THE COLLIERY GUARDIAN

■ AND

JOURNAL OF THE COAL AND IRON TRADES.

Vol. CXI.	FRIDAY, APRIL 7, 1916.	No. 2884.

Modern Coal and Coke Handling Machinery:

AS USED IN THE MANUFACTURE OF GAS.*
By J. E, LISTER, Wh.Ex., A.M.I.C.E., A.M.I.M.E.

The amount of gas produced per. ton of coal varies
from 10,000 to 15,000 cu. ft. or more. To handle this ■
coal and the resultant Coke entirely by hand would cost '
for labour .approximately 2s. ,6d. per, ton, but by the
introduction-of modern machinery this figure -may. be ■
reduced to 9d. per ton, or, if conditions are suitable, to
as low a figure as 6d. To obtain such results the plant
must be so- designed as to require the minimum of
attention, and the question of upkeep must not be lost
sight of, or the saving of labour will be considerably dis-
counted by the repair bill. Ina properly designed plant
the annual amount. required for the upkeep of the -
machinery should not greatly exceed 3d.- or 4d. per ton,
taken over a period of several years.	s

In charging the retorts by hand, putting charges of
3 or 4,'cwts. into each,; it requires considerable skill on
the part of the stoker to put in regular and level charges,
and unless this is... done the. coal is burnt off unevenly,
and the results are poor. Consequently, the use of
machinery for introducing the coal ■ into the retort is
extending. .

One of the best-known machines. for charging-
“ through ” retorts from one end only is the De Brouwer
machine, which travels along one side of the retort
bench, the coal being projected or thrown into the retort
by giving it the necessary velocity to suit the length of
the retort and the thickness of charge required. The pro-
jector consists of a built up steel frame carrying a large
grooved drum and: three broad guide pulleys arranged
on the inside of the-belt,..-and,so arranged that the drum
revolves at . the same speed as the-belt. The motor
driving the belt is usually an ordinary shunt wound
variable speed' machine of 4 ‘to 6b.b.p., with a speed-
variation of 750 to 1,500 revolutions per minute, but
compressed-air motors and rope drives are. also used.

The coal is fed into a small hopper, by a conveyor
running along the top, and passes■ directly from the
hopper through a telescopic shoot to-the machine.

• The coke is discharged from one end of the retort by a
telescopic ram, the first, or outer, length of which con- .
sists. of a solid bar, in which rack teeth are ■ cut in
the underside, a number1 of links with'teeth cast in
being jointedhn. to the tail end of the bar, so as to form
a long rack which is flexible in one direction-only. Safety
gear: is provided to- prevent overwinding when ; hoisting
or lowering the machine, and also to cut off the current ;
and'stop the motor automatically at the two ends.of the
stroke of the ram.	'

Many of the charging machines and combined charg-.
ing and discharging machines are'fitted with weighing
chambers for regulating the charges put into the retorts.
A large dial, and pointer, arranged in front of the oper-
ator’s, platform, show the. weight of coal run into the
chamber from the overhead hopper, and also act as a
guide to the man when he is regulating the speed of the
motor, and thus greatly facilitate the putting in of level
and uniform charges. The chambers, are made with
capacities of 12, 15, or 20 cwt., according to the size, of
the retorts.

Coal Handling Plants.

The coal must be elevated into overhead - hoppers,
from which the travelling machine can take.its supplies,
and must also be,broken to suitable size. . This is mosf
conveniently done ' before elevating; into the storage ,
hoppers, so that coal brought into the works, by rail or
cart is 'usually fed through a breaker , and down suitable
shoots to tlie elevator boot. In many cases mechanical

* From a paper read before- tfe :Society of Engineers. >

wagon tippers can be profitably installed; and one man
can then deal with .large quantities of coal without,
difficulty.	’'	;

• ...A complete plant which, together with the steel-
framed retort house, was recently supplied to the Osaka
(Japan) Gas Company, is showm in the illustration. - In
this case the combined charging and discharging machine
is fitted with a weighing chamber, and a hopper holding a
24 hours’ supply of coal is arranged in front of each bed
mf retorts. The elevator, which is of the usual enclosed
type, with malleable iron buckets carried on a man-
ganese steel ‘chain, delivers the coal op to a push b,ar
conveyor, which distributes it into the various' hoppers.
This arrangement, though more pxpdnsiye than the
central hopper plant in first cost, .is rather ' more
economical in working, as with the larger capacity of
the storage hoppers it is only necessary for the coal plant
to be. worked during the daylight shift.

- Scraper or push plate conveyors are very convenient
for dealing with small coal, owing to the ease with
which the point 6f discharge can be altered, ’while by
only partly opening some of the doors the coal can be
made to discharge' at two or three points simultaneously.
These conveyors work at speeds between 100 and 200 ft.

