For your bottom reclamation, check out General Kinematics VIBRA-FLOW Activator / Feeders. These units have been successfully utilized for bio-mass applications. The Vibra-Flow combines two feeders and a pile activator into a single, low-headroom unit, significantly reducing both tunnel width and height requirements. This reduction in tunnel size provides considerable cost savings during construction,while maintaining access for inspection and maintenance.



http://www.gkmining.com/proddesc.cfm/productid/77

Thank you,

Thomas Musschoot

General Kinematics Corp. ■

Originally Posted by Preben Messerschmidt

Wood chip storage and bottom reclaiming systems

DONG Energy is as a part of a large Utility Power Station project developing a wood chip unloading and storage facility.

The quay will need to unload approx. 5 million cubic meters (m3) per annum of wood chip, being delivered by Panamax vessel size, approx. 120.000 m3.

The wood chip will be stored in a high volume floor storage with a bottom reclaiming and discharge system. The storage and reclaiming shall be automated.

The storage will contain 400,000m3 and the maximum height of the stockpile will be 40 m. The rate of reclaiming will be approx 20,000 m3 per day.

We are interested to hear about experience with fully automated stacking and bottom reclamation systems, as well as experiense with stocking wood chips to such a height.

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You should visit the major burners of wood chips in the United states to examine how they handle wood chips

The problem with storing wood chips out of doors is they will freeze and be a source of fuel for spontaneous combustion.

Are both the stock pile and the steam to be located very near each other, or is the hog fuel to be transported X distance by a method yet to be finalised?

Have you examined the use of wood pellets for fuel rather than wood chips/hog fuel for the generating system?

The reason I ask is simply one of space wood pellets for fuel occupy much less space in shipping and storage and are simpler to store and transport but are also subject to

issues from moisture to some degree but not as much as wood chips/hog fuel.

The benefit of making pellets allows for uniform product size and ability to create heat with forced draft boilers.

less machinery will be required to move and transport pellets on the power station site as well.

5,000,000 cubic meters of wood chips is equivalent to 1,350,000 tons of wood pellets is equivalent to 6,750,000 cubic feet of wood pellets being

47-50 cubic feet per ton depending on wood species.

1,350,000 tons of wood pellets would require the use of 33,750 shipping containers transporting 40 tons per container annually, equaling 650 shipping containers per week.

and the shipping containers can be filled with wood chips in bulk form and then stored on the ground to avoid issues with stacking them filled.

The empties could be stacked per normal stacking rates etc.

each container would occupy 2261 square feet of area is stored one container high and 650 containers would occupy 1,500,000- rounded higher

using one acre as square area 650 containers would occupy 34 acres of flat ground one container high.

The clyde materials handling iso veyor can be another economical option for storage and transport with no added moisture to product with forty foot container that can be stacked and

transported as it has an exterior frame system surrounding the tank and the iso veyor can be equiped for vacuum service as well as it can be transported by rail or truck and handled

with container handling machinery and prt side cranes.

the containers can be leased or purchased etc. and can be stacked like shipping containers as the iso-veyor frame is what supports the the iso-veyor tank

The floor plan and foundation for the storage area would have to bee designed and built for weight of the iso-veyor and its cargo and it can be easily stacked with its design

and handled with a dedicated bridge crane for the filled and empty containers which would be moved from storage to fil a fuel bunker or silo and the empties returned to the out bound storage areas.

As the iso-veyor is a sealed container, the pellet quality can be maintained for the maximum heat value.

the pellets are loaded through top hatches and unloaded with vaccum service or pressure service depending upon the recommendation of InBulk technology for the material.

If the generating station is on the quay the iso veyor would lend it self very well to the use of a singke container bridge crane unloading the filled iso-veyors and returning with the empty ones

and the number of ships required would be cut in half annually.

The use of a 70,000 DWT Panamax vessel would allow simple shipping as container ship will be all that is required and also increase the number of dedicated transits with a fleet of containers.

But there is nothing to say a dedicated fleet of Iso- Veyors could not be filled on the quay in a dry loading area in a building to maintain the wood pellet quality and speed loading of the iso-veyor.

Or if a dedicated conveyor from the quay to the power station(if it is located near the quay) is possible as long as the conveyor has all weather covers.

A dome form Geometrica could be employed to strore the annual volume of wood pellets and contain a reclaim system with a mobile gathering arm loading system which is used by Morbark or a

vacuum system fed by a small wheel loader.

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A stock pile with a below grade reclaim will require a conveyor gallery, emergency stops, warning horns for start up, a belt drive unit and and electrical works rated for water proof installation,

water proof lighting, a dedicated communications link, an escape tube at the far end of the reclaim gallery and a dedicated ventilation system for entry.

The number of desired reclaim chute(s) has not been addressed and must be determined as well as chute operating methods and the installation of air cannons should be implemented with a smaller conveyor and chuite system as vibrators will pack materials if the openings for the draw down chutes are smaller than the width of the conveyor trough.

A single draw point will require an active method of drawing down material using a bar grizzly and wheel loader or smal dozer to maintain material flow.

