5 Steps To Save Energy
May 17, 2010
By: Mike Grande
Article originally appeared in the January 2010 edition of Process Heating Magazine Process optimization is one of the easiest ways to save energy and money on new or existing ovens or drying equipment.
In a heat processing application, the process oven is designed, rated and commissioned for a specific production capacity. This capacity (pounds per hour or pounds per load) typically is a conservative number reflecting worst-case loading at maximum temperature -- conditions typically is never encountered in actual production.
This inflated rating makes your oven consume more energy even under normal conditions when the extra capacity is not being used.
By carefully analyzing the product being processed, and then designing and adjusting the equipment to more accurately match that process, you can reduce your energy use and save money, sometimes dramatically.
1. What Are Your Product and Process Requirements?
First, determine your anticipated product loading. For continuous process equipment such as conveyor ovens and web dryers, it is the pounds per hour of product or material being processed through the oven.
For batch ovens, it is the pounds being processed in each batch. Remember to add in the weight of the conveyor belt, baskets, carts, fixtures, etc., that carry the product. Be as accurate as you can and do not put a service factor on your estimates. That should be added later.
Next, calculate the amount (if any) of solvent or water to be evaporated in the oven or dryer. Start by measuring the wet vs. dry weight of a sample of material. The difference in weight represents the evaporated solvent or water.
An alternate method when dealing with a uniformly applied coating is to measure the coating thickness and multiply it by the surface area on which it is applied. By multiplying this by the percentage of solvent that the coating contains, the actual solvent content (per part or per hour) can be determined.
The final step is to multiply by the number of parts per batch (for batch ovens) or parts per hour (for continuous ovens).
No matter what method is used, it is critical that the solvent measurement is done accurately. The solvent load has a drastic impact on the exhaust rate, which has a direct effect on the heat input (and energy use) of the equipment. In many instances, the exhaust system consumes even more energy than heating the product itself.
Solvents are flammable and must be properly exhausted in accordance with National Fire Protection Association (NFPA) Standard 86 to prevent unsafe concentrations from accumulating in the equipment....