JPS5977207A - Low nox burner device - Google Patents

Abstract

PURPOSE:To reduce production of NOX when coal having a high fuel ratio is burnt, by a method wherein, in a device which effects multi-fuel combustion of pulverized coal comprising high fuel ratio coal and low fuel ratio coal, the grain of high fuel ratio coal is sized to be smaller than that of low fuel ratio coal on the whole for combustion. CONSTITUTION:A pulverizer 3 for high fuel ratio coal and a pulverizer 4 for low fuel ratio coal, whereto coal is supplied from a bunker 5 for high fuel ratio coal and a bunker 6 for low fuel ratio coal, feed them out to a pulverized coal feed line 9 leading to a burner 2. When a fuel ratio is varied resulting from a change in the type of coal, the power of a motor 12 of the pulverizer for high fuel ratio coal is varied, but even in this case, the grain size regulator of a classifying device 14 is controlled so that the power is maintained at a constant value. Namely, when entrance of high fuel ratio coal results in reduction in the power of the motor 12, the classifying device 14 is regulated so that the grain size reduces. As a result, coal is decreased in grain size as it is increased in fuel ratio, and this permits reduction of production of NOX.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a pulverized coal low NOx combustion device, and is particularly suitable for burning high fuel ratio coal with low NOx.

Regarding pulverized coal combustion equipment.

[Prior art]

There are various types of coal depending on its composition, and in particular, coal with a high fixed carbon content is called high fuel ratio coal, depending on the ratio of fixed carbon to volatile content in the coal. In conventional boilers, there are almost no examples of burning high fuel ratio coal, and when high fuel ratio coal is combusted in conventional boilers, it is difficult to burn due to the small amount of volatile matter contained in the coal. Therefore, it has been difficult to achieve highly efficient combustion with little unburned matter or low NOx combustion.

In addition, in the past, attempts have been made to achieve low unburned content and low NOx combustion by mixing high fuel ratio coal and low-twisted dead ash, but only the amount proportional to the amount of low fuel dead ash mixed All that could be expected was a reduction in unburned carbon dioxide and NOx.

[Purpose of the invention]

The purpose of the present invention is to reduce NO when burning coal with a high fuel ratio.
An object of the present invention is to provide a pulverized coal combustion device that can reduce the generation of x.

[Summary of the invention]

Regarding the generation of NOX during combustion, high fuel ratio coal produces a larger amount of NOX than low fuel dead ash. However, when combustion experiments were carried out by varying the particle size of pulverized coal, a relationship was obtained between the amount of NOx produced and the unburned content in the resulting combustion ash, as shown in Figure 1. Under the same unburnt content in the ash,
The amount of NOx produced decreases as the particle size becomes finer in high-fuel ratio coal, and is not related to particle size in low-fuel dead ash. From this, in mixed combustion of high fuel ratio coal and low fuel ratio coal, the difference in particle size distribution of high fuel ratio coal governs the amount of NOx produced.

The reason for this is that even though the particle size of low-fuel ratio coal is larger than that of high-fuel ratio coal, it has a large amount of volatile matter, so it releases a large amount of volatile matter during the thermal decomposition process after being blown into the furnace, resulting in the combustion of volatile matter. In this case, the air-fuel ratio locally becomes extremely low, and the ring element 1'IN compound is likely to be released, resulting in low NOX production. On the other hand, since the secondary fuel coal has a small volatile content, the nitrogen content in the coal is difficult to release as reducing N compounds, and the generation of NOx increases, but when the particle size is Jj, the specific surface area is As a result, the release of reducing nitrogen compounds becomes more likely to occur, and NO
The generation of X is decreasing. Moreover, due to the presence of low fuel ratio disasters, the NOx generated from high eR dead ash can also be reduced by the action of a large amount of reducing N compounds generated.

[Embodiments of the invention]

Hereinafter, the self-evident actual measurement sequence of F1 will be explained with reference to FIG.

This 15 light consists of a boiler 1, a pulverized coal burner 2, a high fuel ratio coal cleaning powder 4i% lie 3, a substitute fuel dead ash pulverizer 4, and a high fuel ratio coal bunker 5 for supplying coal to the pulverizer. It is composed of a bunker 6 for low fuel ratio, a bunker 7 for high fuel ratio coal, a feeder 8 for low combustion dead ash, and a pulverized coal supply line 9 from each crusher to the burner.

