DE102015213862B3 - Combustion power plant with improved efficiency due to corrosion-resistant heat exchangers - Google Patents

Combustion power plant with improved efficiency due to corrosion-resistant heat exchangers

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Publication number
DE102015213862B3
DE102015213862B3 DE102015213862.3A DE102015213862A DE102015213862B3 DE 102015213862 B3 DE102015213862 B3 DE 102015213862B3 DE 102015213862 A DE102015213862 A DE 102015213862A DE 102015213862 B3 DE102015213862 B3 DE 102015213862B3
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Prior art keywords
working fluid
incinerator
heat
hot air
heat exchanger
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DE102015213862.3A
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German (de)
Inventor
Michael Beckmann
Sebastian Grahl
Nina Hack
Simon Unz
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Technische Universitaet Dresden
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Technische Universitaet Dresden
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01KSTEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K5/00Plants characterised by use of means for storing steam in an alkali to increase steam pressure, e.g. of Honigmann or Koenemann type
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
    • F28D15/02Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
    • F28D15/04Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D21/00Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
    • F28D21/0001Recuperative heat exchangers
    • F28D21/0003Recuperative heat exchangers the heat being recuperated from exhaust gases
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E50/00Technologies for the production of fuel of non-fossil origin
    • Y02E50/10Biofuels
    • Y02E50/12Gas turbines for biofeed

Abstract

The invention relates to a combustion power plant with an incinerator in which a fuel is burned with the development of highly corrosive flue gases, a hot air turbine unit, which operates with a gaseous working fluid, and one or more heat exchangers, or the transfer of thermal energy from the incinerator to the working fluid are suitable. At least one of the heat exchangers includes at least one high temperature ceramic heat pipe having a first end disposed within the combustor and a second end disposed outside the combustor and within the flow path of the working fluid of the hot air turbine assembly. The combustion power plant also has a line which is suitable for supplying the exhaust air of the hot air turbine unit directly to the incinerator as combustion air. Thus, the efficiency of the entire system of incinerator and turbine and the service life of the heat exchanger (s) is increased by better protection against corrosion, oxidation / reduction or abrasion.

Description

  • The invention relates to a combustion power plant in which arise during combustion highly corrosive flue gases, in particular a waste or biomass incineration plant, in which both the efficiency of energy conversion and the corrosion resistance of the heat transfer devices used are improved.
  • In waste heat and power plants (MHKW) and biomass cogeneration plants (BmHKW) for the thermal treatment of waste or biomass, biomass fractions or refuse derived fuels, the thermal energy generated is converted in addition to their possible direct use in electrical energy using gas or steam turbines. In this case, the thermal energy can be removed from the incinerator via a heat exchanger the flue gas stream and fed to the working fluid of a turbine. In this case, the water or steam for a steam turbine or the gas for a gas turbine by means of one or more located directly in the incinerator (in the furnace or in one of the flues) pipe systems or via a heat exchanger located outside the incinerator, which is connected to these pipe systems is, warmed up. Waste-to-energy plants and biomass power plants with such a generation of electrical energy via steam or gas turbines whose working medium are heated via pipe systems in the incinerator are, for example, from RA Zahoransky: "Energietechnik", Vieweg + Teubner, Wiesbaden 2009, 4th edition, chapter 14 and 16 known. The pipe systems in the incinerator are also referred to as heat transfer surfaces.
  • Also the US 2008/0245052 A1 sees heat transfer from a combustion gas to the working fluid of a gas turbine by means of a conventional, tubular heat exchanger through which the working fluid flows, as well as a supply of the exhaust gas of the gas turbine into the combustion chamber.
  • The US Pat. No. 8,205,456 B1 describes a system in which heat is removed from an exhaust gas flow of two combustion systems by means of a plurality of heat exchangers and thus the working fluid of two gas turbines is heated. The figures suggest conventional heat exchangers with pipes through which hot or cold air flows. The exhaust gas of the second gas turbine is returned to the second combustion system.
  • From the US 4,479,355 A For example, a system is known in which both steam for a steam turbine obtained, and the working fluid for a gas turbine is heated by means of a heat exchanger. Again, the working fluid is passed through pipes directly through a convection zone of the exhaust path of an incinerator, while the exhaust gas of the turbine is returned to the incinerator.
  • However, the flue gas streams of such plants have a very large corrosion potential, so that the heat transfer surfaces must be protected from the corrosive attack of hot gases. Also, high quality metal alloys (e.g., nickel based) exhibit increased corrosion (e.g., high temperature chlorine corrosion) at the high temperatures involved and high levels of chlorine and alkali flue gas, depending on the feed. Oxidizing and / or local reducing atmospheres can also be expected in these incinerators. In addition, the flue gas has a high proportion of ash and unburned fuel components, which have an abrasive effect on surfaces located in the flue gas flow, in particular at points with flow deflection.
