GAS DEHUMIDIFICATION SYSTEM

Description

FIELD OF THE INVENTION

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

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.

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 pose significant installation and maintenance challenges due to limited space, which in turn reduces the overall working efficiency of the system.

Patent application no. WO1997046304A1 discloses a process and corresponding device for drying damp gas, particularly natural gas. The process involves an 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.

Patent Application WO2003092849A1 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.

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 and size of such systems may pose practical challenges for implementation and maintenance.

Therefore, there exist unmet needs to develop a system that can withstand the above-mentioned limitations and provide a cost-effective, space-saving, and energy-efficient output while gas dehumidification.

OBJECTIVE OF THE INVENTION

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 600 grams of water per kilogram of air or dry gas.

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

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.

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

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

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. The invention allows achieving process gas cooling temperatures as low as 1° C. under ambient conditions reaching up to 45° C.

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.

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

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.

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.

In another embodiment, the dehumidification unit comprises a hollow pressure cylinder with a finned-tube heat exchanger convectively exchanging heat between the flowing gas and circulating coolant.

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 the bottom of the tank, in which the finned-tube heat exchanger is integrated.

In a further embodiment, said condensate droplets formed during dehumidification are collected within the bottom of tank containing the finned tube heat exchanger.

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 collected at the bottom of the gas dehumidification unit and to ensure that only liquid condensate is released through the condensate pipe.

In an alternate embodiment, said refrigeration unit is a liquid-liquid chiller.

In an embodiment, the dehumidification unit comprises additional fins protruding from outer walls of the finned-tube heat exchanger.

Gravity, inertia, and said protruding contours in the clearance region of the embodiment are employed to process-safely separate said condensate droplets from the major gas stream.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 1 illustrates a schematic view explaining the working operation of an improved gas dehumidification system, in accordance with the disclosed embodiments.

FIGS. 2A and 2B illustrate cross-sectional views of a hollow pressure cylinder of a dehumidification unit of the gas dehumidification system, in accordance with the various embodiments of the gas-dehumidification system.

DETAILED DESCRIPTION OF THE INVENTION

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.

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.

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.

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.

FIG. 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 the heat exchangers 103 and 104.

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.

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.

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.

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 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.

The dehumidification unit 106 comprises a hollow pressure cylinder 110 (shown in detail in FIGS. 2A and 2B) 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 110 is incorporated with a fin-and-tube heat exchanger 111, which enables convective heat exchange between the gas and circulating coolant flowing inside the fin and tube heat exchanger 111. In an embodiment, the fin-and-tube heat exchanger 111 is firmly attached by two metal struts to ensure stability inside the pressure cylinder 110.

The pressure cylinder 110 includes a circular plate with grooves for directing the hot gas to flow through the fin and tube heat exchanger 111. This design of a circular plate allows the hot gas to free flow downward through a plurality of fins 112 of the fin and tube heat exchanger 111 (as illustrated in FIG. 2B) while the coolant circulates inside the fins 112 and tube heat exchanger 111, in an opposite direction i.e., from bottom to top through the tubes of fin and tube heat exchanger 111. In an embodiment, the circular plate prevents any bypass flow of the gas to ensure that the entire gas passes through the fins 112.

As the gas comes into contact with the fins, 112, 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 112. The condensate droplets rain at the bottom of the hollow cylinder 110, where it is checked, collected, and derived. The dehumidified air present at the bottom of hollow cylinder 110, is reversed by 180°, and flows upwards in the gap area between the hollow cylinder and fin-tube heat exchanger 111, to ensure that only liquid condensate is released through the condensate pipe. After the reversed flow of dehumidified air, the control valve closed as soon as the condensate level dropped below a level sensor.

In an embodiment, the level sensor could be positioned at the lower end of the pressure cylinder 110 within the gas dehumidification unit 106. Its purpose is to ascertain the minimum condensate level necessary to maintain within the pressure cylinder 110. This maintenance prevents gas from escaping via the condensate drain holes situated at the lower base of the pressure cylinder 110.

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, which equals a reduction from approximately 560 grams of water per kg of dry air to approximately 7 grams of water per kg of dry air. Thus, for a nominal gas flow with a dry air content gas flow of 1 kg/minute, this equals a water condensation and extraction rate of approx. 0.5 kg/minute.

In accordance with an embodiment, the fins 112 of the fin and tube heat exchanger 111 are coated with a hydrophobic coating. The condensate droplets coming into contact with the fins 112 coated with said hydrophobic coating eventually drain out of the dehumidification unit 106 to get collected within the bottom of the pressure cylinder 110 inside the dehumidification unit 106. The hydrophobic coating ensures the smooth and safe drainage of the droplets formed during the dehumidification of gas.

Once condensate droplets are collected in the bottom of the cylinder 110, 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, said first 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 re-directed to the ambient air-cooler 101 via a return-pipe 109, to initiate the next cycle of the gas dehumidification process.

In an alternate embodiment, the hollow pressure cylinder 110 of the gas dehumidification unit 106 may include a plurality of additional fins 113 positioned on the outer walls/exterior of the integrated fin and tube heat exchangers 111. The additional fins 113 transfer “cold” from the dehumidified air to the hot air coming inside the pressure cylinder, thereby enhancing cold recovery and allowing further heat exchange between the air and coolant due to increased surface area. This process increases condensate formation within the dehumidification unit, improving energy efficiency and reducing drive energy consumption for the heat pump or refrigeration machine.

In another embodiment, the additional fins 113 may be materially connected with the fins 112 of the finned-tube heat exchanger 111.