Opportunities Waste Heat Recovery Creates for Industries

Process heat is essential to many industrial operations; however, a significant amount of that heat energy is lost due to exhaust gases and steam, the heat released by industrial ovens, cooling processes, and as a byproduct of refrigeration. Instead of releasing it into the environment, this heat energy can be recovered and used to offset energy needs in many industrial processes including:

• Heating feedwater in boilers for steam applications or for use with closed loop heat transfer systems
• Combustion air preheating for process heaters, boilers, ovens, and furnaces
• Creating electricity with an Organic Rankine Cycle (ORC) unit – waste heat is transferred to hot oil or hot water that is then used to drive an ORC turbine that utilizes the heat transfer fluid to drive the turbine and generate electricity

Here, we’ll look at the principles behind waste heat recovery and some examples of how it can be used in industry.

Waste heat recovery industrial steam boiler

Opportunities for Waste Heat Recovery in Different Industries

Heat waste can be grouped into three broad categories: high temperatures over 400°C (e.g., from combustion), medium temperatures between 100°C and 400°C (e.g., exhaust from combustion), and low temperatures under 100°C.

Depending on the type of heat being captured and the target applications, there are several ways to design waste heat recovery systems. These systems may use a combination of condensers, evaporators, heat exchangers, compressors, turbines, generators, and pre-heaters to reclaim heat for energy savings.

Waste heat recovery technologies are used to offset fossil fuel consumption from existing process heating equipment which also reduces carbon emissions, or for on-site power generationThese systems are used in many industries including, but not limited to, the following:

Municipal Power Generation

Power plants use waste heat recovery technology to improve the efficiency of combustion turbines and power boilers.

Fuel Refining

Heat is recovered from applications such as:

• Thermal cracking
• Petroleum distillation
• Flue gas emissions (with proper handling of sulphuric acid byproducts)

The reclaimed heat can be used in boilers or for pre-heating in cold combustion air processes.

Cement Production

Cement facilities operate kilns at 200°C to 400°C to produce clinker, the material that is finely ground to create cement. Waste heat from kilns can be recaptured to produce additional process heat or energy. Research by the Department of Energy indicates that while this technology is readily available, it has traditionally been underutilized.

Food Industry

Many food processing and production applications generate low- to medium-temperature waste heat that can be recovered. Some examples include heat generated by:

• Refrigeration and freezing
• Rendering
• Hot cleaning and wash water and steam
• Singeing and scaling in meat and poultry processing
• Dairy and egg pasteurization
• Cooking and canning fruits and vegetables
• Baking and frying

Iron and Steel Industry

Iron and steel production requires enormous amounts of energy, resulting in equally enormous amounts of waste heat. Opportunities for recovery include:

• Heat from cooling areas and slag
• Combustion exhaust from blast furnaces
• Waste gas from electric arc furnaces in steel recycling
• Heat capture from dry and wet coke quenching

Learn More About Waste Heat Recovery

As technology evolves, the advantages of waste heat recovery continue to increase. Selecting a system tailored to your application translates to greater energy efficiency and facility-wide savings.