JPH0248031Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a pulverizer that can be applied to a vertical pulverizer or a horizontal pulverizer having an external classifier.

(Prior Art) FIG. 1 shows an example of a conventional pulverizer, in which a powder raw material 6a is fed into a bowl 8a from a feed pipe 6 passing through a classifier 5 disposed in a pulverizer main body 3.
The powder is supplied to the top and is finely pulverized by the roller 4 which is pressed against the outer circumference of the bowl 8a, which is rotated by the drive unit 8 under a load applied by an external force A, to become a granular material 1, and this granular material 1 is introduced. It is conveyed by hot air 2 supplied through a tube 9, and coarsely classified according to the conveyance flow rate. Furthermore, in order to classify into particles of a predetermined size,
It is usually classified by the fixed or rotating classifier 5 equipped with vanes 7, and those with a product particle size are taken out from the product powder outlet 10, and those with a coarser particle size fall onto the bowl 8a and are re-classified. be crushed.

(Problem to be solved by the invention) In the conventional pulverizer, the recirculated coarse particles contain about 20% or more of the product particles to be taken out from the outlet 10. Therefore, more power is required for grinding,
In addition, there was a limit to the particle size of the product.

In addition, the amount of hot air 2 used to convey the powder 1 depends on the crushing capacity of the pulverizer main body 3, and when it is used for pulverized coal combustion in a pulverizer, the coal/air ratio depends on its combustion characteristics. Since it has a large influence, it is necessary to secure an approximately constant amount. Therefore, between the rollers 4 and the classifier 5 shown in FIG. 1, the particle size of the granular material 1 was determined by the flow velocity of the hot air for conveyance, and the amount of recirculation through the granules reached 4 to 8 times the finished weight.

The present invention has been proposed to solve the above-mentioned conventional problems.

(Means for Solving the Problems) Therefore, in the present invention, powder and granules are fed onto a bowl through a feed pipe passing through the inside of a classifier disposed in the main body of a pulverizer. In a pulverizer, the pulverized powder is dried with hot air supplied from an inlet pipe below the periphery of the bowl, and at the same time is conveyed upward and classified by the classifier. Near the vessel,
An air nozzle for blowing out the hot air is provided branching from the introduction pipe, and this is used as a means for solving the problem.

(Operation) The powder that falls onto the bowl through the feed pipe passing inside the classifier is finely pulverized by the rollers. This finely pulverized powder is dried by hot air supplied from an inlet pipe below the periphery of the bowl and is conveyed upward, and coarse particles are returned to the bowl after passing through the inside of the classifier. The fine powder having a predetermined product particle size is discharged from the upper part of the pulverizer main body.
At this time, the hot air jetted from the air nozzle installed near the classifier swirls or brakes the flow of powder and granules that tends to rise almost vertically in a drifted state due to the influence of the rollers. Coarse classification can be performed upstream, thereby reducing the amount of recirculation.

(Embodiment) The present invention will be described below with reference to the embodiments shown in the drawings. FIG. 2 shows one embodiment of the present invention. In the figure, 23 is the main body of the pulverizer, which includes the feed pipe 11 for the powder raw material passing through the inside of the classifier 16, and the classifier 1.
6, a bowl 12 that is supported by a drive shaft 13 and rotates, a roller 14 that is pressed when an external force A is applied to the outer periphery of the bowl 12, and a pulverizer that uses hot air 15. An introduction pipe 22 introduced into the main body 23 and branched from the introduction pipe 22,
An air nozzle 19 that blows out hot air 15 is provided near the classifier 16. In addition, in the figure, 17 is a guide plate (chlamifer vane) provided on the upper side of the classifier 16, 18 is a branch duct branched from the introduction pipe 22, and 20 is a branch duct from which hot air is sent to the classifier 16. 21 is a cold air pipe for tempering, and 24 is a product powder outlet at the upper part of the classifier.

Next, to explain the operation, the granular raw material is fed from the feed pipe 11 through the inside of the classifier 16 onto the bowl 12. Since the bowl 12 is supported by the drive shaft 13 and rotates, the supplied raw material moves to the outer circumference of the bowl 12 due to this rotation.
Since the crushing roller 14 is forcefully pressed against the outer periphery by the external force A, the roller 14 rotates while the raw material is caught between the outer periphery of the bowl 12 and the roller 14.

