Refrigeration – Cryogenic treatment of gas or gas mixture – Separation of gas mixture
Reexamination Certificate
1999-09-03
2001-07-24
McDermott, Corrine (Department: 3744)
Refrigeration
Cryogenic treatment of gas or gas mixture
Separation of gas mixture
Reexamination Certificate
active
06263701
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH FOR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
The present invention pertains to the field of distillation of fluid mixtures, and in particular to processes for the production of electronic-grade oxygen or other ultra-high purity fluids from a standard-grade supply.
Liquefied atmospheric gases are increasingly used in the electronics industry. Frequently, however, the time required to build a new, full-scale, gas plant is too long or the initial gas requirements of an electronics facility are much less than the ultimate capacity of such a gas plant. In these instances, there is a need for a small system which can convert locally available standard-grade liquid into electronic-grade liquid. Typically, standard-grade liquids contain quantities of light impurities and heavy impurities which are considered undesirable for electronics applications.
There are several prior art processes for the production of electronic-grade oxygen, often called ultra-high purity oxygen. Several processes are directed to producing the oxygen (and sometimes also nitrogen) by cryogenic distillation of air, not by purification of standard-grade oxygen. Examples include: U.S. Pat. Nos. 4,560,397; 4,615,716; 4,977,746; 5,049,173; and 5,195,324. Production of electronic-grade oxygen by direct separation from air can be efficient but requires a relatively long procurement and construction schedule.
Some processes aimed at the direct production of electronic-grade oxygen from standard-grade liquid oxygen also have been disclosed in the prior art. Examples include: U.S. Pat. Nos. 4,780,118; 4,867,772; 4,869,741 and 5,682,763.
U.S. Pat. No. 4,780,118 discloses a process which uses two columns configured in a direct sequence. The feedstock enters the first column, which rejects the light impurities, from the top. The bottom stream from the first column, which is light-lean and contains oxygen and heavy impurities, is passed to the second column, from which the desired oxygen product is recovered from the top. The first column is fitted with a reboiler, and the second column is fitted with a condenser.
U.S. Pat. No. 4,867,772 discloses a process which uses two columns configured in an indirect sequence. The feedstock enters the first column, which rejects the heavy impurities, from the bottom. The top stream from the first column, which is heavy-lean and contains oxygen and light impurities, is passed to the second column, from which the desired oxygen product is recovered from the bottom. The first column is fitted with a condenser, and the second column has both a reboiler and a condenser.
U.S. Pat. No. 4,869,741 discloses a process which uses two columns configured as a main column and a side stripper. Both columns operate at the same pressure. Use of a side stripper eliminates one condenser.
For energy efficiency, U.S. Pat. Nos. 4,780,118; 4,867,772; and 4,869,741 utilize a closed loop heat pump to operate the reboilers and condensers.
U.S. Pat. No. 5,682,763 discloses a number of distillation configurations, some of which have been described previously. The improvement disclosed by U.S. Pat. No. 5,682,763 is the use of an external process stream to drive the reboiler and condenser—thereby eliminating the compression equipment associated with the previous disclosures.
It is desired to have a more economical means of removing light impurities and heavy impurities from standard-grade supply.
It is further desired to have improved processes for the purification of oxygen to produce electronic-grade oxygen.
It is still further desired to have improved processes for the purification of other fluids.
It also is desired to have improved processes for the production of electronic-grade oxygen or other ultra-high purity fluids which processes overcome the difficulties and disadvantages of the prior art processes to provide better and more advantageous results.
BRIEF SUMMARY OF THE INVENTION
The present invention is a process for the production of electronic-grade oxygen or other ultra-high purity fluids from a standard-grade supply.
A first embodiment of the invention is a process for recovering a purified stream of a first component having a first volatility from a multicomponent fluid containing the first component in a concentration of at least 90 mole %, at least one lighter component having a volatility higher than the first volatility, and at least one heavier component having a volatility lower than the first volatility. The process uses a first distillation column operating at a first pressure and a second distillation column operating at a second pressure. The first and second distillation columns are thermally linked and each distillation column has a top, a bottom, and at least one distillation section between the top and the bottom. The process comprises multiple steps. The first step is to feed the multicomponent fluid to the first distillation column. The second step is to separate from the multicomponent fluid in the first distillation column substantially all of the at least one lighter component or substantially all of the at least one heavier component, thereby forming a mixture stream substantially free of the at least one lighter component or substantially free of the at least one heavier component. The third step is to withdraw the mixture from the first distillation column. The fourth step is to feed the mixture stream into the second distillation column. The fifth step is to remove from the second distillation column a first stream substantially pure in the first component. The sixth step is to remove from the second distillation column a second stream enriched in the at least one lighter component or in the at least one heavier component. The seventh step is to remove from the first distillation column a third stream enriched in the at least one lighter component or in the at least one heavier component, wherein the first volatility is between the volatility of the at least one component enriching the second stream and the volatility of the at least one component enriching the third stream.
For example, the first component may be oxygen. The at least one lighter component may be selected from the group consisting of nitrogen, carbon monoxide, helium, hydrogen and argon. The at least one heavier component may be selected from the group consisting of carbon dioxide, nitrogen oxides, and hydrocarbons, said hydrocarbons being selected from the group consisting of methane, ethane ethylene, propane, and propylene.
In a second embodiment, which includes the same multiple steps as the first embodiment, the first pressure is higher than the second pressure. The first and second distillation columns in the second embodiment are thermally linked by condensing at least a portion of a vapor stream from the top of the first distillation column by indirect heat exchange against at least a portion of a liquid in the bottom of the second distillation column.
In a third embodiment, which includes the same multiple steps as the first embodiment, the first pressure is lower than the second pressure. The first and second distillation columns in the third embodiment are thermally linked by condensing at least a portion of a vapor stream from the second distillation column by indirect heat exchange against at least a portion of a liquid in the bottom of the first distillation column.
A fourth embodiment of the invention is a process for producing an electronic-grade oxygen from standard-grade oxygen containing at least one light impurity and/or at least one heavy impurity. The process uses a first distillation column and a second distillation column. The first and second distillation columns each have a top and a bottom, and are thermally linked by condensing at least a portion of a vapor stream from the top of the second distillation column by indirect heat exchange against at least a portion of a liquid in the bottom of the first distillation column. The process comprises multiple steps. The firs
Agrawal Rakesh
Herron Donn Michael
Air Products and Chemicals Inc.
Drake Malik N.
Jones II Willard
McDermott Corrine
LandOfFree
Process for the purification of a major component containing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the purification of a major component containing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the purification of a major component containing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2482846