Flow path switching device and flow path switching method

Abstract

To provide a flow path switching device and a flow path switching method capable of preventing or suppressing overflow at a fluid blocking part in an old waterway when switching the fluid flow path by blocking the old waterway through which the fluid flows and allowing the fluid to flow into a new waterway branched from the old waterway instead of the old waterway.SOLUTION: A flow path switching device that switches from a first flow path 1 to allow the fluid to flow into a second flow path 2 branched from the first flow path 1 through which the fluid flows comprises a blocking part 7 that is provided on a downstream side of the first flow path 1 than a branch part 5 where the second flow path 2 branches from the first flow path 1 in the fluid flow direction, and that blocks the first flow path 1, and conversion parts 4, 8, 9, 10, 11 that are provided in the branch part 5 and generate a fluid flow of the fluid from the first flow path side 1 toward the second flow path 2 side by colliding with the fluid.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for switching flow paths through which a fluid flows, and more particularly to an apparatus and method for switching flow paths through which a liquid phase fluid flows. [Background technology]

[0002] In the steelmaking process, wet dust collectors are often used to remove dust contained in exhaust gas. Wet dust collectors are configured to spray water onto the exhaust gas to bring the exhaust gas into contact with the water and remove dust from the exhaust gas. The dust-collected water (hereinafter referred to as treated water) containing a large amount of dust generated by the wet dust collector flows through a pipe of about 200 m installed in the factory, for example, and is then transported to a water treatment facility via a trough-type waterway installed outdoors. In the water treatment facility, the treated water is purified or rendered harmless by, for example, separating the dust still contained in it.

[0003] The treated water may contain harmful chemicals, and depending on the chemicals contained in the treated water, the treated water may become acidic, for example, with a hydrogen ion concentration index of about "3" (pH3). For this reason, it is required that the treated water does not leak from the waterway through which it flows. On the other hand, due to restrictions on the placement of the wet dust removal equipment and water treatment equipment and the need to monitor the water flow, the waterway that transports the treated water may be a trough-type waterway with an open top, rather than a sealed waterway using pipes, etc.

[0004] As described above, the treated water contains a lot of dust, and when the trough-type waterway through which the treated water flows is used for a long period of time, the dust causes erosion and corrosion of the trough-type waterway. Therefore, the trough-type waterway needs to be renewed at a certain frequency. When renewing the trough-type waterway, for example, the trough-type waterway is branched on the upstream side of the part to be renewed in the flow direction of the treated water to install a new trough-type waterway, and the downstream side of the branching part of the trough-type waterway is blocked in the flow direction of the treated water (hereinafter, the part where the trough-type waterway is blocked is referred to as the blocking part, the trough-type waterway to be renewed is referred to as the old waterway, and the newly installed trough-type waterway is referred to as the new waterway). By doing so, the old waterway is repaired or replaced. However, when the trough-type waterway is branched as described above and the old waterway is blocked, there is a possibility that the flow of the treated water will overflow the blocking part and flow into the old waterway.

[0005] Methods for repairing deteriorated waterways are described in Patent Documents 1 to 3. These involve repairing or renovating existing waterways by forming a tubular waterway within an existing trough-type waterway or by dividing the waterway.

[0006] In addition, methods for preventing overflow of water flowing through a waterway are described in Patent Document 4 and Patent Document 5. Specifically, Patent Document 4 describes a rainwater drainage system that prevents rainwater from overflowing from each waterway by connecting multiple waterways connected to a discharge channel to each other and flowing rainwater from a waterway with a high water level to a waterway with a low water level. Patent Document 5 describes a weir device configured to divert water to another waterway when the water level on the upstream side rises. That is, a movable weir and a fixed weir are provided in the waterway as the weir device, and the movable weir is opened when the water level of the waterway does not exceed the fixed weir, and the movable weir is closed to divert water to another waterway when the water level of the waterway exceeds the fixed weir. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2003-90026 A [Patent Document 2] Japanese Patent Application Publication No. 11-140849 [Patent Document 3] JP 2020-37796 A [Patent Document 4] JP 2006-37478 A [Patent Document 5] Japanese Patent Application Publication No. 11-222835 Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, the hydrogen ion concentration index (pH) of the treated water may be low depending on the dust contained in the treated water, which may deteriorate the trough-type waterway in the steelworks. When the degree of deterioration of the trough-type waterway is large, that is, when the deterioration is severe, the trough-type waterway is removed and a new trough-type waterway is laid. In contrast, the techniques described in Patent Documents 1 to 3 are for repairing or renovating deteriorated waterways, and are not related to the replacement or switching of trough-type waterways in steelworks. Furthermore, when the deterioration of the trough-type waterway is severe, repair may not be enough. In other words, the repair and renovation methods described in Patent Documents 1 to 3 cannot sufficiently repair a severely deteriorated trough-type waterway, and there is a possibility that leakage of treated water may occur due to deterioration or damage of the trough-type waterway.

