JP2008000769A - High dewatering mechanism-fitted screw press - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw press with high dewatering mechanism which can further press-dewater a dewatered cake to be linked with a screw press. <P>SOLUTION: In the screw press (1) where the dewatered cake is discharged to a cake chute (16), a stirring apparatus (18) is arranged at the lower part of the cake chute (16) formed so as to be a trough shape, a pair of water passable press rolls (22, 23) are oppositely provided at the lower end opening part (16a) in the cake chute (16), and the rotation of the press rolls (22, 22) is synchronized with the frequency of a screw shaft (4), thus the dewatered cake is cracked by the stirring apparatus (18) to leak out moisture at the inside thereof, is uniformly fed to the press rolls (22, 23) and is further pressurized, so as to be a uniform cake with a low water content, and the cake exhibits high dewatering properties. Then, the rotational speed of the screw shaft (4) and the press rolls (22, 23) is changed in accordance with the variation in a processing amount by the season and the change in the properties of sludge, and the regulation of the processing amount of sludge and the water content in the dewatered cake can be performed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a screw press for squeezing and dewatering organic sludge such as sewage, human waste, or food production processing wastewater, and in particular, an improvement of a screw press with a high dehydration mechanism for further dehydrating a dehydrated cake in conjunction with the screw press. About.

In the conventional clew press, flocs are generated by adding a flocculant to difficult-to-filter organic sludge to perform dewatering by pressing. The sludge supplied to the start end of the screw press separates the filtrate from the outer cylinder screen while being conveyed by the screw blades, and takes out the dewatered cake from the discharge port at the other end. In order to reduce the moisture content of the dehydrated cake, the screw press is provided with a pressing plate at the discharge port, and the pressing plate is moved in accordance with the discharge pressure of the dehydrated cake to adjust the pressing pressure. The range of moisture content of dewatered cake that can be compressed with a conventional screw press is 74 to 83% for dewatered sludge cake and 83 to 84% for human waste sludge dehydrated cake. In the dewatered cake of wastewater treatment sludge, the water content is 80 to 84%. An increase in the pressing pressure by the pressure plate at the discharge port of the screw press exerts an effect of reducing the moisture content of the cake, but a clogging phenomenon of the cake occurs at the terminal portion of the screw blade. Even if it can be forcibly transported, the solid matter leaks from the screen, resulting in poor recovery. In order to solve the problem, a screw press type press that detects the thrust load and torque applied to the screw shaft and uses the opening ratio of the discharge port as the optimum condition is known as described in Patent Document 1. is there. Further, in a press roll that directly processes a suspension using a pair of water permeable rolls, the pair of permeable press rolls are disposed in a casing, the suspension is supplied at an overpressure, and the press roll A dehydrator that passes through a permeable outer surface and deposits material on the surface of a press roll is known, for example, as described in US Pat.
Japanese Examined Patent Publication No. 7-12554 (paragraph number 0022, FIG. 1) JP 10-510761 A (Detailed description of the invention, FIG. 1)

  The screw press type press described above has a constant moisture content of the dehydrated cake, which can reduce the moisture content of the cake and improve the recovery rate of the solids. The clogging phenomenon of the cake occurs in this, and the moisture content of the dehydrated cake is limited. Press rolls that directly process suspensions can be used to quickly process filtrates in unfiltered stock solutions such as pulp slurries, but they are difficult to filter organic sludge and low-concentration suspensions. In the treatment, large-scale treatment is impossible, the moisture content is limited, and it is not suitable for dewatering organic sludge. This invention provides the screw press with a high dehydration mechanism that applies the above-described conventional technology and enables the cake moisture content to be reduced and the sludge to be processed in large quantities.

  The screw press with a high dehydration mechanism according to the present invention forms a filtration chamber with a screw shaft on which an outer cylinder screen and screw blades are wound, and the sludge supplied to the start end of the filtration chamber is transferred to the filtrate while being transferred by the screw blades. In a screw press that separates the cake and discharges the dehydrated cake to the cake chute from the end of the filtration chamber, a stirring device is disposed below the trough-shaped cake chute and a pair of passages are passed through the lower end opening of the cake chute. A water-based press roll is installed, and the rotation of the press roll is synchronized with the rotational speed of the screw blades. The dehydrated cake from the screw press is crushed with a stirrer to leak moisture inside the cake, and the press Since it is uniformly supplied to the roll and further pressurized, it becomes a uniform cake with a low water content and exhibits high dehydration properties. In addition, the amount of sludge treated and the moisture content of the dewatered cake can be adjusted by switching the rotational speed of the screw shaft and press roll in accordance with seasonal variations in the amount of treated and sludge properties. And since a press roll rotates in synchronization with the rotation speed of a screw axis | shaft, the dewatering cake discharged | emitted from a screw press does not accumulate on the upper surface of a press roll.

