Defra stance on coal burning. Have your say now ....

You'd need more of it for the same work (because it contains less energy per unit mass), so the fireman has to shovel more and the tender has to carry more.. You also change the combustion; effectively it all needs to be primary air (from below the grate) and no secondary air (above the fire). The design of fireboxes changed when coal was introduced, so probably you'd want to change back to burn coke, in particular you need a thicker firebed, so a deeper firebox. It's more expensive per unit energy than coal. The coke particles are also more abrasive, which means the tubes wear more quickly.

Tom

 

Even the early London sub surface lines used coke for their steam locos. Grim, but some folk went down to the trains for supposedly health reasons.
https://en.wikipedia.org/wiki/Metropolitan_Railway_steam_locomotives

Some years ago, when coke was readily available (before North Sea gas) I burnt it here. It gave out far more heat than coal but ventilation was needed. However, those were the days before everyone sealed their homes with double/treble glazing!

 

That answers my question about coke burning hotter than bitumous coal greenway thanks.

 

I know that coke was used for towngas cos of its hydrogen content i think cos up here in cleckheaton and many other heavy woollen towns and domestically it was used for street lighting and lighting in mills and houses we had town gas in cleck right up to the local gas works and railway round here right up to 1968 my dad told me he remembers it cos my dad is 70 years old and remembers town gas having a smell like rotten eggs before igniting it.

 

One of my relatives had a coke CH boiler, whilst we had a coke stove in the sitting room (a Parkray).

 

The Green Howards
You thinking of this? https://encrypted-tbn0.gstatic.com/...1zqFFcw2udw3BGyvqpQEwDDuP_E33MGxffJJ0sq1nlB8S

Knut

 

Town gas was simply a by-product of the coke ovens. Coke is produced by heating 'coking coal' (bituminous coal with good caking properties - ie it forms lumps rather than powder) in an oven in the absence of ait. This has the effect of driving off the volatile fractions of the coal, leaving the carbon and ash behind in the form of smokeless coke. The volatiles include a highish percentage of water, but also a mixture of Methane, Carbon Monoxide (the reason town gas was a useful suicide agent), a small amount of Hydrogen, and a few other bits and pieces, which when dried of the moisture content was sent through the pipes as town gas. I don't recall it smelling of rotten eggs, it wasn't much different to the scent they put in our natural gas (Methane) to make it detectable by smell today. The rotten egg smell that I remember came primarily from pit-heaps in areas of higher sulphur coal, where spontaneous combustion of bits of coal left amongst the rock spoil gave off hydrogen sulphide, with its characteristic smell out of all proportion to its small concentration in the gases given off.

In that respect, until we started using North Sea gas in 1968, coke and town gas was a win/win. each was a by-product of the production of the other. No waste.

Having said that you wouldn't want to live anywhere near a coke oven. They stank.

 

I'm sure that I've posted on this in the past but, very basically, coals can be divided into anthracite, bituminous coal and lignite or brown coal. Bituminous coals can be sub-divided into caking and non-caking coals. Caking coals have a property whereby, when heated, they soften, form a plastic mass and swell up into a porous mass. (I'm sure that many firemen will have come across this phenomenon on occasion, depending on the coal being burned. One minute you have what seems like a massive fire then the next it has collapsed.) Some caking coals are suitable for making coke, but not all. These coals are generally referred to as coking coals, even if they are not used for this purpose. All coals that are not suitable for coking are generally grouped together as steam coals, whether they are caking or non-caking coals. The use of the term steam coal does not necessarily mean it is good for use in a steam locomotive; it means that it is only of major use in steam raising as it cannot be used to make coke.

 

Exactly. The vast majority of bituminous coal produced in the UK was classed as steam coal and the vast majority of that (about 70%) when we were producing a hundred million tonnes per annum went to power stations as smalls and fines. The power station burners were set up for coal in almost powder form. Many seams produced the ideal friable product for this, only some seams produced coal that was robust enough to be screened into doubles (for household), trebles or cobbles as well as fines. Your average steam engine would have a hard time burning power station coal, they needed the nice hard and bright lumpy stuff that would fit on a shovel and not fall through the grate or be blown out of the chimney before it burnt.

 

I know exactly what a coke oven smelt like, I grew up near Sydenham Gas Works in South Londom. coke for steel production was slightly diferent to gas production in that the prime product was gas. Coke was a by product used both domestically as smokeless fuel and industrially. There were also many by products. Creosote, benzine (added to petrol) naptha (mothballs) etc.

