Conveying systems must meet the most stringent requirements for transporting hot materials safely and efficiently....
Pipe conveyors have been in use in Europe since the early 1980s. They are becoming a highly recognised and accepted solution for a number of applications and now represent the state of the art in conveying technology. However, the application potential is far from exhausted, because the possibilities and advantages of this system are still largely unknown to many potential users and in various industries and countries. On-going development is continually expanding the limitations of use. However, not every supplier of pipe conveyors has the expertise necessary to fully exhaust the potential – unlike the specialists in the BEUMER Group.
The range of products offered by BEUMER, a family business headquartered in Beckum, is divided into three fields: conveying and loading technology, palletising and packaging technology and sortation and distribution systems. Conveying and loading technology includes, for example, pipe conveyors, troughed belt conveyors, apron conveyors and bucket elevators. The acquisition of KOCH Holding Czech Republic, bulk material handling specialists, has incorporated additional expertise and years of experience with pipe conveyors into BEUMER’s portfolio. Both companies have extensive experience and references in the development, planning and implementation of pipe conveyors, which are now united as the “Best of both worlds”.
Design, features and applications
To receive material, the belt is open like a conventional belt conveyor in the feeding area of the pipe conveyor. After a certain distance, which depends on the pipe diameter or belt width, special belt forming rollers mould the belt into the desired closed shape. The rollers smoothly roll in the belt, avoiding friction between the belt surfaces. From this point on, the closed belt runs along the entire conveying distance, through what are known as panels and partition plates. Six rollers are installed in a staggered arrangement on each of these panels for the upper and lower strands.
The tubular shape of the belt makes it possible to manoeuvre horizontal and vertical curves without additional transfer stations. This increases operational reliability. At the end of the conveying line, the belt opens on its own and discharges the material like a conventional troughed belt conveyor. In the return strand, the belt is rolled back into its tubular shape, using the same method as in the upper strand.
Fundamental design characteristics
One of the fundamental design characteristics of the pipe conveyor is its tubular shape. There are two variations on this shape: the oval and the circular pipe. Each shape has its advantages. For example, an oval shape allows the belt overlap to seal more tightly, because the overlap is flatter than on a circular pipe. When it comes to belt tracking and torsion on straight sections, this shape is more stable – particularly on long conveyors. Due to the lower overall height, the contact surface is smaller, thus reducing the impact of wind on the system. In contrast, the circular shape requires less steel, and the cross section of the steel construction allows for favourable structural stability. These characteristics enable lower costs, decreased load on the lower idlers and increased service life of the system.
There is enough flexibility for pipe conveyors to be individually tailored to the various needs of the customer. The belt overlap creates a closed conveying system. The belt quality is selected depending on the application, conveying capacity and length. For instance, a differentiation is made between normal, heat resistant or non-abrasive rubber qualities. Steel cables or textile fabric can be used as the traction element, depending on the required belt strength. The whole cross section is not used to transport material. The degree of filling is typically limited to approximately 75 percent, depending on the material to be transported. This figure is a safety factor that allows the system to handle any short-term increases in capacity.
Even though the pipe conveyor is establishing itself more and more, the troughed belt conveyor will continue to have its use. Which conveyor is more suitable depends on the respective application and local conditions.
Features of a pipe conveyor
The inherent features of a pipe conveyor facilitate transportation solutions that are either impossible with other conveying systems or that can only be implemented with significant limitations or additional costs. The enclosed design of the pipe conveyor protects the material from the elements, and the elements from the material. Therefore, the system helps meet environmental protection goals and fulfil official requirements. Tight curve radii and large inclines can be navigated.
This facilitates flexible routing and provides the opportunity to go around existing obstacles, making a number of solutions possible that allow existing terrain and structures to remain intact. Depending on the application, the capital costs of the conveyor itself might be higher in certain cases for a pipe conveyor over a conventional troughed belt conveyor. However, these additional costs are put into perspective when the pipe conveyor is able to make full use of its advantages. Once transfer points, modifications to plant equipment, excavation work or costly dust or noise pollution measures can be avoided, the savings for the customer greatly outweigh the extra costs for the optimal conveying system.
Pipe conveyors in use
On principle, pipe conveyors are used when, for instance, dusty, wet, sticky or light-weight material needs to be conveyed. They are also used in cases of high environmental demands and/or when local conditions require curved, narrow conveying systems. This leads to the following fields of application:
- The cement industry, for cement, clinker, additives or surrogate fuels
- Power plants, for fuel and also for waste, such as ash of various consistencies
- Harbour handling and transfer areas, for the transportation of bulk materials to and/or from off-shore ship loading or unloading systems
- The transportation of coal, limestone, gravel, ore or artificial fertiliser
- The food and beverage industry, with the use of food safe belts
In one cement plant for the company Dyckerhoff, for example, two relatively short BEUMER pipe conveyors are in use. What is special about these conveyors is their 29 degree inclination. Depending on the material properties, a pipe conveyor can – due to its enclosed design – overcome even larger inclines, which are not possible with a conventional troughed belt conveyor. Because a compact column of material is created inside the pipe, it is more difficult for material to slide backwards. Dyckerhoff took the opportunity to also design the conveying line with overlapping horizontal and vertical curves that required three dimensionally manufactured steel frames. This minimised the length of the conveyor and further reduced costs.
In another example, KOCH Holding a.s. supplied and installed a pipe conveyor for a cement plant in Ladce, Slovakia. This conveyor transports surrogate fuels to the furnace. More and more often, pipe conveyors are being used to transport crushed waste, which is being used as fuel. This is often light-weight material or household waste. Transporting waste using a pipe conveyor is cost-efficient and eliminates unpleasant odours. Also, the track is routed to conform with the existing buildings and surroundings.
In the Czech town of Melnik, a pipe conveyor is used to transport wet ash two kilometres from a power plant to the waste site. With a pipe diameter of 350 millimetres, the pipe conveyor first crosses the premises of the power plant, then open country. It goes through three horizontal and four vertical curves. Since the wet ash must be returned to the plant later for recycling, the pipe conveyor is designed to be reversible and can be converted within 24 hours.
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