Author Archives: zollt

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In the autumn of 2014 Bennett & Co completed a 4000tonne refrigerated potato box store for Patrick Dean Ltd.  The brief was to build a store with four storage areas within the existing farmyard as part of their significant potato growing enterprise.  The design needed to incorporate storage for both ware and seed crops in separate areas, with a covered loading and unloading area.  (CIPC is not used therefore it is acceptable to have both seed and ware crop in the same building). The large roof area was also needed to provide additional PV panel capacity to augment the new large electricity supply to the site.

Working with Patrick Dean, a design was achieved to meet their requirements of fitting this large building into the existing farmyard.  Most of the designated area had previously been a pig unit but recently had been a storage area for potato boxes.  Old slurry channels and tanks needed to be dug out and refilled with backfill and then compacted to provide a firm foundation for the building and its concrete floor.

Due to unavoidable delays in getting the project underway, the floor was laid in a single day with laser screed machines and additives included in the concrete specification thereby allowing the cladders to move in and install the internal walls within 2-3 days.  The size of the building allowed the cladding, ventilation and doors to be fixed at one end of the building allowing the client to fill part of the store before the other end was completed.  This required carefully planned project management.

The refrigeration, ventilation and control equipment was supplied by Welvent, who have supplied the client such equipment over a number of years.  25kw packaged fridge units were installed in the seed stores and 90kw units in each of the ware stores.  The building was supplied by A C Bacon Engineering Ltd with ground work and concrete floor by local contractor K&S Allbones.

Bennett & Co designed the store, obtained the planning consent and project managed the construction.

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This project arose out of a client’s need to resite the farmyard away from the old buildings that have provided sites for new and alternative businesses and the need for improving returns from the expanding potato crop.  Therefore the brief was to ensure that the building would be sited to allow further expansion of the farmyard with additional buildings at a later date.  It also had to provide new workshops for the farm and a certain amount of machinery storage as well as two potato box storage areas which could be kept under different storage regimes if required, plus grading area.

The green field site presented a number of particular planning, drainage and groundwork problems which were successfully overcome by setting the building on an especially designed ring beam foundation.

rhf1The building, supplied by A C Bacon Engineering, was clad with insulated composite cladding over the roof and sides of the storage area including a dividing wall.  The stores were filled via eave height with insulated sectional slide-over doors.

Space at the rear of the store was at a premium because the building needed to be cut into a bank on the site boundary.  The choice of refrigeration units assisted greatly in this.  Two Welvent packaged refrigerated air mixing units were installed with the plant completely contained within the unit inside the building so removing the need for condenser units outside.
rhf3A new electrical supply was brought onto the site which meant that a plant room was constructed at the rear for the meter and distribution boards etc.

rhf2The Welvent units are controlled by their UAPC controller which provides precise control of the store environment utilising low tariff electricity which can be used with a printer or have the facility for remote sensing by PC.  The unit also has the ability to control the CO2 levels within the store.


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AM2This particular farmer has had three Harvest Installations Constant Humidity Controllers for a number of years.  These have operated on both indoor round bins and outdoor silos as well as a floor store used to dry grain prior to storing their main crop potatoes.  When the Maxi-stirrer was first developed it was recognised that this store lent itself to its use in speeding up the drying of relatively large batches of grain, but at the time the larger three double auger unit was not available.

The store has an underground main air duct with below floor lateral ducts.  This allows the stirrer tracks to be mounted off the building stanchions on both sides, so that the stirrer spans the whole building.  The client constructed the tracks and brackets himself.  The building is well ventilated with large vents down both sides.  This is important when drying with a stirrer at high temperatures as the exhaust air will be saturated.

Much lower quantities of air are required for stirrer drying than for conventional floor drying, consequently the inlet on the existing fan is baffled to reduce the volume of air produced.  The client’s Harvest Installations Constant Humidity Controllers are used all together to provide the heat required to raise the air temperature.  Two are operated at full output using “click-boxes” to act as dummy sensors with the third providing temperature control.


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all1A major potato producer in the Fens had a suite of specialist potato box stores, some with refrigeration.  However they had no specialist grain drying and storage facility.  They felt that silos provided a secure means of storage to provide good quality assurance.

Two 30ft. dia. Westeel silos were selected as the most economic solution.  Drying floors with Hutchinson Powersweep silo unloaders were included with drive for the sweep augers from the outside of the silos.  To provide rapid drying at depth both silos were fitted with Harvest Installations Maxi-stirrers.  This will allow batch drying to be done if additional storage silos are added at a later date.  A 15hp fan with 2 million BTU/hr Harvest Installations Constant Humidity Controller provides the high temperature low airflow regime required for the high rates of drying possible with stirrers.

legge1The site is situated on peat fenland where the soil is very unstable.  An especially designed transformation duct feeds the hot air into either silo.  This is because the silos needed to be some distance apart to spread the load and allow each silo to “float” independently. A large base area of hardcore was constructed on top of the clay subsoil before the especially reinforced bases were laid.

The silo is filled with a 200mm dia auger with a nominal rated capacity of 50 tph.  This is also used for outloading in combination with the Powersweeps.  This provides a low cost secure drying and storage facility.

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FF1A farming company were in serious need of uprating their old Turner drier and handling equipment to feed into their large floor store.  This was compounded when the drier caught fire and burnt out.  However fitting a drier with twice the capacity into the original drier’s space presented  a number of problems.  The selection of a 4m wide Svegma 20tph drier provided the solution in that it could be fitted into the space with the addition of extended legs to support the drier over the elevator pit.  The single exhaust fan could be taken out through the roof.

