U.S. patent application number 13/066217 was filed with the patent office on 2011-10-13 for ultra-low emission natural gas dehydration unit with continuously fired reboiler.
Invention is credited to Joseph A. Witherspoon.
Application Number | 20110247489 13/066217 |
Document ID | / |
Family ID | 44759970 |
Filed Date | 2011-10-13 |
United States Patent
Application |
20110247489 |
Kind Code |
A1 |
Witherspoon; Joseph A. |
October 13, 2011 |
Ultra-low emission natural gas dehydration unit with continuously
fired reboiler
Abstract
A natural gas dehydration system and method includes a
contactor, a flash tank, and a still interconnected by a desiccant
circulation system. A continuously fired reboiler is coupled to the
still and the flash tank to bum the flash gas from the flash tank
and heat the desiccant.
Inventors: |
Witherspoon; Joseph A.;
(Kaysville, UT) |
Family ID: |
44759970 |
Appl. No.: |
13/066217 |
Filed: |
April 8, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61322022 |
Apr 8, 2010 |
|
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Current U.S.
Class: |
95/18 ; 95/91;
96/112; 96/118 |
Current CPC
Class: |
B01D 2252/2026 20130101;
B01D 53/263 20130101; C10L 3/106 20130101 |
Class at
Publication: |
95/18 ; 96/118;
96/112; 95/91 |
International
Class: |
B01D 53/26 20060101
B01D053/26 |
Claims
1. A natural gas dehydration system, comprising: a contactor, a
flash tank, and a regeneration system interconnected by a desiccant
circulation system with dry desiccant entering the contactor along
with wet gas to absorb water vapor and leave the contactor as wet
desiccant, the wet desiccant entering and leaving the flash tank
with flash gas separating in the flash tank, and the wet desiccant
entering the regeneration system with the water vapor vaporizing
and leaving as dry desiccant returning to the contactor; and a
continuously fired reboiler coupled to a still and the flash tank
to burn the flash gas from the flash tank and regenerate the
desiccant.
2. A natural gas dehydration system as defined in claim 1, further
comprising a flash-gas driven pump coupled to the desiccant
circulation system to pump the desiccant.
3. A natural gas dehydration system as defined in claim 1, further
comprising a control system coupled to the reboiler to maintain a
temperature of the desiccant above a predetermined minimum
temperature.
4. A natural gas dehydration system as defined in claim 1, further
comprising a flash gas contactor disposed on the flash tank.
5. A natural gas dehydration system, comprising: a contactor
coupled to a wet gas source and a lean tri-ethylene glycol (TEG)
source, and coupled to a dry gas storage and a first rich TEG
outlet; a flash tank coupled to the rich TEG outlet of the
contactor and coupled to a second rich TEG outlet and a flash gas
outlet; a still coupled to the second rich TEG outlet; a
continuously fired reboiler coupled to the still and a flash-gas
contactor configured to burn the flash gas to heat the rich TEG
from the second TEG outlet and vaporize the water vapor and leave
lean TEG; and a TEG circulation system disposed between the
contactor, the flash tank, the still and the reboiler.
6. A natural gas dehydration system as defined in claim 5, further
comprising a flash-gas driven pump coupled to the TEG circulation
system to pump the desiccant, including hot desiccant for heat
trace and lean desiccant to the flash-gas contactor.
7. A natural gas dehydration system as defined in claim 5, further
comprising a control system coupled to the reboiler to maintain a
temperature of the desiccant above a predetermined minimum
temperature.
8. A natural gas dehydration system as defined in claim 5, further
comprising a flash gas contactor disposed on the flash tank.
9. A method for dehydrating natural gas, comprising the steps of:
circulating a desiccant between a contactor, a flash tank, and a
still with a reboiler; introducing wet gas into the contactor with
dry or lean desiccant, the dry or lean desiccant absorbing water
vapor from the wet gas resulting in a rich or wet desiccant and dry
gas; extracting flash gas from rich or wet desiccant in the flash
tank; removing the water vapor from the rich or wet desiccant in
the still by heating the rich or wet desiccant to vaporize the
water vapor resulting in the dry or lean desiccant; recirculating
the dry or lean desiccant from the still to the contactor; and
continuously firing the reboiler with the flash gas from the flash
tank.
10. A method as defined in claim 9, further comprising the step of
circulating lean desiccant from the still to a flash gas contactor
disposed on the flash tank during winter.
