Description

Field of the Invention

The present invention relates to heat transfer apparatus and methods, especially those employing an absorption cycle using three heat transfer fluids, as well as industrial processes using such apparatus and methods.

Background to the Invention

In many power generating and other industrial processes, low grade heat must be rejected during the operation of thermal processes. An example is thermal power stations operating on the modified Rankine thermal cycle. Not all the heat added to a working fluid may be extracted into mechanical work and onto electrical energy. Some heat must be rejected. Although this "waste" heat may not be efficiently used in the actual power generating cycle, it has the potential to be used for other applications, such as preheating the feed water prior to entry into a boiler of the thermal cycle, carbon capture apparatus, steam reheating, moisture removal from fuels such as lignite and biomass, etc.

Furthermore, other industrial process such as petroleum and petrochemical refinement require a great deal of cooling water to function, and such cooling water will possess significant amounts of such low grade heat after use that could be usefully recovered rather than simply being rejected to the environment.

Summary of the Invention According to a first aspect of the present invention there is provided heat transfer apparatus utilising a three fluid absorption cycle comprising an evaporator for evaporating a first working fluid in the presence of a second working fluid thereby absorbing heat from a first heat source, a first fluid pipeline for transporting a mixture of first working fluid and second working fluid to a condenser/absorber where a third working fluid is added and whereby the third working fluid dissolves the second working fluid from the first working fluid causing the first working fluid to condense and transmitting heat to a heat sink, a second fluid pipeline for transporting the first working fluid back to the evaporator, a third fluid pipeline for transporting the mixture of the second and third working fluids to a separator wherein separation of said second and third working fluids from one another takes place assisted by injection of a pressurised gas into the separator, a fourth fluid pipeline to transport said second working fluid to the evaporator and a fifth fluid pipeline to transport said third working fluid to the condenser/absorber.

The pressurised gas may be the third working fluid in a gaseous or vapour phase, and it may be injected at an elevated temperature. This may be obtained from, for example steam being vented from a turbine in a Rankine-cycle thermal power plant. There may be a valve provided on the separator to vent or drain excess third working fluid. The dissolving of the second working fluid in the third working fluid may be exothermic.

At least one of the first, second, third, fourth or fifth fluid pipelines may pass another of said first, second, third, fourth or fifth fluid pipelines through a heat exchanger.

At least one of the first, second, third, fourth or fifth fluid pipelines may pass through a purifying unit.

The purifying unit may contain activated alumina to assist separation of the second and third working fluids. The purifying units may be heated by a heat source to assist separation of the second and third working fluids. The heat source may comprise the third working fluid at an elevated pressure and/or temperature.

At least one of the first, second, third, fourth or fifth fluid pipelines may pass through a pressure boosting device.

At least one of the first, second, third, fourth or fifth fluid pipelines may pass through a valve. The first working fluid may be selected on the basis of assured liquid-liquid separation at higher temperature in the condenser/absorber with respect to the second fluid dissolved in the third fluid. It may be for example selected from the group consisting of an alkane and pyrrolidine. The second working fluid may be ammonia. The third working fluid may be selected from the group consisting of water, an ionic liquid or a thermal oil.

According to a second aspect of the present invention there is provided heat transfer apparatus comprising two or more heat transfer apparatus of the first aspect wherein the two or more apparatus are connected together such that the condenser/absorber of one apparatus supplies heat to the evaporator of the second apparatus.

According to a third aspect of the present invention there is provided heat transfer apparatus comprising at least one heat transfer apparatus of any preceding claim wherein the condenser/absorber of the at least one apparatus supplies heat to at least one chemical heat pump.

The at least one chemical heat pump may use the reversible endothermic and exothermic reactions of the hydrogenation and dehydrogenation of a substance. The at least one chemical heat pump may use the reversible endothermic and exothermic reactions of the hydration and dehydration of a substance. The at least one chemical heat pump uses the reversible endothermic and exothermic reactions of the carbonation and decarbonation of a substance. By "carbonation" and "decarbonation" this will be understood to mean, respectively, the reaction of a first substance, usually an oxide, with carbon dioxide to form a second substance, such as a carbonate, and the reverse of that process.

