Gas dehumidification system

Abstract

Disclosed herein is an improved gas dehumidification system comprised of an ambient air-cooler (101) for cooling a circulating coolant. A central pump (102) is connected to the ambient air cooler (101) to receive and circulate a part of the circulating coolant to a first heat exchanger (103) and another part to a second heat exchanger (104), fluidly coupled with the central pump (102). A dehumidification unit (106) is in connection with the first and second heat exchangers (103) and (104) to receive the cooled coolant to dehumidify a gas passing through dehumidification unit (106) and directs back the coolant to ambient air-cooler (101) through the second heat exchanger (104) to re-utilize the coolant for another cycle of gas dehumidification.

Description

GAS DEHUMIDIFICATION SYSTEMFIELD OF THE INVENTION

[0001] The present invention relates to a gas dehumidification system designed to dehumidify high mixed-gas streams such as air at elevated temperature and humidity.BACKGROUND OF THE INVENTION

[0002] Dehumidification is the process of eliminating excess moisture or humidity, particularly from a saturated mixed-gas stream, and is typically achieved through cooling or desiccation methods or sorption-based methods. In industrial settings, dehumidification plays a crucial role in maintaining optimal conditions for processes, equipment, and product quality. Excessive moisture can result in corrosion, mold growth, equipment malfunctions, and compromised product integrity, especially in industries such as pharmaceuticals, food processing, electronics manufacturing, and storage facilities. The control of humidity ensures a stable and controlled environment, improving production efficiency, and preserving the quality and shelf life of materials and products. Thus, dehumidification is a fundamental necessity in various industrial operations.

[0003] Conventional approaches or methods of dehumidification often face challenges when dealing with gases with high temperatures and high moisture content. The known methods encounter various limitations, such as inefficiency in handling high water loads, leading to decreased performance and increased energy consumption. Moreover, known systems are not sufficient to maintain consistent humidity levels, particularly in industries with fluctuating operating conditions. Additionally, the complexity of traditional dehumidification systems can posesignificant installation and maintenance challenges due to limited space, which in turn reduces the overall working efficiency of the system.

[0004] Patent application no. WO1997046304A1 discloses a process and corresponding device for drying damp gas, particularly natural gas. The process involves adiabatic expansion of the damp gas followed by turbulent flow in a rotationally symmetrical centrifugal field, resulting in the formation of separate hot and cold gas streams due to the Hilsch effect. However, this method's reliance on adiabatic expansion and a rotationally symmetrical centrifugal field may not efficiently handle high water loads or supersaturated gas flows at elevated temperatures. Furthermore, the use of a cyclone tube and gas-liquid separator in the process may not be suitable for compact or pressure-resistant dehumidification systems required in certain industrial applications.

[0005] Patent Application W02003092849A1 discloses a condenser designed to cool a gas flow and promote vapor condensation. The condenser features a cylindrical chamber where gas enters, acquiring a swirl velocity before passing through radial holes into a separator. Water droplets are directed outward by the swirl velocity and collected in a separate compartment. Cooling for condensation is achieved via an external jacket with a helical coolant flow. However, challenges may arise in effectively handling high water content in the gas flow and ensuring efficient condensation, especially in variable operating conditions.

[0006] The known methods primarily focus on cooling the gas to promote condensation but do not adequately address the challenges posed by elevated temperatures and high water loads. Each of the existing approaches has limitations in effectively managing high-temperature gas flows with high water content. Such challenges aggravate especially in fluctuating operating conditions, and thus, require innovative solutions tailored to industrial needs. Additionally, the complexity andsize of such systems may pose practical challenges for implementation and maintenance.

[0007] Therefore, there exist unmet needs to develop a system that can withstand the above-mentioned limitations and provide a cost-effective, space-saving, and energyefficient output while gas dehumidification.OBJECTIVE OF THE INVENTION

[0008] An objective of the present invention is to provide a gas dehumidification system that is capable of achieving continuous dehumidification of gas flowing at an elevated temperature ranges from 50 °C to 80 °C and containing high moisture contents up to 1600 grams of water per kilogram of air or dry gas.

