JP2016068022A - Dewatering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dewatering device capable of maintaining the water content of dewatered cake after dewatering at a substantially constant value without fluctuating the water content, and capable of obtaining a high dewatering ratio.SOLUTION: A dewatering device 18 comprises a screw body 28 and a dewatering drum 23. One end side of the dewatering drum 23 is provided with a supply port 210. The other end side of the dewatering drum 23 is provided with a push plate 30 whose opening can be controlled by a control device 20 and provided with a pressure detector 40 detecting the pressing force of the push plate 30. The balance between the pressure of discharging an object to be treated by a screw blade 29 and the pressing force of the push plate 30 is controlled to produce and discharge dewatered cake whose dewatering ratio is adjusted to a predetermined value. The control device 20 controls the opening of the push plate 30 so that the pressing force of the push plate 30 is maintained at a set value preset to adjust the dewatering ratio of the dewatered cake to a predetermined value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a dehydrating apparatus that dehydrates moisture from an object to be treated, and more particularly to a dehydrating apparatus that performs dehydration using a screw press.

  Industrial wastewater, household wastewater, etc. generally contain 85% or more of water and solids, so that the water content is at least 80% or less to be reused as dehydrated cake or disposed of as industrial waste. Need to be dehydrated. Moreover, when incinerated as industrial waste, it is necessary to reduce the water content to 70% or less.

  Conventionally, dehydration of industrial wastewater, household wastewater, etc., is generally performed by putting the wastewater into a settling tank and precipitating solids in advance, and then dehydrating the precipitate by a screw press or belt press. It was. However, although these methods have the feature that the system configuration and maintenance are simplified, there is a problem that the treatment time becomes long and a large amount of waste water cannot be treated in a short time. Therefore, a flocculant is added to the sedimentation tank to cause agglomeration, and further, a dehydration aid (also referred to as a dehydration aid) made from waste paper is added to the floc obtained by agglomeration to perform dehydration. ing. Although it has become possible to dramatically increase the dehydration efficiency by such a method, it has been necessary to use a large amount of dehydration aid in order to increase the dehydration rate.

  As a dehydrating aid for lowering the dehydration rate of the dehydrated cake, in other words, the moisture content, high activity comprising fine pulp fibers having a diameter of 10 to 30 μm and a length of 500 to 1000 μm imparted with mechanochemical activity by mechanical shearing The thing by a cellulose fiber is known (for example, refer patent document 1). The applicant developed a dehydration system and applied for a patent (Patent Document 2).

JP 2005-248337 A JP 2011-156494 A

  However, the conventional dehydration apparatus performs dehydration by pressurizing an object to be treated such as sediment in wastewater treatment, but it is not always easy to adjust the pressure on the object to be dehydrated for continuous dehydration. It was.

  Accordingly, the object of the present invention is to maintain a constant pressure applied to the precipitate obtained by treating the object to be treated, for example, wastewater, thereby maintaining a constant dehydration without changing the water content of the object to be treated. An object of the present invention is to provide a dehydrating apparatus capable of obtaining a rate.

  In order to achieve the above object, the present invention as set forth in claim 1 is provided on the outer side of a screw body in which spiral screw blades are arranged on the outer peripheral surface, and is provided coaxially with the screw body and provided with a large number of fine holes. The dehydrating drum is provided with a supply port for supplying an object to be processed between the screw body and the dewatering drum on one end side of the dewatering drum, and the other end of the dewatering drum formed open. On the side, a push plate whose opening degree can be controlled by a control device is provided, and a pressure detector for detecting the pushing force of the push plate is provided, and the screw blade is moved by the rotation of the screw body. Dehydration adjusted to a predetermined dehydration rate by dehydrating water from the object to be processed by adjusting the balance between the pressure to feed the object to the pressing plate and the pressing force of the pressing plate In the dehydrating apparatus that discharges the dehydrated cake to the outside by forming a gap between the open end of the dewatering drum and the push plate while generating a cake, the control device includes the pusher The pressing force of the plate is controlled such that the opening degree of the push plate is maintained so as to maintain a preset value so that the dewatering rate of the dewatered cake becomes a predetermined dewatering rate.

