This paper describes the evolution of Pipe Conveyors from conventional modes of transport of bulk solids materials by troughed belt conveyors. Various key components of FFE CKIT pipe conveyors are explained. Described are the application of pipe conveyors with regard to various materials conveyed, complex three dimensional routing, elimination of multiple transfer points, environmental protection and return belt conveyance. Pipe conveyor installations in India set up this year by FFE CKIT, for the transport of diverse materials as fluidized rock phosphate, fly ash / gypsum and cement are taken up for a brief presentation in this paper for their interest to the Cement Industry.
The Japan Pipe Conveyor Company was responsible for the initial development of the Pipe Conveyor and patented the original technology that lead to its first successful application in 1979. The basis of the patent was the ability to form a trough belt conveyor into a pipe shape using a special belt construction. Bridgestone Corporation since obtained all the rights of the JPC system and operates through a system of international licencees. Of the over 900 pipe conveyors built worldwide to date, the majority of the installations are in Japan, built with the original JPC technology followed by USA. Krupp Robins Inc. who were granted the exclusive marketing rights from Bridgestone for the United States have built the longest single flight pipe conveyor of about 5.0 km in length. The majority of pipe conveyors are however lesser than 100 m in length with hourly rates lower than 100 tph. In the early 1990s the original JPC patents started to expire, leaving the door open for other conveyor manufacturers alternative to JPC to enter the market.
In India, of the dozen or so pipe conveyor installations, the majority have been designed by CKIT of South Africa including the largest Pipe Conveyor (1800 tph; 3.2 km) in the world at Dahej for Birla Copper.
Since August 2001, FFE Minerals India Private Ltd. ( a member of the FL Smidth Fuller Engineering Group) have entered into an exclusive license agreement with CKIT South Africa for the manufacture and supply of Pipe Conveying Systems in the Indian subcontinent.
Pipe conveyors find their application in virtually every industry for the transport of bulk solids. These include cement, fertilizer, coal, power, steel, pulp and paper, food grains etc. Pipe conveyors overcome several of the problems commonly associated with conventional conveyors, e.g. spillage of materials, belt training, limited angles of conveyance, horizontal curves and multiple flights.
Some of the difficult materials handled by pipe conveyors are cement, flyash, gypsum, fluidized rock phosphate, alumina, sinter, sludge, wood chips etc.
Pipe conveyors have also developed as an alternate and significant energy saving device to pneumatic means of conveying of fine material.
The pipe conveyor resembles a troughed belt conveyor at its tail end where the material is loaded. Thereupon the belt is made to pass over a series of transition idlers of varying troughing angles to form the pipe shape. Prior to the discharge pulley the belt is made to open to effect material discharge over the head pulley drum. Largely due to reasons of engineering geometry as well as with a view to keeping the dirty side of material with the pipe shape, the return belt is also made to form the pipe shape.
One of the big advantages of a pipe conveyor is that material transported contained within the rolled tubular shape of the belt for the majority of its conveying distance. This has the following benefits:
The increased friction between material and the pipe shape of conveyors due to packing makes generally a 50 % higher angle of conveyance possible by pipe conveyors as compared with conventional troughed belt conveyors to angles of inclination as high as 29 degrees. This results in therefore :
The flexibility of the pipe shape permits the belt to be curved both horizontally as well as vertically. In many instances this is a big advantage as it eliminates transfer points where there is a relatively sharp change in conveyor direction. A single conveyor can thus replace several conventional belt conveyors reducing:
The basic design feature of the pipe conveyor belt enables using the return side of the belt for conveying materials in the opposite direction. The conveying in of materials and conveying out of materials in a single belt possible in longer belt conveyor installations especially for plants in the vicinity of ports offer distinct cost advantages.
A pipe conveyor transports the same volume of material as a conventional troughed belt conveyor that 2.5 to 3 times its pipe diameter. This means that pipe conveyor requires support structures of narrower widths and often lesser weights.
