This new breed of power station can easily blend into a rural location.
Bioflame Ltd enters into a Joint Venture agreement with a local waste management company who shred the wood and supply it to the biomass plant.
The low-grade waste wood contains MDF, chipboard, plywood, painted wood, laminated wood etc as well as clean timber such as old pallets and off-cuts from timber manufacture.
The fuel passes through a grader to sift out pieces larger than 100mms in length. The fuel is then fed up a conveyer belt into a distribution hopper and into the combustion unit where it is introduced onto the top of an actuated stepped grate within the primary combustion chamber where the thermal treatment begins. The entire combustion unit is encased in 150mm ceramic insulation to retain the heat and minimise energy loss.
Bioflame has developed its own patented partial gasification technology - an advanced thermal treatment process that converts the fuel into a gas by using the heat of partial combustion to liberate hydrocarbons. The gas is then immediately burnt in a secondary zone with complete oxidation of the gas then taking place in a tertiary zone. This substoichiometric reaction in a finely controlled environment enables much tighter oxygen controls than can be achieved in conventional mass burn energy from waste plants, resulting in very low emissions and achieving classification as an advanced combustion technology and therefore being eligible for 1.5 ROCs under the new Renewables Obligation Order April 2009. The Waste Incineration Directive (WID) stipulates that waste should be processed at a minimum temperature of 850 ºc and for that temperature to be held for a minimum of 2 seconds. The patented Bioflame ATTU has a combustion temperature in excess of 1100ºc and uses the oxidisation zone to allow for 3.9 seconds of residence time for the combustion process.
The heat energy generated from the combustion unit is fed into a fire tube boiler operating at 17 tonnes per hour at a superheated steam temperature of 400°C. This steam is forced through a specially designed dual-stage steam turbine that turns an alternator and makes electrical power.
Finally, a Continuous Emission Monitoring System (CEMS) takes 100,000 readings every 24hrs to measure emission from the chimney stack. The following gases; Carbon Monoxide (CO), Oxygen (O2), Total Organic Compounds (TOCs), Nitrogen Oxides (NOx), Hydrogen Floride (HF) and Hydrogen Chlorine (HCL) and Sulphur Oxides (SOx) are recorded to prove that WID limits on pollutants are being observed.
The Environmental Agency monitors the overall environmental performance of the plant set against strict WID limits stated in the Environmental Permit granted to the plant.
If the CEMS detects levels outside the permitted amounts, the automated control system can shutdown the entire plant under controlled conditions so that there is no danger from carbon or noxious emissions entering the atmosphere.
The ash by-product amounts to 2/3% that of the woodchip that enters the combustion unit. This is used as a second grade aggregate base in construction materials.