Oakhill Saladin Box Maltings
OAKHILL SALADIN BOX MALTINGS extracted from The Brewing Trade Review October 1962
In an address given by Mr. H. C. Hobhouse, Director of Courage, Barclay and Simonds (Western) Ltd., on the occasion of opening the new Oakhill Maltings, Somerset, on the 6th September, 1962, he said:- “Courage, Barclay & Simonds Limited have two maltings, one on the borders of Norfolk and Suffolk at Ditchingham, which, incidentally, was one of the first Saladins ever built in England, and these maltings here which are the most recently equipped in the country. I do not know when malting first started on this site, but the Oakhill Brewery, which is just down the road from here and which is now partially used as a barley store for these maltings, was founded in 1767, and I suspect that part of the malting now used for Saladin Boxes was built between 1800 and 1820.
The building in which we are standing was built in 1898 and we have had to demolish part of this building in order to erect our silo block which consists of 47 Crittall steel bins. We decided to convert the old floor maltings to box maltings for various reasons, the principal one being that malt being the main basic ingredient of beer, we were anxious to have control over the exact types of barley and malt that our brewers require. We were making malt here on the old floor system up to May, 1960, and used to produce about 8,000 quarters per year. Under this new system we hope to produce 32,000 quarters a year. We buy the majority of our barleys in Somerset, Devon, Dorset, Hampshire and Wiltshire and so we hope that the increased production here will be of considerable advantage to West Country farmers.”
During the winter months of 1959-60, major demolition commenced on two conventional floor maltings at Oakhill, Somerset, owned by Courage, Barclay & Simonds Ltd. with a view to reinstating them as up-to-date Saladin Box Germination Maltings, complete with steel silo storage bins and a pressure kiln unit. After careful planning it was thought advantageous to convert the larger malting, a 90 quarter house, into the germination section and the adjoining 60 quarter house into the storage block, complete with kiln and new office with pilot laboratory. The growing floors and loft storage of the smaller malting were demolished completely to make way for the all-steel, asbestos-clad 15,000 quarter storage block, and the two 30 quarter kilns of the same malting were reconstructed as a single kiln of the pressurised type.
The original barley kiln, at the rear of the block, was demolished inside for the construction of an office block and pilot laboratory, whilst the lower level was made available for sack delivery of malt, should the need arise.
The Crittall silo consists of 47-320 quarter storage bins six feet wide by eight feet long: the space of the 48th bin being utilised for elevators and automatic weigher. A comprehensive worm conveying system, with a conveying rate of 30 tons per hour, serves the silo block, pressurised kiln and in addition links up with the steep and bulk out-loading of either malt or barley. Between the office block and silo the original steep and screening floors were retained in order to accommodate up-to-date malt and barley screening equipment, together with dust collection and offal storage. There is also housed within this space a centralised electric control panel incorporating bin thermometer recorder equipment to serve 16 of the storage bins.
The pressurised kiln unit, which was completely reconstructed in the space of the existing kilns, is designed for barley drying as well as malt production: in the case of the former 60 tons batches are permissible and they can be dried down to 12% of moisture within an 8 to 9 hour period. 200 to 220 quarter batches of green malt are also loaded to this kiln from the germination boxes every second or third day, and in view of the variable volume of air available from the fan units, the drying cycle can be accommodated within 24 hours, or, if need be, extended to 48 hours.
The heat source is supplied by oil firing and is interlinked with a 5,000 gallon oil storage tank, sited externally to the building. The natural vent draughts of the kiln have been retained to serve as reek chimneys, and valves have been incorporated to ensure complete control of the air flows during the recalculation of hot air in the latter stages of malting: the recirculation shaft is also utilised as a reek outlet.
Before serious consideration was given to this conversion, it was necessary to find out whether there was an adequate supply of cool fresh water available in the immediate vicinity, which, to minimise on costs, would eliminate the necessity of installing a refrigeration plant. Test proved satisfactory, but it was evident a balancing tank for a reserve of water and disposal of trade effluent was necessary. A rectangular concrete 60,000-gallon storage/effluent tank was constructed in close proximity to the maltings, and in order to serve the dual role was centrally divided. Water for steeping or humidifying can be drawn either directly from the neighbouring supplies, or alternatively, from one half of the balancing tank.
It was evident that all the working floors and three kilns of the original 90 quarter house would have to be demolished completely to accommodate the steeps, humidifier/washer chambers, with associate ducts and three germination boxes, and still leave little room to spare.
