JPS6370007A - Gas burner in fluidized bed - Google Patents

Abstract

PURPOSE:To provide a gas burner, installed in a bed, which performs uniform combustion on the wide plane of a fluidized bed, is durable to the continuous use for a long time, improves economical efficiency, and facilitates maintenance and inspection, by a method wherein the gas burner is provided with a gas fuel feed pipe, installed in a fluidized bed, a burner branch pipe, branched from the gas fuel feed pipe and extended in a flat surface manner in parallel to an air dispersion plate, and gas injection nozzles, situated in a dispersed manner on the upper surface of the branch pipe. CONSTITUTION:Air for combustion fed in an air box 5 is fed through an air injection nozzle 7 to a fluidized bed 2. Gas fuel is fed to the fluidized bed 2 through a gas fuel feed pipe 9, a burner branch pipe 11, and a gas injection nozzle 12, and is externally mixed with the air for combustion for combustion. In case multi-fuel combustion is effected by using gas and coal, coal is fed in the fluidized bed 2 through a coal feed pipe 8. Gas burnt in the fluidized bed 2 and an air tower 3 passes a heat transfer part situated at the rear part of a boiler, and is exhausted as exhaust gas to the outside of the boiler. By arranging the gas injection nozzle 12 as shown in Fig., the gas can be uniformly burnt on the wide surface of the fluidized bed. In a large boiler, a plurality of burners 10 are arranged in juxtaposition, and combustion on a wide area is practicable.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a combustion device using a fluidized bed, particularly a fluid bed capable of co-combusting coal and gas. Regarding the l1 in-layer gas burner.

[Conventional technology]

A fluidized bed combustion apparatus has a structure in which solid fuel is combusted while flowing together with a fluidized medium, and does not use gaseous fuel or liquid fuel as the main fuel. Also, at present, the startup ignition of the combustion equipment.

Generally, an oil-burning hot air furnace or an oil-fueled bed burner is used. In-bed burners that perform combustion in a fluidized bed include those described in the following publications: Utility Model Application No. 56-75513, Utility Model Application No. 58-148410, Utility Model Application No. 58-148411, and Utility Model Application No. 58-148412. However, all of them are small and were devised as starting burners. FIG. 8 shows an in-bed ignition burner device described in Japanese Utility Model Application No. 56-75513.

[Problem that the invention seeks to solve]

Fluidized bed boilers were originally planned as boilers that used solid fuel, but in recent years, blast furnace gas generated in steel plants, etc.
There is a demand for co-firing converter gas, coke oven gas, and flammable gas generated in chemical plan 1- with coal in a fluidized bed boiler. On the other hand, the burners described in each of the above-mentioned publications are startup burners as mentioned above, and although they can heat a local area within the fluidized bed, they burn the entire fluidized bed over a wide plane. However, no consideration was given to the long-term co-firing of gas with coal, and it was limited to an in-bed burner that could be started without a hot blast furnace.

Further, as shown in FIG. 9, a burner branch pipe 11 is provided in the wind box 5 of the fluidized bed boiler, and gas nozzles dispersed from the burner branch pipe 11 are installed inside the air jet nozzle 7 provided in the air distribution plate 6. A burner for gas combustion, in which a branch pipe 16 is arranged to pass through the top of the air jet nozzle, and a cap-shaped gas jet nozzle 12 having a gas jet pore is provided at the top of the air jet nozzle. is also being devised. However, this structure does not take into consideration the difference in elongation in the plane (horizontal) direction and thermal stress due to the relative temperature difference (200 to 350°C) between the air distribution plate 6 and the burner branch pipe 11, and the gas nozzle branch pipe There is a problem that 16 is damaged. In order to avoid this, there is a method of using bellows at the gas nozzle pipe attachment part, but since gas jet nozzles are installed in a base pattern with a pitch of 100 to 200 m, for example, in the case of a 10 m square furnace, As many as 10,000 to 2,500 bellows were required, which caused problems in terms of economy and ease of inspection and maintenance of the connection.

An object of the present invention is to provide a gas burner installed in a bed that burns evenly over a wide flat surface of a fluidized bed, can withstand continuous use for a long time, is economical, and is easy to inspect and maintain.