According to a fourth aspect of the present invention there is provided a method of heat transfer comprising the steps of evaporating a first working fluid in an evaporator in the presence of a second working fluid thereby absorbing heat from a first heat source, transporting a mixture of first working fluid and second working fluid to a condenser/absorber where a third working fluid is added and whereby the third working fluid dissolves the second working fluid from the first working fluid causing the first working fluid to condense and transmitting heat to a heat sink, transporting the first working fluid back to the evaporator, transporting the mixture of the second and third working fluids to a separator, injecting of a pressurised gas into said second and third working fluids thereby separating them from one another, transporting said second working fluid to the evaporator and transporting said third working fluid to the condenser/absorber.

The pressurised gas may be the third working fluid in a gaseous or vapour phase, and it may be injected at an elevated temperature. This may be obtained from, for example steam being vented from a turbine in a Rankine-cycle thermal power plant.

The first working fluid may be selected on the basis of assured liquid-liquid separation at higher temperature in the condenser/absorber with respect to the second fluid dissolved in the third fluid. It may be for example selected from the group consisting of an alkane and pyrrolidine. The second working fluid may be ammonia. The third working fluid may be selected from the group consisting of water, an ionic liquid or a thermal oil. According to a fifth aspect of the present invention there is provided a circulating water heat transfer apparatus utilising a three fluid absorption cycle comprising an evaporator for evaporating a first working fluid in the presence of a second working fluid thereby absorbing heat from a first heat source in a circulating water apparatus, a first fluid pipeline for transporting a mixture of first working fluid and second working fluid to a condenser/absorber where a third working fluid is added and whereby the third working fluid dissolves the second working fluid from the first working fluid causing the first working fluid to condense and transmitting heat to a heat sink, a second fluid pipeline for transporting the first working fluid back to the evaporator, a third fluid pipeline for transporting the mixture of the second and third working fluids to a separator wherein separation of said second and third working fluids from one another takes place, a fourth fluid pipeline to transport said second working fluid to the evaporator and a fifth fluid pipeline to transport said third working fluid to the condenser/absorber.

"Circulating water" apparatus will be understood by the skilled addressee to comprise all apparatus in which water is used as a working fluid or coolant exchanging heat with the ambient environment. Examples include, but are not limited to, thermal power stations and petrochemical refineries.

A second heat source may be applied to the separator to aid separation of the second and third working fluids. The second heat source may be provided by the circulating water apparatus. For example, steam may be vented from a turbine to provide the heat source.

The first working fluid may be selected on the basis of assured liquid-liquid separation at higher temperature in the condenser/absorber with respect to the second fluid dissolved in the third fluid. It may be for example selected from the group consisting of an alkane and pyrrolidine. The second working fluid may be ammonia. The third working fluid may be selected from the group consisting of water, an ionic liquid or a thermal oil. At least one of the first, second, third, fourth or fifth fluid pipelines may pass another of said first, second, third, fourth or fifth fluid pipelines through a heat exchanger. At least one of the first, second, third, fourth or fifth fluid pipelines may pass through a purifying unit.

At least one of the first, second, third, fourth or fifth fluid pipelines may pass through a pressure boosting device.

At least one of the first, second, third, fourth or fifth fluid pipelines may pass through a valve. According to a sixth aspect of the present invention there is provided a method of recovering heat from a circulating water process comprising the steps of evaporating a first working fluid in an evaporator in the presence of a second working fluid thereby absorbing heat from circulating water within the process, transporting a mixture of first working fluid and second working fluid to a condenser/absorber where a third working fluid is added and whereby the third working fluid dissolves the second working fluid from the first working fluid causing the first working fluid to condense and transmitting heat to a heat sink, transporting the first working fluid back to the evaporator, transporting the mixture of the second and third working fluids to a separator wherein separation of said second and third working fluids from one another takes place, transporting said second working fluid to the evaporator and transporting said third working fluid to the condenser/absorber.

A second heat source may be applied to the separator to aid separation of the second and third working fluids. The second heat source may be provided by the circulating water apparatus. For example, steam may be vented from a turbine to provide the heat source.

The first working fluid may be selected on the basis of assured liquid-liquid separation at higher temperature in the condenser/absorber with respect to the second fluid dissolved in the third fluid. It may be for example selected from the group consisting of an alkane and pyrrolidine. The second working fluid may be ammonia. The third working fluid may be selected from the group consisting of water, an ionic liquid or a thermal oil.

According to a seventh aspect of the present invention there is provided an electricity generating station comprising at least one of the apparatus according to the first, second, third or fifth aspects, and/or using the method of the fourth or sixth aspects.

