JPS6140851A - Vertical burning furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (1) Purpose of the Invention (Field of Industrial Application) This invention is a field in which raw lime or dolomite or clay (hereinafter referred to as "raw stone") is fired to obtain fired products such as quicklime. In particular, it relates to a vertical kiln for firing the kiln.

(Prior Art) The applicant has proposed a vertical lime kiln disclosed in, for example, Japanese Patent Publication No. 58-32307.

This kiln can efficiently produce quicklime, etc., but there is still room for improvement in terms of heat exchange with raw stone based on the convection of flames within the combustion chamber. In FIG. 1 of the above-mentioned publication, the downward flame generated by the burner 14 merges with the high-temperature gas injected from the air injection nozzle pipe 40, flows into the firing zone and the ripening zone, and exchanges heat with the object to be heated. . However, since the gas flow rate flowing into the raw stone is low, there is little heat exchange through convection heat transfer with the raw stone in the firing zone and ripening zone exposed in the combustion chamber, which has a considerable effect on thermal efficiency.

(Problems to be Solved by the Invention) The present invention attempts to solve the above-mentioned conventional problems by creating a vortex flow of high-temperature gas in the combustion chamber, thereby reducing the surface layer of the rough stone exposed in the combustion chamber. To provide a kiln which can improve the aging effect by sufficiently contacting a high-temperature gas in a combustion chamber.

(2) Structure of the Invention (Means for Solving the Problems) The present invention, as a means to solve the above-mentioned problems, consists of a vertical furnace body and a furnace lid with burners attached downward. In a firing furnace, the space is divided from above into a preheating zone, an upper firing zone (corresponding to the firing zone in the above publication), a combustion chamber, a lower firing zone (corresponding to the ripening zone in the above publication), and a cooling zone. A space is formed between the step-shaped hearth provided at the upper part of the periphery and the furnace lid, and the space is communicated with the raw stone supply port and the exhaust port to temporarily retain the supplied raw stone, and the raw stone supply side of the space is The preheating zone and the inner combustion chamber side are used as the upper firing zone,
A nozzle structure supported by support beams extending radially inward from the inner wall of the furnace body is disposed at a central position within the furnace body, and a vertical nozzle penetrating vertically is provided in the center of the nozzle structure. The inside of the vertical nozzle is equipped with an ejector that blows air upward from outside the furnace. The layer below the lower firing zone and up to the outlet provided at the bottom of the furnace body is the cooling zone, and a horizontal nozzle that blows out air with a circumferential component is installed on the furnace inner wall at the upper height of the nozzle structure. A circulation path is provided that communicates the horizontal nozzle with a space directly below the support beam, and the outlet of the branch pipe of the ejector is disposed within the horizontal nozzle.

If a part of the circulation path is formed into a nozzle shape, and a discharge port of a second branch pipe further separated from the branch pipe is arranged inside the nozzle, the flow in the circulation path is further improved.

(Function) Next, we will explain how raw stone such as lime is fired in the kiln of the present invention having the above configuration, and how it works)
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The rough stone is supplied from the supply port that leads to the space between the furnace lid and the upper end of the furnace body, and is temporarily retained in the hearth.The raw stone is used in the preheating zone on the supply port side, and the upper firing stage where the primary firing is performed on the combustion chamber side. forming a belt.

In addition, the above-mentioned sub-fired raw stone falls and accumulates in the lower part of the furnace, and the upper layer reaches a position slightly above the support beam of the nozzle structure, forming a lower firing zone near the nozzle structure and further. A cooling zone is formed in the lower layer.

The raw stone is fired by supplying the raw stone into a furnace and igniting a burner within the furnace.

When the burner is ignited, its flame spreads downward within the combustion chamber. The high-temperature gas in the combustion chamber is sequentially exhausted from the exhaust ports located above and around the combustion chamber. Further, the ejector in the vertical nozzle of the nozzle structure introduces air from the outside and ejects it upward at high speed within the vertical nozzle. This creates a suction force at the lower inlet of the vertical nozzle, so that the hot gases in the combustion chamber are drawn from the upper surface of the lower firing zone, pass through the lower firing zone, reach the space directly below the support beam, and then vertically It is pulled upward through the nozzle. That is, a vertical circulation flow is generated inside and outside the nozzle structure. The hot gas supplies a large amount of heat to the lower firing zone as it passes through the lower firing zone. The amount of air flowing from the product outlet at the bottom of the furnace body is the minimum amount necessary for cooling the lime, and is determined by a combination of the ventilation resistance of the cooling zone and the length of the cooling zone.

Further, since the air is ejected at high speed into the circulation path from the branch pipe separated from the ejector, the high-temperature gas that has passed through the lower firing zone from the combustion chamber is pulled and ejected from the horizontal nozzle.

Since the horizontal nozzle is installed within the combustion chamber with a component in the inner circumferential direction, its jet flow generates a vortex flow within the combustion chamber.

