 4, and is via a automatically acting coupling 109 can be coupled to the generator 3; this single-shaft design of combination systems is familiar to the person skilled in the art.
• the relaxed fluid flow from the turbine 2 flows into a first heat sink 11, in which the entire fluid flow is cooled and at least part of the steam is condensed. Condensate is separated in a first separator 5a and passed into a condensate store 17.
• a second heat sink 13 defines the lower process temperature of the primary process fluid; condensate still occurring is separated off in a second separator 5b and likewise passed into the condensate store 17.
• the dried and cooled process fluid 24 then flows back into the first partial compressor 1a, as a result of which the circuit of the primary process fluid is closed.
• Condensate from the condensate store 17 is conveyed by a feed pump 18 as the cooling medium and feed water 12 - in the closed circuit, of course, as mentioned above, it can also be a liquid other than water - to the first heat sink 11 designed as a steam generator.
• this feed water is heated by means of the heat to be dissipated in the first heat sink, evaporated, and at least slightly overheated as fresh steam 26 is returned to the thermal power process.
• Liquid is also pumped from the condensate container 17 to the injection cooler 44 by a pump 43 promoted.
• a shunt valve makes it possible to direct process fluid bypassing the turbine 2 directly from the high-pressure part to the low-pressure part of the power plant, which is necessary for rapid load reductions.
• a high-pressure container 45 is arranged in connection with the high-pressure part of the closed gas turbine group. In an operating state, this is charged by a compressor 48 via a recooler 47, a condensate separator 50, and a non-return element 46.
• This charging process removes process fluid from the circuit, which lowers the pressure level of the overall process, and consequently the circulated mass flow. This means that the power can be reduced while the pressure ratio and operation of the gas turbine group remain the same at or near the design point.
• the high-pressure fluid stored in the container 45 is returned to the circuit via the shut-off and throttling member 49, as a result of which the density of the circulated medium and thus the mass flow and the output are permanently increased.
• the feeding of fluid from the high pressure container 45 acts directly as an increase in the turbine mass flow.
• the energy stored in a gas volume can be made available very quickly and is therefore suitable for spontaneous increases in performance, as are required, for example, when supporting a network with frequency.
• the performance potential of the closed gas turbine group can be easily varied. This is where essential advantages of the power plant shown in FIG. 2 can be seen. If, in fact, strongly fluctuating waste heat potentials of the open gas turbine group 100 are available, the process using waste heat can very easily and in a manner known per se via the pressure level of the overall system by shifting process fluid between fluid circulating in the circuit and fluid stored in the high-pressure container 45 to the different performance potentials be adjusted. This also has 26 advantages with regard to the steam introduced. If the exhaust gas temperature of the gas turbine exhaust gas 107 drops, and thus the maximum possible inlet temperature of the turbine 2, the potential effects are that they are excessive Condensation occurs in the turbine 2, and on the other hand, overheating of the live steam in the steam generator 11 is no longer possible.
• a lowering of the total pressure of the closed gas turbine process enables an adaptation in such a way that the steam is always sufficiently overheated when it enters the turbine 2.
• a sliding pressure mode for the steam can be implemented in a simple and expedient manner.
• the use of waste heat tends to be somewhat poorer, resulting in significantly greater flexibility in use.
• the compressor outlet temperature of the closed process should be as low as possible; In the case of a gas turbine group which works according to the process according to the invention, this can be conveniently achieved in addition to the arrangement of intercoolers by means of a relatively low pressure ratio in the range from approximately 3 to 8.
• the comparatively high turbine outlet temperature is negligible, since the exhaust gas heat is recuperated by the waste heat steam generator, and is rather advantageous in terms of the steam quality generated.
• the low power of a gas turbine process with a low pressure ratio in relation to the compressor mass flow is compensated for by the additional steam mass flow which is passed through the turbine 2.
• 5a, 5b condensate separator Heat exchangers, heat exchangers, heaters

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• 2003
  • 2003-03-11 DE DE50305418T patent/DE50305418D1/de not_active Expired - Lifetime
  • 2003-03-11 EP EP03714950A patent/EP1483483B1/fr not_active Expired - Lifetime
  • 2003-03-11 AU AU2003219156A patent/AU2003219156A1/en not_active Abandoned
  • 2003-03-11 AT AT03714950T patent/ATE343048T1/de not_active IP Right Cessation
  • 2003-03-11 WO PCT/EP2003/050053 patent/WO2003076769A1/fr active IP Right Grant
• 2004
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