Plunger pumps for margarine plant

Cheshire, UK – Amtech Developments Ltd, which supplies food processing and packaging equipment, has started fitting Cat Pumps triplex plunger pumps to its shortening, margarine and low-fat spreads production equipment for this duty.

The first recipient of this pump type is a Nairobi-based food processing plant manufacturing shortening. Here, Amtech has replaced an existing positive displacement pump feeding the heat exchanger with a Cat Pumps’ model 3841 Stainless Steel 38 Frame block-style pump.

In margarine production the emulsifier is melted at about 90ºC and is then mixed with oil to form the oil blend. This blend is then transferred to an emulsion mixing tank and a specific volume of pasteurised water phase - typically containing salt and milk powder - is added, resulting in an emulsion.

Now at a temperature of around 40ºC, this emulsion needs to be rapidly chilled in a scraped surface heat exchanger to crystallise the fat content. Here, the high pressure triplex plunger unit pumps the oil/water emulsion, typically at between 20 and 70 bar, through the crystallisation equipment.

Once reduced to a temperature of between 10 and 15ºC, the crystallised fat turns the emulsion into a semi-solid (plastic) product. In this form, considerable force is required to keep an even and steady product flow through to the packaging line and it is the pump that overcomes the high back-pressure and ensures a smooth and continuous flow of product through to the packaging line.

In the case of shortening, no water phase is required, so it is typically just the oil/emulsifier blend that is pumped into the heat exchanger for rapid chilling.

“Neither shortening nor margarine are difficult products to pump”, comments Bob Willis of Amtech. “However, what the process requires is a pump that can operate against a high back pressure and for many centrifugal and positive displacement pumps this would exceed or be at the top end of their performance range.

“The quality of the shortening is affected if the pump does not provide its duty. With many shortening and margarine plants running 24/7, there is a great deal for the pump to do, making reliability, accuracy and maintainability a pre-eminent demand.”