Polymer or Stainless Economiser - ECO

HeatMatrix polymer economiser

Recover additional heat

Prevent corrosion and fouling problems

Reduce your costs and CO2 emissions

The Economiser recovers waste heat from flue gas or exhaust air

Common economiser problems

Corrosion and mechanical failures with economiser limit waste heat recovery from flue gas or exhaust air

Heat Exchanger corrosion and rust

Flue gases contain acidic elements when using sulphur containing fuels like refinery gas, biogas, coal, oil and biomass. Exhaust air may contain acidic components from the product that is dried or baked.If you want to recover more heat and cool through the acid dew point, acids will condense on the cold tube surface as a result of the cold liquid flowing through the tubes. This leads to corrosion in conventional metal economisers.

Mechanical failure

The tubes in a conventional economiser are welded on two sides of the exchanger leading to mechanical stresses at high temperatures. These stresses cause damage to the tube welds with leakage as a consequence.

Benefits of the polymer or stainless steel ECO

  • Resistant for corrosive flue gas and exhaust air
    Resistant for corrosive flue gas and exhaust air

    The economiser can be made from bare stainless tubes or tubes lined with polymer. Based on your application we select the most suitable construction material. The polymer economiser can cope with highly corrosive environments.

  • Free from mechanical stresses
    Free from mechanical stresses

    The unique design of the economiser prevents mechanical stresses resulting from thermal expansion. This makes this economiser a robust and reliable solution.

  • Prevent economiser blocking
    Prevent economiser blocking

    The low propensity of the applied polymer to bind in combination with the possibility of in-line cleaning make the polymer economiser suitable for fouling services.

Polymer & Concentric Tube (PCT) Technology

Concentric Tubes

The economiser consists of concentric tubes. Cold water is fed via the inner tube. Heat is transferred via the outer tube. The concentric tubes guarantee a proper flow path for the water to maximise heat exchange efficiency. The tubes are fixed in one tube sheet only. The other side of the tubes is free floating. In this way the tubes are not exposed to mechanical stresses.

Polymer Technology

For highly corrosive applications all parts of the interior of the heat exchanger are made from polymer. With this configuration the economiser prevents heat exchanger corrosion problems

Economiser cleaning and maintenance

Economiser cleaning with water

A cleaning system can be integrated in the economiser to maintain the optimal performance. Spray bars will be integrated in the heat exchanger casing.

Economiser maintenance

The polymer or stainless steel economiser has minimal maintenance requirements.

Technical Polymer or Stainless Economiser details

Economiser operating range

F: 3.000 – 500.000+ kg/hr
Tdesign: 250 °C ( polymer economiser)
Pdesign water: 30 barg
Pdesign flue gas: 150 mbar
ΔP: 1-10 mbar
For operating temperatures above 250°C a stainless steel economiser is applied.

Economiser thermal expansion

The economiser is designed in such a way that the tubes can thermally expand without stresses acting on the tubes. The economiser can be heated-up and cooled down instantaneously, there is no time dependent heating profile required.

Economiser dimensions

The design of the HeatMatrix economiser is based on the requirements and process data of a specific situation. The dimensions are derived from the hot and cold flows, temperatures and composition of the flows.


The construction materials are selected based on the flue gas composition.

Stainless steel For low to modest corrosive environments
Polymer For surfaces in contact with very corrosive flue gas

Your path to lower CO2 emissions, energy consumption and costs


Technical Assessment

Our process engineers assess the technical feasibility of additional heat recovery on your process. The potential reduction in CO2 emissions, energy consumption and costs is determined.


Heat exchanger design and Business Case

A proposal is made with all technical details and economic assessment with payback time. You have everything for budget approval.


Realize Project delivery

HeatMatrix designs, delivers and -upon request- installs a complete heat recovery system in your factory. For bigger projects we work with your preferred Engineering company from start to implementation.


An economiser is used to recover waste heat from flue gas or exhaust air to preheat boiler feed water or process water. Economisers are typically applied on steam boilers but can also be used on other thermal processes like oven, incinerators or dryers.

The purpose of an economiser is to recover waste heat from a flue gas stream and use that heat to preheat boiler feed water or a process water stream. The working principle is that flue gas heat is transferred through the heat exchanger tubes of the economiser to the liquid (water or thermal oil) that is being preheated. Flue gas flows around the tubes and liquid flows inside the tubes. Different designs of economisers are available to deal with corrosion resistance and thermal stresses.

The design temperature of the polymer lined ECO is 250ºC. For flue gas or exhaust air of higher temperatures, a stainless steel or a combination of stainless and polymer ECO is applied.

Downward flow of flue gas or exhaust air is preferred. Condensate and wash liquid will flow in the same direction as the flue gas and will drain easily.
The ECO can be used to heat up water, water/glycol mixtures or thermal oil. For heating up other process liquids please contact us.

Heat recovery from flue gases can be done using air preheaters or economisers depending on the application of the waste heat. Economisers use the flue gas waste heat to preheat boiler feed water or process water. With an air preheater the recovered heat is used to preheat the (combustion) air.