JP2001246276A - Installation for pulverizing coal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To completely prevent coal from being accumulated in and scattered toward the mill side and the hot air duct side at the time of swirling air current. SOLUTION: This installation for pulverizing coal comprises a pulverizing apparatus 5 for pulverizing coal with a pulverizing wheel rotated by a driving source and a pulverizing roller rotated interlockingly with the rotation of the pulverizing wheel and a hot air duct 29 for introducing hot air for drying and air-transporting the coal pulverized with the coal-pulverizing apparatus 5. A damper 50 is installed in the hot air duct, so that hot air can be supplied to the coal-pulverizing apparatus 5 through the hot air duct without any troubles during the normal operation and the scattering coal from the coal-pulverizing apparatus can be prevented from entering the hot air duct at the time of stopping operation of the installation for pulverizing coal by almost completely closing the channel of the hot air duct. A water infection apparatus 52 for washing the scattered coal is installed near the damper 50. Further, the hot air duct is joined to the coal-pulverizing apparatus 5 through a horizontal part duct and an inclining part duct and the damper 50 is installed in the peripheral part of the boundary of both ducts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a coal crusher,
The present invention relates to a coal crushing facility suitable for safely discharging remaining coal in a crusher after an emergency stop without leaving it in the system.

[0002]

2. Description of the Related Art In a direct coal combustion system, a coal pulverizing facility includes a pulverized coal mill (hereinafter referred to as a mill) for pulverizing coal, and hot air for introducing hot air for drying and conveying the pulverized coal. It consists of a duct, a coal feeder for supplying coal (raw coal) to the pulverized coal machine, and a transport pipe for supplying pulverized and dried pulverized coal to the burner.

FIG. 5 shows a typical flow of a coal-fired boiler using the pulverized coal machine. As shown in the figure, in the coal-fired boiler, the combustion air A is divided into primary air B and secondary air C after passing through the forced draft fan 1. further,
The primary air B is divided into cold air which is directly sent to the pulverized coal machine 5 after passing through the primary air pusher 4 and hot air which is superheated through the air preheater 3. Then, the cold air and the hot air are mixed before the pulverized coal machine, and the inlet temperature of the pulverized coal machine 5 is controlled to be a predetermined temperature. The secondary air C is sent to the boiler 8 after being superheated through the steam-type air preheater 2 and the air preheater 3.

On the other hand, coal D is supplied from coal bunker 6 to coal feeder 7
And is supplied into the pulverized coal machine 5 through the pulverized coal machine 5 to be pulverized. The pulverized coal is transported to the burner 26 of the boiler 8 by the primary air B, and is burned in the boiler 8 by the secondary air C.

In FIG. 5, reference numeral 9 denotes a dust collector, 10 denotes a denitration device, 11 denotes an induction ventilator, 12 denotes a desulfurization device, and 13 denotes a chimney.

[0006] The pulverized coal machine 5 is configured as shown in FIG. As shown in FIG.
4, coal D having an average diameter of about 2 to 70 mm is supplied and falls onto the crushing table 16. Grinding table 16
Is connected to the electric motor 17 through the speed reducer 32,
It is rotating at 0 to 40 rpm. Also, grinding table 1
A crushing load is applied to a crushing roller 18 on a crushing wheel 19 attached to 6 by an external pressing device 20. The crushing roller 18 rotates with the rotation of the crushing wheel 19. Then, the coal D that has dropped on the crushing table 16 is transported by a centrifugal force between the crushing wheel 19 and the rotating crushing roller 18, crushed when passing through the space, and sent to the upper part of the throat 21.

On the other hand, the primary air B superheated to about 150 to 300 ° C. is uniformly supplied to the throat 21 through the hot air duct 29 and the chamber 22, and conveys the pulverized coal at the upper part of the throat while drying. Relatively fine particles of the pulverized coal are conveyed by the primary air B and sent to the classifier 24 via the vane 23. Further, the coarse particles are separated from the airflow as the air flow velocity decreases, and returned to the pulverizing table 16 again (this is referred to as primary classification). In the classifier 24, centrifugal force acts on the coal particles due to the swirling flow, and relatively coarse particles fall down in the classifier 24 and are returned to the crushing table 16 from the hopper 25 again (this is referred to as secondary classification). Then, only the fine particles are supplied to the burner 26 through the coal feeding pipe 15.

Further, foreign matters (stones, iron pieces, etc.) in the coal fall on the heated primary air B passing through the throat 21, and the pyrite probe (also called a scraper) 2
7 and is discharged to the outside at regular intervals. That is, the foreign matter is raked up by the rotating pyrite probe and stored in the pyrite box.

