EP4350215A1

EP4350215A1 - Emission bleeder

Info

Publication number: EP4350215A1
Application number: EP22815860.6A
Authority: EP
Inventors: Satoshi Kawahata; Tomoyuki Kawashima; Tamotsu Takahashi; Shunichi Kamezaki
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2021-06-02
Filing date: 2022-05-19
Publication date: 2024-04-10
Anticipated expiration: 2042-05-19
Also published as: EP4350215B1; JP7207618B1; TW202307372A; WO2022255108A1; JPWO2022255108A1; BR112023023492A2; EP4350215A4

Abstract

Provided is an emission bleeder that can promote combustion of coke oven emission gas containing flammable gas and reduce an emission amount of unburned coke oven emission gas while keeping a cost for altering the emission bleeder small.

An emission bleeder 1 that burns and releases coke oven emission gas into atmosphere, including a bleeder pipe 3 that distributes the coke oven emission gas 17; a hood 2 that is provided on an upper end side 3A of the bleeder pipe 3, has an inner diameter larger than an outer diameter of the bleeder pipe 3, and whose lower end side 2A surrounds the upper end side 3A of the bleeder pipe 3; a blowing pipe 4 that is provided along a circumferential direction of the bleeder pipe 3 and blows combustion promoting gas 8 for promoting combustion into the hood 2 from a gap 5 between the bleeder pipe 3 and the hood 2; and an ignition device 6 that is disposed on an inner wall of the hood 2, in which the hood 2 has a notch part 7 at a position that faces a position in the circumferential direction where the blowing pipe 4 is disposed across a central axis line O of the hood 2.

Description

Technical Field

The present invention relates to an emission bleeder that can reduce an emission amount of unburned coke oven emission gas by promoting combustion of coke oven emission gas.

Background Art

In an iron making plant, a petrochemical plant, or the like, flammable gases such as methane, carbon monoxide, and hydrogen are discharged as by-products produced as a result of incomplete combustion in various combustion processes. If incomplete combustion occurs when these flammable gases are burned to make the flammable gases harmless and then be released into the atmosphere, black smoke (soot) is generated. Therefore, when the flammable gases are released into the atmosphere, it is necessary to completely burn the flammable gases before releasing them.
An emission bleeder is known as a device used when flammable gas is released. A conventional emission bleeder has a double-pipe structure including a hood leading to the atmosphere at an upper opened end part and a bleeder pipe that is surrounded by a lower end side opposite to the opened end part of the hood and leads to a flammable gas generation source. Flammable gas is fed to the bleeder pipe by pressure, a negative pressure thus generated in the hood causes gas (e.g., air) containing oxygen to be taken into the hood through a gap between the hood and the bleeder pipe, and these gases are mixed and ignited by an ignition device to burn the flammable gas.
As a technique concerning such an emission bleeder, Patent Literature 1 discloses a technique (see, for example, [0091] and Fig. 3 of Patent Literature 1) of adjusting an amount of air taken in from an outer pipe by adjusting sizes, the number, intervals, and the like of air passages (52, 92) provided in the outer pipe and thereby improving combustion efficiency.
Furthermore, Patent Literature 2 discloses a technique of improving combustion efficiency by passing air through a bleeder pipe and taking flammable gas in through a gap between the bleeder pipe and an outer pipe.

Citation List

Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No. 2010-236856
PTL 2: Japanese Unexamined Patent Application Publication No. 2010-286230

Summary of Invention

Technical Problem

However, just by taking in air by a negative pressure in a hood as described above, gases are not efficiently mixed and stirred and it is difficult to completely burn flammable gas, and therefore a large amount of unburned flammable gas is undesirably released into the atmosphere.
According to the technique disclosed in Patent Literature 1, it is necessary to newly provide a component, a system, or the like for controlling an amount of air taken in from the outer pipe. This undesirably complicates an apparatus configuration and an operating method. In particular, it is necessary to greatly alter an outer pipe of an emission bleeder.
Furthermore, to apply the technique disclosed in Patent Literature 2 to a conventional general emission bleeder, a gas flow needs to be made different from a conventional gas flow, in which flammable gas is passed through a bleeder pipe and air is taken into an outer pipe. This undesirably makes it necessary to alter the whole equipment.
The present invention was attained in view of the above problems, and an object of the present invention is to provide an emission bleeder that can reduce an emission amount of unburned coke oven emission gas by promoting combustion of coke oven emission gas containing flammable gas while keeping a cost for altering the emission bleeder small.

Solution to Problem

An outline configuration of the present invention that solves the above problems is as follows.

