JP4381551B2 - Coagulation sedimentation equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coagulation sedimentation apparatus that clarifies a liquid to be treated by aggregating and precipitating suspended substances in the liquid to be treated in a precipitation tank.
[0002]
[Prior art]
The coagulation sedimentation device is a kind of sedimentation separation type water treatment device. Suspended substances contained in the liquid to be treated such as raw waste water are agglomerated and flocked with appropriate additives and suspended from the liquid to be treated. It is intended to remove substances and the like by precipitation.
[0003]
As this type of coagulating sedimentation apparatus, the one disclosed in Japanese Patent Publication No. 1-38523 is known. In the coagulation sedimentation apparatus described in this publication, a cylindrical mixing chamber for aggregating suspended substances and the like is provided in an upright state at the center of the sedimentation tank, and the object to be treated has an aggregation floc in the mixing chamber. The liquid is distributed and supplied by the distributor to the internal space of the settling tank (excluding the inside of the mixing chamber. In this specification, this internal space is referred to as “precipitation space”).
[0004]
Conventionally, a general distributor basically includes a plurality of discharge pipes that are arranged in a lower portion of the mixing chamber and extend radially. Each discharge pipe communicates with the inside of the mixing chamber, and a plurality of discharge holes are formed along the longitudinal direction of the lower portion of each discharge pipe. Since the outer end portion of the discharge pipe is closed, the liquid to be processed containing aggregated floc in the mixing chamber passes through the discharge pipe and is discharged from the discharge hole to the processing space in the precipitation tank. Further, the discharge pipe is rotated together with the mixing chamber or separately from the mixing chamber. Therefore, when the distributor is driven to rotate, each discharge hole draws a circular trajectory, and the floc-containing liquid to be processed discharged therefrom is distributed to the precipitation space.
[0005]
In the settling space in the settling tank, the aggregated floc in the liquid to be treated settles and forms a sludge layer concentrated at the bottom of the settling tank. On the other hand, the supernatant liquid rises in the upper part of the precipitation tank and flows out from the upper part of the precipitation tank as a clarified treated liquid.
[0006]
[Problems to be solved by the invention]
The above type of coagulation sedimentation equipment is used for various applications such as wastewater treatment and papermaking white water recovery, but in recent years, it has been further clarified from the viewpoint of improving the quality of various industrial products and environmental conservation. There is an increasing need for a coagulation sedimentation apparatus capable of obtaining a liquid.
[0007]
Then, this invention aims at provision of the coagulation sedimentation apparatus which can obtain the processed liquid very clarified.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, it is desirable that the upward flow generated in the settling space in the settling tank is as uniform as possible throughout the tank. However, in the conventional coagulation sedimentation apparatus, a slight disturbance occurs in the upward flow. Although this disturbance is considered to be caused by various causes, the present inventors have conducted extensive research, and as a result, the liquid to be treated discharged from the discharge hole of the distributor is not radially downward but radially outward. It was found that this was partly due to the diagonal flow toward.
[0009]
In other words, since the liquid to be treated flows radially outward from the center of the tank in the discharge pipe, the liquid to be processed discharged by the discharge holes has an inertia force acting in the radially outward direction. The liquid to be treated flows out obliquely downward. In addition, since the discharge pipe is driven to rotate, centrifugal force is also applied to the liquid to be processed, and the liquid flows further inclined outward. As described above, when the discharge flow from the discharge hole is inclined, the sludge layer at the bottom of the settling tank is created by inhibiting the formation of a uniform upward flow in the settling tank and generating a swirling flow in the settling tank. It is considered that fine particles such as suspended substances are mixed in the supernatant liquid.
[0010]
Based on the above research results, the present invention provides a precipitation tank, a mixing chamber arranged in an upright state in the precipitation tank, into which a liquid to be treated and an additive are introduced, mixed, and stirred, and the above-described covering in the mixing chamber. A discharge pipe which communicates with the inside of the mixing chamber and has a plurality of discharge holes formed along the longitudinal direction so as to distribute and supply the processing liquid to the settling space between the settling tank and the mixing chamber. A vertical baffle plate that deflects the flow of the liquid to be treated from the discharge hole downward in an adjacent position outside the tank of each discharge hole in a coagulation sedimentation apparatus including a discharge pipe that is rotatable about a central axis It is characterized by providing. Thereby, the diagonal flow of the to-be-processed liquid from a discharge hole reduces, and it contributes to formation of a uniform upward flow.
