JPS6238607B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coal feeding device for a fluidized bed boiler for stably supplying coal feedstock, which deteriorates coal conveyance due to the amount of water content, to the fluidized bed boiler.

In a fluidized bed boiler, it is necessary to stably supply coal pulverized to a particle size of 10 mm or less into or onto the fluidized bed. However, coal itself has moisture (approximately 7% surface moisture), so it has poor coal transportability, and when it gets wet with rainwater, the moisture content increases even more, making coal transportability difficult. becomes worse. For this reason, even if you simply cut out coal from a coal bin storing wet coal and quantitatively guide it to a coal feeding nozzle, the outlet of the coal bin,
There is a problem that coal may become clogged within the coal feeding nozzle or while being guided from the coal bin to the coal feeding nozzle. For this reason, conventionally, a drying device is provided to dry the pulverized coal before introducing it into a coal bin, thereby improving coal transportability. However, these conventional methods have the problem of consuming a very large amount of energy for drying the coal, and the equipment cost of the drying equipment is also large (2-3% of the boiler cost).
In addition, the number of locations where failures occur also increases.

The present invention was made in view of these circumstances, and uses a coal bin with a double hopper structure and a screw feeder with a double screw structure to facilitate and ensure the dropping and transport of coal, and to create an air flow inside the tubular structure. The object of the present invention is to provide a device that can stably supply coal in the form of wet coal without drying it by forming a pneumatic transport system for coal.

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

1 and 2 show an example of the present invention, in which coal (wet coal) 2 put into a coal bin 1 is
The coal is supplied into a fluidized bed boiler 7 via a screw feeder 3, a vertical coal feed pipe 4, a mixing device 5, and a tip nozzle 6.

In the above, the coal bin 1 has a double hopper structure consisting of an upper hopper 8 and a lower hopper 9, so that the coal 2 charged inside does not block the lower outlet.

In addition, a slide gate 1 is placed below the lower hopper 9.
The screw feeder 3 provided horizontally through the screw feeder 3 has a double screw structure consisting of screws 11 and 12, so that the lower hopper 9
This makes it possible to increase the cross-sectional area of the lower outlet of the lower hopper 9, thereby preventing clogging of coal in the lower hopper 9 and ensuring reliable coal conveyance. In the figure, 13 is a motor for driving the screws 11 and 12, and 14 is a motor for driving the screw feeder 3 in order to prevent damage to the screw feeder 3 in the event that the inside of the screw feeder 3 is blocked. A level switch 15 for detecting the coal level in the IDA 3 is an inspection hole, and 31 is an inspection window.

A rotary valve 16 is provided in the vertical coal feed pipe 4 provided below the conveyance side end of the screw feeder 3.
A purge air supply port 17 for blowing air to prevent coal from clogging is provided on the inner peripheral wall thereof, and a purge air supply device 18 is provided.
It is connected to the. In the figure, 19 and 20 indicate inspection holes. In the above, when coal is supplied into the fluidized bed, the pressure of blowing and supplying coal acts on the vertical coal feed pipe 4, so it is necessary to provide the rotary valve 16, but as shown in FIG. There is no need to install a rotary valve if the fluid is supplied to the top of the fluidized bed.

The mixing device 5 has a tubular structure fixed to the lower end of the vertical coal feed pipe 4 in a substantially T-shape so as to have a downward slope of a required angle α toward the boiler 7,
Coal conveying air supply ports 21, 22, and 23 for conveying coal from the vertical coal feed pipe 4 toward the lower end are provided at the upper end of the mixing device 5. Among the coal conveying air supply ports 21, 22, 23, 21 forms a conveying air flow at the bottom of the mixing device 5, 22 applies pressure to the entire cross-sectional area of the mixing device 5, and 23 is a vertical coal feeding pipe. Air is blown into the bottom position just where the coal from 4 falls into the mixing device 5. In the figure, 24 indicates an autopsy window.

