Gas Dehydration - Inside Mines - Colorado School of Minesinside.mines.edu/~jjechura/GasProcessing/08_Dehydration.pdf · Reasons for Gas Dehydration ... 30 MMscfd of a 0.65 gravity

Gas Dehydration

Chapter 11Based on presentation by Prof. Art Kidnay

Updated: December 27, 2017Copyright © 2017 John Jechura ([email protected])

Plant Block Schematic

2


Reasons for Gas Dehydration

Field Operations Prevent hydrate formation Minimize corrosion

• Need to dry gas to dew point below lowest operating temperature

Plant Operations Need 4 to 7 lb/MMscf (85 to 150 ppmv) in pipeline

• Glycol dehydration most common to produce water contents down to 10 ppmv

Need to have less than 1 ppmv H2O in gas to cryogenc units• Glycol dehydration cannot get to these low water levels – mole sieves

used for this service

3


Topics

Water Content of Hydrocarbons

Gas Dehydration Processes Absorption processes Adsorption processes Non regenerable desiccant processes Membrane processes Other processes Comparison of dehydration processes

Safety and Environmental Considerations

4


Water Content of Hydrocarbons


Equilibrium considerations

Equal fugacities for each component in each phase. Between gas & water phases:

For a gas in contact with pure water:

Formation of the water phase will control the water content in the gas phase Increasing water in the feed increases the amount of free water, not the

concentration of water in the gas. Can decrease the gas water content by adding compounds that are water soluble

6

, ,

, ,

where expsati

Pvapi L i Li i

i i i ii V i V P

vPy x K K dP

P RT

H2OH2O H2O since 1

vapPy x

P


Water content of natural gas

Based on “typical” gas composition Separate corrections for actual composition &

acid gas content

Takes into account non-idealities

Take care if gas is specified as “wet” or “dry” basis – dry basis does not include the amount of water in the MMscf

When less than 5,000 lb/MMscf the wet & dry values are within 0.5%

7

Fig. 20-4, GPSA Engineering Data Book, 13th ed.Figure 11.1 in Kidnay et. al. text book

H2O H2OH2O H2O H2O

HC H2O

H2O H2O H2O H2OH2O

HC H2O

/Wet Basis: /

/ /Dry Basis:

1

N MX y M

N N

N M y MX

N y


Water content of natural gas – typical pipeline specs

8

GPSA Engineering Data Book, 13th ed.


Water content of natural gas

9

GPSA Engineering Data Book, 13th ed.Figure 11.1 (b) & (c) in Kidnay et. al. text book


Applicability of dehydration processes

10


Dehydration by Absorption


Equilibrium considerations

Glycols tend to be only in the water phase (i.e., non-volatile & very low solubility in the hydrocarbon liquid phase)

For a gas in contact with water/glycol mixture:

Water content in the gas phase is less than that for a pure water phase since x’H2O < 1

Away from glycol, must reduce temperature to create a free water phase.

12

H2OH2O H2O

vapPy x

P


Typical Glycols

EG DEG TEG

Name Ethylene Glycol

DiethyleneGlycol

TriethyleneGlycol

Formula C2H6O2 C4H10O3 C6H14O4

Molecular Weight 62.1 106.1 150.2

Boiling Point (°F) 386.8 473.5 550.4

Vapor pressure @ 77°F (mmHg) 0.12 < 0.01 < 0.01

Density @ 77°F (lb/gal) 9.26 9.29 9.34

Viscosity @ 77°F (cP) 16.9 25.3 39.4

Decomposition temperature (°F) 329 328 404

13

Fig. 20-50, GPSA Engineering Data Book, 13th ed.


Glycol molecular structure

Ethylene glycol HO-CH2-CH2-OH

Diethylene Glycol HO-CH2-CH2-O-CH2-CH2-OH

Triethylene Glycol HO-CH2-CH2-O-CH2-CH2-O-CH2-CH2-OH

14

Chemical structures drawn using http://molview.org/


Equilibrium water content above TEG solutions

15

Based on Fig 20-59 GPSA Data Book 13th ed. & Figure 11.3 in Kidnay et. al. text bookBased on 1,000 psia contactor pressure


Example – Equilibrium water content above TEG solutions

Operate a TEG contactor @ 100oF & 1,000 psiawith 99.9 wt% TEG introduced at the top

