JPS6243487A - Stabilization of aqueous slurry of carbonaceous solid - Google Patents

Abstract

PURPOSE:To prevent the thickening of a slurry produced by mixing carbonaceous solid, water and additive, and to prevent the increase of stabilization treatment cost, by adjusting the viscosity, etc., of the slurry to specific respective level in the production of the slurry. CONSTITUTION:A slurry is produced by mixing (A) a carbonaceous solid such as coal, oil coke, petroleum pitch, etc., (B) water and (C) an additive (e.g. anionic, cationic or nonionic surfactant, etc.). In the above process, the viscosity at the shear rate of 20sec<-1> on the increasing curve of the flow curve of the slurry is adjusted to 7-50 poise at 25 deg.C, the viscosity at the shear rate of 100sec<-1> on the decreasing curve of the flow curve of the slurry is adjusted to 5-30 poise at 25 deg.C, the viscosity difference at 25 deg.C is adjusted to 5-70 poise and the yield value at 25 deg.C is adjusted to 0.5-30 dyne/cm<2> to enable the stabilization of the carbonaceous solid-water slurry.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for stabilizing water slurry of carbonaceous solids such as coal, oil coke, and petroleum pitch, and more specifically, to stabilize a product slurry with optimal properties ( In particular, it relates to a stabilization method that adjusts the rheological properties within the range, thereby making it stable and minimizing quality changes during handling such as pipe transportation.

[Conventional technology]

In recent years, due to the instability of oil supplies, technological development has been underway to effectively utilize carbonaceous solids such as coal, oil coke, and petroleum pitch. For example, various technologies for effectively utilizing these carbonaceous solids include pyrolysis, gasification, combustion, alternative fuels for blast furnace-injected heavy oil in the iron smelting industry, and alternative fuels for heavy oil in cement kilns. However, in these various utilization technologies, carbonaceous solids are difficult to handle because they are solid at room temperature.
It has disadvantages such as the risk of pollution caused by flying dust and the risk of dust explosion, making it difficult to use.

Therefore, it is desirable to convert these carbonaceous solids into fluids to facilitate handling and prevent pollution and danger. On the other hand, in order to reduce the cost of transporting carbonaceous solids, it is effective to transport them in the form of a fluid.

For the purpose mentioned above, it is effective to make a slurry as a method of fluidizing carbonaceous solids, but this slurry can be thermally decomposed, gasified, combusted, or blown into a blast furnace.
In order to use the slurry as a fuel for cement kilns, it is necessary to make the slurry highly concentrated and to prevent solid particles suspended in the slurry from settling and causing solid-liquid separation.

Conventionally, methods for preparing a stable slurry include adding thickeners and surfactants to water slurry of coal whose particle size has been adjusted, and methods for preparing carbonaceous slurries as shown in Japanese Patent Application Laid-Open No. 59-4691. It is known to mix the substances, naphthalene sulfone heavy ring, karaya gum and water to obtain a slurry.

[Problem that the invention seeks to solve]

However, the above-mentioned prior art relates to the constituent materials of the slurry composition and the method of stabilization treatment, and does not address the range of optimal properties (especially rheological properties) of the product slurry.

In general, a water slurry of carbonaceous solids has a high viscosity in a static state, and when stirred, the viscosity decreases and fluidity increases. This phenomenon can be expressed as a flow curve with the horizontal axis representing the shear rate (1/5ec) and the vertical axis representing the shear stress (dyne/Cm'). When plotting the shear stress or apparent viscosity when the shear stress is decreased, the changes in shear stress do not form the same curve, but a hysteresis curve. The details of the flow curve measurement method will be described later.

In view of the above points, the present inventors conducted intensive research on a method for stabilizing water slurry of carbonaceous solids, and found that the shear rate on the rising curve (curve in the direction of increasing shear rate) of the flow curve of the slurry Viscosity at 20SecC, viscosity at a slip rate of 100 seconds on the downward slope of the slurry flow curve (a curve in which the velocity decreases by m It has been found that a stabilized water slurry of carbonaceous solid can be obtained by adjusting the difference between the viscosity at 100 sec, that is, the differential viscosity, and the yield value to fall within a certain range of values.

