IMPROVEMENTS IN PURIFYING COAL GAS.
Year: 1882

page_text: PROVISIONÁL SPECIFICATION left by James Walker at the Office of the
Commissioners of Patents on the 1st August 1882.
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, or the small from the coke
heaps called breeze, or the breeze which falls under the fire bars of the retorts
generally called pan breeze (if it be made from the gas coal, not cannel coal) first
screening out the ashes and the large clinkers, and I put the coke or breeze into a
suitable machine, say a disintegerater, pulveriser, or a revolving grinding pan with
perforated bottom having holes of sufficient mesh to allow the coke or breeze to
escape without being ground too small properly, say about the size of river sand or
of ordinary saw dust. I take one part of this pulverised coke or breeze to one part,
or two parts or other suitable proportions more or less, of hydrate oxide of iron such
as Irish bog earth usually called oxide or any other oxide of iron prepared and
suitable for purifying coal gas and I mix them intimately together by hand or
machine in place of sawdust which is now generally mixed with the oxide for the
purpose of separating the particles of oxide so that the gas can pass through the
oxide in the purifiers more easily.
I then place the mixed oxide and coke or breeze in the purifying boxes in layers
in the usual way to the extent the boxes will hold, when the gas may be turned
on for purifying work at the regular pressure of the works.
By mixing the ground coke or breeze in any suitable proportion that may
be adopted with the oxide-of iron or bog earth as aforesaid I improve and enlarge
the purifying power of the oxide by giving it a greater surface for its action on the
gas, as the coke or breeze mixed therein not only separates the particles of the
oxide but it also takes up absorbs and retains impurities such as sulphur, tarry
matter, ammonia which may have escaped in the previous operations the gas has
passed through. Whereas when sawdust is applied for separating as above stated
it only gives useless bulk to the oxide in the boxes and thereby lessens its area for
work absorbs no impurities and does nothing beyond opening the oxide for the
easier passage of the gas.

page_text: The ground coke or breeze mixed in the oxide will revivify itself as the oxide
does on exposure to the air and be ready for further work when replaced from time
to time in the purifying boxes as is now done regularly where oxide of iron mixed
with sawdust is used in purifying gas.
I fill the same number of purifying boxes with this mixture of ground coke or
breeze and oxide of iron as if oxide mixed with sawdust were used for purifying with,
If auxillary or supplementary box or boxes of lime be required to finish off the
purification of the gas I use instead of neat hydrate of lime a mixture of hydrate
of lime and the ground coke or breeze, say two parts of lime to one of coke or
breeze or any other suitable proportions more or less prepared by mixing the two
materials intimately together by hand or machine or by grinding the coke or breeze
and lime as it comes from the kiln together in the same proportions as described in
the specification of the Letters Patent granted to me and numbered 1561 dated
March 31st 1882. I wet the coke or breeze to a damp moisture before mixing it
with the lime so that when pressed in the hand it adheres in a loose ball. I place the
ground coke or breeze mixed with the lime in the purifying boxes in layers exactly
as if it were lime only and to the extent of the capacity of the purifiers then in
hand. It is then ready for passing the gas either before or after the boxes, that are
filled with the mixed coke or breeze and oxide of iron aforesaid, at the ordinary
daily routine of pressure. The auxillary or supplementary box or boxes of lime
mixed with coke or breeze in any proportions as aforesaid rather than lime by itself
do more work, pass more gas in a given time freer from impurities than can be.
done by lime itself because the ground coke or breeze mixed in the lime opens it
and makes the passage of the gas through the charge much easier thereby assisting
and enlarging its purifying action and the coke or breeze mixed therein absorbs
and retains. impurities which the lime of itself will not take up and the mixed
coke or breeze and lime gives no pressure or back pressure as lime only often does
and this is a very great advantage and saving of time cost and risk in working the
gas through the purifying boxes of lime.
In filling the purifying boxes with this mixed coke or breeze and lime I cause
the layers to be pressed at the sides of the boxes and the surface also slightly, so as
to somewhat solidify the charge that the gas shall not pass too rapidly through
without leaving its impurities.-But as to the layers of the pulverised coke or
breeze and oxide of iron or bog earth being of a heavier nature requires only the
ordinary care now used in placing it in the purifiers.-When the mixed oxide of
iron or bog earth and pulverised coke or breeze is fully charged with sulphur to
the amount of say 50 per cent it may be then sold for the recovery of the sulphur
in the usual way. By mixing ground coke or breeze with hydrate oxide of iron in
any proportion as herein stated coupled with auxillary purifiers of lime and coke or
breeze I can purify the gas at a much cheaper rate per 1000 feet and give a better
quality of gas freer from impurities than can be done either by oxide of iron by
itself or lime by itself, and I save the proportionate cost of the oxide of iron, bog
earth or lime to the amount of the pulverised coke or breeze introduced.
Also the breeze being of little value at most works it is a matter of economic
importance to gas Companies in this work of purifying because there is no outlay
required in its use.
The basis and novelty of my Invention is mixing pulverised coke or breeze in
any proportion with bydrate bog oxide earth or other oxide of iron suitable for
purifying coal gas whether supplementary purifiers of hydrate of lime and coke or
breeze be added or not.