JPH0531364Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a pulverized coal-fired burner, and in particular heats the fuel injection port side of the flame ejected from the fuel injection port of a pulverized coal nozzle to reduce the amount of NOx generated. This invention relates to a pulverized coal-fired burner that can reduce the

[Prior Art] A pulverized coal-fired burner as shown in FIG. 3 is generally known.

As shown in the figure, a throat-shaped opening b is provided in the furnace wall a.
A pulverized coal nozzle d is provided through which fuel is injected into the furnace interior c. Further, the fuel injection port e of the pulverized coal nozzle d is provided with a ventilation passage f for sending combustion air toward the inside of the furnace c along the fuel injected from this, and inside this ventilation passage f. A flow divider g is provided to divide the combustion air into areas closer to the center of the opening b and closer to the outer periphery, and the velocity of the combustion air divided into the axial side and the distal side of the opening b is provided. Inner vanes h and outer vanes i are provided for changing the distribution.

Therefore, the pulverized coal as a fuel flows through the pulverized coal nozzle d
It is blown out toward the inside of the furnace c, and is ignited by an ignition device (not shown) to turn into a flame and heat the inside of the furnace c. Further, combustion air at this time is sent in from the ventilation passage f to adjust the combustion of the pulverized coal.

[Problems that the invention aims to solve] Conventional burners for pulverized coal-fired boilers have the problem of generating a large amount of NOx when pulverized coal is burned. It has become desirable to achieve combustion.

Furthermore, it has conventionally been thought that the oxidation rate of N contained in fixed carbon (Char) in pulverized coal increases as the fixed carbon heating temperature increases, as shown by the dotted line in FIG. However, as a result of experiments, the inventors of the present invention found that the oxidation rate of N decreases when the heating temperature of fixed carbon exceeds T° C. (approximately 1300° C.), as shown by the solid line in FIG.

Therefore, the present invention was devised in consideration of the above circumstances, and its purpose is to
The object of the present invention is to provide a pulverized coal-fired burner that can reduce the amount of NOx generated as much as possible by heating the upstream side of the flame, which has a relatively low temperature.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a pulverized coal-fired burner having a pulverized coal nozzle, in which the pulverized coal nozzle has a cylindrical shape with a ring-shaped fuel injection port. It has a housing and is provided with an auxiliary burner inside the housing to heat the fuel injection port side of the flame ejected from the ring-shaped fuel injection port to a temperature exceeding 1300°C.

[Function] With the above configuration, the flame ejected from the fuel injection port of the pulverized coal nozzle has a relatively low temperature and produces NOx.
1300 with an auxiliary burner on the fuel injection port side where the amount of fuel generated is large.
By heating the pulverized coal to a temperature exceeding .degree. C., oxidation of N in the pulverized coal, especially the fixed carbon that is a component thereof, injected from the fuel injection port is suppressed.

[Example] Next, an example of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, the pulverized coal-fired burner 1 includes a pulverized coal nozzle 5 and an opening 3 for injecting fuel into the furnace 4 through an opening 3 provided in a furnace wall 2, as in the conventional example.
A ventilation passage 6 through which combustion air is blown into the furnace 4
It is composed of. A flow divider 7, an outer vane 8, and an inner vane 9 are provided in this ventilation passage 6.
divides the combustion air to be blown into the axial side and the distal side of the blown opening 3, the outer vane 8 adjusts the amount of combustion air blown, and the inner vane 9 especially controls the axial side of the opening 3. Adjust the amount of combustion air blown to the core side. The velocity distribution of combustion air is changed by the flow divider 7, outer vane 8, and inner vane 9, and the pulverized coal nozzle 5
The degree of combustion of the flame injected from the flame is adjusted.

Particularly in the present invention, the pulverized coal nozzle 5 is formed of a cylindrical housing having a ring-shaped fuel injection port 10 at its tip, and is surrounded by the ring-shaped fuel injection port 10. The part that has been removed will take on a hollow cylindrical shape. In the hollow portion or housing of the cylindrical pulverized coal nozzle 5 formed in this way, there is an injection port 10 located approximately at the axial center of the fuel injection port 10, and a flame injection port 10 for injecting flame from the fuel injection port 10. An auxiliary burner 11 is provided for heating the sides to temperatures above 1300°C.

An auxiliary burner nozzle 12 for substantially injecting fuel is formed at the tip of the auxiliary burner 11. Further, the inner wall of the pulverized coal nozzle 5 surrounding the auxiliary burner 11 has castable coal 14 on its surface.
are laminated to form a heat-resistant wall structure. Further, the hollow part of the pulverized coal nozzle 5 forms an air passage 13 for supplying or sending combustion air to the auxiliary burner 11. That is, the hollow part of the cylindrical pulverized coal nozzle 5 forms the air passage 13 of the auxiliary burner 11, and the auxiliary burner nozzle 12 is provided in this air passage 13. A swirler 15 is provided at the tip of the auxiliary burner nozzle 12 to improve the combustion of the auxiliary burner by stirring the combustion air blown in the direction in which the auxiliary burner nozzle 12 injects fuel in the air passage 13. It is being The fuel ejected from the auxiliary burner nozzle 12 may be pulverized coal, oil, or gas.

With the above configuration, the flame is injected from the pulverized coal nozzle 5 through the opening 3 into the furnace 4, and the fuel ejected from the auxiliary burner nozzle 12 is ignited by the ignition device (not shown) and becomes a flame.
The side of the fuel injection port 10 of the flame injected from the pulverized coal nozzle 5 is heated. At the same time, the auxiliary burner 11
The combustion air blown from the auxiliary burner 11 is stirred by the swirler 15.
Optimize the combustion condition.

In this way, the pulverized coal nozzle 5 is
NOx generated from the combustion flame can be suppressed by heating the nozzle side of the flame injected from the combustion flame to a temperature exceeding 1300°C.

[Effects of the Invention] As is clear from the above explanation, the present invention provides the following excellent effects.

The flame of the pulverized coal-fired burner burns the fuel injection port side, which has a low temperature and generates a large amount of NOx, with an auxiliary burner.
Heat to temperatures exceeding ℃. By the way,
The amount of NOx generated can be suppressed as much as possible, and low NOx combustion can be achieved with the burner alone.

[Brief explanation of the drawing]

Figure 1 is a side sectional view showing an embodiment of the pulverized coal-fired burner of the present invention, and Figure 2 is the relationship between the oxidation rate of N contained in the fixed carbon (Char) in the pulverized coal and the heating temperature of the fixed carbon. FIG. 3 is a side sectional view showing a conventional pulverized coal-fired burner. In the figure, 1 is a pulverized coal-fired burner, 5 is a pulverized coal nozzle, 10 is a fuel injection port, and 11 is an auxiliary burner.

Claims (1)

[Scope of utility model registration request] In a pulverized coal-fired burner having a pulverized coal nozzle, the pulverized coal nozzle has a cylindrical housing having a ring-shaped fuel injection port, and a flame injected from the ring-shaped fuel injection port into the housing. A pulverized coal-fired burner characterized by being equipped with an auxiliary burner that heats the fuel injection port side to a temperature exceeding 1300°C.