VOGT ICE TUBE-ICE P-24A, Service Manual

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P24A & P34A Service Manual
HOW YOUR TUBE-ICE MACHINE WORKS
8/25/05
4-1
4. How Your Tube-Ice Machine Works
Operating Features. Your packaged Tube-Ice
®
machine is an efficient ice producing plant. If
installed and maintained properly, it will give many years of operation with a minimum amount of
repairs. Refer to piping schematics, FIGURE 4-1 and 4-2 to identify component parts while
following the information and instructions in this manual.
The machine is manually started and stopped by the START and STOP push buttons. The machine
will automatically stop by safeties such as compressor, cutter and pump overloads, as well as other
auxiliary motor overloads. It will also stop automatically by high head pressure, low suction
pressure or low compressor oil pressure. The circulating water pump can be operated independently
for chemically cleaning the freezer tubes and water tank by use of the HAND/AUTO selector
switch. The machine can be manually forced into a harvest cycle with the manual harvest push
button.
Principle of Operation. The freezer (2) is a shell and tube-type vessel. During the freezing period
(cycle), water is constantly recirculated through the vertical tubes of the freezer by a centrifugal
pump (6). Make-up water is maintained by a float valve (12) in the water tank (7). The float switch
(10) opens and closes the liquid feed “A” solenoid valve (20) and maintains the desired refrigerant
level in the freezer (2) (evaporator).
Refrigerant gas from the top of the freezer (2) passes through the suction accumulator (88) and to the
compressor (3). Here, the cool gas is compressed to a high temperature, high pressure gas which
discharges through the oil separator (14), then through the heat coil of the condenser and then into
the P24 condenser/receiver (15). P34A condenser (15C)/receiver (15R). In the condenser, heat is
removed and the gas is condensed to a high temperature, high pressure liquid. The high pressure
liquid goes out the liquid line through a strainer (43), liquid “A” solenoid valve (20) check valve
(101), and hand expansion valve (17). At the hand expansion valve (17), the refrigerant expands
from a saturated high pressure liquid state to a low pressure, low temperature liquid. This cold
liquid enters the freezer (2) where it absorbs heat from the circulating water in the freezer tubes.
Cool gas is again pulled out of the freezer through the suction outlet, thereby completing the circuit.
The freezing period is completed by action of the freezer pressure switch (2PS) in the control panel.
The water pump (6) stops and the “A” solenoid valve (20) closes. After a delay of 20-30 seconds,
the cutter motor starts, the thawing gas “D” solenoid valve (18) opens, and the harvest (thawing)
timer (2TR) is activated. Warm gas from the receiver is discharged through the thawing chamber
(16), check valve (101), and into the freezer. There it warms the refrigerant and the outer surface of
the freezer tubes, allowing the ice to release on the inside of the tubes and drop down onto the
rotating cutter for sizing. After sizing, the ice drops on the tines cutter disc and discharged through
the ice discharge opening.
See “Freeze Period” and “Harvest Period” for more detailed description of machine.
Freeze Period. The Tube-Ice
®
is frozen inside the stainless steel tubes of the freezer (2) by the
direct application of refrigerant to the outside shell side of the tubes. Ice is produced from
constantly recirculating water down each tube. As the ice thickness increases, the freezer suction
pressure decreases. At a set pressure, the freezer pressure switch (2PS) energizes the relay (1CR),
which stops the water pump, closes the “A” liquid feed solenoid valve (20), turns out the two pilot
lights, ammonia feed and freezing.