[0009] Another objective of the present invention is to develop a gas dehumidification system capable of handling and maintaining / regulating the overpressure conditions throughout the gas dehumidification process, thereby mitigating the risk of casualties.

[0010] Yet another objective of the present invention is to develop a gas dehumidification system that is compact in construction, utilizes less space, and requires less maintenance.

[0011] A further objective of the present invention is to minimize energy consumption and thus achieve cost savings during the dehumidification process.SUMMARY OF THE INVENTION

[0012] This section provides a general summary of the disclosure and is not a comprehensive disclosure of the full scope of all its features.

[0013] The present invention provides an improved gas dehumidification system specifically designed to dehumidify a gas at a high temperature of 50 to 80 °C and high humidity, containing up to 600 grams of water per kilogram of air or dry gas with high moisture content. In an embodiment, the disclosed gas dehumidification system comprises an ambient air-cooler for cooling a circulating coolant. A central pump is connected to the ambient air cooler for receiving the circulating coolant to supply the first part of said circulating coolant to a first heat exchanger and a second part to a second heat exchanger. The first heat exchanger and the second heat exchanger are fluidly coupled with the central pump. Said cooled circulating coolant is introduced into the dehumidification unit. The dehumidification unit comprises a falling film condenser, to dehumidify the gas passing through it. Thereafter, the coolant is circulated back to the ambient air cooler through the second heat exchanger for reuse. This integrated system efficiently controls humidity levels in gas streams for various industrial applications.

[0014] In an embodiment, a refrigeration unit is convectively linked to both of the heat exchangers, and a dehumidification unit is connected to the first and second heat exchangers. The refrigeration unit facilitates heat exchange with the circulating coolant to further lower the temperature of the circulating coolant.

[0015] In an embodiment, the circulating coolant is cooled convectively against ambient air via said ambient air cooler.

[0016] In an embodiment, the second heat exchanger receives the second part of the coolant through a bypass mechanism arranged between the first heat exchanger and the second heat exchanger.

[0017] In a further embodiment, the bypass mechanism comprises a control valve to regulate the flow of the second part of the circulating coolant within said second heat exchanger.

[0018] In another embodiment, the dehumidification unit comprises a finned-tube heat exchanger convectively exchanging heat between the flowing gas and circulating coolant.

[0019] In an embodiment, said fins of the finned-tube heat exchanger are coated with a hydrophobic coating to direct the condensate droplets, formed while dehumidification of said gas, to an outlet, bottom of the finned-tube heat exchanger.

[0020] In a further embodiment, said condensate droplets formed during dehumidification are collected within the outlet bottom of the finned tube heat exchanger.

[0021] In yet another embodiment, a level sensor is installed at the base of the dehumidification unit to determine the level of condensate collected at the outlet bottom space within the dehumidification unit.

[0022] In an alternate embodiment, said refrigeration unit is a liquid-liquid chiller.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forthillustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings or figures, of which:

[0024] Figure 1 illustrates a schematic view explaining the working operation of an improved gas-dehumidification system, in accordance with the disclosed embodiments.DETAILED DESCRIPTION OF THE INVENTION

[0025] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and the following description. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the present disclosure herein may be employed.

[0026] Some embodiments of this invention, illustrating all its features, will now be discussed in detail. The words “comprising,” “having,” “containing,” and “including,” and other forms thereof, are intended to be equivalent in meaning and be open-ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items.

[0027] It must also be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context dictates otherwise. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, the preferred, systems and methods are now described.

[0028] The present disclosure pertains to an improved gas dehumidification system that effectively eliminates significant moisture / water content from a gas flowing at elevated temperatures. Additionally, it ensures that gas leaks are prevented throughout the dehumidification process.

[0029] Figure 1 illustrates a schematic view of an improved gas-dehumidification system 100, comprising an ambient air-cooler 101 that serves to cool a circulating coolant used in a dehumidification system. A central pump 102 is connected to the ambient air cooler 101 for receiving a circulating coolant. Two heat exchangers, namely a first heat exchanger 103 and a second heat exchanger 104, are fluidly coupled with the central pump 102 to receive the circulating coolant. A refrigeration unit 105 is convectively connected with both of the heat exchangers 103, and 104; and a dehumidification unit 106 is in a fluid connection with both of the heat exchangers 103, 104.

