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CURRENT SCIENCE

Effect of Removal of Benzol from Coke Oven Gas.

It is generally stated that the removal of benzol from
coke-oven gas has the result of causing a diminution in
the calorific value of the gas of about 10 per cent. In
a recent paper, says the Gas World, a well-known writer
gave the following particulars:—	'

Calorific value before extraction of benzol ... 560

,,	,, after ,,	... 511

Experimental proof has also been brought forward at
times, and in such cases a diminution of About 7 or 8
per cent, is generally observed. The benzol is removed
by means of creosote, oil and the calorific value of the
gas determined by calorimeter. There is, of course, a
certain amount of carburetting action, due to the
creosote oil itself, so that such determination is not
absolutely accurate. The following method of calcula>
tioii can be applied, and gives fairly approximate
results:—

Let the yield of gas per ton of coal

be, say ......................... 11,000 cu. ft.

Calorific value of the gas with

benzol, say	...... 530 B.Th.IT.

Total heat value of the gas = 11,000 x 530 — 5,830,000B.Th. U.
Let the yield of benzol be ...... 2| galls, per ton of coal.
Let the calorific value of the benzol

be______ _____................................ 17,500	B.Th.IT. per lb.

Let the specific gravity of the
benzol be	_________	0*875.

The weight of 2f galls, of benzol is
then............................................ 2 75 x 0*875 x 10

= 23*06 lb.

Calorific value of benzol per ton

of coal_________ __.....................= 23*06 x 17,500 B.Th.U.

= 403,550 B.Th.U. .

Hence the removal of the benzol causes a diminution in
v -.fi i e 403,556 x 100 • n.h	. ■

calorific value of ————------- =69 per cent.

5,830,000	■

The various quantities taken can be adjusted to meet
particular cases.	‘ •

Dredging for Coal.

Although the coal miner has frequently invoked the
forces of Nature to assist him.in his yrork, it is probable
that an instance of. collaboration, Tecorded by F. W.
Brady, in the Colliery Engineer (October 1914), is
without precedent. One of the streams traversing the
anthracite region in Pennsylvania has been dammed,
the water above the dam forming a cooling pond for a
power-station on the bank. On cleaning but this pond
some three years ago, it was found that the dam was
filled with good coal, which had been deposited each
time the brook was in spate, the- source- being the
numerous culm piles, breakers .and washeries above the
dam, as well as the loaded trucks running along
the banks of the stream. The power station imme-
diately set about recovering this coal by means of a
dredger. The plant consists of a scow with dredging
machinery, a floating pipe line, a booster pumping
station on shore, a screen shaker and coal loader. In
1913 over 30,000 tons of coal were recovered, at a labour
cost of about 14c. per ton. The “business endXjpf the
system consists of a. float carrying an electrically-ctriven
centrifugal pump capable of passing 4 in. solids. The
intake,;!^ a 14 ft. length of 6 in. spiral riveted pipe
attached to the pump by means of a, swivel joint, and
capable of being lowered or raised by a windlass» An
important feature is an agitator .mounted on a shaft
extending the full length of the pipe ; it consists of
straps of steel riveted on to a boiler-plate disc, 18 in. in
diameter, and is operated by a brake-wheel at the fop of
the pipe., The water carrying about one-tenth solids is
delivered through the floating pipe-line to the booster
pump on shore, which raises it to the shaker and
screen, A considerable quantity of ash is reclaimed
with the coal, but the latter has a heating value of
11,000 B.T.U. .

Chlorides in Coal.

