Agitating – With heating or cooling – Electrical heating
Patent
1993-11-02
1995-05-23
Scherbel, David A.
Agitating
With heating or cooling
Electrical heating
366 85, 366300, 366301, 219388, 219421, 219426, 2221465, 4253781, 425DIG13, B01F 1506, B01F 708
Patent
active
054174929
DESCRIPTION:
BRIEF SUMMARY
This invention relates to apparatus for continuously mixing and heating flowable materials such as liquids, powders, granular materials and other flowable materials including cakes, and residues.
Apparatus comprising a screw in a casing for conveying such materials is well known. It is also known that such screws may comprise a rotating hollow shaft carrying a hollow screw flight through which heat transfer media may be passed for heating the conveyed material. However for heating some materials steam or oil heating is not particularly practicable. For instance, pyrolysing treatment of pulverised coal requires a pyrolysing temperature of about one thousand degrees Fahrenheit. For this purpose a single screw device was tried many years ago in which the screw rotated alternately clockwise and anticlockwise but its use was discontinued long ago so presumably it was inefficient.
Heating hollow screws by steam or hot oil was unlikely to be suitable for such high temperatures. An alternative would be to pass molten salts through hollow screws. This has been tried, but unless the salt is totally evacuated from the screws on the shutdown, it freezes solid which involves considerable difficulties.
Another possibility could be to incorporate electrically heated rods in the shafts carrying the screw flights but this also involves practical difficulties and is of doubtful efficiency.
SUMMARY OF THE INVENTION
The object of the present invention is to devise improved apparatus for continuously mixing and heating flowable materials.
A further object of the invention is to provide more efficient heating means for heating a casing incorporating a pair of rotating screws having screw flights of One interleaving with the screw flights of the other so as to effect a mixing of the materials with enhanced uniformity of heating.
According to the present invention there is provided an apparatus for continuously mixing and heating flowable materials comprising a housing, at least two rotatable screws within said housing, each screw having a rotatably mounted shaft and a screw flight, said screws being arranged in parallel juxtaposition with their respective flights of opposite hand intermeshing, and means for driving said shafts in opposite rotation to each other, characterised in that each rotatably mounted shaft is hollow, that fixed support shafts extend within said rotatably mounted shafts, and that there are provided electric heaters respectively within said hollow shafts carried by said support shafts.
This arrangement has been tested and found to be most surprisingly efficient and practicable.
Also, according to the invention said support shafts may each carry a hollow cylinder on the exterior surface of which is mounted said heater.
The additional heater shaft with nearing elements may be provided in each of a pair of interleaved rotatable shafts.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
The invention will be further described by way of example with reference to the accompanying diagrammatic drawings wherein:
FIGS. 1A and 1B are an elevational view of a screw conveying apparatus made in accordance with the invention;
FIGS. 2A and 2B are a sectional view on the plane 2--2 on FIG. 1;
FIG. 3 is a sectional view on the plane 3--3 on FIG. 1, and
FIG. 4 shows a sectional view of a modification of the apparatus in which four screws are provided.
DESCRIPTION OF A PREFERRED EMBODIMENT
The apparatus comprises a base 10, a support 11 having an inclined upper track 11a, an upright drive bearing housing 12 mounted on rollers 12a engaging said track 11a to permit movement of said housing to accommodate expansion and contraction of the apparatus, a casing 20, and screws 8, 9 within said casing arranged in parallel juxtaposition relative to each other and inclined at 3 to 25%.
The screws 8, 9 comprise respectively rotatable hollow shafts 13, 14 and screw flights 18, 19 fixed thereon. The casing 20 which in turn is preferably arranged within a heat insulating jacket 21, is mounted at the lower end on a fixed part of the bearing ho
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Almojuela Manuel M.
Barish Emil Z.
Christian Robert F.
Mazur Mikhail D.
Nicdao Noland F.
Christian Engineering
Cooley Charles
Scherbel David A.
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