JP2012030158A - Concentrated sludge dehydration system and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably concentrate and dehydrate concentrated sludge of a constant flow rate.SOLUTION: This concentrated sludge dehydration system includes: a concentrator 101 that filters sludge and generates concentrated sludge; a liquid level measurement instrument 102 that temporarily stores concentrated sludge discharged from the concentrator and measures the liquid level of the stored concentrated sludge; a concentrated sludge feed pump 103 that discharges concentrated sludge temporarily stored by the liquid level measurement instrument 102; a pressure gage 104 that measures press-fit pressure of concentrated sludge discharged from the concentrated sludge feed pump 103; a dehydrator 105 that dehydrates concentrated sludge discharged and press-fitted from the concentrated sludge feed pump 103; and a controller 106 that controls the discharge amount from the concentrated sludge feed pump 103 based on the press-fit pressure measured by the pressure gage 104 and controls the rotational frequency of a dehydration screw shaft provided in the dehydrator 105 based on a liquid level measured by the liquid level measurement instrument 102.

Description

  The present invention relates to a sludge concentration and dehydration system that continuously concentrates and dehydrates a sludge stock solution having a constant flow rate, and a control method thereof.

  Conventionally, a technique for concentrating and dewatering organic sludge such as sewage, human waste, or food production processing wastewater by the following method is known. First, a polymer flocculant is added to organic sludge, and it stirs and mixes in a coagulation tank, and produces | generates an aggregation floc. The aggregated floc is concentrated by a concentrating device, and then filtered and dehydrated by a dehydrating device.

  Coagulation floc purified in the coagulation tank has a low concentration of organic sludge, so if it is concentrated and dehydrated directly with a dehydrator, the water load on the sludge injection side of the dewaterer becomes greater than the solid load. A large amount of water is discharged from the outer cylinder screen. Therefore, in order to reduce the water load in the dehydrator, the aggregated floc is concentrated by the concentrator and then filtered and dehydrated by the dehydrator. For example, the concentration device concentrates sludge having a concentration of 1% to 4 to 5%, and the concentrated sludge is filtered and dewatered by a dewatering device.

  Here, as a concentrating device, there has been proposed a rotary concentrator for concentrating while rotating a screw shaft provided in an outer cylinder screen and regenerating a filter surface that is likely to be clogged (see, for example, Patent Document 1).

  In addition, a dehydrating apparatus that includes a cylindrical screen and a screw shaft that is rotatable inside thereof and that separates solid and liquid while conveying concentrated sludge by driving rotation of the screw shaft is conventionally known. A concentrated sludge supply pump for supplying sludge and the like to the dewatering device and a pressure detector for detecting the pressure of the concentrated sludge supplied to the dewatering device are provided so that the pressurizing pressure detected by the pressure detector becomes substantially constant. In addition, a method of controlling the supply flow rate of the concentrated sludge supply pump has also been proposed (see, for example, Patent Document 2). Furthermore, a method for controlling the number of rotations of the screw shaft of the dehydrating apparatus has been proposed so that the press-fitting pressure detected by the pressure detector is substantially constant (see, for example, Patent Document 3).

JP 2003-181216 A JP 2008-55450 A Japanese Patent No. 3542970

  Usually, when dewatering concentrated sludge, the sludge concentrated by the concentrating device is once put in a storage tank, and then used as a stock solution to re-aggregate and dehydrate. In this case, the sludge is retained in the concentrated sludge storage tank for a long time due to the processing procedure and time constraints, and as a result, the decay of the concentrated sludge proceeds. Therefore, not only does the dewatering efficiency of the concentrated sludge not increase, but conversely, a phenomenon such as a decrease in dewaterability may occur. Therefore, when dewatering concentrated sludge, it is desirable to dehydrate immediately after concentration. Further, in order to dehydrate after concentration, not only the above-described concentration device and dewatering device, but also a concentrated sludge storage tank is required, and a large installation area is required.

  The conventional dehydrator can prevent overload and obtain a cake with a uniform moisture content by controlling the rotational speed of the screw shaft for sludge with good filterability. For sludge, if the volume of the filtration chamber is reduced and compressed and dehydrated, the filtration surface of the outer cylinder screen is clogged at an early stage. Or if it squeezes rapidly, sludge will be discharged | emitted from an outer cylinder screen with a filtrate, and there exists a possibility that a filtrate may be suspended. In the conventional operation control method of the dehydrator, the supply flow rate of the stock solution supply pump is controlled to control the supply flow rate of the stock solution supplied to the dehydrator in order to keep the press-fitting pressure of the stock solution supplied to the dehydrator constant. To do. However, in actuality, the amount of solids to be treated varies depending on the concentration of the stock solution and the dehydration. For example, when the stock solution concentration is low, the solid processing amount decreases, and when the stock solution concentration is high, the solid processing amount increases. For this reason, there has been a problem that the amount of solid matter processing varies.

