JPS599802B2 - Combustion method of pulverized coal burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a pulverized coal burner for a rotary kiln, in particular, the amount of primary air for transporting pulverized coal is zero or significantly reduced compared to the conventional method, and the amount of primary air is increased through a separate path within the burner. A combustion method for a pulverized coal burner that achieves good combustion by rapidly mixing high-temperature secondary air and pulverized coal by ejecting primary air containing no pulverized coal from the burner at high speed, and its combustion method. The present invention relates to a pulverized coal burner used in the method.

The conventional pulverized coal burner has three pulverized coals as shown in Figure 1.
and primary air 4 are directly fed into the burner body 1 formed of a refractory 2 etc., and the pulverized coal 3 and the primary air 4 are
In one method, pulverized coal 3 and primary air 4 are mixed in advance in a pulverized coal mixing chamber (not shown), and then the mixture is injected into the burner main body 1.
There was a method in which the mixture was injected from Burnaro 5 through the inside.

However, in all of these systems, in addition to the primary air 4 serving as a combustion source, pulverized coal is also used in a burner body 1 with a large diameter.
Since the mixture of primary air and pulverized coal itself is simultaneously injected from the burner rotor 5, a relatively large amount of primary air is required.

In addition, in the conventional method, the mixture of pulverized coal 3 and primary air 4 directly collides with the guide vanes 6 installed in the burner body 1, and in particular, in order to increase the combustion speed, the guide vanes are accelerated by increasing the air velocity of the mixture. However, it had the disadvantage that it would be damaged and become unusable after 3 to 4 months.

Furthermore, in the conventional method, the amount of primary air to burn pulverized coal is quite large, 20 to 25 yen of the theoretical combustion air amount, so the amount of hot secondary air used is reduced and the loss of thermal energy is reduced. there were.

In this way, the conventional primary air amount is 20 to 20% of the theoretical combustion air amount.
The reason for the 5% setting is that in addition to using primary air as a combustion air source, a relatively large amount of primary air is also used to transport pulverized coal to the burner port and for the purpose of diffusion when pulverized coal is injected from the burner. based on what was needed.

The inventor believes that the theoretical combustion air amount of pulverized coal depends on the total amount of primary air and secondary air, that the amount of secondary air can be supplied in large quantities from the product cooling device, and that the temperature of the secondary air is 80.
Since the temperature rises to 0 to 1000 degrees Celsius, we focused on the fact that by using a large amount of pulverized coal, we can effectively burn the burner. The primary air sent through another route is injected into the kiln from around the pulverized coal at a higher speed than before, and the kinetic energy of the primary air rapidly mixes the high temperature secondary air and the pulverized coal, resulting in a good production process. It is an object of the present invention to provide a combustion method for a pulverized coal burner that can obtain combustion.

SUMMARY OF THE INVENTION An object of the present invention is to transport pulverized coal by reducing the amount of primary air, which has a relatively low temperature, to zero or a very small amount. We aim to achieve thermally efficient combustion of pulverized coal in a rotary kiln.

Another object of the present invention is to feed primary air containing no pulverized coal for pulverized coal injection at high speed through a route separate from the transport of pulverized coal, and to reduce the total amount of primary air for injection to a smaller amount than before. By supplementing the theoretical amount of combustion air required for pulverized coal with high-temperature secondary air, we aim to achieve more sufficient combustion of pulverized coal in the rotary kiln.

As an embodiment of the present invention, a pulverized coal burner having two pulverized coal transport pipes will be described with reference to the accompanying drawings.

In the schematic cross-sectional view of the present invention according to FIGS. 2 and 3,
The burner body 7 has a portion inserted into the rotary kiln 22 covered with a refractory material 8, and a burner rod 9 whose tip is slightly constricted.

Inside the burner main body 7, there are two pulverized coal transport pipes 12 for transporting only the pulverized coal 11 by gravity from the rear of the burner main body 7, or for transporting pulverized coal and a small amount of primary air for transporting the pulverized coal.
is arranged at the axial center of the burner main body 7.

Also, around the pulverized coal transport pipe 12, there is a burner rod 9 at the tip.
A primary air supply pipe 14, which also serves as a cooling unit and which supplies air from the rear of the burner body 7 equipped with a cooling porous plate 13 for cooling the burner body 7, is integrally connected to the burner body 7 by extending from the rear part 10 of the burner to the burner rotor 9. It is equipped with.

Further, around the primary air inlet pipe 14 which also serves as a cooling device, there is a primary air inlet pipe 16 that sends air from the rear of the burner main body 7 to a larger size using a guide vane 15 provided at its tip to generate a swirling flow. Around the primary air inlet pipes 16, there are provided primary air inlet pipes 17 in multiple stages, which allow air to advance straight from the rear of the burner main body 7 to create a straight flow.

FIG. 4 is a schematic cross-sectional view of the inlet portion of the pulverized coal transport pipe 12 of FIG. 3 according to the present invention. Normally, the lid 20 is closed and the pulverized coal 11 is introduced from the pulverized coal inlet 18.

When using heavy oil, stop feeding the pulverized coal, remove the lid 20, and insert a known heavy oil burner gun (not shown) equipped with an atomizer at the tip of the pulverized coal transport pipe 12 from the heavy oil burner gun insertion port 19. Insert it inside and fix it at the position where the atomizer reaches the burner rotor 9.

In this case, when one pulverized coal transport pipe 12 is used, the burner burns only with heavy oil.

