JPS6011290B2 - combustion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION For example, in a rotary kiln for firing cement, raw materials fed into a large rotary kiln are
In order to perform firing by heating to a high temperature of 550 qo, the majority of the combustion air, about 90% of the secondary air, is passed through a clinker box, preheated to about 800°C, and then flowed back into the rotary kiln to discharge the product. A large amount of heavy oil is supplied into the rotary kiln together with about 10% of the amount of high-pressure primary air from a large number of bundled high-pressure spray burners, and high-load combustion is performed.

In such large-scale high-temperature combustion, a large amount of N○× is naturally generated, and the exhaust gas contains NOx of 40Q and 10%.
Since it is contained in extremely high concentrations, it is a pollution problem, and there has been a demand for the development of combustion equipment that generates a small amount of N○x. The present inventors conducted research on low N0x combustion equipment,
As a result of repeated experiments, we first developed the combustion device shown in Figures 3 and 4.

This is provided with one large-diameter burner 21 in the center, and the large-diameter burner has a large-diameter oil jet hole 22 at its tip, and surrounding it, a primary air central flow is spouted out at high speed. It has a central flow jet hole 23, and surrounding the large diameter burner are four or one small diameter burners 24, 24', etc., each of which has a small diameter oil jet at its tip. It has holes 25, 25'..., and has annular primary air ambient flow ejection holes 26, 26'... surrounding these 4 diameter oil ejection holes and from which the primary air ambient flow is ejected at high speed. However, the structure was such that a large amount of high-temperature secondary air was supplied from the outer periphery of these burner groups of the combustion apparatus. With this structure, heavy oil is ejected in relatively fine particles from the respective heavy oil injection holes 25, 52' of the small-diameter burners 24, 24' in the surrounding area, and therefore, by supplying high-temperature secondary air. Although it is relatively short, a flame is created and the fuel is rapidly combusted, relatively large particles of heavy oil are ejected from the heavy oil jet hole 22 of the central large-diameter burner 2i, and the secondary air is The heavy oil jet of the large-mouth burner does not reach the heavy oil jet until it passes through the flame, and during this time the combustion gas generated by the surrounding small-diameter burners is also sucked into the heavy oil jet, resulting in combustion as a whole with a relatively long flame. will be carried out.

By such combustion, it was possible to reduce the amount of NO gas generated in the large medium compared to the conventional method. However, in the conventional combustion device that simply bundles a large number of heavy oil burners and the above-mentioned combustion device, when the heavy oil jets ejected from each hydraulic spray burner intersect with each other, dense lumps of heavy oil are formed there. This is a problem that occurs in high-load combustion.In order to solve this problem, we developed the combustion equipment shown in Figures 5 and 6. did. This has a primary air central flow supply path 31 in the center, and therefore has a primary air central flow jetting hole 32 in the center of the tip of the combustion device, and has four central air flow injection holes surrounding the primary air central flow supply path. one to twelve small diameter burners 33;
33', and these small-diameter burners have small-diameter oil spout holes 34, 34'... at their tips, and these four
- It has annular primary air ambient flow jetting holes 35, 35' surrounding the diameter oil jetting hole and from which a small amount of primary air peripheral flow is jetted out at high speed, and a large amount of high temperature secondary air flows through these of the combustion device. The structure was such that the fuel was supplied from the outer periphery of the burner group. With this structure, the heavy oil jets ejected from the heavy oil jet holes 34, 34' of the respective small-mouth flea burners 33, 33' are directed away from the central pipe by the action of the primary air central flow.
That is, by being spread out radially, each heavy oil jet no longer intersects with its neighbors to create a dense area of heavy oil, and is more likely to come into contact with the high-temperature secondary air, thus improving combustion and increasing combustion efficiency. I can do that.

The combustion device that the present inventors have developed this time is a combustion device that reduces the amount of N○× generated and that burns smoothly and efficiently without creating heavy oil-dense areas.

The combustion apparatus of the present invention will be explained with reference to FIGS. 1 and 2 showing embodiments thereof.

A primary air central flow supply passage 2 is provided at the center of the blowing pipe 1, and is surrounded by a primary air peripheral flow supply passage, respectively. ′・
... are arranged next to each other, so that the blowing pipe tip 7 has a primary air central flow outlet 8 in the center,
At its periphery are annular orifices 9, 9 for primary air ambient flow, respectively.
Heavy oil spout holes 11, 1 of the large-diameter burner surrounded by '...
1'... and the annular ejection holes 10, 10 for the primary air ambient flow.
' The heavy oil outlet hole 12 of the small-diameter burner surrounded by...
12'...

Note that 13 is the primary air central flow intake port 14 with a damper.
Next is the intake with a damper for the ambient air flow. 15 is the outer shell of the blowing pipe.

In the combustion apparatus of the present invention, approximately 10% of the theoretical air amount relative to the amount of heavy oil supplied is supplied as primary air into the combustion apparatus, but the primary air is supplied separately into a central flow and a peripheral flow. The central flow is larger than the surrounding flow, and the ratio is 8.
:2 to 6:4, and is supplied from each intake at a high pressure of 1000 m2 to 250 m2 water column.
The ambient flow is distributed to each burner so as to be approximately proportional to the amount of heavy oil ejected from each burner, and is ejected from around each heavy oil ejection hole.

Heavy oil is supplied to each of these hydraulic light mist burners at a high pressure of 40k9/min to 70k9/carp, and the ratio of the amount of heavy oil ejected from the large diameter burner to the amount of heavy oil ejected from the small diameter burner is 9:1 to 7: It is 3. The secondary air, which is about 90% of the combustion air, passes through the clinker box, flows back to the product discharge, enters the rotary kiln, is heated to a high temperature of about 800° C., and is supplied from the outer periphery of each burner.

