Improvements in the Process of and Apparatus used for Coking.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Process of and Apparatus used for Coking.
1, JOHN BOWING, of Tilbury, in the County of Essex, Consulting Chemist, do
hereby declare the nature of this invention to be as follows:-
I have found when coking coal, and especially when coking such coals as
coke with difficulty that the success of the operation depends to a large extent
upon the way in which the temperature is regulated.
My present Invention relates to certain Inventions with respect to which
Leters Patent have been granted to me and more particularly to the methods of
coking for which Letters Patent 16622 of 1892 were granted to me in which the
heat was caused to travel gradually through the mass either radially or otherwise
so as to obtain the advantages therein referred to.
The coking action appears to commence at about a temperature of 450 to 500°
centigrade but I have observed that if the coal be subjected for any considerable
time to temperature somewhat lower than this say from 150°C. upwards the
coal is more or less completely deprived of its coking properties and I further
observed that when once the coking temperature has been reached it is very
desirable that it should at all events not be allowed to fall during the operation
of coking.
I have also observed that one of the principal causes which leads to the fall of
the temperature in the charge which is being coked below the above mentioned
coking temperature is the large variations in temperature in the flue surrounding
the coking retort.
I believe as above indicated that the conditions which should be maintained
when coking in a retort so as to get the best results with uniformity are as
follows-First that the temperature inside the retort should be raised as rapidly
as possible to about 450° centigrade or more and should not subsequently be
allowed to fall below that temperature and secondly that the temperature outside
the retort riz., in the flue should be kept as nearly constant as possible and be
such that the above indicated conditions inside the retort may be maintained. I
find when working with a fire clay retort two feet in diameter with walls three
inches thick that this flue temperature is about 1100° centigrade but this will
vary with the size of the retort and the materials of which it is made.
In order to maintain the flue temperature it is of great importance in con-
structing these flues that the sectional area of the flue round the retort measured
at right angles to the direction of the gases should be the same as the sectional
area of the culvert or channel by which the gases are conducted to the flue
measured in the same way.

page_text: Improvements in the Process of and Apparatus used for Coking.
I, JOHN BOWING, of -Tilbury, in the County of Essex, Consulting Chemist, do
hereby declare the nature of this invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement:-
My invention relates to the manufacture of coke and chiefly from coal of the
kind usually regarded as unsuitable for coking, such for instance, as Welsh
Steam coal which has formed the subject of many attempts to convert into coke,
but these attempts have met with but little success on a commercial scale.
I have observed in the course of many experiments,
(1) That if such coal as herein before referred to is in the course of the coking
operation subjected to a heat far below the coking temperature for a sufficient
time it is more or less deprived of its coking property, for example I have found
that after coal has been exposed to a temperature of 150° C. for some hours a
coking action cannot subsequently be set up; and
(2) That after the coking temperature (which with Welsh Steam coal my
experiments show to be from 440° C. to 480° C.) has been attained the temperature
should never be allowed to fall to any great extent even although the variation
so caused takes place above the coking temperature, as an oscillation of the tem-
perature of the charge during the process of coking if it be considerable or
prolonged may result in complete or partial failure to coke.
The natural corollary to these observations is that for the successful
manufacture of coke the following conditions must be complied with, viz.:—
(1) The coal must be quickly raised to the coking temperature. In practice
all parts of a large body of coal cannot be thus heated simultaneously but the
supply of heat must be sufficient to prevent any part remaining for a long time
below the coking temperature.
(2) The supply of the heat for coking should be capable of being uniformly
maintained.
I have discovered that these conditions can be complied with by using an oven
containing a vertical retort (which is preferably made of a material of high
heat-conductivity) and which is entirely surrounded by a shallow flue in such a
manner that the whole area of the vertical walls is acted upon by the heating
gases, which flue has a sectional area at any point measured at right angles to the
flow of the heating gases equal or approximately equal to the sectional area of the
throats or culverts by which the heating gases are conducted into the said flue
measured in the same manner, the result of so proportioning the areas of the
said throats or culverts and flue being that the incandescent gases, which must
be suplied from the furnace (which may be adapted for either solid or gaseous
..fuel) in sufficient volume to fill the throats, maintain their temperature and
produce uniform heating over the whole area of the retort.
