JPH01217110A - Pulverized coal burner - Google Patents

Abstract

PURPOSE:To catch only minute fine particles into a flame holding device and promote the ignition of the mixture of pulverized coal and air by providing an air straightening block on the central axis of a pulverized coal pipe and a particle separator of louver type and providing heating means on the inside surface of a furnace in a flame holding device. CONSTITUTION:Pulverized coal supplied to a pulverized coal pipe 20 is diffused and straightened in its flow by a flow straightening block 101 on a distance piece 61 and coarse particles and air mixture in the flow move to the inner circumferential side and fine particles and air mixture to the outer circumferential side. The minute particles and air mixture on the outer circumferential side is caught by a flame holding ring 50 and edge 51 and the mixture with secondary air which is involved-in by the ring 50 form an area of stagnant minute vortexes. The mixture of coarse particles and air on the inner circumferential side is in the state of being roasted and the gasification of the NOx in the char is promoted and in the downstream of the burner flame the generation of NOx is suppressed. A louver 100 is supported by a piece 61 and it is slid on the piece to collect a proper mixture of minute particles and air near the flame holding ring 50. The collected mixture is heated by the flame holding ring 50 and ceramics heater 201 on the edge 51 and ignited.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pulverized coal combustion device, and particularly to a pulverized coal combustion device suitable for promoting the ignition of high fuel ratio coal (low volatile bone coal).

[Prior Art] FIG. 4 is a cross-sectional view of the upper half of a low NOx pulverized coal burner having a peripheral flame holder having a cross-sectional shape according to the prior art. This device includes a pulverized coal pipe 20 that opens into a burner throat portion 10 on a side wall of the furnace, a flame-holding ring 50 that is provided at the spout of the pulverized coal pipe 20 and has a cross-sectional shape, and a flame-holding ring 50 that has a cross-sectional shape. A flame-holding edge 51 provided on one side in the direction of the center of the pulverized coal pipe;
A secondary air sleeve 30 provided on the outer periphery of the pulverized coal pipe 20, an outward guide sleeve 31 provided at the tip of the secondary air sleeve 30, and a space between the pulverized coal pipe 20 and the secondary air sleeve 30. a secondary air register 33 and a secondary vane 32 provided in the secondary air passage of the tertiary air register 43 provided in the tertiary air passage between the secondary air sleeve 30 and the burner throat 18, and the pulverized coal pipe. 20
A distance piece 61 provided at the center of the distance piece 61 and a startup burner 6 attached to the tip of the distance piece 61 for starting.
It is composed of 0.

In the above burner configuration, the pulverized coal is transported by the conveying air (-secondary air) and becomes a pulverized coal flow to the pulverized coal pipe 2.
It is injected into the furnace from 0 through the jet nozzle. At this time, a vortex is generated inside the L-shaped part of the flame-holding ring 50 by the cross-sectional flame-holding ring 50 and the flame-holding edge 51, and the pulverized coal flow is diffused to the outside of the L-shaped part by this vortex. The flame is suppressed and ignites at this point, creating a flame-holding effect. On the other hand, the secondary air passes through the secondary air register 33, is given a swirling force by the secondary vane 32, is supplied into the furnace through the outer periphery of the flame caused by the combustion of the pulverized coal flow, and is further supplied into the furnace through the tertiary air register 33. Air is supplied into the furnace from the outer periphery of the secondary air via a tertiary air register 43.

Note that when starting up the coal boiler, oil is sprayed from the startup burner 60 provided at the tip of the distance piece 61 and ignited.

In such a device, it is possible to prevent the diffusion of pulverized coal and bring the high-temperature reduction region extremely close to the tip of the burner, thereby improving the ignitability of the pulverized coal tube spout and performing good gas phase reduction. However, in order to maintain this function, a stagnation area of the pulverized coal is formed along the inner circumference of the flame-holding ring at the tip of the pulverized coal tube, and the pulverized coal is not dispersed in the radial direction more than necessary, but rather quickly at the spout. It is necessary to ignite it. Therefore,
Low-fuel ratio coal with a high volatile content is effective, but conversely, when using high-fuel ratio coal with a low volatile content, additional methods are required to achieve rapid ignition. Functionality must be added.

