Tilbury Grain Terminal regains 36,000 tonnes of storage capacity as construction work of 10 steel silos, associated flat store & connecting high-capacity handling system is completed.
Its not every day that a customer has two challenging situations such as a steel silo collapse & subsequent concrete silo fire & dust explosion to deal with on-site. The Grain Terminal at the Port of Tilbury experienced this very occurrence with two serious incidents in September 2018 & July 2020 respectively. Losing overall 70,000 tonnes of cereal storage and the ability to transfer grain to neighbouring facilities necessitated some significant strategic operational & reconstruction planning, all this whilst still maintaining their day-to-day customer business activities within the Port.
Assuming the role as the Principal Designer & Principal Contractor for the initial steel Silo 3 complex rebuild, T H WHITE Projects were also awarded the contract extension which included an interconnecting high-capacity transfer reclaim conveying and elevating system. This would link up and interface with operations within the main Grain Terminal enabling not just a connection with the 20,000 tonne steel silos, but also with the adjacent 16,000 tonne flat store and high-level belt conveying gallery to feed the adjoining flour mills of ADM & Allied.
The two projects have been designed, manufactured and installed in tandem such that both could be fully commissioned at the same time. The new concrete grain Silo 4 reconstruction currently underway alongside these projects, is due for completion in January 2024.
Throughout the project all viable layout options have been technically and commercially considered to ensure the correct solution is selected whilst being ATEX compliant and heavily engaged in CDM Regulations for optimal site safety within a small footprint of engagement for the site-based contractors.
The rebuild of the Silo 3 complex was first on the agenda and after the demolition of the remaining silos, the bases were adapted to have the top slab cut away and removed with its replacement having the concrete reinforcement designed to accept the new silo wall stiffeners and their location around the perimeter of the corrugated steel silos. The grain storage complex is arranged in two rows of five silos, 11m diameter x 30m high, 2000 tonne flat bottom, corrugated design, each one having a man access personnel door at the base slab level as well as the usual material repose level entry hatch with stair access. Each 2000 tonne silo includes a 150tph sweep discharger, low & high-level probes whilst four of the silos also have temperature monitoring and twin sets of aeration fans offering extended crop management and condition monitoring.
Silo 3 is designed to eventually be fed at a rate of 700 tph from the concrete silos in the Grain Terminal via a series of overhead 800mm wide Guttridge chain conveyors that are fitted with motorised slides for the steel silo distribution and located on T H WHITE Projects specially designed 3m wide heavy-duty catwalks with extended platforms and railings for safe access & maintenance. Material can be reclaimed via the silo main central discharge points at 650tph into one of two underground chain conveyors installed in 2.4m wide x 2.2m high tunnels running beneath the rows of silos which have safe stair access down inside via a weatherproof enclosure.
As part of the Silo 3 works a new 40m tall emergency access/maintenance tower, also designed and installed by T H WHITE Projects acted as an intermediate support for the bridges that connect the high-level conveyors across to Silo 4. Two new transformers and compounds were installed for both the Silo 3 and transfer reclaim system at different locations on site including MCC switch rooms and the associated site wiring, lighting, automated controls and system integration with the Grain Terminal.
The Silo 3 high and low level interconnecting conveyors have been adapted to allow connection into the transfer reclaim system and then for extension and modification when the Silo 4 concrete grain terminal comes back on stream later in 2023. The transfer reclaim system will be heavily utilised whilst the new concrete Silo 4, which is currently making good progress, is constructed.
Connecting the feed to and from the Grain Terminal are a series of high-capacity chain conveyors rated at 500 tph on the transfer and 650t ph on the reclaim plus a single common Guttridge elevator catering for all selected routes.
To implement the transfer reclaim arrangement a significant amount of civil engineering design and ongoing inspection via CSP was required to support the necessary groundworks throughout the site. The groundworks content included all the necessary piled concrete bases for the towers, trestles, plinths, switch rooms, transformers & main tower elevator pit plus the associated drainage, sumps, pumping station, road bridge and fire main dry riser.
All the fabricated hot dip galvanised steelwork on the contract has been structurally designed and manufactured by T H WHITE Projects and installed using Graph Engineering equipment. This controls ensured optimal quality, on-time delivery and maintained accuracy for on-site alignment, The steelwork arrangement includes a short transfer tower near the Grain Terminal centre house and a very tall tower near to Silo 3 which is connected by a double deck gantry conveying structure with trestles to ground across approximately 100m. The double deck gantries are contained within an extremely tight footprint running alongside Silo 4 and the adjacent bulk flat storage facility with additional low- and high-level transitions at either end into the centre house & Silo 3 respectively.
Throughout the project, design stairways and safe-operator maintenance platforms have been incorporated plus the inclusion of lifting beams, electrical sockets and lighting. This is very evident in the main operating tower which houses the common belt and bucket elevator through its middle as it travels upwards from the 5m deep pit to the top of the tower over a 45m distance and just over 200 steps if you are ascending the numerous flights of stairs. In the base of the tower the lower-level area is clad to assist in the weatherproofing of the large elevator pit which has safe-stair personnel access inside. Further cladding and enclosure is present towards the top section of the tower structure where the connection is made with the mill gallery belt conveyor and feed system. Also contained within the tower is a significant amount of interconnecting 600mm square wear resistant lined chute runs and diverter valves connecting the various material routes. Plate magnets are deployed in the elevator chutes to collect any ferrous objects in the feed’s material flow supported by the Fike dust protection system.
Further protection of the slow speed belt & bucket elevator with an internal ATEX zone 20 rating is the inclusion of plastic buckets, head & boot belt alignment, bearing, rotation and speed sensors. Two Delta Neu dust filters & the associated dust extraction system has been installed & successfully operating within the main tower structure. Filter 1 is dedicated to the elevator operation with Filter 2 functioning in conjunction with the grain feed onto the enclosed mill gallery belt conveyor where a new aspirated infeed coffin box has been incorporated.
Key to the project is the overall system automation and control of which working under T H WHITE Projects in conjunction with D B Brooks as the MCC & site wiring contractor, TBA have ensured an accurate software design, its implementation & integration with the existing Grain Terminal operating system.
After a successful period of dry & wet commissioning the 20,000 tonne steel silo grain storage facility, connecting transfer reclaim conveying & elevating system and 16,000 tonne bulk flat store became operational in August with the final commissioning & handover to the Port of Tilbury London Ltd completed this February 2023. Based in the Southeast of England and located on the banks of the River Thames, the Grain Terminal which handles approximately 2 million tonnes of cereals, pulses & beans per annum was initially built in the 1960s & plays a significant role throughout the global market in ensuring the food chain is reliably supported & supplied with on time quality materials.
The team at T H WHITE Projects would like to thank the close co-operation of the client, our suppliers and onsite contractors in bringing this challenging and rewarding handling & storage project to fruition within the anticipated programme window thus enabling the functionality of the new silo 3 storage, mill gallery connectivity and adjoining flat storage facility.
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