Ammonia compressor replacements – Dairy Factory

Our client is Britain's largest producer of branded and private label dairy products, with a network of dairies and depots servicing customers throughout the country.

Our clients existing chilled water system at their production site in Shropshire, comprised of 4 x RC 911 Grasso compressors feeding 2-off gravity fed ammonia plate heat exchangers, each providing 1500 kW of chilled water with a flow temperature of +5°c. Changes to the system over the course of its life resulted in the plant having significant over capacity.

Seward Refrigeration Ltd were awarded the contract to replace the existing RC911 Compressor units 1 and 2 with 2-off fully independent Grasso M-Series inverter driven screw compressors, sited onto the existing compressor plinths. Each compressor provides 1158kw of duty, evaporating at +0.5 deg c, condensing +32 deg c. Each compressor comes complete with 200kw motor operating between 1,000 - 4,500 RPM, depending on load. The compressors have adapted variable internal volume ratio and continuous capacity control. With the two new compressors operational, the client’s requirement will be to use the two screw packs as lead compressors and the two remaining RC911 units as standby to facilitate future servicing of the screws or in the unlikely event of a screw pack failure.

Both new Grasso M-Series screw compressors were installed complete with new starter panels and inverter drives. The suction temperature is controlled by an RDM PLC as requested by our client. The RDM starts, stops, loads and unloads the No1 & No2 screw compressors along with the standby reciprocating machines.


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