I think you need a bin similar to those tanks used to hold LPG/LNG. They have a steel shell clad with a proprietary aerated concrete mixture for the insulation business. You will need steam heating pipes throughout the internals. Dont forget that it is the water in the coal which freezes and binds the business together. If you can remove some moisture it will help to reduce the heat demand during storage. Can you dry the coal in batches before you drop it into the bin? I see continuous drying as difficult because of conveyor idler lubricant thinning out at the drying temeratures required. Or you could try for a heated chain conveyor: depending on the throughput.

How do the people who work in the chilly parts resolve the problem? ■

Originally Posted by Serhey778

Dear professionals,

Does anyone have experience with heating systems for coal storage bin?

We are looking for heating solution for coal storage bin, 1100 ton capacity,

to prevent material freezing, keep material ability to flow.

Off course it should be cladded tower building, heated inside.

But still, coal is coming from outside open storage which is at

minus 40 degrees Celsius. What would be the heating idea?

Thank you for any information

AS Louis has so kndly stated steam is an excellent option to keep

the bin walls heated. In the United States typically in all climates

the coal bituminous coal is dumped then stock piled then crushed

and conveyed to to a coal bunker where it is either gravity fed or

mechanically conveyed to a stoker or pulverised coal boiler or to

a fluidized bed combustion boiler.

The problem is the plumbing and heat loss as relates to the square

area of the side walls or for that matter the cone if a conical

hopper is used WITH THE PROPERLY SIZED DRAWDOWN HOLE

ABOVE THE APRON FEEDER which in turn delivers the coal to the

intake hopper of the coal stoker.

Ideally if you can divert 15 pounds of low pressure steam to the

four side walls of the hopper/bunker it wil continue to heat up

the coal and promote it flow by reducing feeezing to a mininum.

Using household steam pressure would work using simple steam radiators

like those used for steam heating in homes; this would allow you

the fastest installation time as a shelf could be welded to the side

walls of the silo/bunker/bin to permit you use a simple single

pipe heating system for the entire compliment of steam radiators

on all four walls with basic individual atmosperic thermostats on

each radiator reducing the complexity of the system to near zero as

each radiator will have its own thermostat and you can adjust them

with one set temperature for the entire height of the hopper or

have the lower radiators adjusted with a higher temperature

closer to the bottom near the drawpoint of the hopper.

The radiators would have to be secured to the shelves they are resting

on to prevent them from moving but that is simple to do with a lip

around the edge of the shelf.

Basic household radiators would permit the fastest installation to the silo/

hopper/bin for your needs and a single pipe boiler or a single pipe feed

from your steam plant reduced to a REGULATED maximum 15 pound

delivery rate branching into four feeder pipes to the four sides of the

silo/hopper/bin would provide you with lots of steam heating tonnage at

a safe low pressure.

Not trying to throw out brand names but a very small Burnham coal stoker would work

and be independent of the main system preventing high steam pressure blowouts and

pinhole leaks in the piping.

The other plus is you can use schedule 80 threaded steel pipe rated for steam

heating and all you need to keep track of is the air vent thermostats mounted

on the radiators themselves replacing them as needed and keeping the system

as simple as possible avoiding dealing with the related high steam pressures

and water temperatures of 1,001 degrees or more in coal fired steam plants ■

It is usually impractical to design for full mass flow with a coal storage facility, but a mixed flow design will substantially enlarge the flow channel and reduce the prospect of arching due to frozen product by enhancing flow stresses for discharge and reduce the stability of ratholes. A point to consider is that coal entered to storage in a frozen condition will not stick together unless thawed out to melt the ice to re-freeze. Problems of dealing with frozen coal in severe winters have been overcome in 4000 Te coal hoppers by a design conversion that changed the flow regime from funnel flow to an expanded flow construction. ■

Will frozen coal under pressure from considerable overburden migrate under that pressure and subsequently refreeze to form an even bigger lump? Remember the wire cutting through a block of ice under the action of saddle weights. Maybe -40C is cold enough to prevent regelation.

If you do get any blockages the cleaning method must be compatible with the steel used for the bunker. Minus 29C is the reasonable limit for everyday boiler plate steel. Below that and you will need Charpy test certification for your steel. Even smacking a plate with a rubber mallet could be risky.

Why clad the tower building when only the bunker and outboard walkway galleries need the insulation? ■