Even if the type of coal has the same volatile content, the particle size of the pulverized coal obtained depending on the performance of the coal pulverizer (mill) and the pulverized coal/lI! Since the weight ratio (C/A) of the blown air differs, these greatly influence rapid ignition and flame holding in the burner. Experience has shown that for rapid ignition, the higher the content of fine particles of 40 μm or less, the better, and the higher the value of C/A. However, it is difficult to match mill control functions with requirements that follow each load of the boiler.

[Problem to be solved by the invention]

An object of the present invention is to solve the problems of the prior art and provide a pulverized coal combustion device that can promote rapid ignition without adding any additional functions and regardless of coal type and mill performance. There is a particular thing.

[Means to solve the problem]

The present invention provides a pulverized coal pipe that is inserted into a burner throat of a side wall of a furnace and supplies pulverized coal and air into the furnace, a means for supplying pulverized coal and air to the pulverized coal pipe, and the pulverized coal pipe and its outer periphery. A secondary air passage formed between the secondary air supply pipe provided on the side, a tertiary air passage formed outside the secondary air supply pipe, and a secondary air passage formed between the secondary air and the tertiary air supply pipe. In a pulverized coal combustion apparatus comprising means for supplying air or oxygen-containing gas to each air passage, and a flame stabilizer provided near the tip of the pulverized coal pipe, the pulverized coal on the upstream side of the flame stabilizer The present invention is characterized in that a rectifying block and a louver-shaped coarse particle separator are provided on the center axis of the tube, and if necessary, a heating means is provided on the inner surface of the furnace of the flame stabilizer.

[Effect]

The block-shaped rectifier block and louver-shaped coarse particle separator installed on the central axis of the pulverized coal tube allow only the fine particles suitable for rapid ignition to be captured in the flame stabilizer, promoting ignition of the pulverized coal mixture. . Furthermore, since the earlier louver type coarse particle separator can be slid on the central axis of the pulverized coal tube, appropriate fine particles can be collected near the flame stabilizer. Furthermore, this pulverized coal mixture can be ignited more rapidly by providing a heating means (for example, a ceramic heater) on the furnace inner surface of the flame stabilizer.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to Examples.

FIG. 1 is an upper half sectional view of a pulverized coal burner showing one embodiment of the present invention, and FIG. 2 is a front view of the flame-holding ring shown in FIG. 1. In FIG. 1, the same parts as in FIG. 4 are denoted by the same reference numerals, and the description thereof will be omitted. The difference between the figure and FIG. 4 is that a rectifying block 101 supported by a distance piece on the central axis of the pulverized coal pipe 20 on the upstream side of the flame-holding ring 50 having an angled cross-section
Moreover, a plurality of electric ceramic heaters 201 are provided on the louver 100, the flame-holding ring 50, and the flame-holding edge 51.

In such a configuration, the pulverized coal pipe 2 is
The pulverized coal supplied to the pulverized coal is dispersed and rectified in the radial direction at one end by a rectifying block 101 installed on a distance piece 61, and then passed through a louver l installed at its rear end.
The OO separates the mixture into a coarse particle mixture and a fine particle mixture. That is, the coarse particle mixture moves toward the inner circumference, and the fine particle mixture moves toward the outer circumference. The fine particle mixture on the outer circumferential side is captured by the flame stabilizing ring 50 and the flame stabilizing edge 51, and forms a micro-vortex stagnation area along the inner circumference of the flame stabilizing ring 50 together with the secondary air drawn in by the flame stabilizing ring 50. do. on the other hand,
The coarse-grained pulverized coal mixture diverted to the inner peripheral side enters a so-called "steamed" state on the central axis of the burner, and gasification of nitrogen compounds (NOx) in the char is promoted. Therefore, in the wake of the burner flame, N from the coarse-grained char
0X generation can be suppressed.

