JPH0673636B2 - Pulverizer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vertical crusher, a fine crusher that can be used as a vertical crusher, a crusher (for cement production, etc.), and the like.

(Prior Art) A mill that is a crushing and feeding machine for coal in a coal-fired boiler,
It is equipped with multiple units including the standby unit, and it is common to increase or decrease the number of mills to obtain the partial load of the boiler.
Furthermore, in recent years, coal has been converted to DSS (Daily Start and Stop).
In other words, in the power plant, there is a demand to stop the boiler at night when power demand decreases and to ignite, start, and operate the boiler in the morning in preparation for daytime when power demand increases, and it is necessary to start and stop the mill. . In particular, in order to start the boiler and put it into a normal operation state, the time from the start of the mill to the crushing of coal should be as short as possible, but in the past, it was impossible because of the following mill stop and standby states. .

(1). When the mill is stopped, it will be explained with reference to the vertical baul mill shown in FIG. 1. First, the coal supply from the coal feeding pipe 4 of the mill is stopped, the coal in the mill is burned as much as possible, and then a large amount of air is fed from the air inlet pipe 8. Air was blown into the mill and the residual coal on Baul 1 was sent to a boiler for combustion or dropped into the pyrite chamber 10. However, there was a considerable amount of coal remaining on the Baul.

(2). Since there is a considerable amount of residual coal on the baul, the atmosphere inside the baul must be cooled with air, and at the same time flammable gas generated from the residual coal must be purged from the mill to ignite the residual coal and cause an explosion hazard. there were.

(3). Because of the above item (2), the temperature of the cowl, roll, casing, and the like gradually decreases because the amount of heat obtained during operation is released to the cold air. Therefore, when restarting the stopped mill, since the inside of the mill is cold, it took time until hot air was introduced to heat the inside and to add coal.

(Problems to be Solved by the Invention) The present invention is intended to solve the problem of residual coal on the baul in a conventional crusher.

(Means for Solving the Problems) Therefore, in the present invention, in the crusher for crushing the object to be crushed on the baul by the roll, the nozzle outlet is located in the vicinity of the outer peripheral side edge portion of the bawl and the coal feeding is stopped. Before stopping the subsequent mill, a nozzle is provided to inject air toward the outer peripheral edge of the crushing surface of the baul, and the residual coal on the outer peripheral side of the nozzle is blown up and blown off to the outside of the baul. It is a means to

(Operation) If compressed air is injected from the nozzle outlet toward the outer peripheral edge of the crushing surface of the baul and before the mill is stopped, the residual coal on the outer peripheral side of the nozzle blows up and at the same time the centrifugal force causes baul. Since it is blown to the outside of the mill, it can be kept warm while the mill is stopped or heated, and the mill can be maintained in a state in which it can be rapidly started.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 to 3 show an embodiment of the present invention, and a detailed perspective view of an upper surface of a bawl 1 in a vertical bawl mill of FIG. Shown in the figure. First, in FIG. 1, 1 is a cowl, 2 is a roll, 3 is a vertical shaft, 4 is a coal feeding pipe, 5 is a roll shaft, 6 is a separator,
7 is a pulverized coal pipe, 8 is an inlet pipe, 9 is a casing, 10 is a pyrite chamber, and 11 is a scraper.

The coal particles previously crushed to an appropriate particle size are supplied by dropping through the coal feeding pipe 4 and onto the baul. The vertical main shaft 3, which is the rotating shaft of the bawl 1, is driven by an electric motor (not shown) via a reduction gear (not shown). By biting coal between the rotating bawl 1 and the roll 2 having the shaft 5 fixed to the casing 9, the coal is crushed. During this time, the coal is dried by the hot air flowing in from the air inlet pipe 8, and further crushing and drying are repeated. Then, the coarse particles are classified by the separator 6, returned to the original bowl 1 and pulverized again.

On the other hand, the classified fine powder is conveyed by the hot air in the fine coal pipe 7 and burned in the boiler. A hard substance that cannot be crushed on the bawl, for example, a pyrite component in coal, protrudes from the recess of the baul 1 by the centrifugal force of the baul 1 and falls into the pyrite chamber 10 below the baul 1.
The pyrite component is transferred to a container such as a pyrite hopper by a scraper 11 that rotates together with the vertical spindle 3, and is made into a slurry with water to be conveyed and processed.

