JPH11207200A - Vertical roller mill and its operation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vertical roller mill stably operated with low power consumption and the operating method in the vertical roller mill for mixing and pulverizing coal and a refuse fuel such as municipal refuse. SOLUTION: The vertical roller mill has a dam ring 15 having a rising edge part, 4 table 7 having a bull ring existing inside of the dam ring and forming a solid matter pulverizing surface and a roller 6 arranged upper side thereof and for pressing a solid matter and the dam ring 15 is formed so that the height is controlled to 1/14 to 1/10 of the diameter of the table 7. In such a case, the discharge property of the pulverized solid matter is improved and the consumption of power for the mill is saved by decreasing the height of the dam ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical roller mill for mixing and pulverizing coal and refuse fuel such as municipal refuse, and a method of operating the same.

[0002]

2. Description of the Related Art A basic structure of a vertical roller mill will be described with reference to FIG. 1 and a conventional operation state of the vertical roller mill will be described with reference to FIG.

[0003] 1 is a coal bunker for storing coal, and 2 is a waste fuel bunker for storing waste fuel such as municipal waste. 3
Reference numeral 4 denotes a fixed quantity coal feeder for transferring a predetermined amount of coal stored in the coal bunker 1, and reference numeral 4 denotes a fixed quantity waste fuel feeder for similarly transferring a predetermined amount of the waste fuel stored in the waste fuel bunker 2.

[0004] Reference numeral 5 denotes a supply pipe which is connected downstream of the coal quantitative feeder 3 and the waste fuel quantitative feeder 4 and is supplied from the coal quantitative feeder 3 and the waste fuel quantitative feeder 4. Guide the waste fuel to the downstream crushing section.

[0005] Reference numeral 7 denotes a table for pulverizing coal and refuse fuel. A bull ring 16 forming a pulverizing surface extending in a radial direction and a circumferential direction is disposed on a surface thereof, and a dam ring 15 standing upright is disposed at a peripheral portion. It is configured to be rotationally driven by a driving device (not shown).

Reference numeral 6 denotes a roller.
6, facing the upper surface and being pressed by a hydraulic cylinder 13 to cooperate with the bullring 16 to form a crushing portion for solids, that is, coal and refuse fuel.

Reference numeral 8 denotes a hot air supplied from the outside, 9 denotes a hot air guide vane disposed close to the peripheral surface of the table 7, 10;
Is a primary classifier disposed above the hot air guide vane 9 after that, 11 is a separator, and 12 is a separator 11
Classifying vanes arranged along the circumferential direction at the upper end position, and 14 denotes an outlet pipe for removing the finely divided solid coal or refuse fuel.

In the above configuration, the coal stored in the coal bunker 1 descends from the coal bunker 1 to the coal quantitative feeder 3 at the time of pulverization, and a predetermined amount is supplied to the table 7 through the supply pipe 5.

Then, the coal dropped and dispersed on the upper surface of the table 7 moves in the circumferential direction by centrifugal force due to the rotation of the table 7 and is transported to the lower portion of the roller 6, and is pressed by the roller 6 with the bullring 16. Crushed.

At this time, the hydraulic cylinder 13 is controlled by a control device (not shown) to adjust the pressurization in order to obtain the thickness of the coal layer between the table 7 and the roller 6 and the proper coal particle size from the controllability of the vertical roller mill. .

The pulverized coal thus pulverized is discharged out of the table 7 over the dam ring 15, and is dried and blown from the outer peripheral end of the table 7 through the hot air guide vanes 9 and the primary classifier 10. The hot air 8 for transport is guided to the classifying blades 12 above the separator 11 and is classified into coarse particles and fine particles.

The fine particles are transported from the outlet pipe 14 as a product to a boiler or the like and subjected to combustion or the like. The coarse particles pass through the inner wall of the separator 11 and return to the table 7 again to be reground.

On the other hand, the supply of the waste fuel from the waste fuel bunker 2 is started when the operating condition of the vertical roller mill using only coal is settled. As a specific step, the waste is first mixed and pulverized from the refuse bunker 2 through the supply pipe 5 while being controlled by the refuse fuel metering device 4 on the table 7 as in the case of coal. In this case, the rotation of the table 7 is a normal rotation, and is the same when pulverizing coal alone and when mixing and pulverizing coal and waste fuel.

