Changing a belt on the fly
Do you need to change the belt in your conveyor system but want to avoid prolonged shutdowns? We have a solution, and it’s based on a very special method. In our blog post we’ll explain how you can do it smoothly.
A few years ago, we supplied a complex system consisting of several belt conveyors to the TPI Polene Public Company Ltd, a cement manufacturer in Thailand. The system transported limestone from the quarry to the blending bed. When the belt of the nearly 3.5-kilometer-long Overland Conveyor was through, we did not want to change the individual belt sections one after the other in long operating stops. Instead of replacing the belt sections one by one and stopping the system each time, we recommended a method that allowed the customer to insert a new belt and remove the old one in a single operation. This saved the customer a huge amount of time and enabled it to avoid unplanned downtimes.
We support our customers from the initial project meeting up to startup, and afterwards we make sure that the system runs safely on a sustained basis. When the risk of failure increased at TPI Polene Public Company due to the belt in the Overland conveyor wearing out, replacement became necessary.
The conventional method for replacing a belt is to change the sections one by one. Depending on the size of the belt rolls, eight to eighteen sections may be involved. When employees do all of this work at once, it is very time-consuming. The cement manufacturer therefore wanted to replace the segments in steps in order to spread out the downtimes and minimize the impact on the workflow. However, the total downtime of the conveyor system would still have been very large. Changing the belt in such a long system is no easy task, so a new solution had to be found that would be more satisfactory.
Why we do it all at once
In order to reduce the downtime to a minimum, we suggested replacing the belt all at once. In our process the belt rolls are joined next to the conveyor system to form a long belt which is then connected to the old one. With the help of the existing drive unit and other equipment, we pull the new belt into the system while pulling the old one out.
Our technicians first surveyed the conveyor to find suitable space for the new belt. The area had to be right next to the system, easily accessible and large enough so that workers could do preparations. As a rule, the ends of the belt are spliced by means of vulcanization. For this it is necessary to have space for the work and for stocking the necessary materials. The belt sections were stored outdoors and protected from UV radiation by a special film. Splicing was carried out in an air-conditioned tent and the sections were provided on a just-in-time basis.
The preparations take place during ongoing operations. This also means that the team is not under so much time pressure. This, but also better accessibility and the use of weather protection, ensures the best possible quality in the creation of the belt splices.
Why the weather is so important
Weather protection is important because vulcanization can be complicated by environmental conditions such as the nature of the terrain and, above all, by the weather. Snow, frost, ice or rain can cause employees to take a forced break because the process requires a lot of time. For example, we’d never change a belt during the monsoon in India.
Based on our preparations and broad experience, we were able to make a reliable estimate of the total downtime during belt replacement. The work itself was performed by the customer’s service personnel. A supervisor provided by the belt supplier was on hand to monitor the workmanship.
Why fewer downtimes mean lower costs
The conventional procedure is cheaper if one looks only at the direct costs. However, the new one has the advantage of significantly shorter downtimes. This has a positive effect on the total costs, especially with conveyor systems that are several kilometers long, like that operated by the TPI Polene Public Company Ltd. And because we can replace the belt in one go, the user benefits from much greater safety: The risk of an unplanned failure due to poor-quality belt splices or time pressure, for example, is virtually non-existent.
We have also successfully used this process in China at Sichuan Yadong Cement Co, Ltd.: The conveyor was a 12.5-kilometer-long overland conveyor.
Facts about belt replacement:
The entire belt is replaced at once.
The belt rolls are joined to form a long belt next to the conveyor system which is then connected with the old belt.
The new belt is pulled into the system and the old one is removed at the same time.
There must be space next to the system for preparations and belt splicing (Belt ends are joined together by means of hot vulcanization).
The system at TPI Polene Public Company Ltd:
- Several belt conveyers: two running down hill in regenerative mode and one troughed belt conveyor with horizontal curves
- PLC system control
- Transfer stations and filter systems
- Foreign material separators
- Conveying capacity of 2,200 t/h
- Acceleration belt
- Overland conveyor: distance between centres of 3,464 m, speed of 4.5 m/s
- Other conveyor systems: overall length of 989 m, for removing material from the blending bed and feeding the primary hopper of the raw mills
Do you also need to replace the belt in your system or do you have other questions on this topic?
Get in touch with us – we are happy to help!
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