11. A method as defined in claim 9, further comprising the step of
maintaining a temperature of the desiccant in the reboiler within
at least a 10.degree. C. temperature range.
12. A method as defined in claim 9, further comprising the step of
pumping the desiccant as a heating fluid with a flash-gas driven
pump, and without a jet-gas circulation system and without a
dry-gas driven circulation pump.
13. A method as defined in claim 9, further comprising the step of
washing and drying the flash gas to remove moisture and heavy
hydrocarbons in the winter.
14. A method as defined in claim 9, further comprising the step of
burning all of the flash gas in the reboiler without venting or
flaring the flash gas.
Description
1. RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional Pat.
App. Ser. No. 61/322,022, filed Apr. 8, 2010, and entitled "NATURAL
GAS DEHYDRATION UNIT WITH CONTINUOUSLY FIRED REBOILER."
BACKGROUND
[0002] 2. The Field of the Invention
[0003] This invention relates to natural gas dehydration units and,
in particular, to the emission control of Volatile Organic
Compounds (VOC's) and Benzene from natural gas dehydration units in
remote field locations.
[0004] 3. The Background Art
[0005] Natural gas from underground resources is commonly mixed
with other hydrocarbons, such as ethane, propane, butane, and
pentanes; water vapor; hydrogen sulfide; carbon dioxide; helium;
nitrogen; etc. The gas is often transported through a network of
pipelines that can stretch thousands of miles. The gas is usually
processed to separate the various hydrocarbons and fluids to
produce pipeline quality dry natural gas.
[0006] The Gas Processors Association (GPA) sets forth pipeline
quality specifications for gas that the water content should not
exceed 7 lb/MMSCF. The natural gas from underground resources
usually contains a large amount of water, and can be completely
saturated with water vapor. The water can cause problems to the
pipeline, such as freezing at low temperatures, and forming
hydrates with carbon dioxide and hydrocarbons that can clog
equipment and pipes or cause corrosion.
[0007] In the cold northern regions of the United States and
Canada, remote field location dehydration units are often used to
remove the water vapor from the gas between the wellhead and the
raw-gas gathering system pipelines. These gathering systems
comprise of thousands of linear miles of pipelines in each
gathering area which direct the raw gas to the gas processing and
separations facility. An initial dehydration of the raw gas must be
accomplished in the cold-climate regions, especially during the
winter, in order to prevent water condensation and freezing within
the gathering system.
[0008] One method of removing water vapor utilizes a liquid
desiccant dehydrator, such as a glycol dehydrator. Glycol, which
has an affinity for water, is used to absorb the water vapor from
the natural gas. The natural gas and glycol are brought together in
a contactor. The desiccant or glycol bearing the water out of the
contactor is referred to as rich or wet. The pure or lean glycol
flows from the top of the contactor down to the bottom of the
contactor, absorbing water out of the gas as the gas flow from the
bottom of the contactor to the top of the contactor. The water-rich
glycol at the bottom of the contactor is referred to as rich or wet
glycol. The rich or wet glycol is removed from the bottom of the
contactor. The gas with the water vapor removed is referred to as
dry gas and exits the top of the contactor to the gathering system
pipeline.
[0009] Methane and other hydrocarbon compounds, including volatile
organic compounds and benzene, are typically absorbed by the glycol
and are found in the rich or wet glycol. A glycol flash tank can
also be used to remove significant amounts of methane and other
hydrocarbon compounds from the rich glycol that has been removed
from the contactor by reducing the pressure of the glycol, allowing
the methane and other hydrocarbons to vaporize or flash out of the
liquid phase.
[0010] The gas that flashes out of the rich glycol can be used as a
fuel source at the glycol regenerator. The rich or wet glycol is
fed to a still or distillation column which is the first stage of
the glycol regeneration system. The glycol regeneration system
consists of a still or distillation column equipped with a fuel-gas
fired reboiler. The regenerator system vaporizes the water vapor
and hydrocarbon compounds from the rich glycol using the
boiling-point differences between the water and the glycol. Water
has a boiling point of around 100.degree. C. (212.degree. F.),
while glycol has a boiling point of around 204.degree. C.
(400.degree. F.). One problem with prior art regenerators is that
the reboiler runs sporadically (i.e., turns on and off), such that
the glycol temperature can vary by about 10.degree. C. (50.degree.
