SU884553A3 - Method of detecting suspended particles in liquid - Google Patents

Abstract

1281667 Wet screening of materials B G JANSON 19 April 1971 [22 April 1970] 26932/ 71 Heading B2H In a method of separating fine particles from coarse particles in a liquid, e.g. cellulose or paper pulp or food particles, the liquid containing the particles is sprayed against a screen while a pressure difference is maintained between the pressures on the inlet and outlet sides of the screen and a liquid column is maintained in contact with the outlet side of the screen, so that a portion of the liquid together with fine particles and a gas, e.g. air, passes through the screen to its outlet side while the coarse particles are arrested by the screen and removed on the inlet side thereof. The screen may have a horizontal, vertical or inclined attitude and the water may be sprayed from above, from beneath or from one side laterally of the screen. The Figs. I and 2, a collecting chamber 10 of a separating apparatus contains one or more chambers 15 extending transversely or, as shown, longitudinally thereof. The or each chamber 15 is provided with a vertically adjustable liquid supply pipe 19 having one or more spray nozzles 21. The upper wall 18 of the chamber 15 is provided with a screen 18 which may be flat, conical or dome-shaped. Liquid in the collecting chamber 10 is maintained at a selected level 25 by means of a vertically adjustable spillway 26. The pressure of air in the space 27 above the liquid level 25 is maintained by a pump or fan 29 at a higher value than the pressure in the space 28 in chamber 15 above the level 23 of the portion of the liquid which collects in the chamber and whose level is controlled by a vertically adjustable spillway 24. The liquid in chamber 15 is drained through a pipe 30 and recirculated to the apparatus. Air may be mixed with the liquid supplied through the pipe 19. The fine particles passing through the screen 22 floats to the top of the liquid in chamber 10 and is discharged through the spillway 26, purified liquid being discharged through a pipe 29'. In Fig. 3, a separator comprises a housing 30 in which a pipe 32 having a nozzle 33 is vertically adjustable. The jet of liquid supplied to the pipe 32 impinges against a screen 34 above which the liquid column is formed. A number of the separators may be arranged in a row as in Fig. 4. Liquid containing coarse and fine particles and air is fed through a common line 318 Liquid and coarse particles are discharged through an outlet pipe 37 on the floor of each housing to a common outlet line 39. Liquid, fine particles and air pass through the screens 34 and are conducted through a common line 40 to a flotation chamber 41. In the line 40 are located a pump 42 and a pressure regulator (not shown) which regulates the pressure in the line. Other arrangements of .the separators are described.

Description

The invention relates to methods for filtering liquid through a partition and can be used in chemical technology and related fields, in particular in pulp and paper ₅ and the food industry.

A known method of filtering a liquid by supplying a jet of it to a horizontal filter baffle, which creates a pressure drop. u

The liquid is sprayed on an inner coarse filter surface on which large particles are separated, and then fed to an intermediate filter surface on which a filter layer of fine particles is formed. Then the liquid rises, passing through the outer filter surface. The rise of the liquid is carried out under the influence of an increasing pressure drop on the filtering surfaces and the layer of filtered fine particles [Ί].

The disadvantage of this method is the frequency of the process, since 25 the latter must be interrupted to remove material that has accumulated on the inner and intermediate filter surfaces. The method also does not allow to increase the pressure difference on each side of the filter above a predetermined specific value in order to increase the productivity of the filtration process. The efficiency of liquid purification is also insufficient.

The purpose of the invention is to increase the cleaning efficiency and process performance.

This goal is achieved by the fact that the liquid stream is directed to the lower surface of the septum, on top of which a layer of liquid is supported, and the upper part of the layer is continuously subjected to flotation, and the liquid from the side of the lower surface of the septum is directed to sedimentation. .

In FIG. 1 shows a device.

to implement the method (option); figure 2 is a section aa in figure 1; in FIG. 3 unit fractionating element of the device, longitudinal section; in FIG. 4 and 5 are variants of a device including a battery of individual fractionating elements and an external flotation chamber.

The proposed method is implemented in the device as follows.

The contaminated liquid is fed into the chamber 1 through the inlet pipe 2 with nozzles 3 mounted on it, issuing conical jets having a vertical direction. The liquid is sprayed onto the bottom surface of a horizontal filter. rod 4, made in the form of flat sieves or filter plates, or conical or dome-shaped. The distance from the nozzles 3 to the filter baffle 4, which depends on the angle of conicity of the liquid stream, is controlled by raising or lowering the pipe 2. In the chamber 1, the liquid level maintained by the device 5 is kept constant by means of a drain 5. Adjust the vertical • height of the drainage outlet, as indicated by arrows B. Partially purified liquid that has not passed through the filtering partition 4 is discharged through the pipe 6 and returned to the device. In the collection chamber? О, the liquid layer is maintained over the filter baffle 4 at a constant level by means of a drain device 8 with vertical adjustment of the extraction height, as indicated by arrows B. The air pressure above the liquid layer in the collection chamber 7 is adjusted to the required negative pressure by means of a pump or fan through the pipe 9. Above the liquid layer in the chamber 1 set a higher pressure than above the liquid layer in the collection chamber 7 · Differential pressure on the inlet and outlet side of the filter partition 4 create the difference between the air pressure on the inlet side of the partition 4 and the pressure of the liquid layer above the partition 4 with the air pressure on the liquid layer above the partition 4. In some cases, the air pressure on the liquid layer above the partition 4 may be greater than atmospheric pressure, while the air pressure on the inlet side partitions 4 are set, respectively, higher. The pressure difference is selected depending on the design of the filtering partition 4, the pressure of the spray jet, the height to

884553 4 layers of liquid above the partition 4, the type of particles representing contamination in the liquid, and the efficiency of flocculation of particles in the flotation space of the collection chamber 7 or in the flotation chamber 10.

