Polymer or Stainless Economiser - ECO

Recover additional heat

Prevent corrosion and fouling problems

Reduce your costs and CO2 emissions

The Economiser recovers heat from flue gas or exhaust air

Heat up boiler feed water or make-up water

The polymer or stainless steel ECO preheats the boiler feed water from the deaerator or make-up water. By using preheated boiler feed water the fuel consumption is reduced. In other situations the make-up water that is fed to the steam cycle, is preheated.

Heat up process water

The flue gas from processes like incinerators, fired heaters or kilns can be recovered with the polymer or stainless ECO. The recovered heat can be used to heat up process water for usage in process steps that require hot water.

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

Corrosion problems

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.


Corrosive flue gas is no longer a show-stopper for heat recovery

A significant amount of waste heat in flue gases and exhaust air remains untapped due to risk of acid dew point corrosion. Download the whitepaper to find out how to overcome this limitation.

Benefits of the polymer or stainless steel ECO

  • Corrosion resistance
    Corrosion resistance

    The ECO 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 ECO can cope with highly corrosive environments.

  • Free from mechanical stresses
    Free from mechanical stresses

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

  • Anti-fouling

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

Polymer & Concentric Tube (PCT) Technology

Concentric Tubes

The ECO 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 transfer. 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 is insensitive for corrosion.

Easy cleaning and maintenance

Cleaning with water

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


The polymer or stainless steel ECO has minimal maintenance requirements.

Technical details

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.

Thermal expansion

The  ECO 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.


The design of the HeatMatrix ECO 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

The Polymer or Stainless ECO can be applied in these industries and thermal processes

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.


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.