Biomedical Engineering Reference
In-Depth Information
Forest
Chemicals
Energy
Power plant
Pulp mill / chemical plant
FIGURE 12.1 Biomass is used for energy production or other commercial products like paper
or chemicals.
case, biomass has to be procured. It can be procured from the following
sources:
1. Energy crop (farming) or forestry
2. Lignocellulosic wastes that are from forestry, agriculture, wood, or other
industries
3. Carbohydrates such as fat, oil, and other wastes.
The collection methods for biomass vary depending on its type and source.
Forest residues are a typical lignocellulosic biomass used in biomass conver-
sion plants. They are collected by various pieces of equipment and transported
to the conversion plant by special trucks (or rail cars in some cases). There,
the biomass is received, temporarily stored, and pretreated as needed.
Sometimes the plant owner purchases prepared biomass to avoid the cost of
on-site pretreatment. The treated biomass is placed in storage bins, located in
line with the feeder, which feeds it into the gasifier at the required rate.
Biomass typically contains only a small amount of ash, but it is often
mixed with undesirable foreign materials. These materials require an elabo-
rate system for separation. If the plant uses oxygen for gasification, it needs
an air separation unit for oxygen production. If it uses steam, a steam genera-
tor is necessary. Thus, a biomass plant could involve several auxiliary units.
The capacity of each of these units and the selection of equipment depend
on a large number of factors. These are beyond the scope of this chapter.
Forestry and agriculture are two major sources of biomass. In forestry, large
trees are cut, logged, and transported to the market. The logging process involves
delimbing, and taking out the large-diameter tree trunks as logs. The processes
involved in biomass harvesting, such as delimbing, deburking, and chipping,
produce a large amount of woody residue, all of which constitutes a major part
of the forest residue. The entire operation involves chopping the tree into chips
and then using those chips to make fuels or feedstock for pulp industries.
Search WWH ::




Custom Search