US2963875A - Heat pump - Google Patents

Description

Dec. 13, 1960 E. MILLS 2,963,875

HEAT PUMP Filed May 18, 1953 3 Sheets-Sheet l V 9 REL T 25 T l9 COOLING WATER w 5 l7 L z 23 WI HEATER 23 INVENTOR.

Dec. 13, 1960 Filed May 1953 3 Sheets-Sheet 2 L L ,14%) can: I l I I i E BRINE I I 1 I I COOLING n r] I I I I WATER /22 LHE'VATER INVENTOR.

L. E. MILLS Dec. 13, 1960 HEAT PUMP 3 SheetsSheet 3 Filed May 18, 1953 SOL INVENTOR.

United States Patent HEAT PUMP Lindley E. Mills, 518 Pinehurst Blvd, Kalamazoo, Mich.

Filed May is, 1953, Scr. No. 355,750

2? Claims. (CI. 62-112) This invention relates to the transfer of heat, particularly to a novel method and to-apparatus and compositions useful for transferring heat from a region of lower temperature to a region of higher temperature. This application is a continuation in part of co-pending application Serial No. 75,079, filed February 7, 1949 and now Patent No. 2,638,760.

The transfer of heat from a region at one temperature to a region at a higher temperature is necessary in many processes, including such extensively practiced processes as refrigeration, air conditioning and cooling operationsin general. In such processes, heat is extracted from one region, thereby reducing its temperature to a desired degree, and discharged to another region, thereby increasing its temperature. In refrigeration or cooling practice the discharged heat is generally dissipated by cooling water or air, or in some other convenient way. The apparatus and systems of substances used in transfering heat from one region to a region of higher temperature is generally referred to as a heat pump.

Of increasing importance is the use of this type of process primarily for the purpose of heating by utilizing thetransferred heat liberated in the region of higher temperature for useful purposes, the heat extracted from the region of lower temperature being in this instance replenished from any convenient low cost source, such as the atmosphere, water, and the like. Buildings have been heated satisfactorily in this manner by extracting heat from the air or water out of doors, or even from the soil, and discharging it inside the building.

, The transfer of heat from a region of lower temperature to a regionof higher temperature has heretofore practically always been effected by one of two processes. In one of these processes, referred to as the compres sion process or method, a liquid of suitable boiling point is caused to evaporate in a vaporizer in the region'being cooled thus absorbing heat from the region. The vapor is removed continuously from the vaporizer by a pump and compressed. The compressed vapor is then cooled in acondenser, e.g.'with air or cooling water, to convert it to liquid form, after which it is reintroduced into the vaporizer to effect further cooling. A number of low boiling substances have-been used, or proposed for use, in this process including ammonia, sulfur dioxide, carbon dioxide, dichlorodifluoromethane, methyl chloride, propane and many others including even water. .In thecase of water the vapor is-generally discarded and fresh water introduced into the vaporizer. A refrigerant having a high latent heat of vaporization and a suitably low boiling point is desirable for use in this process to reduce'the weight of material cycled per unit of refrigeration effected and to avoid the necessity for using a highly evacuated vaporizer. This method involves the use of costly compressing machinery and of a source of relatively costly energy to operate the compressor.

The other generally utilized method for efi'ecting refrigeration, referred to' as the absorption method, in-

vol-ves' the-boiling'of substantially anhydrous-ammonia in- 2,963,875 Patented Dec. 13, 1960 a vaporizer to cool the latter and the absorption of the vapors in relatively dilute ammonia in an absorber. The heatwhich is evolved in the absorber is dissipatedwithair or cooling water. The efiluent from the absorber, which is relatively rich in ammonia, is then transferred to a still, or generator, operating under a higher pressure than that prevailing in the absorber and vaporizer, and fitted with a fractionatin'g column. In this apparatus a portion ofthe ammonia is distilled and led to a con: denser where it is cooled and collected in as nearly anhy drous .form as possible. The collected liquid ammonia is, then reintroduced into the vaporizer and the weak} am monia liquor remaining-in the still is reintroduced into the absorber. This process is less economical in the expenditure of energy to produce a given unit of refrigeration than is the compression system, but the energy can be supplied. in the form of a fairly low grade heat source so that the system or process finds extensive use in situa' tions where a large amount of refrigeration is desired and a relatively inexpensive source of heat at a suflic'iently high temperature, e.g. at about 3 to about 50 lb./sq. in. gauge, is available in large quantities. The equipmentto operate the process is, however, costly to install, even though no gas compressor is required, because of the necessity of carrying out the fractional distillation of the strong ammonia liquor under considerable pressure. In practice, only a small proportion of the ammoniais distilled from the strong liquor during each cycle. This re-' quires the circulation in the apparatus of a very large proportion of the ammonia in the form of relatively di= lute liquor without its ever being used to effect refrigera tion.

In both of the conventional methods for effecting cooling just described, the principal cost of operation usually arises from the necessity of expending energy to restore the refrigerant evaporated in the vaporizer to a liquidcondition wherein it can be reintroduced into the vaporizer and used again. The same is true when either method is used'for heating purposes rather than for refrigeration, the principal difference being that the desired efiect is obtained by utilizing the heat discharged to the absorber" or condenser, respectively. It isapparent-that the present. status of the refrigeration art leaves much to be desired both in the way of simplicity and cost of apparatus and in the cost of operation, and that any-improvements in either respect would be of great value. i

In the co-pending. application referred to thereis' in the parent application and with apparatus and systems of substances whereby the new method an'd th'e' variatio'nsthereof can be carried out easily'an'd' economically.

The, method for effecting refrigeration described in the parent application utilizes a system of substances com-- prising a low-boiling component and a high-boiling component chosen so that the coeificient of solubility "with respect to temperature of the low-boiling component inthe high-boilin component is negative when both sub-* stances are in liquid form. Under such circumstances,'

the solubility of the low-boiling component in the high-- boiling component decreases as the temperature of the mixture is raised and, provided the substances are present in proper proportions, two liquid phases are presentin" thex heated mixture, one of which is rich in the low boiling component and the other of which is rich i'n'the high boiling component. 7'

equilibrium. with one another. are known as conjugate solutions." 7

It frequently happensin such systems that at some low temperature, depending upon the particular system involved, the liquidphases: merge and the system becomes homogeneous. The temperature at which this occurs is known as a lower consolute temperature? or a lower I critical solution temperature. Such'a system, whether or 'not it has a lower'consolute temperature, is herein'some- -S uchliquid phases which are in times referred to as a negative conjugate system'to distinguishitfrom the better kown .positive conjugate'systerns, ,wherein the coefficients ofsolubility with respect to temperature; of the components in one another are positive; Suchlatter systems'rnay have an.npper consolute temperature or upper critical solution'tempera-v a-honrogeneous mixture.

. In the method described in the parent application a negture;abov.e. which the conjugate solutions mergeto'give ative conjugate system is heated in a closed vessel under pressure, herein referred to as a separation pressure,

' sufliciently highto maintain it substantially in liquid form, i.e. under at least its substantial total vapor pressure, at

separate containers connected by a vapor conduit, eg in a vaporizer and in an absorber, respectively, of a conventional absorption type refrigeration apparatus, and the high-boiling solution is cooled by any appropriate means,

.eg by cooling water. or air. Under such conditions, vapor of the low-boiling component distills from the low-boiling solution, which'is thereby impoverished with respect to aeeas'za V i In the present application there are described apparatus in which the new cycle can be carried out, systemsof substances which can be employed in carrying out the cycle and variations in the cycle itself which are of value in effecting the transfer of heat from a region of lower temperature to a region of higher temperature. These features and their advantages will be apparent as the description proceeds. l

The invention can be readily understood by reference to the accompanying drawing wherein, in the interest of clarity, certain features are shownon a somewhat exaggera ted scale and wherein: V

Figure 1. is a schematic representation ofzapparatus useful in carrying out. the method or cycle of the invention. 7 A

Figure 2 is a schematic representation of a modification of the apparatus of Figure 1 showing certain features more in detail.

the-low-boiling component and cooledand is thus available for refrigerating purposes, and .is absorbed or dissolved in' the high-boiling solution, which is thereby enriched with respect to'the low-boiling component, the heat of absorption being dissipated by the cooling means. This process continues until interrupted or until theftemperature ofthe low-boiling solution and the concentrations of the low-boiling component in the high-boiling and inthe:

low-boiling solutions have attainedvalues'such that the V 7 partial vapor pressure of the low-boiling" component in each solution at the respective temperatures 'is the s ame. 'I'he impoverished low-boiling solution remaining in the vaporizer and the enrichedloW-bOiling solution remaining inthe absorber. are subsequently vcombined tov furnish the:

original negative conjugate, system which is'athen heated as in the step first describeda A. complete refrigeration .cycle is thus efiectedl wherein the gaseous. refrigerantis restored to itsliquid stateready for re-use without the expenditure and the subsequent dissipation of energy corresponding to the energy of liquefaction described-previously, Furthermore; since only liquids are' concerned in the'heating and separation steps and in the return of the conjugate'solutions to the absorber and vaporizer, respectively, heat interchangers can be employed advantageously to :carry out the first stages of the heating stepj-using the hot separated high-boiling and low-boiling conjugate solutions and the latter thereby cooled before being introduced. into the absorber and vaporizer, respectively. In practice, the cycle is prefer- 7 ably carriedout in continuous fashion, the conjugate solutions beingseparated and conveyed to theabsorber and; vaporizer, respectively, and the enriched and impoverished solutions being withdrawn therefrom and heated, all

in continuous manner. In this way substantially constant conditions of temperature and pressure can be maintained in particular part of the cycle. 7

Figure 3'isa schematicrepresentation'of afu rther modification of the apparatus ofFigure-l.

