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Condensing Heat Recovery

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Basic Concepts

  • Water in products of combustion is vaporized due to heat of combustion

  • Water vapors absorb about 10% of fuel input

  • Energy lost to atmosphere with exhaust gases through stack

  • Heat of vaporization can be recovered if flue gases are cooled below water dew point 

  • When water vapor condenses, it releases heat of vaporization 

  • Condensing economizer recovers both heat of condensation (latent heat) and sensible heat

Typical Applications

  • Industries with steam boilers, requiring large amounts of hot water such as make-up, washing, process, DHW 

  • Best Candidates Include:

    • Textile, commercial laundries

    • Food and beverage industries

    • Breweries

    • Non-integrated paper mills

    • Chemicals

    • District heating

    • Large hospitals

    • Green houses

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Types of Economizers

  • The industry comprises two types of technology; Direct Contact and Indirect Contact Economizers. EKO Green Energy will work with your engineers to determine the appropriate technology for your facility’s needs based on the following key considerations:

  • Space for installation, stacks, icing due to plume impingement, indoor outdoor installation etc.

  • Cost savings, installed cost, payback

  • Direct versus Indirect?

  • »» Site specific, customer preference, cost, temperature requirements, application, heat sinks, etc.

  • Establish how much heat is available

  • »» Existing FW economizer, Flue gas temperature, excess O2, steam production, gas consumption, hours of operation

  • Are there sufficient heat sinks available?

  • »» Boiler make-up water, domestic hot water, process water

  • Entering temperature of heat sink must be below dew point to cause condensation

  • Evaluate impact on existing system including blow down, flash steam, DA, water treatment etc.

  • Fuel used

A Responsible Investment In Sustainability

  • Reduce Fuel consumption by up to 30%

  • Reduce Green House Gas Emissions

  • Reduce Maintenance, Service, and Insurance Costs​


  • Domestic water heating

  • Hydronic (space) heating

  • Fresh air heating

  • Boiler make-up water pre-heating

Technical Advantages

  • Increase of up to 30% in fuel efficiency

  • Reduction of greenhouse gas emissions

  • Rapid return on investment (18-36 months)

  • Maximum efficiencies: close between 95% and 99%
    (based on HHV)

  • Minimum maintenance

  • No supervision required
    (unit is not classes as pressure vessel)

  • Rapid unit start-up (instantaneous hot water production)

  • Outdoor installations possible (reduction of insurance costs)

  • Entirely fabricated of high grade stainless steel

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