JP2011144718A - Piping resistance device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piping resistance device capable of maintaining constant the flow rate of the fluid conveying conduit even in the case the hydraulic head on the conveyance side in a fluid conveying conduit fluctuates suddenly. <P>SOLUTION: The device comprises a branch pipe (Lb) disposed between a sludge pump (Po) of a sludge line system (Lo) and water processing equipment (3) so as to be branched from the sludge line (Lo) for joining a region to the sludge pump (Po) side with respect to a junction (f), and a circulation pump (Pb) disposed in the branch pipe (Lb). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is interposed in a fluid conveyance pipe that conveys a fluid (for example, excavated mud) containing solid matter (for example, excavated earth and sand), and the water head (head, head) on the conveyance side of the fluid is abrupt. The present invention relates to a piping resistance device that can maintain a constant fluid flow rate even if it fluctuates.

FIG. 7 shows an outline of the muddy water shield construction when excavating a horizontal hole (for example, a tunnel).
In FIG. 7, the face chamber 2C of the shield machine 2 communicates with the muddy water adjustment tank 1 on the ground side through the mud feed line L1, and communicates with the water treatment facility 3 on the ground side through the mud discharge line L2.
A mud feed pump Pi having a control panel Ci is interposed on the ground side in the mud feed line L1, and a first mud feed valve V1 is interposed in the vicinity of the face chamber 2C in the mud feed line L1.
A second mud feed valve V2 is interposed near the face chamber 2C in the mud discharge line L2. A plurality of (six in the example of FIG. 7) drainage pumps Pn having a control panel Cn are interposed in the area between the second mud feed valve V2 and the water treatment facility 3 in the drainage line L2. Has been.

The mud feed line L1 and the exhaust mud line L2 are connected so as to bypass the face chamber 2C and the valves V1, V2 by a bypass line L3.
A mud flow meter Mq1 and a waste mud flow meter Mq2 are installed in the mud feed line L1 and the exhaust mud line L2, respectively. The flow rate information detected by the mud flow meter Mq1 and the exhaust mud flow meter Mq2 is grounded by a signal line. It is transmitted to the central monitoring panel 10 installed on the side.
A face pressure gauge Mp is attached to the face chamber 2C, and the pressure information of the face measured by the face pressure gauge Mp is transmitted to the central monitoring panel 10 on the ground side.
Based on the pressure information of the face measured by the face pressure gauge Mp and the flow rate information detected by the mud flow meter Mq1 and the exhaust mud flow meter Mq2, the central monitoring panel 10 on the ground side determines the rotational speed of the mud pump Pi and a plurality of The rotation speed of the mud pump Pn or the ON / OFF of the pump is controlled.

In mountain tunnels where the topography is extremely undulating and for muddy water shield construction where tunnels are built under the seabed, excavation is carried out while holding the water pressure enough to counter abnormally high groundwater pressure, and the excavated sediment is controlled by a pump. While discharging (sludge).
There are various types of grounds such as rock formations and formations containing a large amount of gravel.
Here, the reason why the water pressure sufficient to counter the groundwater pressure is maintained by the face is to stabilize the natural ground during excavation and thus prevent the natural ground from collapsing.

As a general technique for maintaining the water pressure of the face,
a) Control the rotational speed of the mud pump installed on the ground.
b) In the mud discharge line (fluid transport line) for transporting the excavated earth and sand (fluid containing solid matter) to the water treatment facility installed on the ground, a mud pump is provided in the middle, and the rotation speed of the mud pump Control,
Etc. exist.
The mud pump performs control to keep the mud flow rate constant. Further, the muddy water pump is controlled to automatically increase the speed in order to compensate for an increase in frictional resistance as the excavation distance is extended and the pipe length is increased.

However, as shown in FIG. 8, since the topography is complicated, a tunnel may be constructed in a mountain where the groundwater level WL is much higher than the level EL of the water treatment facility 3 installed on the ground. In this case, since the groundwater level WL is high, a very high pressure acts on the mud pump P2.
In addition, in FIG. 8, the code | symbol 1 shows a sewage adjustment tank, the code | symbol 2 shows a shield machine, the code | symbol 3 shows the water treatment equipment 3, the code | symbol P1 shows a mud feed pump, the code | symbol L1 shows a mud feed line, and the code | symbol L2 shows a mud discharge line.

Moreover, as shown in FIG. 9, when deep excavation is performed, the water treatment facility 3 and the mud pump (located on the back side of the sewage adjustment tank 1; indicated by a broken line in FIG. 9) P1 It is difficult to install on the ground side for reasons such as environmental problems, and the water treatment facility 3 and the mud pump P1 may have to be installed under the shaft or underground. In this case, compared with the case where the water treatment facility 3 exists on the ground Gf side, in the case shown in FIG. 9, only the depth of the shaft and the pipe line from the shaft to the ground, the mud pump The total head of P2 becomes smaller.
In addition, in FIG. 9, the code | symbol 2 shows a shield machine, the code | symbol L1 shows a mud feed line, and the code | symbol L2 shows a mud discharge line.