Incidentally the smell of gas is an additive. Methane has no smell, its added to domestic and bottled gas so you know there is a leak. Cant remember if the smell of town gas was natural or added

 

I thought I'd said that in my post.

It's disconcerting on holidays abroad to find that when I'm cooking on a gas hob that the additive is absent. It's easy to leave the tap on unlit if you're not careful.

 

The additive is called Mercaptan, and is horrible stuff. I was discharging a propane/butane mix at a port in the Cape Verde islands and we had to pump it from a 208 litre drum into the cargo stream at the ship's manifold, using a barrel pump. Highly hazardous for our people ☹☹☹

 

And I should think being larger lumps allowed for more air flow through the fire itself.

 

Power station coal was ground to a fine powder at the base of the boiler and blown through jets into the boiler. Most modern stations Eggborough, Cottam etc used 5 to 6 ball mills. Experiments had been made in early years on storing pulverised coal but they usually resulted in explosions.

Lighting a PF boiler was done using oil burners followed by the coal burners which were ignited by the oil

 

Just so, but we the stuff we sent out to the power stations from our screening and disposal points mainly consisted of smalls and fines in the first place, with the larger coal generally being retained for other uses. It still needed crushing at the other end to meet the boiler requirements. Some larger coal might find its way there depending on marketing requirements to meet the tonnage, but in general it was the small stuff.

Not a good idea to store pulverised coal. It's dangerous stuff. The normal run-of-mine was bad enough on the stocking grounds, where temperature tubes sunk into the stock on a grid had to be monitored regularly to ensure that no hot-spots were forming that could lead to a spon-com fire. If the temperature went up, the loaders went in to spread and cool the coal involved.

 

Whilst you wouldn't think so now looking at the scrub/wooded area between Marley Hill shed on the Tanfield Railway and the site of the former Marley Hill Colliery. It's a former valley filled with pit waste and small/fine/coal dust, there had been a link spur from the Bowes Railway [who owned/operated Marley Hill Shed]. This spur is one of the first places that concrete sleepers were used as the whole area had spontaneously combusted and burned for years. There were other areas around the west of Gateshead that were full of small/dusty coal that burned for years too Stargate being one that burned well into the nineties.....

 

Watergate at Gateshead tip was another one. Mainly a shale tip, but there were enough coal and carbonaceous shale fragments in it to start an underground fire that went on for decades. The size of the coal in these situations isn't important. There doesn't even need to be coal there. High carbon shale will do it. It can occur with lumps of any size. The important factors are moisture and the degree of ventilation. Oxidisation starts, heat increases and it can't dissipate, combustion follows and it smoulders on like a garden fire.

 

It's very complex stuff, coal; not simply a black rock.

 

Mercaptans are certainly potent, I believe they are the most pungent compounds available. We used them in our labs at work, always in a fume cupboard, but on one occasion a chemist managed to spill a few drops on the bench resulting in the evacuation of the entire 4 floor lab for several hours.

 

Indeed. Bituminous coal coal alone has four different types that can be found within a single seam in varying proportions. One or more may be missing, or all four may be present - and that's before you get into stuff like percentage ash, percentage moisture, percentage volatiles, percentage carbon, calorific value, caking properties etc.

They are:

Clarain, a shiny black often hot and low ash coal. It looks pretty, with a cubic fracture, but is often crumbly and breaks into small pieces without crushing.

Durain, which along with clarian makes up the main part of most seams. It is dull and as the name suggests, hard. It can vary in ash from low to high and the CV varies accordingly, so you can't judge it on appearance. Pick up a lump and if it's light it's probably low ash and hot; if it's heavy, the opposite. It tends to break into large lumps.

Next there is Vitrain, another descriptive name to describe the glassy appearance of the coal on the semi-conchoidal, as opposed to cubic cleavage planes. It is usually higher CV and breaks into moderate lumps. Often seen in household coal.

The least common form is Fusain. It is a dull, dusty coal that is found in thin dusty bands within or often at the top of a seam. It has a greasy, graphitey feel, totally unlike the granular feel of small particles of clarain. It's appearance suggests it's 'just' coal dust or even dirt, but it's a hot product. Nice for power stations, thown into the general mix, from which it can't usually be separated because of its softness and sparcity within the seam.