On the other hand, when the pulverized coal machine 5 is stopped in an emergency (hereinafter referred to as a trip), the coal circulating in the pulverized coal machine 5 accumulates on the pulverizing table 16 and the pulverizing wheel 19, and a part passes through the throat 21. , Deposited in the chamber 22. The deposited residual coal F ignites spontaneously if left unattended, and may sometimes lead to the occurrence of a fire. In addition, at some point, the remaining coal will burn (heat generation state), and will be picked up when hot air is supplied at the next startup, After the trip, after the trip, the inside of the pulverized coal machine 5 is made inert (inert), and only the electric motor 17 is turned alone to remove the residual coal on the grinding table 16 and the grinding wheel 19 by centrifugal force. It is dropped into the chamber 22 from the throat 21 and collected in a pyrite box 28 by a pyrite probe 27 and discharged out of the system (referred to as a swirl). Here, the swirl means that the mill is rotated to discharge residual coal in the mill without supplying coal and air to the mill during a trip.

However, the pyrite probe 27 has a peripheral speed of several meters.
Because of the rotation at the speed of / sec, the coal and the deposited coal falling into the chamber 22 may be pushed out toward the hot air duct 29 side by the centrifugal force or may be splashed and deposited (G). If left unchecked, there is a possibility that serious accidents may occur due to self-combustion, as described above.

During swirling, water is sometimes injected to cool and clean the inside of the chamber 22, and a mixture of residual coal (F) and water is pushed out by the pyrite probe 27 and rises along the hot air duct 29 to be horizontal. Department.

[0012]

The above-mentioned prior art is based on residual coal (G) which is scattered by centrifugal force to the hot air duct side by a mill pyrite probe 27 rotating at the time of mill swirl,
Alternatively, the coal falling from the grinding wheel through the throat may be driven out by the pyrite probe and scattered to the hot air duct 29 side, and may be deposited on the hot air duct 29 side, particularly in a horizontal portion. The deposited coal ignites itself with the help of the preheating of the hot air duct 29 before the next mill operation, and becomes a burning state. It scatters when fresh hot air is supplied at the next start of the mill, and in the worst case, dust. Risk of explosion.

[0013] In addition, after the swirl, confirming the presence or absence of residual coal one by one affects the next mill operation schedule, and can also limit the boiler load.

As a countermeasure for preventing coal from being scattered to the hot air duct side, there is a method of providing a baffle plate 30 as shown in FIG. 4, but it is effective locally but removes all scattered coal G. Does not reach. In addition, there is no effect on an object rising along the duct 29. In addition, it is conceivable to take an angle and a height such that coal does not accumulate even if the coal is scattered in the hot air duct, but a large space is required in arrangement, and this is not necessarily a fundamental solution.

An object of the present invention is to completely prevent coal deposition and scattering on the mill side and hot air duct side during swirl.

[0016]

In order to solve the above problems, the present invention employs the following configuration.

A pulverizer for pulverizing coal by a pulverizing wheel rotated by a driving source and a pulverizing roller rotating with rotation of the pulverizing wheel; and a pulverizer for drying and pneumatically conveying the pulverized coal by the pulverizer. A hot air duct for introducing hot air, and a coal pulverizing facility comprising, during normal operation, hot air is supplied from the hot air duct to the pulverized coal machine without hindrance, and when the coal pulverizing facility is stopped. A damper for closing the passage of the hot air duct in the hot air duct so as to prevent coal scattered from the pulverized coal machine from entering the hot air duct side, and a water injection device for washing the scattered coal near the damper. Coal pulverization equipment equipped with.

Further, in the coal pulverizing facility, the hot air duct is connected to the pulverizer through a horizontal duct and an inclined duct, and the damper is located near a boundary between the horizontal duct and the inclined duct. Coal crushing equipment to be installed in

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A coal pulverizing facility according to an embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 shows a configuration of an isolation damper and a water injection configuration of a coal pulverization facility according to an embodiment of the present invention. In FIG.
Numeral 0 is installed in the hot air duct 29 and is rotated so as not to hinder the flow of the hot air B during the operation of the normal pulverized coal machine 5.
1, the damper 50 is rotated, and the hot air duct 29 is isolated from the pulverized coal machine 5 side. Further, a washing water injection section 52 is provided around the damper to wash the coal scattered to the hot air side.

The damper 50 is installed parallel to the hot air duct 29 during normal operation (open), and is closed by the actuator 51 at the start of swirl. Coal scattered from the pulverized coal machine 5 due to the start of the swirl
It collides with 0 and falls on the slope of the hot air duct 29. A gap H is provided between the hot air duct 29 and the lower part of the damper 51, and a water injection part 52 is provided on the upstream side of the duct. Coal on the slope of the duct is pushed into the chamber 22 by the shape of the slope and water injection. It is returned and can be discharged into the pyrite box 28 by the pyrite probe 27.

Due to the configuration and arrangement of the damper 50 of the present embodiment, the scattered coal falls here and does not go further upstream of the duct.

