JPH1147510A - Method and apparatus for clarifying aqueous slaked lime solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for obtaining an aqueous clarified slaked lime solution from an aqueous slaked lime solution with rough quality by a simple means and to provide an apparatus for the method. SOLUTION: This method for clarifying an aqueous slaked lime solution is carried out by introducing an aqueous slaked lime solution with rough quality, which is produced by dissolving slaked lime in a concentration not higher than the saturated concentration and contains non-slaked lime substances contained in the dissolved slaked lime as undissolved substances, into a first region formed by partitioning, keeping the aqueous slaked lime solution with rough quality in the first region for a prescribed duration while generating convection of the liquid flow of the aqueous slaked lime solution with rough quality by bringing the solution into collision with a static object to be hit, and flocculating the undissolved substances in the aqueous slaked lime solution with rough quality and after that, introducing the resultant aqueous slaked lime solution with rough quality into a second region partitioned separately from the first region, and precipitating and separating the flocculated undissolved substances from the aqueous slaked lime solution with rough quality to give a clarified aqueous slaked lime solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for clarifying an aqueous slaked lime solution, and more particularly, to a method and an apparatus for efficiently clarifying an aqueous slaked lime aqueous solution by simple means, especially water for tap water. TECHNICAL FIELD The present invention relates to a method for clarifying a slaked lime aqueous solution and a fining apparatus capable of preparing a clarified slaked lime aqueous solution that is optimal for pH adjustment.

[0002]

2. Description of the Related Art Slaked lime is frequently used as a pH adjusting agent for water such as water for tap water in water treatment apparatuses such as water purification plants. For example, a water purification plant generally has a pH of 7.5 to meet a water quality standard set at pH 5.8 to 8.6.
The pH is adjusted by injecting slaked lime into the tap water so that the pH becomes about 8.0.

[0003] When slaked lime is used for adjusting the pH of tap water, slaked lime is rarely converted into an aqueous slaked lime solution before, and is often slaked lime slurry. It is because the solubility of slaked lime in water
It is relatively small at 25 ° C., about 0.17% by weight, and becomes smaller as the water temperature becomes higher. Therefore, it is difficult to prepare a slaked lime aqueous solution because the solubility cannot be increased by increasing the temperature. is there. In addition, when slaked lime is injected as a clear aqueous solution, it is necessary to separate undissolved substances mainly composed of calcium carbonate contained in slaked lime, but the separation is technically and economically. Because it was often difficult. Therefore, conventionally, when slaked lime is added to water for drinking water at a water purification plant, it is premised that undissolved substances in the slaked lime aqueous solution are also removed together with other flocculated precipitates in the final flocculated precipitation step of the water to be treated. Slurry slaked lime is injected into the water to be treated before the coagulation and precipitation step.

However, in the coagulation and sedimentation treatment, the water to be treated
When H becomes high, the removal rate of the component that deteriorates the chromaticity decreases, and the coloring of the treated water may become darker or the transparency may be deteriorated. In many cases, the coagulation and sedimentation of water had an adverse effect. Therefore, although it is necessary to adjust the pH of the tap water to about 7.5 to 8.0, if the pH of the water to be treated is preferably lower from the viewpoint of the effect of the coagulation / sedimentation treatment, the final coagulation / sedimentation step and It becomes necessary to inject slaked lime into the water after the filtration step. In this case, it is necessary to completely dissolve the slaked lime and to inject a clear slaked lime aqueous solution in which there are no undissolved and undissolved substances.

Therefore, in preparing a slaked lime aqueous solution, a slaked lime aqueous solution having a concentration equal to or lower than the saturated dissolution concentration is prepared,
A method has been proposed in which undissolved substances are precipitated and separated from a slaked lime aqueous solution to obtain a clear slaked lime aqueous solution. The prepared slaked lime aqueous solution contains a non-slaked lime substance accompanying the dissolved slaked lime, mainly calcium carbonate as a non-dissolved substance,
It is a so-called crude slaked lime aqueous solution that suspends a hardly water-soluble undissolved substance (mainly calcium carbonate), while the slaked lime has a concentration below the saturation dissolution concentration, and thus slaked lime is completely dissolved in water. It is a slaked lime aqueous solution without any undissolved components.

[0006] The crude slaked lime aqueous solution completely dissolves slaked lime, and since the undissolved matter of slaked lime does not exist in the slaked lime aqueous solution, the crude slaked lime aqueous solution is compared with the super-saturated dissolved slaked lime aqueous solution prepared by the previous batch-type slaked lime aqueous solution preparation method. The amount of undissolved matter in the crude slaked lime aqueous solution prepared by this method is extremely small. Therefore, according to this method, the load on the precipitation separation device is reduced and a small-sized device can be used, so that there is an advantage that the preparation cost of the slaked lime aqueous solution is low.

