coal sizes

Hi all

i got my self a vertial coal fired boiler ,only missing the grate so i need to make one but my question is coal what size coal can/should be used in a firebox roughly 108mm dia 100mm high (bottom of grate to firetubes) its a 29 tube at 8mm each boiler is 250mm long all copper with phos bronse bushes.

hopfully that enought info to help

thanks

Gavin

What ever will fire through the firedoor

ok thanks

i notice there are all sorts of "sizes" Eg beans,grains etc but so far i not found any info to as what they are in terms of mm,cm etc. i was thinking of making the grate with 5-6mm gap

so say if firedoor is 40mm long 30mm high would beans fit ?

thanks

Gavin

When I was a small boy my brother and I used attend Victoria Pond in London with our Father to see our Grandfather run his Tug in straight running competitions, she was coal fired and it was his grandsons job to take small hammers and break up the lumps of coal into pieces that would fit through the fire door of his boiler, approx 3/4" square, the fire bars were approx 1/4" spacings between the bars. Great fun.

Martin P

Greetings Gavin, although beans will fit through your firehole door, I suggest that you would get better results with grains, with a more even fire.

regards

Brian

hi gavin,

you will get better combustion if the coal is of even size. anthracite beans or grains as sold for domestic solid fuel hopper type boilers would be suitable. most coal merchants of any repute will have a decent stock of both.

a 6mm air gap between the firebars is getting a bit big for the size of your boiler, and too big for anthracite grains IMHO.

breaking up welsh steam coal to the right size is a messy and time consuming chore, and produces a lot of dust and small particles of no use unless you have a coal burning stove/open fire, but i always prefer welsh steam coal over anthracite.

cheers,

julian

thanks all for replys

what size air gap and firebars would you recommend for grains ???

thanks all

gavin

hi gavin,

for the size of your boiler i would use 3mm stainless strip with 5/32" gaps in between.

i would buy anthracite beans to start with. if you are very lucky you will get old stock from 'Tower' that is soft anthracite. i wouldnt buy grains, but if you want to try some ive 3/4 ton of anthracite grains.

cheers,

julian

Edited By julian atkins on 31/01/2016 21:35:28

3/4 ton ! that's a lot of coal. could I ask why you wouldn't buy grains ? .by looks of things it looking like either would work but it depends on the boiler?.

gavin

anthracite grains are really very small and not suitable for loco boilers except very small.

i have a solid fuel stove in the lounge and was given the anthracite grains. they are ok in my miniature locos with a few provisos, but i have 30 plus years experience of firing locos, and i would think you would find them rather difficult. anthracite beans are much better. others may disagree of course!

i burn welsh steam coal on my miniature locos for passenger hauling. both types require a 'knack' to get used to. anthracite requires a sharper blast/touch of the blower.

i dont like the anthracite fumes. it makes my chest very bad and gives me an awful cough. hence why i still have 3/4 ton of the stuff!

i have enough decent welsh steam coal to last me out for the miniature locos.

cheers,

julian

Thanks for reply.

Few more questions if you will, what's best way to make the grate? I was thinking of just drilling and bolting all together or braising it up other than that maybe getting one water jetted?

Thanks

Gavin

hi gavin,

drill the strip and fit with steel rod through round spacers with holes in them as per LBSC.

i wouldnt try brazing it up, but you can buy from most ME suppliers stainless welded grate material, though i dont like the spacings/air gaps as not wide enough IMHO.

cheers,

julian

Thanks again for the advice, I drawn the grate in CAD ready to take to local engineering place he thinks depending on the drawings that a 10mm thick SS 316 grate cut as 3mm bars with 5/32 air gap should only cost £20-25 to water jet. So depending on price I either drill and bolt as you said or get one made. I let you know.

Gavin