According to an eighth aspect of the present invention there is provided circulating water apparatus comprising at least one of the apparatus according to the first, second, third or fifth aspects, and/or using the method of the fourth or sixth aspects.

Brief Description of the Drawings

Fig. 1 is a schematic representation of a first embodiment heat transfer apparatus according to a first aspect and fifth of the present invention and of a heat transfer method according to a fourth and sixth aspect of the present invention;

Fig. 2 is a schematic representation of a second embodiment heat transfer apparatus according to a second aspect of the present invention and of a heat transfer method according to a fourth and sixth aspect of the present invention;

Fig. 3 a schematic representation of a third embodiment heat transfer apparatus according to a first aspect of the present invention and of a heat transfer method according to a third aspect of the present invention;

Fig. 4 is a schematic representation of a fourth embodiment heat transfer apparatus according to a first and fifth aspect of the present invention and of a heat transfer method according to a fourth and sixth aspect of the present invention; and Fig. 5 is a schematic representation of a fifth embodiment heat transfer apparatus according to a fifth aspect of the present invention and of a heat transfer method according to a sixth aspect of the present invention.

Referring to the drawings and initially to Fig. 1, a heat transfer apparatus 10 is shown.

Vessel BB1 (the "Evaporator") extracts heat from the surrounding environment (Qin) or from a specific heat source (not shown) such as the wet vapour output from a turbine in a Rankine cycle thermal power cycle.

The heat is extracted by the continuous boiling of a first working fluid {1} in the presence of a chemically inert second working fluid {2} due to lowered partial pressure corresponding to the saturation pressure with respect to the surrounding temperature. First working fluid may be, for example, pyrrolidine and the second working fluid may be ammonia.

Continuous boiling in the Evaporator is achieved by the ingress of working fluid {2} in vapour form through a pipeline BR1 and working fluid {1} in liquid form through a pipeline BR9 to feed the egress of a vapour phase consisting of a mixture of working fluids {1} and {2} out through a pipeline BR2.

The vapour mixture of the working fluids {1} and {2} is transported to a vessel BB2 (the "Condenser/Absorber") through various individual pipeline sections, specifically numbered BR2, BR3, BR4 and BR5 in Fig. 1. The combination of these various individual sections, together with the intervening components, may be considered as a first pipeline which allows transport of vapour mixture of the working fluids {1} and {2} between the Evaporator BB1 and the Condenser/Absorber BB2. In this particular embodiment, various components are placed within the first pipeline.

The pressure of the vapour mixture in pipeline BR2 is boosted by a compressor AN1. Pipeline BR3 transports the vapour mixture from the compressor AN1 to a heat exchanger ACl. Pipeline BR4 transports the vapour mixture from the first heat exchanger ACl to a heat exchanger AC2. The compressor AN1 may overcome a pressure drop in heat exchangers ACl and AC2. Pipeline BR5 transports the vapour mixture to vessel BB2.

Working fluid {3} is injected into the vessel BB2 through pipeline BR18. Working fluid {3} is in this example water.

Working fluid {3} dissolves working fluid {2} out of the vapour mixture with working fluid {1}. Working fluid {1} is forced to recover the partial pressure and is forced to condense itself, forming a liquid phase that exists in conjunction with working fluid {3} incorporating the dissolved fluid {2} as a solution.

Heat is rejected from the vessel BB2 (Qout) due to the condensation of fluid {1} and the exothermic reaction of the dissolution of fluid {2} in fluid {3}.

The condensed working fluid {1} is transported back to Evaporator vessel BB1 through various individual pipeline sections, specifically numbered BR6, BR7, BR8 and BR9 in Fig. 1. The combination of these various individual sections, together with the intervening components, may be considered as a second pipeline which allows transport of condensed working fluids {1} between the Condenser/Absorber BB2 and the Evaporator BB1.

The initial pipeline section BR6 initially transports the condensed working fluid {1} to a purifying unit ATI. Purifying unit ATI may separate traces of fluid {3} and/or fluid {2} as may be necessary. From purifying unit ATI, the pipeline BR7 conducts the fluid {1} to the heat exchanger ACl for heating up the vapour mixture of fluid {1} and {2} coming out of Evaporator BB1. It is further cooled by the heat exchanger AC4 prior to its return to Evaporator BB1 via pipeline BR9.