  • The protection of the heat transfer surfaces from the attack of the flue gas is, for example, realized by the use of radiant superheaters, which reduce the temperature of the flue gas and thus reduce the corrosive properties of the subsequent meeting on the heat transfer surfaces flue gas. In addition, bulkhead heaters are known which have a ventilated plate system in which the steam-carrying tubes of the heat transfer surfaces are arranged behind ceramic or metallic protective walls and thus are no longer directly exposed to the flue gas.
  • However, this means that the radiation superheaters or the protective walls are exposed to a strong thermal and corrosive and / or abrasive load, which leads to a limited service life of these elements. The use of radiant superheaters decreases the efficiency of the system due to the reduced heat extraction by the lower temperature of the incident on the heat transfer surfaces flue gas and by the reduced, but still occurring corrosion of the heat transfer surfaces or a deposition of flue gas particles on the heat transfer surfaces. When using protective walls, the heat extraction is reduced due to the additional thermal resistance. This also reduces the efficiency of the entire system, which is directly proportional to the decoupled heat quantity.
  • Another possibility is the selection of other and more suitable materials for the heat transfer surfaces for the corresponding loads. Here were, for example, the application of less corrosive metallic protective coatings (cladding) or the use of ceramic materials as heat transfer surfaces tested, such as in the US 4,377,072 A described.
  • Ceramic tubes are also known from other publications. That's how it describes EP 0 571 233 B1 a staged furnace assembly having two combustion furnaces, each furnace including heat exchangers for heating a working gas of a gas turbine. The heat exchangers are described as high-temperature heat exchangers containing heat-resistant ceramic surfaces using tubes, so that these heat exchangers consist of tubes within the respective furnace, through which the working fluid flows. Part of the exhaust gas of the gas turbine is supplied as combustion air to the first combustion furnace.
  • Also the US 2008/0118310 A1 describes a system comprising a combustion furnace, a ceramic heat exchanger and a turbine unit with a gas turbine. In the ceramic heat exchanger, hot combustion air flows through the ceramic tubes and heats the working medium of the gas turbine flowing past these tubes.
  • However, none of these methods led to the desired success or brought other problems. For example. Although ceramic materials are inherently resistant to high temperatures and corrosive attack, they are only of low load capacity in the design as tubes under internal pressure, as is already the case in moderate steam cycles. In addition, the connection of the ceramic tubes to metallic portions of the fluid circuit, which are located outside of the incinerator, difficult.
  • It is therefore an object of the present invention to increase the efficiency of the overall system of incinerator and turbine and to better protect the heat transfer surfaces from corrosion, oxidation / reduction or abrasion.
  • This object is achieved by a system according to claim 1 and a method according to claim 10. Advantageous system variants / further developments are described in the dependent claims.
  • A combustion power plant according to the invention includes an incinerator in which a fuel is burned to produce highly corrosive fumes, a hot air turbine unit operating with a gaseous working fluid, and one or more heat exchangers suitable for transferring thermal energy from the incinerator to the working fluid , At least one of the heat exchangers includes at least one high temperature ceramic heat pipe having a first end disposed within the combustor and a second end disposed outside the combustor and within the flow path of the working fluid of the hot air turbine assembly. The combustion power plant also has a line which is suitable for supplying the exhaust air of the hot air turbine unit directly to the incinerator as combustion air. Here, exhaust air of the hot air turbine unit is understood to mean the working fluid emerging from the hot air turbine unit after the expansion.
  • An advantage of the used high-temperature ceramic heat pipes for decoupling the thermal energy from the incinerator is that these heat pipes are made entirely of ceramic material and thus have a very low susceptibility to corrosion and abrasion with very good heat transfer and the working fluid of the hot air turbine unit physically completely from the combustion plant is decoupled - so no gas flows turbine branch directly through a pipe in the incinerator. This results in longer life of the heat exchanger. Moreover, due to its corrosion and heat resistance, the heat exchanger according to the invention can now be arranged at positions in the incinerator which have a higher temperature and thus enable heat extraction at a higher temperature level. Thus, the gaseous working fluid of the hot air turbine unit can be heated to a higher temperature (than at other positions of the incinerator or as with metallic materials), which ultimately leads to a higher efficiency of the hot air turbine used and thus to a higher efficiency of the entire system.
  • By returning the working fluid of the hot air turbine unit to the incinerator, the combustion process can be made more efficient since the turbine exhaust air, which is warmer than normal air, is used to dry and / or burn the fuel. Thus, a higher Enthalpiestrom with the same fuel use in the flue gas is available as without recirculation.
  • Both measures - higher temperature level of the heat extraction and higher flue gas enthalpy with recycling of the working fluid of the hot air turbine unit - allow an increase in the overall degree of efficiency of the combustion power plant.
  • Preferably, the at least one heat exchanger is installed in the combustion chamber (also called first train) or in the second or third train of the incinerator. There will be a lot high temperatures of the flue gas of about 900 ° C to 1400 ° C reached. In addition, in the combustion chamber or in the second train of heat radiation transmitted by heat flow is particularly high. Furthermore, the installation of the at least one heat exchanger is also possible in a further train of the incinerator, ie at locations further away from the combustion chamber of the flue gas path, but reduce the advantages of the used ceramic high-temperature heat pipes with increasing distance from the combustion chamber compared to conventional heat exchangers. Due to the higher temperature of the flue gas in the first train, with appropriate design of the heat exchanger with ceramic high-temperature heat pipes, the working fluid can be heated to much higher temperatures than conventional heat exchangers. In addition, the greater the temperature difference between flue gas and "cold" working fluid, the higher the efficiency of the heat exchangers. Thus, the heat exchanger according to the invention can be made smaller than a conventional heat exchanger for the same amount of heat transferred.
