With 40 possible routes for grain to pass along a network of elevators and conveyors to driers, cleaners and holding bins, it is little wonder that Mark Tufnell felt a little anxious as the first trailer load of harvest 2010 grain arrived at his revamped store.

“I was a bit nervous, as with any new system or equipment, because I was anxious to see whether what we’d planned would work out in practice,” he says. “But once we got into full swing and I became more familiar with the control system, it was soon clear that the new set-up would transform the process of getting dry grain into store.”

The project managed by local installation contractor Nick Twissell of Brookthorpe Engineering has brought major improvements to intake efficiency and increased wet grain holding capacity at Mr Tufnell’s Calmsden Farms near Cirencester, Gloucestershire.

“The project grew from simply replacing the impractical building that housed the intake and cleaning facilities to one that included new drying and cleaning equipment, and increased buffer storage,” explains Mr Twissell. “With a road at the front and grain storage buildings on three sides, together with the need to blend new equipment with existing elevators and conveyors, it was quite a job getting everything right.”

The wet 2008 harvest emphasised an increasingly urgent need to invest in upgraded facilities, says Mr Tufnell. “We had a huge wet grain storage problem; the forecourt was covered in wheat because we just couldn’t process it fast enough and that had a big impact on our ability to keep combining when conditions were favourable.”

The solution involved replacing a twin-span trussed roof shed standing only 3.3m (11ft) at the eaves that provided access to the floor and bin stores adjoining three sides and housed the intake pit and a cleaner.

As working farm manager Simon Thomas recalls: “The big pit is great for depositing a trailer-load of grain, but tipping even a 10t trailer in the old building was a nightmare because of the lack of headroom. Also, overhead power lines outside the front of the building made out-loading with a telescopic handler a bit awkward to say the least.”

Grain intake and out-loading has been transformed by moling the power lines beneath the concrete forecourt and erecting a new Webcox steel-framed portal building that provides enough headroom to tip a grain lorry if the need arises. Trucks collecting grain can be filled under cover from the 500t of bin storage.

With progressively heavier tractors, trailers, handlers and other equipment having taken their toll on the flooring over previous years, the floor of the new building was specified for a long service life. It comprises a 200mm (8in) thick reinforced concrete slab laid and power-floated through the night to get it done in one go.

“It was tricky getting the levels right to keep a flush finish to the intake pit and match the bulk store floor as near as possible while preventing rain water washing in from the road,” notes Mr Twissell. “Laying the floor in one go eliminated joints and it’s been finished with a smooth surface so that as much as 100t of wet grain can easily be pushed or swept into the pit, which itself can hold around 25t.”

The network of elevators and conveyors penned in detail by design consultant Robin Charlwood begins with a new 60t/hr Perry of Oakley elevator that lifts grain to a set of feed and return conveyors of the same capacity. These send grain to a 25t capacity BM Silofabrik square holding bin – with Brookthorpe’s own load-bearing cover for conveyor servicing access – and via an aspirator that removes light rubbish from the crop to the tower drying system installed outside.

There are two Kentra 2225 continuous mixed-flow driers, each rated at up to 25t/hr, but typically running at 15-20t/hr in this installation to avoid over-loading the store handling system. They stand on the same concrete base as the ageing Alvan Blanch Cascade drier they replaced but on new, precisely laid pads that ensure they stand perpendicular.

“We decided on two driers instead of one bigger unit to give us a bit more flexibility,” explains Mr Tufnell. “It’s more practical for drying relatively small batches of 50t of beans, for example, because a lesser volume of crop is needed to fill one of the driers and stabilise the drying process.

“It also means the combine can move from one crop or variety to another without being delayed because we can start drying that material before the previous intake has been finished,” he adds. “Otherwise, we’d be looking at a two-hour or more change-over.”

A Bentall Rowlands circular hopper-bottom silo (supplied with the BM holding bin by BDC Systems) located next to the driers provides a further 110t capacity storage option. Roof air inlets and a suction ventilation system equip it for bulk storage of dry grain.

Where there is scope to improve the quality of consignments, dried grain can be conveyed to a Cimbria Delta aspirated twin-screen cleaner. And whether the crop is destined for the 630t of capacity provided by 18 indoor bins or 2200t of ventilated on-floor storage, it is all logged by a President Diplomat batch weighing system for an accurate record of the tonnage in store.

An existing Carier elevator and level conveyor, plus two angle conveyors uprated from 30t to 40t/hr capacity by fitting deeper flights, were retained along with other conveyors feeding the bin and floor stores. All are operated through a new control system supplied by Kentra and integrated with the drier controls.

Despite the potentially baffling array of manual on-off switches, selection and start-up of elevators and conveyors has been kept as simple as possible by providing a touch-screen menu of the 40 potential routes on the drier control terminals.

“Each menu shows the correct start-up sequence and with proximity switches now fitted to all elevators and conveyors, the system shuts down in the event of a blockage,” notes Barry Higginbottom of Kentra. “A light on the system diagram shows where the problem occurred and the store manager gets a text message alert; I get the same message so that I can interrogate the control system remotely if necessary.”

Mr Tufnell particularly appreciates the timer-based auto shut-down feature: “It saves me having to turn out at 1am to switch the system off when we’re drying late into the night,” he explains.

Despite some complex wiring and a pretty tight installation schedule to get everything in place before the onset of this year’s harvest, the entire system worked effectively first time out, he reports. The only fly in the ointment has been the reluctance of grain to feed evenly across the cleaner’s screens, something Mr Twissell is confident can be resolved.

“The restriction in throughput that caused wasn’t a major issue this year because of the lighter than usual wheat yields we suffered on the Cotswolds,” says Mr Tufnell. “But next year, all being well, we’ll need to take full advantage of the capacity and capabilities of the new system, which in all other respects has met our objectives in full.”

Storage stats

• 200mm (8in) thick reinforced concrete slab floor

• 25t capacity pit

• Two Kentra 2225 continuous mixed-flow driers, each rated at up to 25t/hr.

• 630t of storage capacity in 18 indoor bins

• 2200t of ventilated on-floor storage