Drying Desk: How to reduce drying energy costs
Drying can be one of the most energy-intensive unit operations performed in your plant. With crude oil costs at about $50 per barrel, it’s more important than ever to control your drying operation’s thermal energy requirements. This column will discuss some ways you can do this.
Before you can determine how to reduce your drying energy requirements, you need to understand where the thermal energy in drying goes. As shown in Figure 1, heat, or thermal energy, is input to the dryer either via heated inlet drying gas (if your dryer is a direct-contact convection dryer) or via the dryer’s heated walls (if your dryer is an indirect-contact conduction dryer). The heat is distributed to the dried product, to the evaporation that occurs during drying, and to the outlet drying gas (which contains the evaporated moisture). Some thermal energy also radiates out through the dryer walls and components (called radiation loss)….