JP4679612B2 - Combustion gas discharge chimney - Google Patents

Description

  The present invention relates to a structure of an exit part of a chimney (hereinafter referred to as “combustible gas discharge chimney”) that combusts combustible gas and releases it to the atmosphere. Forming an outlet channel with a cross-sectional area corresponding to the flow rate and releasing exhaust gas to the atmosphere with a sufficient outflow rate, prevents the core from overheating due to the combustion heat of the exhaust gas at the smoke outlet, and its heat resistance Property and durability can be improved.

When exhaust gas having a relatively high CO gas concentration is diffused into the atmosphere, such as a non-combustion converter exhaust gas treatment apparatus, the CO gas is burned at the top of the chimney and is diffused into the atmosphere as harmless CO ₂ gas. In this way, in the chimney that emits exhaust gas, if the exhaust gas flow rate at the smoke outlet decreases when the amount of exhaust gas from the exhaust gas generation source is small, disadvantageous phenomena such as backfire to the CO gas in the chimney and downwash occur. So it is necessary to prevent this.

On the other hand, in a chimney for releasing non-combustible gas to the atmosphere, such as a chimney of a thermal power plant, in order to prevent inconvenient phenomena such as downwash at the smoke outlet due to a decrease or fluctuation of the exhaust gas flow rate. Although it is well known to prevent a decrease in gas flow rate, no appropriate measures have been taken for a chimney that burns and burns combustible gas at the outlet.
By the way, as described above, it is well known to take measures to eliminate the inconvenience such as the above-described downwash for the non-combustible gas discharge chimney, and the method adjusts the opening cross-sectional area of the smoke protrusion according to the exhaust gas flow rate. The required exhaust gas flow rate is increased (Japanese Patent Laid-Open No. 2002-22148, Japanese Patent Laid-Open No. 2001-241647, Japanese Patent Laid-Open No. 2000-130746, and Japanese Patent Application No. 1-78688 (Japanese Utility Model Laid-Open No. 3-21639). ) Microfilm etc.). In these conventional techniques, a variable throttle portion is provided at the smoke outlet, thereby responding to a significant change in the amount of exhaust gas. That is, the variable throttle part is configured by a throttle plate, a partition plate, etc. installed at the smoke outlet, and the objective is achieved by appropriately changing the opening area of the smoke outlet by operating it with a driving device according to the amount of exhaust gas. I am doing so.

In addition, these conventional technologies were invented to cope with fluctuations in the amount of exhaust gas, but are not based on the premise that the combustible gas is burned and discharged at the smoke outlet. There is no consideration for this.
On the other hand, in the case of a chimney (combustion gas discharge chimney) that emits exhaust gas with a relatively high CO gas concentration to the atmosphere, such as a non-combustion converter exhaust gas treatment device, the combustion temperature at the smoke outlet is extremely high (approximately 1000 ° C) ), And the diaphragm portion of the above prior art diaphragm plate or the like has no heat resistance against this high temperature. Therefore, the above prior art cannot be applied to a combustible gas discharge chimney.
From the above, in order to be able to appropriately cope with the above problem in the chimney for combustible gas discharge, the structure of the throttle part in the chimney discharge port is ensured to have high heat resistance to the combustion heat of the combustible gas. It is necessary to devise the structure and the cooling structure.

Japanese Patent Laid-Open No. 2002-22148 JP 2001-241647 A JP 2000-130746 A Microfilm of Japanese Patent Application No. 1-78688 (Japanese Utility Model Application No. 3-21639)

  The problem to be solved by the present invention is to secure a sufficient gas flow rate by reducing the opening area of the discharge port with a simple configuration for the chimney that discharges the combustible gas. It is to improve the heat resistance against radiant heat generated by gas combustion and to devise the structure so that burning is prevented.

