JPS6319769B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distributor installed in a flow path for conveying pulverized coal from a pulverized coal machine to a pulverized coal burner in a pulverized coal-fired boiler.

In FIG. 1, coal is supplied from a coal storage tank (not shown) to a coal pulverizer 2 through a coal feed pipe 1, is pulverized, becomes a mixture with dry air 3, and is turned into a pulverized coal pipe 4.
burner 6 installed in the furnace 5 of the boiler,
7. Here, the burner 6 burns a mixture with a low concentration of pulverized coal, and the burner 7 burns a mixture with a high concentration of pulverized coal. This burner 6,
By combining 7 as shown in Figure 1, stable low NO _x combustion can be achieved. 8 is a distributor installed in the pulverized coal pipe at the burner inlet, which separates the air-fuel mixture flowing through the pulverized coal pipe 4 into two types of air-fuel mixture with different concentrations and amounts, and sends the mixture to burners 6 and 7. supply.

FIG. 2 shows the structure of a conventional distributor 8. In the case of this conventional type, a swirler blade 10 is attached to the distributor main body 9, and gives a swirling force to the air-fuel mixture 11 flowing in. The pulverized coal flows around the outer periphery of the distributor due to centrifugal force. Therefore, a mixture with a high concentration of pulverized coal flows through the branch pipe 12 connected to the outer periphery, and a mixture with a low concentration of pulverized coal flows through the branch pipe 13 connected to the center, so that two gas mixtures having a concentration difference flow. Can be separated into streams. Such conventional distributors have the following problems.

(1) The swirling blade 10 wears out, and the swirling force decreases, resulting in a decrease in distribution performance.

(2) Distribution/separation performance cannot be adjusted.

(3) When the distributor is arranged vertically, it is difficult to create a structure in which the rich mixture is taken out from the top and the lean mixture is taken out from the bottom.

In view of the above, the present invention has been made for the purpose of providing a distributor that has excellent wear resistance, allows adjustment of separation (concentration) and distribution, and allows easy connection of outlet pipes for either concentration or concentration. be. In order to achieve this objective, the present invention aims to extract pulverized coal from a pulverizer.
It consists of an inlet pipe that is connected to a pulverized coal pipe that conveys an air mixture, and a plurality of outlet pipes that are arranged in parallel with each other at intervals and inclined with respect to the axis of the inlet pipe.
The cross section of the pulverized coal flow path between the outlet pipes is made larger than the cross section of the pulverized coal flow path in the inlet pipe, and the inlet part of the inlet pipe is inclined at the same angle as the inclination angle of the outlet pipe with respect to the axis of the inlet pipe. a deflector block having a surface facing the pulverized coal flow path between the outlet pipes;
A distributor is provided which is coupled to a moving means for moving the deflector block axially of the inlet tube.

According to the distributor of the present invention, the flow of the air-fuel mixture within the distributor can be changed by moving the deflector block using the moving means. If it is placed near the inlet pipe, the flow will be bent at the outlet pipe near the inlet pipe, and a rich mixture containing a large amount of pulverized coal will enter this outlet pipe, while A lean mixture with a small amount of pulverized coal enters the outlet pipe, and conversely, if the deflector block is placed far from the inlet pipe, the flow will be bent at the part of the outlet pipe that is far from the inlet pipe, and the pulverized coal will flow. A rich mixture with a large amount of pulverized coal enters this outlet pipe, while a lean mixture with a small amount of pulverized coal enters the outlet pipe closer to the inlet pipe. In this way, by changing the flow of pulverized coal depending on the position of the deflector block,
Since the concentration of pulverized coal entering each outlet pipe can be adjusted, it can be adjusted to the optimum concentration depending on the operating conditions of the burner.

The present invention will be explained below based on an embodiment shown in FIGS. 3 and 4.

The pulverized coal pipe 21 is transformed from a circular shape to a square shape at 22 parts, and is connected to an inlet pipe 24 of a distributor 23 .
The distributor 23 further includes inclined outlet pipes 25, 26.
are installed at a distance from each other. The cross section of the flow path between the outlet tubes 25, 26 is larger than the cross section of the inlet tube 24. Further, a rich mixture air pipe 27 is connected to the outlet pipe 25, and a lean air mixture air pipe 28 is connected to the outlet pipe 26. Contrary to the pulverized coal pipe 21, the rich mixture air pipe 27 and the light mixture air pipe 28 are deformed from a square shape to a circular shape in 22 parts. A deflector block 29 is inserted into the distributor 23 and is connected to an operating handle 31 by a connecting rod 30. 32
is a sealing mechanism. The outlet pipes 25 and 26 are inclined with respect to the axial direction of the inlet pipe 24 at a derived angle θ that provides the highest separation performance with the lowest pressure loss. In this example, the deflector block 29 is an abbreviation of the flow path.
Although it accounts for 50%, the appropriate size and height can be selected depending on the density of pulverized coal required.

The shape of the deflector block 29 is such that its upstream side surface has an inclined surface having the same angle θ as the angle formed between the inlet pipe 24, the axis, and the outlet pipes 25 and 26. In this way, the upstream side of the deflector block 29 and the outlet pipe 2
By matching the inclination angles with 5 and 26, high separability can be obtained with minimum pressure loss.