Evaporator BB1 should be preferably located at a lower elevation compared to the Condenser/Absorber vessel BB2 to ensure that the condensed working fluid {1} can overcome the resistance in fluid flow due to the pressure drop in purifying unit ATI, heat exchanger AC1 and heat exchanger AC4 preferably by utilising the geodetic head. The installation of a pump to overcome such pressure loss is covered by the scope of this invention.

The working fluid {3} containing the dissolved working fluid {2} is transported from the Condenser/Absorber BB2 through various individual pipeline sections, specifically numbered BRIO, BR11, BR12, BR13 and BR14 in Fig. 1. The combination of these various individual sections, together with the intervening components, may be considered as a third pipeline which allows transport of the working fluid {3} containing the dissolved working fluid {2} between the Condenser/Absorber BB2 and a Separator BB3.

The pipeline BRIO carries the fluid {3} containing the dissolved fluid {2} from vessel BB2 to a compressor or pump API and then onward through pipeline BR11, through heat exchangers AC2, on through pipeline section BR12, through heat exchanger AC5, on through pipeline section BR13, to valve AAl, prior to being fed into the packed column Separator vessel BB3 via pipe line BR14. The heat exchanger AC5 or further embodiments thereof might be present for heating other fluid streams, using a seventh pipeline referred to as BRX.

The Separator BB3 (which is not sealed, but is continuously subjected to ingress and egress of working fluids) is designed for the purpose of removing the dissolved working fluid {2} from the working fluid {3} by employing either a gaseous phase of the working fluid {3} at higher pressure and/or temperature from a pipeline BR19 or purely by the application of heat (with or without agitation). Such heat may typically be at temperatures beyond 200°C at pressures equal to or higher than atmospheric.

Working fluid {2} exits in vapour form from a reflux condenser AC3, which in this embodiment is an integral part of Separator BB3 but shown on Fig.l schematically separate from Separator BB3 and is returned to vessel BB1 through pipeline BR1, after purification in a purifying unit AT3. BR1 may be considered as a fourth fluid pipeline which transports working fluid {2} from Separator BB3 back to Evaporator BB1. A pipeline BR20 is included which acts as a make-up line for optionally injecting additional mass flows into pipeline BR1.

Working fluid {3} exits in liquid form from Separator BB3 and is transported to Condenser/Absorber vessel BB2 via a fifth pipeline. The fifth pipeline comprises various pipeline sections and intervening components in the present embodiment: initial pipeline section BR15; to a purifying unit AT2; pipeline section BR16; compressor AP2; pipeline section BR17; valve AA1; and finally pipeline BR18 into Condenser/Absorber vessel BB2.

Valves AA1 and AA2 are required to achieve the desired pressure levels in pipelines BR14 and BR18 respectively.

The various processes described above constitute a cycle capable of acting as a heat pump for industrial applications. Capabilities for load variation might be typically implemented through modulation of the valves AA1/AA2, variable frequency drives for AN1/AP1/AP2, level control settings for BB1/BB2/BB3 and similarly appropriate means for ensuring a stable, reliable and flexible operating philosophy based on standard engineering practices with proper techno-economic optimisation- without impairing the desired functional reliability of the working cycle. Such features for industrial adaptation are deemed to constitute essential components of this invention, without any restriction in the choice of methodologies deemed necessary for control, protection and inter-locks. The choice of the working fluids {1}, {2} and {3} is determined from appropriate temperature regimes and appropriate choice of pressures which determine the (volumetric) sizing and (wall thickness) rating of the constituent equipments. The wall thickness of the equipment ought to confirm to general manufacturing limits for the selected materials.

An embodiment of the second aspect of the present invention is shown schematically in Fig. 2. In this embodiment, the Condenser/Absorber of the first apparatus or cycle supplies heat to the Evaporator of the second apparatus or cycle, effecting enhanced heat transfer to higher temperatures.

This embodiment may be used for delivering heat for rich amine regeneration in the re-boiler of the stripper in a post combustion carbon capture plant without involving substantial steam extraction from the IP/LP Cross-over line in the steam turbine train of thermal power stations.

In Fig. 2, cooling water is typically available from the exit of a stripper condenser at 74°C. An initial application of cold reheat steam with subsequent routing to the heat exchanger AC5, as in Fig. 1, is sufficient to raise its temperature to beyond 80°C, which might be the starting point for heat input to the evaporator of the first cycle or apparatus.