[0009] In addition, the technologies described in Patent Documents 4 and 5 are intended to prevent leakage, including overflow, from waterways. When the flow rate of treated water flowing through each waterway fluctuates suddenly and significantly, such as when switching from an old waterway to a new waterway, it may not be possible to prevent or suppress overflow at the cutoff point of the old waterway.

[0010] The present invention has been made to solve the above-mentioned problems, and aims to provide a flow path switching device and flow path switching method that can prevent or suppress overflow at the fluid blocking section in an old waterway when switching the flow path of a fluid by blocking the old waterway through which the fluid flows and causing the fluid to flow in a new waterway branching off from the old waterway instead of the old waterway. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides [1] A flow path switching device that switches the flow of a fluid from a first flow path through which the fluid flows to a second flow path branching off from the first flow path, the flow path switching device comprising: a blocking section that is provided downstream of the first flow path in the flow direction of the fluid relative to a branching section where the second flow path branches off from the first flow path and blocks the first flow path; and a diversion section that is provided at the branching section and causes a fluid flow of the fluid from the first flow path side to the second flow path side by colliding with the fluid. [2] In the flow path switching device described in [1] above, the conversion portion is a protrusion protruding from a wall surface of the first flow path in the branching portion that faces the second flow path. [3] The flow path switching device according to [2] above, wherein a protruding length L of the protruding portion in a width direction of the first flow path satisfies the following formula with respect to a flow path width W of the first flow path. 0.3W≦L <W [4] The first flow path forms a trough-type waterway, and the protrusion is provided on a first side wall surface of both side walls of the trough-type waterway that faces the second flow path at the branching portion. This is a flow path switching device described in [2] or [3] above. [5] A flow path switching device as described in [4] above, wherein, of the outer peripheral surfaces of the protrusion with which the fluid collides, a first outer peripheral surface located upstream in the flow direction of the fluid is formed flat, and an angle between the first outer peripheral surface and the first side wall surface is greater than or equal to 30° and less than 90°. [6] A flow path switching method for switching a fluid to flow from a first flow path through which a fluid flows to a second flow path branching from the first flow path, the method comprising the steps of: providing a fluid flow direction change section at a branching section where the second flow path branches off from the first flow path in the flow direction of the fluid, the change section colliding with the fluid to generate a fluid flow of the fluid from the first flow path side toward the second flow path side; and blocking the first flow path with a blocking section that is provided downstream of the first flow path relative to the branching section, thereby causing the fluid to flow from the first flow path to the second flow path. Effect of the Invention

[0012] According to the present invention, when a fluid collides with the conversion section, the flow direction of the fluid is converted to the second flow path side and flows toward the second flow path. The fluid that has collided with the conversion section once and has reduced kinetic energy (dynamic pressure) flows downstream of the conversion section. Therefore, even if the fluid collides with the cutoff section, the flow rate and water level of the fluid at the cutoff section are reduced, and the kinetic energy is reduced by the conversion section as described above, so that overflow at the cutoff section can be prevented or suppressed. [Brief description of the drawings]

[0013] [Figure 1] 1A to 1C are diagrams illustrating an example of a flow path switching device and a flow path switching method according to the present invention. [Diagram 2] 10A and 10B are diagrams for explaining an example of the shape of a protrusion; [Diagram 3] 10A and 10B are diagrams for explaining other examples of the shape of the protrusion. [Figure 4] 13A and 13B are diagrams for explaining still another example of the shape of the protrusion. [Diagram 5] 10A and 10B are diagrams for explaining an example of the shape of a blocking portion. [Figure 6] FIG. 2 is a diagram showing an example of a trough-type waterway used in the numerical analysis of the embodiment. [Figure 7] 13 is a diagram for explaining an example in which a protrusion and a straightening portion are provided at a branch portion. FIG. [Figure 8]FIG. 13 is a diagram showing the distribution of water level heights in an embodiment and a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described. The flow path switching device according to the present invention is configured to prevent or suppress overflow at a blocking section that blocks the first flow path when the first flow path is switched to a second flow path connected to the first flow path through which the fluid flows, and to cause the fluid to flow. Specifically, the flow path switching device according to the present invention blocks the first flow path downstream of a point (hereinafter, referred to as a branching section) where the second flow path is connected to the first flow path in the flow direction of the fluid, thereby switching from the first flow path to the second flow path. Also, the branching section is configured to prevent or suppress overflow at a blocking section that blocks the first flow path by generating a fluid flow of the fluid toward the second flow path. Therefore, the above-mentioned fluid is a liquid-phase fluid, and the first flow path and the second flow path are flow paths in which overflow may occur. For example, a trough-type waterway with an open upper surface can be given as the first flow path and the second flow path. The trough-type waterway may be a conventionally known one, and its cross-sectional shape may be any shape, such as a U-shape or a V-shape.

