EP1714009A1

EP1714009A1 - Method and installation for converting thermal energy from fluids into mechanical energy

Info

Publication number: EP1714009A1
Application number: EP05716660A
Authority: EP
Inventors: Erwin Oser; Michael Rannow
Original assignee: Oser Erwin
Current assignee: Ecoenergy Patent GmbH
Priority date: 2004-02-12
Filing date: 2005-02-10
Publication date: 2006-10-25
Also published as: US7845173B2; DE102004006837A1; WO2005078243A1; US20090205337A1

Abstract

The invention relates to a method and an installation for converting thermal energy, which is contained in fluids as perceptible or latent heat, into mechanical energy. According to said method, a working medium is evaporated in an evaporator by means of the thermal energy, the latter if required being converted to a higher temperature using one or more heat pumps that are connected one behind the other. The working medium is then expanded in an expansion device and the thermal energy is at least partially converted into mechanical energy. The invention is characterised in that the expansion takes place in a low-pressure expansion device (8) and the energy that is contained in the expanded vaporous working medium can be returned to the evaporation unit of the evaporator (7), which can be used to evaporate additional working medium.

Description

METHOD AND SYSTEM FOR CONVERTING HEATING ENERGY FROM FLUIDS INTO MECHANICAL ENERGY

The invention relates to a method for converting thermal energy, which is contained in fluids, for example, as tangible or latent heat, into mechanical energy, in which a working fluid is evaporated in an evaporator, which is expanded in a relaxation device, thermal energy at least partially into mechanical energy is converted. Furthermore, the invention relates to a system for converting thermal energy from fluids into mechanical energy. . A large number of devices and methods for obtaining mechanical energy are known from the prior art. For example, thermal power plants are known in which a working medium, for example water vapor, isobarically heated to the boiling point in a boiler, evaporated and then 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 a feed water pump and fed back into the boiler. One of the disadvantages of these devices is that in these expansion processes using steam in turbines, high temperatures for pressures of over 15 bar to 200 bar have to be generated in order to achieve economic efficiency levels, since the pressure ratio in expansion is the essential influencing variable in turbines ,

A further feature of the known relaxation processes for converting thermal energy into mechanical energy is that the condensation waste heat which arises during the condensation of the working medium, due to the process itself, disadvantageously arises as heat loss for the relaxation process, as a result of which the degree of whirling is negatively influenced.

The invention has for its object to provide a method and an apparatus for converting thermal energy into mechanical energy, which avoid the disadvantages mentioned, and an improved efficiency, especially at temperature and pressure levels which, for example, approximately correspond to the natural environmental conditions , exhibit.

To achieve this object, a method with the features of claim 1 is proposed. Preferred further developments are set out in the dependent claims. According to the invention there is provided a method for converting thermal energy from a fluid into mechanical energy by expanding a vaporous working medium in a expansion device connected to an evaporator, in which thermal energy evaporates a working medium by heat exchange in an evaporator and / or thermal energy by means of at least one or more successively connected heat pumps are transformed to a higher temperature level in order to evaporate the working fluid in the evaporator by heat exchange, the vaporous working fluid being a vaporous mixture formed from at least two components and being expanded in a low-pressure expansion device, the pressure being released during the expansion Energy of the working fluid is partially converted into mechanical energy, and at least one second vaporous component experiences a temperature increase after the low-pressure expansion energy and at least one first component of the working fluid is withdrawn, so that the energy contained in the relaxed, vaporous, temperature-raised second component / s of the working fluid can be returned to the evaporator and can be used to vaporize additional working fluid.

Thermal energy, which vaporizes a working fluid through heat exchange in an evaporator, can be made available, for example, by at least one energy source / s which has a good efficiency. An energy source / s with high efficiency can, for example, be selected from the group comprising heat pumps / fuel cells / n and / or solar system / s.

Solar systems in the sense of the invention can also include solar collectors.

At least part of the energy required, preferably all of the energy required to raise the temperature of the second component / s after the low-pressure relaxation can be obtained through the energy released during absorption and / or adsorption.

The terms absorption _"nd" absorbed "in the sense of this invention have the meaning of" absorbed absorption and / or adsorption "or" and / or adsorbed. "

For the purposes of this invention, the term “relaxation” means an increase in volume associated with a reduction in pressure.

According to the invention it can further be provided that with the thermal energy that is present in a fluid in the form of sensible or latent heat of one or more components, if necessary after a transformation to a higher temperature level by means of one or more heat pumps arranged in series in an evaporator is evaporated that the expansion takes place in a low-pressure expansion device and the energy contained in the expanded vaporous working medium can be returned to the evaporator, which energy can be used to evaporate 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 expansion device by means of an absorbent, heat being transferred to the second component remaining in vapor form.