[0011]
Further, when a horizontal baffle plate extending in parallel with the discharge pipe is provided below the discharge hole, supporting the horizontal baffle plate by all or a part of the vertical baffle plate prevents an increase in the number of parts. This is preferable in order to reduce the resistance when rotating the discharge pipe.
[0012]
Further, it is effective to reduce the resistance by making the shape of the horizontal cross section of each vertical baffle plate into an arc shape having a radius of curvature from the central axis to the mounting position of the vertical baffle plate.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the coagulation sedimentation apparatus according to the present invention will be described in detail with reference to the drawings.
[0014]
FIG. 1 is a partial sectional view showing a coagulation sedimentation apparatus according to the present invention. The coagulation sedimentation apparatus 10 shown in the figure is a sedimentation tank 12 that can settle and separate suspended substances and coagulation flocs from a liquid to be treated such as raw waste water, and can take a clarified supernatant liquid as a treated liquid; It is of a type provided with a mixing chamber 14 disposed inside thereof for pre-aggregating and flocking suspended substances in the liquid to be treated. This type of coagulation sedimentation apparatus 10 can perform so-called sludge blanket type operation and slurry circulation type operation according to the characteristics of the liquid to be treated, and can treat wastewater treatment, papermaking white water recovery, DIP wastewater recovery, causticized green. It can be applied to various uses such as liquid clarification, water treatment, and inorganic precipitation washing treatment.
[0015]
The settling tank 12 in the illustrated coagulating sedimentation apparatus 10 has a tank depth of about 4000 to 5000 mm and a tank diameter of about 1500 to 30000 mm, but for these dimensions, the installation space of the settling tank, the properties and amount of the liquid to be treated It is arbitrarily set according to the above. The sedimentation tank 12 is formed by fixing a side wall 18 made of a steel plate on a foundation 16 such as concrete provided in an area installed in the coagulation sedimentation apparatus 10.
[0016]
A gantry 20 is stretched over the upper edge of the side wall of the settling tank 12. The gantry 20 is mainly used as a work space for workers during various maintenance operations. A mixing chamber 14 is suspended from the center of the gantry 20. The mixing chamber 14 has an elongated and substantially cylindrical shape, and has a total length of about two-thirds of the depth of the settling tank 12, for example. The mixing chamber 14 is fixed to the gantry 20 with its center axis aligned with the center axis of the settling tank 12. Thereby, the mixing chamber 14 is fixed upright in the settling tank 12, and a predetermined interval (space) is formed between the lower end of the mixing chamber 14 and the bottom surface of the settling tank 12.
[0017]
Connected to the upper portion of the mixing chamber 14 is an introduction pipe 24 that communicates with the liquid inlet pipe 22 that is connected to a pump outside the system. That is, in this coagulation sedimentation apparatus 10, the liquid to be treated such as raw waste water supplied through the liquid to be treated inflow pipe 22 is first introduced into the mixing chamber 14 through the introduction pipe 24. The introduction pipe 24 is provided below the liquid level in the precipitation space in the settling tank 12 and the liquid level in the mixing chamber 14 during the operation of the coagulation sedimentation apparatus 10. Thereby, generation | occurrence | production of the bubble etc. resulting from introduction | transduction of a to-be-processed liquid is prevented. The height of the liquid level in the settling space in the settling tank 12 is defined by the upper edge of the weir plate 26, and the treated liquid (supernatant liquid) in the settling tank 12 exceeds the settling plate 26 and passes through the settling tank 12. It flows out of the system from an outlet 28 formed in the side wall 18 of the outer wall.
[0018]
The mixing chamber 14 is provided with a plurality of injection nozzles 30 for injecting various additives that aggregate the suspended substances in the liquid to be processed to form a floc. As the additive to be introduced into the mixing chamber 14, a polymer flocculant or the like is used. Each injection nozzle 30 is disposed along the height direction of the mixing chamber 14. For example, one injection nozzle 30 is provided in each of the upper, middle, and lower stages of the mixing chamber 14. Further, an additive introduction pump (not shown) is connected to the injection nozzle 30, and the injection amount of the additive can be controlled for each injection nozzle 30.
