LOW-TEMPERATURE DISTILLATION PLANT

Abstract

A low-temperature distillation facility for distilling a mixed fluid into a pure fluid. An aggregation device has an inlet connected to the vapour space of a supercooling chamber, wherein captured mixed fluid from an evaporator enters the supercooling chamber. The aggregation device's outlet is connected to the vapour space of a superheating chamber, wherein captured pure fluid from a condenser can be sprayed into the superheating chamber. An energy source cools the temperature in the supercooling chamber and heats the temperature in the superheating chamber. A heat exchanger is arranged between the exits of the supercooling chamber and of the superheating chamber. During the process, vapour flows from the supercooling chamber via the aggregation device to the superheating chamber.

Claims

1. A low-temperature distillation facility (LTD) with one or more stages having different mean temperatures T.sub.i, for distilling a mixed fluid into a pure fluid, wherein each stage comprises: an evaporator with a vapour space and with a warmer Ti+T mixed fluid which can be introduced, a condenser with a vapour space and with a cooler T.sub.iT pure fluid which can be sprayed in, and wherein the vapour spaces of the evaporator and of the condenser are connected to one another into a common vapour space by way of vapour connections, in a manner such that the pressure and the temperature therein can equalise at all times in an unhindered manner, at least one aggregation device which at the entry side is connected to the vapour space of a supercooling chamber, wherein captured mixed fluid from an evaporator, with several evaporators from that of the coolest stage, can be brought into the supercooling chamber, and said aggregation device at the exit side is connected to the vapour space of a superheating chamber, wherein captured pure fluid from a condenser, with several condensers from that of the warmest stage can be sprayed into the superheating chamber, wherein the aggregation device is connected to an energy source for cooling the temperature in the supercooling chamber and for heating the temperature in the superheating chamber, wherein vapour flows from the supercooling chamber to the superheating chamber via the aggregation device during the process, and wherein a heat exchanger is arranged between the exits of the supercooling chamber and of the superheating chamber, for cooling the hot captured pure fluid from the superheating chamber, as the entry into the condenser, with several condensers into that of coolest stage, as well as for heating the cold, captured mixed fluid from the supercooling chamber, as the entry into an evaporator, with several evaporators into that of the warmest stage.

2. An LTD facility according to claim 1, wherein the aggregation device comprises at least one sorption chamber and/or a desorption chamber, with a sorbent, wherein at least temporarily, vapour from the vapour space of the supercooling chamber can be condensed and sorbed in the sorbent, and at least temporarily, whilst inputting energy, pure fluid can be desorbed out of the sorbent into vapour and can be fed to the vapour space of the superheating chamber.

3. An LTD facility according to claim 2, comprising at least one sorption chamber and a desorption chamber, wherein the sorption chamber is connected to the desorption chamber by way of at least one connecting channel, and transport devices are provided to the forward and return transport of the sorbent between the sorption chamber and the desorption chamber.

4. An LTD facility according to claim 3, wherein a sorption process and a desorption process can be carried out in the sorption chamber and the desorption chamber in an alternating manner.

5. An LTD facility according to claim 3, wherein the sorption chamber and the desorption chamber are connected to one another by way of at least two connecting channels which on use are constantly sealingly filled with the trickling-through sorbent, so that a stepless sorption and desorption process can be carried out with the help of the transport devices.

6. An LTD facility according to claim 2, comprising at least one sorption chamber and a desorption chamber, a control device which periodically exchanges the functions of the sorption chamber and desorption chamber, for permitting a stepped sorption and desorption, by way of the control device being able to alternatingly connect the vapour connections to the supercooling chamber or to the superheating chamber, to the respective sorption chamber or desorption chamber, and wherein the energy source is always connected to the respective desorption chamber.

7. An LTD facility according to claim 2, wherein the sorbent is zeolite, silica gel, ammonia or lithium bromide.

8. An LTD facility according to claim 1, wherein the aggregation device comprises a compressor/a vacuum pump or spray nozzle, for producing a vacuum in the supercooling chamber and an overpressure in the superheating chamber, by which means vapour is sucked out of the supercooling chamber and is brought into the superheating chamber, amid the simultaneous cooing of the supercooling chamber and heating of the superheating chamber.