The pulverized coal pulverized by the pulverizer is supplied to the pulverized coal burner 2 through the pulverized coal supply line 9 by the conveying air 10 supplied to the pulverizer by the fan 11, and is burned in the furnace of the boiler 1. In this case, the higher the fuel ratio of coal, the easier it is to be crushed, so coal with a higher fuel ratio requires less power in the crusher. During boiler operation, the type of coal used as fuel changes and the fuel ratio changes.The power of the electric motor 12 of the ash crusher changes, but even in that case, the power of the motor 12 of the ash crusher changes. The particle size controller of the classifier 14 is operated so as to keep the particle size constant. In other words, the machine 1 that contains coal with a high fuel ratio and has a constant speed
If the power of classifier 14 decreases, the power of classifier 14 decreases to 1.
: [Adjust so that it becomes 1. As a result, the particle size of coal with a high fuel ratio is rIfl, 1tkN
Oxification can be realized.

Further, another embodiment of the present invention will be explained with reference to FIG.

The difference between this actual hili example and the embodiment shown in FIG.
Whereas the conventional method is equipped with a pulverizer for dead ash and a pulverizer for low-fuel composition, this embodiment is equipped with a pulverizer 5 for mixed coal of both types, and the accompanying control system. There is a difference of 11 feet and 1 line. That is, in this embodiment, when the fuel ratio of coal entering the highly twisted T1 dead ash bunker 5 changes, the power consumption of the electric motor 12 of the mixed coal pulverizer 3 changes, but even in that case, this power is kept constant. High twist P [Manipulate the supply amount of the carbonization feeder 7. In this case, the supply amount of the low-fuel dead ash feeder 8 is also controlled so that the flow rate of the supply line 9 to the burner 1 is constant. At this time, in the implementation row l, the classifier 14
However, in this embodiment, the classifier 14 is not operated in order to avoid changing the particle size of the low-fuel coal. In addition, when the power of the electric motor 12 of the crusher decreases due to coal having a high fuel ratio entering the high fuel ratio coal bunker 5, the number of feeders of the high fuel ratio coal feeder 7 is increased. Adjust. At the same time, the supply amount of the low fuel ratio feeder 8 is reduced in proportion to the increase. As a result, although the maximum particle size of the pulverized coal leaving the pulverizer 3 is regulated, it is a mixed coal with a high fuel ratio of fine particle size and a high fuel content, and low NOx can be achieved.

Furthermore, Ike no Mi+i of the present invention! I will explain about N.

In this husband//i1i column, the particle size of the classifier 14 is adjusted instead of manipulating the supply amount of one cofeeder 7, 8 at the 3181st life y1. ') Mari, Takanorenka dead ash is Banka 5
After entering the machine, the lifting platform and the classifier 14 are operated to reduce the particle size by reducing the assistance of the electric motor. Since the crest of the dead ash of Narai and Mr. 1 fuel is also RF411, the power required for the mixed coal pulverizer increases, but if this is allowed to a certain extent, sufficient reduction in NOx can be achieved in this example as well. In the figure, 13 is a crushing machine, and 15 is a classifier.

〔Effect of the invention〕

According to the present invention, it is possible to reduce the generation of reducing N compounds from highly twisted dead ash to 1≠ as much as possible during the thermal decomposition in the early stage of combustion, and also to reduce the generation of reducing N compounds from highly twisted dead ash to 1≠ as much as possible. Since the original N compound can be used to reduce NOx, it is possible to reduce the amount of NOx that is generated in large amounts during the combustion of high fuel ratio coal, thereby reducing its generation.

[Brief explanation of drawings]

The figure shows the amount of NOx produced during the combustion of enemy coal in relation to the unburned content in the ash. It is a systematic diagram. l...Boiler, 2...Burner, 3, 4...Crusher, 5...High twist I/1 ratio coal bunker, 6...Low fuel dead ash bunker, 7...High; incorrect Dead ash feeder, 8...Low fuel ratio coal feeder, 9...Pulverized ash 1 running supply, IO...Transporting air, ll...Fan, 12...Crushing 1 configuration Motive. Figure 1: Continuation of page 1 Inventor: Takao Hishinuma 3-1-1, Saiwai-cho, Hitachi City Stock% formula No. 2 Babcock-Hitachi Co., Ltd. 0 Applicant: Babcock-Hitachi Co., Ltd. Tokyo 2-6-2 Otemachi, Chiyoda-ku, Miyako

Claims (1)

[Claims] 1. In a combustion device that co-combusts pulverized coal of high fuel ratio coal and low fuel dead ash, the particle size of the high fuel ratio coal is made finer than the particle size of the previous and low fuel dead ash. A low NOx combustion device featuring: