JPS5824712A - Method of blow-in combustion of pulverized coal - Google Patents

Abstract

PURPOSE:To increase combustion efficiency for pulverized coal, by providing a compressed air feed pipe to a burner, and by sucking oxygen-containing gas into the center part of a suction flow of pulverized coal through the pipe. CONSTITUTION:A compressed air feed pipe 14 is provided to a burner 7, which is composed in the manner that the air is divided into two air flows D1 and D2 by a bulkhead 22, the air flow D1 becomes a straight-going flow to the center line B-B of a burner, while the air flow D2 goes through a control pipe 19, passing through a bypass slit 17, to become a swirling flow to the center line B-B of a burner. The divided ratio of the air flow D1 (straight-going flow) to the air flow D2 (swirling flow) is made adjustable by dampers 15 and 16. With such an arrangement, pulverized coal, whose combustibility is low, can rapidly and completely be burnt. A large amount of pulverized coal can be fed into the burner 7, so that fitness of pulverized coal as a fuel for a blast-furnace and the like can be enhanced.

Description

[Detailed description of the invention] The present invention relates to the blowing combustion power mK of pulverized coal fuel.

Specifically, the present invention relates to a pulverized coal injection combustion method that can efficiently burn pulverized coal.

In Tokokonoe, heavy oil was the mainstream fuel used for each melting furnace, smelting furnace, firing furnace, and boiler, but reflecting the recent energy situation, the use of coal was being considered, and the amount of fuel used There is also a trend of gradual increase.

However, while heavy oil is a liquid fuel, coal is a solid fuel, so even if it is pulverized and injected into the combustion chamber, it is the same as injecting liquid fuel, and there are various disadvantages. It has been pointed out.

The present inventor has been conducting research on a method for improving the aS properties of coal, especially pulverized coal, as one of the me problems. In order to clarify the point of failure, a pulverized coal burner used in a blast furnace tuyere will be taken as an example and explained below.

Figure 1 is a flow diagram showing the combustion testing device.

WIk powder*#i is transported from the primary cap 1 to the secondary hopper 8 by the system conveyor 2. At the bottom of the secondary hopper 1, there is a pulverized powder leg cutter attachment 4, which takes out a predetermined amount of pulverized coal and drops it onto a rotary pulp 5. Here, the rotary pulp 5 plays the role of V-V, and the pulverized coal that has passed through the rotary pulp 5 falls into the ejector 6 and is supplied to the burner 7 together with the transportation air pumped from the arrow A. On the other hand, combustion air (secondary air) is preheated in a hot stove 8, then supplied through an air register 9 to surround the burner tip, and blown into the combustion device from around the pulverized coal airflow. . A fuel gas G or heavy oil supply line 1 is connected to the burner section for ignition or auxiliary combustion.
May incorporate 0 or 11.

In order to obtain high temperatures using a pulverized coal burner like the one mentioned above, it is necessary to burn a large amount of fuel efficiently in a short period of time, but pulverized coal has poor combustibility compared to heavy oil, so it cannot be used with heavy oil by normal means. It is difficult to obtain the same level of combustion efficiency.

In particular, burners installed in high-Fi tuyeres are required to form short flames for efficient combustion, but as mentioned above, pulverized coal has poor combustibility, and the flames are long (elongated and soft). This marked a significant change in its suitability for use in blast furnace feathers.

Also, when using it as a general burner, set the flame to #C and shorten the flame (
In order to suppress this, it was necessary to reduce the amount of fuel injected, making it impossible to secure a predetermined amount of heat, and in some cases, it was necessary to increase the size of the combustion system.

In order to solve these problems, various efficient combustion methods for pulverized coal have been studied.2 For example, as shown in FIG. ]Installation, *Pulverized coal P and 2 missing characters S are thoroughly mixed together *Pulverized coal O combustion is promoted, or the amount of auxiliary fuel used is increased, and the combustion heat of auxiliary fuel is used to burn pulverized coal. It was burning. However, in the former case, the swirling blades were exposed to a high-temperature and high-speed flame atmosphere, so they suffered severe wear and tear and could not withstand long-term use. Furthermore, the latter method requires a large amount of auxiliary fuel to burn the pulverized coal sufficiently and all at once.

The economic effects of switching from heavy oil to pulverized coal will be diminished.

Other improvement methods include further increasing the temperature of the preheating secondary static electricity, and increasing the combustion air (2 air I) feeding speed at 1 m before the section 0.
Although the 7F method has been proposed, it is not completely satisfactory.

The OF414 was developed in view of this situation, and its purpose is to provide a pulverized coal injection method that can efficiently (combust) pulverized coal in a combustion chamber.Thus, the present invention The pulverized coal injection method is a pulverized coal injection combustion method in which pulverized coal is injected together with pneumatic transport and static electricity. The pulverized coal that was blown into the combustion furnace was combusted quickly and sufficiently, which made it hot.

The present invention will be described below based on the drawings, but the present invention is not limited to the illustrated examples described below, and the shape of the burner may be changed to change the in or part of the design in accordance with the spirit described above and below. It is also possible to apply the present invention to various burners other than pulverized coal burners for blast furnaces.

Fig. 8 and Fig. 4 (cross-sectional view taken along the line ■-■ in Fig. 8) are explanatory diagrams illustrating pulverized coal (-na) to which the method of the present invention is applied. It is supplied through the pipe 1jlK and injected from the burner 7 as shown by the arrow C. On the other hand, compressed air is supplied to the burner 7 through the supply pipe 14.
The gas is divided into an airflow D1 and an airflow stream by a partition 22 in the supply pipe 14. The airflow D1 is the burner center axis B.
- Flow parallel to BK (straight flow) 1gc flow D2
is introduced into the control pipe 19 through the swirling slit 17, resulting in a swirling flow centered on the burner central axis B--B.

