HK1005629B

HK1005629B - Solid-vapor adsorption apparatus and process with vapor recuperator

Info

Publication number: HK1005629B
Application number: HK98104656.0A
Authority: HK
Inventors: Rockenfeller Uwe; D. Kirol Lance
Original assignee: Rocky Research
Priority date: 1991-12-20
Filing date: 1992-11-24
Publication date: 1999-01-15

Description

BACKGROUND OF THE INVENTION

The use of compounds comprising solid-vapor compositions formed by adsorption, sometimes referred to as absorption, of gas molecules on a solid adsorbent as heat pump working materials is known in the art. Heat pump systems using such materials have a number of advantages over other heat pumps for residential and commercial space conditioning, industrial heat pumping and refrigeration. Such advantages include higher temperature lift created by the solid-vapor media as compared to other sorption media thus eliminating the need for cooling towers or lift staging. Moreover, the apparatus used for the solid-vapor compound heat pumps require few, if any, moving parts, resulting in simple and reliable hardware. Additionally, such systems do not use the objectionable CFC's.

The solid-vapor compounds suitable for heat pumps include complex compounds which are materials which adsorb molecules of gas to form coordinative bonds in which the gaseous reactant coordinates via electron displacement with the solid adsorbent, commonly a solid metal inorganic salt. The adsorption/desorption process releases significant heat during adsorption and adsorbs energy during the desorption phase. Unlike most other sorption processes, the entire adsorption or desorption reactions may occur at constant temperature, thus eliminating problems with hot and cold sorber end. Useful gaseous reactants include water, ammonia, methanol and the like. A number of such materials are described in U.S. patents 4,822,391 and 4,848,994.

Heat activated heat pumps consist of a heat engine subsystem which generates high pressure refrigerant vapor, essentially a thermal compressor, and a heat pump subsystem which uses high pressure refrigerant to produce cooling or heat pumping. The thermal compressor, heat pump, and their combination in a heat activated heat pump comprise useful thermodynamic systems which make advantageous use of solid-gas reactions. In U.S. Patents No. 5 027 607 and 5,079,928 (published after the priority date of the present application) there are described apparatus and methods using constant pressure staging techniques resulting in improved heat activated heat pump systems. It is an object of the present invention to use such reactions and staging techniques to even greater advantage and efficiency.

SUMMARY OF THE INVENTION

In the present invention as defined in claims 1 and 16, there is provided a vapor recuperator and preferably, a liquid subcooler. The vapor recuperator is used with a system incorporating a refrigerant condenser and evaporator, or absorber/desorber receivers for gaseous reactant directed to and from the reactors. The liquid subcooler is used only in a refrigerant phase change (condenser/evaporator) system. According to a further development multiple-circuits for directing different heat transfer fluids through the reactors are disclosed. Preferred reactant media comprise the use of one or more specific complex compounds in different reactors. These preferred complex compounds are disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

Figs. 1 and 2 are schematic illustrations of an apparatus of the invention incorporating a vapor recuperator; Fig. 3 is a schematic illustration of an apparatus (not claimed) incorporating a liquid subcooler; and
Fig. 4 is a schematic illustration of the same apparatus of the invention incorporating both a vapor recuperator and subcooler.

DETAILED DESCRIPTION

As used herein, the term "compound" is intended to mean any reaction product formed by adsorption and desorption of a gaseous reactant, i.e. refrigerant, on a solid reactant within the scope of the invention. In practicing the discrete staging of a constant pressure engine cycle according to the invention, a plurality of two or more different solid reactants are selected, and a different solid reactant is introduced into a different reactor or reaction site in the heat pump apparatus. The different compounds of a set, series or group of compounds used in the process are selected and arranged in ascending order of gaseous reactant vapor pressure such that the temperature of adsorption of the lower vapor pressure compound at low reaction pressure (adsorption), is at least 8°C higher than the desorption temperature of the next higher vapor pressure compound at high reaction (desorption) pressure. Each of the compounds of such sets or groups each also exhibit different vapor pressure curves, i.e., each has a different vapor pressure-temperature relationship, and which is independent of the concentration of the gaseous reactant. By selecting appropriate compounds and arranging them in the aforesaid sequence, the process cycle will be carried out so that the heat of adsorption is always at an adequate temperature to drive the next or subsequent desorption reaction in the cycle. The compounds of the series are also selected so that none of the compounds in the same reactor have an additional coordination step at lower equilibrium temperature which may adsorb more reactant gas from the other compounds during temperature equilibrium or shut-down condition which would reduce cycle performance during intermittent operation. Moreover, masses of each compound are adjusted so that an approximately equal amount of heat is required to desorb each compound.