13 in FIGS. 2 and 3 indicates residual coal. This charcoal 13
Since the coal supply is stopped before the mill stops, it gradually becomes thinner and at the same time it is in a state of being accumulated near the circumference of the baul 1 by centrifugal force. Since the roll 2 is equipped with a stopper mechanism (not shown) to keep the clearance between the roll 2 and the bawl 1 at a certain level or more, the coal will not be crushed if the residual coal becomes thin to some extent. Therefore, the shape of the residual coal layer after stopping the coal supply and crushing the residual coal 13 on the baul 1 as much as possible is almost as shown in FIG. Inside the end of the bowl of the bowl 1, an air injection nozzle 12 as shown in FIG. 2 and FIG.
Is attached, and when compressed air is injected to the outer peripheral side of the residual coal 13, the residual coal is blown up and, at the same time, is blown to the outside of the baul by the centrifugal force. There, the purge air 14 is blown up, and the fine powder is conveyed by the purge air 14, passes through the fine coal powder pipe 7, and is burned in a boiler (not shown). On the other hand, since coal having a large particle size cannot obtain buoyancy with purge air, it falls into the pyrite chamber 10 and is treated by a water slurry method or the like.

(Effects of the Invention) As described in detail above, according to the present invention, the nozzle outlet is located in the vicinity of the outer peripheral edge of the bawl, and is directed toward the outer peripheral edge of the baul crushing surface before stopping the mill after stopping the coal feeding. A nozzle that injects air is provided, and the residual coal on the outer peripheral side of the nozzle is blown up and blown outside the bawl. Therefore, before the mill is stopped, most of the residual coal in the mill, which is on the baul, can be efficiently and safely treated outside the mill, so there is no need to purge the inside of the mill with cold air as in the past. By closing the outlet valve provided in the pulverized coal pipe near the air inlet and mill outlet,
The inside of the mill can be sealed. As a result, each part of the mill that has been warmed during the operation of the mill, especially the bawl, is kept warm, so that when the mill is restarted, coal feeding is started immediately, and after heating and drying, crushing is possible. Therefore, the start-up time of the mill can be shortened compared to the past.If hot air that can heat the inside of the mill while the mill is stopped can be supplied from the boiler, etc., the method of keeping the inside of the mill warm (warming) at all times is It is needless to say that it is particularly effective for the rapid start of the long-term stop mill (a small amount of hot air is introduced from the air inlet pipe 8 to heat the inside of the mill and then blown as combustion air from the pulverized coal pipe to the boiler). Also, at places where coal accumulation is expected inside the mill, residual air is similarly treated with a separate air injection nozzle.

As described above, according to the present invention, the residual carbon in the mill can be completely purged when the mill is stopped, so that the temperature can be maintained or warmed while the mill is stopped, and the mill can be maintained in a state in which it can be rapidly started. Therefore, the present invention is very effective as a quick start method for a baul mill, and it is possible to reduce the start time for each mill by about 5 minutes (it took about 30 minutes in the past) as compared with the conventional method. Since there are 6 to 8 mills in one boiler, 30 in total
Quantiles are expected to be shortened, and in the current state of DSS operation, these 30 minutes are precious.

[Brief description of drawings]

FIG. 1 is a perspective view of a vertical type baul mill which is an example of a pulverized coal machine showing an embodiment of the present invention, FIG. 2 is a detailed perspective view of a main part in FIG. 1, and FIG. 3 is A of FIG. FIG. Description of main parts of the figure 1 …… Bowl 2 …… Roll 3 …… Vertical spindle 12 …… Air injection nozzle 13 …… Residual coal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirohisa Yoshida 1-1 1-1 Atsunoura-machi, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries, Ltd. Nagasaki Research Institute (56) References: 60-79548 (JP, U)

Claims (1)

[Claims] 1. A crusher for crushing an object to be crushed on a bawl with a roll, wherein a nozzle outlet is located near an outer peripheral side edge portion of the bawl, and the outside of the crushed surface of the bawl is stopped before stopping the mill after stopping the coal feeding. A fine pulverizer characterized in that a nozzle for injecting air toward the peripheral portion is provided, and residual coal on the outer peripheral side of the nozzle is blown up to be blown outside the bawl.