JPS63315804A - Method of feeding air for combustion - Google Patents

Abstract

PURPOSE:To improve a flow pattern within the furnace of the vertical combustion furnace apparatus and elevate an efficiency of combustion by making a fixing angle of the air feed short pipe approximate to an angle of a hopper of the fire bed, and by setting a guide vane to adjust the flow rate and the angle of the air current within an each air feed short pipe. CONSTITUTION:A fixing angle formed between a horizontal line and an air feed short pipe 18 is approximated to the hopper angle alpha=50 deg.-55 deg. of the fire bed, to be set to 45 deg., and simultaneously a guide vane 19 is set inside an each air feed short pipe 18 to adjust a flow rate of the air current and its angle. The tertiary air 13 and 13' fed by stages from a wind box 12 causing them to correspond to a fuel character, namely to an amount of volatile matter within the pulverized coal in the ratio of 1 to 1 is allowed to change a flow pattern of a flow of the pulverized coal within the furnace by setting the fixing angle of the air feed short pipe 18 to about 45 deg. and by adjusting an angle of the built-in guide vane 19 by + or -15 deg..

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to the highly efficient combustion of flame-retardant low bituminous coal, semi-anthracite coal, and anthracite coal, and particularly to the combustion of vertical combustion furnace equipment for stable combustion. related to air supply methods.

[Conventional technology]

In boilers that use semi-anthracite coal, anthracite coal, etc. as a floating combustion fuel, the fuel contains a lot of fixed carbon and has a low volatile content. In order to complete combustion, consideration has been given to increasing the necessary residence time in the furnace (see Utility Model Application No. 61-135120 and Japanese Patent Application Laid-Open No. 61-288).
(Refer to Publication No. 067), that is, (1) Adoption of a vertical combustion method In order to secure the residence time in the furnace necessary for combustion, the furnace shape is a tractor type, and multiple vertical burners are installed from the shoulder of the furnace to distribute fuel vertically or vertically. It burns by ejecting it downwards, and the flame inside the furnace forms a W-shaped flame to ensure residence time.

(2) Increase fine particle size and concentration.

(3) By constructing a heat insulating material on the surface of the water-cooled wall of the burner zone inside the furnace, the atmospheric temperature in the burner zone is raised, which not only increases the combustion efficiency but also promotes ignitability.

(4) Combustion air is divided into secondary air, which is supplied from a vertical burner according to the volatile content, and tertiary air, which is staged combustion air that is tailored to char combustion. The amount is minimized to raise the theoretical combustion temperature and contribute to ignition flame stability.

(5) Flame stabilization is carried out by constantly adding a small amount of auxiliary combustion fuel with excellent ignitability, such as heavy oil.

A method based on the above outline has been adopted.

As shown in FIG. 3a, pulverized coal 1 with a low volatile content conveyed by primary air is ejected from a vertical burner 3 provided on the ceiling wall of a furnace 4 and combusted together with secondary air. A stable heavy oil burner 5 containing 10 to 30% of the total heat input of the furnace 4 is installed very close to the vertical burner 3, and the pulverized coal particles are heated and ignited by the radiant heat of the stable burner flame 6 and the furnace atmosphere temperature. to form a coal flame 7. Further, depending on the volatile content, the stable burner 5 may not be used and pulverized coal may be burned exclusively. Since these flames 6 and 7 are ejected downward, they form a W-shaped frame under the influence of the flow within the furnace.

On the other hand, the combustion air includes primary air for transporting pulverized coal, secondary air 14 jetting downward from the periphery of the vertical burner 3,
Tertiary air 13 is supplied in stages along the combustion process from a common wind box 12 according to the fuel properties via a plurality of air supply short pipes 18 provided on the vertical wall directly below the flame, and is connected to the vertical wall. In a vertical combustion furnace apparatus having a hopper hearth, each combustion air is controlled to be opened by a pulverized coal burner inlet damper 11 during vertical burner combustion and closed during rest, and tertiary air 13 is controlled by an air inlet damper 11. The supply short pipe 18 remains open and the jet flow direction is fixed at the installation angle θ = 0° to 30°, and the plurality of air supply short pipes 18 are planned and manufactured with the same size and the same air volume. Ta.

