Densification of biomass for energy efficient transport
The use of densified biomass which is found in abundance in India could be economically desirable for the transport sector at a time when fossil fuel prices are rising rapidly
India has more than 200 million tons of biomass which could be used to replace fossil fuel in steam boilers and other thermal applications. Biomass is generated in different parts of the country as there are varied agro climatic conditions. So far, biomass that is used is the by-product of agro processing industries like rice husk, groundnut shell and bagasse. Till recently these agro residues were used mainly in industries located in the near vicinity where the biomass was generated.
With the rapid rise in the price of fossil fuel, biomass fuel started becoming popular in industries located even at far off areas. It is quite common to see a truck loaded with rice husk, groundnut shell and bagasse moving more than 200 kilometers distance. However, low density fuels cannot be loaded to full capacity in the trucks. Transportation cost has also increased significantly with the hike in price of liquid fuel. Therefore, the cost of loose biomass transportation becomes unaffordable beyond 300 km. In addition recent highway rules do not allow bulging trucks to travel on highways.
Low density biomass fuels having bulk density of 90-120 kg/m3 are uneconomical to transport due to following reasons:
- Loading of truck is time consuming
- Loading in truck is well below the desired carrying capacity of truck
- Unloading of truck at destination is mostly accompanied with the generation of dust
In contrast to above, densified biomass fuel like briquette/pellet has following advantages:
- Bulk density is high, about 650-700 kg/m3 and can be loaded in trucks easily
- Full capacity of truck is achieved
- Unloading is not a problem as there is no dust nuisance
Other advantages of densified biomass are:
- Fuel is ready to be used as per requirement - 6mm pellet for underbed fired fludised bed boilers
- 8-10mm pellets for over bed fired fluidised bed boilers
- 22-25mm pellets for moving grate boilers
- 65-90mm briquettes for fixed grate boilers
- No contamination of biomass fuel with sand and allied materials during loading and transit.
- Fuel can be transported pneumatically up to 25mm size pellets.
- Storage of fuel at consumer end is easier due to high bulk density.
Major consumers likely to benefit from densified biomass fuel are:
- Cement industry could use biomass fuel for cost saving in their klins.
- Biomass fired boilers producing power could use pellitised biomass in boilers during off-season.
- Sugar mill boilers could extend their operating hours.
- Major boilers consuming liquid fuel could be retrofitted to fire biomass fuel to maker it more cost effective.
- Gasifier could use pelletised biomass to generate power through internal combustion engine route.
Courtesy: A.K. Khater, Director
Amrit N.C.E.S.Ltd.
Email: akhater@bol.net.in
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