GB2602832A

GB2602832A - Sorption cooling system for contaminated heat sources

Info

Publication number: GB2602832A
Application number: GB2100626.7A
Authority: GB
Inventors: Ducheyne Wouter
Original assignee: Caloritum
Current assignee: Caloritum
Priority date: 2021-01-18
Filing date: 2021-01-18
Publication date: 2022-07-20
Also published as: WO2022152935A1; GB202100626D0

Abstract

A sorption cooling system for cooling a feed stream 102 comprising an evaporation unit 112 that has a first inlet 116 to receive the feed stream, a first outlet 117 to exit a stream of water vapor 103 from said feed stream; and a sorption unit 113 connected to the evaporation unit. The sorption unit has a first inlet to receive said stream of water vapor, a second inlet 121 adapted to receive sorption means 100 such as polyphosphoric acid to absorb water vapor, thereby forming consumed sorption means 101, and a first outlet 120 adapted to exit consumed sorption means. The evaporation unit also has a second outlet 118 for a cooled feed stream 104. A heat exchanger 107 may be used to regulate the temperature of the sorbent in the sorption unit. The cooling system may also include a regeneration means 106 for regenerating consumed sorbent into usable sorbent again. The regeneration system may include a heat exchange element 111 or an economiser 108 that provides counterflow heat exchange between the sorption means and consumed sorbent.

Description

SORPTION COOLING SYSTEM FOR CONTAMINATED HEAT SOURCES

FIELD OF THE INVENTION

The present invention is related to the field of cooling, more specifically sorption cooling. More specifically, the present invention relates to a sorption cooling system for cooling e.g. a contaminated feed stream of a liquid, e.g. wastewater from industrial plants, sewage... Further, the present invention pertains to the use of said system and a method to cool said stream thereof.

BACKGROUND TO THE INVENTION

Cooling is an important process in many industries. Wherein it is required to either maintain or lower the temperature of a space, a product and/or a substance. In industry many processes still retain a lot of residual heat value; i.e. the outlet temperature of the industrial process is substantial above the ambient temperature which indicates the substantial residual heat value.

Due to the fad liquid outlet stream contain substances -such as but not limited to solids, fibers suspended contaminants, large molecules, biomolecules, dissolved salts close to suspension limit,....-which create fouling and or biofouling, blocking or other ways of limiting the heat transfer, heat is not utilised until now. This blocked or hindered heat transfer makes it not economical to recuperate this residual heat. E.g. the cleaning costs are simply too high or the process disturbances caused by blocked filters or fouled equipment have a negative impact on the overall asset effectiveness and process performance. A practical process enabling further cooling down of industrial processes towards ambient temperatures (or ambient air wet bulb temperatures) is desired in industry to further decrease sustainability of many processes.

In a broader sense, cooling pertains to the heat transfer from a low-temperature reservoir to a high-temperature reservoir. This heat transfer can be performed in various ways, such as, and not limited to: mechanical-compression cooling, absorption cooling, evaporative cooling, and thermoelectric cooling.

In light of the effects of humans' CO2 emissions, meaning global warming, and stricter environmental policies by governments and organizations which aim at reducing energy consumption and/or favor energy recuperation plants, the cooling field needs novel techniques and cooling system fulfilling this need.

Absorption cooling techniques provides for heat transfer by means of an absorption cycle, working in a way similar to what the more commonplace compression cycle offer, except for the method of raising the pressure of the refrigerant vapor. In an absorption system, the compressor is replaced by an absorber which dissolves the refrigerant in a suitable liquid, a liquid pump which raises the pressure and a generator which, on heat addition, drives off the refrigerant vapor from the high-pressure liquid. Vapor absorption cycles are relatively inefficient compared to vapor compression cycles, nevertheless, they are useful for example where fuel for heating is available but electricity is not, such as in recreational vehicles that carry LP gas, or in industrial environments where plentiful waste heat overcomes its inefficiency.

Different absorption cooling system in the state of the art is currently available, among these, lithium bromide-based cooling systems and ammonia-water systems are the most common. In a water-lithium bromide vapor absorption cooling system, water is used as refrigerant, and lithium bromide (LiBr) is used as the absorbent. In such system, LiBr absorbs water vapor from the water refrigerant, which water vapor passes through a condenser providing for the cooling effect. After the water vapor is absorbed, a diluted solution of lithium bromide is obtained, which shall be regenerated to provide again for its absorbing properties. In an ammonia water system, the cooling effect is provided in a similar way, with the main difference residing in water being the absorbent, due to its high affinity for ammonia, whilst liquid ammonia being the refrigerant, with ammonia gas being evaporated and said evaporation providing for the cooling effect.

US4062197A describes an absorption heating-cooling system wherein a membrane is used to separate water from the sorbent after it is consumed. The use of membranes poses limits to the types of refrigerants used in the system, as said membranes require to be resistant to extremely acid or basic conditions, as for example the acidic conditions provided by LiBr solutions. Further, separation membranes are often delicate due to their composition and require particular care in being sensitive to breaking or clogging. To prevent these events to happen to the membranes, monitoring and/or preventive maintenance of said membranes is often required, this providing for additional complexity of the maintenance operation, causing increase in costs.

