JP2005186148A - Method and apparatus for screw press treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the treatment amount of a screw press and further simplify the control of a raw liquid supply system. <P>SOLUTION: An apparatus for screw press treatment is provided with a screw press 10, a raw liquid supply device 20 for supplying raw liquid 38 to the screw press, a raw liquid reservoir 30 in which the raw liquid supply device reserves the raw liquid, and a pump 28 for supplying the raw liquid to the raw liquid reservoir, wherein the raw liquid reservoir has a pressure adding cylinder 31 extending upward and the liquid level of the raw liquid is positioned in the pressure adding cylinder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a screw press processing method and apparatus for compressing a processing stock solution containing sludge and other suspensions by rotating a screw and separating it into moisture and dehydrated cake.

  Conventionally, a screw is housed inside a porous cylinder (cylindrical screen), a stock solution of suspended water containing solids such as sludge and pulp is supplied from one of the cylinders, and the screw is rotated to rotate the water. There is known a screw press sludge treatment apparatus that moves in the axial direction of a screw while compressing the liquid, filters the liquid component through a screen, and separates the solid content in the suspended water.

  A conventional screw press sludge treatment apparatus will be described with reference to FIG.

  FIG. 3 shows a screw press 10 of a screw press sludge treatment apparatus, in which a cylindrical screen 1 is supported so as to rise toward the downstream side, and a screw 2 rotates concentrically inside the cylindrical screen 1. It is provided as possible. The cylindrical screen 1 has a cone shape that narrows from upstream to downstream. The screw 2 is shaped like a cone that narrows from upstream to downstream so that the screw 2 fits into the cylindrical screen 1 and the pitch of the screw blades 3 faces downstream. Gradually becoming smaller.

  An upstream end plate 4 is provided in a liquid-tight manner at the upstream end of the cylindrical screen 1, and a downstream end plate 5 is provided in a liquid-tight manner at the downstream end of the cylindrical screen 1.

  A raw liquid supply pipe 6 is connected to the upstream end plate 4, a filtrate receiver 7 is provided below the cylindrical screen 1, and a filtrate discharge pipe 8 is connected to the lower end of the filtrate receiver 7.

  The downstream end plate 5 is provided with an outlet flange 9, and a back pressure device 11 is provided for the outlet flange 9. The back pressure device 11 applies a conical ring-shaped presser 12 to the opening end of the outlet flange 9 with a cylinder 13 at a required pressure to provide resistance when the cake is discharged. A cake outlet 14 is provided below the outlet flange 9.

  Both ends of the rotary shaft 16 of the screw 2 of the screw press 10 are rotatably supported through bearings 17. A driven sprocket 18 is fixed to one end of the rotary shaft 16. The driven sprocket 18 is driven by a chain 19 to drive a sprocket 22 of a motor 21. It is connected to.

  The stock solution supply pipe 6 is provided with a stock solution supply pump 23, and a pressure detector 24 is provided in the vicinity of the upstream end plate 4 of the stock solution supply pipe 6. Pressure is detected by the pressure detector 24 in the space 15 at the most upstream portion of the cylindrical screen 1, that is, the space 15 formed by the upstream end plate 4 and the most upstream portion of the screw blade 3, and the pressure detection. The detection result of the container 24 is output as an electric signal to the control unit 25, and the control unit 25 controls the discharge amount of the stock solution supply pump 23 so that the pressure in the space 15 in the most upstream part becomes constant. ing.

  When the stock solution is supplied from the stock solution supply pipe 6 and the screw 2 is rotated, the stock solution is sent toward the downstream side by the screw blade 3. The space 15 between the pitches of the screw blades 3 gradually decreases in volume toward the downstream side, and the stock solution is compressed and dehydrated as it moves downstream along the screw 2. It is filtered, falls into the filtrate receiver 7 and is discharged through the filtrate discharge pipe 8.

  The solid content in the undiluted solution is dehydrated and extruded as a cake by the outlet flange 9, but resistance when being extruded by the pressing force of the cylinder 13 is added, and the water content is adjusted to a required level. The cake extruded from the outlet flange 9 falls from the cake outlet 14 and is collected.

  In the process of operating the screw press 10, the space 15 in the most upstream area in the vicinity where the stock solution supply pipe 6 communicates changes greatly as the screw blade 3 rotates. For example, when the upstream end of the screw blade 3 passes through the opening position of the stock solution supply pipe 6, it becomes almost zero.

  As described above, the pressure in the most upstream space 15 is detected by the pressure detector 24, and the discharge amount of the stock solution supply pump 23 is controlled based on the detected pressure. The relationship between the discharge amount (supply amount V) of the pump 23 and the pressure (detected pressure P) in the space 15 in the most upstream part is as shown in FIG.

