A customer who was experiencing some issues with a blow off process in their facility contacted EXAIR for a solution. This customer performs post-harvest processing operations on green beans and other vegetables after they’ve been picked. They were having a problem being able to remove excess moisture after the beans had been washed in cold water and keep additional moisture from forming once packaged. The process involved green beans exiting a wash cycle and moving along a belt conveyor. From there, they are dried by a series of blower style air knives. Shortly after being blown off, the beans are weighed and bagged. Once bagged, it was determined that there was too much moisture inside the package and they could not be shipped.

One common issue with blower style knives, and the fundamental issue in this application, is that the air is heated as it moves through the blower. Depending on the type of blower, outlet air temperatures in excess of 180°F are normal. The effect, in this case, was similar to a convection oven where hot air is circulated over the food to cook it. While the beans were not exposed for a long enough time to actually cook, the high temperature air exiting the blower was enough to raise the temperature of the beans. This caused additional moisture to come out from inside the beans after they were bagged and sealed. This is a condition that the customer wanted to avoid because it would lead to the beans drying out and losing their freshness which is a quality issue for the customer.

A second problem was the turbulent airflow from the blower knives causing the beans to be blown all around on the conveyor. The customer effectively had no control over how forcefully the airflow from the blower powered air knives impacted his product. They were either full-on or full-off. This resulted in less than desirable results from a dryness perspective and also caused damage to the product from the high impact disturbance of the blower air knives.

After talking it over with the customer and learning the specifics of the application, we determined that EXAIR’s Super Air Knife Kit Model 110212SS is able to address both of these issues. The airflow would be at ambient temperature, keeping the product at a desired colder temperature. The blowing force could be precisely adjusted with a pressure regulator so as not to cause damage to the product and provide a laminar airflow to strip the water from the product.

EXAIR’s Super Air Knives are available in 303 or 316 grade Stainless Steel to meet the more stringent requirements of many food grade applications. They also operate at a far lower sound level than blower powered air knives, are more compact for easier mounting, and do not involve the purchase of a blower package and associated ducting.

Our Application Engineers can work closely with you to resolve any issues you may be having, even if compressed air isn’t currently a part of the process. If your process involves washing, drying, conveying, or packaging food or other products and you can relate to any of the issues above, please keep EXAIR Corporation in mind as a viable solutions provider. Contact an Application Engineer today and we’ll do our best to help you solve your application problems.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@exair.com
Twitter: @EXAIR_TD