[0007]

However, the calcium carbonate in the crude slaked lime aqueous solution has a relatively small amount and is suspended in the coarse slaked lime aqueous solution in the form of fine particles which are difficult to separate. It is necessary to remove undissolved substances (mainly calcium carbonate) from the slaked lime aqueous solution to obtain a clear slaked lime aqueous solution that can be poured into water for tap water.
It was a technically difficult problem. For example, even if an attempt is made to clarify the crude slaked lime aqueous solution by sedimentation separation, the undissolved substances in the crude slaked lime aqueous solution are mainly poorly sedimentable, fine particulate calcium carbonate, and have a low concentration. In order to obtain a suitable slaked lime aqueous solution, a long time is required for the sedimentation and separation step. For this reason, there is a problem that a large sedimentation separation tank is required, and the equipment cost increases. In order to remove calcium carbonate from the crude slaked lime aqueous solution, separation methods such as filtration and centrifugation can be applied in addition to the sedimentation separation method.However, filtration separation tends to cause clogging of the filtration membrane and maintenance costs are high. The centrifugal separator has the disadvantage of being bulky, has a large energy consumption, and has a high facility cost, and has the same economical disadvantage. As described above, any of the separation methods has poor economic efficiency and has a problem in practical use.

It is an object of the present invention to provide a method and an apparatus for efficiently obtaining a clear slaked lime aqueous solution from a crude slaked lime aqueous solution by simple means.

[0009]

As a result of the experiment, the present inventor has found that by gently stirring a crude slaked lime aqueous solution,
It has been found that fine calcium carbonate particles in a crude slaked lime aqueous solution aggregate to form coarse flocs. At the time of stirring, it was found that only the crude slaked lime aqueous solution had to be stirred, and for example, it was not necessary to reflux the precipitates and the like obtained in the next sedimentation / separation step. With gentle stirring,
For example, in the case where a crude slaked lime aqueous solution collides with an object to be impacted in a tank to perform convection and stirring, or stirring by a stirring blade, the stirring intensity G value (sec ⁻¹ ) is 5 to 300, preferably 10 to 10 This means gentle stirring with low stirring energy of about 100.

Therefore, in order to achieve the above object, based on the above-mentioned findings, the method for clarifying slaked lime aqueous solution according to the present invention dissolves slaked lime to a concentration equal to or lower than the saturated dissolving concentration, Introducing a crude slaked lime aqueous solution containing a non-slaked lime substance as a non-dissolved substance into the partitioned first region,
A residence / aggregation step of causing a liquid stream of the crude slaked lime aqueous solution to collide with the stationary object in the first region, causing the crude slaked lime aqueous solution to stay for a predetermined time while being convected and stirred, and to aggregate undissolved substances in the crude slaked lime aqueous solution. Then, a crude slaked lime aqueous solution is introduced into a second region separated from the first region,
A sedimentation / separation step in which the aggregated undissolved matter is precipitated and separated from the crude slaked lime aqueous solution to obtain a clear slaked lime aqueous solution.

Alternatively, in another method for clarifying an aqueous slaked lime solution according to the present invention, stirring by a rotary stirring blade is performed instead of the collision and stirring between the slaked lime aqueous solution and the object to be impacted. That is, the method comprises dissolving slaked lime to a concentration equal to or lower than the saturated dissolved concentration, and introducing a crude slaked lime aqueous solution containing a non-slaked lime substance in the dissolved slaked lime as a non-dissolved substance into the first region,
The stirring intensity G value is 5 to 3 by the rotary stirring blade in the region of
A stagnation / agglomeration step in which the crude slaked lime aqueous solution is retained for a predetermined period of time with stirring at a strength of 00 sec ^-1 to aggregate undissolved substances in the crude slaked lime aqueous solution, and then a second region separated from the first region A precipitation / separation step of introducing a crude slaked lime aqueous solution therein, sedimenting the coagulated undissolved substance and separating the same from the crude slaked lime aqueous solution to obtain a clear slaked lime aqueous solution.