The intermediate heat pump process for transforming the temperature level of the work medium to be relaxed can be implemented with different embodiments of heat pumps, as described below. In addition, depending on the size of the desired temperature increase, it can be provided that the energy transformation for the temperature increase is also carried out with several heat pump processes connected in series.

An essential feature of the method according to the invention is the expansion of the working medium in a low-pressure expansion device, the energy contained in the expanded vaporous working medium being able to be returned to the evaporator and being used for the evaporation of additional working medium. For this purpose, the working medium to be relaxed is formed by a mixture, and the method preferably has at least a first component of the working medium which is absorbed in and / or after the low-pressure expansion device by means of an absorbent and / or is adsorbed by means of an adsorbent, thermal energy the remaining vaporous second component / s passes over, which is recyclable.

The working fluid is preferably as an azeotropic mixture or as a _^ mixture having a boiling point lowering, based on the boiling point of the component with the highest boiling point, before, wherein working means are preferably in the form of mixtures having a boiling point lowering of at least, preferably ° C of at least 10 ° C , more preferably at least 15 ° C, even more preferably at least 20 ° C and most preferably at least 25 ° C, based on the boiling point of the component with the highest boiling point.

In an embodiment of the invention, the working medium mixture is an azeotrope with a minimum boiling point for a certain mixing ratio of the components. In the case of azeotropically evaporating mixtures with a boiling point minimum, 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 from the vapor mixture adiabatically beers, 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. In particular, in the case of suitably selected azeotropic mixtures, 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 fed back into the process.

Azeotropic mixtures suitable for use in accordance with the invention can be selected from the group comprising pyridine / water, water / ethanol, water / ethyl acetate, water / dioxane, water / carbon tetrachloride, water benzene, water / toluene, ethanol / ethyl acylate, ethanol / benzene, ethanol / Chloroform, ethanol / carbon tetrachloride, ethyl acetate / carbon tetrachloride, methanol / carbon tetrachloride, methanol / benzene, chloroform / acetone, toluene acetic acid, acetone-carbon disulfide and / or water / silicone.

Suitable azeotropic mixtures which can likewise be used according to the invention can also be multi-component systems, i.e. these azeotropic mixtures comprise at least three components, or at least four components. Basically, all azeotropic mixtures known in the literature, to which reference is made in their entirety in this connection, can be used insofar as they are suitable according to the invention.

It is preferred if the first component to be absorbed is water, for example an alkaline silicate solution can be used as the absorbent.

The use of water is advantageous because the heat of condensation from water, ie from gas to liquid, is particularly high. The thermal energy released in this way can advantageously be used to heat the second component (s). Absorbents and / or adsorbents which can be suitably used according to the invention can be selected from the group comprising zeolites, silicates, inorganic acids, in particular phosphoric acid, halogen acids, sulfuric acid, silicic acid, organic acids, inorganic salts and / or organic salts.

Suitable salts are alkali and / or alkaline earth salts, in particular their halogen salts, such as Li Br, LiCl, MgC] 2 and the like.

In principle, all substances which absorb and / or adsorb a solvent of the working medium are suitable as absorbents and / or adsorbents. However, preference is given to those absorbents and / or adsorbents which release the absorbed and / or adsorbed component of the working fluid with only a small amount of energy.

It can also be advantageous that the absorption agents / adsorbents can be easily separated from the second component (s) of the working medium after taking up a first component (s) of the working medium.

The absorbent / adsorbent for receiving at least a first component (s) of the working fluid can advantageously be chosen such that the overall efficiency of the system according to the invention for converting thermal energy from fluids into mechanical energy at an initial fluid temperature of 25 ° C. is determined over 24 hours inclusive which is preferably still> 40% for separating the first component / s from the absorbent / adsorbent.

The working medium for low-pressure relaxation, for example an azeotropic mixture of water and perchlorethylene, can be, for example, by heat exchange with primary be evaporated from process vapors or heated process liquids and / or heat storage. 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 relaxation device. One of the main advantages here is that the relaxation of the azeotropic mixture can convert thermal energy into mechanical energy and with the help of a generator into electrical energy, and at the same time the relaxed work equipment, which has already done "work" in the relaxation process, through the separation (Absorption) of the first from the second component heats up due to the released heat of absorption, whereby the remaining working medium can be returned after the expansion, for example to give off its heat in a heat exchanger. For example, in one embodiment of the invention it is possible for the remaining Working medium (only second component) is passed into a heat exchanger (evaporator), in which the remaining working medium condenses and, due to the heat of condensation, the liquid working medium evaporates with the first and second components and then back into the En t tensioning device is guided. In this way, according to the invention, the efficiency of the method for converting thermal energy into mechanical energy can be significantly improved.