In other words, the vortex flow generated by the horizontal nozzle first causes a large rotating flow in the horizontal plane at the bottom of the combustion chamber, and as the high-temperature gas in the combustion chamber rises due to suction from the exhaust port,
The rotational flow extends to the upper part, resulting in a rotational flow throughout the combustion chamber.

Moreover, the high temperature gas in the vicinity of the upper part of the nozzle structure descends toward the space directly below the support beam due to the above-mentioned circulation path, so that the circulation flow by the vertical nozzle described above is further promoted.

In this state, the raw ore remaining in the hearth is preheated in the preheating zone (supply port side) by the heat generated when the high-temperature gas in the combustion chamber passes through the retained ore and is exhausted.
Further, in the upper firing zone (combustion chamber side), it is primarily fired by direct contact with the above-mentioned high-temperature gas, and then sequentially falls to the lower firing zone. Then, secondary firing, that is, ripening, proceeds in the lower firing zone. The upper surface of the deposited rough stones faces the combustion chamber,
Because of the exposure to the above-mentioned vortex flow, and as mentioned above, due to the circulating flow, the high temperature gas near the surface layer of the lower firing zone passes through the rough stone in the lower firing zone and reaches the space directly below the support beam.
Extremely efficient heat exchange is performed with the high temperature air, making aging effective. As the aged and fired product descends, it is sequentially cooled by air entering from a product outlet provided at the bottom of the furnace body, and is taken out as a product from the outlet.

In addition, even if the raw stone that falls to the bottom of the furnace body reaches the top of the support beam, a certain amount of space is always maintained directly under the support beam due to the property of the so-called repose angle of the raw stone, and this space communicates with the bottom of the vertical nozzle. Therefore, the circulation flow path is not blocked.

(Example) Embodiments of the present invention not shown in the drawings will be described below.

FIG. 1 is a longitudinal sectional view of the firing furnace of this embodiment, and 1 is a vertical furnace body made of bricks fixed with steel plates. The furnace body 1 has a cylindrical upper part and a conical lower part.

A furnace lid 13 is fixed above the furnace main body 1 with a certain space formed between it and the upper end of the furnace main body 1. A burner 14 and a primary combustion air supply pipe 14a are disposed substantially in the center of the furnace lid, facing downward toward the combustion chamber 1).

A hearth portion 15 is formed at the upper end of the furnace body, in which the rough stone 90 supplied to the space between the furnace lid and the furnace lid is temporarily retained. The raw ore in the hearth section 15 forms a preheating zone A on the supply pipe 14a side and a primary firing zone B on the combustion chamber 1) side.

Further, a divine rod 16 is arranged in the space, which intermittently enters from outside the furnace and causes the rough stones 90 to fall.

The above space has an annular shape, and there is a raw stone supply pipe 1 at the top.
A lid body 17 is provided to which an exhaust pipe 19 from an exhaust system (not shown) is connected.

A nozzle structure 20 is supported at approximately the center of the furnace body 1 by a plurality of support beams 22 that extend horizontally radially inward from the inner wall of the furnace body 1 . This nozzle structure 20
Like the furnace body 1, it is made by stacking bricks, and a vertical nozzle 21 is formed in the center thereof, and an ejector 23 is disposed at a lower position of the nozzle.

The ejector 23 is connected to a pipe 24 introducing compressed air from the outside at the lower part of the furnace body, and is connected to an annular passage 25 in the nozzle structure 20 so that the air is heated to a high temperature when ejected from the ejector 23. It is via.

The raw stone falls from the above-mentioned primary firing zone B to the lower part of the furnace main body, and its upper surface reaches the upper part of the periphery of the nozzle structure 20. Directly below the nozzle structure 20 and the support beam 22 supporting it is a space 40 due to a so-called angle of repose α (see FIG. 2). (Thus, the raw stone forms a lower firing zone C between the upper surface and the space directly below the support beam, and the area below that is a cooling zone.

On the inner peripheral wall of the furnace body 1 at the upper position of the nozzle structure 20,
Horizontal nozzles $1 having circumferential components are provided inwardly at a plurality of locations (see FIG. 3). The horizontal nozzle 31
is connected to a circulation path 32 that communicates with a space 40 directly below the support beam 22 . In this embodiment, the circulation path 32 is also formed in a nozzle shape. At the inlet of the horizontal nozzle 31, there is disposed a discharge port 33a of a branch pipe 33 which branches off from the annular passage 25 leading to the ejector 23, and within the nozzle-shaped circulation passage 32 there is a second branch pipe 33 which branches off from the branch pipe 33. A discharge port 33b of a branch pipe is provided.

The lower end of the furnace body 1 is an outlet 50 provided with a rotary scraping member 51 for taking out the product.

The furnace body 1 is supported by wheels 60 at its outer periphery at its center height so that the furnace body 1 can be selectively rotated for the purpose of uniform firing. During this rotation, the furnace body 1 has a furnace lid 13 at its upper end and a bottom body 55 at its lower end.
It is designed so that it can be separated and rotated independently. Therefore, water seal tanks 71 and 72 are formed at the upper end and the F end to prevent the gas in the furnace from flowing out.

