Flue Gas Economisers

Typical boiler high fire exit flue gas temperatures are approximately 250 degrees celsius. This heat can be utilised to pre-heat the feedwater entering the boiler. The hotter the water entering the boiler, the less fuel energy is required to bring the water in the boiler up to operating temperature.

As we all know, after boils at 100 degrees celsius  so it will be necessary to pressurise the feed water so the temperature can rise to above 100 degrees celsius. To achieve this pressure, it is necessary to convert the feedwater pump to run continuously and install a modulating feedwater control or alternatively a three port valve. Essentially an economiser transfers the waste heat from the boiler flue gases into the incoming feedwater from the hotwell. Water not going into the boiler is transferred back to the hotwell, so subject to the amount of hot water returning back it may be possible to shut off the hotwell steam heating, thus making additional savings.

Minimum savings of 5% can rise further, subject to individual applications to 7-8%. 

Ask us about how flue gas economisers can benefit your business.