  In view of the above problems, an object of the present invention is to provide a sludge concentration and dewatering system for stably concentrating and dewatering a concentrated sludge having a constant flow rate and a control method therefor.

  The first feature of the present invention is that the sludge is filtered to generate concentrated sludge, and the concentrated sludge discharged from the concentrator is temporarily stored, and the liquid level of the stored concentrated sludge is measured. A liquid level measuring device, a concentrated sludge supply pump that discharges the concentrated sludge temporarily stored by the liquid level measuring device, a pressure gauge that measures the pressurization pressure of the concentrated sludge discharged from the concentrated sludge supply pump, and the concentrated sludge Concentrated sludge discharged from the supply pump is press-fitted, and the amount discharged from the concentrated sludge supply pump is controlled and the liquid level is measured based on the dehydration device that dehydrates the concentrated sludge and the press-fitting pressure measured by the pressure gauge. The gist of the present invention is a sludge concentration and dewatering system including a control device that controls the number of rotations of a dewatering screw shaft included in the dewatering device based on the liquid level measured by the device.

  According to the first feature of the present invention, in order to control the discharge amount from the concentrated sludge supply pump based on the pressure of the concentrated sludge that is pressed into the dewatering device, the filtration dewatering pressure in the dewatering device is controlled to be constant. This makes it possible to perform a stable dehydration operation. Moreover, since the rotation speed of the dehydrating screw shaft included in the dehydrating device is controlled based on the liquid level measured by the liquid level measuring device, it is possible to suppress idle operation of the dehydrating device and overflow from the liquid level measuring device. Therefore, the processing flow rate of concentrated sludge can be stabilized.

  In the first feature of the present invention, the amount of discharge from the concentrated sludge supply pump is controlled based on the pressurization pressure of the concentrated sludge that is press-fitted into the dewatering device while keeping the rotation speed of the concentrating screw shaft included in the concentrating device constant. It is desirable to control. Thereby, a process flow rate can be stabilized as the whole sludge concentration dehydration system.

  In the first feature of the present invention, the control device compares the press-fit pressure measured by the pressure gauge with a preset reference press-fit pressure range, and when the press-fit pressure value is larger than the reference press-fit pressure range value, When the discharge amount from the concentrated sludge supply pump is reduced and the pressure injection pressure value is within the standard injection pressure range, the discharge amount from the concentrated sludge supply pump is maintained, and the pressure injection pressure value is higher than the reference pressure input pressure range value. If small, it is desirable to increase the discharge from the concentrated sludge supply pump. Further, the control device compares the liquid level measured by the liquid level measuring device with a preset reference liquid level range, and when the liquid level value is higher than the reference liquid level range value, the rotational speed of the dehydrating screw shaft When the liquid level value is within the reference liquid level range, the rotation speed of the dehydrating screw shaft is maintained, and when the liquid level value is lower than the reference liquid level range value, the rotation speed of the dehydrating screw shaft is decreased. It is desirable to reduce it. When the control device performs the above control, the filtration and dehydration pressure in the dehydrator can be controlled to be constant, and a stable dehydration operation is possible, and at the same time, the dehydrator is idle and overflows from the liquid level measuring device. Can be suppressed.

  The second feature of the present invention is that the sludge is filtered to generate concentrated sludge, and the concentrated sludge discharged from the concentrator is temporarily stored, and the liquid level of the stored concentrated sludge is measured. A liquid level measuring device, a concentrated sludge supply pump that discharges the concentrated sludge temporarily stored by the liquid level measuring device, a pressure gauge that measures the pressurization pressure of the concentrated sludge discharged from the concentrated sludge supply pump, and the concentrated sludge The present invention relates to a control method of a sludge concentration and dehydration system including a dewatering device that press-fits concentrated sludge discharged from a supply pump and dehydrates the concentrated sludge. In this control method, the press-fit pressure measured by the pressure gauge is compared with a preset reference press-fit pressure range, and if the press-fit pressure value is larger than the reference press-fit pressure range, the discharge amount from the concentrated sludge supply pump If the pressure injection pressure value is within the standard pressure injection pressure range, the discharge amount from the concentrated sludge supply pump is maintained.If the pressure injection pressure value is smaller than the standard pressure injection pressure range, the concentration sludge supply pump Increase emissions. Then, the liquid level measured by the liquid level measuring device is compared with a preset reference liquid level range, and when the liquid level value is higher than the reference liquid level range value, the rotational speed of the dehydrating screw shaft is increased, When the liquid level value is within the reference liquid level range, the rotational speed of the dehydrating screw shaft is maintained, and when the liquid level value is lower than the value of the reference liquid level range, the rotational speed of the dehydrating screw shaft is decreased.

