Agora Services have recently supplied two flat bottom corrugated silos to Takoradi Flour Mill, to be used for storing and distributing wheat, this is effectively a transfer station. The silos are 17.77 m diameter, 21 m tall, with a 28 degree conical roof and are the largest that they have installed. These have been supplied with a heavy duty pressed steel gantry, hot dip galvanised to prevent corrosion, decked with open mesh floor grid. There is also a 25 m tall elevator tower, complete with 28.5 m tall 200 tph belt and bucket elevator, with maintenance platforms and access ladders. A new 200 tph chain and flight intake conveyor, 13.6 m long which is being installed in a cast concrete drive over tip ramp. The intake will feed into the elevator, which in turn feeds a 200 tph over silo chain and flight conveyor.
Outloading the wheat will be done using screw augers at 90 tph, measuring 12.7 m from centre of inlet to centre of outlet, fabricated in two parts for easy of installation and transport. The main section being 10.4 m overall length and the head section being 3.15 m overall length, the outloading auger can easily be transported by container. The outloading augers have two additional bleed spouts, once the angle of repose has been reached from the centre intake hopper, these are opened to drain the wheat from round the sweep auger. The sweep auger will then slowly rotate round the silo, pushing the wheat into the centre hopper and discharging via the outloading auger. The sweeps are 90 tph and fitted with sensors to halt the progression until the screw has cleared the grain, progression is achieved using a toothed wheel and track. The advantage of the track is that it gives positive traction, if the grain slides down it can't knock the sweep auger backwards, there is also not lose of traction as the wheel can't slip on the floor.
The wheat is feed from the outloading auger into a 100 tph chain and flight recovery conveyor, 18.5 m long. This feeds an existing elevator to load a new rectangular outloading silo with is elevated above the plant operators control room. The grain being loading into lorries for onward transport.
Our customer has now received all the parts and has been erecting the corrugated silos, one is up completely and the second has just four rings of panels remaining. They have started to install the steelwork for the outloading silo, which is being built on top of a concrete structure that will form the electrical plant room and operators office. This was the customers preferred option to raise the height of the outloading silo but not increase the steelwork required, quite an ingenious and cost effective solution.
As we get more news and photos regarding the install of this project we will add them to the article.
Our 160 tonne CNC pressbrake in action folding up some racking shelves for a customer. These shelves have been laser profiled from 1.5mm galvanised steel, with eight folds to form the shelf. The original shelve were painted, but we have used the galvanised steel as a hard wearing alternative. The racking is boltless, the slots in the sides of shelf simply slot onto louvres on the vertical legs.
Agora Services have retro fitted six new hot dip galvanised steel hoppers for a customer in some Brice Baker silos. The customer had concerns regarding the ingress of water, which could have effectd the stored product and asked Agora to look into repairing them. After an initial consultation and an internal inspection, it was deemed that the main silo structure was still in reasonable condition and did not require replacing. Water ingress and fatigue had caused damage to the original hopper panels where they rested on the chine ring, rain water had caused corrosion at this point meaning that the panels could leak. The problem was with the original design and construction, the panels hang over the chine and are bolted down with clamps holding a base ring for the cylinder. As with all silos, being filled and emptied on a regular basis, there are stress's place on these panels causing them to flex. The result in this case was that the top of the hopper was starting to rust through.
We designed a new chine ring insert to bolt to the inside of the exist rolled channel, with a hopper skirt welded in place. Once fabricated, with the addition of gusset plates, this new chine is very strong and does not need the silo to be dismantled to replace the hopper. In the original Brice Baker design the cylinder is fixed over the hopper panels, meaning that they can't be simply unbolted and replaced.
The first step for installation meant cutting out the original hopper, leaving the section of this under the cylinder in place. The channel, the remaining section of the hopper panels, the clamp plates and the base ring of the cylinder were cleaned up with a wire brush and a painted. We then marked out and drilled the channel to bolt in the new insert. The hopper panels then fix to the skirt and finally an outlet cone is fitted ready for a new set of slides and a new conveyor system.
Pipe adapter fabricated for a customer to suit a 915 mm outside diameter pipe. This will be welded to the end of a steel pipe that is going to be installed using tunnelling technology with a rotating cutting head.
The cylinder is made up of 15 mm rolled plate, with two hatches to allow access to the bolts holding the cutter head in place. The cutting head is sleeved in the end with a reinforced ring machined to suit and held in place with four bolts.
Agora have also made several entrance and exit seals for these types of tunneling machine for use in both flat and curved shafts.
Agora have fabricated a modular sound proof acoustic enclosure for a local tool company for their service engineers to test both electrical and pneumatic power tools without the need for ear protection being used. The customer had been give a basic concept by their sound engineer following an appraisal, the idea being to fabricate a steel box lined with melamine foam wrapped loosely with melinex film. To work the film has to be loose and cannot have any contact with the frame or the inner layer of steel mesh.
The box needed to be able to be dismantled easily for cleaning due to oil splashing off the tools. With this in mind we came up with a design based on a box within a box. The inner box was fabricated from perforated galvanised steel, with the front being open for access. Individual pressed box panels were then made for the base, back, top and sides. These were made to be open on the inside face to allow the acoustic foam insulation to be installed without the risk of damaging the 23 micron film. To hold the panels together toggle latches had been used, meaning that no tools are required for assembly or cleaning procedures. A trip tray was also included to catch the majority of the oil. The entrance of the box was to then have a rubber opening so that operatives can push the tools through. The acoustic insulation and the rubber were fitted by the customer.
They are currently running a trial on this system and if approved are set to order a further 17 units.
Agora have been asked to make some jigs for holding leather covers whilst they are sprayed with glue prior to being applied to upholstery. The initial enquiry was for a mild steel fabrication with a powder coat finish, but that weight was a key issue, as the operative would be handling these frames constantly. The system used previously was light weight, but had little strength and thus flexed about making them awkward to handle. Given the brief we suggested that the mild steel be substituted for aluminium, saving on weight and with the advantage of not needing a coating for corrosion prevention. The customer had voiced concern that aluminium could become damaged by the clips used to hold the leather in place and thus stainless was used for the profiled plates. Whilst the aluminium frames are welded, the stainless plates have had to be bonded to the frame.
The customer has found the first set of jigs to be a success and has since had a second set, with a view to changing more of their production to use the same system. The advantage being that the heaviest frame was only approximately 2.9 kg in weight, yet was stiff, making handling the frames easier.
When boring tunnels in areas where water can be a problem, a seal is used to push the machine and tunnel sections through. This means that the water can be kept out of the shaft or tunnel that the machine starts from. We have in recent months fabricated a number of these for a client, these have been curved to suit different sized round shafts, but we have also altered an existing unit for use in a square shaft.
Agora have fabricated 2000 pressed galvanised steel racking dividers to help a local warehouse keep items in separate locations for order picking. These were only small, 424 mm x 195 mm and 16 mm return flanges on four sides with various cut outs to suit the racking. They are to be bolted into the exist small parts racking to make designated picking locations to avoid items being miss-picked and reduce dispatch errors.
The bollards were made to order, using 100 mm square hollow section with a fully welded and gusseted base plate. To help prevent damage to the bollards, forklifts and goods being moved on pallets or trolleys, a rubber D fender was fixed to the front of bollard. These had been made for one area of the warehouse racking as single units standing at the end of the aisle to protect a steel clad wall. In another area as pairs fitted either side of the aisle at one end to prevent forklifts from coming out into a pedestrian walkway. The pairs had cut back base plates to fit closer to the forklift floor guide rails and thus were handed. The finish being yellow and black painted strips, photos below.
We have since made some pressed galvanised shelf fronts to replace damaged parts in their small items racking.
Agora had been asked by a new customer to carryout a number of silo inspections in the South East of England. In total six locations were inspected over a three day period, using a trailer mounted towable cherry picker to gain access. The inspection was to identify potential problems or faults with the silos and their ancillary equipment.
Various problems were identified, the main issue being with the over/under pressure relief valves on most of the silos and damage to the shut off valves in the hopper. One silo having a restricted flow due to a blockage in the hopper. Where possible the pressure relief valves were cleaned out and a visual inspection made to check that the springs still closed the valve plates and were not stuck/obstructed. It was found that two silos needed these valves replacing, access is an issue for the maintenance of these valves as like many of this type of cement batching silos there is no access ladder to the roof. Some photos of what we found are below:
The silo that had become blocked was cleared out initially by removing the lumps that were free moving and rodding the outlet to draw the cement out through the auger screw. Once the majority was cleared and saved for use in the batching lorries, the outlet cone was removed and the solid lump broken out of the valve. There were signs on water ingress from the cone flange that had caused the blockage, this was cleaned up, the foam seal removed and all lumps scrapped out. We also removed the aeration pads as they had become damaged / collapsed, were not working and had help to cause the build up of cement. The lump in the butterfly valve had become so hard that the operators had torn the blade trying to open and close it to break up the blockage. As the valve is a non standard unit, we could not replace it at the time and instead welded the blade to make a temporary repair. We will be returning to this silo to change the shut off valve shortly, but will have to also replace the flanges on the cone and the auger for a standard off the shelf valve to fit. This will have to be done at a couple of sites, along with changing the pressure relief valves (PRV) on the roofs.
Like all items of plant, silos, plus their ancillaries, do require regular inspection and maintenance. This will help to ensure that they are in good working order and minimize down time by identifying problems before they become a serious issue. Faults found can then be dealt with through a planned maintenance period rather than a breakdown situation. If this type of service is of interest to you please contact us.
We have been back to the sites owned by this customer to inspect their silos again as part of a regular maintenance program and have identified other problems that would have effected the safe running of the plants. One of the main problems identified has been with the over/under pressure relief valves becoming blocked. There are various reasons for this to happen. It could be due to a general build up of dust in layers around the valve, this would be gradual and can be prevented by regular cleaning, which we have done each time we inspect. Another reason is overfilling the silo, material is jammed up into the valve and can clog it, which we think has happened here. If this material then becomes damp it will set and prevent the valve from working, giving a potential for the silo to become over pressured. This can only be prevented by making sure that you know how much material you have in the silo before trying to fill it again, or making sure that the high level probe is in full working order and that the delivery driver knows to stop once the alarm has sounded. Where silos are being over filled we would recommend that a protection system be used, an alarm sounds and if filling is not stopped a valve shuts off the in take pipe.
The photographs above show some ventilation fan bases and canopies for a local tunnelling company. These will be fitted out with Elta ventilation fans and silenced for use in built up areas such as London. The robust design allows for the units to be picked up either by forklift or crane using lifting chains with lugs. We have fabricated 6 units 4.2 m long and 2 smaller units at 2.5 m.