  The structure of the press roll that pressurizes the dewatered cake is a perforated plate stretched around the periphery of a support filter cylinder that has a circumferential groove and has a through hole at the bottom. The separated filtrate is allowed to flow into the cylinder and discharged from the end portion and the lower portion, so that the effect of reducing the moisture content of the cake is obtained, and the solids recovery rate is improved. The means for pressurizing and dehydrating the dewatered cake in conjunction with the screw press is a pair of a scraper that contacts the lower surface of the press roll and a filtrate receiver that is provided with a washing tube, and a pair of press rolls are supported. A scraper and filtrate receiver are supported on the support plate, and an air spring is connected to one end of the support plate, and the other end is pivotally attached so that the gap between the pair of press rolls can be adjusted. Is obtained. And even if the gap between the pair of press rolls is adjusted by the air spring, the scraper and the cleaning pipe move following the movable press roll, and the degree of contact of the scraper with the press roll and the cleaning distance do not change. .

  Corresponding to dehydrated cake that accumulates excessively on the cake chute, a level sensor is arranged on the cake chute above the stirring device, and the rotation of the press roll is increased or the air spring air pressure is lowered to reduce the pressure of the pair of press rolls. The gap is widened to expedite the discharge of the pressed cake. The dehydrated cake discharged from the screw press does not accumulate excessively on the cake chute and is crushed with a stirring device to uniformly press the dehydrated cake. So that it does not cause a failure.

  Since the present invention is configured as described above and synchronizes the rotation of the press roll with the rotational speed of the screw shaft, the press roll follows even if the amount of dehydrated cake discharged varies, and the moisture content is low. It becomes a cake with a high rate and exhibits high dehydrating properties. The dewatered cake that accumulates on the cake chute can cope with the increase in sludge volume and changes in sludge properties depending on the season by adjusting the gap and rotation speed of the press roll.

  An embodiment of the present invention will be described in detail with reference to the drawings. First, FIG. 1 is a longitudinal sectional view of a screw press. The screw press 1 has a screw shaft 4 in which screw blades 3 are wound around an outer cylinder screen 2. The filter chamber 5 between the outer cylinder screen 2 and the screw shaft 4 is reduced from the sludge supply side to the cake discharge side. A stock solution supply hole 7 of the stock solution supply path 6 formed at the start end of the screw shaft 4 is opened in the filtration chamber 5. FIG. 2 is a conceptual diagram of the discharge side of the screw press. A sprocket 9 is fitted to a screw drive shaft 8 connected to a rear end portion of the screw shaft 4, and a screw drive 10 is linked to the sprocket 9. It is. The rotational speed of the screw shaft 4 requires variable speed operation in order to adjust the throughput and the moisture content of the dehydrated cake, and the screw driver 10 uses an inverter motor. The sludge supply pump (not shown) that supplies the coagulated sludge to the filtration chamber 5 of the screw press 1 is configured to have a constant press-fitting pressure control that detects the press-fitting pressure and controls the pump discharge amount. Since the dewatering performance of the screw press 1 is greatly influenced by the type of sludge and sludge properties, especially sludge concentration and crude fiber component content, the sludge supply pump uses a single-screw screw pump with variable quantitative discharge rate. Thus, the press-fitting pressure can be switched.

  As shown in FIG. 1, a pressure plate 12 for adjusting back pressure connected to an air cylinder 11 is disposed on the rear end side of the filtration chamber 5, and the pressure plate 12 is slid on a guide shaft 14 supported on a frame 13. It is hung freely. The air cylinder 11 moves the pressing plate 12 to adjust the clearance of the cake discharge port 15 in the filtration chamber 5. As shown in FIG. 1, the coagulated sludge that is press-fitted into the filtration chamber 5 by the sludge supply pump is conveyed by the screw blade 3 in the concentration zone A while being concentrated by the press-fitting pressure. In the filtration zone B, the concentrated sludge is squeezed and dehydrated while increasing the internal pressure in response to the volume change and the thrust force generated by the screw blades 3. In the squeezing zone C, squeezing and dehydration is performed by the back pressure of the pressing plate 12 and the thrust force and shearing force of the screw blade 3.

  The clearance of the discharge port 15 of the screw press 1 becomes narrow when the moisture content of the dehydrated cake is high due to the change in sludge properties, and the clearance becomes wide when the moisture content of the dehydrated cake is low. Although not shown in the drawing, in order to obtain a dehydrated cake with uniform moisture, the sliding position of the piston of the air cylinder 11 is detected, the press-fitting pressure to the air cylinder 11 is adjusted, and the pressure plate is adjusted in accordance with the clearance of the discharge port 15. The movement of 12 is adjusted so that the dehydrated cake is taken out to the cake chute 16. In addition, by adjusting the rotational speed of the screw shaft 4, the amount of coagulated sludge and the moisture content of the dewatered cake can be adjusted, and the dewatered cake can be set according to the sludge treatment / disposal method and effective use / process. It becomes possible. Reference numeral 17 denotes a filtrate receiving trough 17 disposed below the outer cylinder screen 2. As shown in FIG. 1, the lower part of the cake chute | shoot 16 arrange | positioned at the discharge port 15 of the screw press 1 is formed in trough shape, and the stirring apparatus 18 for spreading | diffusion is arrange | positioned in the longitudinal direction of the inside. FIG. 2 is a front view of the stirring device disposed on the cake chute. The stirring device 18 has a stirring blade 20 wound around the stirring shaft 19 supported on the frame in the opposite direction from the center to the left and right. Yes, dehydrated cake is crushed uniformly and left and right. A sprocket 21 fitted to the end of the stirring shaft 19 is linked to a unique motor (not shown), and the dehydrated cake falling from the discharge port 15 of the screw press 1 is crushed so that the inside of the cake Stir while allowing the water to be retained to leak, and evenly distribute to the left and right.

  FIG. 3 is an enlarged view of the press roll disposed in the lower end opening of the cake chute, and the press rolls 22 and 23 having a pair of water permeability in the lower end opening 16a of the cake chute 16 in which the stirring device 18 is disposed. The dehydrated cake supplied uniformly from the stirring device 18 is further pressure dehydrated. 4 and 5 are enlarged views of the main part of the press roll. The press rolls 22 and 23 are formed of a perforated plate on the outer peripheral surface of the support filter cylinder 24 having a circumferential groove 24a and a through hole 24b at the bottom. 25 is stretched, and is supported on the support roll 26 by a plurality of support rods 24 c at both ends of the support filter cylinder 24. A cake discharge chute 27 is disposed below the facing surface of the pair of press rolls 22 and 23, and scrapers 28 and 28 are brought into sliding contact with the press rolls 22 and 23 to press and dehydrate the cakes. And is discharged to the cake discharge chute 27. The filtrate receivers 29 and 29 are disposed below the press rolls 22 and 23, and the cleaning pipes 30 and 30 supported inside the filtrate receivers 29 and 29 are provided opposite to the press rolls 22 and 23. High pressure water is sprayed on the porous plates 25 of the clogged press rolls 22 and 23 to regenerate the press rolls 22 and 23. A filtrate receiver 29 having a scraper 28 and a cleaning pipe 30 inscribed therein is supported on a pair of support plates 31 and 31 that support one press roll 22, and an air spring 32 is connected to one end of the support plates 31 and 31. The other end is pivotally attached. One press roll 22 is swung by the air spring 32 to adjust the gap with the other fixed press roll 23.

  As shown in FIG. 2, gears 33, 33 are fitted to end portions of support rolls 26, 26 that support the press rolls 22, 23, and a roll driving machine 34 disposed between the gears 33, 33 is used. Rotate them counterclockwise. The crushed cake is fed into the pair of press rolls 22, 23, and the pressurized cake pressurized by the press rolls 22, 23 is peeled off by the scraper 28 and discharged from the cake discharge chute 27. The filtrate obtained by pressurizing and separating the cake with the press rolls 22 and 23 is drained into the support filter cylinder 24, and the outside of the press rolls 22 and 23 from the side end of the support filter cylinder 24 or the lower through hole 24 b. And drained from the filtrate receiver 29. When the press rolls 22 and 23 are clogged, cleaning water is sprayed from the cleaning pipe 30 to regenerate the filtration surfaces of the press rolls 22 and 23.