The working medium for the low-pressure expansion 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. When using an azeotropic mixture Depending on the type, their evaporation temperatures can be reduced so that they are below the evaporation temperatures of the individual components.

In a preferred embodiment, 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.

According to the invention, at least one component of the working medium, preferably the second component, can preferably have a boiling point in the range from 20 ° C. to 250 ° C., preferably from 40 ° C. to 200 ° C., preferably from 60 ° C. to 150 ° C., still preferably from 80 ° C - 120 ° C, and most preferably 90 ° C - 100 ° C.

According to the invention, at least one component of the working medium, preferably the second component, can preferably have a molar heat of vaporization in the range from 5? KJ / mol-15 KJ / mol, preferably from 6 KJ / mol-14 KJ / mol, preferably from 7 KJ / mol. 13 KJ / mol, more preferably from 8 KJ / mol - 12 KJ / mol and most preferably from 9 KJ / mol - 10 KJ / mol.

According to the invention, at least one component of the working medium, preferably the second component, can preferably have a low specific heat capacity [cp] of <1.2 J / g, preferably of 0.4 J / g-1 J / g, preferably of 0.5 J / g - 0.9 J / g, and most preferably from 0.6 J / g - 0.8 J / g.

The working medium is preferably a solvent mixture which has organic and / or inorganic solvent components. Examples of this are mixtures of water and silicones. Silicones and / or derivatives thereof which can preferably be used according to the invention can have a boiling point in the range from 20 ° C. to 250 ° C., preferably from 40 ° C. to 200 ° C., preferably from 60 ° C. to 150 ° C., still preferably from 80 ° C. 120 ° C and most preferably from 90 ° C - 100 ° C.

Silicones and / or derivatives thereof which can preferably be used according to the invention can have a molar heat of vaporization in the range from 5 ?? KJ / mol-15 KJ / mol, preferably from 6 KJ / mol-14 KJ / mol, preferably from 7 KJ / mol-13 KJ / mol , more preferably from 8 KJ / mol - 12 KJ / mol and most preferably from 9 KJ / mol - 10? KJ / mol.

Silicones and / or derivatives thereof which can preferably be used according to the invention can have a low specific heat capacity [cp] of <1.2 J / g, preferably 0.4 J / g-1 J / g, preferably 0.5 J / g-0 , 9 J / g, and most preferably from 0.6 J / g - 0.8 J / g.

The working fluid can have a mixture of water and at least one or more silicones. A mixing ratio of water to silicone / s is preferred from 1: 100 to 1: 2, more preferably from 1:50, even more preferably from 1:25, further preferably from 1:15 and most preferably from 1: 8 to 1: 10th

At least one component can advantageously be a protic solvent.

In an alternative embodiment, the absorbent is a reversible immobilizable solvent, which is the first component of the working medium in the non-immobilized state. The reversible solvent in the boiling working medium can advantageously change due to physico-chemical changes in that it does not immobilize due to ionization or complex formation from the vapor phase State can be changed to the reversibly immobilized state and acts in the non-immobilized form as an absorbent for the work equipment. Thus, the vaporous working medium already contains the absorption medium (in the non-immobilized state) before the expansion. The reversibly immobilized solvent is in a vaporous state and changes to the liquid state due to physical-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 pyridines, 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 expansion device. Furthermore, it is of course possible for an absorption device, for example as a scrubber, to be connected downstream of the low-pressure relaxation device. In one possible embodiment, the reversibly immobilizable solvent can be ionized 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 absorbent. At the same time, the vapors of the working fluid flowing through the absorbent are also ionized, so that the vapor pressure is lowered so that the vapor of the reversible immobilizable component is deposited in the working fluid. The azeotropic working medium is thus passed through the absorbent which absorbs the first component, the released absorption energy being transferred to the vaporous remaining second component. The absorbent can then be fed back into the evaporator where it becomes, for example, by deionization in a non-ionic state and is evaporated again with the condensed phase of the remaining second component as an azeotropic mixture.

In addition to the usual scrubber systems, such as Venturi scrubbers, absorption systems can also include compressors and pumps that have a sufficient amount of operating fluid, such as Roots pumps with injection, screw compressors, liquid ring pumps or liquid jet pumps. By combining the process with a polytropic compression system, temperatures of certain mixtures can be adapted to the requirements.

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.

As a low-pressure expansion device, a device used in the mass of the steam is neither nor the pressure ratio, but only the D ^r uckdifferenz relevant.

