Valves
Burning issue A
b de Kroo is a maintenance engineer at the EPZ power plant in Borssele. This is not the well known nuclear power
station but the coal/biomass powered power plant built at the same location. The amount of biomass has to be increased in the future and a correct dosing of the biomass is extremely important. “In 2008 we installed rotary valves which played a crucial role in the process. As a power station is a con- tinuous operated busi- ness, we have made special agreements with our supplier TBMA with regards to mainte- nance and availability of the spare parts.” “Since 2002 we have been burning biomass in the coal fired power plant in Borssele, nowadays this is 20% meaning 12 kg/second. The inten- tion is to go up to 30% in the near future. The Biomass is made from used wood and agrarian rest products like cacao shells and palm pulp. As wood dust burns easier than coal it can be somewhat more rough. In 2008 our installation was in use for several years and we had all kinds of problems on regular bases with wood dust as fuel. We also wanted to increase the amount of biomass which was not possible with our installation. Together with TBMA we analysed the problem. In 2009 we ex- changed our six rotary valves for the TBMA blowing seals. Our experience learned that this exchange system works perfect with a lifetime of eight months. We are now burning wood dust without any problem.”
TBMA’s HGR Valve
SIX ROTARY VALVES The material arrives in bulk trucks six
days a week and is dumped in two cel- lars. From there the product is transported to a huge rotating sifter removing the oversized particles and is then trans- ported by means of an elevator to four large silos measuring 600 m3 each. Ab de Kroo says: “If required for the pro- duction we can mix the content of the silos and store it in the intermediate bun- kers measuring 250 m3 above the hammer mills. In the hammer mills the pellets are reduced to a fibrous material. Normally the power plant is fed with powder coal which is considerably fin-
er than wood dust. As wood dust burns easi- er than coal it can be somewhat more rough” Each hammer mill has an intermediate bunker and underneath two rotary valves regulate the amount of biomass going to the burner. Totally we have six feed- ing lines each with its own roots blower blowing the product in to the burner. In the burner there is a slight under pressure sucking the product into the fire, there- fore a flame flash back cannot occur. De Kroo adds: “The rotary valves are in fact the accelerator of the biomass installation. The nuclear power plant is delivering a constant output, the coal/ biomass installation is taking care of the fluctuations in power demand”.
MORE CAPACITY
About the investment in new rotary valves De Kroo says: “In 2008 our installation was in use for several years and we had all kinds of problems on regular bases with wood dust
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Our experience learned that this exchange system works perfect with a lifetime of eight months. De Kroo: “Each time we exchange two valves with two spares. The exchanged valves are sent to TBMA for revision. Some- times we feel revision is not really necessary yet, but we choose to let TBMA exchange the wear parts anyway. We do not want to take any risk in this. Reliability is priority. “We want to be 100% sure each ex- changed valve will last for a minimal of eight months without any intervention. “We are now burning wood dust with- out any problem. Following the chang- ing demand in power works smoothly. We have sufficient capacity left to grow in the future with biomass”. Since this installation, TBMA has deliv- ered several biomass systems in biomass for companies like Electrabell, RWE, Juwi and many others. The rotary valves are executed with pressure tight and flame back flash protection. ■
For more information
contact TBMA by email: info@tbma. com or visit:
www.tbma.com
Solids and Bulk Handling June 2012 37
Biomass powered power plant EPZ in Borssele goes for no risk and chooses TBMA valves
as fuel. The product is relatively light and our rotary valves were producing a lot of air leak- age and we therefore were not able to regu- late our installation in a proper way. We also wanted to increase the amount of biomass which was not possible with our installation. “In that year I met TBMA at the Solids fair in Antwerp. Together with TBMA we analysed the problem and looked for a solution to dose Wood dust with a bulk density of 250 Kg/m3 and a capacity of 2 kg/second. During the maintenance intervals in 2008 and 2009 we exchanged our six rotary valves for the TBMA blowing seals in two steps and purchased also two spare valves. De Kroo; “The spare valves are used to exchange the valves preventative”.
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