GB1602177A

GB1602177A - Liquid distribution apparatus

Info

Publication number: GB1602177A
Application number: GB11352/77A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-03-03
Filing date: 1978-03-03
Publication date: 1981-11-11

Description

(54) LIQUID DISTRIBUTION APPARATUS (71) I, GEORGE FRANCIS GILBERT CLOUGH, of Allmeadows, Wincle, Macclesfield, Cheshire, SK11 OQJ, a British Subject do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an apparatus for distributing liquid over the surfaces of packing in biological filters, cooling towers and gas scrubbers.

In the treatment of wastewater by biological filtration the water is distributed over the surfaces of the packing media in the filter, either continuously or intermittently, by a series of jets or sprays. The efficiency of the biological filter is dependent to a large extent on the uniformity of distribution of water over the surfaces of the packing media. If part of the media is over irrigated the wastewater passing over the part of media will be treated to a lesser extent than passing over the other parts of the media. If the media is not fully irrigated, the parts not wetted are ineffective.

Currently two types of system are used to irrigate biological filters, a fixed system in which all parts of the upper surfaces of the media are irrigated continuously and a moving system in which a line of jets or sprays transverses the upper surfaces of the media, so that portions of the upper surfaces are irrigated intermittently.

Fixed systems suffer from disadvantage that the spray orifices are necessarily of relatively small dimensions and hence susceptible to blockage by solid matter, including bacterial growths. The problem may be alleviated by using high pressure sprays but of course this increases the energy consumption and hence the operating cost of the system.

There are two types of moving distributors, one type in which a row of nozzles is carried by an arm which rotates about one end, the arm being horizontal and the axis of rotation vertical, and another type in which the arm traverses the filter in a linear manner, each nozzle then moving at a uniform speed. Rotary distributors are only really suitable for those filters which are substantially circular in plan and the instantaneous rate of liquid application varies with the distance of the media from the axis of rotation of the distributor because the application time at different distances decreases as the speed of travel of the nozzle increases with radius.

Rectangular, i.e. linearly moving, distributors provide a more uniform liquid application but the need to reverse the distributor arm at the end of its stroke may lead to problems associated with over application at the ends and with high inertia forces.

The apparatus of the invention provides a means of irrigation (liquid distribution) which is more uniform than with apparatus which is currently used. The apparatus of the invention is particularly suitable for strong wastes when irrigation rates are low.

According to the present invention there is provided an apparatus for intermittently distributing liquid to a rectangular area of a surface of a packing by successively applying the liquid to different portions of the area such that the instantaneous and average rates of liquid application, as hereinafter defined, and the intervals between successive applications, are substantially the same for all portions of the area, the apparatus including a nozzle for spraying liquid onto the surface and means for moving the nozzle relative to the rectangular area such that the nozzle traverses the area by tracing a closed rectangular wave or closed sawtooth pattern thereover.

The instantaneous rate of liquid application is defined as the flow per unit area to a particular portion of the area when the nozzle is directing a jet of liquid thereto, whereas the average rate of liquid application is defined as the flow per unit area to the whole area averaged over a period of many cycles. In the present case the instantaneous and the average rates are the same for all parts of the packing surface since these are treated with liquid in the same way, which is not the case the rotary distributors.

Preferably the nozzle traces a closed rectangular wave pattern and the nozzle movement means includes two drive means each adapted to move the nozzle in either direction along a respective straight line path, which two paths are arranged at right angles to one another, and which drive means are selectively actuable whereby to cause the nozzle to trace the closed rectangular wave pattern.

Means may be provided whereby the speed at which the nozzle moves is adjustable.

A plurality of rectangular areas may be sprayed with liquid concurrently if the nozzle moving means carries a plurality of nozzles.

One embodiment of the invention is now described with reference to the drawings accompanying the provisional specification in which Figures 1 and 2 show a general arrangement of means for traversing a nozzle in one direction.

Figures 3 and 4 show the mechanism for traversing the same nozzle in a direction at right angles to the first direction.

Figure 5 is a detail of part of Figure 3.

Figures 6 and 7 show the position of the mechanism of Figure 3 at different parts of the cycle of operation.

Figure 8 shows diagrammatically the air and hydraulic circuits employed for the operation of the cylinders used to carry out the traversing of the nozzle.

Referring to Figures 1 and 2, 1 is support tube to which is attached at its upper end a cross piece 2 carrying journal bearings (not shown) at opposite ends in which the horizontal shaft 3 can rotate.

Above the cross piece is a further support member 4 carrying the two double acting cylinders 5. The bottom end of the support member 4 is sealed so that it serves as an oil reservoir. The upper end of the support member is provided with a removable upper cap 6.

The upper part of the double acting cylinders contain oil and are connected to the lower part of the support member 4 through flow control valve 7 and pipe 8 (which is represented diagrammatically) .