Figure 4 is a schematic epresentation .of a modification of a part of the apparatus of Figure 1 illustrating its general applicability in other processes. a

Figure 5 Ba schematic representation of a'modification of the apparatus of Figure 4. t Y 7 In the operation of the new method or cycle utilizing a negative conjugate system, as illustrated by reference to Figure 1, the system is heated under a separation pressure greater than its vapor pressure to maintain the components in substantially liquid form in any conventional heater 12 to a separation temperature at which a desired degree of separation of the components into conjugate solutions is effected, one of which is rich in the lowboiling component and the other of which is rich in the high-boiling component. The solutions are then separated mechanically from one another in liquid form, as in a separator 13, which will be described later, without substantial decrease in the pressure and temperature below the separation temperatureand pressure. The low-boiling' solution, i.e. theconjugate' solutionfn'ch inthe lowboiling component, is then conveyed as by way of a conduit 25 and a pressure relief valve. 42 into a conventional vaporizer 26 and the'high-boiling solution, i.e. the conjugate solution rich in the high-boiling component, is

conveyed as by way of a conduit 17 and-a pressure're'lief valve 41' into an absorber 18 and'cooled therein to an absorbing temperature, e.g. 'by' cooling 'water flowing through a coil 19 or-by-air. "The vaporizer 26 and the absorber .18 are connected by a'vapor conduit 40 to permit free flow of vaporbetween them. Due tothe effect of the cooling water on the high-boiling solution in the absorber 18 and to the relatively low proportion of lowboiling; component therein, its vapor pressureis reducedf greatly and .vapor of the low-boiling component' flows from the vaporizer 26 into the absorber 18 and sorbed in the high-boiling solutiontherein.

Thisprocess continues until the temperature of the lowboiling solution in the vaporizer'26'is'redu ced to'an evaporation. temperature such that'its -vapo'r' pressure is equal to the vapor pressure of the high-boiling solution at the absorbing temperature prevailing in' the' absorber 18.

Because of the relatively low vapor pressures of; the components other than the low-boiling component, the total vapor pressures 'of the 'solutions correspond'closely to the partial vapor pressures of the low-boiling' component in the two solutions. 7 the low-boiling component in the low-boilin'g'solution introduced into the vaporizer 26 is very much greater than it is in the high-boiling solution introduced into the absorber 18 and due, further, to the fact that the solubility of the low-boiling component in the high-boiling component is greater at the absorption temperature'than at the separation temperature, the low-boiling solution in the vaporizer 26; is cooled to a temperature many degrees below the temperature prevailing in the absorber .18. This fall inf temperature in, the vaporizencan thus be for is ab- Due to the fact that the concentration of cooling or refrigeration purposes, e.g. by circulating brine through a coil 27 in the vaporizer 26 or in any other convenient manner.

The product from the absorber 18, consisting of the high-boiling conjugate solution which has been enriched with low-boiling component, and any liquid residue remaining in the vaporizer 26, consisting of the low-boiling solution impoverished with respect to the low-boiling- COIIIPOIIEHL'Z'HB conveyed, as by conduits 43, 44 and 46 and pump 45 to the heater 12, and the cycle repeated. As generally practiced, the method is carried out continuously, the system of substances being circulated continuously after the fashion just described.

It is to be noted that in the operation of the process the pressures prevailing in the absorber 18 and in the vaporizer 26 are at all times equal to one another and that the pressures prevailing in the heater 12 and the separator 13, and in the conduits communicating therewith between the pump 45 and the relief valves 41 and 42, are also at all times substantially equal to one another, but that this latter pressure is higher than that prevailing in the absorber and vaporizer. This latter condition follows from the fact that the vapor pressure of the system of substances in the heater and separator at the separation temperature, which pressure is at least equaled by the pressure developed by the pump 45, is greater than either the vapor pressure of the high-boiling solution at the absorber temperature or the vapor pressure of the low-boiling solution at the evaporation temperature. In the modification shown, the relief valves 41 and 42 are set to open at a pressure higher than the vapor pressure of the system prevailing in the heater and absorber, but less than the maximum pressure at which the pump 45 is capable of forwarding the system through the heater and separater. In this way a constant flow of liquid substantially free from vapor can be maintained through the heater and separator, and a proper pressure differential can be maintained automatically between the absorber and vaporizer on the one hand and the heater and separator on the other hand.

It is, of course, understood that the entire apparatus is, prior to its operation, purged of air and that during operation any air which is allowed to enter the apparatus inadvertently should be purged therefrom for best operation of the process. In many instances the lowboiling component at least, e.g. ammonia, will have a boiling point sufiiciently low that the entire apparatus is at all times under greater than atmospheric pressure during normal operation of the process. Under such conditions any leakage which may occur will be outward and will not result in the introduction of air into the apparatus.

The apparatus which can be used in carrying out the process and the flow of substances in the process is subject to considerable variation without departing from the spirit of the invention. Thus, in Figure 2, certain features of which will be described in more detail later, there is shown one modification wherein the enriched high-boiling solution from the absorber 18 and the impoverished low-boiling solution from the vaporizer 26 are forwarded by separate pumps 20 and 30, respectively, to the heater 12. The use of separate pumps in this fashion to develop pressure on the two solutions before they are combined is sometimes advisable, particularly when there is a tendency for heat to be developed upon mixing the two eflluents. In such an instance the vapor pressure of the warm mixture may be greater than that prevailing in the absorber 18 and vaporizer 26 and there is thus a tendency for the mixture to back up into the vaporizer or the absorber or both. When two pumps are employed they are generally synchronized so as to forward the respective solutions at approximately the respective rates which will result in maximum efiiciency of operation of the cycle. When separate pumps are provided as shown in Figure 2, it is sometimes advisable to provide a cross connection, such as a conduit 48, between the conduit 49, extending between the absorber 18 and the pump 20, and the conduit 51, extending between the vaporizer 26 and the pump 30. By providing the conduit 48, which is generally of smaller diameter than the conduits 49 and 51, any variation on the part of the pumps 2!} and 30 in removing the solutions from the absorber 18 and the condenser 26 at the precise rate at which they collect therein is compensated for by flow of a small amount of one of the solutions through the conduit 48 so that it mixes with the other solution. Such mixing of a small proportion of one of the solutions with the entire amount of the other solution does not generally produce any significant temperature rise in the mixture. The conduit 48, can, of course, extend between the vaporizer 26 and the absorber 18 either below or slightly above the normal level of the liquids therein and the same result be accomplished.

Heat exchangers can also be employed, if desired, to promote the efiiciency of the process and to reduce the amount of heat necessary to be supplied prior to the separation. In Figure 2, for example, there is indicated at 32 a heat exchanger of any conventional type by means of which heat is exchanged between the hot lowboiling conjugate solution flowing in the conduit 25 from the separator 13 and the impoverished low-boiling solution from the vaporizer 26 which is being forwarded by the pump 36 through the conduits 31 and 11 to the heater. In this manner the temperature of the low-boiling conjugate solution entering the vaporizer 26 is lowered, thus reducing the amount of vaporization which must occur from the solution to lower its temperature to the temperature being maintained in the vaporizer, and at the same time the temperature of the impoverished lowboiling solution to the heater 12 flowing in the conduits 31 and 11 is raised, thus reducing the amount of heat which must be supplied to the system in the heater 12'. In the same manner, heat can be exchanged, as in an exchanger indicated at 24, between the enriched highboiling solution flowing from the absorber in the conduits 23 and 11 to the heater, and the high-boiling conjugate solution flowing in the conduit 17 from the separator 13 to the absorber 18. In this manner, the amount of heat necessary to add to the system in the heater 12 is further reduced and the amount of cooling water necessary to be circulated in the conduit 19 is reduced.

