Coke

[Nick Clarke 3Participant @nickclarke3]

I know that some early locomotives burnt coke not coal but that this practise, as far as I know, died out.

Is there any reason why modern locomotives (model and full size) can’t use coke as fuel – wouldn’t it be more environmentally friendly?

[MichaelRParticipant @michaelr]

The cost of producing Coke from Coal would rule that idea out,

 

[noel shelleyParticipant @noelshelley55608]

When town gas was made at the local gas works the coke was a by product and was cheap ! Coke is now specially made and costly, if made in small quantities all the by products would have to be dispossed of, even more costly ! Steel is (was) the last big user of coke and even they are going over to electric for envionmental reasons. Noel.

[SillyOldDufferModerator @sillyoldduffer]

Good stuff coke.  It’s made by baking coal in a retort, which drives off impurities leaving almost pure carbon behind.  How pure the Carbon is depends on the coal, the qualities of which vary enormously.   Much depends on the type of plants that grew, how deep the layer is, how quickly and hard the vegetable matter was pressurised, what else Mother Nature dropped in the mix, and how long the fossilization process has been running.

Generally, very old hard coals are the good stuff, whilst Brown coal is young, very impure, and has a low heat value.   Most of the world’s coal is Brown, and near the surface so it can be strip mined economically, but it’s not worth coking. Most of it is burned to make electricity.  Doing so generates a lot of pollution and Carbon Dioxide for the energy obtained, but Brown coal is literally dirt cheap.  At present rate of consumption, about 300 years before it’s all gone.

Most coke is used to make steel, which depends on pure Carbon.  Steel coke is made from older hard coals, which tend to be found deep underground and are expensive to recover.

When good hard coal is baked, many of the impurities turn out to be valuable by products, so making coke can be highly profitable.   Unfortunately, the coal used has to be suitable and the cheapest most common coals aren’t.

Brown coal is coked on a smaller scale to make smokeless fuels.   Rather than allowing millions of open grates to create smog, making coke with it captures most of the muck with a centralised industrial process.   The resulting fuel doesn’t have as much heat value as a hard coal, but it doesn’t fill the air with Sulphuric Acid as Brown coal is prone to do.

Early locomotives burnt coke because coal in a basic firebox makes incredibly dirty smoke.  Mostly fixed by the invention of the fire arch, a brick structure inside the firebox that glows red-hot and ignites partly combusted smoke by swirling it at high temperature before it reaches the tubes.  More heat is gained from the fire and what goes up the chimney is much cleaner.  Locomotive engine smoke can never be clean, but coal and a fire-arch are as good as a coke fire, and cheaper.

I don’t think there’s much to be gained from burning coke in a locomotive.  A better answer is to electrify the line, and generate the power by burning coal efficiently in a modern power station fitted with Carbon capture.   Then, if the wind happens to be blowing, or the sun shining, the power station can save fuel when the train is propelled by renewable electricity.

Anyone remember ‘Nutty Slack’.  This I think was the worst coal product ever sold to an unsuspecting public.  Low heat, highly polluting, difficult to ignite, useless in furnaces, and filthy to handle.

Dave

 

[Nigel Graham 2Participant @nigelgraham2]

Some steam road vehicles were also intended to use coke, but with a different grate and perhaps blast nozzle. I don’t know the details but I think the bar / space proportions differed from grates intended for coal.

If I recall correctly Hindley & Sons advertised their steam-wagons as suitable for coal or coke, but the catalogue did not mention if this needed a grate to suit.

[Paul LousickParticipant @paullousick59116]

I burn coke, made from wood when I don’t have coal (BBQ fuel from hardware store) which steams well. The only problem is that it burns much faster than coal and produces a lot of hot embers that go up the chimney and they burn when they land on you. You need a spark arrestor if you are using it.

[Clive Brown 1Participant @clivebrown1]

I’ve a hazy memory that the Ravenglass Railway tried coke some years ago. I think the idea was to reduce smoke for better passenger comfort. There was concern from the maintenance staff that the loco firbox suffered in some way, also boiler steaming was not so good due to shorter flame length.

[Nicholas FarrParticipant @nicholasfarr14254]

It’s over twelve years since I had a Parkray boiler to heat my home, but when I first had one, I used coal to get the boiler up to temperature, and then used a rich coke mixture of the two, which would burn longer and give out quite a lot more heat. One side effect though, coke produces clinker, which if isn’t cleared at reasonable periods, prevents the air flow from keeping the fire alight. It must have been about three years or so before I no longer needed a real fire for heating, that the price of coke went up so high, that the coal merchants near to me, stopped selling it, and I used smokeless nuts instead. Quite glad I don’t have to use a real fire now, as there is no need to sweep the chimney and clean up anymore, and no ash dust to clean up in the house, and my environmental pollution amount is greatly reduced.

Regards Nick.

[Clive Brown 1]

On Clive Brown 1 Said:

I’ve a hazy memory that the Ravenglass Railway tried coke some years ago. I think the idea was to reduce smoke for better passenger comfort. There was concern from the maintenance staff that the loco firbox suffered in some way, also boiler steaming was not so good due to shorter flame length.

R&ER used coke for many years untill the composition changed somehow and it was burning the tube ends. No issues with steaming, in fact as coke has lots of air holes you could put a lot more on the grate and not have to fire as often, which is good when you don’t have a fireman, just a driver.

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