F.). When the reboiler is off, there is no fuel gas flowing to the
burner of the reboiler. The flash gas that is being burned as fuel
gas when the reboiler is on or firing is vented to the atmosphere
or has to be routed to a vapor destruction combustor when the
reboiler is off or not firing.
[0011] A problem with the flash gas from prior art glycol flash
tanks is that the flash gas is saturated with water vapor. During
winter operation, the water in the flash gas will condense in the
fuel gas system and will freeze at low temperatures. Frozen water
or ice in the fuel gas system piping blocks the flow of fuel gas to
the burner of the reboiler and turns the reboiler off. If there is
not enough heat to keep the glycol system warm, the entire unit
will freeze up and shut down. For this reason, the flash tank in
the prior art units are by-passed during the winter months and the
flash gas is vented to atmosphere or routed to a vapor destruction
combustor.
[0012] Dehydration systems also commonly use a jet-gas system or
gas-driven pumps which requires a large mass flow of dry gas to
circulate hot glycol as a heating fluid in the winter. The jet gas
and power gas significantly contribute to the overall VOC and
Benzene emissions of the glycol dehydration unit.
[0013] Enhancement methods to dehydration systems often involve
lowering the pressure in the system to increase stripping, using a
vacuum to lower the entire still pressure, using stripping gas,
using a recoverable hydrocarbon solvent, or withdrawing partially
condensed vapors from the bulk liquid in the reboiler. The use of
stripping gas significantly contributes to the overall VOC and
benzene emissions of the glycol dehydration unit.
[0014] In addition, cold climates require more thorough and
expensive glycol dehydration. Furthermore, new environmental
regulations require the removal of BTEX (benzene, toluene, ethylene
and xylene) compounds from the still vents of natural gas
dehydrators.
[0015] Improving the dehydration process is an ongoing
endeavor.
SUMMARY OF THE INVENTION
[0016] It has been recognized that it would be advantageous to
develop an ultra-low emission glycol dehydration unit. In addition,
it has been recognized that it would be advantageous to develop a
dehydration unit that continuously utilizes all of the flash gas at
the burner of the reboiler; maintains glycol temperature;
eliminates the jet-gas system and power-gas pump for hot glycol
circulation; uses a flash gas contactor to provide usable fuel gas
to the reboiler, even during the winter; and utilizes the existing
glycol pump to circulate hot glycol as a heating fluid to prevent
freezing of piping and equipment during the winter that can be
bypassed in the summer.
[0017] An embodiment of the invention provides a natural gas
dehydration system including a main desiccant-to-gas contactor, a
desiccant flash tank, and flash-gas contactor, and a desiccant
regeneration system interconnected by a desiccant circulation
system. Dry desiccant (such as pure or lean tri-ethylene glycol or
TEG) enters the main contactor along with wet gas to absorb water
vapor and leave the contactor as wet desiccant (such as rich TEG).
The wet desiccant enters and leaves the flash tank with flash gas
separating in the flash tank. The wet desiccant enters the
regeneration system with the water vapor vaporizing, and leaves as
dry desiccant returning to the main contactor. A continuously fired
reboiler is coupled to the regeneration system and the flash tank
to burn the flash gas from the flash tank and heat the desiccant,
thus regenerating the desiccant to a relatively pure state.
[0018] In accordance with a more detailed aspect of the present
invention, the system may include a flash gas contactor disposed in
relation to the flash tank and coupled to the dry desiccant.
[0019] An embodiment of the present invention provides a method for
dehydrating natural gas, including circulating a desiccant (such as
TEG) between a contactor, a flash tank and a still with a reboiler.
Wet gas is introduced into the contactor with dry desiccant (such
as lean TEG) absorbing water vapor from the wet gas resulting in a
wet desiccant (such as rich TEG) and dry gas. Flash gas is
extracted from the wet desiccant in the flash tank. The water vapor
is removed from the wet desiccant in the still by heating the wet
desiccant to vaporize the water vapor resulting in the dry
desiccant. The dry desiccant is recirculated from the reboiler of
the regeneration system to the contactor. The reboiler is
continuously fired with the flash gas from the flash tank. Since
the reboiler is continuously fired, sufficient stripping gas is
generated from the wet glycol in the reboiler; thus, additional or
supplemental stripping gas is not required to adequately regenerate
the glycol.
