JPH063500U - Sludge dewatering device - Google Patents

Abstract

(57) [Summary] [Objective] The water content of the cake 62 obtained by compressing and dehydrating the sludge 16 can be maintained substantially constant regardless of the increase or decrease in the amount of water contained in the sludge 16. [Structure] The weight of the reaction tank 40 for mixing and coagulating the sludge 16 and the polymer coagulation liquids A and B is measured by using a load cell 74, and the coagulation liquid polymer tank pump P3 P4 and the rotation speed of the motor M of the screw dehydrator 22 are automatically controlled.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sludge dewatering device that dewaters sludge using a screw dewatering machine or a belt dewatering machine equipped with a filter cloth belt, and in particular, to a control operation corresponding to the water content of sludge.

[0002]

[Prior art]

 Conventionally, this type of sludge dewatering device has been proposed, for example, one that individually detects the squeezing pressure at the end of the screw shaft and the filtration flow rate leaching from the dewatering cylinder, and controls the rotation speed of the screw shaft according to both detected values. (See, for example, Japanese Patent Laid-Open No. 61-162298).

[0003]

[Problems to be solved by the device]

 However, in the above-mentioned device, not only is it difficult to accurately perform the detection operation itself, but also the control is performed using two detection values, so that the configuration of the control unit becomes complicated, etc. There are many problems.

The present inventor has made a study in view of such problems, and as a result, by adjusting the amount of the high-molecular flocculant according to the specific gravity of the sludge, the sludge can be favorably agglomerated and further adjusted to the specific gravity of the sludge. Measuring the specific gravity of sludge is an important factor in any control, such as the ability to discharge a cake with a constant water content by setting the rotation speed of the screw or the running speed of the filter cloth belt. It was found that the change in specific gravity of sludge itself can be easily and accurately measured by measuring the total weight.

The present invention has been made based on the above findings, and provides a sludge dewatering device capable of relatively accurate sludge flocculation control and cake water content control while maintaining a simple configuration. The purpose is to

[0006]

[Means for Solving the Problems]

 In the present invention, as schematically shown in FIG. 1, the basic constitution thereof includes a supply unit 14 for a polymer coagulant 18, a polymer coagulant 18 sent from the supply unit 14, and a dewatering sludge 16. A reaction tank 40 that is mixed and coagulated, and the coagulated sludge 48 is taken out while overflowing, and a screw dehydrator 22 that rotationally drives a screw to compress and dehydrate the coagulated sludge 48 sent from the reaction tank 40. A measuring unit 26 capable of outputting a signal corresponding to the total weight of the reaction tank 40 including the coagulated sludge 48 inside thereof, and a signal outputted from the measuring unit 26 corresponding to the signal outputted from the supplying unit 14. The control unit 28 is capable of controlling the supply speed of the polymer flocculant 18 and the screw rotation speed of the screw dehydrator 22.

When the belt dehydrator 23 is used instead of the screw dehydrator 22, the supply speed of the polymer coagulant 18 sent from the polymer coagulant supply unit 14 and the filter cloth belt 53 of the belt dehydrator 23. The traveling speed is controlled by the control unit 28.

[0008]

[Action]

 In the above-mentioned configuration, the polymer flocculant 18 is sent to the reaction tank 40 in addition to the sludge 16, the sludge 16 is condensed at a rate corresponding to the water content and the amount of the polymer flocculant 18, and then the reaction is performed. The cake 62 is sent from the tank 40 to the screw dehydrator 22 while overflowing and compressed and dehydrated to a predetermined water content.

Here, as a result of the reaction tank 40 overflowing when the sludge 16 supplied exceeds the set capacity, the volume stored in the reaction tank 40 is always constant. On the other hand, the weight of the entire reaction tank 40 including the internal coagulated sludge 48 is constantly measured by the measuring unit 26, and the change in the weight is proportional to the specific gravity of the coagulated sludge 48.

Therefore, the control unit 28 uses a signal corresponding to a value proportional to the specific gravity of the coagulated sludge 48 sent from the measurement unit 26, and supplies the polymer coagulant 18 per unit time and the screw 58. By controlling the rotation speed of No. 1 according to a preset procedure, the screw dehydrator 22 automatically discharges the cake 62 having a predetermined water content.