The present invention was made based on the above knowledge, and it identifies the optimal property range of product slurry, and thereby
The purpose of this invention is to provide a stabilization method that can achieve stability for 2 months or more.

[Means and effects for solving the problems] The method for stabilizing a carbonaceous solid/water slurry of the present invention is to prepare a slurry by mixing carbonaceous solids such as coal, oil coke, petroleum pitch, water, and additives. In adjusting the slipping speed on the rising curve of the slurry flow curve: 20 sec
The viscosity at 25°C is 7 to 50 poise (Poisθ),
Shear rate 1 on the descending curve of the slurry flow curve
The viscosity at 00sθC is 5 to 30 poise (Po
ise), viscosity differential viscosity is 5 to 70 poise at 25°C (Poise), yield value at 25°C is 0.5 to
It is characterized in that it can be adjusted within a range of 30 dyne/c+++.

In the present invention, methods for adjusting the properties to a suitable range include the use of a stabilizer, the use of a dispersant, and JP-A No. 60-584.
Stirring energy imparting treatment as shown in Japanese Patent Application No. 81409/1983, ultrasonic irradiation treatment as shown in Japanese Patent Application No. 81409/1986, etc. are applied.

The additives used in the present invention include anionic, cationic, and nonionic surfactants, used alone or in combination, and are appropriately selected depending on the type of coal. Specifically, the anionic surfactants include fatty oil sulfate ester salts, higher alfur sulfate ester salts, nonionic ether sulfate ester salts, olefin sulfate ester salts, alkylaryl sulfonates, and dibasic acid ester sulfonates. , dialkyl sulfosuccinate, acylsulfucinate, alkylbenzene sulfonate, alkyl sulfate ester salt, polyoxyethylene alkyl (alkylphenol) sulfate ester salt, alkyl phosphate ester salt, dialkyl sulfosuccinate ester salt, acrylic acid or/and Maleic anhydride copolymers, polycyclic aromatic sulfonates, formalin compounds, etc. are used, and as cationic surfactants, alkylamine salts, quaternary amine salts, etc. are used, and nonionic surfactants are used. Examples of agents include polyoxyalkyl ether, polyoxyethylene alkylphenol ether, oxyethylene/oxypropylene block polymer, polyoxyethylene alkylamine, sorbitan fatty acid ester,
Polyoxyethylene sorbitan Q? =fatty m ester, alkyltrimethylammonium chloride, alkyldimethylbenzylammonium chloride, alkylpyridinium salt, polyoxyethylene fat iFJ? ester,
Fat) M alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, polyhydric alcohol fatty acid ester, fatty acid ethanolamide, etc. are used, and amphoteric surfactants such as alkyl betaine are used, and 1, 2 .3 monoamine,
Amine compounds such as diamines, higher alkyl amino acids, etc. are used, and preferably, sodium naphthalene sulfonate, its formalin condensate, sulfonated product of ncrohentadiene J) A copolymer of sodium salt and sodium acetate, etc. are used. 0.00 for carbonaceous solids
1 to 5% by weight, preferably 0.05 to 1.5% by weight.
Naj is used.

The yield value can be measured directly using a B-type viscometer, or by plotting shear stress and shear rate data on a graph using a rotational viscometer or other various rheometers to create a flow curve, and then pushing this curve externally to determine the yield value. There are methods for determining the value, such as the Carson equation (1) method and the method of Bowles et al., but in the present invention, a measurement method using a B-type viscometer was adopted.

The measurement method using a B-type viscometer will be explained below. After adjusting the sample in advance to a constant temperature of 25°C in a constant temperature water bath, it is placed in a sample container and set in a B-type viscometer. Next, the viscometer is rotated as in a normal measurement at as low a rotational speed as possible, and when the pointer breaks to a certain extent, the pointer is clamped and the rotation of the motor is stopped.

Next, release the clamp and observe the point at which the pointer comes to rest. If the sample has a yield value, the pointer does not return to the '9 point, but stops just short of it. The resting point corresponds to the yield point, and if this (direction is K), the yield value can be found by multiplying K by the friction stress coefficient.When making measurements, do not apply vibration to the instrument, and wait several minutes after it has stopped. ~10
Care must be taken to stand still for several minutes and read the point at which the pointer has almost stopped moving.