It is an object of the present invention to overcome the drawbacks of the prior art to work with contaminated streams and provide for an improved sorption cooling system and a new method of cooling by using said system. Further, it is an object of the present invention to provide for a new cooling system providing a reduced contamination of the stream to be cooled and/or providing increased cooling velocity, efficiency and/or continuous operation.

SUMMARY OF THE INVENTION

The present invention provides for sorption cooling system. Here below, enumerated embodiments of the invention are provided.

1. A sorption cooling system for cooling a feed stream comprising: An evaporation unit, meaning a unit wherein the evaporation of a liquid thereby contained cools said liquid, having a first inlet adapted to receive the liquid feed stream, a first outlet adapted to exit a stream of water vapor from said feed stream; and - a sorption unit connected to the evaporation unit, wherein the sorption unit has; o a first inlet adapted to receive said stream of water vapor from the first outlet of the evaporation unit; o a second inlet adapted to receive sorption means to absorb water from said stream of water vapor, thereby forming consumed sorption means; o a first outlet adapted to exit consumed sorption means; and wherein the evaporation unit further comprises a second outlet adapted to exit a cooled feed stream.

2. The sorption cooling system according to the previous claim, wherein the sorption means is provided to the sorption unit at a temperature below 150 °C, preferably from about 50 to 90 °C.

3. The sorption cooling system according to any of claims 1 to 2, wherein the sorption means comprises polyphosphoric acid and/or highly concentrated phosphoric acid.

4. The sorption cooling system according to any of claims 1 to 3, further comprising a first heat exchange element provided to exchange heat with the sorption means. In particular, the first heat exchange element provides for exchange of heat between said sorption means and e.g. heat exchange fluid inside the first head exchange element, so that based on the temperature of said fluid, the temperature of the sorption means can be controlled.

5. The sorption cooling system according to any one of claims 1 to 4, further comprising reduced pressure providing means connected to the evaporation unit and/or the sorption unit. The reduced pressure providing means are provided to reduce the gaseous pressure above the feed stream.

6. The sorption cooling system according to any one of claims 1 to 5, wherein said sorption means has a mass percentage concentration of polyphosphoric acid and/or highly concentrated phosphoric acid (PA/PPA) in the range from about 85 to 110 %, more preferably 95 to 105%.

7. The sorption cooling system according to any one of claims 1 to 6, further comprising reduced pressure providing means connected to the evaporation unit and/or the sorption unit.

Preferably, the reduced pressure providing means is a vacuum pump adapted to startup the installation and/or to remove the inerts, i.e. all conceivable gases (such as nitrogen) or gas mixtures that are inert to the liquid, continuously or discontinuously.

S. The sorption cooling system according to any of claims 1 to 7, further comprising regeneration means, which are adapted to regenerate consumed sorption means, and feed such regenerated sorption means into the sorption unit.

9. The sorption cooling system according to claim 8, the regeneration means comprising: a second heat exchange element providing heat to the consumed sorption means, thereby forming regenerated sorption means. More specifically, regeneration means are adapted to regenerate the sorption means thereby allowing the sorption properties of the sorption means to be improved compared to the those of sorption means which have been consumed.

10. The sorption cooling system according to claims 8 to 9, the regeneration means further comprising: - an economiser providing said regenerated sorption means in counterflow with consumed sorption means. Wherein the economiser allows for heat exchange between regenerated sorption means at a higher temperature and consumed sorption means at a lower temperature.

11. The sorption cooling system according to any one of claims 1 to 10, wherein the sorption unit comprises: - a mixing unit, adapted to mix the water vapor entering the sorption unit with the sorption means; and - a sorption unit top, adapted to distribute the regenerated or fresh sorption means; - a sorption unit base, adapted to collect the consumed sorption means.

12. Use of a sorption cooling system as defined in any of claims Ito 11, for cooling a feed stream 13. The use of a cooling system as defined in claim 12, wherein the feed stream is wastewater, such as wastewater from the food industry, beverage industry, pulp and paper industry.

14. The use of a cooling system as defined in claims 12 to 13, wherein the feed stream is at a temperature from about 0°C to 100°C, preferably 0°C to 60°C.

15. The use of a cooling system as defined in claim 12 to 14, wherein the feed stream is a slurry. In other words, the feed stream is a mixture of solids denser than water suspended in liquid, usually water.

16. A method of cooling a feed stream in accordance with the sorption cooling system described in claims Ito 11, the method comprising the steps of: (a) providing a feed stream to an evaporation unit; (b) providing sorption means to a sorption unit; (c) evaporating a stream of water vapor from said feed stream by means of the evaporation unit; (d) feeding said stream of water vapor into the sorption unit.