  • The at least one ceramic high-temperature heat pipe may have a capillary structure (heat pipe) or be formed without it (thermosyphon).
  • In heat pipes without capillary structure returns to the working fluid of the hot air turbine unit condensed working fluid in the heat pipe by the heat from the cold to the hot side of the heat pipe back to the heat. Therefore, such heat pipes are installed vertically or obliquely with an inclination angle 0 <α ≤ 90 ° relative to the horizontal in the incinerator, so that they protrude vertically or obliquely from above or obliquely from the side into the incinerator. The angle of inclination must be sufficient for the return of the working medium in the heat pipe by gravity.
  • Does the heat pipe used a capillary structure, so that the working fluid of the heat pipe flows back through the capillary forces back to the hot side of the heat pipe, the heat pipe can be installed at any angle, especially horizontally, in the incinerator. Thus, the heat pipe can protrude, for example, horizontally or obliquely from the side into the furnace.
  • Preferably, at least one of the heat exchangers contains a plurality of ceramic high-temperature heat pipes, so that a larger amount of heat at the respective installation position can be transmitted to the working fluid of the hot air turbine unit. In this case, the individual heat pipes in their arrangement at a distance from each other, which ensures sufficient air flow through the heat exchanger in the incinerator even with adhering particles from the flue gas stream. In particular, it should be ensured that the flue gas flow is not affected in its flow and / or the forces generated by the flue gas flow and acting on the heat pipes exceeds the mechanical integrity of the heat pipes. The number of heat pipes in a heat exchanger and their arrangement within the heat exchanger (in one or more rows and / or columns, offset or aligned with each other, with uniform or uneven distance from each other, etc.) depends in particular on the accessibility and the space available at the installation of the heat exchanger , the usable drainable thermal energy as well as the thermal and mechanical load of the heat pipes.
  • Advantageously, the combustion power plant includes a plurality of heat exchangers according to the invention, which transmit the thermal energy from the incinerator to the working fluid.
  • If the hot air turbine unit includes only one turbine, then all the heat exchangers are sequentially arranged in the flow path of the working fluid, wherein a heat exchanger, which is installed at a location of the flue gas path further away from the combustion chamber, is arranged in the flow path of the working fluid farther from the turbine than a heat exchanger , which is installed at a location closer to the combustion chamber of the flue gas path. Thus, the working fluid of the hot air turbine unit first flows through the "coldest" heat exchanger to a next, somewhat "warmer" heat exchanger and so on, until it finally enters the turbine of the hot air turbine unit after passing through the "hottest" heat exchanger. The working fluid is heated gradually and can absorb a larger amount of heat and thus achieve a higher end temperature than when passing only one heat exchanger.
  • Alternatively, the hot air turbine unit may include a plurality of turbines, wherein the working fluid is split among the plurality of turbines and each turbine is assigned a fractional working fluid. In this case, each specific heat exchanger is arranged only in the flow path of the partial working fluid of a specific turbine. In other words, each heat exchanger transfers thermal energy only to a specific sub-working fluid of a specific turbine, but multiple heat exchangers can also transfer thermal energy to a specific sub-working fluid. This allows each specific turbine in their characteristics in terms of structure and performance of the with the help of the respective heat exchanger or the respective heat exchanger, which are arranged in the flow path of the sub-working fluid of this specific turbine, achievable temperatures of the working fluid can be adjusted.
  • However, the working fluid of the hot air turbine unit can also be divided first on the individual turbines, after it has flowed through each heat exchanger in succession.
  • In specific embodiments of the system according to the invention, the hot-air turbine unit includes a gas turbine with a combustion chamber or a gas turbine without a combustion chamber or an exhaust gas turbocharger with an expansion turbine. Here, a gas turbine (with or without combustion chamber) is understood to mean a conventional gas turbine used for power generation in power plants or industry with a power of between a few hundred kW and a few MW. In contrast, exhaust turbocharger with an expansion turbine as a turbine unit from turbocompound systems, for example. From the automotive industry, known and provide benefits in the range of less than a few hundred kW. Particularly in this area of smaller and medium performances, the exhaust gas turbochargers have a significant cost advantage over micro gas turbines or industrial gas turbines. Gas turbine without combustor have the advantage that they do not require additional energy or fuel supply due to the saving of the additional combustion process to increase the temperature and the working fluid of the turbine is not burdened with combustion products. The type of construction of the turbine in the hot air turbine unit depends on the conditions of the working fluid (temperature, pressure), the power extractable from the combustion process in the combustor, the cost to install for the hot air turbine unit, and the hot air turbine unit's intended use. If only the efficiency of the combustion power plant to be increased, so the use of a gas turbine without combustion chamber is sufficient, while providing a very large power through the hot air turbine unit rather a gas turbine with combustion chamber is used.