Specific reactants used to form compounds useful in the invention include metal oxides, halides, borofluorides, carbonates, nitrites, nitrates, oxalates, sulfides, sulfates and chlorates. Preferred metals for the inorganic salts are selected from alkali and alkaline earth metals, transition metals, aluminum, zinc, cadmium and tin. Preferred transition metals are manganese, iron, nickel, and cobalt. Double metal chloride salts of the aforesaid metals, particularly alkali, alkaline earth, aluminum and the preferred transition metals, are also useful. Hereinafter these reactants will be sometimes referred to as solids, salts or solid reactants. Calcium and strontium halides are especially preferred.

Gaseous reactants which are adsorbed on the solids to form compounds which are especially useful in the processes of the invention are ammonia, water, methylamine and methanol, ammonia being especially suitable because it is stable, and forms high energy complexes. However, sulfur dioxide, other lower alkanols, pyridine, alkylamines, polyamines and phosphine as well as any other polar refrigerant having at least one free electron pair may also be used. Carbon dioxide is also useful with metal oxides. These gaseous reactants are also referred to hereinafter as refrigerants. Particularly preferred ammoniated complex compounds are: BaCl_{2 •} 0-8 (NH₃), CaCl₂ • 4-8 (NH₃), CaCl₂ • 2-4 (NH₃), SrCl₂ • 1-8 (NH₃), LiCl • 0-3 (NH₃), SrBr₂ • 2-8 (NH₃),CaBr₂ • 2-6 (NH₃), CoCl₂ • 2-6 (NH₃), NiCl₂ • 2-6 (NH₃), FeCl₂ • 2-6 (NH₃), FeBr₂ • 2-6 (NH₃), , CoBr₂ • 2-6 (NH₃), NiBr₂ • 2-6 (NH₃), AlCl₃ • 3.5 (NH₃), CaCl₂ • 0-1(NH₃), CaCl₂ • 1-2 (NH₃), CuSO₄ • 2-4(NH₃), NaBF₄ • 0.5-2.5 (NH₃) and NaBr • 0-5.25 (NH₃).

Although in the aforesaid complex compounds, numerical value of moles of ammonia per mole of salt is given, in some complexes, the mole range given comprises several coordination steps. Thus, for example, in the case of NaBF₄ compounds, a number of different reaction steps occur between the numerical limits given. Typically however, practical considerations only allow for use of a portion of the designed coordination range. Accordingly, the aforesaid ranges are intended to be approximate as will be understood by those skilled in the art.

In a specific example of a set or series of compounds, to illustrate a system according to the invention, salts FeCl₂, SrBr₂, SrCl₂ and BaCl₂ are used in a heat pump consisting of four separate reaction vessels or separate heat-transfer regions in one or more reactors. The compounds comprise the ammonia ligand complex compound of the aforesaid salts as set forth hereinabove. Fig. 1 illustrates schematically an example of an apparatus embodiment for carrying out the discrete constant pressure staged heat pump. The salts are charged to reactors 12, 14, 16 and 18, respectively, in successive ascending order of the complex compound ligand vapor pressure. Thus, first reactor 12 is charged with FeCl₂, reactor 14 with SrBr₂, reactor 16 with SrCl₂, and reactor 18 with BaCl₂. The apparatus includes a burner 20, heat exchanger 22, evaporator 24 and condenser 26 together with appropriate valves and conduits for directing ammonia gas from and to the reactors and the condenser and evaporator, and valves 52, 54 and 56 for directing heat transfer fluid between the reactors as well as pumps and heat exchange conduits for pumping heat transfer fluid within the system. In the first half-cycle, reactor 12 containing the high temperature salt FeCl₂ is at high pressure and reactor 16 containing SrCl₂ is also at high pressure. Reactors 14 and 18 are at low pressure, reactor 18 containing BaCl₂ and reactor 14 containing SrCl_2.