  In order to achieve the above object, according to a second aspect of the present invention, in the dehydrating apparatus according to the first aspect, when the pressing force of the pressing plate is higher than the set value, the control device is configured to control the pressing plate. The opening is widened, and when the pressing force is lower than a set value, the pressing force of the pressing plate is controlled by narrowing the opening of the pressing plate.

  According to the dehydrating apparatus of the present invention, there is an effect that dehydration can be continuously performed while the moisture content of the processed object after dehydration is kept substantially constant.

It is a block diagram of a dehydration system provided with one embodiment of a dehydration device concerning the present invention. It is a front partial sectional view showing a schematic structure of a dehydrating device. It is a detailed sectional view showing other composition of a push board. It is a flowchart which shows operation | movement of the dehydration apparatus which concerns on this invention.

[Configuration of dehydration system]
A dehydrating apparatus according to the present invention will be described in detail below with reference to the drawings based on a dehydrating system including the dehydrating apparatus. FIG. 1 is a block diagram of a dehydrating system including an embodiment of a dehydrating apparatus according to the present invention. The illustrated dehydration system 1 generally includes a wastewater tank 10 for storing solid waste-containing wastewater, a dehydration auxiliary agent storage tank 14 for storing a dehydration auxiliary agent, and a dehydration aid stored in the dehydration auxiliary agent storage tank 14. The dehydrating auxiliary agent dissolving device 15 for dissolving the agent and the dehydrating auxiliary agent sent from the dehydrating auxiliary agent dissolving device 15 are added to and mixed with the waste water sent from the waste water tank 10 and a pH adjuster is added to adjust the pH. First and second mixing and agglomeration tanks 11 and 12 for adjustment, a flocculant supply device 13 for further supplying a flocculant to the first and second mixing and agglomeration tanks 11 and 12, and a precipitate flocked by the aggregating agent A first dehydrator 18 for dehydrating a precipitate concentrated by the first concentrator 16, and a second concentrator. The sludge concentrated by 17 is dehydrated. 2 of dewatering device 19 is disposed. Further, the first and second dehydrating devices 18 and 19 are configured to control the pressing force applied to the pressing plate 30 of the control device 20 that controls the operation of the pressing plate 30 described later and the first and second dehydrating devices 18 and 19. A length measuring sensor for detecting an opening (opening 43 in FIG. 3) which is the distance of the pressure plate 40 to be detected and the push plate 30 with respect to the rear ends of the screw bodies 28 of the first and second dehydrators 18 and 19. And a display device 42 that is connected to the control device 20 and displays various information such as setting contents, control contents, and operation states.

  The wastewater tank 10 is a tank that stores wastewater containing solids such as industrial wastewater and household wastewater. The stored wastewater contains, for example, 0.6 to 1.0% solids such as sludge. Yes. In the dehydrating auxiliary agent storage tank 14, for example, powdered cellulose such as 50 mesh cedar powder, waste paper, sugarcane straw, bamboo powder and the like is stored as a dehydrating auxiliary agent. The dehydrating auxiliary agent dissolving device 15 is provided with stirring means such as a screw, and is a device for stirring and dispersing or dissolving the dehydrating auxiliary agent sequentially cut out from the dehydrating auxiliary agent storage tank 14 in water. In the first and second mixing and agglomeration tanks 11 and 12, the dehydration aid sent from the dehydration aid dissolving apparatus 15 is added to the wastewater sent from the wastewater tank 10. The dehydrating aid is added in an amount of 10 to 20% by weight based on the solid content of the waste water. Further, in the first and second mixing and aggregating tanks 11 and 12, the pH of the wastewater is adjusted to pH 6.0 to 7.0 by adding a pH adjuster such as a ferric sulfate solution to the wastewater. Adjust to 5-4.0. Then, a floc is formed by adding a polymer flocculant such as a polymer to the pH-adjusted waste water sent from the flocculant supply device 13, and a precipitate (hereinafter referred to as "sludge") is generated. Is done. The sludge is concentrated by the first and second concentrators 16 and 17 and supplied to the supply ports 210 of the first and second dehydrators 18 and 19 shown in FIG.