In the cases shown in FIGS. 8 and 9, when the mud pump P1 is controlled to apply high water pressure to the face, the variable speed motor that drives the mud pump P2 is controlled to drop to the minimum rotational speed. However, even if the variable speed motor that drives the mud pump P2 is stopped, the flow rate of the mud line L2 cannot be maintained at the specified flow rate, and mud water exceeding the specified flow rate flows into the mud line L2. End up. Therefore, it is not possible to perform constant flow rate control in the sludge line L2.
In the case of FIGS. 8 and 9, the flow rate of the mud drain line L <b> 2 becomes too large, and a large amount of mud is discharged to the water treatment facility 3.
Even if such a situation occurs, it can be dealt with if the capacity / scale of the water treatment facility 3 is large. However, enormous costs occur when the capacity and scale of the water treatment facility 3 are greatly planned.

In FIG. 8 and FIG. 9, in order to suppress the flow rate of the sludge line L2 from becoming too large, it is only necessary to give resistance to the sludge line L2.
A general method of giving resistance to the sludge line L2 is to reduce the opening degree of the valve interposed in the sludge line L2. Examples of the valve interposed in the mud discharge line L2 include a partition (gate) valve, a ball valve, a butterfly valve, and a pinch valve.
Regardless of which type of valve is interposed, in order to provide the resistance as described above, the opening degree must be reduced by, for example, 50% or more.
However, the muddy water flowing through the mud discharge line L2 includes gravel generated from natural ground and crushed rocks generated from a crusher in rock excavation. Therefore, when the valve opening is reduced, there is a problem that the gravel and crushed rock are clogged between the valve body and the valve seat, and so-called blockage and biting occur.
Therefore, providing the necessary resistance by controlling the opening degree of the valve interposed in the mud discharge line L2 is not suitable for the muddy water shield construction.

As a method for imparting resistance to the sludge line, it is conceivable to reduce the diameter of the pipe used as the sludge line.
However, when determining the pipe diameter, it is necessary to consider the size of the solids (the gravel and crushed rocks) in the mud. In general, the pipe diameter is set at 3 times the size of the solid matter in the waste mud. During transportation of the waste mud, a plurality of solids are gathered together in the pipe to block the pipe. Is preventing. When the pipe diameter is reduced, a plurality of solid substances are collected in the pipe and block the pipe.
Further, when the constant flow rate control is performed by the mud pump, if the pipe diameter is reduced, the flow rate increases, so the wear rate of the inner wall of the pipe increases. As a result, the problem of early wear of the sludge line occurs.
Therefore, it is also unsuitable to reduce the diameter of the sludge line and provide the necessary resistance.

Further, there is a technique for connecting and extending a large number of U-shaped pipes to the muddy water pipe to provide friction loss resistance to the mud drain line.
However, there is a limit to the allowable space for the sludge line, which is not realistic.

In order to cope with the above-mentioned problem, the applicant firstly installed a fluid pump in the fluid conveyance conduit, and the discharge direction of the pump is opposite to the flow direction of the conveyance fluid, and A fluid conveyance resistance device configured so that the discharge flow rate of the pump is variable has been proposed (see Patent Document 1).
Although such a technique is useful, there is a demand for further improvement.

JP 2008-291800 A

  The present invention has been proposed in view of the above-described problems of the prior art, and even if the transport head in the fluid transport pipe for transporting a fluid containing solid matter fluctuates rapidly, the fluid transport pipe It aims at providing the piping resistance apparatus which can maintain the flow volume of a path | route constant.

  The piping resistance device (4) of the present invention is interposed in the region between the mud pump (Po) and the water treatment facility (3) of the mud line system (Lo), and branches from the mud line (Lo). And having a branch pipe (Lb) that joins the region of the mud pump (Po) side from the branch point (B1), and a circulation pump (Pb) interposed in the branch pipe (Lb). .

In the present invention, the number (of the piping resistance device 4) interposed in the sludge line system (Lo) is the number that produces resistance equal to or greater than the reduction in total head on the sludge pump (Po) side. preferable.
Here, in the pipe resistance device (4) of the present invention, when the face water pressure suddenly rises and the head is temporarily lowered, the drainage pipe head is insufficient and the mud pump (Po) cannot be controlled. It is preferable to install when the excavation position (face position X) is steep (the difference in height is higher than the pipe resistance head) and upward (uphill).

