Special PHE designs for high quality sanitary processing

The plate heat exchanger is the heart of any beverage or dairy manufacturing process and hence a critical component of plant operations to deliver such excellence.

Heat Exchanger manufacturers strive for constant improvement in plate designs to enhance plant productivity. The physical designs of plates have evolved over the years. For fluid milk products, a herringbone or chevron plate pattern will allow the most efficient heat transfer and reduce consumption of utilities such as hot water, chilled water or glycol. More viscous products such as ice-cream mix and yogurt require reduced flow resistance; hence the use of ‘wide-gap’ style plates that allow lower pressure drops and increase CIP response. An expanded inlet design and a wider gap is preferable for such applications to resist fouling. With a much wider range of products being processed in modern manufacturing facilities it is very important that a sanitary or hygienic style plate is used. Narrow gap, thin plates may provide a lower initial capital cost, however in the long run it is much more cost efficient to invest in a sanitary/hygienic style of plate which is specially made to process food, beverage and dairy products.

AGC Engineering’s Sanitary Proflow™ Series of plates have been specifically developed for food, beverage and dairy applications. Features include an enlarged ‘free-flow’ inlet design, providing lower pressure drops - especially when running viscous products and allowing higher CIP flow rates for improved cleaning. {See Figure 1}. The line contact inlet and standard plate thickness’ of 0.7mm and 0.9mm gives superior strength and improved flow characteristics, ensuring there is no premature plate failure. The plates have a metal to metal alignment device and reinforced side band, with the honeycomb design adding significant plate support compared to older style designs. The plates also have a special cleaning channel and a partially relieved gasket groove for true hygienic processing, with the snap-in style gaskets allowing for easy maintenance.

AGC Engineering supplies global beverage and dairy processors and the Proflow™ plates have been proven to provide significant advantages compared to older style designs. One major reason for this is AGC Engineering works very closely with customers to develop the right solutions at their R&D Facility. The rheology of fluids is a dominant parameter for accurately calculating the heat transfer and pressure loss characteristics in a plate heat exchanger. The use of product specific rheology equations in the prediction of plate heat exchanger performance produces the best results for the processor. AGC Engineering works with processors to test their products at the AGC Engineering Research & Development facility. Rheology equations for use in heat exchanger calculations are developed using a rotational rheometer with the geometry precisely controlled to yield the most accurate viscosity measurements. This test is accomplished on a viscometer that can test across a wide range of temperatures and various shear rates yielding a precise mathematical equation for the product. After testing, the data is incorporated into AGC Engineering’s plate sizing program which accounts for the changes in the physical properties of the fluids as they move through the unit. This is achieved by simultaneously solving the set of non-linear differential equations that can be written for the heat exchanger. The specially developed plate program provides real world solutions, resulting in the optimum design and maximum benefit for the customer.

Frame designs have also seen significant improvements recently. Larger processors manufacture much higher volumes (and a wider range) of products. In addition to this, the increased focus on hygienic standards and the need for superior product quality requires an easy maintenance frame. Twin spindle frames allow even closing and trouble free operation. AGC Engineering has further enhanced this concept with a hydraulic frame which includes a self contained automatic closure end support. {See Figure 2}. A single operator can open and close a complete multi-section PHE in a matter of minutes via a lever. A hydraulic relief valve regulates the tightening and stops at the required compressed dimension. This simple, clean design allows higher production volumes and increased frequency of checking PHE components thus maintaining high sanitary standards. Hydraulic closure frames are becoming increasingly popular with major processors because they have recognised the economic advantage of this style of frame.

While innovative plate and frame designs are essential for manufacturing high quality products, one must remember that proper maintenance programs are essential to ensure product quality. There are several methods of testing for pin-holes. Some tend to be quite time consuming and messy such as the visible red/white spray or using a florescent penetrant and a black light. Other methods can be ambiguous due to the heavy dependence on the operator’s judgment or opinion – for example conductivity / ultrasonic and helium gas tests. To be sure of an accurate test a trained, experienced technician is needed who is familiar with the wear characteristics and functionality of the specific plate being tested. Most importantly, the unit must be opened and visually inspected to check the product contact surfaces and also assess the gasket and frame condition. AGC Engineering’s Platecheck™ method uses a water soluble, inhibited food grade dye (AGC RI-606). This dye method has consistently been proven to find plate pin-holes or cracks as small as 3 microns. The dye is circulated in a complete circuit, on one side of the plates, under pressure. Findings are presented in a written report including photographs of problematic areas and also potential future failures.

Please contact AGC Engineering for detailed information on the Proflow™ range of plate and frame heat exchangers and PlateCheck™ heat exchanger testing.

Export Sales Manager:
Rajib Datta (Melbourne, Australia)
Phone: +61 401 931 981
Web: www.AGCEngineering.com