JPS61252424A - Fuel supplier for pulverized-coal-fired boiler - Google Patents

Abstract

PURPOSE:To lessen the dispersion of amounts of pulverized coal to be supplied to a boiler by keeping the level of pulverized coal in an quantitative supplier constant by rotationally controlling a rotary valve by level and weight signals of the quantitative supplier. CONSTITUTION:In a boiler control board 16, the load of a boiler are calculated by load steam pressure and flow rate signals of a pressure outgoing device 5 and a flow rate outgoing device 6. To supply the corresponding amount of pulverized coal to the boiler, a motor 11 for an quantitative supplier 10 is controlled with respect to revolving numbers. On the one hand, the amount of pulverized coal to be supplied in the supplier 10 is controlled by rotation of a rotary valve 8 according to the boiler load by means of the signals of a level sensor 17, and the revolving number of a drive motor 9 is controlled to keep the level constant all the time. A weight sensor 18 is provided to the quantitative supplier 10a, and by weight signals of pulverized coal, the revolving number of the motor 9 is controlled, and the supply amount is controlled by rotation of the valve 8 to keep the weight of pulverized coal in the supplier 10a constant all the time. Since the amount of pulverized coal in the supplier 10a can be kept constant all the time, no dispersion in the amount of pulverized coal to be supplied occurs in fuel tube, and therefore, pulverized coal can be smoothly supplied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel supply system for a boiler that improves combustion efficiency by improving a method for supplying pulverized coal.

[Conventional technology]

The conventional fuel supply system for a pulverized coal-fired boiler, as shown in FIG. For example, the pulverized coal is supplied to the fuel pipe 35 while controlling the feed amount of pulverized coal by the motor 34 whose rotation speed is controlled by the signals from the steam load pressure gauge 38 and flow meter 39, and the pulverized coal and the fuel pipe The mixture is mixed with the combustion air blown into the boiler 3o, and is sent to the boiler 3o for combustion. Further, the quantitative feeder 33 is equipped with a detection switch 36.3 for detecting high and low levels of pulverized coal storage.
7 is provided, and the detection switch 37 when the amount of pulverized coal is at a low level
When the amount of pulverized coal reaches the high level detection switch 36, the rotary valve 32 is activated and pulverized coal is supplied from the pulverized coal silo 31. supply is about to stop. In the figure, 40 is a steam drum, 41 is a forced air blower, 42 is a gas air heater, 43 is a secondary air pipe, 44 is a boiler control panel, and 45 is a rotary valve 32.
This is the drive motor.

[Problem that the invention seeks to solve]

By the way, in such a fuel supply system for a pulverized coal-fired boiler, the level of pulverized coal stored in the quantitative feeder 33 constantly fluctuates. Particularly when the rotary valve 32 is operated and a large amount of pulverized coal is supplied in a short period of time, the powder pressure of the pulverized coal fluctuates sharply, and this fluctuation causes the amount of pulverized coal to be supplied from the quantitative feeder 33 to the fuel pipe 35. If there is variation in the amount of pulverized coal and the supply of pulverized coal becomes excessive, unburned portions will occur and combustion efficiency will deteriorate, and nitrogen oxides will be generated as excess and shortage of pulverized coal supply are repeated frequently. There was a problem that combustion became unstable, such as the degree of fluctuation in the amount of combustion being large and the amount generated being large.

Therefore, in order to solve the above-mentioned problems, the present invention aims to provide a fuel supply device that maintains a constant level of pulverized coal in a quantitative feeder and reduces variations in the amount of pulverized coal supplied to a boiler. be.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a fuel supply system in which pulverized coal supplied from a pulverized coal silo to a metering feeder is sent to a boiler using combustion air for combustion. A rotary valve equipped with a drive motor is installed between the feeder and the feeder, and the rotation of the rotary valve is controlled by a detection signal from a pulverized coal amount detector provided in the quantitative feeder. be. As the detection signal of the pulverized coal amount detector installed in the metering feeder, the level signal of the pulverized coal level detector installed in the metering feeder or the weight signal of the weight detector installed in the metering feeder is used. .

[For production]

The fuel supply device of the present invention having such a configuration uses a level detector or a weight detector to detect the level or weight of pulverized coal supplied from the pulverized coal silo to the metering feeder in the metering feeder, and to detect changes in the boiler load. By correspondingly controlling the rotation of the rotary valve and adjusting the amount of pulverized coal supplied, the amount of pulverized coal in the metering feeder is always kept constant, and the coal is fed slowly to the metering feeder. Fluctuations in body pressure are reduced, and variations in the amount of pulverized coal supplied to the boiler are reduced.

〔Example〕

One embodiment of the fuel supply device of the present invention will be explained based on the block diagram of a boiler in Fig. 1. In Fig. 0, 1 is a pulverized coal-fired boiler, 2 is a combustion chamber, 3 is a heating tube, and 4 is a steam drum. A pressure transmitter 5 and a flow rate transmitter 6 are connected to the steam drum 4 in the middle of a pipe connected to a steam load. Reference numeral 7 denotes a pulverized coal silo, and a rotary valve 8 equipped with a drive motor 9 whose rotation speed can be controlled is attached to the outlet of the lower part of the silo, and is connected to a metering feeder 10 .

