An absorption heat exchange and thermal storage plant

Abstract

The present invention relates to an absorption heat exchange and thermal storage plant which includes separate chambers for storage of liquids for thermal storage and further comprises an evaporator unit for cooling an exterior medium that is to be cooled; an absorber unit, wherein the water vapor deriving from an evaporator unit is absorbed in a concentrated salt solution releasing heat; a generator unit, wherein a diluted salt solution is concentrated by energy absorbing evaporation; a condenser, wherein vapor from the generator unit is cooled to form water in liquid form; wherein a nozzle placed inside the condenser discharges droplets of cooled liquid water into the vapor, such that the vapor is cooled and condensed by droplets of cooled liquid water from the nozzle.

Description

Technical Field

[0001] The present invention relates absorption heat exchange systems capable of storing varying quantities of thermal energy.Background

[0002] Conventionally, absorption cooling plants have been used as equipment for the provision of cooling, e.g., in the form of cooled water, where a cooling plant utilizes an absorption refrigeration cycle using e.g. an aqueous lithium bromide solution as an absorbent.

[0003] This is based in the fact that the water vapor pressure above concentrated water-salt solutions of, for example, calcium chloride, lithium chloride or lithium bromide or the like and / or mixtures thereof is lower than that of pure water at a corresponding temperature, and that these solutions can therefore be used as water-absorption liquids.

[0004] Basically, the cooling equipment consists of an evaporator in which a refrigerant, e.g. water, is evaporated; an absorber, which absorbs the vaporized refrigerant into an aqueous salt solution that is an absorption liquid; a regenerator for heating and regenerating the aqueous solution salt that has absorbed the refrigerant vapor; and a condenser for condensing the water vapor regenerated in the regenerator. Water at a temperature of, for example, 12° C. is introduced as a fluid to be cooled in a heat exchanger and is cooled to, for example, 7° C. by the latent heat of vaporization of water, which is a refrigerant liquid, and thus cold water is supplied to the user facility.

[0005] Lithium bromide absorption refrigeration technology relates to using lithium bromide aqueous solutions at different temperatures to absorb and release water vapor to implement refrigeration using an external heat source for implementing refrigeration.

[0006] Lithium bromide absorption plants are widely used for air conditioning purposes, where waste heat is available due to the achievable temperature ranges, limited toxicity, and high electrical efficiencies. There are several challenges, however, especially in using LiBr in environments with dynamic movements, such as onboard ships, where concerns of crystallization may render plants unusable. It has also been identified that availability of waste heat and need for cooling often coincide with the need for thermal storage at varying temperatures. As such, a high efficiency system capable of exchanging and temporarily storing thermal energy at different temperatures is needed.Disclosure of the Invention

[0007] An aspect of the present invention is to provide an absorption heat exchange and thermal storage plant with improved efficiency.

[0008] An aspect of the present invention is to provide a (high efficiency) scalable absorption heat transfer and storage system.

[0009] It is also an aspect to provide a system according to above that can be used in environments subject to dynamic movements, e.g. onboard ships.

[0010] The absorption plant according to the invention can be used for cooling and / or heating and / or thermal storage purposes in industrial and marine facilities.

[0011] Accordingly, the present invention relates to an absorption heat exchange and thermal storage plant comprising an evaporator unit, wherein water in liquid form is evaporated to form water vapor thereby extracting heat from an exterior medium that is to be cooled, and an absorber unit, wherein the water vapor deriving from an evaporator unit is absorbed in a concentrated salt solution releasing heat. Moreover, the absorption cooling plant comprises a generator unit, wherein a diluted salt solution is concentrated by energy absorbing evaporation, and a condenser, wherein vapor from the generator unit is cooled to form water in liquid form. One or more nozzles are placed inside the condenser and discharge droplets of cooled liquid water into the vapor, such that the vapor is cooled and condensed in the condenser by droplets of cooled liquid water from the one or more nozzles.

[0012] By using droplets of water for condensing vapor, a large space-consuming plate heat exchanger can be omitted which can facilitate the installation of the plant, both in industrial and marine facilities.

[0013] The absorption heat exchange and thermal storage plant according to the invention utilizes salt solutions for absorption of water, and in embodiments the salt in the salt solution is selected from a water absorbing salt such as calcium chloride, lithium chloride, lithium chlorate, zinc chloride, zinc bromide, or lithium bromide or mixtures thereof.