[Configuration of dehydrator]
FIG. 2 is a partial front sectional view showing a schematic configuration of the first dehydrating apparatus 18. That is, a part of the drawing is shown in a sectional view. The first dehydrating device 18 and the second dehydrating device 19 have the same configuration, and here, description will be made based on the first dehydrating device 18.

  The illustrated first dehydrating apparatus 18 is roughly configured by, for example, a casing 21 having a bowl-shaped outer shape, a plurality of stands 22 in the casing 21 and sludge (including a dehydrating auxiliary agent). A dehydrating drum 23 having a supply port 210 to be supplied, a screw shaft 24 installed horizontally at the center of the dewatering drum 23, and a bearing 25 that is disposed on both ends in the longitudinal direction of the screw shaft 24 and supports the screw shaft 24. , 26, a stand 27 that holds the bearing 25, a screw body 28 that includes a screw blade 29 that is formed in a spiral shape on the outer peripheral surface, and that rotates as the screw shaft 24 rotates, and a rear end (dehydration) An annular push plate 30 attached to the rear end of the screw body 28 so as to be interposed between the cake outlet end) and the rear end of the dewatering drum 23; A lid member 31 that functions as a lid and bearing at the rear end side of the casing 21, a hydraulic cylinder 32 that is provided on the lid member 31 so that the distal end side of the shaft 321 can press the push plate 30, and an end of the screw shaft 24 Are provided on a sprocket 33 provided on the portion (left end), a hydraulic pump unit 34 that drives the hydraulic cylinder 32, a screw shaft drive 35 that rotates the screw shaft 24, and a rotation shaft 350 of the screw shaft drive 35. The sprocket 36, the two chains 37 spanned between the sprocket 33 and the sprocket 36, the pressure detector 40 made of a load cell, for example, and the opening degree detector 41 made of a length sensor are provided. Yes. There are various length measuring sensors. For example, when the parallel light projected from the projector is detected by the light receiver, the size of the light shielding object is detected from the change in the amount of received light.

  The casing 21 is provided with a drain pan 211 having a substantially V-shaped cross section formed at the bottom and collecting the water (liquid) dehydrated from the sludge and discharging it from the drain 212 on the bottom surface, and a spiral screw. A discharge space 38 is provided for discharging the dewatered cake in a state where moisture is dehydrated from the sludge conveyed to the rear end side of the screw body 28 by the rotation of the blades 29. The dehydrated cake discharged from the discharge space 38 to the outside of the casing 21 is transferred by a belt conveyor (not shown).

  The dewatering drum 23 has a substantially cylindrical shape, and a large number of annular partition members 231 are provided at predetermined intervals on the peripheral surface thereof, and the outer periphery of the screw main body 28 disposed so as to penetrate the inside thereof. Sludge supplied from the supply port 210 is accommodated between the surface and the inner peripheral surface of the dewatering drum 23. In addition, a large number of fine holes (not shown) are provided on the peripheral surface of the dewatering drum 23 for discharging moisture dehydrated from the sludge to the outside. Thus, the sludge is transported toward the terminal end side of the screw body 28 by the rotation of the screw blades 29 and is compressed by the sludge transported one after another, and the water squeezed out from the sludge by the pressure is dehydrated in the dewatering drum 23. It is discharged out of the dewatering drum 23 through a fine hole (not shown) formed in the peripheral surface. The screw body 28 is formed such that the diameter on the supply port 210 side is small and the diameter gradually increases toward the push plate 30 side, and the clearance between the screw body 28 and the dewatering drum 23 is relatively It is narrower.

  The screw shaft drive 35 transmits the rotation of the motor as a power source to the sprocket 36, and transmits the rotational force to the sprocket 33 having a larger diameter via the chain 37, whereby the screw shaft 24 is decelerated. Rotate.

