JPH0390839A - Method and instrument for measuring turbidity - Google Patents

Abstract

PURPOSE:To take a measurement continuously in real time at a current position under easy maintenance and control by finding an increment in density due to the contamination of a suspended material from measured values of depth, hydraulic pressure, and water temperature at a position to be measured and standard water density. CONSTITUTION:The installation depth values h1 and h2 of hydraulic pressure meters 12 and 14 which are already known and their output signals P1 and P2, and the output signals T1 and T2 of thermometers 16 and 18 are inputted through a converter 20a. Then the interval l between the installation positions of the hydraulic pressure meters 12 and 14 and the hydraulic pressure difference P=P2-P1 are calculated. Those calculated values are used to find the unit volume gammaw of running water from a specific expression. Then the density rhow of fresh water at T2 deg.C is calculated and the density rhow of the running water is also calculated by dividing the unit volume gammaw of the running water by gravitational acceleration g. Then the increment rho in density due to the contamination of the suspended material is calculated from a specific expression and the processing procedure is finished. Consequently, the turbidity is measured continuously in real time at the current position under the easy maintenance and control.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a turbidity measuring method and a turbidity measuring device for determining the degree of turbidity of water.

(Prior Art) As is well known, suspended sediment flows into reservoirs for hydroelectric power generation, drinking water, etc. along with rainwater.

However, when a hydroelectric power plant directly takes in turbid water that contains a considerable amount of suspended sediment, the suspended sediment not only accumulates in waterways and settling basins and obstructs water flow, but also seriously damages water turbines and conduits. become.

For this reason, at present, hydroelectric power plants are taking countermeasures against increased sediment inflow into rivers due to heavy rain, etc. by controlling the amount of water intake by referring to the flow rate of the river.

However, since it is not possible to accurately estimate suspended sediment flowing into a reservoir from the river flow rate, in reality,
This was extremely insufficient as a measure to prevent damage to water turbines caused by the aforementioned suspended sediment.

On the other hand, even in reservoirs for drinking water, the inflow of turbid water significantly pollutes the water in the reservoir, so prompt release is desired. Because there are differences in the concentration of soil and sand, and the distribution of turbid water cannot be accurately determined, the reality is that, like power plants, we are struggling to find countermeasures.

It seems that such a problem can be easily solved by, for example, determining the degree of turbidity in a reservoir (1JllJ) and controlling the water intake and discharge based on that JIIJ fixed value, but this method has been used conventionally. Turbidity measurement method.

The turbidity meter OI device has the following technical problems, particularly when applied to Application 1 as described above (problem to be solved by the invention). For DJ'ing, the suspended sediment contained in sample water taken from the site is separated using filter paper or a centrifuge, the separated suspended sediment is weighed, and the temperature is determined by a laboratory test. One method is to project a light beam onto the sample water and measure the intensity of the transmitted light or scattered light to determine the turbidity.

However, although the former turbidity measurement method can measure the amount of suspended sediment on cobblestones, it cannot be measured in real time at the current location, so it cannot be used for the water intake or water discharge control described above.

On the other hand, with the latter method of measuring turbidity, it is possible to measure in real time at the current location, but if the turbidity is left underwater, there will be sediment accumulation and adhesion. The maintenance and management of the measuring equipment is troublesome, and the color of suspended sediment causes large measurement errors.Moreover, the measurement range is narrow, making it difficult to measure turbidity that contains a large amount of suspended sediment. It was not suitable.

This invention was made in view of these conventional problems, and its purpose is to enable continuous measurement at the current location in real time and measurement over a wide range under easy maintenance and management. An object of the present invention is to provide a turbidity measuring method and a turbidity measuring device that can be used to measure turbidity.

(Means for Solving the Problems) In order to achieve the above object, the turbidity measurement method according to the present invention measures the depth, water pressure, and water temperature at the measurement target position, and uses these measured values and standard water density. The method is characterized in that the amount of increase in density due to the mixing of suspended solids is determined from the above, and the turbidity is determined based on the amount of increase in density.

Further, the turbidity measuring device according to the present invention includes a water pressure gauge installed at a low depth, a thermometer for measuring water temperature, a measured value of the water pressure gauge, and a standard water density in the measured value of the thermometer. and an arithmetic device that calculates the amount of increase in density due to the mixing of suspended solids.