[Solution] (Corresponding to Claim 1)
Means for solving the above-mentioned problems are as follows: (A) A core is attached to the inside of the smoke projecting opening portion, the opening area is reduced, and the chimney for combustible gas discharge is premised on the following (a), (b), (c ).
(A) The core is composed of a ceiling part, a trunk part, and a bottom part, and the ceiling part has a conical shape,
(B) At the ceiling portion of the core and the upper end portion of the trunk portion, a continuous heat shield plate is attached with a gap between the core to form a double structure, and the center of the ceiling of the heat shield plate There is an opening in the part,
(C) A structure in which a part of the exhaust gas flowing through the smoke protrusion port passes through the gap between the core and the heat shield plate and the core and the heat shield plate are cooled.
[Operation]
By attaching a core inside the exit of the combustible gas discharge chimney and reducing the opening area of the smoke protrusion, the gas flow rate at the smoke protrusion is sufficiently secured even when the amount of combustible gas discharged is small. Therefore, inconvenient phenomena such as flashback and downwash are prevented.
The core includes a ceiling portion, a trunk portion, and a bottom portion, and the ceiling portion has a conical shape, and a gap is maintained between the core at the ceiling portion and the trunk portion upper end portion. A continuous heat shield plate is attached to form a double structure, and an opening is provided in the center of the ceiling of the heat shield plate, so that a part of the exhaust gas flowing through the smoke projection port is a gap between the core and the heat shield plate. Since the core and the heat shield plate are cooled by passing through the gas, a part of the exhaust gas flowing through the smoke projection opening passes through the gap between the core and the heat shield plate and the opening portion of the heat shield plate Therefore, even if the CO gas is burned at the smoke outlet and radiant heat is generated, the core and the heat shield plate are overheated by this radiant heat. It is prevented from being burned out.

[Embodiment 1] (corresponding to claim 2)
Embodiment 1 is that in the above solution, the core is a hollow core and a gas vent pipe is provided in the core.
[Operation]
Since the hollow core is attached to the smoke projection opening, the temperature fluctuates under the influence of the exhaust gas temperature and the radiant heat generated by the combustion of the CO gas, and the gas in the hollow core expands or contracts. In such a case, since the gas in the hollow core enters and exits through the gas vent pipe, the core is not deformed and damaged by the expansion and contraction of the internal gas.

[Embodiment 2] (corresponding to claim 3)
Embodiment 2 is the above-described solution or embodiment 1, wherein the core is attached to the inside of the smoke protruding portion by a core support arm having a bottom plate with an opening, and the smoke protruding portion is A part of the flowing exhaust gas passes through the opening of the bottom plate to cool the core support arm.
[Operation]
Part of the exhaust gas flowing through the smoke outlet flows through the opening of the bottom plate and cools the core support arm, so even if CO gas is burned at the smoke outlet and radiant heat is generated, the core is supported by this radiant heat. Burnout of the arm is prevented.

The effects of the present invention are summarized for each main claim as follows.
(1) Advantages of the Invention According to Claim 1 By installing a core inside the chimney that discharges flammable gas such as CO gas (flammable gas discharge chimney), a backfire or down to the CO gas in the chimney Inconvenient phenomena such as washing can be prevented.
In addition, by providing a heat shield plate on the core attached inside the smoke projection opening to form a double structure, a part of the exhaust gas flows between the core and the heat shield plate, and the core and the heat shield plate. Since the hot plate is cooled, the core and the heat shield plate are effectively cooled by the exhaust gas without using a coolant such as cooling water.
Therefore, it is completely prevented from being overheated by the radiant heat at the time of combustible gas combustion and being burned out.
(2) The effect of the invention according to claim 2 Since the hollow core is attached to the smoke projection opening, the temperature fluctuates under the influence of the temperature of the exhaust gas and the radiant heat caused by the combustion of the CO gas. The gas in the air core expands or contracts, which causes deformation of the core and its mounting structure, which can be damaged by applying a large force. However, according to the present invention, in such a case, the gas in the hollow core enters and exits through the gas vent pipe, so that this is prevented.

(3) The effect of the invention according to claim 3 An opening is opened in the bottom plate of the core support arm that attaches the core to the inside of the smoke projection opening, and a part of the exhaust gas flows through the opening, whereby the core Since the support arm is structured to cool, the core support arm can be cooled without using coolant such as cooling water, and it is completely possible that the core support arm is burned out by radiant heat due to combustible gas combustion. Is prevented.

  In this embodiment, the present invention is applied to a chimney of a non-combustion type converter exhaust gas treatment apparatus, and a conical ceiling part and a cylindrical body part are provided inside an outlet part of the chimney, and a gas vent pipe is provided. The core is attached by a core support arm, and a heat shield plate is attached to the upper end portion of the ceiling portion and the trunk portion of the core with a gap between the core and the core support. An opening is formed in the bottom plate forming the arm, and a part of the exhaust gas flowing through the smoke projection opening flows through the gap between the core and the heat shield plate and the opening of the bottom plate, and the core, The heat shield and the core support arm are configured to be cooled.

