Low dew point gas generator cooling system
AssigneeSurface Combustion, Inc.
InventorsMichael J. Huber, Jerry P. Jason, Garry W. Barbee
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Abstract
A drying system is disclosed for drying wet gases, typically produced by a gas generator to dew points less than 32.degree. F. The system uses a refrigeration cycle having a single compressor to dry the wet gas in a first evaporator while simultaneously defrosting the ice buildup on a second evaporator. The cycle then switches from the first evaporator to the second evaporator after the second evaporator is defrosted. The switching is preceded by a changeover phase in which cooled refrigerant is pulsed to the defrosted evaporator and both evaporators go on line for a short time before the system phase change occurs thus assuring control of the dried gas temperature while avoiding shock to the refrigeration system.
Claims26
A method for producing from a wet gas stream a continuous stream of dried gas having a dew point less than about 20.degree. F. comprising the steps of:
- a) providing i) a single compressor for compressing a refrigerant gas to produce a compressed, heated refrigerant gas stream, ii) a condenser for liquefying said compressed heated refrigerant gas stream to produce a cooled refrigerant stream, iii) first and second evaporator coils with associated expansion valves, and iv) valves for porting said refrigerant streams between said evaporators and said wet gas stream over said evaporators;
- b) repeatedly performing a periodic, refrigeration cycle in which i) during a first phase of said cycle, said wet gas is passed over said first evaporator which functions as an active evaporator through which said cooled refrigerant stream passes for drying said wet gas passing over said first evaporator while a portion of said heated compressed refrigerant stream is passed through said second evaporator which is in an inactive state for defrosting same and ii) during a second phase of said cycle, said wet gas is ported over said second evaporator acting as an active evaporator through which said cooled, refrigerant stream passes for drying said wet gas while a portion of said heated compressed refrigerant in passed through said first evaporator functioning as an inactive evaporator for defrosting same;
- c) during each cycle phase metering a portion of said heated compressed refrigerant stream into said cooled refrigerant stream ported into said active evaporator, the metering rate of said heated refrigerant stream being periodically reduced from the beginning to the end of each cycle phase as ice accumulates on said active evaporator whereby said wet gas is continuously dried to a generally constant dew point throughout each portion of the cycle.
A method for producing a gas dried to a low dew point suitable for use as the furnace atmosphere in an industrial heat treat process, said method comprising the steps of:
- a) reacting air with a combustible hydrocarbon gas at a set ratio in a gas generator to produce a wet gas having a desired gas composition including water vapor and immediately drying said wet gas to a dew point of about 100.degree. F.;
- b) providing i) a compressor for compressing a refrigerant gas to produce a compressed, heated refrigerant gas stream, ii) a condenser for liquefying said compressed heated refrigerant gas stream to produce a cooled refrigerant stream iii) first and second evaporator coils, each having associated expansion valves, and iv) valves for porting said refrigerant streams between said evaporators and said wet gas over said evaporators;
- c) repeatedly performing a periodic, refrigeration cycle in which i) during a first phase of said cycle wet gas is passed over said first evaporator functioning as an active evaporator through which said cooled refrigerant stream passes for drying said wet gas to dew points less than 32.degree. F. while a portion of said heated compressed refrigerant stream is passed through said second evaporator functioning as an inactive evaporator for defrosting same, and ii) during a second phase of said cycle said wet gas is passed over said second evaporator coil acting as an active evaporator through which said cooled, refrigerant stream passes for drying said wet gas to dew points less than 32.degree. F. while a portion of said heated, compressed refrigerant is passed thorough said first evaporator for defrosting same whereby the sensible heat of said wet gas is utilized by said refrigeration cycle to defrost said inactive evaporator.
Apparatus for drying wet gases having dew points in excess of about 40.degree. F. to dry gases having a dew point less than 32.degree. F. comprising:
- a) a refrigeration system including a i) compressor for compressing a refrigerant gas to a heated, compressed refrigerant gas, ii) a condenser in fluid communication with said compressor for condensing said heated refrigerant gas to a cooled, condensed refrigerant, iii) first and second evaporators with associated expansion valves for drying said wet gas, and iv) refrigerant valve means for selectively porting said heated compressed refrigerant and said condensed refrigerant to said evaporators;
- b) a cooling tank having first and second compartments, each with an inlet and outlet and insulated from one another and in which said first and second evaporators, respectively, are disposed, each compartment having cooling tank valve means controlling which compartment and its associated evaporator receives said wet gas;
- c) control means regulating said cooling tank valve means and said refrigeration valve means for repeatedly performing a periodic refrigeration cycle in which i) during a first phase of said cycle wet gas is passed over said first evaporator functioning as an active evaporator through which said cooed refrigerant stream passes for drying said wet gas to a dew point less than 32.degree. F. while a portion of said heated compressed refrigerant stream is passed through said second evaporator functioning as an inactive evaporator for defrosting same, and ii) during a second phase of said cycle said wet gas is passed over said second evaporator coil acting as an active evaporator through which said cooled, refrigerant stream passes while a portion of said heated, compressed refrigerant is passed through said first evaporator for defrosting same whereby the sensible heat of said wet gas is utilized by said refrigeration cycle to defrost said inactive evaporator.
Dependencies are inferred from the claim text.