(Operations and Effects of the Invention) According to the turbidity measuring method and device configured as described above, a water pressure gauge and a thermometer are installed in water, and the amount of increase in density due to the mixing of suspended solids is calculated from these measured values and the standard water density. Since the degree of turbidity of the water is determined by calculation, continuous measurement in real time at the current location is possible.

In addition, water pressure gauges generally have a liquid-tight structure, so
There is no influence from the accumulation or adhesion of suspended sediment, and almost no maintenance or management is required.

Furthermore, since some water pressure gauges have various measurement ranges, turbidity can be measured over a wide range by appropriately selecting one according to the amount of suspended solids contained in the water to be measured.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, before describing specific examples of the present invention, the principle of the measuring method of the present invention will be explained.

FIG. 1 is an explanatory diagram of the principle of the measuring method of the present invention. In the figure, when the water pressure at the water depth point is P, the unit weight of flowing water at the same point: γ is expressed by the following formula % formula % On the other hand, The density ρ of flowing water is expressed by the following formula, where g is the gravitational acceleration.

ρ −γ 7g・・・・・・■ v v Now, let Δρ be the increase in suspended solids due to mixing with the density ρ of flowing water, and let ρ be the density of fresh water at the same temperature as the flowing water, then Δρ− ρ −ρ・・・・・・■ v v If the water depth, water pressure P, and water temperature are known, then from these values, the increase in flowing water density due to the mixing of suspended matter Δρ
can be calculated, and the degree of turbidity of the flowing water can be quantitatively measured based on the size of the increase Δρ.

On the other hand, when the particle density of suspended solids is p, the suspended solids f1m in a unit volume of flowing water is expressed by the following formula.

m■ρ ×V S S −ρ × (ρ −ρ ,)XV/(ρ −ρ,
)s v v
s w−ρ
×Δρ/(ρ −ρ5)・・・・・・■S
S v■ =
Volume occupied by suspended solids in a unit volume of flowing water V2 Unit volume Here, since the suspended solid particle density ρ is considered to be approximately constant at the same measurement point, the amount of suspended solids m in a unit volume of flowing water is There is a strong first-order positive correlation with the flow water density increase Δρ due to contamination, and the above equation (2) can be approximated as follows.

m-kX Δρ・・・■■ Thereby, for example, Δρ obtained by the measurement of the present invention
and the results of suspended solids analysis obtained from on-site water sampling.
Alternatively, by actually measuring the density of suspended particulate matter and setting k, the mass m of suspended matter in a unit volume of flowing water can be determined from Δρ.

2 to 4 show an embodiment of the turbidity measuring device according to the present invention.

The turbidity measuring device shown in the figure includes two water pressure gauges 12.14 installed at depths h1 and h2 of the reservoir 10, and two thermometers 12 and 14 for measuring the water temperature at the installation positions of the water pressure gauges 12 and 14.
6.18, and an arithmetic unit 20 through which the outputs of these instruments are input manually.

FIG. 3 shows an example of the water pressure gauge 12.14.

The water pressure gauges 12 and 14 shown in the figure are so-called crystal type water pressure gauges, and a filter is attached to the lower end of the case 22, and a crystal sensor 26 is built in approximately the center of the case 22. .

One end of a deflection transmitting member 28 having a fulcrum in the center is fixed to one end of the crystal sensor 26.
A pair of bellows 32 and 34 whose negative ends are fixed to the frame body 30 are arranged opposite to each other on the other end side with the fulcrum of the bellows 8 in between.

The bellows 32 on the upper side is released to the atmosphere via an atmosphere release tube 36, and the bellows 34 on the lower side is connected to the filter 24 via a water pressure transmission tube 38.

In the water pressure gauge 12.14 configured in this way, changes in water pressure due to changes in water depth are transmitted to the bellows 34 on the lower side via the water pressure transmission tube 38, and at this time, the lower end of the bellows 34 is connected to the frame body. 30, only its upper end expands and contracts in response to water pressure, and this expansion and contraction causes the deflection transmitting member 28 to expand and contract.
is added to the crystal sensor 26 via the crystal sensor 26
distortion occurs.