Before describing this embodiment, an outline of a non-combustion type converter exhaust gas treatment apparatus and an outline of a decarburization operation and a dephosphorization operation performed using this apparatus will be described with reference to FIG.
First, as shown in FIG. 1, the non-combustion type converter exhaust gas treatment apparatus is provided with a hood part 3 and a cooler 4 at an upper part of the converter 1, and at a lower end part of the hood part 3. Is fitted with a skirt 2. A primary dust collector 5 and a secondary dust collector 6 are installed downstream of the cooler 4, and an exhaust gas flow meter 7 and an induction blower 8 are further provided downstream thereof. The outlet of the induction blower 8 is connected to the gas recovery duct 10 and the chimney 11 via the three-way switching valve 9. A pilot burner 13 is provided at the upper end of the chimney 11.

Next, the outline of the decarburization operation performed using the non-combustion type converter exhaust gas treatment apparatus will be described. The molten iron (pig iron) produced in the blast furnace and charged into the converter 1 contains a large amount of carbon. Therefore, it reacts with pure oxygen blown from the lance 14 and / or the bottom blowing nozzle 15 to generate a large amount of CO gas (referred to as blowing). The generated CO gas is sucked into the hood 3 and the cooler 4 by the induction blower 8 through the skirt 2 that adjusts the gap between the furnace port of the converter 1 and the hood 3. The converter gas sucked into the cooler 4 is cooled to about 1000 ° C., and the clean CO gas removed by the primary dust collector 5 and the secondary dust collector 6 has a high CO concentration at the blowing stage. Sometimes it is recovered as valuable gas in a gas holder (not shown) via the three-way switching valve 9. On the other hand, the gas with low CO concentration at the initial stage or the final stage of blowing is switched to the chimney 11 side by the three-way switching valve 9 and ignited by the pilot burner 13 at the upper part of the chimney to be diffused into the atmosphere as harmless CO ₂ gas.

When the non-combustion type converter flue gas treatment equipment planned for decarburization blowing is used as a flue gas treatment equipment exclusively for dephosphorization operation, the exhaust gas flow rate is greatly reduced and the exhaust gas outflow rate is reduced. It will drop significantly. This is a case of diverting to another use of a specific exhaust gas treatment apparatus, but the use rate does not change, and the exhaust gas outflow rate may be greatly reduced even when the exhaust gas treatment amount is reduced.
In this embodiment, the non-combustion converter exhaust gas treatment device (originally planned and installed for decarburization blowing) has an exhaust gas flow rate of 523,000 m ³ / h and a gas temperature of 78 ° C. in the initial plan. The chimney diameter is 2.5 m, the smoke outlet height is 80 m, and the gas flow rate at the smoke outlet is 29.6 m / s.
On the other hand, when dephosphorization operation is carried out using the same non-combustion converter exhaust gas treatment device, the exhaust gas flow rate is 102900 m ³ / h, the gas temperature is 63 ° C., and the gas flow rate at the smoke outlet is 5. 82 m / s.

  In such a non-combustion type converter exhaust gas treatment device, when the gas flow velocity in the chimney becomes 7 m / s or less, a swirl flow is generated in the gas flow in the chimney, and the central portion of the gas flow becomes a funnel shape. There is a risk that the outside air enters the portion and the flame of the pilot burner 13 explosively backfires in the chimney. In addition, when a cross wind strikes the top of the chimney while the gas flow rate at the smoke outlet is decreasing, a so-called downwash phenomenon occurs.

The structure of the smoke outlet of this embodiment is as shown in FIG. 2, and the core 16 of the present invention is attached to the smoke outlet to reduce the opening area of the smoke outlet and to block the radiant heat generated by the combustion of CO gas. The heat effect and the cooling effect on the core are increased to prevent the core from burning out.
First, the structure of the smoke protrusion opening portion on which the core 16 is installed will be described with reference to FIGS.
Inside the outlet portion of the chimney 11, the core 16 is supported on the upper end of the chimney 11 by a core support arm 19 (six in the illustrated embodiment), and the steady rest 20 (in the illustrated embodiment). 4) and held in place. As shown in FIGS. 2 and 3, the core 16 is a hollow core composed of a conical ceiling portion 16a, a bottom portion 16c, and a cylindrical body portion 16b, and the ceiling portion 16a includes a gas vent pipe. 18 is provided. The gas vent pipe 18 allows the gas in the core 16 to enter and exit, and the location where the gas vent pipe 18 is provided is not particularly limited.

A continuous heat shield plate 17 is attached to the upper end portions of the ceiling portion 16a and the trunk portion 16b of the core 16 via a plurality of ribs 22 so that a gap is formed between the core 16 and the upper portion. An opening 21 is provided at the center of the ceiling of the heat shield plate 17. The continuous heat shield plate 17 forms a double structure having a gap between the core 16 and the heat shield plate 17, and a part of the exhaust gas flowing through the chimney 11 passes through the gap to open the opening 21. The heat shield plate 17 is cooled from the inside and becomes a heat insulating air layer inside the heat shield plate.
The core support arm 19 for supporting the core 16 includes side plates 19a and 19b on both sides, and a bottom plate 19c on the lower side thereof. Since the bottom plate 19c has a plurality of openings 19d, a part of the exhaust gas flowing in the chimney 11 flows along the side surfaces of the side plates 19a and 19b through the opening 19d.

