Adopting some simple solutions for reducing heat loss can increase process heating efficiency.
Process heating is a critical step in many manufacturing operations, used to heat materials in the production of metals such as steel and aluminum, and non-metals such as glass, cement, rubber, plastics, petroleum products and ceramics. Heat is applied to raise the temperature of solids, liquids or gases in heating equipment such as process heaters, ovens, dryers, furnaces or melters. The heating process softens, melts or evaporates the materials and may promote chemical reactions or chemical rearrangements or break down the molecules of the materials being heated. Heat required in process heating equipment comes from fuels such as natural gas, fuel oil, coal and other energy sources such as electricity or steam.
Reducing or eliminating of heat losses is the most important consideration in reducing energy use for process heating equipment. In cases where it is impossible to reduce the losses, consider recovering part of the energy lost and using it within the process itself or for other useful purposes. Several heat recovery methods exist that can be used within the heating system, within the plant or converted into easily transportable energy such as electricity.
Efficiency of heating equipment is measured by the ratio of the amount of heat used by the material being heated to the amount of energy supplied to the heating equipment. For example, if heating equipment uses 10 million BTU/hr heat, and the load or material uses or receives 6 million BTU/hr heat during the heating process, thermal efficiency of the process is considered 60 percent. The heat not used by the material is lost through the system.
Heat loss depends on many factors such as the type of heat supply system used, equipment design, operations and maintenance of the equipment. The table shows some common areas of heat loss and suggests steps to take to reduce or recover the heat loss.
You can estimate heat losses in your system by using the U.S. Department of Energy’s Industrial Technologies Program’s Process Heating Assessment and Survey (PHAST) software tool. PHAST also allows the user to estimate how much these losses can be reduced by employing energy saving measures.