Improvements in the Manufacture of Coal and other Illuminating Gas.
Year: 1899

page_text: Date of Application, 4th Mar., 1899
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Coal and other Illuminating Gas.
I, HAROLD GOVETT COLMAN, of 23, Stirling Road, Edgbaston, in the City of
Birmingham, Gentleman, do hereby declare the nature of this invention to be
as follows:-
My invention relates to the treatment of coal or other illuminating gas at the
stage of manufacture known as condensing and its object is to obtain increased
illuminating power and a more complete removal of naphthalene.
The first part of my invention consists in removing the finely divided tarry
matters suspended in the gas before the gas enters the condensers proper while
it is still warm say at about 100° to 140° F. This I preferably accomplish by
means of a centrifugal separator.
The second part of my invention consists in diverting a portion of the gas
before it is completely cooled and causing it to rejoin the gas in the condensers
at a point when the main part has been almost or quite cooled. The hydrocarbons
carried by the uncooled gas are thus added to the main body at a time when they
can be retained and aid the illuminating power. A liye pass may be used for this
part of the invention.
The third part of my invention consists in passing the gas before entering the
condensers through a washer containing warm hydrocarbons which removes the
naphthalene while adding to the gas à considerable quantity of vapour of low
boiling liquid hydrocarbons.
The treatment may be divided into three parts, each of which may be applied
separately, or any two of them together, or finally all three in succession.
In carrying my invention into effect under the first part: (1) The first object
to be attained is the complete removal from the gas before it enters the condensers
proper, (at a temperature of 100° 140° F.) of the whole of the tarry matters
already deposited in the liquid form, including not only the stream of tar flowing
with the gas, but also the whole of the tar still carried along mechanically in
current of the gas in the state of finely divided particles. These particles in the
ordinary method of condensation pass into the condensers and in the subsequent
cooling attract considerable quantities of the low boiling substances present in
the gas, which are thus run away to the tar well instead of being retained in the
gas; their removal at temperature at which their attraction for the low boiling
constituents is small. results in an increased quantity of benzene and other
vapours being retained in the gas than would otherwise be the case, the resulting
gas having thereby a higher illuminating power. Further, owing to the removal
of the high boiling constituents of the tar before the condensers are reached the
hydrocarbons which separate in the latter consists mainly of the light oils, which
of all liquids have the greatest dissolving power for naphthalene, and therefore
effect a more complete removal of this hydrocarbon from the gas.
The apparatus to be used for the removal of suspended tarry particles is of

page_text: the centrifugal separator type and a modification of the well known cyclone dust
collector is found quite suitable. The modification consists in devices for admitting
and discharging coal gas and for collecting and discharging the tar from the
surface to which it adheres.
(2) The second part of the process consists in the bye-passing of a portion of
the gas (10-20%) from the inlet of the condensers, (and after the apparatus
for removal of tarry particles, if such is employed) and reintroducing it into the
condensers at a point where the main stream of gas has been cooled to nearly the
atmospheric temperature. The secondary stream of gas being saturated with
hydrocarbon vapours at 100°-140° F., on meeting the main stream of cooled
gas deposits a portion of these as a mist or fog of light oils, which exposes an
immense surface to the gas. An interchange then quickly occurs between the
particles of the light oils and the gas, the former taking up a portion of the light
oils as vapour, while the still liquid portions of the latter dissolve naphthalene
from the gas.
The result is therefore the same as in the previous case viz. that the low boiling
constituents of the tar are more completely retained in the gas and the naphtha-
lene is more completely removed.
If the tarry particle separator is not used before the condenser, it is advisable
to use one for the secondary stream of gas.
(3) The third process is as follows:-Before entering the condenser the gas is
passed through a suitable washer (analogous to the Livesey washer) in which it is
divided into a number of fine streams, which bubble through a seal of the liquid
hydrocarbons separated out in the condenser, these being heated previous to
running into the washer by passing them through a coil of pipe in the foul main.
If the tarry particles have not been previously removed by a cyclone separator,
as in (1), the washer will effect their removal, but the previous use of a cyclone
separator will greatly minimise the chance of a block in the washer; further the
contents of the washer then remain nearly free from high boiling tar constituents,
rendering them more effective for the purpose in view. The tarry particles being
thus removed the hydrocarbons which separate out in the subsequent condensation
will consist almost entirely of such as have an appreciable vapour tension at
120° 140° F. i.e. of the light oils, and the hot gas therefore passes in fine
streams through these hot light oils, which dissolve out the naphthalene, whilst
at the same time the gas picks up a certain proportion of the lower boiling
constituents of the light oils, especially benzene and toluene which pass on into
the condenser. In this manner there is always present in the condenser a larger
proportion of low boiling hydrocarbon vapours than is in the gas as produced by
destructive distillation, this extra proportion continuously circulating through
the condenser and separating out in the cold portion, returning then to the
washer where it is again taken up by the hot gas. By this means the partial
pressure of these vapours during condensation is greater than would otherwise be
the case, thus causing a larger quantity to be retained in the gas, increasing the
illuminating power, and the presence of an additional quantity of light oils in
the condensers also assists in the removal of any naphthalene which may have
escaped the action of the hot light oils in the washer at the inlet to the condensers.
By my invention I considerable increase illuminating power and reduce or avoid
trouble from the presence of naphthalene in the gas distributing main.
1 .
0
MARKS & CLERK,
18. Southampton Buildings, London, W.C.,
13, Temple Street, Birmingham, and
25, Cross Street, Manchester, Agents.