9. An LTD facility according to claim 1, further comprising a suction device for sucking away non-condensable gases at the end of the condensation process in each condenser and in the superheating chamber.

10. An LTD facility according to claim 1, wherein the feed of mixed fluid, a discharge of pure fluid as well as a discharge of brine.

11. An LTD facility according to claim 1, wherein the distillation facility comprises several stages of different mean temperatures T.sub.i, wherein all evaporators respectively all condensers of the different stages are connected in opposite directions into a circuit, by way of conduits.

12. An LTD according to claim 11, wherein the vapour connections of vapour spaces of different stages are connected by conduits to condensers of other stages with lower mean temperatures, for lifting the pressure in the respective conduits.

13. An LTD facility according to claim 11, wherein the heat which is produced in the aggregation device is distributed into several evaporators of different stages.

14. An LTD facility according to claim 11, wherein captured mixed fluid can be brought out of the evaporator of the coolest stage into the supercooling chamber, and the captured pure fluid from the condenser of the warmest stage can be sprayed into the superheating chamber.

15. An LTD facility according to claim 11, wherein the pure fluid from the superheating chamber and cooled in the heat exchanger can be spayed in at the entry into the coolest condenser, and/or the mixed fluid from the supercooling chamber and heated in the heat exchanger can be brought in at the entry into the warmest evaporator

16. An LTD facility according to claim 1, wherein the heat produced in the aggregation device is distributed in part-flows into several evaporators and/or condensers of different stages as well as into the superheating chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention is hereinafter explained in more detail with reference to the drawings. There are shown in:

[0020] FIGS. 1a, b a schematic representation of a low-temperature distillation facility (LTD facility) according to the state of the art: a) in the simplest embodiment; b) multi-staged;

[0021] FIG. 2 a schematic representation of an LTD facility according to the invention, in its simplest form;

[0022] FIGS. 3a-d aggregation devices, designed as a) sorption chamber, operating continuously; b) sorption chamber, operating discontinuously; c) compressor/vacuum pump; d) jet nozzle;

[0023] FIG. 4 a schematic representation of a multi-stage LTD facility according to the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

[0024] FIG. 1a shows a schematic representation of a low-temperature distillation facility (LTD facility) 1 according to the state of the art, in its simplest embodiment with only one stage. It comprises an evaporator 2 with a vapour space 4, into which mixed fluid 5 which is to be distilled can be introduced, so as to evaporate. Non-evaporated mixed fluid 5 is also captured again in the evaporator 2. The LTD facility moreover comprises a condenser 3 with a vapour space 4, into which pure fluid 6 corresponding to the distillate of the mixed fluid 5 can be sprayed, in order to form the smallest of droplets, on which vapour can condense. These droplets are finally captured again in the condenser 3, as a pure fluid 6. The vapour spaces 4 of the evaporator 2 and the condenser 3 in each case are connected to one another into a common vapour space 4 by way of a vapour connection 10, in a manner such that the pressure and the temperature can propagate therein at all times in an unhindered manner. The common vapour space 4 thus connects to the evaporator 2 to the condenser 3.

[0025] In the representation according to FIG. 1, both fluids, 5, 6 are sprayed into the vapour space 4, wherein the mixed fluid 5 at T.sub.i+T is a few degrees warmer than the pure fluid 6 at T.sub.iT. The pressure in the vapour space 4 thereby corresponds to the saturation pressure Pi at the mean temperature T.sub.i of the two fluids 5, 6. Due to the physical conditions in the vapour space 4, the mixed fluid 5 evaporates and propagates to into the condenser region of the vapour space 4. There, the vapour comes into contact with the finely sprayed, cooler droplets of the pure fluid 6, condenses thereon, falls and is finally captured at the base of the condenser 3. The non-evaporated mixed fluid 5 likewise falls and is captured at the base of the evaporator 2. The temperatures of the captured fluids 5, 6 are roughly the same and correspond to the mean temperature T.sub.i of their initial temperatures. Conduits 7 then remove the captured fluid 5, 6, to and from which fluids heat is respectively fed and dissipated by way of an energy source and heat sink respectively, in order to heat the mixed liquid again to T+T and to cool the pure fluid 6 again to TT. The temperature-managed fluids 5, 6 in conduits 7 are then brought again into the evaporator 2 and sprayed into the condenser 3 respectively. Thus two circuits arise, an evaporator circuit and a condenser circuit.