The first cycle or apparatus is typically envisaged to constitute three working fluids: pyrrolidine, ammonia and water. This is capable of delivering heat from the condenser/absorber at temperatures of around 108°C, which serves as an input to the evaporator of a second cycle or apparatus.

The second cycle or apparatus is typically envisaged to constitute three working fluids: 3,3-diethylpentane, ammonia and water, which is capable of taking in heat from the first cycle or apparatus described above and delivering heat to a re-boiler at around 122°C, sufficient for rich amine regeneration by stripping it of carbon dioxide. The above processes require a minimum of steam at sufficiently high pressures (which might typically be the cold reheat line) to be fed into the separator column for separating water and ammonia. The loss in power generation, together with the auxiliary power for pumps and compressors, is determined to be a small fraction of the power loss from the overall generation capacity if this amount of heat would have to be delivered from IP/LP cross over line.

Fig. 3 depicts an embodiment of the third aspect of the present invention. This embodiment is illustrates a modified thermal cycle according to the first aspect and labelled Water/Ammonia/Pentane heat pumps cascaded with further chemical heat pumps effecting enhanced heat transfer to higher temperatures. This is intended to augment the power generation by eliminating/supplementing regenerative feed heating and/or the steam generator (which is deemed to include any method of heat transfer for transferring heat to water/steam including a nuclear reactor by direct or indirect means, e.g. by molten metals like sodium) re-heater in power generating stations incorporating steam turbine module(s). In one form of the preferred embodiment, it is capable of mitigating the power loss due to the auxiliary power consumption in the modified cycles, cascaded chemical pumps, blowers and pumps in the carbon capture process and including the compressor for compressing carbon dioxide obtained from the carbon capture process.

A typical embodiment of the modified cycle using Ammonia/Water/Pentane provides the uplift for the low grade waste heat (that would have otherwise been eventually rejected to the ambient air or water) at 30~35 °C to 70~75 °C. This heat is utilised by a cascade of chemical heat pumps that augment this heat to a temperature, where after the chemical heat pump operates as a chemical storage device. The first chemical heat pump will utilize the heat output from the modified Einstein cycle at ~70°C as the heat source for the endothermic reaction of dehydration of tert-butanol into isobutene and water. The exothermic reaction of the hydration of isobutene and water results in the formation of tert-butanol at ~110 °C. The choice of the working fluids is subject to further optimisation, but the source of heat input of the chemical heat pump from the modified Einstein cycle is deemed to constitute an essential part of this invention, together with the present application of being used to eliminate/supplement the feed heating cycle in power generating stations.

The heat generated as by the above reaction is typically used in a second chemical heat pump to provide the required energy for the dehydrogenation reaction of Iso- propanol at 110 °C to form acetone and hydrogen, the choice of the working fluids being typically illustrative. The reversible hydrogenation exothermic reaction of acetone and hydrogen provides the temperature lift to 200°C.

Beyond 200 °C, hydration/de-hydration of metal oxides like Magnesium Oxide (typical) can be used to boost temperatures of heat delivery up to ~300 °C. This is typically deemed to represent the final feed-water temperature entering the economising section of a steam generator.

Beyond ~300 °C, the carbon dioxide separated from the carbon capture plant may be gainfully employed in a chemical heat pump constituting a carbonation/de- carbonation process using Lead Oxide (typical) to boost temperatures to ~450 °C.

Beyond ~450 °C, heat delivery temperatures can be raised to ~620 °C by employing hydration/de-hydration of metal oxides like Calcium Oxide (typical). This is aimed to eliminate/supplement the re-heater in steam generator of power generating stations and the employment of such means of heat delivery.

Fig. 4 depicts a modification from the Fig. 1 embodiment. It will be appreciated that common features are depicted in both and that these are labelled identically. The main difference is in the inclusion of a modified system to enhance the separation of the two working fluids. This is depicted to the right hand side of the Fig. 4 embodiment 100. BR13 again carries the working fluid mixture to separator BB3. In this embodiment, the separator is shown smaller than in the Fig. 1 embodiment, but it will be appreciated by those skilled in the art this is for schematic purposes only, and may be of any suitable size. Working fluid {3} at elevated pressure and/or temperature is injected into the separator via BR19.

