JP2010194383A - Screen device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce necessity of installing a cleaning nozzle for removing clogging in using a wedge wire screen for a screen drum. <P>SOLUTION: This screen device comprises: a cylindrical casing 3 erected with an arbitrary direction as the axial center 3a; a cylindrical screen drum 1 erected coaxially inside the casing 3; a helical blade 2 that wraps around the outer periphery of the screen drum 1 to be brought in internal contact with the casing 3; a feeding port 4 for supplying stock solution from above the casing 3; a concentrate discharging port 5 for taking out a concentrate concentrated in the screen drum 1; a filtrate discharging port 6 for taking out a filtrate filtered in the screen drum 1. The screen drum 1 is formed of a wedge wire screen, with the slit 1a arranged in the direction of the axial center 3a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a screen device used for solid-liquid separation or concentration of various liquids.

  Conventionally, for example, there is a screen device that concentrates sludge and the like (Patent Document 1). In this screen device, a cylindrical screen drum having spiral blades wound around the outer periphery is provided at the center of a cylindrical tank provided with a stock solution supply port at the top and a concentrated slurry discharge port at the bottom. Is.

  This screen apparatus does not have a member for stirring the supplied stock solution, and the stock solution flows down along the spiral blades, and is filtered and concentrated by the entire peripheral surface of the screen drum. According to this, since the undiluted solution naturally flows down along the spiral wing by gravity, no power is required for rotating the screen drum.

  However, according to this screen device, the solid contained in the stock solution often clogs the screen, and it is necessary to remove the clogged material with a washing nozzle. Therefore, the cleaning nozzle is suspended inside the screen drum toward the inner surface of the screen drum.

By the way, although this screen device does not consider the screen drum, it is considered that various screens can be adopted. Therefore, a screen drum using a wedge wire screen can be employed based on the type of stock solution to be concentrated.
However, if the wedge wire screen is adopted without any contrivance, it is necessary to install a cleaning nozzle for removing clogging in the screen device as described above.

No. 8-10348

  Therefore, the problem to be solved by the present invention is to provide a screen device that hardly clogs when a wedge wire screen is used as a screen drum.

In order to solve the above problems, a screen device according to the present invention includes:
A cylindrical casing standing upright in an arbitrary direction, a cylindrical screen drum standing coaxially inside the casing, and a spiral wound around the outer periphery of the screen drum and inscribed in the casing A supply port for supplying the stock solution from the upper part of the casing, a concentrate discharge port for extracting the concentrate concentrated by the screen drum, and a filtrate discharge port for extracting the filtrate filtered by the screen drum,
The screen drum is formed of a wedge wire screen, and the slits are arranged in the direction of the axis.

  Preferably, the concentrate outlet and the filtrate outlet are provided with valve means for adjusting the flow rate in order to prevent and eliminate clogging of the screen drum.

  Preferably, a circulation means is provided for circulating the concentrate by supplying it to the supply port.

  The screen device according to the present invention includes a screen drum having spiral blades wound around an outer peripheral portion, the screen drum is formed of a wedge wire screen, and the slit is disposed in the axial direction of the screen drum. Therefore, the spiral blade is disposed substantially orthogonal to the slit direction.

  As a result, the solid matter contained in the undiluted solution is very rarely clogged in the slit, and the screen drum is not clogged. Therefore, according to the present invention, there is little need to install backwashing means for injecting air or water from the inside of the screen drum in order to remove clogging, and the cost and maintenance efficiency are very excellent.

It is a partial cross section front view which shows a screen apparatus. It is the figure which looked at the screen apparatus from the upper part. It is sectional drawing which shows the state in which a liquid flows down along a spiral blade. It is sectional drawing which shows arrangement | positioning of 1st-3rd embodiment of a wedge wire.

  Hereinafter, a screen device according to the present invention will be described with reference to the drawings.

  FIG. 1 is a partially sectional front view showing the screen device. FIG. 2 is a view of the screen device as viewed from above. FIG. 3 is a cross-sectional view showing a state in which the liquid flows down along the spiral blade.

  As shown in FIG. 1, the screen device includes a cylindrical casing 3 having an axis 3a. The direction of the axis 3a is an arbitrary angle in the range of 0 to 90 degrees with respect to the vertical direction. In the present embodiment, the axis 3a is in the vertical direction. Therefore, the axial center 3a of the casing 3 extends in the vertical direction. The screen device includes a cylindrical screen drum 1 standing on a coaxial core 3 a inside a casing 3. The screen device includes a spiral blade 2 wound around the outer periphery of the screen drum 1 and inscribed in the casing 3. The screen drum 1 is a wedge wire screen formed by arranging a wedge wire 10 in the direction of the axis 3a (FIG. 3), and the slit 1a extends in the direction of the axis 3a of the screen drum. .