[0026] The process runs in a continuous manner. A supply container 11 with mixed fluid 5 ensures the resupply, and the recovered which is to say extracted pure fluid 6 can be delivered as distillate into an end-container 12, and brine or thickened/concentrated mixed fluid 13 which has a greater share of salts or unwanted substances or contaminants than the mixed fluid 5 from the supply container 11, is removed from the evaporator circuit. As the case may be, gases which cannot be condensed must be sucked out of the condenser 3 by way of a suction device 9, at the end of the condensation path, so that the process runs in an optimal manner.

[0027] FIG. 1b shows an LTD facility 1 with several, for example n stages, wherein in this figure n=4. It comprises n pairs of evaporators 2 and condensers 3, which are indicated here at E.sub.1, . . . , E.sub.n and C.sub.1, . . . , C.sub.n respectively, each with different mean temperatures T.sub.i, i=1, 2, . . . n. The evaporator circuit begins at the hottest stage E.sub.1, whereafter each conduit 7 brings mixed fluid out of an evaporator E.sub.i to the evaporator E.sub.i+1 of the next cooler stage, in order to be brought or sprayed in there. The mixed fluid 5 from the coolest evaporator E.sub.n is subsequently heated by an energy source 8 and is again brought or spayed into the warmest evaporator E.sub.1. The condenser circuit runs counter to the evaporator circuit. The condenser circuit begins at the coolest stage C.sub.n, whereupon each conduit brings pure fluid 6 out of the condenser C.sub.i to the condenser C.sub.i1 of the next warmer stage, in order to be spayed in there. One has forgone the representation of the conduits 7 to the spray-in nozzles and away from the capture containers in the figure, for the purpose of a better overview. The pure fluid 6 from the warmest condenser C.sub.1 is subsequently cooled by way of a heat sink 8 and is again sprayed into the coolest condenser C.sub.n.

[0028] A simple, single-stage embodiment of the LTD facility 1 according to the invention is represented in FIG. 2. The basic distillation process again runs in the same manner as that according to the state of the art. The reference numerals in each case represent the same components.

[0029] The LTD facility 1 according to the invention and of the simplest type comprises only one stage with a mean temperature T.sub.i, for distilling a mixed fluid 5 into a pure fluid 6. It comprises an evaporator 2 with a mixed fluid 5 which can be brought in and which is warmer by T, and condenser 3 with a fluid 6 which can be sprayed in and is cooler by T, as well as vapour spaces 4 which are connected to one another by a vapour connection 10 and in which the pressure and temperature of the evaporator and condenser can equalise in an unhindered manner at all times. Conduits 7 form an evaporator circuit and a condenser circuit, as described with regard to the design according to the state of the art

[0030] The essential difference of the facility according to the invention compared to a LTD facility 1 according to the state of the art lies in the energy source 8 and the heat sink 8 being replaced by other components which are connected to one another. An aggregation device 14 forms the core of the LTD facility according to the invention, surrounded by a supercooling chamber 15, a superheating chamber 16 and a heat exchanger 17. The aggregation device 14 at the entry side is connected to the vapour space of the supercooling chamber 15, wherein captured mixed fluid 5 can be brought from the evaporator 2 into the supercooling chamber 15. At the exit side, this device is connected to the vapour space of the superheating chamber 16, wherein captured pure fluid from the condenser 3 can be sprayed into the superheating chamber 16. In contrast to the conduits 7, in which fluid flows, these connections are vapour connections 10 which are accordingly designed with a large diameter, in order to ensure a good pressure equalisation to the aggregation device 14. Additionally to the actual distillation facility, vapour flows in these vapour connections 10, from the supercooling chamber 15 via the aggregation device 15 to the superheating chamber 16, in which the vapour is condensed again. The aggregation device 14 is connected to an energy source 8 and ensures the cooling of the temperature in the supercooling chamber 15 and the heating of the temperature in the superheating chamber 16.