[0030] The ambient air-cooler 101 is utilized for convective cooling of the circulating coolant utilizing ambient air. The ambient air-cooler 101 disclosed herein comprises a fan positioned at an opening formed in the wall of the ambient air-cooler 101 and a pipe passing through the ambient air-cooler 101. The fan draws ambient air from the surroundings and allows it to flow over the pipe. The continuous flow of ambient air over the pipe convectively cools down the temperature of the circulating coolant flowing through said pipe. In a preferred embodiment, the circulating coolant flowing in the pipe is a mixture of water and glycol.

[0031] The circulating coolant, after being cooled by the ambient air, is received by the central pump 102 connected to the ambient air cooler 101 by said pipe. The central pump 102 further circulates the coolant to the heat exchangers 103, and 104. Said central pump 102 supplies the first part of the circulating coolant to the first heat exchanger 103 connected by said pipe in continuation to the central pump 102.

[0032] Further, a second part of the circulating coolant is supplied to the second heat exchanger 104 via a bypass mechanism 108. Said by-pass mechanism 108 includes a delivery tube connected between the central pump 102 and the second heat exchanger 104, bypassing the first heat exchanger 103. Said by -passing mechanism 108 is controlled by a control valve 107 installed.

[0033] The first part of the circulating coolant enters the first heat exchanger 103, which is further cooled down by the refrigeration unit 105 which is also connected to the first heat exchanger 103. The refrigeration unit 105 is convectively connected with both of the heat exchangers 103, and 104, thus, enabling heat exchange between both parts of the circulating coolant and the refrigeration unit 105. In a preferred embodiment, the refrigeration unit 105 is a liquid-liquid chiller. Upon cooling of the circulating coolant, the circulating coolant is directed to the dehumidification unit 106 which is fluidly coupled in continuation to the first heat exchanger 103.

[0034] The dehumidification unit 106 comprises a hollow pressure cylinder with closed ends, providing a sealed enclosure, thereby preventing any leakage during the dehumidification process of a gas. In an embodiment, the temperature of the gas entering inside the dehumidification unit 106 may operate within a temperature range of 50 to 80 °C. The hollow pressure cylinder is incorporated with a fin-and-tube heat exchanger which enables convective heat exchange between the gas and circulating coolant, flowing inside the fin and tube heat exchanger. In an embodiment, the fin- and-tube heat exchanger is firmly attached by two metal struts to ensure stability inside the pressure cylinder.

[0035] The pressure cylinder includes a circular plate with grooves for directing the hot gas to flow through the fin and tube heat exchanger. This design of a circular plate allows the hot gas to free flow downward towards the fins of the fin and tubeheat exchanger, while the coolant circulates inside the fin and tube heat exchanger, in an opposite direction i.e., from bottom to top through the tubes of fin and tube heat exchanger. In an embodiment, the circular plate prevents any bypass flow of the gas to ensure that the entire gas passes through the fins.

[0036] As the gas comes into contact with the fins, a convective heat exchange takes place between the gas and the circulating coolant flowing in the tubes. Due to the heat exchange, the temperature of the gas reduces thereby, prompting the conversion of the moisture content in the gas to minute condensate droplets on the fins.

[0037] For example, if the temperature of the hot gas entering the dehumidification unit 106 is 80 degrees Celsius with 100% humidity, then after going through the above heat-exchange process, the temperature of the gas becomes 8 degrees Celsius with around 95% of humidity removed in the form of condensed droplets, that equals a reduction from approx.. 560 Grams Water / per kg dry air to approx. 7 Grams Water / per kg dry air. Thus, for a nominal gas flow with a dry air content gas flow of Ikg / minute, this equals a water condensation rate of approx. 0.5 kg / minute.

