JP3184999B2 - Flow measurement method of earth and sand plug flow - 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 for measuring the flow rate of a plug and sand flow in real time, which can measure the flow rate of a plug flow when soil and sand are mixed and fed using a pipeline such as a pipeline. Things.

[0002]

2. Description of the Related Art In recent years, as one method of transporting gas, liquid, and solid particles by using pipelines such as pipelines, clay, silt, and the like are utilized by using the expansion force of compressed air. The technique of mixed pressure transportation for transporting earth and sand such as fine sand is used. This mixed-pressure feed generates compressed flow by injecting compressed air into the soil such as soft mud sent out into the pipeline by a vortex pump.
This flow is in a fluidized state in which a mass called a plug in which fluidized earth and sand is shaped like a wave and a layer of compressed air are alternately repeated, and the size of the plug tends to gradually increase.

[0003] When the earth and sand is pumped in the pipeline as described above, if the flow rate of the earth and sand that is actually being pumped can be grasped, the actual soil volume at the time of the earth and sand pumping can be calculated, and the work efficiency can be reduced. Useful to know. On the other hand, electromagnetic flow meters and Doppler velocimeters are generally used as a method for measuring the slurry flow rate of a mixture of water or solid particles and a liquid transported in a pipeline. It is a prerequisite that the flow is flowing.

However, in the plug flow generated by the mixed pressure feed, the plug of the earth and sand and the compressed air layer are alternately repeated, and the earth and sand whose flow rate is to be measured is an intermittent flow. The measurement method cannot be applied.
In addition, in order to measure the flow rate of the conventional plug flow, the above general measurement method is applied to the pipeline section in the slurry transport state before the injection of the compressed air, or the sediment discharged from the pipeline end is used. The amount was measured directly by a measuring tank.

However, in a practical machine of mixed pressure feeding, it is difficult to provide a sufficient run-up section for slurry transportation required by a measuring instrument, and the latter cannot respond to large-volume discharge at all. There is a problem that this method is not sufficient.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and the plug flow can be reduced by simply attaching a simple machine, regardless of the structure of a conventional practical machine. It is an object of the present invention to provide a method for measuring the flow of sediment plugs by real-time measurement capable of measuring a flow rate.

[0007]

In order to achieve the above object, a method for measuring the flow of earth and sand plugs according to the present invention comprises the steps of: The speed Fp of the plug alone is determined from the time difference in the pressure waveform in the pipeline of one plug measured by each pressure gauge provided at one fixed point, and the speed Fp of the plug alone and the speed Fp of the two fixed points are determined. The length Lp of the plug alone is calculated from the time when the plug passes through either of them, and the plug volume Vp at an arbitrary measurement time T obtained from the plug length Lp and the cross-sectional area in the pipe is calculated. By the total ΣVp,
The plug flow rate Qp is obtained by Qp = 求 め る Vp / T.

[0008]

[Operation] According to the above-mentioned measuring method, the fluctuation of the pressure in the pipe of the plug flow is simultaneously measured by two pressure gauges at a predetermined interval in the pipe, and the speed of the plug alone is determined from the time difference of the pressure waveform. The plug flow rate can be calculated by calculating the length and volume of the plug alone from the measurement point passage time of the plug alone and measuring the number of plugs passing through the measurement time.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment to which the method of the present invention is applied will be described below with reference to the drawings. FIG. FIG. 2 is an explanatory diagram showing the movement of the plug in the pipeline of FIG. 1 at each time, and FIG. 3 is a diagram showing the pressure fluctuation of each pressure gauge in the pipeline during the movement of the plug of FIG. FIG. 5 is a relationship diagram between pressure and time shown.

First, FIG. 1 shows an example of dredging earth and sand such as ooze on the sea floor. Is sent out to a pipeline 3 such as a pipeline by a vortex pump 4, and compressed air is injected into the ooze in the pipeline 3 by an air compressor 5, and the plug 3 and the compressed air A are injected into the pipeline 3. A plug flow for mixed-pressure feeding is formed, and the soft mud is pumped to a predetermined landfill 10 or the like.

Therefore, in the vicinity of the discharge port of the pipe 3, FIG.
As shown in the figure, two fixed points at a predetermined interval L (m)
X and Y are provided with pressure gauges 6 and 7, respectively.
Record / analyze each measurement result of pipe pressure by
8 and output to a CRT screen or recording paper. Next
Next, in FIG. 2, the passage of the fixed points X and Y of the plug P alone.
Appears on the pressure wave meter as shown in FIG.
Time difference between the pressure gauges 6 and 7 of the waveform (T_Two-T ₀)
The speed Fp (m / s) of the lag alone is Fp = L / (T_Two−
T₀).

Further, since the time (T ₁ −T ₀ ) in which the plug P alone passes through the fixed point X and the plug flow velocity Fp are known,
The length Lp (m) of the plug alone is Lp = Fp × (T ₁ −T
₀ ). Note that the length Lp of the plug alone can also be obtained from the time when the plug passes through the fixed point Y.
Next, if the sectional area of the pipe 3 is A (m ² ), the plug P
The volume Vp (m ³ ) of a single substance is obtained by Vp = Lp × A.

Therefore, the calculation of each of the above expressions is performed for an arbitrary measurement time T (hr), and the total of the plug volume Vp, that is, ΣVp
, The plug flow rate Qp (m ³ / hr)
Is determined by Qp = ΣVp / T.

[0014]

According to the flow rate measuring method of the present invention described above, it is possible to measure, in real time, the flow rate of the sediment of the plug flow which is fed under a mixed pressure in the pipeline, and to determine the flow rate of the sediment flow during the sediment pumping. There is an effect that the calculation can be performed instantaneously and the work efficiency can be grasped appropriately. Further, the present invention has an advantage that a great effect can be obtained by adding a simple device in which only two pressure gauges are provided in the conduit for the mixed pressure feed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a mixed-pressure feed pipe for feeding soil and mixed-pressure by applying the flow rate measuring method of the present invention.

FIG. 2 is an explanatory diagram showing movement of a plug in a pipeline in FIG. 1 at each time;

FIG. 3 is a relationship diagram between pressure and time showing pressure fluctuation of each pressure gauge in the pipeline when the plug of FIG. 2 is moved.

[Explanation of symbols]

 3 Pipeline 4 Centrifugal Pump 5 Air Compressor 6, 7 Pressure Gauge 8 Recording / Analyzer A Compressed Air P Plug

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shinya Izumi 6-3 Matsuoda Higashicho, Shifuzeki City, Yamaguchi Prefecture Toa Construction Industry Co., Ltd. (56) References JP-A-60-190815 (JP, A) JP-A-60-190815 63-44126 (JP, A) JP-A-5-99709 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 1/00-1/74

Claims (1)

(57) [Claims] 1. In the vicinity of a discharge port of a conduit for sending a mixed pressure of earth and sand,
The speed Fp of the plug alone is determined from the time difference in the pressure waveform in the pipeline of the single plug measured by each pressure gauge provided at two fixed points at a predetermined interval L. , The length of the plug alone Lp is calculated from the time when the plug alone passes through one of the above two fixed points, and an arbitrary measurement obtained from the plug length Lp and the cross-sectional area in the pipeline. The plug flow rate Qp is determined by the sum of the plug volumes Vp at time T, ΔVp, by Qp
= Flow rate measurement method of earth and sand plug flow obtained by ΔVp / T.