When a single pipe conveyor replaces several conveyors in a system, the total power consumed is considerably lower. A series of several conventional belt conveyors also require additional power to lift material at each transfer point.
When the pipe conveyor replaces a pneumatic mode of conveyance, energy savings pay for the pipe conveyor themselves.
Like a conventional belt conveyor, a pipe conveyor comprises of the belt, a feed section, the intermediate sections, the head or discharge section and the drive. Each of these sections are described below:
As in a conventional troughed conveyor and dependent on the belt tensions the construction of a pipe conveyor belt could be fabric or steel cord. However as the belt is required to form the pipe shape, several important features are employed in its design.
A special carcass construction is employed as the belt requires adequate stiffness as it is made to form the pipe passing through the idler rolls. Flexibility for transition from the flat to pipe shape at the feed end and pipe to flat at the discharge end is also essential. A layer of special rubber compound is usually placed between each fabric ply to achieve this.
Belt edge stiffness must be reduced for the belt to overlap and prevent material spillage. The plies at belt edge are therefore broken and specially arranged.
In addition top and bottom belt cover grades as well as curing times are specially controlled to prevent the belts natural tendency to remember its pipe shape.
In steel cord pipe conveyor belts, transverse is used above and below the steel cables with a layer of rubber separating the fabric from the cords.
Phoenix Yule India (with the technical backup of its German parent Company a well known international manufacturer of conveyor and pipe conveyor belting) and in close co operation with FFE CKIT is a leading supplier this belt in India.
The feeding or loading section of a pipe conveyor is similar to that of a conventional belt conveyor. To eliminate the problem of material spillage as associated with troughed belt conveyors the FFE CKIT pipe conveyor feed zone incorporates a specially designed skirt board for effective sealing with low friction impact slider pads. A quick release mechanism enables impact rollers to be lowered for removal even with a moving belt and facilitates ease of maintenance. Transitional idlers from the impact zone to the pipe form, comprise of a series of troughing idlers of varying and adjustable troughing angles. A single guide roller is used to press one edge of the belt below the other as the belt comes together. This idler is installed just ahead of the first circular arranged idler set. This idler eliminates belt edge abrasion and allows proper overlap closing of the belt.
Uniform feed to the pipe conveyor is important in a pipe conveyor for its stability and tracking.
FFE CKIT recommend the use of belt or vibrating feeders to ensure a constant and uniform flow.
The intermediate section of the pipe conveyor is the part where the belt is made to roll into a tubular shape. This is achieved by causing the belt to pass through a set of six idlers arranged in a circle each for the carrying and return run. To prevent squeezing of the belt, the FFE CKIT design incorporates offsetting of idlers alternatively on either side of the panel. The construction of the panel which support the idlers is very simple and can be fabricated from rolled steel sections / plates or pressed from sheet metal plates. Mounting holes are jig drilled to maintain idler mounting accuracy. With the pipe conveyor belt guided by idlers surrounding the belt on all sides, the conveyor is able to negotiate curves and centerline misaligments. To ensure that the belt overlap is located as near the top of the belt on the carrying side, a few set of training idlers are provided with adjustable bottom rollers.
Assisting most in belt stability and also keeping the overlap near the center position is of course the weight of material conveyed in the pipe and its heavy center of gravity on the lower crossection of the belt.
On the return side where the overlap is on the bottom of the pipe shape, the extra weight of the overlap maintains dynamic stability of the belt.
The discharge of the pipe conveyor is similar to that of conventional belt conveyors. The belt in the tubular form is allowed to gradually take the trough shape by a series of idlers of varying troughing angles. Material as discharged over the head pulley.
Modern drives are used by FFE CKIT in all their pipe conveyors which include high efficiency, compact space saving bevel helical gearunits shaft mounted to respective pulleys using shrink discs. Drive motors are usually squirrel cage and equipped with VVVF AC drives. This modern drive ensures smooth starting, allows for stepless belt speed variation to create the desirable belt load crossection suitable for the application and maintains belt stability.
Overland pipe conveying systems offered can incorporate the FFE CKIT triangular gantry. This eliminates access walkways and platforms along the length of the conveyor, providing a cost effective solution. Installed first by CKIT at their Richards Bay Pipe Conveyor installation in South Africa, these conventional facilities have been replaced by a self propelled traveling maintenance trolley, which is mounted onto the triangular gantry structure and travels along the full length of the conveyor. with man carrying maintenance trolley.
This and allows access for inspection and maintenance by plant authorized personnel only.
The trolley is independently powered usually by its own onboard diesel engine drive and allows quick access without fatigue.
Substantial savings in structural costs result in adopting the triangular gantry design with the added efficiency of maintenance personnel.
FFE CKIT Pipe Conveyors installed in India in 2002
Fluidised and ground rock phosphate was hitherto transported from silos to a receiving bin in the phosphoric acid plant pneumatically using FK pumps.
With a view to reduce energy costs and high wear associated with pneumatic conveyance, FFE Minerals India Ltd with CKIT South Africa proposed and entered into a contract with CFL in July 2001 to design, supply, install and commission a Pipe Conveying System for this application.
Commissioned in February 02, technical parameter of this conveyor system are :
| Material Conveyed | Ground Rock Phosphate | |
| Capacity | tph | 100 |
| Particle size | mesh | 95 % minus 35 (425 microns) |
| Bulk density | t/m3 | 1,0 aerated 1,5 consolidated |
| Material temperature | deg C | 70 |
| Conveyor length | m | about 140 |
| Lift | m | 22.9 |
| No of vertical curves | Two (one convex, one concave) | |
| No. of horizontal curve | One | |
| Belt width | mm | 900 |
| Nominal pipe dia | mm | 240 |
| Nominal belt speed | m/s | 1,5 |
| Belt type | EP, 3 ply fabric | |
| Strength | kN/m | 315 |
| Cover thickness | mm | 5/3 ( top, bottom) |
| Carrying side idlers | mm | 127 dia, 6 rolls arranged hexagonally |
| Return side idlers | mm | 127 dia, 6 and 3 alternatively |
| Idler spacing | m | 0.53 2,0 |
| Drive motor | kW | 30 |
Transport of cement from mills to silos (To be incorporated after receipt of requisite inputs from SK Nayak)!!
Conveyance of wet flyash and gypsum to Cement mills
| Material Conveyed | Wet flyash / gypsum | |
| Capacity | tph | 140 tph |
| Particle size | mm | Powdery lumps max 100 |
| Bulk density | t/m3 | 0,8 |
| Moisture content | % | 25 |
| Conveyor length | m | ~60 (horiz) |
| Lift | m | 20.4 |
| No of vertical curves | Two vertical | |
| Belt width | mm | 600 |
| Nominal pipe dia | mm | 150 |
| Nominal belt speed | m/s | 3.2 |
| Belt type | EP, 3 ply fabric | |
| Strength | kN/m | 315 |
| Cover thickness | mm | 5/3 ( top, bottom) |
| Carrying side idlers | mm | 127 dia, 6 rolls arranged hexagonally |
| Return side idlers | mm | 127 dia, 6 and 3 alternatively |
| Idler spacing | m | 0.53 2,0 |
| Drive motor | kW | 30 |
It is important to note that earlier a deep pan conveyor was used to transport clinker as well as well as the very wet and sticky gypsum and flyash resulting in cumbersome cleaning and maintenance difficulties.
In this installation, the pipe conveyor finds its application in conveying difficult materials with high moisture content.
Resulting from the ability of pipe conveyors to handle difficult materials, the relative ease in accommodating single conveyors within layouts of existing plants, power savings vis a vis pneumatic means of conveyance of fine powders, ease of operation and maintenance pipe conveyors shall continue to find its main application within the cement industry as has been brought out statistically worldwide.