Certain other arrangements of heat exchangers are also of value in certain instances. Thus, in the arrangement shown in Figure 3 the low-boiling conjugate solution flowing from the separator 13 to the vaporizer 26 through the conduit 25 can be first forwarded through a heat exchanger 52 where it exchanges heat with the relatively cool enriched high-boiling solution from the ab sorber, which is being forwarded by the pump 20 through the conduits 23 and 11 to the heater, and thenthrough a heat exchanger 53 where it exchanges further heat with the colder impoverished low-boiling solution from the vaporizer 26, which is being forwarded by the pump 30 through conduits 31 and 11 to the heater. This arrangement is sometimes particularly advantageous because the amount of impoverished low-boiling solution flowing from the vaporizer 26 is considerably less than the amount of low-boiling conjugate solution entering the vaporizer 26 by way of the conduit 25. On the other hand, the amount of enriched high-boiling solution flowing in the conduit 23 is considerably greater than the amount of high-boiling conjugate solution fiowingin the conduit 17. By first pre-cooling the low-boiling conjugate solution in the heat exchanger 52 and then forwarding it through the heat exchanger 53, its final tem perature as it enters the vaporizer 26 is lower than if it were caused to exchange heat only with the impoverished low-boiling solution from the vaporizer as in the modification of Figure 2. The high-boiling conjugate solution, flowing from the separator 13 through the-conduit -17 to theabsorber 18, can, with advantage, be forwarded througha heat exchanger'54 wherein it is caused to exchange heat withthe enrichedhigh-boiling solution from the absorber 1-8 after the latter has exchanged heat with the low-boiling conjugate solution." In this manner the enriched high-boiling solution is warmed still further and at the same time the high boiling conjugate solution flowing in the conduit 17 .is cooled to a considerable degree.. -'In addition, the high-boiling conjugate solution flowing in the conduit 17. can, before it enters the absorber 18, be conveyed through another heat exchanger or pre-cooler 55 wherein it is cooled by cooling water to substantially the same temperature as that prevailing intheabsorberlS. Other appropriate arrangements of .heat exchangers whereby the ratio of heat extracted from the cooling medium circulating in the conduit 27 in the vaporizer 26 to the amount of heat supplied to the heater 12 can be increased willbe apparent as the description proceeds. The particular arrangement of heat exchangers and-the number thereof employed in any particular instance will, of

course, depend upon a number of factors including the particular system ofsubstances used, the degree of cooling or refrigeration desired, the arrangement of the other units of the apparatus, and upon other factors.

The absorber 18 and the vaporizer 26 can, in most instances be of any suitable and conventional construction, it being only desirable that as good heat exchange between the solutions therein and the cooling medium, e.g. cooling water'flowing in the conduit 19, on the one hand and the refrigerating medium, e.g. brine flowing in the conduit 27, on the other hand be provided for. In one suitable modification, shown somewhat in detail in Figure 2,'the absorber 18 consists of a closed vessel of suitable dimensions containing a coil 19 through which cooling water is circulated. The high-boiling conjugate solution is distributed over the coil by a spray head 21 as it enters the vessel in such a manner that it trickles downward over the turns of the coil. During its travel downward over the coil, it is continuously cooled and presents a large surface to the atmosphere of vapor entering the absorber from the vaporizer 26 through the vapor conduit 40. The vapor conduit 40 should be of sufficiently large internal diameter to avoid substantial restriction to the flow of vapor through it. Enriched high-boiling solution dropping from the coil 19 collects in the bottom of the absorber 18 as a liquid layer 22 and is subsequently removed by the pump 20.

In similar manner brine which is to be cooled to serve as a refrigerating medium circulates in a coil 27 in, the vaporizer vessel 26. The low-boiling conjugate solution enters the vaporizer through a spray head 28 and trickles down over the turns of the coil 27 during which time lowboiling component evaporates from it and flows out of the vaporizer through the vapor conduit 40. The brine flowing in the coil 27 is thus chilled to the desired temperature and is then available for cooling and refrigerating purposes. The unevaporated impoverished low-boiling solution collects as a liquid layer 29 in the bottom of the vaporizer 26 and is subsequently removed by the pump 30.

' or in an insert therein, of the vessel 13 and communicat In similar fashion the lower Theseparation of the conjugate solutionsfrom one the system 'of'substances substantially in the liquid form;

One particularly convenient apparatus for separating the conjugate solutions from one another is shown somewhat in schematic form in Figure 2. The separator comprises the vessel 13 of suitable construction to withstand the necessary internal pressure. The heated system of substances comprising both high-boiling and low-boiling components enter-the separator byway of aconduit 47 and in the separator form two distinct liquid layers 14 and 15 of the conjugate solutions. In the modification shown, the lowboiling conjugate solution 14, which is rich .inthe low- 'boiling component, has a density less than that of the high-boiling conjugate solution 15, which is poor in the low-boiling component. The low-boiling conjugate solution 14 collects in the upper part of the vessel 13 from where it is conducted by way of conduit 25 to the vaporizer 26 as described previously. The heavier'high-boiling conjugate solution 15 collects in the lower part of the vessel 13 and is subsequently conveyed to the absorber 18 by way of the conduit 17 as described previously. The conjugate solutions have aconnnon interface 56. In certain instances itis advantageous to combine the heating and separating means in the same piece of equipment rather than to perform these operations separately.

, To provide for automatic regulation of the discharge of the two conjugate solutions 14' and 15 from the separator, a float 39 is provided inside the vessel 13 which, together with the members attached thereto to be described, has an average density intermediate the densities of the conjugate solutions 14 and 15. The float, therefore, seeks and assumes a position in the vessel 13 such that it floats on the interface 56 between the two conjugate solutions. The float 39 rises and falls as the interface 56 rises and falls with changing ratios of the amounts of conjugate solutions 14 and 15 in the vessel 13. The float is provided with suitable top and bottom valve rods or projections 33 and 57, respectively. The rod 33 is shaped at its upper end to form a valve face 35 adapted to fit into a valve seat 37 formed in the upper end, e.g. in the cover ing with the conduit 25. rod 57 is shaped at its lower end to form a valve face 36 adapted to fit into valveseat 38 formed in the bottom wall, or in an inserttherein, ofthevessel 13 and communicating with the conduit 17; A suitable adjustment 34 is provided integral with the rod 57 so that the distance of the valve faces 35 and 36 from one another can be adjusted. This latter distance is adjusted so that, when either of the valve faces 35 or 36 is seated in its respective valve seat 37 or 38, the other valve face isremoved from its valve seat by a suitable distance and thus provides a means for fluid to flow out of the separator 13.

In operation, with either a steady or an intermittent flow of fluid into the separator through the conduit 47, one or the other of the valves 35 or 36 will be open at all times.

In certain instances both valves will'be at least partially open; When more than a normal amount of the heavier high-boiling conjugate solution 15yis in the vessel, the float 39 rises and closes the valve 35 at the same time opening the valve 36 thus preventing flow of the lighter low-boiling conjugate solution 14 from the vessel 13, but permitting flow of the heavier high-boiling conjugate solution 15 firom the vessel 13. When the vessel 13 contains an excess of the lighter low-boiling conjugate solution 14 the float 39 falls slightly opening the valve 35 and closing the valve 36, thus permitting a part of the low-boiling conjugate solution 14'toflow from the vessel, but preventing the high-boiling conjugate solution 15from flowing from the vessel. In steady operation of the apparatus it is generally found that the float 39 maintains an intermediate position so long as the feed to the separator is substantially constant and the relief valves 41' and 42 are set to open'at the same pressure. Under such conditions the conjugate solutions 14 and 15 both flow continuously from the separator in the same ratio in which they enter the vessel through the conduit 47.

It is to be noted that the separating apparatus asdescribed operates with the vessel 13 entirely full of liquid and free from any vapor space. Any vaporwhich may accumulate in the apparatus through accident or inadvertence escapes immediately through the upper valve 35. It is to be noted, further, that inthe modification described wherein the pressure in the separator is greater than the vapor pressure of the system of substances therein, the pressure is maintained by the operation of the pumps and Working against the setting of the relief valves 41 and 42 and that the operation of the separator is independent of the setting of the relief valves. Should the relief valves 41 and 42 be set to open at difierent pressures, the inequality is compensated for by the operation of the separator. Each conjugate solution is permitted to flow through the respective relief valve only in proportion to the rate at which it enters the separator. The hydrostatic pressure maintained in the separator vessel 13 by the pumps, although it may vary somewhat depending upon any inequality of setting of the relief valves 41 and 42, will at all times be sufficient to force fluid through the particular relief valve to which fluid is being supplied. When the overall composition of the system of substances being used and the temperature of the system attained in the heater 12 are adjusted to optimum conditions, the entire apparatus operates with maximum efliciency attainable with the temperature of the cooling Water employed.

The operation of the apparatus shown in Figures 1, 2 and 3 when using a particular system of substances can be controlled in a number of ways. Thus the pump 45 of Figure l, or the pumps 20 and 30 of Figures 2 and 3, can be operated intermittently or at a variable speed and the amount of low-boiling conjugate solution which is introduced into the vaporizer 26 can be controlled to provide for periods of high and low refrigeration demand. When two pumps are employed, e.g. pumps 20 and 30 of Figures 2 and 3, the rate of flow of the impoverished low-boiling solution and of the enriched highboiling solution can be regulated to some extent independently of one another to provide for optimum efficiency at different vaporizer temperature levels if this appears desirable. The operation of the pumps can be controlled automatically either in response to the pressure prevailing in the vaporizer and absorber or in re sponse to the temperature of the cold brine leaving the vaporizer through the conduit 27 or in response to the temperature of any other control point desired. The operation of the apparatus and the amount of cooling produced can also be controlled to some extent by regulating the temperature to which the system of substances is heated in its passage through the heater 12. Regulation in this manner may alter to some extent the efliciency of Operation of the entire apparatus because of its effect on the degree of segregation of the low-boiling and high-boiling components into the lowboiling andhigh-boiling conjugate solutions, respectively, in the separator.

Although the separator just described, together with certain modifications thereof, is preferred in the operation of the process as usually carried out for refrigerating or cooling purposes, any other convenient separating apparatus can be employed. The separator described can, however, be employed for the continuous separation of any immiscible liquids used in applications other than in the heat pump with which the present application is concerned. In Figure 4, for example, there is shown an adaption of the separator to the separation of immiscible liquids under atmospheric pressure wherein open vessels can be used. In this modification the mixture which is to be separated is fed by gravity or by a suitable pump 57 through a conduit 58 into the open tank 59 where it separates by gravity into a lighter liquid phase 61 and a heavier liquid phase 62. A float 63 is mounted on a float arm 64 which is pivotally mounted to pivot in a vertical plane on a bracket 65 secured to a wall of the tank. Brackets 66 and 67 are also secured to the wall of the tank one being above and one being below the bracket 65. A rotary member 68, conveniently a triangular plate, is pivotally mounted on the bracket 66 so that it is free \to pivot vertically. A valve rod 69 is pivoted at one of its ends to an upper corner of the plate 68 so as to travel horizontally as the member 68 pivots at 66. The rod 69 is formed at its other end with a valve surface 71 contoured to fit a valve seat 72 which is in communication with a conduit 73 which in turn leads to a storage tank 74. A lifter rod 75 is pivotally mounted at one of its ends on the third corner of the plate 68 and at its other end on the float 63 or the float rod 64. In similar manner, another triangular plate 76 is pivotally mounted so as to pivot in a vertical plane on the bracket 67 and is connected with the float 63 or the float rod 64 by the pivotally mounted rod 77. A valve rod 78 is pivotally mounted at the lower corner of the plate 76 and is formed at its free end with a valve surface 79 adapted to engage and close a valve seat 81 which is in turn in communication with a conduit 82 leading to a second storage tank 83. Drawoif valves 85 and 85 may be provided to permit removal of the separated immiscible liquid phases from storage tanks 74 and 83 as desired.

The modification just described operates in a manner similar to the modification described previously. The float 63 has a density intermediate the two liquid phases and floats at the interface between them. When an excess of the heavier immiscible phase 62 enters the tank 59.the float 63 rises and the rotatable members 68 and 76 rotate clockwise. The valve surface 79 movm away from the valve seat 81 thus opening the valve wider and permitting more of the liquid 62 to flow by gravity into the storage tank 83. At the same time the valve surface 71 approaches the valve seat 72 and reduces the rate of flow of the liquid phase 61 from the tank. When an excess of the lighter liquid 61 enters the tank 59, the float 63 is lowered and the rotatable members 68 and 76 rotate counterclockwise, the operation of the valves is reversed permitting more of the lighter liquid 61 to flow into the storage tank 74 while decreasing the rate or stopping the flow of the heavier liquid 62 into the storage tank 83. It is apparent that, in the operation of this modification wherein the flow of fluid is largely by gravity, the tanks 59, 74 and 83 should be located with due regard to their relative elevations.

Although the utilization of a float arrangement for operating the outlet valves from the separator, such as those shown in Figures 2 and 4, is generally satisfactory and preferred it frequently happens that the actual differences in specific gravities of the liquid phases being separated is very small and that the utilization of a float to operate the valves becomes unwieldy because of the large size of the float Which is needed. In such an instance it is sometimes convenient to operate the valves by other means. One such arrangement is shown in Figure 5 wherein the diflerence in electrical conductivity of the two liquid phases is utilized to accomplish this purpose. The mixture to be separated is supplied to the separator vessel 86 by way of a pump 87 and a conduit 88. The mixture separates in the vessel 86 into a lighter upper layer 108, which, for example, is assumed to be a poor conductor, and into a heavier lower layer 107, which here is assumed to be a good conductor. A baffle plate 89 can be secured inside the vessel opposite the conduit 88 to prevent undue turbulence at the liquid interface 91. The vessel 86 is equipped at its top with a drawoff conduit 92 and a solenoid valve 93, normally in a closed position. It is also equipped at the bottom with another drawoff conduit 94 and another solenoid valve 95, also normally in closed position. Although the valves 93 and 95 are, in the modification shown, operated by solenoids, they can be motor operated or operated automatically in any other convenient manner.

A pair of electrodes 96 is positioned within the tank 86 at the level near which it is desired to maintain the liquid interface 91. The electrodes are connected by insulated leads 97 through an insulating plate 98 in the wall of the vessel to terminals 99 outside the tank. These terminals are in turn connected by appropriate lead wires in series with a battery 101 and a relay 102 in such fashion that the relayis energized when current flows between the electrodes 96 A variable resistance 109 can be inserted in therelay circuit to prevent the flow of enough current between the electrodes 96 when they are immersed in 'the liquid phase 108, which is the least conductive of the two phases, to activate the relay 102, but to allow activation of the relay when the electrodes protrude intothe'more conductive of the liquid phases 107. The relay controls the flow of current from a source of 103 to the valve 95, when the electrodes 96 electrodes 96 are surrounded entirely by the poorly conductive liquid layer 108 and the relay is not activated. In this way, when the interface 91 rises, the relay 102 is activated, the valve 93 remains closed, the valve 95 opens and some of the liquid phase 107 flows from the separator. When the interface 91 falls, the relay 102 is no longer activated, the valve 95 closes, the valve 93 opens and some of the lighter liquid layer flows from the separator. I

Still another modification of the separator utilizes the difference in light absorptive properties of the phases together with suitable photoelectric cells and electronic controls to operate the valves controlling the flow of the liquid phases from the apparatus. The separator described can be used advantageously for separating any immiscible liquids regardless of the pressure under which the operation is carried out so long as they differ from one another sufiiciently in one property to enable automatic control to be efiected. Mixtures whichmay be separated include mineral oils and water, vegetable oils' and water, mineral oils and aqueous alcohol, aniline and water, sulfuric acid and mineral oil, liquid sulfur dioxide and mineral oil, alcohol and strong soda ash solution, and many others.

The pumping means 45 of Figure 1 and 20 and 30 of Figures 2 and'3, employed in operating the heat pump with which the present application is concerned can com prise any suitable means for forwarding the respective depending upon the circumstances, be capable of handling such liquids as aqueous ammonia, aqueous sulfur dioxide, aqueous weak acids, aromatic hydrocarbons, ammoniacals copper salt solutions and the like without undue corrosion. a y

'Because the new method is a species ofabsorption method it may at times be advisable to include a certain amount of a gas of low density, e.g. hydrogen or helium, with the substances charged into the apparatus to 'assist in the circulation of vapors of the low-boiling component from'the vaporizer to the absorber as is 'practiced in well known manner in one modification of the conventional ammonia absorption system. When such a low density gas is used, it should, of course, be as little soluble in the liquid components of the system as possible.

, In addition, provision should be made in the apparatus for continuous recycling of the gas between the vaporizer and absorber and back again. This is conveniently accomplis'hed by providing a'second vapor conduit, shown in dotted outline at 50 in Figure 1, between the vaporizerand absorber andlocated below the vapor conduit 40,

preferably just above the maximum level of liquid collecting in either the vaporizer 26 or the absorber 18.

