Demonstration and Commercial Implementation of Energy Efficient Drying for Walnuts
Energy Efficient walnut drying
The Issue
The walnut drying process, the most energy intensive step in nut processing, is a large consumer of natural gas and electricity. Even though the processors have attempted different approaches to reduce energy consumption for walnut drying, the average energy consumption is still high. Walnut drying requires an average of 12 therms of natural gas or 13 gallons of propane and 24 kWh of electricity per ton of dried nuts and inefficient operations may even use twice this much.
Project Innovation
This project will demonstrate a novel infrared technology for walnut drying at pilot and commercial scales to achieve 35-50% natural gas and electric energy savings by significantly reducing walnut drying time. This new technology uses infrared as an efficient heat source to quickly remove the surface and shell moisture of walnuts, followed by the final drying using hot air. Nuts are required to meet strict USDA standards for moisture content. With traditional methods, they are washed then moved to large drying bins where hot air is circulated for 12 to 24 hours. The wettest nuts are dried to the safe storage moisture to prevent mold development, resulting in 6 to 8 hours of additional drying time. As a result, nuts with low moisture are over dried. In addition to energy savings, the new infrared technology will improve product quality, and decrease product loss due to over drying. This new technology could also be used for drying other types of nuts.
Project Benefits
This new technology will reduce energy consumption by up to 50%, decrease drying time and produce a higher quality end product, while reducing product loss. This technology could reduce GHG emissions as the infrared emitters do not produce any NOx or greenhouse gases and the technology will also reduce natural gas consumption.
Lower Costs: This technology will reduce energy consumption during the drying process for walnuts by up to 50% resulting in lower production costs.
Greater Reliability: Reduced energy demand may reduce peak demand on the grid.
Environmental Benefits: This project will result in GHG emission reductions due to reduction in natural gas consumption.