As described above, the deflector block 29 is movable and its position can be moved using the operating handle 31. Deflector block 29 in Figure 3
When set to the lower position (the position where the lower surface of the deflector block 29 and the upper surface of the outlet pipe 25 match),
The concentration of the mixture flowing into the outlet pipe 25 can be maximized. Also, conversely, deflector block 2
9 to the upper position in Fig. 3, the outlet pipe 2
The concentration of the air-fuel mixture flowing into the fuel tank 5 can be made the thinnest. Furthermore, if an intermediate density is required, a deflector block 29 may be set, for example, at the middle position in FIG.

The fifth position depends on the setting position of the deflector block 29.
As shown in the figure, the concentration of the mixture flowing into the outlet pipe 25 can be adjusted, and the concentration and amount of the mixture flowing into each outlet pipe 25, 26 can be adjusted. The two types of burners can be supplied with a pulverized coal mixture having a concentration suitable for the fuel and operating conditions through the branch pipes 27 and 28.

Furthermore, the density of the branch pipes 27 and 28 can be changed using distributors having substantially the same shape, so that the arrangement of pulverized coal near the burner can be simplified and the required space can be minimized.

Note that since the shape of the deflector block 29 is simple, wear-resistant materials such as ceramics can be used, and maintenance (replacement frequency) of the distributor can be greatly reduced.

As described above, if the distributor of the present invention is adopted in the pulverized coal combustion system shown in FIG. 1, the following functions of the system can be fully exhibited.

That is, in FIG. 1, four pulverized coal pipes are derived from a pulverized coal machine 2 and connected to burners 6 and 7 provided at the four corners of a furnace 5. One pulverized coal machine 2 corresponds to the burner stages of burners 6 and 7, and each pulverized coal pipe is branched by a distributor into two pulverized coal pipes with different mixture concentrations at the burner inlet, and each pulverized coal pipe is divided into two pulverized coal pipes with different mixture concentrations. 6,7
is connected to.

If you are currently burning coal with poor combustibility, or if the load on the pulverizer is low and the air/pulverized coal ratio is high (low concentration), stable combustion of the pulverized coal at the burner mouth cannot be maintained. By increasing the air-fuel mixture concentration in one burner stage of the pair (burner 7 stage) and ensuring stable ignition and combustion of that burner, it is possible to stabilize the ignition and combustion of the burner as a whole. Further, by combusting such a mixture with different concentrations, the amount of NO _x produced can be reduced at the same time.

The example in Figure 1 shows a case where three pulverized coal machines, that is, six stages of burners are used, but the burner shading can be arranged from above to light-dark, dark-light, and light-dark. This makes it possible to further improve ignition stability and achieve low _NOx combustion compared to light-dark, light-dense, and light-dense burner arrangements.

Further, in the examples shown in FIGS. 3 and 4, only the movable deflector block 29 is shown, but if it is desired to increase the air-fuel mixture concentration in the outlet pipe 25, the sixth
This can be easily achieved by adding a fixed deflector block 29a to the inlet pipe 24, as shown in FIGS.

Furthermore, if it is necessary to increase the mixture concentration in the outlet pipe 25, as shown in FIGS. 8 and 9,
The movable deflector block 29b may be disposed close to the outlet pipe 24, and the fixed deflector block 29c may be disposed in a position opposite to that shown in FIGS. 6 and 7.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a pulverized coal combustion device, Fig. 2 is a cross-sectional view showing a conventional distributor, Fig. 3 is a cross-sectional view showing an embodiment of the present invention, and Fig. 4 is a - arrow in Fig. 3. 5 is a graph showing the change in air-fuel mixture concentration in the outlet pipe 24, FIG. 6 is a sectional view showing a modified example of the distributor, FIG. 7 is a view taken along the - arrow in FIG. 6, and FIG. 9 is a sectional view showing another modification of the distributor, and FIG. 9 is a view taken along the - arrow in FIG. 8. 21: Pulverized coal pipe, 23: Distributor, 24: Inlet pipe 24, 25, 26: Outlet pipe, 27: Concentrated mixture pipe 2
7, 28: Lean mixture trachea, 29, 29a, 29b,
29c: Deflector block, 30: Connecting rod, 3
1: Operation handle, 32: Seal mechanism.

Claims (1)

[Claims] 1. An inlet pipe connected to a pulverized coal pipe that conveys a pulverized coal/air mixture from a pulverized coal machine, and a plurality of outlet pipes installed in parallel with each other at intervals and inclined with respect to the axis of the inlet pipe. The cross section of the pulverized coal flow path between the outlet pipes is larger than the cross section of the pulverized coal flow path of the inlet pipe, and is at the same angle as the inclination angle of the outlet pipe with respect to the axis of the inlet pipe. A deflector block having a surface facing the inclined inlet portion of the inlet pipe is disposed in the pulverized coal flow path between the outlet pipes, and connected to a moving means for moving the deflector block in the axial direction of the inlet pipe. A distributor characterized by: