IMPROVEMENTS IN PURIFYING COAL PROVISIONAL SPECIFICATION
Year: 1881

page_text: LETTERS PATENT to James Walker, of 10, Elmwood Place, Leeds, in tho
County of York, for an Invention of "IMPROVEMENTS IN PURIFYING COAL
PROVISIONAL SPECIFICATION left by the said James Walker at the Office
of the Commissioners of Patents on the 2nd December 1881.
JAMES WALKER, of 10, Elmwood Place, Leeds, in the County of York.
'IMPROVEMENTS IN PURIFYING COAL GAS."
I take coke from which the gas has been extracted in a semi-dry state as slacked
from the retorts, and I put it through a suitable machine to crush into rough
irregular bits a quarter to half an inch in size. I place a layer of these on the first
grating at the bottom of the purifier, say, nine inches high, then the small and
dust made in the crushing operation upon the top of the layer to the thickness of
one to two inches. Then upon the second grating another layer and small as
above in similar proportions, and so upon each grating in succession to the extent
of the purifying box, not exceeding four layers or any other suitable quantity in
one charge.
This is repeated through each set of purifiers usually coupled to work together.
The covers after charging each box to be replaced and the gas turned on to pass
into and through the coke layers at the ordinary pressure necessary used for that
purpose, and in its passsage the coke by its angularity, porosity, and natural
affinity filters, absorbs, and retains the sulphur and other impurities contained in
the gas when it enters the purifiers. After the gas has passed into and out of the
purifiers the usual time necessary for the coke to be charged with the sulphur and
other impurities, it is then removed in the usual way and the box refilled as before
in the regular rotation as is now practised in all gas works. But should the engineer
in charge of the works think it an advantage he may pass the gas, after it leaves
the coke filters, through two purifying boxes charged with lime as the final finish
to the process of purification before it enters the gas-holder.
The coko when discharged as spent is available for the recovery and extraction
of the sulphur in the usual way in making sulphuric acid, so that by using coke
in this process I save the valuable product of sulphur, which is entirely lost where
lime only is used in the purification, and I obtain a greater illuminating power and
a better gas than when purified with hydrated oxide of iron; also by using coke
I save the carriage and cost of any other materials hitherto used, which is a matter
of importance from an economic point of view besides using the coke at a profitable
rato.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Walker in the Great Seal Patent Office on the 2nd June
1882.
JAMES WALKER, of 10, Elmwood Place, Leeds, in the County of York.
"IMPROVEMENTS IN PURIFYING GAS."
I take coke from which the gas has been extracted in a dry or semi dry state as
slacked from the retorts, or small coke and dust from the coke heaps called breeze,
or the breeze that comes from the fire bars of the retorts termed " pan breeze," or
any other breeze made at gas works, and I put either or both through a suitable
machine, say, a revolving grinding pan with a perforated bottom of a suitable
mesh of holes, so that in grinding the coke it can escape at the required size
without being ground into fine dust. I prefer it to be about the size of river sand
or of ordinary saw dust. I cause water to be sprinkled on the coke while it is
crushing, or afterwards, so as to give it a semi dry or damp condition suitable for
the puritying box and the work it has to do; it is then ready for immediate use in
the box. In crushing or grinding the pan breeze I cause the largest clinkers to be
cast out and the rest goes into the machine and is crushed as above stated.
With this ground coke prepared as above I fill two boxes in every set of four
boxes in layers on the grates of about from one foot to about 18 inches thick, ench
to the total thickness of three to four feet in each box or other thickness according
to the capacity of the boxes, but so preferably that the gas has to travel through
from twelve to sixteen feet of coke. I cause each layer of coke to be pressed or
beaten with a beater so as to make the layer tolerably hard and solid to prevent
the gas passing too rapidly through it. I fill the remaining two boxes of the set
with a mixture of one part of hydrate of lime and one part of the ground coke
or breeze prepared as above stated, or other suitable proportions; or I grind the
coke and unslacked lime as received from the kiln, as hereinafter described, also in
equal parts of lime and coke or other suitable proportions, and I place the mixture
in layers as above stated to the usual extent or capacity of each box.
The gas may be then turned on at the ordinary working pressure to the coke
boxos first and continued through the mixed coke and lime as finishers, and so on
in succession through as many sets of purifiers as the works employ.
The contents of the boxes, whether the ground coke only or the mixture of lime
and coke, are changed in rotation as they become fouled. The fouled coke on its
extraction is to be spread under cover for exposure to the air for revivification,
after which it is ready for a second turn, and so on till it has absorbed as much
sulphur as it can take up, when it is ready for sale for the recovery of the sulphur
in making sulphuric acid in the ordinary way.
It may be stated as an example in working four purifying boxes in one set as
above described three will always he in actual work and one exchanging its charge;
or instead of the two boxes containing coke being arranged to follow each other
as above stated, they may be placed alternately with the mixed coke and lime
finishers, say, the first box containing coke, the second the mixture of coke and
lime, the third coke, and the fourth of mixture of coke and lime as aforesaid.
I cause the mixture of coke and lime as placed in the boxes to be pressed moderately 4
equally over each layer to prevent the gas passing too rapidly through the charge.
Or I vary the preparation of the ground coke and of the mixture of ground coke and
lime in the manner following, which I prefer :-I take the coke or breeze as aforesaid

