JP4948285B2 - How to restart pulverized coal supply equipment - Google Patents

Description

  The present invention relates to a method for restarting a pulverized coal supply apparatus when a coal feeder stops due to lack of coal.

  A pulverized coal supply device for supplying pulverized coal to a pulverized coal boiler is installed in a thermal power plant or the like. Such a pulverized coal supply apparatus includes a coal feeder, a mill, and a pulverized coal conveying means. Then, the pulverized coal supply device generates pulverized coal by pulverizing the coal supplied by the coal feeder with a mill, and supplies the pulverized coal to the pulverized coal boiler using the pulverized coal conveying means. It has become.

  However, in such a pulverized coal supply device, when the load on the mill decreases or when any abnormality occurs in the mill, the coal feeder is left in a state where the mill is operated simply by stopping the mill. Otherwise, the coal remaining in the mill may ignite. Therefore, after stopping the coal feeder, it is necessary to perform a so-called mill purge in which coal remaining in the mill is discharged.

  With regard to such mill purge, there has been proposed a mill purge method that can always carry out optimal purging of coal having different pulverization characteristics without excess and deficiency, and can avoid adverse effects on the mill itself, incidental equipment, control systems, and the like. (See Patent Document 1).

JP 2001-224972 A

  To stop the mill, it is usually necessary to first reduce the load on the coal feeder, then cool the mill and then perform a mill purge. However, the proposed mill purge method cannot cope with the case where the amount of coal supplied to the coal feeder decreases and the coal feeder stops due to so-called lack of coal, and the coal feeder stops. However, there was a problem that the mill continued to operate without stopping. And when the mill was stopped manually when the coal feeder stopped due to lack of charcoal, there was a problem that the mill might stop with insufficient mill purge.

  This invention provides the restart method of the pulverized coal supply apparatus which can restart a pulverized coal supply apparatus in a state with sufficient mill purge, when a coal feeder stops by lack of coal in view of the situation mentioned above. For the purpose.

  1st aspect of this invention which solves the said subject was produced | generated by the coal feeder which supplies coal, the mill which grind | pulverizes the coal supplied from this coal feeder, and produces | generates pulverized coal, and this mill In a pulverized coal feeding device comprising pulverized coal conveying means for conveying pulverized coal to a pulverized coal burner provided in a boiler furnace, the mill is brought to a predetermined temperature or less after the coal feeder stops due to lack of coal. A cooling step for cooling, a mill purge step for purging the mill for a predetermined time after the cooling step, a burner stop step for stopping the pulverized coal burner after the mill purge step, and stopping the mill after the burner stop step A mill stop step to perform, a cause of carbon shortage of the coal feeder after the mill stop step and a lack of carbon elimination step to confirm the cause, and a temporary operation of the coal feeder after the carbon shortage elimination step Let the coal supply A temporary coal feeder operating step for stopping the coal feeder after confirming that the coal is present therein, and the coal feeder, the mill and the pulverized coal conveying means after the temporary coal feeder operating step. And a starting step of igniting the pulverized coal burner, respectively, and a restart method for the pulverized coal supply device.

  In the first aspect, the pulverized coal supply device can be started in a state where the mill purge is sufficient.

  According to a second aspect of the present invention, the pulverized coal conveying means has a blower, and the cooling step is performed by cooling the mill with air from the blower. The method is to restart the pulverized coal supply device.

  In the second aspect, the mill can be cooled without modifying the pulverized coal supply device.

  The third aspect of the present invention further includes a pyrite discharge step of discharging pyrite in the mill between the mill stop step and the decarbonization elimination step. The method of restarting the pulverized coal supply apparatus according to the aspect of the present invention.

  In the third aspect, pyrite can be reliably discharged from the mill.

  According to the restart method of the pulverized coal supply device according to the present invention, the pulverized coal supply device can be restarted with sufficient mill purge, so that the pulverized coal supply device can be restarted safely.

  Hereinafter, the best mode for carrying out the present invention will be described. The description of the present embodiment is an exemplification, and the present invention is not limited to the following description.