[0019]
Furthermore, as shown in FIG. 1, the mixing chamber 14 has a built-in mixer 32 for mixing and stirring the liquid to be processed and the additive. The mixer 30 is composed of a hollow cylindrical body 34 that is rotatively suspended from the gantry 20 so as to be coaxial with the mixing chamber 14 and a plurality of mixer blades 36 attached to the peripheral surface thereof. The cylindrical body 34 of the mixer 32 is rotationally driven by the mixer driving device 38 placed on the gantry 20 when the coagulation sedimentation apparatus 10 is operated. Further, a center shaft 40 is inserted into the mixer cylinder 34. The center shaft 40 is also suspended from the gantry 20 while being coaxially disposed with the mixing chamber 14, and is rotationally driven by a driving device 42 placed on the gantry 20.
[0020]
A lower portion of the center shaft 40 protrudes below the lower end of the mixing chamber 14. A distributor 44 is fixed to this lower portion of the center shaft 40. The distributor 44 is basically fixed to the center shaft 40 coaxially and is disposed so as to close the lower end portion of the mixing chamber 14. The distributor 44 communicates with the inside of the rotation support 46 and supports the rotation. A plurality of (in the illustrated embodiment, four) discharge pipes 48 that extend horizontally outward in the radial direction from the outer peripheral surface of the body 46 are configured. The outer end portion of each discharge pipe 48 is closed. Further, as shown in FIG. 2, a plurality of discharge holes 50 are formed in a line along the longitudinal direction at the lowermost portion of each discharge pipe 48. During the operation of the coagulating sedimentation apparatus 10, the distributor 44 is rotated together with the center shaft 40 by the driving apparatus 42, and the liquid to be treated including the coagulation floc in the mixing chamber 14 passes through the discharge hole 50 of the discharge pipe 48 and the precipitation space in the precipitation tank 12. Discharged.
[0021]
As clearly shown in FIG. 2, in the present embodiment, a flat vertical baffle plate 52 is fixed to the lower portion of each discharge pipe 48 at a position adjacent to each discharge hole 50 and radially outside. And extends vertically downward. Due to the presence of the vertical baffle plate 52, the flow of the liquid to be processed that is radially outward and downward from the discharge hole 50 is deflected downward in the vertical direction.
[0022]
In order to ensure the effect of this deflection, it is preferable that the height (vertical length) of the vertical baffle plate 52 is long. However, since the vertical baffle plate 52 rotates together with the discharge pipe 48, if it is excessively long, There is a possibility that a swirl flow is formed in the settling tank 12 due to resistance. Therefore, it is effective that the height of the vertical baffle plate 52 is set to about 1.5 to 2 times the diameter of the discharge hole 50 because the generation of swirling flow can be prevented. Specifically, in the general coagulating sedimentation apparatus 10 having an inner diameter of the sedimentation tank 12 of 10 m, the diameter of the discharge hole 50 is 70 to 80 mm, so that the height of the vertical baffle plate 52 is preferably about 105 mm to 160 mm. is there.
[0023]
In addition, the width of the vertical baffle plate 52 needs to be equal to or larger than the diameter of the discharge hole 50, but from the viewpoint of preventing the swirling flow as described above, the outer diameter of the discharge pipe 48 is at most about the same. preferable.
[0024]
By providing the vertical baffle plate 52 having such a dimension for each discharge hole 50, the liquid to be processed from the discharge hole 50 flows substantially downward in the vertical direction. Thereby, while a uniform upward flow is formed in the sedimentation tank 12, since stirring of the sludge layer A (refer FIG. 1) of a bottom part can be prevented, it becomes possible to obtain a clear supernatant liquid. .
[0025]
Further, a horizontal baffle plate 54 is attached below each discharge pipe 48. The horizontal baffle plate 54 functions to disperse the liquid to be processed discharged from the discharge holes 50, and prevents the sludge layer A from being stirred by the liquid to be processed discharged from the discharge pipe 48. 10 contributes to the improvement of the sedimentation efficiency.
[0026]
Conventionally, the horizontal baffle plate 54 has been attached to the discharge pipe 48 with a dedicated fixture, but as shown in FIG. 2, it is fixed by using a part or all of the vertical baffle plate 52 as a fixture. Can do. As a result, an increase in the number of components can be suppressed, and an increase in resistance due to an increase in the number of components can be prevented.