  As shown in the figure, when the stock solution supply pump 23 is controlled so that the detection pressure P becomes constant, the discharge amount is decreased in the direction in which the detection pressure P increases, and the discharge amount in the direction in which the detection pressure P decreases. Increase. Accordingly, the discharge amount V varies greatly, for example, when the upstream end of the screw blade 3 passes through the opening position of the stock solution supply pipe 6 is minimized.

  For this reason, an average discharge amount decreases and the processing amount in the screw press 10 decreases. Further, since the controller 25 controls the discharge amount of the stock solution supply pump 23 based on the detected pressure P, there is a problem that the control of the stock solution supply system becomes complicated.

  In addition, there exists what is shown by patent document 1 as what controls the supply pressure of the undiluted | stock solution to the said screw press 10. FIG.

Japanese Patent No. 3159353

  In view of such circumstances, the present invention increases the throughput of the screw press and simplifies the control of the stock solution supply system.

  The present invention relates to a screw press processing method for increasing the stock solution supply pressure when the pressure of the stock solution supply unit to the screw press increases.

  The present invention also includes a screw press, a stock solution supply device that supplies the stock solution to the screw press, the stock solution supply device that stores the stock solution, and a pump that supplies the stock solution to the stock solution reservoir, And a liquid level sensor that detects a liquid level in the stock solution reservoir, and relates to a screw press processing apparatus configured to control the pump by a liquid level detection signal from the liquid level sensor.

  The present invention also includes a screw press, a stock solution supply device that supplies the stock solution to the screw press, the stock solution supply device storing a stock solution reservoir that stores the stock solution, and a pump that supplies the stock solution to the stock solution reservoir. The stock solution reservoir has a pressure application cylinder extending upward, and the screw press processing apparatus is configured such that the liquid level of the stock solution is located in the pressure application cylinder.

  Furthermore, the present invention relates to a screw press processing apparatus configured to provide a liquid level sensor for detecting a liquid level in the pressure application cylinder and to control the pump by a liquid level detection signal from the liquid level sensor. .

  According to the present invention, when the pressure of the stock solution supply unit to the screw press increases, the stock solution supply pressure increases, so the total supply amount of the stock solution to the screw press increases and the throughput of the screw press increases.

  Further, according to the present invention, a screw press, a stock solution supply device that supplies the stock solution to the screw press, a stock solution reservoir that stores the stock solution, and a pump that supplies the stock solution to the stock solution reservoir are provided. Since the liquid level sensor for detecting the liquid level in the stock solution reservoir is provided and the pump is controlled by a liquid level detection signal from the liquid level sensor, the pump control system is simplified.

  Further, according to the present invention, a screw press, a stock solution supply device that supplies the stock solution to the screw press, a stock solution reservoir that stores the stock solution, and a pump that supplies the stock solution to the stock solution reservoir are provided. And the stock solution reservoir has a pressure addition cylinder extending upward, and the liquid level of the stock solution is configured to be located in the pressure addition cylinder, so when the supply amount from the stock solution reservoir is reduced, The liquid level in the pressure application cylinder rises, the stock solution supply pressure increases, the decrease in the stock solution supply amount is suppressed, and the throughput of the screw press increases.

  Further, according to the present invention, a liquid level sensor for detecting the liquid level is provided in the pressure applying cylinder, and the pump is controlled by a liquid level detection signal from the liquid level sensor. It is possible to detect the increase / decrease in the amount sharply and to exhibit excellent effects such as being able to be reflected in the control of the pump.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  An embodiment of the present invention will be described with reference to FIG. In FIG. 1, the same components as those shown in FIG.

  The present invention mainly includes a screw press 10 and a stock solution supply device 20, and the structure of the screw press 10 is substantially the same as the screw press 10 shown in FIG.

  The stock solution supply device 20 will be described.

  A stock solution supply pipe 6 communicated with the screw press 10 is connected to a stock solution reservoir (mixing tank) 30, and a stock solution supply line 26 is connected to the stock solution reservoir 30. A condensed liquid supply line 27 is connected to a required position of the raw liquid supply line 26, and a raw liquid supply pump 28 and a condensed liquid supply pump 29 are provided in the raw liquid supply line 26 and the condensed liquid supply line 27, respectively. The stock solution 38 stored in the stock solution reservoir 30 is stirred by a stirrer 40.

  A pressure applying cylinder 31 having a required diameter, that is, a required cross-sectional area, is erected on the upper surface of the stock solution reservoir 30. As the height of the pressure applying cylinder 31, for example, about 1 m to 2 m is selected.

