March 30, 2015

30/03/2015: Grain conveyors: examining this important piece of equipment

by Mike Spillum, Hi Roller, US

First published in Milling and Grain, February 2015

Hi Roller Conveyors, Sioux Falls, South Dakota, specialises in the design and manufacturing of enclosed belt conveyors for grain and grain by-products. 
     

http://issuu.com/gfmt/docs/mag1502_w1/46

It is well known that grain dust is very dangerous. Not only is it a health hazard for workers, it is also a serious explosion hazard. Even with this knowledge, tragedies occur yearly resulting in down time, property damage, injuries, and even deaths. Although there are many methods of conveying grain, open belt conveyors had historically been the primary choice for moving large volumes or for conveying long distances. Alternative enclosed methods such as chain conveyors or screw conveyors have limitations in regards to length and capacities due to power consumption and other design constraints.

Outweighing the advantages of open belt conveyors are the many negatives. They can be messy.  Although the majority of outdoor installations include covers, they are still exposed to wind and the elements resulting in dust clouds and spillage. Indoor installations create a health and safety hazard if dust is not contained. The cost of proper dust collection equipment and associated maintenance can be high.  Product spillage results in lost profits and requires additional employees to perform clean up. While cleaning around open belt conveyors, employees are exposed to the hazardous dust and can become injured working around moving parts.

As a contractor serving the grain industry in the 1970’s, Hi Roller’s founder felt that there had to be a cleaner, safer, more efficient way to convey grain. Numerous attempts had been made to enclose conventional open belt conveyors. Companies were utilising standard conveyor components and cumbersome reloading designs to address product spillage issues. Enclosures were being built around standard conveyor idlers. Product would build up on idler brackets and other ledges.  While containing dust within the enclosure, they were exposing the explosive grain dust to the idler bearings.  A failed bearing can create heat or a spark resulting in a fire or an explosion.
  

http://issuu.com/gfmt/docs/mag1502_w1/46

The return side of the conveyor belt slid on a steel pan rather than rollers. Grain that fell to the bottom of the enclosure was conveyed to the tail end of the conveyor. The reloading of product at the tail section was attempted by utilising “loop conveyors” which incorporated chains, paddles and multiple gearboxes.  If any of these items failed, product could build up which again created a maintenance or explosion hazard.

The original Hi Roller design was developed nearly 40 years ago and continues to be the standard of the industry for the clean, safe conveying of bulk materials. The Hi Roller was designed with some primary goals in mind.

First, it needed to be totally enclosed. Second, there were to be no internal brackets or ledges that would allow product to build up. Third, it needed to be self-cleaning and self-reloading. Fourth and most importantly, there could be no bearings exposed to the internal atmosphere of the conveyor. In order to accomplish all of the above, innovate conveyor components needed to be used.
  
http://issuu.com/gfmt/docs/mag1502_w1/46

The Hi Roller conveyor utilises a spool-shaped idler to support the conveyor belt in a troughed configuration.  A heavy pipe runs through the center of the idler providing its support. Inserted in to either end of the pipe is a stub shaft. The stub shafts protrude through the sides of the enclosure and attach to externally mounted bearings. This design keeps the bearings away from the dust and eliminates any internal idler support brackets that would allow dust build-up.

The conveyor belt returns on an antistatic UHMW return liner.  The return liner has a low coefficient of friction so that power requirements are not increased significantly versus return rollers. A bottom enclosure cannot simply be installed under standard return rollers. Product would build up on the pan and eventually prevent return rollers from rotating.  The slide return is a crucial feature for enclosed belt conveyors.

Dust and spilled product fall on to the return side of the belt and is conveyed to the infeed or tail section of the conveyor. Dust that clings to the carrying surface of the belt is swept to the same area by a row of wiper cleats that are attached to the carrying surface of the belt. With every belt revolution the wiper cleats continually clean the UHMW return liner, preventing product build-up.