[1] An emission bleeder that burns coke oven emission gas and releases the coke oven emission gas into atmosphere, including a bleeder pipe that distributes the coke oven emission gas; a hood that is provided on an upper end side of the bleeder pipe, has an inner diameter larger than an outer diameter of the bleeder pipe, and whose lower end side surrounds the upper end side of the bleeder pipe; a blowing pipe that is provided along a circumferential direction of the bleeder pipe and blows combustion promoting gas for promoting combustion into the hood from a gap between the bleeder pipe and the hood; and an ignition device that is disposed on an inner wall of the hood, in which the hood has a notch part at a position that faces a position in the circumferential direction where the blowing pipe is disposed across a central axis line of the hood.
[2] The emission bleeder according to [1], in which the notch part is provided in a range of 1° or more and 70° or less toward both directions in the circumferential direction of the hood from the position that faces the position where the blowing pipe is disposed across the central axis line, and a lowermost part of the notch part is located above the ignition device.
[3] The emission bleeder according to [1] or [2], in which the blowing pipe is inclined with respect to a pipe axis line of the bleeder pipe so that a jet flow of the combustion promoting gas ejected from the blowing pipe collides with an outer wall of the bleeder pipe obliquely from a lower side.
[4] The emission bleeder according to [3], in which the blowing pipe is inclined so that a blowing axis line of the blowing pipe is at an angle of 10° or more and 30° or less with respect to the pipe axis line of the bleeder pipe. Advantageous Effects of Invention

According to the present invention, it is possible to promote combustion of coke oven emission gas containing flammable gas and reduce an emission amount of unburned coke oven emission gas while keeping a cost for altering the emission bleeder small.

Brief Description of Drawings

[Fig. 1] Fig. 1 is a schematic view illustrating a coke oven battery.
[Fig. 2] Fig. 2 is a schematic view illustrating an example of a configuration of an emission bleeder according to an embodiment of the present invention.
[Fig. 3] Fig. 3 is a view for explaining a state of a jet flow in the emission bleeder that is produced by disposing a blowing pipe.
[Fig. 4] Fig. 4 is a view for explaining a positional relationship between the blowing pipe and a notch part of a hood in the emission bleeder according to the embodiment of the present invention.
[Fig. 5] Fig. 5 illustrates a relationship between a notch angle of the notch part and a soot generation amount ratio in the emission bleeder according to the embodiment of the present invention.
[Fig. 6] Fig. 6 illustrates distributions of an oxygen concentration and a pressure with respect to the notch angle of the notch part of the emission bleeder according to the embodiment of the present invention.
[Fig. 7] Fig. 7 illustrates an example of a shape of the notch part provided in the hood of the emission bleeder according to the embodiment of the present invention.
[Fig. 8] Fig. 8 is a view for explaining a difference in state of a jet flow of combustion promoting gas ejected from the blowing pipe that is caused by a difference in inclination of the blowing pipe to a bleeder pipe.
[Fig. 9] Fig. 9 illustrates, as a speed distribution in a vertical direction, a state of a jet flow of combustion promoting gas blown from a gap between the bleeder pipe and the hood into the hood by the blowing pipe.
[Fig. 10] Fig. 10 illustrates a speed distribution in a vertical direction of a flow of gas (coke oven emission gas, combustion promoting gas, combustion gas, and atmosphere) inside and around the emission bleeder and a distribution of a soot generation amount (volume) at a corresponding height position in the vertical direction.
[Fig. 11] Fig. 11 is a view for explaining a simulation condition of an emission bleeder according to Example. Description of Embodiments

An embodiment of the present invention is described below.
An outline of a coke oven battery is described with reference to Fig. 1. In a coke oven battery 11, a carbonization chamber 12 and a combustion chamber 13 are alternately disposed. In the combustion chamber 13, heat is generated by combustion of combustion gas. In the carbonization chamber 12, coal is carbonized by heat generated in the adjacent combustion chamber 13. In a coal carbonization process, flammable gas called coke oven gas, which is one kind of flammable gas, is generated. Main components of the coke oven gas are, for example, H₂, CO, and other kinds of hydrocarbon gases. Note that although two carbonization chambers 12 and two combustion chambers 13 are illustrated in Fig. 1, actually, a large number of combinations of the carbonization chamber 12 and the combustion chamber 13 are provided toward a deeper side in Fig. 1.
Above each of the carbonization chambers 12, an ascension pipe 14 that collects the rising coke oven gas 16 and a gas collecting pipe 15 called a dry main that collects the coke oven gas 16 sucked up through the ascension pipes 14 from the plurality of carbonization chambers 12 are provided. The emission bleeder 1 is connected to the gas collecting pipe 15. The coke oven gas 16 generated in the plurality of carbonization chambers 12 passes through the ascension pipes 14 and the gas collecting pipe 15, and is then released into the atmosphere as coke oven emission gas 17 via the emission bleeder 1.
During normal operation of a plant, the coke oven gas 16 generated in the carbonization chamber 12 is sucked and collected by gas sucking equipment (not illustrated) and is re-used as gas for operating various kinds of equipment. On the other hand, during occurrence of a trouble such as power outage of the plant, the coke oven gas 16 generated in the carbonization chamber 12 cannot be sufficiently collected and re-used, and therefore needs to be released into the atmosphere as the coke oven emission gas 17 via the emission bleeder 1.
Next, the emission bleeder 1 according to the present invention is described with reference to Fig. 2. Fig. 2 is a schematic view briefly illustrating an example of a configuration of the emission bleeder 1 according to the embodiment of the present invention. The up-down direction in Fig. 1 corresponds to a vertical direction of the emission bleeder 1 according to the present invention. As illustrated in Fig. 2, the emission bleeder 1 includes a hood 2, a bleeder pipe 3, a blowing pipe 4, and an ignition device 6. The hood 2 has a notch part 7, which will be described later.
The bleeder pipe 3 is communicated with a coke oven gas generation part at a terminal part (not illustrated, an end part below Fig. 2) through the gas collecting pipe 15, and causes the coke oven emission gas 17 containing the flammable gas to flow toward the hood 2. In Fig. 2, the coke oven emission gas 17 flows from a lower part to an upper part. The hood 2 causes the coke oven emission gas 17 flowing through the bleeder pipe 3 to be released into the atmosphere from an opened end part (an upper end part in Fig. 2). An upper end side 3A of the bleeder pipe 3 is surrounded by a lower end side 2A of the hood 2 that has an inner diameter larger than an external diameter of the bleeder pipe 3.
Specifically, a lower end part of the lower end side 2A of the hood 2 is located below an upper end part of the upper end side 3A of the bleeder pipe 3, and thereby a region where the bleeder pipe 3 is surrounded by the hood 2 is formed. In this region where the bleeder pipe 3 is surrounded by the hood 2, a gap 5 is formed between an inner wall of the hood 2 and an outer wall of the bleeder pipe 3. Furthermore, the ignition device 6 for burning the flammable gas contained in the coke oven emission gas 17 is provided on the inner wall of the hood 2.
In the embodiment, the blowing pipe 4 that blows combustion promoting gas 8 for promoting combustion of the coke oven emission gas 17 from the gap 5 formed by the bleeder pipe 3 and the hood 2 into the hood 2 at a high speed is provided. The blowing pipe 4 may be connected, for example, to a compressor or the like (not illustrated) so that the combustion promoting gas 8 can be fed by pressure. Furthermore, when the combustion promoting gas 8 is blown from the blowing pipe 4, not only the combustion promoting gas 8, but also flow of accompanying gas drawn into the gap 5 from surroundings of the combustion promoting gas occurs. As a result, not only the combustion promoting gas 8, but also a large amount of accompanying gas is taken into the hood 2.
The combustion promoting gas 8 and the accompanying gas blown into the gap 5 rise along the outer wall of the bleeder pipe 3, and is mixed and stirred with the coke oven emission gas 17 fed from an inside of the bleeder pipe 3 inside the hood 2. The stirred gas is burned by being ignited by the ignition device 6, and thereby flame (not illustrated) is formed upward from the upper end side 3A of the bleeder pipe 3. A large amount of accompanying gas (especially air) is taken into the hood 2 together with the combustion promoting gas 8 fed from the blowing pipe 4, the flammable gas contained in the coke oven emission gas 17, the combustion promoting gas 8, and the accompanying gas are sufficiently stirred, and thus combustion of the flammable gas is promoted.
The blowing pipe 4 need just be provided at a position where the combustion promoting gas 8 can be injected into the gap 5. For example, the blowing pipe 4 need just be provided so that a tip part of the blowing pipe 4 is located below the upper end side 3A of the bleeder pipe 3. The blowing pipe 4 need just be provided at one or more predetermined positions in a circumferential direction on the outer wall of the bleeder pipe 3 for each combination of bleeder pipe 3 and hood 2. Alternatively, a plurality of blowing pipes 4 may be concentrated at one position being arranged in the circumferential direction.
The combustion promoting gas 8 is not limited in particular as long as it is gas, but is preferably non-flammable gas in order to prevent explosion and incomplete combustion in the hood 2. Among non-flammable gases, at least one of air, nitrogen gas, and steam is especially preferable. Even in a case where nitrogen gas is used as the combustion promoting gas 8, combustion of the flammable gas is promoted since oxygen contained in the accompanying gas such as air taken into the hood 2 together with the nitrogen gas as described above reacts with the flammable gas.
