Plate heat-exchangers cleaning

Various designs of liquid/liquid heat exchanger are widely used. Choice is partly influenced by the cleanliness of the liquids and the need for regular cleaning. A compact and commonly used type is the plate heat exchanger. 

Plate heat exchangers are used extensively in the food and beverage industries, as they can be readily taken apart for cleaning and inspection. Their use in the chemical industry will depend on the relative cost for the particular application compared with a conventional shell and tube exchanger see Parker (1964) and Trom (1990). 

The costs for this form of exchanger are higher than those for gasketed plate heat exchangers. An important limitation is that they can only be cleaned chemically and not mechanically. 

Fmit) preparations are manufactured by either continuous systems (e.g. Ohmic heating, tube or plate heat exchanger, scraped surface heat exchanger) batch or microwave systems. The plant environment, the plant itself and the C.I.P. (Cleaning in Place) equipment are subjected to an intensive quality management. 

Where space is at a premium possibly in retrofit situations, it might be desirable to consider the use of a plate heat exchanger that in general requires less space for cleaning operations. 

The sponge rubber ball system is only suitable for cleaning the inside of tubes and therefore its use is restricted to tubeside single pass or possibly U tube designs for two passes in shell and tube heat exchangers. The system cannot be used for the shell side or for plate heat exchangers and other non tubular designs. 

Jackson, A.T., 1984, Cleaning characteristics of a plate heat exchanger fouled with tomato paste using 2% caustic soda. 1st UK Nat. Conf. Heat Transfer, I.Mech.E./I.Chem.E., 1, 465 - 472. 

These devices are similar with plate filters. Because of small cross section, intensive heat transfer can be realised, as for example from 400 W/m K with viscous fluids up to 6000 W/m K for water. Gasket plate devices are the most common. The effective area per plate can be larger than 1 m. Up to 400 plates can be assembled in a frame. However, the operation is limited to 30 bars and 250 C. Plate heat exchanger are intensively used in food and pharmaceutical industry, but less in chemical industries. Welded plate heat exchangers are similar. The operation can rise to 80 bars and 500 C, but cleaning is problematic. 

A typical cleaning sequence for plate heat-exchangers, enclosed fermenters, conditioning or lagering tanks, bright beer tanks and associated pipework is given below ... 

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