The above-mentioned stirring intensity G value (sec ⁻¹ ) is generally called “velocity gradient” and is a value calculated by the following equations (1) and (2). G = ^{[(C · A · v 3)} / (2ν · V) ] ^0.5 (1) where, C: blade drag coefficient (usually, C = 1.5) A: blade area (cm ²⁾ V: stirring Tank volume (cm ³ ) ν: kinematic viscosity of liquid (cm ² / sec) v: peripheral speed of blade calculated by equation (2) v = (π · D · N) / 60 (2) where D: Blade diameter (cm) N: Blade rotation speed (rpm)

The object to be impacted referred to in the present invention may be any object that collides with the flow of the crude slaked lime aqueous solution and causes convection and agitation. For example, it may be a baffle plate, or a wall defining the first region. But it is good. The retention time, that is, the predetermined time in the present invention, is preferably 3 minutes or more and 30 minutes or less. If the residence time is shorter than 3 minutes, the probability of contact and aggregation of non-dissolved particles and the probability of contact and aggregation of non-dissolved particles and agglomerates are reduced accordingly, and aggregates of calcium carbonate particles grow. This is because it is difficult to make them. vice versa,
This is because the coagulation effect is not so high even if it is kept for 30 minutes or more. In the present invention, the fluid to be retained in the first region in the retention / aggregation step is only a crude slaked lime aqueous solution, with the exception of introducing calcium carbonate particles as seed crystals at the beginning of the step, For example, it is not necessary to reflux the precipitate precipitated in the subsequent precipitation / separation step to increase the concentration of undissolved substances. In other words, even if the concentration of the non-dissolved material is low, the coarse slaked lime aqueous solution is allowed to stay for a predetermined time while being gently stirred, so that the fine non-dissolved material particles grow into a coarse aggregate having good sedimentation. Can be.

In the present invention, utilizing the fact that calcium carbonate particles have the property of agglomerating into coarse flocs,
In the retention / aggregation step, the crude slaked lime aqueous solution is retained in the first region while convectionally flowing, and during that time, undissolved substances mainly composed of calcium carbonate particles are aggregated as flocs. Next, the floc-like undissolved material is separated in a sedimentation / separation step to obtain a clear slaked lime aqueous solution. Since the calcium carbonate, which hardly settles, is in the form of floc, sedimentation and separation is promoted in the settling / separation step, the size of the sedimentation separation tank can be reduced, and the clarity of the slaked lime solution can be improved.
Further, since it is not necessary to reflux the precipitate separated in the settling / separation step, the equipment is simplified, and there is almost no movable equipment such as for feeding a slurry-like substance, and maintenance and inspection are easy.

By performing the staying / aggregating step and the sedimentation / separation step in an atmosphere shielded from carbon dioxide gas in the atmosphere, the formation of calcium carbonate due to the reaction between carbon dioxide gas and slaked lime is prevented, and the aqueous slaked lime aqueous solution is clarified. Promotes liquefaction and avoids the loss of slaked lime. Means for shielding from carbon dioxide in the atmosphere are not particularly limited.
The first and second regions for performing the separation step can be formed in a closed structure, and further provided with a carbon dioxide gas removal tank for removing carbon dioxide in a communication pipe for communicating them with the atmosphere. .

The apparatus for clarifying a slaked lime aqueous solution according to the present invention is configured as a chamber cut off from carbon dioxide in the air.
A chamber is provided with an inlet at the lower part of the chamber, an outlet at the upper part of the chamber, and an object to be colliding located opposite to the inlet, and a crude slaked lime aqueous solution having a concentration equal to or lower than the saturated dissolution concentration is introduced from the inlet. The collision with the colliding body, the collision effect causes the room to stay for a predetermined time while convection in the room, agglomerates undissolved substances in the crude slaked lime aqueous solution, and causes the crude slaked lime aqueous solution accompanying the agglomerated undissolved substances to be drawn out from the outlet. Chamber, configured as a chamber cut off from carbon dioxide in the air, equipped with a downward flow inclined settling means, an upward flow inclined settling means in the room, introducing a crude slaked lime aqueous solution from the outlet of the stagnation chamber, A sedimentation separation chamber which separates the aggregated undissolved material from the crude slaked lime aqueous solution by sedimentation by the downward slanting sedimentation means and then by the upward slanting sedimentation means to obtain a clear slaked lime aqueous solution. It is characterized.

The object to be impacted may be any object that collides with the flow of the crude slaked lime aqueous solution and generates convection. For example, when an inlet is provided at the bottom of the stagnation chamber, a baffle plate is provided at the inlet. In the case where an inlet is provided below the side wall of the stagnation chamber, the other side wall opposing the inlet is used as the object to be impacted. There are no restrictions on the shape of the stagnation chamber,
A general hexahedral shape may be used, and the bottom may be a conical shape or a pyramid shape. Also, in the present invention, by providing an inlet for the crude slaked lime aqueous solution at the bottom plate or the lower part of the side wall of the stagnant agglomeration chamber and providing an outlet at the upper part of the stagnant agglomeration chamber, effective convection and agitation of the slaked lime aqueous solution can be achieved. By causing a phenomenon of agglomeration of the dissolved substance, a coarse aggregate of the non-dissolved substance is generated, and a high-concentration slurry state of the non-dissolved substance that facilitates the sedimentation and separation at the subsequent stage can appear.

