Saxlund innovations deliver on RWE npower plant contract
Scotland's mega renewable plant biomass combined heat and power plant (CHP) at Markinch incorporates Saxlund efficiency know-how and equipment in turnkey project management and supply contract.
Evidence of Saxlund International's capability to tackle large scale projects and deliver innovative solutions is spotlighted by its prestigious contract for the RWE npower renewables biomass combined heat and power plant (CHP) at Markinch in Fife. The bulk handling and biomass experts were tasked with project managing the Biomass Fuel Handling System for the £200 million build in 2010 which, when finished in 2013, will be the largest of its kind in Scotland.
The Biomass CHP, which lies on the grounds of Tullis Russell Paper Makers, will replace their existing coal fired power plant and reinforces the company's position as one of the world's leading environmentally-focused papermakers. Using a mixture of reclaimed and virgin woods, the 49.9 megawatt plant will supply both steam and electricity to Tullis Russell. Moreover, the company also signed a 20 year energy supply contract with RWE npower renewables, with any excess electricity created being supplied to the National Grid, equating to around 25MW an hour, compared with the 17MW actually used.
To help complete this massive project, Saxlund had to choose and develop key subcontractors, as its managing director Matt Drew explains: "One of the largest challenges to overcome was the removal of oversized materials. Our solution was to use two large disc screen separators, which are capable of screening up to 780m3/hr of waste or virgin wood before conveying them to our storage silos. We then had to erect three 20m diameter, 26m high concrete storage silos, complete with explosion protection. Each Silo is fed by two overhead conveyors from the reception system.
"The process of discharging the wood from the silos is completed with the use of a Saxlund TubeFeeder ®. Each TubeFeeder sits on the bottom of the Silo and sweeps its floors discharging the wood at a rate of up to 285m3/hr. The patented TubeFeeder® consists of a screw conveyor housed inside a rotating tube. The tube is perforated with a regular slot pattern permitting 'activated' material to fall onto the screw conveyor, thereby eliminating the external static material pressure on the screw and presenting a uniform feed to the screw."
Here Saxlund has been able to aid Tullis Russell's eco drive, with this system needing just 25% of the power needed for traditional exposed screw reclaimers. The biomass materials collected by the TubeFeeders are transported by chain conveyors back above the ground where they discharge into the downstream conveying system.
Other innovations to support the substantial logistics operation at the plant include specification of Lorry Reception units. Each of the four units is capable of receiving up to 380m3/hr from either Walking Floor Trailers or Tipping Trucks. The units are supplied complete with reverse jet bag filters to minimise dust emissions and fully mobile enabling a simple robust method of providing redundancy.
Working with Canning Conveyors to deliver this project, due to the large size of the Fuel Handling System, Saxlund and Canning Conveyors negotiated separate contracts with the client for their respective scope of supply, with Saxlund taking the overall Project Manager role.
"This is a challenging project, which demands innovation and creative solutions at every stage. Ultimately its projects of this type, not just because of the scale, that allows us to demonstrate how we can add real value to the project; we believe that Tullis Russell is a prime example," concludes Matt.
Saxlund Specification:
• Four x B&W Lorry Reception units.
• Two Disc Screen Separators for the removal of oversize material.
• Three 20m Diameter, 26m Height Concrete Storage Silos.
• Three Saxlund Radial TubeFeeders® for the discharge of waste or virgin wood
• Three Saxlund Elevating Twin Strand Chain Conveyors
• Two GEFA Enmass Elevating Chain Conveyors