The document discusses the components and process of a glycol dehydration system used to remove water from natural gas. It describes the major system components including contactors, filters, heat exchangers, pumps, reboilers, and still columns. It also discusses various process variables that impact the dehydration process such as gas and glycol temperatures, glycol circulation rate, and reboiler pressure and temperature. The overall goal of the system is to use glycol like diethylene, triethylene, or tetraethylene glycol to absorb water from the natural gas in a contactor and then regenerate the lean glycol in a reboiler and still column.

1. Mohamed Abdelraof Saad
Dehydration

2. Mohamed Abdelraof Saad
Glycol Dehydration
The more common liquids in use for
dehydrating natural gas are
Diethylene glycol (DEG)
Triethylene glycol (TEG)
Tetraethylene glycol (TREG).

3. Mohamed Abdelraof Saad

4. Mohamed Abdelraof Saad

5. Mohamed Abdelraof Saad

6. Mohamed Abdelraof Saad

7. Mohamed Abdelraof Saad
Glycol dehydration

8. Mohamed Abdelraof Saad

9. Glycol
Regeneration Unit
Fuel Gas
Package
Oily Water
Treatment
Unit
Well
Separator
A
Separator
B
Separator
C
Coalescer
Sump
Caisson
Water
Vapor
Sea Line
Desander
Glycol
contactor

10. Glycol Reboiler
Gly. Inj. Pump
Glycol
Accumulator
Lean /Rich Gly.
Ex.
Rich Gly.
Flashed
Gas
Gas flow meterSystem Valve
Glycol
Flash
Drum
Glycol
Cartridge
filter Glycol Carbon
filter
Dehydration
tower T-101
Sea Line
Produced
Gas

11. Mohamed Abdelraof Saad
Glycol Dehydration System Components
Inlet Scrubber
Inadequate scrubbing causes about half of all
glycol dehydration system problems.
Free water
Many contaminants include:
1. Oils or hydrocarbons
2. Entrained brine
3. Downhole additives
4. Solids, such as sand and corrosion products

12. PROBLEMS CAUSED BY CONTAMINANTS
PROBLEMSCONTAMINANT
Increases glycol recirculation, reboiler heat duty, and fuel
costs
If the dehydration system becomes overloaded with water,
glycol can carry over from the contactor and/or still .
Sales gas specification may not be achieved
Free Water
Reduce the drying capacity of the glycol With water
present, can cause foaming
Undissolved oils can:
• Plug absorber trays
• Foul heat transfer surfaces in the reboiler
• Increase the viscosity of the glycol
• Light hydrocarbons can flash in the stripping column
and cause loss of glycol and/or damage to the packing
Oils or
Hydrocarbons

13. PROBLEMS CAUSED BY CONTAMINANTS
PROBLEMSCONTAMINANT
Dissolves into glycol
Corrodes steel, especially stainless steel
Deposits on reboiler fire tubes, causing hot spots and
firetube burnout
Brine
Cause foaming, corrosion, and, if they deposit on fire
tubes, hot spots
Downhole
Additives
Promote foaming
Erode valves and pumps
Eventually plug trays and packing
Solids

14. Mohamed Abdelraof Saad
Glycol Dehydration System Components
Contactor
Contactor towers contact the lean glycol with
the wet gas stream.
Scrubbing section in the bottom
Drying (mass transfer) section in the
middle
Glycol cooler and mist extractor in the top

15. Mohamed Abdelraof Saad
Glycol Dehydration System Components
Contactor

16. Mohamed Abdelraof Saad
Contactor
Scrubbing Section :–
Scrubber integrated into the contactor
Wire mesh mist extractor.
This second stage of scrubbing further
minimizes the contamination of the
glycol and helps prevent the free water
from overloading the system.

17. Mohamed Abdelraof Saad
Contactor

18. Mohamed Abdelraof Saad
Contactor
Drying Section :
In the middle section of the
contactor, the gas stream flows
upward and thoroughly
contacts the downward flowing
lean glycol through valve trays,
bubble caps, or packing.

19. Mohamed Abdelraof Saad
Glycol cooler and mist extractor in the top
Its aim is to collect any
glycol droplets which
escape with dry gas to
avoid glycol losses

20. Mohamed Abdelraof Saad
Carryover
can result from
• foam build-up caused by
glycol contamination
• high gas rate. It will happen
continuously when the gas
rate is high enough to agitate
the liquid at the top tray so
that a foam forms that is too
thick for the mist eliminator to
handle.