A volume ratio of the combustion promoting gas 8 blown into the hood 2 and the coke oven emission gas 17 that enters the hood 2 is preferably 1 : 10 to 7 : 10. If the volume ratio of the combustion promoting gas 8 is smaller than 1 : 10, there is a possibility that a gas stirring effect becomes weak and the flammable gas contained in the coke oven emission gas 17 cannot be sufficiently burned. If the volume ratio of the combustion promoting gas 8 is larger than 7 : 10, there is a possibility that a phenomenon called lifting in which flame occurs at a position away from the upper end side 3A of the bleeder pipe 3 and a phenomenon called blow-off in which flame is blown off occur.
In the present invention, the hood 2 has the notch part 7 at a position that faces a position in the circumferential direction where the blowing pipe 4 is disposed across a central axis line of the hood 2. In order to explain a reason why the inventors of the present invention arrived at providing the notch part 7 in the hood 2, first, a state of a jet flow of coke oven emission gas and combustion promoting gas in an emission bleeder in a case where the notch part 7 illustrated in Fig. 2 is not provided in the hood 2 is described with reference to Fig. 3. Fig. 3 is a schematic view briefly illustrating a jet flow in the emission bleeder 1 that is produced by disposing the blowing pipe 4.
As illustrated in Fig. 3, when a jet flow of the combustion promoting gas 8 ejected from the gap 5 between the hood 2 and the bleeder pipe 3 rises along the inner wall of the hood 2, a phenomenon in which the coke oven emission gas 17 fed from an inside of the bleeder pipe 3 is drawn toward the inner wall of the hood 2 occurs (A in Fig. 3). This occurs since the jet flow draws a surrounding fluid due to an effect of viscosity, specifically occurs due to an effect (hereinafter referred to as a "Coanda effect") that a fluid between the jet flow and the wall flows off due to a drawing effect to generate a negative pressure when a wall surface is placed parallel close to the jet flow and the jet flow is drawn toward the wall to fill the shortage.
The flow of the coke oven emission gas 17 becomes a drift by narrowing its flow path while approaching the inner wall of the hood 2 at a predetermined position in the circumferential direction where the blowing pipe 4 is disposed and rises while gradually increasing a flow speed.
On the other hand, at a position that faces the position in the circumferential direction where the blowing pipe 4 is disposed across a central axis line O of the hood 2, atmosphere (air) is drawn (B in Fig. 3) from the opened end part of the hood 2 toward the flow (A in Fig. 3) of the coke oven emission gas 17 drifting inside the hood 2, the air and the coke oven emission gas 17 are stirred, and thus oxygen is supplied into the flame. Furthermore, since the atmosphere (air) is also drawn into the flame (C in Fig. 3) immediately after the flow of the coke oven emission gas is discharged from the hood 2 and the effect of oxygen supply continues, combustion of the coke oven emission gas 17 can be promoted.
Furthermore, in a case where the coke oven emission gas 17 in the hood 2 is drifted toward the inner wall of the hood 2 on the blowing pipe 4 side (A in Fig. 3) as described above, a space region (a range surrounded by the broken line in Fig. 3) filled with atmosphere (air) drawn from the opened end part of the hood 2 occurs in the hood 2, as illustrated in Fig. 3. This space region occurs at a position on an opposite side that faces the position in the circumferential direction where the blowing pipe 4 is disposed across the central axis line O of the hood 2 (D in Fig. 3), and the coke oven emission gas does not flow in this region.
Therefore, in the present invention, the notch part 7 is provided in the hood 2, as illustrated in Fig. 2. That is, by cutting out a region of a circumferential wall part of the hood 2 where the space region in Fig. 3 and the inner wall of the hood 2 are in contact, atmosphere (air) is easily drawn from an outside to an inside of the hood 2, stirring of the coke oven emission gas 17 by the atmosphere thus drawn is enhanced, and combustion of the coke oven emission gas 17 can be promoted.
A positional relationship between the blowing pipe 4 and the notch part 7 of the hood 2 is described with reference to Fig. 4. Fig. 4(a) illustrates a configuration in which the notch part 7 is provided in the hood 2 in the emission bleeder 1 including the hood 2, the bleeder pipe 3, and the blowing pipe 4. Fig. 4(c) illustrates a configuration in which the notch part 7 is not provided in the hood 2 in the emission bleeder 1 illustrated in Fig. 4(a). Fig. 4(b) illustrates a planar positional relationship among the hood 2, the bleeder pipe 3, and the blowing pipe 4 in top view of the emission bleeder 1 in Fig. 4(a). Fig. 4(d) illustrates a planar positional relationship among the hood 2, the bleeder pipe 3, and the blowing pipe 4 in top view of the emission bleeder in Fig. 4 (c) .
As illustrated in Figs. 4(b) and 4(d), the bleeder pipe 3 is surrounded by the hood 2. The blowing pipe 4 is disposed at the gap 5 formed by the hood 2 and the bleeder pipe 3 along the circumferential direction of the bleeder pipe 3. In Fig. 4(b), the hood 2 has a dotted-line part and a thick-line part, the thick-line part indicates a circumferential wall part of the hood 2, and the dotted-line part indicates a range where the notch part 7 is provided in the circumferential wall part of the hood 2.
As illustrated in Fig. 4(b), the dotted-line part indicating that the notch part 7 is provided extends in an arc shape along the circumferential wall part of the hood 2. A midpoint G of the arc shape is located at a position that faces the position in the circumferential direction where the blowing pipe 4 is disposed across the central axis line O of the hood 2. That is, the notch part 7 is provided in the hood 2 at a position that faces the position where the blowing pipe 4 is disposed across the central axis line O.
The range of the dotted-line part indicating that the notch part 7 is provided is a range that stretches by a notch angle θ toward a positive direction and a negative direction in Fig. 4(b), that is, toward both directions in the circumferential direction of the hood 2 in the circumferential direction of the circumferential wall part of the hood 2 starting from the midpoint G of the arc shape, as illustrated in Fig. 4(b). The notch angle θ of the notch part 7 provided in the circumferential direction of the hood 2 is preferably in a range of 1° or more and 70° or less, more preferably in a range of 40° or more and 50° or less toward both directions in the circumferential direction of the hood 2.