In the case of the belt dehydrator 23, the control unit 28 controls the supply amount of the polymer coagulant 18 per unit time and the traveling speed of the filter cloth belt 53 to be increased or decreased according to a predetermined procedure.

[0012]

[Effect of device]

 As described above, the specific weight of the coagulated sludge 48 is obtained by measuring the total weight of the reaction tank 40 including the internal coagulated sludge 48, and the specific weight of the polymer coagulant 18 per unit time is determined according to the measured specific gravity. Since the supply amount and the rotation speed of the screw 58 of the screw dehydrator 22 or the traveling speed of the filter cloth belt 53 are controlled, relatively accurate aggregation control and water content control can be performed while maintaining a simple configuration. .

[0013]

【Example】

 (First Embodiment) FIGS. 1 to 3 show a first embodiment of a sludge dewatering apparatus 10 according to the present invention. As shown in FIG. 2, a supply unit 12 for sludge 16 and a supply of polymer coagulant 18 are supplied. The unit 14, the reaction unit 20 of the sludge 16 and the polymer coagulant 18, the screw type dehydrator 22, the discharging unit 24 for sending the processed material to the outside in the screw dehydrator 22, and the various states of the apparatus are detected. The measuring unit 26 and the control unit 28 that performs a control operation corresponding to the detection result of the measuring unit 26 are provided.

The sludge supply unit 12 supplies the sludge 16 sucked up using the submersible pump P1 from above into a raw water tank 32 equipped with a stirrer 30, while using the supply pump P2 from below to supply the sludge to the reaction unit 20. Sludge 16 is supplied toward the upstream side.

The polymer coagulant supply unit 14 is provided with two polymer tanks 36 and 38 equipped with a stirrer 34, and the polymer coagulant is diluted with water in each of the polymer tanks 36 and 38. The liquids A and B are individually stored, and the two types of coagulation liquids A and B are individually sent to the reaction section 20 using the polymer tank pumps P3 and P4.

The reaction section 20 includes two sets of first and second reaction tanks 40 a and 40 b equipped with a stirrer 39 corresponding to the two types of coagulating liquids A and B, and both reaction tanks 40 a. 40b is integrally formed by joining one side wall 42 in common. Here, since the peripheral wall surface 44 of the first reaction tank 40a is slightly higher than that of the second reaction tank 40b, and the lower surfaces 46 of both reaction tanks 40a and 40b are located on the same plane, the first reaction tank 40a When the sludge 16 is fed from the sludge supply unit 12 to the 40a side, the sludge 16 mixed with one coagulation liquid A in the first reaction tank 40a overflows and then accumulates in the second reaction tank 40b, where the other coagulation liquid is collected. When mixed with B, it is condensed and also overflows the second reaction tank 40b and flows into the screw dehydrator 22.

The screw dehydrator 22 is formed so that the diameter of the draining zone 54 in the middle part thereof gradually decreases from the sludge supply zone 50 provided on the base end side toward the discharge outlet 52 on the tip end side. A screw 58 having spiral blades is rotatably provided in the dehydration cylinder 56. Further, a motor M is provided at the base end of the screw shaft 60, and its rotation speed can be changed by a signal from the control unit 28.

Accordingly, the coagulated sludge 48 sent from the second reaction tank 40b to the sludge supply zone 50 makes forward movement in conjunction with the rotation of the screw 58, and is compressed between it and the dehydration cylinder 56. It is gradually dehydrated through the draining zone 54 and discharged from the discharge port 52 as a cake 62 having a predetermined water content.

The discharge unit 24 is provided with a belt conveyor 64 below the discharge port 52 of the screw dehydrator 22, and moves the formed cake 62 to a predetermined position. On the other hand, a water conduit 66 is provided below the draining zone 54 to guide the dehydrated water into the drainage tank 68, and then most of it is discharged to the outside through the drainage pump P5, while part of it is discharged through the circulation pump P6. The sludge supply unit 12 is returned to the raw water tank 32.