As no specific stock pile design has been mentioned commenting is a moot point at this time as a conical, rectangular trapezoid, or square pile method has not been mentioned by the posting.

a simple conical or radial/conical/horse shoe stock pile could be implemeted using a bucket elevator feeding a material slinger to throw the wood chips a great distance for stock piling.

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A wood chip stock pile fed by conveyor and using a second conveyor for reclaim would benefit from above ground conveyors for simplicities sake;

The inbound conveyor would require all weather conveyor covers and be elevated unless it is simply feeding a very large radial stacking connveyor creating the pile;

but a bucket elevator feeding a material slinger on a tower with a winch to raise and lower the slinger will accomplish the same thing with less work as the stock pile will eventually

create its angle of repose of 30 degrees.

The safe reclaiming of material in a stock pile must be followed as personell can be killed and machinery buried in the event of a massive slide of material, as it is uncontrolled and restricted by

walls which reduce the stockpiles front profile. The smaller the area the less work required to reclaim the wood chips or wood pellets.

a simple passive hopper feeding a reclaim belt on the surface will be adequate for relaiming the wood chips.

lzaharis ■

Continuing with additonal comments with the wood chip thread.

If a rectangular stock pile design is chosen using a trapezoidal design is used to create the angle of repose of 20 degrees approximately.

A radial stacking conveyor and a hard surface asphault area for the stock yard would keep the wood chips clean and free of excess dirt.

Placing a coveyor gallery above ground would eliminate the need for a massive excavation where a possible soil mixing design cold be used to stabilise the soil

under the stock pile and the drawdown galllery avoiding sub surface burial of the conveyor gallery BUT all the same rules apply for an above ground gallery with regard to ventilation,

an escape tube, power for lighting and chute controls, compressed air lines for chutes with air cannons for each chute being the preferred method with smaller multiple chute galleries.

A battery of deluge guns would need to surround the stock pile in the event of a sponataneous combustion fire from heat build up or a lightning strike if the weather is very dry.

The other issue of exposed stock piles is the dust that is inherent with wood chips and dry weather aids in creating wood chips dust and fines.

a smaller system could be used to wet the pile down to keep its temperature at a stable level or the stock pile could be made into a battery of smaller stock piles which would be physically

separated to aid in inspection temperature monitoring and fire control allowing quick attack and cooling of hot spots if they begin to combust or in the event of a lightning strike.

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If wood pellets are considered as a method/source of heat energy they can be handled as previously described using an isoveyor system.

A silo for wood pellets does work but it has many of the same issues with lightning. the pellets would be easily reclaimed using an apron feeder rather than a screw or belt conveyor as it is a

much more powerfull method of product reclaim and only a very small narrow apron feeder of 24 inches in width would be required under the properly sized inverted cone of the pellet silo and

only a small number of air cannons would be required in the event of a minor plugging as the properly size opening diameter is nearly the width of the apron feeder in proper design as the

apron feeder would have skirt boards along both sides to prevent spillage. the degradation of the wood pellets would not be an issue as it is being reclaimed to be burned and not much of an

issue.

As wood pellets would be half the physical volume of the annual wood chip requirements it will require less storage space and work for each therm and could be transported in bulk by a

Panamax class vessel as is done currently from the United States to the European Union via the west to east transit of the panama canal and further east by the Panamax vessels.

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Placing the drawdown gallery above the ground and on the hard surface is a possibility but it would always have a sacrificed depth of wood chips on both side of the gallery with no guarantee

the gallery would not be damaged byy a dozer pushing wood chips by accident.

The sacrificial layer of wood chips would continue to degrade as more wood chips are added and would become a wet mess if not exposed and frozen during the reclaim of wood chips with a crawler dozer earth mover.

On this side of the pond high cube gondola railcarr specifically built for wood chip traffic are used in combination with rotary car dumpers at the generating station where the cars are weighed prior to dumping to verify the scaled weight for the specific car on the bill of lading which is carried by the trains conductor when the wood chips are delivered by the railroad which is delvering the carloads of wood chips

The wood chips are then conveyed to the end use which may be for power generation or the manufacture of chip board, oriented strand board, particle board or fiber board depending upon the plants specific product to be manufactured.

Some plants have belt conveyors to transport the hog fuel to the boilers and some use a dozer and or front end loader to fill a recieving hopper on the exterior of the generating station which

feeds the hog fuel to the boiler.

Some plants use positive displacement blowers with hundreds of feet of pipeline to move the wood chips from silos to the boiler end use etc.

Its something to think about as wood pellets are tolerating the Trans-Atlantic voyage very well for delivery to europe and the pellets would only require have the physical

space of bulk wood chips and if the iso veyor method is used storage and product quality would be maintained using the isovayors with the proper vacuum or pressurized

method of delivery requiring much less dedicated mobile machinery if a storage yard designed with shipping containers as the preferred method of storage where a large bridge crane designed

for shipping containers can be employed to recieve, store, transfer, unload, segregate and return empty containers for load out, load empty containers for return and reloading to begin the

cycle again to maintain supply of wood fuels

lzaharis ■

Dear Sir,

We can provide you with a fully automated stockpile vibrating floor for wood chips.

In case you have decided on the approximate size of the stockpile, kindly let us know at jcp.silexport@wanadoo.fr and we shall reciprocate promptly with a proposal.

Jean-Claude Poncet ■