A relationship between the notch angle θ of the notch part 7 and a soot generation amount ratio is described in relation to the preferable range of the notch angle θ with reference to Fig. 5.
Fig. 5(a) illustrates a soot generation amount ratio that is a ratio of a soot generation amount obtained when the notch angle θ of the notch part 7 is changed in a range of 45° to 165° to a soot generation amount obtained in a case where the notch part 7 is not provided (notch angle θ = 0°). In Fig. 5(b), the soot generation amount ratio in Fig. 5(a) is enlarged.
In a case where the notch angle θ is 45°, the soot generation amount can be decreased by 18% as compared with a case where the notch part 7 is not provided. However, in a case where the notch angle θ is larger than 90°, the soot generation amount increases markedly as compared with a case where the notch part 7 is not provided, and complete combustion of the coke oven emission gas is inhibited. As illustrated in Fig. 5(b), a notch angle θ at which the soot generation amount ratio becomes 1.0 between the notch angles θ of 45° and 90° is 73° as a result of interpolation from two points of 45° and 90°. Accordingly, to promote combustion of the coke oven emission gas and keep occurrence of soot small by providing the notch part 7, the notch angle θ is preferably set to 1° or more and 70° or less at which the soot generation amount ratio is less than 1.0. The notch angle θ is more preferably set to 40° or more and 50° or less at which the soot generation amount ratio is less than 0.85 (the soot generation amount is decreased by 15% to 180) .
Fig. 6 illustrates an O₂ concentration distribution and a pressure distribution in combustion situations where the notch angle θ of the notch part 7 is 0° (the notch part 7 is not provided), 45°, and 135°. When the notch angle θ of the notch part 7 is made large, it becomes easy to take air (atmosphere) into the hood 2 directly from an outside through the notch part 7, whereas it becomes hard to form a negative pressure inside the hood 2 necessary for drawing air (see the hatched part within the rectangular dotted-line frame in a part of Fig. 6 that illustrates a pressure distribution). Therefore, in a case where the notch angle θ is 135°, an amount of drawn air decreases, and an amount of oxygen supplied to flame decreases (compare sizes of regions where the O₂ concentration is 0.05 or less (the hatched part) within the rectangular dotted-line frame in a part of Fig. 6 that illustrates an O₂ concentration distribution).
Regarding the range where the notch part 7 is provided in the circumferential wall part of the hood 2, a lowermost part of the notch part 7 is preferably located above the ignition device 6. This is because if the lowermost part of the notch part 7 is located below the ignition device 6, coke oven emission gas leaks from the circumferential wall part of the hood 2 before ignition and unburned coke oven emission gas is released into the atmosphere.
A shape of the notch part 7 in the hood 2 is specifically described with reference to Fig. 7. Figs. 7(a) and 7(b) illustrate an example of a shape of the notch part 7 in a case where the blowing pipe 4 is provided at one position in the circumferential direction of the bleeder pipe 3.
Fig. 7(a) illustrates a configuration in which the circumferential wall part of the hood 2 that is in contact with the space region of Fig. 3 described above is cut out in a V shape to form the notch part 7 so that the lowermost part of the notch part 7 in a height direction of the circumferential wall part of the hood 2 is located above the ignition device 6. Fig. 7(b) illustrates a configuration different from Fig. 7(a), and illustrates a configuration in which the circumferential wall part of the hood 2 is cut out in a rectangular shape to form the notch part 7. As described above, the notch part 7 may be a part obtained by cutting out the circumferential wall part of the hood 2 in a V shape or may be a part obtained by cutting out the circumferential wall part of the hood 2 in a rectangular shape.
Furthermore, the blowing pipe 4 is preferably inclined with respect to a pipe axis line of the bleeder pipe 3 so that a jet flow of the combustion promoting gas 8 ejected from the pipe collides with the outer wall of the bleeder pipe 3 diagonally from a lower side.
A state of the jet flow that varies depending on a way in which the blowing pipe 4 is disposed is described with reference to Fig. 8. Figs. 8(a) and 8(b) illustrate a state of the jet flow (hereinafter referred to as "vertical ejection") in a case where the blowing pipe 4 is disposed so that a blowing axis line Q of the blowing pipe 4 extends in the same direction as the pipe axis line P of the bleeder pipe 3. Figs. 8(c) and 8(d) illustrate a state of the jet flow (hereinafter referred to as "collision ejection") in a case where the blowing axis line Q of the blowing pipe 4 is inclined with respect to the pipe axis line P of the bleeder pipe 3 at a predetermined angle (hereinafter referred to as an "attachment angle α") so that the jet flow of the combustion promoting gas 8 ejected from the blowing pipe 4 collides with the outer wall of the bleeder pipe 3 diagonally from a lower side.
Figs. 8(a) and 8(c) are perspective views briefly illustrating a way in which the hood 2, the bleeder pipe 3, and the blowing pipe 4 in the emission bleeder 1 are disposed. Fig. 8(b) is a cross-sectional view illustrating a positional relationship among the hood 2, the bleeder pipe 3, and the blowing pipe 4 taken along line V-V in Fig. 8(a), and Fig. 8(d) is a cross-sectional view illustrating a positional relationship among the hood 2, the bleeder pipe 3, and the blowing pipe 4 taken along line W-W in Fig. 8(c). In Figs. 8(a) and 8(c), the jet flow of the combustion promoting gas 8 ejected from the blowing pipe 4 is indicated by the arrows, and a cross-sectional spread of the jet flow of the combustion promoting gas 8 is illustrated as a jet flow R in Fig. 8(b) and as a jet flow S in Fig. 8(d).
