JPS6157833A - Continuous measuring method of viscosity of coal and water slurry - Google Patents

Abstract

PURPOSE:To measure continuously the viscosity of slurry by installing a pressure drop measuring instrument and a flow meter in some section of piping, and letting the slurry flow through the piping. CONSTITUTION:The flow meter 49 which measures the flow rate of the slurry is provided on a differential pressure measurement line 41 at the exit side of a pump 51. The differential pressure measurement line 41 has a smooth internal surface and a differential pressure gauge is fitted in some section by using a flange 43, etc. The differential pressure gauge 42 uses a diaphragm type so as to prevent the slurry from flowing in and freezing, and the pressure of the slurry is received by a diaphragm and sent to a differential pressure transmitter 46 through a capillary tube 44 which is charged with silicone oil. The slurry E is sucked from a samp tank 52 bu a pump 51 and admitted intp the measurement line 41, and its flow rate and differential pressure are measured by the flow meter 49 and differential pressure gauge 42. Signals from the differential pressure transmitter 46 and a flow rate oscillator 50 are processed by a computing element 47 to calculate and display the viscosity of the slurry on an indicator 48 as well as the slurry mean flow velocity and differential pressure in the piping.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous viscosity measurement method for coal/water slurry, and is particularly applicable to coal/water slurries that have large viscosity changes due to concentration changes.
This invention relates to a method for continuously measuring the viscosity of water slurry.

(Conventional technology) Coal has been reconsidered as an alternative fuel to petroleum due to the recent energy situation, and research and development on technologies for its use are actively promoted in each country to expand its use. However, since coal is solid, The drawback is that it is difficult to handle. The technology that is expected to overcome this problem is the technology that utilizes coal as a fluid. C, a mixed fuel of coal and oil
OM (Coal-O4l-Mixtures) and CWM (Co a I-Wa), which is a mixed fuel of coal and water.
ter-Mixtures) is a typical example, but while COM has a coal conversion rate of 50%, CWM, which has a coal conversion rate of 100%, is attracting attention.

The conditions for producing CWM that is stable for one period and capable of direct spray combustion are: (1) increasing the particle density by preparing a wide particle size distribution and achieving high intensity;
) Addition of a surfactant or the like to form crotches on the particle surface and at the same time charge the particles, and evenly disperse the particles in the liquid to lower the viscosity. In the CWM manufactured in this way, the coal concentration is increased to the maximum that can be expected from the body theory, so as shown in Figure 11, a very small change in coal concentration causes a change in viscosity, or fluidity. (Measurement conditions in FIG. 11: temperature 28° C., shear rate 99 sec-''). Therefore, in the CWM manufacturing process, it is important to suppress fluctuations in the viscosity of the slurry as small as possible.

When producing CWM continuously, it is common to use a wet pulverizer, but due to moisture changes in the coal at the entrance of the wet pulverizer, etc. The training is +l'li < ir11-1 Slurry viscosity inside the wet crusher is L b+'I
/,〆I! ?・lil+ 1'l deteriorates and cannot be crushed to the required particle size (1'5). ) 1-Ni 1 degree is expected to be too low, 1'1 γ degree is iiii et al.:,
<Ruru.

Figure 10 shows a typical CWM manufacturing equipment system using a wet crusher. Coal A is supplied from bunker 1 to wet crusher 3 via coal feeder 2, while additive B is supplied from additive tank 4 by pump 6, and water C is supplied from water tank 5 by pump 7 to recovery tank 15. will be supplied in fixed quantities to In the collection tank 15, the coarse slurry separated by the coarse grain separator 10 is mixed by an agitator 16, and the mixture is supplied in a fixed amount to the wet crusher 3 via a coarse slurry collection pipe 14. The CWM produced in the new type crusher 3 is transported from the sump tank 8 to the coarse particle separator 10 by the pump 9, the CWM remaining on the screen 11 is transferred to the recovery tank 15, and the CWM that has passed is discharged to the outside of the yarn from the discharge port. It is sent out as product CWM (D).