Next, the operation of this embodiment will be described.
The exhaust gas containing CO gas generated from the converter 1 is sucked by the induction blower 8, passes through the cooler 4, the primary and secondary dust collectors 5 and 6, and the exhaust gas flow meter 7, and then passes through the three-way switching valve 9 and the chimney. It flows to 11.
The exhaust gas flowing through the chimney 11 flows through the space between the core 16 and the inner wall surface of the chimney 11 at the smoke projection opening. Since this space is narrowed by the core 16, the gas flow is accelerated in this portion, and a sufficient gas flow rate is ensured. Therefore, backfire, downwash, etc. can be prevented, and the exhaust gas discharged from the smoke outlet is made harmless by burning the contained CO gas, blown upward, and diffused to the atmosphere.
By the way, when exhaust gas flows through the space between the core 16 and the inner wall surface of the chimney 11, a part of the exhaust gas passes through the gap between the core 16 and the heat shield plate 17, and further, the heat shield plate 17. To the opening 21 of A part of the exhaust gas flows through the plurality of openings 19d opened in the bottom plate 19c of the core support arm 19, and further flows along the side surfaces of the side plates 19a and 19b. Since a part of the exhaust gas flows in this manner, the core 16, the heat shield plate 17, and the core support arm 19 are cooled. Therefore, the core 16, the heat shield plate 17, And it is prevented that the core support arm 19 is overheated and burned out.

Here, an example of a specific structure of the smoke projection opening will be described.
If the diameter of the core 16 is 1.31 m, the gap between the core 16 and the chimney inner wall surface is 595 mm, and the gas flow rate at the smoke projection port is 8.02 m / s. As a result, the occurrence of flashback and downwash phenomenon is eliminated (generally, it has been confirmed that the above phenomenon can be avoided when the exhaust gas flow velocity at the outlet is 80 m or more in a chimney with a height of 80 m. ) In addition, the cooling action by the exhaust gas is remarkable, and this prevents deterioration such as deformation and burning due to overheating of the core 16 and the core support arm 19.

It is a conceptual diagram of a converter exhaust gas processing apparatus. It is side sectional drawing of the smoke protrusion opening part of the Example of this invention. The core of the Example of this invention is shown. (a) is the top view, (b) is the side view, and shows a part of the heat shield. It is a top view of the smoke protrusion port part (state which removed the heat shield plate) of the Example of this invention. 3 shows a core support arm according to an embodiment of the present invention. (a) is the top view, (b) is the side view.

Explanation of symbols

1: Converter 2: Skirt 3: Hood part 4: Cooler 5: Primary dust collector 6: Secondary dust collector 7: Exhaust gas flow meter 8: Induction blower 9: Three-way switching valve 11: Chimney 13: Pilot burner 14 : Lance 15: Bottom blowing nozzle 16: Core 16a: Core ceiling portion 16b: Core trunk portion 16c: Core bottom portion 17: Heat shield plate 18: Gas vent pipe 19: Core support arm 19a: Core support arm side plate 19b: Core support arm side plate 19c: Core support arm bottom plate 19d: Bottom plate opening 20: Stabilization 21: Opening 22: Rib

Claims (3)

In the chimney for exhausting the combustible gas, which has a core installed inside the smoke projection opening and the opening area is reduced,
The core consists of a ceiling part, a trunk part, and a bottom part, and the ceiling part has a conical shape,
At the ceiling portion of the core and the upper end of the trunk portion, a continuous heat shield plate is attached with a gap between the core and a double structure is formed, and an opening is formed in the ceiling central portion of the heat shield plate. Has a section,
A combustible gas discharge chimney having a structure in which a part of the exhaust gas flowing through the smoke projection port passes through a gap between the core and the heat shield plate and the core and the heat shield plate are cooled. .   2. The combustible gas discharge chimney according to claim 1, wherein the core is a hollow core and a gas vent pipe is provided in the core. The core is attached to the inside of the smoke protruding portion by a core support arm having a bottom plate with an opening,
3. The combustible gas discharge chimney according to claim 1, wherein a part of the exhaust gas flowing through the smoke projection port passes through the opening of the bottom plate to cool the core support arm.

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