In a paper read before the Society of Public Analysts,
A. de Waele describes a case of abnormal corrosion of
the tube of an economiser, which was traced to. the
presence of chlorine in the coal used. Comparisons of
total chlorine, as determined by combustion in lime and
chlorine as soluble chlorine by extraction of the powdered
coal with water, showed good agreement, averaging
a bout, 0*22 per cent. Cl. These coals being traced to
their origin of Midland coals from the brine districts,
Welsh coals supplied to another boiler, where corrosion
was merely normal, were found to average OTO per
cent. Cl, the ignition and extraction analysis, moreover,
agreeing. In a. further paper read at the same, meeting,
Stanley W. Bridge, B.Sc., F.I.C., described the results
of an examination of a number of samples of coke
derived from English coals and cannels from different
districts, with the object of determining the amount Of
soluble .chlorides and total chlorine. The results show
that very considerable variations occur * in the amounts,
and- that the variations, are in general of the same order
as in the coal. The proportion of the chlorine remaining
in the coke depends, however, also to a large extent on
the temperature at which the coal has been carbonised,
the coke obtained from the same coal by low tempera-
ture carbonisation being much higher both in soluble
chlorides and total chlorine than that obtained at a high
temperature.	.	.

In the Days of Watt.

In delivering the James Watt anniversary lecture
before ; the- Greenock Philosophical Society, Pi-of. J. D.
Cormack gave some interesting reminiscenses of the
days^when Watt was living. .. He was born.in 1736 and
died in 1819. Thus Watt was dead five years before
Lord Kelvin saw the light. As a boy Watt saw .the ’45/.
and during hisilifetime occurred the American War of:
Independence/ the French • Revolution, Trafalgar and :
Waterloo. The story of his. life was .well-, told by

THE COLLIERY GUARDIAN.

.

AND TECHNOLOGY.

Prof.* Cormack. As he very truly remarks, when we
look back to-day on Watt’s work, in order to rate it at
its true value we must constantly bear in mind tha£ it
was accomplished during the reign of the phlogistic
theory, and at a time when the nature of heat was only
suspected, and its true relationships were unknown,
We must also take account of, and make duo allowance
for, the materials, tools, and craftsmanship of his day.
As regards craftsmanship, it was excellent in light
work, such as clocks, watches, astronomical instruments,
&c. ; but for heavy work it was hampered by the lack of
suitable tools and. materials. We read of the difficulty
of boiing his cylinders, of the crude way in which,the
pistons, to be steam-tight, were packed—sometimes
with paper, cork, putty, pasteboards, and old hats ; and
of his satisfaction when the difference in diameter
between the cylinder and piston at any part was not
more than the thickness of a shilling. Early boilers
were made of copper with lead domes; early cylinders
were hammered out or made of cast brass ; cast iron was
difficult to bore out, and needed to be about 1 in. thick,
whereas brass could be made £ in, thick and conducted
away theuheat faster, an advantage in the early type of
Newcomen ^engine, but a disadvantage in the Watt
engine. The7 state of scientific knowledge in the days
of Watt was crude as measured by modern standards.
.Physics was still in its infancy, and we learn that Watt
him self was impelled to learn the German language in
: order to study Leupold’s	JWachinarum, an

elaborate work of 10volumes published in 1724.

Economic Utilisation of Coal.

In a lecture delivered before the Department of
Chemical Engineering, University of Pittsburg, Penn.,
Mr. Horace G. Porter, of the United States Bureau of
Mines, showed- that about £50,000,000 are wasted
annually in the United States alone owing to inefficient
methods of use. Of the enormous output of coal in that
country, amounting to 570,000,000 tons in 1913,: he
estimated that the United States uses the following
percentages for home consumption:—

Domestic fuel................ 21

Other heating of buildings ..... 15

Coke and gas __................ 13...

