Refrigeration – Cryogenic treatment of gas or gas mixture – Liquefaction
Reexamination Certificate
2001-12-20
2003-02-25
Doerrler, William C. (Department: 3744)
Refrigeration
Cryogenic treatment of gas or gas mixture
Liquefaction
Reexamination Certificate
active
06523366
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to the provision of refrigeration and is particularly advantageous for providing low temperature or cryogenic refrigeration using a neon-based working fluid to generate the refrigeration.
BACKGROUND ART
The use of low temperature or cryogenic refrigeration is becoming increasingly important in such applications as cooling power transmission cable for superconductivity purposes. Conventional methods for providing refrigeration are generally inadequate when the provision of low temperature refrigeration is desired. Typically, when the generation of low temperature refrigeration is desired, hydrogen or helium is used as the working fluid. These fluids are relatively inexpensive but, because of their low molecular weight, there is an increased difficulty of compressing these fluids. This problem is overcome by increasing the complexity and cost of the compressors used to power the cycle.
Neon has a relatively high molecular weight compared with other very low boiling components such as hydrogen or helium and thus may be more easily compressed for better operation of a refrigeration cycle. Unfortunately, neon is significantly more costly than either hydrogen or helium making its use problematic in a refrigeration cycle. A viable system which will enable the use of neon as the working fluid to generate refrigeration for low temperature refrigeration applications would be highly desirable.
Accordingly, it is an object of this invention to provide an improved system which uses a neon refrigerant fluid to generate refrigeration for use in low temperature, e.g. cryogenic, applications.
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 providing low temperature refrigeration to a use point comprising:
(A) compressing refrigerant fluid comprising neon to produce compressed neon refrigerant fluid, and passing the compressed neon refrigerant fluid to a sealed turboexpander/loader;
(B) expanding the compressed neon refrigerant fluid by passage through the turboexpander of the sealed turboexpander/loader to produce refrigeration bearing neon refrigerant fluid;
(C) warming the refrigeration bearing neon refrigerant fluid by indirect heat exchange with heat transfer fluid to produce cooled heat transfer fluid having low temperature refrigeration; and
(D) passing the cooled heat transfer fluid to a use point and providing low temperature refrigeration to the use point.
Another aspect of the invention is:
Apparatus for providing low temperature refrigeration to a use point comprising:
(A) a compressor and means for providing refrigerant fluid comprising neon to the compressor;
(B) a sealed turboexpander/loader and means for passing neon refrigerant fluid from the compressor to the turboexpander of the sealed turboexpander/loader;
(C) a heat exchanger, means for passing neon refrigerant fluid from the turboexpander of the sealed turboexpander/loader to the heat exchanger, and means for passing heat transfer fluid to the heat exchanger; and
(D) a use point, and means for passing heat transfer fluid from the heat exchanger to the use point.
A further aspect of the invention is:
A sealed turboexpander/loader comprising a turboexpander and a loader coupled together by a shaft, a seal encapsulating the turboexpander, loader and shaft, input means for passing refrigerant fluid to the turboexpander, said input means passing through the seal, and output means for passing refrigerant fluid from the turboexpander, said output means passing through the seal.
As used herein the term “turboexpander” means a device for the flow of high pressure gas through a turbine to reduce the pressure and the temperature of the gas thereby generating refrigeration.
As used herein the term “loader” means a device which receives energy from a turboexpander.
As used herein the term “turboexpander/loader” means a device comprising a turboexpander and loader wherein energy is passed by means of a shaft from the turboexpander to the loader.
As used herein the term “seal” means an essentially air tight structure.
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 “subcooling” means cooling a liquid to be at a temperature lower than the saturation temperature of that liquid for the existing pressure.
As used herein the term “cold box” means an enclosure for cryogenic process equipment used to protect from excessive heat leak.
As used herein the term “buffer vessel” means a vessel used to store a process fluid temporarily dispersing it when needed by the process and storing it when it is not required by the process.
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Bonaquist Dante Patrick
Lynch Nancy Jean
Stanko Michael John
Zia Jalal
Doerrler William C.
Drake Malik N.
Ktorides Stanley
Praxair Technology Inc.
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