It. should be pointed out that the method'of the inventioncan be considered as comprising the circulation of a'high-boiling component first through the separator 13, referring to Figure 1, then through the absorber 18 and then back to the separator while simultaneously forwarding a low boiling component through the separator 7 component in the .vaporizer 26 and the consequent nonequilibrium existing between the two liquids in the vaporizer and absorber, vaporization of a part of the lowboiling'componentsand absorption thereof in the highboiling component occurs, as described previously.

It thus becomes more clear that the rates of circulation of the high-boiling and low-boiling components can 7 be varied independently of one another, e.g. by dual pump 20 and 30 of Figure 2, over. rather wide limits without atthe same time changing the amount of either of the components contained in the apparatus. It is apparent that an optimum value for this ratio, as well as for the total amount of each component circulated, will exist in each particular instance, depending upon'the ratio of the actual amountsofthe respective components making up the system and the performance expected.

Inasmuch as a portion of the high-boiling component circulates with the low-boiling component, because of the incomplete separation of the substances in theseparator, the two portions of high-boiling component, i.e. that which circulates through the absorber 18 and that which circulates through the vaporizer 26 can be thought of separately. The operation of the system can then be thought of as comprising the cycling of a first portion of the high boiling component first through a separator 13 and then through an absorber 18 and back to the absorber While simultaneously cycling a second portion of the high-boiling component through the separator 13, thence through a vaporizer 26 and back to the separator 13, the conditions in the separator 13 being maintained such that the second portion of the high-boiling component is enriched therein with the low-boiling component at the expense of the first portion and the conditions in the absorber 18 beingmaintained such that the first portion of the high-boiling component is enriched therein with the low-boiling component at the expense of the second portion, i.e. by vaporization of low-boiling compo nent from the latter. When regarded in this manner it is seen that the first and second portions of the high-boiling component can be cycled at rates independent'of one another within wide limits and that an optimum ratio of such rates can be found for each particular set of circumstances. a i j n 1 A further modification involves the replacing ,of either of the portions of high-boiling component with a second high-boiling component, immiscible-with the first'highboiling component, and circulating the two high-boiling components with the accompanying low-boiling component. Here again, the rates of'circulation of the two high-boiling components can be effected at an optimum ratio. Thus, the second portion of high-boiling component, referred to in the preceding paragraph, can be replaced with a suitable water-immiscible substance, e.g. an aromatic hydrocarbon, such as meta-xylene, to-form the system composed of ammonia, meta-xylene and water which is referred to later. a a

In carrying out the process using this system, the water is forwarded through the separator 13, then through the absorber 13 and back to the separator While the meta: xylene is forwarded through the separator, then through the vaporizer 26 and back to the separator to complete the cycle for each high-boiling component. Bymaintaining the separator 13 at a tempenatureand pressure. higher than those prevailing in the vaporizer-18, the meta-xylene is enriched with ammonia, in the separator at the expense of the water while'in the absorber'the water is enriched with ammonia at the, expense ,of'the 13. t V meta-xylene in the vaporizer, the latter being cooled by the vaporization of ammonia therefrom.

For most etlicient operation of the process, the segregation of the low-boiling component under the conditions prevailing in the separator into the low-boiling solution and its concentration therein should both be as great as possible While the solubility of the low-boiling component in the high-boiling component in the absorber under the conditions prevailing therein and the vapor pressure of the resulting solution should be as low as possible. ployed, the mutual solubility of the components under the conditions prevailing in the separator should be as low as possible but, under the conditions prevailing in the absorber should be as high as possible. The system composed of triethyl amine and water meets these requirements well. When such a system is heated under pressure to about 70 degrees C., low-boiling and highboiling conjugate solutions are formed, the former containing 96 percent triethyl amine and the latter containing 1.6 percent triethyl amine, the balance in each solution being water. With an absorber temperature of about 18 degrees C., the lower consolute temperature of the system, or lower, the water and triethyl amine are miscible in all proportions.

In the case of a system of more than two components wherein the first of the high-boiling components is circulated through the absorber and the separator and the second is circulated through the vaporizer and separator, best operation of the process is obtained when the components are chosen and the apparatus operated so that the second high boiling component is enriched with the low-boiling component as much as possible in the separator at the expense of the first high-boiling component and the latter is enriched with the low-boiling component as much as possible in the absorber at the expense of second high-boiling component in the vaporizer. These conditions are well realized using a system composed of water, ammonia and meta-xylene with a separator temperature of about 80 degrees to 150 degrees C. and an absorber temperature of about 15 degrees to 30 degrees C. Under such conditions the meta-xylene is enriched strongly in the separator at the expense of the water and the water is enriched strongly in the absorber at the expense of the meta-xylene in the vaporizer.

Another example of a three-component negative conjugate system which can be used advantageously in the process is that composed of water, sodium hydroxide and ammonia in the ratios of about 15 to 55, v to 60 and 20 to 80 parts by weight, respectively. Using such a system and a separator at'a temperature of about 60 degrees C., or higher, a low-boiling conjugate solution rich in ammonia and a high-boiling solution impoverished with respect to ammonia are obtained. When these solutions are introduced into the vaporizer and absorber, respectively, and the latter cooled, the high-boiling solution therein becomes enriched with ammonia at the expense of the low-boiling solution in the vaporizer.

Systems useful in practicing the process are not limited to twoand three-component systems, but may include systems of four and more components. The system composed of water, sodium hydroxide, and ammonia, in the proportions given in the last paragraph, and metaxylene is but one example of a useful four-component system. This can, with advantage, be converted to a fivecomponent system by the addition of sodium or potassium chloride either in place of or in addition to the sodium hydroxide. It is to be noted that it is usually advisable that a component added to a negative conjugate system to promote further segregation of the low-boiling component in the low-boiling solution be chosen so that it is soluble at the separation temperature in one of the components but of only limited solubility in the other, preferably substantially insoluble therein. Such a relationship usually converts the negative conjugate system to another nega- Thus, when a two-component system is em-'' 14 tive conjugate system wherein a more nearly complete enrichment of the low-boiling solution with the lowboiling component occurs in the separator.

In the case of the system consisting of ammonia and water, substances soluble in water but substantially insoluble in ammonia which can be added include many inorganic compounds, such as the alkali metal hydroxides and halides, compounds which in aqueous solution form complexes or salts with ammonia which'are unstable at higher temperatures'including cupric sulfate, cadmium chloride, zinc nitrate, acetic acid, monoammonium tartra'te and many others. Organic compounds soluble in water which can be added include certain of the monoand poly-hydroxy alcohols, polyglycols and many others. Substances soluble in liquid ammonia at the separation temperature but substantially insoluble in water include many organic compounds, such as certain organic amines, certain halohydrocarbons, aromatic hydrocarbons, and many others. Mixtures of either group or mixtures of members from each group can be added with advantage in many instances.

Of particular interest and advantage is the addition of an aromatic hydrocarbon to a system comprising ammonia and water. The aroma-tic hydrocarbons form positive conjugate systems with ammonia. The system composed of meta-xylene and ammonia has an upper consolute temperature of 15 degrees C. Consequently, metaxylene is miscible in all proportions with ammonia at the separation temperature which is, of course, generally about 15 degrees C. Meta-Xylene is substantially insoluble in water. However, when the conjugate solution from the separator is introduced into the vaporizer and the temperature thereof lowered by vaporization of ammonia to below 15 degrees C., the solution separates in the absorber into two other conjugate solutions, the compositions of which depend upon the degree to which the temperature in the vaporizer falls during normal operation of the cycle. When the temperature falls, for example, to l0 degrees C., the two phases contain approximately 8 percent and 88.5 percent, respectively, of ammonia, the partial vapor pressure of ammonia in the latter phase being considerably higher than its partial pressure would be if the entire contents of the vaporizer were homogeneous. There is thus a greater utilization forcooling of the ammonia introduced into the vaporizer. It is even sometimes desirable to cool the low-boiling solution of ammonia and meta-xylene from the separator in a separate step to about the temperature of the vaporizer and to separate the ammonia-rich and xylene-rich conjugate solutions which form. The ammonia-rich solution is then forwarded to the vaporizer and the xylenerich solution is returned to the separator.

The method of the invention is not limited with respect to the particular negative conjugate system employed. Such systems are generally characterized by the formation at a lower temperature of a compound or molecular association between the components which becomes unstable and reverts to the individual components at a higher temperature. Low-boiling components of such systems useful in the present method include ammonia, the low-boiling aliphatic amines, i.e., aliphatic amines boiling below about degrees C., sulfur dioxide, carbon dioxide, dimethyl ether, and others. Appropriate high-boiling components when using the lowboiling components mentioned may be selected from among Water, monoand poly-hyd-roxy alcohols, polyglycols, certain amines, and others as well as mixtures thereof and certain inorganic salts including those mentioned. The nature of certain substances with respect to the lowand high-boiling components which can be added to such systems with advantage has been discussed previously.