[0031] A heat exchanger 17 is arranged between the exits of the supercooling chamber 15 and of the superheating chamber. It ensures the cooling of the hot, captured pure fluid 6 from the superheating chamber 16, said fluid being led in a manner cooled by conduits 7, to the entry into the condenser 3. The heat exchanger 17 moreover ensures the heating of the cold, captured mixed fluid 5 from the supercooling chamber 17, said fluid being led in a manner heated by the conduits 7, to the entry into the evaporator 2.

[0032] The conduits 7 in the heat exchanger 17 run in opposite directions, so that a maximal temperature exchange of the two fluids 5, 6 is rendered possible.

[0033] The advantage of the present invention lies in the fact that as a whole, less energy needs to be supplied from the outside, and also less heat needs to be dissipated, in order to achieve the necessary temperature difference of (n+1).Math.T, wherein n indicates the number of stages in the case of multi-stage facilities. The energy source 8 and the heat sink 8 of the state of the art and for cooling and heating the fluids have been brought together for this, by which means heat is recovered or led back into the process. A greater productivity also results due to the fact that vapour from the evaporator circuit is additionally brought into the condenser circuit via the aggregation device 14.

[0034] It is to be noted that the construction of an evaporator 2, of a condenser 3, of a supercooling chamber 15 and of a superheating chamber 16 in principle can be identical. The fluids 5, 6 can be sprayed in with all embodiments. Moreover, each of the mentioned chambers 2, 3, 15, 16 comprises a vapour space 4 and a lower capture container for capturing the introduced fluids, an upper feed conduit 7 to the spray-in facility, a lower discharge conduit 7 out of the capture container, and a vapour connection 10 to or out of the vapour space, as a connection to another vapour space 4 or to the aggregation device 14. Alternatively, for this, the mixed fluid 5 can be brought into an evaporator 2 or into the supercooling chamber, in another manner and spraying in is not absolutely necessary. On the other hand, the harmonisation of the chambers 2, 3, 15, 16 simplifies the LTD facility 1 according to the invention.

[0035] In a preferred embodiment of the invention, the aggregation device 14 comprises at least one sorption chamber 18 and/or desorption chamber 19, with a sorbent 20. The term sorption is to be understood as any type of receiving of a substance at the surface of another substance or in another substance, the so-called sorbent. In particular, the term sorption includes the adsorption, which is the receiving on solid matter, as well as absorption which is the receiving by a fluid. Desorption describes the reverse process of sorption and again releases the sorbed substance. Whereas a sorption takes heat from the substance to be received, desorption returns likewise just as much heat to the released substance. Accordingly, these processes permit the creation of a large temperature difference between the starting substance and the end substance, which is desirable in the present case.

[0036] Thereby, vapour from the vapour space of the supercooling chamber can be sorbed in the sorbent 20 and vapour can be desorbed out of the sorbent 20 whilst inputting energy 8, said vapour finally being able to be fed into the vapour space 4 of the superheating chamber 16. A sorption can firstly be carried out with such a device, wherein only the vapour connection 10 to the supercooling chamber 15 is open, until the sorbent 20 is saturated with enriched vapour which condenses on the surface of the sorbent 20. The vapour connection 10 to the superheating chamber 16 remains closed in this phase. In a subsequent phase, only the vapour connection 10 to the superheating chamber 16 is opened, and the other vapour connection 10 to the supercooling chamber 15 is closed again. Pure fluid 6 is now evaporated again from the surface of the sorbent 20 amid the supply of heat and is brought through the vapour connection 10 to the vapour space 4 of the superheating chamber 16, where it again condenses on the finely spayed droplets of a lower temperature and is finally captured in the container.

[0037] A preferred arrangement with a sorbent 20 is represented in FIG. 3a. In this arrangement, the aggregation device 14 in each case comprises a separate sorption chamber 18 and desorption chamber 19, wherein both are connected to one another by way of at least one connecting channel 21. Transport device 22 are provided for the forward and return transport of the sorbent 20 between the sorption chamber 18 and the desorption chamber 19. Such an arrangement can operate in a continuous manner, by way of sorbent 20 being transported through the connecting channel 21 to and fro between the sorption chamber 18 and the desorption chamber 19, in portions or in a trickling manner, depending on the degree of saturation.

