JPH0534866Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention is a dewatering roller for a sludge dewatering device, and more specifically, a high-performance belt press type dehydrator that can continuously process large quantities of various sludge and reduce the water content. It's about rollers. [Prior Art] and [Problems to be Solved by the Invention] In conventional belt press type dehydrators, smooth rollers have been used as squeezing rollers. However, since this is a single-sided filtration, the dewatering efficiency is poor, and water draining is particularly poor at the center of the filter cloth in the width direction, resulting in an increase in the water content of the dehydrated cake at the center. In addition, drainage grooves have recently been installed on the roller surface, but sufficient consideration has not been given to the shape, dimensions, and position of the grooves, so there is insufficient consideration to separate the filtrate and prevent scale formation. It is hard to say that it is having any effect. That is, for example, when the drain groove 4 is a vertical groove as shown in Fig. 10, there is a problem that the drain opening is blocked by the filter cloth belt (filter cloth) 1 wrapped around the roller, and there is a limit to the amount of drainage. In the case of the mechanism shown in FIG. 9, the dehydrated filtrate flows in the drain groove 4 along the direction of the roller shaft 7 and is discharged from the end of the roller shaft, but the size of the drain groove 4 is not appropriate. There was a problem that it did not flow smoothly and stagnated, and was reabsorbed by the dehydrated cake. In addition, scale tends to form at the end of the roller shaft, and when it grows, it often appears to block the drainage groove 4, resulting in a reduction in the effectiveness of dewatering mud. In addition,
In the figure, numeral 5 indicates the surface of the protrusion of the dewatering roller. As described above, conventional dewatering machines using dewatering rollers have had problems in that it is difficult to continuously process a large amount of sludge and to reduce the water content of the dehydrated cake. [Purpose of the invention] The present invention solves the above-mentioned problems and creates a dewatering roller that has good drainage properties for the dewatered filtrate, is less prone to scale buildup, and is easy to remove, thereby making it easier to treat sludge than conventional rollers. It is an object of the present invention to provide a dewatering roller for a sludge dewatering device that can achieve a significant increase in the amount of water and a significant decrease in the moisture content of the dehydrated cake. [Structure of the invention] The present invention consists of an endless filter cloth belt that is movably hung over a plurality of dewatering rollers in a face-to-face polymerized state, and a muddy material that is dehydrated by squeezing the muddy material between these filter cloth belts. In the material dewatering device, a plurality of drain grooves are formed on the circumferential surface of at least one of the dewatering rollers, the drain grooves communicating from one end in the width direction of the roller to the other end of the roller, and steps are provided at both ends in the width direction of the roller. form,
And, the width A of the stepped portion is 0.1 to 0.1 of the width B of the dewatering roller.
3%, and the depth C of the stepped portion is approximately the same as the groove depth D of the drain groove. [Example] An example of the present invention will be described with reference to Figures 1 to 3.
As shown in the figure, endless filter cloths 1a and 1b are movably hung on dewatering rollers 2 and 3 in a face-to-face overlapping state. Both of these filter cloths 1a and 1b are made of water-permeable or water-absorbing material, and these
The slurry S is compressed by these dewatering rollers while being held in a state of bending and traveling through the pressurized dewatering section formed by the two dewatering rollers, and the slurry S is discharged as a dewatered cake K. . Thus, at least one of the plurality of rollers 2 and 3 has the structure shown in FIGS. 1 and 2. That is, on the circumferential surface of the roller, a drainage groove 4 that communicates from one axial end of the roller to the other end is formed parallel to the multi-strip roller shaft 7, and furthermore, at both ends of the roller in the width direction, A stepped portion 6 having a cutout shape is provided. According to experiments, the step width A of the step portion 6 is the roller width B.
It is important to keep it within the range of 0.1 to 3%,
In this case, the absolute value of the step width A is usually preferably 5 to 30 mm. Furthermore, it is important that the step depth C be approximately the same as the groove depth D. On the other hand, the groove depth D of the drainage groove 4 is preferably 0.5 to 50 mm, and 2 to 20 mm is particularly effective; if it is too shallow, it will be clogged with scale, and if it is too deep, it will only take time and effort to form the groove. , the effect of improving drainage performance cannot be obtained that much. Therefore, in the dewatering roller of the present invention, the dehydrated filtrate flows through the drain groove 4, moves to both ends of the roller, collects at the stepped portion 6, and coalesces to form a water film.