[Means for solving problems]

The above object is to install a gas fuel supply pipe through the furnace side wall or the air distribution plate into the fluidized bed, branch from the gas fuel supply pipe within the fluidized bed, and form a planar structure parallel to the air distribution plate. This is achieved by providing a gas burner in a fluidized bed consisting of a burner branch pipe extending over the area and gas ejection nozzles arranged evenly distributed on the upper surface of the burner branch pipe.

[Effect]

The fuel gas ejected from gas ejection nozzles distributed over a wide plane within the fluidized bed mixes quickly and evenly with combustion air, and is evenly combusted over a wide plane within the fluidized bed.

The burner is fixed to the air distribution plate or the furnace side wall only in the part where the gas fuel supply pipe penetrates the air distribution plate or the furnace side wall. The elongation is independent of the thermal elongation of the air distribution plate.

In addition, when trying to ignite a gas burner in the fluidized bed when the fluidized medium is cold, if the height of the fluidized bed is lowered until the top surface of the fluidized bed approaches the gas jet nozzle, the empty column above the fluidized bed will ignite the burner. It becomes a burning space of time. When the burner is ignited and combusted, the temperature of the surrounding fluid medium gradually rises, allowing combustion within the fluid medium.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows a side sectional view of a boiler equipped with a gas burner in a fluidized bed according to the present invention. a layer 2, an air distribution plate 6 forming the bottom of the fluidized bed, a wind box 5 provided below the air distribution plate in contact with the air distribution plate, and provided on the fluidized bed side of the air distribution plate, A large number of air jet nozzles 7 that communicate the fluidized bed side and the wind box side of the air distribution plate, and are provided to penetrate the wind box 5 and the air distribution plate 6,
A coal supply pipe 8 having an opening on the upper surface of the air distribution plate 6, a gas fuel supply pipe 9 provided through the wind box 5 and the air distribution plate 6 and reaching into the fluidized bed 2, A burner branch pipe 11 branches from the gas fuel supply pipe 9 within the layer and forms a lattice-like frame that spreads in parallel with the air distribution plate 6, and a burner branch pipe 11 extends upward from the upper surface of the burner branch pipe 11. The gas ejection nozzle 12 is provided along the axial direction and has a gas ejection hole provided on substantially the same horizontal plane as the air ejection hole of the air ejection nozzle 7 .

The combustion air supplied to the wind box 5 is supplied to the flow WJ2 through the air jet nozzle 7, and the gas fuel is supplied to the gas fuel supply pipe 9, burner branch pipe 11. The gas is supplied to the fluidized bed 2 through the gas jet nozzle 12, mixed externally with combustion air, and combusted.

When co-firing gas and coal, coal is supplied into the fluidized bed 2 through a coal supply pipe 8 or the like. Fluidized bed 2 and empty column 3
The combusted gas passes through the heat transfer section at the rear of the boiler and is discharged outside the boiler as exhaust gas.

FIG. 2 is a perspective view of an embodiment of the fluidized bed gas burner according to the present invention, showing the relationship among the gas supply pipe 9, the burner branch pipe 11, and the gas jet nozzle 12.

By arranging the gas jet nozzles in this way, it is possible to burn uniformly over a wide area of the fluidized bed.In a large boiler, if a plurality of burners 10 are installed in parallel, combustion can be performed over a wide area. combustion is possible.

The screw-type holding fitting 14 of the burner branch pipe 11 has a structure that does not restrict the movement of the pipe in the pipe axial direction, and the air distribution plate 6
This prevents the occurrence of thermal stress due to the temperature difference between the burner branch pipe 11 and the burner branch pipe 11. Furthermore, the gas supply pipe 9 is fixed to the air distribution plate 6 with screw-type fittings at the point where it passes through the air distribution plate 6, making inspection and maintenance extremely easy.

Furthermore, since the gas fuel is ejected at the lowest part of the fluidized bed 2, that is, close to the air distribution plate 6, it is easy to secure sufficient combustion time within the fluidized bed, and sufficient combustion within the bed is possible.