(Embodiment 1)
FIG. 1 is a schematic view showing a pulverized coal supply apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, the pulverized coal supply apparatus 1 according to the present embodiment includes a bunker 10 in which coal is accommodated. The bunker 10 is composed of a main bunker 10b and a sub-bunker 10a provided below the main bunker 10b. The sub bunker 10a is connected to a water storage tank (not shown) via a bunker water injection valve 5 so that water in the water storage tank can be injected. On the other hand, the sub-bunker 10a is connected to the coal feeder 20 through the coal gate 11 for supplying and shutting off coal, and a predetermined amount of coal can be supplied to the coal feeder 20. The coal feeder 20 is connected to the mill 30, operates the belt 21 disposed therein, controls the amount of coal supplied from the bunker 10, and supplies it to the mill 30.

  The pulverized coal conveying means 40 and four pulverized coal supply pipes 50 connected to the boiler furnace 100 are respectively connected to the mill 30, and the pulverized coal generated by the mill 30 is conveyed to the boiler furnace 100. Can be done. Specifically, the mill 30 pulverizes the coal supplied from the coal feeder 20 to generate pulverized coal, and the pulverized coal transport means 40 supplies air to the mill 30, the pulverized coal supply pipe 50, and the boiler furnace 100. The pulverized coal generated by the mill 30 is transported to the boiler furnace 100. The transported pulverized coal is burned by the pulverized coal burner 110 provided in the boiler furnace 100.

  The pulverized coal conveying means 40 includes a ventilator (not shown) as a blower, an air preheater (not shown), a hot air system including a gate 41 and a damper 42, a ventilator (not shown) as a blower, and a gate. 43 and a damper 44 and a cold air system, which are configured to be coupled in the vicinity of the mill 30. By configuring the pulverized coal conveying means 40 in this way, the flow of hot air supplied from the hot air system and the flow rate of cold air supplied from the cold air system are controlled, and the temperature of the air sent to the mill 30 and The flow rate can be adjusted flexibly. As a result, the mill 30 can be easily cooled below a predetermined temperature.

  Each pulverized coal supply pipe 50 is provided with a damper 51 so that the amount of pulverized coal supplied from each pulverized coal burner 110 to the boiler furnace 100 can be adjusted uniformly.

  Further, a pyrite hopper 60 is connected to the mill 30 via a pyrite hopper inlet valve 61 so that pyrite that has not been crushed by the mill 30 can be reliably discharged from the mill 30.

  The restart method of the pulverized coal supply apparatus according to the present embodiment is a method of restarting the pulverized coal supply apparatus 1 when the coal feeder stops due to lack of coal. Below, the restart method of the pulverized coal supply apparatus which concerns on this embodiment is demonstrated based on the flowchart shown in FIG.

  When the lack of coal occurs and the coal feeder 20 stops, first, the mill 30 is cooled to a predetermined temperature or lower (S1: cooling step). For example, the gate 41 and the damper 42 are closed to stop the supply of hot air to the mill 30, and the gate 43 and the damper 44 are controlled to adjust the supply amount of cold air (for example, with respect to the fully open state). The mill 30 is cooled so that the temperature of the air sent from the mill 30 to each pulverized coal supply pipe 50 is equal to or lower than a predetermined temperature (for example, 65 ° C. or lower).

  Then, after the temperature of the air sent from the mill 30 to each pulverized coal supply pipe 50 falls below a predetermined temperature, the mill 30 is purged for a predetermined time (S2: mill purge step). For example, the mill 30 is operated for a predetermined time (for example, 8 minutes) while the coal feeder 20 is stopped, and the pulverized coal remaining in the mill 30 is discharged from the mill 30. The time for performing the mill purge is not particularly limited as long as it is sufficient for removing the pulverized coal from the mill 30. Thereafter, the pulverized coal burner 110 is stopped (S3: burner stop step).

  Next, after the pulverized coal burner 110 is stopped, the mill 30 is stopped (S4: mill stop step). At that time, the damper 44 is controlled so that a small amount of cold air is sent to the mill 30 (for example, 3% of the fully opened state is opened).

  Thereafter, pyrite (foreign matter) in the mill 30 is discharged from the mill 30 (S5: pyrite discharging step). Specifically, the pyrite hopper inlet valve 61 is opened and the pyrite in the mill 30 is discharged to the pyrite hopper 60.

