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 and a system for increasing the temperature of a vaporous working medium with an evaporator and a compressor connected to the evaporator.
• Heat pumps are known from the prior art which transform the energy potential of the working medium predominantly through evaporation and condensation.
• compressors are usually used which work with an operating medium which acts as a lubricant in the compressor.
• the problem here is that the lubricant must not dissolve in the working fluid, since otherwise reliable lubrication of the compressor cannot be guaranteed, which can lead to destruction of the compressor.
• the equipment must not be detached or emulsified from the equipment.
• the choice of working fluid is limited to working fluids with low boiling temperatures, which have a sufficiently high vapor pressure in the working area to be driven out of the compressor completely.
• the work equipment is therefore limited to substances such as the well-known halogenated hydrocarbons (CFC refrigerants) or short-chain hydrocarbons (KW), which naturally have a low molar heat of vaporization.
• CFC refrigerants halogenated hydrocarbons
• KW short-chain hydrocarbons
• the working medium must be compressed to a high pressure in order to reach a sufficient temperature, which means that the efficiency and thus the performance figure achieved are reduced due to the compression work to be used.
• the so-called absorption heat pumps use the solubility of one component of the working fluid in an adsorbent or absorbent, from which the adsorbed or absorbed component must then be expelled or separated again.
• a high vapor pressure shift can be overcome and a high heat loss at a low temperature level is often unavoidable, so that the effectiveness factors, efficiencies or performance figures achieved, are rather small compared to mechanical heat pumps.
• the invention has for its object to provide a method and a system for increasing the temperature of a vaporous working medium, which avoid the disadvantages mentioned, in particular has an improved efficiency.
• a method with the features of claim 1 is proposed. Preferred further developments are set out in the dependent claims.
• the temperature of the working medium is increased by mechanical compression and, on the other hand, the temperature of the working medium is additionally increased in the compressor by heat exchange with an operating medium that is in direct contact with the working medium, and / or on the other hand additionally by means of an operating medium, which acts as an absorbent, is increased, the absorbent absorbing a first component of the working medium, which is formed by a mixture, in and / or after the compressor, heat being transferred to the remaining, vaporous second component.
• the efficiency, especially for heat pumps, can be significantly improved by the method according to the invention.
• the compressor is preferably designed as a liquid-superimposed compressor.
• this can be a liquid ring pump or a liquid-superimposed screw compressor. It is particularly advantageous that these liquid-superimposed compressors can be operated with high-boiling equipment. Since the operating medium in the liquid-superimposed compressors does not perform a lubricating function but a pure sealing function, practically any working medium down to water can be used in the process according to the invention, which have high molar heat of evaporation, have large temperature jumps in the low pressure range and allow high operating temperatures of the compressor.
• the liquid ring pump can advantageously transfer a large part of the work output as heat to the working medium, which can heat up above the saturation temperature, as a result of which the Efficiency of the process can be increased significantly. Furthermore, the liquid ring pump ensures that the working medium does not accumulate in the compressor to such an extent that the pumping speed may be reduced.
• performance figures can be achieved which are more than twice as large as in conventional mechanical heat pumps, and even with working materials which have a molar enthalpy of vaporization of over 80 kJ / mol, also more than three times the value of conventional heat pumps.
• Another advantage of the procedural separation of compression and heating in the liquid ring pump according to the invention lies in the possibility of being able to realize temperatures of the working medium after the temperature has risen above 180 ° C.
• Operating materials such as high-boiling silicone oils or diester oils or plasticizers such as dioctyl phthalate with viscosities of up to 50 centistokes (cts) are particularly cheap.
• the boiling point of the operating fluid is advantageously higher than the temperature of the working fluid after the temperature increase.
• the liquid-superimposed compressor can have ring gassing, which prevents over-compression.
• a mixture of alcohols for example, can be used as the working medium, in which the evaporation temperature can be approximately 20 ° C. and the condensation temperature 80 ° C.
• An A3 solvent as a working medium is also conceivable, in which the evaporation temperature can be approximately 90 ° C and the condensation temperature 180 ° C.
• a major advantage of this invention is that higher temperature levels can be achieved with the work equipment than was previously possible with CFC work equipment, for example.
• One possible area of application is, for example, wastewater technology, in which the wastewater generated has to be cooled before being discharged.
• the heating of process baths from waste water or rinsing baths in the electroplating area can be given here.
• the working medium can be a one-component solvent, for example water or a higher-boiling solvent, such as the A3 solvent.
• a separation arrangement is preferably connected downstream of the compressor.