(e) contacting said stream of water vapor with the sorption means to absorb water from said stream of water vapor, thereby forming consumed sorption means, and (f) outgoing said feed stream from the evaporation unit as cooled feed stream. The feed stream is cooled through the evaporation of the water vapor from said feed stream, which is enhanced in the sorption cooling system as herein provided through the absorption of the water vapor into to the sorption unit. Coupling the evaporation unit with a sorption unit lowers the vapor pressure above the feed stream, allowing more water to evaporate from said feed stream, resulting in increased cooling.

17. The method of cooling a feed stream according to claim 16, wherein at step (b) the sorption means is provided at a temperature below 150 °C, preferably from about 50 up to 90°C.

18. The method of cooling a feed stream according to claims 16 to 17, wherein the sorption means comprise polyphosphoric acid and/or highly concentrated phosphoric acid.

19. The method of cooling a feed stream according to claim 18, wherein the concentration of polyphosphoric acid and/or highly concentrated phosphoric acid has a mass percentage concentration of H3PO4 (PA/PPA) in the range from about 85 to 110%, more preferably 95 to 105%.

20. The method of cooling a feed stream according to any one of claims 15 to 18, wherein at step (c) the evaporation of the stream of water vapor is provided at a vacuum pressure from about 20 mbara to 1000 mbara more preferably from about 30 to 500 mbara.

21. The method of cooling a feed stream according to claim 16 to 20, further comprising the step of: (g) regenerating sorption means from consumed sorption means by means of regeneration means.

22. The method of cooling a feed stream according to claim 21, wherein sorption means are regenerated from consumed sorption means by heating the sorption means at a temperature from about 80 to 230 °C, preferably from about 160 to 200 °C.

23. The method of cooling a feed stream according to claims 21 to 22, wherein at step (g), the consumed sorption means are pre-heated by sorption means at a temperature higher than the temperature of the consumed sorption means.

BRIEF DESCRIPTION OF THE DRAWINGS

With specific reference now to the figures, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the different embodiments of the present invention only. They are presented in the cause of providing what is believed to be the most useful and readily description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention. The description, taken with the drawings, makes apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

Figure 1, also abbreviated as Fig. 1, schematically illustrates a sorption cooling system in accordance with the present invention.

Figure 2, also abbreviated as Fig. 2, schematically illustrates an example of a sorption unit in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be further described. In the following passages, different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

When describing the compounds of the invention, the terms used are to be construed in accordance with the following definitions, unless a context dictates otherwise.

The term "about" or "approximately" as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of +/-10% or less, preferably +/-5% or less, more preferably +/-1 % or less, and still more preferably +/-0,1 % or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. It is to be understood that the value to which the modifier "about" or "approximately" refers is itself also specifically, and preferably, disclosed.

As used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. By way of example, "a stream" means one stream or more than one stream.

Fig. 1 illustrates a sorption cooling system in accordance with the present invention. In particular, Fig. 1 illustrates a sorption cooling system for cooling a feed stream (102) comprising an evaporation unit (112) having a first inlet (116) adapted to receive the feed stream (102). As illustrated in Fig. 1, the feed stream (102) can be optionally firstly introduced into filtration means (109), so to remove from the feed stream (102) particles/agglomerates that could potentially cause clogging of the piping system of the system according to the present invention.

Therefore, in accordance with an embodiment of the present invention, the system further comprises filtration means (109). This provides for different kind of feed streams (102) to be cooled, such as feed streams (102) from various industrial processing which e.g. use water to cool warmer water streams result of water intensive processes, such as in the paper and pulp industry and the like.

In the context of the present invention, by means of the term "feed stream", reference is made to a supply of a liquid e.g. a water stream, an industrial slurry etc. to be processed by the system in accordance with the present invention.

In the context of the present invention, by means of the term "filtration means", reference is made to means for separating from a stream one or more components, e.g. agglomerates, debris, foreign objects..

In the context of the present invention, by means of the term "evaporation unit", reference is made to unit adapted to receive a feed stream (102) and providing a stream of water vapor (103) from said feed stream (102) by evaporation e.g. at room temperature, reduced temperature etc..., in other words, the evaporation unit is a unit wherein the evaporation of a liquid thereby contained cools said liquid.

In the context of the present invention, by means of the term "sorption unit", reference is made to a unit adapted to contain sorption means (100).

Further, the evaporation unit (112) of the sorption cooling system comprises a first outlet (117) adapted to exit a stream of water vapor (103) from said feed stream (102), which first outlet (117) allows water vapor (103) to be provided to the sorption unit (113). The stream of water vapor (103) is present due to the vapor pressure of the feed stream (102).

Therefore, the sorption unit (113) is connected to the evaporation unit (112), the sorption unit (113) has a second inlet (121) adapted to receive sorption means (100) to absorb water, a first outlet (120) adapted to exit consumed sorption means (101), and a first inlet (119) adapted to receive said stream of water vapor (103) from said feed stream (102).

In the context of the present invention, by means of the term "sorption means", or sorbent, reference is made to a substance or composition that is capable of sorption of a liquid or gas, e.g. water, water vapor.

In the context of the present invention, by means of the term "consumed sorption means" reference is made to sorption means (100) which uptake capacity of a liquid or gas has been reduced compared to their original state, so that they have to be replaced or regenerated with sorption means (100) with higher uptake capacity.

