Friday 18th Sep, 2020

Conveying innovations from thyssenkrupp

thyssenkrupp has developed two new ways to unlock a belt conveyor system’s productivity and improve its reliability – digital twins and rail-running conveyors.

A major challenge when it comes to designing and building conveyors is the fact that real-life operation and performance can differ from design expectations. Even identical conveyors, when installed and operated side-by-side, may see different performance issues. 

Designers must deal with a number of variables and complex operating conditions that can get in the way of the conveyor’s primary goal of transporting the required amount of material from A to B reliably.

Determining how reliable a conveyor is requires information, and a considerable amount comes from the system in operation. Failure data, performance history and maintenance issues are critical.

Alexandre Loyola, thyssenkrupp’s Digital Twin Products Manager, says when a conveyor performs poorly, it is all too easy for the designer to blame the operator and for the operator to blame the design.

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“There is a clear gap between design engineering and operations/maintenance,” Loyola says.

“The more well-known the operating conditions are, the more cost-effective decisions can be made, without sacrificing reliability. Knowing exactly how each component responds to every operating condition and what effect each design decision will have, opens the door to the next level of belt conveyor operation and maintenance.

“The truth is that when design and operation do work together, there is a lot that can be improved. This is where the digital twin plays an important and decisive role.”

thyssenkrupp’s belt conveyor digital twin

Digital twins are a virtual replica of a physical object or system, built from data gathered by Internet of Things technologies, to enable understanding, learning and reasoning.

thyssenkrupp, in partnership with the North American-based Overland Conveyor Company, have developed a digital twin for belt conveyors. The goal of a digital twin is to continually evaluate the conveyor belt to ensure the system is operating as designed.

thyssenkrupp’s digital twin aims to bridge the gap between operation, maintenance and asset design, enabling a complete understanding of the behaviour of every major component against the changes in real operation variables.

This real-time analysis enables a faster and more accurate decision-making process. A classic example is whether the design has to be changed or the operational parameters adjusted.

Creating a digital twin requires a data model to be built. This is a dynamic representation of the belt conveyor, which models each major components and system. Real operating data is then imported into a virtual environment to ensure its operating conditions match reality.

thyssenkrupp’s digital twin is capable of running a number of dynamic simulations, such as starting or stopping, or constant running under different load conditions, using a physics-based engine. These load analyses provides an in-depth understanding about the behaviour of the asset and are completed for each individual major component.

Automated evaluation software can then catch when a conveyor is running beyond the design intentions. thyssenkrupp engineers then review and evaluate the asset to ensure any design or operating changes will benefit the asset.

Digital twins create a benchmark matched to the existing conveyor. This assists with any capacity upgrades or revamps. They also help detect unreliable systems dealing with chronic problems by finding the root causes of the failures. It can even analyse the power demand to understand where excess power is being consumed.

In addition to digital twins, Martin Lurie, Global Technology, Innovation and Sustainability Manager at thyssenkrupp Industrial Solutions says the company has developed a new technology that will revolutionise conveying productivity.

Rail-running conveyors

Rail-running conveyor systems combine the efficiency of rail transport with the continuous nature of belt conveying to provide additional productivity benefits in overland, steep and pipe conveying.

“The rail-running conveyor system overcomes key limitations of conventional belt conveyors, allowing breakthrough performance improvements in several crucial areas,” Lurie says.

“They use conventional fixed idlers to carry a standard belt in the usual configuration near the head and tail of the conveyor with the belt itself carrying all the tension.

“But between the head and tail, the belt rests securely in the cradles of slim, wheeled carts rolling on light rails. In the transition zones between fixed idlers and the carts, the carts rise up to take over from the idlers or drop away to hand the belt back to the fixed idlers.”

Before reaching the head or tail, the cart train turns around independently of the belt, and a light wire rope keeps the carts moving through the turn-around. Automated inspection devices continuously monitor the condition of wheels and bearings at these turnaround locations, where deteriorating bearings or wheels can easily be exchanged. As with conventional rail systems, derailment is a possibility, but carts can be designed to be both resistant to and tolerant of derailments. Low-cost automated derailment detection will allow the conveyor to be stopped should a derailment occur.   

The measured rolling resistance of about 0.4 per cent of the moving weight is comparable to that of light-rail transport. Trough conveyors are typically designed to handle rolling resistances about three to five times higher.

“This much-lower resistance paradigm translates directly into substantial capital expenditure (CAPEX) and operating expense (OPEX) savings, as estimated in published thyssenkrupp case studies for long overland trough conveyors,” Lurie says.

Craig Wheeler of TUNRA and his team at the University of Newcastle, Australia have been developing the technology for nearly a decade. Coincidentally, the Heavy Duty Conveyor group at thyssenkrupp Industrial Solutions had created a number of designs based on similar principles.

The university’s designs are protected by a number of international patents, and now TUNRA and thyssenkrupp are collaborating to bring this product family to the mining industry under exclusive licenses for nearly every country. 

thyssenkrupp’s testing and analysis of the technology has found the technology provides around 20 to 50 per cent CAPEX saving on the engineer-procure portion of a project when compared to conventional trough conveyors, with OPEX costs 20 to 60 per cent lower. Energy consumption was also found to be one third to one fifth of that for long trough conveyors whose path is not governed by steep elevation changes. The technology allows for very tight curves and longer runs to become possible, eliminating the need for more transfer points.

Rail-running pipe conveyors

Pipe conveyors carry material within a wide belt that forms a pipe to isolate the material from the environment and can negotiate much tighter vertical and horizontal curves than a trough conveyor.

Luke Bennett, thyssenkrupp National Sales Manager, says it is in the pipe conveyor field that the rail-running technology becomes immensely compelling.

“The pipe or enclosed version has all the advantages of conventional pipe conveyors, but without the high tensions developed by drawing the pipe through successive rings of fixed idlers,” Bennett says.

“Conventional pipe conveyors have much higher losses than conventional trough conveyors, especially for pipe conveyors that must operate in very cold conditions designed for rolling resistances of perhaps 4.5 per cent, or 10 times higher than a rail-running pipe conveyor.”

These systems also have similar CAPEX and OPEX savings. For example, elevated gantries do not require walkways for idler maintenance, which allows enormous reductions in structural weight. As with the open-trough version of the rail-running conveyor, the pipe version’s OPEX benefits come from lower power consumption, smaller maintenance crews, and lower costs from idler monitoring and replacement. This means that a rail-running pipe conveyor of even relatively short length can show significant advantages over conventional pipe-conveyor technology.

For pipe or enclosed versions of the rail-running conveyor, the loading point and pipe formation is the same as for a conventional pipe conveyor. For a short distance, the pipe belt moves through conventional pipe conveyor idler panels. Then the carts move up to take over from the fixed idlers. To keep the belt closed in its pipe form, the cradle of each cart has a circular bottom. Every two meters there is a fixed idler that presses down on the belt edge to keep the pipe closed, mounted in a frame above the carts.

Mine or plant layouts that are awkward or unfeasible for conventional trough conveyors become candidates for pipe-form belts carried by the circulating carriages. For example, a rail-running pipe conveyor could run in a single flight from pit to plant along the curve of the haul road.

For many pit layouts where the haul road curve radii can be configured to about 100 metres or greater, mines will be able to run haul trucks adjacent to the conveying corridor, allowing for the flexibility of truck haulage alongside the extremely low cost per tonne of belt conveying.

For some mine layouts, a planner might be considering costly trough conveyors on an elevated structure, such as that visible Figure 1.

Due to the rail-running conveyor’s ability to negotiate very tight curves, the material could be carried by either trough or pipe rail-running conveyor versions along the haul road, on a path indicated by the blue line. Even though the length is greater than the direct, elevated route, the CAPEX cost per metre as well as the much lower maintenance intensity makes the curved rail-running conveyor the lowest cost choice.

The pipe conveyor version of the system is now ready to be deployed in a pilot installation, ideally carrying 500 to 1000 tonnes per hour of sized material for a distance of up to one kilometre or through an elevation change of 50 to 100 metres. 

Lurie says Australian innovation and tax incentives may be available to companies who partner with thyssenkrupp to build pilot-scale systems.

“In fact, thyssenkrupp is about to complete a study comparing conventional and rail-running designs for a specific project in Australia, with very promising numbers emerging thus far,” he says.