  A pneumatic load line 32 is connected to the upper end of the pressure addition cylinder 31, and a supply pressure adjusting valve 33 and a variable throttle valve 34 are provided in the pneumatic load line 32. A lower liquid level sensor 35 is provided at a predetermined position of the pressure applying cylinder 31, and an upper liquid level sensor 36 is provided above the lower liquid level sensor 35. As the liquid level detection sensor, various sensors such as a contact contact type, a photoelectric type, and a capacitance type can be used.

  The liquid level detection signals of the lower liquid level sensor 35 and the upper liquid level sensor 36 are input to the control unit 37, and the control unit 37 is based on the signals from the lower liquid level sensor 35 and the upper liquid level sensor 36. ON / OFF control of the stock solution supply pump 28 and the aggregate solution supply pump 29 is performed.

  Hereinafter, the operation will be described.

  The stock solution supply pump 28 of the stock solution supply line 26 and the aggregate solution supply pump 29 of the aggregate solution supply line 27 are driven to supply the treatment solution with the flocculant (stock solution) to the stock solution reservoir 30. The undiluted liquid supply pump 28 and the condensed liquid supply pump 29 are driven by constant rotation control, and a substantially constant flow rate is discharged although it depends on the pressure fluctuation on the discharge side. The liquid level of the stock solution 38 in the stock solution reservoir 30 is located between the lower liquid level sensor 35 and the upper liquid level sensor 36.

  The inside of the stock solution reservoir 30 is pressurized by the pneumatic load line 32. When the pressure in the stock solution reservoir 30 becomes equal to or higher than a predetermined pressure, the supply pressure adjusting valve 33 is actuated to close the pneumatic load line 32, and the supply of compressed air is stopped. If this happens, the supply pressure adjusting valve 33 is opened and compressed air is supplied. Thus, the stock solution reservoir 30 is maintained at a predetermined pressure.

  The stock solution 38 is stirred by the stirrer 40, and the condensation of solids in the stock solution is promoted by the flocculant.

  Due to the pressurization in the stock solution reservoir 30, the stock solution 38 is supplied into the cylindrical screen 1 through the stock solution supply pipe 6, and is driven by the motor 21 through the drive sprocket 22, the chain 19, and the driven sprocket 18. Then, the screw 2 is rotated, and the stock solution 38 is moved to the downstream side, that is, rightward in the figure by the rotation of the screw blade 3. As the stock solution 38 moves downstream in the cylindrical screen 1, the moisture is filtered, the state changes, and a solid cake is formed.

  The presser 12 is pressed against the outlet flange 9 to provide resistance to movement of the stock solution 38, and the volume of the space 15 between the screw blades 3 decreases toward the downstream side to compress the stock solution 38. The The liquid is separated and filtered and falls to the filtrate receiver 7, and the solid is discharged from the outlet flange 9 as a cake and falls from the cake outlet 14.

  Due to the rotation of the screw 2, the volume of the space 15 at the most upstream part increases and decreases, the pressure of the space 15 fluctuates greatly, and the inflow flow rate into the space 15 also fluctuates with the pressure fluctuation. As described above, since the stock solution supply pump 28 and the coagulated solution supply pump 29 are under constant rotation control, fluctuations in the amount of flow into the space 15 appear as changes in the liquid level of the stock solution 38.

That is, when the pressure in the space 15 increases, the liquid level rises, the liquid head pressure rises, and the delivery pressure of the stock solution 38 increases by the increase in liquid head pressure. There is a change of about 0.1 to 0.2 kg / cm ² due to the change of the liquid level in the pressure applying cylinder 31. Since the stock solution supply pressure to the screw press 10 is approximately 0.5 kg / cm ² , a sufficient amount of change can be obtained. Accordingly, when the pressure in the uppermost stream space 15 increases, the supply pressure of the stock solution 38 to the space 15 also increases. By increasing the supply pressure, the supply of the stock solution 38 that has become difficult to supply due to the increase in the pressure of the space 15 is promoted.

  If the supply amount from the stock solution supply line 26 and the coagulated solution supply line 27 continues to be larger than the supply amount from the stock solution supply pipe 6 to the screw press 10, the liquid level of the stock solution 38 is determined by the upper liquid level sensor. Reach 36. When the upper liquid level sensor 36 detects the liquid level, it is output to the control unit 37 as an upper limit liquid level signal, and the control unit 37 stops the stock solution supply pump 28 and the aggregate liquid supply pump 29.

  When the stock solution 38 is continuously supplied to the screw press 10 after the stock solution supply pump 28 and the aggregate liquid supply pump 29 are stopped, the liquid level of the stock solution 38 is lowered. The liquid level reaches the lower liquid level sensor 35, the lower liquid level sensor 35 detects the liquid level, and is output to the control unit 37 as a lower limit liquid level signal. The control unit 37 includes the raw liquid supply pump 28, the The aggregate liquid supply pump 29 is driven.