In a particularly preferred embodiment, the low-pressure expansion device is designed as a Roots blower - as a Roots blower - or in the form of oval gear pumps. It is advantageous that the roots blower can work as a relaxation device (relaxation motors) with a pressure difference of 500 mbar with full efficiency and can be used in a closed system at pressures of 10 to 0.5 bar. According to the invention, the Roots blower can be equipped with at least one be designed spray opening through which the absorbent 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

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 connected to the generator that can, whereby the mechanical energy can be converted into electrical energy. The use of a Roots color as a low-pressure expansion device opens up the possibility - on the one hand, of supporting the process by injecting absorbent materials, and - especially when using waste heat with a temperature of less than approximately 100 ° C for driving pumps or generators others because of the small pressure and temperature differences to transform the remaining energy in the relaxed vaporous working medium, as described above, back to an elevated temperature level and thus to make it traceable.

According to the invention it can be provided that the roots blower relaxes and does not compress a working medium under pressure.

In a further embodiment of the invention, a separating arrangement can be provided which separates the absorbed first component from the absorbent. The separation arrangement can be designed, for example, as a membrane system which is connected downstream of the absorption device. The desorbed liquid, first component is expediently returned to passed the evaporator by evaporating together with the second liquid component as an azeotropic working medium. The absorbent can, for example, be led to the relaxation device, in which it is injected into the relaxing working fluid. In a further alternative, the absorbent can be returned to the scrubber, in which the first component is absorbed from the working fluid. Oils can be used as absorption medium, from which the first component of the working medium can be completely expelled again, for example by means of a membrane system.

The separation of the first absorbed component in the absorbent can alternatively be carried out by an evaporation process of the absorbed component.

Preferably, 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 and condensed. The heat exchanger is preferably an evaporator, in which the first and second components are evaporated as working medium.

The working medium is preferably an azeotropic mixture of water and silicone. The water is the first, absorbent component and silicone is the second component. The absorbent is expediently a silicate. The absorbent is advantageously an alkaline, molecularly disperse silicate solution, the water absorbed in the alkaline silicate solution being desorbed, for example, by heating.

The object of the invention is also achieved by a system for converting thermal energy into mechanical energy with the features of claim 24. Preferred further developments are set out in the dependent claims. According to the invention, a system for converting thermal energy into mechanical energy is provided, which comprises the following components: a) an evaporator unit in which a working medium which is formed by a mixture can be evaporated, b) a low-pressure expansion device, c) one absorber and / or adsorption device, the expansion device low pressure is integrated in and / or the low-pressure expansion device is connected downstream of, d) a separating device which is designed as a diaphragm system or thermal Austreibersystem _^, in which the absorbed component is separated from the absorbent, and a pump with which the absorption medium is conveyed to the separating device and back to the absorption device, e) at least one energy source which is in contact with the evaporator unit and by means of which heat energy can be generated which is absorbed by a fluid flow in the evaporator in order to reduce the fluid flow to an hour transform higher temperature level.

The energy source / s can be a heat pump / s, a fuel cell and / or solar system / s. The use of at least one heat pump is preferred in view of the advantageous energy balance. Heat pumps can be used advantageously at low ambient temperatures. Solar systems require a sufficiently high level of solar radiation so that the use of heat pumps can often be preferred in colder regions. Fuel cells can also be used due to their high efficiency.

It may be preferable to use fuel cells in combination with solar systems and / or heat pumps. In general, it can be advantageous to use different types of energy sources use to optimize the efficiency of the system according to the invention depending on the ambient conditions.

According to the invention, the invention relates to a system with an evaporator, in which a working medium, which is formed by a mixture, preferably an azeotropic mixture, can be evaporated, with a pressure-reducing device, with an absorption device, which is integrated in the low-pressure device is and / or the low-pressure expansion device is connected downstream, wherein in the absorption device a first component of the working medium can be absorbed by an absorption medium and heat can be transferred to the remaining, vaporous second component, which is recyclable

In the embodiment in which the heat energy of the fluid is first used to evaporate a first working medium, which is then transformed with a heat pump to a higher temperature level in order to evaporate a "second" working medium for low-pressure relaxation, which is then used in a low-pressure process Relaxation device is relaxed, the heat energy is partially converted into mechanical energy, the invention relates to a system that additionally includes one or more heat pumps in different embodiments.

In a first embodiment for such a heat pump it is provided that on the one hand the temperature of the working medium is increased by mechanical compression and on the other hand the temperature of the working medium is additionally in the compressor through a heat exchange with an operating medium that is in direct contact with the working medium, and / or on the other hand, additionally increased by means of an operating medium which acts as an absorption medium, the absorption medium absorbing a first component of the operating medium, which is formed by a mixture, in and / or after the compressor, heat being transferred to the remaining, vaporous second component. The efficiency, in particular for heat pumps, can be significantly improved by the method according to the invention.

