JPH0599709A - Method and device for measuring flow rate of mud and earth transported under pressure - Google Patents

Abstract

PURPOSE:To accurately measure the flow rate of fluidized mud and earth transported through a pipe under pressure in real time. CONSTITUTION:Vibration sensors 1 and 2 respectively composed of accelerometers are installed on a measurement pipe 3 through which mud and earth are pneumatically transported under a pressure and the sensors 1 and 2 output the presence/absence of the transportation of the mud and earth to an arithmetic/displaying section 4. At the section 4, the transporting speed of the mud and earth is found from the time difference between the time T1 at which the first sensor 1 detects the commencement of vibrations of the sensor 1 which occur when the mud and earth come into contact with the sensor 1 and the time T2 at which the second sensor 2 detects the commencement of vibrations of the sensor 2 which also occur similarly and the distance L between the sensors 1 and 2 and the flow rate of the mud and earth is measured from the time T3 which elapses until the tail of the lumped mud and earth passes the first sensor 1, calculated transporting speed, and inside diameter of the pipe 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-fed mud for measuring the flow rate of mud in a fluidized state such as "anko" as well as being pressure-fed by compressed air in a pipe mainly in a plug flow. Flow rate measuring method and device.

[0002]

2. Description of the Related Art In recent years, as a dredging method for the sea bottom, lake bottom, rivers, etc., a pressure feeding method has been known in which dredged mud is pressure fed through a pressure feeding pipe provided over a long distance by using compressed air.

[0003] In this system, in order to efficiently pump mud in a pipe, for example, in a pumping tank to which compressed air for pumping is supplied, or before the mud is supplied to the pumping tank, the mud is stirred by a stirring means or the like. It is fluidized in the shape of an anko. In addition, an injection pipe for a solidifying agent that solidifies the mud is attached in the middle of the pressure-feeding pipe, the solidifying agent is mixed into the mud during the pressure-feeding, the mud discharged from the pressure-feeding pipe is appropriately solidified, and water seeps at the dumping site. There is no secondary pollution, such as taking out.

[0004] The mud transferred in the pressure feed pipe exhibits various flow patterns mainly due to plug flow and the like, so that the injected solidifying agent is uniformly mixed into the mud. The injection control of the solidifying agent is controlled so that a fixed amount of the solidifying agent is injected into the pressure feeding pipe by measuring the flow rate of the mud.

By the way, the flow rate measurement of the pressure-fed mud is a batch type measurement method, that is, at the inlet or the outlet of the pipe end, because the mud is a complicated flow with various styles, mainly plug flow in the pressure-fed pipe. At present, it depends on volume measurement such as measuring cells.

Although a method using ultrasonic waves or an electromagnetic sensor has been proposed as a method for measuring the flow rate of mud in real time, it cannot be accurately detected because it causes malfunction due to mud particles floating in the pipe. It was

Therefore, there is a problem that it is impossible to inject the solidifying agent at an optimum ratio to the mud continuously pumped and having different flow rates.

[0008]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to perform in real time an accurate flow rate measurement of mud that is pressure-fed in a pipe exhibiting various flow patterns, mainly plug flow. There is something that cannot be done.

[0009]

Means and Actions for Solving the Problems A method for measuring the flow rate of mud sent under pressure in order to solve the problems of the present invention is such that the passage of mud under pressure is detected at two different points. It is characterized in that the flow rate of the pressure-fed mud is detected based on the distance between the sensors, the pipe diameter, the mud passage time between both sensors, and the time until the mud passes through the detection.

Further, a flow rate measuring apparatus for pressure-fed mud for solving the problems of the present invention is a contact-type device provided along a pressure-feeding direction of mud with a predetermined interval in a measurement pipe through which mud is pressure-fed. The vibration sensor and the time difference at which these vibration sensors start detecting vibration due to contact with mud and the sensor interval determine the pumping speed of the mud, and the time from the start of vibration detection to the end, the pumping speed and the measuring pipe. And a calculation means for calculating the flow rate of the mud pumped by the inner diameter of the.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of a flow rate measuring device for pumped mud which can effectively carry out the method of the present invention.

In the flow rate measuring device according to the present embodiment, a first vibration sensor 1 and a second vibration sensor 2 are attached to a measuring pipe 3 having a diameter d for pumping mud with a predetermined distance L. The detection signals of the first vibration sensor 1 and the second vibration sensor 2 are output to the calculation display unit 4 including a microcomputer or the like.

First sensor 1 and second sensor 2
As shown in FIG. 2, is a vibrometer body 10 that is an accelerometer.
The sensor rod 11 is fixed to the sensor rod 11, the sensor rod 11 is inserted into the measuring pipe 3, and the disk-shaped flange portion 12 formed on the base side of the sensor rod 11 is formed of an elastic member such as rubber on the front and back sides. Rings 13 and 14 are provided respectively, and the hold rings 15 and 16 elastically float and hold the vibrometer body 10 and the sensor rod 11 via the O-rings 13 and 14, respectively.

The hold rings 15 and 16 are fixed by a bolt 17 and a nut 18, and the measuring pipe 3
The mounting flange 19 fixed to the holding ring 1
It is fastened together with 6 by bolts and nuts, and the vibration sensor is attached to the measuring pipe 3. Also, the sensor rod 1
The portion inserted in the pipe 1 is inclined along the flow direction, and its surface is subjected to a ceramic coating treatment in order to prevent abrasion due to contact with the pumped mud. The insertion depth of the sensor rod 11 is approximately up to the center of the pipe in order to make sufficient contact with the pressure-fed mud and enable high-sensitivity vibration detection.

In the vibration sensor thus constructed, when the sensor rod 11 detects the mud pressure-fed in the measuring pipe 3,
The vibrating meter body 10 vibrates with the flange portion 12 as a substantially fulcrum.
Detects vibration and outputs a vibration detection signal.

In this case, the measuring pipe 3 is connected to the pressure feeding pipe. In this embodiment, as shown in FIG. 3, the measuring pipe 3 is connected to the pressure feeding pipe 20 via the flexible tube 21 made of rubber, and pressure feeding is performed. The vibration from the pipe 20 is prevented from being transmitted to the measuring pipe 3.

Next, the flow rate detecting operation of this embodiment will be described.

The interval L between the first vibration sensor 1 and the second vibration sensor 2 and the diameter (inner diameter) d of the measuring pipe 3 are input to the calculation display unit 4 in advance.

When the pumped mud reaches the first vibration sensor 1 at time T ₁ as shown in FIG. 1 (A),
The first vibration sensor vibrates and outputs the first detection signal to the calculation display unit. The calculation display unit 4 waits for the second detection signal from the second vibration sensor 2 to be input next.
As shown in (B) of FIG. 1, when the mud that has passed through the first vibration sensor 1 reaches the second vibration sensor 2, the second detection signal from the second vibration sensor 2 also causes the second detection signal at time T. ₂
Is output to the calculation display unit 4.

The calculation display unit 4 calculates the flow velocity V of the mud according to the following equation (1) and displays this value.

V = L / (T ₂ −T ₁ ) ... Equation (1) Further, as shown in FIG. 1B, a mass of mud passes through the first vibration sensor 1, that is, When the vibration of the first vibration sensor 1 stops at time T ₃ , the flow rate (Q) of the mud pumped during that time is calculated according to the following equation (2), and this value is displayed on the display unit.

[0022] ^{Q = (π · d 2/} 4) × V × (T 3 -T 1) ··· Equation (2) therefore together that may be implanted solidifying agent to the flow (Q) of the mud become.

Then, the integrated flow rate Q'is obtained from Q '= ΣQ.

[0024]

As described above, according to the present invention,
The vibration sensor vibrates due to the contact with the mud pumped in the pipe and detects that the mud is being transferred, but the fact that the mud is not contacted during the operation is only a small moment due to the flow condition of the mud. Even if it occurs, since the vibration sensor continues to vibrate, it is possible to accurately detect the flow rate of the pumped mud flowing in a complicated manner without malfunctioning.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a flow rate measuring device for pumped mud according to the present invention.

FIG. 2 is a sectional view showing an example of a vibration sensor.

FIG. 3 is a side view showing a mounting state of the measuring pipe.

[Explanation of symbols]

 1, 2 ... Vibration sensor 3 ... Measuring tube 4 ... Calculation display unit 10 ... Vibrometer main body 11 ... Sensor rod 13, 14 ... O-ring

Claims (2)

[Claims] 1. Different passage of mud pumped in a pipe
At the point, the passage of mud is detected by a vibration detection type sensor, and the flow rate of the pressure-fed mud is detected from the distance between the sensors, the pipe diameter, the mud passage time between both sensors, and the time until the mud passes. A method for measuring the flow rate of pumped mud, which is characterized in that 2. A contact-type vibration sensor provided in a measuring pipe to which mud is pumped and having a predetermined interval along the mud pumping direction, and the vibration sensor detects vibration by contact with mud. And a calculation means for calculating the pumping speed of the mud by the time difference for starting and the sensor interval, and calculating the time from the start to the end of vibration detection, the pumping speed and the flow rate of the mud pumped by the inner diameter of the measuring pipe. A flow rate measuring device for pumped mud characterized by the above.