The lower part of each of the double acting cylinders is connected by pipes 9 (shown diagrammatically) to the reversing valve 10.

The piston rods 11 are connected to the rocking beam 12 fixed to the end of the horizontal shaft 3.

The reversing valve is operated by a trip mechanism consisting of levers 13 and 14 and spring 15. Levers 13 and 14 are provided with adjustable tappets 16 operated by the upper part 17 of the rocking beam. Lever 13 is provided with a pin 41 which engages a cam face or notch or lever 14. The purpose of this section of the mechanism is to cause the horizontal shaft 3 to oscillate continuously over a predetermined arc.

Referring to Figures 3, 4 and 5, the horizontal shaft 3 carries at its outer end a block 18 through which passes a pin 19 providing a hinge point for pipe 20, the lower end of which carries a nozzle 21'. The pipe 20 is caused to oscillate in a direction at right angles to the direction in which it is caused to move by the oscillations of shaft 3 by the double acting cylinder 21. The operation of the double acting cylinder is controlled by a reversing valve 22 and escapement mechanism. The escapement consists of a notched bar 23 on which there is a raised portion 38, a rocking member 24 provided with two rollers 25 and 26 (also see Figures 6 and 7).

The rollers engage with the shoulders ot the notches on bar 23. The rocking member is carried by the lever 27 which is normally held down by spring 28. At one stage of the operation the lever is held in a raised position by rocking member 29, a notch in this member engaging a pin 30 attached to the lever 27.

At another stage of the operation it is released by pin 31 bearing against its lower end.

The part rotary movement of rocking member 29 operates the reversing valve 22 by the medium of shaft 32 and lever 33.

The reversing valve 22 is connected to the double acting cylinder by pipes 34 and 35 (both shown diagrammatically) and flow control valve 36. Pin 31 is operated by striker 37 attached to the notched bar 23. The rocking member 24 is caused to rock by the action of the double acting cylinder 39.

The operation of the mechanism is described as follows and with reference to Figure 8 in which the reference numerals correspond to those used in the above description with the additional item of a pressure reducing valve 40, the function of which is to reduce the pressure of air applied to the double acting cylinder 21.

The part rotary oscillation of horizontal shaft 3 is obtained by admitting air alternately to the lower parts of double acting cylinders 5. Air is applied at a convenient pressure to reversing valve 10 which in the position shown admits air to the right hand cylmder so causing the rocking beam 12 to rock. The upper part 17 of the rocking beam coming into contact with the tappet 16 on lever 13 extends spring 15. As lever 13 rotates, the pin 41 moves into a position In which it no longer prevents the rotation of lever 14. At this pqint lever 14 rotates under the tension of the spring 15 and in so doing operates the reverslng valve 10.

Air is now admitted to the other cylinder and the first cylinder vented to atmosphere. The rocking beam will commence to rotate in the opposite direction. As the upper part 17 of the beam comes into contact with tappet 16 on lever 14, spring 15 is placed under tension and when the notch in lever 14 clears pin 41 attached to lever 13, lever 13 rotates under the influence of spring 15 at the same time restoring the reversing valve 10 ot its original position. The stroke of the rocking beam may be adjusted by altering the distance between tappets 16 and the upper part 17 of the beam.

The speed at which the oscillation takes place is controlled by the adjustment of flow control valves 7 which throttle the oil leaving the upper parts of the cylinders to return to the reservoir of oil in member 4.

The position of the reversing valve 10 also controls the position of the double acting cylinder 39, a T-connection being provided in each of pipes 9 for this purpose.

In figure 3 the notched bar is shown in a position in which it is at the end of its stroke with double acting cylinder 21 fully extended, air pressure being applied to the rod end of the cylinder but the movement inward of the piston rod being constrained by one of the notched in the notched bar 23 engaging with roller 25 of the rocking member 24. At the next reversal of oscillation of horizontal shaft 3 air pressure is applied to the other side of the double acting cylinder 39 so that rocking member 24 assumes a position in which the inward motion of the notched bar is restrained by roller 26. The dimensions of the notches and rollers are such that the bar moves inwards by the chosen amount.

This inward motion continues until the position shown in Figure 6 is reached. At the next oscillation, roller 25 bears on a raised portion 38. In the absence of a notch into which the roller would otherwise fall, the pivot point of the rocking member 24 and hence the lever 27 is raised against the compression of spring 28. The movement allows the rotation of lever 29 and consequently operates the reversing valve 22. This applies air pressure to the opposite side of double acting cylinder 21. The notched bar 23 and pipe 20 go to the opposite extreme position at a speed governed by flow control valve 36, striker 37 acting through pin 31 restores lever 29 to its original position thus allowing the lever 27 to fall so that roller 25 engages in the appropriate notch of bar 23. At the same time the reversing valve is released by lever 33 and air pressure is applied to the rod end of double acting cylinder 21 thus restoring the mechanism to its original condition.