On the one hand, the temperature of the working fluid increases due to the compression of the working fluid. On the other hand, there is the possibility of reacting to the temperature increase by exchanging heat with the equipment. Here, the compressor is preferably designed as a liquid-superimposed compressor. For example, 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 up 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 permit high operating temperatures of the compressor.

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 achieve temperatures of the working medium after the temperature has risen by more than 180.degree. 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.

It is also possible that the working fluid of the heat pump is a one-component solvent, for example water or a higher-boiling solvent. A separation arrangement is preferably connected downstream of the compressor. When using 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. In a further embodiment of the invention, 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. In a further embodiment of the invention, any oil that may accumulate can be conveyed back into the compressor.

A condenser is connected downstream of the separating arrangement and / or the aerosol separator, the condensate of the working medium 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 temperature increase of the vaporous working medium can also be realized according to the invention in addition to the mechanical compression also by absorption of 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 released heat of absorption being reduced to the dan second component remaining in the form of an F is transmitted. The absorption systems used for this purpose can be, in addition to the usual scrubber systems, such as, for example, venturi scrubbers, also compressor systems 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 for the heat pump process 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. This means that 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 of the working medium. In one embodiment of the invention, the mixture is an azeotrope with a minimum boiling point at a certain mixing ratio of the components. In the case of azeotropically evaporating mixtures with a boiling point minimum, 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 working medium, for example an azeotropic mixture of water with perc ethylene or silicones, can be evaporated, for example, by heat exchange with the fluid from process vapors or heated process fluids and / or heat storage or any other fluids. The absorption, in which, according to the invention, the heat of absorption obtained 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 working fluid is additionally heated due to the separation (absorption) of the first and second components due to the released heat of absorption. 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. When using an azeotropic mixture, depending on the type, 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. Advantageously, at least one component can also be a protic solvent.

In an alternative embodiment, the absorbent is a reversible immobilizable solvent, which is the first component of the working medium in the non-immobilized 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 absorbent works for the work equipment. Thus, the vaporous working medium already contains the absorbent (in the non-immobilized state) before compression. The reversibly immobilized solvent is in a vaporous state and passes through physical-chemical changes - such as pH shift, change in mole fraction and temperature in its volatility and / or in its vapor pressure - into the liquid state (comparable to steam as a solvent in non-immobilized form and water as a reversibly immobilizable solvent medium). 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 resersible 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. In the uncharged or non-dissociated state, the reversibly immobilizable solvent, as a solvent mixture, will behave azeotropically with the second component and evaporate according to the set pressure-temperature level. However, if the reversibly immobilizable solvent in the ionized or dissociated form is used as the washing liquid, it can be absorbed in a substantial amount and returned to the evaporator in order to be deionized or undissociated again in the evaporation.

In addition to the usual scrubber systems, such as Venturi scrubbers, absorption systems can also include compressors and pumps that have a sufficient amount of operating fluid, such as Roots pumps with injection, screw compressors, liquid ring pumps or liquid jet pumps. By combining the? Process with a polytropic compression system, 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 , The method according to the invention for converting thermal energy from fluids into mechanical energy can be used for very different fluids which either exist as one-component fluids or as fluid mixtures. The fluids can also be either gaseous or in the form of liquids. In the case of gaseous fluids, the presence of condensable components which condense in the evaporation of a "first" working medium by falling below the dew point is particularly advantageous since the heat of condensation released, which is present as latent heat, usually significantly increases the usable energy supply because the latent heat energies in phase transitions, condensable gases are usually significantly higher than the sensible heat energies in permanent gases, the phase transition advantageously still taking place at a constant temperature.

Examples of such fluids can be exhaust air or waste water flows from industrial cooling, heat exchange or relaxation processes.

A particularly preferred embodiment of the invention relates to the conversion of the thermal energy from the atmospheric air with the water vapor dissolved therein as atmospheric moisture.

From an energetic point of view, the atmospheric air with the water vapor dissolved in it represents a large, practically inexhaustible energy reservoir. The decisive factor here is that, taking current meteorological data into account, this energy reservoir, which is formed by the sensible heat of the air and the latent heat of the water vapor, is everywhere the world, that is, regardless of location. This energy reservoir is constantly replenished by the sun's rays. Ultimately, the conversion of the thermal energy contained in moist air into mechanical energy is an indirect use of thermal energy from solar radiation. The decisive advantage of air with the water vapor dissolved in it as an energy store for solar radiation lies in its fluid character, so that it can be conducted in large volume flows through heat exchange devices due to natural or generated flow, so that the amount of thermal energy that can be used by the device is temporal and can be spatially decoupled from the limited radiation power of the sun. This means that this inexhaustible energy reservoir, which is available at all locations worldwide, can be used technically at any time and regardless of location.