  The screen device includes a tank 8 for storing the target liquid 7. Various liquids are applied to the target liquid 7 according to the usage situation. The screen device includes a supply port 4 for supplying a liquid to one side (upper part in the present embodiment) of the casing 3. The supply port 4 is connected to the tank 8 through a supply pipe 40. Then, the target liquid (stock solution) 7 is supplied from the tank 8 to the supply port 4 by driving the pump 42 provided in the supply pipe 40. The target liquid 7 supplied from the supply port 4 flows into the casing 3 and flows down along the spiral blade 2.

  The supply port 4 is formed by connecting a supply pipe 40 provided in a direction perpendicular to the axis 3 a to the casing 3. As shown in FIG. 2, the supply port 4 is provided with its center 4a being eccentric with respect to the casing axis 3a. Thereby, the target liquid 7 supplied from the supply port 4 can be smoothly swung in the direction of the spiral blade 2 to flow in at high speed. Further, the target liquid 7 can be introduced at a high speed by increasing the output of the pump 42.

  The screen device includes a concentrate discharge port 5 and a filtrate discharge port 6 for taking out a liquid on the other side of the casing 3 (lower part in the present embodiment). The concentrate discharge port 5 is connected to the other side of the casing 3 and takes out the concentrate (target liquid 7 flowing down along the spiral blade 2) that flows outside the screen drum 1. The filtrate discharge port 6 is connected to the other side of the screen drum 1 and takes out the filtrate flowing inside the screen drum 1 (target liquid 7 flowing into the screen drum 1).

  The concentrate discharge port 5 is connected to the tank 8 via the concentrate discharge pipe 50. The filtrate outlet 6 is connected to another tank (not shown) via the filtrate outlet pipe 60. Therefore, a part of the target liquid 7 in the tank 8 returns from the concentrate discharge port 5 to the tank 8, and the rest is processed from the filtrate discharge port 6.

  Thereby, the undiluted liquid (target liquid) 7 supplied from the supply port 4 is separated into the filtrate and the concentrated liquid on the entire peripheral surface of the screen drum 1, and the filtrate is processed as the processing liquid from the filtrate discharge port 6. The concentrated liquid is circulated from the concentrated liquid discharge port 5 as a circulating liquid. In addition, when the concentrate of a predetermined density | concentration is obtained only by letting a raw | natural solution pass in the casing 3, it processes without circulating a concentrate. It is also possible to circulate the filtrate until a filtrate with a predetermined concentration is obtained.

  The screen device includes a supply valve 41 provided in the supply pipe 40, a concentrate discharge valve 51 provided in the concentrate discharge pipe 50, and a filtrate discharge valve 61 provided in the filtrate discharge pipe 60. Each valve 41, 51, 61 adjusts the passage flow rate of each pipe 40, 50, 60. The clogging of the screen drum 1 can be adjusted by adjusting the flow rate.

  A part of the feed water 7 flows to the filtration side 6, and most of the feed water 7 passes through the surface of the screen 1 and is discharged from the discharge port 5. As a result, there is always a constant amount and a constant speed flow on the surface of the screen 1, and this flow generates a shearing force between the surface and the surface of the screen 1, thereby causing particles on the surface of the screen 1 to be clogged. It has become difficult to do.

  From the viewpoint of the processing capacity of the apparatus, it is preferable that the flow rate of the filtrate discharge pipe 60 is large. From the viewpoint of preventing clogging, it is preferable that the flow rate of the concentrate discharge pipe 50 is large as described above. Therefore, it is possible to adjust the valves 51 and 61 so as to increase the processing capacity while preventing clogging of a certain standard.

  There is a limit point at which clogging proceeds rapidly when the ratio of the flow rate of the filtrate discharge pipe 60 to the flow rate in the concentrate discharge pipe 50 exceeds a certain level. Therefore, by adjusting and circulating the valves 51 and 61 so as to be smaller than the limit point, it is possible to obtain a filtrate / concentrate having a predetermined concentration without clogging.

  Although it varies depending on the type, concentration, viscosity, temperature, flow rate, pressure, flow rate, etc. of the target liquid 7, the flow rate of the supply pipe 40 is 100%, the flow rate of the concentrate discharge pipe 50 is 70% or more, and the filtrate discharge pipe When the flow rate of 60 is 30% or less, clogging of the screen drum 1 can be reduced very much. Therefore, by continuously circulating the screen drum 1 while maintaining this flow rate, continuous operation can be performed without clogging.

  Further, when the screen drum 1 is clogged, the filtrate discharge valve 61 is closed, and the entire amount of the supply liquid 7 is caused to flow on the surface of the screen drum 1, thereby increasing the passing speed of the surface of the screen 1. Therefore, clogging can be eliminated by increasing the shearing force between the screen 1 and the surface.

  Each valve 41, 51, 61 may be a manual valve, but may also be an electric valve. The electric valve can be opened and closed by timer control or control by a sensor that detects pressure and flow velocity, and continuous operation can be achieved while clogging is periodically eliminated.