[Problem that the invention seeks to solve]

Conventional technology lacks consideration for forming a flow pattern in the furnace for complete combustion of flame-retardant pulverized coal, and the supply of combustion air, especially the supply of tertiary air, is limited to that from the vertical burner. There were problems such as not having a one-to-one correspondence with the supply of pulverized coal. That is, a sufficient flow pattern in the furnace that governs the residence time in the furnace during vertical combustion cannot be ensured, and therefore, the effective utilization rate of the furnace is as low as 65 to 70%, and the combustion efficiency is accordingly deteriorated. As shown in Fig. 2, in the flow pattern model test, the pulverized coal flow was affected by the tertiary air flow from the air supply short pipe, resulting in a short path inside the furnace.

An object of the present invention is to provide a combustion air supply method that improves the flow pattern in the furnace of a vertical combustion furnace apparatus to increase combustion efficiency and increase the effective utilization rate of the furnace.

[Means for solving problems]

In order to achieve the above object, the present invention provides pulverized coal conveyed by primary air, which is ejected downward from a vertical burner provided on the ceiling wall of a furnace and burned together with secondary air, and is provided on a vertical wall directly below the flame. In the combustion air supply method for a vertical combustion furnace device that has a hopper furnace where tertiary air is supplied stepwise along the combustion process from multiple short air supply pipes and is connected to a vertical wall, the installation angle of the short air supply pipes is It is configured to approximate the furnace hearth hopper angle and to provide guide vanes inside each air supply short pipe to adjust the flow rate and angle of the air flow.

[Effect]

According to the present invention, the installation angle of the short air supply pipe of the vertical combustion furnace apparatus is approximated to the furnace hopper angle, and.

By adjusting the built-in guide vanes, the supplied tertiary air creates a winding flow as the jet develops within the furnace, and the pulverized coal flow is drawn downward along the flow pattern, so that the inside of the furnace is As the residence time increases, tertiary air is supplied in stages to promote proper mixing with the fuel.

〔Example〕

A first embodiment of the present invention will be described with reference to FIGS. 1a and 1b.

As shown in Figure 1a, pulverized coal 1 with a low volatile content consisting of bituminous coal, semi-anthracite and anthracite with a fuel ratio (fixed carbon/volatile content) of 4.0 to 14 is conveyed by primary air. It is ejected from the vertical burner 3 provided on the ceiling wall of the furnace 4 and combusted together with the secondary air 14. That is, a stable burner 5 of heavy oil containing 10 to 30% of the total human calorific value of the furnace 4 is installed very close to the vertical burner 3, and the pulverized coal particles are heated by the radiant heat of the stable burner flame 6 and the atmosphere temperature inside the furnace. The coal is heated and ignited to form a coal flame 7 and burn. Tertiary air 13 is supplied stepwise along the combustion process from a plurality of air supply short pipes 18 provided on the vertical wall directly below the flame, and the combustion air is supplied to a vertical combustion furnace apparatus having a hopper furnace connected to the vertical wall. In the method, the installation angle θ between the air supply short pipes 18 and the horizontal line is approximated to the furnace hopper angle α = 50” to 55”, which is 45°, and the air flow inside each air supply short pipe 18 is set to 45°. This configuration includes guide vanes 19 that adjust the flow rate and angle.

In other words, the feature of the present invention is that the tertiary air 13 and 13', which is supplied in stages from the wind box 12 in a one-to-one correspondence with the fuel properties, that is, the amount of volatile matter in the pulverized coal, is The installation angle is based on 45 degrees, and the flow pattern of pulverized coal in the furnace can be changed by adjusting the angle of the built-in guide vanes 19 by ±15''.