During the first-half cycle, valves 52 and 56 are positioned so that pump 19 circulates heat transfer fluid through reactors 14 and 16, thereby transferring energy released during gas adsorption from reactor 14 to the solid reactant in reactor 16 to drive the desorption reaction occurring there. With the valve settings and proper positioning of valve 15, energy released during the adsorption in reactor 18 is rejected or recovered via heat exchanger 22. In this first half of the heat exchange cycle, valve 25 is also positioned for directing ammonia vapor from reactors 12 and 16 to condenser 26 and from evaporator 24 to reactors 14 and 18. Pump 17 circulates heat transfer fluid from burner 20 to reactor 12 to drive the desorption of the compound in that reactor.

Before start of the second half-cycle of the process, a short phase of heat recuperation and temperature shifting is required. The valve positions are changed so that reactors 12 and 14 are coupled, and reactors 16 and 18 are coupled, respectively, for heat transfer communication. Heat transfer fluid is pumped through each pair of coupled reactors to transfer heat from the hotter to the colder reactor. Thus, reactor 12 is cooled while reactor 14 is heated; reactor 16 is cooled while reactor 18 is heated. This terminates the recuperative and temperature adjustment phase in preparation for the second half-cycle.

In the second half-cycle burner 20 is not used. Solid reactant in reactor 14 desorbs its refrigerant, driven by heat from the adsorption reaction in reactor 12. The compound in reactor 18 desorbs, driven by heat released from adsorption of the compound in reactor 16. Ammonia from the desorption reactions is directed to the condenser 26, and ammonia for the adsorption reactions is obtained from evaporator 24. At the conclusion of the second half-cycle, another phase of recuperation and temperature adjustment as previously described readies the system for repeating the first half-cycle. The apparatus of Fig. 1 could also be modified with reactors 12 and 16 combined and reactors 14 and 18 combined in single vessels, respectively, since both reactors in either pair are always at the same pressure. All four compounds may be located in a single reactor, with the heat pump consisting of two such reactors, each operating at alternately high and low pressure.

In selecting the preferred compounds according to the invention, preferred highest vapor pressure compounds, for use in one or more higher vapor pressure stages are CaCl₂ • 4-8 (NH₃), CaCl₂ • 2-4 (NH₃), and mixtures thereof, SrCl₂ • 1-8 (NH₃), BaCl₂ • 0-8 (NH₃), LiCl • 0-3 (NH₃), SrBr₂ • 2-8 (NH₃), CaBr₂ • 2-6, FeCl₂ • 2-6 (NH₃), CoCl₂ • 2-6 (NH₃), NaBF₄ • 0.5-2.5 (NH₃) and NaBr • 0-5.25 (NH₃). Preferred compounds used in one or more lower vapor pressure stages are SrCl₂ • 1-8 (NH₃), CaCl₂ • 2-4 (NH₃), LiCl • 0-3(NH₃), SrBr₂ • 2-8 (NH₃), CaBr₂ • 2-6 (NH₃), FeCl₂ • 2-6 (NH₃) and CoCl₂ • 2-6 (NH₃), CoBr₂ • 2-6(NH₃), NiCl₂ • 2-6(NH₃), CuSO₄ • 2-4(NH₃), and CaCl₂ • 0-1(NH₃) and CaCl₂ • 1-2(NH₃) used individually or in combination.

A most preferred grouping of compounds uses CaCl₂ • 4-8 (NH₃), CaCl₂ •2-4 (NH₃), or a combination thereof, or SrCl₂ • 1-8 (NH₃), in the low temperature stage, i.e., highest vapor pressure compounds, CaBr₂ •2-6 (NH₃) in an intermediate stage, and CaCl₂ • 0-1 (NH₃), CaCl₂ • 1-2 (NH₃) or mixtures thereof in the high temperature (low pressure) stage.

An important feature and advantage of the invention is in staging the adsorption and desorption reactions such that the heat generated by exothermic adsorption reactions is directed to reactors for driving the endothermic desorption reactions. According to the present invention, the different complex compounds present in the different reactors are used in ascending order of gaseous reactant vapor pressure, such that the adsorption temperature a lower vapor pressure compound at adsorption pressure is at least 8°C higher than the desorption temperature of the next successive higher vapor pressure compound at desorption pressure. Thus, the lines for directing heat transfer fluid between the reactors and in thermal communication with the compounds are such that the fluid is directed successively from the lower vapor pressure compounds to the higher vapor pressure compounds.

