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
  • F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
  • F01K25/06—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using mixtures of different fluids
  • F01K25/065—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using mixtures of different fluids with an absorption fluid remaining at least partly in the liquid state, e.g. water for ammonia
• • 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
  • F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
  • F01K25/06—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using mixtures of different fluids

Definitions

• the invention relates to a method for converting thermal energy, which arises in a refrigerator from the condensation of a refrigerant, into mechanical energy, in which a working medium is evaporated in an evaporator by the thermal energy, which is relaxed in a relaxation device and at least partially the thermal energy is converted into mechanical energy. Furthermore, the invention relates to a plant for converting thermal energy into mechanical energy.
• thermal power plants are known in which a working fluid is isobarically heated to the boiling point at a high pressure in a boiler, evaporated and then still overheated in a superheater. The steam is then adiabatically expanded in a turbine, performing work, and liquefied in a condenser, giving off heat. The liquid is brought to a pressure by the feed water pump and fed back into the boiler.
• One of the disadvantages of these devices is that high pressure of over 15 bar to 200 bar must be generated in the expansion processes in turbines, since in turbines the pressure ratio of the expansion achieved is decisive for the efficiency achieved.
• the invention has for its object to provide a method and a system for converting thermal energy into mechanical energy, which avoid the disadvantages mentioned, in particular have an improved efficiency.
• the expansion takes place in a low-pressure expansion device and the energy contained in the expanded vaporous working medium can be fed back into the evaporator and can be used for the evaporation of additional working medium.
• the method preferably has a first component of the working medium, which is formed by a mixture, is absorbed in and / or after the low-pressure relaxation device by means of an absorption medium, heat being present the remaining vaporous second component passes over, which is recyclable.
• the mixture is an azeotrope with a minimum boiling point at a specific mixing ratio of the components.
• the evaporation temperatures can be reduced, depending on the type, so that they are below the condensation temperatures of the individual components. If the first component is absorbed adiabatically from the vapor mixture, the corresponding heat is transferred to the second component remaining in vapor form. The heat of condensation can thus be withdrawn at an elevated temperature level.
• the second vaporous component can be condensed in the evaporator of the working medium itself, giving off the heat of condensation, so that the corresponding proportion of the thermal energy can be returned to the process.
• the first component to be absorbed is water, an alkaline silicate solution, for example, can be used as the absorbent.
• the working fluid for example an azeotropic mixture of water and perchlorethylene
• the absorption in which, according to the invention, the heat of absorption is transferred to the second component remaining in vapor form, as a result of which this component heats up to a temperature level above the boiling point of the azeotropic mixture, can take place in and / or after the expansion device.
• One of the main advantages here is that mechanical energy can be "gained” by relaxing the azeotropic mixture and, at the same time, the relaxed working medium, which has already done “work” in the relaxation process, by separating (absorbing) the first from the second component heated due to the released heat of absorption.
• the remaining working fluid can be returned after the expansion, for example to give off its heat in a heat exchanger.
• the remaining work equipment only second component
• a heat exchanger evaporator
• the remaining working fluid condenses and, due to the heat of condensation, the liquid working fluid evaporates with the first and second components and is then fed back into the expansion device.
• the efficiency of the method for converting thermal energy into mechanical energy can be significantly improved.
• the working medium is preferably formed by an azeotropic mixture with a boiling point minimum or an almost azeotropic mixture.
• the invention is described below with an azeotropic mixture; the invention can of course also be applied to almost azeotropic mixtures or to non-azeotropic mixtures. High efficiencies can be achieved particularly with an azeotropic or an almost azeotropic mixture.
• the evaporation temperatures can be lowered so that they are below the evaporation temperatures of the individual components.
• the working medium has a low volume-specific or low molar enthalpy of vaporization. This ensures that a large amount of motive steam is generated with a predetermined amount of thermal energy.
• the working medium is preferably a solvent mixture which has organic and / or inorganic solvent components. Examples of this are mixtures of water and selected silicones. At least one component can advantageously be a protic solvent.
• the absorbent is a reversible immobilizable solvent, which is the first in the non-immobilized physical state Component of the work equipment.
• the reversible solvent in the boiling working medium can advantageously change through physical-chemical changes in such a way that it can be changed from the non-immobilized state to the reversibly immobilized state by ionization or complex formation from the vapor phase and in the non-immobilized form as an absorbent works for the work equipment.
• the vaporous working medium already contains the absorption medium (in the non-immobilized state) before the relaxation.
• the reversibly immobilized solvent is in a vaporous aggregate state and changes to the liquid state due to physico-chemical changes - such as pH shift, change in mole fraction and temperature in its volatility and / or vapor pressure (comparable to steam as a solvent in non-immobilized form and water as a reversibly immobilizable solvent).
