CN103512829A - Method for measuring sediment concentration through density of muddy water - Google Patents

Abstract

The present invention relates to a method for measuring sediment concentration through the density of muddy water, which includes the following steps: 1) Preparatory stage: ① Weigh the mass M _S of sediment as a sand sample, put it into a container, and measure the volume V of clear water _W , pour it into the container and stir it into muddy water; ② measure the muddy water volume V obtained in step ①, and calculate the muddy water volume V _S = VV _W ; ③ calculate the muddy water density ρ _s = M _s /V _s ;2) Testing stage: ①Weigh the mass M of the muddy water to be tested, and measure the volume V of the muddy water to be tested; ②Calculate the density of muddy water ρ=M/V and the density of clear water ρ _W ＝M _W V _W ; ③Calculate to obtain mud Sand volume concentration C _V =(ρ-ρ _W )(ρ _S -ρ _W ). The present invention can be applied to the measurement of sediment concentration in muddy water rivers, hydropower stations, water pumping stations, etc., the measurement of sediment concentration in simulation test devices in pressurized flow and open channel flow, and the calibration of various concentration measuring instruments, including solid particles. In all solid-liquid two-phase flow solid particle concentration measurements.

Description

A Method of Measuring Sediment Concentration by Muddy Water Density

technical field

The invention relates to a method for measuring sediment concentration, in particular to a method for measuring sediment concentration through muddy water density.

Background technique

In our daily life, industrial and agricultural production, and scientific research work, we often need to know or measure the proportion of two or more different media mixed together, and the concentration is often expressed in liquid. For example, in muddy water containing silt particles, it is often necessary to measure the concentration of these silt particles in the water. Concentration has two main expressions, namely volume concentration and mass concentration. In terms of sediment concentration, the volume concentration C _V is the ratio of the volume of sediment in muddy water to the total volume of muddy water, while the mass concentration C _M is the ratio of the mass of sediment in muddy water to the total mass of muddy water. In engineering practice, China's engineers and technicians often express the sediment mass C' _M per unit volume of muddy water (C' _M = M _S /V, where V is the volume of muddy water, and M _S is the mass of sediment in muddy water). The concentration of sediment particles in muddy water is called sediment concentration, and its common unit is kg/m ³ . In the measurement of sand concentration, the general method is the weighing method: take muddy water with a volume of V containing sediment particles, filter out most of the water by means of filtration, etc., then dry and weigh to obtain The mass of sediment particles M _S , that is, the sediment content C' _M (C' _M ＝ M _S /V) can be calculated. In the above measurement method, only the sediment content C' _M is measured, and the sediment density is not measured. ρ _S , only the quartz sand density of 2650kg/m ³ is generally used to approximate the volume concentration C _V of muddy water (C _V =C' _M /ρ _S ).

The above-mentioned weighing method has the following three disadvantages: 1. If the mineral types of solid particles such as sediment are different, and the proportions of various minerals are different, their densities will be different. Generally, the density of quartz sand is used to replace the sediment containing different minerals The density is bound to bring great errors due to its uncertainty; the filtration of sediment needs to be very meticulous and cautious, and a little carelessness may increase the test error due to the introduction and removal of sediment. 2. The operation process is cumbersome and labor-intensive. 3. Since the filtration and drying of sediment are very cumbersome and time-consuming, a lengthy measurement process is often required, and the measurement results cannot be obtained immediately. We can only take samples first, and then select the timing to measure and determine C' _M , so that after the test Concentration or sand concentration values cannot be obtained for a long time, and errors in the testing process cannot be found in time.

With the development and progress of testing technology, the use of real-time online monitoring for sediment concentration measurement has become a development trend. At present, there are various concentration measurement methods such as ultrasonic attenuation method, photoelectric method (infrared method) and gamma ray method. In these measurement methods, the measurement results are mostly volume concentration or mass concentration. To convert it into the commonly used sediment concentration C' _M in China, it is necessary to use the sediment density ρ _S for conversion (C' _M = C _V · ρ _S ), it is necessary to measure _ρS accurately. Although the density of minerals that make up sediment particles is definite and measurable, when a variety of different mineral particles are combined into sediment in a definite but unknown specific ratio, the density is uncertain, so it cannot be calculated and can only be measured . However, there are gaps between sediment particles, and the gaps are also different due to different particle sizes, gradations and compaction degrees, so the sediment density cannot be accurately measured in the atmosphere.

Contents of the invention

In view of the above-mentioned problems, the object of the present invention is to provide a method for measuring sediment concentration through muddy water density, which is simple in operation, high in measurement accuracy, and the test result can be obtained immediately.

