EP2368080A2

EP2368080A2 - Method and apparatus for evaporating and liquefying a medium

Info

Publication number: EP2368080A2
Application number: EP09775631A
Authority: EP
Inventors: Otto Preglau
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-09-22
Filing date: 2009-09-10
Publication date: 2011-09-28
Also published as: AT507617A1; WO2010031095A2; WO2010031095A3

Abstract

During the continuous evaporation and liquefaction of a medium, such as ammonia, with the objective of using ambient heat for heating purposes, the medium is conducted in a circuit between a liquefier (5), an evaporator (2) and a heat exchanger (20) using a fan (1). In the evaporator (2), the medium is evaporated into an atmosphere of an inert gas and the mixture of the evaporated medium and inert gas is heated in the heat exchanger (20) in that it absorbs heat from the surroundings. In the liquefier (5), inert gas is separated from the medium/inert gas mixture such that the partial pressure of the medium rises and liquefies the same. Liquefied medium is returned to the evaporator (2) from the liquefier via a pump (13) while exchanging heat with the inflowing cold mixture, and inert gas is returned via a separate line (10). From the liquefier (5), heat is dissipated from the steam chamber (4) of the liquefier (5) via a heat exchanger (21) and used for heating purposes.

Description

Method and device for vaporizing and liquefying a medium

The invention relates to a method and a device for vaporizing and liquefying a medium with the aim of heat, namely to win condensation heat during liquefaction. In particular, the medium continuously evaporated and liquefied according to the invention is a refrigerant, e.g. Ammonia, as it is also used in heat pumps.

In heat pumps known today, the refrigerant (eg ammonia, NH ₃ ) should evaporate at the lowest possible temperatures and thus absorb heat energy from the environment in order to release condensation heat again at the highest possible temperature.

When operating heat pumps should the environment (air, water and the like.) With little energy consumption constantly removed heat at a low level, converted into service heat and fed to a low-temperature heating.

The increase in temperature occurring in heat pumps is achieved today mainly by means of compressors, refrigerant and expansion valve in a closed circuit. The drive of the compressor is comparatively labor intensive and consumes significant amounts of energy, e.g. Electricity.

In contrast to compression heat pumps (these work with mechanically driven compressors), absorption heat pumps operate by supplying heat energy, and in this process too the expansion and cooling of the medium takes place via a throttle valve.

The invention has for its object to provide a method for vaporizing and liquefying a medium available, is obtained in the heat of condensation and in which for the execution of the method or the operation of the device less energy than previously required in the operation of heat pumps.

This object is achieved according to the invention with a method which has the features of the independent method claim.

As far as the device according to the invention is concerned, this method is solved with the independent claim directed to the device.

Advantageous refinements of the method and the device according to the invention are the subject of the dependent subclaims. In contrast to the known heat pumps, the lowering of the pressure is not achieved by a throttle valve, but by applying a neutral gas in the inventive method.

According to the law of Dalton, the total pressure of a gas mixture changes as the sum of the partial pressures of the individual gases of which the mixture consists. Therefore, the pressure of the mixture is determined from the partial pressure of the medium (e.g., ammonia) and the partial pressure of the inert gas (e.g., hydrogen or nitrogen) when carrying out the method of the present invention.

The liquefied medium, for example ammonia, evaporates in the process according to the invention into an inert gas, which may be hydrogen or nitrogen. In this way, a gaseous mixture of medium and inert gas, e.g. from ammonia, hydrogen or nitrogen, wherein the required heat of vaporization by means of a heat exchanger of the environment (air or water or the like.) Is removed.

The resulting in the evaporation of the liquid medium in the inert gas mixture is separated again in the process according to the invention. The separation of the mixture, consisting of vaporized medium and inert gas, can be carried out in various ways.

One possibility is to separate the mixture by the action of an electric field on the mixture. The separation of the gas mixture can be carried out, for example, by loading charged molecules of the medium, e.g. charged ammonia molecules are deflected in the electric field.

