As a pioneer in the Bulk Materials Handling Industry, The Hendrik Group, Inc. provides custom designed solutions to bulk materials handling applications.
HoverGlide™ air supported belt conveyors (asbc) use meticulously calibrated air chambers to support conveyor belts carrying bulk materials with fewer friction oriented components than vintage roller conveyors.
These conveyors utilize a thin cushion of air (film) rather than idlers to support the belt and load. Use of this air film reduces friction between the tail section and discharge thus reducing dust emissions and, of course, maintenance. This reduction in friction, dust emissions and maintenance can be translated into an annual savings of as much as $40,000 to $50,000 in housekeeping, parts replacement and energy costs. Installation savings may also be realized since walkways along the conveyors are not needed and enclosed galleries are not required. Conveyor support spacing ranges from 20-40 feet depending on the width.
In the following we present some FAQs which help to understand this conveying principle:
Q. Do you use compressed air?
A. No. Air is supplied through a low pressure, low volume, centrifugal fan.
Q. How much air is used?
A. This depends on the width of the conveyor, weight of the belt and the handling capacity.
We calculate the belt weight and load to determine the volume and pressure. An average volume is from 3-8 CFM per linear foot at pressures from 12-30 inches of water. 95% of all conveyors require less than one (1) PSI, (27.7 inches of water.
Q. How is the air distributed?
A. The fan, preferably located at the center of the conveyor, blows air into the plenum air chamber. Through a series of holes placed along the centerline of the conveyor, air is forced between the plenum bed plate and belt, forming a film of air. If necessary, the fan may be placed near the tail or head of the conveyor.
Q. May the air be recycled?
A. Yes. This may be done as long as the conveyor is totally enclosed. Air escapes between the plenum plate and belt for the entire length of the conveyor. This air may be captured at the discharge and/or loading areas. Depending on the dust generations, this air may be directed back to the fan through intake filters other than those supplied as standards.
Q. Is there a limit to the conveyor length?
A. Not really. Due to pressure drops in the plenums, we suggest placing a fan every 650-700 feet. However, we can supply one fan for up to 1000 feet, depending on the width of the conveyor, material handled and the handling capacity.
Q. What prevents the holes in the plenum from plugging?
A. When the conveyor is in operation, air is forced between the plenum bed plate and belt, which escapes along the belt edges. This creates a positive seal against dust and material from entering between the plenum bed plate and belt. When the conveyor is not operating, the belt lies in the trough and seals the holes.
Q. Will the conveyor operate without air?
A. If the conveyor is short enough, probably. It would act as a slider bed conveyor.
However, the fan is interlocked with the conveyor motor. When the conveyor is started, the fan is activated first. Through an adjustable pressure switch, the conveyor drive is started once the plenum pressure is reached.
Q. Are covers needed for operation?
A. No. We do recommend at least covering the first 20-30 feet at the loading point to reduce dust generations.
Q. If the conveyor is not covered, will rain water enter the plenum sections?
A. Yes, there may be seepage between the belt and plenum bed plate. We generally provide a bleeding valve at the tail end of the conveyor. If the conveyor is operating in a cold climate and not covered, we recommend keeping the blower on and possibly a creep drive to keep the conveyor running in low temperatures.
Q. Will the conveyor operate in extreme temperatures?
A. Yes. We have furnished several conveyors where we designed to a low temperature of minus 30º C. At one installation we incorporated duct heaters to keep the belt flexible. However, these heaters are not really used. When the temperature reaches minus 10º C, the blower and creep drive are actuated through a preset thermostat.
Q. Is there a limit to handling capacity?
A. No. We manufacture conveyors with belt widths from 12" to 72" wide. The cross section on the belt is equal to a 45º troughing idler. The trough is a concave curve which eliminates the belt cover from cracking at the pinch points, which is experienced in conventional 45º idler conveyors. The belt sag between idler rolls is also eliminated. The belt is supported for its entire troughing length, which eliminates idler bumping. On idler conveyors, the bumping causes material to be thrown up every time it goes over an idler, thus causing dust generations, product separation and degradation.
Q. Can the HoverGlideTM be reversing?
A. Yes. Several reversing conveyors are in operation. Special attention has to be given to the take-up area in reverse mode.
