US3214022A - Apparatus for cleaning hydrocyclones - Google Patents

Description

of. 26, 196s N. A. L. WIKDAHL 3,214,022

APPARATUS FOR CLEANING HYDROCYGLONES Filed June 11, 1956 lyllmmigy-Ill IN1/EN TOR /J//m Aw;

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@fro mvfr United States Patent O The portion of the term of the patent subsequent to Aug. 3, 1976, has been disclaimed 1 Claim. (Cl. ZIO-138) The present invention relates to an apparatus for the separation of fractionation of suspensions by means of hydraulic cyclones. Generally, such hydraulic cyclones consist of a conical chamber of circular cross-section into which the suspension is introduced tangentially under pressure in the enlarged portion of the cone by which turbulences arise causing the heavy fraction to be flung outwards on account of the centrifugal force and to leave .the chamber through the apex. The light fraction leaves thr-ough a central base outlet, the so-called overflow pipe.

vIn the following the operation of the hydraulic cyclones will be described with particular reference to the conical type `although cyclones constructed in the form of a hollow cylinder operate according to the same general principles and the phrase apex outlet will be used hereinafter to describe the opening from which the heavy fraction is emitted not only from the conical type cyclone but from the cylindrical type cyclone as well.

When using such cylones it is often necessary, in order to obtain a satisfactory separating effect, t-o give each cyclone a relative small capacity. tities of liquid, for instance in water purifying or in the purification of pulp for the manufacture of paper, a hydraulic cyclone plant, thus, consists Vof a very great number of small cyclones. In the operation of such plants it often occurs that the cyclones are plugged in the apex outlet, i.e. the outlet for the heavy fraction, and the separating effect is then reduced" or even brought to naught. Hitherto, the cleaning of these plugged cyclones was made manually.

The present invention relates to .an apparatus which eliminates these drawbacks and is characterized thereby that the outlet for the leaving heavy fraction is expanded intermittently. Thus, the apex outlet which generally during operation is kept at a constant predetermined cross-sectional area is intermittently expanded for a short period and then is caused to reassume the predetermined cross-sectional area.

This can be obtained by applying hydraulically a certain pressure about the apex outlet so that its inner diameter or cross-section area stands in a certain proportion to the hydraulic pressure. By reducing the pressure the cross-sectional area of the apex outlet is increased.

It is also possible to obtain this expansion of the crosssection of the apex outlet by periodically `choking the base outlet or the outlet for the light fraction so that a ternporary increase of the pressure in the apex outlet is obtained. The choking or throttling of the base outlet should preferably be maintained only for a short period of time.

As already mentioned the choking of the base outlet will result in .an increase of the pressure in the apex outlet. If this outlet is plugged by particles baked together or the like, the increased pressure will result in an expansion of the outlet which may be of an elastic material, such as rubber, thus making it possible for the plug to pass through the outlet.

After operation for some time the apex outlet nozzle In case of large quan- ICC may have got a larger cross-sectional area on account of wear. To keep the cross-sectional area constant a ring of soft rubber or similar elastic material may be placed around the nozzle, so that the nozzle is contracted to the desired cross-sectional area. The ring being of elastic material it does not prevent the apex outlet from expanding when choking the base outlet.

The accompanying drawing illustrates an embodiment of an apparatus according to the invention. FIG. l. shows diagrammatically the first step in a hydraulic plant for purification of paper pulp. FIG. 2 shows on a larger scale a section through the cone apex of a hydraulic cyclone provided with an outlet nozzle of soft rubber, and FIG. 3 shows the same detail as expanded.

The plant illustrated in FIG. l consists of a number of hydraulic cyclones 10 to which paper pulp is fed from a feed pipe 11, common to all of the cyclones, tangentially through inlets 12. The light fraction obtained at the separation leaves through overflow pipes 13 (hase outlets) in each cyclone and the heavy fraction leaves through the apex outlets of the cyclones and is led from there to a collecting groove 14. From the overflow pipes 13 the light fraction leaves toa common pipe 15 and from there it is conducted further on for other treatment. In this pipe 15 there is arranged a valve 16, which is opened and closed by a motor 17 in certain time intervals, for example for two seconds each half hour. When the valve 17 is closed, the pressure will be greater in the cone apiees which are constructed in the manner illustrated in FIG. 2. The outlet nozzle shown therein consists of a part lil of soft rubber having internally a conical bore. When the pressure in the system is increased in the manner mentioned above, the outlet nozzle will expand to the shape shown in FIG. 3, and if some of the hydraulic cyclones should be plugged the plugs will obviously be thrown out and removed.

If the outlet nozzle should get a larger cross-sectional area due to wear, a ring 19 of soft rubber may he placed around it. This ring should be so elastic as to give the nozzle the desired cross-sectional area. On account of the elasticity of the ring 19 it is possible to increase the cross-sectional area temporarily in the manner described above.

What I claim is:

Apparatus for separating solid particles in liquid suspensions comprising an elongated chamber of circular cross-sectional configuration, means for introducing a stream of the suspension into one end of said chamber tangentially to the wall thereof, a first outlet disposed adjacent said one end, a hollow member formed of rub ber-like elastic material secured solely at one end to the other end of said chamber to provide a second outlet for said chamber through the other end of said member,1 said member being free to expand radially when the pressure within said second outlet is increased above normal operating press-ure to free said second outlet of accumulated solid material tending to obstruct the same, and time-controlled means for 4intermittently increasing the pressure within said second outlet.

References Cited by the Examiner UNITED STATES PATENTS 2,308,476 l/43 Gerrer 299-133 X 2,402,741 6/46 Draviner 299--133 2,671,560 3/54 Fontein et al. 209-211 2,765,918 10/56 Fontein et al. 210-84 REUBEN FRIEDMAN, Primary Examiner.

HERBERT L. MARTIN, CHARLES F. KRAPFT,

Examiners.

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