High Angle Conveying, the Vital (missing) Link to IPCC Systems – 2017

Belt Conveyor Technology

High Angle Conveying, the Vital (missing) Link to IPCC Systems – 2017

Installations and recent studies have demonstrated the technical and economical advantages of high angle conveying for optimization of any IPCC system, yet that industry continues to struggle with the use of conventional solutions to achieve the high angle function.
(ed. WoMaMarcel - 07/4/2017)
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The “Chevron Mega-Pipe” Conveyor in Comparison

Prompted by the 2016 article “Pipe Conveying – the next Stage” (BSH 2/3 2016), against the above backdrop I now present a comparison of the Dos Santos Sandwich Belt high angle conveyor against the “Chevron Mega-Pipe” conveyor. Table 2 summarizes important points of this comparison. Most importantly the “Chevron Mega-Pipe” is a proposition at this point so that the comparison is that proposition against the long proven characteristics and features of the Dos Santos Sandwich Belt high angle conveyors.

Table 2: Comparison of Mega-Pipe vs Dos Santos Sandwich Belt.

Conveying Angle

Developers of the “Chevron Mega-Pipe” claim high conveying angles from 30° to 45°. Because of the material’s free surface we know that even if all dynamics are suppressed in the running “Mega-Pipe” the best incline angle that can be achieved approaches the material’s angle of repose. CEMA (Conveyor Equipment Manufacturer’s Association) lists angles of repose for most materials from 10° to 39°. Only fibrous intertwining materials such as woodchips, bagasse, etc have angles of repose exceeding 40°. To approach such incline angles the Chevron Mega-Pipe uses high profiled cleats that eliminate the material to belt surface sliding interface and crowd the material between the walls (vertical belt surfaces) of the pipe belt. This is a high price to pay as the former precludes the possibility of scraping the pipe belt clean while the latter is largely the reason why pipe conveyors have increased belt travel resistances and require significantly increased power. Dos Santos Sandwich Belt high angle conveyors always apply a continuous hugging pressure onto the material and can convey at any angle up to 90°. Furthermore power requirements are like any single flight conventional elevating conveyor, only modestly higher than the useful work requirement.

Belt Width, Design Rate and Lump Size

The belt width, capacity and lump size comparison is best illustrated in Fig. 17. This shows, to a common scale, the cross-section of the “Mega-Pipe” carrying strand as well as two carrying cross-sections each of Dos Santos Sandwich Belts of 2600 mm belt width and 2400 mm belt width respectively.

Fig. 17: To-scale cross-section, “Chevron Mega-Pipe”, two comparable Dos Santos Sandwich belts.

The two sandwich belt cross-sections are taken at the transition curve and at the straight GPS incline. The former tends to set the design rate and the recommended material size. For the 3000 mm belt width “Mega-Pipe” I assumed a 30 mm belt thickness, likely an understatement, especially if the chevron cleats are considered. The design material area at 60% filling (as recommended by CEMA for coarse materials) is 327.400 mm2. By comparison, for operation at 45° incline, a Dos Santos Sandwich Belt of 2600 mm belt width exceeds this at 350 700 mm2 while a sandwich unit of 2400 mm belt width has a lesser material area of 297.500 mm2. Indeed our previously cited system of 2438 mm (96 in) belt width is nearly comparable in material area to the “Mega-Pipe”. Most interesting we have depicted three lumps of 350 mm size at the cross-sections. In the “Mega-Pipe” these must overlap to fit while at the Sandwich belts they line up easily across. Most importantly, they are confined within the rigid “Mega-Pipe” space while there are no rigid spaces within the Dos Santos Belt Sandwich. The sandwich has a floating belt surface that applies the engineered hugging pressure but is free to float on the material even to the point of severe overload. Other aspects worth noting – the “Mega-Pipe” loading skirts must be equally constraining at 840 mm width risking jamming of multiple lumps. By comparison the two sandwich belts depicted will have loading skirt width of BW/2, 1300 mm and 1200 mm respectively.

Terminal Transitions

A most important point of comparison, the end terminals, predicts in the “Mega-Pipe” an imposing system with limited flexibility and conformance to the general pit wall. The “Mega-Pipe” transitions from flat and wide at the end pulleys, to the formed pipe are at least 54 m long according to CEMA. With the additional length required to beat out and dislodge caked material, from the chevron cleats onto a collector belt, the head end terminal length goes up to 70 m. This compares with Sandwich Belt terminal transitions of less than 3 m.

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