JPS5946718B2 - Screw Press - Google Patents

Description

[Detailed description of the invention] This device relates to improvements in screw presses.

In general, a conventional screw press, as shown in Fig. 1, consists of an outer cylinder 3 made of a cylindrical filter medium provided between a supply port 1 and a discharge port 6, and a screw shaft 4 with internal screw blades provided in the outer cylinder. Moreover, by sequentially reducing the annular gap volume between the outer cylinder 3, screw blades, and screw shaft, and sequentially compressing the compressed material supplied to the supply port 1 while feeding it in the axial direction by the rotation of the screw shaft 4. It has a structure in which the liquid is discharged to the outside of the case, while the compressed material that has finished being compressed is discharged from the narrowest annular part between the nut 5 and the discharge port 6 at the end of the screw shaft.

These are effective for paper making, oil extraction, fruit juice staining, etc., but in the compression dewatering of fine particles such as sludge generated in wastewater treatment, the material to be compressed has fluidity, so it is not possible to obtain a sufficient squeezing effect. If the result is not obtained, reduce the rotation of the screw shaft,
One method is to increase the filtration time to lower the moisture content of the cake.

Furthermore, since these fine particles have a low coefficient of friction, as the compression rate increases, a co-rotation phenomenon occurs with the screw shaft, making processing impossible.

The object of the present invention is to provide a first screw shaft and a second screw shaft to provide an effective compression dewatering means and a co-rotation prevention means, and to obtain a dehydrated cake with a low moisture content.

The present invention will be explained in detail below with reference to the drawings.

Referring to FIGS. 2 to 4, reference numeral 10 denotes a main body, which includes a supply port 11, a holder 12, and a cylindrical filter medium outer cylinder 13.

Inside the cylindrical filter medium outer cylinder 13, from the supply port 11 to the extrusion port 14
A first screw shaft 15 having a first screw blade 16 extending halfway up the outer periphery is inserted, a thin shaft portion 117 at the tip of the shaft 15 is supported on a second screw shaft 18, and a second screw shaft 15 is inserted.
A second screw blade 19 is attached to the outer periphery of the screw shaft 18.
are provided so that their outer peripheries become larger in diameter as they go from the first screw shaft side to the extrusion port, and are rotatable with respect to each other.

First screw blade 16 and second screw blade 19
During this period, the ring-shaped protruding blade 16' of the first screw blade 16 is slightly extended to slightly reduce the squeezing resistance when being pushed out from the first screw blade, and engages with the second screw blade. let

The first screw shaft is connected to a rotation transmission mechanism such as a pulley 20.
is driven by a deceleration motor 21.

The squeezing operation of the first screw blade is the same as that of the general screw press, and as shown in FIG.
The shaft 15 and the blade 16 up to the shaft end E of the screw shaft.
By sequentially decreasing the annular volume between the two, the liquid content formed by the compressed dewatering material is discharged from the mirror body of the outer cylinder 13 to the outside, and the solid content concentration is increased.

In such a screw press, the moisture content of the cake can be lowered by reducing the thickness of the dehydrated cake, which is determined by the gap between the screw shaft at the terminal end E of the screw press and the outer cylinder. If it is made smaller, there is a drawback that the ability to transfer the pressed material decreases.

Therefore, in the present invention, this gap A is set larger than usual.

In 1973, it was reported that mixing and stirring was effective as a means of lowering the water content because even though the outer cover of the filter becomes hard due to dehydration, the inside becomes sticky and dehydration cannot be carried out.
Inserting mixing and stirring during the continuous screw dehydration process described in Japanese Patent No. 21187 is considered disadvantageous because it requires a longer space.

The second screw shaft 18, which is provided from the first screw shaft end E to the extrusion port, has blades 19 on the outer periphery so as to sequentially scrape off the material extruded by the first screw with a thickness of the clearance A from the inside of the material to be pressed. The outer diameter is gradually increased toward the extrusion port, and the outer diameter at the extrusion port is D".

The gap G with the outer cylinder is smaller than A, and this portion corresponds to the final extrusion port of the so-called freeboard C which is not affected by the blades from the end of the first screw blade 16' to the outlet.

The second screw shaft 18 has a rotation transmission mechanism 2 in a thin shaft portion 22.
3 and is driven by a deceleration motor 24.

