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contain some of the abrasive material from the sanders. are modified to produce a fuel in a different form. I’m
Those heavier and denser solids can seriously erode the sure you’re most familiar with one, charcoal. You also
fuel handling equipment, burners, grates, and the boiler use one regularly; the ethanol added to your gasoline is
tubes. Although some people don’t consider it wood made from corn.
fuel paper plants burn large quantities of bark that’s Unlike dried corn kernels much of biomass has to
stripped from the wood used to make pulp for paper. be processed to prepare it for burning in conventional
Bark is usually burned over a high set overfeed stoker fuel burning equipment. A typical example is wood
where the bark is introduced as much as sixty feet above pellets but the equipment can also take larger particles
the grate. and reduce them to dust (or nearly dust) such that the
Wood and wood and paper product manufacturers fuel can burn in suspension in a furnace like pulverized
have an opportunity to convert waste to fuel but in many coal. A fairly common reduction creates a fuel labeled
cases it’s less expensive to landfill the waste and burn gas RDF (for refuse derived fuel). RDF can be a fairly fine
or oil as a fuel. Environmental restrictions also limit its material that’s typically blended with pulverized coal
use. The increased cost of fuel and landfilling may change for firing in combination with pulverized coal. Another
that in coming years. There are also innovations in wood form of RDF is a reduction to something less than ½ inch
burning systems including fluidized bed firing but those in dimension for firing in a spreader-stoker.
technologies will only be applied and proven as decisions I don’t know of any at the moment that generate a
to burn wood and wood waste increase. liquid fuel but there’s applications in pilot plant stages
Wood firing problems and how an operator can that could do that. Producing a liquid fuel that’s easily
respond to them vary with the fuel. There is usually less transported and burned like our standard fuel oils has
ash than with coal firing but the ash can be finer and been attempted many times but no single method has
plug up equipment more. Keeping the systems clean, stood out as economically viable. Normally a conversion
and dressing the fire of stoker fired boilers are principal process performs a reaction known as pyrolysis where
activities. heat is generated by adding oxygen (in air or pure) to
One thing that wood fired boilers have is plenty burn some of the fuel with the remainder vaporized into
of air. Much of the air that’s used for combustion comes combustible gases, principally carbon monoxide.
with the wood. If you think about logs you put on your With biomass fuels the instruction manual may not
fireplace, wood stove, or campfire, you’ll recall the wood tell you all that would be good to know about burning
is full of little air spaces, especially if it’s dry. There’s so that fuel. That’s because advances in the technology
much air available that a pile of wood in a corner that are made regularly. Looking through your equipment
looks like it’s all burnt out ash can have glowing embers manufacturer’s web site on a regular basis may make
underneath. They can also be there after several hours you aware of changes and improvements in operation
or even days. Always treat any accumulation of any- that have been developed. Check it out and you may
thing in a wood fired installation as a potential source of find a user’s group that you can join online that shares
flame. Stir it up and mix it with a little air and you could problems, improvements and solutions.
have an explosive mixture, same as with coal.
I’ve been involved with four major projects to burn
wood and wood waste. They have all had their technical PUMPS
and operational problems on startup but all are operat-
ing and reducing the amount of wood and wood waste Pumps are used to move all of the liquids around
going to waste and landfills. Some processing of wood a boiler plant and there is a diversity of designs and ar-
wastes have produced specialized wood fuels (pellets) rangements for pumping that provides many options.
and included material like leaves. When engineers use the word ‘application’ it means what
the equipment is used for; applications include feedwa-
Biomass Burners ter pumping, condensate pumping, fuel oil pumping,
Wood is one of the many fuels identified as “bio- sewage pumping, etc. Over the years the applications of
mass,” a label applied to materials that are grown or pumps to boiler plants has singled out a particular pump-
produced from vegetation. Biomass is commonly re- ing method and pump construction for each service. As
stricted to mean a solid fuel and the burner may actually a result you’ll seldom find any deviations in the type of
be a device that processes that fuel to convert it to a gas pump used for a particular fluid service.
or liquid fuel that’s then burned. Other biomass fuels High pressure feedwater and condensate system