The present invention relates to a device for distributing liquid, especially washing liquid for washing paper pulp, in a diffuser having at least one screen plate, comprising means for supplying the washing liquid and at least one elongated nozzle which can be connected to the said means and which projects down in front of the screen plate and is arranged to supply the liquid.

Such a device is previously known through US-A-3, 348, 390 which relates to a liquid distribution device in a diffuser with openings being arranged on two different levels - at the top and at the bottom - along the height of the screen plates . The washing liquid is thereby conveyed in separate conduit systems to the different levels, which results in a complicated system for supplying the washing liquid. In addition, it can give rise to uneven distribution of the washing liquid along the height of the screen plate.

In a further development, the washing liquid is supplied through two nozzles, namely a long nozzle which reaches to the lower part of the screen plate and a short nozzle which is designed to supply washing liquid to the upper part. The washing liquid is distributed to each nozzle by means of a rotatable so- called nozzle plate which is provided with a number of holes, more specifically throttle holes, the cross- sectional area of which is predetermined in relation to the current quantity of liquid passing through the nozzle. An uneven distribution of the liquid along the height of the screen plate also occurs when this device is used.

The object of the present invention is to produce a device in a diffuser of the type mentioned at the outset, which device is designed, to the greatest

possible extent, to provide each part of the screen plate of the diffuser with its share of the washing liquid.

This object is achieved by a device of the type mentioned at the outset in which each of the said nozzle is provided with openings for washing liquid which open out at different predetermined levels and that a channel for supplying washing liquid is arranged to each opening in the nozzle. Preferred embodiments of the device have been given the features which are evident from the subclaims.

Use of the device according to the invention provides better distribution of the washing liquid along the whole of the extent of the height of the screen plate, which, in turn, must improve the efficiency of the machine and prevent local thickening in the screen, which can give rise to an increased requirement for hydraulic power. The invention is described in more detail below with reference to the attached Fig. 1, which shows a preferred embodiment.

Fig. 1 shows a screen plate 1 which is arranged in a diffuser which is not shown. In front of the screen plate 1, a first, elongated distribution nozzle 2 is arranged in such a way that, in the main, it extends with its tip 3 to the lower edge 4 of the screen plate 1. A second, elongated distribution nozzle 5 extends with its tip 6 to immediately above the middle of the height of the screen plate. Both the distribution nozzles 2 and 5 are designed to be connected to a nozzle plate, which is not shown, for supplying washing liquid to the nozzles via throttle holes, the cross-sectional area of which is predetermined in relation to the current quantity of liquid passing through the connected ^' nozzle.

Each nozzle 2 and 5 is provided with three openings 7, 8, 9 and 10, 11, 12, respectively, which open out at different levels calculated from the tip

and upwards, with the three openings 7, 8, 9 on the first nozzle 2 being distributed over the lower half of the screen plate 1 and the three openings 10, 11, 12 on the second nozzle 5 being distributed over the upper half of the screen plate 1, so that the washing liquid which flows into the diffuser out of the openings 7-12 is distributed evenly over the whole height of the screen plate.

Channels 13, 14, 15, each of which is connected to its own opening 7, 8 and 9, respectively, are arranged in the first distribution nozzle 2. In the same way, channels 16, 17, 18 are arranged in the second distribution nozzle 5, each of which channels is connected to its own opening 10, 11 and 12, respectively. The distribution nozzles 2 and 5 are connected to the throttle holes in the nozzle plate. It is also possible to connect each channel 13-18 in distribution nozzle 2 or 5, respectively, to a socket, thereby rendering it possible for each channel to be connected to a throttle opening in the nozzle plate. As a consequence of the movement of the pulp or the location of the nozzles in the diffuser, it can be possible to produce a differentiated supply of washing liquid to the channels in the nozzles. By means of the embodiment shown in Fig. 1 and described above, washing or displacement liquid is distributed at six different levels of the height of the screen with the aid of the two nozzles 2 and 5. Naturally, it is possible, within the scope of the attached patent claims, to choose a different number of openings or channels in each nozzle, as it is likewise possible to vary the number of nozzles in dependence on the size of the screen plate or the number of screen plates . Although the invention has been described with reference to the embodiment shown in the attached drawings, it is naturally possible to modify the inven¬ tion within the scope of the attached patent claims.