  Thus, in the present invention, when the pressure in the space 15 increases, the supply pressure of the stock solution 38 increases, and the supply amount of the stock solution is suppressed from decreasing.

  The relationship between the pressure in the space 15 and the supply amount of the stock solution 38 is schematically shown in FIG. As shown in the figure, even if the pressure in the space 15 fluctuates, the fluctuation in the supply amount of the stock solution 38 to the space 15 is small. Accordingly, the total supply amount increases. Further, since the control of the supply pumps such as the stock solution supply pump 28 and the coagulated solution supply pump 29 of the stock solution supply apparatus 20 is ON / OFF control, the control system is remarkably simplified.

  The mode of ON / OFF control can be changed according to the distance between the lower liquid level sensor 35 and the upper liquid level sensor 36 and the size of the cross-sectional area of the pressure applying cylinder 31.

  By narrowing the interval between the lower liquid level sensor 35 and the upper liquid level sensor 36, the fluctuation of the liquid level during ON / OFF control is reduced, and the pressure fluctuation of the supply pressure is reduced.

  Further, by reducing the cross-sectional area of the pressure application cylinder 31, the fluctuation of the liquid level in the pressure application cylinder 31 with respect to the volume change of the stock solution 38 in the stock solution reservoir 30 appears to be amplified, Increase / decrease in supply pressure increases.

  If the capacity of the stock solution reservoir 30 is sufficient, the lower liquid level sensor 35 and the upper liquid level sensor 36 may be provided directly in the stock solution reservoir 30. Further, the pressure applying cylinder 31 may be connected to an accumulator in which air is sealed, and the pneumatic load line 32 may be omitted. Further, if the fluctuation of the liquid level in the stock solution reservoir 30 when the stock solution 38 is supplied to the space 15 at a constant flow rate is known in advance, the height of the pressure addition cylinder 31 is set to a fluctuation amount or more, and the lower order The liquid level sensor 35 and the upper liquid level sensor 36 may be omitted, and the control of the stock solution supply pump 28 and the aggregate liquid supply pump 29 may be omitted.

  The lower and upper liquid level sensors 35 and 36 detect the upper limit and lower limit of the liquid level. If a single liquid level sensor detects the width of the liquid level change, one liquid level sensor is used. It's okay. In addition, when a mixture of the coagulated liquid and the stock solution is supplied in advance, the number of pumps that supply the stock solution to the stock solution reservoir 30 may be one. Furthermore, the pump control is not limited to ON / OFF control, but of course, flow rate increase / decrease control is also possible.

  Further, in the above embodiment, the screw press 10 is provided in an inclined manner, but it goes without saying that the screw press 10 can be similarly implemented even when it is installed horizontally.

It is a schematic block diagram which shows embodiment of this invention. It is a schematic diagram which shows the pressure of the space of the most upstream part of a screw, and the stock solution supply amount to a screw press. It is a schematic block diagram of a prior art example. It is a schematic diagram which shows the relationship between the pressure of the space of the most upstream part of a screw, and the discharge pressure of a stock solution supply pump.

Explanation of symbols

3 Screw blade 4 Upstream end plate 5 Downstream end plate 16 Rotating shaft 21 Motor 26 Stock solution supply line 27 Condensate supply line 28 Stock solution supply pump 29 Condensate supply pump 30 Stock solution reservoir 31 Pressure application cylinder 32 Pneumatic load line 33 Supply pressure Adjusting valve 34 Variable throttle valve 35 Lower liquid level sensor 36 Upper liquid level sensor 37 Control unit 38 Stock solution

Claims (4)

  A screw press processing method, wherein the stock solution supply pressure is increased when the pressure of the stock solution supply section to the screw press increases.   A screw press; a stock solution supply device that supplies the stock solution to the screw press; the stock solution storage device that stores the stock solution; a pump that supplies the stock solution to the stock solution reservoir; and A screw press processing apparatus comprising a liquid level sensor for detecting a liquid level and configured to control the pump by a liquid level detection signal from the liquid level sensor.   A screw press; and a stock solution supply device that supplies the stock solution to the screw press, the stock solution supply device including a stock solution reservoir that stores the stock solution, and a pump that supplies the stock solution to the stock solution reservoir, the stock solution storage A screw press processing apparatus, wherein the vessel has a pressure applying cylinder extending upward, and the liquid level of the stock solution is located in the pressure applying cylinder.   The screw press processing apparatus according to claim 3, wherein a liquid level sensor for detecting a liquid level is provided in the pressure addition cylinder, and the pump is controlled by a liquid level detection signal from the liquid level sensor.

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