The aforesaid specific complex compounds may be used in a heat activated heat pump system incorporating receiving means comprising one or more evaporators and one or more condensers in which the refrigerant goes through a gas/liquid phase change as illustrated in Fig. 1, or used in a system in which the receiving means comprises reactors for adsorbing (absorbing) and desorbing the refrigerant to replace the evaporator and condenser, as disclosed in U.S. Patent No. 5,079,928. Where a single evaporator and single condenser are used, refrigerant is directed to the condenser from all desorbing reactors, and from the evaporator to all adsorbing reactors. Where multiple evaporators or multiple condensers are used, each evaporator will operate at a different temperature, as will each of the condensers. Other receiving means may be used including power generating devices such as a turbine or other expansion means, or a liquid vapor sorption cycle. Additionally, this type of staging system may be used on the heat pump instead of the heat engine side to increase temperature lift for a given pressure ratio, or to decrease pressure ratio for a given lift. When used in this mode, the system may be activated by either a mechanical or thermal compressor. For heat pump staging, as also described in the aforesaid application, the complex compounds are selected and arranged in ascending order of adsorption temperatures at the same adsorption and desorption pressure, respectively, such that the adsorption temperature of the lower adsorption temperature compound at high reaction pressure is at least 8°C higher than the desorption temperature of the next successive higher adsorption temperature compound at low reaction pressure.

VAPOR RECUPERATOR

According to the invention, an increase in the coefficient of performance (COP) and specific refrigeration capacity is provided by a vapor recuperator, comprising a heat exchanger located along the flow paths of the refrigerant to and from the reactors. As illustrated in Fig. 1, the vapor recuperator 40 is placed conveniently along the conduits 38 and 39 between the reactors and the evaporator 24 and condenser 26, respectively. At such a location, the recuperator 40 provides for heat exchange between the refrigerant vapor streams flowing between the reactors and the condenser, and between the evaporator and the reactors. By incorporating such a recuperator, super-heated vapor flowing from the desorption reactors toward the condenser is cooled against the relatively cool vapor directed from the evaporator to the adsorption reactors. Because energy recuperated from the superheated refrigerant leaving the desorption reaction is transferred to the cold gaseous refrigerant typically leaving the evaporator and then undergoing exothermic adsorption, thermal efficiency of the system is increased. A vapor recuperator may also be advantageously installed between reactors (stages) or, alternatively between the highest pressure reactor and the condenser and evaporator. Refrigerant vapor exiting the next hottest reactor is used to heat vapor entering the next coldest vapor reactor. Combinations of various recuperator placements are also often desirable; for example, between the highest pressure reactor and the condenser/evaporator, and/or between the two lower stage reactors.

In the embodiment shown in Fig. 2, reactors 55 and 57 are substituted for the evaporator and condenser components used in the refrigerant phase change apparatus of Fig.1. Such reactors, contain a solid or liquid solutions for alternately adsorbing (absorbing) and desorbing the refrigerant directed thereto from the staging reactors 72, 74 and 76. The reactors 55 and 57 cooperate with heat exchanges (not shown) for recovery of energy from the alternating chemisorption reaction. The vapor recuperator 40 functions the same way in this embodiment as in Fig. 1, to cool super-heated refrigerant vapor directed from a staging desorbing reactor to an adsorbing reactor (55 or 57), against the relatively cool vapor directed fron a desorbing reactor (55 or 57) to a staging adsorbing reactor.

LIQUID SUBCOOLER

In the apparatus shown in Figs. 3 and 4 a liquid subcooler is used in a refrigerant phase change apparatus incorporating an evaporator and condenser. In the (not claimed) embodiment of Fig. 3, a liquid subcooler 42 comprising a liquid-vapor heat exchanger is provided for cooling liquid refrigerant flowing from the condenser to expansion valve 31 via conduit 33 against relatively cold vapor of the exiting the evaporator 24. The liquid subcooler 42 is conveniently located along the conduits 33 between the condenser 26 and evaporator 24 on the condenser side of expansion valve 31, or other gas expansion means, and conduit 38, whereby these fluid streams are in thermal communication to provide for heat transfer therebetween. This heat transfer causes the liquid refrigerant in conduit 33 to become subcooled by the heat exchange against the relatively cold vapor from the evaporator in conduit 38 whereby a smaller fraction of the liquid will flash to vapor in isenthalpic expansion thereby increasing the cooling efficiency and capacity of the system based on the amount of refrigerant fluid directed through the system. A further advantage of the subcooler is increasing the energy provided in the vapor stream from the evaporator to the adsorbing reactor(s) thereby ultimately decreasing the amount of prime energy needed to drive desorption reactions. Accordingly, refrigeration capacity and COP are both increased.