  • The combustion power plant is preferably a waste incineration plant or a biomass or substitute fuel incineration plant. In these plant types, the flue gas is particularly aggressive (corrosive, oxidizing / reducing and / or abrasive), so that the use of a ceramic high-temperature heat pipe is particularly advantageous. In addition, garbage or biomass as fuel often have a high humidity and low calorific value. A preheated combustion air here supports the drying of the fuel, so that less chemically bound energy has to be expended from the fuel for it.
  • The inventive method for operating a combustion power plant according to the invention includes the use of a high temperature ceramic heat pipe for at least one of the heat exchangers, wherein a first end of the ceramic high temperature heat pipe in the incinerator and a second end of the ceramic high temperature heat pipe outside the incinerator are arranged and the working fluid of the hot air turbine unit flows around the second end.
  • In addition, the exhaust air of the hot air turbine unit is fed directly to the combustion system as combustion air.
  • Advantageously, the incinerator is initially operated without the at least one heat exchanger in a trial operation. This is possible for newly designed and constructed systems as well as for systems already in use. During the trial operation, the mechanical loads and the atmosphere present in the combustion chamber and in the flues of the incinerator are examined with regard to their temperature and their corrosive, abrasive and oxidising or reducing action. Based on the examination results obtained, the installation position, the type, the material and the dimensions of the at least one ceramic high-temperature heat pipe are subsequently selected and the at least one selected ceramic high-temperature heat pipe is installed in the incinerator.
  • In the installation position, in particular the installation location at which the heat exchanger is installed, and the installation position is selected. In particular, the combustion chamber and the second and the third train of the incineration plant come into consideration as the installation site, but other trains can also be used for the installation of such a heat exchanger. Under installation position is understood here in particular the angle to the earth's surface, which also depends on the type of heat pipe - whether with or without capillary structure. Under the material of the heat pipe not only the ceramic material of the cladding tube itself, but also the material of the working medium is understood. Particularly suitable ceramic materials for the cladding tube are silicon carbides (SiC, SSiC) or aluminum oxides or aluminum nitrides. The choice of this material depends in particular on the temperature of the flue gas at the installation site and on the resistance of the ceramic material with respect to corrosion, abrasion or oxidation / reduction Components of the flue gas. For example, Zn, K, Li or Na are used as the working medium. When choosing the working medium in particular the working temperatures on the hot side of the heat pipe, ie on the side of the heat pipe located in the incinerator, and on the cold side of the heat pipe, ie on the located in the working fluid of the hot air turbine process side of the heat pipe, of importance. The dimensions of the heat pipe are understood to mean the diameter and in particular the length of the heat pipe. The length of the heat pipe is important for the amount of heat transferable, but is limited by the forces acting on the heat pipe. In particular, the weight force causes a tensile and depending on the installation position, a bending load of the heat pipe. These forces can be absorbed by additional support plates and thus the load on the heat pipe can be reduced. In addition, the forces generated by the flue gas flow and acting on the heat pipe forces are observed. The heat pipe must be designed so that no natural oscillations are excited by the flue gas flow. Also possible deposits of particles from the flue gas on the heat pipe to be installed are to be considered, as these can increase the mass of the heat pipe on the one hand and on the other hand can change the flue gas flow.
  • For the selection of the individual parameters of the heat pipe on the basis of given boundary conditions or environmental factors, those skilled in the calculation method are known. Since different parameters and factors, such as, for example, installation location and type, materials and dimensions of the heat pipe, influence each other, it is advantageous to test different variants of the parameters by means of simulations, so that an optimum for the heat transfer is achieved. In addition, the creep rupture strength of the heat pipes must be ensured for a minimum travel time, which does not fall below a planned time interval to the next revision of the boiler.
  • Preferably, sample samples of the ceramic heat pipes are introduced in trial operation at certain, already recognized as advantageous installation positions and after a certain operating time, eg. 14 days, with respect to their corrosion, abrasion and oxidation / reduction resistance and the deposits occurred.
  • Preferably, at least one heat exchanger is realized by a plurality of ceramic high temperature heat pipes, i. at a location several heat pipes are installed parallel to each other. In this case, the distance between the individual ceramic high-temperature heat pipes to each other within the heat exchanger is selected based on the examination results obtained.
  • Of course, several heat exchangers can be installed from ceramic high-temperature heat pipes at different locations of the incinerator, in which case each heat exchanger with respect to the type, material and dimensions of the ceramic high-temperature heat pipe or the distance between individual heat pipes with each other according to the present at this location Conditions is selected.
  • Preferably, the thermal energy is transferred from the incinerator to the working fluid of the hot air turbine unit by means of a plurality of heat exchangers.
  • In one embodiment, the working fluid in the hot air turbine unit is supplied to only one turbine. In this case, the working fluid flows through several or all heat exchangers in succession, wherein it flows from a heat exchanger which is installed at a location of the flue gas path farther away from the combustion chamber, to each built closer to the combustion chamber in the flue gas path heat exchanger.