Alternatively, it is possible to separate the component of the mixture to be separated off, in particular the inert gas, from the mixture by temporary chemical bonding. This is particularly advantageous when using hydrogen as an inert gas, when the inert gas (hydrogen) is separated by formation of metal hydrides.

Since distraction of uncharged ammonia molecules in an inhomogeneous electric field by dipole effect is practically ineffective, in one embodiment of the method according to the invention ammonia molecules are electrically charged by applying a corona discharge. Such charged ammonia molecules can be effectively separated from the mixture in the electric field.

In practice, electrode arrangements with separate charging and deposition zones have proven to be particularly advantageous because they operate very effectively. For example, after the molecules of the medium have been electronically charged by corona charging processes, the mixture of inert gas (hydrogen or nitrogen) and medium (ammonia) is bubbled through a (narrow) gap between electrodes. The charged molecules of the medium (ammonia molecules) are deflected in the direction of the working electrode, so that the mixture is separated. It is advantageous to provide separation tongues in the flow path, which guide the separate gases into separate flow paths.

When hydrogen is used as the inert gas in the process of the present invention, the separation of the mixture of inert gas and medium may be carried out by forming metal hydrides in an adiabatic pressure difference method at a pressure of several hundreds of Torr. In this adiabatic pressure swing process, (practically) no heat exchange will take place, so that all the work done on the system will be completely transformed into the internal energy. In the case of the adiabatic pressure swing process carried out in one embodiment of the invention for separating the inert gas / medium mixture, it is provided that the absorption and desorption of hydrogen are allowed to proceed simultaneously with the aid of a single absorber column. The amount of heat released during absorption is stored in ballast material stretched hydride pellets and consumed again.

The envisaged in the process according to the invention separating the mixture with the formation of metal hydrides can be carried out by itself or in addition to the separation with electrodes.

Since charged molecules of the medium (ammonia molecules) are deflected in a static electric field toward the working electrode in the corona charging process, in one embodiment of the invention, in the said method, the rate of passage of hydrogen through the metal hydride block for increasing the pressure difference to accelerate without the use of a compressor.

The charged molecules of the medium (ammonia molecules) are drawn in an embodiment of the invention in the condenser in the region of the working electrode. The metal hydride block is only lapped by the hydrogen as the second electrical pole, so that on this side the total pressure prevailing in the condenser, but only the partial pressure of the hydrogen on the opposite side in the evaporator comes into effect.

In the method according to the invention is advantageous that sufficient for the required circulation of the gas blower (compressors are not necessary), so that the energy required for the separation of the mixture in the inventive method in Unlike compressors in compression refrigerators is very small. Thus, the economy in the invention of recovering condensation heat compared to known heat pumps or cold steam engines can be considerably increased.

In one embodiment, the sequence of the method according to the invention can be described as follows:

I. A medium (refrigerant, eg NH ₃ ) is periodically evaporated and liquefied again.

2. The medium is circulated by a fan.

3. The medium vaporizes in an evaporator in an inert gas atmosphere (eg H ₂ or N ₂ ), whereby its partial pressure drops, so it expands.

4. The mixture of vaporized medium and inert gas is passed through a heat exchanger where it absorbs ambient heat.

5. Then, the mixture flows through another heat exchanger in which it is heated by flowing out of the condenser (hot) inert gas.

6. Via a line, the mixture is driven by a fan into a vapor space of the condenser.

7. In the vapor space of the condenser, the mixture is (largely) separated.

8. In the condenser, the mixture enriched with medium (eg ammonia, NH ₃ ) condenses, because the dew point is undercut. Liquid medium collects at the bottom of the condenser.

9. Condensation heat - produced because the medium (ammonia) enriched mixture condenses - is removed from the condenser's vapor space via a heat exchanger and is e.g. fed to a low temperature heating.

10. Liquefied medium is pumped through the heat exchanger (to cool it by the cold, gaseous mixture flowing into the condenser) and a

Line again transported to the evaporator.