In the embodiment of the invention shown in Fig. 4, an example of an apparatus incorporating both the vapor recuperator 40 and liquid subcooler 42 is illustrated.

Fig. 2 also illustrates an embodiment using multiple-circuits for directing heat transfer fluids to and from the salts in the reactors with the heat transfer fluids passing through the reactors. The use of multiple circuits in the reactors provides for the use of different heat transfer fluids and different phases of those fluids. For example, reactor 72 might be direct fired with flue gas or exhaust from furnace 71 during the desorption phase, and a different fluid or other heat transfer liquid used for rejecting or removing the heat during the adsorption phase. A plurality of different heat transfer fluids may be used in different circuits to maintain high heat transfer coefficients over the temperature of the heat exchange required in the staging of the reactors and compounds. The use of specific and different heat transfer fluids may be tailored to the system, depending on a different combination of salts and the temperature ranges achieved in the reaction phases. The heat transfer fluids may be chosen to take optimum advantage of their respective heat transfer properties when used in such systems. By way of further example, in a three salt system illustrated, the high temperature salt in reactor 72 could be desorbed by being direct fired or heated with a hot fluid from furnace 71, a phase change heat transfer medium such as Dowtherm J® used to transfer heat from the high temperature reactor 72 to the intermediate temperature reactor 74, during adsorption of the high temperature salt and desorption of the intermediate temperature compounds. Water could be used to transfer energy from the intermediate to the low stage reactor 76, with phase change or pumped heat transfer both being practical, and phase-change ammonia to transfer heat from the low temperature salt in reactor 76 to heat exchanger 70 (heat rejection). Such use of four incompatible fluids requires dual circuits in each reactor. Such multiple circuits may also be used to take advantage of using high temperature exhaust gases from furnace 71 or from outside waste or reject heat sources by directing such heated fluids through the reactors and a different fluid, for example, water or a heat transfer oil for heat rejection. The staged cycles can use two or three different heat transfer fluids and/or phase change heat transfer fluids to maintain good transport properties over all heat exchange temperatures required for the staging. These as well as other advantages within the scope of the invention will be evident to those skilled in the art.

Claims

An apparatus comprising:
a plurality of two or more reactors (12, 14, 16, 18) each of said reactors having a different compound therein comprising a solid reactant adsorbent and a gaseous reactant adsorbed thereon, each of said compounds having a different gaseous reactant vapour pressure, substantially independent of the concentration of the gaseous reactant therein, wherein said gaseous reactant comprises ammonia, water, carbon dioxide, sulfur dioxide, a lower alkanol, alkylamine, polyamine, phosphine or polar refrigerant having at least one free electron pair, and said solid reactant is an inorganic salt comprising a metal oxide, halide, carbonate, oxalate, nitrate, nitrite, sulfide, or sulfate, wherein said metal comprises an alkali metal, alkaline earth metal, transition metal, aluminum, zinc, cadmium, or tin, or a double metal chloride of an alkali metal, alkaline earth metal, aluminum, manganese, iron, nickel or cobalt;

heating means (20) for introducing heat into at least one of said chambers, means (52, 54, 56, 15) for supplying a heat transfer fluid to and from said reaction chambers, and means for directing the heat transfer fluid through said reaction chambers in thermal communication with said compounds therein whereby heat from an exothermic reaction is directed to a reaction chamber for driving an endothermic reaction;

flow directing means (38, 39) for directing relatively heated gaseous reactant from one or more desorbing reaction chambers to receiving means and for directing relatively cool gaseous reactant from receiving means to one or more adsorbing reaction chambers;