  The push plate 30 is a substantially annular metal plate arranged so that the opening at the rear end of the dewatering drum 23 can be sealed. The push plate 30 is arranged on the terminal side (exit end of the dewatered cake) of the screw body 28 and is substantially annular. The inner opening surface of the screw body is slidable in the axial direction along the outer peripheral surface of the screw main body 28. The push plate 30 is externally fitted to the rear end of the screw body 28 in a state where the push plate 30 is connected to the front end surface of the shaft 321 of the hydraulic cylinder 32. A gap between the push plate 30 and the dewatering drum 23 becomes an outlet of the dewatered cake. Then, the pressing plate 30 is moved in the left-right direction along the screw shaft 24 to appropriately adjust the opening degree of the pressing plate 30 and the dewatering drum 23, thereby keeping the pressing force of the pressing plate 30 constant and dewatering sludge. It becomes possible to adjust the water content of the dehydrated cake after the aging.

  In the above configuration, the push plate 30 is slidable on the outer peripheral surface of the screw main body 28 in a liquid-tight state. However, the push plate 30 is fixed to the outer peripheral surface of the screw main body 28 and the screw main body 28 is pivoted. The degree of opening of the gap between the push plate 30 and the dewatering drum 23 can also be adjusted by configuring it so as to be movable in the direction.

  On the other hand, the push plate 30 shown in FIG. 3 is attached so that the screw shaft 24 is inserted through the inner opening surface formed in a substantially annular shape, and its cross-sectional shape becomes narrower toward the dewatering drum 23 side. The shape is a truncated cone shape, and is formed so that the opening of the dewatering drum 23 can be closed. The hydraulic cylinder 32 is driven by a hydraulic pump 46 included in the hydraulic pump unit 34, and a pressure gauge 47 is attached to the hydraulic pump 46. Although the push plate 30 shown in FIG. 2 and the push plate 30 shown in FIG. 3 are attached at different positions, their operations and functions are the same.

  The control device 20 controls the opening degree of the push plate 30 by adjusting the hydraulic pressure sent from the hydraulic pump unit 34 to the hydraulic cylinder 32. In other words, the hydraulic cylinder 32 is provided with the pressure detector 40 made of, for example, a load cell, and the opening degree detector 41 made up of a length measuring sensor for detecting a gap between the push plate 30 and the dewatering drum 23. The pressure detector 40 and the opening degree detector 41 are connected to the control device 20. Here, if the moisture content of the dewatered cake from which the sludge has been dehydrated becomes lower, the dehydrated cake becomes harder. If it is necessary, the internal pressure needs to be lowered. On the other hand, when the moisture content of the dehydrated cake is high, the dehydration rate is low and the internal pressure is low, so it is necessary to increase the internal pressure. Therefore, the control device 20 always monitors the internal pressure in the dewatering drum 23, that is, the pressing force of the push plate 30, by the pressure detector 40, and when the internal pressure in the dewatering drum 23 becomes higher than a predetermined set value. Increases the opening between the push plate 30 and the dewatering drum 23 to lower the push force by the hydraulic cylinder 32, and when the internal pressure in the dewatering drum 23 becomes lower than a predetermined set value, the push plate 30 And the dehydrating drum 23 is controlled to increase the pressing force by the hydraulic cylinder 32 by narrowing the opening. The opening degree is monitored by an opening degree detector 41.

[Operation of dehydrator]
Next, the operation of the above-described dehydrator will be described. First, in the dehydration system 1 including the first and second dehydrators 18 and 19, the dehydration auxiliary agent stored in the dehydration auxiliary agent storage tank 14 is dispersed or dissolved in water in the dehydration auxiliary agent dissolution apparatus 15. . The flocculant supply device 13 contains a polymer flocculant. Then, waste water containing about 0.6 to 1.0% of solid content is supplied from the waste water tank 10 to the first and second mixing and aggregation tanks 11 and 12, respectively, and the dehydrating auxiliary agent dissolving device 15 is used as a dehydrating auxiliary agent. Is added in an amount of 10 to 20% by weight based on the solid content of the wastewater. Further, a pH adjuster such as sodium hydroxide solution or polyferric chloride sulfate solution is added to the waste water. As a result, the pH 6.0 to 7.0 of the wastewater sent from the wastewater tank 10 in the first and second mixing and aggregation tanks 11 and 12 is adjusted to pH 3.5 to 4.0. Further, flocs are generated by adding a flocculant (polymer flocculant such as polymer) from the flocculant supply device 13.