The tip nozzle 6 is linearly and integrally fixed to the lower end of the mixing device 5, and is attached to the outer wall 2 of the boiler 7.
5 with an airtight device 26, and passes between the furnace wall tubes 27 so that its lower end reaches a required position above the fluidized bed 28. The lower end of the tip nozzle 6 is closed by an end plate 29, and a coal supply port 30 of a required size is formed on the lower surface of the lower end.

Next, the operation of the above embodiment will be explained.

Into the coal bin 1, undried coal 2 which has been pulverized into particles of, for example, 10 mm or less is placed.

The coal put into coal bin 1 is
Since it has a double hopper structure with an upper hopper 8 and a lower hopper 9, when the slide gate 10 is opened, it is smoothly dropped and fed to the screw feeder 3 without clogging. Moreover, since the screw feeder 3 has a double screw structure, the width of the lower outlet of the lower hopper 9 can be increased, and the effect of preventing blockage in the lower hopper 9 can therefore be further enhanced. can.

The coal supplied to the screw feeder 3 is 2
The coal is effectively conveyed by two screws 11, 12 and fed to the vertical coal feed pipe 4 at its conveying end. The coal supplied into the vertical coal feed pipe 4 is
It is supplied dropwise to the mixing device 5 via the rotary valve 16, but at this time, the purge air supply port 1
By injecting purge air downward from the inner circumferential surface from 7, it is possible to prevent clogging in the vertical coal feed pipe 4 from occurring.

The coal dropped into the mixing device 5 is fed through a coal conveying air supply port 23 that injects air toward the bottom position of the falling part, a supply port 22 that injects air along the bottom, and air pressure throughout the interior. The air is mixed by the air flow from the supply port 21 that gives an air flow, and is carried by the flow and sent to the tip nozzle 6 without causing clogging, and is pushed downward by the end plate 29 of the tip nozzle 6. Coal is supplied onto the fluidized bed 28 of the boiler 7 from the formed coal supply port 30. At this time, as described above, since the coal supply port 30 is formed on the lower surface of the tip nozzle 6, the coal can be widely diffused and supplied onto the fluidized bed 28, and the coal can be injected downward. It is possible to reduce the amount of fine coal powder that is discharged as is. Further, when coal is directly supplied into the fluidized bed 28, the shape of the tip nozzle may be such that the tip is simply cut at a right angle.

It should be noted that the present invention is not limited to the above embodiments, but may also be applied to the stable supply of a wide range of fuels other than coal, such as petroleum coke, coffee grounds, and other solid particles, and may depart from the gist of the present invention. Of course, various changes may be made within the scope.

According to the above-described coal feeding device for a fluidized bed boiler of the present invention, it is possible to stably and reliably feed the wet coal charged into the coal bin to the fluidized bed boiler, thereby eliminating the need for a coal drying device. The excellent effect of reducing the energy consumption required for drying and providing an extremely economical coal feeding device can be achieved.

[Brief explanation of the drawing]

Figure 1 is a side view showing one embodiment of the present invention, Figure 2 is a side view showing one embodiment of the present invention;
The figure is a directional view of FIG. 1. 1 is a coal bin, 3 is a screw feeder, 4 is a vertical coal feeding pipe (short pipe), 5 is a mixing device, 7 is a fluidized bed boiler, 8 is an upper hopper, 9 is a lower hopper, 1
1 and 12 are screws, 17 is a purge air supply port, 21, 22, and 23 are coal conveyance air supply ports, 2
8 is a fluidized bed, 29 is an end plate, and 30 is a coal supply port.

Claims (1)

[Claims] 1. A screw feeder having a double screw structure is provided below the lower outlet of a coal bin having a double hopper structure, and a coal conveying air supply port is provided at one end of the screw feeder under the conveying side end. 1. A coal feeding device for a fluidized bed boiler, comprising: a mixing device having a tip nozzle connected to the other end thereof via a short vertical pipe.