• the advantage here is that the working fluid consists of two components, with one component simultaneously acting as an absorbent for the other component in the reversibly immobilized state.
• Cyclic nitrogen compounds such as P ridine, for example, can be used as pH-dependent, reversibly immobilizable solvents.
• the absorption of the first component can already take place, for example, in the low-pressure relaxation device.
• an absorption device for example as a scrubber
• the ionization of the reversibly immobilizable solvent can be carried out in the absorption device by electrolysis or by adding electrolytes, as a result of which the immobilized solvent forms from the working medium as an absorption medium.
• the vapors of the working medium flowing through the absorption medium are also ionized, so that the vapor pressure is reduced so that the steam of the reversible immobilizable component is deposited in the working medium.
• the azeotropic working medium is thus passed through the absorption medium, which is the first component absorbs (absorbed), the released absorption energy being transferred to the vaporous remaining second component.
• the absorbent can then be fed back into the evaporator, where it is converted into a non-ionic state, for example by deionization, and is evaporated again with the condensed phase of the remaining second component as an azeotropic mixture.
• the molar ratio of the working medium is expediently chosen such that the pressure in the expansion decreases more by reducing the number of molecules remaining in the gas phase than the pressure increases by the heating of the remaining gas, so that an otherwise resulting back pressure builds up after the expansion device is avoided.
• the relaxed vaporous working medium is transformed with the aid of a heat pump to a temperature level above the boiling point of the working medium.
• This energy return can be implemented using a one-component working fluid.
• the heat pump is operated with a liquid-superimposed compressor system, for example a liquid ring pump or a screw compressor, and an operating liquid is used to operate the heat pump, the molar enthalpy of vaporization of which is several times, preferably more than four times, particularly preferably more than five times the evaporation enthalpy of the working fluid for the relaxation is.
• an excess of the energy return is achieved over the drive energy of the heat pump.
• a device can be used as the low-pressure expansion device in which neither the mass of the steam nor the pressure ratio, but only the pressure difference is relevant.
• the low-pressure expansion device is designed as a Roots blower - as a Roots blower - or in the form of oval gear pumps System can be used at pressures from 10 to 0.5 bar.
• the Roots blower can be designed with at least one injection opening through which the absorption agent and / or a protic solvent can be introduced into the Roots blower. Pressure-controlled injection is advantageously carried out to prevent liquid damage.
• Another advantage is that in the relaxation devices mentioned, only the pressure difference and not the mass or the relaxation ratio is decisive for the efficiency. With already small pressure differences of less than two bar, full efficiency can be achieved.
• the Roots blower expediently has a gas-tight seal between the scoop space and the gear space, in a further embodiment the Roots blower comprising multi-bladed rotors.
• the Roots blower also has a shaft that can be connected to the generator, whereby the mechanical energy can be converted into electrical energy.
• the use of a Roots blower as a low-pressure expansion device opens up the possibility, on the one hand, of supporting the process by injecting absorption agents, and, in particular when using waste heat with a temperature of less than approximately 100 ° C. for driving pumps or generators others due to the small pressure and temperature differences to raise the condensation energy of the working fluid, for example with a heat pump, to an elevated temperature level again.
• a separating arrangement can be provided which separates the absorbed first component from the absorbent.
• the separating arrangement can, for example, be designed as a membrane system which is connected downstream of the absorption device.
• the desorbed liquid, first component is expediently fed back into the evaporator, in which it evaporates together with the second liquid component as an azeotropic working medium.
• the absorbent can, for example, be guided to the relaxation device, in which it is injected into the relaxing working fluid.
• the absorbent can be returned to a scrubber, in which the absorbent of the first component takes place from the working fluid. Oils from which the first component of the working fluid can be completely expelled, for example by a membrane system, can be used as the absorbent.
• the separation of the first absorbed component in the absorption medium can alternatively be carried out by an evaporation process of the absorbed component.
• the second component remaining after the absorption device, which according to the invention has absorbed heat due to the absorption of the first component despite relaxation is passed into a heat exchanger in the evaporator, in which the second component condenses.
• the condensate is pumped back into the evaporator.
• the first and second components are preferably evaporated as working medium in the evaporator. Liquids can be used as absorption media, from which the first component of the working fluid can be completely expelled again, for example by the membrane system or evaporation.
• the working medium is preferably an azeotropic mixture of water and silicone.
• the water is the first component to be absorbed and silicone is the second component.
• the absorption agent is expediently a silicate. It is advantageous the absorbent is an alkaline molecularly disperse silicate solution, the water absorbed in the alkaline silicate solution being desorbed, for example by heating.
• the thermal desorption is advantageously implemented in an expulsion unit separate from the evaporator.
