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Arrangement and method for treatment of compressed gasRelated Patent Categories: Pumps, With Condition Responsive Control Of Coolant Or LubricantArrangement and method for treatment of compressed gas description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080031742, Arrangement and method for treatment of compressed gas. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD OF THE INVENTION [0001] The invention relates to an arrangement for pre-processing compressed gas for separation in an air-gas or other gas-gas separation unit, such as and preferably by membrane filtering. The arrangement includes a heat recovery arrangement for use with a compressor for gas, and to a method of recovering heat from compressor cooling fluid for regulating the temperature of the compressed gas before entering the gas separation unit. BACKGROUND OF THE INVENTION [0002] In the pre-processing of air or other gas for a membrane based air-gas or other gas-gas separation unit, it is important that air fed to the separation unit satisfies defined criteria. The dew point of the air must be such as to avoid condensation. The air must be filtered at an acceptable temperature to avoid aerosol and particle carry over. The air must be at a suitable operating temperature for efficient membrane separation. This is especially important and the temperature must be regulated before entering the separation unit to achieve best possible operation of the separation unit. The invention is concerned with heat recovery from the compressor cooling fluid for the continuous temperature regulation of the supply of air to satisfy these criteria. DISCLOSURE OF THE INVENTION [0003] The invention provides an arrangement for use with a liquid cooled and/or lubricated compressor for compressing gas, and incorporating provision to add liquid for cooling purposes to the gas prior to entry of the gas into the compressor, in which downstream of the compressor there is a liquid/gas separator to separate the liquid from the gas and in which there is means to recover heat from the liquid, and in which there is at least one filter in the gas stream downstream of the liquid/gas separator, and there is a heater in the gas stream downstream of the filter in which the gas is heated using heat recovered from the liquid, whereby to regulate the temperature of the pressurised gas prior to gas entry into the-separator unit. [0004] It is preferred that there is a heat exchanger in the gas stream between the liquid/gas separator and the at least one filter, and in that heat exchanger cooling medium from an external source is used to cool the gas stream. [0005] It is also preferred that there is a refrigerant dryer group arranged to cool the gas after the liquid has been separated from the gas, and before the gas is passed through the at least one filter. [0006] The at least one filter may be a coalescing particle filter, or a carbon filter for removal of vapour from the cooling liquid. [0007] The at least one filter may include two stage filtration, the first filter stage comprising a coalescing particle filter, and the second filter stage comprising a carbon filter for removal of vapour from the cooling liquid. [0008] The invention includes the arrangement described above, in combination with a membrane gas separator unit arranged to receive gas from the heater using the heat recovered from the liquid prior to the liquid passing through the filter. [0009] The invention includes the arrangement described above, in combination with a compressor for compressing the gas. The compressor may be a screw compressor, and the screw compressor may be cooled or cooled and lubricated by oil or other suitable cooling liquid. [0010] The invention also includes a method of recovering heat from a compressed gas from a liquid cooled and/or lubricated compressor, and comprising the steps of adding liquid for cooling purposes to a gas or directly into the compressor prior to the gas entering into the compressor, separating liquid from the gas after the gas has left the compressor, recovering heat from the liquid, passing the gas through at least one filter, and, downstream of the filter, using heat recovered from the liquid before the gas passed through the filter to heat the gas, whereby the regulate the temperature of the pressurised gas. ADVANTAGES OF THE INVENTION [0011] Performance of the separation process is dependent upon a relatively narrow range of operating parameters, particularly feed air temperature and pressure. It is for this reason that efficient conditioning of feed air supplied to the separator is important. The specific embodiment of the invention described above includes efficient use of heat supplied to the air, arranges for filters for the compressed air to operate at near optimum conditions, and allows the separation membranes to function at near optimum air pressure, temperature and dryness. Use of heat withdrawn from the gas stream to reduce the gas temperature before the filters, to preheat the gas stream after the filters makes efficient use of the energy applied to the system. The temperature regulation of the gas before entering the separation unit may in several prior art cases some from an external heating source. It is in some cases possible that additional heating from an external source may be required. The need is however reduced and in many cases eliminated by the invention. [0012] The invention is especially suited for building a module based system (compressor, arrangement for conditioning of compressed gas, separation unit) where the conditioning module does not require an external heating source. BRIEF DESCRIPTION OF THE DRAWINGS [0013] A specific embodiment of an arrangement to pre-process air for a membrane nitrogen separator will now be described by way of example with reference to the accompanying-process flow drawing, which shows a compressor section and a nitrogen separator section. DESCRIPTION OF THE SPECIFIC EMBODIMENT [0014] To facilitate efficient performance of the membrane nitrogen separator, compressed air must be cooled down to remove liquid, the dew point temperature must be reduced in order to avoid liquid condensation, the air must be filtered at an acceptable temperature to avoid aerosol and particle carry over, and finally the air temperature must be increased to the operating temperature for membrane separation. [0015] According to this example, air for the compressor section is drawn in through an inlet filter 9 to a single stage oil cooled/lubricated screw compressor 10. The compressed air with entrained oil passes to an oil/air separator 11, having a safety valve 12. The air passes on through a compressed air aftercooler 14 (also known as a `combicooler`). The aftercooler 14 comprises an integrated water cooled heat exchanger which also functions as a temperature control unit for the compressed air. [0016] The air then passes through a combined water separator/refrigerant cooler/dryer 15. This reduces the dew point to approximately 15 deg C. below inlet temperature, so that condensation will not occur further downstream. The dryer 15 is equipped with a dedicated cooling medium recycling unit with evaporator, compressor and condenser. [0017] It should be noted that the dryer 15 is not essential. However, if the dryer is dispensed with, the air from the compressor 10 will be at its saturation point after leaving the cooler 14. In this circumstance the temperature of the air must be increased to avoid condensation further downstream. A problem may arise in that the increased temperature might be beyond the limitations of the polymer membranes preferably used in the nitrogen separator section. [0018] Air from the dryer 15 passes through a check valve 16 and a ball valve 16a. The cooled air is now at a suitable temperature, pressure and dryness to pass through a coalescing particle filter 17 (for retention of oil aerosol carry over) and a carbon filter 18 (for removal of oil vapour). Elimination of the dryer 15 might also lead to inefficiencies in the filters 17 and 18 due to the higher operating temperatures. Continue reading about Arrangement and method for treatment of compressed gas... Full patent description for Arrangement and method for treatment of compressed gas Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Arrangement and method for treatment of compressed gas patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Arrangement and method for treatment of compressed gas or other areas of interest. ### Previous Patent Application: Jet pump slip joint with axial grooves Next Patent Application: Frame mounted pump Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Arrangement and method for treatment of compressed gas patent info. 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