[0038] In accordance with an embodiment, the fins of the fin and tube heat exchanger are coated with a hydrophobic coating. The condensate droplets coming in contact with the fins coated with said hydrophobic coating eventually drain out from the dehumidification unit 106 to get collected within a bottom of the vessel not shown here coupled fluidly with the dehumidification unit 106. The hydrophobic coating ensures the smooth and safe drainage of the droplets formed during the dehumidification of gas.

[0039] Once condensate droplets are collected in the drain tank, the first part of the circulating coolant, heated due to absorption of the heat from the gas, is directed to the second heat exchanger 104. Before entry into the second heat exchanger 104, saidfirst part is- mixed with the second part of coolant directed to the second heat exchanger 104 through the bypass mechanism 108. Due to this, the overall temperature of the mixture reaches an average of the temperature of the first part and the second part of the circulating coolant. The circulating coolant is further redirected to the ambient air-cooler 101 via a return-pipe 109, to initiate the next cycle of the gas dehumidification process.

[0040] In an alternate embodiment, the gas dehumidification unit 106 may include additional fins positioned outside of heat exchangers. They act as attached and serve to keep "cold” from the dehumidified air to the incoming hot to transmit gas / air - an internal one, to the wall of the pressure cylinder, allowing for further heat exchange between the gas and the coolant due to an increased surface area, thereby, increasing the condensate formation within the dehumidification unit 106.

[0041] In another embodiment, said additional fins may be materially connected with the fins of the fin and tube heat exchanger.

[0042] Additionally, a level sensor could be positioned at the lower end of the pressure cylinder within the gas dehumidification unit 106. Its purpose is to ascertain the minimum condensate level necessary to maintain within the pressure cylinder. This maintenance prevents gas from escaping via the condensate drain holes situated at the lower base of the pressure cylinder.

Claims

I / We Claim1. A gas dehumidification system (100), comprising: an ambient air-cooler (101) for cooling a circulating coolant; a central pump (102) connected with said ambient air cooler (101); a first heat exchanger (103) and a second heat exchanger (104) fluidly coupled with said central pump (102); a dehumidification unit (106) in connection with said first and second heat exchangers (103) and (104); wherein said central pump (102) supplies a part of said circulating coolant to said first heat exchanger (103) and another part to said second heat exchanger (104), wherein said dehumidification unit (106) is configured to receive the cooled circulating coolant to dehumidify a gas passing through said dehumidification unit (106) and directs back said circulating coolant to said ambient air-cooler (101) through said second heat exchanger (104) for re-utilization.

2. The system as claimed in claim 1, wherein said circulating coolant is cooled convectively against the ambient air via said ambient air cooler (101).

3. The system as claimed in claim 1, said the second heat exchanger (104) receives another part of said coolant through a bypass mechanism (108) arranged between said first heat exchanger (103) and said second heat exchanger (104).

4. The system as claimed in claim 1, said bypass mechanism 108 comprises a control valve (107) to regulate the flow of said circulating coolant within said second heat exchanger (104).

5. The system as claimed in claim 1, wherein said dehumidification unit (106) comprises a finned-tube heat exchanger convectively exchanging heat between said flowing gas and said circulating coolant.

6. The system as claimed in claim 5, wherein said fins of said finned-tube heat exchanger are coated with a hydrophobic coating to ensure the formation of condensate droplets while dehumidification of said gas.

7. The system as claimed in claim 6, wherein said condensate droplets formed during said gas dehumidification gets collected within a drain tank coupled with said dehumidification unit (106).

8. The system as claimed in claim 7, wherein a level sensor is installed at the base of said dehumidification unit to determine the level of condensate collected at said base within said dehumidification unit.

9. The system as claimed in claim 1 further comprises a refrigeration unit (105) coupled convectively with said first heat exchanger (103) and said second heat exchanger (104), wherein said refrigeration unit (105) facilitates heat exchange between said the circulating coolant and said refrigeration unit (105), to further cool down the temperature of said circulating coolant.

10. The system as claimed in claim 9, wherein said refrigeration unit (105) is a liquid-liquid chiller.

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