JPS6116955Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sludge feeding device. More particularly, the present invention relates to a sludge delivery device with improved dewatering capabilities. Conventionally, a belt-Perez type dewatering device used for dewatering sludge dewaters incoming sludge by sandwiching it between two rotating endless cloths separated by a gap that gradually decreases from the upstream side to the downstream side. After the low-pressure dehydration section, there is a medium-pressure dehydration section that dewaters the sludge sandwiched between two rotating endless cloths using the tension of the cloth and the compression force of the pressure roll, and a shearing section with a smaller diameter than the pressure roll. A shear dewatering section and two rotating sheets are arranged in which rolls are arranged alternately and the sludge sandwiched between rotating endless cloths is passed through these shear rolls to dewater with stronger surface pressure and shear force. Two or three of the high-pressure dehydration sections that further wrap a pressure belt over the endless cloth and dehydrate it at a higher pressure.
It is composed of a combination of two. In conventional belt-Perez type dewatering equipment, the sludge sandwiched between cloths in the low-pressure dewatering section is transferred as is to the medium-pressure dewatering section. Since the pressure applied to the sludge in the medium-pressure dewatering section is much higher than that in the low-pressure dewatering section, increasing the sludge thickness at the entrance of the medium-pressure dewatering section will result in
On the other hand, some of the sludge returns to the low-pressure dewatering section through the cloth and escapes, which has the disadvantage of reducing the amount of sludge swallowed at the inlet of the low-pressure dewatering section. sludge supply thickness
It had to be less than 10mm. The sludge treatment equipment in the belt Perez type dehydrator has the following: Sludge treatment amount (Kg-DS/h)
= Dehydrated cake thickness (m) × Fabric width (m) × Cloth advancing speed (m/h) × Dehydrated cake solid content concentration (Kg-DS/m ³ ), but the thickness of the sludge supplied When the amount of water is limited, the thickness of the dewatered cake becomes thinner, and in order to increase the sludge processing capacity, it is necessary to increase the cloth width or
The speed of cloth movement must be increased,
If the speed of the cloth is increased, the time that the sludge remains in the pressurized area will be shorter, and the dewatering rate will be lowered, so it will be necessary to increase the length of the cloth to ensure the retention time, and in any case, the equipment will be larger. I had to change my mind. In addition, the thickness of the sludge supplied is thin, less than 5 mm in the shear dewatering section, and the shear force is small, so it is necessary to apply pressure dewatering by applying a large tension of ^about 1 to 10 kg/cm2 to the cloth. had shortened its lifespan. The present invention eliminates the above-mentioned drawbacks, and provides a sludge feeding device for a belt-Perez type dewatering device that increases the sludge processing capacity, achieves a high dewatering rate, and also extends the life of the cloth. This invention gradually decreases the distance between two rotary endless cloths toward the downstream in a wedge-like manner; the cloth narrows the sludge supplied to the upstream opening of the cloth, and drives a coaxial circumferential orbit. It is in contact with at least two rolls out of three or four rolls on the circumferential track; the roll movement speed is faster than the advancing speed of the cloth; It is a feeding device. The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a sectional view of a sludge feeding device according to the present invention. The interval between the two rotating endless cloths 1 and 2 gradually decreases in a wedge shape toward the downstream, and the sludge 6 is supplied from the upstream opening. If the low-pressure dehydration section and medium-pressure dehydration section are made of different fabrics, the opening is provided upstream of the feeding device, and if the low-pressure dehydration section and medium-pressure dehydration section are made of fabrics of the same system, the opening is provided between the opening and the feeding device. A low pressure dehydration section is provided between the two. The lower cloth 1 and the upper cloth 2 move together on the circumferential orbit of the roll 3 and are guided to the roll 5 of the medium pressure dehydration section. The four rolls 3 rotate in a circumferential orbit 4 about an axis 7, and swallow the sludge at a position 21.
The moving speed of the roll 3 moving on the circumferential track 4 is faster than the traveling speed of the cloth. Note that the roll movement speed is the speed at which the roll moves on the circumferential orbit, and is m/
Expressed in units of min. The sludge 11 is squeezed and dewatered as the roll 3 at position 21 moves. As the cloth progresses, the sludge is forcibly transferred while being dehydrated. Roll movement speed is 50% faster than cloth movement speed
When increasing, when the fabric at position 21 advances to position 23, the roll at position 21 moves to position 24. The roll at position 21 dewaters the sludge 11 and the roll at position 22 dewaters the sludge 12. The sludge that has passed through the position 23 is sent to the medium pressure dewatering section together with the cloth. The tension of the cloth is sufficient to absorb the slack that occurs after the upper and lower cloths are separated, and the tension of the upper and lower cloths should be set at 0.1 with springs, etc. on each of the guide rolls (not shown) for both the upper and lower cloths.
It is sufficient to apply a tension of about Kg/ ^cm2 . When the moving speed of the cloth and the moving speed of the rolls are approximately the same, roll 3 can prevent the sludge from returning to the low-pressure dewatering section, so the sludge can be swallowed thicker than with conventional equipment. However, the dewatering of sludge in the feeding device depends mostly on the tension of the cloth, so in order to increase the dewatering rate in this part, it is necessary to It becomes necessary to increase the tension. On the other hand, if the tension of the cloth is too strong,