Since the burner components are located below the air/gas ejection level, no wear of the burner components by the flowing medium occurs. The ejection holes of the air ejection nozzle 7 and the gas ejection nozzle 12 are configured to emit air diagonally downward and radially from each nozzle, as shown in FIG. 4, to improve the mixing of air and gas fuel in the fluidized bed. At the same time, the fluidized medium is prevented from leaking into the nozzle when the furnace is stopped.

In addition, a single burner has a small amount of penetration through the furnace side wall and air distribution plate, and has a low equipment cost.

Another embodiment of the in-bed gas burner according to the invention is shown in FIGS. 5 and 6. The planar frame shape of the burner branch pipes is either radial or centipede-shaped.In both cases, a gas fuel supply pipe is installed approximately in the center, and a gas fuel supply pipe is installed on the top surface of each branch pipe along the pipe axis. This structure is equipped with a gas jet nozzle.

It is difficult to stably ignite a burner using gaseous fuel in the starting state of the furnace when the burner is filled with a cold fluidized medium. In this embodiment, as shown in Fig. 7, at startup, the height of the fluidized bed is temporarily lowered to the position of the gas jet nozzle before ignition, and the amount of fluidized medium is increased as the temperature of the fluidized medium increases. By adopting a startup method that gradually raises the layer height to the required level, stable ignition temperature rise was made possible.

〔Effect of the invention〕

According to the present invention, co-firing of blast furnace gas, coke gas, converter gas, and coal is possible in a fluidized bed boiler,
Furthermore, startup using gas such as LPG is possible.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a perspective view of an embodiment of the gas burner according to the invention, Fig. 3 is an enlarged view of the part shown in Fig. 1, and Fig. 4 shows an air jet nozzle and a main body. Figures 5 and 6 are diagrams showing the mutual positions of the gas ejection nozzles according to the invention, Figures 5 and 6 are diagrams showing other embodiments of the invention, and Figure 7 is a sectional view showing the start-up of a boiler to which the two inventions are applied. , FIG. 8, and FIG. 9 are diagrams showing examples of the prior art. 1... Furnace, 2... Fluidized bed. 5... Wind box, 6... Air dispersion plate, 7.
...Air jet nozzle, 9...Gas fuel supply pipe, 10
...Fluidized bed gas burner, 11...Burner branch pipe, 12...Gas jet nozzle.

Claims (8)

[Claims] (1) a furnace, a fluidized bed provided at the bottom of the furnace, an air distribution plate provided at the bottom of the fluidized bed, a wind box provided in contact with and below the air distribution plate; A fluidized bed combustion apparatus having an air jet nozzle provided on an air distribution plate and communicating the wind box and the fluidized bed, comprising: a gas fuel supply pipe arranged in the fluidized bed; and a gas fuel supply pipe arranged in the fluidized bed; Branching from the supply pipe and parallel to the air distribution plate,
A gas burner in a fluidized bed, characterized in that it has a burner branch pipe that spreads out in a planar manner, and gas ejection nozzles that are distributed and provided on the upper surface of the burner branch pipe. (2) The gas burner in a fluidized bed according to claim 1, wherein the burner branch pipes are arranged horizontally and radially. (3) The gas burner in a fluidized bed according to claim 1, wherein the burner branch pipes are arranged in a centipede shape. (4) The gas burner in a fluidized bed according to claim 1, wherein the burner branch pipes are arranged in a grid pattern. (5) The gas burner in a fluidized bed according to claim 1, wherein the burner branch pipes are arranged concentrically. (6) The gas ejection hole provided in the gas ejection nozzle and the air ejection hole provided in the air ejection nozzle are located on substantially the same horizontal plane, according to any one of claims 1 to 5. Fluidized bed gas burner. (7) A claim characterized in that the gas ejection holes provided in the gas ejection nozzles are provided radially when viewed from the center of each nozzle, and are inclined obliquely downward from the inside of the nozzle to the outside. The gas burner in a fluidized bed according to any one of Items 1 to 6. (8) Claims 1 to 1, characterized in that the gas fuel supply pipe is provided through the wind box and the air distribution plate.
The gas burner in a fluidized bed according to any one of Item 7.