The discharge of filtrate is accelerated as if by a siphon effect, improving drainage performance. Furthermore, since the filtrate can be easily drained out of the system, it not only makes it difficult for scale and SS to accumulate in the drain, but also
Since scale and the like are concentrated in the stepped portions, this has the effect of preventing scale from accumulating in the drain and making it easier to clean. When the step is not provided, or even if it is provided, its width A is less than 0.1% of the width B of the dewatering roller, and when the step depth C is greater than the groove depth D, the filter of each drain groove is Since the liquid is discharged from each drain independently, it does not collect or coalesce, and the filtrate cannot be easily drained due to the effect of interfacial tension, which worsens sludge dewatering performance and makes it easy for scale etc. to accumulate in the drain and cause blockage. Therefore, when the step depth C is smaller than the groove depth D, the flow of the dehydrated filtrate is inhibited, and the filtrate accumulates in the grooves, making it easy for scale and the like to accumulate. Furthermore, even when the step width A is larger than 3% of the dewatering roller width B, if the step depth C is not approximately the same as the groove depth D, the dewatered filtrate tends to flow in each drain groove independently. , aggregation and coalescence are less likely to occur, and the filtrate is insufficiently discharged, resulting in no improvement in dewatering performance, and the dewatering roller becomes too long, resulting in a lack of practicality and economic efficiency. It is desirable that the drain groove 4 is formed so that its total area occupies 20 to 80% of the entire circumferential surface of the roller. If this is less than 20%, the dehydrated filtrate will not be completely discharged and will be reabsorbed into the slurry.
%, the pressure receiving surface for sludge decreases, resulting in poor dewatering performance. Also, the ratio of the protrusion width W _t of the drain groove 4 to the groove width W _n
W _t /W _n (see Figure 2) is preferably 0.20 to 5;
A value of 0.3 to 3 is particularly advantageous; if it is too small, the pressure-receiving surface of the sludge will be reduced, and if it is too large, the pressure-receiving surface will be reduced. In other words, in either case, the compression dewatering effect will decrease, and the groove width W _n is 0.5.
A range of ˜50 mm, particularly 3-30 mm, has been found to be preferred. In addition to the example shown in Fig. 1, the drainage groove 4 may have a combination of horizontal and vertical grooves (Fig. 4), a combination of horizontal and slanted grooves (Fig. 5), and a combination of vertical and slanted grooves. It is preferable to use a composite groove (FIG. 6), a groove with only slanted grooves (FIGS. 7 and 8), or a combination of horizontal grooves, vertical grooves, and slanted grooves. Among these, as shown in the examples in FIG. 5 to _FIG . It is particularly preferable to form θ
It has been confirmed that the discharge performance of the dehydrated filtrate is significantly improved by setting the angle to 10 to 80°, particularly 30 to 60°. In addition, by forming the drainage grooves symmetrically with respect to the center line C _w in the roller width direction as described above,
When rotating the dewatering roller and running the filter cloth,
For example, for inclined grooves, as shown in Figure 7,
The roller axial component of the filter cloth tension acting perpendicularly to the drain groove acts to pull the filter cloth symmetrically with equal force, so the filter cloth is always held at the center position in the width direction of the roller. It has the effect of accurately preventing meandering of the filter cloth and wrinkles of the filter cloth. The dewatering roller may be made of a hard material such as metal, and a drainage groove may be formed on the surface of the roller, or steps formed by notches may be formed at both ends of the hard material. The surface may be coated with a water-impermeable elastic member such as rubber, and grooves may be formed therein.
The latter method is easier and more practical to create drainage ditches. Test Example 1 0.72% (based on solid content) of an organic polymer flocculant was added and mixed to sewage mixed raw sludge with a concentration of 2.8%, and a dewatering test was conducted using a belt press type dehydrator. In this case, the filter cloth speed is 1 m/min, the filter cloth tension is 5 kgf/cm ² , the filtration speed is constant at 133 kg/m・h, and the step width A of the dewatering roller and the roller width B (constant)
The content of the dehydrated cake was investigated by changing the ratio of 0 and the step depth C (the groove depth D was constant). The results are shown in Table 1.

