IMPROVEMENTS IN SCREENS FOR COAL GAS PURIFIERS
Year: 1873

page_text: LETTERS PATENT to Edward Duffee, of. Haverhill, in the County of
Essex, and State of Massachusetts, of the United States of America,
COMPLETE SPECIFICATION filed by the said Edward Duffee at the
Office of the Commissioners of Patents, with his Petition and
Declaration, on the 1st May 1873, pursuant to the 9th. Section.
of the Patent Law Amendment Act, 1852..
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD:
DUFFEE, of Haverhill, in the County of Essex, and State of Massa-
chusetts, of the United States of America, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS
IN SCREENS FOR COAL GAS PURIFIERS," and have petitioned Her most Ex-
cellent Majesty Queen Victoria to grant unto me, my executors, ad-
ministrators, and assigns, Her Royal Letters Patent for the said In-
vention, and have made solemn Declaration that I am the true and first
Inventor thereof.
NOW KNOW YE, that I, the said Edward Duffee, do hereby declare
that the following Complete Specification, under my hand and seal; fully
describes and ascertains the nature of the said Invention, and in what
manner the same is to be performed, reference being had to the accom

page_text: panying Drawing, and the figures and letters marked thereon (that is to
say) :—
My Invention relates to that class of screens in which dry lime is
used as the purifying agent, such screens being employed in the ordinary
gas purifying boxes, and arranged in tiers one above another, and my
Invention consists,―
First. In dispensing with the thin strips of wood or rattan, woven
across the frame, or interlaced in the form of basketwork, as heretofore
employed, and using in the place thereof a series of independent cylin-
drical, or other proper shaped bars or rods extending across the frame
either longitudinally or transversely, each of the rods passing through
holes (corresponding in shape to the rods) made for its reception in the
frame, and extending through or beyond the outer face; each of the said
rods being loosely fitted to the frame or bars through which it passes, so
that it may be readily inserted in or drawn out of the frame whenever
desirable.
And Second. In forming the sides of the wooden frame with inclined
or bevelled edges, in order that when two of the screens are placed in
the box, and side by side, a wedge-shaped opening (with its base upper-
most) shall be formed between them to receive a larger body of lime,
and thus. better lute or cover the opening than if the sides of the frame.
were formed straight and parallel to each other.
In the said Drawing A, B, C, and D are four bars, constituting the
frame of the screen, the same being composed of wood or other suitable
material. a is a cross bar, which may be employed in large screens when
desirable to prevent sagging of the rods, to be herein-after described.
The bar a may be disposed either transversely of the frame, or longitu-
dinally thereof, as may be preferable. When used, this bar should have
holes made transversely through it to receive the rods b, b, etc. These
bars or rods I prefer to make of a cylindrical shape, but but they may
have a square or any other desirable form, such rods extending through
holes formed through the sides of the frame, they being disposed at the
requisite distance apart to support the lime, and allow the gas to pass up
between them.
The series of rods may extend either longitudinally or transversely of.
the frame, as may be deemed best.
The ends of the rods may be flush with the frame, or may project

page_text: beyond the outer face thereof, and in line with the projecting tenons, c, c,
c¹, c³, or the extended ends e, e, e¹, e¹, of the frame. Each of the rods is
to be so applied to the frame as to be readily removable whenever
desirable for repair or substitution, as may be necessary.
Each side d of the frame is to have a bevel, groove, or rabbet e,
formed on its upper and lower portions, in order that when the screens
are placed in the box side by side, the openings left between the frames
for the passage of the gas, shall have a flaring shape, so as to better
receive and hold the mass of lime than if the frame were unprovided
with such reductions.
The screens are so made as to be reversible, either side being used
uppermost.
From the above it will be seen that by my peculiar construction of the
series of rods and their application to the frame, a simple, durable, and
effective screen is produced, one not only cheap and easily constructed,
but little liable of getting out of order, for should one of the rods become
damaged, the same can be readily removed and another substituted. So
also it will be seen that by bevelling or grooving the sides of the frame,
a better luting of the joints between the frame is secured, and thereby a
better filtration of the gas is attained.
Having described my Invention, what I claim is,-
1st. The improved gas screen as described, the same consisting of the
frame A, B, C, D, and the series of detachable bars or rods b, b, etc.,
combined and arranged as herein-before stated.
2nd. A gas screen of the kind described, having its frame bevelled,
grooved, or rabbeted, in manner and for the purpose set forth.
In witness whereof, I, the said Edward Duffee, have hereunto set
my hand and seal, this 25th day of March, 1873.
Witnesses,
F. P. HALE.
F. C. HALE.
EDWARD DUFFEE. (L.S.)