[0020] In accordance with a more detailed aspect of the present
invention, the method includes flowing dry desiccant to a flash gas
contactor on the flash tank, thus absorbing water from the flash
gas and rendering the flash gas as a usable fuel gas during winter
operation and effectively destroying the flash gas without venting
the gas to atmosphere and without requiring a waste-gas combustor
for VOC and benzene destruction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The foregoing and other objects and features of the present
invention will become more fully apparent from the following
description and appended claims, taken in conjunction with the
accompanying drawing. Understanding that the drawing depicts only
typical embodiments of the invention and is, therefore, not to be
considered limiting of its scope, the invention will be described
with additional specificity and detail through use of the
accompanying drawing in which:
[0022] FIG. 1 is a process flow diagram of a natural gas
dehydration system in accordance with an embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0023] It will be readily understood that the components of the
present invention, as generally described and illustrated in the
drawing herein, could be arranged and designed in a wide variety of
different configurations. Thus, the following more detailed
description of the embodiments of the system and method of the
present invention, as represented in the drawing, is not intended
to limit the scope of the invention, but is merely representative
of various embodiments of the invention. The illustrated
embodiments of the invention will be best understood by reference
to the drawing, wherein like parts are designated by like numerals
throughout.
[0024] As illustrated in FIG. 1, a natural gas dehydration system,
indicated generally at 10, in an example implementation in
accordance with the invention is shown for dehydrating natural gas.
Such a system can be used in the field at remote operations
adjacent one or more well heads for processing natural gas prior to
transporting in a pipeline. Alternatively, the system can be used
with a plant and can vent hydrocarbon vapors to a relief or fuel
gas system. The system can be an ultra-low emission glycol
dehydration unit that can sufficiently dehydrate raw, compressed
natural gas to less than 7 lbs water/MMSCF gas with total
hydrocarbon (THC) emissions of less than six tons per year. In
contrast, normal THC emissions are 20 to 80 tons per year. In
addition, the system can provide an ultra-low emission rate and
sufficient dehydration for up to 12 MMSCFD of wet gas at 300 PSIG
operating pressure, or up to 40 MMSCFD of wet gas at 1000 psig
operating pressure. The system can be an absorption type
dehydration system using a liquid desiccant, such as glycol or
tri-ethylene glycol (TEG).
[0025] Generally speaking, the system 10 can include a contactor
14, a flash tank 18, and a regeneration system 22 with a still 26,
an overhead vapor condenser 30 and a reboiler 34. A desiccant or
TEG circulation system 58 can interconnect the various components
with pipe or tubing. The contactor 14 can be coupled to a wet gas
source 42, such as a compressor discharge, and a lean tri-ethylene
glycol (TEG) source, such as the still 26 or regenerator 22. In
addition, the contactor 14 is coupled to a dry-gas storage, such as
the pipeline 46, and a rich TEG outlet that can be coupled to the
still 26 or regenerator 22. Dry or lean TEG enters the contactor 14
along with wet gas with the TEG absorbing water vapor from the wet
gas. After absorbing the water vapor, the TEG becomes wet or rich
TEG and accumulates at the bottom of the contactor 14 where it
leaves or is withdrawn. The gas with the water vapor removed
becomes dry gas and leaves or is withdrawn from the contactor 14.
Thus, lean TEG enters the contactor 14, absorbs water vapor and
leaves the contactor as rich TEG. Similarly, wet gas enters the
contactor 14, has its water vapor absorbed by the TEG, and exits
the contactor as dry gas. The wet gas may first pass through an
inlet gas separator 50 coupled between the gas source 42 and the
contactor 14. The dry gas leaving the contactor 14 and the lean TEG
entering the contactor can pass through a gas/glycol heat exchanger
54 which superheats the dry gas and cools the lean TEG.
[0026] A pump 58 can be coupled to the TEG circulation system to
pump lean TEG into the contactor 14 and rich TEG out of the
contactor. The wet TEG is withdrawn from the contactor 14 and
directed to the flash tank 18 where flash gas separates from the
wet TEG. The flash tank 18 can be coupled to rich TEG outlet of the
contactor 14, and can have a rich TEG outlet and a flash gas
outlet. The rich TEG can pass through a glycol/glycol heat
exchanger 62 along with lean TEG from the still 26 on the way to
the contactor 14 where the rich TEG temperature is increased and
the pressure decreased. For example, the rich TEG temperature can
increase between about 37.degree. C. and about 44.degree. C.
