Ship loaders are a key component in bulk handling systems used to load bulk solids onto ships, often for export. Their capabilities and cost-efficiencies are critically important to miners, railroad systems, ports and shippers, where capacity improvements of even a few percentage points can mean millions of dollars profit.
But these loaders regularly experience high temperatures and excessive wear, as well as not having the “throw” performance to efficiently maximise each load. Throw refers to how far the material falls from the discharge point (typically a trimmer flap or spoon) into the hatch of the ship.
“The result can be that you end up paying to ship air or taking longer to do the job of fitting in more coal, or whatever bulk material you are transporting. High temperatures resulting from less-than-optimal design can also more quickly degrade the properties of liners and reduce life, while poor throw may lower efficiency and lead to equipment operating in too close a proximity to ships, where there is a risk the ship loader can collide with the ship and cause unwanted cost and downtime,” says Mr Dennis Pomfret, Managing Director, Chute Technology, which has collaborated with the University of Newcastle, to address these issues, and design a superior solution, contained in a scientific paper, Thermal investigation and optimised design of a ship loader.
The University of Newcastle is an Australian leader in issues related to the sustainability of mining, including being a Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals.
In the joint paper, Chute Technology has brought to bear its specialist knowledge in solving materials handling problems, including more than 40 years of practical experience in optimising material flow in loaders throughout Australia and the USA. The company and the university combined their in-house expertise and technologies, including Chute Technology’s Discrete Element Method (DEM), Heat Transfer Analysis (NASTRAN), and thermal testing, to develop an optimised trimmer flap design.
A trimmer flap, or spoon (as shown below), is designed to be mounted at the end of the ship loader, to control material flow onto the ship.
The investigative paper, led by Chute Technology employees Jiahe Shen and Gian Naldi, in conjunction with Craig Wheeler from the University of Newcastle, shows how performance improvements offered by the optimised trimmer flap were then demonstrated by simulations. Modelling and simulations showed the potential performance gains, based on real-world inputs.
“This is not a theoretical exercise. This is a thoroughly researched practical demonstration of how good design can optimise a process to produce the most efficient and sustainable outcome that uses the least resources for a permanent improvement,” says Mr Pomfret.
Optimised trimmer flap design
Chute Technology modelled and tested both a constant radius and parabolic trimmer flap design, which both performed better than the existing design.
The constant radius design achieved the best overall results, with throw performance increased at all angles, as shown in the diagram below.
“Our analysis and modelling showed that not only had throw performance increased at every boom angle, but we were better able to control spillage, and the heat was better dispersed throughout the chute, leading to increased life of the wear liners,” said Mr Pomfret.
“Better material flow management also means less dust dissipation, which is an important consideration for operations situated in close proximity to towns and residential areas,” he said.
“Typically, wear liners used are Chromium Carbide Overlay wear plates. The high surface temperatures, in conjunction with thermal shocks – caused by moisture in coal, for example – generate high stresses and deformation of the liner, which ultimately can cause cracks and failure of the liner”.
“At this point of failure, a change-out of the trimmer flap is required, causing downtime, delay and cost to the operator. Through Chute Technology’s improved design, the ship can be loaded more completely, and wear liners will last longer, since they are not being subjected to the same surface temperatures and impact angles.”
Testing and modelling in this paper was done using coal as the material being loaded onto the ship, but the same improved designs could deliver gains to a broad range of bulk solids, says Mr Pomfret.
“The improved trimmer flap design will deliver efficiency, performance and reduced wear to bulk solids being loaded onto ships via ship loaders,” he said.
“Chute Technology also designed environmentally conscious features for the new trimmer flap. Our new design included a mechanism that allowed the trimmer flap to tilt horizontally, to prevent any spillage from entering the water when a ship is not docked. Previous designs could be impacted by vibration, movement, wind and other factors and some spillage or debris could fall out of the chute, into the water below.”
“I’d like to congratulate Jiahe and Gian on such a successful paper, as well as University of Newcastle employee Craig Wheeler. All parties made outstanding contributions to this paper, which will provide real-word benefits to materials handling and ship loading operations,” said Mr Pomfret.
“This paper perfectly showcases the real world gains that can be achieved through analysing current processes and developing new designs that improve performance.”
To request a full copy of the paper, Thermal investigation and optimised design of a ship loader, contact Chute Technology on 1300 833 140, or email email@example.com