[0014] In an embodiment of the absorption heat exchange and thermal storage plant, the cooled liquid water discharged from the nozzles into the condenser is cooled in a heat exchanger, and preferably the water entering the heat exchanger is condensed water from the condenser. Preferably, the heat exchanger is a liquid / liquid cooling exchanger and may be a plate heat exchanger which, as it is liquid / liquid cooling, requires a far smaller plate heat exchanger than with vapor / vapor or vapor / liquid cooling.

[0015] Thus, in an embodiment of the absorption heat exchange and thermal storage plant, the cooled liquid water discharged into the condenser is recycled water from the condenser. In this manner, a part of the condensed water can be re-used to condense vapor in the condenser after being cooled in the heat exchanger, and part of the condensed water is led to the evaporator to participate in the cooling process.

[0016] In an embodiment, the vapor is condensed in the condenser to form liquid water, and the liquid water is collected at the lower part of the condenser and led to a separate chamber for temporary storage. By collecting and storing the liquid water in a separate chamber in the bottom, the challenges imposed by environments with dynamic movements are minimized, as the horizontal surface of the water can be minimized, thus ensuring that water is available for the suction side of the pump. The storing of water in a separate chamber also enables dimensioning of the plant to varying thermal storage capacities.

[0017] The absorption heat exchange and thermal storage plant according to the invention is operated at very low pressures, whereby the condensation and boiling points of liquids are proportionally low, and in an embodiment the droplets of water are subcooled to about 14-40 degree Celsius while the pressure is about 40-100 mbara.

[0018] In an embodiment of the absorption heat exchange and thermal storage plant, at least one of the evaporator unit, absorber unit, generator unit and condenser unit is connected to a chamber, where said chamber collects and stores liquid from the unit temporarily. In this manner, the chamber may serve as thermal storage.

[0019] In an embodiment of the absorption heat exchange and thermal storage plant, the exterior medium to be cooled or heated comprises two or more fluids, where each fluid may have inlet and outlet temperatures different from the other fluids. The fluids may be in liquid or gaseous form and may optionally change material state during the process in the plant.

[0020] The absorption heat exchange and thermal storage plant also provides an embodiment, where the fluids are cooled by the evaporator unit and / or the generator unit, and each fluid has a temperature differing from the other fluid(s) when entering the plant, and the fluid is cooled to a different temperature. Thus, the invention also provides an option to cool or heat two different fluids, such that two different cooling temperatures may be achieved concurrently.

[0021] In the absorption heat exchange and thermal storage plant, each of the fluids is cooled by the generator unit and / or the evaporator unit such that each fluid may be cooled to a desired temperature. Thereby, it is possible to cool two different fluids to desired temperatures such that the fluids can be used in processes in other plants.

[0022] In an embodiment of the absorption heat exchange and thermal storage plant, wherein the exterior medium to be cooled comprises two or more fluids, and where each fluid enters the cooling plant with a temperature different from the other fluid(s). Thus, the plant according to the invention may be used to cool fluids from two different processes, and where the fluids enter the absorption cooling plant with two different temperatures. In an example, the hottest fluid may e.g. enter the absorption cooling plant with a temperature at about 80 degrees, and the colder fluid may enter the absorption cooling plant with a temperature at about 16 degrees.

[0023] The absorption heat exchange and thermal storage plant also provides an embodiment, where one or more fluids are heated in the condenser unit and / or absorber unit, and where each medium has a temperature differing from the other medium when entering the plant, and where the medium(s) are heated to different temperature(s). Thus, the invention also provides an option to heat two different fluids, such that two different heating temperatures may be achieved.

[0024] In the absorption heat exchange and thermal storage plant, each of the fluids is heated by the condenser unit and / or absorber unit such that each fluid is heated to a desired temperature. Thereby, it is possible to heat two different fluids to desired temperatures, such that the fluids can be used in processes in other plants.

[0025] In an embodiment of the absorption heat exchange and thermal storage plant, wherein the exterior medium to be heated comprises two or more fluids, and where each fluid enters the plant with a temperature different from the other medium(s), the plant according to the invention may be used to heat mediums from two different processes, and where the mediums enter the absorption cooling plant with two different temperatures. In an example, the coldest medium to be heated may enter the absorption cooling plant with a temperature at about 10 degrees, and the warmer medium to be heated may enter the plant with a temperature at about 60 degrees.

