BG Europa supply new hot storage system to Westleigh Asphalt Plant

Owned and operated by Aggregate Industries UK Ltd (AI) the quarry was originally best positioned for the creation of the M5 with the asphalt plant installed in 1972. Originally designed as a direct load plant (with no storage system) it has supplied material over the years for the North Devon Link Road and continual work for the M5, currently being involved in the supply of material for the motorway (on nights) over a seven week period.

Currently managed by the AI Asphalt Area Manager - Matthew Bishop, it wasn’t long after his arrival that he undertook a feasibility study to justify the inclusion of a hot storage system.
Matthew, commented, “Over the years demand has changed. In 1972 there was only a base material, a road base, base course and a surface (wearing) course with maybe half a dozen different mixes in total. Today every company wants to sell its best products and diversify into different products, offering customers a variety of solutions. Therefore there is an increasing demand for a variety of materials making hot storage essential. Sometimes direct loading onto trucks is not the most efficient approach. We needed the ability to load different materials out at the same time hence why we put together a proposal for £½ million to bolt on a hot storage system onto the side of a 42 year old BG Europa asphalt plant.”

Supplied by the Ulllrich agents - BG Europa of Wickhambrook the new system was installed while the plant was operational, with the civils completed by AI, the plant was closed off on one side and traffic redirected. Installation by the BG Europa team was completed on time, on schedule and in budget. The whole project was managed and scheduled on a daily basis by Matthew and overseen by the AI Project Manager John Richards.

The Ullrich 200t S200/4 Hot Storage System
The new hot storage system is essentially a four compartment silo arranged in a cluster (two x 47t compartments and two x 53t compartments) which allows the storage of hot asphalt in preparation for vehicle discharge to a single loading point. This provides the advantage of allowing the discharge of all four bins to one truck way with the retrofit silo mounted on load cells to allow accurate weighing of material into the vehicles.

The Ullrich S200/4 hot storage system installed at Westleigh offers 200 tons capacity at 1.8 t/m³ for a hot mix with a coefficient for friction of 27°, in stationary construction for connection to the existing high profile 4000kg batch plant, output 320tph.

Numerous features including:

• In transit weighing of skip and contents
• Automatic winch brake test function
• Skip elevator with automatic or manual operation.
• Skipway with foldable skip rails and electric winch to facilitate direct truck loading.
• Automatic skip spray system.
• Electrically heated silo cones.
• Remote controlled discharge gates suitable for hot rolled asphalt.
• Discharge gates electrically oil-bath heated and regulated by thermostat.
• Weighing system for four silos with four load cells and amplifiers.
• Failsafe discharge door closure with emergency backup system.
• 3 stage discharge door control to facilitate accurate and fast loading of small loads.

Massive benefits
Specifically designed for short term (overnight) storage the silos allow production of material in preparation for vehicle loading. Vehicle waiting time is therefore reduced and also potentially the number of vehicles required for a project (vehicles not queuing at the production site). Vehicles at Westleigh can now load in around 20-30 seconds whereas loading time before used to be around 10 minutes per load. It also releases haulage to do other work because the truck is not sat waiting to load.

Matthew, commented, “Essentially the hot storage facility increases your capacity, quite simply 10 lorries sat for 30 minutes equates to 300 minutes of inactivity which allows trucks to be sent out to a local stone tip and return in the time they would have been inactive. Therefore it increases the hauliers earning ability as they are not sat here waiting, so it’s a massive change for them.”

There has also been a huge reduction in energy use since the installation of hot storage with the average total energy consumption dropping by 10%. The percentage of rework aggregate back to stock (material heated and not used in the production of asphalt, but instead returned to stock) also shows a decrease of 8%, with RAP % achieving an increase of 7.3% on binders and bases, therefore showing a massive saving when compared to 2013.

Matthew, further commented, “The saving in bitumen by adding extra RAP has actually increased our profitability and environmental contribution by a significant amount. So now, we have the energy saving, and the bitumen saving through adding more RAP. When we are processing a run of material it is easier to control our temperatures on production so we can ramp up the temperatures to add more RAP to the process. With the grouping of production, it allows more time for on-going maintenance, greasing checks etc. Prior to hot storage the plant would achieve a maximum of 1,000 tons but now it’s capable of achieving around 1,400 tons in a day shift simply because the plant is running more effectively. We are no longer doing so many individual loads or clean outs, it’s all more concentrated on production. Attention to planning the day before has been the key to the success of this system.”

Flexibility
The new storage system has brought greater flexibility as the plant can now rationalise production rather than producing purely for each vehicle as it now produces longer runs of each material to be held in the bin. This reduces the number of batch tower cleanouts where the plant has to empty its hot stone bins to produce a material with a different stone type.

Running the batching plant continuously reduces energy consumption, as before the plant had to stop if there were no trucks. They can now continue to produce and store the material in the bin ready for the trucks to arrive.

Matthew summarised, “We can rationalise production, produce longer runs of material and hold in the bin which in turn reduces the number of batch tower clean outs. We can also group production together, if I have 10mm and 20mm with different PSVs to mix and I have one load of each throughout the morning I would, in the old days have to clean out the whole plant when we swap from one to the other. This means any stone that is heated in the plant already would be sent back up to the stocking area to be put back through the system to reheat at some point and then we would have to run up new aggregate for the next. With the new system we have less cleanouts and as each has a fuel cost we are more efficient whilst satisfying customers at the same time! Hot storage completely changes how you do things, especially as CE marking now cancels out fly changing; hence hot storage is the way forward.”

“Night work on the plant has also changed dramatically. In the past if we have had a large tonnage booked we would not normally have accepted additional orders. However with hot storage we can bin up the additional order in addition to the night work commitment. The plant on night work does not require to run as long, as once the required tonnage is produced into the bins they can shut down, so reducing the environmental impact of the plant at nights on our neighbouring community.”

“Overall it’s been a huge success; the inclusion of hot storage allows greater continuity of mixing, reduced clean outs, increased volumes, increased flexibility and new collect trade (new business). We will see a return from the investment within 18 months and as the plant is being operated less there is a positive environmental effect.”

 
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