• a liquid-superimposed compressor there is the possibility that small amounts of the operating medium of the compressor can accumulate in the vaporous working medium.
• the separation arrangement ensures that these parts are collected and fed back to the compressor.
• an aerosol separator can be connected downstream of the separation arrangement, which can collect the smallest particles (droplets) of the operating medium from the vaporous working medium, which are also conveyed to the compressor.
• any oil that accumulates can be conveyed back into the compressor.
• a separator is expediently connected to the separating arrangement and / or the aerosol separator, the condensate of the working fluid being fed to the evaporator.
• the working medium condenses in the condenser under an increased pressure which was generated by the compressor, and the working medium can give off heat at a high temperature level.
• the condensate is preferably returned to the evaporator via an expansion valve.
• the increase in temperature of the vaporous working medium can, according to the invention, in addition to the mechanical compression, also be achieved by absorbing a component of the working medium, which in this case is formed from a mixture of at least two components, in an absorption medium, the heat of absorption being released being vaporized remaining second component is transferred.
• the absorption systems used for this purpose can, in addition to the usual scrubber systems, such as venturi scrubbers, also be compressor systems, some of which have a sufficient amount of operating fluid, such as the liquid ring pumps already mentioned and explained in their mode of operation.
• a particularly favorable embodiment of the invention provides for the use of azeotropic mixtures as the working medium, the operating medium of the compressor acting as an absorption medium for a component of the working medium.
• the mixture shows an azeotropic behavior. If a component is extracted during the passage of the vaporous working medium during compression, the heat released during its phase transition is transferred to the still vaporous component, which causes an additional temperature increase in the working medium.
• the mixture is an azeotrope with a boiling point at a certain 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 steam mixture, the corresponding heat is transferred to the second component remaining in vapor form. The condensation heat can thus be withdrawn at an elevated temperature level.
• the working medium for example an azeotropic mixture of water with perchlorethylene or silicones
• 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 compressor.
• One of the main advantages here is that the compressed work equipment through the separation (absorption) of the the first of the second component additionally heats up due to the heat of absorption released.
• 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; of course, the invention can 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 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 also be a protic solvent.
• the absorbent is a reversible immobilizable solvent, which is the first component of the working medium in the non-immobilized physical state.
• the reversible solvent in the boiling working medium can advantageously change through physico-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 absorption agent works for the work equipment.
• the vaporous working medium thus already contains the absorption medium (in the non-immobilized state) before compression.
• the reversibly immobilized solvent is in a vaporous state and goes through physical-chemical changes - such as pH shift, change in Molenbraches and the temperature in its volatility and or in its vapor pressure - in the liquid state (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 pyridines, for example, can be used as pH-dependent, reversibly immobilizable solvents.
• An electrochemical change can advantageously be achieved by the above-mentioned electrolysis of one of the components or of an added electrolyte.
• the reversibly immobilizable solvent In the uncharged or non-dissociated state, the reversibly immobilizable solvent will behave azeotropically as a solvent mixture with the second component and evaporate according to the set pressure-temperature level.
• the reversibly immobilizable solvent in the ionized or dissociated form is used as the washing liquid, it can be taken up in any quantity and returned to the evaporator in order to be deionized or undissociated in the evaporation.
• temperatures of certain mixtures can be adapted to the requirements, for example by extracting waste heat from a relaxation process by volumetrically conveying the gas according to the heat output, without having to generate excess pressure on the evaporator side. Mixing occurs during compression, which facilitates ionization. The residual gas emitted by the pump can then be additionally raised to the desired condensation temperature by compression.
• the component deposited on the heat exchanger of the consumer is fed to the evaporator via a return line with a pump such as that.
• the process can be operated either as a closed or open heat pump system.
• a closed heat pump is a system with a separate evaporator and condenser. Heat is fed into the evaporator and, after the transformation in the condenser, is transferred to a downstream heat consumer by heat exchange.
• An open heat pump system is in the present invention if the condenser is integrated into the evaporator itself, so that the heat transformed to a higher temperature level feeds the heat released during the condensation directly back into the evaporator. This means that the heat transformed to the higher temperature level of the condenser can be used again directly for the evaporation of working fluid.
• heating systems with appropriate controls are advantageous. This applies in particular to open heat pump systems.
• liquid working fluid is injected into the compressor system when starting up.
• the steam formed condenses inside the evaporator and transfers the heat of condensation to the liquid working fluid and is gradually brought to a boil, so that the heat required to start up the system is obtained solely from the work of the compressor.
• the absorption of the first component can already take place, for example, in the compressor. Furthermore, it is of course possible for a separating arrangement to be connected downstream of the compressor.