When distortion is applied to the crystal sensor 26, its oscillation frequency changes, so the frequency change is converted into water pressure.

At this time, the bellows 32 on the upper side is open to the atmosphere via the tube 36, so it can sense changes in atmospheric pressure due to high pressure or low pressure, and prevent the influence of atmospheric pressure changes on the water surface on the water pressure. to erase.

On the other hand, the arithmetic unit 20 includes a converter 20a that converts human power signals from the water pressure gauge 12.14 and the thermometer 16.18 into digital signals, and an arithmetic operator that receives and processes signals from the converter 20a. It is composed of a container 20b.

An outline of the processing procedure executed by the computing unit 20b is shown in FIG. 4. In the processing procedure, first, in step S1, the known installation depth hl of the water pressure gauge 12.14 is determined.

h2 and these output signals P1. P2 and thermometer 1
6.18 output signals Tl, T2 are taken in via a converter 20g.

Next, in step S2, the distance l between the installation positions of the water pressure gauges 12 and 14, and the water pressure difference ΔP-P2-PL are calculated, and in step S3, the flow rate is calculated based on the above-mentioned formula (2) from each of these calculated values. The unit volume weight γ of is calculated.

V In step S4, the density of fresh water ρ at T2°C is calculated, and γ is expressed as the gravitational acceleration gV
ν
The density of flowing water, ρ, is calculated by dividing by .

ν In this case, since the change in density of fresh water with respect to temperature is well known, it may be stored in advance.

In the subsequent step S5, the density uniformity Δρ due to the mixing of suspended substances is calculated based on the above-mentioned formula (2), and the processing procedure is completed.

Here, for example, if the constant k in the above-mentioned formula (■) is set in advance by conducting suspended solids analysis using on-site water sampling, then
Of course, it is also possible to obtain the suspended solids ff1m based on the result of step S5.

Now, with the turbidity measuring device of the present invention configured as described above, continuous measurement in real time at the current location is possible.

In addition, according to experiments by the present inventors, the amount of suspended solids is 200
It has been confirmed that automatic measurement can be performed from low concentrations around pp- to high concentrations of 111 pl.

Furthermore, since the water pressure gauge 12.14 has a crystal sensor 26 built into the cover 22, it is not affected by limescale or suspended matter, so there is almost no need for maintenance and inspection, making management extremely easy. Become.

! FIG. 5 shows another embodiment of the present invention, and FIG. 5(A) shows a large number of water pressure gauges 1 arranged at equal intervals from the water surface.
This is an example of arranging 2a, b...n, and when a large number of water pressure gauges are arranged in this way, it is possible to continuously measure the distribution of suspended solids at each depth, from the surface layer of a reservoir to the deep layer. Can be accurately grasped.

Further, in FIG. 2B, a pair of water pressure gauges 1.2a and 12b'' are fixed at a predetermined interval and are configured to be moved in the vertical direction.

With this configuration as well, suspended solids jl (turbidity) at any water depth can be measured in the same way as above.

Furthermore, in FIG. 4(C), the water pressure gauges 12a-, 12b shown in FIG. This makes it possible to measure the wind at any depth.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the flp1 method of the present invention, Figs. 2 to 4 show an embodiment of the turbidity measuring device according to the present invention, and Fig. 2 is an overall layout diagram of the turbidity measuring device. FIG. 3 is a detailed view of the water pressure gauge, FIG. 4 is a flowchart of the arithmetic device, and FIG. 5 is an explanatory diagram showing another embodiment of the measuring device. 12.14... Water pressure gauge 16.18... Temperature gauge

Claims (2)

[Claims] (1) Measure the depth, water pressure, and water temperature at the measurement target location, calculate the amount of increase in density due to the mixing of suspended solids from each of these measured values and the standard water density, and calculate the turbidity based on the size of this increase in density. A turbidity measurement method characterized by determining. (2) A water pressure gauge installed at the existing depth, a thermometer that measures water temperature, and an increase in density due to the mixing of suspended solids based on the measured value of the water pressure gauge and the standard water density based on the measured value of the thermometer. A turbidity measuring device characterized by having a calculation device that calculates a quantity.