Reducing Costs and Harmful Emissions with Green Drying
Highly Efficient and Eco-Friendly
Steam tube dryers are indirect-heat dryers utilizing the latent heat from clean low-temperature saturated steam rather than hot gases used in fossil fuel-fired combustion systems. This highly efficient heat-transfer design also makes steam tube dryers one of the most thermally efficient drying technologies.
Pictured Above - the inside of a steam tube dryer
Some rotary dryer manufacturers specialize in green drying by incorporating low energy and ecological features into their designs. Such eco-friendly measures can significantly reduce the operating expenses of processing industry businesses. Using clean steam rather than products of combustion, steam tube dryers are one of the most ecological drying technologies.
Optimal Waste Processing With Low Temperature Drying
Many industrial processes now utilize waste heat boilers which are designed to use process waste streams, or biomass, as fuel. What was once a waste stream can now be a low cost environmentally-friendly energy source in a steam tube dryer, which is often used to replace less efficient, higher emission drying processes.
Some steam tube dryer designs use low temperatures which release fewer volatiles from organic compounds than other types of higher temperature, direct heat drying technologies. This eliminates the need for costly thermal oxidizers often required for other drying technologies.
Lower temperature operation also means lower thermal stresses on the equipment and longer intervals between major maintenance requirements. One of the premier rotary dryer manufacturers of long-lasting steam tube dryers is Louisville Dryer Company of Louisville, Kentucky – who reports that some of their steam tube dryers in service today were commissioned over 75 years ago.
Pictured - a new steam tube dryer being installed
Drying Without Heated Air
Louisville Dryer’s steam tube dryers do not use heated air as energy to drive the drying process. Only a very small volume of air is used to carry out the water vapor generated in the drying process of their units. With such a small exhaust volume discharged from their dryers, the size and horsepower requirements of the air handling equipment are normally 80% less than direct-heat dryers. And, in some processes, the small amount of exhaust gas is sent directly to the boiler as combustion air, completely eliminating air emissions.
Turn Waste Into Profit
The larger volumes of dryer discharge gas from Louisville Dryer steam tube dryers are used in many industries to convert process waste streams into valuable secondary products.
Some examples include:
The residual spent grains from the fermentation process in both beverage alcohol and ethanol production are dried in steam tube dryers and sold as high nutrient animal feed.
In the manufacture of soda ash, steam tube dryers are used to convert sodium bicarbonate into sodium carbonate – where CO₂ is generated, captured in the dryer, and returned to the process to make more feedstock. Direct heat drying technologies would contaminate the valuable CO₂ byproduct.
Waste paper sludge which, for decades, had been sent to landfill is now being dried in Louisville Dryer's steam tube dryers and returned to the boiler as fuel.