LoconiDtives and steamboats ... 19

Industrial power ............. 32

Probably 80 per cent, of the coal consumption is
diiectly burned in air, whereby there is a great loss of
efficiency. He then showed that of the two chief
components of coal, the cellulose bodies and the resins,
the latter have a higher hydrogen content and less
oxygen, decomposing by heat into hydrocai boris and
hydrogen, while the celluloses yield principally the
paraffin hydrocarbons and the oxides of carbon. The
resinous bodies are contained most abundantly in the
coking coals of the Appalachian region. On slow
distillation the “ primary products ” are composed
mainly of water, hydrogen sulphide, carbon dioxide,
and various saturated and unsaturated paraffin hydro-
carbons and hydrogen.. Most of the constituents of
coal gas, coal tar, and. gas liquor, such as benzene,
naphthalene, pitch and ammonia, are the products of
secondary decomposition of these primary products.
Amongst the volatile bodies are various incombustible
gases. It is the cellulose bodies that chiefly yield
these, and as the younger coals, such as lignite, are rich
in celluloses, these produce in burning more of the
oxidised non-combustible gases than the more mature
coals.' Mr. Porter proceeds to criticise the theory of
Dr. Wheeler that coal contains certain substances which
decompose only above 700 degs. Cent. He thinks the
large amount of hydrogen appearing above this tempera-
ture is due to the secondary breaking down of the hydro-
carbons first liberated, and of' the partially carbonised
solidjpraterial left behind, these substances not having
been present as such' in the original coal. The author
proceeds to show that we have not yet solved the problem
of coking coals, laboratory experiments not having been
satisfactory. He recalled experiments in Germany, in
which cellulose has been converted into coal by great
pressure and moderate heat. In the practical burning of
coal in the furnace it is of more importance to regulate
the rate at which the volatile matter is given off than
the total quantity produced. Thus Pittsburg coal
produces more combustible volatile matter than
Wyoming coal, but the latter liberates more in the
early stages of heating. He then discussed problems of
oxidation and spontaneous combustion, and showed the
deterioration of coal on storage is due to oxidation, and
not to doss of volatile matter.

The “ Cracking ” of Heavy Oils.

Prof./V^ivian B. Lewes recently read a paper before
the Institution of Petroleum Technologists on “ The
Chemistry of the Cracking of Heavy Oils.” The term
“ cracking ” is an Americanism and implies the resolu-
tion of a complex molecule into simpler molecules
without actual decomposition or total disruption. At
the same meeting Mr. William A. Hall read a paper on
“ The Cracking of Oils with a View to Obtaining Motor
Spirit and Other Products.” As regards the actual
chemistry of the process of cracking, Prof. Lewes
showed, by means of graphic formulae, how methane
and the higher membei s of the paraffin series of hydro-
carbons are built up on the open-chain theory. Thus
the paraffin and olefine series can be represented as
CH3 — CH2 — CH3, which is the formula for propane.
Dodecane could thus be shown by

Hex- f CH3 - CH2 - CH2 - I CH2 - CH2 - CH2 T Hexy-
ane Z,CH3-CH2-CH2- | CH2 - CH2 - CH2 \ lene,
by writing the chain in two lines instead of a single
line. Now,, on dissociation the left-hand half of this
molecule becomes the, paraffin hexane, and the right-
hand half becomes the' olefine hexylene. As .written

March 19, 1915.

_______	____________________________________

above* however, hexylene is an unsaturated hydro-
carbon, having an open end to the chain and capable of
forming additive compounds with bromine, &c. But
under ordinary conditions of commercial cracking the
hexylene chain closes up into a ring compound, forming,
instead of the unsaturated hexylene, the saturated ring
substance hexahydrobenzol, one of the naphthene series
of closed j ring compounds. These naphthenes differ
from the olefines in their behaviour when further
heated. The olefines are merely resolved into simpler
members of the same series, whereas the naphthenes
shed off the extra hydrogen atoms and are converted
into, aromatic hydrocarbons such as benzol, toluol,
xylol, &c. In Mr. Hall’s paper, a description is given
of his process of cracking, which differs from Burton’s
process in passing, the vapours through heated tubes
instead of into a still. He thus secures more uniformity.
Difficulties due to. deposition of carbon in the tubes
are avoided by providing for a sudden expansion of the
vapours, whereby. 99 per cent, of the carbon is deposited.
Crude cracked spirit is yellow and has a resinous odour
both of which can be removed by refining, although
tending to return: on ageing. Mr. Hall describes
methods of overcoming this difficulty.

__________________________

THE GERMAN AND AUSTRIAN COAL
AND IRON TRADES.

