IMPROVEMENTS IN THE MANUFACTURE COAL GAS FOR ILLUMINATING PURPOSES."
Year: 1881

page_text: LETTERS PATENT to Francis John Bolton, of No. 19, Grosvenor Gardens, in
the County of Middlesex, Lieutenant Colonel, and James Alfred Wanklyn,
of No. 7,- Westminster Chambers, in the same County, Professor of Chemistry,
for an Invention of "IMPROVEMENTS IN THE MANUFACTURE COAL GAS FOR
ILLUMINATING PURPOSES."
PROVISIONAL SPECIFICATION left by the said Francis John Bolton and
James Alfred Wanklyn at the Office of the Commissioners of Patents on the
16th March 1881.
FRANCIS JOHN BOLTON, of No. 19, Grosvenor Gardens, in the County of
Middlesex, Lieutenant Colonel, and JAMES ALFRED WANKLYN, of No. 7, Westminster
"IMPROVEMENTS IN THE
Chambers, in the same County, Professor of Chemistry.
MANUFACTURE OF COAL GAS FOR ILLUMINATING PURPOSES."
The object of our Invention is the purification of coal gas by a dry method,
thereby avoiding the absorption of the olefines and light hydrocarbons which
takes place when water is used.
In carrying out our Invention we substitute for the wet scrubber or washer at
present used for the abstraction of the ammonia, a dry scrubber charged with a dry
porous substance, which will combine with the ammonia, but does not attack the
olefines or hydrocarbons in any appreciable degree.
When the wet washer is used for the abstraction of the tar, and in cases where a
dry coke scrubber cannot be used in its stead, we raise the temperature of the
water, or gas liquor when that is employed, sufficiently to prevent the absorption of
the hydrocarbons.
The substances which we employ in our dry scrubber are dry porous sulphate of
lime, or sulphate of lime mixed with phosphate of lime, or porous chloride of
calcium, or double chloride of calcium and sodium, or double chloride of calcium
and potassium, or double chloride of magnesium and potassium, or a mixture of
these substances in a fairly dry state and in a permeable condition,
There are economical reasons in favor of the use of a mixture of sulphate of
lime and soluble phosphate of lime, such as occurs in commercial superphosphate of

page_text: lime. This product is in excellent mechanical condition for application to gas
purification; care must however be taken that it contains no acid superphosphate,
that is to say, no real sulphuric acid, as otherwise the hydrocarbons might be
attacked.
The dry scrubber which we employ as a substitute of the ordinary wet scrubber
or washer resembles the ordinary lime "purifier," and we prefer to work it
downwards.
We also provide, when necessary, convenient 'machanism for the stirring up of
the layer from time to time to prevent caking or to break up any cakes that may
have been formed. In works where the gas is worked downwards through the lime
purifiers the top layer of lime may be replaced by one of the substances above
mentioned, or any mixture of them, and the stirring may be effected either by any
suitable known mechanical arrangements, or by opening the purifier and turning
over by hand. When this plan is adopted we do away entirely with the scrubber
or washer at present in use, and we require no special apparatus whatever for
the purposes of our Invention.
In addition to the ammonia the solid substances above mentioned will absorb
some sulphurated hydrogen, carbonic acid, cyanogen, and other impurities.
After passing through our dry scrubber or through a layer placed in the ordinary
purifier, as described, the gas passes through the usual lime purifiers or oxide of
iron, or both, according to the plan adopted in each particular case.
'
The product resulting from the action above described on sulphate of lime
consists of a mixture of carbonate of lime and sulphate of ammonia. By heating
this product the sulphate of lime is regenerated and carbonate of ammonia is given
off and may be condensed, when it will be available as an article of commerce.
The regenerated sulphate of lime after suitable treatment may be employed over
again in the above described process.
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page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Francis John Bolton and James Alfred Wanklyn in the Great
Seal Patent Office on the 14th September 1881.
FRANCIS JOHN BOLTON, of No. 19, Grosvenor Gardens, in the County of
Middlesex, Lieutenant Colonel, and JAMES ALFRED WANKLYN, of No. 7, Westminster
Chambers, in the same County, Professor of Chemistry. "IMPROVEMENTS IN THE
MANUFACTURE OF COAL GAS FOR ILLUMINATING PURPOSES."
The object of our Invention is the purification of coal gas by a dry method,
thereby avoiding the absorption of the olefines and light hydrocarbons which takes
when water is used.
In carrying out our Invention we substitute for the wet scrubber or washer at
present used for the abstraction of the ammonia, a dry scrubber charged with a dry
porous substance, which will combine with the ammonia, but does not attack the
olefines or hydrocarbons in any appreciable degree. The commercial "super-
phosphate of lime," which is a mixture or combination of sulphate of lime with
the soluble phosphate of lime, and frequently contains some phosphate of iron
or phosphate of alumina, is well adapted for our purpose. Before being used it
has to be submitted to some preliminary treatment. It must be devoid of free
acid, which is frequently present in commercial superphosphate. By mixing the
superphosphate with about one-twentieth (5 per cent) of its weight of common
gas-liquor the absence of free acid is ensured, and the commercial "superphosphate"
is moreover rendered eminently porous (on account of the evolution of carbonic acid
gas which takes place). In using the word dry we desire simply to imply that we
do not use a liquid or even a paste, but we use a very porous mass, and it will be
readily understood that the quantity of gas liquor to be mixed with the material
will depend upon the hygrometric condition of the gas. In place of the commercial
superphosphate we sometimes employ sulphate of lime in proper mechanical
condition, dry, in the sense of not being liquid or paste. Chloride of calcium is
likewise available; we render it porous by mixing a concentrated solution of
chloride of calcium with lime, when the whole forms a porous mass.
We are aware that it has been proposed to employ acid superphosphate of lime
for the absorption of ammonia from coal gas, and we do not claim the use of acid
superphosphate for this purpose. The free acid contained in such acid superphos-
phate would act injuriously upon the light giving constituents of the gas, and
therefore this substance cannot be used with advantage for its purification.
Having thus described the nature of our Invention, and in what manner the
same is to be performed, we claim,—
The method of abstracting ammonia from coal gas by the dry way, by causing
the gas to pass in intimate contact with any one or more of the following
substances: porous commercial superphosphate of lime or porous sulphate of lime,
with or without admixture of phosphate of lime and phosphate of iron, or porous
chloride of calcium, the absence of free acid from the superphosphate, when such
is used, having been previously ensured.
In witness whereof, I, the said Francis John Bolton, have hereunto set my
hand and seal, this Twelfth day of September, in the year of our Lord One
thousand eight hundred and eighty one.