Filter vessel provided with a rinsing trough

A filter vessel comprises a sieve or nozzle bottom, which carries a filter material and on which at least one trough for washing out the filter material is provided. A pipe for rinsing liquid is disposed above the trough and is provided with a plurality of nozzles, which are obliquely directed into the trough. The distance A measured between the top edges of the trough and the longitudinal axis of the pipe is 0.2 to 2 times the outside diameter D of the pipe.

This invention relates to a vessel, which serves to contain granular filter 
material and comprises a sieve or nozzle bottom for carrying the filter 
material and at least one trough, which is provided on the bottom and 
serves to wash out the filter material by means of a rinsing liquid fed 
through nozzles into the trough. 
Filter vessels provided with rinsing troughs are known and have been 
described, e.g., in Published German Application 19 47 229 and in U.S. 
Pat. No. 3,444,078. In the vessel disclosed in Published German 
Application 19 47 229, a rinsing pipe is provided on the bottom of the 
trough and is formed with holes and distributes rinsing liquid into the 
trough, but it has been found that in that arrangement a part of the 
filter material will be caught by and retained in the trough so that it is 
not possible or hardly possible to effect a clean washing-out. 
It is an object of the invention to ensure in an apparatus as described 
hereinabove that the granular filter material will be washed out in a 
simple manner and without difficulty. This is accomplished in accordance 
with the invention in that a pipe for rinsing liquid is provided above the 
trough and has a plurality of nozzles, which are obliquely directed into 
the trough, and the angle between the longitudinal axis of the pipe and 
the spraying direction of a nozzle is 10.degree. to 50.degree. and the 
distance A measured between the top edges of the trough and the 
longitudinal axis of the pipe is 0.2 to 2 times the outside diameter D of 
the pipe. Owing to the provision of the pipe having oblique nozzles above 
the trough, a strong thrust is exerted on the filter material which is to 
be washed out. At the same time, the flow of the filter material from the 
region above the nozzle bottom to the trough is not be obstructed. 
The trough suitably has a curved shape in cross-section so that there are 
no corners in which filter material could easily be retained.

The filter vessel 1 shown in FIGS. 1 and 2 is provided in its upper portion 
with an inlet 2 for the liquid to be treated, such as water. A bed 4, 
which is not shown in detail and consists of granular filter material, 
such as activated carbon, sand or pumice, is provided over the nozzle 
bottom 3. The treated liquid is drained through a line 7 from the 
collecting chamber 6 disposed below the nozzle bottom 3. 
To permit washing of the filter material out of the vessel 1, an 
open-topped trough 8 is provided on the nozzle bottom 3. A rinsing pipe 9 
extends over the trough 8 and is supplied from the outside with a rinsing 
liquid, such as water. That liquid is subsequently discharged through 
nozzles 10 into the trough 8. The nozzles are forwardly inclined toward 
the outlet 12 of the trough 8, which outlet is adapted to be closed. The 
angle between the longitudinal axis of the pipe 9 and the spraying 
direction of a nozzle 10 is 10.degree. to 50.degree. and preferably not in 
excess of 40.degree.. In dependence on the width of the vessel 1, one or 
more troughs 8 provided with an associated rinsing pipe 9 each are 
disposed over the nozzle bottom 3. 
To move the filter material completely from the nozzle bottom 3 into the 
trough 8, the collecting chamber 6 is provided with a line 14 for 
supplying rinsing water and/or air. That fluid or fluid mixture enters the 
filter bed from below through the nozzle bottom 3 and raises the filter 
material so that it can flow into the trough 8. 
The rinsing pipe 9 is held by supports 15 in such an arrangement over the 
trough 8 that the flow of the filter material to the trough 8 will not be 
obstructed. Further details are apparent from FIG. 3. For instance, the 
distance A measured between the top edges 8a of the trough and the 
longitudinal axis of the pipe 9 is 0.2 to 2 times and preferably at least 
0.5 times the outside diameter D of the pipe. The distance B between the 
two top edges 8a of the trough is suitably 2 to 8 times the outside 
diameter D of the pipe and preferably 3 to 7 times that outside diameter 
D. The spacing of the nozzles 10 provided on the pipe usually amounts to 
10 to 70 cm and preferably 20 to 50 cm. Optimum conditions for washing out 
are established when the trough has a curved rather than a cornered shape 
in cross-section. The cross-sectional shape shown in FIG. 3 is a 
semicircle. 
It will be appreciated that the instant specification and claims are set 
forth by way of illustration and not limitation, and that various 
modifications and changes may be made without departing from the spirit 
and scope of the present invention.