JPH05141617A - Flame retardant plural fuel combustion furnace - Google Patents

Abstract

PURPOSE:To prevent lowering of practicality of a furnace due to upward extensive dispersion of a burner and to prevent contact of a furnace wall with flame by disposing burners of different types of fuel at four corners and sides of a horizontal square section. CONSTITUTION:One flame retardant fuel burner 4 and an assist burner 8 are provided at corners, and other flame retardant fuel burner 6 is disposed at a center of the side of a furnace. The burners are so disposed as to regulate angles in a horizontal direction. The burners 4 are disposed in multi-stages at the corner, the burners 8 may be disposed therebetween, and the burner 5 may be disposed in multi-stages at the side. Thus, in the case of an existing facility, a decrease in an allowable load is suppressed, lacking in a furnace is prevented, and a heat load at the side of the furnace in which the heat load is concentrated is alleviated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler combustion furnace.

[0002]

2. Description of the Related Art Various burners installed in a conventional combustion furnace such as a boiler have a corner firing system (tangential firing system) in which the levels are arranged at different levels above and below the four corners of the combustion furnace. There is a horizontal firing method (opposed combustion method) arranged on the front wall or front and rear walls of the combustion furnace. As the fuel, blast furnace gas and coal, which are evaluated to be flame-retardant in view of the amount of heat absorbed by the furnace, are considered as flammable heavy oil, and the combustion method (burner arrangement) is selected. Large boilers often employ a corner firing system that uses coal or blast furnace gas as fuel, and small boilers often employ a horizontal firing system that uses heavy oil as a fuel.

The characteristics of blast furnace gas, coal and heavy oil as a boiler fuel are as follows. First, the heat exchange characteristics in the boiler are remarkably different between the blast furnace gas and the heavy oil. Coal can be considered to be in the middle of the two. The theoretical combustion temperature is about 2000 ° C for heavy oil, but 140 for blast furnace gas.
It is quite low at 0 ° C. The amount of combustion produced gas is about twice as much in blast furnace gas as in heavy oil. The heavy oil combustion flame is a bright flame, but in the case of blast furnace gas, it is a bright flame. The heat absorption amount of blast furnace gas in a furnace is significantly lower than that of heavy oil. These are summarized in the table below.

[0004]

[Table 1]

FIG. 3 is a vertical cross-sectional side view showing an example of a conventional corner fire ring type flame-retardant fuel-fired boiler, and FIG. 4 is a schematic view showing the burner arrangement. Also in FIG.
FIG. 6 is a diagram schematically showing another example of the conventional burner arrangement. First, in FIG. 3, a blast furnace gas burner (4) is provided at the lower four corners of the furnace (1), blast furnace gas is supplied from a fuel pipe (3), and a heavy oil burner (8) for auxiliary combustion is provided above it. Further above that, a coal burner (6) to which pulverized coal is supplied from the pulverizer (11) is provided. As shown in FIGS. 4 and 5, the burners are arranged so that fuel is ejected from the corners in the tangential direction of the virtual circle.

Although not shown, in the horizontal firing method, a large number of multi-stage burners are arranged in one side of the furnace wall, and in the opposite combustion method, a large number of burners are arranged so as to face each other in two opposite sides of the furnace wall. A multi-stage burner is arranged.

[0007]

The conventional flame-retardant fuel combustion furnace has the following problems to be solved. 1) In the existing combustion furnace of a boiler, for example, when a function of using coal in addition to using blast furnace gas is added, a problem that the rated load cannot be carried occurs. 2) A failure (for example, a sudden drop in steam temperature in the case of a boiler, called Excursion in English) occurs due to the phenomenon of the recirculated gas falling out of the furnace. 3) Each combustion flame contacts the furnace wall, causing incomplete combustion and damage to the furnace wall due to rapid cooling. 4) It is necessary to increase the size (especially height) of the furnace, which is very expensive. 5) Problems occur due to the maximum concentration of the heat load on the furnace wall.

[0008]

In order to solve the above-mentioned conventional problems, the present invention is directed to a combustion furnace having a rectangular horizontal section for burning an easily combustible fuel and two kinds of flame-retardant fuels. Flame-retardant multi-fuel combustion furnace characterized by arranging burners of different kinds of fuel at four corners and four sides of the same; and a rectangular horizontal section for burning an easily combustible fuel and two flame-retardant fuels In the combustion furnace, the burners for two kinds of fuel among the above three kinds of fuels are arranged at the four corners of the rectangular horizontal section, and the burners for the other one kind of fuel are arranged on the four sides of the substantially same rectangular horizontal section. This invention proposes a flame-retardant multiple-fuel combustion furnace characterized by being arranged.