Dried gas is protected to a dew point of -40oF

16

Fig. 20-59, GPSA Engineering Data Book, 13th ed.Figure 11.3 in text book


Equilibrium water content for TEG solutions

17


Typical Glycol Dehydration Unit

System 2 – 5 gal TEG per lb water removed

Absorber / Contactor 60 – 100oF inlet Can operate up to 2,000 psia Typically 4 – 10 bubble cap trays

• 25 – 30% efficiency 5 – 10 psi pressure drop

Flash tank 10 – 20 minute residence time 150oF, 50 – 75 psig

Regenerator Packed equivalent to 3 – 4 trays 375 – 400oF

18

Fig. 20-58, GPSA Engineering Data Book, 13th ed.Basis for Figure 11.2 in text book


Typical Glycol Dehydration Unit

System 2 – 5 gal TEG per lb water removed

Absorber / Contactor 60 – 100oF inlet Can operate up to 2,000 psia Typically 4 – 10 bubble cap trays

• 25 – 30% efficiency 5 – 10 psi pressure drop

Flash tank 10 – 20 minute residence time 150oF, 50 – 75 psig

Regenerator Packed equivalent to 3 – 4 trays 375 – 400oF

19

H2O H2O H2Ovapy P x P


Example based on GPSA Data Book example 20-11

30 MMscfd of a 0.65 gravity natural gas enters a TEG contactor at 600 psiaand 100oF. The outlet water content specification is 7 lb H2O/MMscf and the TEG circulation rate is 28 lb TEG/ lb H2O absorbed (3 gal TEG/lb H2O). How much water is to be absorbed? What is the rich TEG concentration? What is the lean TEG concentration? Water content at inlet

conditions?

70 lb/MMscf

How much water is removed?

20

lb H2O lb TEG1890 28

day lb H2O

lb TEG52920

day



30 MMscfd of a 0.65 gravity natural gas enters a TEG contactor at 600 psiaand 100oF. The outlet water content specification is 7 lb H2O/MMscf and the TEG circulation rate is 28 lb TEG/ lb H2O absorbed (3 gal TEG/lb H2O). How much water is to be absorbed? What is the rich TEG concentration? What is the lean TEG concentration? How much TEG is circulated?

21

lb H2O lb TEG1890 28

day lb H2O

lb TEG52920

day

lb H2O gal TEG1890 3

day lb H2Ohr min

24 60 day hr

gal TEG3.9

min


Example based on GPSA Data Book example 20-11 (#2)

30 MMscfd of a 0.65 gravity natural gas enters a TEG contactor at 600 psiaand 100oF. The outlet water content specification is 7 lb H2O/MMscf and the TEG circulation rate is 28 lb TEG/ lb H2O absorbed (3 gal TEG/lb H2O). How much water is to be absorbed? What is the rich TEG concentration? What is the lean TEG concentration? Dew point temperature at the

contactor pressure (600 psia)?

~ 24oF

22



30 MMscfd of a 0.65 gravity natural gas enters a TEG contactor at 600 psiaand 100oF. The outlet water content specification is 7 lb H2O/MMscf and the TEG circulation rate is 28 lb TEG/ lb H2O absorbed (3 gal TEG/lb H2O). How much water is to be absorbed? What is the rich TEG concentration? What is the lean TEG concentration? What is the minimum TEG concentration for

a 24oF dew point & the contactor temperature (100oF)? ~98.5 wt%• Lean TEG has 806 lb/day water

Rich TEG content (after absorbing the water from the wet gas)

23

lb TEG52920

daylb H2O lb TEG

1890 806 52920 day day

95.2 wt% H2O


Solubility of hydrocarbons in glycol solutions

Methods to control BTEX emissions from Regenerator Condense overhead & recover Burn vent gas through flare or thermal oxidizer Recycle back to process

24

GPSA Engineering Data Book, 13th ed.


Field Glycol Dehydrator

25

reboiler

contactor

gas burner

heat exchanger,surge tank

Flash separator3-phase, gas,glycol,condensate

Inlet separatorglycol pump

stripper

From Sivalls, “Glycol Dehydration Design,” LRGCC, 2001


Common Operational Problems

Contactor foaming Contaminates: hydrocarbons, salts, particulates, inhibitors, O2

Poor dehydration (from source other than foaming) Gas rate too low - 80% flow reduction = 20 % tray eff Glycol rate low - 75% flow reduction = 33% tray eff Glycol inlet temperature too high

Flash drum / Foaming in Still Presence of heavy hydrocarbons

26


Dehydration by Adsorption


Absorption vs Adsorption

28

Absorption Adsorption


Physical absorption

29


Adsorption fundamentals

Two types of adsorption Chemisorption

• Chemical interaction between adsorbate and adsorbent• May not be completely reversible

