JPS6312660B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention crushes and pulverizes a solid substance containing moisture supplied onto a rotating round table using rollers or balls, and dries the solid substance containing moisture by hot air blown upward from below the gap around the round table.
The generated fine powder is transported to an air classifier installed above the round table, and the fine powder of the required fineness is taken out of the system.
The present invention also relates to a method for drying and pulverizing a solid material containing moisture, which comprises returning the solid material falling from the gap around the round table onto the round table using a suitable transporter. In conventional devices of this type, when drying and pulverizing cement raw materials, the raw materials supplied onto a rotating round table are moved around the round table by the centrifugal force accompanying the rotation of the round table, while some of the raw materials are moved around the round table by rollers or The cement raw material that is crushed and crushed by the pressure of the ball and reaches above the gap around the round table is dried by being blown away by an ascending jet of hot air. In this case, relatively fine particles (particularly fine powder) are transported and classified by gas to an air classifier installed concentrically above the round table, and only the fine powder of the desired fineness is extracted from the system, while other coarse particles are Return it to the table and crush it again. In addition, relatively coarse particles (particularly granules) are returned to the center of the round table and crushed together with the coarse powder. A characteristic of this type of conventional equipment is that when crushing cement raw materials on a round table with rollers or balls, the power required to rotate the round table is significantly smaller than that of a tube mill, generally less than half.
the amount of hot air blown out through the gap around the round table;
The pressure loss is large, the driving power of the fan that draws the hot air is greater than the power required to rotate the round table, and the power required for the entire system is only slightly smaller than that of a tube mill. Moreover, if the moisture content of the cement raw material is not particularly high, such as a few percent, half of the current air volume is sufficient as a drying heat source in terms of calorific value. In other words, the current air volume is used only to prevent solid materials moving above the gap around the round table from falling through the gap, to transport fine powder to the air classifier, and to blow coarse particles or uncrushed materials back into the center of the round table. It is determined by the amount of energy supply medium. In other conventional devices of this type, solid materials are allowed to fall through the gap and then returned to the center of the round table using a bucket elevator or the like. This is true, for one thing, when dealing with materials that are difficult to crush or crush, and that remain in the equipment for long periods of time, causing significant wear on the rollers, balls, and round tables, or the accumulation of which makes it impossible to continue operation. Although it has the effect of reducing the maintenance burden on the equipment and improving the operating rate, there is no idea of actively trying to make solid substances fall, and the idea is to prevent solid substances that move into the above-mentioned gaps from falling in the future. In order to transport the fine powder to the air classifier and to blow back the coarse particles or uncrushed material to the center of the round table, the amount of gas, wind speed, etc. are still large, and the power is almost the same as the above-mentioned device. In another conventional device, almost no gas is ejected from the gap around the round table, and solid substances are actively dropped from around the round table, collected, and transported by a bucket elevator to be supplied to the air classifier. It is sometimes classified into fine powder and coarse powder, and the coarse powder is returned to the round table. However, this can be applied to dry materials or materials that do not contain moisture such as cement clinker, but if the solid material contains moisture, there is a small probability that the solid material will be crushed by a roller or ball on a round table. Due to the characteristics of the crushing equipment, the amount of powder falling downward from around the round table increases significantly, and the transportation system used to extract, lift and guide the coarse powder to the air classifier, and return the coarse powder to the round table is complicated. The disadvantage is that the equipment cost and maintenance cost increase as the device becomes larger and larger. Furthermore, there was a drawback that a separate dryer was required for raw materials containing moisture. The present invention has been proposed in order to solve the above-mentioned conventional drawbacks, and is a drying method for solid substances containing moisture, in which: Amount of solid material falling from around a round table/Amount of ground powder≧0.2 0.7≦Amount of ground powder/Hot air It is an object of the present invention to provide a method for pulverizing solid substances that can reduce pressure loss and fan power by setting the weight to 1.3, thereby reducing maintenance costs, equipment costs, etc. Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show embodiments of the present invention. In the figure, a round table 2 is rotated between horizontal planes by a drive device 1, a crushing drying chamber 3 extends above the table, a chute 4 supplies materials to be crushed, and a layer of solid material supplied onto the round table 2 is collected inside the chute 4. Two rollers 5, 5 that rotate by friction as the round table 2 rotates; a shaft 7 that supports the rollers 5 and passes through the casing 6; an annular gas ejection zone 8 and a solid material surrounding the round table 2; Gaps 10 and 10' forming the drop zone 9, a discharge passage 11 directly below the gap 10' of the drop zone 9, and a hot air chamber 12 for supplying gas to the gas ejection zone 8 are provided. Further, above the grinding drying chamber 3, there is a coarse powder outlet 13 that opens above the center of the round table 2, a powder/granular material containing gas inlet 14 with a guide blade on the upper side, and a fine powder containing gas outlet 15 connected to the center of the top. A truncated inverted conical air classifier 22 equipped with a solid material inlet 17, a shaft 20 for rotating the dispersion plate 18 and a rotor 19, and a fine powder-containing gas outlet 21 at the top is used to carry out the method of the present invention. This is shown as an example of the applied crushing device. In addition to the above, this device also includes a solid material discharge path 11.