  • Alternatively, the working fluid in the hot air turbine unit is supplied to a plurality of turbines, wherein the working fluid is divided among the plurality of turbines and each turbine is assigned a partial working fluid. The partial working fluid of a specific turbine in each case flows through a specific heat exchanger.
  • In a further alternative embodiment, the working fluid of the hot air turbine unit flows through several or all heat exchangers in succession, as described above, but is then divided into several turbines, which are each coupled to a specific generator. Optionally, the working fluid of the hot air turbine unit may also be provided by a plurality of compressors each coupled to one of the generators.
  • In the following, the invention will be illustrated with reference to embodiments and figures.
  • Show it:
  • 1 a schematic representation of the combustion power plant according to the invention ( 1 ) with an incinerator ( 10 ), a heat exchanger ( 20 ) and a hot air turbine unit ( 30 ).
  • 2 a schematic cross section through an incinerator ( 10 ), in the possible installation locations of the heat exchanger ( 20 ) Marked are.
  • 3 a schematic representation of a combustion power plant with several heat exchangers ( 201 - 203 ), in which the working fluid of the hot air turbine unit ( 30 ) all heat exchangers ( 201 - 203 ) flows through one after the other.
  • 4 a schematic representation of a combustion power plant with several heat exchangers ( 201 - 203 ), in which the working fluid of the hot air turbine unit ( 30 ) is divided into several partial working fluids, each associated with a specific turbine, and a specific heat exchanger ( 201 - 203 ) is only flowed through by a specific partial working fluid.
  • 5 a schematic representation of a combustion power plant with several heat exchangers ( 201 - 203 ), in which the working fluid of the hot air turbine unit ( 30 ) first all heat exchangers ( 201 - 203 ) is successively flowed through and then divided into several sub-working fluids, each associated with a specific turbine.
  • embodiments
  • 1 shows schematically a combustion power plant according to the invention ( 1 ) with an incinerator ( 10 ), a heat exchanger ( 20 ) and a hot air turbine unit ( 30 ). In the incinerator, a fuel ( 11 ), eg waste or biomass, burned, whereby a flue gas ( 12 ) arises. The hot air turbine unit ( 30 ) contains a compressor ( 31 ), an expansion turbine ( 32 ) as well as a generator ( 33 ), in which electrical power from the mechanical work of the expansion turbine ( 32 ) is produced. The compressor generates a compressed, gaseous working fluid from an externally supplied fresh gas ( 34 ), with the help of the heat exchanger ( 20 ) and then in the expansion turbine ( 32 ) is relaxed. Optionally, the expansion turbine ( 32 ) still be provided with a combustion chamber in which the working fluid ( 34 ) is heated even further when the temperature of the heat exchanger ( 20 ) heated working fluids ( 34 ) not for efficient operation of the expansion turbine ( 32 ) is sufficient. The exhaust air ( 36 ) of the expansion turbine ( 32 ) is used as combustion air ( 13 ) into the incinerator ( 10 ). This can be done directly or the exhaust air ( 36 ) can optionally before feeding into the incinerator ( 10 ) Heat by means of a recuperator ( 40 ) are withdrawn. The recuperator ( 40 ) may be any known heat exchanger, so for example. A pipe system in which a fluid flows, or even one or more heat pipes. The extracted heat can, for example. For preheating a fresh combustion air ( 14 ), the optional incinerator ( 10 ), or used for other purposes.
  • For heat transfer from the incinerator ( 10 ) on the working fluid ( 34 ) of the hot air turbine unit ( 30 ) is a first end ( 21 ) of the heat exchanger ( 20 ), which consists of at least one ceramic high-temperature heat pipe, in the flow path of the flue gas ( 12 ) in the incinerator ( 10 ), while a second end ( 22 ) of the heat exchanger ( 20 ) in the flow path of the working fluid ( 34 ) of the hot air turbine unit ( 30 ) is arranged. The installation position and the nature of the at least one heat pipe (with or without capillary structure), the ceramic material, the working medium and the dimensions of the at least one heat pipe and possibly the number of heat pipes and their distance from each other are of the in the incinerator ( 10 ) and the parameters of the expansion turbine ( 32 ) and can be calculated or simulated by a specialist. In a test facility, SSiC ceramic heat pipes were tested with zinc as the working medium, having an inner diameter of 12 or 14 mm, an outer diameter of 22 mm and a total length of 77.5 cm or 1 m. The dimensions of the heat pipes depend mainly on the application plant. For MW power plants, larger heat pipes make sense.