Certain modifications of the invention contemplate systems, and their use, wherein a component of the high-boiling solution reacts chemically with thelow- 15- boiling component to form a definite compound stable at the temperature prevailingin the absorber, but sufficiently unstable at the separation temperature to regenerate the low-boiling component in free form.

, In the case of an ammonia-water system, for instance,

cupric sulfate can be dissolved in the water. The soluble complex tetramminecopper (II) 'sulfate formed by absorption of ammonia in aqueous cupric sulfatein the absorber decomposes when the-mixture; is heated to re.-

is again released at elevated temperatures and which thus can, under proper conditions, be included advantageously in a lower conjugate system for use in the present refrigeration cycle include ammonium acid tartrate, ammonium molybdate, ammonium ferricyanide, diammonium citrate, ammonium dichromate, acetic acid and others. Often mixtures of such substances can be included to advantage.

Referring again to the ammonia-Water system, it is often advantageous to include a component which is miscible with liquid ammonia but not with water at the separation temperature. Such substances include dialkyl ethers, such as diethyl ether, dimethyl ether, methyl propyl ether, the low molecular weight alkyl amines, such as mono-, diand trimethyl and ethyl amines, hexyl amine and the like, amides, such 'as'acetamides and benzamide and heterocyclic nitrogen compounds,

such as pyridine, quinoline and pyrrole. The inclusion in the system of certain aromatic hydrocarbons, such as benzene, toluene, xylene, cumene, ethyl benzene, p-.

cymene and others, and the advantages accruing thereto, have been discussed previously. i

- It is generally ,true that inclusion in the system of a third component, in addition to the high-boiling and low-- component or leads to a particular degree of separation at a lower temperature than would be the case without the inclusion of the third component.

a 7 Two-component systems whichare homogeneous over a particular range of temperatures are often converted, by the addition 'of V a third icomponent which is'more soluble in'one comture range and which when heated to a temperature higher than the lower consolute' temperature, but still within the particular temperature range, separates into conjugate solutions.

The following cyclic operation using a negative conjugate system consisting of substantially equal partsby weight of triethyl amine and water illustratesQbut does not limit, the method of the invention. The mixture is heated in a closed container to a temperature of about 70 degrees C., at which temperature it has a vapor pressure of about 450 millimeters of mercury, and the liquid layers which form are separated from one another without cooling and-without substantial vaporization thereof. One of the layers contains about 1.6 percent of triethyl amineand the other containsabout 96 percent of'triethyl amine, the balance in each case being water.. The layers have specific gravities of approximately 0.98 and 0.71, respectively. The layer containing 1.6 of triethyl amine is introduced into an absorber and cooled with cooling water at about 15 degrees C., at which'temperature it has a vapor pressure of about 21 millimeters of mercury, and the layer containing about 96' percent of triethyl amine is introduced'into a vaporizer having a vapor conduit connecting it with the absorber. Triethyl amine distills tromthe vaporizerand the temperatu e o I 16 the liquid remaining therein. 7 slightly above, its vapor pressure at 0 degrees C; being substantially equal to the vapor pressure of the .fresh cooled 1.6 percent solution in theabsorberf The triethyl amine vapors are absorbed by the liquid in the absorber are subsequently drawn of and pumped into sorber are subsequentially drawn offiand'pumped-into the heating vessel and heated as first described. s In anotherillustrativecyclic operation of he proce 3 17 parts by weight of a mixture containing 41.2 percent sodium hydroxide, 40.9 percent water, 16.9 percent animonia and a total of 1.0 percent sodium chloride and sodiumchlorate as impurities in the sodium hydroxide is heated ina closed vessel at 60 degree s'C. under a pressure of about 450 lb./sq. in. and the conjugate solutions which form as layers separated at the same temperature and pressure. The conjugate solution rich in ammonia consisting of 60 parts of a solution containing 9.7 percent sodium hydroxide, 37.7 percent water, 47.7 percent ammonia and 4.9 percent combined sodium chloride and sodium chlorate is placed in a vaporizer connected by a vapor conduit with an absorber. The other conjugate solution consisting of 257 parts by weight of a solution containing 48.7 percent sodium hydroxide, 41.6 percent water, 9.7 percent ammonia and traces of sodium chloride and sodium chlorate is placed in the vaporizer and cooled to about 25 degrees C. Ammonia vaporizes in the vaporizer and is absorbed in the solution in the absorber, the fluid remaining in the vaporizer being cooled to a low temperature. The liquids remaining in the vaporizer and. absorber are then removed and placed in the closed vessel and heated to form the originalconjugate solutions.

In yet another illustrative operation of the process about equal parts of 40 percent aqueous ammonia and of meta-xylene are placed in a closed vessel and heated to aboutlOO degrees C. and the conjugate solutions separated at the same temperature. The ammonia-rich metaxylene layer is placed in a vaporizer and the aqeuous layer is placed in an absorber connected with the vaporizer by a. vapor conduit. The solution in the absorber is cooled to about 25 degrees 'C. whereupon the solution in the vaporizer boils vigorously and ammonia distills and is absorbed in the solution in the absorber, the solution remaining in the vaporizer being cooledto a low temperautre, The solutions remaining in the absorber and in the vaporizerare returned to the closed vessel and.

heatedto about 100 degrees C. whereupon the original conjugate solutions are formed. 7 Although the method-of the invention has been descrihedwith particular reference to cooling or refrigeration wherein a desirably low temperature is maintained inthe vaporizer, it is pointed out that the method is also capable, using appropriate systems of substances, of

serving for the productionof useful heatin theabsorber. Thus, byusing appropriatesystems of substances, heat may. be extracted from the atmosphere, from stream or ocean water, or even from soil, by the vaporizer and discharged in the absorber at a temperature sufiiciently high so that water or other fluidcirculated through the cooling coil in the absorber is heated to a temperature at which it can be employed directly as hotrwater or for heatingbuildings or for other useful purposes. It is obvious that the particular degree; of'refrigeration or cooling desired, on the one hand, and the particular degree of heating desired, on the other hand, will govern a -epa1'ation temperature at which the system comprises falls to 0 degrees C. or

a high-boiling conjugate solution impoverished with respect to the low-boiling component and a low-boiling conjugate solution enriched with respect to the low-boiling component; separating the conjugate solutions from one another at the separation temperature and pressure; decreasing the pressure on the separated conjugate solutions to a pressure below the separation pressure; cooling the impoverished high-boiling conjugate solution in vapor contact with the enriched low-boiling conjugate solution to cause vaporization of the low-boiling component from the low-boiling conjugate solution and leave a low-boiling solution impoverished with respect to the low-boiling component and at a temperature below the temperature of the high-boiling conjugate solution and to cause enrichment of the high-boiling conjugate solution with respect to the low-boiling component by absorption of the vapor of the latter therein; increasing the pressure on the enriched high-boiling solution and on the impoverished low-boiling solution and combining them to form the original negative conjugate system; and exchanging heat between the separated low-boiling conjugate solution prior to decreasing the pressure thereon and the impoverished low-boiling solution subsequent to increasing the pressure thereon and prior to combining it with the enriched high-boiling solution.

2. The method which includes: heating a negative conjugate system comprising a high-boiling component and a low-boiling component under a separation pressure greater than the total vapor pressure of the heated system to a separation temperature at which the system comprises a high-boiling conjugate solution impoverished with respect to the low-boiling component and a lowboiling conjugate solution enriched with respect to the low-boiling component; separating the conjugate solutions from one another at the separation temperature and pressure; decreasing the pressure on the separated conjugate solutions to a pressure below the separation pressure; cooling the impoverished high-boiling conjugate solution in vapor contact with the enriched low-boiling conjugate solution tocause vaporization of the low-boiling component from the low-boiling conjugate solution and leave a low-boiling solution impoverished with respect to (below-boiling component and at a temperature below the temperature of the high-boi1ing conjugate solution and to cause enrichmentof the high-boiling conjugate solution with respect 'to the low-boiling component by absorption of the vapor of the latter therein; increasing the pressure on the enriched high-boiling solution and on the impoverished low-boiling solution and combining them to form thetoriginal negative conjugate system; and exchanging heat between the separated highboiling conjugate solution prior to decreasing the pressure thereon and the enriched high-boiling solution subsequent to increasing the pressure thereon and prior to combining it with the impoverished low-boiling solution.

