The Sun.
London, England, 1854-04-19 00:00:00

rII ST.

INSTITUTION OF CIVIL ENGINEERS.

At the last meeting of this society, Mr. James Simp-
, son, president, in the chair,- the evening was entirely
devoted to the, discussion of the papers by Mr. J. Simp-
, son, jun., and Mr. C. Wye Williams, "On the Manage-
, ment of the Engine and other Furnaces, and the
Prevention of Smoke." An explanation was given, by
, means of a diagram, of several divisions of the process,
leading to the combustion of gas in furnaces. The first
division gave the mere relative gross bulk of gas and air
required for combustion. In the second the mechanical
mixture of the gas and air was described, such mixture,
or contact of atoms, being essential to the subsequent
chemical union. The third exhibited the several consti-
tuents ofgas and air—the former being hydrogen and car-
bon ; thelatter, oxygen and nitrogen; the relative volumes
of each were given, and it was shown that ten volumes of
air were absolutely essential to the combustion of one
volume of gas. The fourth division showed the propor-
tions in which those constituents combined. The nature
of flame and smoke was examined ; showing that the
intense heat, caused by the combustion of the hydrogen,
was the direct cause by which the temperature of the
.carbon was raised to that of white heat, which produced
the luminosity of flame. This process was illustrated by
reference to the mode of producing the intense heat and
luminosity required for the oxy-hydrogen miscroscope.
In the latter the piece of lime or carbon, on which the
heat was projected, was instantly raised to the tempera-
ture of extreme luminosity, neither the lime rior carbon,
however, suffering rapid combustion. In the former, the
carbon of the gas vfas raised, by the same means (the
combustion of the hydrogen) to the high temperature,
but could not suffer combustion until it was brought into
contact, in its turn, with its equivalent of the oxygen of
the air. If, however, that supply of air was not pro-
vided before the carbon lost its high temperature, it re-
turned to its previous and natural state of a black sub-
stance, and gave the black character to the products,
called smoke. The first important condition was then-
shown to be, the providing the required quantity of air.
Reference was then made to the area, recommended by
some authorities, as being sufficient to allow the quan-
tity to enter a furnace. It had been considered, that
even half a square inch of aperture for each square foot
of furnace grate was sufficient for the combustion of the
fuel. This was, however, stated to be insufficient for
practical purposes, The 'proper area for admission being;
frona 4 to 6 square inches for each foot of grate, accord-
ing to the extent of draught and the nature of the coal.
This serious difference was supposed to have been caused
by an erroneous calculation of the rate of the current
of air entering. For, if half a square inch of area was
all that was allowed, the air must have a velocity ten
times greater than could be shown to have ever been
attained. Thus, supposing a furnace to be '4 feet by 2
, feet 6 inches, equal to 10 square feet of bar surface, this
would effect, a combusion of 2 cwt. of coal per hour,
and require, for the gas alone, a supply of 10,000 cubic
feet per hour, or for 20 cwt. of the coal, 100,000 cubic
feet. The following comparison of velocity of the en-
tering air for the supply of the gas gave some idea of the
cause of underrating 'the required area of admission :

Air aperture per
square foot of
grate.
6 square inches t
6 ~

Velocity of Quantity of air Quantity for
draught per per each ton of
second. hour. coal.

, 5 ft. per sec.! 7,500 cubic ft. 75,000
tat 10 ~ 15,000 „ 150,000

Then, if the area were reduced to half a square inch, it
would require a velocity of 80 feet per second to pro-
vide for the admission, within the given time, of the
necessary quantity. By close observation, by means
of an aerometer, the velocity of the entering current
was estimated at from 8 to 10 feet per second, if the
draught was good ; and froin 5 to 8 feet when it was but
moderate. Again, it was observed that, by admitting
the air through numerous thin films or divisions, the
velocity was necessarily reduced by mere friction through
so many half-inch orifices as were exhibited in the models
and drawings on the table,. The mode of admitting the
air by numerous small orifices, as practised by Mr. C.
Wye Williams, ::cya:s then considered, and it was shown
that the great object to be effected was, the division of
the air, on its admission to the furnace, so that no more
atoms were brought into contact with the atoms of the
gas, at any one momont, than were required for their
successive union and combustion. If this were the case,
combustion and heat would be generated, continuously,
as the gas and air came into contact. If, however, the
air entered in a body, or even in a film, in larger quan-
tities than could be taken up by the gas, before the teni-
perature was lowered, a refrigeratory effect must be the
consequence, smoke would be formed and fuel would be
wasted. It was asserted that the phrase " burning
smoke was improper, inasmuch as the smoke did not
exist until the gases had left the furnace ; this was de-
monstrated by a diagram, showing that on distilling
coal in a close vessel, and forcing in a small quantity of
air, a jet of gas issued, which, on ignition at the ori-
fice, was almost colourless, then merged into flame, and
ultimately became opaque smoke. It was stated, as an
argument for the necessity for some stringent measure
with respect to the engine furnaces in all large towns,
that in the last nine years, between 1845 and 1853, 801
new chimney shafts-had been erected in the metropolis
for manmfactories, breweries, &c. Some few of them
might have been merely re-built, after destruction, but
the large majority caused additional impurity in the
London atmosphere. -From 1845 to 1851 the greatest
number bt r
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too much stress had been laid on the chemical part
of the subject, as also, that-the statement of its being
" impossible. to burn smoke" had complicated that
which was; in itself, a simple question. All that the
public cared about was, that by some simple means the
black or brown visible smoke should be prevented from
forming, or be consumed, if its formation was inciden-

