Cyclone construction

A cyclone separator construction has a gas supply pipe which joins a horizontal inlet spiral of the cyclone and is inclined downwadly at an angle of between 30 degrees and 70 degrees with the horizontal. In this way disruptive material deposits in the inlet region of the cyclone are avoided.

The invention relates to a cyclone construction for use in separating gases 
and fine materials. 
BACKGROUND OF THE INVENTION 
In a conventional cyclone separator a gas supply pipe has a horizontal 
section that opens into the horizontal inlet spiral of the cyclone. 
Operational experience with such a cyclone has shown that material 
deposits frequently occur in the horizontal section of the gas supply pipe 
which joins the inlet spiral of the cyclone, and these deposits greatly 
restrict the flow of gas. These disruptions are particularly serious in 
cyclones which are intended for use with hot gases charged with fine 
material. For example, in cases where the cyclone is the lowest stage of a 
multi-stage cyclone heat exchanger serving to preheat the fine material, 
the gas supply pipe is formed by the exhaust gas pipe from a rotary kiln 
which is connected downstream from the cyclone heat exchanger and serves 
for final burning of the preheated fine material, and the gas supply pipe 
which serves as a calciner is provided with an arrangement for supplying 
additional fuel. 
The temperatures of the gas and the material at the inlet to the cyclone 
encourage particles of material to stick to the relatively cooler walls of 
the gas supply pipe or of the cyclone. When low-grade fuels are used in 
the gas supply pipe which serves as a calciner this disadvantageous effect 
is aggravated because a proportion of these fuels burns out in the cyclone 
or in the part of the gas supply pipe which opens into the inlet spiral of 
the cyclone. The material deposits formed during overheating can become so 
firmly set that they can hardly be removed by conventional means. 
The conditions in that part of the gas supply pipe which joins the 
horizontal inlet spiral of the cyclone and also runs horizontally are 
particularly unfavorable when the preceding section of the gas supply pipe 
runs vertically downwards from above. In this case the centrifugal forces 
coming into effect when the particles of material are deflected from the 
vertical to the horizontal cause an increased deposit of particles of 
material in the horizontal part of the gas supply pipe. 
The object of the invention, therefore, is to construct a cyclone of the 
type referred to in such a way that these disadvantages are avoided and 
disruptive material deposits are prevented from forming in that part of 
the gas supply pipe which joins the horizontal inlet spiral of the 
cyclone. 
SUMMARY OF THE INVENTION 
In a cyclone constructed according to the invention that part of the gas 
supply pipe which joins the horizontal inlet spiral is inclined downward 
from above and encloses an angle of between 30 and 70 degrees, preferably 
between 40 and 60 degrees, with the horizontal, and therefore the 
deposition of particles of material in this particularly critical part of 
the gas supply pipe is avoided. 
In order to produce the necessary gas inlet cross-section with this 
inclined inflow into the cyclone, the inclined part of the gas supply pipe 
advantageously passes partially through the cover of the cyclone. 
Comparative measurements show that a cyclone constructed according to the 
invention gives comparable or somewhat better results as regards degree of 
separation and pressure loss than a conventional cyclone.

DETAILED DESCRIPTION 
The construction shown in the drawings, comprises a cyclone 1 having a 
vertical axis 2, a horizontal inlet spiral 3, a separating hopper 4, and a 
dip pipe 5. 
A gas supply pipe 6 which is only partially shown has one section 7 which 
runs vertically downwards from above and one section 8 which runs 
downwards at an inclination from above and opens into the horizontal inlet 
spiral 3, enclosing an angle .alpha. between 30 degrees and 70 degrees, 
and preferably between 40 degrees and 60 degrees, with the horizontal. 
This pipe part 8 which is inclined downwards from above partially passes 
through the cover of the cyclone 1 inwardly of the confines thereof in 
order to ensure the necessary inlet cross-section for the gas. As can be 
seen from the drawing, in this way part of the pipe part 8 lies 
immediately adjacent or tangent to the dip pipe 5. 
The illustrated cyclone 1 can for example form the lowest stage of a 
multi-stage cyclone heat exchanger which serves for preheating fine 
material, and in which the gas supply pipe 6 constitutes the exhaust gas 
pipe from a rotary kiln which is connected downstream from the cyclone 
heat exchanger and serves for final burning of the preheated fine 
material. In this case the gas supply pipe 6 is advantageously constructed 
as a calciner and provided with at least one burner assembly for supplying 
additional fuel. 
In the diagram of FIG. 4 a cyclone separator 1 is shown wherein the gas 
pipe 6, formed as the exhaust gas pipe of rotary kiln 12, is provided with 
a fuel and burner assembly indicated at 13. FIG. 4 also diagrammatically 
indicates a material pipe 14 (supplying material from cyclone separator 1 
to rotary kiln 12), and a material pipe 15 which supplies material from 
the next cyclone generator, not illustrated, to the gas supply pipe 6. 
Since for such an application the temperatures of the gas and the material 
at the end of the gas supply pipe 6, i.e., at the junction with the 
cyclone 1, are particularly high and the danger of material caking thereon 
is therefore very great, it has proved particularly advantageous that 
material deposits in the inlet zone of the cyclone are avoided to the 
greatest possible extent as a result of the inclined insertion of the gas 
supply pipe 6 into the cyclone 1.