JPS5834012A - Operation of filter press - Google Patents

Abstract

PURPOSE:To enhance the efficiency of a filter chamber volume changeable type filter press, by a method wherein a cake formed by a raw liquid pressure introducing process is pressed to be collected to the center part of a filter chamber and the cake formation due to pressure introduction of a raw liquid is carried out by a filter cloth on which a cake layer is not formed at all times. CONSTITUTION:A raw liquid is supplied under pressure from a supply valve 11 and a supply port 12 to be filtered by a filter cloth 7 and the filtrate is discharged from a discharge port 10 along a grid groove 9. When a cake reaches a predetermined thickness, a valve 11 is closed and a filter plate 5 is pressed by a press plate 4 to deform an elastic outer peripheral framework 6 and, thereby, a filter chamber 8 is narrowed to mechanically dehydrate said cake. In the next stage, the press plate 7 is returned to be easily released from the filter cloth 7 and the cake 13 is formed at the center of the filter chamber 8. When the valve 11 is opened again and the raw liquid is supplied to the filter chamber 8, said raw liquid is easily filtered because the inner peripheral wall of the filter chamber 8 is present in such a condition that the filter cloth 7 is exposed and the cake 13 is not collapsed within a short time. Mechanical dehydration is again carried out and these operations are repeated to easily increase the amount of the cake in the filter chamber 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an efficient method of operating a variable chamber volume filter press.

Conventionally, when performing filtration, a cake is formed in layers on a filter cloth in order to form a cake of a required thickness. In such filtration systems, the rate of cake formation is proportional to the operating pressure and to the tenth power of the filtration time according to simplified filtration theory. This reduces the thickness of the resulting cake to 2
In other words, the above phenomenon means that as the cake thickness increases, the time required for filtration increases rapidly, and the filtration time increases as the operating pressure increases. Even if it is #1, it is not shortened.

In addition, in a filter press, in order to further reduce the water content of the cake produced by filtration by pressurizing the raw solution, the filter chamber is narrowed and the cake is mechanically compressed and dehydrated. In other words, there is a method in which a diaphragm is inflated through a filter cloth, or an elastic body is attached to the edge and a filter chamber is formed by nine filter plates, and a K peak is generated by pressurizing the stock solution, and then a hydraulic cylinder is used. There is a method of compressing the filter plate and narrowing the filter chamber by deforming the elastic body.

A filter press incorporating the above-mentioned squeezing process is usually operated in a batch mode. Its driving cycle is ■
Filtration by pressurized delivery of stock solution ■Filter chamber.

The process of compressing and dehydrating the resulting cake by narrowing the frame, opening the frame, discharging the cake, and closing the frame is one cycle.

In order to improve the capacity of such a filter, it is necessary to shorten the cycle time or increase the amount of cake produced during the cycle, so that the improvement in buffalo cart removal per unit time is minimal. There is no. In the cake discharging step (2), if a cake that is easily peeled off from the filter cloth is produced, the discharging time can be shortened. It is well known that K, which produces the above-mentioned easy-to-peel cake, has a low water content and can produce a thick cake.

However, if the thickness of the cake layer is increased, the time required for the filtration step (2) increases exponentially with the cake thickness, as described above, and becomes the dominant factor in the total cycle time. It must be shortened as much as possible. In addition, in the squeezing process, the cake produced by filtration is further dehydrated by mechanically squeezing the cake by narrowing the greenhouse, but the thinner the layer of the cake, the faster it is dehydrated. However, the peeling of the cake from the filter cloth after dehydration is better when the cake is thicker.

As mentioned above, each process except for the open frame and closed frame processes during the 1 cycle has an effect on each other.If the filtration process, which is the dominant factor in the time required for the C1 cycle, is shortened, the cake layer becomes thinner. However, if a problem arises in the discharge process and an attempt is made to thicken the cake layer, the filtration time increases significantly and the cycle time becomes longer, resulting in a disadvantage that the efficiency is greatly reduced.

In view of the above circumstances, it is an object of the present invention to provide an efficient operating method for a greenhouse variable volume filter press, in which the stock solution injection process and the subsequent compression process are alternately repeated. The cake produced by the injection of the stock solution is compressed and collected in the center of the chamber, and the cake formation by the injection of the stock solution is always carried out through a filter cloth on which no cake layer is formed.

The method of the present invention will be explained below with reference to the drawings.

FIGS. 1 to 3 show an example of an apparatus for explaining the present invention in detail, and numeral 1 in the figures is a greenhouse variable volume type filter press. In the filter press 1, a large number of filter plates 5 are disposed between a fixed plate 2 and a suppressing plate 4 that is moved by a piston 3a of a hydraulic cylinder 3. An outer peripheral frame 6 passing through an elastic material is provided on the outer peripheral edge portions of both sides of the filter plate 5. In addition, the filter plate 5
A filter cloth 7 is provided between the filter cloths 7 and 7, and as shown in FIG. 7, they are pressed together by the suppressing plate 3 to form a greenhouse 8.

On the inner surface of the outer peripheral frame foot of the filter plate 5,
Grid-like grooves 9... are provided. In order to discharge the filtrate to the outside, the lower part of this grid-like groove 9...
One end of the filtrate discharge hole 10 provided in the filter plate is opened, and the other end of the discharge hole is opened at the lower edge of the filter plate 5.

Further, a through hole 12 is provided which penetrates the fixed plate 2, filter plate 5, . . . and supplies water to each greenhouse 8 .

Filter press greenhouse configured in this way 8...
As shown in FIG. 2, the stock solution is supplied under pressure through the supply valve 11 and the through hole 12. The stock solution is filtered by the filter cloth 7, and a cake layer is formed on the filter cloth 7. The filtrate that has passed through the filter cloths 7 is discharged through the grid grooves 9 and through the filtrate discharge holes 10.

When the cake layer reaches the specified thickness, stop supplying the stock solution,
With the valve 11 closed, the filter plates 5 are pressed by the pressing plate 4 as shown in FIG. By this operation, the elastic outer peripheral frame 6 is deformed, the greenhouse 8 is narrowed, and the cake is mechanically squeezed and dehydrated.

After sufficient dehydration, the suppression of the suppression plate 4 is released, and the greenhouse 8...
Return the size to its original state. At this time, by making sure that the cake has a predetermined thickness and is sufficiently dehydrated, it can be easily separated from the filter cloth 7, and as shown in Fig. A plate-like cake 13 is formed in the greenhouse 8, and the filter cloth 7 from which the cake has been peeled is formed on the inner peripheral wall of the greenhouse 8.
...becomes...

Next, the stock solution supply valve 11 is opened again to supply the stock solution to the greenhouse 8 . In this case, since the filter cloths 7 are exposed on the inner peripheral wall of each greenhouse 8, the stock solution is easily filtered and a cake layer is formed on the surface of the filter cloths 7. At this time, the greenhouse 8... central plate cake 13... is sufficiently dehydrated and solidified, so it will not collapse in a short period of time even if it comes into contact with the stock solution introduced. To some extent, the cake layer is filter cloth 7.
...When the liquid is produced above, the supply of the stock solution is stopped and the valve 11 is closed.

Next, as shown in FIG. 6, the greenhouse 8...
・Narrow the cake and mechanically squeeze the cake to dehydrate it.

In this case, the amount of cake will be the plate cake 13... plus the newly generated cake, resulting in an even thicker dehydrated cake.
The filter cloth 7... is further easily peeled off to form a plate-shaped cake 13.
...becomes.

By repeating the above operations, the amount of cake in the greenhouse 8 can be easily increased. In particular, in the method of the present invention, in the first filtration, it is necessary to form a cake with a certain thickness to improve peeling, but in subsequent filtration, the previous filtered cake is added to the cake layer. The thicker the thickness, the better the releasability from the filter cloth 7. Furthermore, since filtration is always performed using the filter cloth 7 on which no cake layer is formed, filtration can be performed efficiently and the amount of cake (or stock solution) processed per unit time can be increased.

EXAMPLES The present invention will be specifically explained below with reference to Examples.

Example Diameter of filtration surface rocwt, number of filter plates 1, actual filtration area of the filter plate 1
Using a greenhouse variable-volume filter press of the same type as in Figure 1 of 0-, purified water sludge with solids concentration s, twt was filtered under pressure A kp/cII for 60 minutes,
The cake was then dehydrated by pressing at a pressure of tskq/al for to minutes, and the cake was collected in the center of the greenhouse. Furthermore, t.

Pressure filtration of the stock solution for 1 minute and press dehydration for 30 minutes were repeated λ times. The results are shown in Table 7.

Comparative Example Using the same filter press as in the example, the filtration time was carried out by force-feeding the stock solution for 2 io minutes at a pressure of 171 kr/d and then a pressure of 171 kr/d. It was compressed and dehydrated for 220 minutes at kg/cit. The procedure was the same as in the example except that filtration and compression dehydration were not repeated. The results are listed in Table 7 together with the results of Examples.

Further, the operating state is shown in Fig. 7.

As is clear from the table, the operating method of the present invention allows for a significant increase in equipment capacity without any changes to the equipment.

As described above, in the operating method according to the present invention, the undiluted solution is always pumped to the filter cloth to which no cake layer is attached, and the cake layer is removed by squeezing before it becomes too thick. This is an extremely excellent method for operating a greenhouse variable volume reduction filter press, as it can increase the filtration efficiency, which is a dominant factor in cycle time, and also makes the cake thicker, making it easier to discharge.

Although the explanation was given for a filter press using a filter plate made of an elastic material, this operating method can be applied to all greenhouse variable volume filter presses (for example, diaphragm compression type).

[Brief explanation of drawings]

7 and 6 are vertical views showing an example of a variable greenhouse volume filter press for explaining the present invention in detail, FIG. 7 is a view showing a closed state, and FIG. Figure 3 is a diagram of supplying the stock solution to form a cake layer on the filter cloth.
Figure 3 shows a state in which the greenhouse volume has been narrowed, Figure ≠ shows a state in which the greenhouse has been returned to its original volume and the dehydrated cake is collected in the center of the greenhouse, and Figure 3 shows a state in which the dehydrated cake remains in the center and the undiluted solution is Figure 6 shows a state in which water is being pumped into a greenhouse and filtered.
The figure shows a state in which the volume of the filter chamber is narrowed and filter cakes are compressed and dehydrated on both sides of the dehydrated cake in the center.
-1! -aft/ FIG. 7 is a diagram showing the operating states of the example and the comparative example. 1... Filter press, 2... Fixing plate, 3... Hydraulic cylinder, 3a... Piston, 4... Curved pressing plate, 5... Filter plate, 6... Curved elastic outer peripheral frame, 7... Curved filter cloth, 8... Greenhouse, 9...
Curved grid groove, 1o...Filtrate drainage hole, 11.
...Stock solution supply valve, 12...Curved through hole, 13...
...Plate cake. Applicant Tsukishima Kikai Co., Ltd.

Claims (1)

[Claims] A variable chamber volume type filter press alternately repeats the injection process of the X stock solution and the subsequent compression process,
A method of operating a filter press characterized in that a cake produced by injection of a stock solution is squeezed and collected in the center of a greenhouse, and a new cake is constantly produced on a filter cloth.