Vogt P-24AL, Руководство по обслуживанию

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P24AL & P34AL Service Manual
HOW YOUR TUBE-ICE MACHINE WORKS
12/2016
4-1
4. How Your Tube-Ice Machine Works
Operating Features. Your low side 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, Figures 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
features automatic stop safeties, including cutter and pump motor overloads, as well as other
auxiliary motor overloads. It will also stop automatically due to high head pressure and low suction
pressure conditions (if field wired to the high side). 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 refrigerant
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) to the
suction header and back to the compressor. The cool gas from the evaporator is compressed to a high
temperature, high pressure gas which discharges through the oil separator (then through the heat coil
of the receiver, when installed) and to the condenser. In the condenser, heat is removed and the gas
is condensed to a high temperature, high-pressure liquid. The high-pressure liquid passes through
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, completing the circuit.
The freezing period is completed by action of the freeze timer (1TR) 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 (18R) 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 is discharged through the ice discharge
opening.
See “Freeze Period” and “Harvest Period” for additional details.
Freeze Period. Water is frozen inside the stainless steel tubes of the freezer (2) by the direct
application of refrigerant to the shell side of the tubes. Ice is produced from constantly circulating
water down each tube. As the ice thickness increases, the freezer suction pressure decreases. At a
set time, the freeze timer (1TR) energizes the relay (1CR), which stops the water pump, closes the