JPH0480281B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a small once-through boiler that burns coal, oil coke, and other solid fuels using a fluidized bed combustion method to produce steam and hot water.

[Conventional technology]

It is well known that multi-tube and single-tube small once-through boilers are often used as steam and hot water generators.

[Problem to be solved by the invention]

By the way, in boilers using the conventional fluidized bed combustion method, an auxiliary combustion oil combustion device, that is, an auxiliary combustion burner, is used to ignite the flowing solid fuel and ensure stable combustion of the ignited fluidized bed. It is installed in such a way that flame is blown from the lower peripheral wall into the fluidized bed area in the furnace from the side.

Therefore, there was a time lag between floating and fluidizing the solid fuel and igniting the floating and fluidized fuel particles with the auxiliary combustion burner. In other words, the flame from the auxiliary combustion burner is blown across the flow of floating fuel particles, so the contact between the flame and the fuel particles is not good, and the flame is quickly There was a time difference between ignition and ensuring stable fluidized bed combustion. In other words, there were problems with the speed and stability of startup.

This tendency was particularly noticeable when the fluidized bed was disturbed due to poor supply of solid fuel.
In addition, if fluidized bed combustion is disrupted due to a malfunction in the supply of fixed fuel to the fluidized bed combustion chamber, the operation must be stopped, and in such a case, the desired steam or hot water must be secured. It also had the disadvantage that it was not possible.

The present invention eliminates the shortcomings of the conventional small once-through boiler using the fluidized bed combustion method, further enhances the characteristics of the fluidized bed combustion method, and provides a small once-through boiler with high efficiency, functionality, and economical efficiency. The purpose is to

[Means to solve the problem]

As a means for achieving the above object, the present invention consists in setting an auxiliary combustion burner at an upper position of a boiler can in a small once-through boiler using a fluidized bed combustion method so that flame is blown downward.

That is, the setting is such that an auxiliary flame is blown into the solid fuel fluidized bed from above in a countercurrent manner.

Further, the present invention is characterized in that the primary air for the auxiliary combustion burner and fluidized bed combustion is preheated and supplied using heat radiation from the boiler main body.

[Effect]

In the small once-through boiler using the fluidized bed combustion method according to the present invention, the auxiliary combustion burner is set at the upper part of the boiler body as described above, and the flame of the auxiliary combustion burner is directed from above against the fluidized bed in a counterflow manner. Compared to conventional structures in which the auxiliary flame is blown into the fluidized bed from the side, the ignitability is extremely good, especially when the flame tip from the auxiliary burner and the fluidized bed are blown into the fluidized bed. Since contact with the solid fuel particles and the fluid heat medium (silica sand) contained therein is uniform, the conversion to the natural state is quick and ignition can be achieved in a short time.

In addition, since the auxiliary combustion burner is placed in the upper part of the boiler can and is directed downward, steam or hot water can be generated using only this auxiliary combustion burner.

〔Example〕

Next, the present invention will be explained in more detail based on Examples.

The drawing is a longitudinal cross-sectional view showing the structure of a small once-through boiler using the fluidized bed combustion method according to the present invention, in which 1 is a screw feeder for supplying solid fuel to a fluidized bed combustion chamber 2, and 3 is a screw feeder for supplying solid fuel to a fluidized bed combustion chamber 2. This is the primary air chamber provided at the bottom of 2.

By blowing the primary air upward from this primary air chamber 3, solid fuel such as coal and oil coke sent from the screw feeder 1 and the solid fuel stored in advance at the bottom of the fluidized bed combustion chamber 2 are combined. The fluidized heat medium (silica sand) is made to float upward and become fluidized. 4 is a primary air supply pipe to the primary air chamber 3;

Reference numeral 5 denotes an auxiliary combustion burner set in the upper part of the fluidized bed combustion chamber 2, that is, in the upper part of the boiler can body 9, which will be described later, and constitutes the main part of the present invention. 6
is a fuel oil supply valve to this auxiliary combustion burner 5, 7
is also the primary air chamber of this auxiliary combustion burner 5, and 8
is a primary air supply pipe to this primary air chamber 7.

As mentioned above, 9 is a boiler case installed above the fluidized bed combustion chamber 2, which is configured concentrically with the fluidized bed combustion chamber 2 and functions as the so-called heart of the boiler for producing steam or hot water. be.

The boiler body 9 in this embodiment is configured as a once-through boiler in which a donut-shaped upper air/water drum 9a and a lower water drum 9b are connected through a plurality of evaporation pipes 9c, as shown in the drawings. There is.
In addition, 9d is a buff-full plate interposed between the plurality of evaporation tubes 9c, 9c.
This is to control the flow of flame to the boiler body 9 and increase the heat transfer efficiency to the boiler body 9.

