JPS63315805A - Method of feeding air for combustion - Google Patents

Abstract

PURPOSE:To improve a flow pattern within the furnace of the vertical combustion furnace apparatus by setting an after air port formed separately from the air feed short pipe on the ceiling wall at a portion closer to the central side of the furnace than the vertical burner, and by feeding a tertiary air flowing downward from the after air port. CONSTITUTION:At least one after air port, formed separating from an air feed short pipe 18 is set on the ceiling wall at a portion closer to the central side of a furnace 4 than a vertical burner 3 to be composed so that a tertiary air 13 flowing downward from the after air port 19 may be fed. Combustion air for fuel corresponded to the fuel character, namely an amount of a volatile matter within the pulverized coal in the ratio of 1 to 1 is fed from the vertical burner 3, and the remaining air for combustion, namely the tertiary air 13 fed by stages from a wind box 12 is separated to those on both sides of the air feed short pipe 18 and the after air port 19. Thus, a flow pattern of a flow of the pulverized coal within the furnace 4 can be changed by jetting the air current in a laminar condition from the after air port 19 to the vertical down- stream of the furnace 4.

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, anthracite, etc. as a fuel in floating combustion in the form of fine powder, the fuel has a high fixed carbon content and 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).
(See Publication No. 067). In other words, (1) Adoption of a vertical combustion method In order to secure the residence time in the furnace necessary for combustion, the furnace is shaped like a tractor, and the fuel is jetted vertically or nearly vertically downward from the shoulders of the furnace using multiple vertical burners. It burns, and the flame inside the furnace is used as 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 remarkable 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 weft 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 plurality of air supply short pipes 18 installed on the vertical wall around the combustion flame via a common wind box 12 according to the fuel properties. The coal flame 7 that burned together with the air 13 is in the furnace 4.
The combustion air rises in the center and reaches the superheater 9, and each combustion air is
It is controlled by the pulverized coal burner inlet damper 11 to open during vertical burner combustion and close when at rest.
Regarding the tertiary air 13, the air supply short pipe 18 remains open and the jet direction is fixed at the installation angle θ'=o'~30'', and the plurality of air supply short pipes 18 are of the same size, They were planned and manufactured with the same air volume.

[Problem that the invention seeks to solve]

The conventional technology lacks consideration for forming a flow pattern in the furnace for complete combustion of flame-retardant pulverized coal. That is, the combustion air supply, especially the air jet from the air supply short tube of the tertiary air, versus the pulverized coal jet from the vertical burner.

The mixture was mixed at an intersection angle of 75° to 45". As a result, the flow pattern in the furnace that governs the residence time in the furnace for vertical combustion could not be ensured sufficiently, and therefore the effective utilization rate of the furnace was 65". As shown in Figure 2, in flow pattern model tests, the pulverized coal flow was affected by the tertiary air flow from the air supply short pipe. There was a short bus 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 to be ejected downward from a vertical burner provided on the ceiling wall of a furnace and combusted together with secondary air, and the combustion flames connected to the ceiling wall to be combusted. Tertiary air is supplied in stages along the combustion process from multiple air supply short pipes installed on the vertical wall of the vertical combustion furnace, and the coal flame that burns with the tertiary air rises in the center of the furnace and reaches the superheater. In the combustion air supply method,
At least one after-air port configured separately from the air supply short pipe is arranged on the ceiling wall closer to the center of the furnace than the vertical burner, and is configured to supply downward-flowing tertiary air from the after-air port. .

[Effect]

According to the present invention, tertiary air is supplied in a downward flow by arranging an after-air port in which a part of the air supply short pipe is separated on the ceiling wall of the furnace of the vertical combustion furnace apparatus, and one coal flame is It works to prevent the water from turning and flowing to the furnace outlet. Therefore, the coal flame flows downward in the furnace where there is no ejected fluid, and the residence time in the furnace increases.

〔Example〕

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

As shown in Fig. 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 to a furnace. The fuel is ejected from the vertical burner 3 installed on the ceiling wall of No. 4 and combusts. That is, a stabilizing heavy oil burner 5, which has 10 to 30% of the total human heat 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 furnace atmosphere temperature. The coal is ignited, forms a coal flame 7, and burns. Tertiary air 13 is supplied in stages along the combustion process from a plurality of air supply short pipes 18 installed on the vertical wall around the combustion flame connected to the ceiling wall, and the coal flame 7 that has burned with the tertiary air 13 is sent to the furnace. 4 In a vertical combustion furnace device that rises up the center and reaches the superheater 9, the air supply short pipe 18
At least one after-air port 19 formed separately from the vertical burner 3 is arranged on the ceiling wall closer to the center of the furnace 4, and is configured to supply downward-flowing tertiary air 13 from the after-air port 19. ing.