  • Regarding 2 Now, the installation position of a heat exchanger ( 20 ). Shown is a schematic cross section through an incinerator ( 10 ), which has a firebox ( 101 ), a second move ( 102 ) and a third move ( 103 ) as well as several fly ash discharges ( 104 ) and a flue gas outlet ( 105 ) having. The heat exchanger ( 20 ) can in the firebox ( 101 ), for example at the locations marked "A" or "D", or in the second train ( 102 ) or in the third move ( 103 ) in the places marked "B" or "C". The installation locations "A", "B" and "C" are suitable for both heat pipes without capillary structure and for heat pipes with capillary structure, since the heat pipe is vertically from above into the incinerator ( 10 ) protrudes. At installation location "D", the heat pipe protrudes from the side into the combustion chamber ( 101 ), with the heat pipe running horizontally or diagonally to the earth's surface. When arranged horizontally, only heat pipes with capillary structure can be used, while at high angles of inclination heat pipes without capillary structure can be used. Preferred installation locations are the locations "A" and "D", since there the temperatures in the incinerator are very high and the heat radiation transmitted by heat flow is particularly high.
  • In 2 are next to the heat exchanger ( 20 ) yet further means for utilizing the heat energy of the flue gas shown schematically, as are known in the prior art. These are in particular a protective evaporator ( 50 ), Superheater packages ( 60 ) and economiser packages ( 70 ), which are used to operate a steam turbine unit or to heat other work equipment.
  • With reference to the 3 to 5 Embodiments for an inventive combustion power plant with several heat exchangers ( 201 - 203 ). At which locations the individual heat exchangers ( 201 - 203 ) in the incinerator ( 10 ) are only relevant in so far as the first heat exchanger ( 201 ) in the flow path of the flue gas ( 12 ) (Flue gas path 121 ) is positioned within the combustion chamber or closer to the combustion chamber than the second heat exchanger ( 202 ) and this in turn closer to the combustion chamber than the third heat exchanger ( 203 ) and so on. The return of the working medium of the hot-air turbine unit ( 30 ), ie the exhaust air ( 36 ), into the incinerator ( 10 ) is not shown in the sense of clarity of the figures.
  • 3 schematically shows a first embodiment in which the working fluid of the hot air turbine unit ( 30 ) all heat exchangers ( 201 - 203 ) flows through one after the other. The hot air turbine unit ( 30 ) has a compressor ( 31 ), an expansion turbine ( 32 ) and a generator ( 33 ) on. The working fluid ( 34 ) first flows through the heat exchanger furthest away from the combustion chamber, here the third heat exchanger ( 203 ), then by the opposite to the flow direction of the flue gas ( 12 ) in the flue gas path ( 121 ) as the next built-in heat exchanger, here the second heat exchanger ( 202 ), and so on and finally by the heat exchanger positioned in the combustion chamber or next to the combustion chamber, ie the first heat exchanger ( 201 ). Since the temperatures at the second ends of the heat exchangers ( 201 - 203 ), ie at the "cold" ends, with the removal of the heat exchanger ( 201 - 203 ) sinks from the combustion chamber, the working fluid ( 34 ) from the "coldest" heat exchanger ( 203 ) to the "next-coldest" heat exchanger ( 202 ) and ultimately the "hottest" heat exchanger ( 201 ) and is heated further and further. Thus, the heat energy of the flue gas ( 12 ) particularly effective on the working fluid ( 34 ) be transmitted.
  • 4 schematically shows a second embodiment in which the working fluid of the hot air turbine unit ( 30 ) to several partial working fluids ( 341 - 343 ), each of a specific expansion turbine ( 321 - 323 ), and a specific heat exchanger ( 201 - 203 ) in each case only by a specific partial working fluid ( 341 - 343 ) is flowed through. In the example shown, the hot air turbine unit ( 30 ) a compressor ( 31 ), which provides a compressed working fluid, which is subsequently mixed with three partial working fluids ( 341 - 343 ) is divided. The compressor ( 31 ) via a separate motor ( 37 ), as in 4 represented by one of the expansion turbines ( 321 - 323 ) are driven by a shaft. But it is also possible that each part working fluid ( 341 - 343 ) is generated by a separate compressor when the associated specific expansion turbines ( 321 - 323 ) work with different working pressures. In turn, each of the separate compressor via a motor or by one of the expansion turbines ( 321 - 323 ) are driven by a shaft. In addition, every expansion turbine ( 321 - 323 ) a generator ( 331 - 333 ). In the illustrated case, each partial working fluid flows through ( 341 - 343 ) only one specific heat exchanger ( 201 - 203 However, a partial working fluid can also flow through several heat exchangers in succession, as with reference to 3 was explained. Since each partial working fluid ( 341 - 343 ) only one heat exchanger ( 201 - 203 ), it is - with the same size and design of the respective heat exchanger ( 201 - 203 ) - heated to a lower temperature than the total working fluid ( 34 ) at the in 3 illustrated embodiment. Every expansion turbine ( 321 - 323 ) can in their parameters to the for the respective sub-working fluid ( 341 - 343 ) achievable temperature can be adjusted so that, if necessary, a higher overall efficiency of the combustion power plant than when using only one expansion turbine is achieved. The exhaust air of the individual expansion turbines ( 321 - 323 ) can each be supplied separately or via a common line of the incinerator. The advantage of this embodiment is the flexibility of the entire plant by the operation of only one or more expansion turbines ( 321 - 323 ).
