In food-processing applications, this technology excels at product recovery and waste reduction.
by Paul Cardon
October 8, 2015
Figure 1. Side-by-side comparisons illustrate how a series of significant design and operational benefits allow eccentric disc pumps to outperform lobe pumps in many critical food processing applications.Figure 1. Side-by-side comparisons illustrate how a series of significant design and operational benefits allow eccentric disc pumps to outperform lobe pumps in many critical food processing applications.
Image 3. The eccentric movement principle drives eccentric disc pumps, which use a disc inside the pump cylinder that is driven by an eccentric bearing on the pump shaft, creating four distinct pumping chambers. This produces a regular flow rate with no pulsing, cavitation, slip or shear.Image 3. The eccentric movement principle drives eccentric disc pumps, which use a disc inside the pump cylinder that is driven by an eccentric bearing on the pump shaft, creating four distinct pumping chambers. This produces a regular flow rate with no pulsing, cavitation, slip or shear.

For a food processing operation that may use the same pump to transfer different products, these pumps are also often unable to adequately strip lines, which is another critical consideration.

Lobe/ECP pumps have two shafts that must be sealed. This doubles the number of areas where leaks can occur. Their self-draining capability requires vertical porting, which can result in as much as a 25 percent decrease in volumetric consistency. Lobe pumps are not self-priming and can run dry for only a short period of time. Without lubricated seals, lobe pumps must operate at greatly reduced speeds in order to handle high-viscosity liquids, and they can experience diminished performance when handling low-viscosity liquids.

Table 1. Incorporating increased energy efficiency into food processing operations is one way to reduce operating costs. This chart shows how much money is consumed per positive displacement pump, if the cost for energy is $0.10 per kilowatt hour (KwH).Table 1. Incorporating increased energy efficiency into food processing operations is one way to reduce operating costs. This chart shows how much money is consumed per positive displacement pump, if the cost for energy is $0.10 per kilowatt hour (KwH).
Table 2. Useable raw materials or saleable finished products that cannot be recovered from inlet or discharge lines is akin to flushing money down the drain. Utilizing eccentric disc pumps presents an opportunity for food processors to maximize their product recovery rates, leading to significant annual cost savings, as the chart above illustrates.Table 2. Useable raw materials or saleable finished products that cannot be recovered from inlet or discharge lines is akin to flushing money down the drain. Utilizing eccentric disc pumps presents an opportunity for food processors to maximize their product recovery rates, leading to significant annual cost savings, as the chart above illustrates.

The Solution

Eccentric disc pump technology operates on the eccentric movement principle developed by French engineer Andre Petit. Petit's pump design features a disc that is placed inside a pump cylinder. The disc is driven by an eccentric bearing on the pump shaft, creating four distinct pumping chambers that increase and decrease in volume as the disc is rotated by the eccentric bearing. This movement produces both suction and discharge pressures as the chambers move in pairs that are 180 degrees apart. This ensures that the fluid passes through the pump at a constant and regular flow rate with no pulsing, cavitation, slip or shear.

Some eccentric disc pumps can pump air when no fluid is present. This creates a vacuum effect on the pump's suction side and a compressor effect on the discharge side. Once the product runs out in the feed tank, the eccentric disc technology continues to pump air in a constant, non-abrupt, non-pulsating manner so that the surface tension on any remaining fluid is not broken. This produces a plug effect, which pushes out the product "plug" as a whole.

One significant area in which the incorporation of eccentric disc pumps can have significant results is product recovery. Product waste in hygienic food processing is an area that incurs extremely high costs. The McKinsey Quarterly Food Waste Alliance has reported that more than $120 billion of product goes to waste worldwide annually. The Natural Resources Defense Council (NRDC) also estimates that the U.S. is losing 40 percent of its food from farm to fork to landfills. Between farm and fork are the processing plants that manufacture some of these products.

While many food processors turn to reduced energy expenditures as a way to reduce operational costs, eccentric disc pumps with a minimum product recovery capability of 70 percent have been shown to produce significantly higher annual savings. Product waste is a severe handicap to the manufacturer's bottom line, and product recovery is an opportunity to limit waste and gain cost savings.

The typical amount of product recovered by eccentric disc pump technology can be more than 95 percent on the suction side of the pump and typically 60 to 80 percent on the discharge side.

When used in food and beverage manufacturing operations, the eccentric disc pump serves as the normal process pump, with its product-recovery capability adding cost-saving value to the operation in the form of recovered and still usable raw materials or saleable finished products.

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