[0015] FIG. 1 is a diagram showing an example of a flow path switching device and a flow path switching method according to the present invention, and FIG. 1(a) is a top view showing an example of a first flow path. In the example shown here, although details are not shown, a wet dust collector is arranged on the upstream side of the first flow path 1 in the flow direction of the fluid. As an example, the wet dust collector is for removing dust contained in exhaust gas generated in an iron making process of an ironworks, and is configured to remove dust in the exhaust gas by contacting the exhaust gas with the water by spraying water onto the exhaust gas. The wet dust collector may be configured similarly to a conventionally known one. Water containing a large amount of dust generated in the wet dust collector (hereinafter, referred to as treated water) corresponds to the above-mentioned liquid phase fluid. In addition, a water treatment facility is located downstream of the wet dust collector in the flow direction of the treated water. The water treatment facility purifies or renders the treated water harmless, and may be configured similarly to a conventionally known water treatment facility.

[0016] The exhaust gas or dust discharged in the steelmaking process may contain harmful chemicals, and therefore the treated water may contain the above-mentioned chemicals. Depending on the type of chemicals, the hydrogen ion concentration index (pH) of the treated water may be acidic, about "3". When the first flow path 1 is exposed to the acidic treated water, it may corrode or be worn down by particulate matter such as dust contained in the treated water, and may gradually deteriorate. Therefore, it is preferable that the first flow path 1 is renewed or replaced at a predetermined frequency. For example, a second flow path is newly connected to a portion of the first flow path 1 that is highly deteriorated or to the upstream side of a range including such a portion, and the flow path through which the treated water flows is switched from the first flow path 1 to the second flow path. In this way, the first flow path 1 downstream of the branching part where the second flow path is connected to the first flow path 1 in the flow direction may be renewed or replaced. Alternatively, the entire length of the first flow path 1 may be renewed or replaced at once. The example shown here is an example in which the flow path through which the treated water flows is switched from the first flow path 1 to the second flow path, and the first flow path 1 downstream of the branching part is renewed or replaced.

[0017] As a specific procedure for switching the flow paths, first, a position in the first flow path 1 where the second flow path is connected, that is, a position where the first flow path 1 is branched (hereinafter, referred to as a branch start position, not shown) is determined. An example of the branch start position is a portion of the first flow path 1 that is highly deteriorated, or an upstream portion of a range including a portion that is highly deteriorated. Such an upstream portion is, for example, a portion where the first flow path 1 is laid in a straight line or a gentle curve, and is a position where a working space for installing a branching section can be secured. In addition, a position where the flow path width of the first flow path 1 is relatively wide and the flow rate of the treated water is low is preferable.

[0018] Next, the second flow path 2 is connected to the branch start position as shown in (b) of FIG. 1. The second flow path 2 may be a trough-type waterway configured similarly to the first flow path 1. The width and depth of the second flow path 2 are set to be substantially the same as those of the first flow path 1. In addition, before the flow path of the treated water is switched from the first flow path 1 to the second flow path 2, that is, until the installation of the second flow path 2 is completed over the entire length, a partition wall 3 is installed between the first flow path 1 and the second flow path 2. (b) of FIG. 1 shows this state. By doing so, the treated water is configured not to flow from the first flow path 1 to the second flow path 2, and in this state, the second flow path 2 is installed for a predetermined length from the branch start position or from the branch start position to the above-mentioned water treatment facility.

[0019] After the construction of the second flow path 2 is completed, or in parallel with the construction of the second flow path 2, a conversion section of this embodiment is installed to generate a fluid flow of treated water from the first flow path 1 toward the second flow path 2, as shown in FIG. 1(c). In the example shown in FIG. 1(c), a protruding section protruding from the side wall surface of the first flow path 1 toward the inside of the first flow path 1 is formed as the conversion section. Therefore, in the following description, the conversion section is referred to as a protruding section 4. The installation position of the protruding section 4 in the first flow path 1 is a branching section 5 where the second flow path 2 branches off from the first flow path 1, and the branching section 5 is shown surrounded by a dotted line in FIG. 1. The protruding section 4 will be described later.