(between about 100.degree. F. and about 110.degree. F.), such as
from between about 33.degree. C. and about 93.degree. C. (between
about 92.degree. F. and about 200.degree. F.).
[0027] In addition, a flash gas contactor 66 can be coupled to the
flash tank 18. The flash gas contactor 66 can be coupled to the
source of lean TEG to the contactor 14 and an outlet for the flash
gas. A heat-trace system with a bypass system can be coupled
in-line between the lean TEG to the flash gas contactor 66. The
flash gas can be coupled to a fuel gas scrubber and outlet to a
fuel tank or pipeline, which in turn, can be coupled to the burner
of the reboiler 34 as discussed below. The flash gas contactor 66
provides usable fuel gas to the re-boiler, even during winter
operations.
[0028] The rich TEG leaving the flash tank 18 can pass through one
or more filters, such as a glycol filter 70 and a glycol charcoal
filter 74 to remove impurities that may clog or foul piping or
equipment. In addition, the rich TEG can pass through a
glycol/glycol heat exchanger 78 coupled to the lean TEG from the
still 26 to the contactor 14. Again, the rich TEG temperature is
increased and the pressure decreased. For example, the rich TEG
temperature can increase between about 54.degree. C. and about
60.degree. C. (between about 130.degree. F. and about 140.degree.
F.), such as from between about 86.degree. C. and about 163.degree.
C. (between about 188.degree. F. and about 325.degree. F.). Thus,
from the contactor 14 to the still 26 or regeneration system 22,
the rich TEG temperature can increase between about 110.degree. C.
and about 116.degree. C. (between about 230.degree. F. and about
240.degree. F.).
[0029] The rich TEG enters the still 26 and the absorbed water and
hydrocarbon compounds vaporize out of the TEG. The still 26 is
coupled to the rich TEG outlet of the flash tank 18. The water and
hydrocarbon vapor can vent out the top of the still 26 to the
overhead vapor condenser 30 that is also coupled to the dry gas
leaving the contactor 14. The water vapor can be accumulated in a
liquid accumulator 82 with any waste gas vented or flared, and the
liquid pumped to a condensate storage tank 86.
[0030] The reboiler 34 takes TEG in the still 26, heats it, and
returns it to the still 26. Heating the TEG causes the water vapor
to boil off the TEG. The reboiler 34 can be coupled to the flash
tank 18 and can burn the flash gas. All of the flash gas can be
burned in the reboiler 34, without venting or flaring the flash
gas. The reboiler 34 can be configured to preferentially consume
glycol flash gas over make-up fuel gas. The reboiler 34 can be a
continuously fired reboiler 34 that maintains a consistent
temperature of the TEG in the reboiler 34. A control system can be
coupled to the reboiler 34 to maintain a temperature of the TEG
above a predetermined minimum temperature. As described above,
prior art reboilers operate sporadically burning mostly dry make-up
gas from the dry-gas system 46, resulting in temperature
differences of up to about 10.degree. C. (about 50.degree. F.) in
the TEG which yields un-regenerated TEG and does not consume the
flash gas from the flash tank 18. Additionally, a reboiler 34 that
is continuously fired does not generally require the use of
supplemental stripping gas (typically dry gas injected into the
reboiler) in order to sufficiently regenerate the glycol. The lean
or dry TEG is withdrawn from the still 26 into a glycol surge tank,
and directed back to the contactor 14 through the heat exchangers
78 and 62 and pump 58. In addition, a side-stream of lean TEG is
fed from the pump 58 to the flash gas contactor 66. The pump 58 is
used to circulate hot TEG as a heating fluid or heat trace to the
equipment and piping that are at risk of freezing during winter
operation, and can be bypassed during summer operation.
[0031] Hydrocarbon liquids are removed from the separator 50,
accumulator, glycol flash tank, fuel-gas system and power-gas
system.
[0032] A method for dehydrating natural gas, and for using the
system described above, includes: [0033] 1) introducing wet gas
with water vapor and lean tri-ethylene glycol (TEG) into a
contactor 14 and allowing the lean TEG to absorb water vapor from
the wet gas resulting in rich TEG with absorbed water and dry gas;
[0034] 2) extracting the dry gas and the rich TEG from the
contactor 14; [0035] 3) introducing the rich TEG into a flash tank
18; [0036] 4) separating flash gas from the rich TEG in the flash
tank 18; [0037] 5) directing the rich TEG from the flash tank 18 to
a still 26 with a reboiler 34; [0038] 6) heating the rich TEG in
the reboiler 34 to vaporize the water and hydrocarbon compounds
from the rich TEG resulting in dry or lean TEG; [0039] 7) directing
the dry or lean TEG from the still 26 back to the contactor 14; and
[0040] 8) continuously heating the TEG by continuously firing the
reboiler 34 with dry flash gas from the flash-gas contactor 66.
