Improvements in Sieve Purifiers suitable for Treating Middlings and like Granular Materials.
Year: 1891

page_text: Date of Application, 9th Feb., 1891
Complete Specification Left, 7th Nov., 1891-Accepted, 12th Dec., 1891
PROVISIONAL SPECIFICATION.
Improvements in Sieve Purifiers suitable for Treating Middlings
and like Granular Materials.
I, PEIRSON TURNER, of Ipswich, in the County of Suffolk, Engineer, do hereby
declare the nature of this invention to be as follows:-
This invention has for its object improvements in sieve purifiers suitable for
treating middlings and like granular materials.
In the manufacture of flour it is usual to pass the middlings over a sieve the
surface of which is commonly of silk fabric. The sieve is set at a slight inclination
and is shaken continuously. The middlings pass on at. the upper end of the. sieve
where the silk fabric is comparatively fine and descend towards, the lower end;
the fabric over which the material passes getting progressively coarser and coarser.
An air current ascends through the silk. The greater part of the material passes
through the meshes of the sieve and little, is left to pass off at the end.
.
Now in order that such sieves should work to the best advantage, the surface
should be evenly covered with material from end to end; but the present practice
does not admit of this, for the sieve being uniformly inclined from end to end, the
speed at which the material passes along it is also approximately uniform. But
much of the material passes through the sieve near its upper end consequently
near the lower end the sieve is left nearly bare. I remedy this defect by inclining
the surface of the sieve comparatively steeply at the upper end, but lessening the
steepness of the incline as the lower end of the sieve is approached. In this way
I am able to ensure that the entire surface of the sieve when at work shall, be
suitably and more or less uniformly covered.
In some cases I find it desirable even to cause the; further end, of the. sieve to
incline in the opposite direction, so that the material ascends slightly before making
its escape at the tail of the sieve.
Dated this 9th day of February 1891.
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION..
Improvements in Sieve- Purifiers suitable for Treating Middlings
and like Granular Materials. .
I, PEIRSON TURNER, of Ipswich, in the County of Suffolk, Engineer, do hereby
declare the nature of this invention and in what mauner the same is to be performed
to. be. particularly described and ascertained in and, by the followirg.statement :-
This invention has for its object improvements in sieve purifiers suitable for
treating middlings and like granular materials.
In the manufacture of flour it is usual to pass the middlings over a sieve the
surface of which is commonly of silk fabric. The sieve is set at a slight inclination
and is shaken continuously. The middlings pass on at the upper end of the sieve
where the silk fabric is comparatively fine and descend towards the lower end;
the fabric over which the material passes. getting progressively coarser and coarser.
An air current ascends through the silk. The greater part of the material passes
through the meshes, of the sieve and little is left to pass off at the end.
Now in order that such sieves should work to the best advantage, the surface
should be evenly covered with material from end to end, but the present practice
does not admit of this, for the sieve being uniformly inclined from end to, end, the
D
1

page_text: But
speed at which the material passes along it is also approximately uniform.
much of the material passes through the sieve near its upper end consequently
near the lower end the sieve is left nearly bare. I remedy this defect by inclining
the surface of the sieve comparatively steeply at the upper end, but lessening the
steepness of the incline as the lower end of the sieve is approached.
In this way
I am able to ensure that the entire surface of the sieve when at work shall be
suitably and more or less uniformly covered.
In some cases I find it desirable even to cause the further end of the sieve to
incline in the opposite direction, so that the material ascends slightly before making
its escape at the tail of the sieve.
In order that my said invention may be fully understood and readily carried into
effect I will proceed to describe the drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a longitudinal section of the sieve and other parts of a purifier to
which my invention is applied.
Figure 2 is a transverse section of the same.
a is the frame and a¹ is the silk surface of the sieve. As represented in the
drawing the silk surface of the sieve inclines uniformly from its upper end as far
as a* and then the inclination changes and from a* to a* the downward slope is less.
At a there is another change of inclination and from a² to as the silk is nearly
horizontal. Finally in the last section from a³ to a the silk has a slight inclination
upwards.
The changes in inclination may be more or less frequent and even one change
will practically be found sufficient to effect a great improvement and at least to
prevent the lower end of the sieve being left comparatively bare. 'The sieve is
fine at the upper end and becomes progressively coarser and coarser in passing
towards the lower end. The sieve is mounted in the usual manner in a casing b.
cc is a stationary cover placed over the sieve; it consists of prisms of wood c'
fixed in a frame parallel the one to the other with their apices downwards.
The
Plates of sheet metal c² care fixed upon the prisms c¹ on either side and a
narrow lateral slit or aperture is left between the upper edges of each pair of plates.
The sieve serves to separate the casing b into two chambers an upper and a lower.
Air is drawn out by a fan from the upper chamber and this causes air to flow
upwards from the lower chamber through the silk surface of the sieve.
semolina or the like is fed on at the upper end of the sieve. The sieve receives a
jogging movement and the material becomes distributed over it with approximate
uniformity; it travels gradually down towards the lower end of the sieve where
the larger particles are discharged whilst the smaller (with the exception of the
dust or impurities) fall through the sieve into the lower chamber and are collected.
The dust or impurities are carried upwards by the current of air passing through
the sieve and are so separated.
The bases of the prisms form the receiving surface for the dust or impurities
which are deposited upon this surface in the furrows or troughs between the
plates in consequence of the air currents rapidly losing velocity when they
enter the free space over the cover c. d is a brush carried by endless bands passing
around rollers mounted within the casing; these rollers have a slow rotary motion
imparted to them. The dust is swept by the brush d along the top of the cover
and is delivered into a trough e. The trough e is mounted upon the sieve and
partakes of the jogging movement; this enables the trough to deliver the dust at
the end of the sieve into a suitable receptacle.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The arrangement of the silk surface through which the air rises and along which

page_text: the material under treatment travels, in two or more inclines so arranged as to
obtain a more uniform distribution of the material on the surface as herein set
forth.
Dated LL 1
1801
PEIRSON TURNER.