Gas Dehydration. Chapter 11 Based on presentation by Prof. Art Kidnay

Gas Dehydration Chapter 11 Based on presentation by Prof. Art Kidnay

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 H 2 O 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: vap P il, ip i vil, yi xk i i where Ki exp dp iv, iv, P sat RT P i For a gas in contact with pure water: y H2O P P vap H2O since x 1 H2O 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

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 N / M Wet Basis: X y / M Dry Basis: H2O H2O H2O H2O H2O NHC NH2O X H2O N / M y / M N 1 y H2O H2O H2O H2O When less than 5,000 lb/mmscf the wet & dry values are within 0.5% HC H2O Fig. 20-4, GPSA Engineering Data Book, 13 th ed. Figure 11.1 in Kidnay et. al. text book 7

Water content of natural gas typical pipeline specs GPSA Engineering Data Book, 13 th ed. 8

Water content of natural gas GPSA Engineering Data Book, 13 th ed. Figure 11.1 (b) & (c) in Kidnay et. al. text book 9

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: y H2O x H2O P P vap H2O 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

Typical Glycols Name EG DEG TEG Ethylene Glycol Diethylene Glycol Triethylene Glycol Formula C 2 H 6 O 2 C 4 H 10 O 3 C 6 H 14 O 4 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 Fig. 20-50, GPSA Engineering Data Book, 13 th ed. 13

Glycol molecular structure Ethylene glycol HO-CH 2 -CH 2 -OH Diethylene Glycol HO-CH 2 -CH 2 -O-CH 2 -CH 2 -OH Triethylene Glycol HO-CH 2 -CH 2 -O-CH 2 -CH 2 -O-CH 2 -CH 2 -OH Chemical structures drawn using http://molview.org/ 14

Equilibrium water content above TEG solutions Based on Fig 20-59 GPSA Data Book 13 th ed. & Figure 11.3 in Kidnay et. al. text book Based on 1,000 psia contactor pressure 15

Example Equilibrium water content above TEG solutions Operate a TEG contactor @ 100 o F & 1,000 psia with 99.9 wt% TEG introduced at the top Dried gas is protected to a dew point of -40 o F Fig. 20-59, GPSA Engineering Data Book, 13 th ed. Figure 11.3 in text book 16

Equilibrium water content for TEG solutions 17

Typical Glycol Dehydration Unit System 2 5 gal TEG per lb water removed Absorber / Contactor 60 100 o F 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 150 o F, 50 75 psig Regenerator Packed equivalent to 3 4 trays 375 400 o F Fig. 20-58, GPSA Engineering Data Book, 13 th ed. Basis for Figure 11.2 in text book 18

Typical Glycol Dehydration Unit System 2 5 gal TEG per lb water removed Absorber / Contactor 60 100 o F 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 150 o F, 50 75 psig Regenerator Packed equivalent to 3 4 trays 375 400 o F y P x P H2O vap H2O H2O 19

Example based on GPSA Data Book example 20-11 30 MMscfd of a 0.65 gravity natural gas enters a TEG contactor at 600 psia and 100 o F. 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? lb H2O lb TEG 1890 28 day lb H2O lb TEG 52920 day 20

Example based on GPSA Data Book example 20-11 30 MMscfd of a 0.65 gravity natural gas enters a TEG contactor at 600 psia and 100 o F. 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? lb H2O lb TEG 1890 28 day lb H2O lb TEG 52920 day lb H2O gal TEG 1890 3 day lb H2O hr min 24 60 day hr gal TEG 3.9 min 21

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 psia and 100 o F. 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)? ~ 24 o F 22

Example based on GPSA Data Book example 20-11 (#3) 30 MMscfd of a 0.65 gravity natural gas enters a TEG contactor at 600 psia and 100 o F. 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 24 o F dew point & the contactor temperature (100 o F)? ~98.5 wt% Lean TEG has 806 lb/day water Rich TEG content (after absorbing the water from the wet gas) lb TEG 52920 day lb H2O lb TEG 1890 806 52920 day day 95.2 wt% H2O 23

Solubility of hydrocarbons in glycol solutions GPSA Engineering Data Book, 13 th ed. Methods to control BTEX emissions from Regenerator Condense overhead & recover Burn vent gas through flare or thermal oxidizer Recycle back to process 24

Field Glycol Dehydrator stripper contactor reboiler glycol pump Inlet separator gas burner heat exchanger, surge tank Flash separator 3-phase, gas,glycol,condensate From Sivalls, Glycol Dehydration Design, LRGCC, 2001 25

Common Operational Problems Contactor foaming Contaminates: hydrocarbons, salts, particulates, inhibitors, O 2 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 Absorption Adsorption 28

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 -ΔH Chem >> -ΔH Phys 30

Physical Adsorption Fundamentals Factors affecting selectivity Size adsorbent pore diameter major factor Volatility less volatile displaces more volatile (e.g., C 3 displaces C 2 ) Polarity For desiccants, more polar displaces less polar (e.g., CO 2 displaces C 2, MeOH displaces CO 2, water displaces MeOH) 31

Adsorption Isotherms Lb Water Adsorbed / 100 lb Activated Adsorbent From UOP 32

Solid Desiccant Dehydrator Twin Tower System Fig. 20-76, GPSA Engineering Data Book, 13 th ed. 33

Typical Vessel Loading Sample packing of catalyst/dessicant on top of supports Model prepared by Enterprise Products Possible configuration for drying 100 MMscfd to a dew point of -150ºF, adsorption time ~12 hours

Concentration Profile Equilibrium Zone (Saturated) Mass Transfer Zone (Partially saturated) Active Zone (Unsaturated) 35

Concentration Profile y In y Out 36

Regenerating Bed Temperature History Heat On 600 500 Inlet Temperature 300 250 400 200 300 150 200 100 0 Outlet Temperature Desorption Bed Heating Bed Cooling 0 1 2 3 4 5 6 7 8 Time, Hours 100 50 37

Regenerating Bed Temperature History Heat On 600 300 500 Inlet Temperature 250 Temperature, ºF 400 300 200 Outlet Temperature 200 150 100 Temperature, ºC 100 50 0 Desorption Bed Heating Bed Cooling 0 1 2 3 4 5 6 7 8 Time, Hours 38

Common Adsorbents for Drying In order of increasing cost: Silica gel (SiO 2 ) Min exit water content 10 to 20 ppmv (~-60 o F) Inert and used for inlet concentrations of > 1 mol% Activated Alumina (Al 2 O 3 ) Min exit water content 5 to 10 ppmv (~-100 o F) High mechanical strength but more reactive Molecular Sieve (4A and 3A) Min exit water content below 0.1 ppmv (~-150 o F) 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 Regeneration o Too long more desiccant & larger vessels needed than necessary o Too short a time shorter desiccant life 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 P B V C V L 2 Viscosity [cp] & density [lb/ft³] determined at inlet conditions Solve quadratic equation for maximum superficial velocity (V max [ft/min]) for 0.33 psi/ft pressure drop Pressure drop gradient in units of psi/ft Minimum diameter D min 4 m V max Adjust diameter upwards to nearest ½ foot increment Recalculate superficial linear velocity & pressure drop using adjusted diameter 41

Design equations (#2) Determine bed length (method 1) Amount of desiccant in saturation zone S m 4 S L 0.13 SS T water sat sat sat 2 C C D bulk Assumes 13 lb water per 100 lb dessicant Amount of desiccant in the mass transfer zone (MTZ) (GPSA EDB method) C 0.636 0.0826 ln %sat SS L MTZ ft V ft/min 0.3 35 C Z where C Z is 1.70 ft for 1/8 inch sieve & 0.85 for 1/16 inch sieve or Trent method for MTZ L MTZ ft 2.5 0.025 V ft/min C 1.20 0.0026 F T 42

Design equations (#3) 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. S m 4 S L water bed bed bed 2 Ceff D bulk Finalize bed length Total bed height (L sat +L MTZ or L bed ) 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

Design equations (#4) 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, & vaporize o 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

Design equations (#5) Regeneration Calculations (cont.) Calculation of vessel weight for heating calculations 12 DPdesign tin 0.0625 and msteel lb155t 0.125Lvessel 0.75 D D 37600 1.2 P design 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 50 o F hotter than the desired regeneration temperature (e.g., 500 o F gas needed to regenerate at 450 o F) 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 m Q m V Total Regen rg Regen Gas rg 2 CP Thot Tbed rg D 4 45

Example based on GPSA Data Book example 20-14 100 MMscfd natural gas (molecular weight of 18) is water saturated at 600 psia and 100 o F & must be dried to 150 o F 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 100 o F) & has a molecular weight of 17. The bed must be heated to 500 o F 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

Example based on GPSA Data Book example 20-14 (#2) 100 MMscfd natural gas (molecular weight of 18) is water saturated at 600 psia and 100 o F & must be dried to 150 o F 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? 70 0 lb/mmscf100 MMscfd 7, 000 lb/day 47

Example based on GPSA Data Book example 20-14 (#3) 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 100 o F) V IG 3 3 6 ft 14.7 psia 100 460 R 6 ft 100 10 2.6 10 day 600 psia 60 460 R day Real gas flow much different? Estimate: Z=0.93 V act 3 3 3 6 ft 6 ft ft ZV IG 0.932.6 10 2.510 1700 day day min 48

Example based on GPSA Data Book example 20-14 (#3) 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 100 o F) 60018 lb 1.93 3 0.9310.7316560 R ft PM ZRT Gas viscosity at inlet conditions (600 psia and 100 o F). Estimate 0.015 cp. Velocity vs. pressure gradient. For given beads & gas properties: P B u C u L 2 0.33 0.056 0.015 u 8.89 10 1.93 u u 41.4 min 5 2 ft 49

Example based on GPSA Data Book example 20-14 (#4) 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. A ft 4 1700 2 D V min act Dmin 7.2 ft D=7.5 ft 4 u ft 41.4 min 50

Example based on GPSA Data Book example 20-14 (#5) 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 3 V 4V 4 1700 ft /min u 38.5 ft/min 2 2 A D 7.5 ft P Bu Cu L 2 5 2 psi 0.056 0.015 38.5 8.89 10 1.93 38.5 0.29 ft 51

Example based on GPSA Data Book example 20-14 (#6) 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 S L m water sat 0.13 CSS CT 0.13 1 1.20 0.0026 100 sat sat 2 2 D bulk 7.5 45.0 3500 4 S 4 28600 14.4 ft 28,600 lb sieve 52

Example based on GPSA Data Book example 20-14 (#7) 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. C Z =1.7 for this size sieve L MTZ 0.3 0.3 u 38.6 CZ 1.7 1.74 ft 35 35 Total bed height is the sum of these two zones. Total vessel height adds 3 ft for supports, L L L 14.4 1.74 16.1 ft L L 3 19.1 ft Bed sat MTZ vessel Bed 53

Example based on GPSA Data Book example 20-14 (#7) 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 p p Lbed 0.2916.1 =4.7 psi (close enough) L 54

Example based on GPSA Data Book example 20-14 (#8) The regeneration gas is part of the plant s residue gas (at 600 psia & 100 o F) & has a molecular weight of 17. The bed must be heated to 500 o F for regeneration Determine amount of heat needed for regeneration Heat to desorb water Q m H 3500 1800 6,300,000 Btu w w w Heat the sieve to regeneration temperature Q m C T T C T T 4 4 3,070,000 Btu 2 DL si si p, si regen ads p, si regen ads bed bulk 2 7.5 16.145.0 0.24 500 100 55

Example based on GPSA Data Book example 20-14 (#9) The regeneration gas is part of the plant s residue gas (at 600 psia & 100 o F) & has a molecular weight of 17. The bed must be heated to 500 o F for regeneration Determine amount of heat needed for regeneration (cont.) Heat the steel to regeneration temperature t steel 12 DP design in 0.0625 37600 1.2 Pdesign 127.51.1600 14.7 37600 1.21.1600 14.7 lb155 0.125 vessel 0.75 Q m C T T steel steel p, steel regen ads 506200.12500 100 2, 430, 000 Btu m t L D D 0.0625 1.636 in 155 1.636 0.125 19.10.75 7.5 7.5 50620 lb 56

Example based on GPSA Data Book example 20-14 (#10) The regeneration gas is part of the plant s residue gas (at 600 psia & 100 o F) & has a molecular weight of 17. The bed must be heated to 500 o F for regeneration Determine amount of heat needed for regeneration (cont.) Total regeneration heat needed Q Q Q Q Q Q Q Q f 1 6, 300, 000 3, 070, 000 2, 450, 001 0.10 regen w si steel loss w si steel loss 13, 002, 000 Btu Determine amount & rate of regen gas needed Heat that must be transferred to the regeneration gas Q rg 2.5Q 2.5 13, 002, 000 =32, 505, 000 Btu regen 57

Example based on GPSA Data Book example 20-14 (#11) The regeneration gas is part of the plant s residue gas (at 600 psia & 100 o F) & has a molecular weight of 17. The bed must be heated to 500 o F for regeneration Determine amount & rate of regen gas needed (cont.) Determine amount regen gas needed o o C, 0.65 Btu/lb F (based on Fig. 23-48 in GPSA EDB averaged between 100 & 550 F) m prg rg Qrg 32, 505, 000 111,100 lb C T T 0.65 500 50 100 prg, rg cold Determine rate of regen gas needed m rg mrg 111,100 15, 430 lb/hr 257 lb/min t 0.6 12 58

Example based on GPSA Data Book example 20-14 (#12) The regeneration gas is part of the plant s residue gas (at 600 psia & 100 o F) & has a molecular weight of 17. The bed must be heated to 500 o F 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 (@ 550 o F): PM 60017 lb rg 0.94 3 ZRT 1 10.7316550 460 ft u rg V rg 4 m 4 257 6.2 ft/min A 0.94 rg D 2 rg 7.5 2 0.023 cp (from Fig. 23-23 in GPSA EDB) P 2 5 2 psi B u C u 0.056 0.023 6.2 8.89 10 0.94 6.2 0.011 L ft Flow rate is sufficient 59

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 H 2 S + CO 2 COS + H 2 O 60

Other Dehydration Processes

Other processes Consumable salts (CaCl 2 ) 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 80 o C) 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 http://twisterbv.com/pdf/resources/twister_-_how_does_it_work.pdf 63

Comparison of Dehydration Processes For < 1 ppmv H 2 O 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 (CaCl 2 ) for remote, low water content gas 64

Summary

Summary Water content can be estimated from Fig. 20-4 Units of lb/mmscf Wet & 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 stripping still contactor reboiler http://www.kirkprocess.com/products/highspeed-gas-dehydration/ 68

Glycol Dehydration Unit stripping still contactor reboiler http://www.en-fabinc.com/en/glycol_dehydration_system.shtml 69

Mole Sieve Dehydration Unit http://www.enerprocess.com/processing-&-treating-units/gas-conditioning-&-treating/mol-sieve-dehydration-units 70

Zeolite structures Zeolite A Zeolite X 71