Sophisticated Control Systems

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Central Refrigeration System Control

Problem

Screw compressor controls failing, high electric demand and time-of-day rates, hot gas defrost issues, inefficient condenser control, difficulty monitoring and controlling various refrigerated storage and production rooms, refrigeration gas leaks, and frequent power outages causing screw compressors to shut down and not restart without an operator present — plus concerns about monitoring for costly excessive compressor and motor vibration.

Solution

Energy Consulting Services provided a turnkey control system that cured all the issues the client was experiencing. Our reputation has been built on a platform of spending time with our clients to get to know their operation, combined with our decades of control and systems knowledge.

Industrial control panel circuit boards and wiring

Nuts and Bolts

Control algorithms were written and hardware was installed to:

1Properly start and stop the screw compressors by integrating compressor slide valve positions, compressor amperage, system head pressure, oil pressure, oil temperature, and voltage.
2Properly monitor, alarm, and control refrigerant levels in refrigerant receivers — initiating shutdown of room refrigerant liquid solenoid valves and/or master valves based on refrigerant level conditions to keep the central refrigeration system operational. This sequencing is also pivotal to proper restarting upon a power outage or safety trip.
3Monitor the facility's electric demand and consumption by providing multiple temperature resets for refrigerated areas — allowing cooling of product during off-peak electric periods for up to half the high-peak electric cost, and coasting into the high-peak electric rate for hours without a refrigeration load.
4Properly terminate hot gas defrosts with electronic sensors in each evaporator to accurately terminate defrosts, allow accurate timing of multiple defrosts, and integrate with cooling tower control algorithms to raise head pressure during defrosts as required.
5Properly control the cooling towers to stage loading and unloading of fans and pumps with selectable time delays to prevent short cycling, while keeping a narrow low band of head pressure yet raising head pressure when hot gas defrost is required.
6Properly control and monitor refrigerated areas by integrating highly accurate electronic sensors to monitor room temperatures and evaporator temperatures — evaluating each system's performance and alarming if out of range.
7Change temperatures of production rooms based upon required operational parameters and time-of-day scheduling.
8Monitor refrigerant leaks with multiple sensors to both alarm and indicate where the leak is.
9Properly stop the refrigeration system high and low screw compressors upon a power outage or safety trip, then restart the system upon a return to normal parameters.
10Monitor the total and fault vibration of compressors and motors to proactively perform maintenance rather than experience a catastrophic system failure.
11Provide automated HACCP data gathering for effective control of food safety.

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