In the context of the present invention, by means of the term "inlet", reference is made to a means of entry for e.g. a fluid or gas to one or more parts of the system according to the present invention.

In the context of the present invention, by means of the term "outlet", reference is made to a means of exit for e.g. a fluid or gas to one or more parts of the system according to the present invention.

In accordance with an embodiment of the present invention, the sorption means (100) comprise an inorganic oxoacid and/or its salt and water. For example, suitable inorganic oxoacids have chemical formula of type FlmX0n, where X is an atom functioning as a central atom, whereas parameters m and n depend on the oxidation state of the element X, such as, but not limited to, H2SO4, H3PO4 In accordance with a further embodiment of the present invention, the sorption means (100) comprises polyphosphoric acid and/or highly concentrated phosphoric acid. In a further embodiment, the sorption means (100) has a mass percentage concentration of H3PO4 (PA/PPA) in the range from about 85 to 110 % wt, more preferably 95 to 105 % wt. The present polyphosphoric acid and/or highly concentrated phosphoric acid is provided to sorb the water vapor (103) evaporated from the feed stream (102).

In accordance with an embodiment of the present invention, the sorption unit (113) is at least partially comprising acid resistant material provided to be in contact with the sorption means (100), wherein said material is selected from: carbon impregnated graphite, phenol impregnated graphite, silicium carbide (SiC) stainless steel or corrosion resistance metal alloys alloy S28, alloy G30, alloy S30, alloy G35.

Further, to the first outlet (107) the evaporation unit (112) also comprises a second outlet (118) adapted to exit a cooled feed stream (104), which can e.g. be subsequently discharged into the environment or used for cooling of further machinery or be part of further subsequent industrial processes.

It has been found by the inventors that the present invention as described herein provides for improved sorption cooling system and reduced contamination of the feed stream (102) to be cooled, by e.g. having the sorption process at lower vapor pressure. Further, the present invention provides for increased cooling velocity and continuous operation and improved efficiency, allowing the feed stream to be at lower starting temperatures compared to existing cooling systems.

In accordance with an embodiment of the present invention, the sorption means (100) is provided at a temperature below 150 °C, preferably from about 50 up to 90°C. Possibly, the temperature should be kept as low as possible to absorb as much water from the feed stream (102) as possible due to the lower partial water vapor pressure of the sorption means compared to the partial vapor pressure of the water in the feed stream (102).

In accordance with an embodiment of the present invention, the sorption cooling system further comprises a first heat exchange element (107) provided to exchange heat with the sorption means (100). The temperature of the sorption means (100) can be provided to be regulated by means of said first heat exchange element (107) in contact with the sorption means (100). The first heat exchange element (107) can be for example provided with a heat exchange fluid, meaning e.g. a fluid suitable to transfer heat within a heat exchanger, adapted to cool or heat the heat exchange element (107) so to maintain the most appropriate temperature of the sorption means (100) contacted thereto, wherein a valve unit regulates inflow/outflow of the heat exchange fluid under controlled by a control unit coupled with a temperature device.

In the context of the present invention, by means of the term "heat exchange element" reference is made to a system capable of transferring heat between two entities, e.g. material and substance, water and air etc. In accordance with an embodiment of the present invention, the first heat exchange element (107) is adapted to maintain the temperature of the sorption means (100) below 150 °C, preferably from about 50 up to 90°C. The control of the temperature of the sorption means (100) is advantageous to keep the vapor pressure in the sorption unit (113) at lower pressure than in the evaporation unit (112) to create a positive driving force to process the water vapour (103) from the evaporation unit (112) to the sorption unit (113). The exact temperature of the sorption means (100) depends on the water vapor temperature from the feed stream (102). The higher this temperature, the higher the temperature of the sorption means (100) entering the sorption unit (113) must be to maintain a lower vapor pressure in the sorption unit when compared to the vapor pressure in the evaporation unit. In case the sorption means (100) entering the sorption unit (113) is at a high temperature, such as for example a temperature of around 230°C, it has been found that the first heat exchange element (107) must cool down the sorption process to decrease the vapor pressure of the sorption means (100) to a value below the vapor pressure in the evaporation unit (112). In this way, the temperature of the consumed sorption means (101) has to be regulated in light of getting the correct water content of said sorption means (100) and the composition of said sorption means (100) to enable absorption. It has been found that by keeping the temperature of the sorption means (100) below 150 °C, preferably from about 50 up to 90°C, the temperature of the consumed sorption means (101) can be kept below 230°C, and the sorption cooling system is more energy efficient. Further, a temperature of the consumed sorption means below 230°C allows for the best balance between cooling efficiency and energy consumption.

The first heat exchange element (107) can be a tower with packing, plates, and a heat exchange element with plates which can be incorporated in the tower but can also be heat exchanger tubes incorporated in said tower. The presence of a first heats exchange element (107) allows to control the desorption temperature of the sorption means (100).

