Category Archive: Waste Heat Recovery Systems

Reclaiming Every BTU: The Ultimate Guide to Industrial Waste Heat Recovery

Industrial facilities release significant amounts of recoverable waste heat every day—energy that was purchased but not productively used. Much of it is lost through hot exhaust streams, representing major opportunities for industrial operations to implement waste heat recovery systems.

At Sigma Thermal, our advanced waste heat recovery systems capture the thermal energy, transfer it to where it is needed, and reuse it as opposed to simply releasing it into the atmosphere. Recovering this otherwise lost energy allows facilities to reduce operating costs and improve efficiency while supporting environmental goals. As energy prices continue to rise, implementing waste heat recovery has become a strategic and financially sound investment.

What Is Waste Heat and Where Can It Be Found?

Industrial processes produce substantial heat, but a significant portion escapes through stacks, vents, cooling water, and blowdown. Any process that burns fuel, compresses air, oxidizes VOCs, or dries product and reaches at least 450 °F is a good candidate for waste heat recovery.

Common Waste Heat Producers

• Thermal oxidizers. Used to destroy VOCs, thermal oxidizers release high-temperature exhaust streams that are ideal for waste heat recovery.
• Combustion turbines. Combustion turbines generate hot gas, often over 900 °F, that can be repurposed.
• Fired heaters. These are commonly found in oil, gas, and chemical manufacturing. The flue gases they expel are prime heat recovery candidates.
• Kilns. Cement, lime, and mineral processing kilns release high volumes of hot exhaust.
• Dryers. Industrial drying systems often vent substantial amounts of thermal energy in their process air.
• Blast furnaces. Steel production involves extreme temperatures, with exhaust heat that can be captured and redirected.
• Engine and turbine exhaust. Engines used for power generation or compression emit consistent high-temperature heat.
• Steam system exhaust/blowdown. Boiler blowdown contains high-pressure, high-temperature flash steam that can be recovered.

Technologies for Waste Heat Recovery

Understanding how waste heat recovery works involves knowing the right system to capture it and directing it to a process that can use that heat. At Sigma Thermal, our engineers design and build the following types of waste heat technologies.

Combustion Air Pre-Heat (CAPH) Systems

CAPH systems use heater exhaust gases to pre-heat incoming combustion air. Combustion air burns better at higher temperatures, and plants can see system efficiency increase to 90%.

Waste Heat-Powered Thermal Fluid Heating Systems

Using thermal oil, water, or glycol, these closed-loop systems capture thermal energy from waste heat producers and deliver it wherever your process needs it. Our heat exchanger heat recovery design keeps the transfer reliable and efficient, even over long distances.

High Particulate Systems

Particulate-rich exhaust from biomass systems requires robust, specialized heat exchangers. Sigma Thermal specializes in biomass and gasification systems for oil, gas, and chemical plants, and can capture waste heat from high-particulate exhaust gas. Once recovered, this thermal energy can be used with any waste heat consumer.

Common Waste Heat Consumers

Recovered heat can be used almost anywhere thermal energy is needed:

• Combustion air pre-heating
• Boiler feedwater heating
• ORC generators for on-site electricity
• Building HVAC systems
• Wash water pre-heating
• General process heat (tank heating, heat exchangers, thermal fluid heaters)

Sigma Thermal: Your Partner in Energy Efficiency

Industrial waste heat recovery is one of the most effective ways to reduce annual fuel usage and advance sustainability goals. When combined with available federal and state tax incentives, industrial waste heat recovery systems can save facilities a significant amount of money and improve ROI.

If your facility is ready to make waste heat recovery part of its long-term strategy, Sigma Thermal is your partner. Our engineers are experts in heat energy management, and we offer hands-on services ranging from audits to detailed technical evaluations. We supply the right equipment to guarantee maximum energy savings.

Contact us today or request a quote to get started on your waste heat recovery project.

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.

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.

Sigma Thermal specializes in providing waste heat recovery systems and process heat solutions for customers in many industries. Our products include thermal oil and thermal fluid heating systems, electric process heaters, indirect process bath heaters, direct-fired process heaters, biomass-fired energy systems, system automation, parts, and retrofits/upgrades.

Please contact us to learn more about waste heat recovery and process heat options, or request a quote today.

Save Money with Waste Heat Recovery Systems

Why implement a waste heat recovery system into your application? With natural gas prices currently trending at historical lows there is no question that the potential payback from waste heat recovery projects has fallen considerably.  That being said, solid economic justification still exists for many simple thermal efficiency improvements.

Do you have an exhaust stack with exhaust temperature over 500Fº?  Does that process operate continuously, or at a high frequency over the course of the year?  Do you have an older heater, boiler, or furnace with burner/combustion control technology that has never been upgraded?  If so, you should consider one of the following relatively simple projects to cut your fuel consumption:

• Retrofit your burner with modern electronic fuel/air ratio control to keep your burner running on ratio at all firing rates.
• Consider using a self-contained combustion air pre-heat system that doesn’t require heating an auxiliary process.
• Install a waste heat recovery coil in your stack to heat water, air, or to make steam for other processes in your plant.

As experts in the heat recovery and combustion automation business, we can provide you with the most appropriate system for your needs.  In addition we can also offer engineering studies and energy audits to determine if you have a viable waste heat recovery project. Contact us today to find out if you should be spending less on your fuel bills.