Alfa Laval Contherm 6X11, Instruction Manual

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7 Operations
7.8 Operating the Contherm™ in an Ammonia or Freon Full-Flooded Refrigeration Configuration
The installation and set-up of the Contherm
™
for a refrigerated configuration is described in Chapter Six, Section 6.10 Installing
an Ammonia or Freon Full-Flooded Refrigeration System. An installation drawing of the configuration is provided in Figure
5-12. Refer to these portions of Chapter Five as necessary while performing the initial start-up and operating procedure
that is provided below.
7.8.1 Maintain Status Feature
Normally, when the product becomes too cold in the product cylinder (due to a product flow stoppage or a temperature
controller malfunction, etc.), the product becomes thicker and increases the load on the Contherms
™
drive system. With the
Maintain Status feature, the load on the Contherms
™
drive system is monitored. An ammeter is used with Contherms
™
equipped with electric drives.
When the drive system’s sensor reaches a predetermined set point (Set Point One), the main back pressure regulator closes.
The closure of this regulator causes the refrigerant pressure and temperature to increase to the preset auxiliary back pressure
valve setting values. Warming of the product occurs followed by a corresponding reduction in the load sensed by the drive
system sensor. The system is then automatically returned to normal operation.
If the drive overload condition persists, as may occur with a serious refrigeration malfunction, the product will continue to be
cooled and will become even thicker, further increasing the load on the Contherms
™
drive system. In such a situation, the
Maintain Status feature’s drive system sensor will reach the next predetermined set point (Set Point Two). When this set point is
reached, the liquid line solenoid valve will close and the Contherms
™
rotor will stop. Hot gas will automatically be introduced to
the annulus for one to three minutes.When this occurs, the operator must manually restart the entire system.
If your Contherm
™
is not equipped with the Maintain Status feature, then the drive sensor is not provided as part of the system
and the procedures described in the previous paragraph (i.e., closing of the main back pressure valve and the liquid line solenoid
valve, the shutdown of the Contherms
™
rotor, and the input of hot gas) must be performed manually.
CAUTION
Do not cool the water below 40
o
F (4.4
o
C).
Table 7-10. Start-Up and Operation of Contherm
™
With Ammonia or Freon Full-Flooded Refrigeration System
Step
Action
1
Start flowing the test product (water) through the Contherm
™
via the product inlet. When water exits the product
outlet, start the rotor.
Note: For best results, adjust the water inlet flow rate and temperature to that of the actual product.
2 Turn on the refrigeration system after the desired water flow rate is obtained.
3 Set the temperature controller, if provided, or adjust the back-pressure regulator for your desired temperature
setting. The product outlet temperature gauge should show the desired temperature within several minutes. Set the
controller or adjust the back-pressure regulator for several other temperatures setting and verify that the product
outlet temperature reaches the new setting within several minutes.
4 When you are satisfied that the Contherm
™
is operating properly with water as the product, shut off the refrigerant,
and drain and flush the water “product” from the system.
5
Your Contherm
™
is now ready to begin service.
1. Note: 1) For applications operated at below freezing temperatures, the product should be flowing through the
system and diverted back to the source before the refrigerant media is turned on. This will prevent a freeze up
from occurring as the product will not be exposed to a colder than normal cylinder surface. Divert the product
back to the source until the product is at the desired temperature, then begin the forward flow.
2. An adjustable back pressure regulator is required for systems that do not have a product temperature controller.
This regulator will be used to control the temperature of the refrigerant.
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