I'd suggest that 30% moisture & - 40 degrees is something akin to piping a Bingham plastic around a freezer, & then some. You'd need extensive lagging everywhere. Chute lining is one of your lesser problems, but it will need to be Charpy tested along with the majority of your steelwork. Belt cleaning could be a nightmare. Most people would simply move shop.

If your outfit is serious about taking the job on then you could consider lagging (pipes all around the site will be lagged as a matter of course) the chutes and let frozen ash crack up at discharge.

You have to be talking about transfer chutes only. Any storage hoppers are on a hiding to nothing. Why not use belts one size up from the design requirement & use simple deflector panels at the transfer points? With 30% moisture, frozen or not, you are hardly likely to encounter dust problems so why enclose the gunge in the first place?

Just thinking aloud. Sounds like a Ukrainian metals refinery has Stepped up to the plate yet again. ■

Originally Posted by Roland Heilmann

Dear louispanjang,

thank you so much for your response / at least someone takes this seriously...

No, in order to do the (a) job we'll not move shop.

The moist flyash will leave the mixer at a temperature of appr. 90° C and the transport has to be faster than the warmth dissipation.

(The phone no. of Mr. Scott wouldnt be bad...)

So we move the bulk in a closed system (warmth!) until the stacking site. There in the transfer points now the problem arise: How to converge abrasiveness with the building up of the flyash in contact with (probably very) cold metallic (?) surfaces. Any shared experience is welcome!!!

As for the loud thinking, no, this problem dwells north of the 49th degree N.

points taken:

Charpy tested quality of steel materials: I do this always when being so far north.

Flat baffle plates in place of curved: If the transfers will allow for this...

Thanks once more!

Roland

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Greetings and salutations Roland,

A poly liner material would melt unless the ash is cold so its not an option, a ceramic liner material from Coors ceramics might be the best way-- not to name drop mind you as its the first product I thought of.

(www.coorstek.com)

Aanother option is Hardox steel plating I think it is also referred to as AR plate-attack resistant plate not to name drop that name either but.

lzaharis ■

First: I am obviously missing part of the puzzle as the explanation is not complete.

you apparently are not using a pulverized coal boiler with a wet ash pit to pump bottom ash.

Please explain further;

Can you offer up a drawing of some type or a flow schematic?

how is the coal delivered to the system boiler?

A coal bunker consisting of either: A dump hopper with a delivery auger to the boiler or a belt conveyor from a stock pile to the boiler throat via drop chute?

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Are you dealing with bottom slag from a Riley or other Stoker?

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Is your stoker totally exposed to the weather and if so why?

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How exactly is your waste coal stream set up? Please explain in detail either here

or use my email lzaharis@lightlink.com as some thing seems very odd with this unless you are using a small horse power Burnham coal stoker steam boiler

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So you are not going to be using a plow conveyor or auger for the coal wastes transfer to a waste hopper below the stokers-assuming you are using stokers. and if you are using stokers----a plow conveyor under the stoker discharge will work wonders and work in all weather with a chain drive and gutters.

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In lieu of a zero option for Coors Ceramics making you custom lined chutes:

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A plow conveyor is a win, win, set up for hot coal waste slag removal and easy to repair.

Please explain further as something is terribly wrong here. ■

Power station fly ash (ash in the gas stream) in my experience is collected from an electrostatic precipitator. It's not bottom ash which frequently is dropped into a submerged chain conveyor (SCC) these days.

It's pretty normal to mix the bone dry fly ash with a bit of water to dampen it and stop it "flying" about during subsequent handling. Trouble is in this form it can be sticky (very) and can even set hard with suitable conditions (after all, some fractions are used as a replacement for cement in concrete structures), or in very cold conditions can freeze solid.

What to do??

Trace heating and lagging to maintain above freezing (high temperatures can encourage concreting)?

Flexible chutework that's deformable to enable any concreted material to be cracked (hammering the flexible chutework) and then removed?

Just ideas. ■

I'd like to jump in alongside Designer. Trelleborg used to make dump truck body strength rubber panels which would be suitable. ■

Hello Gentlemen. After monitoring the case study may I comment ?

Flexible rubber chutes are not up to ash abrasion, ceramics in adhesives are also out, BUT ceramics in either a mechanical rail fixing or in polyurethand bolted pannels are.

To have trace heating to remove dew point or temps up to 100 C will eliminate the freeze.

The chute design MUST be circular as to eliminate corner valley angles which will

cause sticking and rat holeing and subsequent total blockage.

The ash must be presented with a wear surface which give a low coefficient of friction of something of 2.8 or near glass.

All polymer linings will not perform in the abrasion but in the early days give flow.

Polished stainless steel can be used as the chuite fabrication base and double up as the liner.The problem is the life expectancy.

We have made linings in The most severe cold conditions which perform both in the COLD & HEAT as a dual life.

If you want an in depth proposal and specification you could contact me directly.

Finally beware of your angle for your chutes faces and your chute geometry design. ■

Originally Posted by Roland Heilmann

Gentlemen,

thank you very much for your detailed questioning & input.

As general information: I'm only involved in the problem of liner material choice and related problems in the dumping equipment zone (hints to chute design etc.). Nevertheless I'll try to redirect other information or proposals.

As I exactly understand there's two wholly different bulk areas with special features of their own: dry ash transportation zone and wet ash zone.

I'd conclude as following for wet ash zone:

The main point in wet zone is maintaining the flow, avoid any buildup and take care of a speedy way to replace liners (points for chute design: straight / steep surfaces, avoid corner angles). Then, as abrasion will occur (and heavily so), regular checking & replacement must be enabled and the systems flow regime must allow for that (planned downtimes).

Feasible options for liner material are: steel lining (perhaps specially treated), profiled rubber bars / rubber plating over base steel plating. Transfer points: heating of flow relevant zones should be possible (~ housing, heating plates).

Nevertheless, if there's someone who has seen moist flyash going over a belt conveyor / chute - system, any hint would be welcome.

Thanks once more to everyone!

Roland

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The one option not discussed is the simple use of a twin ram concrete pump to move the wet fly ash, the pipe is easily replaced as it is simply clamped together can be heated with resistance cable. the delivery pipe is abrasion resistant.

As long as the concrete pump rams are moving the ash will move so that is a no problem situation.

Using concrete delivery pipe and a concrete pump would eliminate and issues or need for conveyors as the waste could simply be pumped to the fly ash dump and simple friction and a bit of water will keep it hot for proper flow as the pipeline will have no restrictions other than distance and the inside surface area of the pipe for that distance.

lzaharis ■

As long as the temp remains below 70 deg. C you could look at inflatable rubber liners. They have a proven performance in keeping chutes clean and have quite good wear life as well.

For abrasion resistance consider bolt on rubber ceramic composite liners.

The inflatable liners and the ceramic composites can be made with stainless backing so corrosion wont be much of a problem.

Both these products are manufactured by Valley Rubber in Alabama USA. The contact there is Bob Cooper.

regards

David

Screentek ■