In addition, when using two pulverized coal transport pipes 12, put pulverized coal in one of the two pulverized coal transport pipes 12 and a heavy oil gun in the other to create a co-firing burner of pulverized coal and heavy oil. I can do it.

Of course, if the supply of pulverized coal is stopped and two dual heavy oil guns are inserted, it can be used as a heavy oil-only burner.

Next, a method of combustion using the pulverized coal burner according to the present invention will be explained.

First, pulverized coal containing the minimum amount of air necessary for transporting the pulverized coal is discharged from the burner rotor 9 through the pulverized coal transport pipe 12.

Discharging here refers to a state in which the pulverized coal is sufficient to come out from the pulverized coal transport pipe 12 (burner rotor 9).

At this time, in order to discharge the pulverized coal 11 into the kiln from the burner tube 9 which is also the tip of the pulverized coal transport pipe 12, it is also possible to tilt the pulverized coal transport pipe 12 and allow the pulverized coal to fall naturally by gravity. The pulverized coal is transported pneumatically by sending a small amount of primary air, which is normally required for transport, to the pulverized coal transport pipe 12.

The pulverized coal discharged from the burner rotor 9 is effectively transformed into pulverized coal in the kiln at the tip of the burner mouth by high-speed primary air that also serves as a cooling agent, primary air that creates a swirling flow, and primary air that creates a straight flow. The pulverized coal is mixed with air, and this is rapidly mixed with high-temperature secondary air to burn the pulverized coal.

Therefore, the relatively low-temperature primary air injected into the rotary kiln 22 minimizes the amount of primary air necessary for transporting the pulverized coal, and the primary air for injection is routed through a route different from the pulverized coal transport route. By using high-velocity injection, the total amount of primary air can be reduced to only 5-15% of the theoretical combustion air amount of pulverized coal, and the other required air is provided by the rotary kiln 22 for cooling the calcined minerals. The product is supplied by high-temperature secondary air of 800 to 1000° C. rising from a product cooling device 21 provided at the bottom of the device.

As a result, the amount of relatively low-temperature primary air that was conventionally used in large quantities can be reduced, and pulverized coal can be combusted with this reduced amount of air and high-temperature, yet sufficiently supplied, secondary air. Sensible heat of a certain secondary air can be used effectively.

In addition, according to conventional burners, the primary air mixed with pulverized coal is injected from the burner, which causes damage to the guide vanes due to collision of the pulverized coal, and to avoid damage, the speed of the primary air at the burner is reduced. The speed had to be limited to 50 to 70 m/s.

In the present invention, by making the supply of primary air and the transportation of pulverized coal take separate paths in the burner body, the velocity of the primary air at the burner can be increased from 100 to 150 m without considering damage to the guide vanes. Accordingly, pulverized coal with a higher concentration than the pulverized coal burner gun can be discharged to the burner for combustion.

Since there is no damage to the guide vanes, etc., it is possible to use the burner continuously for a long period of time, and this burner can be used even when the kiln itself has recently been operated continuously for a long period of time (for example, one year).

Furthermore, by lowering the velocity of the primary air at the burner port from 50 m/s to 150 m/s, the kinetic energy per unit amount of air increases nine times.

In the present invention, the amount of primary air per unit amount of pulverized coal is smaller than that of conventional burners, but the kinetic energy given to pulverized coal and secondary air is greater than that of conventional burners, and the injection and diffusion of pulverized coal by primary air and secondary air are mixed more effectively, making it possible to obtain good combustion with a much smaller amount of primary air than in conventional burners.

The present invention can also be used as a coal/heavy oil co-fired burner or a heavy oil-only burner, but in this case, it is not necessary to change the amount of primary air as long as the total calorific value per hour of the fuel used does not change.

This is because in the present invention, unlike the conventional pulverized coal burner, the proportion of primary air is the same as that in the heavy oil burner and is sufficient.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a conventional pulverized coal burner, FIG. 2 is an explanatory diagram of a pulverized coal combustion device, FIG. 3 is a schematic sectional view of a pulverized coal burner according to the present invention, and FIG. 4 is a schematic sectional view of a pulverized coal burner according to the present invention. is the third
It is a schematic sectional view of the entrance part of the pulverized coal transport pipe of the pulverized coal burner of the figure. 7... Burner body, 8... Refractory material,
9... Burner rotor, 10... Rear part of burner, 11... Pulverized coal, 12... Pulverized coal transport pipe, 13... Cooling Porous plate for use, 14.
...Primary air supply pipe for cooling, 15...
・Swirl vane, 16...Primary air inlet pipe that causes a swirling flow, 17...Primary air inlet pipe that causes a straight flow, 18...Pulverized coal inlet, 19...
Heavy oil burner gun insertion port, 20... Lid, 21.
...Product cooling device, 22...Rotary kiln.

Claims (1)

[Claims] 1 In this method, pulverized coal is injected into the kiln together with primary air using a rotary kiln burner, and the pulverized coal is burned by combining the primary air with hot secondary air sent from a product cooling device. The pulverized coal is discharged from the burner into the kiln, or the pulverized coal and a small amount of primary air necessary for transporting the pulverized coal are discharged from the burner into the kiln, and at the same time, the pulverized coal is sent through a route different from that for transporting the pulverized coal. Primary air that does not contain air is injected into the kiln from around the discharged pulverized coal at high speed, and the pulverized coal is substantially mixed with air in the kiln at the tip of the burner mouth, and the entire amount of the primary air is converted into theoretical combustion air. A combustion method for a pulverized coal burner, characterized in that pulverized coal is burned in a kiln in an amount of 5 to 15% of the amount of pulverized coal.