In other words, the feature of the present invention is that an amount of combustion air corresponding to the fuel properties, that is, the amount of volatile matter in pulverized coal, in a 1:1 ratio is input from the vertical burner 3, and the remaining combustion air, that is, the amount of combustion air is input in stages from the wind box 12. The tertiary air 13 is supplied to the air supply short pipe 18.
The flow pattern of the pulverized coal flow (or coal flame 7) in the furnace 4 is controlled by separating the air flow into the side and the after air port 19 side, and ejecting the air flow vertically downstream of the furnace 4 in a layered manner from the after air port 19. It is made so that it can be changed.

The after air port 19 is 1 as shown in FIG. 1b.
For example, four ports are arranged in parallel in a line facing two vertical burners 3, and one stable burner 5 having a stable burner throat 21 is arranged opposite to the vertical burners 3. It is configured.

To provide a supplementary explanation of the structure shown in FIG. The heavy oil flame 6 generated by the burner 5 is ignited to become a coal flame 7 and burn. Air supply short pipe 18 and after air port 19
A wind box 12 is provided surrounding the air box 12, and an inlet damper 11 dedicated to the secondary air 14 and an air passage are installed inside the upper wall of the wind box 12. On the other hand, a partition plate 17 is fixed in the center of the wind box 12, dividing the air chamber leading to the short air supply pipe 18 and the after air port 19, and piping for introducing tertiary air 13 into each chamber is installed. Connected. The inner surface of the furnace 4 is surrounded by casters 8, and the furnace 4 is surrounded by casters 8.
The coal flame 7 rising in the center reaches the superheater 9, and
The ash after combustion is collected in the ash processing hopper 10.

A second embodiment of the invention will be described with reference to FIG. 1a.

As shown in FIG. 1a, an adjustment damper 20 is provided at the inlet of one of the piping for supplying the tertiary air 13 to each room that flows through the air supply short pipe 18 and the after-air port 19. Adjustment damper 2
By adjusting the amount of tertiary air at 0, the flow rate and flow velocity from the after air port 19 can be adjusted.
By arranging three stages, or four or more stages in some cases, the flow rate and flow velocity can be similarly adjusted, and the flow pattern of the coal flame 7 can be optimized.

〔Effect of the invention〕

According to the present invention, the tertiary air is separated and supplied as a downward flow from the after air port provided on the ceiling wall of the furnace of the vertical combustion furnace apparatus, so that the pulverized coal flow is sandwiched by the secondary air from the air supply short pipe. The improved interposition and flow pattern improves the mixing of fuel and combustion air, improving combustion efficiency.

[Brief explanation of the drawing]

FIG. 1a is a cross-sectional view showing the first and second embodiments of the present invention, FIG. 1b is a partially enlarged view of FIG. 1a, FIG. 2 is a cross-sectional view showing the flow pattern of the prior art, and FIG. The figure is a sectional view showing the prior art, and FIG. 3b is a partially enlarged sectional view of FIG. 3a. 1...Pulverized coal, 3...Vertical burner, 4.
... Furnace, 7... Coal flame, 9... Superheater, 13... Tertiary air. 14...Secondary air, 18...Air supply short pipe,
19...After Airport.

Claims (2)

[Claims] (1) Pulverized coal carried by primary air is ejected downward from a vertical burner installed on the ceiling wall of the furnace and combusted together with secondary air. Combustion air supply method for a vertical combustion furnace apparatus in which tertiary air is supplied stepwise along the combustion process from a plurality of air supply short pipes, and the coal flame burned together with the tertiary air rises in the center of the furnace and reaches a superheater. At least one after-air port formed separately from the air supply short pipe is arranged on the ceiling wall on the central side of the furnace from the vertical burner, and downward-flowing tertiary air is supplied from the after-air port. A combustion air supply method characterized by: (2) Combustion air supply according to claim 1, characterized in that an adjustment damper for adjusting the flow rate of tertiary air is provided on either one of the pipes connected to each of the air supply short pipe and the after air port. Law.