Mechanical conveyors selection and operation pdf
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- Mechanical Conveyors: Selection and Operation
- Belt Conveyors for Bulk Materials Published by the Conveyor Equipment Manufacturers Association
For companies entering the market for mechanical conveyor systems — and even companies that already have them, planning, designing and building these systems can often seem overwhelming. There are certainly many variables to consider, especially when a poorly designed and executed system will cause frustration and loss of time, money and production long after the installation team has left. Careful planning is necessary to maximize the benefits of any conveyor system.
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Device can be adjusted for proportioned discharge to several places. Lowering with regenerative load. Lowering without regenerative load. Horizontal belt conveyor. Counterweight and cables not shown. Material class description. K1-Lump adjustment factor. Average weight lbs of troughing idler rotating parts-steel rolls. Average weight lbs of return idler rotating parts-steel rolls. WK 2 lb-in 2 average for three equal-roll troughing idlers.
Skirtboard friction factor, C s. Wrap factor, C w Rubber-surfaced belt. Wrap limits. Recommended belt sag percentages for various full load conditions.
Final tensions, full and reduced friction. Mechanical efficiencies of speed reduction mechanisms. Backstop and brake recommendations.
Some materials used in belting reinforcement belt carcass. Estimated maximum impact rating multi-or reduced-ply belts in footpounds Joules. Lump weight factor in pounds. Recommended pulley face width and belt clearances. Typical ratings for multi-or reduced-ply conveyor elevator rubber belting. Typical ratings for straight warp conveyor or elevator rubber belting.
Typical ratings for pvc solid woven conveyor and elevator belting Table A. Typical ratings for pvc solid woven conveyor and elevator belting Table B. Ordinate distances of points on concave vertical curves. Trough angle of the carrying idlers. Minimum bend pulley diameter. It offers information on numerous examples of modern high-performance and complex systems and includes suggestions and guidelines for economic evaluations and conclusions. In this Fifth Edition, the presentation of belt conveyor design technology and engineering data has been updated both in its technology and in its presentation.
The technical information contained in this book is generally conservative in nature. Variations in specific application requirements or extreme service requirements should be addressed by member company engineering personnel whose depth of experience exceeds that covered in this text.
This book is primarily a design manual, but Chapter 1 is included to acquaint the reader with the many uses of belt conveyors and their advantages under widely varying conditions of operation. Belt conveyors have attained a dominant position in transporting bulk materials due to such inherent advantages as their economy and safety of operation, reliability, versatility, and practically unlimited range of capacities.
In addition, they are suitable for performing numerous processing functions in connection with their normal purpose of providing a continuous flow of material between operations.
Recently, their conformity to environmental requirements has provided a further incentive for selection of belt conveyors over other means of transportation.
Low labor and low energy requirements are fundamental with belt conveyors as compared with other means of transportation. The dramatic increase in these operating costs since the oil crisis of the seventies has placed conveyors in an extremely favorable position for applications that were not considered previously. Belt conveyor manufacturers have consistently anticipated the needs of industry with improvements in designs and with components that have exceeded all known requirements.
Reliability and safety are outstanding now that stronger and more durable belts are available, as well as greatly improved mechanical parts and highly sophisticated electrical controls and safety devices. Also included are examples of relatively long-distance belt conveyor systems which are being used extensively because they combine such important benefits as reliability, safety, and low cost per ton of material transported.
Conveying of a Variety of MaterialsThe size of materials that can be conveyed is limited by the width of the belt. Materials can range from very fine, dusty chemicals to large, lumpy ore, stone, coal or pulpwood logs. See Figure 1. Closely sized or friable materials are carried with minimum degradation.
Because rubber belts are highly resistant to corrosion and abrasion, maintenance costs are comparatively low when handling highly corrosive materials or those that are extremely abrasive, such as alumina and sinter. Materials that might cause sticking or packing if transported by other means are often handled successfully on belt conveyors.
Even such hot materials as foundry shakeout sand, coke, sinter, and iron ore pellets are conveyed successfully. Wide Range of CapacitiesCurrent available belt conveyors are capable of handling hourly capacities in excess of any practical requirement. Yet they are also used economically in plants for transporting materials between process units at a wide range of rates -sometimes as little as a mere dribble.
Belt conveyors operate continuously -around the clock and around the calendar when required -without loss of time for loading and unloading or empty return trips.
Scheduling and dispatching are unnecessary as the material is loaded to and unloaded from the belt conveyor automatically. Operating labor costs differ little, regardless of capacity ratings. Overall costs per ton decrease dramatically, however, as annual tonnage handled increases. Such economic considerations are illustrated later in this chapter. For these reasons, belt conveyors are capable of handling tonnages of bulk materials that would be more costly and often impractical to transport by other means.
Adaptability to Path of TravelBelt conveyor systems provide the means of transporting materials via the shortest distance between the required loading and unloading points. They can follow existing terrain on grades of 30 to 35 percent, compared with the 6 to 8 percent effective limits for truck haulage. See Paths of travel can be quite flexible, and the length of the routes can be extended repeatedly, as required.
In some open-pit mining operations, conveyors thousands of feet long are shifted laterally on the bench to follow the progress of excavation at the face. Technology has advanced substantially in the design and application of horizontally curved belt conveyors. As a conveyor's total length increases, so does the probability that transfer stations will be required to avoid some obstacle in its straight line path. Horizontal curves eliminate the constraints of the straight line conveyor and reduce the installed and operating cost of the conveyor Figure 1.
Horizontally curved conveyors use conventionally troughed conveyor belts and standard components. The loaded and empty belt passes through the carry and return runs of the horizontal curve in unconstrained equilibrium by super-elevating the idlers. Curved conveyors further enhance the reliability, availability and environmental advantages of the standard belt conveyor by eliminating the infrastructure and dust control requirements at transfer stations.
Cleats are available in various sizes, shapes and configurations with most allowing the belt to run in either a troughed or flat position. Cleated belts are usually restricted to short conveyors where few or no return idlers are needed and either the material does not stick to the surface or where the carryback is acceptable. To improve on the cleat approach, corrugated sidewalls can be added to the transverse cleated belt to form complete rectangular partitions.
These sidewalls and a transverse rigid belt carcass allow it to run flat without troughing idlers. The sidewalls also increase the load carrying capacity over the "cleat only" design and allows conveying up to 90 degree inclines. One family of conveyors known as "pipe" or "tube" conveyors, "fold" belts, and "suspended" belts totally encloses the material with the belt increasing the allowable angle of incline.
In each case, the internal area of the enclosed belt is fixed, and therefore is capable of transporting material up steeper inclines only if the internal area is completely loaded with material.
At a steep angle these conveyors are unable to completely unload the trailing end of a load when no additional material is coming along to "push" the load up. Another family using the sandwich belt principle totally encloses the material and applies pressure to secure it. This insures that neither sliding or rollback will occur, even when conveying vertically. Systems are available that use only standard conveyor belts and components and therefore have high availability and low maintenance.
These systems permit high belt speeds resulting in high capacity capabilities. Consult with the respective CEMA member manufacturers of steep angle belt conveyors for more information and specific applications. Loading, Discharging, and Stockpiling CapabilitiesBelt conveyors are very flexible in their capabilities for receiving material from one or more locations and for delivering it to points or areas, as required by plant flow sheets.
They can provide the main transportation artery while being loaded at several points Belt conveyors, with their stackers and reclaimers, have become the only practical means for large-scale stockpiling and reclaiming of such bulk materials as coal, ore, woodchips, and taconite pellets.
See Unloading capacities of such systems are usually greater than those of several grab bucket unloaders, requiring less turnaround time and lower labor and other operating costs. In contrast with the above-mentioned highcapacity unloading systems, certain materials, such as foundry sand, can be plowed from the belts Figure 1.
Process FunctionsAlthough belt conveyors are generally used to transport and distribute materials, they are also used with auxiliary equipment for performing numerous functions during various stages of processing. A high degree of blending is accomplished as materials are bedded into and reclaimed from stockpiles.
Accurate samples of the material conveyed can be obtained by devices which cut through the stream of material as it flows from one conveyor to the next.
Magnetic objects can be removed from the material Figure 1. While being Figure 1. In many cases, such operations are not only performed more effectively in connection with belt conveyors but are the only practical means.
Mechanical Conveyors: Selection and Operation
Contents Conveyor Solutions The vital role of conveyor systems 8 Conveyor Solutions you can count on 9 Common Conveyor challenges 11 Health, safety and environment Cleaners - Primary and secondary 19 Light, medium or heavy? The information contained in this handbook has the potential to transform your operations — to increase the safety, productivity and ultimately the profitability of your business. Ready to go? There are three chapters: accessories, belts and components. Supporting information is placed next to the relevant product section.
Belt Conveyors for Bulk Materials Published by the Conveyor Equipment Manufacturers Association
Summary quently, greatly improved design methodologies. For these reasons it is relevant that the and conveyor belt interaction are highlig ted. Introduction uous modes of transport, the results being as indicated in Fig.
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