JP7849673B2 - Repair method for deteriorated coke oven burner piping and coke oven fuel ducts - Google Patents

Description

This invention relates, for example, to burner piping for use in existing coke oven fuel ducts that have deteriorated over time.

Coke is produced through a carbonization process in a coke oven, where coal is heated to high temperatures (e.g., over 1,300°C) and is primarily used in the steelmaking process of steel manufacturers.

A coke oven has carbonization chambers and combustion chambers arranged horizontally and alternately at the top. In the carbonization chamber, coke is produced by dry distillation of raw materials, primarily coal. Fuel gas and air are supplied to the combustion chamber, generating high-temperature combustion gases (e.g., 1000°C to 1400°C). The carbonization chamber and combustion chamber are separated by a wall made of heat-resistant bricks or similar material. The heat of combustion is transferred to the carbonization chamber through this wall, thereby heating the coal inside.

The heat storage chamber is located at the bottom of the coke oven. High-temperature exhaust gas from the combustion chamber is guided to the heat storage chamber, where a portion of the heat is stored in heat storage bricks. The heat storage chamber is separated by a wall and runs parallel to the air supply duct and fuel supply duct. The heat from the heat storage chamber is used to preheat the air introduced into the combustion chamber from the air supply duct and fuel supply duct. The carbonized gas (COG) generated during coke production in the carbonization chamber is recovered and purified, and reused as a new energy source.

The air supply duct and fuel supply duct are connected to the combustion chamber from below.

Incidentally, at the time of filing this application, the existing coke ovens had been in operation for half a century, and significant deterioration due to aging was becoming apparent. In particular, cracks in the fuel supply ducts, etc., could cause gas leaks, leading to unintended combustion and sometimes preventing the combustion chamber from reaching the required temperature. Insufficient temperature can lead to decreased productivity and variations in coke quality, resulting in a decline in manufacturing functionality.

Even if we wanted to repair cracks in the fuel supply ducts, the existing coke ovens, built half a century ago, were not designed with repair in mind, and there is no established method for detecting where the cracks are occurring. Even if the cracks could be identified, there is insufficient workspace, making repairs difficult.

For existing coke ovens that have deteriorated over time, maintenance burner piping has been proposed (for example, Patent Document 1). This maintenance burner piping is formed by connecting ceramic tubing with metal bellows tubing. The outer diameter of the maintenance burner piping is smaller than the inner diameter of the fuel supply duct, and the length of the maintenance burner piping is equivalent to the length of the fuel supply duct.

The maintenance burner piping is inserted into the existing fuel supply duct. This ensures a reliable supply of fuel gas to the combustion chamber burner without the need to repair cracks or other damage to the fuel supply duct.

Japanese Patent Publication No. 2020-158715

After actually operating the maintenance burner piping described above, it became clear that the verticality of the existing fuel supply duct was worse than expected.

The maintenance burner piping described above also includes a section made of metal bellows. This allows it to be inserted into existing fuel supply ducts with poor verticality, by bending it as needed.

However, the main body of the above-mentioned maintenance burner piping, designed for high-temperature environments, is relatively long and highly rigid. This rigidity hinders the full flexibility of the metal bellows pipe.

Furthermore, identifying and predicting how the verticality of the existing fuel supply duct is deteriorating is difficult, requiring trial and error in inserting the maintenance burner piping. As a result, the process is more time-consuming than initially anticipated. Additionally, the low rigidity of the metal bellows pipes further complicates the insertion process.

Furthermore, although the metal bellows tube had a maximum heat resistance of 1000°C and was expected to have sufficient heat resistance, it was found to deteriorate more quickly than initially anticipated.

This invention aims to solve the above problems and to reliably supply fuel gas to the combustion chamber of an existing coke oven that has deteriorated over time, without requiring large-scale repairs.

In particular, the aim is to easily and reliably insert burner piping into fuel supply ducts where verticality has deteriorated.

To achieve the above objective, the present invention relates to coke oven burner piping inserted into the combustion gas duct of a coke oven. The burner piping includes multiple divided insertion pipes and joints provided between the insertion pipes, characterized by the provision of circumferential play at the connection points between the insertion pipes and the joints.