In the present invention, preferably, a partition having a mesh structure is provided in a region where the direction of flow of the slaked lime aqueous solution from the downward slanting sedimentation means to the upward slanting sedimentation means is changed. Among the aggregates settled and separated by the downflow inclined sedimentation means, aggregates accompanying the slaked lime aqueous solution can be captured by the network structure, and sedimentation and separation in the sedimentation separation chamber can be promoted.

In a preferred embodiment of the present invention, in the sedimentation separation chamber, the downward-flow inclined sedimentation means is disposed along the central longitudinal direction of the sedimentation separation chamber, and the upward-flow inclined sedimentation means is connected to the downward-flow inclination sedimentation means. A vibrating device for vibrating the upflow inclined settling means is provided on at least one of the side walls of the settling separation chamber in contact with the upward flow inclined settling means on both sides of the sedimentation separation chamber. Have been. In the upward slanting sedimentation means, although the flow direction of the slaked lime aqueous solution and the sliding direction of the agglomerates are opposite to each other, the undissolved matter agglomerates in the slaked lime aqueous solution adhere to the upward slanting sedimentation means with weak adhesion. Because
It can be easily peeled off by vibration. Then, the upward slanting sedimentation means and the like are vibrated by the vibrating device to separate and agglomerate the agglomerate from the upward slanting sedimentation means, thereby preventing clogging of the upward slanting sedimentation means and the like.

[0020]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Example 1 of a device for clarifying a slaked lime aqueous solution This embodiment is one of the embodiments of a device for clarifying a slaked lime aqueous solution according to the present invention, and FIGS. 1 is a partially broken plan view of the fining device, a vertical cross-sectional view taken along a line AA in FIG. 1, a cross-sectional view taken along a line BB in FIG. 1, a vertical cross-sectional view taken along a line CC in FIG. 2 view bb
FIG. Note that FIG. 1 is a partially cutaway plan view taken along the line aa in FIG. 2, and the right side of FIG. An apparatus for clarifying a slaked lime aqueous solution 10 of the present embodiment (hereinafter simply referred to as an apparatus 10) is an apparatus for removing undissolved substances from a crude slaked lime aqueous solution to obtain a clear slaked lime aqueous solution, as shown in FIG. Is formed in a single rectangular parallelepiped closed container 12 and has a stagnant aggregation portion 1 on the left side.
4 and a settling / separation unit 16 on the right side.

As shown in FIGS. 1 to 3 and 5, the stagnation unit 14 is formed as a part of the container 12 as one chamber separated from the sedimentation / separation unit 16 and has a lower part. As shown in FIG. 3, the inlet 1 is formed in an inverted quadrangular pyramid shape, and introduces a crude slaked lime aqueous solution (hereinafter simply referred to as slaked lime aqueous solution as long as it does not cause confusion) into the stagnant aggregation unit 14.
8 is provided at the bottom, and a disc-shaped collision plate 20 for causing the liquid flow of the slaked lime aqueous solution introduced from the introduction port 18 to collide with the introduction port 18, and an outlet 19 is provided at the top. In addition, a drain nozzle 2
2 are provided. The residence time of the slaked lime aqueous solution in the retention aggregation part 14 is about 5 minutes. In addition, the collision plate 20 is connected to the inlet 1
8 is located at a position relatively close to 8, and in this embodiment,
The distance between the collision plate 20 and the inlet 18 is about 1/10 of the liquid level of the stagnant agglomerated portion 14. In addition, the inlet 18
The flow rate of the slaked lime aqueous solution at the above is about 1 m / sec.
Instead of providing the collision plate 20, as shown in FIG.
The introduction pipe 21 for the crude slaked lime aqueous solution is connected to the bottom plate 2
The slaked lime aqueous solution flowing from the introduction pipe 21 may collide with the bottom plate 23 by being attached downward so as to face 3.

As shown in FIGS. 1 to 4, a distribution pipe 24 for guiding the slaked lime aqueous solution to the sedimentation / separation unit 16 extends from the outlet 19 on the upper part of the stagnation unit 14 along the longitudinal direction of the center of the upper part of the sedimentation / separation unit 16. It is provided. The distribution pipe 24 is formed of a half-split pipe body whose upper part is opened, and has a large number of distribution holes 26 arranged at equal intervals on both sides of the pipe wall. In addition, the distribution pipe 24 does not need to be a half-split shape, and may be a tube itself. The flow rate of the slaked lime aqueous solution in the distribution pipe 24 needs to be a flow rate that does not destroy the undissolved matter that has become a coarse aggregate, for example, 0.05 m / sec.
The slaked lime aqueous solution flows through the distribution pipe 24 from the outlet 19 of the stagnation and agglomeration section 14, and extends over the entire length of the sedimentation and separation section 16 at a substantially uniform flow rate from the distribution hole 26 as shown by the arrow in FIG. Left and right.

As shown in FIGS. 2, 4 and 5, the settling / separation unit 16 includes a downward slant settling unit 28 for flowing slaked lime aqueous solution in a downward slant flow, and an upward slant flow for slaked lime aqueous solution in upward slant flow. An inclined settling unit 30, an inverting unit 32 for inverting the flow of the slaked lime aqueous solution from a downward flow to an upward flow, and an inverting unit 32
And a sediment hopper 34 provided below the hopper. As shown in FIG. 5, the downflow inclined settling section 28 extends along the central longitudinal direction of the settling / separation section 16, and the upward flow inclined settling sections 30 </ b> A and 30 </ b> B have the downflow inclined It extends on both sides of the settling portion 28 over its entire length.

The downward-flow inclined settling section 28 and the upward-flow inclined settling sections 30A and 30B are inclined flow paths each having a honeycomb-shaped cross-section as shown in FIG. It is constituted by a body 31. Inclined channel body 31
Is an aggregate formed by arranging a large number of corrugated formed plates 31a having a continuous trapezoidal cross section as shown in FIG. Or in the cross section in a direction perpendicular to the flow path, the hollow portion is shown in FIG.
Molded body 31b formed into a honeycomb shape shown in FIG.
It consists of. The corrugated plate 3 shown in FIG.
Many flat plates may be arranged in place of 1a. In the present embodiment, the downward slanting sedimentation section 28 and the upward slanting sedimentation means 30
Each of them is constituted by an inclined channel body having a trade name of Olpack having the same configuration as that shown in FIG. 8B, and each of them is inclined downward by about 60 ° with respect to a horizontal plane from the left hand to the right hand in FIG. It is arranged. In the present embodiment, the inclined flow path body is arranged such that the flow path is inclined downward from the upper left to the lower right in FIG. 2, but in the opposite direction, the flow path is shifted from the upper right to the lower left. May be arranged so as to be inclined downward. Further, in the upward slanting sedimentation sections 30A and 30B, most of the agglomerates are settled and separated in the downflow slanting sedimentation section 28 in the preceding stage. May be smaller than the cross-sectional area of the downflow inclined settling section 28.

As shown in FIG. 4, the reversing section 32 is located below the downflow inclined settling section 28 and the upflow inclined settling sections 30A and 30B. Settling part 3
The extended portion 38 of the partition wall 36 that partitions 0A and B has a mesh structure. The mesh structure has a mesh size of 5 mm, for example.
Use a synthetic resin net. Below the reversing part 32,
As shown in FIG. 2 to FIG. 5, the precipitate hopper 34
It has become. The sediment hopper 34 is formed in an inverted quadrangular pyramid shape, and a siphon type sediment extraction nozzle 40 is provided at the bottom thereof.

As shown in FIGS. 1 and 4, on the upper part of each of the upward slanting sedimentation sections 30A and 30B, as shown in FIGS. Hereafter, it is called a clearing slaked lime aqueous solution).
2A and 2B are provided along the longitudinal direction of the upward-flow inclined settling portions 30A and 30B. Each of the water collecting gutters 42A and 42B is a rectangular tubular body, and a water collecting hole 44 for allowing a clear slaked lime aqueous solution to flow in from the upward slanting sedimentation part 28 is provided at the bottom thereof. As shown in FIG. 1 and FIG.
Each is connected to outflow chambers 46A and 46B provided on both sides of the distribution pipe 24 of the stagnant aggregating section 14, respectively. Outflow chamber 4
Outlet nozzles 48A and 48B are provided in 6A and 6B, respectively, and are connected to a slaked lime aqueous solution feed pipe (not shown) for sending a clear slaked lime aqueous solution.

An air communication pipe 51 having a carbon dioxide gas removing tank 50 filled with a carbon dioxide gas removing agent 52 is provided on the ceiling wall of the container 12 to allow air to flow into and out of the container 12.
It is provided as shown in FIGS. Atmospheric communication pipe 5
By providing a carbon dioxide gas removal tank 50 in
Prevents the formation of calcium carbonate in the interior, and minimizes the suspension of clear slaked lime solution and the loss of slaked lime. As the carbon dioxide removing agent 52, granular slaked lime, granular sodium hydroxide, or the like is used.