  • 5 shows a third embodiment, in which the working fluid ( 34 ) of the hot air turbine unit ( 30 ) on several specific expansion turbines ( 321 - 323 ) after all heat exchangers ( 201 - 203 ) has flowed through. Every expansion turbine ( 321 - 323 ) is a generator ( 331 - 333 ). Since in the example shown each expansion turbine ( 321 - 323 ) drives a compressor, the hot air turbine unit ( 30 ) also a corresponding number of compressors ( 311 - 313 ), each containing a portion of the compressed working fluid ( 34 ). However, only one compressor can be used, if this one of the several expansion turbines ( 321 - 323 ) or operated entirely separately. Since the working fluid ( 34 ) all heat exchangers ( 201 - 203 ), it is heated to a higher temperature than the in 4 illustrated embodiment, so that the expansion turbines ( 321 - 323 ) have a higher efficiency. Via control valves ( 351 - 353 ), which are optional in the supply lines of the expansion turbines ( 321 - 323 ), the working fluid ( 34 ) depending on the temperature reached only one or less than all expansion turbines ( 321 - 323 ). Thus, each expansion turbine ( 321 - 323 ) whose parameters are based on the temperature reached and the mass flow of the working fluid ( 34 ) are best adapted. Thus, the third embodiment offers high performance flexibility of the combustion power plant ( 1 ) with high total efficiency of the plant. The exhaust air of the individual expansion turbines ( 321 - 323 ) can each be separated or via a common line of the incinerator ( 10 ) are supplied as preheated combustion air.
  • All embodiments and embodiments of the combustion power plant according to the invention ( 1 ) and the method for operating the combustion power plant according to the invention ( 1 ) can be combined with each other and with each other, as long as this is not explicitly excluded or impossible for physical and / or technical reasons.
  • LIST OF REFERENCE NUMBERS
  • 1
     Combustion power plant
    10
     incinerator
    11
     fuel
    12
     flue gas
    13
     Combustion air from exhaust air of the hot air turbine unit
    14
     fresh combustion air
    101
     firebox
    102
     second train
    103
     third train
    104
     Flugascheaustrag
    105
     Flue gas outlet to a forge
    121
     Flue gas cleaning
    20
     Heat exchanger
    21
     first end of the heat exchanger
    22
     second end of the heat exchanger
    201-203
     first to third heat exchanger
    30
     Hot air turbine unit
    31
     compressor
    32
     expansion turbine
    33
     generator
    34
     working fluid
    35
     fresh gas
    36
     exhaust
    37
     engine
    321-323
     first to third expansion turbine
    331-333
     first to third generator
    341-343
     first to third partial working fluid
    351-353
     control valve
    40
     recuperator
    50
     protection evaporator
    60
     Superheater packages
    70
     Economiserpakete

Claims (14)

  1. Combustion power plant ( 1 ) with an incinerator ( 10 ), in which a fuel ( 11 ) with the development of highly corrosive flue gases ( 12 ), a hot air turbine unit ( 30 ), which are mixed with a gaseous working fluid ( 34 ) and one or more heat exchangers ( 20 ), the or for the transmission of thermal energy from the incinerator ( 10 ) on the working fluid ( 34 ), characterized in that - at least one of the heat exchangers ( 20 ) contains at least one ceramic high-temperature heat pipe whose first end ( 21 ) in the incinerator ( 10 ) and its second end ( 22 ) outside the incinerator ( 10 ) and within the flow path of the working fluid ( 34 ) of the hot air turbine unit ( 30 ), and - the combustion plant ( 1 ) has a conduit which is suitable for the exhaust air ( 36 ) of the hot air turbine unit ( 30 ) directly to the incinerator ( 10 ) as combustion air ( 13 ).
  2. Combustion power plant according to claim 1, characterized in that the at least one heat exchanger ( 20 ) in the firebox ( 101 ) or in the second or third train ( 102 . 103 ) of the incinerator ( 10 ) is installed.
  3. Combustion power plant according to claim 1, characterized in that the at least one ceramic high-temperature heat pipe is a heat pipe with or without capillary structure and vertically or obliquely from above into the incinerator ( 10 ) protrudes.
  4. Combustion power plant according to claim 1, characterized in that the at least one ceramic high-temperature heat pipe is a heat pipe with capillary structure and horizontally or obliquely from the side into the combustion chamber ( 101 ) protrudes.
  5. Combustion power plant according to claim 1, characterized in that at least one of the heat exchangers ( 20 ) contains a plurality of ceramic high-temperature heat pipes, which have a distance from each other, the sufficient air flow through the heat exchanger ( 20 ) in the incinerator ( 10 ) guaranteed even with adhering particles.
  6. Combustion power plant according to claim 1, characterized in that - the combustion power plant ( 1 ) several heat exchangers ( 201 - 203 ), which is used to transfer thermal energy from the incinerator ( 10 ) on the working fluid ( 34 ), - the hot air turbine unit ( 30 ) at least one turbine ( 32 ), and - all heat exchangers ( 20 ) successively in the flow path of the working fluid ( 34 ) are arranged, wherein a heat exchanger ( 203 ) at one of the firebox ( 101 ) further away from the flue gas path ( 121 ) is incorporated in the flow path of the working fluid ( 34 ) further away from the at least one turbine ( 32 ) is arranged as a heat exchanger ( 201 ), which is closer to the firebox ( 101 ) arranged point of the flue gas path ( 121 ) is installed.