The number of discrete stops in the position of pipe 20 is governed by the number of notches in bar 23. The arc travelled by pipe 20 can be adjusted by altering the position of the pivot point.

The nozzle 21' thus follows a closed rectangular wave pattern. The speed of travel (in either direction) caused by the drive means including the double acting 21 is fast compared to the travel (in either direction) caused by the oscillating shaft 3 in order that the consequences of the double liquid application on the return stroke of the double acting cylinder 21 is minimal. Whereas a closed rectangular wave pattern has been described, it is alternatively possible to provide a similar intermittent distribution by means of a closed saw-tooth pattern.

Using the described apparatus a film-flow packing constituting a biological filtration media was irrigated over a range of irrigation rates. The film-flow packing had a square cross section, the sides of the square being 1.2 metres providing a plan area of 1.44m2.

Measurements were taken of flow rate at a number of positions over the plan area indicated by the following diagram.

1 2 3 4 5 6 7 r^-l 150 150 150 1150 150 150 1 150 rl50 150 to 150 150 I I 150 C 1.2m 150 150 150 150 t XXF 1 rio I 12m

The results obtained were as follows, showing an extremely uniform distribution of flow over the plan area of the packing: Flow rates Flow rates cmlm hour. 1.5 2.2 3.0 cm3/m hour. 15 2.25 30 Al 1.4 2.2 3.0 D5 1:5 2.25 j:O Al 1.4 2.2 3.0 D5 15 2.25 3.1 A2 1.5 2.2 3.0 D6 1.5 2.25 31 A3 1.5 2.2 3.0 D7 1.5 2.25 3.1 A4 1.5 2.2 3.0 El 1.5 2.23 3.0 A5 1.5 2.2 3.0 E2 1.5 2.23 3.0 A6 1.5 2.2 3.0 E3 1.5 2.23 3.0 A7 1.4 2.2 3.0 E4 1.5 2.23 3.0 B1 1.5 2.2 3.0 E5 1.5 2.23 3.0 B2 1.5 2.2 3.0 E6 1.5 2.23 3.0 B3 1.5 2.2 3.0 E7 1.5 2.23 3.0 B4 1.5 2.2 3.0 F1 1.5 2.2 3.0 B5 1.5 2.2 3.0 F2 1.5 2.2 3.0 B6 1.5 2.2 3.0 F3 1.5 2.2 3.0 B7 1.5 2.2 3.0 D4 1.5 2.2 3.0 C1 1.55 2.24 3.0 F5 1.5 2.2 3.0 C2 1.55 2.24 3.0 F6 1.5 2.2 3.0 C3 1.55 2.24 3.0 F7 1.5 2.2 3.0 C4 1.55 2.24 3.0 G1 1.4 2.2 2.9 C5 1.55 2.24 3.0 G2 1.5 2.2 2.9 C6 1.55 2.24 3.0 G3 1.5 2.2 2.95 C7 1.55 2.24 3.0 G4 1.5 2.2 2.95 D1 1.5 2.25 3.1 G5 1.5 2.2 2.95 D2 1.5 2.25 3.1 G6 1.5 2.2 2.95 D3 1.5 2.25 3.1 G7 1.4 2.2 2.95 D4 1.5 2.25 3.1

Claims

WHAT WE CLAIM IS:

1. An apparatus for intermittently distributing liquid to a rectangular area of a surface of a packing by successively applying the liuid to different portions of the area such that the instantaneous and average rates of liqmd application as hereinbefore defined, and the intervals between successive applications, are substantially the same for all portions of the area, the apparatus including a nozzle for spraying liquid onto the surface and means for moving the nozzle relative to the rectangular area such that the nozzle traverses the area by tracing a closed rectangular wave or closed saw-tooth pattern thereover.

2. An apparatus as claimed in claim 1, and in which the nozzle traces a closed rectangular wave pattern, wherein the nozzle movement means includes two drive means each adapted to move the nozzle in either direction along a respective straight line path, which two paths are arranged at right angles to one another, and which drive means are selectively actuable whereby to cause the nozzle to trace the closed rectangular wave pattern.

3. An apparatus as claimed in claim 1 or claim 2 and provided with means by which the speed at which the nozzle moves is adjustable.

4. An apparatus as claimed in any one of the preceding claims and whereby a plurality of rectangular areas are so sprayed with liquid concurrently, wherein a plurality of nozzles are carried by the nozzle moving means.

5. An apparatus for intermittently distributing liquid to a rectangular area of a surface of a packing, substantially as herein described with reference to and as illustrated in the drawings accompanying the provisional specification.