JP5528004B2 - Screw press type dehydrator and control method thereof - Google Patents

Description

  The present invention relates to a screw press-type dewatering device for dewatering sludge generated by sewage, human waste, industrial wastewater, and other wastewater treatment, and a control method therefor.

  When the sludge is dewatered with a screw press type dewatering device, the moisture content of the cake is adjusted by adjusting the shaft rotation speed of the screw press and the opening of the tapered cone that adjusts the clearance of the dewatered cake discharge port. Further, when a portion without screw blades (hereinafter referred to as “plug zone”) is provided at the dewatered cake discharge port, the water content can be adjusted by the length. In general, the cake moisture content decreases as the shaft speed and taper cone opening of the screw press are reduced and the plug zone is lengthened.

  On the other hand, when the moisture content of the cake decreases, the cake discharge resistance increases, the filter and the cake outside the screw press easily slip, the cake itself adheres to the screw shaft, and the cake rotates together with the screw shaft. Will occur. If such a co-rotation phenomenon occurs, the cake cannot be discharged and the dehydration process becomes impossible.

Japanese Patent Laid-Open No. 11-320192

  In the conventional screw press type dehydrator, there is no appropriate method to prevent the co-rotation phenomenon between the screw shaft of the screw press and the cake, and the taper cone is removed when the moisture content is suppressed or the cake discharge is reduced. If it is too late to stop the operation of the screw press type dehydrator, disassemble the screw press filter and disassemble the screw shaft. The current situation is to remove the attached cake.

  This invention is made | formed in view of the above-mentioned point, and it aims at providing the screw press type | mold dehydration apparatus which can prevent the co-rotation of a cake, and its control method, aiming at the moisture content reduction of a dehydrated cake.

In order to solve the above problems, the present invention provides a screw having a sludge supply section and a dewatered cake discharge port, and a screw blade provided on a shaft whose shaft diameter is increased at an inclination angle toward the dewatered cake discharge port. covering the outer periphery of the shaft in the filtration body, with filtered dewatering through the filtration body while conveying the sludge was introduced from the sludge supply unit, a screw press type screw shaft is provided with a slidable screw press axially dehydration in the apparatus, the pressure pattern in the screw press dehydration even cake without least the outlet side provided the pressure measuring means for measuring the pressure of the screw in the press at a point of two positions, the points measured by the pressure measuring means P _B There pressure P _a of the plug zone no screw blade cake near the outlet, the pressure around the blade end of the cake outlet side of the screw blade, Ke If the pressure between one pitch before the blade from the key outlet side of the blade end in the case of the P _C becomes _{P C> P B ≧ P A} , or sliding the screw when the P _C> P _B And a control means for controlling the opening and closing of the tapered cone for adjusting the clearance of the dewatering cake discharge port and the cleaning of the filter body .

Further, the present invention provides a sludge supply part and a dewatered cake discharge port, and the outer periphery of the screw shaft equipped with screw blades on the shaft whose diameter is increased at an inclination angle toward the dewatered cake discharge port is a filter body. covering, with filtered dewatering through the filtration body while transporting the sludge was introduced from the sludge supply unit, the screw shaft is a control method for a screw press type dewatering device having a slidable screw press in the axial direction , even without less of dehydrated cake outlet side the pressure in the screw press is measured at the point of two positions, the pressure of the plug zone pressure pattern no screw blade in the vicinity cake outlet in a screw press which is measured at the point P _a, the pressure between the pressure P _B, 1 pitch before the blade from the blade end of the cake outlet side near the blade end of the cake outlet side of the screw blade If the case of the P _C becomes _{P C> P B ≧ P A} , or P _C> sliding screw shaft when the P _B, opening and closing of the tapered cone for adjusting the clearance of dehydrated cake discharge opening, and wherein By controlling the washing of the filter body, the moisture content of the dewatered cake is adjusted and the dewatered cake is prevented from co-rotating.

The present invention prevents sludge generated by sewage, human waste, industrial wastewater, and other wastewater treatments from causing blockage of the apparatus due to co-rotation of the dewatered cake and the screw shaft while maintaining the predetermined moisture content of the dewatered cake. The sludge can be dehydrated.

