03-11-2016, 02:31 PM
1464042765-RE130Bio.ppt (Size: 2.54 MB / Downloads: 4)
13.3 Energy Extraction and Preparation
Dry biomass may have some residual moisture but only requires physical preparation like chipping to fire it
Some research is being done to see if long trees can be directly fired on a metal conveyor belt
Wet biomass can absorb more heat energy from a furnace than it can supply; the biomass must be externally dried to burn
Small biomass pellets are made from wood scraps and sawdust
There are pellet-burning stoves with a screw conveyor feed
13.3.1 Dry Biomass
13.3.1 Biofarms: Trees, Shrubs, and Grasses
Energy tree farms are grown to produce a sustainable crop suitable for chipping and combustion
Switchgrass, sugar beets, and sugar cane residual waste are likely possibilities
Counterculture groups are pushing “biohemp” for various reasons and agendas – growing hemp is illegal in the US -- Controlled Substances Act of 1971
These groups claim trace levels of THC (tetrahydrocannibinol), active ingredient of marijuana, shouldn’t make it a controlled substance
Mostly in the tips of leaves
The Drug Enforcement Agency has free food and housing for you available should you grow it anyway!
13.3.1 Biofarms: Bagasse (processed cane)
The stalks of the sugar cane are squeezed to get the juice out to make sugar
The wet fibrous residue is called bagasse
A bioenergy version could be developed to make a cane maximized for energy, yet it would still yield sugar juices
The leaves could be burned as well; now discarded or burned off in the fields
13.3.1 Examples of Existing Systems
Forest waste or mill waste byproducts
Agricultural waste
A boiler receives the combustion heat and produces steam
The boiler supplies steam to a condensing steam turbine-generator unit generating about 25 to 60 MW
Coal plants can cofire biomass or convert completely to burn only biomass
13.3.1.1 Example: Forest Waste
13.3.1.2 Municipal Solid Wastes (MSW)
Municipal waste streams may have anything in it that people want to throw away -- it’s a mix
Air blast and magnetic separation can select different streams to go in various piles
Permanent magnets first extract the steel and iron
Alternating current electromagnets use the eddy current effect to remove nonferrous metals (Al, Cu)
Light paper and plastic will stratify in an air column to remove them from heavier substances (metal and bottles)
Hand sorting can pick out some of what’s left
Without this process, pollutants aren’t removed