Ammonia Automation

An Allen Bradley PLC based control system will monitor and control of the refrigeration system to include graphical user interface displays and control all current operating conditions, temperatures, pressures, motor amps, vessel liquid levels and alarm states. 

The ammonia automation system will manage the refrigeration compressors, condensers and evaporators.  The system will be designed to provide maximum energy conservation while maintaining the temperatures and pressures necessary for the refrigerated environment.  The control system will control compressor starting, stopping, loading and unloading to maintain a constant suction pressure utilizing the least amount of horsepower as possible.  All automation systems are customized to suit facility needs and include some of the functions described below.

Compressor Control
This module will control all compressors and suction pressures.  It will maintain
a suction pressure set point and maintain the minimum amount of compressor
horsepower on line to do this.  The program will provide a step control for
machines with discrete unloaders or proportional control for machines with
0 to 100% operation.  We have developed the software script to communicate with Vilter Vantage and Vission and All FES machines via high speed communications.  Frick machines can be monitored over the Qnet protocol.

Condenser Control
This module will control the head pressure to a user adjustable set point.  Staging of all fans and pumps will be provided.  Utilize floating head setpoint control based on current weather conditions. Use VFD fans to maximize air flow over entire condenser surface area to minimize power consumption.
Level Monitoring
Level monitoring will provide the capability to view and alarm on levels on the high pressure receiver, accumulators and recirculator.  The electronic level probes will be terminated at the PLC. 

Evaporator Control 
This module will sequence the automated defrost initiate commands for existing air units and include energy saving functions: Load Shed, Fan Stir, Demand Defrost based on run time and temperature difference and stage VFD fans to conserve energy at low load conditions.

Recirculator Pump Control 
This module will sequence the automated pumping of liquid supply to the process refrigeration equipment.  Pump safety controls are monitored to ensure pumps only run within design conditions, safeties include low liquid level, high motor temperature, low differential pressure, abnormal amperage, and bearing wear monitors.