  According to the sludge concentration and dewatering system of the present invention and the control method thereof, stable dewatering operation is realized, and the dewatering device is prevented from empty operation and overflow from the liquid level measurement device, thereby stabilizing the concentrated sludge at a constant flow rate. And can be concentrated and dehydrated.

It is a block diagram which shows the sludge concentration dehydration system which concerns on embodiment of this invention. It is the schematic which shows the specific apparatus structural example of the sludge concentration dehydration system of FIG. It is sectional drawing which shows the specific structural example (rotary concentrator 11) of the concentrator 10 of FIG. It is sectional drawing which shows the specific structural example (screw press 31) of the dehydrator 30 of FIG. It is sectional drawing which expands and shows the concentrated sludge supply side of the screw press 31 of FIG. It is sectional drawing which expands and shows the concentrated sludge discharge | emission side of the screw press 31 of FIG. It is a flowchart figure which shows the control method of the sludge concentration dehydration system which concerns on embodiment of this invention.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and the configuration of the apparatus and system is different from the actual one. Therefore, a specific configuration should be determined in consideration of the following description. In addition, it is a matter of course that portions having different configurations are included between the drawings.

  The following embodiments of the present invention exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is the material and shape of the component parts. The structure, arrangement, etc. are not specified as follows. The technical idea of the present invention can be variously modified within the technical scope described in the claims.

<Functional configuration of sludge concentration and dehydration system>
As shown in FIG. 1, the sludge concentration and dewatering system according to the embodiment of the present invention is produced by aggregating and stirring a sludge stock solution with a polymer flocculant and filtering the agglomerated sludge supplied at a constant flow rate to produce concentrated sludge. The concentration device 101, the concentrated sludge discharged from the concentration device 101 is temporarily stored, and the liquid level measurement device 102 that measures the liquid level of the stored concentrated sludge, and the liquid level measurement device 102 temporarily stored. The concentrated sludge supply pump 103 that discharges the concentrated sludge, the pressure gauge 104 that measures the press-fitting pressure of the concentrated sludge discharged by the concentrated sludge supply pump 103, and the concentrated sludge discharged from the concentrated sludge supply pump are pressed and injected. The amount of discharge from the concentrated sludge supply pump 103 is controlled on the basis of the dewatering device 105 for dewatering the concentrated sludge and the pressure of the concentrated sludge measured by the pressure gauge 104, and the liquid Based on the liquid level measuring device 102 is measured, and a control unit 106 for controlling the rotational speed of the dewatering screw shaft dewatering device 105 is provided. The control device 106 keeps the rotation speed of the concentration screw shaft included in the concentration device 101 constant.

  The concentrator 101 concentrates the sludge stock solution so as to have a predetermined sludge concentration.

  The liquid level measurement device 102 temporarily stores the concentrated sludge discharged continuously from the concentration device 101, and detects, detects, and measures the liquid level of the stored concentrated sludge. The liquid level of the concentrated sludge is due to fluctuations in the sludge properties, for example, the influence of the filterability of the concentrated sludge. The sludge liquid level rises due to the decrease in filterability.

  The concentrated sludge supply pump 103 applies pressure to the concentrated sludge in the flow direction so that the concentrated sludge discharged from the liquid level measuring device 102 is discharged at a flow rate higher than the supplied flow rate. The concentrated sludge discharged from the concentrated sludge supply pump 103 is pressed into the dehydrator 105.

  The pressure gauge 104 measures the press-fitting pressure of the concentrated sludge discharged from the concentrated sludge supply pump 103 at a supply port of the dehydrator 105 described later.

  The dehydrator 105 dehydrates the filtered sludge by filtering it. That is, the moisture content of the concentrated sludge is lowered by squeezing out the water from the concentrated sludge that is press-fitted by the concentrated sludge supply pump 103.

  As the dehydrating apparatus 105, a screw press, an impeller rotary pressurizing dehydrator, a belt press, a vacuum dehydrator, and a centrifugal dehydrator can be applied. As the dehydrating apparatus 105 according to the embodiment of the present invention, an outer cylinder rotary type screw press can be applied.