A second embodiment of the invention will be described with reference to FIGS. 1a and 1b.

As shown in FIG. 1a, the air supply short pipes 18 are arranged in two to three stages in the height direction of the furnace ice wall, and in some cases four or more stages, and also in the furnace width direction, in three to three stages for each of the three vertical burners. Since four rows are provided, by adjusting each guide vane 19, it is possible to adjust not only the direction of the air flow but also the flow rate passing through each short air supply pipe.

The air supply short pipe 18 arranged in the furnace width direction is divided into 18' and 18' as shown in Fig. 1b. 01. It has a guide vane 19 that can be adjusted to θ2,
The air supply short pipe 18', which is placed slightly away from the center of the vertical burner 3, is adjusted to the right, and the guide vane 19, which can be adjusted to the left, is installed so as to enclose the flame. within the scope of the invention.

In this way, the optimal arrangement of the air supply short pipes with built-in adjustable guide vanes, the jet flow effect with increased flow velocity, and adjustment of the ejection direction promote appropriate mixing of fuel and combustion air within the furnace. The flow pattern is, for example, 1a
As shown in the figure, it is now possible to reach deep into the furnace in the vertical direction, increasing residence time in the furnace, increasing the effective utilization rate of the furnace, and increasing combustion efficiency.

In addition, to supplement the structural explanation with respect to FIG. is ignited by the heavy oil flame 6 generated by the coal to become a coal flame 7 and burn. A wind box 12 is provided above the furnace 4, and an inlet damper 11 for secondary air 14 is fixed inside the earthen wall of the wind box 12. The inner surface of the water-cooled wall 17 of the furnace 4 is equipped with casters 8.
A plurality of air supply short pipes 18 for supplying tertiary air 13 are provided on the vertical wall thereof at an installation angle θ. This air flow forms a flow pattern of coal flame 7 leading to superheater 9 . On the other hand, the ash after combustion is collected in the ash processing hopper 10.

〔Effect of the invention〕

According to the present invention, the installation angle of the air supply short pipe on the vertical wall of the furnace of a vertical combustion furnace device is approximated to the furnace hopper angle, and the built-in guide vanes are adjusted to change the flow rate and jetting angle of tertiary air. This makes it possible to improve the flow pattern within the furnace and increase combustion efficiency.

[Brief explanation of drawings]

FIG. 1a is a sectional view of a furnace showing a first embodiment of the present invention, FIG. 1b is a partially enlarged sectional view of FIG. 1a, FIG. 2 is a sectional view showing a flow pattern of a conventional furnace, and FIG. The figure is a sectional view of a conventional furnace, and FIG. 3b is a partially enlarged sectional view of FIG. 3a. 1...Pulverized coal, 3...Vertical burner, 4.
...furnace, 7...coal flame, 13...
Tertiary air, 14... Secondary air, 18... Air supply short pipe, 19... Guide vane. θ: Installation angle, α: Fire hearth hopper angle.

Claims (2)

[Claims] (1) Pulverized coal conveyed by primary air is ejected from a vertical burner installed on the ceiling wall of the furnace and combusted together with secondary air, and is gradually distributed through multiple air supply short pipes installed on the vertical wall directly below the flame. In a combustion air supply method for a vertical combustion furnace apparatus having a hopper furnace connected to the vertical wall to which tertiary air is supplied along the combustion process, the installation angle of the air supply short pipe is approximated to the furnace hopper angle, and A combustion air supply method characterized in that a guide vane for adjusting the flow rate and angle of the air flow is provided inside each of the short air supply pipes. (2) Provide tertiary air that envelops the flame by arranging multiple stages of air supply short pipes in the height direction and changing the installation angle of each, and by providing multiple rows in the width direction of the furnace and adjusting each guide vane. A combustion air supply method according to claim 1, characterized in that: