Regenerative Dryer Terms Renew - restore. Regenerate: Absorbent Desiccant: Used in HP dryers. Adsorbent: To collect on and within the surface in condensed (liquid) form. Adsorbent Desiccant: Used in regenerative dryers. The desiccant does not deliquesce. The liquid water collects on and within the surface of the desiccant. Adsorbent desiccant can be regenerated (renewed). A A d d sorbent Desiccant is sorbent Desiccant is more hygroscopic than more hygroscopic than A A b b sorbent Desiccant sorbent Desiccant
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Adsorbent Desiccant is more hygroscopic than Absorbent Desiccant
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Regenerative Dryer Terms
Renew - restore.
Regenerate:
Absorbent Desiccant:
Used in HP dryers.
Adsorbent:
To collect on and within the surface in condensed (liquid) form.
Adsorbent Desiccant:
Used in regenerative dryers. The desiccant does not deliquesce. The liquid water collects on and within the surface of the desiccant. Adsorbent desiccant can be regenerated (renewed).
Maximum flow x temperature Maximum flow x temperature multiplier x pressure multiplier =multiplier x pressure multiplier =corrected flow.corrected flow.
Note: For temperature lower than 80Note: For temperature lower than 80°°F F consult consult Henderson Engineering Co., Inc.Henderson Engineering Co., Inc.
Pressure Modifier
P1 =114.7
P + 14.7
P1 = Pressure ModifierP = Minimum Inlet Air Pressure
S = inlet flow rate in SCFMV = vapor pressure of waterTC = time cycle (hours and minutes)P = absolute pressure; PSIG plus 14.718 = (constant) molecular weight of water379 = (constant) molal volume
S x V x TC x 18
P x 379
Example: 1000 SCFM, 125 PSIG, 100F
1000 x .950 x 60 min. x 24 hrs. x 18
139.7 x 379= 465
465 lbs. of water per day
Vapor Pressure of WaterTemperature
120115110
10510095
908580
757065
605550
454035
Absolute Pressure PSIG
1.6931.4721.275
1.102.950.816
.698
.596
.507
.430
.363
.305
.256
.214
.178
.147
.122
.099
Calculating Air Velocitythrough the Desiccant Bed
V = velocity in feet per minuteS = inlet air flow in SCFMP = inlet air pressureA = tower area in sq. ft.
To find tower area:
TD2 x .785
144A =
A = tower area in sq. ft.TD = tower diameter
14.7 x S
(P + 14.7) AV =
Determining Air-to-DesiccantContact Time
CT = contact time in secondsP = inlet pressure in PSIGAA = pounds activated alumina per towerS = inlet air flow in SCFM
(P + 14.7) 60 x AA
14.7 x S x 45CT =
Calculating Pressure Dropthrough the Dryer
PD = pressure drop in PSIGS = inlet air flow in SCFMM = maximum air flow at 3 lbs. dropP = inlet air pressure
x 344.1
P + 14.7PD =
SM
2( )
Determining Kilowatts Neededby the Heater on a
Heat Reactivated Regenerative Dryer
KW = actual KW requiredPR = purge rate in SCFMTD = temperature differential between
375 and inlet air temperature
PR x 1.08 x TD
3412KW =
Calculating Annual Operating Costfor a Heatless Dryer
C = annual operating costPR = purge rate in SCFM525600 = constant, minutes in a year1000 = constant, cost per 1000 cu. ft.S = cost of compressed air, normally
$.15 per 1000 SCF
PR x 525600
1000C = x S
Calculating Annual Operating Costfor an Exhaust Purge Dryer
C = annual operating costPR = purge rate in SCFMCA = cost of compressed air per 1000 cu ft.KW = actual KW requiredE = cost of electricity
PR x 525600
1000C = x CA + (KW x 6570 x E)
Calculating Annual Operating Costfor a Blower Purge Dryer
C = annual operating costHP = blower horsepowerKW = calculated heater KWE = cost of electricity
C = [(HP x 8760) + (KW x 6570)] x E
Calculating Annual Operating Costfor a Closed System Dryer
C = annual operating costHP = blower horsepowerKW = heater KWE = cost of electricityE = cost of electricityGPM = water rateWC = water cost/1000 gals.
(typically $.25/1000 gals.)
C = [(HP x 8760) + (KW x 6570)] x E +GPM x 525600 x WC