With reference to the above statements, a particularly preferred embodiment of the method according to the invention provides for the thermal energy from moist ambient air to be taken up in an evaporator for the evaporation of a suitable working medium and, if necessary, for a transformation to a higher temperature level depending on the real environmental conditions in terms of temperature and humidity to relax the steam with one or more heat pumps via a low-pressure expansion device according to the above statements, the thermal energy being partly converted into mechanical energy and the energy still contained in the relaxed working medium being recyclable. On the one hand, the gaseous components are cooled, and on the other hand, depending on the temperature levels of the heat exchange processes, the air humidity contained is largely condensed, the high heat of condensation of the water being obtained for the process.

With sufficiently high ambient temperatures and atmospheric humidity and the use of azeotropic mixtures with sufficiently low boiling points as working medium, the conversion can advantageously also be carried out without the interposition of a heat pump. The average working figure of the system according to the invention for converting thermal energy from fluids into mechanical energy at an initial fluid temperature of 25 ° C. over a period of 24 hours is 2.5 to 12. The average working digit can be 3 to 10 or 4 to 8 for systems according to the invention. The average working digit for systems according to the invention is preferably 5 to 6.

Working figures above 4 can be achieved, for example, by using absorption heat pumps and / or heat pumps with liquid-superimposed compressor systems, as described, for example, in PCT / EP2004 / 053651, to which reference is made in full here.

The overall efficiency of the system according to the invention for converting thermal energy from fluids into mechanical energy at an initial fluid temperature of 25 ° C. determined over 24 hours is preferably> 40%, preferably> 50% and particularly preferably> 60% *

For example, 15% to 40%, preferably 20% to 35% and preferably 25% to 30%, of the energy released can be used for the conversion into mechanical energy by relaxing the working medium on the low-pressure expansion device.

When generating energy from the air, systems according to the invention can handle air quantities from 1.6 m ³ h to 160,000 m? h Withdraw energy. Of course, much larger amounts of air can be extracted from energy. Dimensioning in the range from 160 n ^ h to 1,600 ιr? / H has proven to be economical for a household.

From air volumes of 16 n ^ h to 160,000 mP / h at 25 ° C, 0.1 kW to 1000 KW of electricity can be generated, for example, with systems according to the invention. With systems according to the invention, for example, 1 KW of electricity can be generated from air quantities of 160 r / h at 25 ° C and 10 KW of electricity can be generated from air quantities of 1600 mP h at 25 ° C.

The systems according to the invention can of course extract energy from all types of gases and / or liquids, provided that these do not damage the system. Gases for energy generation can be used, for example, from a temperature of at least 15 ° C up to 250 ° C or even up to 350 ° C or even higher. Gases with low temperatures are usually obtained as process gases. Temperatures of 300 ° C or higher occur with equipment such as oils or the like.

According to the invention, however, it is preferred to use the thermal energy of ambient air, which is usually at least 15 ° C. to 50 ° C., preferably 20 ° C. to 40 ° C. and preferably 25 ° C. to 35 ° C.

In the systems according to the invention, it can be advantageous if the temperature T1 of the working medium upstream of the low-pressure relaxation device is higher than the temperature T2 of the working medium downstream of the low-pressure relaxation device and upstream of the absorption device. On the other hand, the temperature T3 of the working medium in the evaporator unit is higher than the temperature T2 of the working medium after the low-pressure expansion device and before the absorption device.

The temperature of the working medium in the evaporator can be 10 ° C to 250 ° C, preferably 20 ° C to 200 ° C, preferably 30 ° C to 150 ° C, more preferably 40 ° C to 130 ° C and particularly preferably 50 ° C to 100 ° C. Most preferably, the temperature of the working medium in the evaporator is above the boiling point. The pressure of the working medium upstream of the low-pressure expansion device can be in the range from 0.3 bar to 15 bar. Higher pressures are possible, but such systems require more material, so that the working fluid in the supply line from the evaporator to the low-pressure expansion device is preferably in the range from 1 bar to 10 bar, more preferably in the range from 1.5 bar to 8 bar, more preferably in the range from 2 bar to 6 bar and more preferably in the range from 3 bar to 4 bar.

The pressure difference ΔP of the working medium in front of the low-pressure expansion device and immediately after the relaxation of the working medium but in front of the absorption device should be ΔP 0.1 bar to 5 bar, preferably ΔP 0.5 bar to 3 bar and preferably ΔP 0.75 bar to Make 1 bar.

Further advantages, features and details of the invention result from the following description, in which an embodiment of the invention is described in detail with reference to FIG. 1. The features mentioned in the claims and the description can be essential to the invention individually or in any combination. It shows

Figure 1 shows a system for converting thermal energy from humid ambient air into mechanical energy.