Chain conveyors 23 and 25 are connected to the air classifier 22, and a bucket elevator 24 is provided to transport the material to be crushed to the supply port 17 of the air classifier 22. Exhaust gas from the firing apparatus suspension preheater (not shown) is ejected into the pulverizing drying chamber 3 through the hot air chamber 12 by an induction fan (not shown) and the gap 10 in the gas jet zone 8, and is blown out by the rotation of the round table 2. The resulting centrifugal force blows away the solid material that has moved into this zone 8, and carries it with it to the air classifier 1.
6 from the gas inlet 14 on the upper side of the classifier 16.
It becomes a swirling flow, separates coarse powder, and enters the air classifier 22 from the fine powder-containing gas outlet 15. On the other hand, the solid material supplied from the solid material supply chute 17 to the center of the round table 2 is spread around by the centrifugal force generated as the round table 2 rotates. During this time, the round table 2 is
The solid material sandwiched between the two is crushed and crushed. A portion of this solid material moves to the gas ejection zone 8;
It is blown away by the gas flow jetting upward, a part of which is guided to the air classifier 16, and the rest is blown back to the center of the round table 2. Other solid substances that have moved to the fall zone 9 and gap 10 around the round table 2 are
Passing through the discharge path 11, chain conveyors 25, 23,
It is transported by a bucket elevator 24 and guided to the solid material supply port 17 of the air classifier 22. The solid substance supplied to the solid substance supply port 17 is sent to the dispersion plate 18, and is scattered around by the centrifugal force generated as the plate rotates. Here, the solid substance is guided from the fine powder-containing gas outlet 15 of the air classifier 16, and is dispersed in the swirling upward fine powder-containing gas.
It rotates upward and is struck by the rotary blades 19, and the coarse particles are blown to the peripheral wall and fall into the air classifier 16 from the wall surface. The fine powder that is not struck by the rotary blade 19 further swirls upward, is discharged through the fine powder-containing gas outlet 21 above the air classifier 22, and is collected as fine powder by a collector (not shown). The present inventors have found that the following conditions are most suitable for achieving the above-mentioned effects in a comprehensive manner including equipment costs, maintenance costs, operating costs, etc. That is, (a) (amount of solid material falling from around the round table) / (amount of fine powder) = CF/P≧0.2 (b) 0.7≦ (amount of fine powder) / (weight of hot air) = P/G≦1.3 or less To explain the above basis in detail, CF/P
In order to maintain <0.2, it is necessary to blow most of the solid substances that have moved around the round table back to the center of the round table, or to transport the gas to the air classifier installed above the round table. In addition to the use of exhaust gas circulation, it is necessary to provide a large amount of hot air and a high gas velocity in the gap around the round table, and as with conventionally known devices of this type, pressure loss and fan driving power are high. However, if CF/P≧0.2 is given, at least a part of the solid material that has moved around the round table will not be blown back to the center of the round table, but will fall from around the round table, allowing transport equipment with low power requirements such as chain conveyors and bucket elevators to be used. You can take over. In addition to this, if P/G≧0.7 is given, the pressure loss will further decrease, and together with the decrease in hot air volume, the pressure loss and fan driving power will be 80% of the values of conventionally known devices of this type.
%, reduce to 40% or less. However, as P/G increases, the contact between the solid substance and the hot air and the effect of dispersing and drying the solid substance decrease.
If P/G≦1.3, fine powder quality (moisture, fineness),
There is no problem with the stability of operation, but if this range is exceeded, the degree of agglomeration of the fine powder being conveyed will increase abnormally, the classification efficiency of the air classifier will deteriorate significantly, and the amount of fine powder returned to the round table will increase. Furthermore, the amount of falling solids increases, and the moisture content of the falling solids also increases. Therefore, even if a part of it is supplied to an air classifier, the classification efficiency is low. The circulation of the above two types of solid substances increases, which in turn increases the required power. At first glance, the upper limit of P/G seems to change depending on the properties of the solid substance and the water content, but according to the results of studies conducted by the present inventors, it is almost constant. This can be explained from the drying process. In other words, in the early stage of drying (i.e., high moisture content), the driving force for drying is large and the drying speed is high, and the period is short and is not affected by P/G much, but in the final stage, there is little remaining moisture and drying is slow. Propulsive force is low and affected by P/G. When it is large, the contact and dispersion effects are low, and when it is small, they are high, which is P/G = 1.3
It is assumed that there are significant differences in drying, degree of agglomeration, and classification efficiency. In addition, in the present invention, the gap 10,1 around the round table 2
0' is divided into a gas ejection zone 8 and a solid material fall zone 9, and the latter is not made to eject gas, but the entire zone is made to eject gas without partitioning.
For example, it is possible to take advantage of the tendency that solid substances tend to accumulate and fall near the side of the roller 5 where solid substances are bitten, whereas the reaction side has a small amount of solid substances, is blown up by the jet stream, and is less likely to fall. This is also an embodiment of the present invention. Further, in the embodiment described above, since solid substances having a relatively large particle size fall, the falling substances are not carried to the supply port 17 of the air classifier 22, but are directly supplied to the round table 2. The air classifiers 16, 22 are then simplified (not shown). Furthermore, in the above-mentioned embodiments, the falling position of the solid substance may spread over the entire gap, so it becomes necessary to provide a part for collecting and discharging the falling substance. Since the present invention is constructed as described in detail above, it has the following advantages compared to the conventional example.