• the ionization of the reversibly immobilizable solvent by electrolysis or by adding electrolytes, whereby the solvent in its immobilized form is created as an absorbent from the working fluid.
• 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 receives (absorbs) the first component, the absorption energy released being transferred to the vaporous remaining second component.
• the absorbent can then be fed back into the evaporator, where it is converted into a nonionic state, for example by deionization, and evaporated again with the condensed phase of the remaining second component as an azeotropic mixture.
• the absorption agent can be injected into the compressor.
• the compressor which in this embodiment can be designed, for example, as a Roots blower or as a liquid jet pump, "is designed with injection openings through which the absorption medium is introduced into the compressor.
• the object of the invention is also achieved by a system for increasing the temperature of a vaporous working fluid with the features of claim 20. Preferred further developments are set out in the dependent claims.
• the invention relates to a system which is an evaporator in which a working medium, which is formed by a mixture, is evaporable, a compressor which causes a temperature increase of the working medium by mechanical compression, an operating medium which is in the compressor with the Working medium can be brought into contact directly, whereby an additional temperature increase can be brought about by means of heat transfer, and has a condenser in which the temperature-increased (and pressure-increased) working medium is condensable.
• a separation arrangement and / or an aerosol separator is preferably connected to the compressor, as a result of which the operating medium is guided back into the compressor.
• Figure 1 is a heat pump with a liquid superimposed compressor
• Figure 2 shows a heat pump in which the working fluid is heated by absorption.
• FIG. 1 shows a system in which a working fluid evaporates in an evaporator 1.
• the working fluid is compressed in a liquid ring pump 2, whereby the temperature of the working fluid is raised by this mechanical compression process.
• the liquid ring pump 2 is operated with an operating medium which is in direct contact with the working medium, the operating medium having a higher boiling point than the working medium.
• the operating fluid can be a high-boiling silicone oil. It is particularly advantageous that the temperature of the working medium, for example low- or high-boiling solvents, additionally increases in the present system due to the heat exchange with the operating medium, which in the case of a silicone oil can reach an operating temperature of over 200 ° C.
• condenser 5 heat is given off to a further fluid due to the condensation, which serves, for example, as the flow of a downstream heating system or heat consumer.
• the condenser 5 is also connected to the evaporator 1 via a pressure compensation line 8.
• the operating medium which may accumulate in the evaporator 1 and which, despite the separating arrangement 3 and the aerosol separator 4, reaches the evaporator 1 via a valve 7 is led back into the compressor 2.
• this system can also be operated with an azeotropic mixture.
• FIG. 2 shows a further alternative of the system according to the invention with an evaporator 9, in which a working fluid evaporates.
• the evaporator 9 is fed thermal energy of an upstream process via a heat exchanger.
• the gas or salt formed saturating in the solution and being required as a vaporous working medium to the compressor 10.
• the working fluid is an azeotropic mixture with a first and a second component.
• the working medium is a solvent mixture, the first component of the solvent mixture being reversibly immobilizable. This component is contained in the non-immobilized form in vapor form in the working fluid.
• this system is operated with a working medium which has only two components, the first component being the immobilized form at the same time as the absorption medium.
• the compressor 10 which is designed as a Roots blower, is designed with injection openings, so that the absorbent is introduced into the vaporous working medium in liquid, reversibly immobilized form during operation of the system.
• part of the first component is absorbed by the absorption agent during the expansion process within the Roots compressor 10.
• a further absorption of the compressed working medium takes place in the downstream separating arrangement 11, which is designed as a separator.
• the tennis arrangement 11, which in a further embodiment can also be designed as a scrubber, has an electrolysis device 13 which maintains the deposition of the vapor of the reversibly immobilizable first component in the absorption medium.
• the working medium is an azeotropically evaporating mixture in which, depending on the type, 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 remaining, relaxed working medium thus heats up in addition to the mechanical compression process, so that the working medium remaining in vapor form can transfer a larger amount of heat in a downstream heat exchanger 12, which significantly improves the efficiency of the system.
• the separating device 11 also has a liquid separator which separates the remaining vapor of the working fluid from the liquid absorbed component. The liquid second component is fed back to the compressor 10. The second component condensed in the heat exchanger 12 is expanded via a valve 14 and conveyed back into the evaporator 9. LIST OF REFERENCE NUMBERS

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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)
• Engine Equipment That Uses Special Cycles (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)

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• 2004
  • 2004-12-22 EP EP04816348A patent/EP1702140B1/fr active Active
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