This is based on an embodiment with an upstream, mechanically driven heat pump and a low-pressure expansion with an azeotropic mixture as the working medium. A forced air flow in a heat exchanger (2) is cooled with the aid of a fan (1). In order to improve the efficiency of the process, the supply air can be pre-cooled in an air-air heat exchanger (3) by exchanging heat with the cooled air.

The heat exchanger (2) serves as an evaporator unit of a heat pump, which forms the compressor (4), the heat exchange unit (5), which acts as a condenser of the heat pump, and the expansion valve (6) as further functional modules.

With the heat pump, the energy obtained in the evaporator (2) from the condensation of the air humidity, in addition to the cooling of the air, is transformed to a higher temperature level and in the heat exchange unit (5) releases the heat at this high temperature level by condensation. The energy released is used to vaporize an azeotropic mixture that is used as a working medium in an energetic cir- cular process. The vapor produced in the evaporator unit (7) from the azeotropic mixture is expanded via a low-pressure expansion device (8), a mechanical force occurring on the shaft, which is converted into electricity with the aid of the generator (9).

The relaxed vapor is separated in a downstream scrubber (10) in which the absorbent injected into the scrubber (10) at the top absorbs one of the components. The heat of absorption released in this process is transferred to the other component remaining in vapor form, as a result of which the residual vapor is heated to a temperature level above the boiling point of the azeotropic mixture. The residual vapor releases its heat of condensation in the heat exchanger unit (13), which is integrated in the evaporator unit (7). The component liquefied in (13) is returned to the storage tank by means of the pump (14). rather transported for the azeotropic mixture, and is available here again for mixing with the other component.

The component absorbed in the scrubber is fed with the aid of the pump (11) to a membrane filter (12) in which this component is separated again from the absorption liquid. The pressure generated by the pump (11) is sufficient to return the absorbent to the scrubber on the one hand and to feed the second component of the evaporator unit (7) on the other. The two components in the storage space of the evaporator unit are mixed together again.

Two energy components therefore contribute to the production of the motive steam from the azeotropic mixture: On the one hand, the energy obtained with the heat pump (2, 4, 6, 5) from the cooled air and the condensed air humidity and transformed to the high temperature level of the evaporation, and on the other hand the energy energetic cycle after the relaxation, absorption energy returned from the motive steam separation of the vapor generated from an azeotropic mixture. According to the invention, this return of the energy ensures the good efficiency of the extraction of air from air.

In a favorable embodiment, a motor can also be used to drive the compressor (4) of the heat pump, which is operated either with diesel or natural gas or also with biogenic fuels, such as, for example, biogas, rapeseed oil or bio-diesel. In this variant, an additional energy component for the evaporator unit (7) can be obtained from the engine waste heat or the exhaust gas heat of the engine (16). With such an arrangement, on the one hand, the efficiency of the overall process is further improved, and on the other hand, this arrangement is intended to simplify “starting up the system”. Reference numerals list

1 fan

2 heat exchangers, evaporators 1

3 air-air heat exchangers (pre-cooler)

4 compressors

5 heat exchange unit

6 expansion valve

7 evaporator unit, evaporator 2

8 expansion device, Roots blower

9 generator

10 washers, absorption device

11 pump

12 separator, membrane filter

13 • <• Heat exchanger unit

14 pump

15 engine / CHP

16 supply line

Claims

Patent claims

1. A method for converting thermal energy from a fluid into mechanical energy by expanding a vaporous working medium in a expansion device connected to an evaporator (7), characterized in that thermal energy evaporates a working medium by heat exchange in an evaporator (7) and / or that thermal energy is transformed to a higher temperature level by means of at least one or more heat pumps connected in series in order to evaporate the working medium in the evaporator (7) by heat exchange, the vaporous working medium being a vaporous mixture formed from at least two components and in a low-pressure expansion Device (8) is expanded, the energy of the working medium released during the expansion being partially converted into mechanical energy, and at least one second vaporous component experiencing a temperature increase after the low-pressure expansion and energy is withdrawn from at least a first component of the working medium, so that the energy contained in the relaxed, vaporous, temperature-raised second component / s of the working medium can be returned to the evaporator and can be used to evaporate additional working medium.

2. The method according to claim 1, characterized in that at least a part of the energy required, preferably the total energy required to raise the temperature of the second component / s after the low-pressure relaxation, by the energy released during absorption and / or adsorption is recoverable.

3. The method according to claim 1 or 2, characterized in that the working medium is formed by a mixture and a first component is absorbed in and / or after the low-pressure expansion device by means of an absorbent, wherein heat is transferred to the remaining vaporous second component, the is traceable.