[0026] In the absorption heat exchange and thermal storage plant, the fluids with different temperatures are cooled by the evaporator unit and / or the generator unit, where each fluid has a different temperature when entering the absorption cooling plant and is cooled to a different temperature when leaving the absorption heat exchange and thermal storage plant. Preferably, the hottest fluid is cooled by generator unit, e.g. from about 80 degrees to about 75 degrees, and the colder fluid is preferably cooled by the evaporator, e.g. from about 16 degrees to about 10 degrees.

[0027] In an embodiment of the absorption heat exchange and thermal storage plant, each of the fluids to be cooled is cooled by the evaporator unit and / or the generator unit, such that each fluid is cooled to a desired temperature. By adjusting the flow of the fluids to be cooled through cooling loops, it is possible for the plant to control the temperature to which the fluid is cooled.

[0028] In an aspect, the present invention relates to a system for absorption heat exchange, and where the system comprises an evaporator unit, wherein water in liquid form is evaporated to form water vapor thereby extracting heat from an exterior medium that is to be cooled, and an absorber unit, wherein the water vapor deriving from an evaporator unit is absorbed in a concentrated salt solution releasing heat.

[0029] The system also includes a generator unit, wherein a diluted salt solution is concentrated by energy absorbing evaporation, and a condenser unit, wherein vapor from the generator unit is cooled to form water in liquid form.

[0030] In the system, at least one of the evaporator unit, absorber unit, generator unit and condenser unit is connected to a chamber separate from the unit, where said chamber collects and stores liquid from the unit temporarily. By collecting liquid in separate chambers, it is possible to optimize the dimensions of the plant, and in case the plant is used in marine installations, it is easier to control the motion of the liquids, when the installation is exposed to strong dynamic movement.

[0031] In an embodiment of the system, the liquid collected in a chamber from a unit can be recycled into the unit or distributed to neighbouring units. In this manner, collected liquid e.g. water can be re-used in the unit from which it is collected or be distributed to another unit for use in this unit.

[0032] The use of separate chambers for liquid in the system may facilitate the dimensioning of the plant, e.g. it may be possible to produce the plant in smaller size, and in an embodiment of the system the chambers connected to different units have the same or different sizes.

[0033] For the purpose of further improving the use of the system, one or more of the separate chambers may have a size which can be varied. Thus, the thermal storage capacity of the plant may be scalable by varying the sizes of the chambers in different system models.Brief Description of the Drawing(s)

[0034] The invention is explained in detail below with reference to the drawing(s), in which Fig. 1 shows principles of the invention; Fig. 2 shows a plant with separate chambers; Fig. 3 shows a plant according to the invention with combined parts.

[0035] The figures are only intended to show the principles of the invention, and details, which do not form part of the invention, may be omitted. The same reference numbers are used for the same parts.Detailed description of the Invention

[0036] Figure 1 illustrates a plant according to the invention. The plant includes an evaporator 1, in which a first fluid enters the evaporator 1 via a coil 5 for being cooled by the liquid evaporating in the evaporator 1, and thus the first fluid leaves the evaporator 1 via the coil 5 in a cooler state than it enters. In this embodiment, the liquid is water, and when the water evaporates and turns into vapor, it absorbs heat from the first fluid in the coil 5, thereby cooling the first fluid in the coil 5. The pressure in the evaporator may be lowered such that the boiling point of the water becomes lower.

[0037] The vapor evaporated in the evaporator 1 is led to an absorber 2 via connection 6. In the absorber 2, the vapor is absorbed in a mixture of liquid and salt. In this embodiment, the liquid is water, and the salt is LiBr which is known to absorb water and vapor very well. Thus, the vapor from the evaporator is absorbed in a mixture of water and LiBr in the absorber 2 and becomes part of the liquid water / LiBr solution.

[0038] From the absorber 2, the solution of water / LiBr is led to the generator 3, where the solution is concentrated by removing water from the solution. The solution is led from the absorber 2 to the generator 3 by means of connection 7. In the generator 3, the solution is concentrated in respect of LiBr by applying heat which will cause the water to evaporate, thereby concentrating the solution.

