High pressure plunger pumps cleaning up at malting plant

Greencore Malt at Bury St Edmunds is the largest malting site in the UK and just one of seven plants operated by the Company. The 175,000 tonnes per year output from the malting makes Bury one of the largest and most modern malting complexes in Europe and it has been the focus of major expansion in recent years.

The malting’s principle products are for brewing, distilling and speciality beverages and the production processes involved place considerable importance on hygiene in order to ensure the integrity of the products. Hygiene means thorough cleaning of all plant and equipment and this is achieved by employing water jetting lances powered by Cat Pumps high pressure plunger pumps.

The cleaning system comprises of two Cat Pumps model 3521 stainless steel plunger pumps mounted on a bed plate together with two 30kW 4 pole motors. Power is transmitted to the pumps by belts with a reduction ratio of 2:1. A pressure regulating valve is fitted to manage the pumps’ output, together with accumulators to reduce water hammer and vibration. Each pump provides 87 l/min. at 140 bar, giving a combined output of 174 l/min. at 140 bar. Water flow and pressure are continuously monitored to start and stop the pumps in response to the demands of the cleaning system.

Each of the pump sets come with a simple galvanised enclosure to protect the pumps from water falling from above. The enclosure is easily removable to allow for maintenance and servicing operations. Both pumps run on demand to facilitate the use of up to 10 lances simultaneously. As pressure drops in the pipework system the combination of pressure and flow switches starts up one pump which runs for as long as demand dictates. In the event of demand exceeding the output of one pump set, the second pump set will start up automatically. Both pumps stop sequentially as demand ceases. 

The pumps serve two purposes; firstly they are used every day to enable the cleaning of buildings and machinery via hand held lances and with both pumps running they are capable of feeding ten lances. Secondly they are used as a backup system to automatically clean germination vessels. These stainless steel vessels are approximately 25 meters in diameter and they require regular and through cleaning.

Each vessel comprises two decks: the upper deck is where the grain is germinated and the lower deck is an air plenum chamber, which is pressurised with humidified air. This lower deck is very wet and humid which can cause very slippery algae to build up if it is not washed off every time the vessel is emptied. A single large pump is normally used to clean the germination vessels but in the event of failure the two Cat pumps can be used to ensure that there is no loss of production.