[0027]
On the other hand, as shown in FIG. 1, the center shaft 40 to which the above-described distributor 44 is fixed is extended below the distributor 44 and reaches the bottom surface of the settling tank 12. A rake 56 and a cone scraper 58 that rotate together with the distributor 44 are attached to the tip of the center shaft 40.
[0028]
The rake 56 concentrates the sludge formed by aggregation flocs in the liquid to be treated discharged from the discharge pipe 48, and scrapes the sludge into the sludge extraction recess 60 at the center of the tank bottom. Thereby, the concentrated sludge layer A is formed in a region below the distributor 44 in the settling tank 12.
[0029]
The cone scraper 58 is disposed in the sludge extraction recess 60. The recess 60 is connected to a sludge extraction pipe 62 formed on the foundation 16 of the settling tank 12. The sludge extraction pipe 62 is connected to a sludge extraction pump 64 and a sludge return pump 66. For example, when the sludge blanket operation is performed, the sludge extraction pump 64 is operated based on an instruction value of an interface detector (not shown) provided in the sedimentation tank 12 to remove the concentrated sludge in the sedimentation tank 12 out of the system. By discharging, the interface height of the sludge blanket layer B is kept within a certain range. At this time, since the corn scraper 58 is rotating, the concentrated sludge in the settling tank 12 is discharged evenly. Further, when the slurry circulation type operation is performed, the sludge return pump 66 is operated based on the instruction value of the interface detector to return and circulate the sludge. On the other hand, the supernatant liquid flows out of the system from an outlet 28 provided in the upper part of the settling tank 12.
[0030]
Next, a procedure for clarifying the liquid to be treated using the above-described coagulation sedimentation apparatus 10 will be described. Here, a case where a sludge blanket type operation is performed to obtain a clear treated liquid will be described.
[0031]
First, the liquid to be processed is supplied into the mixing chamber 14 from the liquid inlet pipe 22 and the inlet pipe 24. At this time, the liquid to be processed flowing out of the liquid to be processed introducing pipe 24 first flows into the liquid receiving chamber 68 to be processed. Then, the liquid to be processed flows through the space defined by the bottom of the receiving chamber, the side wall of the receiving chamber, and the inner peripheral surface of the mixing chamber 14, and then overflows into the mixing chamber 14 from the upper part of the liquid receiving chamber 68 to be processed. Will be.
[0032]
As a result, compared to the case where the liquid to be processed is directly introduced into the mixing chamber 14 from the liquid to be processed introduction pipe 24, particles having a large specific gravity, coarse flocs, etc. settle in the mixing chamber 14 and accumulate on the bottom. Can be reduced very effectively. As a result, the processing liquid inlet of the discharge pipe 48 of the distributor 44 is prevented from being blocked, so that the processing liquid is always efficiently distributed and supplied into the sedimentation tank 12. The operating performance is improved and the clarity of the supernatant is also improved.
[0033]
For the liquid to be processed which has flowed into the mixing chamber 14 from the liquid receiving chamber 66, an additive is injected at any timing from any or all of the injection nozzles 30 provided in multiple stages. Thereby, while the effect by an additive continues for a long time, the aggregation floc with favorable sedimentation property will be formed. Then, the liquid to be processed and the additive in the mixing chamber 14 are agitated by the mixer 32 that is rotationally driven by the mixer driving device 38, and suspended substances in the liquid to be processed are aggregated to aggregate flocs (initial floc). Form.
[0034]
The liquid to be processed including the coagulation floc is supplied into the sedimentation tank 12 through the discharge hole 50 of the discharge pipe 48 from the rotation support 46 in the distributor 44 disposed at the lower end of the mixing chamber 14. Since the distributor 44 is rotationally driven by the driving device 42 during the operation of the coagulating sedimentation apparatus 10, the liquid to be treated discharged from the discharge hole 50 of the discharge pipe 48 is distributed to the precipitation space in the precipitation tank 12 while drawing a circle. Is done. In addition, as described above, the liquid to be processed that is going to flow radially outward from each discharge hole 50 is corrected downward in the vertical direction by the vertical baffle plate 52, so that the liquid is evenly distributed in the settling tank 12. An upward flow is generated, and a good sludge blanket layer B is formed above the distributor 44.