21. Mohamed Abdelraof Saad
Glycol cooler
-It decrease lean glycol
temperature to
increase affinity of
glycol to absorb water

22. Mohamed Abdelraof Saad
the best glycol temp. ( 5-15 ) higher than
gas temperature

23. Mohamed Abdelraof Saad
Flash Drum Separator
A two-phase separator with a 5 to 10 minute liquid
retention time prevents excess hydrocarbon vapor
from entering the stripping column

24. Mohamed Abdelraof Saad
GAS-CONDENSATE-GLYCOL
SEPARATOR Skimmer

25. Mohamed Abdelraof Saad
Filters
Cartridge filters remove solids, that is, corrosion products.
Activated carbon filters remove hydrocarbon impurities, for
example, well treating chemicals and compressor oils.

26. Mohamed Abdelraof Saad
Filters
• Activated carbon filters remove hydrocarbon impurities, for example, well
treating chemicals and compressor oils.
• They work well until their adsorption capacity is reached. In cases where
the glycol contains appreciable quantities of light hydrocarbons, they
must be changed frequently.
• Most glycol systems cannot be operated successfully without carbon
adsorption.
• There are two types of activated carbon filters.
• Most systems use a carbon canister; however, larger systems use a
loose fill carbon vessel. When the loose fill vessel is used, care must be
taken to trap carbon fines and keep them from entering the glycol
dehydration system. This is especially important when a fresh carbon
bed is put into service.
• Carbon filters should be replaced anytime the level of contaminants in
the glycol solution goes up.
• Monthly test should be run to determine the contamination level.

27. Mohamed Abdelraof Saad
Heat Exchangers
Lean gas/glycol
Glycol/glycol
Reflux coil located in still column

28. Mohamed Abdelraof Saad
Glycol Pump
Glycol circulation pumps contain the only moving parts in a
glycol dehydration system.
Electric-motor driven
High-pressure gas-operated
High-pressure liquid-operated

29. Mohamed Abdelraof Saad
Reboiler
Reboilers provide enough heat to boil the water out of the
glycol.

30. Mohamed Abdelraof Saad
Still Column
Reflux Coil :
The top of the still column contains a cooling coil that
condenses some of the steam rising from the reboiler.
Providing reflux for the column.
Packing
Still columns usually contain 4 to
8 ft of packing although some
large units use trays.

31. Mohamed Abdelraof Saad
Surge Tank (Accumulator)
The surge tank (accumulator) holds glycol to compensate
for fluctuations in the load on the glycol dehydration
systems

32. Mohamed Abdelraof Saad
OVERFLOW TUBE
The glycol level in the reboiler is maintained above the heating tube
by the location of the overflow tube.
The dried, purified glycol spills into the overflow tube and flows into
the surge tank.

33. Mohamed Abdelraof Saad
Stripping Gas
Adding a stripping gas to the still column increases the glycol
purity produced by the glycol reconcentrator from about
98.5% to 99.9%.

34. Mohamed Abdelraof Saad

35. Mohamed Abdelraof Saad
Process/Design Variables
Gas Temperature
water content of the inlet gas increases as this
temperature is raised.
Glycol vaporization losses are also increased at the
higher temperature.
Problems can result from too low a temperature (below
50°F) because glycol becomes very viscous.
Lean Glycol Temperature
It should be kept at least 10°F above the inlet gas
temperature to minimize hydrocarbon condensation in
the absorber and subsequent foaming.

36. Mohamed Abdelraof Saad
Process/Design Variables
Glycol Reboiler Temperature
The reboiler temperature controls the concentration of the water in the
glycol.
The glycol concentration increases with higher reboiler temperatures.
The reboiler temperature should never be allowed to remain at or above
the glycol degradation temperatures.
When higher glycol concentrations are required, stripping gas can be
added to the reboiler..
Regenerator Top Temperature
A high temperature can increase glycol losses due to excessive
vaporization.
The recommended temperature in the top of the column is about 225°F.
If the temperature in the top of the column drops too low, too much water
can be condensed and washed back into the regenerator to flood the
column and fill the reboiler with excessive liquids.

37. Mohamed Abdelraof Saad
Process/Design Variables
Reboiler Pressure
Reducing the pressure in the reboiler at a constant
temperature results in higher glycol purity
Glycol Concentration
The water content of the dehydrated gas depends
primarily on the lean glycol concentration
Glycol Circulation Rate
The dew point depression of a saturated gas is a function
of the glycol circulation rate
A typical glycol circulation rate is about three gallons of
glycol per pound of water removed (seven maximum).

38. Mohamed Abdelraof Saad
EQUILIBRIUM WATER DEW POINTS FOR GASES IN CONTACT
WITH VARIOUS CONCENTRATIONS OF TEG

39. Mohamed Abdelraof Saad
DESCRIBING THE GLYCOL
DEHYDRATION PROCESS

40. Mohamed Abdelraof Saad
Glycol dehydration unit