It is a figure showing a schematic structure of a screw press type dehydrating device concerning the present invention.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a diagram showing a schematic configuration of a screw press type dehydrating apparatus according to the present invention. In the figure, reference numeral 3 denotes a cylindrical filter body. A sludge supply unit 1 having a hopper 2 is provided at one end of the filter body 3, and a dehydrated cake discharge port 6 is provided at the other end of the filter body 3. Yes. A screw shaft 5 having screw blades 4 on the outer periphery is provided inside the filter body 3. The shaft 5 a of the screw shaft 5 is a shaft having an increased shaft diameter at a certain inclination angle toward the dewatered cake discharge port 6. A concentric taper cone 7 of the shaft 5a is provided on the side of the dewatering cake discharge port 6 of the shaft 5a of the screw shaft 5. In addition, the hatched part in the figure is the plug zone 12 without the screw blades 4.

  Reference numeral 9 denotes a drive device for rotating the screw shaft 5. The rotational drive force of the drive device 9 is transmitted to the shaft 5a of the screw shaft 5 via a sprocket and a chain (not shown). 10 is a hydraulic drive device for sliding the screw shaft 5 in the axial direction, and 11 is a taper cone drive device for opening and closing the taper cone 7. The hydraulic drive device 10 and the tapered cone drive device 11 are driven when a signal to be described later is issued, and the screw shaft 5 is slid in the axial direction as indicated by arrows D and E, respectively, and the tapered cone 7 is changed to the arrow F. It is moved and opened and closed as shown.

  8-1, 8-2, and 8-3 are pressure sensors for detecting the pressures of the respective parts in the screw press. The pressure sensor 8-1 is in the A part of the plug zone 12, and the pressure sensor 8-2 is the screw shaft 5. The pressure sensor 8-3 is disposed in a portion B between the last blade of the screw blade 4 and the next blade in the vicinity of the last blade of the screw blade 4, and detects the pressure of each portion.

  The drive device 9 is operated to operate the screw shaft 5 at a predetermined rotational speed. Next, a predetermined amount of sludge conditioned by a sludge refining device (not shown) is charged into the hopper 2 of the sludge supply unit 1. The introduced sludge is filtered by the filter body 3, and the filtrate is discharged out of the system. The filtered solid matter (dehydrated sludge) is transferred to the dehydrated cake discharge port 6 side by the screw blade 4. Further, since the shaft diameter of the shaft 5a of the screw shaft 5 is increased at a certain inclination angle toward the dewatered cake discharge port 6 as described above, the volume of the chamber formed by the screw blades 4 is gradually decreased. For this reason, the filtered solid matter is forced into a narrow room, so that dehydration and volume reduction proceed. Further, the plug zone 12 without the screw blades 4 and the tapered cone 7 having a predetermined opening is further compressed, and the dehydration proceeds further, and the dehydrated cake is discharged as a dehydrated cake 6.

In the screw press type dehydrator, in order to continue the continuous operation, the rotational speed of the screw shaft 5, the length of the plug zone 12, and the taper cone 7 are adjusted so that the water content of the dewatered cake becomes the target water content. Adjust the opening to a predetermined value. At this time, the hydraulic drive device 10 and the pressure detection values P _A , P _B , and P _{C of} the A part, the B part, and the C part detected by the three pressure sensors 8-1, 8-2, and 8-3, and The operation command to the taper cone drive device 11 is issued. That is, the pattern of the pressure detection values P _A , P _B , and P _C of the pressure sensors 8-1, 8-2, and 8-3 in the steady state is P _B > P _A > P _C. Although it is not necessary to issue an operation command to the drive unit 10 and the tapered cone drive unit 11, the pattern of the pressure detection values P _A , P _B , and P _C at the time of simultaneous rotation is P _C > P _B ≧ P _A In this case, an opening command for opening the taper cone 7 is output to the taper cone drive device 11, and a command for sliding the screw shaft 5 toward the dewatering cake discharge port 6 is output to the hydraulic drive device 10. Open and slide the screw shaft 5 to forcibly discharge the closed dehydrated cake out of the screw press.

Furthermore, when clogging of the filter body 3 occurs, the filter body 3 in the dehydrated cake discharge port 6 is washed. After a certain interval, a determination of the pressure pattern by sampling the pressure detected value P _A, P _B, the P _C, After returning the pressure pattern during steady-state, releases the operation command.