[0038] In an improved arrangement, the sorption chamber 18 and the desorption chamber 19 are connected to one another by way of at least two connecting channels 21, which on use are constantly filled with trickling-through sorbent 20 in a sealed manner. A stepless sorption and desorption process can thus be carried out with the help of transport devices 21, wherein the sorbent 20 passes the sorption chamber 18 and the desorption chamber 10 in a circulation or circuit.

[0039] On the other hand, as is represented in FIG. 3b, a sorption process and desorption process can be carried out in each case in an alternating manner in the sorption chamber and the desorption chamber 18, 19. For this, the functions of the sorption chamber 18 and of the desorption chamber 19 are periodically exchanged with the help of a control device 23, by way of the control device 23 being able to alternating connect the vapour connections 10 to the supercooling chamber 15 or to the superheating chamber 16, to the respective sorption chamber 18 or desorption chamber 19. The energy source 8 is always connected to the respective desorption chamber 19.

[0040] On saturation of the sorbent 20 in the sorption chamber 18 and with the complete drying of the sorbent 20 in the desorption chamber 19, both vapour connections 10 are connected to the respective other chambers 18, 19 so that these change their function. The sorbent 20 remains in the same chamber 18, 19 in each case, and no transport devices 22 are necessary. The energy source 8 is always connected to the respective desorption chamber 19. The control device 23 permits the stepped sorption and desorption, by way of alternating the respective accesses of the vapour connection 10.

[0041] The sorbent 20 can be a solid sorbent for example such as zeolite or silica gel, or in the case of a fluid absorbent, for example ammonia or lithium bromide. A gaseous sorbent can also be applied in principle.

[0042] The LTD facility 1 can be designed with an aggregation device 14 in the form of a compressor or a vacuum pump (FIG. 3c) or in the form of a jet nozzle (FIG. 3d), in two alternative embodiments according to FIGS. 3c and 3d, for producing a vacuum in the supercooling chamber 15 and an overpressure in the superheating chamber 16. Vapour is sucked out of the supercooling chamber 15 and brought into the superheating chamber 18, amid the simultaneous cooling of the supercooling chamber 15 and heating of the superheating chamber 16, with each of the mentioned embodiments of the aggregation device 14.

[0043] In all these embodiments, the necessary temperature difference for the complete LTD facility is produced centrally in the aggregation device 14. This reduces thermal losses which necessarily arise when the heating and cooling is produced separately, for example by way of heaters, fans or heat exchangers.

[0044] The LTD facility 1 according to the invention preferably comprises a suction device 9 for sucking away non-condensable gases at the end of the condensation process in each condenser 3 and in the superheating chamber 16. This suction device 9. when necessary is put into operation as soon as the pressure in a chamber exceeds the saturation pressure of the present vapour by more than a predefined value, which is only a few percent.

[0045] A feed of mixed fluid 5, a discharge of a pure fluid 6 as well as a discharge of brine (concentrated solution) 13 having a higher concentration of salt and/or other impurities/undesired substances than the feed of mixed fluid 5, are envisaged for the operation of the LTD facility 1.

[0046] According to FIG. 4, the LTD facility 1 according to the invention in particular can comprise a multi-stage distillation facility of different mean temperatures T.sub.i, with i=1, 2, . . . n, with n stages. With such a LTD facility 1, all evaporators 2, here indicated at E.sub.i, respectively all condensers 3, here indicated at C.sub.i, of the respective different stages i are connected in oppositely running directions into a circuit by way of conduits 7, as already represented and described in FIG. 1b. A representation of the connection between the heat exchanger 17 and the coolest condenser C.sub.n have been done away with for the purpose of a better overview, and such are represented symbolised by two triangles.

[0047] The supercooling chamber 15 is arranged at the end of the evaporator circuit, i.e. subsequently to the coolest evaporator E.sub.n, in the same manner as if it were to be a further evaporator E. Moreover, the superheating chamber 16 is arranged at the end of the condenser circuit, i.e. subsequently to the warmest condenser C.sub.1, in the same manner as it were to be a further condenser C. The aggregation device 14 is arranged between the supercooling chamber 15 and the superheating chamber 16, and this device is connected to these chambers by way of vapour connections 10, as already been specified. A control device 23 controls the energy feed by the energy source 8 and the aggregation device 14, in accordance with the requirements.