[0020] 1(d), the partition wall 3 is removed to open the inlet 6 of the second flow path 2. In this way, the treated water flows from the first flow path 1 to the second flow path 2, so that the flow rate and water level of the treated water downstream of the partition wall 4 in the flow direction of the treated water in the first flow path 1 are reduced compared to before the partition wall 3 was removed.

[0021] Almost simultaneously with or after the partition wall 3 is removed, a blocking unit 7 that blocks the first flow path 1 is installed downstream of the branching unit 5 in the flow direction of the treated water in the first flow path 1. If the flow of the treated water in the first flow path 1 is blocked by the blocking unit 7 in a state where the flow rate and water level of the treated water downstream of the protruding unit 4 have not been reduced as described above, the water level of the treated water in the vicinity of the blocking unit 7 will rise compared to when the flow rate and water level of the treated water are reduced. If the treated water collides with the blocking unit 7 in this state, there is a possibility that the treated water will overflow the blocking unit 7, and this is to avoid this. The timing of blocking the first flow path 1 by the blocking unit 7 after removing the partition wall 3 can be determined by experiments, etc. In the present invention, the flow of the treated water is switched from the first flow path 1 to the second flow path 2 as described above. (e) of FIG. 1 shows this state.

[0022] Here, the protruding portion 4 will be described. The protruding portion 4 is configured to change the flow direction of the treated water flowing along the first flow path 1 so that the treated water flows toward the second flow path 2. Specifically, the protruding portion 4 is in the shape of a triangular prism that protrudes from the side wall surface 1a, which faces the inlet 6 of the second flow path 2, among both side wall surfaces 1a, 1b of the first flow path 1. Of the three side surfaces 4a, 4b, and 4c of the protruding portion 4, the first side surface 4a is installed in the first flow path 1 in a state where it is almost in contact with the side wall surface 1a of the first flow path 1. Of the remaining two side surfaces 4b, 4c, the second side surface 4b is located upstream of the third side surface 4c in the flow direction of the treated water. By colliding the treated water flowing along the first flow path 1 with the second side surface 4b of the protruding portion 4, a component force whose line of action is directed toward the second flow path 2 side is generated, that is, a fluid flow of the treated water flowing toward the second flow path 2 is generated, thereby changing the flow direction of the treated water.

[0023] The protrusion 4 is preferably installed between the upstream end and downstream end of the inlet 6 of the second flow path 2 in the flow direction of the treated water. This is to avoid the possibility that the treated water whose flow direction has been changed to the second flow path 2 side by the protrusion 4 collides with the side wall surface 1b of the first flow path 1 on the second flow path 2 side, causing overflow, when the protrusion 4 is installed downstream of the downstream end of the inlet 6 in the flow direction, causing the width of the first flow path 1 at the installation location to be narrowed and the water level to be raised. Also, the treated water whose flow direction has been changed to the second flow path 2 side by the protrusion 4 collides with the side wall surface 1b of the first flow path 1 on the second flow path 2 side, causing overflow, when the protrusion 4 is installed downstream of the downstream end of the inlet 6 in the flow direction, causing overflow, when the protrusion 4 is installed downstream of the downstream end of the inlet 6 in the flow direction. Also, the treated water whose flow direction has been changed to the second flow path 2 side by the protrusion 4 collides with the side wall surface 1b of the first flow path 1 on the second flow path 2 side, causing overflow, when the protrusion 4 is installed downstream of the downstream end of the inlet 6 in the flow direction, causing overflow, when the protrusion 4 is installed.

[0024] In addition, the angle θ1 between the second side surface 4b of the protruding portion 4 with which the treated water collides and an axis parallel to the flow direction of the treated water (hereinafter referred to as the inclination angle) is preferably 30° or more and less than 90°. This is to avoid a decrease in the function of redirecting the flow direction of the treated water to the second flow path 2 when the inclination angle θ1 of the second side surface 4b is less than 30°. In addition, the treated water collides almost directly with the blocking portion 7 of the first flow path 1, which may cause overflow, and this is to avoid this.

[0025] On the other hand, when the inclination angle θ1 of the second side surface 4b is 90° or more, the second side surface 4b ends up blocking a part of the treated water. That is, the dynamic pressure of the treated water colliding with the second side surface 4b is received by the second side surface 4b without being diverted. In order to resist the dynamic pressure of the treated water, the strength or rigidity of the protruding portion 4 must be increased, and this may result in an increase in the material cost, processing or manufacturing cost, and installation cost of the protruding portion 4, and this is to be avoided.

[0026] It is more preferable that the inclination angle θ1 of the second side surface 4b is substantially equal to the angle between the first flow path 1 and the second flow path 2 at the branching portion 5. The case where the first flow path 1 and the end side of the second flow path 2 connected to the first flow path 1 are each linear will be described. It is more preferable that the inclination angle θ1 of the second side surface 4b is substantially equal to the angle between the central axis of the first flow path 1 at the branching portion 5 and the central axis of the end side of the second flow path 2 connected to the first flow path 1. Next, it is described that the first flow path 1 and the end side of the second flow path 2 connected to the first flow path 1 are each curved. It is more preferable that the inclination angle θ1 of the second side surface 4b is substantially equal to the angle between the tangent to the center line of the first flow path 1 passing through the intersection point between the center line of the first flow path 1 at the branching portion 5 and the center line of the end side of the second flow path 2, and the tangent to the center line of the end side of the second flow path 2 passing through the intersection point. This is because the effect of directing the flow direction of the treated water toward the second flow path 2 is enhanced.

[0027] Furthermore, it is preferable that the second side surface 4b is immersed in the treated water and that a part of it, even if only slightly, protrudes from the surface of the treated water. This is because the flow of the treated water near the surface can be guided to the second flow path 2 side. In addition, the inertial force near the surface of the water flow has a large effect on the overflow at the blocking section 7 of the first flow path 1, and the flow (inertial force) of this part is reduced by the protruding part 4. In this way, it is sufficient for the protruding part 4 to change the flow direction of the treated water and at least reduce the inertial force near the surface of the treated water. Therefore, the protruding part 4 may be installed in the first flow path 1 at the branching part 5 so that a gap is generated between the first flow path 1 and the bottom surface of the protruding part 4. FIG. 2(a) shows this state. However, it is preferable that the height of the protruding part 4 is set to be approximately the same height as the depth of the first flow path 1 as shown in FIG. 2(b), and is installed so as to rise from the bottom of the first flow path 1. This is because the flow of the treated water can be effectively changed to the second flow path 2 side.

[0028] Furthermore, it is preferable to configure the protrusion 4 so that the protrusion length L of the protrusion 4 in the width direction of the first flow path 1 satisfies the relationship of the following formula (1) with respect to the flow path width W of the first flow path 1, and it is even more preferable that the protrusion 4 satisfies the relationship of the following formula (2). 0.3W≦L <W …(1) 0.5W≦L<0.9W …(2)

[0029] The flow width W in the above formulas (1) and (2) means the width of the first flow path 1, which is a trough-type waterway. The protruding length L means the length or distance between the side wall surface 1a of the first flow path 1 at the branching portion 5 and the portion where the protruding portion 4 protrudes most from the side wall surface 1a toward the second flow path 2 in the direction of the flow width W of the first flow path 1.

[0030] If the protruding length L is smaller than the length equivalent to 30% of the flow width W (0.3W≦L), the amount of treated water colliding with the protruding portion 4 will be reduced, which may reduce the function of diverting the flow direction of the treated water toward the second flow path 2. In addition, the entire amount of treated water will collide with the blocking portion 7 of the first flow path 1 almost as it is, which may cause overflow at the blocking portion 7.

[0031] If the protruding length L is greater than or equal to the flow width W, the amount of treated water that collides with the protruding portion 4 increases, and it becomes necessary to increase the strength or rigidity of the protruding portion 4 in order to resist the dynamic pressure of the treated water. This may result in an increase in the material cost, processing or manufacturing cost, and installation cost of the protruding portion 4.

[0032] The shape of the protrusion 4, that is, the cross-sectional shape of the protrusion 4 parallel to the horizontal plane is not limited to a triangular shape as shown in FIG. 1, and may be a trapezoidal protrusion 8 as shown in FIG. 3(a). Also, as shown in FIG. 3(b), it may be a trapezoidal protrusion 9 configured such that the upstream side is inclined in the flow direction of the treated water and the downstream side is perpendicular to the first flow path 1. Also, the protrusion 4 is not limited to a bank-like structure as shown in FIG. 1, and may be configured such that the side wall surface 1a of the first flow path 1 protrudes inwardly of the first flow path 1 as shown in FIG. 4(a). That is, it may be a protrusion 10 formed integrally with the first flow path 1. Furthermore, as shown in FIG. 4(b), a plate (hereinafter referred to as a protruding plate) 11 protruding inwardly of the first flow path 1 from the side wall surface 1a of the first flow path 1 may function as a protrusion. In this case, the overhanging plate 11 may be rotatably attached to the side wall surface 1a of the first flow path 1 so that the inclination angle θ1 of the overhanging plate 11 with respect to the flow direction of the treated water can be changed, and the inclination angle θ1 of the overhanging plate 11 may be changed by an actuator (not shown). In this way, when switching the flow path of the treated water from the first flow path 1 to the second flow path 2, the overhanging plate 11 can be rotated by the actuator so as to have the inclination angle θ1 that generates the above-mentioned fluid flow toward the second flow path 2. Then, the actuator (not shown) may be controlled, or the overhanging plate 11 may be fixed by a stopper (not shown) so as to maintain the inclination angle θ1 that generates the above-mentioned fluid flow toward the second flow path 2. In this way, the protrusion 4 may be configured to generate a fluid flow toward the second flow path 2 by colliding with the treated water when switching the flow path of the treated water from the first flow path 1 to the second flow path 2.