4. The method according to any one of the preceding claims, characterized in that the mixture forms an azeotrope with a minimum boiling point at a certain mixing ratio of the components.

5. The method according to any one of the preceding claims, characterized in that the working medium is present as an azeotropic mixture or as a mixture with a lowering of the boiling point, based on the boiling point of the component with the highest boiling point, whereby working means in the form of mixtures are preferred which have a lowering of the boiling point at least 5 ° C, preferably at least 10 ° C, more preferably at least 15 ° C, even more preferably at least 20 ° C and most preferably at least 25 ° C.

6. The method according to any one of the preceding claims, characterized in that the absorption of the first component / s is controlled so that the vaporous second component / s is heated to a temperature above the boiling point of the mixture, and the second component / n in a heat exchanger is condensed, whereby the evaporation of the working fluid takes place.

7. The method according to any one of the preceding claims, characterized in that the working medium is a solvent mixture with low molar enthalpy of vaporization, which has organic and / or inorganic solvent components, wherein one of the components can be a protic solvent.

8. The method according to any one of the preceding claims, characterized in that the absorbent is a reversibly immobilizable solvent which is the first component of the working medium in the non-immobilized state of aggregation.

9. The method according to any one of the preceding claims, characterized in that the working fluid is a mixture of water and silicone.

10. The method according to any one of the preceding claims, characterized in that the absorbent is a silicate solution.

11. The method according to any one of the preceding claims, characterized in that the low-pressure expansion device is a Roots blower.

12. The method according to claim 11, characterized in that the roots blower is filled with at least one injection opening through which an absorbent or a protic solvent can be brought into the roots blower.

13. The method according to any one of the preceding claims, characterized in that the low-pressure relaxation device is followed by an absorption device in which the first component / s of the working fluid is absorbed, the absorption device preferably being designed as a washer.

14. The method according to any one of the preceding claims, characterized in that a separation arrangement separates the absorbed first component / s from the absorbent.

15. The method according to claim 14, characterized in that the separation arrangement is designed as a membrane system.

16. The method according to claim 14, characterized in that the separating arrangement is designed as an expulsion unit in which the absorbed first component is desorbed by heating.

17. The method according to any one of the preceding claims, characterized in that the absorbent is conveyed with a pump into the separation device and then back to the washer.

18. The method according to claim 1, characterized in that the heat pump is driven by a mechanical evaporator or a liquid-superimposed compressor system.

19. The method according to claim 18, characterized in that the heat pump is designed as an absorption heat pump with an azeotropic mixture, in which the temperature increase takes place by absorption of a component and transfer of the absorption energy to the vapor component remaining.

20. The method according to claim 1, characterized in that the fluid is a single or multi-component gas or a single or multi-component liquid.

21. The method according to claim 20, characterized in that the fluid is a gas or liquid flow from industrial cooling, heat exchange, conversion or relaxation processes.

22. Verfahreij, according to claim 1 and 20, characterized in that the Huid is atmospheric ambient air with the water vapor dissolved therein as atmospheric moisture.

23. The method according to any one of the claims, characterized in that the thermal energy is composed of sensible and / or latent heat of individual or several components.

24. Plant for converting thermal energy into mechanical energy, characterized in that it comprises the following components: a) an evaporator unit (7) in which a working medium which is formed by a mixture can be evaporated, b) a low-pressure expansion device ( 8th), c) an absorption device (10) and / or adsorption device (10) which is integrated in the low-pressure relaxation device (8) and / or the low-pressure relaxation device (8) is connected downstream, d) a separating device (12), which acts as a membrane system or thermal expulsion system in which the absorbed component is separated from the absorbent, and a pump with which the absorbent is conveyed to the separating device (12) and back to the absorbing device (10), e) at least one energy source which is connected to the evaporator unit (7 ) is in contact, by means of which heat energy can be generated, which is absorbed by a fluid stream in the evaporator (1) in order to transform the fluid stream to a higher temperature level.

25. Plant according to claim 24, characterized in that the energy source / s a heat pump, a combustion «. is fabric and or solar system

26. Plant according to claim 24 or 25, characterized in that the low-pressure expansion device is a Roots blower.

27. Plant according to claim 24 to 26, characterized in that a separation arrangement separates the absorbed first component from the absorbent.

28. Plant according to one of the preceding claims, characterized in that the low-pressure expansion device is connected to a generator (9) which converts mechanical energy into electrical energy.

29. Plant according to claim 24 to 28, which can be operated according to one of the methods mentioned.

30. The method according to any one of claims 1 to 23, wherein the method has an additional process step in which the condensate water occurring when using heat pump / s is processed in an additional process step to process water and / or water with drinking water quality.