FIG. 4 summarizes this driving situation.
Taking a common time axis on the horizontal axis, A roller lift, B cylinder load, C mill power, D
The solidified refuse fuel supply amount, the E coal supply amount, and the F table peripheral speed (which are kept constant at a steady value) are shown.

[0015]

In the above-mentioned conventional apparatus, soft hard-to-pulverize substances such as plastic or fiber waste mixed in the refuse fuel accumulate on the table 7 to increase the thickness of the coal layer, and the roller 6 And the power for pressing the roller 6 is increased, which causes a problem that the power of the whole mill is greatly increased.

An object of the present invention is to provide a vertical roller mill capable of operating stably with lower power and a method of operating the same, which solves such problems in the conventional apparatus. .

[0017]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a dam ring having an upright edge provided at an edge thereof and a pulverized surface for forming a pulverized surface of a solid material charged therein. A table provided with a ring, and a roller disposed above the bull ring and pressing the solid material, the height of the dam ring from the contact position of the roller and the bull ring to the top of the dam ring is set to the height of the table. 1/14 of diameter
A vertical roller mill formed in 1/10 is provided.

That is, according to the present invention, by selecting the dam ring height from 1/14 to 1/10 with respect to the diameter of the table as described above, this value becomes larger than that generally used up to now. Because it is small, in short, the dam ring height is low, the discharge of crushed solids is improved,
This suppresses the mill power.

The present invention also provides a table provided with a dam ring standing upright at an edge thereof and a bull ring provided inside the dam ring to form a pulverized surface for a solid material to be charged. In a vertical roller mill having a roller for pressing an object, when the solid is coal, the table is rotated by switching so that the solid is slower than in the case of mixing coal and refuse fuel. The present invention provides a method of operating a mold roller mill.

That is, according to the present invention, depending on the type of solid matter, when the coal is a simple substance, it is slower than the case of the coal and the refuse fuel, whereby the centrifugal force is reduced to transfer and discharge the coal. In this case, the pressing force of the roller is increased by maintaining the roller lift, thereby improving the pulverizing efficiency.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. The basic structure of the vertical roller mill has already been described as a conventional technique with reference to FIG. 1 showing the present embodiment, and the common part of the basic structure of the present embodiment is referred to in the above description. A duplicate description will be omitted, and the description will focus on features that are unique to the present embodiment.

That is, in the present embodiment, the height of the upright dam ring 15 attached to the outer peripheral portion of the table 7 in the roller mill is reduced by about 10 to 50% from the optimum height for pulverizing coal alone. It is assumed.

In this embodiment, an appropriate method such as a pole change method of a mill motor or a method of incorporating an inverter to change the number of revolutions is adopted, and the peripheral speed of the table 7 can be switched and changed as needed. It has a configuration.

More specifically, the height of the dam ring 15 will be described with reference to FIG.
When the height of the roller 5 is from the position where the roller 6 contacts the upper surface of the bull ring 16 to the top surface of the dam ring 15, and the height of the dam ring 15 is compared with the diameter D of the table 7, = (1/10) D to (1/8) D
(Approximately 0.1D to 0.125D), whereas in the present embodiment, h = (1/14) D to (1 /
10) D (about 0.071 D to 0.01 D), and preferably h = (1 / 10.5) D (about 0.095
D).

The dam ring 15 is originally a member for adjusting the amount of coal and the like held on the table 7 to promote the stable operation of the roller mill. However, if the height of the dam ring 15 is too high, the power increases. As a result, the capacity of the mill becomes insufficient.On the contrary, if the capacity is too low, the roller lift becomes low and the mill vibrates, causing the mill to lose its original performance and stable operation. It has been difficult to analyze various factors based on many years of experience to find the optimum value.

The inventors of the present application have gone through this difficulty through repeated trial and error, and have reached the specific numerical values of the present embodiment described above. By selection, a suitable vertical roller mill that operates stably with lower power can be obtained.

As shown in FIG. 3, by using a vertical roller mill having a low dam ring height h, the coal feed amount E is first started to crush the coal alone, and the timing is measured at this time. The table peripheral speed F is decreased from the steady speed so as to decrease, and the peripheral speed is returned to the original steady speed at the stage when the solidified waste fuel supply amount D starts.