  The control device 106 controls the number of rotations of the concentrated sludge supply pump 103 based on the pressurization pressure of the concentrated sludge at the supply port of the dewatering device 105 measured by the pressure gauge 104, thereby discharging the concentrated sludge supply pump 103. To control. Further, the control device 106 controls the number of rotations of the screw shaft included in the dewatering device 105 based on the liquid level of the concentrated sludge measured by the liquid level measuring device 102. Moreover, the control apparatus 106 keeps constant the rotation speed of the screw shaft with which the concentration apparatus 101 is provided.

  That is, the control device 106 compares the press-fit pressure measured by the pressure gauge 104 with a preset reference press-fit pressure range. Here, the reference press-fit pressure range is an empirical value suitable for realizing an appropriate sludge treatment. Based on the result of the comparison, when the value of the press-fit pressure is larger than the value of the reference press-fit pressure range, the control device 106 reduces the discharge rate by reducing the rotation speed of the concentrated sludge supply pump 103. When the value of the press-fit pressure is within the reference press-fit pressure range, the rotation speed and discharge amount of the concentrated sludge supply pump 103 are maintained. When the value of the press-fitting pressure is smaller than the value of the reference press-fitting pressure range, the number of revolutions of the concentrated sludge supply pump 103 is increased to increase the discharge amount.

  In addition, the control device 106 compares the liquid level measured by the liquid level measuring device 102 with a preset reference liquid level range. Here, the reference liquid level range is an empirical value suitable for realizing appropriate sludge treatment. Based on the result of the comparison, when the liquid level value is higher than the reference liquid level range value, the control device 106 increases the rotation speed of the dewatering screw shaft included in the dewatering device 105. When the value of the liquid level is within the reference liquid level range, the rotation speed of the dehydrating screw shaft is maintained. And when the value of a liquid level is lower than the value of a reference | standard liquid level range, the rotation speed of a dehydration screw shaft is decreased. When the rotational speed of the dewatering screw shaft included in the dewatering device 105 is increased, the conveying speed by the screw blades increases in the filtration chamber, the pressure in the filtration chamber decreases, and the liquid level measuring device is controlled by the rotational speed control of the concentrated sludge supply pump. The amount of concentrated sludge discharged increases and the liquid level falls. On the other hand, when the rotational speed of the dewatering screw shaft included in the dewatering device 105 is decreased, the conveying speed by the screw blades decreases in the filtration chamber, the pressure in the filtration chamber increases, and the liquid level is measured by controlling the rotational speed of the concentrated sludge supply pump. The amount of concentrated sludge discharged from the device decreases and the liquid level rises.

  As described above, the control device 106 controls the concentrated sludge supply pump 103 so that the press-fitting pressure in the dewatering device 105 is constant, and the liquid level measured by the liquid level measuring device 102 is within the reference liquid level range. The dehydrator 105 is controlled so that That is, the control device 106 controls the number of rotations of the concentrated sludge supply pump 103 based on the measurement result of the pressure gauge 104, and the dehydration device 105 includes the dehydration device 105 based on the liquid level measured by the liquid level measurement device 102. Controls the rotational speed of the screw shaft.

<Equipment configuration of sludge concentration and dehydration system>
With reference to FIG. 2, the example of a specific apparatus structure of the sludge concentration dehydration system of FIG. 1 is demonstrated. The sludge concentration and dehydration system 100 supplies a processing stock solution such as raw sludge stored in a sludge storage tank (not shown) to the aggregating device 3 through the stock solution supply pipe 2 at a stock solution flow rate (supply flow rate) by the stock solution supply pump 1. To do. A polymer supply pump 4 is connected to the stock solution supply pipe 2 via a flocculant supply pipe 5. The polymer supply pump 4 supplies the polymer flocculant to the flocculant supply pipe 5. Note that the flocculant supply pipe 5 can be directly connected to the aggregating apparatus 3. The polymer flocculant is supplied at a constant rate relative to the stock solution flow rate. The control device 60 controls the rotation speed of the polymer supply pump 4 and the rotation speed of the stock solution supply pump 1 so that they are proportional to each other.

  The aggregating device 3 agitate and mix the sludge and the polymer aggregating agent supplied to the aggregating device 3 from the stock solution supply pump 1 and the polymer supply pump 4, respectively, to generate agglomerated floc. The processing stock solution and the polymer flocculant that have flowed into the agitation tank 6 are agitated by the agitation blade 8 that is rotationally driven by the agitation drive unit 7. The agglomerated sludge stirred and agglomerated by the aggregating device 3 is supplied to the concentrator 10 through the agglomerated sludge supply pipe 9.

