JPH0745671B2 - Coal slurry manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A coal slurry obtained by mixing fine coal powder with heavy oil and further with additives such as surfactants has been developed as a fuel to replace petroleum. One of the necessary conditions for commercialization of coal slurry as a boiler fuel is to satisfy the static stability of the coal slurry, and the goal is to be stable for 30 days after manufacturing.

Regarding the stability of coal slurry, it is well known that coal species, heavy oil, additives, manufacturing method, etc. are related, but from the results of the test conducted by the applicant, the same kind of coal is used. However, it has been proved that it is affected by the difference in the history. When a coal slurry is put into practical use, the type of coal as a raw material of the coal slurry will be determined for a certain period of time, so the production conditions will be selected for that type of coal and the actual plant will be operated. However, in the case of coal, even if it is the same brand, its physical
Due to the difference in chemical properties, in practical application of a coal slurry manufacturing plant, it is essential to be able to cope with this difference in the lot of coal in order to manufacture a coal slurry of constant properties.

The present invention satisfies the above-mentioned requirements, and pulverizes coarse coal in fuel oil with a wet mill to obtain a coal slurry intermediate product, and measures the apparent viscosity of the coal slurry intermediate product on the downstream side of the wet mill. Based on the results, the grinding time of the wet mill was adjusted to produce a coal slurry intermediate product whose properties were constant regardless of changes in the properties of the coking coal, and a coal ratio of 0.
125wp% additive is added and dispersed by a line mixer to stabilize and fluidize the coal slurry, which is related to the method of manufacturing the coal slurry. Even so, it is to provide an improved coal slurry manufacturing method capable of manufacturing a coal slurry having a constant property regardless of the fluctuation.

Next, the method for producing the coal slurry of the present invention will be specifically described. Conventionally, various proposals have been made regarding the stability properties that coal slurries should have, and the applicant of the present invention has investigated the properties, and further, the relationship between the manufacturing method and the properties, from laboratory tests to real-scale tests. We have conducted various tests up to the pilot plant test. As a result, it was found that the coal slurry with stable properties formed a sufficient amount of the structure, which was apparently deposited. The basis for this will be described below by citing the test results. First
The figure shows the results of the static tank test, and the properties of the coal slurry were stable, and the properties of the coal slurry were judged to be unstable.
The distribution of coal concentration in the tank after the day-to-day static test is shown. As can be seen from Fig. 1, there is a significant difference between the in-tank coal concentration distribution of the coal slurry with stable properties and that of the coal slurry with unstable properties. FIG. 2 and FIG. 3 show an example of the test results carried out to clarify the difference between the two.
That is, FIG. 2 collectively shows the sedimentation behavior for each coal particle diameter of the coal slurry having stable properties, and FIG. 3 shows the sedimentation behavior for each coal particle diameter of the coal slurry having unstable properties. Shows. It can be seen by comparing FIG. 2 and FIG. 3 that, in the coal slurry whose properties are unstable in FIG.
Larger particles tend to settle in order, and for example, fine particles of 200 mesh or less are pushed up relatively, whereas in the coal slurry with stable properties shown in Fig. 2, fine particles of 200 mesh or less for 30 days. Even when it is left standing, it exists at the bottom in a state close to the original composition. As described above, from FIG. 1, FIG. 2, and FIG. 3 as typical examples, it is said that the coal slurry having stable properties forms a structure that can be imitated, for example, in the Ostwald scaffold structure. Conceivable.
On the other hand, in a method for producing a coal slurry using a wet mill that pulverizes coarse coal and disperses it in fuel oil to obtain a coal slurry, an abnormal viscosity due to mutual interference of solid particles known in the Ostwald scaffold structure It was also found that it can be grasped by observing the viscosity properties of the intermediate product of coal slurry at the exit of the wet mill. For example, Table 1 shows the results when coal slurries were produced under the same operating conditions by changing the lot for the same coal type and using the same wet mill.

As shown in Table 1 above, the so-called coal property values such as HGI crushing index and coal analysis value change depending on the lot, even with the same coal type. It was found to have a significant effect on the properties of the product. Based on the facts explained above, the relationship between the apparent viscosity of the intermediate product of the coal slurry at the exit of the wet mill and the bottom concentration of the product coal slurry after the 30-day static stability test is summarized and shown in Fig. 4. Indicated. In the above test, 0.125% of the additive was added to the coal slurry intermediate product at the outlet of the wet mill with respect to the coal slurry and dispersed by the line mixer to stabilize and fluidize the coal slurry.
It should be noted that other methods may be used for stabilizing and fluidizing the coal slurry as long as the use of additives and fluidization of dispersion by high shearing force can be substantially achieved. As can be seen from FIG. 4, the coal slurry having stable properties has a relatively high apparent viscosity at the exit of the wet mill (the apparent viscosity here is a value obtained by using a general B-type viscometer, and is exemplified. Numerical values are those obtained using the No. 3 rotor under the measuring conditions of 30 rpm and 5 minutes). Therefore, in order to produce a coal slurry having stable properties, it is effective to adjust the apparent viscosity at the outlet of the wet mill to a certain value or more. From the results of the coal slurry production test shown in Fig. 4, if the bottom concentration in the tank is 60% or less, preferably 57% or less, and more preferably 55% or less, it is stable and has excellent fluidity. You may decide that it is a coal slurry. According to this judgment standard, it is possible to produce a practical coal slurry by adjusting the apparent viscosity of the intermediate product of the coal slurry at the outlet of the wet mill from FIG. 4 to 3000 cp or more, preferably 3300 cp or more, and more preferably 3500 cp or more. The present invention is based on what has been described above. Coarse pulverized coal is pulverized in fuel oil by a wet mill to obtain a coal slurry intermediate product, and the apparent viscosity of the coal slurry intermediate product is determined by the downstream of the wet mill. Side, and adjust the pulverization time of the wet mill based on the measurement result to produce a coal slurry intermediate product whose properties are constant irrespective of fluctuations in the properties of coking coal.
It is characterized by adding 0.125wp% additive and dispersing it with a line mixer to stabilize and fluidize the coal slurry. By adopting this method, even if the properties of the coking coal change due to the difference in the lots that coal always experiences, it is possible to manufacture a coal slurry intermediate product having a constant property regardless of the changes.