The small extension to the drier building which had held the burner for the old drier now became part control room and part dustbox for the existing Law-Denis rotary cleaner.

FF3The existing mechanical intake and elevator feeding the wet bins were retained as they were of high enough capacity.  The remaining machines were replaced by Perry of Oakley 40tph machines and comprised two belt and bucket elevators, a flow and return conveyor, a drier output conveyor and an inclined flight elevator to feed from the drier to the conveyor going out to the store.  The store conveyors were to be replaced at a later date.

The drier and handling equipment control panels are linked together and contain the starters for the eventual replacement store conveyors and possible waste conveyors for the cleaner.

The client required that the drier should remain within the building which required very careful drier selection.  Perry of Oakley are able to provide a wide range of machines which gives flexibility in designing a handling system to fit into tight spaces.

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DENNIS2This Suffolk farmer had demolished his outdated square bin store and replaced it with a large floor store.  However, he was reluctant to take up floor space with batch drying on the floor with a stirrer system which would reduce the overall capacity of the building.  Instead a silo stirrer system was chosen using the Harvest Installations Maxi-stirrer and Perry of Oakley handling equipment.

DENNIS6The 30ft. dia. Westeel silo is loaded via a 60tph mechanical intake that feeds the elevator and inclined conveyor.  The system can dry approximately 300 tonnes at a time.  Once dried the silo is emptied via a Hutchinson Powersweep silo unloader with drive for the sweep auger from the outside of the silo.  The grain is then taken up the elevator into a conveyor running down the centre of the building in the roof apex.  This in turn feeds a travelling cross conveyor that runs on rails suspended from the roof.

Harvest  Installations Maxi-stirrers provide rapid drying at depth.  The client’s own Simplex fan was used, baffled to reduce its output, with a 2 million BTU/hr Harvest Installations Constant Humidity Controller providing the high temperature low airflow regime required for the high rates of drying possible with stirrers.  These were placed in an especially designed fan house to meet the noise restrictions required close to the village.


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drierA Norfolk farming family had an Alvan Blanch drier that was nearing the end of its useful life.  The cleaner and handling equipment also needed uprating to cope with the larger tonnages and higher combine capacities.  At the heart of the new system is a new 20tph Alvan Blanch Double Flow Drier.  The drier was chosen because of its low visual and noise impact, vital in a beautiful part of the North Norfolk coast.  It fitted into the position of the old drier.  In fact the new dryer requires about the same power as the old one with twice the output.  It comes pre-assembled, pre-wired and pre-plumbed and coupled with the improved range of Perry handling equipment makes it easy to install.

Revamping a drying and cleaning plant into existing and traditional farm buildings require purpose built handling equipment that Perry provides.  A number of curved and inclined conveyor/elevator units were used, particularly the large combination machine that feeds the two new 30 tonne lorry loading bins.

drier3A Cimbria Delta sieve type cleaner/grader provides high quality samples of the large amount of malting barley grown, most of which is moved off the farm through the lorry loading bins. The cleaner provided the ideal solution enabling a high capacity machine to fit into a small space in the existing building.

Wheat is loaded into the existing barns either by overhead conveyor or the existing pneumatic conveying system that is also used to unload the stores to into the lorry loading bins.

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When the client acquired an additional farm there was a need for a centralised grain drying and storage facility.  In the rear of a general purpose building there was space for a drying plant including a floor area for wet grain storage.

dryerInitially a Perry mechanical intake pit was required, particularly as the fenland site has a high water table.  This is part of a combination conveyor/elevator unit that lifts the grain up to the drier intake conveyors.

The drier installed is a Svegma continuous mixed flow drier giving a capacity of 13tph.  As it has to fit within the building height, the unloading conveyor is set into the unloading hopper on the bottom of the drier.  This also is part of a similar combination to the intake machine providing a ninety-degree change of direction.

The output from the drier is cleaned in a Turner precleaner already owned by the client.  The output from the cleaner is lifted by a curved flight elevator to the conveyor to the storage buildings.  The curve allows the inclined section of the elevator to fit the pitch of the roof.

The storage buildings across the other side of the yard are reached by a Perry conveyor.  Another conveyor feeds the grain across the top of the doorways where it drops via removable ducting to the client’s telescopic elevator to load the store.

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storeThis organic grower produces a number of different cereal crops which necessitates the smaller amounts being stored separately.  An existing Norfolk barn with a precast concrete square bin system was uprated to dry and store all the client’s cereal crops.

The old Bentall dryer was removed with most of the existing handling equipment.  The new drying system consists of an 80tonne round open top Brice-Baker silo installed in place of the old dryer and has a drying floor and Harvest Installations Maxi-stirrer with 5hp fan and Harvest Installations Constant Humidity Controller.  This provides a batch dryer that keeps up with the smaller amounts of grain being harvested on this organic farm.  The large amounts of moist air given off in the high temperature fast drying stirrer system is extracted from above the silo, which also provides dust extraction when loading the silo.
store-2The store is loaded via a new mechanical intake pit and conveyor into a new Perry chain and flight elevator that feeds via a Perry aspirator cleaner onto a new Perry top conveyor. This is used to feed the drying, silo storage bins and lorry loading out of the far end of the building at 45tph.

store-4The storage bins have been hoppered with timber hoppers to make the emptying easier.  They are emptied via the existing belt conveyor and elevator, whose output drops down through the existing Turner cleaner (if required) into a new Perry bottom conveyor which passes under the drying silo back to the new input elevator and onto the top conveyor.  The drying silo is emptied through a sump under the drying floor into the bottom conveyor, the rack and pinion slide being controlled from outside the silo.  A sweep auger is lowered from the catwalk to remove the remaining grain.

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