Summary
McCain Foods Holland bv has four production facilities in the Netherlands, located in Hoofddorp, Lelystad, Waspik and Lewedorp, mostly producing French fries and potato specialities. During the process the potatoes are cut into fries and then blanched. Between blanching and frying the potatoes are also dried. This drying process removes water from the surface of the fries, which helps to make them crispy. The less water there is to be evaporated by the hot fat or oil, the less the fat deteriorates. The aim is to reduce energy consumption of the fryer and improve product quality.
Conventional dryers use hot air at approximately 100 °C and the discharged air has a relatively low humidity content (33%). This humidity content indicates the loss of energy from exhaust air. McCain in Canada has developed a dryer that can be operated at low drying temperatures (80 °C) and has an exhaust air humidity content of approximately 55%. This reduces the air throughput by 50%. Fuel consumption for heating the air in the dryer is reduced by 18%
or 781,000 m³ of natural gas. Electricity consumption is also reduced as there is less drying air. The drying temperature can probably be reduced further, to approximately 65 °C, thereby reducing energy consumption even more. Better quality means less rejection rate, thereby improving the energy efficiency and reducing reject handling costs. Lowering the drying temperature implies that the drying period needs to be extended. In order to maintain the same production capacity the dryer needs to be larger than a conventional dryer.
The project costs for the low-temperature dryer have been defined as the costs over and above those of a conventional dryer and are estimated at NLG 1,230,000. Total energy savings add up to NLG 230,000 per year. The payback period for energy savings is approximately 4 years.
Drying at low temperatures is suitable for many products that cannot be subjected to high temperatures. Low-temperature dryers are applicable to industrial drying processes, mainly in the food-processing sector.