Hereinafter, the apparatus 1 will be described with reference to FIGS.
The function of each part constituting the zero and the behavior of the slaked lime aqueous solution in the apparatus 10 will be described, and the implementation of the method of the present invention will also be described. The slaked lime aqueous solution is supplied from the inlet
And collides with the collision plate 18 as shown in FIG.
The inflow energy of the slaked lime aqueous solution is diffused, and the stream lines of the slaked lime aqueous solution flow are also dispersed so as not to form a linear upward flow. Thereby, a convection of the slaked lime aqueous solution is generated in the stagnant agglomerated portion 14.

Due to the gentle stirring effect of the convection, fine particulate non-dissolved substances having poor sedimentation in the slaked lime aqueous solution, mainly calcium carbonate particles, come into contact with each other and grow into flocculated flocs having a large particle size. Due to such a phenomenon that the undissolved particles are included in the flocculated floc, a coarse floc having good sedimentation properties is obtained. The agglomerates together with the slaked lime aqueous solution accumulate convectively in the stagnant aggregating section 14, and the slaked lime aqueous solution becomes a high-concentration slurry having a high non-dissolved substance concentration. Retention aggregation section 14
While the high-concentration slurry is slowly convectively stirred by the inflow energy of the slaked lime aqueous solution that continuously flows into the slaked lime aqueous solution, fine undissolved substances in the slaked lime aqueous solution that has flowed in come into contact with the high-concentration slurry and form coarse agglomerates. To form In this way, the undissolved matter, that is, calcium carbonate particles, becomes coarse aggregates.

At the beginning of the operation, there is no high-concentration slurry of undissolved material in the stagnant agglomeration section 14, but after the operation is started,
Over time, the undissolved material gradually accumulates and accumulates, reaching a steady state at concentrations ranging from 0.5 to 3%. At the beginning of the operation when the high-concentration slurry is not formed, the calcium carbonate concentration is set to about 0.1% in advance,
It is desirable to add calcium carbonate powder as a seed crystal.

The aqueous slaked lime solution in which the coarse aggregates are suspended is supplied from the outlet 19 above the stagnation aggregate 14 to the distribution pipe 24.
The sediment is further distributed to the left and right at a uniform flow rate over the entire length in the longitudinal direction of the sedimentation / separation part 16 via the distribution hole 26, and is introduced into the sedimentation / separation part 16. As shown in FIG. 3, the slaked lime aqueous solution first passes through the downflow inclined settling section 28 in a downward flow, and then passes through the partition wall extending section 38 having a mesh structure while diverging right and left at the inversion section 32. Then, the flow is reversed and passes upward through the upward-flow inclined settling section 30.

Most of the agglomerates agglomerated in the stagnant agglomeration section 14 are trapped by the first downflow inclined settling section 28, which settles and adheres to the wall of the inclined flow path body. When the amount of sedimentation of the aggregate on the wall of the inclined channel body increases, the aggregate is separated from the wall of the inclined channel body, and the downward slanted sedimentation section 2
8 slides down with the flow of the slaked lime aqueous solution. Due to the sliding-down phenomenon, excessive downward sedimentation of agglomerates does not occur in the downward-flow inclined settling section 28, and the inclined flow path body is not blocked.

The slaked lime aqueous solution that has passed through the downflow inclined settling section 28 passes through the network structure of the partition wall extension section 38 while changing the direction of the flow from the downflow to the upflow at the inversion section 32, and then flows upward. It flows into the inclined settling parts 30A and 30B. When the slaked lime aqueous solution passes through the network structure, the remaining agglomerates and fine particles that have not been captured in the downward-flow inclined settling section 28 come into contact with the network of the partition wall extension section 38 and are attached and captured. The agglomerates attached to the mesh trap other agglomerates and fine undissolved substances in the slaked lime aqueous solution and further enlarge. Most of the agglomerated agglomerates will fall off and fall, but the rest will grow further and block the mesh. When the mesh is clogged, the flow rate of the slaked lime aqueous solution passing through the mesh structure is increased, and a part of the aggregate that has adhered and grown on the mesh is peeled off, and the upward slant settling portion 30
Accompany with A and B. The entrained agglomerates are again adhered and captured on the walls of the inclined flow path bodies of the upward flow inclined settling sections 30A and 30B,
Then, it slides down against the flow of the slaked lime aqueous solution.

The slaked lime aqueous solution in which the undissolved matter is captured and clarified flows into the collecting troughs 42A, B from the collecting hole 44, and is sent from the outlet nozzles 48A, B via the outflow chambers 46A, B. On the other hand, the separated undissolved material is the precipitate hopper 34
, And are discharged intermittently from the precipitate discharge nozzle 40.

