Refrigeration – Cryogenic treatment of gas or gas mixture – Separation of gas mixture
Reexamination Certificate
2000-08-16
2001-10-02
Doerrler, William (Department: 3744)
Refrigeration
Cryogenic treatment of gas or gas mixture
Separation of gas mixture
C062S651000
Reexamination Certificate
active
06295838
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to cryogenic air separation and, more particularly, to the integration of cryogenic air separation with a gas turbine system.
BACKGROUND ART
Gas turbines are employed to generate power. In a gas turbine system fuel and oxidant are combusted to form pressurized combustion products which are then expanded in the gas turbine to generate power.
Cryogenic air separation plants may be integrated with gas turbine systems. For example, a common compressor may compress air for combustion in the gas turbine system and also for separation in the cryogenic air separation plant. In addition, one or more products from the cryogenic air separation plant may be used in the gas turbine system. Any improvement in the integration of cryogenic air separation and gas turbine systems would be advantageous.
Accordingly, it is an object of this invention to provide an improved cryogenic air separation and gas turbine integration system.
SUMMARY OF THE INVENTION
The above and other objects, which will become apparent to those skilled in the art upon a reading of this disclosure, are attained by the present invention, one aspect of which is:
A method for operating a cryogenic air separation and gas turbine system comprising:
(A) compressing feed air to produce compressed feed air having heat of compression, and cooling the compressed feed air;
(B) passing the compressed feed air into a cryogenic air separation plant and producing nitrogen by the cryogenic rectification of the feed air within the cryogenic air separation plant;
(C) withdrawing nitrogen from the cryogenic air separation plant and heating the withdrawn nitrogen by indirect heat exchange with the compressed feed air having heat of compression to produce heated nitrogen; and
(D) turboexpanding the heated nitrogen in a gas turbine.
Another aspect of the invention is:
Cryogenic air separation and gas turbine apparatus comprising:
(A) a feed air compressor, a high level heat exchanger, means for passing feed air to the feed air compressor, and means for passing feed air from the feed air compressor to the high level heat exchanger;
(B) a cryogenic air separation plant and means for passing feed air from the high level heat exchanger to the cryogenic air separation plant;
(C) means for passing nitrogen from the cryogenic air separation plant to the high level heat exchanger; and
(D) a gas turbine and means for passing nitrogen from the high level heat exchanger to the gas turbine.
As used herein the term “cryogenic air separation plant” means a facility for fractionally distilling feed air by cryogenic rectification, comprising one or more columns and the piping, valving, etc. attendant thereto.
As used herein the term “column” means a distillation or fractionation column or zone, i.e. a contacting column or zone, wherein liquid and vapor phases are countercurrently contacted to effect separation of a fluid mixture, as for example, by contacting of the vapor and liquid phases on a series of vertically spaced trays plates mounted within the column and/or on packing elements such as structured or random packing. For a further discussion of distillation columns, see Chemical Engineer's Handbook, fifth edition, edited by R. H. Perry and C. H. Chilton, McGraw-Hill Book Company, New York, Section 13,
The Continuous Distillation Process.
The term “double column” is used to mean a higher pressure column having its upper portion in heat exchange relation with the lower portion of a lower pressure column. A further discussion of double columns appears in Ruheman “The Separation of Gases”, Oxford University Press, 1949, Chapter VII, Commercial Air Separation.
Vapor and liquid contacting separation processes depend on the difference in vapor pressures for the components. The high vapor pressure (or more volatile or low boiling) component will tend to concentrate in the vapor phase whereas the low vapor pressure (or less volatile or high boiling) component will tend to concentrate in the liquid phase. Distillation is the separation process whereby heating of a liquid mixture can be used to concentrate the more volatile component(s) in the vapor phase and thereby the less volatile component(s) in the liquid phase. Partial condensation is the separation process whereby cooling of a vapor mixture can be used to concentrate the volatile component(s) in the vapor phase and thereby the less volatile component(s) in the liquid phase. Rectification, or continuous distillation, is the separation process that combines successive partial vaporizations and condensations as obtained by a countercurrent treatment of the vapor and liquid phases. The countercurrent contacting of the vapor and liquid phases can be adiabatic or nonadiabatic and can include integral (stagewise) or differential (continuous) contact between the phases. Separation process arrangements that utilize the principles of rectification to separate mixtures are often interchangeably termed rectification columns, distillation columns, or fractionation columns. Cryogenic rectification is a rectification process carried out at least in part at temperatures at or below 150 degrees Kelvin (K).
As used herein the term “indirect heat exchange” means the bringing of two fluids into heat exchange relation without any physical contact or intermixing of the fluids with each other.
As used herein the term “feed air” means a mixture comprising primarily oxygen and nitrogen, such as ambient air.
As used herein the term “heat of compression” means thermal energy imparted to a fluid as a result of the compression of that fluid.
As used herein the term “turbine” means a device which converts pressure energy of a fluid into shaft energy by expansion of the fluid. The shaft energy can be utilized in driving a compressor and/or a generator for power generation.
As used herein the term “gas turbine” means a turbine wherein combustion products are expanded.
As used herein the term “nitrogen turbine” means a turbine wherein nitrogen but no combustion products is expanded.
As used herein the term “combustor” means an enclosure wherein fuel and oxidant are combusted to form combustion products.
As used herein the term “humidifier” means a device wherein moisture is added to gas.
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Drnevich Raymond Francis
Lynch Nancy Jean
Mahoney Kevin William
Shah Minish Mahendra
Doerrler William
Ktorides Stanley
Praxair Technology Inc.
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