JPH01315492A - Method for producing high concentration coal water slurry - Google Patents

Abstract

PURPOSE:To obtain the subject low-viscosity slurry readily transportable with a small amount of an added surfactant by adding an oil-in-water type emulsion to coal in fine pulverization thereof. CONSTITUTION:The objective slurry obtained by adding an oil-in-water(O/W) type emulsion containing oil droplets of a hydrophobic oil, such fuel oil A, preferably stabilized with molecules of a surfactant, such as anionic surfactant or sodium naphthalenesulfonate formalin condensate, to coal in fine pulverization thereof. For example, the anionic surfactant, together with fuel oil A in an amount of about 2 times, as the O/W type emulsion is added to reduce the slurry viscosity by about 34% in comparison with that without adding the fuel oil A.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an R-adjustment method for a low-viscosity, high-concentration coal-water slurry that is easy to transport.

[Conventional technology]

Highly concentrated coal water slurry (Coal
Water Mixture (hereinafter referred to as CWM) is spontaneous ignition during transportation and storage in lump coal utilization systems.
This coal fluidization technology was developed as an energy alternative to oil as a way to solve safety problems such as dust scattering and convert coal into an easy-to-handle fluid fuel, and is the closest to practical application. It is attracting attention as

The above CWM is a mixture of pulverized coal and water, and CWM is a mixture of pulverized coal and water.
In order to efficiently burn WM in a boiler, it is necessary to increase the coal concentration as much as possible without impairing its fluidity, and in this case, it is necessary to add a surfactant to increase the dispersibility of coal particles in water. has become essential. However, since these surfactants are expensive, an increase in the cost of CWM is unavoidable, and in order to reduce the cost of CWM, measures must be taken to reduce the amount added as much as possible.

By the way, as a method for producing CWM, a method has been used so far in which coal is wet-pulverized in the presence of water and a surfactant. In this case, a two-step addition method in which the surfactant is added separately during and after the coal is pulverized, and a divided addition method in which the surfactant is added into the mill in divided portions depending on the elapsed time of pulverization have been proposed. It is described in Japanese Patent Application Laid-Open No. 59-20390.

However, even with this method, it is difficult to prevent the surfactant from being adsorbed onto the pore surface of the coal, which does not contribute to the dispersibility of CWM.

[Problem to be solved by the invention]

In the above conventional technology, sufficient consideration has not been given to the method of adding surfactant that is effective in reducing the amount of surfactant added in CWM. The surfactant is adsorbed, and as a result, the amount of surfactant added is greater than the required amount, which is considered to be a problem in increasing the cost of CWM.

Therefore, the present inventors conducted extensive studies on the method of adding surfactant in order to reduce the amount of surfactant added in the manufacturing process of CWM.

The purpose of the present invention is to reduce the amount of surfactant added.

and to provide an advantageous CWM by reducing CWM viscosity.

[Means to solve the problem]

The present invention has been made to solve the above problems,
The object of the present invention is to use oil droplets of hydrophobic oil stabilized by surfactant molecules, i.e. the first
An oil-in-water (O/W) emulsion containing oil droplets of hydrophobic oil with surfactant molecules oriented with their polar groups toward the aqueous phase as shown in the figure. This is achieved by adding it during pulverization of coal.

[Effect]

In CWM, a surfactant is adsorbed onto the surface of coal through hydrophobic bonds, charges the surface of the coal, and its electrostatic repulsion prevents and stabilizes coal fine particles from agglomerating.

However, because the coal surface contains hydrophilic oxygen-containing functional groups (carboxyl groups, hydroxyl groups, etc.) and ash, the hydrophilicity increases in this area and reduces the affinity of the hydrophobic bond between the coal and the surfactant. This makes it difficult to absorb.

Coal also has many pores. As shown in Figure 2, the equilibrium adsorption amount when surfactant-containing water is mixed with coal of various particle sizes obtained by dry crushing and classification is constant without being affected by the particle size. It can be seen that the activator molecules are diffused and adsorbed not only on the outer surface of the coal particles but also on the pore surfaces. However, the surfactant adsorbed on the inner surface of the pores is not related to electrostatic repulsion, does not contribute to the above-mentioned stabilization, and is not effective in preventing agglomeration of fine coal particles.

In the present invention, by adding the above-mentioned emulsion at the time of pulverizing coal, oil droplets of hydrophobic oil in the emulsion block the pores of the coal and at the same time form an oil droplet surface, as shown in Figure 3. Surfactant molecules are adsorbed onto the outer surface of the coal,
In addition, the hydrophilic groups and hydrophilic substances present on the outer surface of the coal are made hydrophobic by coating them with the hydrophobic oil of the emulsion, and at the same time, the surfactant molecules forming the surface of the oil droplets of the emulsion are Sufficiently effective adsorption and CW
This makes it possible to reduce the amount of surfactant added in M. Furthermore, the surfactant adsorbed on the outer surface of the coal prevents coal particles from agglomerating, lowering the viscosity of CWM and making it possible to increase the concentration.

