summarized Guidelines Based on both the results of the research projects and practical experience of real silo fires, the following recommendations are given: • Make an initial risk assessment of the situation. Concentrations of carbon monoxide in indoor areas in the vicinity of the silo may be dangerously high. Fur-ther, consider the risk of dust and gas explosions in the silo and associated systems. • Close all openings to the silo and turn off ventilation, so that air into the silo is minimized. A re-lease hatch or similar device for gas and pressure relief should be present while still preventing any inflow of air. • Inject nitrogen close to the bot-tom of the silo. A large-diameter silo will require several gas inlets. The nitrogen should be injected in gaseous phase, and an evaporator must be used. Assume an injec-tion rate of 5 kg/m 2 hour (cross-• • • • • sectional area) and a total gas consumption of 5-15 kg/m 3 (gross volume) of the silo. If possible, measure the concen-tration of CO and O 2 at the top of the silo during the entire extin-guishing and discharge operation. Do not begin discharging the silo until there are clear signs (low lev-els of CO and O 2 ) that the fire is under control. Be aware that the discharge capac-ity might be considerably reduced compared to that available in a normal situation, and that the op-eration might take several days to complete. The discharged pellets must be inspected for glowing or burning material and extinguished using water if necessary. The gas injection should continue during the entire discharge process. • cause air entrainment, which will increase the fire intensity and might cause dust and gas explosions and an escalation of the fire situation. Do not use water inside a silo filled with wood pellets. Water application will cause consid-erable swelling of the pellets which could both damage the silo construction and cause sig-nificant problems for the dis-charge operation. • Important to remember! • Do not open the silo during the firefighting operation. This will Henry Persson is working as a project leader at the Fire Dynamics section at SP, the Swedish Technical Research Institute, mainly with testing and research in the areas of fire protection, fire extinguishing systems and extin-guishing media. He has been working at SP since 1979 and is actively participating in the International and European standardization work as the principal Swed-ish expert. He also chairs the ISO group for firefighting foams, ISO TC21/SC6/WG4 and has been project leader for a large number of BRANDFORSK projects. He also was the project leader at SP for the EU foam research project FOAMSPEx and has been participating in several other EU projects. THE COMPLETE SOLUTION TO BIOMASS FEEDSTOCK MANAGEMENT From Concept To Completion Alternative Fuel Solutions From Vecoplan A worldwide leader in size reduction technology, Vecoplan designs, engineers, manufactures, and implements complete biomass feedstock preparation systems, including pre-shredding, separation, screening, air classification, re-shredding, storage, unloading, sampling, and fuel delivery. Working with individual customers, Vecoplan delivers technologically advanced, material specific, and application specific shredding, ferrous and non-ferrous removal, size and density separation, screening and classification technologies and extremely efficient conveyor and bulk material handling, metering, storage and unloading technologies. Contact Vecoplan today to learn more about our existing systems or to arrange a visit to one, or several, of our installations. Phone: (336) 861-6070 • Fax: (336) 861-4329 vecoplanllc.com 30 Canadian BIOMASS NOVEMBER/DECEMBER 2011
Canadian Biomass November/December 2011: Page 30