We give below further extracts from German
periodicals that have reached us,1 showing the course of
the coal and iron trades in Germany and Austria:—

Fuel Shipments from Ruhr Harbours in January.

Shipments to Coblenz .and places higher up river,
431,183 tons (333,968 tons); to place below Coblenz,
15,673 tons (18,291 tons); to Holland, 171,502 tons
(342,582 tons); to Belgium, 109,079 tons (219,857 tons);
to France, nil (22,107 tons); to other destinations, 6,315
tons (22,415 tons). / Total shipments from: Ruhrort,
457,279 tons (575,545 tons); Duisburg, 106,428 tons
(169,316 tons); Hochfeld, 2,885 tons (12,423 tons) ;
Rheinpreussen, 71,687 tons (76,258 tons); Schwelgern,
34,951 tons (59,074 tons).; Walsum, 60,522 tons (66,604
tons); aggregate, 733,752 tons (959,220 tons) ; a deficit
of 225,468-tons. During the first six months of the war
the total deficit in the shipments amounted to 5,366,876
tons, as compared with the corresponding period of the
previous year, 2,536,244 tons of this deficit being on the
shipments to Holland, 1,595,433 tons on those to
Belgium, and 171,160 tons on those to France.

Ruhr Coal Market.

During February the coke distribution attained
50 per cent, of the actual participation, which is regarded
as an indication that the use of coke as industrial is
increasing. In fact, its employment has become
essential, since it is only in this way that an adequate
supply of fuel can be obtained. Enquiries for broken
coke are certain to increase, because the collieries are
using larger quantities of this grade in preference to
the dearer coal. On the other hand, the provision of a
supply of coke will be facilitated by the new arrange-
ments made between the Coal Syndicate and the pits,
according to which the large coke will be passed through
a breaker and sold as it is, without first being classified.
The increased production of coke has not lessened the
scarcity of coal, and the fluctuations in the output
of the former have introduced such an element of
uncertainty as to the relative amounts of both fuels
available, that business for delivery after April 1
has been considerably interfered with, whereas, in
ordinary years, the bulk of such contracts have been
settled by this time. The agreement for the renewal
of the Syndicate has already been signed by most
of the members ; and between now and the autumn it
will be necessary for the prevailing differences of
opinion and interests on the part of the dissentients to
be settled. The negotiations for this purpose are in
the hands of a small committee which is investigating
each case, and will report to the renewal committee.
It is also reported that negotiations between the
Syndicate and the fiscal authorities have been resumed.
The advantages of combination are admirably demon-
strated by the present situation, for without it the
systematic distribution of fuel among consumers, both
in the home market and in neutral countries, would
have been impossible, and prices, instead of remaining
moderate, might have risen to the unusual extent that
they have in England.

Bar Iron Market.

The Cologne District Bar Iron Merchants’Association
has fixed the following base prices for bars, rods and
plates for delivery from stock in any quantity :—Mild
steel bars, 155 mk. per ton (20 mk. extra for Mannstaedt
iron and T’s and L’s under 30 mm.) ; welding ba»s
200 mk.; hoop ir n. 175 mk.; thin plate (below 5 mm.),
185 mk. ; heavy plate, 170 mk. ; corrugated sheets,
180 mk.; horse shoe bars, &c., Siegen brand, 210 mk.;
Haas brand 230 mk. For quantities above 2| tons of
each kind, special rates by arrangement.

Coal and Iron Market in Upper Silesia.

During February, the coal market remained unchanged,
except for increased difficulties of transport to certain
districts ; and as these districts are mostly those
usually supplied with English coals, the demand will
certainly become very active for a considerable time.
However, the home market has proved capable of
absorbing the whole output up to the present, without
its requirements being fully satisfied, so that, even in
view of the, occasional scarcity of transport, stocks are
comparatively insignificant. Tfie cpke market is also
in a satisfactory; condition, there being no appreciable
stocks of any grade. The actiye demand has stimulated
the .output, but. .attempts in this direction have, been
hampered .by the scarcity of. coking coal.,. Prices are