  The concentrator 101, the liquid level measuring device 102, the concentrated sludge supply pump 103, the pressure gauge 104, the dehydrator 105, and the controller 106 shown in FIG. 1 are the concentrator 10, the concentrated sludge pipe (hopper) 26 shown in FIG. And the liquid level gauge 28, the concentrated sludge supply pump 27, the pressure gauge PS, the dehydrator 30, and the control device 60, respectively.

<Apparatus configuration of the concentrator 10>
With reference to FIG. 3, the specific structural example (rotary concentrator 11) of the concentrator 10 of FIG. 2 is demonstrated. The rotary concentrator 11 includes an outer cylinder screen 12 having a filtration surface on the periphery, and a screw shaft 14 installed inside the outer cylinder screen 12. Screw blades 13 are spirally wound around the screw shaft 14. An inlet flange 15 and an outlet flange 16 are fitted to the end of the outer cylinder screen 12. The screw shaft 14 is rotatably supported by an inlet flange 15, and is rotatably supported by a bearing 19 that supports an outer cylinder drive shaft 17 connected to an outlet flange 16 on a filtrate receiving tank 18. A screw drive shaft 20 is connected to the screw shaft 14, and the screw drive shaft 20 is inserted into the outer cylinder drive shaft 17.

  A sludge supply path 21 is provided at the end of the screw shaft 14 on the inlet flange 15 side. A plurality of supply ports 21 a are opened near the start end of the outer cylinder screen 12 of the screw shaft 14. The outlet flange 16 is provided with a plurality of outlets 16a. A filtration chamber 22 is formed between the outer cylinder screen 12 and the screw shaft 14. An outer cylinder driving machine 23 and a screw driving machine 24 are individually linked and connected to the outer cylinder driving shaft 17 of the outer cylinder screen 12 and the screw driving shaft 20 of the screw shaft 14. The outer cylinder driving machine 23 and the screw driving machine 24 rotate the outer cylinder screen 12 and the screw shaft 14 at different speeds in opposite directions. The rotary concentrator 11 reversely rotates the outer cylinder screen 12 and the screw shaft 14. Thereby, the sludge supplied to the filtration chamber 22 from the supply path 21 of the screw shaft 14 is concentrated by being separated from the filtrate through the outer cylinder screen 12. The sludge concentrated by the rotary concentrator 11 (concentrated sludge) is discharged from the outlet 16 a of the outlet flange 16.

  By rotating the outer cylinder screen 12 and the screw shaft 14 at a differential speed, the rotational speed of the screw blade 13 is relatively increased, and the number of sliding contact of the filtration surface of the outer cylinder screen 12 is increased. The rotary concentrator 11 regenerates the filtration surface of the outer cylinder screen 12 that is clogged during operation, thereby promoting the discharge of the filtrate and realizing a large amount of sludge treatment with a low concentration. The cleaning water pipe 25 shown in FIG. 3 is disposed along the outer cylinder screen 12, and jets high-pressure water onto the clogged outer cylinder screen 12 to eliminate clogging of the filtration surface. Further, by supplying a part of the filtrate separated and discharged to the filtrate receiving tank 18 into the concentrated sludge pipe 26, bridge of the concentrated sludge in the concentrated sludge pipe 26 is prevented, and the concentrated sludge supply pump 27 is supplied smoothly. It becomes possible.

  The concentrated sludge from which the filtrate has been separated by the rotary concentrator 11 is supplied to the concentrated sludge supply pump 27 via the concentrated sludge pipe (hopper) 26 of FIG. The concentrated sludge pipe 26 has a volume capable of storing the concentrated sludge discharged from the rotary concentrator 11 with a predetermined capacity, and a liquid level meter 28 for measuring the storage amount is provided. The concentrated sludge stored in the concentrated sludge pipe 26 is press-fitted and supplied to the dehydrator 30 through the concentrated sludge supply pipe 29 by the concentrated sludge supply pump 27. The concentrated sludge supply pipe 29 is provided with a pressure gauge PS for measuring the press-fitting pressure of the concentrated sludge that is press-fitted and supplied to the dehydrator 30.