Physical adsorption• Only physical interaction between adsorbate and adsorbent• Completely reversible

-ΔHChem >> -ΔHPhys

30


Physical Adsorption Fundamentals

Factors affecting selectivity Size – adsorbent pore diameter major factor Volatility – less volatile displaces more volatile (e.g., C3 displaces C2) Polarity

• For desiccants, more polar displaces less polar (e.g., CO2 displaces C2, MeOH displaces CO2, water displaces MeOH)

31


Adsorption Isotherms

32

From UOP

Lb W

ater

Ads

orbe

d /

100

lb A

ctiv

ated

Ads

orbe

nt


Solid Desiccant Dehydrator – Twin Tower System

33

Fig. 20-76, GPSA Engineering Data Book, 13th ed.


Typical Vessel Loading

Possible configuration for drying 100 MMscfd to a dew pointof -150ºF, adsorption time ~12 hours

Sample packing of catalyst/dessicant on top of supports

Model prepared by Enterprise Products


Concentration Profile

35

Equilibrium Zone (Saturated)

Mass Transfer Zone (Partially saturated)

Active Zone (Unsaturated)


Concentration Profile

36

yIn

yOut


Regenerating Bed Temperature History

37

Heat On

DesorptionBed Heating Bed Cooling

0 1 2 3 4 5 7 86

Time, Hours

100

200

300

400

600

500

0

50

100

150

200

250

300Inlet Temperature

Outlet Temperature


Regenerating Bed Temperature History

38

Heat On

Inlet Temperature

DesorptionBed Heating Bed Cooling

Outlet Temperature

0 1 2 3 4 5 7 86

Time, Hours

Tem

pera

ture

, ºF

100

200

300

400

600

500

0

Tem

pera

ture

, ºC

50

100

150

200

250

300


Common Adsorbents for Drying

In order of increasing cost:

Silica gel (SiO2) Min exit water content 10 to 20 ppmv (~-60oF) Inert and used for inlet concentrations of > 1 mol%

Activated Alumina (Al2O3) Min exit water content 5 to 10 ppmv (~-100oF) High mechanical strength but more reactive

Molecular Sieve (4A and 3A) Min exit water content below 0.1 ppmv (~-150oF) Highest surface area Composite of sieve and clay binder

39


Design steps

Determine size of vessels for adsorption Determine the bed diameter based on superficial gas velocity / allowable pressure drop

• Too small – pressure drop will be too high & can damage the sieve• Too large – need too high a regeneration gas rate to prevent channeling• Typically use (-P/L) < 0.33 psi/ft with a total pressure drop of 5 – 8 psi max

Choose an adsorption period & calculate the mass of desiccant

• Sets the bed height – contributions from saturation zone & mass transfer zone heights• 8 to 12 hour periods with 2 or 3 beds are common

o Too long – more desiccant & larger vessels needed than necessaryo Too short a time – shorter desiccant life

Regeneration Calculate heat required to desorb water while also heating the desiccant & vessel Total amount of regeneration gas flow calculated based on heating phase about 50-60% of

total regeneration time Regeneration gas flowrate should give a pressure drop gradient of at least 0.01 psi/ft

40


Design equations (#1)

Determine gas velocity for bed diameter Modified Ergun equation for pressure drop

• Viscosity [cP] & density [lb/ft³] determined at inlet conditions• Solve quadratic equation for maximum superficial velocity (Vmax [ft/min]) for 0.33 psi/ft

pressure drop• Pressure drop gradient in units of psi/ft

Minimum diameter

Adjust diameter upwards to nearest ½ foot increment• Recalculate superficial linear velocity & pressure drop using adjusted diameter

41

2PB V C V

L

minmax

4 mD

V



Determine bed length (method 1) Amount of desiccant in saturation zone

Assumes 13 lb water per 100 lb dessicant Amount of desiccant in the mass transfer

zone (MTZ) (GPSA EDB method)

where CZ is 1.70 ft for 1/8 inch sieve & 0.85 for 1/16 inch sieve

… or Trent method for MTZ

42

water satsat sat 2

bulk

40.13 SS T

m SS L

C C D

0.3

MTZ

ft/minft

35 Z

VL C

0.636 0.0826 ln %satSSC

1.20 0.0026 FTC MTZ ft 2.5 0.025 ft/minL V



Determine bed length (method 2) Calculate “effective desiccant capacity” which includes the MTZ effect, temperature,

and relative humidity corrections. An effective capacity of 8–10% is typically assumed.

Finalize bed length Total bed height (Lsat+LMTZ or Lbed) but should not be less than the bed diameter or 6

ft, whichever is greater Total bed pressure drop should be 5 – 8 psi max

• If too large increase the bed diameter

Determine vessel height & weight Total bed height plus other allowances – at least 3 ft (for inlet distributor on top and

bed support & hold down balls underneath)

43

water bedbed bed 2

bulk

4

eff

m SS L

C D



Regeneration calculations Used to determine the required regeneration gas flow & the fuel gas requirements

• If regeneration gas recycled back to inlet of mole sieves then you must add this rate to that of the feed gas for the bed calculations

Heat loads• Heat to desorb water – increase water to its desorption temperature, break

adherence to surface, & vaporizeo Use 1,800 Btu/lb water adsorbed for conservative design

• Heat to increase sieve to regeneration temperature• Heat to increase vessel to regeneration temperature• Heat losses – typically estimated as 10%

44



Regeneration Calculations (cont.) Calculation of vessel weight for heating calculations

where the 0.75D term accounts for the weight of the vessel heads• Design pressure in psig. Usually 10% greater than operating pressure (minimum

50 psig) Usually have to heat the regeneration gas 50oF hotter than the desired regeneration

temperature (e.g., 500oF gas needed to regenerate at 450oF) Total regeneration load 2.5 times the minimum load

• Assumes only 40% of the heat is transferred from gas to mole sieve system. • The remainder exits as hot gas. Need to size downstream coolers appropriately.

Regen gas flowrate. Check that pressure drop gradient at least 0.01 psi/ft

45

designsteel vessel

design

12in 0.0625 and lb 155 0.125 0.75

37600 1.2

D Pt m t L D D

P

Total Regen rg

Regen Gas rg 2hot bed rg

4

P

Q mm V

C T T D



100 MMscfd natural gas (molecular weight of 18) is water saturated at 600 psiaand 100oF & must be dried to –150oF dew point. Determine the water content of the gas (inlet & outlet) & amount of water that must be removed.

Do preliminary design of a molecular-sieve dehydration system consisting of two towers with down-flow adsorption in one tower and up-flow regeneration in the other. Use 4A molecular sieve of 1/8″beads (i.e., 4x8mesh). The regeneration gas is part of the plant’s residue gas (at 600 psia and 100oF) & has a molecular weight of 17. The bed must be heated to 500oF for regeneration. Base this on a 24-hour cycle consisting of 12 hours adsorbing and 12 hours regenerating (heating, cooling, standby, and valve switching; the heating time is 60% of the regeneration time).

46



100 MMscfd natural gas (molecular weight of 18) is water saturated at 600 psiaand 100oF & must be dried to –150oF dew point. Determine the water content of the gas (inlet & outlet) & amount of water that must be removed. Water content at inlet

conditions?70 lb/MMscf

Water content at outlet conditions?

Essentially 0 lb/MMscf How much water is to be

removed?

47

70 0 lb/MMscf 100 MMscfd

7,000 lb/day



… Do preliminary design of a molecular-sieve dehydration system consisting of two towers with down-flow adsorption in one tower and up-flow regeneration in the other. Use 4A molecular sieve of 1/8″ beads (i.e., 4x8 mesh)… Determine bed diameter. Velocity criteria not given so determine from allowable

pressure drop (0.33 psi/ft max)• Ideal gas flowrate at inlet conditions (600 psia and 100oF)

• Real gas flow much different? Estimate: Z=0.93

48

3 36 6

IG

100 460 °Rft 14.7 psia ft100 10 2.6 10

day 600 psia 60 460 °R dayV

3 3 3

6 6IG

ft ft ft0.93 2.6 10 2.5 10 1700

day day minactV Z V



… Do preliminary design of a molecular-sieve dehydration system consisting of two towers with down-flow adsorption in one tower and up-flow regeneration in the other. Use 4A molecular sieve of 1/8″ beads (i.e., 4x8 mesh)… Determine bed diameter. Velocity criteria not given so determine from allowable

pressure drop (0.33 psi/ft max)• Real gas density at inlet conditions (600 psia and 100oF)

• Gas viscosity at inlet conditions (600 psia and 100oF). Estimate 0.015 cP.• Velocity vs. pressure gradient. For given beads & gas properties:

49

3

600 18 lb1.93

0.93 10.7316 560°R ftPMZRT

2

5 2 ft0.33 0.056 0.015 8.89 10 1.93 41.4

min

PB u C u

L

u u u



… Do preliminary design of a molecular-sieve dehydration system consisting of two towers with down-flow adsorption in one tower and up-flow regeneration in the other. Use 4A molecular sieve of 1/8″ beads (i.e., 4x8mesh)… Determine bed diameter. Velocity criteria not given so determine from allowable

pressure drop (0.33 psi/ft max)• Minimum diameter is ratio of volumetric flowrate to maximum velocity. Scale up to

next 6”.

50

2

min

ft4 1700

min7.2 ft D=7.5 ft

ft4 41.4min

actVDA D

u



… Do preliminary design of a molecular-sieve dehydration system consisting of two towers with down-flow adsorption in one tower and up-flow regeneration in the other. Use 4A molecular sieve of 1/8″ beads (i.e., 4x8mesh)… Determine bed diameter. Velocity criteria not given so determine from allowable

pressure drop (0.33 psi/ft max)• Determine actual gas velocity & pressure drop in absorbing bed

51

3

22

4 1700 ft /min438.5 ft/min

7.5 ft

V Vu

A D

2

25 psi0.056 0.015 38.5 8.89 10 1.93 38.5 0.29

ft

PB u C u

L



… Base this on a 24-hour cycle consisting of 12 hours adsorbing and 12 hours regenerating (heating, cooling, standby, and valve switching; the heating time is 60% of the regeneration time). Since the overall removal rate is 7,000 lb/day we must have enough adsorbent to

safely contain 3,500 lb of water (corresponding to the adsorbing time). No other criteria given for amount of water to be contained by desiccant –

determine size using the zone analysis (method 1)• Size saturation zone to contain all water for the cycle. Use a typical sieve bulk

density of 45.0 lb/ft3

52

watersat

satsat 22

bulk

350028,600 lb sieve

0.13 0.13 1 1.20 0.0026 100

4 4 2860014.4 ft

7.5 45.0

SS T

mS

C C

SL

D



… Base this on a 24-hour cycle consisting of 12 hours adsorbing and 12 hours regenerating (heating, cooling, standby, and valve switching; the heating time is 60% of the regeneration time). … determine size using the zone analysis

• Add appropriate length for the mass transfer zone (MTZ) to ensure no breakthrough of water. CZ=1.7 for this size sieve

• Total bed height is the sum of these two zones. Total vessel height adds 3 ft for supports, …

53

0.3 0.3

MTZ

38.61.7 1.74 ft

35 35Z

uL C

Bed sat MTZ vessel Bed14.4 1.74 16.1 ft 3 19.1 ftL L L L L



… Base this on a 24-hour cycle consisting of 12 hours adsorbing and 12 hours regenerating (heating, cooling, standby, and valve switching; the heating time is 60% of the regeneration time). … determine size using the zone analysis

• Check that the bed length is at least the bed diameter (here 7.5 ft) or 6 ft, whichever is greater.

o This bed depth does not need to be adjusted• Check that total pressure drop is 5 – 8 psi. If too small, add bed height; if too

large, add diameter

54

bed 0.29 16.1 =4.7 psi (close enough)p

p LL



… The regeneration gas is part of the plant’s residue gas (at 600 psia & 100oF) & has a molecular weight of 17. The bed must be heated to 500oF for regeneration… Determine amount of heat needed for regeneration

• Heat to desorb water

• Heat the sieve to regeneration temperature

55

3500 1800 6,300,000 Btuw w wQ m H

2

, ,

2

4

7.5 16.1 45.00.24 500 100

4

3,070,000 Btu

bed bulksi si p si regen ads p si regen ads

D LQ m C T T C T T



… The regeneration gas is part of the plant’s residue gas (at 600 psia & 100oF) & has a molecular weight of 17. The bed must be heated to 500oF for regeneration… Determine amount of heat needed for regeneration (cont.)

• Heat the steel to regeneration temperature

56

,

50620 0.12 500 100

2, 430,000 Btu

steel steel p steel regen adsQ m C T T

design

design

steel vessel

12in 0.0625

37600 1.2

12 7.5 1.1 600 14.70.0625 1.636 in

37600 1.2 1.1 600 14.7

lb 155 0.125 0.75

155 1.636 0.125 19.1 0.75 7.5 7.5 50620 lb

D Pt

P

m t L D D



… The regeneration gas is part of the plant’s residue gas (at 600 psia & 100oF) & has a molecular weight of 17. The bed must be heated to 500oF for regeneration… Determine amount of heat needed for regeneration (cont.)

