Anco Eaglin A-E Votator - Manual (Page 10)

10
Gravity System
Liquid Overfeed Refrigeration System
Brine Water Steam
Gravity System
In the gravity refrigeration system, liquid refrigerant flows from a
receiver in the compressor plant to a surge drum installed above
the Votator
® II or the Votator ® II Extra Heavy Duty. A modulating
thermostatically controlled expansion valve automatically maintains
the correct refrigerant level in this vessel. Gravity forces the
refrigerant into the cooling jacket, where product heat vaporizes a
portion of the liquid and reduces the bulk density of the remainder.
The flow of vapor and this density difference combine to create
the classic “thermosyphon effect,” which forces liquid refrigerant
to circulate from the surge drum to the cooler. A regulating valve
controls the pressure in the surge drum and, consequently, the
temperature of the refrigerant in the cooling cylinder. Make-
up liquid enters through the level control and the entire cycle
continues. Individual surge drums can be provided for each
cooling cylinder or a single drum can be used for two cylinders.
The gravity system protects against freeze-up through an
instantaneous current relay system. Optional hot gas controls also
can be provided for freeze-up protection and to assist in removing
refrigerant for pump down.
Liquid Overfeed Refrigeration System
Liquid Overfeed (LOF) is available on the Votator ® II and the
Votator ® II Extra Heavy Duty. It is a proven direct expansion
concept in which only 25-35% of the liquid refrigerant flowing to
the heat exchanger is actually vaporized. A large low pressure
receiver replaces individual surge drums. This receiver, normally
located in the compressor plant, is designed to separate the vapor
from the circulated liquid. Waukesha Cherry-Burrell has designed
many scraped surface heat exchangers for operating with Liquid
Overfeed refrigeration. Overload protection against freeze-up is
included and hot gas systems can be provided.
Liquid / Steam Jacketing
When using a liquid heat transfer medium, it is necessary
to maintain a high flow rate for optimum efficiency. This is
accomplished by using a centrifugal pump to maintain a constant
media flow. A controller monitors the product temperature out of
the Votator
® II heat exchanger and allows liquid media from the
supply to be introduced into the loop as required
Versatile Heat Transfer Systems