The measurement unit 26 includes level meters 70 and 72 provided in the raw water tank 32 of the sludge supply unit 12 and one in the sludge supply zone 50 of the screw dehydrator 22, and the first and second reaction tanks 40a. It is composed of four load cells 74 provided so as to be interposed between the lower surface 46 of 40b and the installation surface 73.

The level meters 70 and 72 send a predetermined signal to the first or second control circuit 76 or 78 when the liquid level exceeds a preset upper limit value or falls below a preset lower limit value. The load cell 74 determines the specific gravity of the coagulated sludge 48 in the reaction tank 40 by making it possible to measure the total weight of sludge stored in the reaction tank 40 in a fixed volume. Therefore, a signal having a value corresponding to the detected load is sent to the third control circuit 80.

The first control circuit 76 described above controls on / off of the submersible pump P1 by a signal sent from the level meter 70 in the raw water tank 32 so that the water level in the raw water tank 32 falls within the lower limit value and the upper limit value. Make it fit. Further, the second control circuit 78 works in conjunction with the detection operation of the level meter 72 in the screw dehydrator 22 to turn on / off the polymer tank pumps P3 and P4 of the polymer condensate supply unit 14 and the supply pump P2 of the sludge supply unit 12. The amount of coagulated sludge 48 supplied to the screw dehydrator 22 is regulated so as to be substantially constant.

The present invention is characterized by the control operation in the third control circuit 80 using the load cell 74 described above, and supplies the aggregating liquids A and B in conjunction with the detection operation of the load cell 74. The rotation speed of the polymer tank pumps P3 and P4 and the rotation speed of the motor M of the screw dehydrator 22 are simultaneously controlled.

The third control circuit 80 uses the load data output from the four load cells 74 as shown in the block diagram of the schematic configuration of FIG. The total weight of the reaction tank 40 including is calculated. Further, the specific gravity determination unit 84 determines the specific gravity from the previously obtained data on the weight and volume of the reaction tank 40 itself, and inputs the specific gravity to the comparison unit 86.

The comparison unit 86 sets the upper limit value and the lower limit value of the specific gravity in advance as comparison data, and when the measured value exceeds the upper limit value or falls below the lower limit value, the pump driving unit 88 outputs a signal corresponding thereto. Then, the rotation speeds of the polymer tank pumps P3 and P4 and the motor M can be controlled by the both drive portions 88 and 90.

That is, when the specific gravity of the coagulated sludge 48 in the reaction tank 40 is below the lower limit value, it can be seen that the amount of water in the coagulated sludge 48 has increased above the standard value and the proportion of solids has decreased. , The rotation speed of the polymer tank pumps P3 and P4 is lowered below the predetermined value to reduce the supply amount of the coagulation liquids A and B to the coagulation sludge 48, while the rotation speed of the motor M is decreased below the predetermined value. The transfer speed of the coagulated sludge 48 in 22 is slowed down, and the dehydration amount from the coagulated sludge 48 is increased.

On the other hand, when the specific gravity of the coagulated sludge 48 exceeds the upper limit value, it can be seen that the amount of water in the coagulated sludge 48 has decreased below the standard value and the solid content ratio has increased. The rotation speeds of pumps P3 and P4 are increased above a predetermined value to increase the supply amount of the coagulation liquids A and B to the coagulation sludge 48, while the rotation speed of the motor M is increased above a predetermined value in the screw dehydrator 22. By increasing the transfer speed of the coagulated sludge 48 and decreasing the dehydration amount from the coagulated sludge 48, the water content of the cake 62 finally obtained can be improved regardless of the water content in the coagulated sludge 48. It is automatically kept almost constant.

Second Embodiment FIG. 4 schematically shows a belt dehydrator 23 which replaces the screw dehydrator 22. The belt dehydrator 23 includes a filter cloth belt 53 stretched between the rollers 51a and 51b and a press belt 57 stretched between the press rollers 55a and 55b so as to face the filter cloth belt 53. The filter cloth belt 53 allows only the moisture in the sludge to pass therethrough, and the moisture is guided to the water conduit 66 via the tray 59.