page_text: Improvements in the Manufacture of Coal and other Illuminating Gas,
I, HAROLD GOVETT COLMAN, of 23, Stirling Road, Edgbaston, in the City of
Birmingham, 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 treatment of coal or other illuminating gas at
the stage of manufacture known as condensing and its object is to obtain increased
illuminating power and a more complete removal of the naphthalene.
The first part of my invention consists in removing the finely divided tarry
matters suspended in the gas before permitting it to enter the condensers proper
and while it is still warm, say at about 100° to 140° F. This I preferably accom-
plish by means of a centrifugal separator.
The second part of my invention consists in diverting a portion of the gas
before it is completely cooled and causing it to rejoin the gas in the condensers
when the main part has been wholly or completely cooled. The hydro-carbons
carried by the uncooled gas are thus added to the main body at a time when they
can be retained and aid the illuminating power. A bye pass may be used for this
part of the invention.
The third part of my invention consists in passing the gas before entering the
condensers through a washer containing warm hydrocarbons which removes the
naphthalene while adding to the gas a considerable quantity of vapour of low
boiling liquid hydrocarbons.
The treatment may be divided into three parts, each of which may be applied
separately, or any two of them together, or finally all three in succession.
The object to be attained in the first part of the invention is the removal from
the hot gas, previous to its entering the condensers, of the whole of the liquid
matters which have then separated, including not only the stream of tar flowing
with the gas but also the finely divided tarry particles mechanically suspended in
the gas. These particles in the ordinary method of condensation pass with the
gas into the condensers; and in the subsequent cooling attract considerable
quantities of the low boiling substances present as vapour in the gas which are
thus run away to the tar-well instead of being retained in the gas. By my
removal of the said particles from the gas at temperatures at which their attrac-
tion for the said low boiling substances is small, I am enabled to retain a larger
proportion of the latter (chiefly henzene and toluene) in the thoroughly cooled
gas than would otherwise be the case, thus increasing its illuminating power;
further, owing to the removal of these high boiling constituents of the tar before
the condensers are reached the hydrocarbons which separate in the latter, consist
mainly of light oils, with very little of the higher boiling compounds, and such
light oils being then capable of dissolving a greater amount of naphthalene than is
the case with the tar separating out under the ordinary method of condensation,
effect a more complete removal of the latter hydrocarbon from the gas.
The apparatus which I employ for the aforesaid removal from the gas of
suspended tarry particles if the ordinary centrifugal separator type. An appliance
similar to the well known cyclone dust collector is found quite suitable, an
ordinary flap or other valve being provided thereon by means of which the linear
velocity of the gas entering the cyclone can be regulated to a constant quantity
with varying volumes of the gas passing through the apparatus. I also arrange
a vertically adjustable outlet pipe, to allow of a variation in the height at which
the gas leaves the separator, and a syphon for the discharge of the far from the
bottom of the separator.

