Van Air Systems PLD 8-2.8 User Manual
INSTALLATION, OPERATION AND
MAINTENANCE INSTRUCTIONS
PIPE LINE DEHYDRATOR FOR NATURAL GAS
PLD 8-2.8 thru PLD 36-2.8
PN 32-0280
REV A
FEBRUARY 2011
WARNING
DO NOT REMOVE, REPAIR OR REPLACE ANY ITEM ON THIS VESSEL WHILE IT IS UNDER
PRESSURE.
DO NOT OPERATE IF THERE IS A LEAK IN VESSEL. IMMEDIATELY TAKE VESSEL OUT OF
SERVICE AND CALL YOUR CERTIFYING AUTHORITY. IF THERE IS A LEAK, DEPRESSURIZE
VESSEL, INSPECT, REPAIR AND OR REPLACE AS NECESSARY.
DO NOT OPERATE ABOVE MAXIMUM WORKING PRESSURE (MWP) AND OR ABOVE MAXIMUM
OPERATING TEMPERATURE (DEGREES OF).
DO NOT WELD OR GRIND VESSEL. IT WILL NOT BE SAFE TO OPERATE.
DO NOT OPERATE IF THE VESSEL HAS BEEN DAMAGED BY FIRE. TAKE OUT OF SERVICE
IMMEDIATELY AND NOTIFY YOUR CERTIFYING AUTHORITY.
ANY DAMAGE TO VESSEL CAN MAKE IT UNSAFE. INSPECT OUTSIDE AND INSIDE OF
VESSEL REGULARLY FOR CORROSION OR ANY DAMAGE (I.E., DENTS, GOUGES OR BULGES).
IF DAMAGED, TAKE OUT OF SERVICE IMMEDIATELY. CALL YOUR CERTIFYING AUTHORITY.
1.0 OPERATION
A Pipeline Dehydrator removes the water vapor (humidity) present in the gas stream. The process cleans and dries the gas as it
ows through a vessel which is lled with a special drying agent
(desiccant). The dehydrator operates automatically. There are no
moving parts and no external source of power is required.
"Wet" natural gas enters the lower portion of the dryer where liquid
water and solid particles are separated by gravity and fall to the
bottom of the vessel. The gas moves upward through the prebed
and drying bed of Van Gas desiccant tablets. The tablets attract
and absorb moisture from the gas as it ows through the desiccant
bed. The tablets dissolve gradually as they absorb the moisture
and the liquid falls to the bottom of the vessel. The liquid run off in
the prebed creates an extended surface area capable of removing
additional moisture from the gas. This conserves the absorbent
desiccant tablets. The "dry" natural gas ows through the dryer
outlet.
The solution of dissolved desiccant and water that falls into the
claim area at the bottom of the vessel must be drained regularly to
prevent the vessel from ooding. An automatic drain valve can be
installed to prevent the vessel from ooding.
2.0 INSTALLATION
2.1 LOCATION
The ability of a dehydrator to dry natural gas is dependent on
the correct location of the unit. Temperature and pressure are
the keys to selecting the proper location.
IMPORTANT
ALWAYS PROCESS THE GAS THROUGH THE
DEHYDRATOR AT THE LOWEST TEMPERATURE
AND THE HIGHEST PRESSURE.
INLET GAS TEMPERATURE: Lower inlet gas temperatures will
result in a lower moisture content at the outlet of the dehydrator.
Locate the dehydrator at the point where temperature is the lowest.
CAUTION
The gas temperature should not exceed:
100°F for GASDRY PRIME
80°F for GASDRY PEAK
100°F for GASDRY MAX
MAXIMUM CAPACITIES - MSCFD
1,000 STANDARD CUBIC FEET PER DAY
AFTERCOOLING: If the gas being processed has been compressed
mechanically, an aftercooler, nned tubing or extended run of piping
will usually be necessary to reduce the inlet gas temperature to the
dehydrator.
OPERATING PRESSURE: More gas can be processed through the
dehydrator at higher pressures. Locate the dehydrator at the highest
practical pressure, but do not exceed the maximum rated working
pressure of the dehydrator. Refer to the capacity chart located below.
CAPACITY: The chart below indicates the maximum ow rate
through the dehydrator for a 24 HOUR period. To calculate the
capacity for a rate per minute just multiply the MSCFD RATE (from
chart ) by 0.6944 example:
A PLD 12-2.8 operating at 50 PSIG has a maximum MSCFD rate of
79. To gure the SCFM multiply 79 MSCFD x 0.6944 which equals
54.86SCFM
NOTE: This is the MAX instantanious ow that can be processed
through the dehydrator without deterioration of the drying
performance.
MODEL
NO.
PLD 8-2.8
PLD 12-2.8
PLD 16-2.8
PLD 20-2.8
PLD 24-2.8
PLD 30-2.8
PLD 36-2.8
PAGE 2
PART
NO.
80-1397
80-1399
80-1401
80-1403
80-1405
80-1468
80-1407
MAXIMUM
WORKING
PRESSURE
280 PSIG
280 PSIG
280 PSIG
280 PSIG
280 PSIG
280 PSIG
280 PSIG
50 PSIG
42
79
125
192
280
447
672
100 PSIG
75
141
221
341
497
793
1191
150 PSIG
108
202
317
489
714
1139
1711
175 PSIG
124
233
365
563
822
1312
1970
200 PSIG
141
263
413
638
930
1485
2230
225 PSIG
157
294
462
712
1038
1658
2490
250 PSIG
173
325
510
786
1147
1831
2749
280 PSIG
193
362
567
875
1277
2038
3061
2.2 PIPING AND ANCILLARY EQUIPMENT
2.3 INLET AND OUTLET PIPING
IMPORTANT
COMPLY WITH ALL FEDERAL, STATE, AND
LOCAL REGULATIONS CONCERNING
INSTALLATION OF NATURAL GAS SYSTEMS.
COMPLIANCE TO AND KNOWLEDGE OF ALL
REGULATIONS IS THE RESPONSIBILITY OF
THE INSTALLER.
Make sure that the temperature of gas is not over the maximum
for the desiccant being used. If gas temperature is too high, cool it
prior to the dehydrator.
Mount the dehydrator on a level surface capable of supporting the
weight of the vessel, such as a cement pad or a skid.
Install a pressure relief valve in the up-stream piping (relief
valve not furnished). A relief valve must be installed to
conform with the ASME Boiler and Presssure Vessel Codes,
Section VIII, Division 1 UG-125, Paragraph (1) and OSHA
standards. Also comply with all applicable Federal, State,
and Local codes.
FIGURE 2-A RECOMMENDED INSTALLATION
Two shut-off valves should be installed (not furnished with
dehydrator)-one at dryer inlet and another at dryer outlet. See
Figure 2-A Recommended Installation.
Connect the inlet and outlet piping as shown in Figure 2-A.
NOTE
Inlet and outlet shut-off valves will make start-up
and addition of desiccant easier.
2.4 AFTERFILTER
Van Gas "GF" Series Filters can be installed downstream of the
dehydrator to remove particulate contamination from the natural
gas. Contact Van Gas for details.
2.5 DRAIN VALVE
Install a drain valve (not furnished with dehydrator) in the drain
coupling at the bottom of the tower (except on PLD8-2.8). A oat/
auto drain valve system is available. Contact Van Gas for details.
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