• the invention relates to a system with an evaporator, in which a working medium, which is formed by a mixture, preferably an azeotropic mixture, is evaporable, with a low-pressure expansion device, with an absorption device, which is in the low-pressure expansion device is integrated and / or the low-pressure relaxation device is connected downstream, with a refrigeration machine which is connected to the evaporator, wherein means for heat recovery are provided, with which a first component of the working medium can be absorbed by an absorption medium and heat energy to the absorption device remaining, vaporous second component is transferable, which is recyclable to the evaporator.
• the heat energy (waste heat) generated in the refrigeration machine during the condensation of the refrigerant in the condenser or in the condenser is used for the evaporation process in the evaporator, in which the working fluid is evaporated and passed into the expansion device.
• the thermal energy is converted into mechanical energy in the relaxation device.
• the relaxation device can be connected to a generator, for example, so that the mechanical energy is converted into electrical energy. If the working medium is formed as an azeotropic or an almost azeotropic mixture, the system according to the invention is distinguished by a particularly good efficiency.
• a large amount of mechanical energy is generated, in particular through the use of a Roots blower, which preferably follows the conversion into electrical energy for the partial coverage of the drive energy in the chiller process can be returned.
• the remaining, second component contains a sufficiently large amount of thermal energy that can be used for the evaporation process of the liquid working fluid.
• Figure 1 shows a system for converting thermal energy from a condenser of a refrigerator 8 into mechanical energy.
• the system comprises a refrigeration machine 8 with a compressor 12.
• the compressor 12 which can be designed, for example, as a piston or turbo compressor, draws in a vaporous refrigerant from an evaporator 13 and compresses the steam to a specific pressure.
• the compressed steam is then condensed in the heat exchanger 15, which is connected to an evaporator 6 for a liquid working fluid, which is carried out in a further separate process.
• the heat of condensation is used for the evaporation process of the working fluid.
• the condensed, liquefied refrigerant is expanded in the throttle valve 14 and then returns to the evaporator 13, where heat is added to it.
• the working fluid which in the present embodiment is an azeotropic mixture with a first and a second component, is evaporated by the thermal energy of the refrigerating machine 8 and expanded in the downstream low-pressure expansion device 2, mechanical energy being “obtained”.
• Relaxation device 2 which in the following embodiments as Roots blower 2 is connected to a generator 1 and drives it, so that mechanical energy is converted into electrical energy.
• This electrical energy can, for example, be used proportionally for the operation of the compressor 12 of the refrigeration machine 8.
• an absorption device 3 Downstream of the relaxation is an absorption device 3, shown in FIG. 1 as a scrubber 3, in which the vaporous working medium is washed with an absorption medium.
• the first component is absorbed by the absorption medium.
• the working medium is an azeotropically evaporating mixture in which, depending on the composition, the evaporation temperatures can be lowered so that they are below the condensation temperatures of the individual components. If the first component is absorbed adiabatically from the vaporous working medium, the heat corresponding to the decrease in entropy is transferred to the remaining second component.
• the vaporized, relaxed working medium heats up despite the relaxation, so that a certain part of the heat of the remaining working medium can be returned to the evaporator 6 (heat return), which significantly improves the efficiency of the system.
• the vaporous second component is fed back into a heat exchanger 7 in the evaporator 6, where it evaporates further liquid working fluid by condensation.
• the condensate is then pumped into the evaporation space of the evaporator 6 with the pump 9.
• the absorbed first component is passed together with the absorbent through a pump 10 into a membrane system 5, which separates the first component from the absorbent.
• the first component is then conveyed into the evaporator 6, and the absorption agent returns to the scrubber 3.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
• Applications Or Details Of Rotary Compressors (AREA)
• Sorption Type Refrigeration Machines (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Engine Equipment That Uses Special Cycles (AREA)

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• 2004
  • 2004-12-22 WO PCT/EP2004/053655 patent/WO2005066466A1/fr active Application Filing
  • 2004-12-22 US US10/583,936 patent/US7726128B2/en not_active Expired - Fee Related
  • 2004-12-22 ES ES04816348T patent/ES2293384T3/es active Active
  • 2004-12-22 ES ES04804988.6T patent/ES2624638T3/es active Active
  • 2004-12-22 AT AT04816348T patent/ATE371101T1/de active
  • 2004-12-22 WO PCT/EP2004/053654 patent/WO2005061858A1/fr active IP Right Grant
  • 2004-12-22 WO PCT/EP2004/053651 patent/WO2005061973A1/fr active Application Filing
  • 2004-12-22 WO PCT/EP2004/053649 patent/WO2005066465A1/fr active Application Filing
  • 2004-12-22 DE DE502004004776.9T patent/DE502004004776C5/de active Active
  • 2004-12-22 EP EP04804985A patent/EP1706681A1/fr not_active Withdrawn
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  • 2004-12-22 EP EP04816348A patent/EP1702140B1/fr active Active
  • 2004-12-22 WO PCT/EP2004/053650 patent/WO2005061857A1/fr active Application Filing
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