An oven which I have found in practice to give good results, is illustrated in
Figures 1 and 2 of the accompanying drawings, Figure 1 being a vertiacl section
and Figure 2 a horizontal section.
This oven comprises a plumbago retort a circular in transverse section and
having a height of say 10 feet with a diameter at the upper end of say 1 foot
10 inches and at the lower end of 2 feet 2 inches (this slight taper being provided
in order to facilitate the discharge of the coke) so that the heat has only to
penetrate a distance of about 12 inches. By employing this relatively great height
for the retort as compared with its diameter I provide for treating a large body

page_text: of coal in a comparatively thin section whereby I obtain the advantage on the
one hand that the coke formed near the walls of the retort is not deteriorated
to any great extent whilst the heat is penetrating the thickness of the coal
layer or section and on the other. hand I effect an economy of fuel as with this
cylindrical form of retort it is obvious that the area of coal surface upon which
the coking heat is acting gradually decreases as the heat penetrates and the
disproportion would be still greater if the diameter of the cylinder was increased.
The retort herein before described is provided with a removable bottom b which
as shewn is pivoted upon a stud c to permit of its being readily turned aside for
discharging the retort and which is adapted to be wedged up into a taper seat in
the base plate d and luted to hermetically seal it. At the top of the retort is
a cover having a tubular arm or elbow f through which the products of
distillation may escape. Surrounding this cylinder is a narrow flue g (herein-
after referred to as the cylindrical flue) the adjacent surface of the wall forming
which is coaxial with the axis of the retort so that the said cylindrical flue is of
uniform width throughout. In practice this width is say 3 inches which I find
sufficient to give satisfactory results while effecting large economy as compared
with flues of greater dimensions. At the lower end of this cylindrical flue
two or more horizontal flues i (hereinafter referred to as throats) the total
sectional area of which throats measured as before described is the same ог
approximately the same as the sectional area of the cylindrical flue at say the
centre of its height. The wall h is of sufficient thickness to ensure stability and
is faced on the flue surface with fire brick or other refractory material of low
heat conductivity to prevent as far as possible loss of heat by radiation.
are
If the total of the united areas of the throats was smaller than that of the
cylindrical flue the gases might escape through the latter without passing over
the whole area of the retort, whilst if the throats had a larger area unitedly than
the cylindrical flue eddies might be set up in the throats which would result
in imperfect combustion, a waste of fuel and uncertain temperatures.
The coal to be coked must be crushed fine in order that it shall lie very com-
pactly in the retort with the interstices as small as possible, to prevent the
formation of channels through which currents of heated gas might flow, and so
cause the premature partial heating of the mass, which would be detrimental to
the formation of coke as before indicated. In practice I have found that coal
crushed fine enough to pass through a sieve with 3/16 inch mesh gives good
results.
In using my apparatus the retort and also the flue walls must first of all be
heated to the required temperature which must be maintained throughout the
operation this being an easy matter for a skilled fireman by observing the
character of the flame; to ensure uniformity, however, fusion plugs having known
melting points or other forms of pyrometer should also be applied. In practice
the furnace and flues should be so proportioned that when the desired temperature
is reached the heated gases in the flues will on inspection exhibit what is known
as a "clean and hard." heat. The retort having been thus heated a charge of
coal which will completely fill the retort and in a wet condition is quickly
introduced into the said retort the falling of the coal and tamping, if necessary,
serving to thoroughly compact the mass the cover being finally applied.
As the firing of the retort is continued the heat which is uniform on all the
walls gradually penetrates the mass in a uniform manner so that a cylinder of
coke is formed which gradually increases in thickness until the coking heat has
reached the centre of the retort.
