JP2005195274A - Pulverized coal firing boiler and burner operation method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulverized coal firing boiler, optimizing the pulverized coal concentration. <P>SOLUTION: In this pulverized coal firing boiler, a plurality of pulverized coal supply pipes 4 are connected to an outlet side of one coal pulverizer 1, and a burner 3 is installed at the forward end part on the boiler side of each pulverized coal supply pipe 4. The number of burners used is varied according to the outlet side pulverized coal concentration of the coal pulverizer 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pulverized coal burning boiler and a burner operating method thereof, and more particularly to a fuel concentration control technique at the outlet of a pulverized coal machine.

  In the prior art, when the pulverized coal machine is started, the flow rate of air (primary air) for conveying the pulverized coal is kept constant despite the small amount of coal supply, so the pulverized coal concentration inevitably decreases. . Moreover, since all the burners which receive supply of pulverized coal from the pulverized coal machine are used simultaneously on the boiler side, low concentration pulverized coal is supplied to all the burners. This brings about a decrease in the combustion performance of the burner, and a phenomenon is observed in which the concentration of nitrogen oxides increases at the start of the pulverized coal machine.

  FIG. 6 is a diagram showing the nitrogen oxide emission concentration characteristics when the pulverized coal machine is activated according to the prior art. In the figure, the vertical axis represents time, and the vertical axis represents the nitrogen oxide concentration. As shown in the figure, at the start of the pulverized coal machine, the concentration of pulverized coal supplied to the burner is low as described above, and therefore the nitrogen oxide concentration is considerably higher than that at the time of settling.

Regarding the burner operation method of the pulverized coal fired boiler, for example, the following patent documents can be cited.
JP-A-6-147470

  In the prior art described above, no consideration has been given to optimizing the concentration of pulverized coal at the start of the pulverized coal machine, and there has been a problem that there is no choice but to rely on other process improvements for improving exhaust gas properties.

  An object of the present invention is to provide a pulverized coal-fired boiler and a burner operation method thereof that can eliminate such drawbacks of the prior art and optimize the pulverized coal concentration.

  In order to achieve the above object, the first means of the present invention is that a plurality of pulverized coal supply pipes are connected to the outlet side of one pulverized coal machine, and a burner is installed at the boiler-side tip of each pulverized coal supply pipe In the pulverized coal fired boiler, the number of burners used is variable according to the outlet side pulverized coal concentration of the pulverized coal machine.

  A second means of the present invention is characterized in that, in the first means, a damper is provided in the middle of each pulverized coal supply pipe, and the number of burners used is controlled by the number of opened dampers. To do.

  The third means of the present invention is a burner of a pulverized coal fired boiler in which a plurality of pulverized coal supply pipes are connected to the outlet side of one pulverized coal machine, and a burner is installed at the tip of the boiler side of each pulverized coal supply pipe. The operation method is characterized in that the number of burners used is variable in accordance with the outlet side pulverized coal concentration of the pulverized coal machine.

 According to a fourth means of the present invention, in the third means, a damper is provided in the middle of each pulverized coal supply pipe, and the number of burners used is controlled by the number of opened dampers. To do.

  In the present invention, the number of burners to be operated is appropriately controlled according to the amount of coal supplied, and the performance of the burners is utilized to the maximum. That is, by controlling the number of pulverized coal machine outlet dampers to be opened based on the measured pulverized coal conveying air (primary air) flow rate and the amount of coal supply, the number of pulverized coal machine outlet dampers to be opened is controlled. The density can be controlled to an appropriate value. Therefore, the nitrogen oxide emission concentration can be kept low, and the deterioration of the combustion performance can be avoided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an outlet system diagram of a pulverized coal machine in a pulverized coal burning boiler according to an embodiment of the present invention. As shown in the figure, a plurality of pulverized coal supply pipes 4 are connected to the outlet of one pulverized coal machine 1, and a damper 2 is installed in the middle of each pulverized coal supply pipe 4 to supply each pulverized coal. A burner 3 is connected to the boiler-side tip of the pipe 4.

In the case of a power plant boiler, a plurality of pulverized coal supply pipes 4 for one pulverized coal machine 1.
A plurality of sets of dampers 2 and burners 3 are installed.

