Energy Efficiency Measures

PROCESS HEATING

Process heating is the use of energy to heat materials in manufacturing. It plays an important role in a wide range of products including computer chips, ceramics, plastics, and castings and is applied to materials ranging from paper to steel to cement. A process heating system is typically made up of these five components:

Heat Generation	A furnace or combustion chamber which converts the energy contained in the fuel into heat energy.
Heat Transfer	A mechanism which directs the heat energy from the generation component to the load or process. In some industries there is no heat transfer device, the heat is directly applied to the process.
Heat Containment	A physical barrier which separates the combustion and heat transfer from the rest of the industrial facility
Heat Recovery	A heat exchanger placed in the exhaust stream which extracts heat from the flue gases and transfers that energy to another part of the process.
Sensors/Controls	Pressure, temperature, stack gas chemistry (e.g., CO, CO2, O2) and flow devices used to calibrate, maintain, and ensure the process heating system is operating correctly.

Process heating consumes 5.2 quads (quadrillion Btu’s) of energy annually or 17% of all industrial energy consumption in the U.S. Most of this energy comes directly or indirectly (electricity) from the combustion of fossil fuels. As the costs, both direct and indirect, of burning fossil fuels increase, the benefits from maintaining and maximizing the efficiency of a process heating system will rise. Some suggestions for energy saving and efficiency improvements for each of the five areas are listed below.

Heat Generation

Check and reset air fuel ratios to maintain efficient combustion. Maintaining precise levels of combustion air for a particular process minimizes the formation of excess carbon monoxide, eliminates unburned hydrocarbons, and provides the maximum combustion efficiency. (Too little air results in more, not less CO)

Minimize air leakage (secondary air) into the furnace to avoid cooling and enhance control of combustion air.

Heat Transfer

All heat exchangers are less than 100 percent efficient. Accordingly, if possible, replace an indirect heating system with a direct-fired heating system. If it is not possible to remove the heat transfer mechanism, schedule cleaning and maintenance of the heat transfer surfaces on a regular basis to reduce thermal losses.

Heat Containment

Reduce heat losses by enhancing insulation and perform regular insulation inspections and maintenance.

Heat Recovery

Use flue gas heat recovery to capture waste heat that can be used to preheat the load and/or combustion air. The waste heat can also be used in lower temperature process heating applications.

Sensors/Controls

Update process sensors and controls to maintain optimal process operation through regularly scheduled calibration and maintenance.

Optimizing Designs

When designing new or retrofit process heating systems, take advantage of recent advancements in computers and computer software. These are quite useful in optimizing their process designs through simulation and modeling. Advancements in materials can be included in the process design and used to reduce non-productive heating.

Resources

The U.S. Department of Energy’s Energy Efficiency and Renewable Energy Industrial Technologies Program works to improve the energy intensity of the U.S. industrial sector through research and development, validation, and dissemination of energy efficiency technologies and practices. You can access its extensive process heating best management practices, case studies, tip sheets, technical tools, and other information at the link below.

EERE BestPractices Process Heating

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2260 Baseline Road, Suite 212, Boulder, CO 80302
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