This method uses a very low sliding speed (1
0 to 10 1/5 ec), so a relatively true yield value can be obtained.

Next, a method for measuring a flow curve according to the present invention will be explained. After adjusting the sample to a constant temperature of 25° C. in a thermostatic water bath, the sample is placed in a sample container and set in a rotational viscometer. Next, the flow curve was measured under the following conditions, and the shear rate (1/5ee) and shear stress (ayne/C
y+'), shear rate (1/5ec
) and the apparent viscosity (Poise, 25°C).

Measurement conditions: Side chamber temperature: 25°C Sliding speed range: 0 to 4005 ec-1 (Example 0 to 15
0 sec "1 program mode: T, =0.
1 to 20 minutes (example: 0.1 minute) T, = 0.1 to 20 minutes (example: 6 minutes) T, = 0.1 to 20 minutes (example: 1 minute) From Figure 2, rising surface m (up) The apparent viscosity at 20sθC above is taken as representative viscosity 1, the apparent viscosity at 100 sec on the down curve (down) is taken as representative viscosity 2, and (
Apparent viscosity A at 7 sec on the rising curve - (apparent viscosity B at 100 sθC on the rising curve) is defined as the viscosity difference viscosity (both at 25°C). In FIG. 2, UP indicates an ascending curve, and DOWN indicates a descending curve.

〔Example〕

Examples and comparative examples will be described below.

Comparative Example 1 Coal having the properties shown in Table 1 was crushed in advance by tfI to 5 min or less, and then mixed with 0.6% by weight of a dispersant (using a formalin condensate of sodium naphthalene sulfonate) and water based on the coal. Supplied to wet ball mill, 100kq/
h, a slurry with a coal concentration of 65% by market weight was produced. The properties of this slurry are shown in the left column of Table 2, and FIG. 4 shows the results of testing the stability of this slurry by putting it into the standing tank 1 shown in FIG. 6.

In Fig. 6, 2 is an upper layer outlet, 6 is a middle layer outlet, and 4 is an upper layer outlet.
5 is the lower layer outlet, 5 is the coal/water slurry, and the numerical values are as follows.

Table 1 Example 1 The same slurry as in Comparative Example 1 (to which a dispersant was added in the same way) was placed in a stirring tank, and a 1% aqueous solution of a stabilizer (using sodium salt of carboxymethylcellulose) was added to the slurry. 0.007% by weight of active ingredients was added to the coal, and the mixture was stirred and mixed at 1100 rpm for 10 minutes for stabilization treatment. The properties of this stabilized slurry are shown in the right column of Table 2, and the stability of this slurry was investigated by putting it into the standing tank 1 shown in FIG. 5. FIG. 5 shows the results. The slurry after the stabilization treatment remained stable without sedimentation even after being allowed to stand for two months.

Table 2 Comparative Example 2 Coal having the properties shown in Table 6 was pre-pulverized to 3 JI #l or less, and then 1.0% by weight of dispersant (using a formalin condensate of naphthalene sulfonic acid sodium salt) based on the coal was used. and water to a wet ball mill, producing 95 kq/
A slurry with a coal concentration of 72% by weight was produced in 1 hour. The properties of this slurry are shown in the left column of Table 4, and the results of stability studies in the standing tank 1 shown in FIG. 6 are shown in FIG.

Table 6 Example 2 Using the same coal and the same dispersant as in Comparative Example 2, the addition rate of the dispersant was adjusted to 0.5% by weight based on the coal, and coarsely pulverized coal was wet-processed together with the dispersant and water. The slurry was supplied to a ball mill and a slurry having a coal concentration of 72% by weight was produced at 95 kq/h. The properties of this slurry are shown in the right column of Table 4, and the test results in the standing tank 1 shown in FIG. 3 are shown in FIG. The slurry produced by adjusting the addition rate of the dispersant to a rate close to the required minimum was stable without sedimentation even after being stored statically for two months.

Table 4 Comparative Example 5 Coal having the properties shown in Table 5 was crushed in advance to a size of 3 m or less. A slurry with a coal concentration of 63.5% by weight was produced at a rate of 90 kg/h. The properties of this slurry are shown in the left column of Table 6, and the test results in the standing tank 1 shown in FIG. 6 are shown in FIG.