According to the present invention having the above-described configuration, the discharge flow rate of the mud pump (Po) can be reduced with the same head. And the discharge flow rate of the mud pump (Po) can be given a margin by the decrease.
Since the discharge flow rate of the mud pump (Po) can be given a margin, according to the present invention, when the groundwater level on the mud pump (Po) side is high, or the resistance on the downstream side of the mud pump (Po). Even when the head of the mud pump (Po) fluctuates, such as when the flow rate is small, the flow rate of the mud line (Lo) can be kept constant.

  According to the present invention, it is not necessary to reduce the opening degree of the valve interposed in the mud discharge line (Lo), and it is not necessary to reduce the pipe diameter. As a result, solids (such as gravel and crushed rock) in the mud are caught between the valve and the valve seat, closing the part where the valve is interposed, Blocking the mud line is prevented.

Furthermore, according to the pipe resistance device (4) of the present invention, the suction head (Pbi) of the circulation pump (Pb) interposed in the branch pipe (Lb) has a water head (branch) on the mud discharge line (Lo) side. The water head at the point B1 acts so as to push muddy water from the branch point (B1) to the suction side (Pbi) of the circulation pump (Pb).
Therefore, the water head (the water head at the branch point B1) roughly cancels out the water head (the water head at the junction point e) on the drainage line (Lo) acting on the discharge side (Pbo) of the circulation pump (Pb).
Thereby, it is not necessary to select a pump having a large discharge head larger than the head of the junction (B2) as the circulation pump (Pb), and a pump having a small discharge head is sufficient. And the introduction cost of this invention can be restrained low.

It is a schematic diagram which shows embodiment of this invention. It is a schematic diagram which shows the principal part of embodiment. It is a schematic diagram for demonstrating the relationship between the total head and the flow volume of a sludge discharge line. It is a schematic diagram for demonstrating the working principle of this invention. It is a characteristic view which shows the relationship between the total head described in FIG. 4, and flow volume. FIG. 6 is a characteristic diagram similar to FIG. 5, showing the relationship between the total head and flow rate when the characteristics of the auxiliary pump are different from those in FIG. 5. It is a figure which shows the outline | summary of a muddy water shield construction. In a muddy water shield construction, it is a figure which shows the state where a groundwater level is high and a high pressure acts on a mud pump. It is a figure which shows the state with small resistance of a mud drain line in a muddy water shield construction.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 and 2 schematically show an embodiment of the present invention, FIG. 1 schematically shows an outline of a muddy water shield construction to which the embodiment is applied, and FIG. 2 shows a pipe resistance device according to the embodiment. This is shown schematically.

In the muddy water shielding apparatus generally designated by 100 in FIG. 1, the shield machine 2 exists on the face side of the excavation hole (lateral hole) Th (the tip side of the excavation hole Th: the left end in FIG. 1), and on the ground Gf side. The muddy water adjustment tank 1 and the muddy water treatment facility 3 are installed.
The ground Gf and the start point of the excavation hole Th are connected by the hole Tv.
The shield machine 2 has an excavation part 2A having an excavation bit (not shown) on the face side and a face chamber 2C on the back side of the excavation part 2A.

The muddy water adjustment tank 1 and the face chamber 2C are communicated with each other by a mud feed pipe (hereinafter referred to as a mud feed line) Li provided with a mud feed pump Pi.
The mud feeding line Li has a line Li1 and a line Li2. The line Li1 connects the muddy water adjusting tank 1 and the injection side Pii of the mud pump Pi. Line Li2 connects the discharge side Pio of the mud pump Pi and the face chamber 2C.

The face chamber 2C and the water treatment facility 3 are communicated with each other through a sludge line Lo (hereinafter referred to as a sludge line) Lo with a sludge pump Po interposed therebetween.
Referring also to FIG. 2, the mud discharge line Lo has a line Lo1 and a line Lo2. The line Lo1 connects the face chamber 2C and the injection side Poi of the mud pump Po. The line Lo2 connects the discharge side Poo of the mud pump Po and the water treatment facility 3.

A pipe resistance device 4 is interposed in the line Lo2. The pipe resistance device 4 includes a branch pipe Lb that is branched from the line Lo and a circulation pump Pb that is interposed in the branch pipe Lb.
In other words, a branch point f is formed on the line Lo2 on the water treatment facility 3 side, and a junction point e is formed on the drainage pump Po side. The branch point f and the junction point e communicate with each other through a branch pipe Lb with a circulation pump Pb.
The branch pipe Lb has a line Lb1 and a line Lb2.
Line Lb1 connects branch point f and injection side Pbi of circulation pump Pb, and line Lb2 connects discharge side Pbo of circulation pump Pb and junction point e.

In the illustrated example, only one pipe resistance device 4 interposed in the mud discharge line Lo is shown for the sake of convenience. However, the number of pipe resistance devices 4 that generates resistance equal to or greater than the total head reduction on the mud pump Po side is shown. It is said. As for the number of the mud pumps Po, only one unit is shown in FIGS. 1 and 2, but a plurality of units may be provided.
Here, the piping resistance device 4 has a sharply rising face water pressure, and various loss heads are relatively temporarily lowered, or the excavation hole has a steep slope (a slope where the height difference exceeds the pipe resistance head). It is preferably installed when the excavation position (face position) becomes higher and the head on the face side becomes larger when heading upward (uphill slope). In particular, it is effective to install the pipe resistance device 4 when the discharge flow rate of the mud pump Po becomes uncontrollable.

Hereinafter, referring to FIGS. 3 to 6, if the piping resistance device 4 according to the illustrated embodiment is used in the same head, the discharge flow rate is reduced even if the head of the mud pump Po is the same. explain.
Here, if the discharge flow rate of the mud pump Po decreases at the same head, the discharge flow rate of the mud pump Po can be afforded by the decrease. With such a margin, if the piping resistance device 4 of the illustrated embodiment is used, the flow rate of the sludge line Lo can be kept constant even if the resistance head is very small with respect to the head on the face side. .

FIG. 3 schematically shows a model for obtaining the discharge flow rate Q with respect to the total head H.
In FIG. 3, the code | symbol 6 has shown the virtual water tank (for example, slurry tank).
In FIG. 3, the total head H = 100 m, the inner diameter D of the pipe (6 inch pipe) D = 0.1552 m, the length L = 130 m, the pipe friction loss coefficient (λ) = 0.2, and the inside of the sludge line Lo. It is assumed that a fluid flow with a flow velocity v = 10.5 m / s (at point B) occurs and the flow rate Q is Q = 11.9 m ³ / min. In this case, the calculation of the flow velocity v and the flow rate Q is performed when the fluid is fresh water.
The following explanation is based on the premise that the concentration of mud water (mud concentration) is thin and can be handled roughly the same as fresh water.
Here, when soil and sand are contained and the concentration of mud is high, the total head H has an element of liquid specific gravity, and the pipe friction loss head is larger than that in the case of fresh water. Since the friction loss head is large, the control by the mud pump Po is easy, so that the above-described problems hardly occur. Therefore, consider the case of fresh water with a small friction loss head.

In FIG. 4 which simplified the mud pipe system in the muddy water shield construction, the branch pipe Lb branches at the point f (branch point) of the main pipe (corresponding to the mud line in FIGS. 1 and 2) Lo. e is joined to the main pipe Lo. A pump (an auxiliary pump Ps when fresh water is supplied from the external water tank 7 and a circulation pump Pb when fresh water is sucked only from the main pipe Lo) is interposed in the branch pipe Lb.
The pump (auxiliary pump in the illustrated example) Ps has a suction side closer to the point C that is the outlet of the main pipe Lo, and is closer to a point A that is a connection point between the slurry tank 6 and the main pipe Lo. Is the discharge side. The branch point f close to the point C is located at a distance so as not to suck air from the point C open to the atmosphere.

Here, the branch pipe Lb has a line Lb1 and a line Lb2. The line Lb1 connects the branch point f to the suction side of the auxiliary pump Pb (or the circulation pump Pb), and the line Lb2 connects the discharge side of the auxiliary pump Pb (or the circulation pump Pb) to the junction e. is doing.
Further, the suction side of the auxiliary pump Pb (or the circulation pump Pb) communicates with the external water tank 7 through a line L7 having an on-off valve 9 interposed therebetween.
A suction valve 8 is interposed in the line Lb1, and a discharge valve 10 of the auxiliary pump Ps is interposed in the line Lb2.
In FIG. 4, the branch point f is located in the vicinity of the outlet (point C) of the main pipe, the junction point e is in the vicinity of point A (the outlet of the slurry tank 6), and the distance from point A to point C. The distance l between the junction point e and the branch point f is approximately equal (L≈l).

At point B in FIG. 3, the total head H is the pipe friction loss head hf from point A to point B, the speed head hv (= v ² / 2g: gravity acceleration g = 9.8 m / s ² ), and the pressure head. (Or hydrostatic head) is the sum of hp (H = hf + hv + hp).
At point C, which is the outlet, the pressure head hp = 0,
H = hf + hv = hf + v ² / 2g
Substituting the numerical values of the parameters (D, L, λ, g) described above, H = hf + v ² /2g=0.703×Q ²
here,
D is the inner diameter of the main pipe Lo,
L is the length dimension of the main pipe Lo,
λ is the friction loss experimental coefficient,
g is a gravitational acceleration.
A plot of this expression on the (Q, H) coordinates is a quadratic curve (broken line) y1 in FIG.

In FIG. 4, the case where the suction side Psi of the pump Ps interposed in the branch pipe Lb is connected to the external water tank 7 and the pump is used as the auxiliary pump Ps is considered.
The reason why the water source is the external water tank 7 is that, as will be described later, the calculation when the pump (circulation pump Pb) is interposed in the branch pipe Lb branched from the main pipe Lo becomes complicated. . In other words, the piping resistance device 4A having the external water tank 7 as shown in FIG. 4 is shown for explanation of the operating principle of the illustrated embodiment, and is not an embodiment of the present invention. .

In this case, the suction valve 8 is closed, and the suction side Psi of the auxiliary pump Ps does not communicate with the branch point f in the main pipe Lo. The on-off valve 9 interposed in the line L7 is open, and the suction side Psi of the auxiliary pump Ps communicates with the external water tank 7.
In such a case, if two auxiliary pumps Ps and a sludge pump Po are operated simultaneously (parallel operation), and the discharge flow from the auxiliary pump Ps and the flow of the sludge pump Po merge at the junction e, Compared to when the auxiliary pump Ps or the mud pump Po is operated alone, the discharge flow rates of the auxiliary pump Ps and the mud pump Po are reduced.
Hereinafter, referring to FIG. 4 to FIG. 6, compared to when the auxiliary pump Ps or the mud pump Po is operated alone, each of the auxiliary pump Ps and the mud pump Po is discharged in parallel operation. The decrease in the flow rate will be described.

In FIG. 5, a characteristic curve y2 shows the characteristics of the head H and the discharge flow rate Q when the auxiliary pump Ps using the external water tank 7 as a water supply source is operated alone. Characteristic curve y2 shows pipe friction loss from the outlet characteristic of auxiliary pump Ps to the junction e between the outlet of external water tank 7 and main pipe Lo and branch pipe Lb (in FIG. The line L7 connecting the mechanical pump suction side Psi and the pipe friction loss head in the branch pipe Lb2 are reduced.
The characteristic between the head H and the discharge flow rate Q when the sludge pump Po is operated alone is a characteristic curve y3. In FIG. 4, since the slurry tank 6 is directly connected by the mud pump Po and the mud feed pipe Loi and is pressure-controlled, the characteristic curve y3 shows that the mud mud from the characteristics when the mud pump Po is operated alone. The characteristic which reduced the mud feed pipe friction loss head from the pump discharge port Poo to the point e in FIG. 4 and the various loss heads in the slurry tank 6 is shown.

Here, the flow rate from the outlet C when the auxiliary pump Ps using the external water tank 7 as the water supply source is operated alone is indicated by the intersection P5 between the curve y2 and the curve y1 in FIG. 5 (= 10.6 m ^3). / Min).
The pump Ps interposed in the branch pipe Lb is indicated as “auxiliary pump” when the external water tank 7 is used as a water supply source as shown in FIG. 4, and in FIG. When the pipe Lb1 is connected to the branch point f of the main pipe Lo (or when it is configured as shown in FIGS. 1 and 2), “circulation pump” Pb is displayed.

In FIG. 4, when the discharge valve 10 of the auxiliary pump Ps is closed, the total head of the slurry tank 6 is set to 100 m 2, and the sludge pump Po is operated alone, as described above with reference to FIG. The discharge flow rate Q from the discharge port C is 11.9 m ³ / min.
Here, the flow rate 11.9 m ³ / min from the discharge port C when the mud pump Po is operated alone is indicated by the intersection P 4 between the curve y ³ and the curve y 1.
When the auxiliary pump Ps whose characteristic at the point e is the curve y2 in FIG. 5 is started and the discharge valve 10 of the auxiliary pump Ps is opened, the sludge pump Po and the auxiliary machine at the junction e (FIG. 4). The pump Ps is operated in parallel.
The characteristic of the sludge pump Po and the auxiliary pump Ps operating in parallel is indicated by a curve y4 in FIG. Such a curve y4 can be obtained from the sum of the discharge flow rate of the auxiliary pump Ps and the discharge flow rate of the mud pump Po at the same head.

The flow rate at the outlet (point C in FIG. 4) when the sludge pump Po and the auxiliary pump Ps are operated in parallel is obtained at the intersection P3 between the curve y4 and the curve y1 in FIG. 5, and is 12.5 m ³ / min. It is.
The flow rate 12.5 m ³ / min at the intersection P ³ is higher than the flow rate 11.9 m ³ / min from the outlet C when the sludge pump Po is operated alone.
The flow rate 12.5 m ³ / min at the discharge port (point C in FIG. 4) when the mud pump Po and the auxiliary pump Ps are operated in parallel is the discharge flow rate of the auxiliary pump Ps at the head of the point P1 (at the point P1). The sum of the discharge flow rate) and the discharge flow rate of the mud pump Po at the head of the point P1 (discharge flow rate at the point P2).

When the drainage pump Po and the auxiliary pump Ps are operated in parallel, the discharge flow rate of the auxiliary pump Ps (discharge flow rate at the point P1) is 4.6 m ³ / min, and the auxiliary pump Ps is operated alone. Compared to the discharge flow rate in the case (= 10.6 m ³ / min: flow rate at the point P5), the amount is reduced.
When the mud pump Po and the auxiliary pump Ps are operated in parallel, the discharge flow rate of the mud pump Po (discharge flow rate at the point P2) is 7.9 m ³ / min, and the mud pump Po is operated alone. Compared to the discharge flow rate (= 11.9 m ³ / min: the flow rate at the point P4) in the case of the discharge, the amount is reduced.

That is, by operating the drainage pump Po in parallel with the auxiliary pump Ps, the discharge flow rates of the drainage pump Po and the auxiliary pump Ps are clearly reduced as compared with the case where each is operated independently. And if it is the same flow volume, the water head in the mud pump Po can be enlarged more by carrying out parallel operation of the mud pump Po with the auxiliary machine pump Ps.
Thus, according to the illustrated embodiment, if the flow rate is the same, the mud pump Po (see FIGS. 1 and 2) is operated in parallel with the circulation pump Pb, so that the mud pump Po is operated independently. However, it became clear that the water head could be enlarged.

6 is different from the case where the characteristics of the auxiliary pump Ps are described with reference to FIG. 5 (the discharge flow rate is reduced), but the characteristics of the mud pump Po are described with reference to FIG. In this case, the case where the mud pump Po and the auxiliary pump Ps are operated in parallel is expressed.
In FIG. 6, the characteristic curve of the auxiliary pump Ps is indicated by a symbol y2A, and the characteristic curve of the drainage pump Po is indicated by a symbol y3 as in FIG. And the characteristic curve at the time of carrying out parallel operation of the sludge pump Po and the auxiliary machine pump Ps is shown by the code | symbol y4A in FIG.
In FIG. 6, the flow rate from the outlet C (see FIG. 4) when the auxiliary pump Ps is operated alone is indicated by the intersection P5A between the curve y2A and the curve y1.
The flow rate (11.9 m ³ / min) from the discharge port C when the sludge pump Po is operated alone is the intersection P4 between the curve y3 and the curve y1, as in FIG.

The flow rate from the outlet C when the mud pump Po and the auxiliary pump Ps are operated in parallel is an intersection P3A between the curve y1 and the curve y4A.
As described with reference to FIG. 5, the characteristic that the drainage pump Po and the auxiliary pump Ps are operated in parallel is the sum of the discharge flow rate of the auxiliary pump Ps and the discharge flow rate of the mud pump Po at the same head. As obtained. The discharge flow rate of the auxiliary pump Ps having the same head as that when the drainage pump Po and the auxiliary pump Ps are operated in parallel is indicated by a point P1A in FIG. 6, and the discharge flow rate of the waste mud pump Po is indicated by a point P2A. It is shown in
When the mud pump Po and the auxiliary pump Ps are operated in parallel, the discharge flow rate of the mud pump Po (discharge flow rate at the point P2A) is 9.6 m ³ / min. Compared to the discharge flow rate (7.9 m ³ / min) of the sludge pump Po (when the mechanical pump Ps is operated in parallel), the increase is found.
However, it is lower than the discharge flow rate (11.9 m ³ / min) when the sludge pump Po is operated alone.

As a result of the decrease in the discharge flow rate of the auxiliary pump Ps, the circulation flow rate (the flow rate at the point P3A) in the case where the drainage pump Po and the auxiliary pump Ps are operated in parallel is compared with the case where the discharge pump Po is operated alone. Slightly increase. However, the discharge flow rate of the sludge pump Po (discharge flow rate at the point P2A) is reduced as compared with the case of the single operation of the sludge pump Po.
From this, if the characteristics of the auxiliary pump Ps change, the discharge flow rate of the mud pump Po when the mud pump Po and the auxiliary pump Ps are operated in parallel is compared with that when the mud pump Po is operated independently. It can be seen that the rate of decrease changes.
It is also understood that the rate at which the discharge flow rate of the mud pump Po decreases can be adjusted by the characteristics of the auxiliary pump Ps.

3 to 6, when the water supply source includes an auxiliary pump Ps which is an external water tank 7 (in FIG. 4, the on-off valve 9 is open and the suction valve 8 is closed). 1 and 2, as shown in FIGS. 1 and 2, the circulation pump Pb is connected to the branch pipe (line Lb1, line Lb2 in FIG. 4) branched from the sludge line (main pipe in FIG. 4) Lo. The same can be said when the external water tank 7 is not provided (when the suction valve 8 is open and the on-off valve 9 is closed in FIG. 4).
That is, when the circulation pump Pb is operated in parallel with the mud pump Po (see FIGS. 1 and 2), the discharge flow rate of the mud pump Po is reduced as compared with the case where the mud pump Po is operated alone. . And if it is the same flow volume, the water head in the mud pump Po can be enlarged more by carrying out the parallel operation of the circulation pump Pb and the mud pump Po.

As described above, the reason why the water source is the external water tank 7 in FIGS. 3 to 6 is to simplify the calculation, and the pipe resistance device 4A having the external water tank 7 as shown in FIG. It is not a form.
More specifically, as shown in FIGS. 1 and 2, when a circulation pump Pb is interposed in a branch pipe (Lb in FIG. 4) branched from a sludge line (main pipe in FIG. 4) Lo, A pipe friction loss head from the branch point f of the main pipe Lo to the outlet C in FIG. 4 is further generated.
Moreover, if the water supply source of the auxiliary pump Pb is set to the external water tank 7, the flow rate increases by the amount of the flow from the external water tank 7, and the problem to be solved is promoted (the flow rate of the muddy water flowing through the waste mud line Lo). Will increase).

Here, when the circulation pump Pb is installed in the branch pipe Lb (in the case of FIGS. 1 and 2: the external water tank is not used as the water supply source: in FIG. 4, the suction valve 8 is open and the on-off valve 9 is closed. And the auxiliary pump Ps (when described with reference to FIG. 4: when the suction valve 8 is closed and the on-off valve 9 is opened in FIG. 4) and the circulation pump Pb The water head of the auxiliary pump Ps will be described.
When the circulation pump Pb is interposed (in the case of FIGS. 1 and 2: the external water tank 7 is not used as a water supply source: the suction valve 8 is open and the on-off valve 9 is closed in FIG. 4) 4, the head Hc of the circulation pump Pb is the pipe friction loss head at the branch point f−the auxiliary pump Ps−the junction e in FIG. 4 (the pipe friction loss head at the circulation flow rate of the circulation pump Pb = 4.6 m ³ / min). ) And the pipe friction loss head of the branch point e to the junction point f (the sum of the discharge flow rates of both the sludge pump Po and the circulation pump Pb = 1 pipe friction loss head at 12.5 m ³ / min).
That is, the head Hc of the circulation pump Pb is Hc = H1 + H2.
H1: Piping friction loss water head of line Lb1 and line Lb2 (4.6 m ³ / min)
H2: Piping friction loss head from the junction e to the branch point f in the main pipe Lo (12.5 m ³ / min)
It becomes.

On the other hand, the head of the auxiliary pump Ps when the auxiliary pump Ps is interposed (in the case described with reference to FIG. 4: when the suction valve 8 is closed and the on-off valve 9 is opened in FIG. 4). Hs is the piping friction loss head of the line L7 and the line Lb2 (circulation flow rate of the auxiliary pump Ps only = pipe friction loss head at 4.6 m ³ / min), the pressure head at the confluence point e, and the confluence points e to point. the sum of the C pipes frictional head loss (pipe friction head losses in the sum = 12.5 m ³ / min of discharge flow rate of the auxiliary pump Ps both hydro pump Po).
The head Hs (m) of the auxiliary pump Ps is Hs = H3 + H4 + H5
H3: Piping friction loss water head of line L7 and line Lb2 (4.6 m ³ / min)
H4: Pressure head of the confluence point e H5: Piping friction loss head of the confluence point e to point C (12.5 m ³ / min)
It becomes.

Here, in FIGS. 3 to 6, the characteristics of the auxiliary pump Ps using the external water tank 7 as the water supply source are the characteristics at the junction e. As is clear from FIG. 4, the pressure becomes the total head H at the junction e. Therefore, in the characteristics of the head of the auxiliary pump Ps and the discharge flow rate, it is necessary to have a performance equal to or higher than the total head (for example, H = 100 m) at the deadline.
On the other hand, as shown in FIGS. 1 and 2, a circulation pump Pb is interposed in a branch pipe (line Lb1 and line Lb2 in FIG. 4) branched from the sludge line (main pipe in FIG. 4) Lo. In the case where the external water tank 7 is not provided, the water head required for the circulation pump Pb is smaller than that in the case of the auxiliary pump Ps. In the case where the distance between the branch point f and the outlet C in FIG. 4 is relatively long, the pushing pressure by the fluid flowing through the main pipe Lo acts on the suction side of the circulation pump Pb. This is because the indentation pressure and the total head at the point e are roughly offset.

The operational effects of the embodiment shown in FIGS. 1 and 2 will be described by way of example.
[Example]
As a specific example, a case where the face pressure P is increased from 100 KPa to 1000 KPa will be described.
Height difference = 32m, shield center depth Hc = 0.0m, treatment discharge height h = 10.0m from ground surface (GL), total resistance loss head of drainage pipe Hf2 = 510.8m, drainage pipe Resistance loss head per Lom hf2 = 0.118 and slurry coefficient δ = 1.399.
In such a case, if the pressure P of the face is 100 KPa, the total drainage pump Po total head TH2 is TH2 = Hf2 + Hc + h − {(P / 9.8) / δ} −height difference = 510.8 + 0.0 + 10.0 − {( 100 / 9.8) /1.339} -32
= 481.3m
It became.

When the pressure P of the working face is increased to 1000 KPa, the sludge pump Po total head TH2A is
TH2A = Hf2 + Hc + h − {(P / 9.8) / δ} −height difference = 510.8 + 0.0 + 10.0 − {(1000 / 9.8) /1.339} −32
= 412.7m
It became.
That is, when the pressure P of the face fluctuated from 100 KPa to 1000 KPa (pressure increase), the water head decreased by 68.6 m.
In order to compensate for the water head (68.6 m), which has been reduced by changing (increasing) the pressure P of the face from 100 KPa to 1000 KPa, by adding a horizontal pipe, 68.6 ÷ 0.118 (hf2) It was necessary to add a pipe with a length of 581.2m.

In the pipe resistance device according to the illustrated embodiment, the pipe diameter of the mud pipe (the junction point e to the branch point f of the main pipe Lo in FIG. 4) in the pipe resistance device 4 is equal to the other mud line, and the branch pipe If the pipe diameter of Lb is set to 3 times the mud drain line Lo, the flow rate Qp = 8.2 m ³ / min in the mud pipe in the pipe resistance device 4 and the pipe flow velocity Vp = 17.41 m / s per meter Resistance loss head hfp = 2.169.
Further, the flow rate Qh = 6.5 m ³ / min in the branch pipe Lb (Lb1, Lb2) in the pipe resistance device 4 and the pipe flow velocity Vh = 1.53 m / s, the resistance loss head per meter hfh = 0.008. It was.
If the circulation pump head Hh = 43.8 m, the required sludge pipe length Lx in the pipe resistance device 4 was 20.1 m {= 43.8 / (hfp + hfh)}.
The resistance (water head) in such a pipe resistance device is 20.1 m × 2.169 = 43.6 m
It became.

In order to compensate for the resistance corresponding to the water head of 68.6 m which is reduced by increasing the pressure P of the face using the embodiment of FIGS. 1 and 2, two pipe resistance devices shown in the figure are prepared. It will be good.
68.6 / 43.6 = 1.6
1.6 <2
Since the total length of the exhaust pipes of the two pipe resistance devices was 40.2 m, the reduced water head could be compensated for in a much smaller space than when horizontal pipes were added.

In the above-described embodiment, the case where the reduced water head is compensated by the pipe resistance device 4 when the pressure at the face sharply increases has been described.
However, the pipe resistance device 4 shown in FIG. 1 and FIG. 2 also applies to the case where the excavation hole Th has an upward slope, the face side is positioned upward, and the total head of the mud pump Po decreases. Need only be provided in a number that provides resistance more than that corresponding to the reduced total drainage pump Po total head.

Here, in the piping resistance device 4 shown in FIGS. 1 and 2, it is not necessary to reduce the opening degree of the valve interposed in the mud discharge line Lo. For this reason, solids (such as gravel and crushed rock) in the mud are caught between the valve and the valve seat, the valve becomes inoperable, and the mud system is not blocked.
Similarly, according to the pipe resistance device 4 shown in FIGS. 1 and 2, it is not necessary to reduce the pipe diameter in the sludge system Lo. Therefore, it is prevented that the solidified part in the muddy water becomes a lump and is caught in a part where the diameter of the exhaust mud line Lo is small and the part is blocked.

Furthermore, in the piping resistance device 4 shown in FIGS. 1 and 2, the water head on the drainage line Lo side (water head at the confluence point e) acts on the discharge side of the circulation pump Pb interposed in the branch pipe Lb. The water head at the junction point e is roughly offset from the water head (water head at the branch point f) that acts as a force for pushing from the branch point f to the suction side of the circulation pump Pb.
For this reason, the discharge head of the circulation pump Pb is not required to be larger than the head of the junction e.

  The illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Sewage adjustment tank 2 ... Shield machine 2A ... Excavation part 2C ... Face chamber 3 ... Sewage treatment equipment 4 ... Pipe resistance device 6 ... Slurry tank 7 ... External Water tank 8 ... Suction valve 9 ... Open / close valve 10 ... Discharge valve e ... Junction point f ... Branch point Pi ... Mud pump Po ... Mud pump Th ... Excavation Hole

Claims (2)

  A branch pipe that is interposed in the area between the sludge pump and the water treatment facility of the sludge line system, branches from the sludge line, and joins the area on the side of the sludge pump from the branch point, and is installed in the branch pipe And a circulating resistance pump.   2. The piping resistance device according to claim 1, wherein the number of intervening sludge line systems is a number that produces a resistance equal to or greater than a decrease in the total head of the sludge pump.

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