Modified Example 1 of Embodiment 1 This modified example is a modified example of the embodiment, in which gradual mechanical forced agitation is performed in place of the convection agitation due to the collision between the slaked lime aqueous solution flow and the impingement plate of the first embodiment. Here is an example. In this modification,
As shown in FIG. 6, the paddle type stirrer 6
0 is provided. If the stirring intensity is high, the grown coarse aggregates are broken and return to fine particles again. Therefore, the peripheral speed at the tip of the stirring blade is set to 5 m / min or less. In this modification,
In order to keep the concentration of the non-dissolved substance in the stagnation section 14 high, as in the first embodiment, the inlet 62 is located at the lower part
A lead-out port 64 connected to the fourth port 4 is provided at the upper part.

In the modified example 2 of the first embodiment , the flow direction of the slaked lime aqueous solution does not coincide with the falling direction of the agglomerate in the partition wall extension part 38 and the upward flow part inclined settling parts 30A, B of the network structure of the apparatus 10. For this reason, the aggregates may not peel off smoothly and do not slide down. By the way, in the apparatus 10, the aggregates are formed with the mesh of the partition wall extension part 38 and the inclined flow path body of the upwardly flowing part inclined sedimentation parts 30A, B with a strong adhesion strength that requires chemical cleaning like a normal scale. Instead of adhering to a wall or the like, it is attached so as to hang with a weak adhesive force. Therefore, by applying weak vibration to the wall of the inclined flow path body or the mesh structure of the partition wall extension 38, the aggregate can be easily separated. Therefore, this modification example 2
Then, as shown in FIGS. 1 and 4, the vibration device 66 is attached to the side wall of the container 12, several times a day, for several seconds to several seconds.
By operating it for ten and several seconds to vibrate the upward-flow inclined settling part 30 and the like, the attached aggregates are dropped and the accumulation of aggregates is prevented. The effect of the vibrating device 66 is further enhanced when linked with the operation of pulling out the sediment in the sediment hopper 34. The vibrating device 62 is a known device, and may be a commercially available type such as an electric type or a pneumatic type. As shown in FIG. 1, the mounting position is effective at the center of both side walls. If the device is small, only one of the side walls may be used. If the device is large, two or more devices are mounted on both side walls.

Embodiment 2 This embodiment is another embodiment of the apparatus for clarifying an aqueous slaked lime solution according to the present invention. As shown in FIG. 7, the slaked lime aqueous solution clarification device 70 of this embodiment includes
And a plurality formed separately from the stagnant aggregation section 72 (FIG. 7).
In this case, three sedimentation / separation sections 74A, B, and C are shown as an example).
A stagnant aggregation section 72 and a sedimentation separation section 74A,
B and C are connected by pipes 76A, 76B and 76C, respectively. In the case where the flow rate of the slaked lime aqueous solution is large and the apparatus becomes large, the present embodiment is preferably adopted in consideration of various conditions of manufacturing, transportation and installation.

[0038]

According to the constitution of the method of the present invention, the crude slaked lime aqueous solution is allowed to stay for a predetermined time while being gently stirred, so that the non-dissolved material mainly composed of calcium carbonate particles, which hardly settles, is brought into contact with and coarsened. As a result, a method for clarifying an aqueous slaked lime aqueous solution, in which the sedimentation and separation at the subsequent stage is made more efficient, is realized. Further, according to the configuration of the apparatus of the present invention, an apparatus capable of efficiently performing the method for clarifying the slaked lime aqueous solution is realized by a simple mechanism having almost no movable parts.

[Brief description of the drawings]

FIG. 1 is a partially broken plan view of an embodiment of an apparatus for clarifying a slaked lime aqueous solution according to the present invention.

FIG. 2 is a longitudinal sectional view taken along the line AA of FIG.

FIG. 3 is a cross-sectional view taken along a line BB in FIG. 1;

FIG. 4 is a longitudinal sectional view taken along the line CC of FIG. 1;

FIG. 5 is a transverse sectional view taken along line bb in FIG. 2;

FIG. 6 is a longitudinal sectional view of a stagnant agglomerated portion according to a modification 1 of the first embodiment.

FIG. 7 is a plan view of Embodiment 2 of the clarification apparatus for slaked lime aqueous solution according to the present invention.

FIGS. 8A and 8B are perspective views each showing a structure of an inclined flow path body.

FIG. 9 is a vertical cross-sectional view of a main part of a stagnant agglomeration portion in an example in which a stationary plate is used as a stationary plate instead of a collision plate.

