408

THE COLLIERY GUARDIAN.

March 3, 1916.

borings in the Campine. The correlation of the Campine
coal measures with those of the adjacent districts is
shown in the accompanying Table IL, in which the
author has supplemented Renier’s classification so as to
include as many important data as possible relating to
the thickness of the measures, number of seams, gas
content, etc.

(To be continued.)

FUEL OILS FROM COAL.

At a meeting of the Manchester Association of
Engineers on Saturday last, a paper on “ Fuel Oils from
Coal ” was read by Mr. Harold Moore, M.Sc.Tech.,
F.C.S. He said the present was a time of critical self-
examination for our country, and any method of employ-
ing more efficiently its natural resources was worth
careful consideration. It was of special importance to
find a substitute for petroleum. This matter had
become more apparent since the outbreak of war,
because the importation of liquid fuels was one of our
most serious expenses, and if it were possible to pro-
vide a home supply, even of small proportions, it would
be a desirable attainment from the view-point of
national economics. Shale oil had been found to be a
satisfactory substitute for petroleum, but, unfortu-
nately, the output was not sufficiently large to make any
'serious impression upon the market. In Scotland, it
was less than 300,000 tons per year of crude oil, as com-
pared with about 33 million tons of petroleum produced
in the United States. Animal and vegetable oils were
scarce) and of too much value for other industrial pur-
poses to find their way on to the fuel market, where large
quantities and low prices were essential. Nor was there
any immediate prospect of peat oils coming into use,
though the quantities of peat available warranted
optimism in that direction. Turning to the question of
coal as a source of liquid supply, Mr. Moore said that
special note should be taken of the chamber oven process
■—a plant which was designed for carbonising large
charges of coal, and yielded liquid products differing con-
siderably from those produced from other types of oven.

these processes might be used for the generation of
electricity by using the coke in producers, mixing the gas
from the retort with the producer gas, and then burning
the result in gas engines, in which case tar and ammonia
would be by-products. As no process of carbonisation
could be successful without obtaining a suitable market
for all the products, it was necessary to find some use
for the coke and the gas. The yield of the latter being
small it would probably be washed for motor spirit, and
then burnt under the retort. The disposal of the coke
was a much more difficult matter, but if a suitable
organisation for its sale to householders existed, the pro-
blem would be solved, because low temperature coke
was more easy to ignite than other classes, and formed
an excellent smokeless fuel for household purposes.
There was also the possibility of using the coke for
producers where it should make a good substitute for
anthracite. It was suitable for steam raising, but that
would not be a very profitable means of disposal as the
price would have to bo low in order to compete with the
cheaper coals.

The yield of liquid products from the low temperature
carbonisation varied very much with the class of coal
used, but it was only from raw material containing a
large percentage of volatiles that any great advantage
would be gained. The Premier Tarless Fuel Company,
working a plant at 900 to 1,000 degs. Fahr., under a
vacuum of 25 in. of mercury, obtained the following
average yields of tar:—Cannel (poor) yielded 52 to
60 gals, of tar per ton; cannel (good), 60 to 80 gals, per
ton; and slack, 20 to 25 gals, per ton. The specific
gravity of the tar was 1-060. That product, if carefully
dehydrated, would make an excellent fuel for Diesel
engines.

There was another possible solution of the fuel oil
question which had not yet been approached, and which
was applicable to all types of carbonising plants, namely,
the fractional condensation of tars. Though that method
had, from time to time, been suggested as a means of
helping the fractionation of the tar, or to some extent to
avoid distillation, it had not, to his knowledge, been
recommended as a means of obtaining coal-derived
liquid fuels. The principle of fractional condensation

THE JEFFREY CRUSHERS.

The crushing machinery made by the Jeffrey Manu-
facturing Company, of Columbus, Ohio, is well known
in this country, both for the pulverisation of rocks and
ores, and for ’ihe disintegration of coal and other softer
materials.

To meet the demand for a product smaller than 2 J in.
the Jeffrey Manufacturing Company has designed a
single roll crusher capable of reducing through-and-
through coal to 1 in. size and under in one operation.
In this crusher, the variation of the “ crusher opening,”
i.e., the adjustable space between the crusher roll and
the bottom of the crushing plate, enables a considerable
range of sizes to be obtained.

A view of the machine is given in fig. 1, whilst fig. 2
shows the adjustment of the teeth on the crusher roll.
The design is simple, consisting of a heavy east iron
frame in which are mounted a crushing roll and a
breaker plate. The breaker plate is hinged at its upper
end, and is held in position by a pair of adjusting rods
at the lower edge by means of which the clear opening
between the breaker plate shoe and the surface of the
•roll can be varied to give any product required. A
clamping effect is produced by the proper adjustment of
the cross-rod bolts between the side frames, whereby
sufficient friction is brought upon the hinged breaker
plate to eliminate chattering and to assist the safety
device.

The concave breaker plate acting in conjunction with
the roll, makes a form of maw with a very small angle
of repose; hence the machine will readily grip a very
large lump and reduce it-to such a size as to pass through
the opening between the roll and plate. A countershaft
is mounted directly on the machine, and drives the roll
through such a heavy pair of gears that' sufficient torque
is obtained to start the roll under all conditions of load.

The driving pulley is not keyed to the shaft, but is
mounted on a separate hub, which it drives through a
set of wood pins inserted in holes in the arms of pulley.
When any undue strain comes on the machine from any
cause, these wood pins shear off, and the roll stops while
the pulley keeps on revolving, thu-s forming a very

V

II

I"

Fig. 1.—General View of Single-Roll Orhsher.



Fig. 2.—Teeth of Crusher Roll.

I

Some coke oven tars were suitable for use in Diesel
engines, while others were unsuitable, but chamber oven
tars were generally suitable.