3. The method which includes: heating a negative conjugate system comprising a high-boiling component and a low-boiling component under a separation pressure greater than the total vapor pressure of the heated system to a separation temperature at which the system comprises a high-boiling conjugate solution impoverishedwith respect to the low-boiling component and a lowboiling conjugate solution enriched with respect to the low-boiling component; separating the conjugate solutions from one another at the separation temperature and pressure; decreasing the pressure on the separated conjugate solutions to a pressure below the separation pressure; cooling the impoverished high-boiling conjugate solution in vapor contact with the enriched low-boiling conjugate solution to cause vaporization of the low-boiling component from the low-boiling conjugate solution and leave a low-boiling solution impoverished with re- "spect to the low-boiling component and at a temperature jugate solution with respect to the low-boiling component by absorption of the vapor of the latter therein; increasing the pressure on the enriched high-boiling solution and on the impoverished low-boiling solution and combining them to form the original negative conjugate system; and exchanging heat between the separated enriched low-boiling conjugate solution prior to decreasing the pressure thereon first with the enriched high-boiling solution subsequent to increasing the pressure thereon and then with the impoverished low-boiling solution subsequent to increasing the pressure thereon.

4. The method which includes: heating a negative conjugate system comprising a high-boiling component and a low-boiling component under a separation pressure greater than the total vapor pressure of the heated system to a separation temperature at which the system 'comprises a high-boiling conjugate solution impoverished with respect to the low-boiling component and a low-boiling conjugate solution enriched with respect to the low-boiling component; separating the conjugate solutions from one another at the separation temperature and pressure; decreasing the pressure on the separated conjugate solutions to apressure below the separation pressure; cooling the impoverished high-boiling conjugate solution in vapor contact with the'enriched low-boiling conjugate solution to cause vaporization of the low-boiling component from the low-boiling conjugate solution and leave a low-boiling solution impoverished with respect to the low-boiling component and at a temperature below the temperature of the high-boiling conjugate solution and to cause enrichment of the high-boiling conjugate solution with respect to the low-boiling component by absorption of the vapor of the latter therein; increasing the pressure on the enriched high-boiling solution and on the impoverished low-boiling solution and combining them to form the original negative conjugate system;

exchanging heat between the separated, enriched low-boil- 7 ing conjugate solution prior to decreasing the pressure thereon first with the enriched high-boiling solution .subsequent to increasing the pressure thereon and then with the impoverished low-boiling solution subsequent to increasing-the pressure thereon; and exchanging heat between the impoverished high-boiling conjugate solution and the enriched high-boiling solution subsequent to the exchange of heat between the latter and the enriched lowboiling solution.

5. The 'method which includes: heating a negative conjugate system comprising a high-boiling component selected from the group consisting of water and the monoand poly-hydroxy alcohols, a low-boiling component selected from the group consisting of ammonia, the aliphatic amines boiling below about degrees C., sulfur dioxide, carbon dioxide and dimethyl ether, and a substance other than the lowboiling component soluble in the high-boiling component but of limited solubility in the low-boiling component under a pressure greater than the vapor pressure of the heated system to form a high-boiling conjugate solution and a low-boiling conjugate solution therein, the low-boiling solution being rich in the low-boiling component; separating the conjugate solutions from one another without substantialcooling or vaporization thereof; and cooling the highboiling solution in vapor contact with the low-boiling solution to cause vaporization of the low-boiling component therefrom and cooling thereof to a temperature below that of the high-boiling solution 6. The method which includes: heating a negative conjugate system comprising water as a high-boiling component, ammonia asa low-boiling component and a compound selected from the group consisting of the alkali metal hydroxides and chlorides under a pressure greater thanthe total vapor pressure of the heated system to form a high-boiling conjugate solution and a low-boiling conjugate solution therein, the low-boiling conjugate solution being rich in ammonia; separating theconjugate solutionsfrom one another without substantial'cooling or'vaporizationthereof; and cooling the high-boiling conjugate solution in vapor contact with'the low-boiling conjugate solution to cause vaporization of ammonia rom'the low-boiling conjugate solution'and cooling of the low-boiling'solution to a temperature below that of the high-boiling solution.'

7. The method which includes: heating a negative coujug'ate system comprising water as a'high boiling component, ammonia as a low-boiling component and sodium hydroxide under a pressure greater than the total vapor pressure of the heated system to form-a high-boiling conjugate solution and a' low-boiling conjugate solution therein, the'low-boilingi conjugate solution being rich in ammonia; separating the conjugate solutions from one another without substantial cooling or vaporization thereof; and cooling the high-boiling conjugate solution in vapor contact with the low-boiling conjugate solution to cause'vaporization of ammonia from the low-boiling conjugate solution and cooling of the low-boiling solution to a temperature below that of the high-boiling solution.

, 8; The method which includes: heating a neagtive conjugate system comprising from about '15 to about 55 parts by weight of Water as a high-boiling component, from about 20 to about 80 parts of ammonia as a lowboiling component and from about to about 60 parts of sodium'hydroxide under a pressure greater than the total vapor pressure of the heated system to form a high-boiling conjugate solution and a low-boiling conjugate solution therein, the low-boiling conjugate solution being rich in ammonia; separating the conjugate solutions from one another without substantial cooling or vaporization thereof; and cooling the high-boiling conju Igate solution in vapor contact with the low-boiling con-' ju'gate solution to cause vaporization of ammonia from the low-boiling conjugate solutionland cooling of the lowboiling solution to a temperatureb'e'lowthat of the highboiling solution: I i r v F .19. fThemethod'which includes: gheating a negative con- .jugate system comprising water" asahigh boiling component, ammonia as'a low-boiling c'omponent and sodium chloride under a pressure greater thanthe totalvapor pressure of the heated system to form a high-boiling conjugate solution and a low-boiling conjugate solution therei in, thelow-boiling conjugate solution being rich in ammonia; separating the conjugate solutions from one anotherwithout substantial cooling o r'vaporization thereof; and cooling the high-boiling conjugate solution in vapor contact with the low-boiling conjugate solution to cause vaporization of ammonia from the low-boiling conjugate solution and cooling of the. low-boiling solution to a temperature below that of the high b'oiling'so1ution;

' 10;eThe method which includesz heating a negative conjugate system comprising a high-boiling; component selected from the group consisting of water, the monoand ,poly-hydroxy alcohols and the polyglycols, a' lowboiling component selected from the group consisting of ammonia, the low-boiling aliphatic amines, sulfur dioxide, carbon, dioxide and dimethyl ether and a substance other than the high-boiling component soluble in the low-boiling component but of limited solubility in the high-boiling component under a'pressure greaterthan the vapor pressures of the heated system to form ahighboiling conjugate solution and alow-boiling conjugate solution therein, the low-boiling solution being rich in the low-boiling component; separating the conjugate so- 'lutions from one another-without substantial cooling or vaporization thereof; and cooling the high-boiling solution in vapor contact with the low-boiling solution to cause vaporization of the low-boiling component therefrom and cooling thereof to a temperature below that of the high-boiling solution. I g

11. The method of claim 10 wherein the high-boiling component is water, the low-boiling component is am- 1 monia'and the substance solu'ble'in the low-boiling cbmponent is an organic 'compound non-reactive with water andammonia. "f l V 3 7 12. The method of claim 10 wherein'the high-boiling component is water, the low-boilingcomponent is ammonia and the substance soluble in the low-boiling component is a liquid aromatic hydrocarbonl f'l3.fThe method of of claim 10 wherein the high-boiling component is water, the low-boiling component is ammonia and the substancesoluble in the low-boiling component is meta-xylene.

14. The method of claim 10 wherein the high-boiling component is water, the low-boiling component is ammonia and the substance soluble in the low-boiling component is meta-xylene, the ammonia and meta-Xylene being in a ratio forming a pair of conjugate solutions at a temperature below about 15 degrees C.

15. The method which includes: heating a negative conjugate system comprising a high-boiling'component selected from the group consisting of water, the monoand poly-hydroxy alcohols and the polyglycols, a lowboiling component selected from the group consisting of ammonia, the low-boiling aliphatic amines, sulfur dioxide, carbon dioxide and dimethyl ether, a substance other than the low-boiling component soluble in the high-boiling component but of limited solubility in the low-boiling component and a substance other than the high-boiling component soluble in the low-boiling component but of limited solubility in the'high-boiling component under a pressure greater than the vapor pressure of the heated system to form a high-boiling conjugate solution and a low-boiling conjugate solution therein, the low-boiling solution being rich in the low-boiling component; sepaing component is ammonia and the substance soluble in the low-boiling component is an aromatic hydrocarbon. 1 17. The method of claim, 15 wherein the. high-boiling component is water, the substance soluble in the high-boil- ,ing component sodium hydroxide, the low-boiling component is ammonia and the substance soluble in the low-boiling component is meta xylene.

i 18.7 The method of claim i15iwherein the high-boiling component is water, the substance soluble in the highboiling component is sodium hydroxide, the'low-boiling component is ammonia and the substance soluble in the low-boiling component is.met-a-xylene,'the water, sodium hydroxide and ammonia being in the ratios of 15 to 55, 5 to 60 and '20 to parts by weight, respectively.