[0039] The heat may be applied to the generator 3 via the coil 9 by which a second fluid can apply heat to the generator 3 and cause water in the solution to evaporate into vapor. By means of tube 8, the concentrated solution collected in the bottom part of the generator is recycled to the absorber 2 to help absorb more water.

[0040] The vapor formed in the generator 3 is led to the condenser 4 by means of connection 10. In the condenser 4, the vapor is condensed by droplets of cooled water discharged from a nozzle 11 placed in the upper part of the condenser 4 which discharges droplets of cooled liquid water into the vapor, such that the vapor is cooled and condensed on droplets of cooled liquid water after which the condensed water is collected in the bottom part of the condenser 4. A part of the condensed water is taken out from the bottom part of the condenser 4 and led to a heat exchanger 13 by tube 12. In the heat exchanger 13, the water is further cooled before it is transported to the nozzle 11 by means of tube 14 and discharged into the vapor in the condenser 4.

[0041] The use of cooled water droplets for the condensation process is an advantage in particular in respect of space, as the condenser 4 can be dimensioned in smaller size than the traditional condensers using plates or tubes for condensing.

[0042] Another part of the condensed water in the bottom part of the condenser 4 is led to the evaporator 1 via connection 15 for another cycle in the evaporator 1, absorber 2, generator 3, and condenser 4.

[0043] The water in the evaporator 3 and the condenser 4 may serve as thermal storage. The water / LiBr solution in the absorber and in the generator may also serve as thermal storage.

[0044] The coils 5, 9 shown in the evaporator 1 and the generator 3 are only illustrative examples and can be replaced with other means such as tubes or plates.

[0045] The plant may also comprise not shown control means, such as e.g. control valves and one-way valves mounted e.g. in the connections 6, 7, 10 and 15, and in the tubes 8, 12 and 14.

[0046] Figure 2 is an illustration of a similar absorption heat exchange and thermal storage plant comprising an evaporator 1 connected to an absorber 2, which is connected to a generator 3. The generator 3 is connected to a condenser which is connected to the evaporator 1 completing the cycle.

[0047] In the plant illustrated in figure 2, the absorber 2 and the evaporator 1 each comprises a separate chamber 16, 17. The chamber 16 may collect and store concentrated water / LiBr solution which is collected in the absorber 2, and from the chamber 16 the concentrated water / LiBr solution can be transported to the generator 3 by means of tube 7.

[0048] The chamber 17 may collect and store water from the condenser 4. Water is transported from the condenser 4 to the evaporator 1 by means of tube 15. From the evaporator 1, water can be transported to the absorber 2 by means of tube 6.

[0049] Figure 3 shows an embodiment of an absorption heat exchange and thermal storage plant according to the invention. The plant comprises two vessels 21 and 22. Each vessel 21 and 22 is divided into two sections, and the dotted lines indicate where the sections are divided.

[0050] The vessel 21 comprises the condenser 24 and the generator 25. The vessel 22 includes the evaporator 28 and the absorber 29. The vessel 21 and 22 each includes two separate chambers. The chambers 26 and 27 are placed on vessel 21, and chambers 30 and 31 are placed on vessel 22. The chambers can be used for storing liquid e.g. for thermal storage of heated liquid. The collecting of fluid in separate chambers placed below the process vessel mitigates challenges imposed by plants placed in environments with dynamic movements, e.g. onboard ships.

[0051] The chambers 26 and 27 each runs along the length of the vessel 21, and chamber 26 is connected to the condenser 24, and the chamber 27 is connected to the generator 25.

[0052] In a similar manner, the chambers 30 and 31 each runs along the length of the vessel 22, and chamber 30 is connected to the evaporator 28, and the chamber 31 is connected to the absorber 29.

[0053] The size and volume of the vessels 21 and 22 may vary depending on the specific use of the plant, and in the vessel 21 the condenser 24 and the generator 25 may e.g. have different sizes and occupy different volumes in the vessel. Also, the evaporator 28 and the absorber 29 may occupy different volumes in the vessel 22.

[0054] The chambers 26 and 27 connected to the vessel 21 and the chambers 30 and 31 connected to the vessel 22 may have different sizes and volumes according to the desired thermal storage capacity of the specific model / design.