[0033] Next, the blocking unit 7 will be described. The blocking unit 7 that blocks the first flow path 1 only needs to have a function of blocking the flow of treated water in the first flow path 1, and the shape of the blocking unit 7 and the material of the blocking unit 7 are not limited as long as the blocking unit 7 has such a function. The blocking unit 7 may be a plate-shaped structure such as an iron plate or a concrete plate. The plate-shaped blocking unit 7 may be configured to be inserted along a groove 12 formed in the first flow path 1 as shown in FIG. 5. The groove 12 is provided on each of the side wall surfaces 1a, 1b and the bottom surface of the first flow path 1, and the groove 12 formed on the side wall surfaces 1a, 1b is provided over the entire length of the first flow path 1 in the height direction. The height of the blocking unit 7 is set to be approximately the same as the depth of the first flow path 1. This makes it possible to prevent or suppress overflow at the blocking unit 7 when the blocking unit 7 blocks the flow of treated water in the first flow path 1.

[0034] In addition, a gantry crane (not shown) may be placed around the blocking unit 7 to install the blocking unit 7 and open and close the first flow path 1. Specifically, although not shown in detail, a platform is installed so as to cross the first flow path 1, and a chain block is attached to the platform. The attachment position of the chain block may be a position where the hook of the chain block can access a jig (not shown), such as a hanging piece, provided on the upper part of the blocking unit 7. In this way, the blocking unit 7 can be raised and lowered in the vertical direction using the gantry crane, and the first flow path 1 can be blocked and opened. The blocking unit 7 may also be configured of a structure that can be opened and closed like a water gate.

[0035] Therefore, according to the present invention, when the treated water collides with the protrusions 4, 8, 9, 10 and the overhanging plate 11, the flow direction of the treated water is changed to the second flow path 2 side and flows toward the second flow path 2. In other words, the protrusions 4, 8, 9, 10 and the overhanging plate 11 guide the collided treated water to the second flow path 2 side. As a result, the treated water that once collided with the protrusions 4, 8, 9, 10 and the overhanging plate 11 and whose kinetic energy (dynamic pressure) has been reduced flows downstream of the protrusions 4, 8, 9, 10 and the overhanging plate 11. Therefore, even if the treated water collides with the blocking section 7, the flow rate, water level, and kinetic energy of the treated water at the blocking section 7 are reduced as described above, so that overflow at the blocking section 7 can be prevented or suppressed.

[0036] In addition, in this embodiment, in addition to the above-mentioned protrusions 4, 8, 9, 10 and the protruding plate 11, the conversion section may also be provided with a straightening section that straightens the fluid flow (hereinafter sometimes referred to as the conversion flow) of the treatment water flowing from the first flow path 1 to the second flow path 2.

[0037] 7 is a diagram for explaining an example in which the protrusion 4 and the rectification section 13 are provided in the branch section 5. The rectification section 13 is, for example, formed in a plate shape, and extends from the bottom surface of the first flow path 1 to the water surface. The length of the rectification section 13 in the width direction of the first flow path 1 is not particularly limited, but in the example shown in FIG. 7, the sum of the length and the protrusion length L of the protrusion 4 is set to be approximately the same as the flow path width W of the first flow path 1 or shorter than the flow path width W of the first flow path 1.

[0038] The rectifying section 13 rectifies the diverted flow generated by collision with the protruding section 4. Therefore, it is preferable to arrange it on the second flow path 2 side of the protruding section 4 in the width direction of the first flow path 1, on an extension line along the second side surface 4b of the protruding section 4. It is preferable to arrange the rectifying section 13 in the branching section 5 at approximately the same timing as the arrangement of the protruding section 4. In addition, the rectifying section 13 is configured to be rotatable about the center 13a in the length direction of the rectifying section 13 as the center of rotation in a top view of the trough-type waterway shown in FIG. 7, and the rotation angle θ2 of the rectifying section 13 can be controlled by an actuator (not shown). Here, the rotation angle θ2 of the rectifying section 13 means the angle between the rectifying section 13 and the center line of the first flow path 1 in a top view of the trough-type waterway shown in FIG. 7.

[0039] (action) For example, when switching the flow path of the treated water from the first flow path 1 to the second flow path 2, the rotation angle θ2 of the rectifier 13 is set to approximately the same angle as the inclination angle θ1 of the second side surface 4b of the protruding portion 4 by an actuator (not shown). The treated water collides with the protruding portion 4, and the diverted flow generated thereby flows along the rectifier 13. Specifically, the rectifier 13 functions as a weir that suppresses the diverted flow from being swept away by the treated water flowing from the upstream side of the protruding portion 4 to the downstream side of the protruding portion 4, and also guides the treated water to the second flow path 2 side. Therefore, the treated water flows more easily into the second flow path 2 than in each of the above-mentioned embodiments, and the flow rate of the treated water flowing through the second flow path 2 is increased. On the other hand, the flow rate of the treated water toward the blocking portion 7 is reduced, and overflow at the blocking portion 7 can be more effectively suppressed.

[0040] When the rotation angle θ2 of the flow straightening unit 13 is set to be smaller than the inclination angle θ1 of the second side surface 4b of the protrusion 4, for example, to be approximately 0°, at least a part of the diverted flow is easily swept away to the downstream side of the protrusion 4 by the treated water flowing from the upstream side of the protrusion 4. As a result, the treated water is less likely to flow into the second flow path 2, and the flow rate of the treated water flowing through the second flow path 2 decreases. On the other hand, the flow rate of the treated water toward the blocking unit 7 increases, and the treated water can wash away dust remaining near the blocking unit 7. In addition, in FIG. 7, the flow straightening unit 13 with the rotation angle θ2 set to approximately 0° is depicted by a dotted line.

[0041] 7, the flow straightening unit 13 is configured to be rotatable, but the flow straightening unit 13 may be fixed to the first flow path 1. Although details are not shown, in this case, the plate-shaped flow straightening unit 13 is fixed to the first flow path 1 so as to extend along an extension line along the second side surface 4b of the protruding portion 4. Even in this configuration, the treated water can easily flow into the second flow path 2, and the flow rate of the treated water heading toward the cut-off unit 7 can be reduced to suppress overflow at the cut-off unit 7.

[0042] The present invention is not limited to the above-mentioned embodiment. Instead of the protrusions 4, 8, 9, 10 and the overhanging plate 11 as described above, for example, a plurality of pillars are aligned in a row at a fixed interval. The plurality of pillars aligned in a row are installed in the branching section 5 so that the angle between the axis parallel to the alignment direction of the plurality of pillars aligned in a row and the side wall surface 1b of the first flow path 1 is the above-mentioned inclination angle θ1. Even in this configuration, the treated water can be collided with the plurality of pillars to generate a fluid flow toward the second flow path 2, and the flow rate, water level, and kinetic energy of the treated water at the blocking section 7 can be reduced. That is, the same action and effect as the above-mentioned embodiment can be obtained.

[0043] [Example] As an embodiment of the present invention, an example of a numerical analysis is shown in which the flow path of treated water is switched in the trough-type waterway shown in Fig. 6. The flow direction of treated water shown in Fig. 6 is opposite to the flow direction of treated water shown in Fig. 1. Since other configurations are similar to those shown in Fig. 1, the same reference numerals as those in Fig. 1 are used for the same configurations as those in Fig. 1, and the description thereof is omitted.

[0044] The dimensions of the trough-type waterway shown in FIG. 6 will be described. In the example shown here, the flow path width W of the first flow path 1 is set to 800 mm, the protruding length L of the protruding portion 4 is set to 400 mm, and the inclination angle θ1 of the second side surface 4b of the protruding portion 4 is set to 30°. In addition, in the axial direction of the first flow path 1, the length between the blocking portion 7 and the portion where the protruding portion 4 protrudes most toward the second flow path 2 side is set to 2250 mm, and the flow path width of the second flow path 2 is set to 800 mm, similar to the flow path width W of the first flow path 1. In addition, the height of the protruding portion 4 is set to a height equal to or greater than the depth of the treated water in the first flow path 1, and is set to be in contact with the bottom surface of the first flow path 1 and the side wall surface 1a of the first flow path 1 at the branch portion 5. In other words, the upper part of the protruding portion 4 is set to extend above the water surface of the treated water. In addition, the blocking portion 7 is set to a height equal to or greater than the depth of the first flow path 1, that is, the upper part of the blocking portion 7 is set to extend above the water surface of the treated water.

[0045] The numerical analysis was performed by unsteady analysis using the VOF (Volume of Fluid) method, which is capable of analyzing free surface flows. The analysis conditions were as follows: the flow rate of treated water flowing into the branch was 900m 3 / h, flow velocity was set to 3.125 m / s, and water level was set to 100 mm.

[0046] FIG. 8(a) shows the distribution of the water level in the above-mentioned embodiment. FIG. 8(b) shows the distribution of the water level in the comparative example in which the protruding portion 4 is not provided at the branching portion 5. As shown in FIG. 8(a) and FIG. 8(b), in the comparative example, the water level of the treated water rises to about 425 mm near the blocking portion 7 of the first flow path 1, whereas in the embodiment of the present invention, the water level of the treated water near the blocking portion 7 of the first flow path 1 is about 300 mm. In addition, in the embodiment of the present invention, the maximum water level in the first flow path 1 and the second flow path 2 is suppressed to about 325 mm. From these results, it is assumed that there is a high risk of overflow of the treated water from the blocking portion 7 of the first flow path 1 in the comparative example in which the protruding portion 4 is not provided. In contrast, it is assumed that there is a low risk of overflow in the embodiment of the present invention.

[0047] In addition, the water level of the treated water flowing from the first flow path 1 to the branch 5 in FIG. 8(a) is about 125 mm, while the water level of the treated water at the outlet of the second flow path 2 is about 200 mm, and it can be seen that the water level in the second flow path 2 is higher than the water level in the first flow path 1. This is because the flow rates of the treated water flowing into the first flow path 1 and the treated water discharged from the second flow path 2 are equal, and the flow rate of the treated water at the outlet of the second flow path 2 is lower than the flow rate of the treated water flowing through the first flow path 1. On the other hand, the water level of the treated water at the outlet of the second flow path 2 in the comparative example in FIG. 8(b) is about 175 mm, which is lower than the water level of the treated water in the example of the present invention. This is thought to be because the water level in the branch 5 of the comparative example is higher, so the pressure of the treated water flowing through the branch 5 increases, and the flow rate of the treated water at the outlet of the second flow path 2 in the comparative example is faster than that in the example of the present invention. However, in the embodiment of the present invention, the water level of the treated water at the outlet of the second flow path 2 is lower than the water level at the branching portion 5, and overflow does not occur in the second flow path 2. [Explanation of symbols]

[0048] 1 First flow path 2 Second flow path 3 Bulkhead 4,8,9,10 Protruding part (conversion part) 5 Branch 6 Inlet of second flow path 7. Breaking section 11. Extrusion 12 grooves 13 Rectification section (conversion section)

Claims

1. A flow path switching device for switching a fluid from a first flow path through which the fluid flows to a second flow path branched from the first flow path, a blocking portion that is provided downstream of a branching portion at which the second flow path branches off from the first flow path in a flow direction of the fluid and blocks the first flow path; a conversion portion that is provided at the branching portion and that generates a fluid flow of the fluid from the first flow path side toward the second flow path side by colliding with the fluid, the conversion portion is a protruding portion protruding from a wall surface of the first flow path at the branch portion that faces the second flow path, The first flow path forms a trough-type waterway, A flow path switching device, wherein the protrusion is provided on a first side wall surface, one of both side wall surfaces of the trough-type waterway, that faces the second flow path at the branching portion.

2. The protruding length L of the protruding portion in the width direction of the first flow path is The flow path switching device according to claim 1 , wherein the following formula is satisfied: 0.3W≦L<W

3. a first outer circumferential surface of the protrusion with which the fluid collides, the first outer circumferential surface being located upstream in a flow direction of the fluid, the first outer circumferential surface being formed in a flat shape; The flow passage switching device according to claim 1 , wherein an angle between the first outer circumferential surface and the first side wall surface is equal to or greater than 30° and less than 90°.

4. A flow path switching method for switching a fluid from a first flow path through which the fluid flows to a second flow path branched from the first flow path, the method comprising: a fluid flow direction change section that collides with the fluid at a branching section where the second flow path branches off from the first flow path in the flow direction of the fluid, and that changes the flow direction of the fluid to generate a fluid flow of the fluid from the first flow path side toward the second flow path side; a blocking portion that is provided downstream of the first flow path from the branch portion and blocks the first flow path, thereby causing the fluid to flow from the first flow path to the second flow path; the conversion portion is a protruding portion protruding from a wall surface of the first flow path at the branch portion that faces the second flow path, The first flow path forms a trough-type waterway, A flow path switching method, in which the protrusion is provided on a first side wall surface, of both side wall surfaces of the trough-type waterway, that faces the second flow path at the branching portion.

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