[0035]
Further, among the aggregated flocs in the liquid to be treated, those that have settled and separated in the settling tank 12 form a sludge layer A at the bottom of the settling tank 12. At the bottom of the settling tank 12, the sludge layer A is concentrated by the rake 56 and is raked into the sludge extraction recess 60 in the center of the tank, so that the sludge layer A becomes concentrated and homogeneous. Since the sludge is extracted from the concentrated sludge layer A as needed by the sludge extraction pump 64 controlled based on the support value of the interface detector, the interface height of the sludge blanket layer B is kept within a certain range.
[0036]
On the other hand, fine flocs and other fine particles are included in the upward flow, but as a result of the provision of the vertical baffle plate 52, the upward flow is uniform with very little turbulence. It is reliably captured by the large flock of the blanket layer B and removed from the upward flow. In this manner, flocs and other particles are settled and removed from the upward flow, and an extremely clear supernatant liquid rises in the precipitation tank 12 to form a clarified layer C. Then, the supernatant liquid flows out from the outlet 28 at the top of the settling tank 12 as a processed liquid.
[0037]
As mentioned above, although preferred embodiment of this invention was described in detail, it cannot be overemphasized that this invention is not limited to the said embodiment.
[0038]
For example, in the above embodiment, the vertical baffle plate 52 has a flat plate shape, but as shown by a reference numeral 53 in FIG. The arc of the horizontal cross section of each vertical baffle plate 53 has a radius of curvature that is the distance from the center of rotation (the central axis of the mixing chamber 14 or the center shaft 40) to the mounting position of the vertical baffle plate 53. By adopting such a shape, the resistance of the vertical baffle plate 53 is reduced, and the stirring action of the vertical baffle plate 53 is suppressed. This will be effective when the distributor 40 is rotated at a relatively high speed.
[0039]
【The invention's effect】
As described above, the coagulation sedimentation apparatus according to the present invention can form an ascending flow that is much more uniform and stable in the sedimentation tank than in the prior art, so that an extremely clarified treated liquid can be obtained. It is possible to greatly contribute to quality improvement of various industrial products and environmental conservation.
[0040]
In addition, since the performance of the apparatus is improved, there is an effect that the entire apparatus can be made compact.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a coagulation sedimentation apparatus to which the present invention can be applied.
FIG. 2 is a side view schematically showing a discharge pipe constructed according to the present invention.
FIG. 3 is a view showing a modification of the present invention, and is a view of a part of a discharge pipe as viewed from below.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Coagulation sedimentation apparatus, 12 ... Precipitation tank, 14 ... Mixing chamber, 16 ... Base, 18 ... Side wall, 32 ... Mixer, 40 ... Center shaft, 42 ... Drive device, 44 ... Distributor, 48 ... Discharge pipe, 50 ... Discharge Hole 52 ... Vertical baffle plate 54 ... Horizontal baffle plate

Claims (3)

In the coagulation sedimentation apparatus that clarifies the liquid to be treated by settling and separating suspended substances and coagulation flocs in the liquid to be treated in the precipitation tank,
A mixing chamber that is arranged upright in the settling tank and into which the liquid to be treated and the additive are introduced, mixed and stirred;
In order to distribute and supply the liquid to be processed in the mixing chamber to the precipitation space between the settling tank and the mixing chamber, a plurality of discharge holes are formed along the longitudinal direction so as to communicate with the inside of the mixing chamber. A discharge pipe that is rotatable about a central axis of the mixing chamber; and
With
A coagulation sedimentation characterized in that a vertical baffle plate for deflecting the flow of the liquid to be processed from the discharge hole downward in a substantially vertical direction is suspended from the discharge pipe at a position adjacent to the outside of the tank of each discharge hole. apparatus. The aggregation according to claim 1, further comprising a horizontal baffle plate extending in parallel with the discharge pipe below each discharge hole , wherein the horizontal baffle plate is supported by all or a part of the vertical baffle plate. Precipitation equipment.   The coagulation sedimentation apparatus according to claim 1 or 2, wherein a shape of a horizontal cross section of the vertical baffle plate is an arc shape having a radius of curvature as a distance from the central axis to a mounting position of the vertical baffle plate. .

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