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Heat recovery

Heat Recovery

Reducing energy costs and Government Mandates and Incentives provide financial motivation to capture waste heat destined to be discharged to the atmosphere. Most High Volume / High Temperature heat recovery opportunities have been captured in the form of Recuperators or Regenerators we can assist with the low and medium temperature opportunities. There are a variety of sophisticated engineered systems designed and packaged to target heat recovery that are appropriate for specific processes. We look for untapped flue gas, hot exhaust gases from processes and waste hot water from once through cooling or to cooling towers as an opportunity for heat recovery. These applications are also typically less complex to install and maintain and provide a fast payback.

The nature of the process typical dictates the benefactor of the waste heat however three essential components are required for waste heat recovery:

  1. An accessible source of waste heat
  2. A use for the recovered energy
  3. A recovery technology.

Waste Gas Heat Sources

Common examples include;

  1. Combustion Exhausts:
    • Glass melting furnace
    • Cement kiln
    • Fume incinerator
    • Aluminum reverberatory furnace
    • Boiler
  2. Conductive, convective, and radiative losses from heated products:
    • Hot cokes
    • Blast furnace slag
  3. Process off-gases:
    • Steel electric arc furnace
    • Aluminum reverberatory furnace

Uses for the Recovered Energy;

Gas to Gas Heat Recovery

Gas to Gas Heat Recovery: Hot exhaust gases from boilers, dryers ovens or other processes can be used to heat incoming air or gas streams required by the process.

Gas to Liquid Heat Recovery: Economizers installed in a boilers flue gas to preheat the boiler feedwater. Comfort or Space Heating. In some cases it is easier to pipe water or glycol over a distance so if hot air in needed in an area a long distance from the heat source then, capturing the exhaust heat with water or water/glycol and piping is to an air heating coil elsewhere in the facility might be a more practical solution. This is also an effective manner to capture a large amount of heat and distribute it to multiple locations through a run-around loop.

Waste Water Heat Sources

Common examples include;

  1. Furnaces
  2. Cooling water from Air Compressor Intercoolers and Aftercoolers
  3. Internal combustion engines
  4. Once through Cooling water
  5. Cooling Tower Water
  6. Cooling Tower Blowdown

Uses for the Recovered Energy;

  1. Process Water heating
  2. Space Heating
  3. Domestic water Heating

Note: We use the term water but the water might be mixed with a heat transfer fluid for freeze protection or might be a heat transfer fluid. We can size for any liquid. In cases of poor water quality, energy recovery systems can be designed to recover heat or cold from process grey water.

Recovery Technology

There are many diverse manners of recovering energy from industrial process and they can vary significantly in complexity (both by design and operation). Delta T Heat Exchangers can supply; Gas to Gas, Gas to Liquid or liquid to liquid in both sensible and condensing applications.

Gas to Gas

Des Champs Technologies has both custom and pre-engineered industrial systems to suit most gas to gas heat recovery applications.

  • Temperature limit of up to 1800°F
  • Air flow limit of up to 100,000 CFM
  • Can incorporate easy to remove panels for cleaning access
  • Ends sealed with refractory cement meaning virtually no air leakage between air streams
  • Completely seem welded to ensure against cross contamination
  • Heavy duty, stainless steel construction for strength, durability, and corrosion resistance


  • Expansion Joints
  • Insulation with outer casing
  • Face and Bypass section
  • Integral blower motor assembly
  • Transitions and ducting

Thermo Z:

Thermo Z
  • Dimpled Plate Design
  • Available in Aluminized steel, 304L SS, 316LSS
  • Also available in 309/310S SS and nickel alloys and coated metals
  • Temperature limit of up to 1500°F
  • Can incorporate easy to remove panels for cleaning access
  • Ends sealed with refractory cement meaning virtually no air leakage between air streams
  • Completely seem welded to ensure against cross contamination
  • Heavy duty, stainless steel construction for strength, durability, and corrosion resistance

Thermo T:

Thermo T
  • Tubular Design
  • Flexible materials of construction
  • Temperature limit of up to 1800°F
  • Tubes mechanically expanded and fully welded to tubesheet
  • Couner flow or cross flow design. Can be multi-pass
  • Heavy duty, stainless steel construction for strength, durability, and corrosion resistance

Gas to Liquid

Economizers Click here for more information

Custom Coils Click here for more information

Liquid to Liquid

Shell and Tube Click here for more information

Plate Heat Exchangers Click here for more information

Design Considerations:


  1. Payback Period
  2. Energy Input Savings
  3. Utility Incentive Programs
  4. Costs of heat recovery equipment, auxiliary systems, and design services

Material Selection:

Certain applications require advanced and more costly materials. These materials are required for high­temperature streams, streams with high chemical activity, and exhaust streams cooled below condensation temperatures. Selecting the correct material is an essential consideration, not only for the up front cost but to ensure proper operation and maintenance and replacement cost considerations. Corrosion, scaling, and fouling of heat exchange materials lead to higher maintenance costs and lost productivity. Waste heat can be diluted with outside air to reduce temperatures although this reduces the quality of energy available for recovery.

Temperature Considerations:

  1. Find a viable end­ use for the energy available.
  2. Liquid and solid components can condense as hot streams cool in recovery equipment. This can leads to corrosive and fouling conditions.
  3. Thermal expansion and cycling ­ The heat flow in some industrial processes can vary dramatically and create mechanical and chemical stress in equipment. Accomodation for thermal expansion and contraction should be considered in the heat exchanger design.


Deposition of substances on the recovery equipment surface will reduce heat transfer rates and efficiency. The rate of deposition varies by application, temperatures, and chemical composition.

Other Equipment:

  1. Waste heat recovery from exhaust streams may complicate or alter the performance of exhaust duction or environmental control and abatement equipment.
  2. Performance of upstream and downstream equipment must be considered, pressure drops and thermal design consitions of existing equipment will be affected by the retrofit.
  3. Chemical composition and dew points of both fluid streams may be altered so fouling and corrosion upstream and downsteam needs to be considered.

Installation Considerations:

  1. Available Space : Some heat recovery equipments requires significant surface area (particularly gas to gas exchangers).The design may need to strike a ballance between quantity of heat reat recovered and available installation space.
  2. Accessibility :Typically access will be required to components of the heat recovery system for; instection, pleaning and replacement of comentents.
  3. Fluid Flow : Many waste heat fluid streams are discharged at near­atmospheric pressure limiting the ability to transport them to and through equipment without additional energy input. Condiseration must be given to size the equipment to meet the availalble pump or fan capacity or instal auxiliary fluid handling equipment.

For High Temperature and High Pressure Gas to Liquid Heat Recovery Systems, Click Here