Four 100 quarter steeps, which operate in pairs were installed at the rear of the building and appropriately intercoupled with the main water supply and trade-effluent section of the balancing tank. The grain and water steep outlets are likewise intercoupled so that apart from being able to pump over to any of the three germination boxes it is possible to move the steeped grain to the adjoining pair of steep tanks, or, alternatively, recirculate within a steep grain and water separators are placed centrally over the steeps, making it possible to carry out a water change at the same time as the pumping operation.
External aeration boxes are fitted to the cone of each steep and coupled in pairs to two separate aeration blower units, which operate automatically every two hours to aerate for 15 minutes, or, alternatively, controlled manually to suit the requirements of the management.
The steep room is separated from the humidifier room by a partition wall internally clad with aluminium foil for insulation: a desirable feature because, as mentioned earlier, refrigeration is not incorporated. The three concrete and brick humidifier chamber units are interlinked with the germination boxes and intake from atmosphere by galvanised metal ducts. The ducts are fitted with valves, coupled to servo-cylinder motors and in turn to the instrument panels for regulating the quantity of fresh air and recirculated air that will pass through the fan units. Each washer chamber holds some 800 gallons of water which is in continual recirculation through centrifugal pumps discharging on to motorised atomiser discs within the chambers.
Mercury capillary tubes placed below the germination floor relay the discharged humidified air temperature to the dial-type recorder controller units on the instrument panels: they in turn operate on a compressed air principle, served by a common compressor unit, to actuate the servo cylinders for additional fresh air to obtain temperature control; or on a further increase of pressure depress the diaphragms of mixer control valves to bring in a fresh supply of cold clean water to the pumps.
Incorporated into each set of ducting is a two-stage axial fan with hand-operated butterfly damper, and under normal working conditions only one fan is utilised; however, the second-stage fan can be brought in automatically to serve as an additional boost if temperature control is not achieved by normal intake of air and additional supply of water. Should the outside atmospheric temperature rise excessively a solenoid valve automatically closes the fresh air intake valves, and the boxes, therefore, are in complete recirculation. As only one stage of the axial fan is normally required, the second stage is always available as a standby unit. It is interesting to note that this method of operation has already proved beneficial during the spring and summer months because temperature control has been kept within a half to one degree at all times, utilising only one stage of the fans and with a very small consumption of water.
The three germination boxes are truly separated in every respect. Access is gained to any of the boxes by a double-door system at both ends, thus permitting free movement of management and all personnel. The ceilings above the boxes are rendered and plastered and well insulated with a combination of fibre glass and aluminium foil immediately below the original top timber floor of the maltings. Hand-operated Venetian louvres are fitted into the end walls for assisting the operators to obtain accurate temperature control and high humidity conditions. Each germination box is fitted with a brass wedge wire floor mounted on a galvanised steel underbed and supporting joists seven feet above ground-floor level, thus permitting easy cleaning-down facilities between the discharging and filling periods. The floors are 86 feet long by 14 feet wide and are closed at the ends during the germination period by sectional aluminium concaves; during the discharging and filling periods they are removed manually. Washing-down water supplies are available above and below the box floors and in addition there is a metered water supply for the sprinkling operation. The basic capacity of each box is 200 quarters of green malt, which represent a 34 inch “dip” at the end of the germination cycle; this capacity has been increased without detriment to the finished product by nearly 10%; since the plant was first brought into operation. Filling of the boxes, which takes approximately one hour, is carried out by the grain and water pumping method and without the need of detachable pipes. A centralised pipe with 24 offset outlets runs the length of each box above the turner units, and therefore forms equal heaps of grain evenly distributed over the length and width of the box floor: levelling automatically takes place when the spiral turners complete their first traverse. The spiral turner/stripper units are in themselves an interesting design feature as they can readily be converted manually from a turner to a stripper or vice versa in a matter of five or six minutes. The turning operation takes exactly one hour and the machine automatically comes to rest at the end of traverse, the electrical trips reset themselves for making the return traverse eight hours later, or at whatever interval is thought desirable.
When germination is complete a final turn is given to lighten the grain immediately before the stripping operation; the concaves at both ends of the box are removed; the spirals are then detached and parked at the rear end of the box and the bridge section of the machine is driven forward under the control of an operator.
A large worm conveyor is housed within a “U” shaped concrete trough covered with inverted “V” deflectors and grids at the discharge end of the box: the worm feeds a grain malt elevator, located in the walkway of box No. 1 and in turn discharges to two similar size worm conveyers for conveying the product across to the centralised kiln door and into a mobile piler and spreader. The stripping operation, which takes about one-and-a-half hours, complies with the bulldozing principle, whereby the bridge unit is driven in reverse over the top of the green malt and when the forward traverse is engaged the blade ploughs its way through the bed of grain and into a vertical position; the traverse is continued until the “bite” is discharged through the grids into the green malt convevor.