Reference numeral 10 denotes a furnace wall made of a refractory material surrounding the lower peripheral wall of the fluidized bed combustion chamber 2. Reference numeral 11 denotes a water pipe buried within the furnace wall 10, which constitutes an economizer for heat recovery. The hot water preheated by the economizer is sent to the lower water drum 9b of the boiler can 9.

Reference numeral 12 denotes an exterior plate that covers the entire outer periphery of the furnace wall 10 and the boiler can 9. In this embodiment, the fluidized bed combustion chamber 2 is provided between the exterior plate 12 and the boiler can 9 and the furnace wall 10. A flow path 13 for primary air to be supplied to the auxiliary combustion burner 5 is provided, and the primary air can be preheated and supplied using heat radiation from the furnace wall 10 and the boiler can body 9.

In addition, 14 is the primary air intake port,
Reference numeral 15 designates a blower for feeding the preheated air into the primary air chamber 3 provided at the bottom of the fluidized bed combustion chamber 2 and the primary air chamber 7 provided above the auxiliary combustion burner 5, respectively.

Furthermore, 16 is a cyclone dust collector for purifying the exhaust gas that has completed fluidized bed combustion. In the embodiment, the cyclone dust collector 16 separates the unburned solid fuel contained in the exhaust gas, that is, dust, from the exhaust gas, and also sends the collected dust to the fluidized bed combustion chamber 2 again to collect the exhaust gas. It has been set with consideration given to suppressing pollution through purification and increasing fuel combustion efficiency.

17 is a simple ejector for efficiently sending the unburned dust collected by the cyclone dust collector 16 into the fluidized bed combustion chamber 2.

The small once-through boiler using the fluidized bed combustion method according to the present invention is configured as explained in the embodiments above, so it exhibits the following effects and is extremely efficient and functional compared to the conventional small once-through boiler. This boiler has the characteristics of a small boiler that is efficient, economical, and easy to start.

〔Effect of the invention〕

(1) The auxiliary combustion burner is set at the top of the fluidized bed combustion chamber so that the flame is blown into the fluidized bed from above in a countercurrent direction, so that the fuel particles contained in the fluidized bed and the heat of fluidization are The contact with the medium is uniform, the conversion to self-combustion is quick, and self-combustion can be started in a short time. That is, rapid start-up is ensured, quick response to hot water or steam loads, and good start-up.

(2) The auxiliary combustion burner is set in the upper part of the fluidized bed combustion chamber, that is, in a position corresponding to the upper part of the boiler can,
Because the flame is blown downward from the top, the heat transfer from the auxiliary burner to the boiler case is good, and as a result, it is possible to create steam or hot water using only the auxiliary burner. It is.

Therefore, in the event that fluidized bed combustion is disrupted due to poor supply of solid fuel to the fluidized bed combustion chamber, the function as a small once-through boiler can be maintained even if only the auxiliary burner is operated without having to stop the boiler. I can do it. Therefore, it can be safely used as a small boiler in facilities such as hospitals where the supply of steam or hot water cannot be interrupted.

(3) The primary air for the auxiliary combustion burner and the fluidized bed combustion is preheated and supplied by recovering heat radiated from the fluidized bed combustion chamber and the boiler can, respectively, so combustion efficiency is significantly improved.

In addition, since an economizer is embedded in the furnace wall surrounding the bottom of the fluidized bed combustion chamber to preheat the water, this combined with the preheating of the primary air using the heat radiation mentioned above improves the overall thermal efficiency. , functions as a highly economical small boiler.

(4) Preheating of the secondary air is performed through the space between the furnace wall surrounding the fluidized bed combustion chamber and the exterior plate surrounding the boiler can, reducing the noise associated with the supply of primary air and ensuring quiet operation. be done.

As described above, the small once-through boiler using the fluidized bed combustion method according to the present invention dramatically improves the inherent high combustibility and efficiency of the fluidized bed combustion method, and is effective as a small boiler. can greatly contribute to increasing the

[Brief explanation of drawings]

The drawing is a longitudinal sectional view showing the structure of a small once-through boiler using a fluidized bed combustion method, which is an embodiment of the present invention. 1...Screw feeder, 2...Fluidized bed combustion chamber, 3...Primary air chamber, 4...Primary air supply pipe,
5... Burner for auxiliary combustion, 6... Fuel oil supply valve,
7...Primary air chamber, 8...Primary air supply pipe, 9...
...Boiler can body, 9a... Upper air/water drum, 9b...
...lower water drum, 9c...evaporation tube, 9d...buffer plate, 10...furnace wall, 11...economizer water pipe, 12...exterior plate, 13...primary air flow path, 14...primary Air intake, 15...
...Blower, 16...Cyclone dust collector, 17...
Simple ejector.

Claims (1)

[Claims] 1. An auxiliary combustion burner is installed in the upper part of the boiler body of a small once-through boiler using the fluidized bed combustion method so that the flame blows out vertically downward, so that the flame and floating fuel particles come into countercurrent contact. A small once-through boiler using a fluidized bed combustion method characterized by the following configuration.