Q. Are there any belt training problems?
A. On most conveyors, the shortest ones are harder to train. We incorporate crowned head and tail pulleys to help in the training. We have not experienced training problems on any conveyor longer than 100 feet (30 meters). One of the most important aspects of our design is to centrally load the conveyor. We design the load point and belt loader based on the conditions provided by the client.
Q. Can the conveyor have vertical curves?
A. Absolutely. There are many HoverGlide air supported belt conveyors in operation where the conveyor is loaded on the horizontal, curving up to the discharge.
Q. Can the HoverGlideTM be loaded on an incline?
A. Yes. Most of our installations include conveyors with inclined loading sections. Our standard loaders are designed with rear skirting to prevent any fall or roll back, and side skirting to prevent any materials from "boiling " over the belt edge.
Q. Is there any wear on the plenum beds?
A. Not that we are aware of. Based on feed back from our clients and their maintenance personnel, none of the paint coatings show any wear, even after years of operation.
Q. Will the conveyor start under loaded conditions?
A. We design all our conveyors to start under full load. We base starting conditions on CEMA's recommendations of twice friction plus lift.
Q. What about longevity?
A. There is an installation of (4) 60" wide conveyors at Sorrel, Quebec which has been in operating since 1984. Based on maintenance records, no belts, drives, pulleys, etc. have ever been changed. These conveyors operate year round in a very cold climate. There are (6) conveyors operating at a quarry near Bangor, Maine that were installed in 1985. They do change the belts every 6-7 years and have just replaced their first fan. Many of the European facilities have been operating since the early 1970s.
Q. Does material build up beneath the belt?
A. No. There is constant pressure released between the belt and plenum bed plate providing an air seal. If the conveyor is turned off, the belt seals the holes.
Q. What protection do you use to avoid corrosion?
A. Our standard protection is powder coating with a zinc rich epoxy primer coat and a urethane top coat. This system is resistant to all climates and has been tested to 4000+ hours of continuous salt
Air Supported Belt Conveyors
Air Supported Belt Conveyors
As a pioneer in the Bulk Materials Handling Industry, The Hendrik Group, Inc. provides custom designed solutions to bulk materials handling applications.
HoverGlide™ air supported belt conveyors (asbc) use meticulously calibrated air chambers to support conveyor belts carrying bulk materials with fewer friction oriented components than vintage roller conveyors.
These conveyors utilize a thin cushion of air (film) rather than idlers to support the belt and load. Use of this air film reduces friction between the tail section and discharge thus reducing dust emissions and, of course, maintenance. This reduction in friction, dust emissions and maintenance can be translated into an annual savings of as much as $40,000 to $50,000 in housekeeping, parts replacement and energy costs. Installation savings may also be realized since walkways along the conveyors are not needed and enclosed galleries are not required. Conveyor support spacing ranges from 20-40 feet depending on the width.
In the following we present some FAQs which help to understand this conveying principle:
Q. Do you use compressed air?
A. No. Air is supplied through a low pressure, low volume, centrifugal fan.
Q. How much air is used?
A. This depends on the width of the conveyor, weight of the belt and the handling capacity.
We calculate the belt weight and load to determine the volume and pressure. An average volume is from 3-8 CFM per linear foot at pressures from 12-30 inches of water. 95% of all conveyors require less than one (1) PSI, (27.7 inches of water.
Q. How is the air distributed?
A. The fan, preferably located at the center of the conveyor, blows air into the plenum air chamber. Through a series of holes placed along the centerline of the conveyor, air is forced between the plenum bed plate and belt, forming a film of air. If necessary, the fan may be placed near the tail or head of the conveyor.
Q. May the air be recycled?
A. Yes. This may be done as long as the conveyor is totally enclosed. Air escapes between the plenum plate and belt for the entire length of the conveyor. This air may be captured at the discharge and/or loading areas. Depending on the dust generations, this air may be directed back to the fan through intake filters other than those supplied as standards.
Q. Is there a limit to the conveyor length?
A. Not really. Due to pressure drops in the plenums, we suggest placing a fan every 650-700 feet. However, we can supply one fan for up to 1000 feet, depending on the width of the conveyor, material handled and the handling capacity.