Again, two outputs from the separator BB3 are provided which proceed along BR14 and BR15. Two purifying units BB4 and BB5 are provided into which fluid flow from BR14 and BR15 respectively enter. The purifying units include activated alumina 102 (shown schematically as circles within the BB4 and BB5 units). The activated alumina acts as a desiccant to working fluid {3} (i.e. water), drawing it out of the mixture with working fluid {2} (i.e. ammonia). Thus, the purity of working fluid {2} exiting purifying units BB4 and BB5 is improved. Working fluid {3} may be liberated from the activated alumina by the application of heat. Since working fluid {3} is envisaged as a working fluid which is relatively safe, and relatively plentiful, e.g. water, the fact that additional working fluid {3} must be added to the system to compensate for the quantity of working fluid {3} that is temporarily removed from the cycle by its absorption by the activated alumina.

Heat may be applied to purifying units BB4 and BB5 by, for example, drawing working fluid {3} from the process where it is at an elevated temperature and pressure, for example drawing it from prior to entry into an electricity generating turbine, or at another suitable point in the process.

Fig. 5 depicts an embodiment according to the fifth and sixth aspects of the present invention. Fig. 5 depicts a modification from the Fig. 1 embodiment. It will be appreciated that common features are depicted in both and that these are labelled identically. The main difference is in the inclusion of a modified system to enhance the separation of the two working fluids. This is depicted to the right hand side of the Fig. 5 embodiment 200. In the Fig. 5 embodiment 200 the third working fluid {3} is an ionic liquid or a mineral oil with low vapour pressure being the principal characteristic. While the evaporation and condensation / absorption components are similar, the separation of the third working fluid {3} from the second working fluid {2} is achieved in a different way, by taking advantage of the low vapour pressure of the third working fluid.

While the first and second system of fluid pipelines are similar to the first aspect of the invention, the third system of fluid pipeline constitutes the pipeline BR13i as an entry point to the separation process with the condenser / absorber BB2 as the upstream source.

A mixture of the second working fluid dissolved in the third working fluid is carried by fluid pipeline BR13i through the flow restricting device AAli, which may be a valve; to the separator vessel BB3i by the fluid pipeline BR14i. The pressure in BB3i is lower than the pressure prevalent in the BB1 or BB2 (system pressure) due to the throttling in AAli. The reduced pressure enables easier separation of the mixture into the second working fluid as vapour phase and the third working fluid as the liquid phase by the application of heat {Qi}, which may be typically obtained by steam drawn from the turbine in a power generating station and / or other molecular agitation phenomena like electrolysis or ultra-sonography. The electric energy required for the same may be typically drawn from the power generating station or the electric grid by appropriate conversion of high voltage to high current. The third working fluid exiting as liquid from BB3i is restored to system pressure through pump AP2i before being led into pipeline BR23 for discharge into the condenser / absorber BB2 after being regulated for pressure maintenance by valve AA2. This constitutes the fifth fluid pipeline for returning the third working fluid from the separator BB3i to the condenser / absorber BB2. The second working fluid exiting as vapour from BB3i is carried by pipeline BR16i to the compressor AN2i, which exhausts to pipeline BRli. Any external make-up of the second working fluid is achieved by the pipeline BR20, which merges with pipeline BRli for constituting the fourth pipeline BR1 for returning the second working fluid to the evaporator BB1.

As might be appreciated by those skilled in the art, the above processes are capable of substantial augmentation of power generation capability without substantial re- engineering of conventional equipment together with mitigating the losses incurred due to parasitic power consumption by auxiliary processes (with or without addons like carbon capture plants). It is recognised that processes involving solid phase reactions are subject to alternate phases of operation and cannot be expected to function in a pure cyclic manner for single unit components as is typically expected for process applications.

However, it is nevertheless recognised that the waxing and waning of solid phase reactions can be optimally engineered to operate in a phased sequence such that the multiplicity of a number of similar units can be expected to approach the cyclic mode of operation progressively through a batch mode and semi-continuous mode of combined operations. The availability of high temperatures generated by the above process might be most gainfully employed in heating up an optimal proportion of the carbon dioxide obtained from post combustion carbon capture plants to remove moisture in an inert atmosphere environment from high moisture content fuels like sub- bituminous coals/lignite and bio-mass which are consumed as raw materials for combustion processes used in various industries (including but not limited to power generation).