  Next, the wastewater in which the floc is generated is sent to the first and second concentrators 16 and 17 and concentrated to generate sludge. And this sludge is supplied to the inside from the supply port 210 of the 1st, 2nd dehydrator 18,19. Hereinafter, the operation of the first dehydrator 18 will be described.

  In the first dehydrating apparatus 18 shown in FIG. 2, the screw body 28 is rotated by transmitting the rotation to the screw shaft 24 by driving the screw shaft driving machine 35. The sludge supplied to the supply port 210 is pushed into the spiral groove 291 formed by the screw blade 29 as the screw body 28 rotates (see FIG. 2). Then, the sludge is conveyed in the spiral groove 291 toward the rear end side (left end side in FIG. 2) of the screw main body 28 by the rotation of the screw 28, and is compressed by the screw blade 29 in the process. At this time, since the push plate 30 is pressed to the right side in FIG. 2 by the hydraulic cylinder 32 with a predetermined pressure, the sludge is dehydrated by the compression by the rotation of the screw blades 29. The liquid dehydrated from the sludge is discharged to the outside of the dewatering drum 23 through a number of micro holes provided in the dewatering drum 23, and further falls to the drainage pan 211 through the partition member 231, so that the drainage pan 211 Collected in the lower drain 212 and discharged from the drain 212 to a waste water tank or the like (not shown).

  In this way, the sludge enters the spiral groove 291 of the screw body 28 and is gradually packed into the spiral groove 291, whereby the moisture in the sludge is pushed out toward the dehydration drum 23 by the pressing force, and the dewatering is gradually performed. As it progresses and reaches the left end of the screw body 28, the sludge becomes a dewatered cake, and the dewatering rate is 70% or less.

[Control of dehydrator]
Next, the control of the dehydrator and the operation accompanying it will be described. FIG. 4 is a flowchart showing the control of the dehydrating apparatus. First, the pressure value (initial value) of the push plate 30 is set (S1). As an initial value, for example, the pressure value is set so that the dewatering rate of the dewatered cake is about 70%. Then, the hydraulic pump unit 34 is operated, and the dehydrator 18 is activated.

When the dewatered cake that has reached a predetermined dewatering rate is discharged from the dewatering device 18, the pressing force at that time is detected by the pressure detector 40, and the pressing force is taken into the control device 20 as a set value (S2). The dehydration rate can be calculated by the following formula.

Dehydration rate = [(mass before dehydration−mass after dehydration) / mass before dehydration] × 100

  Then, the control device 20 determines whether or not the pressing force of the pressing plate 30 by the pressure detector 40 has reached a value taken as a set value (S3). When it is a set value (S3: Yes), the push plate 30 has a preferable opening, and the dewatered cake is continuously discharged into the discharge space 38 through the gap formed by the push plate 30 (S4). Further, the dehydrated cake is conveyed to a predetermined place by a belt conveyor (not shown).

  If the pressure applied to the pressing plate 30 becomes higher than the set value due to the screwing pressure of the sludge packed in the spiral groove 291 in the process of generating the dewatered cake, the dewatering rate is also increased (S5: “high”). The opening value 43 of the plate 30 is widened to maintain the set value of the pressing force of the push plate 30 (S6). On the other hand, when the pressure applied to the push plate 30 becomes lower than the set value, the dewatering rate is also lowered (S5: “Low”), so the opening 43 of the push plate 30 is narrowed to reduce the push force of the push plate 30. The set value is maintained (S7). Then, it is determined whether or not the pressing force by the pressure detector 40 has been restored to the set value with respect to the processes in S5 and S6 (S8). If the pressing force is a set value (S8: Yes), the operation is maintained as it is (S9). On the other hand, if it is not the set value (S8: No), the process proceeds to S5, and the subsequent processes are re-executed. When the generation process (dehydration) of the dehydrated cake is completed (S10: Yes), all the processes are completed. If the process is continued (S10: No), the process is returned to S5 and the subsequent processes are re-executed.

