JP4909191B2 - Fluid agitation method - Google Patents

Description

  The present invention relates to a fluid stirring method and an arm rotary sparger.

  A wet desulfurization apparatus is generally used as a desulfurization apparatus for coal-fired desulfurization exhaust gas and the like. In wet desulfurization equipment, SO2 in exhaust gas is absorbed in a slurry solution containing alkali such as lime, and oxygen-containing gas (generally air) is blown into the resulting sulfite ions to effect contact oxidation to sulfate. Processing to change is made.

  A rotary air sparger [ARS] is known as an agitating member that efficiently blows air into a slurry solution that has absorbed exhaust gas and makes gas-liquid contact efficiently (see, for example, Patent Document 1).

As shown in FIG. 9, the ARS has a hollow rotary shaft 91 connected to a motor 93 via a speed reducer 92 at the ceiling, and is rotatable in the direction of the arrow. The reduction gear 92 and the hollow rotary shaft 91 are interlocked via a gear (not shown). The air 95 from the air source 94 is ejected from the air nozzle 98 via the pipe 96, the hollow rotary shaft 91 and the branch pipe 97, and is sheared with the flow generated in the solution by the rotation of the hollow rotary shaft 91 by the motor 93. The fine bubbles 99 are dispersed and mixed in the liquid.
Japanese Patent Laid-Open No. 5-220363

  When a plurality of stirring members (for example, ARS) are arranged and rotated in the fluid in the tank, the ARS is caused by the rotation of the stirring members themselves, the mutual interference of the fluid force with the adjacent stirring members or walls, and the like. When an unbalance fluctuation load called a lateral load is significantly received and exceeds a predetermined value, the gear of the speed reducer 92 may cause one-sided contact and may be damaged.

  Moreover, in the conventional design, the same tolerance is given from the actual data of the lateral load actually measured in the past plant, and the measurement is performed with a uniform formula in any plant. However, the number of revolutions differs from plant to plant, and the conventional rotational phase is the timing at the time of startup. Therefore, when two or more ARSs are started up, a lateral load more than expected is generated due to interference with other stirrers. There is a risk.

  An object of this invention is to provide the stirring method for reducing a lateral load, and the stirring member suitable for reduction of a lateral load, without lowering the rotation speed of a stirring member in view of the said present condition.

The present invention has been made to solve the above problems. That is, the fluid agitation method according to the present invention is a fluid agitation method in a fluid tank provided with at least two agitation members having parallel rotation axes, and maintains the rotation speed of adjacent agitation members at a predetermined value. However, the rotation phase is controlled to a predetermined value at which the maximum unbalance load is minimized, and stirring is performed.
The arm rotary gas sparger according to the present invention includes a hollow rotary shaft capable of conducting gas, two or more stirring arms projecting horizontally from the hollow rotary shaft, and a branch from the hollow rotary shaft, A pipe that is attached to the arm and includes a branch pipe that takes in a part of the gas that is conducted through the hollow rotary shaft and that can be discharged simultaneously with the rotation, and at least one stirring surface of the two or more stirring arms However, the height is different from the stirring surface of the other stirring arm.
An arm rotary gas sparger according to the present invention includes a hollow rotary shaft capable of conducting gas in a vertical direction, two or more stirring arms extending horizontally from a lower end of the hollow rotary shaft, and a branch from the hollow rotary shaft. A branch pipe attached to the stirring arm, and a branch pipe capable of taking in a part of the gas conducted through the hollow rotary shaft and discharging it at the same time as rotation, and adjusting the length of the hollow rotary shaft Is something.

By the stirring method of the present invention, without reducing the rotation speed of the adjacent stirring member, it is possible to reduce the lateral load due to the rotation of the stirring member itself, the mutual interference of the fluid force with the adjacent stirring member or the wall, It is possible to suppress a decrease in the safety factor due to breakage of the rotating gear, and as a result, it is possible to improve the reliability of the entire apparatus.
By using the arm rotary sparger of the present invention, the maximum unbalance load can be reduced as compared with the case of using a conventional ARS.