  Next, it is confirmed that the cause of the lack of coal in the coal feeder 20 has been eliminated and the cause of the lack of coal in the coal feeder 20 has been eliminated (S6: Missing coal elimination step). For example, first, the control authority of the coal feeder 20 is transferred from the central control room to the actual controller of the coal feeder 20. Then, after hitting the sub-bunker 10a with a hammer or the like (hammering), the bunker water injection valve 5 is opened and water is poured into the bunker 10 from a water tank (not shown). Then, the coal that has been clogged in the flow path leading to the coal feeder 20 with the water is washed away, and the cause of the lack of coal in the coal feeder 20 is eliminated. Next, it is confirmed that the cause of the lack of coal in the coal feeder 20 has been eliminated by the coal falling sound when the coal that has been the cause of the lack of coal falls on the belt 21 of the coal feeder 20. Thereafter, the coal feeder 20 is temporarily operated to visually confirm that coal is present on the belt 21, and the coal feeder 20 is stopped (S7: Temporary coal feeder operation step). And the control authority of the coal feeder 20 is returned from the control apparatus of the actual coal feeder 20 to the central control room.

  Thereafter, the pulverized coal burner 110 is ignited, and the bunker 10, the coal feeder 20, the mill 30 and the pulverized coal conveying means 40 are activated (S8: activation step).

  By using the restart method of the pulverized coal supply apparatus as described above, the pulverized coal supply apparatus can be started with sufficient mill purge when the coal feeder stops due to lack of coal. The feeding device can be restarted safely.

(Other embodiments)
In the cooling process of the first embodiment, the mill 30 is cooled using the pulverized coal conveying means 40, but the method of cooling the mill 30 is not limited to this.

  In the mill purge process of the first embodiment, the mill 30 is operated for a predetermined time while the coal feeder 20 is stopped, and the pulverized coal remaining in the mill 30 is discharged from the mill 30. The mill purge process is not limited to this. For example, as a mill purge process, compressed air may be blown onto the inner wall surface of the mill 30 to discharge the pulverized coal remaining in the mill 30 from the mill 30.

  Further, in the lack of carbon elimination process of the first embodiment, after hitting the sub-bunker 10a with a hammer or the like (hammering), the bunker water injection valve 5 is opened to inject water from a water tank (not shown), and the coal feeder 20 Although the clogging of coal, which is the cause of the lack of carbon, has been eliminated, the lack of carbon elimination process of the present invention is not limited to this.

  In addition, in Embodiment 1, although the pyrite discharge process was provided between the mill stop process and the carbon deficient elimination process, this need not be provided.

It is the schematic which shows the pulverized coal supply apparatus which concerns on Embodiment 1. FIG. It is a flowchart which shows the restart method of the pulverized coal supply apparatus which concerns on Embodiment 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pulverized coal supply apparatus 5 Bunker injection valve 10 Bunker 10a Sub bunker 10b Main bunker 11 Coal gate 20 Coal feeder 21 Belt 30 mil 40 Pulverized coal conveyance means 41, 43 Gate 42, 44, 51 Damper 50 Pulverized coal supply pipe 60 Pyrite hopper 61 Pyrite hopper inlet valve 100 Boiler furnace 110 Pulverized coal burner

Claims (3)

A coal feeder supplying coal,
A mill for pulverizing coal supplied from the coal feeder to produce pulverized coal;
In the pulverized coal supply device comprising the pulverized coal transport means for transporting the pulverized coal generated by the mill to the pulverized coal burner provided in the boiler furnace,
A cooling step of cooling the mill to a predetermined temperature or less after the coal feeder stops due to lack of carbon;
A mill purge step of mill purging the mill for a predetermined time after the cooling step;
A burner stop step of stopping the pulverized coal burner after the mill purge step;
A mill stop step for stopping the mill after the burner stop step;
After the mill stop step, cancel the cause of the lack of coal in the coal feeder and confirm the fact,
After temporarily operating the coal feeder after the lack of coal elimination step and confirming that the coal is present in the coal feeder, a temporary coal feeder operation step of stopping the coal feeder;
A pulverized coal supply apparatus comprising: an activation step of starting the coal feeder, the mill, and the pulverized coal conveying means after the temporary coal feeder operation step and igniting the pulverized coal burner. How to restart. The pulverized coal conveying means has a blower,
The restarting method of the pulverized coal supply apparatus according to claim 1, wherein the mill is cooled by air from the blower.   3. The pulverized coal supply apparatus according to claim 1, further comprising a pyrite discharging step of discharging pyrite in the mill between the mill stop step and the lack of carbon elimination step. starting method.

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