DE2154558A1 - FULL-CASED SCREW CENTRIFUGE - Google Patents

Description

8313 Vilsbiburg

Schwaiblmeierweg 3 Vilsbiburg, 10/22/71

Solid bowl screw centrifuge

The invention relates to a solid bowl screw centrifuge even. Called a decanter> based on the direct current principle.

It mainly refers to a solid bowl screw centrifuge, which is used for the thickening of sewage sludge. In centrifuges of this type, the Chemical flocculant added to the centrifugal medium to achieve a clear flow from the decanter. By adding chemical flocculants it is it is no longer necessary to run the centrifuges at very high speeds. It turned out that a multiple of the acceleration due to gravity between 500 and 800 for a satisfactory separation of the solids without further ado is sufficient.

In the case of solid bowl screw centrifuges based on the direct current principle, the centrifuged material is fed into the larger diameter of the drum. The cleaned liquid is drained off in a known direct current decanter (German patent specification 102 05 75) in the screw body, whereby the liquid in the screw body runs to the large bowl diameter and there through openings which are sealed against the drum contents, is discharged to the outside. In another known DC decanter (German Patent 1274997) the cleaned liquid is removed by a peeling device, which is arranged in the screw body. The screw body is at the point where the peeling organ works enlarged in diameter and provided with openings. The peeling organ is adjustable in diameter to be able to work with different fluid levels.

3098 19/0083

- O M>

The described two forms of DC decanters adhere to various disadvantages caused by the invention Decanters to be avoided "

In the first described DC decanter takes place the removal of the cleaned liquid in the interior of the screw body. Due to this construction one is forced to to choose the diameter of the screw body so large that it is in any case with the entire surface area must be immersed in the liquid ring. As a result, 1. the clarification volume is reduced and also turbulence In addition, the supply is also caused precisely at the upper layer of the liquid ring of the centrifuged material and the discharge of the cleaned ™ ten liquid can only be achieved with relatively complex parts «. A change in fluid level in the drum is only possible to a very limited extent. The flow speed in the interior of the screw can hardly be influenced, as a result of which certain substances settle in the Snail interior.

In the case of the second direct current decanter described, the cleaned liquid is removed by an adjustable peeling element. The peeling member is arranged in Innenraüm of the screw body at the point of engagement of the peeling member in the liquid ring of the worm is increased ^ body and provided with openings through which openings the cleaned liquid flows into a chamber in the screw interior, where it is peeled off by the peeling member _o here also The screw body dips into the liquid jacket at the peeling point and thereby constricts the passage of solids considerably. In addition, the peeling organ, which is stationary opposite the drum jacket, triggers strong eddies which also act in the separating space. The peeling element located in the interior of the screw represents a very expensive and complex device. Adjustment of the liquid level is only possible to a limited extent here.

3 0 D 8 1 9 / ü 0 B 3

The invention is based on the object of a full-jacket screw centrifuge to make available according to the direct current principle, the disadvantages described does not own.

The object is achieved according to the invention in that the return of the purified liquid through pipes or gutters that are outside the liquid level of the drum "

Such channels or pipes can only work if a certain vacuum is built up in these pipes will. With high-speed decanters of this type, the level difference that can be achieved by means of a vacuum is so small that it cannot be exploited. With decanters however, those used for thickening sludge and those with the help of flocculants work, the speed is so low that a level difference of up to 4 cm can be achieved through a vacuum. This vacuum can be built up by a built-in pump, but it can, after a preferred embodiment of the invention ^ also by the draining liquid is generated by itself «.

The spin medium runs at the larger drum diameter in the separation chamber of the centrifuge a _o The direct flow of the spin medium in the direction AbIaufbohrungen is «closed by a disc which is mounted on the drum casing and which is above the normal level of the liquid ring, the liquid is characterized dammed up the Tube in which the drain takes place and which is radially angled at the drainage point, dips into the liquid ring. The liquid now continues to rise until it begins to 'overflow' over the disc, which is arranged at the end of the larger drum diameter, overflowing liquid is collected in a channel that has two or more nozzles axially guided drainage pipes _/ which are now generated by the

- 309819/0083

Suction, the liquid overflowing the disc, begin to work.

The suction can of course initiated water are also produced by from the outside, the continuously with a small amount flows ₀ As already said, may also include a vacuum pump fixed in the machine to be installed, which generates a certain vacuum in this tube when the tube front with the Part immersed in the liquid level,

The advantages achieved with the invention are in particular that the drain pipes only with the suction point immerse in the liquid jacket and thereby no turbulence caused on the surface will. This is especially true when using machines in | sludge drainage is particularly important. An embodiment of the invention is shown in the drawing and is described in more detail below:

Show it:

FIG _o 1 a section through a decanter according to the uniflow principle, with downcomers above the liquid level, the work by vacuum "

FIG. 2 shows a section of the arrangement of the nozzles of the nozzle shown in FIG. 1 that generate the vacuum DecanterSun

Fig. 3 is a partial section through a decanter according to the ^ DC principle, in which the vacuum in the Ab

running pipes is created by externally supplied water ο

Fig. 4 is a partial section through a decanter, in which the vacuum in the discharge pipes by a permanently installed Pump is generated in the decanter.

5 shows a partial section through a decanter according to the DC principle, in which the vacuum in the

309819/0083

Drain pipes through, a PUmPe _x installed outside the decanter is achieved _o

In Fig. 1, the centrifugal material runs through the inlet pipe 1 into the screw body 2 and is openings 3 in the separating space 4 of the centrifugal. The centrifugal medium now flows following the screw flights in the direction of the smaller drum diameter. The solids sediment on the inner wall of the centrifugal drum 8 and are captured by the screw helixes 7 and conveyed in the direction of smaller drum diameters, where they are ejected through the discharge bores 9. The cleaned liquid collects on the liquid surface and begins to overflow after a corresponding filling over the disc 10 at the larger diameter of the drum _o This creates a suction at the nozzles 11 in the drainage pipes 12, which are arranged close above the surface of the liquid. As a result of the suction generated, the cleaned liquid runs in the drain pipe 12 to the larger drum diameter and leaves the centrifuge there through the bores 13. The drainage pipes 12 are arranged in such a way that their immersion depth at the take-off point is several mm deeper than the inside diameter of the disc 10, so that when the drainage pipes are working, there is no longer any overflow over the disc 10.

In Fig. 2 it can be seen that the nozzles generating the suction are arranged so that they can be adjusted through the drain holes 13, so that the gap between the Drain pipe 12 and the nozzle 11 is adjustable.

3 shows a water supply pipe 14 fastened in the inlet pipe 1 through which water is introduced into the chamber 15 which is fastened to the screw body 2. The introduced water creates suction in the drain pipe 12 and the drain pipe begins to work _o The nozzle 11 is also here adjustable from the outside through the bore 13 o

30 9 8 1 97Ü083

In Fig. 4 the suction is generated by a disk 16 which is fastened to the bearing cover 17 o The disk 16 carries radial Ribs and has only a very small distance from the drum cover 18. The radial ribs can also be on the Be arranged drum cover 18, then the disc 16 is a smooth disc =,.

The resulting negative pressure is introduced through the bore 19 in the drum cover and in the screw body into the chamber 20, which is attached to the screw body _{or the like}

When the centrifuge starts to work, a certain amount of liquid runs over the / disk 10 into the chamber and closes the annular gap. The clarified liquid now running off leaves the chamber 21 _{o via the bore 13}

In FIG _o 5, the vacuum is required to work the Äbläufrohre 12 through an outside of the centrifuge located vacuum pump "produced via the pipe 22 disposed in the inlet tube 1, the negative pressure is introduced into the chamber 20? If the space 21 is now filled by the overflow of the liquid over the disc 10, the chamber 20 is sealed and a vacuum is created in the inlet pipe 12, which starts to work, the overflow of the cleaned liquid flows out through the bore to the outside, _etc.

3098 1 9/0083

Claims (1)

Claims Claim '/ l) Solid bowl screw centrifuge according to the direct current principle, in which the material to be centrifuged is fed through an inlet pipe at the end or near the end of the larger drum diameter into the separating chamber of the centrifugal drum, characterized in that the cleaned liquid is returned through pipes or channels lie outside the liquid level and work through vacuum _{or the like} Claim 2 solid bowl screw centrifuge according to claim 1, characterized in that the vacuum in the Drainage pipes is achieved in that liquid over a larger drum diameter arranged disc (10) flows to a nozzle system that generated the negative pressure Claim 3 solid bowl screw centrifuge according to claim 1, characterized in that the vacuum in the Drain pipes is achieved by a liquid that is fed in from the outside « Claim 4 Claim 5 Solid bowl screw centrifuge according to claim 1, characterized in that the vacuum in the Drain pipes is achieved by a vacuum pump that is attached to the centrifuge. Solid bowl screw centrifuge according to Claim 1, characterized in that the vacuum in the discharge pipes is achieved by a vacuum pump which is arranged outside the centrifuge _{or the like} 30 98 19/0083 Empty soap