PROPANE SIDE: Low pressure liquid propane absorbs heat and evaporates from the chiller. The low pressure gas is then compressed and sent to a condenser, where it will cool and become a high pressure liquid. An expansion valve will create a pressure drop for the liquid, which cools and re-enters the chiller as a low pressure liquid.
PROCESS SIDE: Gas enters the chiller heat exchanger, where it is cooled by the cold liquid propane.
Common Themes with Propane Refrigeration
Propane refrigerant gas is clean and dry.
The required refrigeration load is variable depending on inlet gas flow to the chiller.
Power consumption is dictated by the ambient temperature.
The heat duty, evaporator, and condenser temperatures are determined by the process requirements and the ambient temperature.
Propane Refrigeration Compressor Solutions
Rotary Screw Compressors provide unmatched operating flexibility to accomodate large flow changes. Many screw compressors also have an economizer port, which creates a pseudo two-stage system that injects a propane side-flow at an inter-stage pressure. This increases the heat duty and reduces the power requirements of the compressor. The economizer itself is an additional vessel with controls, but the operating cost advantages can quickly pay for the increased capital cost.
Indirect Cooling. These are often large compressors with massive volumes of oil. Although the condenser is typically outside the compression packager’s scope of supply, oil cooling is still required. Instead of a direct air-oil cooler, we use a glycol cooler for the oil. This reduces the overall volume of oil required, as well as eliminates cold-weather start-up difficulties by keeping the oil warm.