Note that in the present invention, any surfactant and hydrophobic oil can be used, and examples of the surfactant include anionic surfactants.

For example, sodium naphthalene sulfonate formalin condensate is preferably used, and as the hydrophobic oil, heavy oil A is preferably used.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

<Example 1> Pacific coal, a domestic coal, was ground and adjusted to have the particle size distribution shown in FIG. Take 65g of the coal whose particle size has been adjusted, add 0.39g of anionic surfactant and 0.2g of the anionic surfactant.
The oil-in-water type (O
/W) was added and mixed, and the viscosity of CWM at each added amount of heavy oil A was measured at 25° C. using a rotational viscometer.

Next, for comparison, 35 g of water in which 0.3 g of anionic surfactant was dispersed alone was added to 65 g of the above coal and mixed, omitting the addition operation of heavy oil A, and the same method as above was carried out. The viscosity of CWM was measured by Table 1 shows the apparent viscosity (
The results of measuring the viscosity (hereinafter abbreviated as viscosity) are shown below.

Table 1 From the results shown in Table 1, as the amount of A heavy oil added increases, C
It can be seen that the viscosity of WM decreases. In addition, anionic surfactants are mixed with about twice the amount of heavy oil in an oil-in-water type (oil-in-water type).
It is also seen from Table 1 that by adding CWM as an O/W) emulsion, the viscosity of CWM is reduced by about 34% compared to when heavy oil A is not added.

<Example 2> The particle size of coal used in Example 1 was determined to rljm in the same manner. Take 65g of this coal whose particle size has been adjusted and add 0.13g to it.
35 g of water containing anionic surfactants with varying amounts added in the range of ~0.39 g was added and mixed, and the viscosity of CWM at each added amount was measured at 25°C using a rotational viscometer. .

In addition, 65 g of the above coal was taken, and twice the amount of A heavy oil was added to the amount of surfactant added to form an oil-in-water type (O/W) containing oil droplets as shown in Figure 1. 35 g of the emulsion was added and mixed, and the viscosity of CWM at each addition amount was measured in the same manner as above. The viscosities of these CWMs are shown in FIG.

From Figure 5, the required amount of surfactant to be added to produce CWM with a viscosity of 1500 mPa-8 or less is 11
It can be seen that by adding the 3-ion surfactant together with twice the amount of heavy oil as the oil-in-water type (○/W) emulsion, the reduction can be achieved by about 32%.

<Example 3> Using the CWM preparation method of Example 1, the amount of heavy oil added was reduced to 0.
．． 8g constant, CW by changing the type of heavy oil added
M was prepared and the viscosity of the CWM was measured in the same manner as described in Example 1. The results are shown in Table 2.

In Table 2, the heavy oils A, B, and C have different hydrophobic strengths, and the hydrophobic strengths are in the order of A>B>C, with heavy oil A having the strongest hydrophobicity.

From the results shown in Table 1 and Table 2, when adding an anionic surfactant together with heavy oil as an oil-in-water (O/W) emulsion, it is better to use highly hydrophobic heavy oil to reduce the viscosity of CWM. It can be seen that it is effective in reducing

〔Effect of the invention〕

According to the present invention, in the production of CWM, an oil-in-water type (O/W) containing oil droplets in which surfactant molecules are oriented around oil droplets of hydrophobic oil as shown in FIG. By adding this emulsion during the pulverization of coal, the pores of the coal are filled with hydrophobic oil, the surface of the coal is made more hydrophobic, and CWM with low viscosity can be produced using a small amount of surfactant. I can do it.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of oil droplets contained in the emulsion used in the present invention, Figure 2 is a diagram showing changes over time in the amount of surfactant adsorbed due to differences in coal particle size, and Figure 3 is a diagram showing oil droplets contained in the emulsion used in the present invention. A schematic diagram showing the state of adsorption of droplets onto coal. Figure 4 is a particle size distribution diagram of coal suitable for CWM production. Figure 5 is the amount of surfactant added and the viscosity of CWM depending on the method of adding surfactant. Relationship with prefecture 1 map? Search/Kin i) o-41io Okkyusei 1, minute 1,000 2nd figure company breath time (h) 杢3 figure ground 40 Mi#L'4 raw (μm) Next S concavity;

Claims (1)

[Claims] 1. In a method for producing a highly concentrated coal-water slurry, an oil-in-water (O/W) emulsion containing oil droplets of hydrophobic oil stabilized by surfactant molecules is added during pulverization of coal. A method for producing a highly concentrated coal slurry, characterized in that the slurry is added.