September 13, 1918.

THE COLLIERY GUARDIAN.

551

CURRENT SCIENCE

Oil Fuel in the Foundry.

In a paper presented to the annual meeting of the
Institute of Metals, Capt. A. E. Plant described the
application of oil fuel to a repair shop foundry in
France.

A “ Charlier” oil furnace, with a capacity of 5 cwt.,
was installed. The fuel recommended was a tar oil.
There was no burner. A 1-in. gas pipe, led along the
top of the air blast pipe, was bent over at right angles
at the end, and was connected to a receiver—this, in
turn, being connected to an oil tank mounted on a
platform about 12 ft. from the ground. The oil issued
in a thin stream at the end of the blast pipe, and the
force of the blast converted it into a spray. It was
regulated in the usual way. The air blast showed a
pressure of 9g m. (water gauge).

Owing to a considerable rise in the cost of this tar oil,
an attempt was made to utilise a considerable quantity
of wasts oil and grease that had accumulated from the
cleaning out of the engines and gear boxes of cars and
lorries that were undergoing repairs in the depot.
After settling, this oil was found to be quite easy to use.
It gave better results than did the tar oil, and, for over
two and a-half years, nothing else but waste oil has
been used.

For remelting ingots in crucibles, it was decided to
build a vertical furnace to take up to 100 lb. crucibles,
and to use the same waste oil as fuel. The furnace was
circular in design—the casing being made of cast iron
and the lining of firebricks. The blast pipe had a jet of
in. diameter connected to it. and the jet entered the
furnace at such an angle that the issuing flame struck
the furnace wall at a tangent, and a whirling motion
was imparted. The vaporised oil entered the furnace
just below the centre of the crucible—not the bottom.
The blast pipe was itself 2f in. diameter. Flames and
hot waste gases, which exhausted through an opening
at the bottom of the furnace, impinged directly on it, so
that the blast entered the furnace at a high temperature.
The fuel entered the blast pipe through a f-in. steel
pipe, just above the place where the hot exhaust gases
struck it. Directly in front of the heated portion of the
blast pipe was a cast iron baffle plate, which deflected
the flow of exhaust gases upwards, and gave the blast-
pipe in front of it the full benefit of all the waste heat.
The fuel oil was contained in a 15 gallon tank, fitted
with a hand air pump and a pressure gauge. About
5 lbs. of pressure was kept up. In between the fuel tank
and the entrance of the oil to the blast pipe a brass
receiver was fitted, in order to fulfil two purposes.
Firstly, it was easily heated by a blow lamp on very cold
days, to make the oil run freely for starting up.
Secondly, it regulated the supply of oil to the blast pipe
in case the oil flow from fuel tank was a little sluggish,
as it often is when very cold. Thirdly, it acted as a final
trap to catch any dirt or foreign matter in the fuel oil.
Between the receiver and the fuel lead pipe to the
furnace a small regulating cock, was fitted. The
pressure of air used was 9in. (xyater guage). Anelec-
tric motor driving a fan at 3,<»00 revolutions per minute
was the source from which the air supply was derived.
A firebrick cover closed the top of the furnace, and had
a small aperture in the centre for charging and
inspection.

The chief points in favour of using oil fuel in the
circumstances mentioned are—(1) It is only necessary
to have the furnace in operation about a quarter of an
hour before the crucible and charge are introduced ; (2)
It often happens that the furnace is not required all day
long, and it can be put in and out of operation very
quickly; (3) Temperature control is easy and consistent;
(4) Saving in transport of solid fuel; (5) Utilising waste
oil on the spot; (6) In the case of the “ Charlier”
furnace, borings and scrap can be melted more easily
and economically than could be done in crucibles.

Lubrication and Lubricating Oils.

In a paper contributed to the Society of Engineers
Journal, Tokyo, Japan (abstracted in Railway Gazette),
Mr. N. C. Bruun, states that the available amount of
fixed oils (animal or vegetable) having been found to be
insufficient recourse had to be taken to neutral or
mineral oils. These were found to have such manifest
advantages over the fixed oils that the author, while
acknowledging some of the good qualities of fixed oils,
confines his remarks almost entirely to paraffin and
asphaltum base oils.