In the case of the vertical ejection illustrated in Figs. 8(a) and 8(b), the jet flow of the combustion promoting gas slightly spreads in a radial direction about the blowing axis line Q of the blowing pipe 4 toward an upper side of the hood 2. The jet flow travels toward the upper side of the hood 2 while keeping an almost same speed as that immediately after ejection from the blowing pipe 4.
On the other hand, in the case of the collision ejection illustrated in Figs. 8(c) and 8(d), the jet flow of the combustion promoting gas 8 diffuses by colliding with the outer wall of the bleeder pipe 3, so that a speed of the jet flow decreases and a range of the jet flow thinly spreads in the circumferential direction (the jet flow S in Fig. 8(d)) . When the range of the jet flow spreads in the circumferential direction, a contact area between the jet flow and the atmosphere increases, and as a result accompanying gas such as air that is drawn into the gap 5 from surroundings of the combustion promoting gas 8 increases. As a result, an amount of atmosphere drawn into the hood 2 from an outside increases. This promotes combustion of the coke oven emission gas.
Fig. 9 illustrates, as a speed distribution in the vertical direction (an upward direction is positive), a state of the jet flow of the combustion promoting gas blown from the gap 5 between the bleeder pipe 3 and the hood 2 into the hood 2 by the blowing pipe 4. In the case of the vertical ejection (Fig. 9(a), the attachment angle is 0°), the jet flow of the combustion promoting gas ejected from the blowing pipe 4 becomes a jet flow that gradually spreads in a fan shape in a radial direction about the blowing axis line Q (not illustrated) of the blowing pipe 4 after being ejected from the blowing pipe 4. On the other hand, in the case of the collision ejection (Fig. 9(b), the attachment angle is 30°), the jet flow of the combustion promoting gas collides with the outer wall of the bleeder pipe 3 at an inclined angle, and thereby becomes a straightened jet flow that rises along the outer wall in the direction of the pipe axis line P (see Fig. 8(c)) while spreading thinly in the circumferential direction of the outer wall of the bleeder pipe 3 (see the jet flow S of Fig. 8(d)). A thickness Wb of the jet flow of a speed 15 m/s in an upper portion of the hood 2 in the case of the collision ejection (Fig. 9(b)) is smaller than a thickness Wa in the case of vertical ejection (Fig. 9(b)) (Wb < Wa), and Wb is approximately 30% of Wa. Therefore, in the case where the collision ejection, the Coanda effect can be increased by the straightened jet flow that rises along the inner wall of the hood 2, and a larger amount of air can be drawn.
Fig. 10 illustrates a speed distribution in a vertical direction (an upward direction is positive) of a flow of gas (coke oven emission gas, combustion promoting gas, combustion gas, and atmosphere) inside and around the emission bleeder and a distribution of a soot generation amount (volume) at a corresponding height position in the vertical direction. Fig. 10(a) illustrates a speed distribution of gas in the case of the vertical ejection (attachment angle α = 0°), and Fig. 10(b) illustrates a speed distribution of gas in the case of the collision ejection (attachment angle α = 30°). Fig. 10(c) illustrates a graph of a soot generation status in a case where the vertical ejection and the collision ejection of Figs. 10(a) and 10(b) are performed.
Note that the vertical axis (height) of the graph of Fig. 10(c) corresponds to a position in the vertical direction in Figs. 10(a) and 10(b), and the horizontal axis of the graph indicates a soot generation amount (volume) at each position in the vertical direction. The speed distribution of the gas illustrated in Fig. 10 includes a speed of a jet flow of the combustion promoting gas, a speed of the coke oven emission gas, and a speed of combustion gas and atmosphere (air).
It can be confirmed that, in the case of the collision ejection of Fig. 10(b), the flow of the coke oven emission gas is greatly drifted while approaching an inner wall surface of the hood 2 on a side where the blowing pipe 4 is disposed due to the Coanda effect, as compared with the case of the vertical ejection of Fig. 10(a). According to the soot generation status at the height position in the vertical direction illustrated in Fig. 10(c), a soot generation amount in the collision ejection is reduced to approximately 25% of that in the vertical ejection although both the soot generation amount in the vertical ejection and the soot generation amount in the collision ejection exhibit maximum values immediately after exit from the hood 2 (the height in Fig. 10(c) is around 4 m).
The blowing pipe 4 is preferably inclined so that the blowing axis line Q of the blowing pipe 4 is at an angle (attachment angle α) of 10° or more and 30° or less with respect to the pipe axis line P of the bleeder pipe 3.
This is because if the attachment angle α of the blowing pipe 4 is less than 10°, it is hard to obtain the straightening effect produced by collision of the jet flow with the outer wall of the bleeder pipe 3. Furthermore, this is because if the attachment angle α of the blowing pipe 4 is larger than 30°, a flow (backflow) of the jet flow toward a lower side in the vertical direction increases in addition to a flow of the jet flow toward an upper side in the vertical direction. This inhibits inflow of the accompanying gas taken in from the gap 5 between the bleeder pipe 3 and the hood 2, thereby inhibiting complete combustion of the coke oven emission gas.
As described above, by applying the emission bleeder 1 according to the present invention to the coke oven battery 11, it is possible to promote complete combustion of the coke oven emission gas generated in the carbonization chamber 12 even during occurrence of a trouble such as power outage and to release the gas into the atmosphere as a substance that causes little harm such as CO₂ or H₂O.
In a case where the emission bleeder 1 according to the present invention is applied to the coke oven battery 11, air is preferably used as the combustion promoting gas injected from the blowing pipe 4. To supply steam or nitrogen gas in a plant, it is necessary to operate an emergency steam generator, an air separation plant, and the like. On the other hand, in a case where air is used as the combustion promoting gas, the combustion promoting gas can be supplied to the emission bleeder 1 speedily and easily by a compressor equipped with an engine or the like even in an emergency.