[0055] The plant also comprises a control unit 23 for controlling the flow and the processes in the plant. Moreover, the plant also includes not visible pipes and valves and other devices necessary for running the plant.

[0056] The design of the plant as illustrated in figure 3 can be adapted for several industrial and marine applications as the size and volume of the different parts in the plant can easily be adapted to a specific application. The easy scalability of thermal storage capacity provides a functionality of constant cooling or heating effect, hitherto unseen in absorption plants.

Claims

1. An absorption heat exchange and thermal storage plant comprising a. an evaporator unit, wherein water in liquid form is evaporated to form water vapor thereby extracting heat from an exterior medium that is to be cooled; b. an absorber unit, wherein the water vapor deriving from an evaporator unit is absorbed in a concentrated salt solution releasing heat; c. a generator unit, wherein a diluted salt solution is concentrated by energy absorbing evaporation; d. a condenser, wherein vapor from the generator unit is cooled to form water in liquid form; wherein one or more nozzles placed inside the condenser discharge droplets of cooled liquid water into the vapor, such that the vapor is cooled and condensed by droplets of cooled liquid water from the nozzle.

2. An absorption heat exchange and thermal storage plant according to claim 1, wherein the salt in the salt solution is selected from a water absorbing salt such as calcium chloride, lithium chloride, lithium chlorate, zinc chloride, zinc bromide, or lithium bromide or mixtures thereof.

3. An absorption heat exchange and thermal storage plant according to claim 1 or 2, wherein the cooled liquid water discharged from the one or more nozzles into the condenser is cooled in a heat exchanger, preferably the water entering the heat exchanger being condensed water from the condenser.

4. An absorption heat exchange and thermal storage plant according to anyone of the preceding claims, wherein the cooled liquid water discharged into the condenser is recycled water from the condenser.

5. An absorption heat exchange and thermal storage plant according to anyone of the preceding claims, wherein the vapor is condensed in the condenser to form liquid water, said liquid water being collected at the lower part of the condenser and leading to a separate chamber for temporary storage.

6. An absorption heat exchange and thermal storage plant according to anyone of the preceding claims, wherein at least one of the evaporator unit, absorber unit, generator unit and condenser unit is connected to a chamber, where said chamber collects and stores liquid from the unit temporarily.

7. An absorption heat exchange and thermal storage plant according to anyone of the preceding claims, wherein the exterior medium to be cooled or heated comprises two or more fluids, where each fluid enters the absorption heat exchange and thermal storage plant with the same temperature or a temperature different from the other fluid(s).

8. An absorption heat exchange and thermal storage plant according to claim 7, wherein said fluids are cooled by the evaporator unit and / or the generator unit, each fluid having a temperature differing from the other fluid(s) when entering the plant and the fluid being cooled to a different temperature.

9. An absorption heat exchange and thermal storage plant according to claim 7 or 8, wherein the fluids each are cooled by the evaporator unit and / or the generator unit such that each fluid is cooled to a desired temperature.

10. An absorption heat exchange and thermal storage plant according to claim 7, wherein the one or more fluids are heated in the condenser unit and / or the absorber unit, and when two or more fluids are heated in the system, each fluid has a temperature differing from the other fluid when entering the plant, and they are heated to different temperatures.

11. A system for heat exchange and thermal storage, said system comprising: a. an evaporator unit, wherein water in liquid form is evaporated to form water vapor thereby extracting heat from an exterior medium that is to be cooled; b. an absorber unit, wherein the water vapor deriving from an evaporator unit is absorbed in a concentrated salt solution releasing heat; c. a generator unit, wherein a diluted salt solution is concentrated by energy absorbing evaporation; d. a condenser unit, wherein vapor from the generator unit is cooled to form water in liquid form; wherein at least one of the evaporator unit, absorber unit, generator unit and condenser unit is connected to a chamber, where said chamber collects and stores liquid from the unit temporarily.

12. A system according to claim 11, wherein liquid collected in a chamber from a unit can be recycled into the unit or distributed to neighbouring units.

13. A system according to claim 11 or 12, wherein chambers connected to different units have the same or different sizes.

14. A system according to claim 11, 12 or 13, wherein a chamber may have a size dimensioned to provide a desired thermal capacity.

15. A system according to any of the previous claims 11-14, wherein said chambers can be dimensioned to enable concurrent or intermittent cooling or heating processes.

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