JPH0336579B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling a pulverizer, and more particularly, to a method for controlling a pulverizer in which the amount of pulverized coal supplied from a coal pulverizer can be immediately adjusted to changes in the load of a combustion device.

For example, in a large boiler for a coal-fired power plant, all the coal used is pulverized coal, and the pulverized coal is pulverized in a pulverizer and transported by airflow to a burner for combustion. In this case, if pulverized coal is manufactured and stored in advance and the amount of pulverized coal supplied to the burner is adjusted according to the boiler load, the boiler load can be quickly responded to. This is extremely dangerous as it may cause explosive combustion of the charcoal. For this reason, a direct combustion method is adopted in which the pulverized coal is not stored, and the pulverized coal produced by the pulverized coal is supplied directly to the burner. In this case, the load response of the crushing device itself will influence the load response of the boiler.

FIG. 1 shows a conventional example of a method for manufacturing a crushing device.

The pulverized coal produced by pulverization in the pulverizer (mill) 7 is airflow-transported to the burner 20 via each coal feed pipe 9 by air supplied from the primary air fan 2, and is combusted. When the boiler load decreases, the amount of pulverized coal produced is reduced, the airflow velocity in the coal feeding pipe 9 is reduced, and the amount of coal fed per unit time is reduced. However, if the air velocity is reduced too much, the burner flame will enter the coal feed pipe 9 and create a backfire, which is very dangerous. Furthermore, if the concentration of pulverized coal in the airflow is lowered below a predetermined value, there is a risk that the flame in the burner will blow out. In other words, for the above reasons, a minimum load is determined for the crushing device, and the load cannot be lowered beyond this.
For this reason, if one pulverizer cannot cope with the boiler load, the operation of the pulverizer is stopped and the load on the other pulverizers is varied to cope with the boiler load. That is, when the crusher is stopped, the operation is stopped after the residual pulverized coal in the coal feeding pipe is purged to the boiler side using primary air. However, once the crusher is stopped, it takes time to restart it, creating the problem that it is not possible to respond immediately to an increase in boiler load. Furthermore, in recent years, in order to improve economic efficiency, there has been a trend to increase the capacity of crushing devices and to decrease the number of crushing devices installed, so the responsiveness to boiler load has tended to decrease.

The purpose of the present invention was constructed in view of the above-mentioned problems, and it is an object of the present invention to provide a method that allows the operating state of a crusher to immediately respond to load fluctuations of a boiler without stopping the operation of the crusher. .

In short, the present invention is a method for controlling a pulverizer that enables immediate response to boiler load by individually controlling each of a plurality of coal feed pipes attached to the pulverizer.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, a bypass pipe 11 is connected to at least a part of the plurality of coal feed pipes 9 that connect the crushing device 7 and the burner 20 provided in the boiler 10. Specifically, one end of the bypass pipe 11 is connected to the coal feeding pipe 9 on the downstream side of the installation part of the outlet damper 8, and the other end is connected to the air supply pipe (in the illustrated case, the cold air passage 21b).
is connected to.

First, the case where the boiler load is above a certain value or the case where the boiler is operating at full load will be explained. The amount of air supplied by the primary air fan 2 is adjusted by the damper 1 on the inlet side, and the air travels through the air passage 21a. By adjusting the dampers 5 and 6, part of this air passes through the cold air passage 21b, and the other part passes through the air preheater 3, where it is heated and then flows into the crushing device 7. The pulverized coal here flows into a coal feed pipe 9 via a damper 8 and is combusted in a burner 20. In this case, the damper 12 is kept closed.

When the boiler load decreases, the first response is to reduce the amount of pulverized coal produced and reduce the airflow velocity within the coal feed pipe 9. As mentioned above, this response has its limits.
If this measure is insufficient, the number of coal pipes used will be controlled. That is, in response to a decrease in boiler load, the damper 8 of each coal feed pipe 9 is closed, and the damper 12 of the bypass pipe 11 connected to the coal feed pipe 9 with the damper 8 closed is opened to close the damper 8. Purge the pulverized coal remaining inside to the boiler side. By controlling the number of coal feeding pipes, the flow velocity of the airflow inside the coal feeding pipes during use is maintained at a high level, and the pulverized coal concentration is also high, so problems such as backfire and flame blowout do not occur. In other words, by controlling the number of coal conveyance pipes, the minimum load on the crusher can be significantly reduced and the boiler load can be sufficiently handled, and since there is no need to stop the operation of the crusher, it is possible to prevent a rapid increase in the boiler load. can also be responded to immediately. The pulverized coal concentration is measured by a measuring device (not shown) that uses means such as Gaman line attenuation and luminous intensity attenuation.

By carrying out the present invention, the operating state of the crusher can be immediately adjusted to load fluctuations of a combustion device such as a boiler, and high load responsiveness can be achieved even in direct combustion.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a conventional method for controlling a grinding device, and FIG. 2 is a system diagram showing a method for controlling a grinding device according to the present invention. 7... Coal crushing device, 9... Coal conveyance pipe, 10...
Boiler, 11... bypass pipe, 20... burner.

Claims (1)

[Scope of Claims] 1. Control of the coal pulverizer in response to load fluctuations of the combustion device in a method in which a coal pulverizer and a burner are connected by a plurality of coal feeding pipes and pulverized coal produced by the pulverizer is transported to the burner. A method for manufacturing a coal crushing device, characterized in that, in addition to controlling the pulverized coal concentration of the airflow in each coal feeding pipe and controlling the flow rate of this airflow, the number of coal feeding pipes to be used is controlled. 2. A patent claim characterized in that a bypass pipe is connected to at least some of the plurality of coal feeding pipes, and purge gas is supplied to unused coal feeding pipes via this bypass pipe. A method for manufacturing a coal pulverizer according to item 1.