The distribution ratio between the straight flow and the swirling flow is adjusted by dampers 15 and 16, and a mixed flow is formed according to the respective distribution ratios. Depending on the content of the mixed flow, the flow/(turn, flow velocity distribution, and spread υ angle of the airflow discharged from the tip 20 of the blow control pipe 19 will be different.
As shown in the V-line new plane arrow view in Figure 8 (Figure 5), various commonly known means such as swirl vanes and swirl slits are applied, as well as a cylinder with tangential air holes. things are used. In addition, 21 is a cooling air flow passage that sends cooling gas along the arrow E1 to suppress overheating of the burner 7. An example is shown in which the cooling passage is opened inside φ at the tooth opening, but a jacket type indirect A cooling method can also be adopted. Air is generally used as the cooling sword here, but steam,
It may also be water or the like.

The shape of the pulverized coal flame injected from the tip of the burner by the burner is shown in FIG. As mentioned above, the compressed air flow is given a swirling force.

When it is ejected from the tip 20 of the blow control tube 19, it spreads out from the direction of the arrow R in a spiral direction due to centrifugal force. On the other hand, the pulverized coal C transported by current is ejected parallel to the burner center axis 4, so that the combustion air flow E is caused by the spiral flow.
being swept away in the direction of As a result, the contact between the secondary air for combustion and the pulverized coal can be made very quickly and completely. As a result, pulverized coal burns efficiently within a short period of time. By the way, in conventional type burners that do not emit air current, pulverized coal is formed in the 1 [adcisemental manner, and diffuses little by little into the combustion air current E from the outer surface of the air flow. It takes a considerable amount of time for most of the current to flow through the trench, which simulates the combustion air, and as the diffusion is delayed, the combustion speed is delayed and the flame lengthens. With the damper 16 shown in Figure 2 for both paths fully closed, the damper 15
When fully opened, the airflow is ejected parallel to the central axis B-BK, so the spread of the pulverized coal is small and the angle is 1, but due to the entrainment phenomenon caused by the expansion force and momentum of the compressed gas, the combustion air of the pulverized coal is Diffusion in the E direction is promoted and the combustion rate is accelerated. Although the type of gas for diffusion ('IEfItD) is specified, it is absolutely necessary to use a gas that does not inhibit combustion efficiency, especially if static electricity or oxygen is used. Combustion efficiency is W! This is preferable because it is the same as above.

FIG. 7 is a graph showing the relationship between the degree of swirl (swirling air flow rate/total air flow rate) of the diffusion air flow ejected from the blow control pipe 19 and the flame length. The flame length is 1004 when no blow control pipe is provided.

The flame length ratios are shown when compressed air or compressed oxygen is used as the diffusion air flow. The total amount of the diffusion airflow is 1 fS Nm”/Hr, and the damper 15,
The distribution of turning static electricity was adjusted at 1g.

f#I combustion condition is pulverized coal supply amount: Is 5 h/H
ra Current transport capacity: 15 Nm”/Hr*Furnace temperature:
18QO℃.

Combustion static preheating temperature: 450°C, combustion exhaust gas residual acid snow concentration: 6.4°C. As is clear from the graph, the flame length according to the present invention is shorter than that according to the conventional method, and in particular, as the swirling airflow ratio increases, the flame length becomes shorter. Also, when gas is oxygenated, t/C is the effect #-
ij! ! It is noticeable that the flame length in the conventional method is 40
You can shorten it with 111.

Furthermore, increase the relative ratio of the dispersion electric body ejection speed to the 1g powder leg ejection speed or the combustion air current speed (if taken).

The diffusion mixing becomes faster, the combustion rate increases further, and the flame becomes shorter.

FIGS. 8 and 9 are schematic diagrams showing the main parts of another burner to which the method of the present invention is applied. (Fig. 8) or a turning slit (Fig. 9). However, in these examples, the flame length is controlled by the flow velocity (and flow rate) of the transport gas, so the joint range of the degree of diffusion is the same as in the previous example.]
It's a little narrower, but you can get the same effect. In addition to the above method, the present invention also includes the use of gas or heavy oil for ignition or auxiliary fuel.

This is because the present invention is configured as described above.

Pulverized coal, which has poor combustibility, can be combusted quickly and sufficiently, making it possible to inject a large amount of pulverized coal compared to conventional methods, dramatically increasing the suitability of pulverized coal as fuel for blast furnaces, etc. I ended up getting it. Also, by adjusting the swirling flow in the blow control pipe, it became possible to adjust #A to the optimum heat load distribution.

[Brief explanation of drawings]

Figure 1 is a flow diagram of the combustion experiment equipment, Figure 2 is a sectional view of the main part of a conventional pulverized coal parser with a swirl vane at the tip, and Figure 8
The figure is a front view of a pulverized coal burner to which the method of the present invention is applied, FIG. 4 is a side view of the same, FIG. 5 is a sectional view taken along line A-A in FIG. 7 is a graph showing the relationship between the degree of rotation of the injection current and the flame length ratio, and FIGS. 8 and 9 are explanatory diagrams of the rotation mechanism of a pulverized coal burner to which the method of the present invention is applied. . 7... Burner 14-- Supply pipe 17... Laser slit 19-- Blowing control tube C... Pulverized coal D... Blow air flow E... Secondary air is Figure ♂1 Swirling air Flow rate/Total air flow rate (哄) Figure 8 Figure 9

Claims (1)

[Claims] This is a pulverized coal blowing combustion method in which a pulverized coal powder leg is blown in together with a combustion static electricity, and the pulverized coal blowing combustion method is characterized in that an oxygen-containing gas is blown into the center of the pulverized powder blowing flow.