JP3379042B2 - Method and apparatus for injecting improver into sediment transport pipe - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for injecting an improving agent for improving soil quality into a sediment transport pipe for pneumatically transporting sediment generated by dredging work, shield work and the like.

[0002]

2. Description of the Related Art Pneumatic feeding has an advantage of being able to transport relatively high-concentration earth and sand over a long distance, and is widely used for the transportation of dredged earth and sand (see, for example, JP-A-6-30688). By the way, if the soil to be transported is soft mud with a high water content, if it is dumped directly into a mud discharge or a landfill, it will take a long time to dry and solidify, and effective use of the land, environmental protection, etc. In terms of aspects, many problems will be left.

In order to solve the above-mentioned problems, in some cases, a soil-improving agent (cement-based solidifying agent, etc.) is injected into a transportation pipe for pneumatically transporting the sand and transported to a destination. . However, when pneumatically feeding soft mud, as shown in FIG. 2, when compressed air is supplied into the transport pipe 1 through the air supply pipe 2, the sand and sand are subjected to a shearing action and separated in the transport direction A, and the transport pipe 1 An intermittent flow of the plug 3, that is, a so-called plug flow is formed therein. Therefore, if the improver is continuously injected into the transport pipe 1, most of it is supplied into the air layer 4 between the plugs 3, and it is difficult to inject a predetermined amount of the improver into the earth and sand. Not only that, but the use of useless improvers will increase.

This plug flow appears more clearly as it moves away from the air supply pipe 2 toward the downstream side. Therefore, if the improver is injected near the air supply pipe 2 or upstream from the air supply pipe 2. The problem will be solved. However, in such an injection method, since the viscosity of the earth and sand increases due to the injection of the improving agent, long-distance transportation becomes difficult, and in some cases, the earth and sand solidify during transportation and the transportation pipe 1 is clogged, and thus large-scale maintenance is required. Is needed, and a fundamental solution cannot be reached.

Therefore, for example, in Japanese Unexamined Patent Publication (Kokai) No. 5-112965, a swirl chamber provided with a submersible sand pump consisting of a centrifugal impeller is provided in the middle of a pipeline (transportation pipe) for pneumatically feeding earth and sand, and Connect a measuring device for additive (improving agent) supply to the suction side of the sand pump via a check valve, and respond to changes in the detected value of the current meter or flow meter installed in the conduit away from the volute chamber. A method and an apparatus for operating and stopping the measuring instrument by the above are described. According to this method and device,
By detecting the flow of the plug from the change in the detected value of the current meter or the flow meter and predicting the time until the plug reaches the measuring instrument, it is possible to mix the improver with the sand in a timely manner. Become.

[0006]

However, according to the method of injecting the improving agent described in the above publication, a measuring instrument for supplying the additive is provided from a point in the pipeline where the velocity meter or the flow meter is provided. The time required for the plug to reach the specified point is measured in advance, and the measuring instrument is operated after a predetermined time has elapsed after receiving the detection signal of the flow velocity meter or the flow meter (the gazette, column 2, columns 35 to 35). Therefore, there is a problem that when the flow velocity of the plug changes with time, there is a gap between the operation timing of the measuring instrument and the arrival time of the plug, and the improver cannot be stably mixed in the earth and sand.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a plug
Accurately grasp the flow rate and flow rate to improve the timing of the improver.
It is an object of the present invention to provide a method and an apparatus for injecting a modifier into a sediment transport pipe, which enables a good injection and an appropriate amount of injection .

[0008]

Means for Solving the Problems To achieve the above object, the method of the present invention uses signals from two plug detection means provided in the middle of a transportation pipe for pneumatically feeding earth and sand at intervals shorter than the flow pitch of the plugs. based on determines the flow velocity and flow rate of the plug flowing current, and controlling the injection timing and injection amount of modifier into the transport tube according to the flow velocity and flow rate.

In the method of the present invention, the flow velocity of the plug can be accurately grasped by taking the difference in the detection time of the plug by the two plug detection means provided at a predetermined interval. In addition, according to this plug detection means,
From the change in the physical quantity of the fluid flowing in the pipe,
Detect the time when the plug reaches and passes through the part
Therefore, if you take the difference between the two times, the transportation
Grasping the plug size (flow rate) by correlating with the pipe diameter
can do.

Here, the plug flow formed in the transport pipe is
As described above, the more clearly it moves away from the compressed air supply point in the transportation pipe, the more downstream it becomes. Therefore, the location where the plug detection means is attached and the location where the improver is injected are as close to the end of the transportation tube as possible. Is desirable. In this way, when the plug detection means and the injection point of the improving agent are set in the portion near the end of the transportation pipe, the sediment will be discharged to the destination soon after it solidifies, which will of course hinder long-distance transportation. There is no need to worry about clogging of the transport pipe.

By the way, when a plug flow is generated in the transport pipe, the pressure, flow velocity, flow rate at any portion of the transport pipe,
As a matter of course, the density and the like are different when the plug is flowing and when the air layer is flowing. Further, when the plug flows through an arbitrary portion of the transportation pipe, a large vibration or a loud noise is generated at that portion. Therefore, in the present invention, the sensors for measuring each physical quantity described above, that is, the pressure sensor, the flow velocity sensor, the flow rate sensor, the density meter, the vibrometer, the acoustic measuring instrument, the load meter, etc. can be used as the plug detecting means. In this case, the sensors that measure these physical quantities may be used alone or in combination, and when used in combination, the flow of the plug can be detected more reliably.

Although the present invention does not specify the type of the above-mentioned improving agent, it is desirable to use a material having excellent fast hardening property, for example, a cement-based solidifying agent. Further, as the improving agent, a composite agent obtained by adding a plasticizing agent, a lightening agent, a separation preventing material, an odor eliminating material, a fast strengthening agent, a retarding material, etc. to the solidifying agent can be used.

According to the method of the present invention, as described above,
Based on the signals from the two plug detection means, the current flow
Since the flow velocity and flow rate of the plug that is
Feedback to the injection side of the improver,
However, the required amount of the improver can be reliably mixed.

In the method of the present invention, since the flow rate is calculated in addition to the flow rate of the plug, by controlling the injection amount of the improver according to the flow rate, the improver is uniformly mixed into the earth and sand. It is possible to control the injection amount of the improver in this case by controlling both the injection time and the injection pressure.
Becomes

The apparatus of the present invention is for carrying out the above-mentioned method invention, and is provided with two plug detecting means at a distance shorter than the flow pitch of the plugs in the middle of a transportation pipe for pneumatically feeding earth and sand, and the transportation is performed. An injection nozzle connected to the improving agent supply device through a pipe is attached to a portion of the pipe on the downstream side of the plug detecting means, and an opening / closing device and a pump are attached to the pipe.
And the opening timing and opening of the switchgear based on signals from the two plug detecting means.
A control device for controlling the time and the discharge pressure of the pump is provided. Here, the type of the opening / closing device is arbitrary as long as it has a structure capable of automatically opening / closing the flow path in the pipe, and for example, an electromagnetic valve, a cylinder gate, an electric valve or the like can be used.

In the improving agent injecting device thus constructed, the signals of the two plug detecting means are fetched into the control device to calculate the flow velocity and the flow rate of the plug, and the opening / closing device is operated by the command from the control device. Thus, the optimum amount of the improver can be injected into the transport pipe at the optimum timing.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an improving agent injecting device as one embodiment of the present invention. In the present embodiment, two pressure sensors 10 and 11 are attached at a predetermined interval S in the middle of the transportation pipe 1 for pneumatically feeding the earth and sand, and particularly in a portion near the end thereof, and An injection nozzle 12 is provided on the downstream side of the pressure sensors 10 and 11. Further, a modifying agent supply device 13 is separately installed, and the modifying agent supply device 13 and the injection nozzle 12 are connected by a pipe 14. A pump 15 and an opening / closing device 16 are interposed in the pipe 14, and the injection nozzle 1
2, a predetermined amount of the improving agent having a predetermined pressure is supplied according to the operation of the pump 15 and the operation of the opening / closing device 16. Cement milk is used here as the improving agent, and the improving agent supply device 13 is configured as a milk plant for producing cement milk having a predetermined concentration.

Inside the transport pipe 1, an intermittent flow of the plug 3, that is, a so-called plug flow is formed as shown in FIG. The pressure in the transport pipe 1 is high in the part where the plug 3 is flowing and is low in the part where the air layer 4 (FIG. 2) is flowing. Therefore, the pressure in each cycle is the same as the plug flow. The output signals of the sensors 10 and 11 will change. That is, each pressure sensor 1
From the change in the output signals of 0 and 11, it is possible to know the arrival and passage of the plug 3 to their installation sites. Therefore, the two pressure sensors 10 and 11 function as plug detection means for detecting the flow of the plug 3. It is supposed to do. Therefore, the distance S between the two pressure sensors 10 and 11 is set to be shorter than the flow pitch of the plug 3 (for example, 3 to 8 m). As a result, the flow of the same plug 3 is detected by the two pressure sensors 10 and 11 over time, and the flow velocity of the plug 3 can be obtained by taking the difference between the detection times. Further, from the changes in the output signals of the pressure sensors 10 and 11, the time when the plug 3 reaches and the time when the plug 3 passes through can be detected. The size (flow rate) of the plug 3 can be grasped by the correlation of

Hereinafter, a method for injecting an improving agent by the improving agent injecting apparatus constructed as described above will be described. Now, when one plug 3 of the plug flow formed in the transport pipe 1 reaches the installation site of the upstream pressure sensor 10, the output signal of the upstream pressure sensor 10 changes and the control device 17 Remember the time the signal changed. Thereafter, the plug 3 reaches the installation site of the pressure sensor 11 on the downstream side, which changes the output signal of the pressure sensor 11 on the downstream side. The controller 17 calculates the flow velocity of the plug 3 by taking the difference between the time when the output signal of the downstream pressure sensor 11 changes and the time when the output signal of the upstream pressure sensor 10 changes. The time required for the plug 3 to reach the installation site of the injection nozzle 12 is calculated. The controller 17 also calculates the flow rate (size) of the plug 3 from the change with time of the output signal of the pressure sensor 10 on the upstream side, and at the same time, mixes the modifying agent to be mixed into the plug 3, that is, a predetermined mixing amount. Calculate the amount of modifier injection required to obtain the ratio. The injection amount of this improving agent is the discharge pressure of the pump 15 and the opening / closing device 1.
6 is determined by the opening time (injection time), the control device 17
Is determined by giving priority to the optimum injection time at which the improving agent can be uniformly mixed in the plug 3 of a certain size, and then the discharge pressure for ensuring a predetermined injection amount within the optimum injection time. It is supposed to be decided.

Then, in response to a command from the controller 17, the discharge pressure of the pump 15 is first adjusted, and the opening / closing device 16 is opened at the timing when the plug 3 reaches the installation site of the injection nozzle 12. Thereby, the improving agent supply device 13
The improver pumped from the pipe 14 from the injection nozzle 1
2 is injected into the transport pipe 1, and the improving agent is continuously mixed into the plug 3 flowing through the installation site of the injection nozzle 12. Then, the opening / closing device 16 is closed at the timing when the plug 3 finishes passing through the installation site of the injection nozzle 12.
As a result, the required amount of improving agent is uniformly mixed in the plug 3. Thereafter, the injection control of the improving agent is repeated for each plug 3, whereby the improving agent is uniformly mixed in the earth and sand pneumatically fed in the transport pipe 1 at a predetermined mixing ratio,
Improved sediment will be discharged to destinations such as drainage ponds and landfills. In the present embodiment, in particular, since the improving agent is injected near the end of the transport pipe 1, the improved sediment is discharged to the destination soon after it solidifies, and does not hinder long-distance transportation. Further, there is no concern that the transport pipe 1 will be clogged, but even if the transport pipe 1 is clogged, only the maintenance in the vicinity of the end of the transport pipe 1 will be necessary and the repair will be easy.

[0022]

[0023]

As described above in detail, according to the method and the device for injecting the improving agent into the earth and sand transport pipe according to the present invention, the flow velocity and flow rate of the plug formed by pneumatic feeding can be accurately grasped. As a result, the target plug can be reliably mixed with the required amount of the improving agent, and its utility value is great.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an apparatus for carrying out a method for injecting a modifier to a sediment transport pipe according to the present invention.

FIG. 2 is a cross-sectional view showing a state of a plug flow in a transport pipe formed by pneumatic feeding.

[Explanation of symbols]

1 transport pipe 3 plugs 4 air layer 10, 11 Pressure sensor 12 injection nozzles 13 Improvement agent supply device 14 Piping 15 pumps 16 Switchgear 17 Control device

   ─────────────────────────────────────────────────── ─── Continued front page       (56) Reference JP-A-5-112965 (JP, A)                 Actual Kaihei 7-14321 (JP, U)

Claims (2)

(57) [Claims] 1. A method for injecting an improving agent into a transportation pipe for pneumatically feeding earth and sand based on a signal from two plug detection means attached to the transportation pipe at an interval shorter than a flow pitch of the plug. Injection of the improving agent into the sediment transport pipe, characterized in that the flow velocity and the flow rate of the flowing plug are obtained, and the timing and the injection amount of the improving agent into the transport pipe are controlled according to the flow velocity and the flow rate. Method. 2. An apparatus for injecting an improving agent into a transport pipe for pneumatically feeding earth and sand, wherein two plug detecting means are provided in the middle of the transport pipe at intervals shorter than a flow pitch of the plug, At a portion downstream of the plug detection means, an injection nozzle connected to the improving agent supply device through a pipe is attached, and an opening / closing device and a pump are provided in the pipe.
Further, based on the signals from the two plug detecting means, the opening timing and opening time of the switchgear and the
An improving agent injecting device into a sediment transport pipe, which is provided with a control device for controlling a discharge pressure of a pump .