Combustion – Structural installation
Reexamination Certificate
2000-10-25
2002-11-26
Bennett, Henry (Department: 3743)
Combustion
Structural installation
C431S333000, C095S166000
Reexamination Certificate
active
06485292
ABSTRACT:
REFERENCE TO MICROFICHE APPENDIX
This application is not referenced in any microfiche appendix.
BACKGROUND OF THE INVENTION
Previously issued United States Patents that provide background information concerning the technology to which this invention is directed include the following:
PATENT NO.
INVENTOR
TITLE
2,725,337
Laurence et al.
Method and Apparatus for
Low Temperature
Separation and
Stabilization of Liquid
Hydrocarbons from High
Pressure Natural Gas
3,395,512
Finney et al.
Method and Means for
Cooling and Cleaning Hot
Converter Gases
3,904,351
Smith et al.
Combustor and Method of
Eliminating Odors Using
the Same
3,932,111
Liknes et al.
Apparatus for Incinerating
Combustible Wastes
4,003,722
Holter
Process and Arrangement
for the Removal of
Impurities From Gases
4,162,145
Alleman
Regeneration of Liquid
Absorbents
4,182,659
Anwar et al.
Method of Concentrating a
Water-Containing Glycol
4,227,897
Reed
Apparatus for Recovery of
Flared Condensible
Vapors
4,237,620
Black
Contactor
4,280,867
Hodgson
Glycol Regeneration
4,494,967
Barth
Process for the Removal
of Impurities from a Gas
Stream Containing Solvent
Vapors
4,597,733
Dean et al.
Gas Heating System for
Dehydrators and Like
4,676,806
Dean et al.
Temperature Sensitive
Control System for Liquid
Motor and Pump in a
Natural Gas Dehydration
System
4,702,898
Grover
Process for the Removal
of Acid Gases from Gas
Mixtures
4,714,032
Dickinson
Pollution-Free Pressurized
Combustion Utilizing a
Controlled Concentration
of Water Vapor
4,717,408
Hopewell
Process for Prevention of
Water Build-Up in
Cryogenic Distillation
column
4,983,364
Buck et al.
Multi-Mode Combustor
5,163,981
Choi
Method and Apparatus for
Controlling Discharge of
Pollutants from Natural
Gas Dehydrators
5,221,523
Miles et al.
Contaminant Control
System for Natural Gas
Dehydration
5,261,225
Dickinson
Pressurized Wet
Combustion at Increased
Temperature
5,346,537
Lowell
Method and System for
Controlling Emissions
5,514,305
Ebeling
Bubble Tray
5,520,723
Jones, Jr.
Method and System for
Reducing Air Pollution
from Natural Gas
Dehydrators
5,536,303
Ebeling
Method of Low
Temperature
Regeneration of Glycol
Used for Dehydrating
Natural Gas
5,664,426
Lu
Regenerative Gas
Dehydrator
5,665,144
Hill et al.
Method and Apparatus
Utilizing Hydrocarbon
Pollutants from Glycol
Dehydrators
5,766,313
Heath
Hydrocarbon Recovery
System
5,882,486
Moore, Jr.
Glycol Refining
Hodgson, U.S. Pat. No. 4,280,867, discloses a reboiler used to heat wet glycol and water vapor is discharged. The dehydrated glycol then flows through a stripping column where glycol comes into contact with dry flue gas generated by a catalytic burner.
Anwar et al., U.S. Pat. No. 4,182,659, provides a system where wet glycol is initially drawn off into an expansion chamber where part of the hydrocarbon gases separate out, are drawn off and may be re-used as heating gas. The glycol is then heated to remove the majority of the water which is vented to the atmosphere. Finally, then glycol is heated at sub-atmospheric pressure (vacuum) to further purify it.
Holter, U.S. Pat. No. 4,003,722, discloses a system where gas may be purified by cleansing fluid. The cleansing fluid may be admitted from a flow circuit into an evaporator causing the impurities to be evaporated by heating. The impurities liberated in the evaporator are conveyed to a burner or combustion chamber and combusted.
The other previously issued patents provide information as to the state of the art of glycol dehydration of natural gas.