page_text: and I saturate it thoroughly with water by immersion, and I take about equal
parts by measure of the coke or breeze and of lime as delivered from the kiln
(unslacked), and I place both these quantities at the same time in the revolving
grinding pan above stated, and I grind them together to the requisite fineness (by
preference to about the fineness of river sand) as aforesaid, and if properly and
evenly mixed in the last operation the mixture is passed into a heap, but if the
grinding does not sufficiently mix them, the contents as delivered from the pan are
passed into another machine automatically as the pan revolves, which effectually
mixes then ready for use. During the grinding if the coke does not contain
sufficient moisture to slack the lime I cause water to be dropped into the pan,
so that when stored up after this process the lime becomes thoroughly hydrated
from the moisture of the coke as described and is now ready for purifying
operations.
I thus save the cost of slacking lime and its disagreeable and unhealthy
manipulations. I cause cach box to be filled with this mixed lime and coke to its
usual or full capacity in layers as above stated, and I press each layer inolerately
in order to prevent the too rapid passage of the gas through the charge; the gas may
be now turned on in the usual manner of daily routine till the boxes become fouled,
when they are changed in succession.
The coke being so intimately intermixed with the lime makes the lime more
porous and gives a greater surface of lime for the gas to pass through, and it passes
through the charge more easily and prevents the lime giving pressure or back
pressure, whilst its purifying action is thereby enlarged and the coke filters absorbs
and retains impurities that the lime of itself will not take up.
In using this mixture of ground coke and line I obtain a better gas, freer from
impurities, and giving greater illuminating power than ordinary gas, and I can
effect the purification more rapidly than can be done with lime alone, and this at a
greatly reduced cost, for in accordance with the proportions of coke used with the
lime the cost of each charge is reduced in accordance with the proportion of coke.
Of course this mixture of coke and lime when fouled cannot be used for saving
the sulphur products for making sulphuric acid as is the case when coke alone
is used.
My Invention has the further advantage of utilizing the breeze, at present
almost a waste article and nearly unsaleable in a great many gas works for want
of customers to buy it; by my Invention I make it an article of value in the
economical production of pure gas.
When this mixed ground coke and lime is turned out of the boxes, having done
its purifying work, it may be drilled into the land as a fertilizing manure, or be
mixed with clay for making bricks, and if spread in layers between the bricks in
the kiln the coke will as-ist the burning of the bricks; also if the lime be revivified
by reburning it the coke dust mixed therein will greatly facilitate the operation
and the ashes af the coke remaining in the limo will add to the value of the lime
when used again as a purifying agent.
I do not confine myself to the exact proportions of lime and coke named, as a
mixture of the two materials or of the number of the boxes each, or of the arrange-
ment thereof, whether they be used in boxes containing coke or in sets of boxes
containing mixed, ground, and prepared coke as above stated, as variations of
mixture may be made without deviating from the principles of this Invention.
Having now described the nature of my suid Invention, and the manner in
which the saine is or may be used or carried into effect, I would observe in conclusion
that what I consider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,―
First. The employment and use of coke when in a state of division in order
to effect the purification of coal gas, substantially in the manner as hereinbefore
described.
Second. The employment and use of coke when in a state of division in

page_text: conjunction with lime in order to effect the purification of coal gas substantially in
the manner as hereinbefore described.
In witness whereof, I, the said James Walker, have to this my Specification
set my hand and seal, this Second day of June, One thousand eight hundred
and cighty-two.
JAMES WALKER. (L.S.)