In the above example, the "co-rotation phenomenon" is detected by the three pressure sensors 8-1, 8-2, and 8-3 in the pressure in the screw press. For example, the pressure in the screw press can be detected and controlled by two pressure sensors. By placing pressure sensors at three or more points in the screw press and covering the pressures at three or more points with pressure sensors arranged at only two points, the probability of incorporating "non-co-rotation" noise increases. Although the frequency of the shaft sliding of 5 increases, the screw press type dehydrating apparatus as a whole is not a big problem, and the control is simple and the operation is easier. Specifically, the control is performed using only two points P _B and P _C among the three detected pressure values P _A , P _B and P _{C described} above. The state of P _B > P _A > P _C is substituted by the state of P _B > P _C , and the state of P _C > P _B > P _A is substituted by P _C > P _B , so that three points of pressure are detected. It is possible to perform substantially the same control as the above.
This will be described in detail with reference to examples.

Here, the screw press whose diameter of the screw blade 4 of a screw press type | mold dehydrator is 250 mm is used. As a conventional example, an apparatus in which each pressure sensor 8-1, 8-2, 8-3 was removed from the screw press type dehydrating apparatus according to the present invention was used. The sludge to be treated was a mixed sludge of raw urine and septic tank sludge, and the sludge having a pollution concentration of 10.6 g / L. The amount of sludge supplied was 2 m ³ / h and tempered with polyferric sulfate and amphoteric polymer. The target moisture content of the cake was set to 70% or less. Therefore, the rotational speed of the screw shaft 5 is 0.5 rpm, the length of the plug zone 12 is 200 mm, and the opening degree of the tapered cone 7 is 30 mm. The shaft sliding of the screw shaft 5 was periodically set to be once / 30 min, and the sliding width was 150 mm.

  In the conventional example, since there is no pressure sensor, all of the solid matter processing amount was handled manually as an index. When judged to be steady, the solids throughput was 20 kg / h and the water content of the dehydrated cake was 71.3%. Since the target value of the moisture content of the dehydrated cake is 70% or less, when the opening degree of the tapered cone 7 is changed from 30 mm to 25 mm, after 30 minutes, the moisture content of the dehydrated cake becomes 69.5% and the solids processing amount is 19. It became 5 kg / h. After 30 minutes in this state, the amount of solids processing decreased to 14.7 kg / h at a stroke, so the opening of the taper cone 7 was set to 40 mm and the shaft was slid. Blocked.

On the other hand, in the screw press type dehydrator according to the present invention, when the pressure detection values P _A , P _B , and P _C of the pressure sensors 8-1, 8-2 and 8-3 are P _B > P _A > P _C , No operation command is issued to the hydraulic drive unit 10 and the taper cone drive unit 11, and when P _C ≧ P _B ≧ P _A , the taper cone 7 is opened 5 mm so that the shaft slides once, and after 5 minutes, again. When the pressure pattern was determined and P _B > P _A ≧ P _C did not return, a sequence was set up to repeat the same operation.

The pressure pattern of the pressure detection value when it was determined to be steady was P _B = 0.09 MPa, P _A = 0.04 MPa, and P _C = 0.01 MPa. 30 minutes after the opening of the taper cone 7 was changed from 30 mm to 25 mm, the pressure pattern of the pressure detection values became P _C = 0.09 MPa, P _B = 0.07 MPa, P _A = 0.05 MPa, and therefore the taper cone 7 was 5 mm. Opened and the shaft slid once. Since the pressure pattern of the detected pressure value after 5 minutes was P _B = 0.08 MPa, P _A = 0.05 MPa, and P _C = 0.05 MPa, the operation was continued in this state. The pressure pattern of the pressure detection value after 30 minutes is P _B = 0.09 MPa, P _A = 0.05 MPa, P _C = 0.02 MPa, the dehydrated cake moisture content is 69.7%, and the solids throughput is 20. It became 1 kg / h. For convenience, the operation command to the hydraulic drive device 10 and the taper cone drive device 11 was issued four times in the operation for 7 hours, but the operation was possible without being blocked. Moreover, the average water content and solid matter throughput were 69.6% and 19.8 kg / h, respectively.

