Refrigeration – Processes – Circulating external gas
Reexamination Certificate
2001-07-11
2002-10-29
Doerrler, William C. (Department: 3744)
Refrigeration
Processes
Circulating external gas
C062S093000, C062S402000, C062S498000
Reexamination Certificate
active
06470693
ABSTRACT:
FIELD OF INVENTION
The present invention relates generally to gas compressors, and more particularly to refrigeration systems for gas compressors.
BACKGROUND OF INVENTION
A common problem when using a gas in an enclosed system is removing condensable material from the gas. Condensable material may lead to a variety of problems within the closed system if the material is left in the gas. A common method to remove condensable material from a gas is to cool the gas to a temperature below the condensation temperature of the condensable material, and then separate the condensed material from the gas. The substantially condensate free gas may then proceed through the system to its final application.
Removing condensable material from a gas is especially important for air compressors that must remove water vapors from the compressed air. Compressed air may experience several temperature changes within compressed air lines, and water vapors may form a liquid within the lines. Water vapors and liquid within compressed air lines may cause corrosion, reduce air pressure, clog filters, and lead to inconsistent air output. These problems can be substantially eliminated by removing the water from the compressed air before using the air in the final application.
Air compressors typically have a refrigerant system to lower the temperature of the compressed air to a temperature below the condensation temperature of water, such that condensed water can be removed from the compressed air. The refrigerant system passes a charge of refrigerant through an enclosed circuit that transfers heat from the compressed air to the refrigerant, and reduces the compressed air temperature. Elements of the refrigerant system generally include a chiller, a compression unit, a condenser, and a reheater. The chiller uses the refrigerant to lower the compressed air temperature to a temperature below the condensation temperature of water. The compression unit adds energy to the refrigerant. The condenser transfers heat from the refrigerant to ambient air, and lowers the temperature of the refrigerant. The reheater transfers heat from the refrigerant to the compressed air to warm the compressed air before it is discharged.
Prior art devices pass the refrigerant through a compression unit, condenser, reheater, and then a chiller in series. This arrangement adds energy to the refrigerant in the compression unit, and then removes that energy in the condenser soon afterwards.
SUMMARY OF INVENTION
The present invention includes an improved and efficient gas compressor cooling system for removing condensable material from a compressed gas. The cooling system comprises a gas system and a closed refrigerant system. The gas system includes a chiller for cooling the gas and forming a condensate, a separator for separating the condensate from the gas, and a reheater for reheating the gas. In the preferred embodiment, the compressed gas is air, and the condensate being removed from the air is water.
The gas system passes compressed air through a chiller, separator, and reheater in series to remove water from the compressed air. The chiller lowers the temperature of the compressed air to a temperature below the condensation temperature of water, and a condensate forms. The separator separates the condensed water from the compressed air. Finally, the reheater increases the temperature of the compressed air. In the preferred embodiment, the temperature of the compressed air exiting the reheater is higher than the inlet temperature of compressed air entering the chiller.
The refrigerant system preferably includes the chiller, a compression unit, the reheater, a condenser, a filter dryer, and an expansion device. A charge of refrigerant is passed through the compression unit, the reheater, the condenser, and the chiller in series. The compression unit adds energy to the refrigerant, and increases the pressure and temperature of the refrigerant. The reheater transfers heat from the refrigerant to the compressed air, and the condenser transfers heat from the refrigerant to ambient air. Preferably, the filter/dryer removes water and particulate matter from the refrigerant, and the expansion device lowers the pressure of the refrigerant. The chiller transfers heat from the compressed air to the refrigerant, and lowers the compressed air temperature below the condensation level of water.
The refrigerant passes through the reheater directly after passing through the compression unit, and before passing through the condenser. This arrangement utilizes the energy added to the refrigerant from the compression unit to maintain a high temperature for the refrigerant entering the reheater. The high refrigerant temperature increases the difference in temperature between the refrigerant and the compressed air entering the reheater. The large temperature difference creates a large heat exchange potential in the reheater, which improves the reheater efficiency, and allows a high compressed air discharge temperature.
REFERENCES:
patent: 1853236 (1932-04-01), Shadle
patent: 3041842 (1962-07-01), Heinecke
patent: 3585808 (1971-06-01), Huffman
patent: 5566555 (1996-10-01), Hewitt
patent: 5611209 (1997-03-01), Ogasawara et al.
patent: 5794453 (1998-08-01), Barnwell
patent: 5845505 (1998-12-01), Galus et al.
patent: 6170270 (2001-01-01), Arshansky et al.
Doerrler William C.
Drake Malik N.
Ingersoll-Rand Company
Michael & Best & Friedrich LLP
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