Once at the tail section, product is automatically reloaded back on to the carrying surface of the belt. This is accomplished by the use of a reloading tail pulley, developed and patented by Hi Roller. Material is diverted to the outer edges of the tail pulley which has “reloading flippers” attached. As the pulley rotates, material is picked up and thrown against a stationary deflector, which directs material back on to the belt.
    
http://issuu.com/gfmt/docs/mag1502_w1/46

Today, Hi Roller offers a variety of conveyor styles to handle capacities ranging from 50 to 3800 metric ton per hour of grain.  The original “Hi Roller” model uses a spool shaped idler design as previously described. The patented “Hi Life” model utilises 3 idlers that rotate independently of each other. While resembling the profile of a conventional open belt conveyor idler, all bearings are isolated from the internal atmosphere of the conveyor. The idler is completely supported by the conveyor sidewalls eliminating any internal support brackets. The Hi Life idler design provides a deeper trough and longer idler and belt life.

Hi Roller conveyors are commonly used within tunnels for unloading various types of storage structures. They are also used under truck receiving pits and incorporate multiple opening control gates often referred to as ladder gates.  Seldom will you find an open belt conveyor in such applications for the many reasons described previously.

Other uses include processing plant feed conveyors due to their 24/7 usage. Storage silos are filled by utilising cascading enclosed belt conveyors with built-in 2-way discharge valves.  A single enclosed belt conveyor can accomplish the same utilising stationary intermediate discharge trippers. High capacity enclosed belt conveyors are also used to fill rail cars, barges, and ships.  Hi Roller has worked jointly with multiple ship loader suppliers to incorporate enclosed belts into their systems.

While many grain operations are similar, they all incorporate various design challenges.  Hi Roller prides itself on customising features to meet a specific application. Hi Roller’s design team provides approval drawings with each sale and works jointly with the customer to assure the proper design and installation of the conveyor. Conveyor inlets and discharges are customised as needed to match up to the customer’s other equipment.  Complimentary equipment such as control gates, support legs, and safety devices are incorporated as needed.

Hi Roller has discovered this communication to be an invaluable source of ideas and information. Improvements on the life and maintenance of the conveyor belts are often considered a joint venture with clients. Changes are made to adapt to the customer’s existing parameters.  Other manufacturers often expect the customer to adapt the company’s standards. Hi Roller’s consistent effort to integrate the needs of the customer into the design process has proven beneficial to both parties.  This willingness to veer from their standard features is the key to developing a strong following.

Hi Roller is amidst construction of a new facility in Sioux Falls, South Dakota. It will house Hi Roller’s headquarters including all office and manufacturing functions. The new facility will include a powder coat paint line, state-of-the-art manufacturing equipment and space for future growth. The anticipated completion date is the summer of 2015.

Hi Roller conveyors are in use worldwide. Hi Roller (www.hiroller.com) is owned by Canadian-based Ag Growth International (www.aggrowth.com), which offers a full catalog of storage and handling solutions. AGI has 11 manufacturing facilities in Canada, the US, the United Kingdom and Finland. 

mikes@hiroller.com
 

Read the magazine HERE.
 

The Global Miller
This blog is maintained by The Global Miller staff and is supported by the magazine GFMT
which is published by Perendale Publishers Limited.


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5 comments:

  1. This blog is very interesting with allot of new information and knowledge.
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    ReplyDelete
  2. An Apron conveyor is a type of conveyor made from individual apron plates that are linked together with hinges on its underside, thus creating a looped carrying surface where materials can be placed. Apron Conveyors are used to carry materials and pieces horizontally and inclined lines. Neoconveyors.com offers Apron conveyors, which are made of pans with uneven edges to keep a check on material loss.

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  3. Belt Conveyors, are specially designed to leverage the open frame and trough effect of the rubber belt to fully contain the load of materials. This type of conveyor is often used for assembly line operations, sorting, trash handling, inspection or packing operations. bulkmaterialshandling.in is the leading Belt conveyor manufacturer in India.

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  4. Thanks for sharing the list we are a Dhanvanthri Engineers Pvt Ltd agency based in Mumbai.
    Material Handling Equipments

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