  As shown in FIG. 3, the target liquid 7 is a liquid containing solids 70 and fine particles 71. The screen drum 1 is formed by arranging a number of wedge wires 10 in parallel to form slits 1a. As described above, since the spiral blade 2 is arranged in a direction substantially orthogonal to the slit 1a (about 45 degrees or more and less than 90 degrees), the target liquid 7 flows orthogonally to the slit 1a.

  Here, only fine particles 71 smaller than the width of the slit 1a pass between the slits 1a and flow to the inside of the screen drum 1, and the solid material 70 which is substantially the same as or larger than the width of the slit 1a is a concentrated liquid. Or are clogged into the slit 1a.

The following is a summary of the behavior of the solid material 70 that causes clogging when it passes over the slit. ~ D. It is thought that either.
a. Pull into the slit 1a and exit to the filtrate side b. The slit 1a cannot get stuck (that is, clogged).
c. Bounces back on the wedge wire 10 (does not come off to the filtrate side)
d. Passes directly above the wedge wire 10 without contact

  When the target liquid 7 flows perpendicularly to the slit 1a, compared with the case where the target liquid 7 flows in parallel, b. Of the above-mentioned c. Is considered to have a high probability (that is, it is difficult to clog). This will be described below.

  It has been experimentally found that if the slit 1a is disposed in a direction perpendicular to the axis 3a, it clogs and closes in a short period of time. That is, since the directions of the spiral blade 2 and the slit 1a are parallel, the target liquid 7 flows in parallel with the slit 1a. Thereby, it is considered that the solid material 70 contained in the target liquid 7 gets into the slit 1a and easily becomes clogged while flowing along the slit 1a for a very long time and distance.

  Therefore, when the target liquid 7 was allowed to flow perpendicularly to the slit 1a and the flow rate and flow rate of the target liquid 7 were appropriately adjusted, the clogging progress speed was significantly reduced. That is, when the target liquid 7 flows perpendicularly to the slit 1a, b. The clogging probability is smaller than when flowing in parallel. This is because, unlike the case where the target liquid 7 flows in parallel with the slit 1a, the time for the solid 70 to pass over the slit 1a is very short, so it hits the wedge wire 10 and rebounds without getting stuck in the slit 1a. Conceivable.

  As described above, the solid solution containing solids is rectified by the spiral blades and flows perpendicularly to the slits, so that solids smaller than the slit width flow into the slits, while being approximately the same as or smaller than the slit width. Large solids flow while jumping through the slit or rebound even if it hits the slit, resulting in very little clogging. Therefore, there is little need to install backwashing means for injecting air or water from the inside of the screen drum 1 to remove clogging, and the cost and maintenance efficiency are very excellent. Note that clogging may be completely removed by providing backwashing means or the like. For example, the back washing means causes a fluid such as air or filtrate to flow back toward the screen drum 1 through the filtrate discharge pipe 60. At that time, it is also possible to perform continuous operation while periodically removing clogging by controlling opening / closing of the electric valve 61 based on a timer control or a sensor for detecting a predetermined pressure or flow velocity.

  Next, the arrangement of the wedge wires will be described with reference to FIG. FIG. 4A shows the first embodiment. As shown in FIG. 4A, the wedge wire 10 is arranged such that the upper surface 10 a of the wedge wire is parallel to the flowing direction 7 a of the target liquid 7. FIG. 4B shows a second embodiment. As shown in FIG. 4 (b), the wedge wire 10 is arranged to be inclined with respect to the flowing direction 7a of the target liquid 7 by an angle α so that the upper surface 10a of the wedge wire faces the inflow side 7b. FIG. 4C shows a third embodiment. As shown in FIG. 4C, the wedge wire 10 is arranged to be inclined by an angle β with respect to the flowing direction 7 a of the target liquid 7 so that the upper surface 10 a of the wedge wire faces the outflow side 7 c. An appropriate arrangement and angle can be selected and used according to the type, concentration, viscosity, temperature, flow rate, pressure, flow rate, and the like of the target liquid 7.

1 Screen Drum 10 Wedge Wire 1a Slit 2 Spiral Blade 3 Casing 4 Supply Port 41 Supply Valve 42 Pump 5 Concentrate Discharge Port 51 Concentrate Discharge Valve 6 Filtrate Discharge Port 61 Filtrate Discharge Valve 7 Target Liquid 72 Filtrate 73 Concentrate 8 tanks

Claims (3)

A cylindrical casing erected with an arbitrary direction as an axis, a cylindrical screen drum erected coaxially within the casing, and an outer periphery of the screen drum wound around the casing. A spiral blade, a supply port for supplying liquid from the upper part of the casing, a concentrate discharge port for taking out the concentrate concentrated by the screen drum, and a filtrate discharge port for taking out the filtrate filtered by the screen drum And
The screen drum is formed of a wedge wire screen, and the slit is disposed in the axial direction.   2. The screen device according to claim 1, wherein the concentrate discharge port and the filtrate discharge port include valve means for adjusting a flow rate in order to prevent and eliminate clogging of the screen drum.   The screen apparatus according to claim 1, further comprising a circulation unit that circulates the concentrated liquid supplied to the supply port.

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