The number of rotations of the first screw shaft and the second screw shaft is set to N1. When N2, the transfer amount Q2 at point E of the second screw shaft (P - pitch at point E of the first screw) is (P
'- is the pitch at point F of the second screw) From the above, the amount of movement Q3 of the free board from the gap G is the compression ratio for the amount of movement from point E. Qt'' When Q2 + Q3, the compression ratio is 1. By decreasing Q2, the compression rate from E to F changes, and appropriate compression dehydration can be performed.

In this case, the second screw scrapes off the pressed material from the first screw in a wedge-like manner, thereby dewatering by shearing. If the filter tube is provided with a large number of small holes, water will be removed inside the outer tube 3, and this can be an effective means for lowering the water content.

The free board C is the area from the tip of the first screw blade 16' to the extrusion port G. In conventional screw presses, if this is too long, a solid concentration of the material to be pressed is required to be extruded, which increases the compression rate. Although this method lowers the water content, there are problems such as the tendency for co-rotation to occur.

This co-rotation phenomenon is related to the compression force as well as the friction coefficient with the outer cylinder, but the freeboard part of the present invention forms a wedge-shaped space, and the side surface of the second screw is opposite to the first screw that provides the propulsive force. Since it is in contact with the blades 19 and is successively scraped off, it acts by mutual compression and is propelled, so it has the advantage that the squeezing action with the first screw is smaller than when it is directly propelled only by the first screw.

Therefore, since the outer periphery of the second screw is fixed with a wedge, it is difficult for slippage to occur here, and the compression force of the first screw can be smaller than that of conventional ones, and the tip of the first screw can be attached to the inside of the second screw. and these two
Since there is a rotation difference between the two, it has an anti-slip effect and prevents the co-rotation phenomenon.

Another advantage of the present invention is that it can be operated freely by greatly changing the dewatering time, supply amount, and compression rate.

In other words, in addition to changing the rotation speed of the second screw, it is also possible to freely select the rotation speed of the first screw, so when compressing and dewatering sewage sludge, concentration,
Properties etc. can be easily followed.

In conventional screw presses, such a free choice is not possible.

FIG. 3 shows a modification of the embodiment shown in FIG. 2 in which the difference in rotation between the first screw and the second screw is made by a differential gear, and the shaft 22 is connected to the first output shaft of the differential gear. are fixedly connected via a box 25, a second output shaft of a differential gear 26 is disposed on the shaft 17 of the first screw, and the input shaft 27 of the differential gear is driven by a motor. , the rotation of the first screw is applied in the same manner as in the example of FIG. Make the number output.

By changing the input rotation speed of the differential gear, the differential rotation speed between the first output shaft and the second output shaft can be freely changed. 1) There is an advantage that the rotational speed of the first and second screw shafts does not change due to slippage of the pulley, motor, etc.

As described above, according to the screw press of the present invention, the first screw shaft on the squeezed material supply port side is formed to have a gradually larger diameter toward the extrusion port, and the screw blades disposed thereon have the same outer diameter. In addition to adjusting the dimensions, the second screw shaft located on the extrusion port side is formed to have the same outer diameter as the outer diameter of the end of the first screw shaft on the extrusion port side, and the screw blades arranged thereon are formed so as to face toward the extrusion port. Since the diameter is gradually increased, the first
The object to be processed is squeezed and extruded with a screw blade, and the extruded object is scraped off with a second screw blade,
It is possible to perform the dewatering action by shearing and extrusion, and it is possible to obtain extremely good squeezing and dewatering efficiency, and due to the rotational differential between the first and second screws,
There is no fear that the material to be processed will co-rotate with the second screw, and operation can be performed by freely changing the dehydration time, supply amount, and compression rate by arbitrarily selecting the rotation speed of both screws. be.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional screw press, Fig. 2 is a sectional view of a screw press according to the present invention, Fig. 3 is a similar view to Fig. 3 showing one change, and Fig. 4 is an enlarged view of main parts. FIG. 10...Main body, 15...First screw shaft, 16...First screw blade, 18...
...Second screw shaft, 19...Second screw blade.

Claims (1)

[Claims] 1. In a screw press consisting of an outer cylinder made of a cylindrical filter medium and two relatively rotatable coaxial screw shafts provided inside the outer cylinder, the first screw shaft on the side of the compressed material supply port is pressed. The diameter is gradually increased toward the exit, and the screw blades arranged thereon are made to have the same outer diameter,
The second screw shaft located on the extrusion port side is formed to have the same outer diameter as the outer diameter of the end of the first screw shaft on the extrusion port side, and the screw blades arranged thereon gradually increase in diameter toward the extrusion port. A screw press characterized by forming.