Sullair LS-25S-257KW, Руководство оператора и список запасных частей

Страница: 12 / 83

Section 2
DESCRIPTION
7
needs. With a Sullair compressor, there is no
maintenance or inspection of the internal parts of
the compressor unit permitted in accordance with
the terms of the warranty.
Fluid is injected into the compressor unit in large
quantities and mixes directly with the air as the ro-
tors turn, compressing the air. The fluid flow has
three main functions:
S
As coolant, it controls the rise of air tem-
perature normally associated with the heat
of compression.
S
Seals the leakage paths between the ro-
tors and the stator and also between the
rotors themselves.
S
Acts as a lubricating film between the ro-
tors allowing one rotor to directly drive the
other, which is an idler.
After the air/fluid mixture is discharged from the
compressor unit, the fluid is separated from the air.
At this time, the air flows to the service line and the
fluid is cooled in preparation for reinjection.
2.4 COMPRESSOR COOLING AND LUBRICATION
SYSTEM, FUNCTIONAL DESCRIPTION
Ref er to Figur e
2 --- 2 . The c ool ing a nd l ubr ic ation
system consists of a
fluid cooler, aftercooler, full
flow fluid filters, fluid stop valve, thermal valve
and
interconnection piping. For water---cooled
models, a shell and tube fluid cooler and after-
cooler are mounted on the compressor package.
For air---cooled models, they are radiator---type
coolers which are mounted on separate cooling
packages.
The pressure in the receiver/sump causes fluid flow
by forcing the fluid from the high pressure area of
the sump to an area of lower pressure in the com-
pressor unit.
Fluid flows from the bottom of the receiver/sump to
the thermal valve. The thermal valve is fully open
when the discharge temperature is below 170
_
F
(77
_
C). The fluid passes through the thermal valve,
the main fluid filter and directly to the compressor
unit.
As the discharge temperature rises above 170
_
F
(77
_
C), due to the heat of compression, the ther-
mal valve begins to close and a portion of the fluid
then flows through the cooler. In the case of 24KT
compressors, as the injection fluid temperature
rises above 140
_
F (60
_
C), the thermal valve begins
to close and a portion of the fluid begins to flow
through the cooler. From the cooler, the fluid flows
to the main filter and on to the compressor unit. The
fluid filter has a replacement element and an inte-
gral pressure bypass valve.
The fluid stop valve prevents fluid from filling the
compressor unit when the compressor is shut
down. When the compressor is operating, the fluid
stop valve is held open by air pressure from the
compressor unit allowing a free flow of fluid from
the receiver/sump back to the compressor unit. On
shutdown, the compressor unit pressure is re-
duced, causing the fluid stop valve to close and iso-
late the compressor unit from the cooling system.
2.5 COMPRESSOR DISCHARGE SYSTEM, FUNC-
TIONAL DESCRIPTION
Refer to Figur e
2 --- 2 . The c ompr essor unit dis -
charges the compressed air/fluid moisture through
a discharge check valve into the combination re-
ceiver/sump. The discharge check valve prevents
air in the receiver from returning to the compres-
sion chamber after the compressor has been shut
down. The receiver has three functions:
S
It acts as a primary fluid separator.
S
Serves as the compressor fluid sump.
S
Houses the final fluid separator elements.
The compressed air/fluid mixture enters the re-
ceiver and is directed against the ends of the tank.
The direction of movement is changed and its ve-
locity significantly reduced, thus causing large
droplets of fluid to form and fall to the bottom of the
receiver/sump. The fractional percentage of fluid
remaining in the compressed air collects on the
surfaces of the dual separator elements as the
compressed air flows through them. Two return
lines (or scavenge tubes) lead from the bottom of
each separator element to the inlet region of the
compressor unit. Fluid collecting on the bottom of
each separator is returned to the compressor by a
pressure difference between the receiver and the
compressor inlet. Sight glasses are located in the
return lines to observe this fluid flow. There are also
orifices in this return line (protected by strainers) to
assure proper flow. By pressing the
Δ
P1 pad on the
Supervisor, the operator may monitor the condition
of the separator elements by reading differential
pressure on the digital display. At a differential of 10
psid (0.7 bar) or greater, the operator will be told to
service the separator element. At this time, separa-
tor element replacement is necessary.
The receiver is an ASME pressure vessel. A combi-
nation minimum pressure/check valve, located
downstream from the separator, assures a mini-
mum receiver pressure of 50 psig (3.4 bar) during
full load operation. This pressure is necessary for
proper air/fluid separation and proper fluid circula-
tion while supplying air to the system. This valve
also acts as a check valve preventing compressed
air in the service line from bleeding back into the re-
ceiver on shutdown and during operation on the
compressor in an unloaded condition.
A pressure relief valve (located on the wet side of
the separator) is set to open if the sump pressure
exceeds 150 psig (10.3 bar).