[0048] In contrast to all evaporator-condenser pairs E.sub.i, C.sub.i, i=1 . . . n, whose vapour spaces 4 are connected to one another in each case and thus have the same mean temperature Ti, the temperatures of the vapour spaces 4 of the supercooling chamber 15 and of the superheating chamber 16 and thus of the fluids which are captured therein have the greatest difference of the complete facility. The fluid which are let into these two chambers 15, 16, with the multi-stage method already originate from the coldest evaporator E.sub.n and the warmest condenser C.sub.1, but their temperature difference is increased yet again by the aggregation device 14. The sole energy feed or input for the creating the necessary temperature difference of the various evaporator and condenser stages is introduced into the vapour spaces of the supercooling chamber 15 and of the superheating chamber 16 by way of the aggregation device 14.

[0049] The representation in FIG. 4 is to be understood as a functional schematic representation and not as a spatially optimised specification of the arrangement. In particular, with regard to the conduits 7 in the condenser circuit, the leading of the run-in upwards in each case and the leading of the run-out from below away from the chambers C has being omitted, so that this representation remains clear. On the one hand, it is advantageous if captured, mixed fluid 5 from the evaporator E.sub.n of the coolest stage can be brought or spayed into the supercooling chamber 15, and the captured pure fluid from the condenser 3 of the warmest stage C.sub.1 can be spayed into the superheating chamber 16. On the other hand, it is also advantageous if pure fluid 6 from the superheating chamber and which is cooled in the heat exchanger 17 can be sprayed in at the entry into the coolest condenser C.sub.n, and the mixed fluid 5 from the supercooling chamber 15 and which is heated in the heat exchanger 17 can be spayed in or brought in at the entry into the warmest evaporator E.sub.1.

[0050] Part-flows (not represented) from different condensers C or evaporators E, in conduits 7 or vapour conduits 10 can moreover also be connected to feeding or leading-away conduits 7 and/or vapour conduits 10 of the aggregation device 14 and/or of the heat exchanger 17, in order to achieve further thermal improvements, wherein part-flows can also be fed and/or led away within the heat exchanger 17. Smaller temperature adaptations in individual condensers C and/or evaporators E can be effected by way of this, without external heat being required for this and without heat being lost to the surroundings.

[0051] In a further improved LTD facility, which is not represented, further vapour connections 10 of vapour spaces 4 of different stages are connected by conduits 7 to condensers C.sub.i of other stages with lower means temperatures, for increasing the pressure in the respective conduits 7. The energy consumption for producing the required pressure differences can also be reduced by way of this, additionally to the reduction of the energy effort for producing temperature differences. The LTD facility 1 according to the invention and which is described here can be combined with further optimisation methods without any problem.

[0052] In particular, the heat which is produced in the aggregation device 14 can be distributed in part-flows into several evaporators 2 and/or condensers 3 of different stages E.sub.i, C.sub.i as well as into the superheating chamber 16. This can be achieved for example by way of further heat exchangers which are arranged running oppositely between different conduits 7 being provided additionally to the mentioned heat exchanger 17.

LIST OF REFERENCE NUMERALS

[0053] 1 low-temperature distillation facility (LTD facility)

[0054] 2 E, E.sub.i evaporator

[0055] 3 C, C.sub.i condenser

[0056] 4 vapour space

[0057] 5 mixed fluid

[0058] 6 pure fluid

[0059] 7 conduits, fluid conduits

[0060] 8 energy source, heat sink

[0061] 9 suction device, V

[0062] 10 vapour connections

[0063] 11 supply container of mixed fluid

[0064] 12 end container with pure fluid, distillate

[0065] 13 brine

[0066] 14 aggregation device

[0067] 15 supercooling chamber

[0068] 16 superheating chamber

[0069] 17 heat exchanger

[0070] 18 sorption chamber

[0071] 19 desorption chamber

[0072] 20 sorbent

[0073] 21 connecting channel

[0074] 22 transport device

[0075] 23 control device

[0076] 24 compressor, vacuum pump

[0077] 25 jet nozzle