said apparatus characterised by a heat exchanger (40) co-operating with said flow directing means for transferring heat between said heated gaseous reactant and said relatively cool gaseous reactant.
Apparatus according to Claim 1 wherein said receiving means comprises one or more condensers (26) for receiving said relatively heated gaseous reactant and one or more evaporators (24) for supplying relatively cool gaseous reactant.
Apparatus according to Claim 1 wherein said receiving means comprises means (55, 57) for adsorbing and desorbing said gaseous reactant.
Apparatus according to any preceding claim wherein said means for directing heat transfer fluid through said reaction chambers comprises multiple channel means capable of directing different heat transfer fluids therethrough in thermal communication with said compounds during adsorption and desorption reactions in said reaction chambers.
Apparatus according to any preceding claim, wherein at least one of said compounds is: CaCl₂ • 4-8 (NH₃), CaCl₂ • 2-4 (NH₃) or mixtures thereof, SrCl₂ • 1-8 (NH₃), BaCl₂ • 0-8 (NH₃), LiCl • 0-3 (NH₃), SrBr₂ • 2-8 (NH₃), CaBr₂ • 2-6 (NH₃), CoCl₂ • 2-6 (NH₃), CoBr₂ • 2-6 (NH₃), NiCl₂ • 2-6 (NH₃), FeCl₂ • 2-6 (NH₃), CuSO₄ • 2-4 (NH₃), NaBF₄ • 0.5-2.5 (NH₃), NaBr • 0-5.25(NH₃), or CaCl₂ • 0-1 (NH₃), CaCl₂ • 1-2 (NH₃) or mixtures thereof.
Apparatus according to Claim 1, wherein:
said different compounds have an ascending order of gaseous reactant vapour pressure and wherein the adsorption temperature of a lower vapour pressure compound at adsorption pressure is at least 8 deg C higher than the desorption temperature of the next successive higher vapour pressure compound at desorption pressure; and comprising

condenser means (26) comprising a single condenser and conduit means (39) for directing gaseous reactant from each of said reaction chambers to said condenser, or two or more condensers, each operating at a different temperature; and

evaporator means (24) comprising a single evaporator and conduit means for directing gaseous reactant from said evaporator to each of said reaction chambers, or two or more evaporators, each operating at a different temperature;

and wherein the highest vapour pressure compound comprises: CaCl₂ • 4-8 (NH₃), a mixture of CaCl₂ • 4-8 (NH₃) and CaCl₂ • 2-4 (NH₃), BaCl₂ • 0-8 (NH₃), LiCl • 0-3 (NH₃), SrBr₂ • 2-8 (NH₃), CaBr₂ • 2-6 (NH₃), FeCl₂ • 2-6 (NH₃), CoCl₂ • 2-6 (NH₃), and NaBF₄ • 0.5-2.5 (NH₃), or NaBr • 0-5.25 (NH₃).
Apparatus according to Claim 6, wherein one or more lower vapour pressure compounds comprises: SrCl₂ • 1-8 (NH₃), CaCl₂ • 2-4 (NH₃), LiCl • 0-3 (NH₃), SrBr₂ • 2-8 (NH₃), CaBr₂ • 2-6 (NH₃), FeCl₂ • 2-6 (NH₃), NiCl₂ • 2-6 (NH₃), CoCl₂ • 2-6 (NH₃), CoBr₂ • 2-6 (NH₃), CuSO₄ • 2-4 (NH₃), or CaCl₂ • 0-1 (NH₃), CaCl₂ •1-2 (NH₃) or mixtures thereof.
Apparatus according to Claim 6, comprising:
a plurality of three or more reactors each of said reactors having a different one of said compounds therein;

and including means for introducing heat into at least one of said reactors, means for supplying. a heat transfer fluid to and from said reactors, and means for directing the heat transfer fluid through said reactors in thermal communication with said compounds therein, whereby heat from an exothermic reaction is directed to a reactor for driving an endothermic reaction;

means for directing gaseous reactant to and from said reactors;

heat exchange means (22) for heating andlor cooling said heat transfer liquid and for selectively recovering andlor adsorbing heat therefrom; and