Hereinafter, the present invention will be described in detail with reference to the drawings. The same members are denoted by the same reference numerals. In addition, this invention is not restrict | limited to the form demonstrated below.
The stirring method according to the present invention is suitably employed for stirring liquids, slurries and the like, particularly stirring involving aeration, performed in the presence of two or more stirring members having parallel rotation axes.
The two or more stirring members may be installed so as to be arranged in a straight line when viewed from above the fluid tank as long as the rotating shafts are arranged in parallel. It may be installed so as to form each vertex of the triangle.
The number of stirring members is not particularly limited as long as there are two or more stirring members in the same fluid tank, but the upper limit can be set to ten.
In order to maintain the rotational phase at a predetermined value, the number of rotations of the stirring member needs to be the same in all the stirring members existing in the same fluid tank.
The rotational speed of the stirring member is maintained at a predetermined value between 10 rpm and 100 rpm in consideration of various factors such as slurry viscosity, slurry density, and the degree of bubble dispersion when aeration is involved. If it is less than 10 rpm, the shearing force of the bubbles, the dispersion force of the bubbles, and the stirring force may be insufficient, and if it exceeds 100 rpm, the stirring power may be excessive and it may be difficult to maintain the mechanical strength. .

  In this specification, the term “stirring member” includes not only a stirrer having a gas-liquid contact function such as ARS disclosed in Patent Document 1, but also a turbine type, propeller type, paddle type, anchor paddle type, gate A stirrer having various impeller shapes such as a mold paddle type and a ribbon type and having a gas supply function, or a stirrer having various impeller shapes but no gas-liquid contact function is included.

The fluid agitation method according to the present invention maintains the rotational speed of adjacent agitation members at a predetermined value, and the rotational phase is set to the maximum lateral load applied to each agitation member, that is, the maximum unbalance load is minimized. The rotation is controlled to a predetermined value (optimal rotation phase).
The rotational phase refers to a surface including a specific impeller and a rotating shaft of one stirring member in two stirring members having impellers (including stirring arms and stirring blades) protruding from the same number of rotation shafts at the same angle. The angle formed by the surface including the specific impeller and the rotation axis of the other stirring member.
The optimum rotation phase varies depending on various parameters such as the interval between adjacent stirring members, the number of stirring members, the distance between the tank wall surface and the stirring member, the number of rotations of the stirring member, and the blade diameter. An optimum rotational phase can be obtained by the method.
As shown in FIG. 1, two or more strain gauges 12 are attached to the rotating shaft 11 of the stirring member 10 (the upper limit is about four). The angle θ1 formed by the lateral load detection directions x and y between the strain gauges is determined to be, for example, 90 ° so as not to be 0 ° or 180 °. By synthesizing the load applied to each strain gauge, the value and direction of the load actually applied to the rotating shaft with rotation can be measured. Since the load fluctuates with rotation, it is possible to measure the maximum value of the load, that is, the maximum unbalance load, by changing the rotation phase in various ways, and to set the rotation phase at which the maximum unbalance load is the smallest as the optimum rotation phase.

  The rotation phase of the adjacent stirring members may be set and / or held at a value other than 0 ° or 90 ° when the stirring member having four stirring blades at 90 ° intervals is rotated counterclockwise. preferable. This is because when the angle is 0 ° or 90 °, the force of the fluid caused by the rotation of the adjacent stirring members is synthesized at the same timing, and it is considered that a large load is applied to the tip of the stirring blade.

  The rotation directions of adjacent stirring members are preferably opposite to each other. Although it does not exclude rotating in the same direction, if it is in the same direction, the pressure of the fluid generated by the stirring of each stirring member is combined, which may cause a lateral load to increase.

  In the fluid stirring method according to the present invention, “controlling to the optimum rotation phase” means (1) setting the rotation phase of the adjacent stirring member to the optimum rotation phase when each stirring member is activated, and (2) rotating. Sometimes, one or both of setting or maintaining the rotational phase of the adjacent stirring members at the optimal rotational phase is intended. Therefore, the above-described control method (1) is used at the time of start-up, and a method of controlling intermittently or continuously using the above-described control method (2) when a phase shift occurs during rotation is adopted. Also good.