Further, a gap H is provided below the damper, and the washing water flows from the upstream side of the duct, so that the coal on the slope of the duct can be flown to the chamber side without leaving.

Next, FIG. 2 shows an isolation damper and a water injection structure of a coal pulverizing facility according to another embodiment of the present invention. The damper of the present embodiment is a guillotine damper 53 of a lifting type,
The cleaning water is applied to the damper 53 side.
During normal operation, the damper 53 is at its highest position and has a structure that does not hinder the passage of hot air.During swirl, the damper descends and scattered coal from the pulverized coal machine collides with the damper and enters the horizontal part of the duct. I try not to.

Since the washing water 52 is also injected into the duct side, it is possible to prevent the coal from adhering to the duct even when highly adhesive coal is scattered, and to inject water into the inclined surface of the duct (see FIG. 2). (The upper figure shows the water injection state at the bottom.)
There is also no residual coal on the inclined surface, and there is no danger of self-ignition, and since the water flows between the sliding surface of the damper and the duct surface, the drive of the damper due to the narrowing of coal between both surfaces is impeded. No more.

As described above, according to the coal pulverizing equipment according to the embodiment of the present invention, the following configuration and function are provided. That is, in order to completely isolate the mill and the hot air duct side during swirling, during normal operation, an openable / closable damper is installed in the hot air duct so that hot air can be supplied without any obstacles, and A water injection facility will be installed to wash the coal received by the damper.

The damper installed in the hot air duct is open during normal operation, and the hot air freely flows into the mill. On the other hand, at the time of swirl, the damper is closed. Thereby, the coal scattered from the mill side is received by the damper and falls to the lower surface (slope) of the hot air duct. The fallen coal is flushed to the mill side by the washing water and discharged to the outside from the pyrite box, so there is no coal accumulation in the hot air duct.Therefore, there is no self-ignition of coal and the mill can be operated safely. it can.

[0027]

According to the present invention, the coal can be prevented from being scattered and deposited on the hot air duct during swirl, so that the self-combustion of the coal and the ignitable combustion of the coal in the hot air duct can be prevented. As a result, it is possible to prevent coal dust explosion due to coal scattering when hot air is supplied at the next start of the mill, and to operate the mill safely.

In addition, when fresh air is supplied when a manhole is opened for inspection or the like at a place where flammable combustion occurs, a fire may develop, but this can be prevented.

Further, since the hot air duct is installed in the hot air duct without disturbing the flow, the pressure loss can be minimized, and the hot air duct can be made high and the inclination angle can be made small. Can save.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a separation damper and a water injection configuration of a coal pulverization facility according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a separation damper and a water injection configuration of a coal pulverization facility according to another embodiment of the present invention.

FIG. 3 is a diagram showing a configuration and an arrangement of a baffle provided on a hot air damper according to the related art.

FIG. 4 is a diagram showing a system of a conventional coal-fired boiler.

FIG. 5 is a view showing a conventional coal pulverizing facility.

[Explanation of symbols]

 Reference Signs List 5 Pulverized coal machine 19 Crushing wheel 21 Throat 22 Chamber 27 Pyrite pro 29 Hot air duct 50 Damper 51 Actuator 52 Water injection device 53 Guillotine damper B Hot air (primary air) F Residual coal G Deposited coal H Gap I Pyrite pro rotation direction

Continued on the front page (72) Inventor Yoshito Kawamoto 6-9 Takaracho, Kure-shi, Hiroshima Prefecture Inside Babcock Hitachi Kure Factory (72) Inventor Taketoshi Tanabe 6-9 Takaracho, Kure-shi Hiroshima Prefecture Inside Babcock Hitachi Kure Factory (72) Inventor Tadashi Hasegawa 6-9 Takara-cho, Kure City, Hiroshima Prefecture F-term in Babcock Hitachi, Ltd. Kure Plant (reference) 4D063 EE03 EE12 EE22 4D067 EE13 EE39 GA04 GB03

Claims (2)

[Claims] 1. A pulverized coal machine that pulverizes coal by a pulverizing wheel rotated by a driving source and a pulverizing roller that rotates with the rotation of the pulverizing wheel; and drying and pneumatically conveying the pulverized coal by the pulverized coal machine. A hot air duct for introducing hot air, for supplying hot air from the hot air duct to the pulverized coal machine without any problem during normal operation, A damper for substantially closing the passage of the hot air duct is provided in the hot air duct so that coal scattered from the pulverized coal machine does not enter the hot air duct side when stopped, and the scattered coal is washed in the vicinity of the damper. Coal pulverization equipment characterized by having a water injection device. 2. The coal pulverizing facility according to claim 1, wherein the hot air duct is connected to the pulverizer through a horizontal duct and an inclined duct, and the damper is inclined with the horizontal duct. Coal pulverization equipment, which is installed near the boundary of the duct.