Accordingly, it is a principal object and purpose of the present invention to provide a system for control and disposal on contaminants released by natural gas dehydration processes.
It is further an object and a purpose of the present invention to provide a system for control and disposal of contaminants released in the glycol regeneration process wherein the contaminants are incinerated to reduce them to non-pollutant states.
It is further an object and a purpose of the present invention to provide a system for control and disposal of contaminants released in the glycol regeneration process which will not add undo back pressure to the reboiler.
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a system for use to incinerate contaminants released in the regeneration or reconcentration of glycol, or similar liquid desiccant, employed in the process of dehydration of natural gas.
Natural gas processing usually includes removal of contaminants in order to produce a transportable natural gas product. One of the major contaminants removed from natural gas is water, either in the gaseous state or in condensed form. Other contaminants present in smaller quantities are BTEX and VOCs and other pollutants.
Most large volume dehydration units are of the glycol type. Glycol is a preferred liquid desiccant because it has a relatively high boiling point, is thermally stable and does not oxidize in normal use. The glycol used is normally of one of three kinds: ethylene, diethylene, or triethylene, with triethylene being the most frequently used at the present time. Water, including other pollutants in natural gas, is absorbed by contact with the glycol.
A typical dehydration facility includes an inlet gas scrubber and a separator where liquid accumulations that are easily separated are removed. The natural gas is then directed to a gas contractor where the glycol comes into contact with the gas, a majority of any entrained water and the water vapor being absorbed by the glycol producing what is known as “wet glycol”. The dehydrated natural gas leaves the contractor tower where it is directed to be transported for use as fuel or raw material for the chemical industry. The wet glycol is directed from the contractor tower to a reconcentrator or reboiler column.
In the reboiler column the wet saturated glycol is heated to a temperature of between 380° to 400° Fahrenheit to boil off the water. The reboiler is usually maintained at the lowest possible pressure so that the water solubility of glycol is not increased. The vaporized water, along with the contaminants not removed with the skimming and filtration process, have, in the past, been vented to the atmosphere. Venting the contaminants to the atmosphere is becoming an increasing environmental problem. These odorous vapors emitted from the reboiler create uncomfortable living conditions and health concerns for local residents and workers.
New environmental laws have mandated a great reduction in the amount of pollutants that can be emitted from natural gas dehydrators. These pollutants consist primarily of BTEX and VOCs, and are absorbed from the gas stream by the glycol. Also, some natural gas becomes dissolved in the glycol, and since the function of a dehydrator is to remove water vapor from the gas stream, the glycol will also contain water. The glycol regeneration process utilizes a reboiler to heat the glycol and drive off the water, but the process also liberates the pollutants that are dissolved in the glycol. Current technology to control emissions consists of two methods: 1) The stream from the still column's outlet is condensed. The waste gas is flared and the liquid is trucked to disposal. Or, 2) The stream from the still column's outlet is condensed and the waste gas is compressed and injected into a gas sales line, the liquid, once again, being trucked to disposal. Obviously, the problem with both systems is dealing with the disposal of the BTEX and/or VOCs laden water. It is to this problem that the present invention is directed.
REFERENCES:
patent: 2393231 (1946-01-01), Breese
patent: 2470682 (1949-05-01), Breese
patent: 2725337 (1955-11-01), Laurence et al.
patent: 3190342 (1965-06-01), Smith
patent: 3395512 (1968-08-01), Finney, Jr. et al.
patent: 3904351 (1975-09-01), Smith et al.
patent: 3932111 (1976-01-01), Liknes et al.
patent: 4003722 (1977-01-01), Holter
patent: 4021189 (1977-05-01), Swann et al.
patent: 4118173 (1978-10-01), Shakiba
patent: 4162145 (1979-07-01), Alleman
patent: 4182659 (1980-01-01), Anwer et al.
patent: 4227897 (1980-10-01), Re
McDonald Randy L.
Polk Stafford E.
Rhodes James E.
Bennett Henry
Ferko Kathryn
Head Johnson & Kachigian
Process Equipment & Service Company, Inc.
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