page_text: The second part of my invention consists (as hereinafter described) in the bye
passing of a portion of the gas from the inlet of the condensers, and re-introducing
it therein at one or more subsequent points, after the main stream of gas has
undergone partial or complete cooling and it may be used alone or in conjunction
with the prior separating process hereinbefore described. The secondary stream
of gas which will under usual conditions have a temperature varying from 100°
140° F., will always be saturated with the hydrocarbon vapours at that tempera-
ture, and on mixing it with the wholly or partially cooled gas it is suddenly
reduced in temperature, with the result that a considerable quantity of the hydro-
carbons is deposited in the form of a mist or fog, which exposes an immense
surface to the gas. An interchange then quickly occurs between the particles
of the light oils and the gas, the latter taking up a portion of the lowest boiling
constituents of the light oils, whilst the still liquid portions of the particles,
which consist of hydrocarbons having a very great dissolving power for naphtha-
lene, absorb the latter hydrocarbon from the gas and carry it finally to the tar well.
In carrying out the process, streams of the hot gas previously diverted (by means
of any suitable arranged bye pass and connections) from the main bulk or
stream of the gas, may be returned to the condenser and mixed with the said main
bulk when at different temperatures, but in all cases 10-20 per cent. of the
hot gas must be added to the main stream when the latter has been reduced to a
temperature of at least 70°, by which time the greater quantity of tarry matters
will have been removed, even if no preliminary removal of these has been made
as indicated in the first part of the invention. The gas is then always capable
of taking up considerably larger quantities of benzene and toluene, which are
supplied to it by the secondary stream of gas. If the tarry particles separator
is not used before the condensers, it may be used with advantage for the secondary
stream of gas.
The result obtained by this part of the invention is therefore the same as in
the previous case, viz. that the low boiling constituents of the hot gas are more
completely retained in the gas, whilst the naphthalene is more completely removed.
The process comprising the third part of my invention is as follows. Before
entering the condenser the gas is passed through a suitable washer (preferably of
the Livesey type), in which it is divided into a large number of fine streams,
which bubble through a seal of the liquid hydrocarbons separated out in the
condenser, these latter being heated previous to running into the washer by
passing through a coil of pipe in the main conveying the hot gas, the washer itself
being maintained at a temperature equal to that of the hot gas by suitable
and known means. If the tarry particles have not been previously removed
by the cyclone separator in accordance with the first part of my invention, the
washer will effect their removal, but the previous use of the separator will greatly
minimise the chance of a block in the washer; further, the contents of the
washer then remain nearly free from high boiling tar constituents, rendering
them more effective for the purpose in view. The tarry particles being thus
removed the hydrocarbons which separate out in the subsequent condensation
will consists of such as have an appreciable vapour tension at 1200-140° F., i.e.
chiefly of the light oils, and the hot gas therefore passes in fine streams through
these hot light oils, which dissolve out the naphthalene, whilst at the same
time the gas picks up a certain proportion of the lower boiling constituents of the
light oils, especially benzene and toluene which pass on into the condenser. In
this manner there is always present in the condenser a larger proportion of
low boiling hydrocarbon vapours than is in the gas produced by destructive distilla-
tion, this extra proportion continuously circulating through the condenser and
separating out in the cold portion, returning then to the washer where it is again
taken up by the hot gas. By this means the partial pressure of these vapours
during condensation is greater than would otherwise be the case, thus causing a
larger quantity to be retained in the gas, increasing the illuminating power; and
the presence of an additional quantity of light oils in the condensers also assists

page_text: in the removal of any naphthalene which may have escaped the action of the
hot light oils in the washer at the inlet to the condensers.
In place of supplying the washer with the hydrocarbons separating out in the
condensers, it may be fed with the light oils obtained by the distillation of coal or
oil tar. Where the condenser tar is used, this must only be allowed to remain in
the washer sufficiently long to allow of the lowest boiling portions being taken up
by the hot gas, as if allowed to remain too long the latter takes up appreciable
quantities of naphthalene instead of losing it.
By my invention I considerably increase illuminating power and reduce or avoid
trouble from the presence of napthalene in the gas distributing main.
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. In the manufacture of coal and other illuminating gas, the removal from the
gas, before it enters the condensers proper, of the stream of tar and of the finely
divided tarry matters suspended therein, substantially as and for the purposes
herein described.
2. In the manufacture of coal and other illuminating gas, the diversion of
a portion of the gas from the inlet of the condensers and subsequently causing
such portion to rejoin in the condensers the part from which it was separated,
substantially as and for the purposes herein described.
3. In the manufacture of coal and other illuminating gas, the passing of the
gas, before it enters the condensers, through a washer wherein it is divided
into fine streams and caused to bubble through a seal of heated liquid hydro-
carbons, substantially as and for the purposes herein described.
4. in the manufacture of coal and other illuminating gas, the treatment of
the gas by a combination of any one of the three processes claimed in the
preceding claims with either or both of the others, substantially as and for the
purposes herein described.
Dated this 29th day of November 1899.
MARKS & CLERK,
18, Southampton Buildings, London, W.C.,
13, Temple Street, Birmingham, & 25, Cross Street, Manchester,
Agents for the Applicants.