JPH07293817A - Fuel supplying device for fluidized bed type furnace - Google Patents

Abstract

PURPOSE:To prevent a fluidized bed material from being back flowed into a fuel nozzle without bringing fuel into a furnace or a dust-removing device when a fluidized bed type boiler and the like are warmed up. CONSTITUTION:There is provided a bypassing pipe 13 having a valve 9 where it is branched from an inlet of a fuel feeding device 3 and merged at an upstream side of a fuel nozzle 7. During warming-up operation with air heated by a hot air generating furnace 12, primary air is flowed into the fuel nozzle 7 without passing through the mixing device 3 and almost of a fuel transporting pipe 5, but through a bypass pipe 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for a fluidized bed furnace such as a fluidized bed boiler.

[0002]

2. Description of the Related Art FIG. 2 is a system diagram showing an example of a conventional fuel supply device for a fluidized bed boiler. In a fluidized bed boiler that conveys fuel by air and supplies powdered fuel from the furnace bottom into the furnace, a feeder (2) that controls the flow rate from a fuel hopper (1).
The powder fuel supplied to the mixing device (3) by the air is conveyed by the primary air introduced into the mixing device (3) from the primary air pipe (4), and passes through the fuel transfer pipe (5) and the fuel nozzle (7). To the fluidized bed (8) in the furnace. In the figure, (6) is a fuel cutoff valve, (10) is a wind box, and (11) is a secondary air pipe.

[0003]

In a fluidized bed boiler, fuel is ignited while fluidizing a part or all of the fluidized bed (8) with heated secondary air so that the fuel can be ignited in preparation for fuel injection. Warm to the temperature possible. Since the fluidized bed (8) is flowing during the warming, the fluidized material flows back into the fuel nozzle (7) at the bottom of the furnace and closes it.

In order to prevent the backflow and blockage of the fluid material, it is sufficient to let primary air flow through the fuel nozzle (7). Then, the fuel remaining in the mixing device (3) and the transfer pipe (5) will be removed. Brought into the furnace. At this time, since the temperature of the fluidized bed is not sufficiently high, the carried-in fuel is not burnt and is collected by a dust removing device (not shown). The unburned material collected is heated by the load increase of the boiler and ignited, which damages the dust removing device,
It could have caused a fire.

[0005]

In order to solve the above-mentioned conventional problems, the present inventor has proposed a fuel hopper for storing powdered fuel and a fuel feeder for controlling the flow rate of powdered fuel supplied from the fuel hopper. A mixing device for mixing the powder fuel supplied from the fuel supply device with the primary air for fuel transportation supplied through the primary air pipe, and the fuel mixture mixed by the mixing device through the fuel transportation pipe. In a fluidized bed furnace equipped with a fuel nozzle to be fed into the furnace via, a bypass pipe branching from the primary air pipe upstream of the mixer and joining the fuel carrier pipe near the fuel nozzle, A fuel supply device for a fluidized bed reactor, which is provided with a system including a mixing device and a means for switching the bypass pipe line to each other.

[0006]

[Function] During warming of the fluidized bed boiler, by flowing the primary air to the fuel nozzle through the bypass pipe which does not include the mixing device, the backflow of the fluid material is prevented, and the residual air remains in the mixing device and the fuel transfer pipe. Existing fuel from entering the furnace during warming. After warming up,
Supply fuel by switching to a system that includes a mixing device. By the switching operation between warming and after warming as described above, fuel is prevented from being brought into the furnace during the warming with a low fluidized bed temperature and scattered to the dust removing device.
It is possible to prevent damage and fire to the dust remover.

[0007]

FIG. 1 is a system diagram showing an embodiment of the present invention. The powdered fuel supplied from the fuel hopper (1) to the mixing device (3) by the fuel supply device (2) for controlling the fuel flow rate is
It is carried by the primary air introduced into the mixer (3) from the primary air pipe (4), passes through the fuel carrier pipe (5) and the fuel cutoff valve (6), and flows from the fuel nozzle (7) to the fluidized bed (8).
Supplied at the bottom of the. On the other hand, from the wind box (10) at the bottom of the fluidized bed (8), the secondary air coming through the secondary air pipe (11) is supplied to the bottom of the fluidized bed (8).

In this embodiment, the bypass pipe line (13) branches from the primary air pipe (4) at the inlet of the mixing device (3), and the fuel flows near the fuel nozzle (7) downstream of the fuel cutoff valve (6). It joins the carrier pipe (5). A purge valve (9) is provided in this bypass line (13).

During warming of the fluidized bed, secondary air passes from the secondary air pipe (11) through the hot air stove (12) to the wind box (10).
Through and into the fluidized bed (8). At this time, the fuel cutoff valve (6) is closed and the purge valve (9) is opened. Then, the primary air during warming does not pass through the mixing device (3) but passes through the bypass pipe (13) and the purge valve (9),
It is injected into the fluidized bed (8) from the fuel nozzle (7). Therefore, the fuel remaining in the mixing device (3) and the fuel transfer pipe (5) is not brought into the furnace during warming.

After the warming is completed, the fuel cutoff valve (6)
Open and close the purge valve (9). After this switching, the fuel supply device (2) is activated to start fuel supply.

[0011]

According to the present invention, during the warming of the fluidized bed, the primary air or the inert gas is introduced from the fuel nozzle without passing through the mixing device and the fuel transfer pipe, so that the backflow of the fluid material is prevented and the fuel flow is reduced. It is possible to prevent bringing in the furnace. Since no combustibles are brought into the furnace and the dust removing device in this manner, damage to the dust removing device and fire can be prevented.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is a system diagram showing an example of a conventional fuel supply device for a fluidized bed boiler.

[Explanation of symbols]

 (1) Fuel hopper (2) Fuel feeder (3) Mixer (4) Primary air pipe (5) Fuel carrier pipe (6) Fuel shutoff valve (7) Fuel nozzle (8) Fluidized bed (9) Purge valve ( 10) Wind box (11) Secondary air pipe (12) Hot air generator (13) Bypass line

Claims (1)

[Claims] 1. A fuel hopper for storing powdered fuel, a fuel feeder for controlling the flow rate of powdered fuel supplied from the fuel hopper, and a primary air for fuel transfer supplied through a primary air pipe to the fuel. In a fluidized bed furnace equipped with a mixer for mixing powdered fuel supplied from a feeder and a fuel nozzle for supplying a fuel mixture mixed by the mixer into the furnace through a fuel carrier pipe, A bypass pipe branching from the primary air pipe upstream of the container and joining the fuel carrier pipe near the fuel nozzle, and means for switching between the system including the mixer and the bypass pipe. A fuel supply device for a fluidized bed reactor characterized by the above.