The steam and gases produced in the retort are driven towards the centre into
the uncoked coal and I rely on the bad heat conducting properties of the coal
and its compact condition to keep the temperature of the latter below the point
at which the detrimental action, herein before referred to, takes place until the
zone in which the coking heat is acting is so close behind the adjacent uncoked
coal that the temperature of the latter will be quickly raised. Furthermore the

page_text: condensation of some of the products in the uncoked coal of the charge serves
to enrich the latter.
The products of distillation which escape from the retort during the coking
operation and the cessation of which indicates when this operation is complete
are advantageously led into a closed condenser which is preferably one of the 5
bunkers in which coal for future treatment is stored. By adopting this course
the coal to be subsequently treated is more or less enriched and I obtain the
further advantage that the coal under treatment is converted into coke of better
quality than if the products of combustion escaped into the atmosphere or were
drawn off by an exhauster. I am not prepared to state definitely the cause of 1
this improvement in the quality of coke due to the discharge of the gases into
the closed condenser but I believe it to be due to the retardation of the flow of
gases which results, and if this retardation is the cause it can be produced in
other manners. As, however, this arranged of condenser forms part of the subject
matter of an aplication of later date than this aplication viz., No. 2786 of 1897
I make no claim to it in this specification.
Although I obtain practical results with the plumbago retort hereinbefore
described difficulties might arise in the commercial working of my invention
due to the deterioration or injury of the retorts and the consequent expense of
renewal, I therefore sometimes modify the construction of my apparatus in the
manner shewn in Figures 3 and 4 which are respectively a vertical section and a
horizontal section. This modified form of apparatus also forms part of the applica-
tion of later date before referred to and is therefore not claimed herein.
In these figures the retort a instead of being made of plumbago is of iron or
of steel and to prevent the destruction of this retort due to the action which the
furnace gases playing directly against it would exert I surround the said retort
by a wall h, so that the retort is practically enclosed in a muffle the heat being
conveyed to the retort by radiation from the wall of the muffle instead of by
direct conduction as in the foregoing case. The throats and flue around the outside
of this wall are constructed of uniform width and of equal or substantially equal
areas in the same manner and in the same proportions as the cylindrical flue
herein before described. With this last described form of oven the heat in the
flue is somewhat greater than when the gases directly play upon the retort, for
instance I have found that to obtain the required temperature in the retort
necessitates a temperaure of say 520° C. in he muffle to produce which a
temperature of say 900° C. more or less must be maintained in the flue.
This last described form of oven has also the advantage that slight variations
of temperature in the flue are less likely to be felt in the retort than is the case
with the oven first described.
Although I have described my invention as applied to the manufacture of coke
from-inferior coking coal it is to be understood that it is also applicable for the
manufacture of coke from coal of superior quality, in which case the coking
temperature and the mode of preparing the charges may have to be modified.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:-
1. The method of manufacturing coke consisting in subjecting coal finely
crushed and in a wet condition to treatment in an oven or retort constructed in
such a manner that the gradual warming or heating of the said coal for any length
of time prior to its being subjected to the coking temperature is substantially
prevented and that a uniform heat is maintained during the coking operation,
substantially as described.
2. A coke oven wherein a vertical retort of high heat-conductivity is surrounded
by a shallow flue of uniform width at all points so that the whole area of the
walls is acted upon by the heating gases and having a throat or throats through
which the furnace gases enter the said flue, the area or united sectional area

page_text: of the said throat or throats measured at right angles to the flow of the said gases
being the same or substantially the same as the sectional area of the flue around
the retort measured in the same manner, substantially as described.
3. In a coke oven the use for heating the charge of a flue as hereinbefore
described having, that is to say, such proportions that the sectional area thereof
measured at right angles to the direction of the flow of the incandescent gases
at any point shall be constant and equal to the sectional area of the culvert or
channel by which the gases are introduced measured in the same way.
4. A coke oven constructed, arranged and operating substantially as herein-
before described and illustrated in Figures 1 and 2 of the accompanying drawings.
5. The treatment of steam coal and other non-coking" coals by the herein
described process for the production of coke therefrom.
Dated the 26th day of November 1897.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.