The upper part of the liquid layer in the chamber 7 is continuously subjected to flotation, for which air is mixed with the liquid, ι entering through the pipe 2. When spraying the liquid onto the filtering partition 4, the required amount of air is passed through the latter together with the liquid and fine particles, for example, scraps of threads . The swallowed bundles of threads that have accumulated on the surface of the liquid in the chamber 7 are removed through the drainage device 8, and the purified liquid is removed through the lower pipe 11.

The method can also be carried out in single fractionating elements connected to a battery, in which a layer of liquid is supported over the filter element 12 of the element (on its output side) in a discharge pipe 13 connected either through a collector 14 or directly to a flotation chamber 10. In this case, large particles that do not pass through the partition 12 fall down,, they are removed through the outlet pipe 15.

The invention allows, for example, during the extraction of pulp and purification of circulating water for irrigation of cloth, to increase the efficiency of purification of contaminated liquids and the performance of the process in flotation washing systems using input pressures below 1 kg / cm · * -.

Claims (2)

element of the device, a longitudinal section; in fig. 4 and 5 are versions of the device including a battery of unit fractionation elements and a remote flotation cell. The proposed method is implemented in the device as follows. The contaminated liquid is fed into the chamber 1 through an inlet pipe 2 with nozzles 3 emitting conical jets installed on it, having a vertical direction. The liquid is sprayed onto the bottom surface of the horizontal filtering strip. k rinks, made in the form of flat sieves or filter plates, either conical or dome-shaped. The distance from the nozzles 3 to the filter septum, depending on the angle of taper of the liquid jet, is controlled by raising or lowering the pipe 2. In chamber 1, the level of liquid maintained by the device 5 for draining is kept constant. Adjustment is made in the vertical of the discharge extraction height, as indicated by arrows B. Partially purified liquid that has not passed through the filter septum 4 is discharged through pipe b and returned to the device. In the collecting chamber, the QA maintains a fluid layer over the filtering walls C at a constant level by means of a draining device 8 with a vertical adjustment of the withdrawal height, as indicated by arrows B. The air pressure above the fluid layer in the collecting chamber 7 is adjusted to the required negative pressure by means of a pump or a fan through a pipe 9- Above the layer of liquid in chamber 1, pressure is set higher than above the layer of liquid in the collecting chamber 7- The pressure difference on the inlet and outlet side of the filter septum k create a difference in air pressure on the inlet side of the partition 4 and the pressure of the fluid layer above the partition 4 with air pressure on the fluid layer over the partition wall k. In some cases, the air pressure on the fluid layer above the partition A may be greater than atmospheric, while the air pressure on the inlet side partitions 4 set, respectively, higher. The pressure drop is selected depending on the design of the filtering partition k of the pressure of the spray jet, the heights 34 of the liquid layer over the partition, the type of particles representing the contaminants in the liquid, and the efficiency of flocculation of the particles in the flotation space of the collecting chamber 7 or in the flotation cell 10. Top a layer of liquid in the chamber 7 is continuously subjected to flotation, for which air is mixed with the liquid flowing through the pipe 2. When spraying liquid onto the filter septum k, the required KOJ.H air quality is passed through the latter along with liquid and fine particles, for example, scraps of filaments. The floated bundles of filaments accumulated on the surface of the liquid in chamber 7 are removed through the draining device 8, and the purified liquid is removed through the bottom pipe 11. The method can also be carried out in single fractionation elements connected to a battery in which each filter partition 12 elements (from its outlet side) support a layer of liquid in the outlet pipe 13 connected either through the collector} k or directly with the flotation cell 10.. At the same time, large particles that do not pass through the partition 12 fall down, they are removed through the outlet pipe 15. The invention, for example, when extracting pulp and purifying recycled water for irrigation cloth, improves the purification efficiency of contaminated liquid and the process efficiency in flotation washing systems using inlet pressures below 1 kg / cm. A method of separating particles suspended in a liquid by supplying liquid jets to a horizontal filter wall on which a pressure differential is created, characterized in that, in order to increase the effect According to the cleanliness and performance of the process, a stream of liquid is directed to the lower surface of the partition wall, over which the liquid layer is maintained, the upper part of the layer is continuously floated, and the liquid from the lower surface of the partition is directed to the lag. Sources of information taken into account In the examination 1. Patent of France W 1594785, cl. On 01 D 37/00, 1968.