Carbonising Plant and Stoking Machinery.

per minute, and vary in sizes up to 24 in. wide. The
capacity of a 24 in., conveyor, with scrapers pitched 2 ft.
apart,; and running at 100 ft. per minute, would be
approximately. 150 tons per hour, if horizontal. Placing
the conveyor on the slope entails'a reduction in carrying
capacity of about 16 per cent, for each 10 degs. of
inclination.

Another-type of conveyor which is very frequently
used where large quantities of small coal are to be
handled, Is the gravity bucket conveyor, consisting of
two strands of chain supported by rollers or skidders
and carrying between them a series of buckets. This
type can be used for carrying-material both vertically
and horizontally, and the buckets can be made to dis-
charge at any required point, of their horizontal travel.
The buckets are. generally filled by an automatic feeder
which, brings’ a series'of: openings or pockets containing
a suitable amount of coal over each bucket in turn. This
prevents spilling of‘ the coal and ensures the buckets
being.evenly filled.	. .. ■

Band conveyors are frequently used:, as, by-means, of
a suitable • travelling throw^ofi - carriage, they- can - be
arranged to deliver at any point along the conveyor.

They require very little power in proportion to. the ;
amount of material carried, and they- are smooth and •
noiseless in working. Ordinary, cotton conveyor belting
is very generally used, but a built up belt of cotton duck
•and rubber gives by far the best results. . .In-one installa- •
tion a belt of this type dealt with<200,0Q0 or 300,000 tons.

of coal before the one face of the belt wore out and-’
the other side had to be used. These belts are frequently
made with additional plies of. duck lat the.: edges and
fewer in the middle, with a corresponding extra thicks -
ness of rubber. Rubber faced belts should not, however,
be used where the belt is continually subject-to heat.

The belts are carried on sets of rollers at short
intervals along the framing. The end pulleys should ;
not be less in diameter than 5 in. for every ply of. the
belt, i.e., for a s-ix-ply belt the pulleys should not be less
than 30 in. diameter. The working stress in the belt
when loaded should not exceed 30 lb. per in., of .width
per ply.	.

One of the principal London gas . companies -has.
recently installed a band conveyor plant for delivering
coal from a pontoon or wharf fixed in the Thames to a
large bunker arranged over the end of a retort house.
The bunker holds 600 tons, and the conveyor, which can
deliver at various intermediate points, has a capacity of
140 tons per hour. All the coal on its way to the. bunker
passes through a weighing machine, so;that a constant
check can be kept of the. amount of coal carbonised.. The
conveyor is divided .into three sections,' and -the total
length is 465 ft. ; The width of the belt is 2 ft. in., and
the speed 190 ft. per minute. The plant is driven, by a
gas engine of about 30 horse-power. .	,

Coke Handling Plants.

There are two principal methods of dealing mechanic-
ally with hot coke :—-(1) By means of-conveyorsand
(2) by means of transporters or telphers. In many -
cases a combination of the. two is the ideal arrangement, ■
a conveyor being used inside the retort house and a
telpher outside in the coke yard.	, J.

The chief advantages of a conveyor are that; if • is..
continuous in action, and therefore does not restrict the .
speed of the stoking machinery, and when once started
to work it is practically 'automatic in action, and does
not require a man in constant attention. The principal
advantages of. a telpher plant are the amount of ground;
that can be covered without an excessive expenditure,
and the small, amount of handling received by the coke,-
with ia corresponding decrease in the production of
breeze; but the speed of the stoking machinery is
regulated by the time taken by the transporter to run
out with a load, deposit it at the required spot, and
return for a fresh charge. A man is required constantly
on each telpher, which increases the labour cost, but .
the cost of upkeep, is light.	■■ y ; ’ ; ;

.One of the best-known hot coke conveyors’was :also ■
the invention of Mr. De Brouwer. The trough is lined
with renewable cast iron bottom plates and side angles,"
and is made watertight, so that water may be run into
■the trough or sprayed on ‘ to the coke for quenching
purposes. As the red hot coke leaves the retorts it is •
directed into, the trough by a deflecting plate or shoot,
and is drawn forward by the chain.	,	. ...

-Another type of conveyor which is considered by some ,
engineers to be the best for coke, ashes, and other sharp
and gritty materials is the. tray dr carrying conveyor.
This consists of a series of overlapping steel trays fixed
to a steel chain-running in the conveyor trough. The
material is carried quietly along without friction, and
in this respect the tray conveyor is good‘-tfon; brittle or
friable materials.	•mni..

A somewhat novel arrangement has recently b$en
adopted in one or two installations ‘ to enable a > largp .
amount of storage space to be covered by the conveyors,';fw
with; special arrangements for filling railway wagons or .
dumping the coke on to the ground without breakage.