[0041] The temperature of the TEG in the reboiler 34 can be
maintained within at least a 10.degree. C. (50.degree. F.)
temperature range. In addition, dry TEG from the pump 58 can be
circulated to a flash gas contactor 66 disposed in relation to the
flash tank 18, such as during winter. The TEG can be pumped through
the circulation system, and through the heat trace to the flash gas
contactor 66, with a pump, and without a jet-gas system and without
a dry-gas driven pump. Furthermore, the flash gas can be washed and
dried, particularly in the winter, to remove moisture and heavy
hydrocarbons. In addition, all of the flash gas can be burned in
the reboiler 34, without venting or flaring the flash gas.
[0042] Embodiments of the present invention may be configured to
sufficiently dehydrate raw, compressed natural gas to less than 7
lbs. Water/MMSCF gas with total hydrocarbon (THC) emissions of less
than about 6 tons per year (normally, between about 20 and 80 tons
per year) using tri-ethylene glycol as the absorbent/desiccant up
to about 12 MMSCFD of wet gas at 300 psig operating pressure and up
to about 40 MMSCFD of wet gas at 1000 psig operating pressure. The
present invention is also applicable to remote, field-installed
units with field automation. Plant installed units of the present
invention may also be configured to vent hydrocarbon vapors to a
relief or fuel-gas system.
[0043] One embodiment of a method for dehydrating natural gas of
the present invention may include the steps of: (1) introducing wet
gas 42 with water vapor and lean tri-ethylene glycol (TEG) into a
contactor 14 and allowing the lean TEG to absorb water vapor from
the wet gas 42 resulting in rich TEG with water vapor and dry gas
46; (2) extracting the dry gas 46 and the rich TEG from the
contactor 14; (3) introducing the rich TEG into a flash tank 18;
(4) separating flash gas from the rich TEG in the flash tank 18;
(5) directing the rich TEG from the flash tank 18 to a still 26
with a reboiler 34; (6) heating the rich TEG in the reboiler 34 to
vaporize the water in the rich TEG resulting in dry TEG; (7)
directing the dry TEG from the still 26 back to the contactor 14;
and (8) continuously heating the TEG by continuously firing a
reboiler 34 with the flash gas from the flash tank 18. Such
embodiment of a method for dehydrating natural gas of the present
invention may further involve the steps of (1) circulating lean TEG
from the regeneration system 22 to a flash gas contactor 66
disposed on the flash tank during winter; (2) maintaining a
temperature of the TEG in the reboiler 34 within at least a
10.degree. C. temperature range; (3) pumping the TEG with a pump
58, and without a jet gas system; (4) washing the flash gas to
remove moisture and heavy hydrocarbons in the winter; and (5)
burning all of the flash gas in the reboiler 34 without venting or
flaring the flash gas.
[0044] Some of the benefits realized by embodiments of the present
invention may include: (1) eliminates jet-gas systems for hot
glycol circulation; (2) uses no-bleed power-gas level controllers;
(3) a glycol flash gas contactor provides usable fuel gas to the
reboiler, even during the winter; (4) reboiler fuel system designed
to preferentially consume glycol flash gas over make-up fuel gas;
(5) requires additional heat-exchange surface area for
glycol/glycol heat exchangers for energy optimization; (6) requires
additional insulation on strategic piping and equipment; (7) Glycol
Still Column overhead vapors are condensed, recovered, accumulated,
and pumped to storage; (8) improved hydrocarbon liquids handling
system to remove liquids from separator, accumulator, glycol flash
tank, fuel-gas system, and power-gas system; (9) minimizes glycol
circulation to contactor; and (10) utilizes glycol pump to
circulate hot glycol heat trace during winter operation and can be
by-passed during summer operation.
[0045] The present invention may be embodied in other specific
forms without departing from its fundamental functions or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative, and not restrictive. All changes
which come within the meaning and range of equivalency of the
illustrative embodiments are to be embraced within their scope.
* * * * *