By supplying this secondary air, the heavy oil ejected from the small-diameter burner among the large-diameter burners and small-diameter burners arranged alternately around it can be easily created into a relatively short flame because the oil droplets are fine. The jet of heavy oil that is combusted and ejected from the large-diameter burner is surrounded by a primary air surrounding flow with a large momentum, and the primary air surrounding flow of the large-diameter burner absorbs the high-temperature combustion gas generated by the combustion of the small-mouth burner. Since it is sucked into the heavy oil jet of the large-mouth burner, the heavy oil jetted out by the large-diameter burner first undergoes an endothermic gasification reaction with the high-temperature combustion gas. It is then combusted by air.

In this way, most of the heavy oil is ejected from a large-diameter burner, partially combusted, and then completely combusted by supplying high-temperature secondary air, and the resulting flame burns smoothly without creating an extremely high-temperature area. Therefore, the amount of NO produced is greatly reduced.

In addition, the primary air central flow causes the heavy oil jets of each burner to be injected in a direction away from the central axis, and in particular, the heavy oil jets of small diameter burners are first spread radially in the direction away from the central axis and come into contact with the secondary air. This facilitates quick combustion with a short flame. Next, the jets of the large-diameter burner are also slightly radially expanded in the direction from the central axis, and the formation of dense areas of heavy oil due to the intersection of adjacent heavy oil jets is completely eliminated, resulting in efficient combustion. The reduction in the amount of N○k generated by the combustion apparatus of the present invention is as shown in FIG.

Figure 7 shows the air ratio on the horizontal axis and the N in the combustion exhaust gas on the vertical axis.
The solid line indicates the amount of NOx generated by the combustion device of the present invention at each air ratio, and the N0x amount generated by the conventional combustion device with a structure of simply bundling a large number of burners at each air ratio.
The dotted line indicates the amount of ○k generated. As a result of experiments, it was confirmed that the combustion device of the present invention has less than half the amount of NOk compared to a combustion device with a conventional structure, and since it does not create a dense area of heavy oil, smooth combustion occurs and the combustion device has a good shape. flame can be obtained and thermal efficiency can be improved. Although the combustion device of the present invention is suitable for rotary kilns for burning cement, it can also be applied to general rotary kilns, reducing the amount of N0k generated, and creating a flame with a good shape for smooth combustion. The efficiency of the fuel can be increased because it is combusted.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 show the second part of the combustion apparatus according to the present invention, respectively.
They are a 1-1 section side sectional view and a front view seen from the combustion chamber side in the figure. Figures 3 and 4 show the low N0k first developed by the inventors.
They are a side sectional view and a front view of the combustion device as seen from the combustion chamber side, respectively. 5 and 6 are a side sectional view and a front view, respectively, of a combustion device developed by the present inventors for smooth combustion, as seen from the combustion chamber side. FIG. 7 is a graph showing a comparison of the amount of NOk generated at various air ratios between the combustion apparatus of the present invention and the conventional combustion apparatus. 1 is a blow pipe 2 is a primary air central flow supply passage 3 is a primary air ambient flow supply passage for a large-diameter burner 4 is a primary air ambient flow supply passage for a small-mouth burner 5 is a large-diameter heavy oil burner 6 is a small-diameter heavy oil In the burner 7, the blowing pipe tip face 8 has a primary air central flow jet hole 9. The primary air peripheral flow jet hole 10 of the large diameter burner has a large diameter.The primary air peripheral flow jet hole 11 of the diameter burner has a large diameter. The heavy oil spout hole 12 of the burner is a heavy oil spout hole of a small diameter burner. Figure 7 Figure 2 Figure 3 Figure 4 Figure 5 and 6 Figure 7 Figure 7

Claims (1)

[Claims] 1 The high-pressure primary air, which is about 10% of the theoretical air amount for the amount of heavy oil supplied to this combustion device, is divided into a central flow and a peripheral flow, and the central flow, which is the majority of the amount, is divided into the primary air central flow. The ambient flow, which is less than half of the other amount, is supplied to the supply channel 2 by dividing it into several large-diameter ambient flow supply channels 3, 3'... and several small-diameter ambient flow supply channels 4, 4'... This combustion device blow pipe 1
A primary air central flow supply passage 2 is provided in the central shaft portion, a primary air central flow jetting hole 8 is provided at the tip of the primary air central flow supply passage 2, and a primary air central flow jetting hole 8 is provided around the primary air central flow supply passage 2. Several large-diameter heavy oil burners 5, 5'... and several small-diameter heavy oil burners 6, 6' are arranged alternately, and these large-diameter heavy oil burners 5, 5'...
...A large-diameter heavy oil supply path is provided in the center of each of them, a large-diameter heavy oil jetting chip 11 is provided at the tip of each of the large-diameter heavy oil supply paths, and a large-diameter ambient flow is supplied around each of the large-diameter heavy oil supply paths. A passage 3 is provided, and a large diameter ambient flow jetting hole 9 is provided at the tip of each of the large diameter ambient flow supply passages 3, and each of these small diameter heavy oil burners 6 is provided with a small diameter heavy oil supply passage at the center thereof, and a small diameter heavy oil supply passage is provided at the center thereof. A small-diameter heavy oil jetting tip 12 is provided at each tip of the heavy oil supply path, a small-diameter ambient flow supply path 4 is provided around each of the small-diameter heavy oil supply paths, and a small-diameter fuel oil jetting tip 12 is provided at each tip of the small-diameter ambient flow supply path 4. It has a structure in which a peripheral flow jetting hole 10 is provided, and a large amount of secondary air is supplied from the outer periphery of these large diameter burners 5, 5'... and small diameter burners 6, 6'... after passing through a clinker box. Combustion device for rotary kiln.