That is, when the table 7 is set to the steady rotation speed, the height h of the dam ring 15 is increased in the pulverization of the coal alone.
Is reduced, the thickness of the coal layer on the table 7 is reduced, and the lift of the roller 6 is also reduced.
Also, as the wear on the roller 6 progresses, the lift of the roller 6 is lowered, and the mill vibration may increase, making it impossible to operate the mill safely.

On the other hand, in the present embodiment, the peripheral speed of the table 7 is reduced to reduce the centrifugal force to increase the thickness of the coal seam, secure the safe operation of the mill, and increase the lift of the roller 6. As a result, the crushing rate is improved by increasing the pressurization in the hydraulic cylinder 13, and a decrease in the capacity of the mill is prevented.

In the case of mixing and crushing of coal and refuse fuel, the height h of the dam ring 15 is reduced even if the table 7 is returned to the normal rotation speed. The amount of hard-to-pulverize substances such as debris accumulating on the table 7 is reduced, and the load of the roller 6 effectively acts on the accumulation on the table 7 such as grinding and shearing to improve the pulverization efficiency. Moreover, it is possible to mix and grind the waste fuel without significantly increasing the mill power as compared with the case of grinding the coal alone.

Although the present invention has been described with reference to the illustrated embodiment, the present invention is not limited to such an embodiment.
It goes without saying that various changes may be made to the specific structure within the scope of the present invention.

[0032]

As described above, according to the present invention, there is provided a table in which an upright dam ring is provided at an edge portion and a bull ring which forms a pulverized surface of a solid material charged therein is provided therein.
A roller that is disposed above the bull ring and presses the solid material; and a dam ring height from a contact position between the roller and the bull ring to a dam ring top is 1/14 to 1/1 / the diameter of the table. 10 to form a vertical roller mill.
The dam ring height selected to １／1/10 is smaller and lower than the dam ring height that has been usually adopted,
The discharge property of the crushed solid material was improved, and the mill power could be suppressed.

According to the second aspect of the present invention, there is provided a table in which a dam ring is provided upright at an edge portion and a bull ring is provided inside the dam ring to form a pulverized surface of a solid material to be charged. In a vertical roller mill having a roller disposed above and pressing the solid, when the solid is coal, the table is switched so that the solid is slower than in the case of mixing coal and refuse fuel. Since the operation method of the vertical roller mill is configured to rotate, depending on the type of solid matter, when this is coal alone, it is slower than when coal and garbage fuel, and as a result, the centrifugal force is reduced. Thus, the transfer and discharge of the coal were delayed, the roller lift was maintained, the pressing force of the roller was increased, and the pulverization efficiency was improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a configuration of a vertical roller mill according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing a configuration of a main part of FIG.

FIG. 3 is an explanatory diagram showing an outline of a vertical roller mill operation in the present embodiment.

FIG. 4 is an explanatory diagram showing an outline of operation of a conventional vertical roller mill.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coal bunker 2 Garbage fuel bunker 3 Coal quantitative supply machine 4 Garbage fuel quantitative supply machine 5 Supply pipe 6 Roller 7 Table 8 Hot air 9 Hot air guide vane 10 Primary classifier 11 Separator 12 Classification blade 13 Hydraulic cylinder 14 Outlet pipe 15 Dam ring 16 Bull Ring

Claims (2)

[Claims] 1. A table provided with a dam ring rising on an edge thereof and a bull ring forming a crushing surface of a charged solid substance disposed therein, and a table disposed above the bull ring and pressing the solid substance. A vertical roller mill, wherein a height of a dam ring from a contact position between the roller and the bull ring to a top of the dam ring is formed to be 1/14 to 1/10 of a diameter of the table. . 2. A table provided with an upright dam ring at an edge thereof and a bull ring formed therein to form a pulverized surface for a solid material to be charged, and a table arranged above the bull ring to press the solid material. A vertical roller mill having a roller, wherein when the solid is coal, the table is rotated by switching so that the solid is slower than in the case of mixing of coal and garbage fuel. Roller mill operation method.