wherein the highest vapour pressure compound comprises: CaCl₂ • 4-8 (NH₃), a mixture of CaCl₂ • 4-8 (NH₃) and CaCl₂ • 2-4 (NH₃), BaCl₂ • 0-8 (NH₃) or NaBF₄ • 0.5-2.5 (NH₃).
Apparatus according to Claim 8, wherein an intermediate stage vapour pressure compound is CaBr₂ • 2-6 (NH₃).
Apparatus according to Claim 8 or 9, wherein the third lower vapour pressure compound comprises CaCl₂ • 0-1 (NH₃), CaCl₂ • 1-2 (NH₃) or mixtures thereof.
Apparatus according to Claim 8, 9 or 10, wherein the lowest vapour pressure compound is NiCl₂ • 2-6 (NH₃).
Apparatus according to Claim 8, wherein one or more lower stage vapour pressure compounds comprises: SrCl₂ • 1-8 (NH₃), CaCl₂ • 2-4(NH₃), LiCl • 0-3 (NH₃), SrBr₂ • 2-8 (NH₃), CaBr₂ • 2-6 (NH₃), FeCl₂ • 2-6 (NH₃), CoCl₂ • 2-6 (NH₃), FeBr₂ • 2-6 (NH₃), NiCl₂ •2-6 (NH₃), CoBr₂ • 2-6 (NH₃), CuSO₄ • 2-4 (NH₃), NaBF₄ • 0.5-2.5 (NH₃), NaBr • 0-5.25 (NH₃), or CaCl₂ • 0-1 (NH₃), •CaCl₂ • 1-2 (NH₃) or mixtures thereof.
Apparatus according to Claim 6, comprising:
a plurality of three or more reactors each of said reactors having a different one of said compounds therein and including means for introducing heat into at least one of said reactors, means for supplying a heat transfer fluid to and from said reactors, and means for directing the heat transfer fluid through said reactors in thermal communication with said compounds therein, whereby heat from an exothermic reaction is directed to a reactor for driving an endothermic reaction; means for directing gaseous reactant to and from said reactors;

heat exchange means for heating andlor cooling said heat transfer liquid and for selectively recovering and/or adsorbing heat therefrom; and

wherein said compound in at least one of said reactors comprises a calcium halide or a strontium halide.
Apparatus according to any of Claims 1 to 5, wherein the highest vapour pressure compound comprises CaCl₂ • 4-8 (NH₃), CaCl₂ • 2-4 (NH₃), mixtures thereof, SrCl₂ • 1-8 (NH₃), BaCl₂ • 0-8 (NH₃), LiCl • 0-3 (NH₃), SrBr₂ • 2-8 (NH₃), CaBr₂ 2-6 (NH₃), FeCl₂ • 2-6 (NH₃), CaCl₂ • 2-6 (NH₃), NaBF₄ • 0.5-2.5 (NH₃), or NaBr • 0-5.25 (NH₃).
Apparatus according to Claim 13 or 14, wherein one or more lower vapour pressure compounds comprises SrCl₂ • 1-8 (NH₃), CaCl₂ • 2-4 (NH₃), LiCl • 0-3 (NH3), SrBr₂ • 2-8 (NH₃),CaBr₂ • 2-6 (NH₃), FeCl₂ • 2-6 (NH₃), NiCl₂ • 2-6 (NH₃), CoCl₂ • 2-6 (NH₃), CoBr₂ • 2-6 (NH₃), CuSO₄ • 2-4 (NH₃), or CaCl₂ • 0-1 (NH₃), CaCl₂ • 1-2 (NH₃) or mixtures thereof.
A process for staging solid-vapour compound reactions, comprising:
selecting a plurality of two or more different compounds comprising a solid reactant adsorbent and a gaseous reactant adsorbed thereon, wherein each of said compounds has a different gaseous reactant vapour pressure, substantially independent of the concentration of the gaseous reactant, and locating a different one of said compounds in a different one of a plurality of reactors (12, 14, 16, 18);

in a first reaction cycle, operating a first portion of said reactors at a temperature resulting in a first pressure, whereby said compound therein desorbs said gaseous reactant in an endothermic reaction, and operating said second portion of said reactors at a second pressure whereby said compound therein adsorbs said gaseous reactant in an exothermic reaction;

in a second reaction cycle, operating said first portion of said reactors at said second pressure whereby said compound therein adsorbs said gaseous reactant in an exothermic reaction, and operating said second portion of said reactors at a temperature resulting in said first pressure whereby said compound therein desorbs said gaseous reactant in an endothermic reaction;

directing at least a portion of the heat from an exothermic reaction to a reactor for driving an endothermic reaction;

directing a first flow of gaseous reactant released from said desorbing reactors to a condenser or to receiving means for said gaseous reactant, and directing a second flow of gaseous reactant from an evaporator or from receiving means to adsorbing reactors;

the process characterised by directing said first flow of said gaseous reactant from the desorbing reactor to the condenser (26) or receiving means (55, 57) and concurrently directing said second flow of gaseous reactant from the evaporator (24) or receiving means to the adsorbing reactor through a heat exchanger (40) and exchanging heat between said first and second flow.