The roller 51a on the filter cloth belt 53 side is rotationally driven by the motor M, and the traveling speed of the filter cloth belt 53 can be changed by a signal from the control unit 28. The coagulated sludge 48 sent from the reaction tank 40 onto the filter cloth belt 53 is gradually dehydrated by being compressed between the belts 53 and 57 as the filter cloth belt 53 and the press belt 57 travel. The cake 62 having a predetermined water content is introduced to the belt conveyor 64 of the discharge section 24. The third control circuit 80 controls the polymer tank pumps P3 and P4 as described above, while controlling the rotation speed of the motor M to control the traveling speed of the filter cloth belt 53.

When the specific gravity of the coagulated sludge 48 in the reaction tank 40 falls below the lower limit value, the rotation speed of the motor M is reduced to slow the traveling speed of the filter cloth belt 53. As a result, the dehydration time of the coagulated sludge 48 on the filter cloth belt 53 is lengthened and the dehydration amount from the coagulated sludge 48 is increased. On the contrary, when the specific gravity of the coagulated sludge 48 exceeds the upper limit value, the rotation speed of the motor M is increased and the traveling speed of the filter cloth belt 53 is increased. Then, the dehydration time of the coagulated sludge 48 on the filter cloth belt 53 is shortened, and the dehydration amount from the coagulated sludge 48 is reduced.

It should be noted that the rotation speeds of the polymer tank pumps P3 and P4 and the motor M are not limited to being changed stepwise, but may be changed steplessly. Needless to say, the weight of the reaction tank 40 may be measured by various measuring means instead of the load cell 74. Further, the press belt 57 in the belt dehydrator 23 is omitted, and a suction device connected to a vacuum pump is arranged at a position corresponding to the tray 59 to suck water in the sludge from the back surface side of the filter cloth belt 53. May be. When the suction force is constant, the moisture suction time is changed by the increase / decrease control of the running speed of the filter cloth belt 53, so that the water content of the cake 62 can be adjusted.

[Brief description of drawings]

FIG. 1 is a conceptual diagram for explaining the present invention in principle.

FIG. 2 is a schematic diagram of an overall configuration showing a first embodiment of the present invention.

FIG. 3 is a block diagram showing an example of a third control unit.

FIG. 4 is a conceptual diagram illustrating another embodiment of the present invention.

[Explanation of symbols]

 12 Sludge Supply Section 14 Polymer Coagulant Supply Section 16 Sludge 18 Polymer Coagulant 20 Reaction Section 22 Screw Dewatering Machine 23 Belt Dewatering Machine 24 Discharging Section 26 Measuring Section 28 Control Section 40 Reaction Tank 48 Coagulation Sludge 58 Screw 60 Screw Shaft 62 cake

Claims (2)

[Scope of utility model registration request] 1. A supply unit 14 for a polymer coagulant 18, and a polymer coagulant 18 and sludge 16 sent from the supply unit 14.
And a flocculating sludge 48 that is taken out while overflowing, and a screw dehydrator 22 that rotationally drives a screw to compress and dewater the flocculated sludge 48 sent from the reaction tank 40. A measuring unit 26 capable of outputting a signal corresponding to a change in the total weight of the reaction tank 40 including the coagulated sludge 48 inside, and a signal output from the measuring unit 26 corresponding to the reaction unit from the supply unit 14 A sludge dewatering device including a control unit 28 capable of controlling the supply speed of the polymer flocculant 18 sent to 40 and the screw rotation speed of the screw dehydrator 22. 2. A supply unit 14 for supplying a polymer coagulant 18, and a polymer coagulant 18 and sludge 16 sent from the supply unit 14.
The reaction tank 40 from which the coagulated sludge 48 is taken out while overflowing and the filter cloth belt are driven to run, and the coagulated sludge 48 sent from the reaction tank 40 is dehydrated via the filter cloth belt. The belt dehydrator 23, the measuring unit 26 capable of outputting a signal corresponding to the change in the total weight of the reaction tank 40 including the coagulated sludge 48 therein, and the signal output from the measuring unit 26, A sludge dewatering device including a control unit 28 capable of controlling the supply speed of the polymer flocculant 18 sent from the supply unit 14 to the reaction tank 40 and the traveling speed of the filter cloth belt of the belt dehydrator 23.