Graham Spriggs is a proponent of air supported conveyance. I imagine it is selective in relation to suitable products. Over long distances there would have to be instumentation to monitor the airflow balance...which isn't too difficult and would eliminate idler replacements.

As far as I know there is no Standard for these machines which means that in this age of litigation you would really need someone of Mr Spriggs' calibre to confidently undertake the design. ■

Conveyor Dynamics, Inc. (CDI) was commissioned by a small firm to solve and encode into BELTSTAT the air supported conveyor many years ago. A version of this solver was then sold Martin Engineering, who publish its virtues:

http://www.martin-eng.com/products/m...onveyor-system

We evaluated its advantages upon development completion and found the claimed advantages to be marginal when all losses are considered. A conventional conveyor has more moving parts, but does not require more power when all losses are considered and today's technology is applied.

As noted, there is no standard. The necessary computational fluid dynamics modeling has probably made the analytic method less approachable than a CEMA or DIN simple friction solution for conventional trough conveyors. ■

I had a passing brush with these conveyors many years ago. I don't recall any particular problems except at feed points where the belt would wander off line according to the feed arrangement.

I remember some vertical plates being added that projected into the load to help stabilise the belt. ■

I have seen this work well if the belt is being center loaded. There are two large ones I am familiar with handling coal. Once loading issues were cleared up, it has worked fine. ■

Hi there Ivanco..

Indeed I have had good experience with air supported conveyors, and have used them on coal, sticky fibrous bagasse left over from sugar cane and so on.

I have done concave ones as well as straight ones, but all of them have been in-plant as opposed to long overland type conveyors.

Our supplier here in South Africa seemed to fizzled out, probably due to patent squabbles.

This was a pity as I would liked to have put in some longer ones.

Since the only moving part on the carry side is the belt, the clients like them, as do I because they don't cost much, and they go a bit steeper than conveyors with rollers.

For longer ones we have to ensure that the belt maintains tension at all times especially when coasting fully loaded.

When you turn off the air, the belt sits on the plenum i.e. no run back. (How safe can you get?)

Key aspects are:

- Plenum pressure

- Diameter of the air holes on centre-line of air plenum supporting the belt, and

- Air hole spacing

Dramatically reduced carry friction is offset to an extent, by the blower power requirements, but I look forward to using them again, in what is left of my sheltered life..

Cheers

LSL Tekpro ■

Ivanco,

If you are interested, contact us at The Hendrik Group and we will be more than happy to give you many applications that you may contact and talk to directly. THG has a vast amount of clients with many different materials being handled with air supported belt conveyors. Sizes from 18" to 60" (72" in the testing stage) and lengths exceeding 1000', with air supporting the belt on the return as well as the carrying side.

We will also be happy to answer your questions and concerns about ASBC technology.

Best Regards,

Rik Hartsuiker

The Hendrik Group, Inc.

973-616-9060

www.thehendrikgroup.com ■

Hi Rik

I enjoyed your website, and was interested to see you run the return belt on air as well.

Are there any considerations regarding the cleanliness of the return belt when you do this?

Have you discovered any limitations with ASBC systems?

Cheers

LSL Tekpro ■

Thanks Graham. To answer your question, an air return is not always applicable, but on dry or mostly dry materials can be beneficial. We incorporate at least a primary and secondary belt cleaner and in most cases, a tertiary cleaner like a rotary brush or an air knife. This works very well on coal, grains, clinker, etc. Materials like sugar, sludge or anything that is sticky or wet, we use an idler return. But if you can take ALL the moving parts out of the conveyor between the head and tail, the maintenance costs are substantially lowered. As far as limitations with ASBC systems, The Hendrik Group has been very innovative. We have provided just about every type of belt conveyor profile (shuttles, booms, stackers, feeders, cascading, convex and concave curves, sometimes on the same conveyor) except movable trippers and multiple discharges. We have supplied conveyors over 1000' long and handled 4800 STPH on a 60" wide belt, and we are presently designing a 72" version that will increase our handling capacities. BTW, we use a 45 degree trough so as to get 15-25% more cross sectional capacity. Thanks for your interest. ■

Very Good Rik...

How do you find the energy loss attributable to the blowers compares with the energy savings due to the reduced friction from the floating belt(s)?

(I have always wanted to put in a long overland with belt turn-overs with both belts floating on air.

What do you think...)

