As the price of biomass fuels on a R/kJ basis is becoming more competitive with traditional fuels such as coal, oil and gas, the need for biomass-fired boilers is steadily increasing.
To meet this need and the growing demand worldwide for a cleaner and more sustainable environment, John Thompson, the Cape Town based designer and manufacturer of industrial boilers with 80 years of service to South Africa’s industries has, in the past few years, carried out a series of tests firing a variety of biomass fuels on sites, and on the boiler installed in their test and development centre. These fuels include wood-pellets, wood-chips, wood-pucks, grape pomace, nut shells, sunflower seed husks, corncobs, dried-hops and torrefied biomass.
The test boiler installation is a fully operational boiler house complete with one of their Europac coal-fired boilers with chaingrate stoker, fuel and ash handling plant, deaerator, water treatment and chemical dosing, flue-gas clean-up equipment and an integrated boiler plant control system.When firing biomass fuels, steam outputs of between 50 and 85% of the coal-fired rating were achieved under efficient combustion conditions. As many boiler installations have surplus capacity this means that some boilers could be converted from coal to biomass-firing without the need to purchase additional boilers.
Conversions and retrofits
The high outputs achieved during the tests were largely due to John Thompson's modified chaingrate stoker and their Micropac boiler management system which was easily fine-tuned for the different fuels. Both of these can be retrofitted to existing coal-fired boilers when a change from coal to biomass fuel is required. Upgrades and conversions to existing plant can be engineered to achieve optimal boiler efficiency and emissions in compliance with the latest Air Quality Act.
This is produced from the treatment of waste-water in certain industries and can offset 10 to 15% of fuel requirements for the production of steam. A number of John Thompson biogas boilers have been supplied into the local market which has reduced the owners' carbon emissions and reliance on fossil fuel.
For customers who are interested in outsourcing their non-core business, John Thompson's Energy Management Dept offers a range of negotiable contracts from operation of existing plant to a BOOT (build, own, operate, transfer) contract, inclusive of all operating and maintenance costs, under which steam, for example, is purchased on an agreed combination of a fixed monthly rate and Rand per ton of steam basis.
In addition to boiler design and manufacturing facilities, John Thompson also specialise in turnkey installations for all of their boilers. This includes responsibility for all civil, structural and electrical works, pipe-work systems, fuel and ash handling plant, installation and commissioning.