FIG. 5 shows a structural example of an apparatus used for carrying out the method for producing a coal slurry of the present invention. In FIG. 5, (1) is a feeder that supplies coarse coal, (2) is a fuel oil supply pump, and (3) is coarse coal that is crushed in fuel oil and dispersed in the fuel oil to produce coal. Wet mill for obtaining slurry, (4) Viscometer for measuring apparent viscosity of coal slurry intermediate product, (5) Coal slurry intermediate product receiving tank, (6) Supply pump, (7) Additive supply pump , (8) is a mixing device having a shearing force equal to or higher than that of a wet mill, and the operation speed of the coarse coal feeder (1) and the fuel oil supply pump (2) can be adjusted by a measurement value signal from the viscometer (4). An eid back line is provided so that the raw material retention time (grinding time) in the wet mill (3) can be adjusted. The position of the viscometer (4) shown in FIG. 5 may be anywhere between the wet mill (3) and the mixing device (8), for example, installed in the coal slurry intermediate product receiving tank (5). It is also possible.

Next, the effects of the present invention will be described based on the test results of the same coal type using a small-scale device. Figure 6 shows
The apparent viscosity change of the coal slurry intermediate product obtained by changing the residence time (crushing time) in the wet mill is shown, and the viscosity sharply rises when the operation time of the wet mill exceeds a certain value. Point A in Fig. 6 is the condition position where it was estimated from the relationship in Fig. 4 that a coal slurry with stable properties could be obtained, and point B was a coal slurry with poor stability due to insufficient formation of the structure. It is a condition position estimated to be generated. Coal slurry intermediate product manufactured under the conditions of points A and B in Fig. 6 has a coal ratio of 0.
Fig. 7 shows the coal concentration distribution in the tank when the coal slurry prepared by adding 125 wt% of the additive and dispersing it with a line mixer was allowed to stand for 30 days. From the comparison of changes in coal concentration in FIG. 7, particularly the concentration at the bottom of the tank, it is clear that the A condition is superior to the B condition, which shows the effectiveness of the present invention.

Although the present invention has been described with reference to the embodiments, the present invention is of course not limited to such embodiments, and various design modifications can be made without departing from the spirit of the present invention. .

[Brief description of drawings]

FIG. 1 is an explanatory view showing the relationship between the height of the stationary tank and the concentration of coal in the coal slurry, and FIG. 2 shows the relationship between the height of the stationary tank and the ratio of each particle size portion to the coal in the coal slurry with stable properties. Explanatory drawing, FIG. 3 is an explanatory view showing the relationship between the height of the stationary tank and the ratio of each particle size portion to the coal in the coal slurry of which the properties are unstable, and FIG. 4 is the apparent viscosity of the intermediate product of the coal slurry after production. Explanatory diagram showing the relationship with the coal concentration at the bottom of the tank after standing for 30 days, FIG. 5 is a system diagram showing an example of the configuration of an apparatus used for carrying out the method for producing a coal slurry of the present invention, and FIG. 6 is a coal slurry FIG. 7 is an explanatory view showing the relationship between the apparent viscosity of the intermediate product and the mill operation time, and FIG. 7 is an explanatory view showing the relationship between the static tank height and the coal concentration in the coal slurry. (3) …… Wet mill, (4) …… Viscometer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiji Baba 1-1, Atsunoura-cho, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard (56) References Japanese Patent Publication No. 58-4760 (JP, B1)

Claims (1)

[Claims] 1. A wet mill grinds coarse coal in fuel oil to obtain a coal slurry intermediate product, and the apparent viscosity of the coal slurry intermediate product is measured on the downstream side of the wet mill. By adjusting the crushing time of the mill, a coal slurry intermediate product whose properties are constant regardless of fluctuations in the properties of the raw coal is produced, and 0.125wp% of the coal ratio is added to this intermediate product,
A method for producing a coal slurry, which comprises dispersing with a line mixer to stabilize and fluidize the coal slurry.