The sourcing of carbon dioxide as the inert gas constituting the required inert atmosphere for moisture removal from the post combustion carbon capture process, together with source of heat required to be imparted to it for optimal removal of moisture from fuels used in the combustion process- derived by the utilisation of at least one embodiment of the modified Einstein cycle either in a stand-along configuration, or cascaded with further embodiments of the modified Einstein cycle, with or without additional cascades of chemical heat pumps, are deemed to constitute essential parts of this invention. The potential of the modified cycle for recovering waste heat from circulating water systems in industrial applications other than power generating has substantial scope of recovering heat rejected to the circulating water system by processes including (but not limited to) alkylation unit, sulphur plant, reformer, hydro- treater, etc. for application in heat consuming processes including (but not limited to) heating applications (e.g. crude distillation unit, hydro-treater, vacuum distillation unit, production of alkylates, reforming, hydro-cracking, production of isomers, etc.) by gainfully employing single embodiments or cascaded embodiments of the modified cycle with or without chemical heat pumps described above. The process described above is capable of gainful application in a variety of industries like Petrochem, Iron & Steel, Pulp & Paper, Viscose Rayon, Fertiliser, Leather, Alcohol, etc. where it is deemed useful to recover waste heat from circulating water systems. Moreover, coolant or feed water used in such processes will typically be fed in from a natural feature such as a stream. The present invention may be used to cool the incoming stream. Hence, it is possible to cool the incoming stream of cooling water to a desired amount, prior to its entry into the condenser. This has the benefit of reducing condenser vacuum with respect to LP turbine exhaust, below the limits imposed by ambient conditions or the circulating water system exchanging heat with the ambient environment. This alters the exhaust loss profile and adds to power generation capability. Furthermore, this may mitigate the difference in efficiencies between power plants in tropical and temperate latitudes and likewise between coastal and inland power plants.

After getting heated up in the condenser the cooling water outlet temperature can be still lower than the ambient. This is beneficial in all respects, but particularly for direct discharge into natural water bodies since lowering of temperatures for liquids increases solubility of gases- the Biological Oxygen Demand (BOD) and may aid flora and fauna. Modifications and improvements can be made to the embodiments herein before described without departing from the scope of the invention.

The working fluids are not limited to those discussed in the specific embodiments. The principal nature of custom engineered ionic liquids which have contributed to their attractiveness in vapour absorption cycles is their low vapour pressure across a wide range of temperatures (at least up to 200 °C), which significantly reduce the amount of heat energy needed to disassociate dissolved gases from solutions consisting of ionic liquid(s) or containing significant proportions thereof. However, while thermal stability of ionic liquids and their ability to dissolve gases at higher temperatures might be limited, there exists another class of liquids- the so called "heat transfer fluids" or "thermal oils" which also display low vapour pressures across a wide range of temperatures and which retain thermal stability at relatively higher temperatures suitable for solar powered applications. The typical class of liquids suitable for such applications are custom-engineered 'synthetic' fluids typically consisting of benzene-based structures and include the diphenyl oxide/biphenyl fluids, the diphenylenthanes, dibenzyltoluenes, and terphenyls. They are formulated from alkaline organic and inorganic compounds and often used in diluted forms. Typical examples include a mixture of biphenyl (C12H10) and diphenyl oxide (C12H10O), variously sold under brand names like DOWTHERM A, DOWTHERM G, THERMINOL, etc.

It is thereby possible to formulate a 'synthetic liquid' described above with the characteristic low vapour pressure, thermal stability at high temperatures and desired solubility of dissolved gases at a certain range of temperatures suitable for optimum performance of the working fluids constituting the modified cycle under consideration. The amount of heat at the desired temperature required to separate the dissolved gases from such a typical liquid would be typically available from the nature of industrial applications considered in this invention (e.g. power plants, petrochemical plants, etc.). In light of the above, it is possible to formulate a 'synthetic liquid' for use in the modified cycle described herein which requires only a minimum amount of heat to separate the dissolved gases from a liquid, from a heat source readily available in the nature of the industries considered fit for purpose for the application of this invention. While it is not the intent of this invention to formulate the exact composition of such 'synthetic liquids', the inventor and the assignees would not be precluded from using such 'synthetic liquids' if determined to be optimally suitable for purpose of being employed in the modified cycle described herein, under the terms and conditions of any protection mechanism. The scope of this invention is deemed to extend to the deployment of such 'synthetic' liquids which are made to be fit for purpose in modified cycle(s) described herein.