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US 7,111,470 B2Granted
Variable evaporator control for a gas dryer
AssigneeSPX Corporation
InventorsBrian W. Pritchard, Mark F. Honath, Timothy J. Fox
Life of this patent
Estimating the term…
Abstract
A variable evaporator control system and method in a gas dryer for maximizing the cooling which can be accomplished for a given length heat exchanger by adjusting the evaporator refrigerant approach temperature responsive to changes in the gas load on the system. Pressure and/or temperature sensors positioned at particular locations in the system provide feedback for controlling adjustments in the approach temperature depending on the gas load.
Claims8
A variable evaporator control refrigerated compressed gas dryer comprising:
- a. an evaporator heat exchanger having a first flow path for compressed gas at a first temperature;
- b. said evaporator heat exchanger having a second flow path for a refrigerant at a second temperature which is lower than said first temperature to cool said compressed gas to a third temperature;
- c. a compressor to circulate said refrigerant at a predetermined pressure, said predetermined pressure having a correlation to said second temperature;
- d. a temperature sensor to sense said third temperature at an outlet of said first flow path, wherein said temperature sensor positioned at a single location to sense a fourth temperature wherein said fourth temperature is representative of said third temperature when a compressed gas load is above a certain level, and representative of said second temperature when said compressed gas load is below said certain level;
- e. a valve intermediate said second flow path and a source of refrigerant, said valve controllable to admit refrigerant into circulation to adjust said predetermined pressure;
- and
- f. a controller connected to receive feedback from said temperature sensor indicative of said third temperature, said controller controlling said valve to adjust said predetermined pressure and thus adjust said second temperature to generally maintain said third temperature at a desired value, wherein said controller connected to receive feedback from said temperature sensor indicative of said fourth temperature to control said valve to adjust said predetermined pressure and thus said second temperature such that said fourth temperature is generally maintained at said desired value;
- and
- g. a smooth tube evaporator heat exchanger.
6 more elements
A variable evaporator control system comprising:
- a. an evaporator heat exchanger having a first flow path for a gas at a first temperature and a second flow path for circulation of a refrigerant at a second temperature which is lower than said first temperature to cool said gas to a third temperature;
- b. a compressor to circulate said refrigerant;
- c. a temperature sensor positioned in said evaporator heat exchanger at a single location to sense a fourth temperature which is representative of said third temperature when a gas load is above a certain level, and representative of said second temperature when said gas load is below said certain level;
- and
- d. a controller connected to receive feedback from said temperature sensor indicative of said fourth temperature to control said second temperature to generally maintain said fourth temperature at a desired value.
2 more elements
A compressed gas dryer having a heat exchanger with a first flow path for a compressed gas and a second flow path for a refrigerant to cool said compressed gas, the compressed gas dryer comprising:
- a. a temperature sensor to sense a temperature of said compressed gas at an outlet of said first flow path;
- b. a controller connected to receive feed back from said temperature sensor indicative of said temperature of said compressed gas at said outlet of said first flow path, said controller controlling a temperature of said refrigerant at an inlet of said second flow path to generally maintain said temperature of said compressed gas at said outlet of said first flow path at a desired value;
- c. said temperature sensor of said compressed gas at said outlet of said first flow path being positioned in said heat exchanger at a single location;
- d. a temperature sensed at said single location being representative of said temperature of said compressed gas at said outlet of said first flow path when a compressed gas load is above a certain level;
- and
- e. said temperature sensed at said single location being representative of said temperature of said refrigerant at said second flow when said compressed gas load is below said certain level.
3 more elements
Dependencies are inferred from the claim text.