<Device configuration of the dehydrator 30>
A specific configuration example (screw press 31) of the dehydrator 30 in FIG. 2 will be described. The screw press 31 is placed in the vicinity of the rotary concentrator 11. For example, the concentrated sludge pipe 26 is disposed on the discharge side of the rotary concentrator 11, the concentrated sludge supply pump 27 is disposed on the discharge side of the concentrated sludge pipe 26, and the screw press 31 is disposed on the discharge side of the concentrated sludge supply pump 27. Arrange. Since the screw press 31 is placed in the vicinity of the rotary concentrator 11, it is not necessary to retain the concentrated sludge in the storage tank for a long time, and the dehydration effect due to rot does not decrease. Further, a large installation area for the rotary concentrator 11, the concentrated sludge pipe 26, and the screw press 31 is not required. Therefore, if it is installed in wastewater treatment facilities such as sewage, human waste treatment, village drainage, and factories, it becomes a space-saving concentrated water-saving facility.

  As shown in FIG. 4, the screw press 31 includes an outer cylinder screen 32 having a filtration surface in the peripheral portion, and a screw shaft 34 disposed in the outer cylinder screen 32. A screw blade 33 is spirally wound around the screw shaft 34. The diameter of the screw shaft 34 increases from the sludge supply side toward the cake discharge side, and the filtration chamber 35 between the outer cylinder screen 32 and the screw shaft 34 extends from the supply side toward the discharge side. It shrinks in the vertical direction on the page.

  The configuration on the supply side of the screw press 31 will be described with reference to FIG. An inlet flange 36 is fitted on the supply side end of the outer cylinder screen 32, and a sprocket 37 is fitted on the inlet flange 36. The sprocket 37 is interlocked and connected to an outer cylinder driving device 39 that is placed on a frame 38 and can be rotated forward and backward. The screw shaft 34 is provided with a supply path 41 for agglomerated slurry, and a supply hole 41 a is opened at the start end of the screw shaft 34. The extending portion of the screw shaft 34 is connected to the concentrated sludge supply pipe 29. The concentrated sludge that is press-fitted into the filtration chamber 35 from the supply hole 41 a is supplied from between the screw blades 33 wound around the screw shaft 34. Thereby, the concentrated sludge such as agglomerated soft sludge is not affected by the screw blades 33. In this embodiment, the outer cylinder screen is rotatable, but may be fixed.

  With reference to FIG. 6, the structure in the discharge | emission side of the screw press 31 is demonstrated. A frame 43 that rotatably supports the rotating plate 42 is connected to the end of the outer cylinder screen 32 on the discharge side. A screw drive shaft 44 is connected to a screw shaft 34 provided in the outer cylinder screen 32. A presser 45 for adjusting the back pressure is installed to face the discharge port 35 a of the filtration chamber 35. The back pressure adjusting presser 45 is slidably supported on a moving shaft 46 disposed on the frame 43.

  As shown in FIG. 4, the screw drive shaft 44 connected to the screw shaft 34 is rotatably supported by a bearing 49 provided on a frame 48 of the frame 43. A sprocket 50 is fixed to the screw drive shaft 44. The sprocket 50 is linked and connected to a screw driver 51 placed on the frame 43. The screw driver 51 rotationally drives the screw shaft 34, and the concentrated sludge is supplied from the supply path 41 of the screw shaft 34 to the filtration chamber 35. The concentrated sludge is dehydrated by being separated from the filtrate from the outer cylinder screen 32 while being transferred by the screw blades 33.

  The presser 45 adjusts the opening amount of the discharge port 35 a of the filtration chamber 35, promotes solid-liquid separation while applying back pressure to the filtration chamber 35, and discharges the dehydrated cake. A cleaning pipe 52 is disposed along the outer cylinder screen 32. During cleaning, cleaning water is sprayed from the cleaning pipe 52 to the outer cylinder screen 32, and the outer cylinder screen 32 is rotated by an outer cylinder drive 39. The entire surface of the outer cylinder screen 32 is cleaned. A filtrate trough 53 is provided below the outer cylinder screen 32 on the paper surface, and a cake receiving tank 54 for receiving dehydrated cake is provided adjacent to the filtrate trough 53 at the end of the screw press 31.

<Control method of sludge concentration and dehydration system>
Next, a control method of the sludge concentration and dehydration system according to the embodiment of the present invention will be described. Specifically, referring to FIG. 7, a method in which the control device 106 in FIG. 1 controls the concentration device 101, the concentrated sludge supply pump 103, and the dehydration device 105 will be described.

  As shown in FIG. 1, the control device 106 controls so that the press-fitting pressure due to the concentrated sludge to the dewatering device 105 is constant in the path from the concentrating device 101 to the dewatering device 105. The control device 106 adjusts the flow rate of the concentrated sludge to be constant by controlling the rotation of the concentrated sludge supply pump 103 so that the concentrated sludge supply pump 103 maintains a predetermined rotation speed. Further, the sludge concentration and dehydration system 100 controls the flow rate of the concentrated sludge to be constant in the path from the concentrated sludge supply pump 103 to the dewatering device 105. The control device 106 controls the rotation of the concentrated sludge supply pump 103 and the rotation of the screw shaft included in the dewatering device 105 so as to maintain a predetermined rotation speed, and adjusts the pressure of the concentrated sludge to be constant. To do. As a result, the dewatered sludge discharged from the dewatering device 105 is generated as a high-quality sludge cake with constant dewaterability.

  (A) First, the control device 106 controls the rotation speed of the concentrated sludge supply pump 103 so that the press-fitting pressure of the concentrated sludge flowing into the dewatering device 105 shown in FIG. Specifically, in step S201, the control device 106 compares the measured press-fitting pressure, which is the press-fitting pressure of concentrated sludge measured by the pressure gauge 104, with a preset reference press-fit pressure range. Here, the reference press-fitting pressure range is a press-fitting pressure to the dehydrating device 105 by the concentrated sludge measured by the pressure gauge 104, and is a pressure range in which the dehydrating efficiency by the dehydrating device 105 is the best. In step S201, when the measured press-fit pressure is larger than the reference press-fit pressure range, the process proceeds to step S202, and the control device 106 decreases the rotation speed of the concentrated sludge supply pump 103. In step S201, when the measured press-fitting pressure is within the reference press-fitting pressure, the process proceeds to step S203, and the control device 106 maintains the rotation speed of the concentrated sludge supply pump 103. In step S201, when the measured press-fit pressure is smaller than the reference press-fit pressure range, the process proceeds to step S204, and the control device 106 increases the rotation speed of the concentrated sludge supply pump 103.

  (B) Thereafter, the control device 106 controls the number of rotations of the dewatering screw shaft included in the dewatering device 105 so that the liquid level measured by the liquid level measuring device 102 becomes constant. Specifically, the process proceeds to step S205, and the control device 106 compares the liquid level (hopper level) measured by the liquid level measuring device 102 with a preset reference liquid level range. In step S205, when the liquid level measured by the liquid level measuring device 102 is higher than the preset reference liquid level range, the process proceeds to step S206, and the control device 106 increases the rotation speed of the dehydrating screw shaft included in the dehydrating device 105. Let In step S205, when the liquid level measured by the liquid level measuring device 102 is within the preset reference liquid level range, the process proceeds to step S207, and the control device 106 maintains the rotational speed of the dehydrating screw shaft included in the dehydrating device 105. . In step S205, when the liquid level measured by the liquid level measuring device 102 is lower than the preset reference liquid level range, the process proceeds to step S208, and the control device 106 decreases the rotation speed of the dehydrating screw shaft included in the dehydrating device 105. Let

  In the above control, the control device 106 keeps the rotation speed of the concentrating screw shaft included in the concentrating device 101 constant.

  When the control device 106 performs the above control, the filtration and dehydration pressure in the dehydrating device 105 can be controlled to be constant, and a stable dehydrating operation can be performed. Overflow from 102 can be suppressed.

  As described above, the sludge concentration and dehydration system according to the embodiment of the present invention is based on the pressure of the concentrated sludge that is press-fitted into the dewatering device (screw press) 105, and the discharge amount from the concentrated sludge supply pump 103, That is, the rotation speed of the concentrated sludge supply pump 103 is controlled. Thereby, the filtration dehydration pressure in the dehydrator 105 can be controlled to be constant, and a stable dehydration operation can be performed. Moreover, since the rotation speed of the dehydrating screw shaft included in the dehydrating device 105 is controlled based on the liquid level measured by the liquid level measuring device 102, it is possible to suppress idle operation of the dehydrating device 105 and overflow from the liquid level measuring device 102. . Therefore, the processing flow rate of concentrated sludge can be stabilized.

  Further, by installing the dehydrator 105 and the concentrator 101 close to each other, the reaction to the press-fitting pressure by the dehydrator 105 is quick, it is possible to respond quickly to changes in the press-in pressure, and the stability of the constant process is improved. Furthermore, the concentrating device 101 and the dewatering device 105 are installed close to each other, and the concentrated sludge is continuously circulated, so that a storage tank for storing the concentrated sludge is not required upstream of the dewatering device 105. In addition, since the liquid level of the concentrated sludge temporarily stored in the liquid level measuring device 102 is also controlled, it is possible to prevent the dehydration device 105 from being idle and overflowing due to the concentrated sludge from the liquid level measuring device (hopper) 102. it can.

  In this way, by keeping the internal pressure of the dewatering device 105 constant, the dewaterability of the concentrated sludge can be made constant and a high quality sludge cake can be produced.

  In addition, the sludge concentration and dewatering system keeps the rotation speed of the concentration screw shaft included in the concentration device 101 constant, and discharges from the concentrated sludge supply pump 103 based on the pressure of the concentrated sludge that is pressed into the dewatering device 105. Control the amount. Thereby, a process flow rate can be stabilized as the whole sludge concentration dehydration system.

  As mentioned above, although this invention was described by embodiment of this invention, it should not be understood that the statement and drawing which make a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. It goes without saying that the present invention includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 100 ... Sludge concentration dehydration system 101 ... Concentrator 102 ... Liquid level measuring device 103 ... Concentrated sludge supply pump 104 ... Pressure gauge 105 ... Dehydrator 106 ... Controller

Claims (4)

A concentration device for filtering sludge to produce concentrated sludge;
A liquid level measuring device for temporarily storing the concentrated sludge discharged from the concentration device, and measuring the liquid level of the stored concentrated sludge;
A concentrated sludge supply pump for discharging the concentrated sludge temporarily stored by the liquid level measuring device;
A pressure gauge for measuring the pressure of the concentrated sludge discharged from the concentrated sludge supply pump;
A dewatering device in which the concentrated sludge discharged from the concentrated sludge supply pump is press-fitted and dehydrated the concentrated sludge;
Based on the press-fitting pressure measured by the pressure gauge, the amount of discharge from the concentrated sludge supply pump is controlled, and based on the liquid level measured by the liquid level measuring device, rotation of the dehydrating screw shaft included in the dehydrating device A control device for controlling the number;
A sludge concentration and dehydration system comprising:   The sludge concentration and dehydration system according to claim 1, wherein the rotation speed of the concentration screw shaft included in the concentration device is kept constant. The control device compares the press-fit pressure measured by the pressure gauge with a preset reference press-fit pressure range, and when the value of the press-fit pressure is larger than the value of the reference press-fit pressure range, the concentrated sludge supply pump When the value of the press-fit pressure is within the reference press-fit pressure range, the discharge amount from the concentrated sludge supply pump is maintained, and the value of the press-fit pressure is greater than the value of the reference press-fit pressure range. Is also small, increase the discharge from the concentrated sludge supply pump,
The liquid level measured by the liquid level measuring device is compared with a preset reference liquid level range, and when the liquid level value is higher than the reference liquid level range, the rotation speed of the dehydrating screw shaft is increased. When the value of the liquid level is within the reference liquid level range, the rotational speed of the dehydrating screw shaft is maintained, and when the value of the liquid level is lower than the value of the reference liquid level range, the dehydrating screw shaft The sludge concentration and dehydration system according to claim 1 or 2, wherein the number of rotations is reduced. A concentration device that filters sludge to produce concentrated sludge, a liquid level measuring device that temporarily stores the concentrated sludge discharged from the concentration device, and measures the liquid level of the stored concentrated sludge, The concentrated sludge supply pump that discharges the concentrated sludge temporarily stored by the liquid level measuring device, the pressure gauge that measures the press-fitting pressure of the concentrated sludge discharged from the concentrated sludge supply pump, and the concentrated sludge supply pump And a dewatering device for dewatering the concentrated sludge, the concentrated sludge discharged from
Compare the press-fit pressure measured by the pressure gauge with a preset reference press-fit pressure range,
If the value of the press-fit pressure is greater than the value of the reference press-fit pressure range, decrease the discharge amount from the concentrated sludge supply pump,
When the value of the press-fitting pressure is within the reference press-fitting pressure range, the discharge amount from the concentrated sludge supply pump is maintained,
If the value of the press-fit pressure is smaller than the value of the reference press-fit pressure range, increase the discharge amount from the concentrated sludge supply pump,
Compare the liquid level measured by the liquid level measuring device with a preset reference liquid level range,
If the value of the liquid level is higher than the value of the reference liquid level range, increase the rotation speed of the dehydrating screw shaft,
When the value of the liquid level is within the reference liquid level range, the number of rotations of the dehydrating screw shaft is maintained,
When the liquid level value is lower than the reference liquid level range, the rotational speed of the dewatering screw shaft is decreased.

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