  Similarly, when a dehydration test was performed with control using only two pressure detection points, the B part and the C part, the operation command to the hydraulic drive device 10 and the taper cone drive device 11 was given five times in a 7-hour operation. It was generated but could be operated without clogging. The average moisture content of the dehydrated cake was 69.9%, and the treatment rate was 20.5 kg / h.

  In the present embodiment, the washing operation of the filter body 3 is not performed, but when the filter body is blocked by a dehydrating aid or other substances, the washing operation of the filter body can be added. Moreover, it is also possible to add the operation time of the sludge supply pump (not shown) which supplies sludge to a parameter | index, and to combine washing | cleaning operation of the filter body 3 into a sequence. That is, the cleaning operation of the filter body 3 may be performed every time the sludge supply pump has been operating for a predetermined time.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Can be modified. Note that any shape or structure not directly described in the specification and drawings is within the technical scope of the present invention as long as the effects of the present invention are achieved. For example, although the screw press type dehydrating device in which the screw shaft 5 is slidable in the axial direction has been described as an example, a screw press type dehydrating device in which the screw shaft does not slide in the axial direction may be used.

  The present invention measures the pressure in the screw press at at least two points on the dewatering cake discharge port side of the screw press type dewatering device, and slides the screw shaft according to the pressure pattern in the screw press at the point. By controlling the opening and closing of the tapered cone that adjusts the clearance of the discharge port and the filter body washing, the dewatering cake is prevented from co-rotating. In addition, sludge can be treated while maintaining a predetermined moisture content of the dewatered cake without causing the apparatus to be blocked.

DESCRIPTION OF SYMBOLS 1 Sludge supply part 2 Hopper 3 Filter body 4 Screw blade 5 Screw shaft 6 Dehydrated cake discharge port 7 Tapered cone 8-1 to 3 Pressure sensor 9 Drive apparatus 10 Hydraulic drive apparatus 11 Taper cone drive apparatus 12 Plug zone

Claims (2)

A sludge supply section and a dewatered cake discharge port, and an outer periphery of a screw shaft equipped with a screw blade on a shaft whose diameter is increased at an inclined angle toward the dewatered cake discharge port is covered with a filter, and the sludge supply unit In the screw press type dewatering device provided with a screw press that allows the screw shaft to slide in the axial direction while being filtered and dehydrated through the filter body while transporting more sludge that has been introduced,
The even without less of dehydrated cake discharge port side provided the pressure measuring means for measuring the pressure of the screw in the press at a point of two positions, the pressure pattern within the screw press in the points measured by the pressure measuring means the The pressure in the plug zone without the screw blade near the cake outlet is P _A , the pressure near the blade end on the cake outlet side of the screw blade is P _B , and between the blades one pitch before the blade end on the cake outlet side When the pressure of Pc is P _C , when P _C > P _B ≧ P _A , or when P _C > P _B , the screw is slid to adjust the clearance of the dewatered cake outlet. A screw press-type dewatering apparatus comprising a control means for controlling opening and closing and cleaning of the filter body . A sludge supply section and a dewatered cake discharge port, and an outer periphery of a screw shaft equipped with a screw blade on a shaft whose diameter is increased at an inclined angle toward the dewatered cake discharge port is covered with a filter, and the sludge supply unit In the control method of the screw press type dewatering device provided with a screw press in which the screw shaft is slidable in the axial direction while being filtered and dehydrated through the filter body while transporting more sludge,
The even without less of dehydrated cake discharge port side to measure the pressure of the screw in the press at a point of two positions, the plug zone pressure pattern no the cake near the outlet of the screw vane in the screw press measured at said point Is P _A , P _{B is} the pressure near the blade end on the cake outlet side of the screw blade, and P _C is the pressure between the blade end on the cake outlet side and the blade one pitch ahead is P _C > When P _B ≧ P _A or when P _C > P _B , the screw shaft is slid, the opening and closing of the tapered cone for adjusting the clearance of the dewatered cake discharge port, and the cleaning of the filter body are controlled. A control method of a screw press type dehydrating apparatus characterized by adjusting the moisture content of the dehydrated cake and preventing co-rotation of the dehydrated cake.

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