[Explanation of symbols]

10 Example of a device for clarifying a slaked lime aqueous solution according to the present invention 12 Closed container 14 Retention aggregation part 16 Sedimentation separation part 18 Inlet 19 Outlet 20 Collision plate 21 Inlet pipe 22 Drain nozzle 23 Bottom plate 24 minute pipe 26 Distribution hole 28 Downward Flow inclined sedimentation part 30 Upflow inclined sedimentation part 31 Inclined channel body 32 Reversal part 34 Precipitate hopper 36 Partition wall 38 Partition wall extension part of network structure 40 Precipitate extraction nozzle 42 Water collecting gutter 44 Water collecting hole 46 Outflow chamber 48 Outlet Nozzle 50 Carbon dioxide removal tank 51 Atmospheric communication pipe 52 Carbon dioxide removal agent 60 Stirrer 62 Inlet 64 Outlet 66 Exciting device 70 Example 2 of the apparatus for clarifying slaked lime aqueous solution according to the present invention 72 72 Remaining aggregation part 74 Sedimentation separation part 76 Piping

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[Procedure amendment]

[Submission date] July 27, 1998

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

Continued on the front page (72) Inventor Hiroo Yoshida 5-5-16-1 Hongo, Bunkyo-ku, Tokyo Organo Corporation

Claims (6)

[Claims] 1. A method for dissolving slaked lime to a concentration equal to or lower than a saturated dissolving concentration and introducing a crude slaked lime aqueous solution containing a non-slaked lime substance in the dissolved slaked lime as a non-dissolved substance into a first region partitioned, In the region, the liquid flow of the crude slaked lime aqueous solution collides against the stationary object to be convected, and the crude slaked lime aqueous solution is convected, and is retained for a predetermined time while being stirred, and a residence / aggregation step of aggregating undissolved substances in the crude slaked lime aqueous solution, A crude slaked lime aqueous solution is introduced into a second region separated from the first region, and aggregated undissolved matter is precipitated and separated from the crude slaked lime aqueous solution to obtain a clear slaked lime aqueous solution. A method for clarifying a slaked lime aqueous solution, comprising a separation step. 2. A method for dissolving slaked lime to a concentration equal to or lower than a saturated dissolving concentration and introducing a crude slaked lime aqueous solution containing a non-slaked lime substance in the dissolved slaked lime as a non-dissolved substance into the first region, A residence / aggregation step in which the crude slaked lime aqueous solution is retained for a predetermined time while being stirred at a strength of 5 to 300 sec ^-1 as a stirring intensity G value by a rotary stirring blade in the region, and an undissolved substance in the crude slaked lime aqueous solution is aggregated; A crude slaked lime aqueous solution is introduced into a second region separated from the first region, and aggregated undissolved matter is precipitated and separated from the crude slaked lime aqueous solution to obtain a clear slaked lime aqueous solution. A method for clarifying a slaked lime aqueous solution, comprising a separation step. 3. The method for clarifying a slaked lime aqueous solution according to claim 1, wherein in the precipitation / separation step, undissolved substances are precipitated and separated by a gradient sedimentation separation method. 4. A chamber which is configured as a chamber shielded from carbon dioxide in the air, and has an inlet at a lower portion of the chamber, an outlet at an upper portion of the chamber, and a collision object located opposite to the inlet in the room, respectively. A crude slaked lime aqueous solution having a concentration equal to or lower than the saturated dissolved concentration is introduced from the inlet and collides with the object to be impacted, and due to the collision effect, the undissolved substance in the crude slaked lime aqueous solution is retained for a predetermined time while convection in the room, A stagnant coagulation chamber for drawing out a crude slaked lime aqueous solution accompanied by coagulated undissolved matter from an outlet, and a chamber shielded from carbon dioxide gas in the air, comprising a downflow inclined settling means and an upward flow inclined settling means. Provided in the room, a crude slaked lime aqueous solution was introduced from the outlet of the stagnant agglomeration chamber, and the aggregated undissolved matter was precipitated by the downward slanting sedimentation means, and then precipitated by the upward slanting sedimentation means and separated from the crude slaked lime aqueous solution, Qing Characterized in that it comprises a sedimentation separation chamber so as to obtain a slaked lime aqueous solution, clarification device of slaked lime aqueous solution. 5. The slaked lime according to claim 4, wherein a partition wall having a mesh structure is provided in a region where the direction of flow of the slaked lime aqueous solution from the downflow inclined settling means to the upward flow inclined settling means is changed. Aqueous solution clarifier. 6. The sedimentation separation chamber, wherein the downflow inclined settling means is disposed along the central longitudinal direction of the sedimentation separation chamber, and the upward flow inclined settling means is provided on both sides of the downward flow inclined settling means. A vibrating device configured to vibrate the upwardly inclined settling means is provided on at least one of the side walls of the settling separation chamber in contact with the upwardly inclined settling means, which is configured in a planar arrangement arranged along the settling means. The apparatus for clarifying a slaked lime aqueous solution according to claim 4 or 5, wherein