tal to perfect combustion. The air necessary to per-
form this could be admitted any either through
a split bridge, by the fire-door, by an infinite num-
ber of holes, between plates with narrow spaces, or by
others arranged like Venetian blinds. Practically, the
end could be attained by the mechanical systems of
Juckes, Hazeldine, Hall, and others, or by the double
furnace boilers of Galloway, Rose, M`Gavin, and others,
or by the systems of Williams, Prideaux, and many
others. The objections alleged against all these plans
were illustrated, and 'it was stated that, with ordinary
boilers, the admission of air invariably reduced the eva-
porative power, or caused waste of fuel, unless there was
a sharp draught, and spare boiler power ; but that when
these latter requisites were secured the air might be ad-
mitted in any way practically found most convenient.
The arrangement proposed by Mr. Prideaux was noticed
as the most creditable mechanicism yet brought forward,
but its neatness was its only recommendation, as it could
not improve the draught, nor could it aid in " burning
smoke" better than would be done by merely leaving the
furnace door ajar. The remarkable coincidence between
the arrangement of the parallel plates in Prideaux's fire
door and that of William's well-known and long-prac-
tised system was also noticed ; it being stated, as funda-
mental principles, that in the former system " the door of
the furnace should be double, and the air should pass
into the furnace through a series of perforations in the
inner plate. By this arrangement three important re-
sults are secured-1. The heating of the air. 2. Its
subdivision into minute jets. This is the precise prin-
ciple and operation of Mr. Williams's argand furnace.
3. The keeping of the outer surface of the furnace-deer
comparatively cool, and thereby both economising heat
and preventing its radiation outwardly, to the aunoy-
ance of the attendants." Drawings were exhibited oc
double flue and double furnace-boiler, whose action was
stated to be very satisfactory ; the proportion of air
space provided, in that care, was one square inch to each
square foot of grate area. The admission of too large
quantities of cold air immediately behind the bridge had
been found prejudicial, and the system of admitting the
supply of air through the perforations in the fire. door was
generally preferred. The system of alternate firing, and
of having ample boiler space and a good draught, was in-
sisted upon. It was stated, on behalf of the mechanical
methods of firing, that at Price's candle manufactory, at
Vauxhall, three methods, Jucke's, Hazeldine's, and
Hall's were employed with success. The general prin-
ciple of a continuous supply of fuel, at the front of the
fire, by means of moving bars, carrying the coal for-
ward, was common to all these apparatus. The air was
admitted only from below, and between the bars, which
were always covered with fuel. The objections urged
against these machines were, the first cost, and their
liability to derangement. These, however, were now di-
minished, particularly with those of Juckes and Hazel-
dine, to which preference was therefore given in the con-
struction of new furnaces. They were found to pro-
duce almost perfect combustion, and to make a great
saving of fuel, with other practical advantages. Two
cases were mentioned, as illustrative of the necessity
of admitting the air above the incandescent fuel—the
first was that of the ventilating furnaces in pits where
it was essential to raise, to a certain temperature, the
largest amount of air by passing it through or over
the fuel in a furnace, in such a manner as to render the
air as light as possible, and not to encumber it with
smoke ; the second was that of coke ovens, which were
now constructed in pairs, and were worked alternately,
in such a manner that the early smoke from one oven
mingled with the later development of gases from the
other oven ; by this means the appearance of any opaque
smoke was entirely prevented. In reply to the argil-
meats in the papers, and to some of those used by the
speakers, it was urged, that even with the best con-
struction of furnaces, skilful firemen must be employed,
and that it was desirable the subject should be divested
of all complexity, and should be rendered clear to
the meanest capacities. Instances were given of
the advantageous employment of mechanical methods
of stoking, particularly at the brewery of Messrs.
Truman, Hanbury, and Co., where sixteen sets of
Juckes's apparatus had been - used for several years,
and had induced a great saving of fuel, as well as
insured undeviating regularity of temperature in
the furnaces. The self-acting systems practised by
Brunton and by Parkes, many years since, were al-
luded to, and the reasons for their use being discontinued
were given. The alleged defeots of these systems were
Shown not to exist in the apparatus of Juckes, Hazel-
dine, and Hall, but that even they were up to this time
unfit for use in steam-vessels, where, it had been
imagined, that mechanical means of firing would have
been most advantageous, but where, in reality, the heat
in the furnaces was so intense as to destroy any ma-
chinery attached to the fire-bars. The success attend-
ant on Mr. Ilouldsworth's system for preventing smoke,
and on his invention of the metal rod pyrometer, was
described. The general result of the investigation ap.
peared to be, that, although for certain large establish-
ments, the mechanical methods of firing were success-
ful, it could not be expected they would be adopted for
every furnace in the smallest manufactory ; therefore, a
good system of mingling a due proportion of atmos-
pheric air with the gases evolved during combustion
was essential, and the method employed by Williams
&Heusi to fulttie, otaind coaditiout.