The Daldowie Fuel Plant, commissioned in 2002 and operated by SMW, a subsidiary of ScottishPower, is one of the largest sludge drying centres in Europe. It processes sludge from hundreds of wastewater treatment plants in the west of Scotland into processed sludge pellets (PSP) which are suitable for use as a dry fuel in a range of applications from power stations to cement columns.
The dry, low odour pellets produced at Daldowie are a type of biomass - biological material that is deemed to be a sustainable form of fuel. Every year SMW turns more than two million cubic metres of liquid sludge into more than 45,000 tonnes of PSP, which is burned to produce electricity or heat. The nature of the input material collection process means that it contains a percentage of grit which makes both the sludge and the dry pellets particularly abrasive.
The abrasive nature of the process material and the high volumes being transported around the plant mean that wear erosion is a challenge faced on many areas of the plant. Some areas of the process such as the pipes used to pneumatically transport the dry product are particularly vulnerable and were fitted with Kingfisher ceramic lined pipes and bends as original equipment when the plant was first installed ten years ago.
According to process and projects manager at SMW Daldowie, Iain Russell, the Kingfisher wear protected six inch diameter pipework on-site is showing few if any signs of wear, hence the reason for asking Kingfisher to look at some other problem areas of the plant.
Russell said, “A regular inspection is made of the process equipment - with external visual inspections taking place during every daily shift and a more detailed internal inspection made during a two week shutdown period, which is scheduled every six months for each section of the process plant.
“Having taken the opportunity to inspect a pipe bend transporting dry pellets during routine maintenance, we noted that the ceramic lining was barely showing signs of wear, even though it had been in use for ten years.
“Although having used other ceramic bead coatings at site before, Kingfisher have lined the inner shell of a ploughshare mixer which is a metal drum (approximately one metre in diameter) and has a central shaft with mixing blades (termed ploughs).
“The work was completed during 2011 and has just been inspected again in detail - we are pleased to report that the surfaces look like new. The estimated minimum lifespan of five to six years now sounds like a conservative estimate.
“The work was done during a routine shutdown period and so there was no interruption to our operations schedule. The high standard of supporting risk assessment statements and method statements provided by the Kingfisher team also gave us tremendous confidence with them as a supplier and meant we were more than comfortable with them working on our site. The team was obviously well trained and very experienced which added to the professionalism of the job as a whole.”
John Connolly, Kingfisher Industrial MD, commented, “Dry pellet production is coming under increasing pressure from less energy intensive processes such as gas from anaerobic digestion - although the plants tend to be smaller and the yields lower as a result. It is essential that the Daldowie PSP plant operates at its maximum efficiency and maintains uptime, hence the use of carefully selected and matched wear protection systems, installed by a professional company are essential to the long term viability of the plat. It is in these continuous applications where good wear protection sees its maximum ROI.”