Cooling & DH

In biomass plants with high efficiency are there two types of gas coolers:

1. a high temperature cooler which cool the flue gas from app 950 C to app 150c
2. a low temperature condensating cooler which cool the gas to 30-40C

Approximately 2/3 of the energy is recovered in the high temperature cooler and 1/3 of the energy is recovered in the low temperature cooler.

Dall Energy have developed a system, where the high temperature gas cooler cool the gas from app 950C to app 400C. Hereby is the high temperature cooler very compact.

In such system will the quench before the low temperature condensing cooler cool the flue gas from 400C to 100C instead of from 150C to 100C.

The quench is then sligthly bigger, but the high temperature cooler is much smaller, and the overall cost of the plant is reduced.

Also this way corrosion in the back end of the boiler and particle buildups are awoided.

Dall Energy biomass system with small high temperature cooler and quench that cooles from 400C to 100C.   Such system will be built  in biomass plants in Denmark and in the USA during 2012.

Air moisturizers

Air moisturizers are used to warm up and moisturize the combustion  air and to cool the condendate.
The use of air moisturizers have several advantages:

• Increased energy efficiency in the condensator
• Reduction of NOx and slagging in the Furnace

System layout with high temperature quench, recirkulation of particles to furnace and airmoisturizers