Example

Example in which the emission bleeder according to the present embodiment was used is described below.
In the present Example, soot generation amounts (volumes) were compared by using a simulation model or the like on conditions that an emission bleeder including a bleeder pipe having an inner diameter of 100 mm was placed in a housing that was 10 m tall and 3 m wide, a situation where air flowed at a wind speed of 0.1 m/s was reproduced in the housing, and a situation where flammable gas flowed at a fluid speed of 2.5 m/s in the bleeder pipe was reproduced, as illustrated in Fig. 11.

To predict soot generation, the soot inception model for predicting soot generation, growth, and disappearance including nuclear inception, coagulation, surface growth, and oxidation processes proposed by Wen et al. (Acetylene inception model, Z. Wen et al, "Combustion and Flame", 2003, Vol.135, p.323-340) was used.

[Table 1]

	hood notch part		blowing pipe		soot generation amount ratio (based on present invention example 1)
	present/absent	notch angle θ[°]	present/absent	attachment angle α[°]
conventional example 1	absent	0	absent	-	66.31
conventional example 2	absent	0	present	0	4.50
present invention example 1	present	1	present	30	1.00
present invention example 2	present	20	present	30	0.92
present invention example 3	present	45	present	30	0.83
present invention example 4	present	60	present	30	0.92
present invention example 5	present	70	present	30	0.98
present invention example 6	present	45	present	10	0.83
present invention example 7	present	45	present	20	0.83
present invention example 8	present	90	present	30	1.10
present invention example 9	present	135	present	30	3.10
present invention example 10	present	45	present	5	1.66
present invention example 11	present	45	present	40	2.08