• Total regeneration heat needed

Determine amount & rate of regen gas needed• Heat that must be transferred to the regeneration gas

57

1

6,300,000 3,070,000 2, 450,00 1 0.10

13,002,000 Btu

regen w si steel loss w si steel lossQ Q Q Q Q Q Q Q f

2.5 2.5 13,002,000 =32, 505,000 Bturg regenQ Q



… The regeneration gas is part of the plant’s residue gas (at 600 psia & 100oF) & has a molecular weight of 17. The bed must be heated to 500oF for regeneration… Determine amount & rate of regen gas needed (cont.)

• Determine amount regen gas needed

• Determine rate of regen gas needed

58

,

32, 505,000111,100 lb

0.65 500 50 100rg

rgp rg rg cold

Qm

C T T

111,100

15, 430 lb/hr 257 lb/min0.6 12

rgrg

mm

t

, 0.65 Btu/lb F (based on Fig. 23-48 in GPSA EDB averaged between 100 & 550 F)o op rgC



… The regeneration gas is part of the plant’s residue gas (at 600 psia & 100oF) & has a molecular weight of 17. The bed must be heated to 500oF for regeneration… Verify there is sufficient pressure drop during regeneration to prevent channeling

(i.e., pressure drop is above 0.01 psi/ft)• For the hot regen gas (@ 550oF):

Flow rate is sufficient

59

3

600 17 lb0.94

1 10.7316 550 460 ftrg

PMZRT

0.023 cP (from Fig. 23-23 in GPSA EDB)

22 5 psi0.056 0.023 6.2 8.89 10 0.94 6.2 0.011

ftP

B u C uL

22

4 4 2576.2 ft/min

0.947.5rg rg

rgrg

V mu

A D


Common Mole Sieve Operational Problems

Loss of bed capacity Aging, rapid initial loss then

gradual loss over years Coking by partial oxidation of

heavy hydrocarbons Coking by conversion of H2S to

elemental sulfur Poor regeneration

Increased pressure drop Attrition Caking at top of bed

Fines Attrition Failed bed support

COS formation Chemical equilibrium

H2S + CO2 COS + H2O

60


Other Dehydration Processes


Other processes

Consumable salts (CaCl2)

Refrigeration with MEOH addition, more complex

Membranes, ideal for remote sites when low pressure permeate gas can be used effectively

If drying high pressure gas: Vortex tube – one application known

• Simple but poor turndown ratio and efficiency Twister Supersonic Separator one known offshore application

• Simple, poor turndown ratio but better efficiency

62


Twister Operating Principle

Acceleration to Mach >1 cools gas (typically 60 – 80oC) ΔP = 30%

Cooling causes condensation (water and heavier hydrocarbons)

Swirl centrifuges liquid droplets to the tube wall

Drainage section removes liquid film from the wall + ~20% gas

Diffuser section recompresses the gas

63

http://twisterbv.com/PDF/resources/Twister_-_How_Does_It_Work.pdf


Comparison of Dehydration Processes

For < 1 ppmv H2O need mole sieve.

For higher concentrations: Glycol (usually TEG) widely used

• Minimal manpower requirements• High turndown

Regenerative desiccants (silica gel, alumina) more costly Membranes, and Twister(?) where pressure drop acceptable Nonregenerative desiccants (CaCl2) for remote, low water content gas

64


Summary


Summary

Water content can be estimated from Fig. 20-4 Units of lb/MMscfWet & dry bases essentially the same below 5,000 lb/MMscf

Three primary separation technologies Bulk removal by cooling & separation TEG dehydration to pipeline specs (4 – 7 lb/MMscf) Mole sieves required upstream of cryogenic applications

66


Supplemental Slides


Glycol Dehydration Unit

68

contactor

stripping still

reboiler

http://www.kirkprocess.com/products/highspeed-gas-dehydration/


Glycol Dehydration Unit

69

contactor

stripping still

reboiler

http://www.en-fabinc.com/en/glycol_dehydration_system.shtml


Mole Sieve Dehydration Unit

70

http://www.enerprocess.com/processing-&-treating-units/gas-conditioning-&-treating/mol-sieve-dehydration-units


Zeolite structures

Zeolite A Zeolite X

71

Documents

Gas Dehydration - Inside Mines - Colorado School of Minesinside.mines.edu/~jjechura/GasProcessing/08_Dehydration.pdf · Reasons for Gas Dehydration ... 30 MMscfd of a 0.65 gravity