Fixed oils are excellent when fresh and can be varied
in viscosity as required ; but they contain oxygen, and
in use absorb still more of the gas, resulting in the oil
drying into a gummy matter of no use as a lubricant.
Acids are also developed, causing pitting and cor io-ion.
They do not easily separate from wat^r—a fatal
objection on some systems; they cannot be distilled,
and when treated they decompose and carbonise. These
oils are used in some cases compounded with mineral
oils where the lubricant must possess emulsifying
characteristics, as in the inverted cylinder type of
marine reciprocating engines; in drawing, wool cutting,
or softening oils for textile mills. In the later circu-
lating or forced oil systems a pure mineral must
perforce be used.

By applying the Conradson carbon test, or from an
ordinary distilling flask, the following approximate
results are obtained:—

Paraffin base oil—

5< >0 viscosity, deposit 0*55 per cent. } hard

300	„	„	0’26	„	j carbon.

Asphaltum base oil—

500 viscosity,	deposit	0’03	„	I soft

300	,,	,,	0’02	„	J carbon.

The carbon deposited by the asphaltum oil, when
issued in equal quantities with paraffin oil, is from two
to three times less than that deposited by the latter;
and, moreover, the deposits are soft and can be dissolved
in kerosene, whereas the paraffin deposits are hard and
crystalline and have to be scraped or even chipped.

The chemical formula for asphaltum base oil is
Cn £Lzn — 4; that of paraffin base oil On Hzn 4- 2 (the
value of n being a variable factor); that is asphaltum

AND TECHNOLOGY.

base crudes have four less* than twice as many atoms of
hydrogen than of carbon, whereas paraffin base crudes
have two more than twice as many atoms of hydrogen
than of carbon. The asphaltum molecules aie much
sm iIler than those of paraffin ; they are of uniform
shape and are packed close toge her; whereas the
others are of irregular shape with comparatively large
spaces between them. The asphaltum base oils, there-
fore, having a high specific gravity, give the lowest
co-efficient of friction, as well as the greatest durability.
Owing to the absence of paraffin wax they have a natural
cold test as low as 0 degs. Fahr, in some cases, as
against 20 degs. Fahr, in the paraffin. Asphaltum base
crudes can produce an oil with a viscosity of 750 sec.
and a cold test of 5 degs. Fahr.—these two points being
the most important in a lubricant. This has been
recognised both in the Navy and the War Department
of the United States.

Experience with Powdered Coal.

Low grade fuels can be burned with high efficiency
if used in powder form. Experiments show that many
grades of coal can be prepared, transported, stored
and burned with the same equipment without physical
difficulty; higher efficiency can be obtained than with
any other means of combustion, and low grade fuel
may be used which will not burn efficiently by any
other means. Powdered coal is not dangerous to
handle, and it is a smokeless fuel giving remarkably
flexible control.	J

Mr. A. E. Maginnis (Electrical World) reports that
as prepared in the plant of the Pacific Coast Coal
Company, coal is crushed to f in. and fed to a Ruggles
drier, consisting of two nearly horizontal steel
cylinders one within the other, the space between them
being the drying space. The dried coal is ground in
a Raymond mill. The degree of fineness should permit
of complete combustion whilst the fuel is suspended.
Finer grinding is needed by coal with a high propor-
tion of fixed carbon than by coal with a high volatile
content and ash with a high melting point. In a par-
ticular case the best results were obtained when 95 per
cent, of the ground coal would pass a 100 mesh screen,
and 85 per cent, would pass a 200 mesh screen.

It is important to keep the ground coal dry and to
provide sufficient air velocity and sufficient furnace
space for combustion to be completed whilst the fuel
is suspended and before the boiler tubes or brickwork
are reached. A “ Dutch oven” extension on the front
of the boiler provides the space required. A slag pit
should be provided if the boiler is to be forced, or if
coal is to be used which slags at comparatively low
temperatures.

Tests on a 300 horse-power B. and W. boiler burning
four grades of powdered coal (some of very inferior
quality) showed efficiencies from 74 to 77 per cent.
A description is given of powdered coal plant in use
with ten boilers, the total rating of which is 4,100
horse-power. The coal-grinding plant is capable of
grinding 20 tons per hour, using heavy cast iron balls.
Leading particulars are given concerning other
powdered coal equipments.