Since the circumferential speed is different between the center side and the outer circumferential side of the bowl 12, the supplied powder and granular material is transferred to the roller 1 on the outer circumferential side.
4 to be ground to fine powder. This finely pulverized material is dried by hot air 15 supplied from around the bowl 12 and is conveyed upward. The finely pulverized powder and granules guided to the outer periphery of the classifier 16 are given a swirling force by the guide plate 17, and the coarse ones are returned to the bowl 12 through the inside of the classifier 16, and are returned to a predetermined level. Fine powder of product particle size is passed through the product powder outlet 24 provided at the upper part of the classifier 16.
more excreted.

By the way, at this time, hot air 15 is placed near the classifier 16.
Since an air nozzle 19 is installed to blow out hot air 15 , a part of the hot air 15 guided to the introduction pipe 22 is jetted out from the air nozzle 19 toward the classifier 16 . Therefore, under the influence of the rollers 14, a swirling or braking effect is applied to the flow of the powder and granular material which tends to rise substantially vertically while maintaining a drifted flow. In addition, the cold air from the tempering cold air pipe 21 is branched from the pulverizer cold air system, and the amount of hot air input to the pulverizer is branched because it affects the pulverizer. The amount of hot air is limited to about 10-15% of the total. The air nozzle 19 can be tilted horizontally, vertically, and can also be moved forward and backward in order to give directionality to the air nozzle 19.

(Effect of the invention) The coarse particles that are classified by the classifier and recycled usually contain about 20% or more of the product particles. This is because the amount of powder and granules introduced into the classifier is larger than necessary, which exceeds the capacity of the classifier.

In this invention, an air nozzle that blows out hot air is installed near the classifier in the pulverizer main body, so the powder and granules that blow up from below can be coarsely classified on the upstream side, and the amount of recirculation is By reducing the amount of powder and granules having a sufficient capacity for the classifier, it is possible to reduce the amount of recirculation of powder and granules of product size, and thereby the power consumed for pulverization can also be reduced.

Previously proposed Japanese Patent Application Laid-Open No. 57-140658 includes a blow-up nozzle on the side of the casing that blows air toward the lower surface of the bowl, and an air blower that opens toward the lower part of the crushing roller on the upper side of the bowl. A roller mill with a spout is shown.

In a roller mill, primary classification by gravity (gravity classification) is generally performed while the airflow rises from the bowl to the classifier inlet, and this gravity classification is more effective as the rising flow rate is smaller. However, in the conventional roller mill, air is injected from the air outlet directly above the bowl, so the rising flow velocity increases and effective gravity classification cannot be performed.
Therefore, with this conventional roller mill, it is not possible to reduce the proportion of coarse powder entering the classifier.

That is, in the conventional roller mill, since air is injected directly above the bowl, the flow velocity of the air flow inside the mill is much higher than in the present invention in which air is injected near the classifier. Therefore, the present invention can perform primary classification (gravity classification) more effectively than the conventional mill roller.

Furthermore, in the present invention, even more effective gravity classification can be performed by injecting air just before the end of the effective gravity classification to apply a brake on the upward flow, and the coarse powder enters the classifier. The ratio can be made even lower.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an example of a conventional pulverizer, Fig. 2 is a longitudinal sectional view of a pulverizer showing an embodiment of the present invention, and Fig. 3 is a planar sectional view of the air nozzle section in Fig. 2. It is a diagram. Explanation of the main parts of the diagram, 11...Feed pipe, 12...Bowl, 13...Drive shaft, 14...
Roller, 15... Hot air, 16... Classifier, 17
... Guide plate, 18 ... Branch duct, 19 ... Air nozzle, 22 ... Introductory pipe, 23 ... Pulverizer main body, 24 ... Product powder outlet.

Claims (1)

[Scope of utility model registration request] Powder and granules are fed onto the bowl through a feed pipe that passes through the classifier installed in the pulverizer main body, are pulverized by rollers on the bowl, and are fed from the introduction pipe below the periphery of the bowl. In the pulverizer, which is dried with hot air and simultaneously transported upward and classified by the classifier, an air nozzle that blows out the hot air is introduced near the classifier in the pulverizer main body. A pulverizer characterized by being installed by branching from a pipe.