Cheers

LSL Tekpro ■

Good Day Graham,

Typically on straight, horizontal conveyors, no matter what the length, we can save about 15-20% of the overall HP for the conveyor...no big deal. On conveyors with lift, the drive HP is usually the same as on conventional idler types (gravity is what it is). THG does not really make notice of a HP savings when we are selling our conveyors. Most of the savings are in the reduction of overall maintenance. No moving parts between tail and discharge, no spills at the loading section because it is totally enclosed, less chance of carry back on the return side and lower workloads on dust collection systems are the biggies in the savings department. On overland conveyors, depending on the length and the roll of the land, HP may be actually generated on down hill slopes, but again this is not where the majority of the savings are realized.

If I may, I have a question for you. You mentioned that your local supplier fizzled out. I am interested in why because as far as I know, these folks were started by engineers from the original developer in the Netherlands. Do you have any insights? ■

Morning Rik..

I was asked about what happened to Lee Thane and his Aeroconveyors at Q&A time at the end of Beltcon 12 here in Johannesburg.

The answer was provided not by myelf, but as I remeber it, by Arnold Mattee of Batemans.

Maybe he will pick up this thread..otherwise I will try and contact him for you.

Cheers

LSL Tekpro ■

Hi Ryk...FYI

I received an e-mail from Louis Masurik of Aerobelt/Conveyquip including as follows..

"..I saw your comments on Bulk Online, regarding the existence of the air supported company in South Africa. Regretfully Aeroconveyor closed after the last of the two Brommels brothers died. The company was restarted under the old Dutch name Aerobelt, and most of the Aeroconveyor staff were employed by the new company. The original designer Lee Thain, is also a partner in the company. You may look at our website and see that we now hold several world firsts, in air supported belt conveying. We currently have agents in Brazil, Thailand, New Zealand and Australia..."

So..there you go..

Cheers

LSL Tekpro ■

Good Day Graham,

Thank you for the info and the history. I did not know what happened after the Dutch company fizzled. I went to Aerobelt's site...very interesting. Its good to know that some of the parent company still exists and that there are still professionals in the industry who know what they are doing.

Please let me know how else I may be of service. I have enjoyed our dialogue. ■

Hello there,

our client is interested in 2,000 m/long air belt with capacity of 2,000 MT. Is there any significant disadvantage/advantage in using air belt conveyor of this lenght/capacity in comparison with enclosed belt conveyor?

thanks! ■

Hi,

Magaldi Power Spa have a great experience on such type of conveyors, being in parthnership with Kawasaki Plant System, who provides the technology of the air supported conveyors that they call FDC, Flow Dynamics Conveyors.

They have hundreds of installation worldwide, mainly in Japan, of course, and we have already erected and commissioned one of them in an Italian refinery.

Actually Kawasaki is, to my knowledge, the most experienced supplier of such conveyors if we are talking of serious conveyors in the range of 3.000 t/h.

Regarding sticky materials and return side on air, this is not an issue, we provide both washing stations, blade scrapers and turn over stations, therefore the belt returns on the clean side.

How may we help you?

For more information, please wisit us at www.magaldi.com or contact my e-mail fabio.defeo@magaldi.com

Regards, Fabio ■

Greetings,

Configuring the air supply system for Air Supported Belt Conveyors is becomming easier. Using finite elements we finally have an application to simulate pressure drops along the system and belt deflections/air gap, to ensure that the system will met the requirements for different service conditions: https://desk.asbc-eng.com

Best Regards

Nuno Rocha ■

Conveyor Dynamics, Inc. (CDI) have designed a number of air supported conveyors and assisted in correcting problems on others. Two problems of special importance are:

1. Belt rubbing at the transition between straight to trough at the loading and discharge points. The belt is supported by transition rollers until it is supported by the tube chamber. The belt can rub on the tube entry point causing excessive belt wear that rubs all rubber cover off the belt. This then caused excessive leakage of air. Special care needs to be taken in this area as well as controlling pressure under the impact point at the loading station. We developed a finite element model to guide our designs at these trouble points.

2. Air chamber leakage between air support and internal product chamber can induce currents that suspend fine granular product into the product void space that is then carried into the fan discharge and filters. The filters become clogged up and require constant maintenance. CDI has developed a new seal concept to eliminate this troubling maintenance condition. ■

CDI also uses CFD modeling to properly design the air plenum, its sealing system, and air entry nozzles and placement for both carry and return strands. Many return strands are fitted with return rollers, where slight product carryback is not a problem. ■