Gas Circulation in Hot Blast Stoves.

Mr. A. D. Williams (Blast Furnace and Steel Plant)
discusses the general laws of gas circulation in the
regenerator checkers of hot blast stoves and furnaces,
based in part on the research work of Grum-Grjimailo.
There is a definite relation between the amount of
heating surface, the thickness of the checker wall, the
heating and cooling time, the velocity of the gas, and
the cost of checker and of fuel. Curves are given
showing the time required for the central plane of walls
of different thickness to reach any given percentage of
their surface temperature.

These curves reveal that a checker wall may be too
thin for economical work, and that the rate of heating
varies as the square of the thickness. If the walls
are too thick, the heat gradient may be curved, due
to an increased distance between the isothermals at
the cold end of the checker. There will be too much
reserve heat storage capacity, or the interchange will
be inefficient. In connection with the wall thickness
it is necessary to consider the size of the checker
opening. This also hinges on the cleanliness of the
gas. The heat conductivity of the dust and cinder
deposit is only about one-tenth that of the brick. Too
large a checker opening is a disadvantage, as it reduces
the weight of the brickwork and is not efficient in
transferring the heat to the air; 6 inches is about
the' maximum limit, and smaller openings are de-
sirable, except with dirty gas. With clean gas, 3| to
4J in. openings are to be preferred. If convection
currents could be prevented, it would take about 60
seconds to heat a 3 in. square column of air to 80 per
cent, of the checker temperature. However, the con-
vection currents greatly reduce -this time.

The Future of the Oil Engine for Ship Propulsion.

According to Engineering, the present is a time of
change, and there are two reasons for that. In the
first place, the war has brought about a shipping situa-
tion which is unprecedented in the history of the
world. There is a demand for ships to-day such as
never existed before, but there is at the same time
just as real and as strong a demand for the men to
run those ships. The heavy oil engine is one of the
various possible ways of driving a ship, providing the
ship be not too large. Its fuel economy is a direct
value in ship operation, since it gives a larger cruising
radius or the maximum possible cargo capacity. It
furthermore is peculiarly adapted to a ship, in view
of the fact that we are facing a labour shortage in
ship operation, and the heavy oil engine ship can be
operated with less men below the deck than any
other type of vessel ever produced—except, of course,
the small gasoline boat. The war, then, has brought
to our attention this heavy oil engine as a possible
motive power for the smaller of these new merchant
vessels as well as naval vessels, though more merchant
than naval. And it is a fact that shipping people

are considering this question to-day all over the
country, but most of them are afraid to act. They
would like to, as near as can be found out by talking
to them, but they .are afraid to act. The time is not
far distant when they will have to act or lose some-
thing by not acting.

INDIAN AND COLONIAL "NOTES.

Australia.

Conciliation Courts.—The State Minister for Labour and
Industry has been endeavouring for a considerable time
to establish concilation courts, but so far his efforts have
received little assistance from the unions affected. The
Northern Delegates’ Board has decided not to nominate
its representatives for the concilation committees and the
Coal Court. In the south the position is complicated by
the refusal of the old Federation to accept the committee.
In the west there is a strong feeling in favour of the adop-
tion of the scheme, and the Minister is hopeful that the
Federation will co-operate in the creation of conciliatory
machinery for the whole of the industry.

Unequal Distribution of Trade.—Considerable dissatis-
faction exists on the south coast and in the northern
districts, owing to the unequal distribution of the trade.
The secretary of the Australasian Coal and Shale Em-
ployees’ Federation complains that for some time past a
number of collieries in the lower end of the south coast
district have only worked half time, while at the northern
end the collieries have practically worked full time. The
general opinion is that if there is not sufficient work for
all, such work as there is should be distributed as equally
as possible. The miners contend that as there is very little
difference in the quality of the coal, there ought not to
be any real difficulty in making this arrangement.

Canada.

