JPH0539281Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This 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]

Generally, the so-called fluidized bed combustion method is known as a means for efficiently burning coal, oil coke, and other solid fuels and reducing the furnace area.

Conventionally, as a small once-through boiler using the fluidized bed combustion method, a patent application previously filed by the applicant in 1983
-55771 (see Japanese Patent Application Laid-Open No. 01-23090).

The structure of this conventional once-through boiler is as shown in FIG. A plurality of evaporation tubes 31 are provided.

At the lower part of the combustion chamber 32 of the boiler body 30, an air dispersion plate 33 having jet ports formed on its surface is provided. Below this air distribution plate 33 is a primary air chamber 3 into which primary air is supplied by a blower 34 in order to fluidize the solid fuel and heat medium with the primary air.
There are 5. 36 is a primary air supply pipe.

On the other hand, an auxiliary combustion burner 37 is provided downward in the upper part of the combustion chamber 32, and the flame of the auxiliary combustion burner 37 is blown into the fluidized bed from above, so that the contact with the solid fuel and heat medium is uniform, and self-combustion is achieved. The conversion is quick and self-combustion can be started in a short period of time.

Further, in the upper part of the combustion chamber 32, there is a hollow supply part 39a connected to a secondary air supply pipe 38 that supplies secondary air from the blower 34 and having a vent hole 39b formed in the lower part; vent 39b
An ejection box 39 is provided, the ejection box 39 having a hollow ejection portion 39c communicating with the combustion chamber 32 at its lower part and covering the outer periphery of the auxiliary combustion burner 37.

Incidentally, after the combustion gas rises into the combustion chamber 32 and passes up and down the passage formed by the baffle plate 40 and the guide plate 41, the cyclone dust collector 42 separates the unburned materials contained therein and the exhaust gas. are separated. Then, the unburned dust collected by the cyclone dust collector 42 is sent into the combustion chamber 32 of the fluidized bed again by the simple ejector 43.

[The problem that the idea aims to solve]

However, the above conventional technology has the following problems.

(1) With the structure of the injection box 39 of a conventional once-through boiler, secondary air cannot be injected all over the combustion chamber, resulting in poor combustion efficiency and incomplete combustion, which produces a large amount of NOx (nitrogen oxides). There was a problem with this occurring.

(2) After the combustion gas rises within the combustion chamber 32, it passes up and down the passage formed by the buff-full plate 40 and the guide portion 41 and is discharged to the outside, so that no gas remains in the device during the discharge. There were problems in that maintenance of unburned materials and ash was difficult, and that unburned materials and ash caused boiler malfunctions.

This invention was made in view of the above-mentioned problems, and an object thereof is to provide a small once-through boiler that can further improve combustion efficiency and prevent accumulation of unburned materials and ash.

[Means to solve the problem]

In order to solve the above problems, this invention includes an auxiliary combustion burner installed in the upper part of the combustion chamber in the boiler body so that flame blows out downward, and secondary air for combustion directed from the vicinity of the auxiliary burner toward the combustion chamber. In a small once-through boiler using a fluidized bed combustion method, the ejection box has a hollow supply part to which secondary air is supplied and has a vent at the bottom, and an upper part of the supply part. a hollow ejection part that communicates with the ventilation port and whose lower part communicates with the combustion chamber and covers the outer periphery of the auxiliary combustion burner; A rising passageway for discharging combustion gas upward is formed on the outer periphery of the ejection box.

[Effect]

According to this invention, the ejection box includes a hollow supply section into which secondary air is supplied and has a vent in the lower part, an upper part that communicates with the vent of the supply part, a lower part that communicates with the combustion chamber, and a lower part that communicates with the combustion chamber. It consists of a hollow ejection part that covers the outer periphery of the auxiliary combustion burner, and a flange part that is attached to the outer periphery of the ejection part and communicates with the vent of the supply part, and has an ejection port that communicates with the combustion chamber on the lower surface, Secondary air can be blown out over the entire surface of the combustion chamber.

Further, since a rising passage is formed on the outer periphery of the ejection box, the combustion gas passes through this rising passage and is discharged upward.

〔Example〕

Embodiments of this invention will be described below based on the drawings. Figure 1 of the drawings is a vertical cross-sectional view showing the structure of the small once-through boiler of the present invention, Figure 2 is a cross-sectional view showing how the evaporator tube and baffle plate are attached, and Figure 3 is a vertical cross-sectional view showing the structure of the ejection box. It is a diagram.

In Fig. 1, 1 is a combustion chamber equipped with a furnace at the bottom, 1a is a furnace wall made of refractory material formed around the furnace of the combustion chamber 1, and the upper part thereof is sloped toward the inside of the furnace. is formed.

Reference numeral 2 denotes a screw feeder for supplying solid fuel such as coal or oil coke to the combustion chamber 1 from a fuel tank (not shown) that stores solid fuel.

3 is a primary air chamber provided at the bottom of the combustion chamber 1.

Reference numeral 4 denotes an air distribution plate provided in the furnace of the combustion chamber 1 above the primary air chamber 3. This air distribution plate 4 is formed with many jet ports (not shown).

5 is a blower for supplying primary air to the combustion chamber 1.

6 is a primary air supply pipe provided to supply air from the blower 5 to the primary air chamber 3.

The primary air supplied from the blower 5 is sent into the interior and upper part of the combustion chamber 1 through the primary air chamber 3 and the air distribution plate 4, and the solid fuel such as coal and oil coke sent from the screw feeder 2, The fluidized bed medium (silica sand, etc.) stored in advance on the surface of the air distribution plate 4 is made to flow upward.

7 is an auxiliary combustion burner provided in the upper part of the combustion chamber. The blast tube of this auxiliary combustion burner 7 and the nozzle set within the tube are the same as those of a normal pressure spray burner.

8 is a fuel oil supply valve to this auxiliary combustion burner 7.

Reference numeral 9 denotes an ejection box for ejecting secondary air for combustion supplied from the blower 5 into the combustion chamber 1.

Reference numeral 10 denotes a secondary air supply pipe provided for supplying secondary air from the blower 5 to the blowout box 9.

As shown in FIG. 3, the ejection box 9 has a hollow supply part 9b connected to the secondary air supply pipe 10 and having a vent 9a formed at the lower part, and the supply part 9 at the upper part.
a hollow spouting part 9c that communicates with the vent 9a of b, the lower part of which communicates with the combustion chamber 1 and covers the outer periphery of the auxiliary combustion burner 7; and a vent of the supply part 9b that is attached to the outer periphery of the spouting part 9c. 9a, and a flange portion 9e having a jet nozzle 9d communicating with the inside of the combustion chamber 1 on the lower surface thereof.

A boiler body 11 is installed outside the combustion chamber 1, is configured concentrically with the combustion chamber 1, and is used to produce steam or hot water.

As shown in FIGS. 1 and 2, this boiler main body 11 has a plurality of evaporation pipes 11 arranged between a doughnut-shaped upper air-water drum 11a and a lower air-water drum 11b.
It is configured by connecting with c.

Reference numeral 12 denotes a baffle plate interposed between the plurality of inner evaporator tubes 11c, which controls the flow of flame to the evaporator tubes 11c and increases the heat transfer efficiency to the boiler body. This battle board 1
2 is attached to the tip of the flange 9c of the spout hook 9 in a vertically downward direction. And squirt box 9
The flange 9e, the buff-full plate 12, and the inner wall of the boiler body 11 form an upward passage 13 for discharging combustion gas. This rising passage 13 is configured so that the combustion gas uniformly contacts the evaporation pipe 11c.

A discharge pipe 14 connected to the ascending passage 13 is provided at the upper part of the combustion chamber 1, and a cyclone dust collector (not shown) is attached to the discharge pipe 14 to collect the combustion gas after the fluidized bed combustion is completed. Unburned materials are fed into the combustion chamber 1 again by a simple ejector or the like. This makes it possible to increase the effectiveness of energy resource utilization and prevent pollution caused by dust.

Further, 15 is a water suction pump, 16 is a steam extraction pipe created by the boiler, and 17 is a steam release valve.

According to this invention, the flame of the auxiliary combustion burner 7 provided at the top of the combustion chamber 1 heats the heat medium in the furnace of the combustion chamber 1, and at the same time, the heat medium is heated by the primary air supplied from the bottom of the combustion chamber 1. squirt, approx.
When the temperature reaches 550~600℃, solid fuel such as coal or oil coke is introduced, and the temperature rises to 700~800℃ due to self-combustion.
The auxiliary combustion of the burner 7 is continued until the temperature reaches a uniform temperature of °C.

On the other hand, the secondary air from the blower 5 is sent to the blowout box 9.
As mentioned above, the injection box 9 is composed of a supply part 9b, an injection part 9c, and a flange part 9c, which are in communication with each other, and the secondary air is ejected to the combustion chamber 1 side through the Since the fuel can be ejected over the entire surface, the mixture of fuel and air can be improved, combustion can be made more complete, and combustion efficiency can be increased.

Also, since secondary air is blown into the combustion chamber 1,
There is no need to worry about overheating due to combustion heat in the furnace, and the combustion temperature is low (900-1000℃), so NOx (nitrogen oxides)
can reduce the occurrence of

Further, since the combustion gas generated after combustion is discharged to the outside through the ascending passage 13, unburned materials and ash fall toward the bottom of the combustion chamber 1 and do not accumulate on the way. Therefore, maintenance of the boiler after operation will not be difficult, and functional failure of the boiler will not occur.

Furthermore, the combustion gas generated after combustion is transferred to the evaporator tube 11.
Since it touches c uniformly, thermal efficiency is good. After completing the heat transfer to the evaporation tube 11c, the heat is discharged to the outside through the rising passage 13 formed by the buff-full plate 12 attached to the tip of the flange 9e of the ejection box 9 and the inner wall of the boiler body 11. During this time, heat is exchanged with the secondary air for combustion, raising the air temperature, increasing combustion efficiency, while the combustion gas itself is discharged at a lower temperature, contributing to energy savings.

[Effect of idea]

Since this invention is constructed as described above, it has the following effects.

The blowout box can blow out secondary air over the entire surface of the combustion chamber, improving the mixing of fuel and air, making combustion more complete, increasing combustion efficiency, and reducing NOx generation. can do.

Since the combustion gas generated after the fuel is discharged to the outside through the ascending passage, unburned materials and ash fall toward the bottom of the combustion chamber and do not accumulate on the way. Therefore, maintenance after the boiler is in operation is difficult and the boiler does not malfunction.

[Brief explanation of the drawing]

The drawings relate to an embodiment of this invention, and FIG. 1 is a longitudinal sectional view showing the structure of the small once-through boiler of the invention, FIG. The figure is a longitudinal sectional view showing the structure of a jet box, and FIG. 4 is a longitudinal sectional view showing the structure of a conventional once-through boiler. 1... Combustion chamber, 2... Screw feeder, 3
...Primary air chamber, 4...Air distribution plate, 5...Blower, 6...Primary air supply pipe, 7...Assistant burner,
9...Gout box, 9a...Vent, 9b...
Supply part, 9c...Ejection part, 9d...Ejection port, 9e
... Flange part, 10 ... Secondary air supply pipe, 11 ... Evaporation pipe, 12 ... Buff full plate, 13 ... Rising passage.

Claims (1)

[Scope of Claim for Utility Model Registration] An auxiliary combustion burner provided in the upper part of the combustion chamber in the boiler body so that the flame blows out downward, and secondary air for combustion being blown toward the combustion chamber from the vicinity of the auxiliary burner. In a small once-through boiler using a fluidized bed combustion method, the ejection box has a hollow supply part to which secondary air is supplied and has a vent at the bottom, and an upper part of which is connected to the vent of the supply part. a hollow ejection part whose communicating lower part communicates with the combustion chamber and covers the outer periphery of the auxiliary combustion burner; and an ejection part which is attached to the outer periphery of the ejection part and communicates with the vent of the supply part and whose lower surface communicates with the combustion chamber. 1. A small once-through boiler comprising: a flange having an outlet; and a rising passageway for discharging combustion gas upward on the outer periphery of the ejection box.