Improvements in and connected with Apparatus for Drying or Dehydrating Pulverized Gypsum and other Finely 'Divided Materials.
Year: 1895

page_text: .Date of Application, 3rd Apr., 1895
Complete Specification Left, -28th Dec., 1895--Accepted, 15th Feb., 1896
.
'PROVISIONAL SPECIFICATION.
Improvements in and connected with Apparatus for Drying or
Dehydrating Pulverized Gypsum and other Finely 'Divided
Materials.
I, HERMANN KROPFF, Engineer, of Friedrichstrasse, Düsseldorf, in the
German Empire, do hereby declare the nature of this invention to be as
follows:-
'This invention has for its object, to provide apparatus for rapidly 'and
thoroughly drying or dehydrating crude gypsum and at the same time relieving
it of dust. The apparatus chiefly comprises a vertical cylindrical case containing
shelves or horizontal partitions placed one over the other, a stirring or sweeping
appliance adapted to agitate or propel the material lying on the said shelves or
partitions, steam-heating-pipes adapted to heat some or all of the said shelves, and
a water-jet or ejector adapted to suck off the air and vapour from the interior of
the said casing.
The said shelves or partitions have openings alternately at the circumference
and in the centre, so that the gypsum which travels from the top to the bottom of
the apparatus over the said partitions follows a zig-zag course. A shaft situated
in the axis of the cylindrical casing carries in each interval between two partitions
a pair of radial arms to which are secured suitably inclined blades, so that, when
the shaft revolves, the said blades sweep the gypsum'lying on the shelves alter-
nately from the centre to the circumference and (after it has 'dropped upon the
next lower shelf) from the circumference to the centre. Some or all of the said
partitions or shelves (those situated in the upper part of the casing) are hollow and
heated by steam, for which purpose vertical steam pipes are placed on diametrically
opposite sides of the casing and communicate with the hollow partition by radially
arranged short branch pipes. Each of the vertical feed pipes is divided into two
or more sections, and the fresh steam is admitted to the lowest section of a' feed
pipe, from which it enters the lowest group of partitions through several parallel
branch pipes (one for each partition of the said group). After having passed
through the said partitions, the steam escapes into the lowest section of the opposite
feed pipe, from which it is conducted into the upper section on the entrance side,
where it passes through parallèl branch pipes into the upper partitions and through
the same to the opposite discharge pipe.
The cylindrical casing has at the top an inlet for the crude gypsum and an
outlet for the vapours and dust arising from the same, and at the bottom two
outlets for the dried gypsum. As the fresh steam enters at the bottom,' the tem-
perature of the partitions in the lower part of the apparatus, which acts on the
partly dried gypsum, is higher, than the temperature of the partition in the upper
part of the apparatus which acts on the fresh or crude gypsum powder.
The vapours and dust arising from the gypsum are conducted into a water jet
condenser or ejector, which 'draws the same out of the apparatus.
Dated this 2nd day of Anril 1895.
FAIRFAX & WETTER,
Agents for the Applicant.

page_text: Improvements in and connected with Apparatus for Drying or
Dehydrating Pulverized Gypsum and other Finely Divided
Materials.
I, HERMANN KROPFF, Engineer, of Friedrichstrasse, Düsseldorf, in the
German Empire, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
This invention has for its object to provide apparatus for rapidly and thoroughly
drying or dehydrating crude gypsum and at the same time relieving it of dust.
In the accompanying drawings Fig. 1 is an elevation and Fig. 2 a vertical
section, of an apparatus embodying my invention.
Fig. 3 is a horizontal section along line A-B of Fig. 2.
The apparatus chiefly comprises a vertical cylindrical case g containing shelves
or horizontal partitions p, p, p², placed one over the other, a stirring or sweeping
appliance adapted to agitate or propel the material lying on the said shelves or
partitions, steam heating pipes adapted to heat some or all of the said shelves, and
a water jet, or ejector adapted to suck off the air and vapour for the interior of the
said casing.
The said shelves or partitions p, p¹, p³ have openings alternately at the circum-
ference and in the centre, so that the gypsum which travels from the feed hopper t
at the top to the bottom of the apparatus over the said partitions follows a zig-zag
course. A shaft w situated in the axis of the cylindrical casing carries in each
interval between two partitions a pair of radial arms to which are secured suitably
inclined blades f, so that when the shaft revolves, the said blades sweep the gypsum
lying on the shelves, alternately from the centre to the circumference, and (after
it has dropped upon the next lower shelf) from the circumference to the centre.
Some or all of the said partitions or shelves (those situated in the upper part of
the casing) are hollow and heated by steam, for which purpose vertical steam
pipes r,,, are placed on diametrically opposite sides of the casing, and com-
municate with the hollow partitions by radially arranged short branch pipes. The
vertical feed pipes are divided into two or more sections, and the fresh steam is
admitted to the lowest section r of a feed pipe, from which it enters the lowest
group of hollow partitions p', p', through several branch pipes u, u (one for each
partition of the said group). After having passed through the said partitions p¹,
the steam escapes into the opposite pipe, from which it is conducted through a
pipe into the upper section r, on the entrance side, where it passes through
parallel branch pipes u' into the upper partitions p³, p³, and the water of con-
densation formed in the same escapes through the branch pipes to the discharge
pipe v', from which it is drawn off by a syphon h.
The cylindrical casing has at the top an inlet t for the crude gypsum and an
outlet a for the vapours and dust arising from the same, and at the bottom two
outlets, z, for the dried gypsum. As the fresh steam enters at the bottom, the
temperature of the partitions in the lower part of the apparatus, which acts on the
partly dried gypsum, is higher than the temperature of the partitions in the upper
part of the apparatus, which acts on the fresh or crude gypsum powder.
The vapours and dust arising from the gypsum are conducted through the tube a
into a condenser or ejector c, which draws the same out of the apparatus by means
of a cold water jet i.
The vapours are thereby condensed, while the dust is precipitated in the form of
mud, and the air is conducted to the top through a tube c surrounding the tube a.

page_text: Although the apparatus is primarily intended for drying pulverized gypsum, it
may be used for drying other solid material in the shape of powder or granules.
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:
Apparatus for drying pulverized gypsum and other finely divided materials,
comprising in its construction a series of hollow shelves or partitions p¹, p³, a
rotary stirring and transporting mechanism, heating pipes r, r', and short con-
necting pipes u, u' adapted to conduct the steam to the said shelves or partitions in
such a manner that the hottest steam acts on the partly dried gypsum, and a
discharge or draw-off appliance provided with a water jet i, the whole being
arranged and adapted to operate substantially as described.
Dated this 27th day of December 1895.
FAIRFAX & WETTER,
433, Strand, London, Agents..