CWM is produced using the above method, but as the moisture content in the coal, precision, etc. change from time to time, the slurry concentration, viscosity, and particle size of the product CWMr) fluctuate, making it difficult to secure a high-concentration, stable, and high-quality CWM. Not only is this difficult, but it can also lead to blockage and stoppage of the crusher. Therefore, conventionally,
A continuous viscometer is installed at the outlet of the sump tank 8 to detect the viscosity of the slurry and control the amount of water supplied to the 1'l mill (the amount of water supplied from the water tank). That is, when the slurry viscosity is low, the amount of water supplied from the water tank is reduced, and when the slurry viscosity is high, the amount of water supplied to the mill is increased.

However, the flow characteristics of CWM vary depending on the type of coal, manufacturing conditions, additives, etc. In other words, Figure 9 shows the three types of C
For WM (A), (B), and (C), the relationship between the shear rate and shear stress τ of each CWM was determined using a coaxial double cylinder rotational viscometer (Haal (e company! iJ)). However, it can be seen that there is a large difference in fluidity.Here, A is a Newtonian fluid in which the gradient of D is always constant, and B is a so-called pseudo-fluid in which τ decreases as the shearing speed increases. Plastic fluid, C, is called dilatant fluid. Here, apparent accuracy/I is expressed by τ and D.

Figure 8 shows the flow curves as shown in Figure 9 obtained using a coaxial 20i rotary viscosity needle manufactured by Haake.
The relationship between shear rate and viscosity was determined for M (A-C). The viscosity of the new fluid (A) remains constant even if the shear rate changes, but the viscosity of the pseudoplastic fluid (B) decreases as the shear rate increases, while the viscosity of the dilatant fluid (C) decreases as the shear rate increases. On the contrary, it is shown to increase. In other words, the pseudoplastic fluid (B) appears to have a high viscosity at first glance in a stationary state in a tank, etc., but when CWM due to pumping etc.
It exhibits low viscosity behavior under transport conditions. On the other hand, dilatant fluid (C) has a low viscosity in a stationary state in a tank, but exhibits high viscosity behavior under transfer conditions such as bombing.

As described above, since the viscosity of CWM changes depending on the shear rate, it has been found that quickly detecting the flow characteristics of CWM is most important in producing a high-quality and uniform CWM.

The configuration of a conventional continuous viscometer is not shown in Figure 7. This is what is called a rotating online viscometer (Chino Seisakusho, rotating continuous viscometer), and is composed of a synchronous motor 74, a magnet 75, an inner cylinder 76, a potentiometer 81, a converter 80, etc. . The principle is the same as the rotational viscosity liver for laboratory use, where CWM (1?,) flows in from pipe 83A,
Continuously passes around the inner cylinder 76 and flows out from the pipe 83B,
On the other hand, the inner cylinder 76 is rotated by a magnet I-75 installed at the bottom of the synchronous motor 74, and the slip torque generated during this rotation is detected by a potentiometer 81, and a converter 8
The signal is processed at 0 and displayed as viscosity on an indicator 79.

Here, the shear velocity in the tubes 83A-B is expressed by the following equation.

v D=□ where V: CWM flow velocity in the pipe (m/S), d: 'l'
1 diameter (m) Figure 6 shows the results of calculating the relational expression between shear velocity and viscosity by changing the flow velocity of slurry flowing into the cylindrical part using a continuous rotational viscometer (NamcLore, vibrating sphere viscometer). This is what is shown. The fluid used was 3 shown in Figure 6.
These are slurries of types A, +1, and C. For each slurry, results were obtained in which the slurry viscosity hardly changed despite changes in shear rate, and slurry A shown by the solid line in Figure 6 was obtained.
, B, and C.

It has thus been found that the viscosity obtained with a continuous tachometer is not representative of the accurate flow characteristics of the slurry.

Furthermore, FIG. 5 is a diagram showing the configuration of a conventional vibrating continuous viscometer. This viscometer is composed of a vibration method 21, a coil 22), an AC amplifier 23, a variable pulse oscillator 29, etc.

In the vibration method 21, a flange or the like is installed in the slurry pipe, and the slurry E flows continuously. This is a method in which a pulse current is applied to the vibration method 21 to instantaneously drive the vibration method, and its damped vibration is detected to determine the viscosity.

In this case, considering the shear velocity inside the viscometer, it is expressed as follows, where the pipe diameter is d (m) and the flow velocity inside the pipe is V (m/s).

FIG. 4 shows the results of determining the relationship between shear rate and viscosity by varying the flow velocity V in the pipe. As a result, each fluid has a high viscosity at low shear rates, and the viscosity of each fluid decreases as the shear rate increases, but it has the characteristic of having one or two peaks in the middle. As described above, in the conventional continuous type viscosity diameter, the viscosity characteristics depending on the shear rate are unclear, and it is difficult to grasp accurate viscosity and flow characteristics.

(Problems to be Solved by the Invention) An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a method for continuously measuring the viscosity of a highly concentrated coal/water slurry with high accuracy.

(Means for Solving the Problem) In order to achieve the above object, the present inventors have made extensive research and found that the pressure loss (differential pressure) of high-concentration CWM slurry is It was discovered that this corresponds to the viscosity of the slurry, and the present invention was achieved.

In the present invention, a differential pressure gauge is preferably used as the pressure loss measuring device, but other similar measuring means can also be used.

FIG. 1 is an explanatory diagram showing an embodiment of a continuous viscometer according to the present invention. This device consists of a differential pressure measurement line 41, a differential pressure gauge (diaphragm type) 42, a differential pressure transmitter 46, an indicator 48, and a flow meter 4 installed on the upstream and downstream sides of the line.
It consists of 9 mag.

A flow meter 49 is installed in the differential pressure measurement line 41 on the outlet side of the pump 51 to measure the flow rate of the slurry.

The differential pressure measurement line 41 has a smooth inner diameter of 30 to 150 mm.
Type A is used, and the differential pressure gauge 42 is attached to a certain section with a flange 43 or the like. The differential pressure gauge 42 is of a diaphragm type to prevent slurry from flowing in and solidifying.
sent to.

Slurry E is sucked from the sump tank 52 by the pump 51.
, is introduced into a differential pressure measurement line 41, and a flow meter (electromagnetic or ultrasonic type) 49 and a differential pressure gauge 42 measure the flow rate and differential pressure. Signals from the differential pressure transmitter 46 and the flow rate oscillator 50 are processed by a calculator 47 to calculate the viscosity of the slurry and display it on an indicator 48 . At the same time, the average flow velocity of the slurry in the pipe and the differential pressure are also displayed. Note that the differential pressure gauge may be of any type other than the capillary tube type, as long as it does not come into direct contact with the slurry or the conduit that transmits the pressure.

FIG. 2 shows the relationship between the flow velocity and pressure loss in the pipe of the AlB, C slurry (FIG. 8) measured using the apparatus shown in FIG. 1 in a logarithmic manner. The pipe diameter used was 50A, and the slurry flow rate was in the range of 0.07 m/s to 2 m/s. For each slurry, the pressure 1n loss △P increases as the flow rate increases, but the slopes of each slurry are significantly different. The Newtonian fluid slurry A has a slope of about 45°, while the pseudoplastic fluid B has a slope of about 45°. It exhibits a slightly downward convex behavior at 15 to 30 degrees, and in slurries with C dilatant characteristics, the slope is 50 degrees or more. Here, the shear velocity inside the pipe can be determined by:

Also, pressure loss per unit length P/L (mmH20/m)
is indicated by .

From equation (2), the slurry viscosity μ is It can be expressed as

Here, d: Pipe diameter (m) g: Gravitational acceleration (m/S) /l: Viscosity (kg/m-3>■2: Pipe length (m) Δp: Pressure 1■ loss (mmH20) V: Flow rate
(m/s) Therefore, if the shear rate and viscosity μ are calculated from equations (1) and (3) and the measured data shown in FIG. 2, the result will be as shown in FIG. 3. The solid lines indicate the flow characteristics of the three types of fluids shown in FIG. 8, and the flow characteristics determined by the continuous viscometer according to the present invention and Df i! It was confirmed that they matched.

Therefore, it is clear that by using the viscometer according to the present invention, the slurry at the mill outlet can be continuously measured in a wide range of shear rates, and the flow characteristics of the slurry can also be grasped.

(Effects of the Invention) According to the present invention, it is possible to continuously measure the viscosity of a product slurry, and it is also easy to understand the flow characteristics of the slurry, so the viscosity management of CWM manufacturing equipment can be carried out with high precision. In addition, it becomes easy to obtain the optimum 81 conditions even in piping transportation.

It also has the advantage of being cheaper to manufacture than conventional continuous viscometers.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a continuous viscosity measuring device according to the present invention using a differential pressure type viscosity needle, FIG. 2 is an explanatory diagram showing the relationship between flow velocity and pressure loss in an embodiment of the present invention, and FIG. , An explanatory diagram showing the relationship between the shear rate of each slurry and the slurry viscosity measured by the viscometer of the present invention, FIG. 4 shows the relationship between the shear rate and the slurry viscosity determined using the viscometer of FIG. Explanatory diagram: Figure 5 is a configuration diagram of a conventional continuous vibrating sphere viscometer; Figure 6 is an explanatory diagram showing the relationship between shear rate and slurry viscosity using the viscometer in Figure 7; , a configuration diagram of a conventional continuous rotary viscosity needle, FIG. 8 is an explanatory diagram showing the relationship between shear rate and slurry viscosity, FIG. 9 is an explanatory diagram of the flow characteristics of slurry, and FIG. 10 is a diagram of wet pulverization. FIG. 11, which is a system diagram of CWM manufacturing equipment using a machine, is an explanatory diagram showing the relationship between coal concentration and slurry viscosity. 41... Differential pressure measurement line, 42... Differential pressure needle, 43...
...Flange, 44...Capillary tube, 46.
... Differential pressure transmitter, 47 ... Arithmetic unit, 48 ... Indicator, 49 ... Flow meter, 50 ... Flow rate oscillator, 51 ...
・Pump, 52...Sump tank. Agent Patent Attorney Takenaga Kawakita Figure 1 41-11 Is it fun? Figure 3 [Fr speed D (S-') Figure 5 Figure 6 Figure 4 Shear speed D (S-') Figure 7 Figure 8 Figure 9 Shear Liao, buy D (S-”) Fig. 10 1 B ] 3 工 TING shi ξ-2, J to , , o 45 Kuwo 16L12 ・ □D 67

Claims (3)

[Claims] (1) By installing a pressure loss measuring device and a flow meter in a certain section of the piping and circulating slurry within the piping, the pressure loss detected by the pressure loss measuring device and the flow rate (flow velocity in the pipe) detected by the flow meter are calculated. A continuous viscosity measurement method for coal/water slurry, which is characterized by continuously measuring the viscosity of the slurry. (2) A continuous viscosity measuring method for coal/water slurry according to claim 1, which uses a differential pressure gauge as a pressure loss measuring device. (3) A continuous viscosity measuring method for coal/water slurry according to claim 2, characterized in that the viscosity of the slurry is calculated according to the following formula. μ=(Δp)/L・(d^2g)/(32v) d: Pipe diameter (m) g: Gravitational acceleration (m/s) μ: Viscosity (kg/m・s) L: Pipe length (m) Δp: Pressure loss (mmH_2O) v: Flow velocity (m/s)