JPH0227012B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slurry storage method for stably storing a slurry in which solid particles tend to settle over a long period of time.

Some slurries have good stability, with solid particles uniformly suspended in the medium over a long period of time, but others have low static stability, where the particles settle out in a short period of time, resulting in phase separation or compaction solidification. many. There are many factors that determine static stability, but in the relative relationship between the medium and the solid particles, the easier the particles settle, the lower the stability. For example, coal-methanol slurry (generally called methanol), which is used as a fluid fuel, is made by suspending fine coal particles in methanol, but the viscosity of the methanol medium is extremely low; Because the difference in specific gravity between coal and coal is relatively large, the stationary stability is low. For this reason, if methadol is temporarily stored in a normal tank, the coal particles will undergo phase separation or solidification in a short period of time, causing problems during reflow during subsequent transportation.

The present invention aims to provide a method for stably storing a slurry having low static stability, such as a highly concentrated particle suspension such as a paint in which the above methacol, COM, and pigment particles are suspended, over a long period of time. The purpose is

In the process of conducting numerous experiments to analyze the behavior of solid particles (suspended solids) in slurry left still, the present inventors discovered that the maximum dimension in the horizontal direction of a container containing slurry It was discovered that there is a specific correlation between this and the sedimentation rate of solid particles in this slurry, and the method of the present invention was completed.

According to our experiments (described below), when the container is cylindrical, the settling velocity of solid particles in the slurry becomes significantly faster when the diameter of the container is approximately 55 mm or more, and rapidly increases when the diameter of the container is less than 55 mm. It was confirmed that it would be delayed. In other words, when slurry is stored without phase separation, there is a critical maximum diameter in the storage container, and if the storage container exceeds this critical maximum diameter, phase separation will occur in a short period of time during storage, a caking phenomenon will occur, and reflowability will disappear. It is a fact that even if the slurry is such that the diameter is below the critical maximum diameter, the slurry state will be maintained stably for a long time. The critical maximum diameter is indicated by the diameter when the cross-sectional shape of the container is circular, the length of the longest side when the cross-sectional shape is triangular, and the length of the diagonal when the cross-sectional shape is square or polygonal. is appropriate.

When storing slurry on an industrial scale,
Insert many pipes with inner diameters below the critical diameter vertically into a large storage tank, or
By providing a polygonal honeycomb structure, the maximum diameter of each of the many divided spaces can be made equal to or less than the critical maximum diameter, thereby making it possible to put it into practical use. According to experiments, the critical maximum diameter is 50
mm.

Experimental example 1 Three types of graduated cylinders with inner diameters of 28 mm, 55 mm, and 87 mm were prepared, and the concentration was
A methacol slurry of 46.6% by weight and a temperature of 20°C was injected to a height of 180 mm, and a penetration test was conducted on each of them. The methacol slurry used was made by wet-pulverizing ordinary coal for 24 hours and mixing particles with a particle size of 37 μm or less and particles with a particle size of 125 to 250 μm in a weight ratio of 40:60. It is adjusted by dispersing it in methanol to the above concentration, and its viscosity is approximately at 20℃.
It was 1.5×10 ² centipoise.

The penetration test uses a rod penetration test device schematically shown in Figure 7, and a penetration rod (glass rod) with a diameter of 6 mm and a weight of 18 g or 20 g is penetrated into the center of each female cylinder by its own weight, and its penetration depth ( mm) and penetration time (seconds).

The results of the penetration test are shown in Figures 1 to 6. 1st
The figure is a graph of the measurement results immediately after injecting the sample into a measuring cylinder with a diameter of 28 mm and the measurement results one week later. Figure 2 shows the case where the diameter of the female cylinder is 55 mm, and Figure 3 shows the case where the diameter is 87 mm. A similar experiment was also conducted using a penetrating rod weighing 20 g, and measurement results were obtained immediately and after 3 weeks.
Figure 4 shows the fifth cylinder when the diameter of the female cylinder is 28 mm.
The figure shows the case of 55mm, and Figure 6 shows the case of 87mm.

As is clear from these results, in the case of diameters of 55 mm and 87 mm, a sedimentation compaction layer is formed after 1 week and 3 weeks, making it impossible for the penetrating rod to penetrate, whereas in the case of diameter 28 mm In the case of , the penetration speed in the deep part is slightly slower, but the penetration rod penetrates to the bottom, and no consolidation due to consolidation is observed.

Experimental Example 2 A cube-shaped hard vinyl chloride container with a side length of 300 mm was provided with a partition wall made of hard vinyl chloride thin plates 1 mm thick in a rectangular shape. The interior of the chamber was divided into elongated chambers with a square cross section of 30 mm x 30 mm extending vertically parallel to each other. Inside this divided container,
A slurry consisting of the same methanol dispersion of coal as used in Experimental Example 1 (viscosity at 20°C: approximately 1.5×10 ² centipoise) was filled up to a height of 180 mm in each chamber. The container was left standing for 3 weeks while maintaining the temperature of the slurry at 20° C., and a penetration test was conducted on the slurry in each chamber in the same manner as in Experimental Example 1 immediately after filling and 3 weeks later. The test results obtained are shown in FIG. The curve shown in Figure 8 is based on the data obtained for 5 cells randomly selected from the periphery near the side wall of the container, the center of the container, and the intermediate area in between, out of 100 cells. Based on average values.

For comparison, a container with the same material and dimensions as above was prepared except that no partition wall was provided, and the same slurry as above was filled into this container to a height of 180 mm. A penetration test was conducted using the same method. The test results obtained are shown in FIG.

In the container divided into small chambers according to the method of this invention, the slurry retains considerable fluidity even after three weeks, and in particular, the fluidity does not depend on the horizontal position of the container. There is almost no difference between the upper, middle, and lower layers.

As described above, according to the present invention, the cross section of the storage tank is determined by the critical maximum diameter at which sedimentation of particles in the slurry is suppressed (approximately 50 mm in the above experiment, but depending on the type of suspended solids, particle size, The slurry is divided into the following spaces (which change depending on the concentration, suspension medium, etc.), and the slurry is accommodated within this space, so even slurries with low static stability can be stored stably for long periods of time. In addition, it is stable when stored in a storage tank.
Subsequent reflow operations such as transportation are possible. Therefore, not only meth alcohol as mentioned above, but also COM (coal oil mixer),
The ease of handling paint and other slurries is greatly improved.

[Brief explanation of drawings]

Figures 1 to 6 are graphs showing the relationship between penetration depth and penetration time under various conditions obtained through experiments to confirm the existence of the critical maximum diameter, and Figure 7 shows the penetration experiment equipment. An explanatory diagram, FIG. 8 is a graph showing the results of a penetration test conducted on a container divided into small chambers according to the present invention, and FIG. 9 is a graph showing the penetration degree conducted on a container not divided into small chambers. FIG. 2 is a graph diagram showing the results of a comparative test.

Claims (1)

[Claims] 1. A method for storing slurry, which comprises dividing the internal cross-section of a storage tank into vertical spaces with a diameter equal to or less than a critical maximum diameter in which sedimentation of particles in the slurry is suppressed, and storing slurry within these spaces.