  7. Combustion power plant according to claim 1, characterized in that - the combustion power plant ( 1 ) several heat exchangers ( 201 - 203 )) for the transmission of thermal energy from the incinerator ( 10 ) on the working fluid ( 34 ), - the hot air turbine unit ( 30 ) several turbines ( 321 - 323 ), wherein the working fluid ( 34 ) on the several turbines ( 321 - 323 ) and each turbine ( 321 - 323 ) a partial working fluid ( 341 - 343 ), and - any specific heat exchanger ( 201 . 203 ) only in the flow path of the partial working fluid ( 341 - 343 ) of a specific turbine ( 321 - 323 ) is arranged.
  8. Combustion power plant according to claim 1, characterized in that the hot air turbine unit ( 30 ) contains a gas turbine with or without a combustion chamber or an exhaust gas turbocharger with an expansion turbine.
  9. Combustion power plant according to claim 1, characterized in that the combustion power plant ( 1 ) is a waste incineration plant or a biomass incineration plant or a substitute fuel incineration plant.
  10. Method for operating a combustion power plant ( 1 ) with an incinerator ( 10 ), a hot air turbine unit ( 30 ), which are mixed with a gaseous working fluid ( 34 ) and one or more heat exchangers ( 20 ), in which a fuel ( 11 ) with the development of highly corrosive flue gases ( 12 ) burned and the thermal energy from the incinerator ( 10 ) by means of or the heat exchanger ( 20 ) on the working fluid ( 34 ), characterized in that - as at least one of the heat exchangers ( 20 ) at least one high-temperature ceramic heat pipe is used, wherein a first end ( 21 ) of the ceramic high-temperature heat pipe in the incinerator ( 10 ) and a second end ( 22 ) of the ceramic high-temperature heat pipe outside the incinerator ( 10 ) and wherein the working fluid ( 34 ) of the hot air turbine unit ( 30 ) the second end ( 22 ) flows through, and - the exhaust air ( 36 ) of the hot air turbine unit ( 30 ) directly to the incinerator ( 10 ) as combustion air ( 13 ) is supplied.
  11. Method according to claim 10, characterized in that - the incinerator ( 10 ) first without the at least one heat exchanger ( 20 ) is operated in a trial operation, - during the trial operation in the furnace ( 101 ) and in the trains ( 102 . 103 ) of the incinerator ( 10 ) the mechanical stresses and the present atmosphere caused by the flue gas flow are examined with regard to their temperature and their corrosive, abrasive and oxidizing or reducing action, - the installation position, the type, the material and the dimensions of the ceramic high-temperature heat pipe based on the results of the investigation are selected and - the selected ceramic high-temperature heat pipe is installed.
  12. A method according to claim 11, characterized in that - at least one heat exchanger ( 20 ) is realized by a plurality of ceramic high-temperature heat pipes and - the distance between the individual high-temperature ceramic heat pipes to each other within the heat exchanger containing a plurality of ceramic high-temperature heat pipes ( 20 ) is selected based on the obtained examination results.
  13. A method according to claim 10, characterized in that - the thermal energy from the incinerator ( 10 ) on the working fluid ( 34 ) of the hot air turbine unit ( 30 ) by means of several heat exchangers ( 201 - 203 ), - the working fluid ( 34 ) in the hot air turbine unit ( 30 ) at least one turbine ( 32 ), and - the working fluid has several or all heat exchangers ( 201 - 203 ) flows around one after the other, whereby it is separated from a heat exchanger ( 203 ) at one of the firebox ( 101 ) further away from the flue gas path ( 121 ) is installed, each closer to Firebox ( 101 ) in the flue gas path ( 121 ) built-in heat exchanger ( 202 ) flows.
  14. A method according to claim 10, characterized in that - the thermal energy from the incinerator ( 10 ) on the working fluid ( 34 ) of the hot air turbine unit ( 30 ) by means of several heat exchangers ( 201 - 203 ), - the working fluid ( 34 ) in the hot air turbine unit ( 30 ) several turbines ( 321 - 323 ), the working fluid ( 34 ) on the several turbines ( 321 - 323 ) and each turbine ( 321 - 323 ) a partial working fluid ( 341 - 343 ), and - the partial working fluid ( 341 - 343 ) of a specific turbine ( 321 - 323 ) a specific heat exchanger ( 201 - 203 ) flows through.
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Publication number Priority date Publication date Assignee Title
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US4479355A (en) * 1983-02-25 1984-10-30 Exxon Research & Engineering Co. Power plant integrating coal-fired steam boiler with air turbine
EP0571233B1 (en) * 1992-05-22 1997-09-03 Foster Wheeler Energy Corporation Staged furnaces for firing coal pyrolysis gas and char
US8205456B1 (en) * 2006-01-21 2012-06-26 Florida Turbine Technologies, Inc. Dual heat exchanger power cycle
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