To achieve the above object, the present invention adopts the following technical solutions: a method for measuring sediment concentration by muddy water density, which includes the following steps: 1) Preparatory stage: obtaining the sediment density ρ _S : ① Weighing the mud as a sand sample sand mass M _S , and put it into a container, measure the volume of clear water V _W , pour it into the container, and stir it into muddy water; ② measure the muddy water volume V obtained in step ①, and calculate the muddy water volume V _S = VV _W ; ③ Calculation of sediment density ρ _s = M _s /V _s ; 2) Test stage: measure and calculate various mineral types and mineral ratios in muddy water that are basically the same as those in step ① in step 1). Sediment volume concentration C _V : ①Weigh the mass M of the muddy water to be tested, and measure the volume V of the muddy water to be tested; ②Calculate the density of muddy water ρ=M/V and the density of clear water ③Calculate and obtain sediment volume concentration

It can convert the sediment volume concentration C _V into the commonly used sediment concentration C' _M in the industry:

C' _M = ρ _S · C _V .

的推导过程如下：The sediment volume concentration in the step 1)

The derivation process is as follows:

The volume V _S occupied by sediment in muddy water is:

V _S =V V _W (1)

And the sediment density ρ _S in muddy water is:

ρ _s =M _s /V _s (2)

In muddy water, the relationship between sediment quality and clear water quality is as follows:

ρ·V= _ρS · _VS + _ρW · _VW (3)

The sediment volume can be expressed as:

V _S =C _V ·V (4)

The clear water volume can be expressed as:

V _W =V V _S (5)

Substitute formula (4) and formula (5) into formula (3):

ρ V = ρ C _V V + ρ _W (VC _V V) (6)

After simplifying formula (6), we get:

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&rho;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; .</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

When obtaining the sediment mass M _S and the muddy water mass M to be measured, it is obtained by weighing with standard weighing equipment.

When obtaining the clear water volume V _W and the muddy water volume V, it is obtained by measuring the standard volume barrel of the metering volume.

The present invention has the following advantages due to the adoption of the following technical solutions: 1. The present invention determines the sediment density due to the method measurement and calculation of directly weighing the standard volume clear water with the required sediment, and the density is different for the solid particles of the same mineral matter It basically does not change with particle size gradation, and is also slightly affected by water temperature. It can be considered that _ρS remains unchanged under the condition that the water temperature does not change much, the minerals are basically the same, or the ratio of different minerals is basically the same. The ρ _S is measured for all concentrations, so that filtering and baking sediment for each concentration can be avoided, which not only reduces the labor intensity, but also greatly shortens the test time, and can also make the test results available immediately. 2. Since the present invention accurately measures the sediment density ρ _S , whether it is converted from C _V to C' _M or converted from C' _M to C _V , it is more accurate than the general value of quartz sand density 2650kg/ ^m3 used in the past .

Detailed ways

The present invention will be described in detail below in conjunction with the examples.

What the present invention adopts is a kind of indirect measurement method, does not directly measure the sediment concentration in muddy water, but firstly by measuring the method of dry sand mass M _S , clear water volume V _W and muddy water volume V after the two are mixed, and then calculates After determining the sediment density ρ _S and obtaining the sediment density ρ _S , measure the muddy water density ρ and clean water density ρ _W at each point through actual measurement or calibration, and calculate the corresponding sediment volume concentration C _V .

Principle of the present invention is as follows:

The volume V _S occupied by sediment in muddy water is:

V _S =V V _W (1)

The sediment density ρ _S in muddy water can be calculated by the following formula:

ρ _s =M _s /V _s (2)

In muddy water, the relationship between sediment quality and clear water quality is as follows:

ρ·V= _ρS · _VS + _ρW · _VW (3)

And the sediment volume V _S can be expressed as:

V _S =C _V ·V (4)

Among them, C _V is the sediment volume concentration.

The clear water volume can be expressed as:

V _W =V V _S (5)

Substitute formula (4) and formula (5) into formula (3):

ρ V = ρ C _V V + ρ _W (VC _V V) (6)

Simplify formula (6) to get sediment volume concentration C _V :

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; V</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&rho;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

Therefore, when measuring the volume concentration of sediment, the volume concentration C _V of sediment can be calculated by formula (7) through the measurement of muddy water density ρ, clear water density ρ _W and muddy water density ρ _S under different concentration conditions.

If necessary, formula (8) can also be used to convert the sediment volume concentration C _V into the commonly used sediment concentration C' _M in the industry:

C' _M ＝ρ _S ·C _V (8)

In addition, considering that the density of minerals does not change due to particle size and is less affected by temperature, it can be considered that muddy water with the same mineral (or a variety of different minerals, but the proportion of each mineral is basically unchanged) In the concentration measurement, the sediment density ρ _S is constant, so it is not necessary to measure repeatedly.

The inventive method comprises the following steps:

1) Preparatory stage: measure and calculate sediment density ρ _S

① Mix the silt particles evenly, and take a certain quality of silt particles to dry as needed;

② Use a balance or other high-precision weighing equipment to weigh the required dried sediment mass M _S ;

③Put all the weighed sediment into the standard volume barrel that can measure the volume;

④ Pour the clear water with the measured volume V _W into the standard barrel, stir evenly, so that the sediment and clear water are fully fused until there are no air bubbles around the sediment particles;

⑤ Measure the volume V of muddy water, and calculate the volume V _S occupied by sediment or solid particles of the same minerals in muddy water according to the formula V _S = VV _W ;

⑥ Calculate the sediment density ρ _S according to the formula ρ _s =M _s /V _s .

In order to improve the test accuracy, try to make the volume V of muddy water close to the full range of the volume barrel, and choose the highest possible concentration to measure ρ _S , but make sure that the solid particles are fully integrated into the water, there are no bubbles, the muddy water can flow, and it will automatically keep free , Horizontal water surface.

2) Test stage: by measuring the muddy water density ρ and clear water density ρ _W , calculate and determine the sediment volume concentration C _V

① Measure the volume V and mass M of muddy water, and calculate the density ρ of muddy water;

②Measure the clear water density _ρW at the same temperature as the muddy water;

③ Utilization Calculate the sediment volume concentration C _V ; if the commonly used sediment concentration C' _M is required, use the formula C' _M = ρ _S · C _V to calculate.

For different sediment concentrations, it is only necessary to repeat the above three steps without going back to the preparation stage to repeatedly measure the sediment density ρ _S .

Since the weight method is used to weigh the quality of sediment, muddy water and clear water, and the air buoyancy will affect the measurement results during weighing, in order to ensure the measurement accuracy, the air buoyancy correction should be carried out during weighing.

The above-mentioned embodiments are only used to illustrate the present invention, and the specific implementation steps and detailed rules of each stage and each item measurement all can be changed to some extent. Improvements and equivalent transformations made in the detailed rules shall not be excluded from the protection scope of the present invention.

Claims (5)

1. by a method for muddy water density measure sediment concentration, it comprises the following steps:

1) preparatory stage: obtain silt density p _s

1. weigh the Sediment quality M as husky sample _s, and put into a container, measure clear water volume V _w, pour in described container, stir into muddy water;

2. the muddy water volume V that 1. measuring process obtains, calculates silt volume V in muddy water _s=V-V _w;

3. calculate silt density p _s=M _s/ V _s;

2) test phase: measure to calculate the 1. silt volumetric concentration C in the basically identical muddy water of described husky sample of step in various mineral types and mineral matter ratio and step 1) _v

1. weigh muddy water mass M to be measured, measure the volume V of muddy water to be measured;

2. calculate muddy water density p=M/V and clear water density

3. calculate and obtain silt volumetric concentration

2. as claimed in claim 1 a kind of by the method for muddy water density measure sediment concentration, it is characterized in that: can be by silt volumetric concentration C _vbe converted into conventional silt content C' in industry _m:

C' _M＝ρ _S·C _V。

3. as claimed in claim 1 or 2 a kind of by the method for muddy water density measure sediment concentration, it is characterized in that: the silt volumetric concentration in described step 1)

derivation as follows:

Silt is shared volume V in muddy water _sfor:

V _S＝V-V _W （1）

And silt density p in muddy water _sfor:

ρ _s＝M _s/V _s （2）

In muddy water, between Sediment quality and clear water quality, there is following relation:

ρ·V＝ρ _S·V _S+ρ _W·V _W （3）

And silt volume can be expressed as:

V _S＝C _V·V （4）

Clear water volume is expressed as:

V _W＝V-V _S （5）

Formula (4) and formula (5) are distinguished to substitution formula (3):

ρ·V＝ρ·C _V·V+ρ _W(V-C _V·V) （6）

After being simplified to processing, formula (6) obtains:

$C_V=\frac{\mathrm{\&rho;}-{\mathrm{\&rho;}}_W}{{\mathrm{\&rho;}}_S-{\mathrm{\&rho;}}_W}.---\left(7\right)$

4. as claimed in claim 1 or 2 a kind of by the method for muddy water density measure sediment concentration, it is characterized in that: obtain Sediment quality M _sduring with muddy water mass M to be measured, adopt the acquisition of weighing of standard weighing-appliance.

5. a kind of by the method for muddy water density measure sediment concentration as claimed in claim 3, it is characterized in that: obtain clear water volume V _wduring with muddy water volume V, adopt the orthobaric volume cylinder bucket metering of metered volume to obtain.