This is not preferable because the life of the cloth will be shortened and the amount of sludge that can be caught between the rolls 3 to 3 will also be reduced. Therefore, in order to increase the amount of sludge treated and to perform dewatering to an average water content of 75%, it is necessary to provide a high-pressure dewatering section on the downstream side. In this invention, the sludge is transferred not only by the movement of the cloth, but also by the movement of the rolls, which gives the sludge extrusion effect and dewatering effect, so it is possible to obtain a high dewatering rate without applying strong tension to the cloth, and the wastewater treatment plant is Even in the case of sludge, the moisture content can be reduced without installing a high-pressure dewatering section.
It can dehydrate up to about 75%. In addition, if the moving speed of the cloth and the moving speed of the rolls are approximately the same, it is because the thickness of the sludge on the roll 5 of the medium pressure dewatering section is particularly thick (for example, the inlet 17
mm, exit 13mm) 15mm in turning radius of upper and lower cloth
There is a difference in degree, and the difference in length in contact with the roll 5 is about 5 cm. However, in this part,
Since the cloth is pressed against the roll 5, misalignment between the two cloths is less likely to occur. This causes the lower fabric to sag, and if the operation continues,
The folded lower cloth gets caught up in the roll 5, which shortens the life of the cloth. In contrast, in the feeding device of the present invention, the moving speed of the roll is faster than the moving speed of the cloth, which has the effect of forcibly causing a shift in the upper fabric, and the lower fabric between the feeding device and the medium pressure dewatering section. It can prevent sagging. The device of the present invention is applicable to various types of sludge such as sewage sludge, simulated sedimentation sludge, and pulp sludge. When the water content of sludge is 90% or more, it is suitable for sending sludge that has been dehydrated to a water content of about 80 to 87% by low-pressure dehydration. Although FIG. 1 shows the case where four rolls are used, three rolls can also be used. As the number of rolls increases, the speed ratio (roll movement speed/fabric advancement speed) can be reduced. A speed ratio of 2 to 3 is preferred when three rolls are used, and a speed ratio of 1.3 to 2 is preferred when four rolls are used. FIG. 2 is a system diagram of a belt press type dewatering device incorporating the sludge feeding device according to the present invention. The sludge fed into the supply hopper 32 via the mixing device 31 is dehydrated in the low pressure dewatering section, and the dewatered sludge is then sent to the medium pressure dewatering section by the sludge feeding device according to the present invention, where it is dehydrated and then further transferred to the shear dewatering section and Dehydrated sludge is obtained through a high-pressure dewatering section. The effects of the present invention can be summarized as follows. (1) The thickness of the sludge can be increased from the sludge intake part to the dewatered cake.
The amount of processing increases dramatically. (2) Since it is possible to obtain a higher dewatering rate than before in the sludge feeding device, the dewatering efficiency of the entire dewatering device is improved. (3) Since the tension of the fabric can be reduced to less than 1/10 of that of conventional fabrics, the lifespan of the fabric is dramatically extended. (4) Since the moving speed of the roll is faster than the advancing speed of the cloth, it has the effect of forcing the upper cloth to shift, and even though the treated sludge is thick, the cloth does not become sagging in the medium pressure dewatering section. It can be prevented. (5) The thickness of sludge supplied to the shear dewatering section is reduced to 0 by the forced sludge feeding action by the movement of the rolls.
The dewatering efficiency in the shear dewatering section is increased by approximately 15 mm, which is more than double that of the conventional method. Example Excess sludge from a sewage treatment plant with a moisture content of 95% was subjected to low-pressure dehydration treatment, and then the sludge was supplied to a medium-pressure dewatering section using the sludge feeding device of the present invention. The sludge discharged from the medium pressure dewatering section was further dehydrated in the shear dewatering section and the high pressure dewatering section. The feeding device was operated at a cloth traveling speed of 0.6 m/min and a roll traveling speed of 0.9 m/min. The thickness of the sludge was 20 mm at the inlet of the feeding device, 13 mm at the outlet of the medium pressure dewatering section, 10 mm at the outlet of the shear dewatering section, and 10 mm at the outlet of the high pressure dewatering section. On the other hand, the moving speed of the roll is set to the same speed as the cloth.
When the speed was set to 0.6 m/min, approximately 5 cm of cloth sagged in the medium-pressure dewatering section, and as the operation continued, the cloth became folded and caught in the rolls of the medium-pressure dewatering section. The results are shown in the table below. 【table】

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the sludge feeding device of the present invention. FIG. 2 is a system diagram of a belt-Perez type dewatering device incorporating the sludge feeding device according to the present invention. 1, 2... Cloth, 3... Roll, 4... Circumferential orbit drawn by the roll.

Claims (1)

[Claims for Utility Model Registration] 1. The exchange between the two rotating endless cloths is gradually reduced toward the downstream in a wedge shape; the cloth holding the sludge supplied to the upstream opening of the cloth is coaxial It is in contact with at least two of the three or four rolls that drive a circular orbit; the moving speed of the rolls is faster than the advancing speed of the cloth; the sludge is dewatered under medium pressure. Sludge feeding device for sending sludge to the department. 2. The device according to claim 1, wherein the moving speed of the roll is 1.3 times or more the advancing speed of the cloth.