Gas separation: processes – Liquid contacting – And degasification of a liquid
Reexamination Certificate
1999-05-07
2001-04-03
Smith, Duane S. (Department: 1724)
Gas separation: processes
Liquid contacting
And degasification of a liquid
C095S174000, C095S177000, C095S192000, C095S236000, C096S234000
Reexamination Certificate
active
06210467
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to the production of carbon dioxide.
BACKGROUND ART
Carbon dioxide has a large number of uses. For example, carbon dioxide is used to carbonate beverages, to chill, freeze and package seafood, meat, poultry, baked goods, fruits and vegetables, and to extend the shelf-life of dairy products. It is an important environmental component in industrial waste and process water treatment as a replacement for sulfuric acid to control pH levels. Other uses included drinking water treatment, an environmentally-friendly pesticide and an atmosphere additive in greenhouses to improve the growth of vegetables.
Generally carbon dioxide is produced by purifying a waste stream which is a by-product of an organic or inorganic chemical process. The waste stream comprises carbon dioxide and water soluble contaminants from the chemical process, and the carbon dioxide must be cleaned of these contaminants prior to recovery. The cleaning results in the loss of some of the carbon dioxide.
As the demand for carbon dioxide continues to increase, more effective and efficient carbon dioxide cleaning systems are desirable in order to cost effectively improve the recovery of the carbon dioxide.
Accordingly it is an object of this invention to provide a system which can effectively process a crude carbon dioxide feed stream which contains water soluble contaminants in a more efficient manner than that possible with conventional carbon dioxide processing systems thereby improving the recovery of the carbon dioxide.
SUMMARY OF THE INVENTION
The above and other objects, which will become apparent to one skilled in the art upon a reading of this disclosure, are attained by the present invention, one aspect of which is:
A method for recovering carbon dioxide from a gas stream comprising:
(A) compressing a gas stream comprising carbon dioxide, water vapor and water soluble contaminants to produce a compressed gas stream;
(B) cooling the compressed gas stream to condense at least some of the water vapor, and separating the resulting two-phase fluid into a carbon dioxide-richer gas stream containing water soluble contaminants, and into a remaining liquid;
(C) passing the carbon dioxide-richer gas stream into and up an absorption column, passing water into and down the absorption column, and passing water soluble contaminants and some carbon dioxide from the upflowing carbon dioxide-richer gas stream into the downflowing water within the absorption column to produce cleaned carbon dioxide and contaminant-bearing water containing carbon dioxide gas absorbed therein;
(D) withdrawing and recovering cleaned carbon dioxide from the absorption column; and
(E) withdrawing contaminant-bearing water from the absorption column, reducing the pressure of the contaminant-bearing water, releasing absorbed carbon dioxide gas from the contaminant-bearing water, and passing the released carbon dioxide gas into the carbon dioxide-richer gas stream for passage into the absorption column.
Another aspect of this invention is:
Apparatus for cleaning carbon dioxide comprising:
(A) a compressor and means passing a feed stream comprising carbon dioxide, water vapor and water soluble contaminants to the compressor;
(B) an aftercooler, a phase separator, means for passing fluid from the compressor to the aftercooler, and means for passing fluid from the aftercooler to the phase separator;
(C) an absorption column, means for passing fluid from the phase separator into the lower portion of the absorption column, and means for passing water into the upper portion of the absorption column;
(D) means for recovering cleaned carbon dioxide from the upper portion of the absorption column; and
(E) a pressure reducing device, means for passing fluid from the lower portion of the absorption column to the pressure reducing device, and means for passing fluid from the pressure reducing device to the phase separator.
As used herein, the term “absorption column” means a vessel wherein a gas and liquid are contacted to transfer one or more components from the gas to the liquid. Typically, the contact will be with upward flow of gas and downward flow of liquid on mass transfer elements such as random or structured packing or trays.
As used herein, the term “phase separator” means a vessel wherein a two phase feed can be separated into its separate gas and liquid fractions. Typically, the phase separator will be a vessel with sufficient cross-sectional area so that the gas and liquid will be disengaged by gravity, with liquid removal at the bottom and vapor removal at the top of the vessel.
As used herein, the term “water soluble contaminants” means any gaseous contaminant that is appreciably soluable in water such as methanol or ethanol.
As used herein, the terms “upper portion” and “lower portion” mean those sections of a column respectively above and below the mid point of the column.
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 “aftercooler” means an indirect heat exchanger wherein a compressed gas stream comprising water vapor is cooled and at least some of the water vapor is condensed.
As used herein, the term “light contaminants” means one or more species having a vapor pressure greater than that of carbon dioxide. Examples of light contaminants include nitrogen, oxygen, argon, hydrogen, carbon monoxide and methane.
REFERENCES:
patent: 3593491 (1971-07-01), Tennyson
patent: 3770622 (1973-11-01), Freireich et al.
patent: 4080424 (1978-03-01), Miller et al.
patent: 4184855 (1980-01-01), Butwell et al.
patent: 4252548 (1981-02-01), Markbreiter et al.
patent: 4305733 (1981-12-01), Scholz et al.
patent: 4528002 (1985-07-01), Linde
patent: 4548620 (1985-10-01), Albiol
patent: 4589896 (1986-05-01), Chen et al.
Nonhebel, “Gas Purification Processes”, 1964, pp. 250-274.
Zawacki et al., “Process Optimized for High Pressure Gas Cleanup”, Hydrocarbon Processing, Apr., 1981.
Ktorides Stanley
Praxair Technology Inc.
Smith Duane S.
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