Heat recovery for biogas-fired water treatment plant

For a water treatment facility, Heat Matrix developed a system to recover heat from biogas flue gases. The system is expected to deliver 191 kW of thermal output, heating 8,000 litres of water per hour from 75 to 90 °C.

Heat recovery system at a biogas-fired water treatment plant, with industrial piping and heat exchanger.

Sustainable energy solution for wastewater treatment

A wastewater treatment facility aimed to generate electricity and heat using a CHP unit fired with biogas from its anaerobic treatment process. To maximise sustainability and efficiency, the facility wanted to recover heat from the flue gas. However, biogas contains hydrogen sulfide (H₂S), which makes the flue gases corrosive when cooled—posing a serious challenge for conventional heat exchangers.

Proprietary corrosion-resistant heat exchanger

Heat Matrix designed a heat recovery system using its proprietary corrosion-resistant polymer heat exchanger. The corrosive flue gases from the four biogas engines of the CHP system are routed through a central duct into this polymer economiser. The flue gas is cooled below the acid dew point, allowing additional heat to be recovered safely.

191 kW heat recovery

Cooling the flue gas from 180 to 102 °C results in a thermal gain of 191 kW. This energy is used to heat 8,000 kg of water per hour from 75 to 90 °C—without any corrosion issues.

Specifications

Operating hours8,400 h/year
Flue gas flow8,000 kg/h
Flue gas temperature180 °C
SO₂ concentration800 mg/Nm³
Heat exchangerPolymer economiser
Energy saved191 kW
Annual energy savings5,775.84 GJ
Annual CO₂ reduction325 tons

Proces flow diagram

Schematic overview of heat recovery from biogas flue gases using the HeatMatrix Polymer ECO.

“Heat Matrix helped us explore our sustainability options. Their technical assessment made the polymer economiser a serious contender for our future energy plans.”
— Operations Manager, Water Treatment Facility

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