The situation in Canada as regards the supply of coal
for the coming winter is becoming increasingly serious,
especially in the Western Provinces. Owing to the greatly
increased home demand for war industries, the amount
of anthracite obtainable from the United States will be
greatly reduced, and confined largely to the provinces
of Ontario and Quebec, which have no coal of their own.
The West, more especially the Province of Alberta, having
extensive mines of bituminous coal, has been warned to
provide for its own requirements, as little, if any, of the
American anthracite will be shipped further west than
Winnipeg. The American operators are treating Canada
on the same footing as their own country, where the
people of the Western States have been told to burn their
own coal of an inferior quality, so that the output of
the eastern mines may be reserved for the Eastern States
and the section of Canada dependent on the American
mines. But the warnings of the Fuel Controller, urging
dealers to put in their orders early, have had little effect.
The public, accustomed to the American anthracite, de-
layed buying their winter supplies of the inferior domestic
article. Consequently, work was slack at the mines for
lack of orders, and production has been far below the
amount required to prevent actual hardship among con-
sumers. C. A. Magrath, the Canadian Fuel Controller,
has issued a strong appeal for immediate action, but the
latest reports from jMberta are to the effect that many of
the mines are still idle, or production much curtailed for
want of orders.

Conditions are somewhat better in Eastern Canada,
though the supply is much short of normal, and many
consumers find it impossible to have their orders filled.
It is hoped to avert serious consequences by a rigid
rationing system, under which those consumers whose
usual supply for the season exceeds six tons will only
be entitled to receive 70 per cent, of their customary
supply, those who violate this regulation being threatened
with the seizure of the excess. Many municipalities have
received a supply of wood as a substitute fuel, the Pro-
vincial Government of Ontario having permitted them to
cut cordwood for fuel in Algonquin Park.

The project of utilising the extensive lignite deposits
of Western Canada by briquetting, so as to furnish a
commercial fuel, is taking practical form. The Canadian
Government has concluded an agreement with the
Manitoba and Saskatchewan Governments, under which
the sum of 400,000 dols. will be raised for this purpose,
the Dominion Government contributing 200,000 dols., and
the others 100,000 dols. each.. A plant will be established
for carbonising and briquetting lignite and recovering
valuable by-products, including oil, pitch, ammonia, etc.,
which will be built and operated by a commission known
as the Lignite Utilisation Board. It consists of R. A. Ross, •
consulting engineer, of Montreal, chairman; J. M. Leaney,
of Winnipeg, provincial electrician, of Manitoba; and
J. A. Sheppard, a prominent business man of Moose Jaw,
Saskatchewan.

Calling-up Notices Cancelled. — Calling-up notices at
present pending to coal miners are being cancelled, and
no further notices will be issued. There is good reason to
believe also that leniency will be shown to coal miners
who are absentees, provided, of course, they are working
in the mines, and that they will not be prosecuted.

Midland Counties Institution of Engineers.—The annual
meeting of the Midland Counties Institution of Engineers
was held at University College, Nottingham, yesterday
(Thursday). Mr. G. Spencer presided. The election of
officers for the ensuing year resulted as follows: Presi-
dent, H. E. Mitton; vice-presidents, Major T. P. Barber,
Capt. Sir H. Dennis Bayley, K.B.E., J. Mein, C. Dickin-
son, C. M. Haslam, and C. R. Hewitt. The president
said he thought that the result of the year’s working was
very satisfactory.

Wigan Mining and Technical College.—The 62nd session
of the Wigan and District Mining and Technical College
commences on Monday, September 16. The scholarships
include the “ Alfred Hewlett ” Mining Scholarship (£52
per annum for three years), the “ Richard Christopher ”
Mining Scholarship (£50 per annum for three years),
the “ George Bradshaw ” Mining Scholarship (£50
per annum for three years), the “ Peace Memorial ”
(Trustees) Mining Scholarship (increased from £35
to £52 per annum by the generosity of Mr. Alfred
Hewlett), the “ Peace Memorial ” (Alfred Hewlett
Mining Scholarship (£52 per annum for three years),
the “ College ” Scholarships in Mining (two scholar-
ships of the annual value of £50, tenable for three
years at the full-time Day Mining Course), and the Osbeck
Mining Scholarships (two scholarships, each of the value
of 10 guineas per annum. Courses have been arranged to
meet the needs of different classes of students in the
College Mining Department,