  Fig. 2 is a characteristic diagram showing the relationship between pulverized coal concentration (horizontal axis) and nitrogen oxide concentration (vertical axis). Fig. 3 is the relationship between coal supply (horizontal axis) and air for conveying pulverized coal (vertical axis). FIG. 4 is a characteristic diagram showing the relationship between the coal supply amount (horizontal axis) and the pulverized coal concentration (vertical axis), and FIG. 5 is a nitrogen oxide emission concentration characteristic diagram according to the present invention.

  Conventionally, all the dampers 2 are simultaneously opened by starting the pulverized coal machine 1. As shown in FIG. 3, when the amount of coal supply is small, such as when the pulverized coal machine is started, the flow rate of the conveying air (primary air) is constant, and thus the fine powder supplied from each burner 3. Charcoal concentration will decrease. That is, the pulverized coal concentration at the outlet of the pulverized coal machine 1 is as shown by the dotted line in FIG. 4, and this is related to the discharge of nitrogen oxidation, which is a factor for reducing the combustion characteristics of the burner 3.

  On the other hand, this invention restrict | limits the number of the burners 3 used according to the amount of coal supply. That is, as shown by the solid line in FIG. 4, with respect to one pulverized coal machine 1, for example, 1 of all the burners 3 in a state where the amount of coal supply at the outlet of the pulverized coal machine 1 is the smallest as in the initial stage of startup. When / 4 is used and the amount of coal supply increases slightly, for example, 2/4 (1/2) of all burners 3 is used, and when the amount of coal supply further increases, for example, 3 of all burners 3 When / 4 is used and the amount of coal supply reaches a predetermined amount, all the burners 3 are used.

 Thus, by gradually increasing the number of burners 3 used in accordance with the increase in the amount of coal supply, the pulverized coal concentration from the burner 3 being used can be maintained high (properly). Limiting the number of burners 3 to be used in accordance with the outlet coal supply amount in this way is specifically controlling the number of open dampers 2, and the pulverized coal concentration in each burner 3 is controlled. It can be kept at an appropriate value. Control of the number of dampers 2 in the open state is performed by a control unit (not shown) of the boiler.

  Therefore, as shown in FIG. 5, the concentration of the pulverized coal supplied to the burner 3 can always be higher than that of the prior art, and particularly the nitrogen oxide concentration at the start of the pulverized coal machine is greatly reduced. It becomes possible to avoid a decrease in combustion performance.

It is an exit system diagram of a pulverized coal machine in a pulverized coal burning boiler concerning an embodiment of the present invention. It is a characteristic view which shows the relationship between pulverized coal density | concentration and nitrogen oxide density | concentration. It is a characteristic view which shows the relationship between the amount of coal supply and the air for pulverized coal conveyance. It is a characteristic view which shows the relationship between coal supply amount and pulverized coal density | concentration. It is a nitrogen oxide discharge concentration characteristic figure at the time of starting of a pulverized coal machine by the present invention. It is a nitrogen oxide discharge density | concentration characteristic figure at the time of starting of the pulverized coal machine by a prior art.

Explanation of symbols

1 pulverized coal machine 2 damper 3 burner 4 pulverized coal supply piping

Claims (4)

In a pulverized coal fired boiler in which a plurality of pulverized coal supply pipes are connected to the outlet side of one pulverized coal machine and a burner is installed at the tip of the boiler side of each pulverized coal supply pipe, the outlet side pulverized coal of the pulverized coal machine A pulverized coal fired boiler characterized in that the number of burners used is variable depending on the concentration. The pulverized coal burning boiler according to claim 1, wherein a damper is provided in each of the pulverized coal supply pipes, and the number of burners used is controlled by the number of opened dampers. boiler. In a burner operation method for a pulverized coal fired boiler in which a plurality of pulverized coal supply pipes are connected to the outlet side of one pulverized coal machine, and a burner is installed at the tip of the boiler side of each pulverized coal supply pipe, A burner operation method for a pulverized coal fired boiler, characterized in that the number of burners used is variable according to the outlet side pulverized coal concentration. The burner operation method of the pulverized coal burning boiler according to claim 3, wherein a damper is provided in the middle of each of the pulverized coal supply pipes, and the number of burners used is controlled by the number of opened dampers. To burn the pulverized coal fired boiler.

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