The louver 100 is supported by a distance piece 61, and is connected to the distance piece 61 via this support rod.
It is possible to slide the top in the direction of the burner axis,
Thereby, an appropriate mixture of fine particles can be collected in the vicinity of the flame stabilizing ring 50.

The air-fuel mixture containing fine particles collected at an appropriate concentration is heated by the ceramic heater 201 installed on the flame-holding ring 50 and the flame-holding edge 51, and ignites.

Since the ceramic heater 201 is red-hot to 1000'C or more, the surface of the flame-holding ring 50 acts as a ignition source.

The ignited pulverized coal group continues to be flame-stabilized due to the large self-recirculation region created by the tertiary air in which a strong swirling flow is formed by the tertiary air register 43. When the ambient temperature rises due to continued combustion and the radiation conditions that do not require red heat from the ceramic heater 201 are satisfied, the power to the ceramic heater 201 may be turned off.

FIG. 3 is an ignition flame holding limit diagram when the burner of the present invention and the conventional burner were tested in a test furnace 500 (kg/h, coal equivalent). In the figure, A is a case where a conventional burner is used, and B is a case where a burner of the present invention is used. By using the burner of the present invention, it becomes possible to self-ignite and hold the flame of high-fuel ratio coal with low volatile content, and it becomes possible to lower the temperature of the preheated air. Therefore, the limit of horizontal combustion in the boiler can be relaxed, and the timing of coal injection at the time of boiler cold can start-up can be brought forward.

In addition, since the surfaces of the louver 100 and the rectifying block 101 in the present invention are likely to wear out due to collisions with pulverized coal, it is preferable to use a wear-resistant material such as ceramics for some or all of them.

〔Effect of the invention〕

According to the present invention, it is possible to collect the fine particle mixture necessary for rapid ignition, and the heater in which the mixture is embedded in the flame-holding ring provides rapid ignition capability. Therefore, the types of coal that can be used can be expanded, and there is no need to add another function when using high fuel ratio coal. Furthermore, combustion can be maintained even in a low load range, and the amount of oil used during startup of the coal boiler can be reduced, improving economic efficiency.

[Brief explanation of the drawing]

FIG. 1 is an upper half sectional view of a pulverized coal burner showing an embodiment of the present invention, FIG. 2 is a front view of the flame-holding ring shown in FIG. 1, and FIG. 3 is a cross-sectional view of the burner of the present invention and a conventional burner. FIG. 4 is an upper half sectional view of a pulverized coal burner according to the prior art. 10... burner throat, 20... pulverized coal pipe, 30
...Secondary air sleeve, 31...Guide sleeve,
32... Secondary vane, 33... Secondary air register,
43...Tertiary air resistor, 50...Flame holding ring,
51... Flame holding edge, 60... Start-up burner, 61... Distance piece, 100... Louver, 101... Rectifier block, 201... Ceramic heater. Agent Patent Attorney Takeshi Kawakita 10: Burner throat 20: Pulverized coal pipe 50: Flame holding ring 51: Flame holding edge 60 Nice start up burner 61: Discun spine 100: Root 101: Rectifier block 2nd Figure 3: Volatile content ('/, da(): 0 Inventor: Koji Kuramasu, Houno, Kure City, Hiroshima Prefecture

Claims (1)

[Claims] (1) A pulverized coal pipe that is inserted into a burner throat on a side wall of the furnace and supplies pulverized coal and air into the furnace, a means for supplying pulverized coal and air to the pulverized coal pipe, and the pulverized coal pipe and its outer peripheral side. a secondary air passage formed between the secondary air supply pipe provided in the secondary air supply pipe, a tertiary air passage formed outside the secondary air supply pipe, and the secondary air and the tertiary air In the pulverized coal combustion apparatus, the pulverized coal combustion apparatus includes a means for supplying air or an oxygen-containing gas to each of the passages, and a flame stabilizer provided near the tip of the pulverized coal tube, the pulverized coal tube upstream of the flame stabilizer. A pulverized coal combustion apparatus characterized in that a rectifying block and a louver-shaped coarse separator are provided on a central axis, and further, if necessary, heating means is provided on the inner surface of the furnace of the flame stabilizer.