24 November, 2017

Partnership leads to pneumatic control development for Biomass transport (Nov 2010)

30 November, 2010

 

Over its past 11 years of trading GB Railfreight (GBRf) has worked hard on differentiating itself from competitors, with the most recent development being its newly modified Biomass wagon. Manufactured with the help of partners Midland ACS, wagon owners VTG Rail UK, WH Davis, and Lloyd’s Register Rail, the wagons will supply Drax Power; owner and operator of the Drax Power Station. Currently producing 12 per cent of the UK’s electricity needs, it is claimed to be the largest, most efficient coal-fired power station in the UK.Drax will, on current forecasts, become responsible for around 15 per cent of the UK’s renewable electricity; of which Biomass will be a prominent feature. It is estimated that through this co-firing project Drax’s CO2 output will be reduced annually by 2.5 million tons.

The transportation of Biomass material for power generation does present its own issues. The solution took an existing HYA wagon and outfitted it with roof doors to counteract the effect of biomass blow-off and spoilage by rain that would be associated with an open top wagon. Biomass that becomes moist can ignite randomly within the pile, posing an additional hazard. Another factor that needed to be considered was the hazard of dust both when loading and emptying the wagons.
“Innovative pneumatic control solution
A sophisticated pneumatic control system used to automatically control the loading and discharging of the Biomass was designed and manufactured by Midland ACS on behalf of GB Railfreight. During the manufacture of the HYA wagons, Drax Power agreed a contract with GBRf to supply Biomass fuel between Port of Tyne, and the Drax Power station at Selby North Yorkshire. The agreement was to have a rake of wagons – 23 in total manufactured for Biomass use. Andrew Brade, project engineer at Drax Power, commented: “We knew what we wanted to achieve but didn’t know how it could be done. Midland-ACS designed and built an innovative pneumatic control solution that met the design criteria, enabling Biomass trains to be discharged efficiently and safely.”
Run on pressure alone
With efficiency and health & safety in mind it was decided to build an enclosed loading station and discharge station at both Port of Tyne and Drax. Both establishments would need to be automated with no personnel involved, and due to the combustible properties of the Biomass material no electrical device would be permitted.The 23 wagons would open their top doors for loading, with both the top and bottom doors opening for discharge at either site. For UK-based manufacturer Midland-ACS the concept presented some major technical issues that needed to be resolved. Due to the need to eliminate any electrical input the whole system had to run reliably on pressure alone. One of the main issues Midland-ACS was faced with was having two systems on each wagon but only one connection pipe between them. A signal of 3.5 Bar transmitted along the rake instigated the top door cycle, while a signal of 5 Bar instigated both top and bottom door cycles.
A pneumatic pressure switch on each wagon controls cylinders, actuating arms to open or close each door depending on where the wagon is within the cycle. The top doors operating pneumatic cylinders incorporate pilot valves and a scotch bolt locking system. A further safe guard in the form of a Scotch Bolt was in corporate into the top door cylinders to provide the extra security of a mechanical lock and latch. The built-in pilot valves ensure that the top doors cannot open during transit. The bottom doors are mechanically latched to ensure the safety requirements. The loading and unloading sequence is initiated via a pneumatic magnetic switch installed on each side for the top doors and three on each side to operate the bottom doors on a individual basis. This provides greater control if the wagon’s forward motion is stopped; consequently not all the bottom doors would be opened. The same switches also close the doors on completion of loaded or discharge of Biomass material.
Completed to schedule
Additionally, key valves are incorporated into the wagon logic control system to provide selection between manual or automatic operation of the doors. The complete system – comprising both pneumatic actuation and pneumatic control logic – was designed in-house by Midland-ACS, taking into account the operational and safety requirements of the project and application. Andy Markwell, on behalf of WH Davis commented: “The design brief called for a very sophisticated system. During rigorous end-user testing, the wagon proved to be a complete success and all wagons were completed to schedule.”  Although the original outlook of the project was related to Biomass transportation, it is hard to imagine that these wagons and automated pneumatic controls could also be used for the transportation of other materials, even those which are not as dense, susceptible to wind carriage, or subject to water damage such as aggregates.





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