A metering feeder motor 11 for controlling the feed of pulverized coal by the rotational speed is attached to the lower part of the metering feeder 10, and is further connected to a fuel pipe 12. This fuel pipe 12 is blown into the gas air heater 1 by a forced blower 13 for the boiler.
The combustion air heated in step 4 is blown into the discharge part of the constant feeder motor 11 to mix pulverized coal and combustion air, and the mixture is fed to the boiler 1 for combustion. Note that 15 is a secondary air pipe. 16 is a boiler control panel which receives steam pressure signals and flow rate signals from the pressure transmitter 5 and flow rate transmitter 6 of the boiler 1 to control the rotation speed of the metering feeder motor 11; The number of rotations of the drive motor 9 is controlled by receiving a pulverized coal level signal from a pulverized coal level detector 17 installed at a predetermined height of the pulverized coal feeder 10a. A detector 18 is provided, and the boiler control panel 16 receives a weight signal of pulverized coal from the weight detector 18 to control the rotational speed of the drive motor 9. is the same as

[Effect of the embodiment]

Next, the operation of the above embodiment will be explained. The pulverized coal supplied from the pulverized coal silo 7 to the metering feeder 10 by the rotary valve 8 is supplied to the fuel pipe 12 while the feed amount is controlled by the metering feeder motor 11 to an amount commensurate with the boiler load. The air is blown into the boiler by the forced air blower 13, mixed with combustion air heated by the gas air heater 14, and sent to the boiler 1 for combustion.

The boiler control panel 16 receives the load steam pressure signal and flow rate signal transmitted from the pressure transmitter 5 and flow rate transmitter 6 of the boiler 1, calculates the boiler load from these two signals, and calculates the pulverized coal that matches the boiler load. The rotational speed of the fixed quantity feeder motor 11 is controlled so that the rotational speed is such that the rotational speed is such that the rotational speed is such that the rotation speed is such that the rotation speed is such that the rotation speed is such that the rotation speed is such that the rotation speed is such that the rotation speed is such that the rotation speed is such that the fixed quantity feeder motor 11 has a rotation speed that supplies the following amount.

The boiler control panel 16 also receives a level signal indicating the level of pulverized coal from the level detector 17 provided in the metering feeder 10, and detects a drop in the level of pulverized coal in the metering feeder 10 when the boiler load is high. Since the amount of pulverized coal is fast, the rotary valve 8 is rotated at high speed to supply a large amount of pulverized coal, and when the boiler load is low, the fall in the pulverized coal level is slow, so the rotary valve 8 is rotated at a low speed to supply a large amount of pulverized coal. The rotation of the drive motor 9 is controlled so that the level of pulverized coal in the quantitative feeder 10 is always maintained at a constant level regardless of the level of the boiler load.

In another embodiment shown in FIG.
6 receives the weight signal of the pulverized coal detected by the weight detector 18 provided in the metering feeder 10a, and when the boiler load is high, the weight of the pulverized coal in the metering feeder 10a decreases quickly. The valve 8 is rotated at high speed to supply a large amount of pulverized coal, and when the boiler load is low, the weight of pulverized coal decreases slowly, so the rotary valve 8 is rotated at a low speed to suppress the amount of pulverized coal supplied, and the boiler The rotation of the drive motor 9 is controlled so that the weight of the pulverized coal in the quantitative feeder 10a always remains constant regardless of the level of load.

In this way, the amount of pulverized coal in the metering feeder 10.10a is always kept constant regardless of the load on the boiler 1, that is, the amount of pulverized coal supplied from the metering feeder 10 to the fuel pipe 12. The pulverized coal is smoothly supplied to the boiler without variations in the amount of pulverized coal supplied.

〔Effect of the invention〕

As described in detail above, the fuel supply system for a pulverized coal-fired boiler of the present invention includes a pulverized coal quantitative feeder equipped with a detector for detecting the amount of pulverized coal, and based on a signal from this detector, the rotation speed of the rotary valve is controlled. The amount of pulverized coal supplied to the metering feeder is adjusted according to the boiler load, so that the amount of pulverized coal in the metering feeder is always kept constant regardless of the amount of boiler load. When pulverized coal is supplied into the fuel pipe from ,
The degree of fluctuation in nitrogen oxide generation is reduced, and the amount of generation can be easily controlled.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the fuel supply system for a pulverized coal-fired boiler according to the present invention, Fig. 2 shows another embodiment, and Fig. 3 shows a conventional fuel supply system for a pulverized coal-fired boiler. FIG.

Claims (3)

[Claims] (1) In a fuel supply system that uses combustion air to send pulverized coal supplied from a pulverized coal silo to a metering feeder to a boiler for combustion, a rotary valve is installed between the pulverized coal silo and the metering feeder. A fuel supply device for a pulverized coal-fired boiler, characterized in that the rotation of the rotary valve is controlled by a detection signal from a pulverized coal amount detector attached to the quantitative feeder. (2) Claim 1, characterized in that the detection signal of the pulverized coal amount detector provided in the quantitative feeder is the level signal of the pulverized coal level detector provided in the quantitative feeder. A fuel supply device for a pulverized coal-fired boiler as described in . (3) The fine powder according to claim 1, wherein the detection signal of the pulverized coal amount detector provided in the quantitative feeder is the weight signal of the weight detector provided in the quantitative feeder. Fuel supply system for coal-fired boilers.