More specifically, in accordance with a further embodiment of the present invention, the sorption cooling system comprises a temperature device adapted to measure a temperature of the sorption means (100), and a control unit adapted to regulate the temperature of the sorption means (100) based on the measured temperature.

In the context of the present invention, by means of the term "temperature device" reference is made to a device provided with a temperature sensor which measures the temperature.

In the context of the present invention, by means of the term "control unit", or processing unit, reference is made to a unit suitable for carrying out logical and arithmetical operations on data as specified in instructions provided to said control e.g. a CPU.

In accordance with a further embodiment of the present invention, the sorption cooling system a valve unit adapted to regulate an inflow of a heat transfer fluid, e.g. a heat exchange fluid inside the first heat exchange element (107) and or the second heat exchange element (111) in response to the control unit In the context of the present invention, by means of the term "valve unit" reference is made to a unit comprising means for controlling the flow of a liquid or a gas through a conduct or the like.

Coupled with the temperature device and the control unit, the valve unit can provide for the opening and closure of incoming streams and outcoming streams to and from the various parts of the system of the present invention.

In accordance with yet a further embodiment of the present invention, the sorption cooling system according further comprises reduced pressure providing means (105) which are preferably connected to the evaporation unit (112) and/or the sorption unit (113).

In the context of the present invention, by means of the term "reduced pressure providing means" reference is made to means adapted to reduce the pressure exerted onto the surface of said feed stream (102).

In accordance with the implementation of the present invention illustrated in Fig.1, it is evident that the reduced pressure providing means (105) are preferably connected in between the evaporation unit (112) and the sorption unit (113). Nevertheless, the reduced pressure providing means (105) can either be provided in connection to the evaporation unit (112), or the sorption unit (113) or both. In accordance with how the various components of the system are displaced, the reduced pressure providing means (105) can be provided elsewhere. The reduced pressure providing means (105) can be a vacuum pump for start-up reasons or to remove inert gases from the feed stream (102).

Under reduced pressure the water vapor (103) is evaporated from said feed stream (102) into the sorption unit (113). Independent of the presence of the reduced pressure providing means (105), the sorption means in the sorption unit (113) has a lower water vapor pressure as the water present in and at the temperature of the feed stream (102) and therefor this lower vapor pressure of the sorption means (100) in the sorption unit (113) forces the water to evaporate in unit (112) before being processed towards (113).

Evidently, in the circumstance in which reduced pressure providing means (105) are used, the various parts of the systems affected by the reduced pressure are adapted to be vacuum resistant, for example, they can be vacuum resistant recipients adapted to contain said feed stream (102) or part of it, and allow for reduced pressure to be achieved without leaks. By reducing the pressure inside the system, there is less gaseous pressure on the surface of the feed stream (102), keeping the molecules from evaporating. In such way, evaporation takes place at a faster rate. The evaporation allows cooling of the feed stream (102), thereby forming a cooled stream. As mentioned above, in the instant cooling system, this evaporation is enhanced by absorbing, i.e. complete absorption, the water vapor (103) in sorption unit (113) by contacting said water vapor (103) with sorption means (100) inside said sorption unit (113).

In accordance with yet another embodiment of the present invention, the sorption cooling system further comprises reduced pressure providing means (105) connected to the evaporation unit (112) and/or the sorption unit (113).

In accordance with a further embodiment of the present invention, the sorption cooling system further comprises regeneration means (106), which can comprise a second heat exchange element (111) providing heat to the consumed sorption means (101), thereby forming sorption means (100). In accordance with the present invention, comprising the regeneration means (106) are adapted to regenerate consumed sorption means (101), and feed such regenerated sorption means (100) into the sorption unit (113).

In the context of the present invention, by means of the term "regeneration means" reference is made to means adapted to provide a substance or composition anew, or in a physical and/or chemical state allowing said substance to retain its original functionality or part of it. In the context of the present invention, regeneration means (106) regenerate sorption means (100) so to provide from sorption means (100) not possessing sorption properties, sorption means (100) having their original sorption properties.

As illustrated in Fig. 1, consumed sorption means (101) leaving the sorption unit (113) are moved to regeneration means (106), wherein in accordance with an embodiment of the present invention, a second heat exchange element (111) resides, which is adapted to heat the consumed sorption means (101), thereby forming sorption means (100) anew. Wherein the sorption means (100) are polyphosphoric acid and/or highly concentrated phosphoric acid, the heat provided to the diluted phosphoric acid obtained after sorption, allows for evaporation of water, thereby forming water vapor (103) from said diluted phosphoric acid, and forming back polyphosphoric acid and/or highly concentrated phosphoric acid, which can be utilized further as sorbent in the system described herein. Therefore, in accordance with an embodiment of the present invention, a second heat exchange element (111) is provided to exchange heat with the consumed sorption means (101) to be regenerated. Further, as evident from Fig. 1, regenerated sorption means (100) are further brought to the sorption unit (113) to provide for sorption of water vapor (103) from said feed stream (102).

