Equans came out on top
The Van Oorschot family mainly washes agricultural produce. Father, mother, and son also provide refrigeration for third parties. In their seven cold stores, they can dry and store up to 5,000 tonnes of products, thanks to a powerful ammonia condensation dryer from Equans Refrigeration. Kees van Oorschot: “We asked three companies for a proposal. With their technical knowledge and good price, Equans came out on top”.
The condensation dryer offers more possibilities than mechanical refrigeration. “If the products arrive in the shed in poor condition, or if we have just washed them, we need to get rid of the moisture as quickly as possible. The best way to do this is with a condensation dryer,” says son Bram. “In principle, we can dry by cooling, but we can’t achieve the drying capacity we have with the condensation dryer – an average of 80 to 100 litres of moisture per hour – with mechanical cooling. This leaves us stuck at 20 to 30 litres.”
Whereas most companies use a condensation dryer for potatoes and onions, Van Oorschot also deploys the system for winter carrots and washed celeriac. That requires more from the refrigeration system, because each product has different moisture content and different cooling or heating requirements. The complexity, according to Van Oorschot, was therefore in the programming of different storage programmes.
“To be honest, it was a challenge to get the controls right,” says Kees. “At that time, Equans already had experience with condensation drying of onions and potatoes, but not with other arable products. We had to spend the first year figuring out the right settings for these products. Based on our input, Equans started tinkering with the storage programmes the following year. In the second storage season, the system performed better. The following year we were able to fine-tune many things. We are almost optimally using the possibilities of the system now. And Equans, in turn, knows what the optimum settings are for each product. ‘Our programme’ and the type of installation have now been applied at several clients.
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Over a 14-day period, the condensation dryer extracts an average of 5 to 6 percent water from onions. The dehydration of potatoes is exactly 3 percent. “Ideal,” says Bram. “This way we keep more kilos (of product) for the customer.”
Van Oorschot also places freshly washed celeriac tubers in the cold store. “Together with Equans, we figured out how to remove the washing water from the tubers using the condensation dryer. After a few adjustments to temperature, air speed, and humidity, we extracted 60 to 70 kilos of water from 1 cubic metre of tubers. A nice bonus,” says Bram. “The condensation that sticks to the slats in the evaporator flows into the drain and is collected in a water basin. We use this water to spray away pesticides off the field. Economical and effective.”
Van Oorschot handles heat just as efficiently. Since the cooling system is constructed as a heat pump, cold and hot energy flows can be reused. Kees: “The heat released during drying or cooling in one cell can be used in another cell, for example to heat onions. Sometimes we use it for underfloor heating in the intermediate hall. We place sweet potatoes out from the cold store in crates on this floor. This way, the products warm up slowly and in an environmentally friendly way.”
The entrepreneurs are delighted with their condensation drying system. “It is a godsend to us,” says Kees. “The system simply works well and offers flexibility. We can easily switch from heating up or cooling down batches very slowly. It is also possible to adjust the standard settings in small steps if a product requires it. I would definitely recommend a condenser dryer to colleagues. With it, you can always dry and keep your product in optimal situations without outside air, heaters, or sprout inhibitors.”