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Below is a description of the System Components
of the
Helium Refrigerator / Liquefier System for sale.
Cold Box
The helium liquefier / refrigerator cold box is a
Cryogenic Consultants, Inc. CCI Model 300 JPS with the
optional wet engine module. The cold box was
manufactured by Meyer Tool& Manufacturing Incorporated,
Oak Lawn, Illinois. The cold box is designed to produce
400 watts refrigeration at 4.5 K or 100 liters of liquid
helium per hour from warm helium gas. Liquid nitrogen is
supplied to the cold box as a pre-coolant. Liquid
nitrogen consumption is rated at 0.7 liters of liquid
nitrogen per liter of liquid helium produced.
Photo 1 - CCI Cold Box
The ‘cold box' is a super insulated, vacuum jacketed
component containing the heat exchangers, extended stem
cryogenic valves, expansion (JT) valve and a piston type
expansion engine. Helium gas, compressed to265 PSIG,
enters the cold box at near room temperature and is
cooled with liquid nitrogen and low pressure helium gas.
The high pressure helium is further cooled by the cold
helium gas exiting the piston expansion engine. This low
press cold gas is produced when a portion of the high
pressure gas stream expands in the cylinder of the
"piston type" expansion engine. The remaining high
pressure helium gas travels to a JT expansion valve or a
wet expansion engine where the temperature of the gas is
reduced to the liquefaction temperature of helium. The
liquefied helium exiting the JT valve or wet expansion
engine is transferred to the liquid helium dewar through
bayoneted vacuum jacketed transfer tubes. A small
portion of the helium returns as cold helium gas to the
cold box to be used to cool the high pressure helium gas
stream.
Photo 1 shows the cold box as manufactured.
Modifications to the instrument panel on the cold box
can be seen in Photo 2. The changes include moving the
gas expander speed control box to a location above the
control panel. An electrical enclosure was installed in
place of the speed control box to house three PID
controllers.
Photo 2 - Modified Control Panel
Controls
The system is controlled with pneumatic actuators and
controllers. However the helium suction pressure
incorporates a duel output PID controller and two I/P
transducer controlled pneumatic actuated valves to
supply helium make up gas or remove excess helium in the
suction manifold. A common problem associated with
pneumatic controls is the internal corrosion created by
moisture carried in with the instrument air. Rather than
using compressed air, this system has been operated from
the boil off nitrogen gas created in the liquid nitrogen
storage tank. As a result, the controllers and actuators
are clean and corrosion free.
Helium Gas Management Rack
The helium gas management rack consists of three
pneumatically controlled valves used to maintain
compressor discharge and suction pressures. The valves
are compressor discharge or "by-pass valve", suction
make up and suction withdraw valves.
Photo 3 - Gas Management Rack
Compressor
Photo 4 - Sullair Compressor
The helium compressor is an oil flooded screw compressor
Sullair Model C20LA 704-48-400 HP. The compressor is
driven by a 480 Volt AC electric motor with a rating of
400 horse power. The screw compressor has a built in
slide-valve to match compressor capacity with
refrigeration load thus permit efficient system
operation.
In photo 4, the electric motor is the gray unit located
on the right side of the vertical oil knock out tank.
Photo 5 - Recovery Compressor
Recovery compressor
A 25 HP Dunham Bush Compressor, seen in Photo 5, stores
the helium boil-off cryostats when the Sullair
compressor is off. The small compressor can be used to
circulate ambient temperature helium to warm cryogenic
devices.
A 25 HP Dunham Bush Compressor, seen in Photo 5, sends
helium boil-off gas to the storage vessels when the
Sullair compressor is off. The small compressor can be
used to circulate ambient temperature helium to warm
cryogenic devices.
Compressor Oil Purifier
The DuPont LB 170X oil is processed before installation
into the Sullair compressor. The process, seen in Photo
6, heats the compressor oil in the two vertical tanks
while under vacuum to remove moisture or chemicals that
may separate from the oil during compressor operation.
The oil in the two tanks can be pressured and sent
directly into the oil knock out tank as needed.