[0009]

Since the present invention is constructed as described above, it has the following functions. 1) The utilization of the furnace is prevented from being lowered due to the spread of the burners in the upward direction. In the case of existing equipment, the above-mentioned allowable load reduction is suppressed and the rated load can be borne, or the load reduction rate is suppressed to a small level. When installing a new furnace, the size of the furnace will not increase. 2) The hollowing of the furnace is prevented, and the obstacles caused by the escape of the recirculated gas and the combustion gas are prevented. 3) Interference with the flame prevents contact with the furnace wall. 4) Heat load is concentrated and maximized, and the heat load on the furnace side is reduced and averaged as a whole. 5) When the recirculation gas is introduced from the bottom of the combustion furnace (below the burner level), the mixing of the recirculation gas in the furnace is promoted, and the obstruction caused by the cylinder drop phenomenon (for example, in the case of a boiler, steam temperature Sudden descent) is prevented.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 (a) is a vertical sectional side view showing a first embodiment of the present invention, and FIG. 1 (b) is a horizontal sectional view of the same. In this embodiment, each corner portion is provided with one flame-retardant fuel burner, for example, a blast furnace gas burner (4) and auxiliary fuel oil or natural gas burner (8), and the other flame-retardant fuel burner, for example, a coal burner (6). ) Is placed in the center of the furnace side. The angle can be adjusted horizontally.

Next, FIG. 2A is a vertical sectional view showing a second embodiment of the present invention, and FIG. 2B is a horizontal sectional view of the same. In this example, one of the flame-retardant burners (6a), (6b)
Is arranged so as to be displaced from the center of the furnace side. This burner (6)
May be only the right side (6a) or only the left side (6b) of the center of the furnace side, or both. Also, the angle can be adjusted horizontally. When installing flame-retardant burners on the left and right sides of the center of the furnace side, one flame-retardant burner (6
If the flame of a) is left-handed, the other (6b) is turned leftward in a direction in which the flame does not interfere with the burners (4) and (8) provided at the corners. (Fig. 2
In each of the above two embodiments, the burners are provided at the four corners and the four sides and are arranged at the same level as much as possible.

In FIG. 1, blast furnace gas burners (4), which are flame-retardant fuels, are arranged in multiple stages (three stages in the illustrated example) at the corners, and heavy oil or a natural gas burner (flammable fuel for supporting combustion) ( 8) is arranged between these, and the coal burner (6) which is another flame-retardant fuel is arranged in multiple stages on the sides, but the blast furnace gas burner (4) and the coal burner (6) which are flame-retardant fuels are arranged. ) May be replaced. Further, in the corner part, a blast furnace gas burner (4) or a coal burner (6) of flame-retardant fuel is arranged in the lower part, and a flammable burner (8) is provided above the burner gas burner (8) and other flame-retardant fuel is provided on the furnace side. Coal burners (6) or blast furnace gas burners (4) may be placed at the same level. Furthermore, a blast furnace gas burner (4) and a coal gas burner (6) for flame-retardant fuel may be provided at the corners, and a heavy oil or natural gas burner (8) for flammable fuel may be provided at the furnace side. Also in the case of the burner arrangement shown in FIG. 2, as in the case of FIG. 1, the combination of the burners may be changed in any way.

[0013]

According to the present invention, the following effects can be obtained. 1) The utilization of the furnace is prevented from being lowered due to the spread of the burners in the upward direction. In the case of existing equipment, it is possible to reduce the allowable load and bear the rated load. Even if the burden cannot be paid, the load reduction rate is suppressed to a small level. When installing a new furnace, the size of the furnace will not increase. 2) The hollowing of the furnace is prevented, and the obstacles caused by the escape of the recirculated gas and combustion gas from the cylinder are prevented. 3) Interference with the flame prevents contact with the furnace wall. 4) Heat load is concentrated and maximized, and the heat load on the furnace side is reduced and averaged as a whole. 5) When the recirculation gas is introduced from the bottom of the combustion furnace (below the burner level), the mixing of the recirculation gas in the furnace is promoted, and the obstruction caused by the cylinder drop phenomenon (for example, in the case of a boiler, steam temperature Sudden descent) is prevented.

[Brief description of drawings]

FIG. 1 is a burner layout drawing showing a first embodiment of the present invention.

FIG. 2 is a burner arrangement diagram showing a second embodiment of the present invention.

FIG. 3 is a vertical cross-sectional side view showing an example of a conventional corner-firing type flame-retardant combustion-fired boiler.

FIG. 4 is a diagram showing a burner arrangement of the boiler shown in FIG.

FIG. 5 is a diagram showing another example of a conventional burner arrangement.

[Explanation of symbols]

(1) Furnace (2) Combustion hot air (3) Fuel (blast furnace gas) pipe (4) Blast furnace gas burner (5) Coal (6), (6a), (6b) Coal burner (7) Auxiliary combustion Fuel (8) Burner for auxiliary combustion (9) Cold air for hot air temperature control for coal drying (10) Booster fan for dry air (11) Crusher

Claims (2)

[Claims] 1. A combustion furnace having a rectangular horizontal section for burning an easily combustible fuel and two kinds of flame-retardant fuel, burners of different kinds of fuel are arranged at four corners and four sides of the rectangular horizontal section, respectively. A flame-retardant multi-fuel combustion furnace characterized by the following. 2. A combustion furnace having a rectangular horizontal section for burning an easily combustible fuel and two kinds of flame-retardant fuel, wherein burners for two kinds of fuel among the three kinds of fuel are provided at four corners of the rectangular horizontal section. A flame-retardant multiple-fuel combustion furnace characterized in that burners for another type of fuel are arranged on four sides of a substantially rectangular horizontal cross-section similar to the above.