Q. What prevents the holes in the plenum from plugging?
A. When the conveyor is in operation, air is forced between the plenum bed plate and belt, which escapes along the belt edges. This creates a positive seal against dust and material from entering between the plenum bed plate and belt. When the conveyor is not operating, the belt lies in the trough and seals the holes.
Q. Will the conveyor operate without air?
A. If the conveyor is short enough, probably. It would act as a slider bed conveyor.
However, the fan is interlocked with the conveyor motor. When the conveyor is started, the fan is activated first. Through an adjustable pressure switch, the conveyor drive is started once the plenum pressure is reached.
Q. Are covers needed for operation?
A. No. We do recommend at least covering the first 20-30 feet at the loading point to reduce dust generations.
Q. If the conveyor is not covered, will rain water enter the plenum sections?
A. Yes, there may be seepage between the belt and plenum bed plate. We generally provide a bleeding valve at the tail end of the conveyor. If the conveyor is operating in a cold climate and not covered, we recommend keeping the blower on and possibly a creep drive to keep the conveyor running in low temperatures.
Q. Will the conveyor operate in extreme temperatures?
A. Yes. We have furnished several conveyors where we designed to a low temperature of minus 30º C. At one installation we incorporated duct heaters to keep the belt flexible. However, these heaters are not really used. When the temperature reaches minus 10º C, the blower and creep drive are actuated through a preset thermostat.
Q. Is there a limit to handling capacity?
A. No. We manufacture conveyors with belt widths from 12" to 72" wide. The cross section on the belt is equal to a 45º troughing idler. The trough is a concave curve which eliminates the belt cover from cracking at the pinch points, which is experienced in conventional 45º idler conveyors. The belt sag between idler rolls is also eliminated. The belt is supported for its entire troughing length, which eliminates idler bumping. On idler conveyors, the bumping causes material to be thrown up every time it goes over an idler, thus causing dust generations, product separation and degradation.
Q. Can the HoverGlideTM be reversing?
A. Yes. Several reversing conveyors are in operation. Special attention has to be given to the take-up area in reverse mode.
Q. Are there any belt training problems?
A. On most conveyors, the shortest ones are harder to train. We incorporate crowned head and tail pulleys to help in the training. We have not experienced training problems on any conveyor longer than 100 feet (30 meters). One of the most important aspects of our design is to centrally load the conveyor. We design the load point and belt loader based on the conditions provided by the client.
Q. Can the conveyor have vertical curves?
A. Absolutely. There are many HoverGlide air supported belt conveyors in operation where the conveyor is loaded on the horizontal, curving up to the discharge.
Q. Can the HoverGlideTM be loaded on an incline?
A. Yes. Most of our installations include conveyors with inclined loading sections. Our standard loaders are designed with rear skirting to prevent any fall or roll back, and side skirting to prevent any materials from "boiling " over the belt edge.
Q. Is there any wear on the plenum beds?
A. Not that we are aware of. Based on feed back from our clients and their maintenance personnel, none of the paint coatings show any wear, even after years of operation.
Q. Will the conveyor start under loaded conditions?
A. We design all our conveyors to start under full load. We base starting conditions on CEMA's recommendations of twice friction plus lift.
Q. What about longevity?
A. There is an installation of (4) 60" wide conveyors at Sorrel, Quebec which has been in operating since 1984. Based on maintenance records, no belts, drives, pulleys, etc. have ever been changed. These conveyors operate year round in a very cold climate. There are (6) conveyors operating at a quarry near Bangor, Maine that were installed in 1985. They do change the belts every 6-7 years and have just replaced their first fan. Many of the European facilities have been operating since the early 1970s.
Q. Does material build up beneath the belt?
A. No. There is constant pressure released between the belt and plenum bed plate providing an air seal. If the conveyor is turned off, the belt seals the holes.
Q. What protection do you use to avoid corrosion?
A. Our standard protection is powder coating with a zinc rich epoxy primer coat and a urethane top coat. This system is resistant to all climates and has been tested to 4000+ hours of continuous salt
sprays.
For more information, please visit:
https://edir.bulk-online.com/oldedirredirect/20399.htm
http://www.google.com/search?client=...UTF-8&oe=UTF-8
http://www.thehendrikgroup.com/pdf/thg.pdf
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