Low Temperature Carbonisation.

The low temperature carbonisation of coal was a
comparatively recent proposition, and was the outcome
of attempts at a logical treatment of coal in order to
obtain the maximum service from all the products.
Three types of plant had been designed for working on
that system, but only one had been on the market
for a sufficiently long period to afford information regard-
ing its practicability from a commercial standpoint.
When coal was subjected to destructive distillation, the
yield of liquid products was largely influenced by
temperature at which carbonisation took place. As a
general rule, the lower -the retort temperature the larger
the yield of tar.

In practice, gas plants such as the horizontal retort
yielded an average of 9 to 13 galls, of tar per ton of
coal, which represented about 5| per cent, of the weight
of coal taken. Coke ovens yielded 4 to 5 per cent, of tar,
whilst the low temperature processes gave 10 to over
20 per cent, of tar, the yield depending very largely upon
the quality of the coal used. Comparatively small
quantities of tar were obtained as a by-product of gas
producers, oil-gas plants, and of some blast furnaces.
Tar from gas producers was too irregular in composition
to become of much value as fuel in the immediate future.
Tar from oil-gas plants was not a coal derivative, and
wias not yielded in -sufficient quantity to become an
important source of power. Blast furnace tars were not
available in quantity, and generally contained far too
high a percentage of ash to be of use for internal
combustion. In point of economy, tars afforded ideal
fuels in a country possessing no petroleum resources and
a copious supply of coal.

Having referred at length to various forms of fuel oils,
the author went on to say that it was improbable that gas
companies would adopt low temperature types of plant,
on account of the low yield of gas, but they might be run
on a small scale to enrich gas of inferior luminosity, as
the gaseous products of the low temperature plant were
of very high candle-power if not stripped of any of their
condensable contents. It had been pointed out that

was that the hot gases containing condensable products
should, on leaving the retort where the carbonisation had
taken place, be cooled in stages, so that the less volatile
would be condensed first, and the more volatile pro-
ducts later. That appeared to be a cheap and economical
way of obtaining ideal fuel oils.

In the course of the discussion, the chairman (Mr. S.
Boswell) pointed out that great attention was now being
paid to the utilisation of materials formerly allowed to
waste, especially in the production of heat. The willow
tree was of little use for timber, but experiments had
shown that a ton would yield 7,700 cu. ft. of gas and
530 lb. of charcoal. Other speakers stated that since the
war it had become increasingly difficult to dispose of the
residuals from gas works, such as tar and pitch, because
markets formerly open were now closed, and prices had
fallen considerably. Gas engineers were therefore dis-
posed to welcome any method of making better use of the
residuals. In one case a gas had been distilled from the
tar and sent into the mains, improving the supply for
lighting and calorific purposes.

London County Council’s Coal Supplies.—Some time ago
the London County Council reported fully upon the special
circumstances affecting the coal supply, and the Council
authorised its Stores Committee to make any necessary emer-
gency arrangements for supplies for the year commencing
July 1, 1915. Now the Stores Committee reports that con-
tracts were accordingly entered into with merchants for the
supply of a portion of the domestic and other supplies of coal
and coke required for offices, schools, tramway depots, parks,
fire stations, etc., and the remainder of the coal (except for
main drainage stations) was obtained direct from collieries.
As regards the supply of steam coal for main drainage
stations and sludge vessels, it was found necessary to make
arrangements with certain firms, and these arrangements
have worked satisfactorily. In addition, it has been neces-
sary, as occasion arose, to make special purchases out of con-
tract in the open market in London. As arrangements
similar to those now in force will be absolutely necessary for
some time to come, the Stores Committee considers that it
should have authority to deal in such manner as it deems
best with all questions relating to the supply of coal and
coke during the period of the war.

efficient safety device and preventing accidents to work-
men. A pair of heavy springs -are placed on the tension
rods. These springs do not move under ordinary working
conditions, but when any undue pressure comes on the
breaker plate they act as a cushion giving way slightly,
taking up -the inertia of the parts and allowing time for
the pins to shear without breaking more important
elements in the machine.

Toothed segments are bolted to the convex surface
of the drum so as completely to cover it. The frame and
hopper are so arranged that by removing the light steel
guard plates access may be had to the bolts and the
segments removed and replaced by new ones without
disturbing either the roll or the hopper. Narrow gaps
in the shoe of the breaker plate enable the long teeth
•to pass without dragging oversize pieces with them.
These teeth not only act as feeders, but they positively
grip the large pieces and break them up in sizes to readily
enter the maw of the machine.

Bv making the smaller teeth on the segments of the
peculiar shape shown, the proper reduction is made with
a minimum amount of slack. For exceptionally severe
work, the long teeth are made of cast steel, and inserted
into the body of the segment, or the segments are made
entirely of manganese steel.

These crushers are made in four standard sizes, vary-
ing from 8 in. by 18 in. to 36 in. by 36 in. The latter,
it is claimed, will reduce to stoker size 200 tons of
bituminous coa-l in one hour. The crushers may be used
in conjunction with hoppers, chutes, conveyors, or
elevators, and may be stationary or portable, according
to the purpose for which they are required. Fig. 3
shows an installation in which lump coal is uniformly
•fed by an oscillating feeder plate to a Jeffrey 24-in. by
24 in. single roll crusher, from beneath which a spiral
conveyor takes the crushed product to the pivoted
bucket line. Through a slide valve at the dump hopper,
fine coal and slack may be delivered direct to the bucket
conveyor without passing the crusher.

Another type of crusher extensively used is the swing
hammer pulveriser, which has proved itself an efficient
machine in the reduction of a variety of substances.
This machine operates on the principle of reducing
material by striking it while in suspension, as opposed to
the attrition mill, which mashes or rolls the substances