  In order to adjust the processing amount and the moisture content of the dehydrated cake due to seasonal fluctuations, the rotational speed of the screw shaft 4 is operated at a variable speed with the screw driver 10, and the press rolls 22, 23 correspond to the rotational speed of the screw shaft 4. The roll drive 34 is operated. In synchronization with the rotational speed of the screw blades 3, the rotation of the press rolls 22 and 23 is increased or decreased so that cake does not accumulate on the cake chute 16 at the top of the stirring device 18. A level sensor 35 is disposed on the top of the cake chute 16, and when the excessively accumulated dehydrated cake is detected, the rotation speed of the press rolls 22 and 23 is increased for a predetermined time. Further, the air pressure of the air spring 32 may be reduced to widen the gap between the pair of press rolls 22 and 23 so that the discharge of the pressure cake sandwiched between the press rolls 22 and 23 may be expedited.

  The screw press with a high dehydration mechanism according to the present invention switches the rotation of the press roll in synchronization with the rotational speed of the screw shaft that switches the rotation speed in accordance with the change in the amount of treatment and the change in sludge properties depending on the season. Corresponding to the amount, the press roll follows and exhibits a high dehydrating property, resulting in a uniform low moisture content cake. And since the gap | interval and rotation speed of a press roll can be adjusted according to the accumulation amount of the dewatering cake of a cake chute, the process amount of sludge and the moisture content of a dewatering cake can be adjusted. Therefore, it becomes a screw press with a high dehydration mechanism suitable for squeezing and dewatering organic sludge such as sewage, human waste, or food production processing wastewater.

It is a longitudinal cross-sectional view of the screw press with a high dehydration mechanism according to the present invention. Similarly, it is a front view of a stirring device disposed on the cake chute. Similarly, it is an enlarged view of a press roll disposed in the lower end opening of the cake chute. Similarly, it is a principal part longitudinal cross-sectional view of a press roll. Similarly, it is a principal part cross-sectional view of a press roll.

Explanation of symbols

2 Outer cylinder screen 3 Screw blade 4 Screw shaft 5 Filtration chamber 16 Cake chute 18 Stirrer 16a Lower end opening 22, 23 Press roll 24 Support filter cylinder 24a Circumferential groove 24b Through hole 25 Perforated plate 28 Scraper 29 Filtrate receiver 30 Washing Tube 31 Support plate 32 Air spring

Claims (4)

  The filtration chamber (5) is formed by the screw shaft (4) around which the outer cylinder screen (2) and the screw blade (3) are wound, and the sludge supplied to the start end of the filtration chamber (5) is converted into the screw blade (3). In a screw press that separates the filtrate while being transferred and discharges the dehydrated cake from the end of the filtration chamber (5) to the cake chute (16), a stirring device is provided below the trough-shaped cake chute (16). (18) is disposed, a pair of water-permeable press rolls (22, 23) are provided at the lower end opening (16a) of the cake chute (16), and the rotation of the press rolls (22, 23) is screwed. A screw press with a high dehydration mechanism that is synchronized with the rotational speed of the shaft (4).   In the press rolls (22, 23), a perforated plate (25) is stretched on the outer periphery of a support filter cylinder (24) having a circumferential groove (24a) and having a through hole (24b) at the bottom. The screw press with a high dehydration mechanism according to claim 1.   A scraper (28, 28) that comes into contact with the lower surface of the press roll (22, 23) and a filtrate receiver (29) for disposing the cleaning pipe (30) are provided in a pair, and one press roll (22) is supported. A scraper (28) and a filtrate receiver (29) are supported on a pair of support plates (31, 31), an air spring (32) is connected to one end of the support plate (31), and the other end is pivotally attached. The screw press with a high dehydration mechanism according to claim 1 or 2, wherein a gap between the pair of press rolls (22, 23) is adjustable.   A level sensor (35) is disposed on the cake chute (16) above the agitator (18) to increase the rotation of the press rolls (22, 23) or reduce the air pressure of the air spring (32). The screw press with a high dehydration mechanism according to any one of claims 1 to 3, wherein a gap between the pair of press rolls (22, 23) is widened to expedite discharge of the pressed cake.

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