[Table] Next, when comparing the present invention and the conventional example regarding the falling of solid substances and external circulation to the round table, it is found that in the past, attempts were usually made to prevent the falling of solid substances, by reducing the amount of refined powder/hot air volume, and by reducing the gap around the round table. Increases passing speed. In addition, a method is used in which the wind speed is partially reduced to cause lumps to fall, and after removing highly hard materials, they are returned directly to the center of the round table. In the present invention, in order to actively cause solid substances to fall, the amount of fine powder/the weight of hot air is set to ≧0.7, and the amount of falling powder/the amount of fine powder≧0.2. Therefore, pressure loss could be reduced to 80% and fan power to less than 40%. Next, regarding the upper limit of refined powder amount/hot air weight, conventionally there was no problem because the operation was performed at less than 1/2 of this upper limit, but in the present invention, if the upper limit exceeds 1.3, hot air Contact with solid substances would reduce the drying effect, reduce the performance of the air classifier, and rapidly increase the required power, so it was suppressed to 1.3 or less. Therefore, according to the present invention, equipment can be made small and simple, equipment costs and maintenance costs can be reduced, and solid substances can be pulverized efficiently.

[Brief explanation of the drawing]

FIG. 1 is a front view of a crushing apparatus showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line A--A in FIG. Explanation of the main parts of the diagram, 2...Round table, 3...Crushing drying chamber, 5...Roller, 8...Gas ejection zone, 9
...solid material fall zone, 10,10'...gap,
11... Discharge path, 12... Hot air chamber, 13... Coarse powder outlet, 14... Gas inlet containing powdery granular material, 1
5... Fine powder-containing gas discharge port, 17... Solid substance supply port, 18... Dispersion plate, 22... Air classifier.

Claims (1)

[Scope of Claims] 1. A solid substance containing moisture supplied onto a rotating round table is crushed and crushed by a roller or a ball, and the solid substance containing moisture is crushed by hot air that is blown upward from below the gap around the round table. The resulting fine powder is transported to an air classifier installed above the round table to take out the fine powder of the required fineness from the system, and the solid material falling from around the round table is transported to the air classifier installed above the round table. A method for pulverizing a solid substance containing water by returning it to a round table, characterized in that the amount of solid substance falling from around the round table/amount of ground powder ≧0.2 0.7≦amount of ground powder/weight of hot air≦1.3 How to grind the substance.