  Note that the opening degree 43 can be arbitrarily set, and the opening degree 43 or the pressing force can be changed depending on the moisture content of the dehydrated cake during operation being equal to or lower than the predetermined moisture content. Furthermore, when the current value of the screw driver 35 reaches the rated value, the opening degree 43 is opened to the maximum value to take measures against overload operation, and again when the current value becomes less than the rated value and becomes stable. Restore the initial settings.

[Effect in the embodiment]
According to the above embodiment, the dehydration rate can be adjusted by controlling the opening of the push plate 30 so that the pressing force of the dehydrating device becomes a desired value, so that the moisture content of the dewatered cake is kept constant. In addition to being able to obtain a high dehydration rate.

The present invention can also be applied to the case where the solid content is made into a cake by dehydrating a liquid composed of a large amount of water and solid content instead of the wastewater containing sludge.
[Other embodiments]

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from or changing the technical idea of the present invention. For example, although it was set as the structure of 2 systems which consist of a mixing and aggregating tank, a concentrator, and a dehydrator, 1 system may be sufficient and 3 systems or more may be sufficient.

  In addition, the first and second dehydrators 18 and 19 have a horizontal configuration, but may have a vertical configuration. And the number of dehydrators may be one or more than three.

DESCRIPTION OF SYMBOLS 1 Dehydration system 10 Waste water tank 11 1st mixing and coagulating tank 12 2nd mixing and coagulating tank 13 Coagulant supply apparatus 14 Dehydration auxiliary agent storage tank 15 Dehydration auxiliary agent dissolution apparatus 16 1st concentrator 17 2nd concentrator 18 First dehydrating device 19 Second dehydrating device 20 Control device 21 Casing 22 Stand 23 Dehydrating drum 24 Screw shaft 25, 26 Bearing 27 Stand 28 Screw body 29 Screw blade 30 Push plate 31 Lid member 32 Hydraulic cylinder 33 Sprocket 34 Hydraulic pump Unit 35 Screw shaft drive 36 Sprocket 37 Chain 38 Discharge space 39 Clearance 40 Pressure detector 41 Opening detector 42 Display device 46 Hydraulic pump 47 Pressure gauge 210 Supply port 211 Drain pan 212 Drain 231 Partition member 291 Spiral groove 321 Shaft 350 axis of rotation

Claims (2)

A dewatering drum provided coaxially with the screw main body and provided with a large number of fine holes is provided on the outer side of the screw main body in which spiral screw blades are disposed on the outer peripheral surface. A supply port for supplying an object between the screw main body and the dewatering drum is provided, and the other end of the dewatering drum formed open is capable of controlling the opening degree by a control device. And a pressure detector for detecting the pressing force of the pressing plate, and a pressure at which the screw blade sends the workpiece to the pressing plate side by rotation of the screw body, and a pressing force of the pressing plate, The dehydrating drum is opened while the dewatering cake is adjusted to a predetermined dewatering rate by dehydrating water from the workpiece by adjusting the balance of the dewatering drum. In the dehydration device for discharging the dehydrated cake to the outside by forming a gap between the the side press plate,
The control device controls the opening of the push plate so that the pressing force of the push plate is maintained at a preset value so that the dewatering rate of the dewatered cake becomes a predetermined dewatering rate. Dehydration device. The dehydrator according to claim 1,
The controller increases the opening of the push plate when the pressing force of the push plate is higher than the set value, and narrows the opening of the push plate when the pressing force is lower than the set value. A dehydrating apparatus for controlling a pressing force of the pressing plate.

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