As a method for controlling the rotation phase of the adjacent stirring member to the above-described optimum rotation phase, a machine that sets or holds the adjacent stirring member so as to be the optimal rotation phase by using a cam, a stopper, a spring, a bearing, an inverter, or the like. Phase control method;
Use sensors, lasers, etc. to obtain information about the rotational phase difference as an electrical signal, then calculate the optimal rotational phase and set the optimal rotational phase by adjusting the motor speed or start timing, etc. The electrical phase control method etc. which do are mentioned, These control methods can also be used in combination.

One mode of the mechanical phase control method at the time of startup is shown in FIG.
In FIG. 2, a cam 22 in the same direction as the rotary blade is provided at the upper end of the rotating shaft 21 of the stirring member, and a stopper 24 that can be set to an arbitrary angle θ2 is provided on a slide 23 having the same height as the cam 22. Disclosure. When the phase of the rotor blade is adjusted before starting, the stopper 24 is pushed toward the rotating shaft, and can come to a stationary phase with a predetermined phase by contacting the cam.

One mode of the electrical phase control method at the time of startup is shown in FIG.
In FIG. 3, a rotation phase detector 32 provided on the upper part of the rotating shaft 31 of the stirring member for detecting a phase difference between adjacent stirring members, and an operation in which information on the rotation phase from the detector is input as an electric signal. , A start control device 34 to which information related to the optimal start phase calculated by the calculator is input as an electrical signal, and an electric motor 35, and using the optimal rotation phase obtained by the calculator 33 A method in which the activation control device 34 controls the activation timing of each stirring member is disclosed.

  The phase control method as described with reference to FIGS. 2 and 3 can be realized with a simple control device, and damage to the device can be prevented.

As an embodiment of the phase control method at the time of rotation, for example, a strain gauge is provided on the rotation shaft to measure the unbalance load, and the rotation phase is calculated based on the measured value so that the maximum unbalance load is minimized. Then, there is a method in which the phase is adjusted by temporarily lowering the rotational speed of any one of the stirring members, and when the phase reaches a predetermined value, the rotational speed is returned to the original value for operation.
As another embodiment of the phase control method at the time of rotation, for example, while providing a strain gauge on the rotating shaft and measuring the unbalanced load, for example, several times a day, the maximum unbalanced load is minimized. There is also a method of driving by controlling the rotation timing so that
As a result, the tip of the stirring member receives a strong force such as fluid interference, so that the rotational phase timing set at startup gradually shifts, and even if an excessive lateral load occurs, the lateral load is always applied. It is possible to quickly detect and correct the phase to a desired value.

  The stirring method according to the present invention is effective in reducing the lateral load even when a stirring member having a diameter of less than 1 m is used, but when a large stirring member having a diameter of 3 m or more is used, the adjacent stirring member is used. Or since mutual interference with a fluid tank wall surface becomes remarkable, it becomes still more advantageous. The upper limit of the diameter can be set to 10 m from the viewpoint of the mechanical strength of the impeller and the rotating shaft in addition to the stirring power.

  By adopting the stirring method of the present invention, the stirring member can be rotated without applying an excessive load while maintaining the rotation speed of the adjacent stirring member at a predetermined value as in the past. There is an advantage that the degree of freedom in designing the approach distance between the stirring members to be increased.

While examining the reduction of the lateral load, the present inventors also studied the shape of the arm rotary gas sparger itself, and simultaneously invented the arm rotary gas sparger having a unique shape.
One embodiment of the arm rotary gas sparger of the present invention is shown in FIG.
The arm rotary gas sparger 40 shown in FIG. 4 has a hollow rotary shaft 11 capable of conducting gas in the vertical direction, four stirring arms 42 extending horizontally from the lower end of the hollow rotary shaft, and a branch from the hollow rotary shaft. The pipe is attached to the stirring arm 42 and includes a branch pipe 43 that can take in a part of the gas conducted through the hollow rotary shaft and discharge it at the same time as the rotation. By changing the cylinder diameter d2 of the rotating shaft 41 to d3 in the middle and providing the joint structure 41, the length can be adjusted.
By adopting such an aspect, the stirring surface of the stirring member can be freely adjusted, and interference between adjacent stirring members can be avoided by setting the stirring surfaces of adjacent stirring members to different heights. . In this specification, the “stirring surface” is a surface perpendicular to the hollow rotation axis at the height of the tip of the stirring arm.

As another aspect of the arm rotary gas sparger according to the present invention, the arm rotary gas sparger includes a hollow rotary shaft capable of conducting gas in a vertical direction, and two or more stirring arms projecting horizontally from the hollow rotary shaft, Among them, a configuration in which at least one stirring surface is at a different height from the stirring surfaces of the other stirring arms can be employed. The above-mentioned “projecting in the horizontal direction” includes not only the case where the stirring arm extends on a plane perpendicular to the hollow rotating shaft but also the case where the stirring arm extends obliquely upward or downward.
The load applied to the tip of the stirring arm can most affect the lateral load, so changing the height of the tip with the stirring arm shifts the height of the fluid swept by the tip of the stirring arm, reducing the interference timing. be able to.

FIG. 5 shows the most preferable aspect as a configuration in which the height of the tip is changed.
In FIG. 5, two of the stirring arms projecting from the hollow rotating shaft 11 (52a, 52b) project from a height different from that of the other two stirring arms (52c, 52d). It has become.
The number of stirring arms may be four or more on the same plane perpendicular to the rotation axis, but may be less than four as shown in FIG.
When two stirring arms are provided on the same plane, the angle formed by the stirring arms on the same plane can be 180 °.
By adopting this configuration, it is possible to reduce the timing of interference with adjacent arm rotary gas spargers and adjacent walls compared to when all stirring arms are installed from the same height of the hollow rotary shaft. This makes it possible to increase the size of the agitator. In addition, there is an advantage that the degree of freedom in designing the approach distance is increased.

  As another mode of the arm rotary type gas sparger, as shown in FIG. 6, a structure in which a dummy blade 61 for reducing Karman vortex is attached to the rear edge of a conventionally known stirring arm 42, and the tip of the stirring arm 42 as shown in FIG. A configuration in which a Karman vortex reduction plate 71 is attached to the upper surface of the part may be employed.

  By adopting the arm rotary gas sparger of the present invention, the stirring member can be rotated without applying an excessive load, and there is an advantage that the degree of freedom in designing the approach distance between adjacent stirrers is increased. .

  The apparatus to which the stirring method and the arm rotary gas sparger of the present invention can be applied is not particularly limited as long as it requires aeration, and a desulfurization apparatus for exhaust gas generated during waste treatment, coal combustion, etc., and slurry stirring. It can be widely applied to devices for chemical synthesis plants such as batch reactors for performing aeration or devices for biomass plants, as well as devices for equalizing the concentration of a specific substance in a liquid using two or more stirring members. .

Examples 1-4
Water was stored up to a height of 5 m in a 24.1 m × 19.2 m water tank, and two conventional ARS (Mitsubishi Heavy Industries, Ltd.) rotating shafts were spaced apart by 12.1 m. Two ARSs each having a diameter of 4 m and having four stirring arms at 90 ° intervals were used. The detailed positional relationship is shown in FIG.
Of the two, one of the two is a strain gauge (part number: F-type gauge, Tokyo, so that the angle θ1 formed by the detection direction is 90 °, two at the side of the hollow rotating shaft at a water depth of 3.5 m. Sokki Kenkyusha Co., Ltd.).
Next, the phase difference θ (initial phase) at the start of the two units was changed to 0 ° (Example 1), 30 ° (Example 2), 45 ° (Example 3), and 60 ° (Example 4), respectively. The sample was rotated at a rotation speed of 30 rpm, and the maximum unbalance load was measured. The results are shown in Table 2.

表２から、回転位相により最大アンバランス荷重が大きく異なることがわかり、今回の条件下では、初期位相が０°のとき、すなわち２基の攪拌機の位相が整合しているときに最も大きく、初期位相が４５°のときに最も小さくなることがわかった。

From Table 2, it can be seen that the maximum unbalance load varies greatly depending on the rotational phase. Under the present conditions, the initial phase is 0 °, that is, the largest when the two stirrers are in phase, It was found that the phase became the smallest when the phase was 45 °.

Example 5
Instead of the conventional ARS used in the first embodiment, two from the lower end of the hollow rotating shaft in the horizontal direction, two from a position 2 m higher than the lower end of the hollow rotating shaft, and the angle formed by the stirring arm is viewed from above. An ARS equipped with four stirring arms each protruding in a step so as to be 90 ° was used. The lower end of the hollow rotating shaft was installed at a water depth of 4 m. FIG. 8 and Table 3 show the positional relationship of ARS in the fluid tank. Other conditions were the same as in Example 1, and the maximum unbalance load was measured. The results are shown in Table 4.
Example 6
Instead of the ARS used in Example 1, two ARSs capable of adjusting the length of the hollow rotating shaft were used. The difference in the height of the stirring surfaces of the two ARSs was 1 m, and the water depths were 3.5 m and 2.5 m, respectively. Other conditions were the same as in Example 1. The results are shown in Table 4.
Example 7
The same procedure as in Example 1 was performed except that a dummy blade 61 for reducing Karman vortex was attached to the trailing edge with respect to the rotation direction of the two ARS stirring arms as shown in FIG. The results are shown in Table 4.
Example 8
The same procedure as in Example 1 was performed except that a Karman vortex reduction plate 71 was attached to the outside of the blades of the two ARS stirring arms as shown in FIG. The results are shown in Table 4.

表４から、従来型のＡＲＳを用いた実施例１に比べて、独特の構造を有するＡＲＳを用いた実施例５は最大アンバランス荷重が劇的に低減していることがわかった。また実施例６のような高さを違えた構造、実施例７〜８の独特の構造を有するＡＲＳを用いることにより、従来型のＡＲＳを用い同じ初期位相４５°で回転した実施例３に比べて、より一層最大アンバランス荷重を低減することができた。

Table 4 shows that the maximum unbalance load is dramatically reduced in Example 5 using ARS having a unique structure as compared to Example 1 using conventional ARS. Further, by using an ARS having a different height as in Example 6 and a unique structure in Examples 7 to 8, compared to Example 3 using the conventional ARS and rotating at the same initial phase of 45 °. Thus, the maximum unbalanced load could be further reduced.

FIG. 1 is a schematic diagram illustrating an example of an installation mode of a strain gauge. FIG. 2 is a schematic diagram showing one aspect of the mechanical phase control method at the time of startup. FIG. 3 is a schematic diagram showing an aspect of the electrical phase control method at the time of startup. FIG. 4 is a schematic view showing an embodiment of the arm rotary gas sparger of the present invention. FIG. 5 is a schematic view showing an embodiment of the arm rotary gas sparger of the present invention. FIG. 6 is a schematic view showing another aspect of the arm rotary gas sparger. FIG. 7 is a schematic view showing another aspect of the arm rotary gas sparger. FIG. 8 is a plan view showing an ARS installation position in the embodiment. FIG. 9 is a schematic diagram showing the entire structure of a conventionally known ARS drive mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Stirring member 11, 21, 31 Rotating shaft 12 Strain gauge 22 Cam 23 Slide 24 Stopper 32 Rotation phase detector 33 Calculator 34 Start-up control apparatus 35 Electric motor 40, 50, 60, 70 Arm rotary gas sparger 41 Joint 42 Stirring arm 43 Branch pipes 51, 91 Hollow rotary shaft 61 Dummy blade 71 for Karman vortex reduction 92 Karman vortex reduction plate 92 Reducer 93 Motor 94 Air source 95 Air 96 Pipe 97 Branch pipe 98 Air nozzle

Claims (2)

A method for stirring fluid in a fluid tank comprising at least two stirring members having parallel rotation axes,
A fluid agitation method in which the rotation phase is controlled to a predetermined value at which the maximum unbalance load is minimized while maintaining the rotation speed of an adjacent stirring member at a predetermined value, wherein the rotation phase is the predetermined value. A fluid stirring method for adjusting the rotational phase to the predetermined value by temporarily lowering the rotational speed of at least one of the at least two stirring members when the value deviates from the value.   The fluid stirring method according to claim 1, wherein the diameter of the stirring member is 1 m or more and 10 m or less.

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