In the firing furnace of this embodiment having the above configuration, raw stone is fired in the following manner.

■ First, the burner 14 is ignited, and its flame enters the combustion chamber 1.
) and spreads downward within it.

(2) Compressed air introduced from the outside via the pipe 24 is heated to a high temperature via the annular path 25 of the nozzle structure 20, and is ejected from the ejector 23 into the vertical nozzle 21 at high speed.

Attracted by this upward high-speed jet, the nozzle structure 20
At the outer periphery of the nozzle 21, the high-temperature gas on the upper surface of the lower firing zone C is sucked downward, creating a circulating flow that reaches the lower inlet of the nozzle 21 through the space 40 directly below the support beam. When this circulating flow of high-temperature gas passes through the lower firing zone C, the raw ore in the lower firing zone C is aged.

■ On the other hand, the high temperature air coming out of the annular path 25 is
3, part of the water is ejected from the outlet 33a of the branch pipe in the horizontal nozzle 31, and the other part is ejected from the outlet 33b of the second branch pipe in the circulation path 32. The high-speed jet jet ejected from the discharge port 33a in the horizontal nozzle 31 is transferred to the vertical nozzle 2.
As in case 1), a large amount of air sucked in from the space 40 directly below the support beam 22 is sent out in the circumferential direction within the combustion chamber 11 to generate a vortex flow within the combustion chamber 1). This vortex is
Combined with the upward flow associated with the exhaust, it spreads throughout the combustion chamber.

Furthermore, the high-speed jet jets ejected from the discharge ports 33b of other branch pipes act in the same manner, promoting the flow within the circulation path 32.

Furthermore, the flow in the circulation path 32 causes the high-temperature gas above the support beam 22 to descend to the space 40 directly below the support beam 22 and reach the circulation path 32, thus promoting the circulation flow in (3) and reducing the aging effect. Improve further.

(2) Thereafter, the aged lime, etc. is cooled by secondary air as it descends within the cooling zone, and is taken out as a product from the outlet 50 provided at the bottom of the furnace body 1.

(3) Effects of the invention The present invention is as described above and has the following effects.

■ Since a vortex of high-temperature gas is generated in the combustion chamber, contact with the surface layer of the lower firing zone becomes active, and highly efficient heat exchange is performed, which improves the aging effect.

■ The rising exhaust gas and vortex flow combine to cause the high-temperature gas in the combustion chamber to generate a rotating flow throughout the combustion chamber, and heat exchange becomes active even in the upper firing zone.

(2) By providing the circulation path, the high-temperature gas in the surface layer of the lower firing zone passes through the lower firing zone and reaches the space directly below the support beam, so that a large amount of heat is exchanged and ripening is promoted.

■ As described above, heat exchange can be made extremely efficient, so baked products such as quicklime can be obtained with high efficiency, and the products are of high quality.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of a vertical lime kiln according to an embodiment of the present invention, Fig. 2 is a sectional view taken along nn in Fig. 1, and Fig. 3 is a sectional view taken along m-m in Fig. 1.
FIG. 1... Furnace body 1) Combustion chamber 13 Furnace lid 14 Burner 15 ...Heart part 20 ...Nozzle structure 21 ... Vertical nozzle 22 ... Support beam 23 ......Ejector 31...Horizontal nozzle 32...Circulation path 33...Diversion pipe A...・・・・・・Pre-heating zone B・・・・・・Upper baking zone C・・・・・・Lower baking zone D・・・・・・・・・Cooling zone

Claims (2)

[Claims] (1) In a firing furnace in which the space formed by the vertical furnace body and the furnace lid with burners mounted downward is divided into a preheating zone, an upper firing zone, a combustion chamber, a lower firing zone, and a cooling zone from above. , A space is formed between the stepped hearth part provided at the upper part of the periphery of the furnace body and the furnace lid, and the space is communicated with the raw rock supply port and the exhaust port to temporarily retain the supplied raw rock. The raw ore supply side is a pre-heating zone, and the inner combustion chamber side is an upper firing zone, and a nozzle structure supported by a support beam extending radially inward from the inner wall of the furnace body is located at the center of the furnace body. A vertical nozzle penetrating vertically is provided in the center of the nozzle structure, and an ejector is provided inside the vertical nozzle to eject air from outside the furnace upward, and the air falls from the upper firing zone through the combustion chamber. The layer above the support beam of the raw ores accumulated near the nozzle structure is the lower firing zone, and the layer below the lower firing zone up to the outlet provided at the bottom of the furnace body is the cooling zone. A horizontal nozzle that blows out air with a circumferential component is installed on the inner wall of the furnace at the position, a circulation path is provided that communicates the horizontal nozzle with the space directly below the support beam, and the flow pipe of the ejector is installed in the horizontal nozzle. A vertical kiln characterized by having a discharge port. (2) A part of the circulation path is formed into a nozzle shape, and a discharge port of a second branch pipe that is further separated from the branch pipe is arranged inside the nozzle shape. Vertical firing furnace.