Table 5 Example 5 The same slurry as in Comparative Example 6 (to which a dispersant was added in the same way) was introduced into two line mixers arranged in series and continuously stirred at a high speed of 1 l and 100 rpm. The properties of the slurry after treatment are shown in the right column of Table 6 and in Figure 5:
The test results for tank 1 are shown in Figure 9. The slurry subjected to high-speed agitation remained stable without sedimentation even after being allowed to stand for one month.

Table 6 and Figure 10 show the relationship between the experimental value of the stable period and the estimated value of the stable period using the experimental formula from the above experimental data.

That is, the stability period is determined by the yield value (dynelcm), viscosity (Poise, 20 see up), viscosity (P
oise, 100Sec aQWn), viscosity differential viscosity (Poise, 7 sec up -100se
c up), and the stable period was determined from this empirical formula.

In addition, Figs. 11 to 13 show examples of adjusting the physical properties of coal/water slurry compositions by various stabilization treatment methods and the relationship between the estimated stability period, and Fig. 11 shows the relationship between the stabilizing side addition rate and the coal/water slurry composition. Figure 12 shows the relationship between the dispersant addition rate and the physical properties of the coal/water slurry, and Figure 13 shows the relationship between the applied shear energy and the physical properties of the coal/water slurry.

〔Effect of the invention〕

As explained above, according to the method of the present invention, long-term stability of the product slurry can be achieved. Also, conventionally,
Excessive amount of stabilizer was added for stabilization, and as a result, the product slurry thickened over a long period of time, degrading quality and increasing costs. However, according to the method of the present invention, This has the effect of preventing deterioration (thickening) of product slurry quality and increase in stabilization cost due to excessive stabilization treatment.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory diagrams of the flow curve measurement method in the present invention. Figure 1 is a diagram showing the relationship between shear rate and shear stress, and Figure 2 is a diagram showing the relationship between shear rate and apparent viscosity. Figure 3 is an explanatory diagram of the static tank used in the Examples and Comparative Examples, Figure 4 is a diagram showing the relationship between the number of days elapsed and the coal concentration of the coal/water slurry without the addition of a stabilizer. Figure 5 is a diagram showing the relationship between the number of days elapsed and coal concentration for coal/water slurry with stabilizer added, Figure 6 is a diagram showing the relationship between the coal concentration and the number of days elapsed for coal/water slurry with stabilizer added.
A diagram showing the relationship between the number of days elapsed and the coal concentration of the coal/water slurry with t% (to coal) added, Figure 7 shows the dispersant Q, 5
A diagram showing the relationship between the elapsed number of days and the coal concentration of the coal/water slurry with wt% (relative to coal) added. Figure 8 shows the relationship between the elapsed number of days and the coal concentration of the coal/water slurry to which no shear energy is applied (untreated). Figure 9 is a diagram showing the relationship between the number of days elapsed and the coal concentration of the coal/water slurry to which shear energy was applied by the line mixer.
Figure 11 is a diagram showing the relationship between estimated stability period values and experimental values during stability period, Figure 11 is a diagram showing the relationship between stable north side addition rate and physical properties of coal/water slurry, and Figure 12 is a diagram showing the relationship between the stable north addition rate and the physical properties of the coal/water slurry. FIG. 13 is a diagram showing the relationship between the weight and the physical properties of the coal/water slurry, and FIG. 13 is a diagram showing the relationship between the applied shear energy and the physical properties of the coal/water slurry.

Claims (1)

[Claims] 1. When preparing a slurry by mixing carbonaceous solids such as coal, oil coke, and petroleum pitch, water, and additives, the viscosity at a shear rate of 20 sec^-^1 on the rising curve of the flow curve of the slurry is set to 25. The viscosity at a shear rate of 100 sec^-^1 on the descending curve of the slurry flow curve is 5 to 30 poise at 25 °C, and the viscosity differential viscosity is 5 to 70 poise at 25 °C. A method for stabilizing a carbonaceous solid/water slurry, the method comprising adjusting the yield value of the carbonaceous solid/water slurry to a range of 0.5 to 30 dynes/cm^2.