[Table] From Table 1, it can be seen that a dehydrated cake with a low moisture content can be obtained using the dewatering roller of the present invention. Test Example 2 (Effect of step depth C) 0.67% organic polymer flocculant (based on solid content) was added and mixed to sewage mixed raw sludge with a concentration of 3.3%, and a dewatering test was conducted using a belt press type dehydrator. , the influence of step depth C was investigated. However, the filter cloth speed is 1m/
min, filter cloth tension pressure was 5 kgf/cm ² , step width A of the dewatering roller was 30 mm, and roller width B was 2000 mm.
The results are shown in Table 2.

【table】

[Table] From Table 2, even if the dewatering roller is provided with drainage grooves and steps, if C<D, the filtrate will accumulate in the grooves and impede the dehydration effect, and if C>D, It can be seen that the dehydration effect is inferior as well as when there is no step. In contrast, it can be seen that in the present invention (C=D), a dehydrated cake with a low water content can be obtained, and in this case, the filtration rate, that is, the amount of sludge throughput increases as the groove depth increases. Note that if the groove depth and step depth are about the same, a good dewatering effect can be observed even if the groove depth exceeds 50 mm, but it takes time and effort to form the grooves, which reduces its practical value. Test Example 3 (Effect of Step Width A) 0.67% (based on solid content) organic polymer flocculant was added and mixed to sewage mixed raw sludge with a concentration of 3.3%, and a dewatering test was conducted using a belt press type dehydrator. Step width A
We investigated the influence of However, the filter cloth speed is 1 m/min,
Filter cloth tension pressure is 5Kgf/cm ² , dewatering roller width B is 2000mm, groove depth D is 10mm, step depth C is 10mm.
And so. The results are shown in Table 3.

[Effect of idea]

As described above, the dewatering roller for a sludge dewatering device of the present invention has the effect of improving drainage of the dehydrated filtrate from the roller and preventing scale generation, increasing the amount of sludge throughput and reducing the water content of the dehydrated cake. There are practical benefits such as significantly easier operation and maintenance.

[Brief explanation of drawings]

Figures 1 to 3 show examples of the present invention; Figure 1 is a front view of the dewatering roller of the present invention;
The figure is a right side view of Fig. 1, and Fig. 3 is a schematic side view of a belt press type dehydrator to which the dewatering roller is applied.
4 to 8 are front views of different embodiments, and FIGS. 9 and 10 are front views of different conventional devices. 1, 1a, 1b... Filter cloth, 2, 3... Dewatering roller, 4... Drain groove, 5... Projection surface, 6... Step, 7... Roller shaft, A... Step width, B... Roller width, C... Step depth, Ca... Center line of roller shaft, C _w ... Center line in roller width direction, D... Groove depth, K... Dehydrated cake, S... Sludge, W _n ...
Groove width, W _t ... Protrusion width, θ... Inclination.

Claims (1)

[Scope of utility model registration request] In a sludge dewatering device in which an endless filter cloth belt is movably hung over a plurality of dewatering rollers in a polymerized state, and the sludge is compressed and dehydrated between these filter cloth belts, the dewatering roller is A plurality of drain grooves are formed on the circumferential surface of at least one roller, each communicating from one end of the roller in the width direction to the other end. A muddy material characterized in that the width A is within the range of 0.1 to 3% of the width B of the dewatering roller, and the depth C of the stepped portion is approximately the same as the groove depth D of the drain groove. Dehydration roller of dehydration equipment.