Photo 6 - Compressor Oil Purifier
Cooling Tower
The Sullair and Dunham Bush Compressors are water cooled
by a 125 Ton Delta Cooling Tower. The water is
circulated by a 300 gallon per minute centrifugal pump
through a PVC piping system. The tower shell is made of
seamless polyethylene (LDPE). The wet decking and drift
eliminator are constructed from a spiral, one piece ABS.
The blower fan motor is a 15 HP, 460 volt, 60 Hz., 3
phase, ODP type.
In Photo 7, the black Delta Cooling Tower can be seen
located in front of the helium gas storage tanks. The
squirrel cage type fan can be seen on the left side of
the tower body. The venting air flows upward through the
tower. The water make up valve for the tower is located
in the gray box to the right of the tower body. The make
up water valve provided by the manufacturer of the tower
was located inside the tower. Problems associated with
this location resulted in the relocation and redesign of
the make up water system.
Photo 7 - Delta Cooling Tower with Helium Vessels in
Background
Storage
Helium Gas Storage
The helium gas is stored in two horizontal 12,000 gallon
pressure vessels as shown in Photo 8. The tank
dimensions are 84 inches outside diameter by 45 feet 2
9/16 inches long and has weld on tank saddles. Each
vessel was manufactured for a working pressure range of
‘full vacuum' to 250 PSIG at a temperature of 125°F. The
weight of each tank is 21,000 pounds. The volume of
helium gas in each pressure vessel when at rated
pressure will produce 1000 liters of liquid helium.
Suction Buffer Tanks
In Photo 8 the two 1000 gallon pressure vessels used as
suction pressure buffer tanks can be seen mounted on top
of the 12,000 gallon tank on the left. The mounting
platforms were included in the design of the tank and
installed by the tank manufacturer.
Photo 8 - Helium Gas Storage Tanks
Liquid Nitrogen Storage
Photo 10 - Liquid Nitrogen Filter
Photo 9 - Liquid Nitrogen Tank
A 3,000 gallon liquid nitrogen tank provides pre-cooling
to the refrigerator and cooling to the thermal shield in
the 1500 liter helium dewar. The LN2 tank is connected
to the cryogenic test area by a vacuum insulated
transfer line. The nitrogen gas is used for instrument
air and also available for pump down and purge of
insulating vacuum spaces.
In Photo 9, the liquid nitrogen vaporizer can be seen
mounted to the liquid nitrogen tank.
In Photo 10, the vacuum jacketed liquid nitrogen filter
is used to remove moisture introduced by supplier during
liquid nitrogen filling of the storage tank.
The liquid nitrogen fill pedestal, seen in Photo 11, is
located at the curb side for ease of refilling. Photo 12
shows the liquid nitrogen pedestal located at the liquid
nitrogen tank.
Photo 12
Photo 11
Photo 13 - Liquid Helium Tank
Liquid Helium Storage
A 1500 liter liquid helium dewar stores and distributes
the liquid helium through two flow control valves
equipped with bayoneted ports The valves are a low heat
leak design utilizing springs to close and a stainless
steel pull rod to open. The liquid helium valves are
positioned with a Foxboro / Jordan Model VA-1110
electric actuator. The valve position is determined by a
4-20 ma signal from a temperature controller or liquid
level controller.
The liquid helium dewar contains liquid nitrogen
reservoir to provide coolant to a thermal shield.
Other Components
Photo 14 - CVI Vacuum Pump Out
Vacuum jacketed piping
All cryogens are transferred between components through
vacuum jacketed, superinsulated piping. Each vacuum
space is equipped with a DV-6 thermocouple vacuum gauge
and a CVI pump out / vacuum relief valve as shown in
Photo 14.
Connecting piping and fittings
All high and low pressure helium piping is fabricated
from 304 stainless steel pipe or tubing.
Written Safety Plan
Lockout / Tag out Procedure - contains a detailed
lockout / tag out procedure including flow drawings.
Photo 16 shows isolation valve locked out.
Photo 16 - Valve Locked Out
Photo 15 - Lockout / Tag Out Center
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