MEETING THE SANITARY HEAT TRANSFER CHALLENGE
Plate Heat Exchangers (PHEs) are used to cool, heat and pasteurise product at key stages in many processes. Their combination of light weight, high efficiency and compact size has proved especially suitable for sanitary duties in the food and drink sectors.
Although the PHE concept is fairly universal, plate design and gasket technology are the real keys to thermal efficiency and reliability. Alfa Laval has developed thinner plates, patented distribution systems for more uniform flow distribution and turbulent flow to provide close temperature approaches, low fouling tendencies and, thus, more efficient heat transfer. Advances in gasket technology such as food grade materials and glue-free Clip-On versions make them particularly suitable for sanitary food processing duties.
These attributes are all apparent in the FrontLine range of sanitary heat exchangers which uses a precision-cut, stainless steel frame in conjunction with either conventional Front gasketted PHEs, Gemini Double Wall PHEs or Widestream PHES, depending on the nature of the duty. FrontLine frames were designed specifically to meet the exacting hygienic standards of the food and beverage industry, with clean lines, simple opening and closing and rapid connection to process or CIP lines.
Front gasketted plates offer a combination of high pressing depth and a pattern with relatively few contact points to provide longer operation with fewer interruptions. When the plates are assembled into a pack and tightened in a frame, corrugations in their surfaces form flow channels for the two media. The plates also have a distribution pattern which provides uniform flow across the entire heat transfer surface while small diameter ports facilitate cleaning in place (CIP) using the same flow as the process itself.
Front plates are supplied with glue-free Clip-On gaskets, made from food grade materials, which are easy to replace while the plates remain in the frame.
Hygienic double-wall plates increase sanitary safety
Gemini plates are used to provide mix-proof heat transfer where no cross-contamination between the product and the heating/cooling medium can be allowed. In the event of a plate cracking, this arrangement ensures that there is no inter-mixing of the two fluids and that there is an immediate visual indication of a leak.
The Gemini plate consists of two sheets formed together, to minimise the air gap between them, and sealed using a single gasket. When the plates are assembled together into a pack, the corrugations in their surface combine to form channels through which the media flow in direct counter-current.
Meeting the challenge of pulp and fibres
Widestream PHEs – as the name implies – have wider channels to allow the processing of fibrous and particulate products such as fruit juices with less risk of fouling. The special plate design features fewer contact points to allow for the formation of wider channels once the plate pack is assembled; a configuration that also enables longer operating cycles than usual and that lends itself to efficient Cleaning In Place (CIP).
The latest addition to the FrontLine range is the Front 8 PHE. As with all PHEs, the number of plates employed is determined by the flow rates, physical properties of the fluids, pressure drop and desired temperature programme of the duty. Thanks to the modular plate and frame approach each Front 8 PHE can be sized precisely for a given duty with no risk of over-engineering and, like all PHEs, can be scaled up or down to meet future needs simply by adding or subtracting the required number of plates.
Each Front 8 plate provides 0.38 m2 of heat transfer surface and can be supplied in AISI 316 stainless steel, Titanium or other exotic materials depending on the nature of the duty.
For more information contact Alfa Laval Ltd, Camberley, Surrey
Tel: 01276 63383 Fax: 01276 413524
E-mail: general.uk@alfalaval.com Web: www.alfalaval.co.uk