In yet another embodiment of the present invention the regeneration means (106) further comprises an economiser (108) providing said sorption means (100) in counterflow with consumed sorption means (101). For example, the economiser (108) can allow for heat exchange between regenerated sorption means (100) leaving the regeneration means (106) at a higher temperature and consumed sorption means (101) leaving the sorption unit (113) at a lower temperature.

In the context of the present invention, by means of the term "economiser" reference is made to a device intended to reduce energy consumption e.g. by exchanging heat and pre-heating a fluid.

In accordance with a further embodiment of the present invention, the sorption unit (113) comprises a mixing unit (114), adapted to mix the water vapor 103) entering the sorption unit (113) with the sorption means (100); and a sorption unit base (115), adapted to collect the consumed sorption means (101).

In the context of the present invention, by means of the term "mixing unit" reference is made to a unit capable of increasing the surface contact between two entities e.g. two liquids, one liquid and a solid etc. The increase in active contact surface between water vapor and sorption means can also be achieved by spraying the sorption means, so to have droplets of sorption means. This can be accomplished by means e.g. of a nozzle.

Fig. 2 illustrates a sorption unit (113) comprising a mixing unit (114), at the top, and a sorption unit base (115) at the bottom of the sorption unit (113). In contact with the sorption unit (113), a first heat exchange element (107) is provided to exchange heat with the sorption means (100), so to reduce or increase the temperature of the sorption means (100) if needed. In accordance with the sorption unit (113) illustrated in Fig. 2, the sorption means (100) are introduced from the top of the sorption unit (113), at the location of the mixing unit (114), here, nozzles or other means allow for the mixing of the sorption means (100) with the stream of water vapor (103). In such way, the sorption means (100) can better sorb water from said water vapor (103), thereby forming consumed sorption means (101). Further, consumed sorption means (101) fall to the base of the sorption unit (115), where water vapor (103) is introduced from the connected evaporation unit (112), from the first inlet (119).

In accordance with Fig. 2, the sorption units (113) that can be used in the context of the present invention can be for example an open packed bed reactor, wherein the mixing unit (114) is represented by a nozzle or other apparatus that allows for the sorption means (100) to better enter into contact with the stream of water vapor (103). In this sorption unit (113), the water present in the stream of water vapor (103) is retained by the sorption means (100). In case the sorption means (100) are polyphosphoric acid and/or highly concentrated phosphoric acid, said sorption means (100) get enriched with water until they do not function anymore as a sorbent and have to be replaced. A stream of water vapor (103) can be provided to the sorption unit (113) from any location allowing for the sorption of water to take place, preferentially from the sorption unit base (115), wherein said stream of water vapor (103) is provided to enter a first inlet (119) of the sorption unit (113). Sorption means (100) enters the mixing unit (114) through a second inlet (121) of the sorption unit (113), either from an economiser (108), a regeneration means (106) and/or from an external stream of sorption means (100). After entering the mixing unit (114), the sorption means (100) are closely contacted inside the sorption unit (113) with water vapor (103). A packed bed inside the sorption unit (113) allows for sufficient contacting of the stream of water vapor (103) with said sorption means (100), which fall to the sorption unit base (115) by means of gravity. At the time the sorption means (100) is collected to the sorption unit base (115), the sorption means (100) is diluted by the water absorbed, meaning that consumed sorption means (101) are formed and collected at said sorption unit base (115). Therefore, consumed sorption means (101) after having retained water, is collected in the lower portion of the bed reactor, where said means are for example pumped out of the sorption unit (113) from the first outlet (120) of the sorption unit (113) to be disposed or regenerated.

In the context of the present invention, by means of the term "sorption unit base" or base of the sorption unit (115), reference is made to a lower portion of the sorption unit (113), wherein liquids and/or solids tend to collect by means of gravitational forces. In other words, reference is made to the bottom of the sorption unit (113).

In the context of the present invention, by means of the term "sorption unit top" or top of the sorption unit (110), reference is made to an upper portion of the sorption unit (113), wherein regenerated or fresh sorption means (100) are introduced inside said sorption unit (113). Preferably, the mixing unit (114) is located at the position of said sorption unit top (110).

At the base of the sorption unit (115), consumed sorption means (101) are collected and conveyed to further the either an economiser (108), which is then connected to regeneration means (106).

In a further aspect, the present invention relates to the use of a sorption cooling system as defined in any of the embodiment of the present invention for cooling a feed stream (102). In accordance with an embodiment of the present invention, the feed stream (102) is wastewater. In accordance with a further embodiment of the present invention, the feed stream (102) is a slurry. As mentioned herein before, one of the benefits of the sorption cooling system of the present invention is that it can be performed on feed streams at lower temperatures, but still above allowed discharge temperatures of waste streams. Hence in yet a further embodiment, the feed stream is at a temperature from about 0 to 100°C, preferably 0 to 60°C. It has been found that a feed stream temperature from about 0 to 100°C, preferably 0 to 60°C is advantageous to achieve a better cooling effect.

