Biomass by definition is a renewable energy source, it is biological material from living, or recently living organisms like household waste, dead trees and left-over crops. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel.
Biomass boilers have the advantage of being able to use the biomass through thermal conversion, using gasification and combustion in order to extract their inherent energy for heating or the production of electricity. Different types of biomass can be used inside a biomass boiler. Although most materials will combust very well, some of them can cause fouling within the unit requiring more maintenance.
Here are a few examples of the types of fuels that can be used inside of a biomass boiler
• Chips and sawdust from sawmill operations are the preferred type of biomass for a biomass fired boiler. They are fairly clean fuels and are readily available wherever there are forestry operations nearby. These types of fuel will cause very little fouling and will require very little care and cleaning of the biomass boiler.
• Bark is another fuel that can be used. Like chips and sawdust bark will gasify and combust very well. Although this type of fuel will have a little more dirt and sand within it. The operating issues can be overcome with the use of a Wellons FEI mobile stepped grate system that can automatically extract the ash. The Wellons biomass boiler system is also equipped with sooth blowers in order to keep the tubes clean in order to be able to operate for longer periods of time between cleaning and tube brushing. System fitted with this type of soot blowing system have permitted systems to run 5 to 6 times longer without having to pause the system in order to clean the boiler tubes.
• Forestry biomass is another type of fuel that can be used in the Wellons biomass fired boiler. This type of biomass comes from residuals that are left in the forest after harvesting operations. This material will be in the form of tree tops, branches and limbs that are too small to be transformed by a sawmill into useful lumber products. In the past they have typically been left to decompose in the forest which can be just as harmful to the environment since the decaying wood will emit methane which can be 20 times more harmful to the ozone layer than CO2 emissions. This type of biomass can be processed and put to good use in order to generate heat and electricity in a Wellons biomass boiler system.
• Agricultural biomass is often considered as biomass other than woody biomass. Miscanthus, switchgrass, hemp, sorghum, sugarcane, and bamboo are just a few examples of agricultural biomass. These types of biomass can sometimes have high levels of alkali such as potassium that can cause fouling issues in biomass boilers. Each type of agricultural biomass has to be analysed in order to determine if they are good candidates for combustion and gasification. In order to control the amount of alkali present in certain types of biomass, crops will sometimes be left out in the field during the winter in order to leach out the alkalis. Although this might not be practical, sometimes it’s the only way to use the fuel without causing substantial fouling issues in the biomass boiler. Other ways of managing fouling issues caused by agricultural biomass is to blend it with clean woody biomass such as chips. This will soften the fouling effects of the alkali rich agricultural biomass. Proportions of the mix will depend on the level of alkali within the agricultural biomass.
Some biomass power plants boil water to produce steam. The steam produced turns generators producing electricity. Biomass can also be obtained by burning waste products in the field and producing methane gas by the decomposition of garbage. Then this gas is collected through pipelines.
One added benefit of using a biomass boiler is it helps to reduce global warming.