19. The method of claim '15 wherein the high-boiling component is water, the substance soluble in the highboiling component is sodium hydroxide, the low-boiling component is ammonia and the substance soluble in the low-boiling component is meta-xylenmthe water, sodium hydroxide and ammonia being in the ratios of 15 to 55, S te 6 0;and' 20 to 80' parts by weight, respectively, and the ammonia and meta-xylene being in a ratio forming conjugate solutions at a temperature belowabout 15 degrees G. r 7 a V 7 20. A liquid, multiphase composition of matter comprising ammonia, water and meta-xylene, the amounts of ammonia and of meta-xylene in the composition being in a ratio which, in a two-component system consisting only of ammonia and meta-xylene in the same ratio, causes conjugate solutions to form at a temperature below an upper consulate temperature of the two-component system. V 21.- A liquid, multiphase composition or matter com- 21 prising ammonia, Water and cumene, the amounts of ammonia and of cumene in the composition being in a ratio which, in a two-component system consisting only of ammonia and cumene in the same ratio, causes conjugate solutions to form at a temperature below an upper consulate temperature of the two-component system.

22. A liquid, multiphase composition of matter com prising ammonia, water and toluene, the amounts of ammonia and of toluene in the composition being in a ratio which, in a two-component system consisting only of ammonia and toluene in the same ratio, causes conjugate solutions to form at a temperature below an upper consulate temperature of the two-component system.

23. A liquid, multiphase composition of matter corn prising ammonia, water, a liquid aromatic hydrocarbon and a substance soluble in water but sparingly soluble in ammonia and the aromatic hydrocarbon.

24. A composition as claimed in claim 23 wherein the substance soluble in water is selected from the group consisting of the alkali metal hydroxides and chlorides, the ammonia and aromatic hydrocarbon being present in a ratio forming conjugate solutions at a temperature below the upper consolute temperature of the system consisting of ammonia and the aromatic hydrocarbon.

25. A liquid, multiphase composition of matter comprising water, sodium hydroxide, ammonia and meta-xylene, the water, sodium hydroxide and ammonia being in the ratio of 15 to 55, to 60 and 20 to 80 parts by weight, respectively, and the ammonia and meta-xylene being in a ratio forming conjugate solutions at a temperature below about 15 degrees C.

26. In apparatus for efiecting transfer of heat from a region of lower temperature to a region of higher temperature using conjugate solutions, the combination including: a separator for separating a high-boiling and a low-boiling conjugate solution from one another at a separating temperature and under a separating pressure greater than the total vapor pressure of the solutions at the separating temperature; a vaporizer; means to convey a low-boiling conjugate solution from the separator into the vaporizer and to reduce the pressure thereon; an absor er; means to convey a high-boiling conjugate solution from the separator into the absorber and to reduce the pressure thereon, the vaporizer and absorber communicating with one another by Way of a vapor conduit; means to cool the absorber to cause vaporization of a lowboiling component from a low-boiling solution in the vaporizer and absorption of the vapor in a high-boiling solution in the absorber thereby to cool the vaporizer and impoverish the low-boiling solution and to enrich the high-boiling solution with respect to the low-boiling component; a first pump means to convey an impoverished low-boiling solution from the vaporizer under the separating pressure into the separator; a second pump means to convey an enriched high-boiling solution from the absorber under the separating pressure into the separator; means to heat the solutions prior to the separation step; and a heat interchanger adapted to exchange heat between a low-boiling conjugate solution being conveyed from the separator at the separation pressure and an impoverished low-boiling solution being conveyed from the vaporizer at the separation pressure.

27. In apparatus for effecting transfer of heat from a region of lower temperature to a region of higher temperature using conjugate solutions, the combination including: a separator for separating a high-boiling and a low-boiling conjugate solution from one another at a separating temperature and under a separating pressure greater than the total vapor pressure of the solutions at the separating temperature; a vaporizer; means to convey a low-boiling conjugate solution from the separator into the vaporizer and to reduce the pressure thereon; an absorber; means to convey a high-boiling conjugate solution from the separator into the absorber and to reduce the pressure thereon, the vaporizer and absorber communicating with one another by Way of a vapor conduit; means to cool the absorber to cause vaporization of a low-boiling component from a low boiling solution in the vaporizer and absorption of the vapor in a high-boiling solution in the absorber thereby to cool the vaporizer and impoverish the low boiling solution and to enrich the high-boiling solution with respect to the low-boiling components; a first pump means to convey an impoverished low-boiling solution from the vaporizer under the separating pressure into the separator; a second pump means to convey an enriched high-boiling solution from the absorber under the separating pressure into the separator; means to heat the solutions prior to the separation step; and a heat interchauger adapted to exchange heat between a high-boiling conjugate solution being conveyed from the separator under the separation pressure and an enriched high-boiling solution being conveyed from the absorber under the separation pressure.

28. In apparatus for effecting transfer of heat from a region of lower temperature to a region of higher temperature using conjugate solutions, the combination including: a separator for separating a high-boiling and a low-boiling conjugate solution from one another at a separating temperature and under a separating pressure greater than the total vapor pressure of the solutions at the separating temperature; a vaporizer; means to convey a low-boiling conjugate solution from the separator into the vaporizer and to reduce the pressure thereon; an absorber; means to convey a high-boiling conjugate solution from the separator into the absorber and to reduce the pressure thereon, the vaporizer and absorber communicating with one another by way of a vapor conduit; means to cool the absorber to cause vaporization of a low-boiling component from a low-boiling solution in the vaporizer and absorption of the vapor in a high-boiling solution in the absorber thereby to cool the vaporizer and impoverish the low-boiling solution and toenrich the high-boiling solution with respect to the low-boiling component; a first pump means to convey an impoverished low-boiling solution from the vaporizer under the separating pressure into the separator; a second pump means to convey an enriched high-boiling solution from the absorber under the separating pressure into the separator; means to heat the solutions prior to the separation step; and heat interchangers adapted to exchange heat between a low-boiling conjugate solution being conveyed from the absorber under the separation pressure and, first, an enriched high-boiling solution being conveyed from the basorber under the separation pressureand, second, an impoverished low-boiling solution being conveyed from the vaporizer under the separation pressure.

29. :In apparatus for efiecting transfer of heat from a region of lower temperature to a region of higher temperature using conjugate solutions, the combination including: a separator for separating a high-boiling and a low-boiling conjugate solution from one another at a separating temperature and under a separating pressure greater than the total vapor pressure of the solutions at the separating temperature; a vaporizer; means to convey a low-boiling conjugate solution from the separator into the vaporizer and to reduce the pressure thereon; an absorber; means to convey a high-boiling conjugate soultion from the separator into the absorber and to reduce the pressure thereon, the vaporizer and absorber communicating with one another by way of a vapor conduit; means to cool the absorber to cause vaporization of a low-boiling component from a low-boiling solution in the vaporizer and absorption of the vapor in a high-boiling solution in the absorber thereby to cool the vaporizer and impoverish the low-boiling solution and to enrich the high-boiling solution with respect to the low-boiling component; a first pump means to convey an impoverished low-boiling solution from the vaporizer under the separating pressure into the separator; a sec- '23 ond pump means to convey an enriched high-boiling solution from the absorber under the separating pressure into the separator; means to heat the solutions prior to the separation step; a heat interchanger adapted to'exchange heat between a low-boiling conjugate solution being conveyed from the separator under the separation pressure and first, an enriched high-boiling solution being conveyed from the absorber under the separation pressure and, second, an impoverished low-boiling solution being conveyed from the vaporizer under the separation pressure; and a heat interchanger adapted to exchange heat etween ahigh-boiling conjugate solution being conveyed' from the separator under the separation pressure and an enriched high-boiling solution being conveyed from the absorber under'the separation pressure subsequent to v 24 Snyder Oct. 26, Lenning May 6, Enstein Nov. 11, Chadwick I Aug; 16,' Taylor June 13, Plat en June 27, Samiran Apr. 26, Smith "Dec. 26, Kuenzli July 8, Sarniran Feb. 23, Willauer Dec. 7, Sherwood Aug. 1, Wagner Feb. 5, Katzow 'Feb; 14, Mills May 19,

FOREIGN PATENTS Denmark Nov. 25, Great Britain Oct. 2,

UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,963,875 December 13, I960 Lindley E, Mills It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 22, line 7, for "components" read component line 47, for "absorber" read separator same column 22, line 49 for "basorber" reed absorber Signed and sealed this 6th day of June 1961.

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer DAVID L. moo

Commissioner of Patents

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