Refrigeration – Processes – Circulating external gas
Patent
1987-04-10
1988-03-22
Capossela, Ronald C.
Refrigeration
Processes
Circulating external gas
62 18, 62 37, 62 42, F25J 300
Patent
active
047325950
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oxygen gas production apparatus by which high purity gaseous oxygen can be expediently produced.
2. Description of the Prior Art
It is customary to produce oxygen gas in an air fractionation plant which separates oxygen from nitrogen by taking advantage of their difference in boiling point. This conventional air fractionation plant is provided with an expansion turbine for generating the refrigeration necessary for the liquefaction and fractionation of air, which utilizes the Joule-Thomson effect due to adiabatic expansion.
However, because of its extremely high speed (tens of thousand revolutions per minute), the expansion turbine cannot delicately follow variations in demand load (variations in the rate of withdrawal of product oxygen gas). Thus, it is technically difficult to vary the rotational speed of the expansion turbine quickly and accurately in response to changes in the demand for product oxygen gas so as to maintain the compressed material air at a constant temperature at all times. As a result, a variation is inevitable in the purity of product oxygen gas, for low purity oxygen is frequently outputted to depress the overall purity of product oxygen.
OBJECT OF THE INVENTION
Having been accomplished in view of the above-described situation, the present invention aims at providing an oxygen gas production apparatus which is adapted to follow variations in load so that the purity of product oxygen gas may be kept constant.
SUMMARY OF THE INVENTION
The present invention is therefore directed to an oxygen gas production apparatus comprising an air compression means for compressing air from an outside source, a purification means for removing carbon dioxide gas and water vapor from the air compressed by said air compression means, a heat exchange means for chilling the compressed air from said purification means to a cryogenic temperature, a fractionation column for liquefying and fractionating the compressed air chilled to a cryogenic temperature by said heat exchange means and holding nitrogen in gaseous state and oxygen in liquid state, a liquid oxygen storage means for receiving liquid oxygen from an outside source and storing the same, a line for introducing into said fractionation column the liquid oxygen from said liquid oxygen storage means as the refrigerant source for liquefaction of compressed air, a liquid level detection-control means for monitoring the liquid level of oxygen held in said fractionation column and controlling the amount of feed of liquid oxygen from said liquid oxygen storage means in response with changes in said liquid level, a second line for guiding gaseous nitrogen in said fractionation column to said heat exchange means as a refrigerant, an expansion means for cooling the gaseous nitrogen in said second line by the principle of adiabatic expansion, and an oxygen gas withdrawal line for guiding the liquid oxygen in said fractionation column to said heat exchange means as a refrigenant and withdrawing the gaseous oxygen produced by heat exchange as a product oxygen gas. Having the above construction, the present invention affords the following advantages. The oxygen gas production apparatus according to the present invention comprises both an expansion means and a means for feeding liquid oxygen for refrigeration from an external source. The expansion means, which is by nature difficult to operate at a speed varying in quick response to changes in load, is driven at a constant speed at all times so as to maintain its cooling capacity at a constant level, while the amount of feed of liquid oxygen from the liquid oxygen storage means is controlled by means of the liquid level detection-control means to adjust the output of oxygen gas, so that the apparatus can adapt itself quickly to changes in the demand for product oxygen gas without detracting from the purity of product oxygen gas.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings;
FIG. 1 is an elementary
REFERENCES:
patent: 2940269 (1960-06-01), Frainier
patent: 3039274 (1962-06-01), Matsch
patent: 3735599 (1973-05-01), Izumichi et al.
patent: 4526595 (1985-07-01), McNeil
patent: 4529425 (1985-07-01), McNeil
Capossela Ronald C.
Daidousanso Co. Ltd.
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