Table 1 shows a simulation result. The estimated soot generation amounts are expressed as soot generation amount ratios based on a present invention example 1 (1.0).
In a conventional example 1, the combustion promoting gas was not blown by the blowing pipe 4. In a conventional example 2, the notch part 7 was not provided in the hood 2, and vertical ejection was performed by setting the attachment angle α of the blowing pipe 4 to 0°. In each case, the soot generation amount ratio exceeded 1.0, and the coke oven emission gas was not sufficiently burned.
In the present invention example 1, the notch part 7 having a notch angle θ of 1°, which is within the preferable range (1° to 70°) of the present invention, was provided in the hood 2, and the attachment angle α of the blowing pipe 4 was set to 30°, which is within the preferable range (10° to 30°) of the present invention. As described above, the present invention example 1 is used as a standard of soot generation amounts in the present Example and the soot generation amount ratio in Table 1 was 1.00, the coke oven emission gas was sufficiently burned, and the soot generation amount ratio was improved, as compared with the conventional example 1 and the conventional example 2.
In present invention examples 2 to 5, the attachment angle α of the blowing pipe 4 was fixed to 30°, which is within the preferable range (10° to 30°) of the present invention, and the notch angle θ of the hood 2 was changed among 20°, 45°, 60°, and 70°, which are within the preferable range (1° to 70°) of the present invention. In each case, the soot generation amount ratio was less than 1.0, and the soot generation amount ratio was improved more than the present invention example 1.
In present invention examples 6 and 7, the notch angle θ of the hood 2 was fixed to 45°, which is within the preferable range (1° to 70°) of the present invention, and the attachment angle α of the blowing pipe 4 was set to 10° and 20°, which are within the preferable range (10° to 30°) of the present invention. In each case, the soot generation amount ratio was less than 1.0, the coke oven emission gas was sufficiently burned as compared with the conventional example 1 and the conventional example 2, and the soot generation amount ratio was improved more than the present invention example 1.
In the present invention examples 8 and 9, the attachment angle α of the blowing pipe 4 was set to 30°, which is within the preferable range (10° to 30°) of the present invention, and a large notch having a notch angle θ of 90° and 135°, which are outside the preferable range (1° to 70°) of the present invention, was provided in the hood 2. Although the soot generation amount ratio was improved as compared with the conventional example 1 and the conventional example 2, the soot generation amount ratio increased to exceed 1.0 as the notch angle θ increased, and combustion efficiency of the coke oven emission gas decreased as compared with the present invention examples 1 to 7, in which both of the notch angle θ of the hood and the attachment angle α of the blowing pipe 4 are within the preferable ranges of the present invention.
In present invention examples 10 and 11, the notch angle θ of the hood 2 was set to 45°, which is within the preferable range (1° to 70°) of the present invention, and the attachment angle α of the blowing pipe 4 was set to 5° and 40°, which are outside the preferable range (10° to 30°) of the present invention. In each case, the soot generation amount ratio was improved as compared with the conventional example 1 and the conventional example 2 but exceeded 1.0, and combustion efficiency of the coke oven emission gas decreased as compared with the present invention examples 1 to 7, in which both of the attachment angle α of the blowing pipe 4 and the notch angle θ of the hood are within the preferable ranges of the present invention.

Reference Signs List

1: emission bleeder
2: hood
3: bleeder pipe
4: blowing pipe
5: gap
6: ignition device
7: notch part
8: combustion promoting gas
11: coke oven battery
15: gas collecting pipe
16: coke oven gas
17: coke oven emission gas
O: central axis line
P: pipe axis line
Q: blowing axis line
θ: notch angle
α: attachment angle

Claims

An emission bleeder that burns coke oven emission gas and releases the coke oven emission gas into atmosphere, comprising:
a bleeder pipe that distributes the coke oven emission gas;

a hood that is provided on an upper end side of the bleeder pipe, has an inner diameter larger than an outer diameter of the bleeder pipe, and whose lower end side surrounds the upper end side of the bleeder pipe;

a blowing pipe that is provided along a circumferential direction of the bleeder pipe and blows combustion promoting gas for promoting combustion into the hood from a gap between the bleeder pipe and the hood; and

an ignition device that is disposed on an inner wall of the hood,

wherein the hood has a notch part at a position that faces a position in the circumferential direction where the blowing pipe is disposed across a central axis line of the hood.
The emission bleeder according to claim 1, wherein
the notch part is provided in a range of 1° or more and 70° or less toward both directions in the circumferential direction of the hood from the position that faces the position where the blowing pipe is disposed across the central axis line, and a lowermost part of the notch part is located above the ignition device.
The emission bleeder according to claim 1 or 2, wherein
the blowing pipe is inclined with respect to a pipe axis line of the bleeder pipe so that a jet flow of the combustion promoting gas ejected from the blowing pipe collides with an outer wall of the bleeder pipe obliquely from a lower side.
The emission bleeder according to claim 3, wherein
the blowing pipe is inclined so that a blowing axis line of the blowing pipe is at an angle of 10° or more and 30° or less with respect to the pipe axis line of the bleeder pipe.