In a further aspect, the present invention relates to a method of cooling a feed stream (102) in accordance with the sorption cooling system described herein, the method comprising the steps of: (a) providing a feed stream (102) to an evaporation unit (112); (b) providing sorption means (100) to a sorption unit (113); (c) evaporating a stream of water vapor (103) from said feed stream (102) by means of the evaporation unit (112); (d) feeding said stream of water vapor (103) into the sorption unit (113).

(e) contacting said stream of water vapor (103) with the sorption means (100) to absorb water from said stream of water vapor (103), thereby forming consumed sorption means (101), and (f) leaving said feed stream (102) from the evaporation unit (112) as cooled feed stream (104). The feed stream (102) is cooled through the evaporation of the water vapor (103) from said feed stream (102), which is enhanced in the sorption cooling system as herein provided through the absorption of the water vapor (103) into to the sorption unit (113). Coupling the evaporation unit (112) with a sorption unit (113) lowers the vapor pressure above the feed stream (102), allowing more moisture to evaporate from said feed stream (102), resulting in increased cooling.

In accordance with an embodiment of the present invention, at step (b) the sorption means (100) is provided to the sorption unit (113) at a temperature below 150 °C, preferably from about 50 up to 90°C.

In accordance with a further embodiment of the present invention, the sorption means (100) comprise polyphosphoric acid and/or highly concentrated phosphoric acid.

In accordance with a further embodiment of the present invention, the concentration of polyphosphoric acid and/or highly concentrated phosphoric acid has a mass percentage concentration of H3PO4 (PA/PPA) in the range from about 85 to 110% wt, more preferably 95 to 105 % wt.

In accordance with yet another embodiment of the present invention, at step (c) the evaporation of the stream of water vapor (103) is at least partially provided by applying a reduced pressure to the feed stream (102) by means of reduced pressure providing means (105).

In accordance with a further embodiment of the present invention, at step (c) the evaporation of the stream of water vapor (103) is provided at a pressure from about 20 to 1000 mbara, more preferably from about 30 to 500 mbara.

In accordance with a further embodiment of the present invention, the method further comprises the step of: (g) regenerating sorption means (100) from consumed sorption means (101) by means of a regeneration means (106).

In accordance with the present invention, comprising the regeneration means (106) are adapted to regenerate consumed sorption means (101), and feed such regenerated sorption means (100) into the sorption unit (113).

In accordance with a further embodiment of the present invention, at step (g), the consumed sorption means (101) is pre-heated by means of sorption means (100) leaving the regeneration means (106) at higher temperature.

In accordance with yet another embodiment of the present invention, the sorption means (100) are regenerated from consumed sorption means (101) by heating the sorption means (100) at a temperature from about 80°C to 230 °C, preferably from about 160°C to 200°C.

Example:

In an experimental setup, 100kg/h wastewater at 43°C were fed to a sorption cooling system in accordance with the present invention -simulating summer conditions of industrial wastewater: The wastewater was evaporated in the evaporation unit (112) at 80mbara and processed to the sorption unit (113).

Sorption temperature, meaning the temperature of the sorption means (100), prior to being contacted with the stream of water vapor (103) in the sorption unit (113) was kept at 70-75°C by means of the first heat exchange element (107). Sorption means (100), in this case (poly)phosphoric acid, entered at 70°C and left at 75°C.

The consumed sorption means (101) was regenerated at 180°C. The initial concentration of sorption the sorption means (100) was between 95 and 100%.

Wastewater left the sorption cooling system at 41,5°C, as cooled feed stream (104). The water stream (103) obtained from the regeneration of the consumed sorption means (101) was at 70°C whereas the regenerator heat input used to heat the consumed sorption means (101) and regenerate it was around 100 kg/h 8 barg at 190°C.

In this experimental setup it was proven wastewater can be cooled from 43°C to 41°C with steam of 180°C at 8 barg by using sorption means (100). The fouling problem of the cooling of wastewater was avoided by using the evaporative cooling in an evaporator driven by absorption in (poly)phosphoric acid. This or similar setup can be applied in many industrial processes with highly contaminated/ loaded water streams in combination with plants where low temperature heat sinks are supplied by 8-10 barg steam. Typical applications are food plants and bio(chemical)plants.

Legend sorption means 101 consumed sorption means 102 feed stream 103 water vapor 104 cooled feed stream reduced pressure providing means 106 regeneration means 107 first heat exchange element 108 economiser 109 filtration means top of the sorption unit (113), or sorption unit top 111 second heat exchange element 112 evaporation unit 113 sorption unit 114 mixing unit base of the sorption unit (113), or sorption unit base 116 first inlet of the evaporation unit (112) 117 first outlet of the evaporation unit (112) 118 second outlet of the evaporation unit (112) 119 first inlet of the sorption unit (113) first outlet of the sorption unit (113) 121 second inlet of the sorption unit (113)

Claims

CLAIMSA sorption cooling system for cooling a feed stream (102) comprising: an evaporation unit (112) having a first inlet (116) adapted to receive the feed stream (102), a first outlet (117) adapted to exit a stream of water vapor (103) from said feed stream (102); and a sorption unit (113) connected to the evaporation unit (112), the sorption unit (113) has; o a first inlet (119) adapted to receive said stream of water vapor (103) from the first outlet (117) of the evaporation unit (112); a a second inlet (121) adapted to receive sorption means (100) to absorb water from said stream of water vapor (103), thereby forming consumed sorption means (101); a a first outlet (120) adapted to exit consumed sorption means (101); and wherein the evaporation unit (112) further comprises a second outlet (118) adapted to exit a cooled feed stream (104).
2. The sorption cooling system according to the previous claim, wherein the sorption means (100) is provided at a temperature below 150 °C, preferably from about 50°C up to 90°C.
3. The sorption cooling system according to any of claims 1 to 2, wherein the sorption means (100) comprises polyphosphoric acid and/or highly concentrated phosphoric acid.
4. The sorption cooling system according to any of claims 1 to 3, further comprising a first heat exchange element (107) provided to exchange heat with the sorption means (100).
5. The sorption cooling system according to any one of claims 1 to 4, further comprising reduced pressure providing means (105) connected to the evaporation unit (112) and/or the sorption unit (113)
6. The sorption cooling system according to any one of claims 1 to 5, wherein said sorption means (100) has a mass percentage concentration of polyphosphoric acid and/or highly concentrated phosphoric acid (PA/PPA) in the range from about 85 to 110%, more preferably 95 to 105 %.
7. The sorption cooling system according to any one of claims 1 to 6, further comprising reduced pressure providing means (105) connected to the evaporation unit (112) and/or the sorption unit (113), wherein preferably the reduced pressure providing means (105) is a vacuum pump.
8. The sorption cooling system according to any of claims 1 to 7, further comprising regeneration means (106), which are adapted to regenerate consumed sorption means (101), and feed such regenerated sorption means (100) into the sorption unit (113).
9. The sorption cooling system according to claim 8, the regeneration means (106) comprising: -a second heat exchange element (111) providing heat to the consumed sorption means (101), thereby forming sorption means (100).
10. The sorption cooling system according to claims 8 to 9, the regeneration means (106) further comprising: - an economiser (108) providing said sorption means (100) in counterflow with consumed sorption means (101).
11. The sorption cooling system according to any one of claims 1 to 10, wherein the sorption unit (113) comprises: - a mixing unit (114), adapted to mix the water vapor (103) entering the sorption unit (113) with the sorption means (100); - a sorption unit top (110), adapted to distribute the regenerated or fresh sorption means (100); - a sorption unit base (115), adapted to collect the consumed sorption means (101).
12. Use of a sorption cooling system as defined in any of claims Ito 11, for cooling a feed stream (102).
13. The use of a cooling system as defined in claim 12, wherein the feed stream (102) is wastewater.
14. The use of a cooling system as defined in claims 12 to 13, wherein the feed stream (102) is at a temperature from about 0°C to 100°C, preferably 0°C to 60°C.
15. The use of a cooling system as defined in claim 12 to 14, wherein the feed stream (102) is a slurry.
16. A method of cooling a feed stream (102) in accordance with the sorption cooling system described in claims 1 to 11, the method comprising the steps of: (a) providing a feed stream (102) to an evaporation unit (112); (b) providing sorption means (100) to a sorption unit (113); (c) evaporating a stream of water vapor (103) from said feed stream (102) by means of the evaporation unit (112); (d) feeding said stream of water vapor (103) into the sorption unit (113).(e) contacting said stream of water vapor (103) with the sorption means (100) to absorb water from said stream of water vapor (103), thereby forming consumed sorption means (101), and (f) leaving said feed stream (102) from the evaporation unit (112) as cooled feed stream (104).
17. The method of cooling a feed stream (102) according to claim 16, wherein at step (b) the sorption means (100) is provided to the sorption unit (113) at a temperature below 150 °C, preferably from about 50°C up to 90°C.
18. The method of cooling a feed stream (102) according to claims 16 to 17, wherein the sorption means (100) comprise polyphosphoric acid and/or highly concentrated phosphoric acid.
19. The method of cooling a feed stream (102) according to claim 18, wherein the concentration of polyphosphoric acid and/or highly concentrated phosphoric acid (PA/PPA) in the range from about 85 to 110 % wt, more preferably 95 to 105% wt.
20. The method of cooling a feed stream (102) according to any one of claims 16 to 20, wherein at step (c) the evaporation of the stream of water vapor (103) is provided at a pressure from about 20 to 1000 mbara, more preferably from about 30 to 500 mbara.
21. The method of cooling a feed stream (102) according to claim 16 to 20, further comprising the step of: (g) regenerating sorption means (100) from consumed sorption means (101) by means of regeneration means (106)
22. The method of cooling a feed stream (102) according to claim 21, wherein sorption means (100) are regenerated from consumed sorption means (101) by heating the sorption means (101) at a temperature from about 80°C to 230 °C, preferably from about 160°C to 200 °C.
23. The method of cooling a feed stream (102) according to claims 21 to 22, wherein at step (g), the consumed sorption means (101) are pre-heated by means of sorption means (100) leaving the regeneration means (106) at higher temperature.