II. Inert gas separated in the condenser flows via the heat exchanger into the first evaporator. It is advantageous in the inventive method: since in all parts of the plant, even in the heat exchangers, only a predetermined operating pressure, depending on the prevailing temperature, is required, enough to circulate the gases (medium and inert gas) blower and for liquefied medium, a circulation pump.

In the method according to the invention or the device provided for carrying out the method, (inert) inert gas (nitrogen or hydrogen) is blown into the evaporator and the liquid medium is injected, which evaporates via troughs flowing down into the inert gas atmosphere. In this case, ambient heat is supplied to the mixture via the wall of the evaporator.

After the evaporator, a heat exchanger is provided, in which the mixture formed in the evaporator (at ambient temperature) is heated by receiving heat from the environment (air and / or water).

The heating of the mixture in the heat exchanger is not detrimental because simply the temperature level in the condenser condensation is higher.

When carrying out the method according to the invention, the dew point of the medium in the condenser is below, because the condenser (continuously), a gaseous mixture of medium and inert gas is fed, but the inert gas and separated from the

Condenser is withdrawn again. Thus, the partial pressure of the medium increases until

Dew point or up to the saturation curve (depending on the temperature) and the medium condenses with release of heat (condensation heat). The heat thus released is discharged via a heat exchanger from the condenser.

The inert gas, whether hydrogen or nitrogen, is heated by the heat of condensation emitted by the refrigerant, but since the pressure difference process is performed adiabatically (ie without heat exchange with the environment), the entry of hydrogen into the metal releases heat to form metal hydride , which, however, is consumed again when hydrogen is discharged.

Further details and features of the method and the device according to the invention will become apparent from the following description with reference to the schematic drawings.

It shows:

Fig. 1 shows schematically a first embodiment and Fig. 2 shows a second embodiment of a system according to the invention. The plant shown in Fig. 1 has as essential parts of a boiler plant as a condenser 5, a heat exchanger 6, an evaporator 2, a heat exchanger 20 and a fan 1. In addition to the lower part 11 of the condenser 5, where there is liquid medium, a pump 13 is connected, the liquefied medium via a line 14 to the evaporator 2 leads. The evaporator 2 is connected to the heat exchanger 20 so that vaporized medium (mixed with inert gas) absorbs heat in the heat exchanger 20 and is conducted via a line 3 via the fan 1 into the vapor space 4 of the condenser 5. In the condenser 5, electrodes 7 and 8 are provided, wherein between the electrodes 7 and 8, a separation tongue 9 is provided. In addition, in the vapor space 4 of the condenser 5, a heat exchanger 21 is provided, which is supplied via lines 12 and a pump 22, a heat transfer medium or dissipated.

Between the electrodes 7 and 8, the separation tongue 9 is mounted so that separated inert gas is supplied via a line 10 to the heat exchanger 6 after it flows via the line 10 to the evaporator 2.

The fan 1 provides the necessary gas circulation and conveys the warmed up to circulation temperature of medium and inert gas (eg ammonia vapor hydrogen gas mixture) from the heat exchanger 20 via line 3 into the vapor space 4 of the condenser 5. Previously, the mixture of inert gas and Medium (ammonia) in the heat exchanger 6 to the operating temperature prevailing in the condenser 5, heated.

In the vapor space 4 of the condenser 5, the molecules of the medium (ammonia molecules) are electrically charged before entry between the electrodes 7, 8 by means of corona charging and the gas mixture passed between the oppositely charged electrodes 7 and 8. In contrast to the inert hydrogen molecules, the charged molecules of the medium are deflected in the direction of the working electrode 7 and the gases thus separated are separated from one another by the at least one separating tongue 9.

Hot inert gas (hydrogen) now flows via the line 10 through the heat exchanger 6 is cooled and takes in the evaporator 2 with further cooling gaseous medium (ammonia gas), wherein the mixture formed (ammonia gas-hydrogen gas mixture) in the heat exchanger 20 is reheated to ambient temperature.

The medium containing e.g. Ammonia, enriched part of the mixture condenses in the

Steam room 4 by falling below the dew point, gives off condensation heat and accumulates in the liquid medium (ammonia) at the bottom 11 of the condenser 5. The heat of condensation is using the heat exchanger 21 from the condenser. 5 removed, so that the condensate on the bottom 11 can not heat up.

The costs incurred in the Verfiüssiger 5 Kondensationswärmemenge (dissipated by the heat exchanger 21) and the required heat of evaporation in the evaporator 2 balance approximately.

Purified inert gas (hydrogen) is blown from the vapor space 4 of the condenser 5 via the line 10 into the evaporator 2. Condensed medium is also conducted by means of the liquid pump 13 via the line 14 into the evaporator 2. Both media are cooled in the heat exchanger 6 against the cold medium-inert gas mixture (ammonia vapor-hydrogen mixture) in countercurrent, before finally in the evaporator 2 liquid medium (ammonia) expands into the inert gas and evaporated under (extreme) cooling.

In the variant of the method according to the invention and the device according to the invention shown in Fig. 2, the separation of medium (ammonia) from the inert gas (hydrogen) takes place in the liquefier by means of a metal hydride block 15. It is provided that as metal e.g. Palladium is provided. Palladium can absorb 600 to 3000 times its volume of gaseous hydrogen, with hydrogen starting to dissolve again at relatively low temperatures (40 to 50 ° C) and very low pressure from the metal lattice of the palladium.

The amount of heat released during absorption is stored in ballast material stretched hydride pellets and consumed again.

The separation of the medium (NH ₃ ) is possible, with finely divided palladium (palladium sponge) is particularly suitable, which is 600 times as SoI can accommodate 3000 times the volume of gaseous hydrogen in its metal grid and the hydrogen at relatively low temperatures (40 ° C - 50 ° C) and very low pressure in turn begins to loosen from the metal lattice of the paladium.

Since water, such as ammonia, is a dipole, water can also be used as the working medium in the process according to the invention, in which case the operating temperature can be just below the "critical point" of the water. As with ammonia, the charging zone consists of a series of sputtering wire-plate electrode pairs that charge the water vapor molecules flowing through a correspondingly applied voltage in the kVolt range and the current in the μA range. It is an inhomogeneous field.

The deposition zone consists of a group of homogenous fields, which with a very high Voltage and an extremely low amperage and be produced with plate pair electrode arrangements.

The electrical power required to deflect is thus small and is in the one-watt range.

The method for evaporating and liquefying a medium (in the example ammonia) described with reference to FIGS. 1 and 2 can be described by way of example as follows:

The medium is circulated by the blower 1. The medium evaporates in the evaporator 2 in an inert gas atmosphere (e.g., hydrogen or nitrogen), whereby the partial pressure of the medium decreases, thus expanding.

The mixture of vaporized medium and inert gas is passed through a heat exchanger 20, where it receives ambient heat.

The mixture of medium and inert gas flows through a further heat exchanger 6, in which it is heated by flowing out of the condenser 5, hot inert gas.

From the further heat exchanger 6, the mixture of inert gas and medium, driven by the blower 1, enters a vapor space 4 of the liquefier 5.

In the vapor space 4 of the condenser 5, the mixture is largely separated, to which ionized ammonia molecules in an electric field (electrodes 7 and 8) are deflected and optionally additionally or exclusively inert gas is chemically bonded or absorbed, for example under Metallhydridbildung when the inert gas is hydrogen.

In the condenser 5 condenses the medium (ammonia) from the mixture because the dew point is exceeded, especially since the partial pressure of the medium increases because inert gas is separated, with liquid refrigerant accumulates at the bottom 11 of the condenser 5.

Resulting condensation heat is removed from the vapor space 4 of the condenser 5 via a heat exchanger 21 and can be supplied to a heater.

From the condenser 5 liquefied medium via a pump 13 via the

Passed heat exchanger 6. In the heat exchanger 6, it is cooled by the cold, gaseous mixture flowing to the condenser 5. The thus obtained heated, liquefied medium is passed via the line 14 to the evaporator 2, where it is in the Inert gas, which is supplied to the evaporator 2 via the line 10, evaporated into it.

In summary, an embodiment of the invention can be described as follows:

In the continuous evaporation and liquefaction of a medium, such as ammonia, with the aim of using ambient heat for heating, the medium is circulated by means of a blower 1 between a condenser 5 and an evaporator 2, and a heat exchanger 20. In the evaporator 2, the medium is evaporated into an atmosphere of an inert gas, and the mixture of vaporized medium and inert gas is heated in the heat exchanger 20 by absorbing heat from the environment. In the condenser 5, inert gas is separated from the mixture of medium and inert gas, so that the partial pressure of the medium rises and liquefies it. Liquefied medium is supplied from the condenser via a pump 13 under heat exchange with inflowing cold mixture back to the evaporator 2, as well as a separate line 10 inert gas. From the condenser 5, heat is removed from the steam space 4 of the condenser 5 via a heat exchanger 21 and used for heating.

Claims

Claims:

1. A process for vaporizing and liquefying a medium, characterized by the following process steps:

the medium is circulated in a closed circuit by means of a blower,

liquefied medium is evaporated in the presence of an inert gas,

The mixture of inert gas and vaporized medium thus formed is in a

Heat exchanger supplied ambient heat,

the mixture of medium and inert gas is separated in a condenser,

By separating inert gas, the medium liquefies by falling below the

Dew point of the medium,

liquefied medium is returned to the evaporator as well as inert gas separated in the condenser,

condensation heat is removed from the condenser.

2. The method according to claim 1, characterized in that is used as a medium ammonia or water.

3. The method according to claim 1 or 2, characterized in that nitrogen and / or hydrogen is used as the inert gas.

4. The method according to any one of claims 1 to 3, characterized in that from the vapor space (4) of the condenser (5) by means of a heat exchanger (12)

Heat is dissipated.

5. The method according to any one of claims 1 to 4, characterized in that in the condenser (5) electrically charged molecules of the medium are separated by an electric field of non-charged inert gas molecules.

6. The method according to any one of claims 1 to 5, characterized in that from the mixture of medium and inert gas inert gas, if it is hydrogen, is separated by Metallhydridbildung.

7. The method according to any one of claims 1 to 6, characterized in that withdrawn from the liquefier liquefied medium as well as withdrawn from the condenser inert gas is passed in a heat exchanger in countercurrent to the supplied mixture of inert gas and medium.

8. The method according to any one of claims 1 to 7, characterized in that the evaporation of the refrigerant is carried out in an inert gas atmosphere in an evaporator, wherein the thus formed mixture of inert gas and medium in a heat exchanger (2) ambient heat is supplied.

9. The method according to claim 8, characterized in that in the evaporator liquid medium is injected from above and injected from below inert gas.

10. The method according to claim 8 or 9, characterized in that in the evaporator liquid medium is passed through cups or trays.

11. A device for carrying out the method according to one of claims 1 to 10, characterized by a condenser (5), a line (14) from the condenser (5) to the evaporator (2), a the evaporator (2) downstream heat exchanger (20). a conduit (3) via which the heat exchanger (20) is connected to the gas space (4) of the condenser (5), a fan (1) in the conduit (3), and a heat exchanger (21) in the vapor space ( 4) of the condenser (5).

12. The device according to claim 11, characterized in that in the vapor space (4) of the condenser (5) comprises means (7, 8, 9, 15) for separating the mixture

Medium and inert gas is provided.

13. The apparatus according to claim 12, characterized in that the means for separating two oppositely electrically charged electrodes (7, 8), which is preceded by a corona discharge station.

14. The apparatus according to claim 13, characterized in that between the electrodes (7, 8) a separating tongue (9) is provided.

15. Device according to one of claims 11 to 14, characterized in that a heat exchanger (6) is provided, through which the line (3) for a mixture of inert gas and vaporized medium on the one hand, and the line (10) for supplying inert gas the condenser (5) to the evaporator (2) is guided as well as the line (14) for liquid medium, and that the line (14) for liquefied medium in front of the heat exchanger (6) is associated with a liquid pump (13).