By incorporating play, an angle adjustment function is added between the insertion pipes, allowing multiple insertion pipes to be connected while accommodating the shape of fuel supply ducts with poor verticality.

More preferably, in the burner piping described above, the play is 2 to 12% of the insertion pipe diameter.

This allows for both angle adjustment and airtightness.

More preferably, the burner piping includes a heat-resistant packing and heat-resistant putty positioned between the end face of the insertion pipe and the pipe end face receiving portion of the joint.

The heat-resistant gasket and heat-resistant putty follow the movement of the insertion tube end face during angle adjustment. This ensures airtightness.

More preferably, in the burner piping described above, the insertion portion of the joint is inserted into the insertion pipe.

This prevents the outer diameter of the burner piping from becoming too thick at the connection point.

More preferably, in the burner piping described above, at least the uppermost of the multiple insertion tubes is made of ceramic.

This allows it to withstand the high temperatures of the combustion chamber.

More preferably, in the burner piping described above, the joint connected to the uppermost ceramic insertion tube is made of ceramic.

This allows it to withstand the high temperatures of the combustion chamber.

More preferably, in the burner piping described above, at least the lowest of the multiple insertion tubes is made of metal.

This allows it to support the weight of the connected insertion tubes.

More preferably, in the burner piping described above, the joint connected to the lowest metal insertion pipe is made of metal.

This allows it to support the weight of the connected insertion tubes.

To achieve the above objective, the present invention provides a method for installing burner piping for coke oven repair. The repair burner piping includes multiple divided insertion pipes and joints provided between the insertion pipes, with circumferential play formed at the connection points between the insertion pipes and the joints.

The first insertion pipe is inserted into the combustion gas duct of the existing coke oven. While positioning a heat-resistant packing and uncured heat-resistant putty between the end face of the insertion pipe and the pipe end face receiving portion of the joint, the joint and the next insertion pipe are inserted. The axial angle of the insertion pipe is adjusted through the play, and the insertion of the insertion pipes and joints is repeated until they are connected.

By providing play between the insertion tubes, the angle adjustment function is activated, allowing multiple insertion tubes to be connected while accommodating the shape of fuel supply ducts with poor verticality. The heat-resistant gasket and heat-resistant putty follow the movement of the insertion tube end faces during angle adjustment, ensuring airtightness. Uncured heat-resistant putty will undergo plastic deformation.

More preferably, in the above method for installing the repair burner piping, the uncured heat-resistant putty hardens after the coke oven repair burner piping is installed.

This determines the shape of the repair burner piping.

According to the burner piping of the present invention, fuel gas can be reliably supplied to the combustion chamber burner without requiring large-scale repairs, for example, in an existing coke oven that has deteriorated over time.

In particular, burner piping can be easily inserted into fuel supply ducts where verticality has deteriorated.

Existing coke ovens and repair examples Schematic diagram of the burner piping for repairs. Detailed diagram of the burner piping for repairs. Detailed diagram of the burner piping for repairs. Operational diagram for repair burner piping Operational diagram for repair burner piping Variation Variation Variation Variation

~Coke Oven~
Figure 1 shows a schematic configuration of an existing coke oven and an example of a repair. In the upper part of the coke oven, carbonization chambers and combustion chambers are arranged horizontally in alternating positions. The carbonization chambers and combustion chambers are separated by a partition wall made of heat-resistant bricks or the like. The heat of combustion generated in the combustion chamber is transferred to the carbonization chamber through the partition wall.

Air and fuel are supplied to the combustion chamber from the bottom of the coke oven via air and fuel supply ducts. If there are cracks or other deterioration in the fuel supply duct, gas leaks will occur. The leaked gas will ignite in unintended locations. As a result, the desired temperature may not be achieved in the combustion chamber.

In this application, the repair burner piping 1 is inserted into the existing fuel supply duct. For example, the length of the existing fuel supply duct is approximately 6m, and the total length of the repair burner piping 1 is also approximately 6m. The design inner diameter of the existing fuel supply duct is 65mm, and the outer diameter of the repair burner piping 1 is 50mm. Note that these values are examples to aid in understanding the invention and are not limiting. In other words, it is sufficient that the repair burner piping 1 can be inserted into the existing fuel supply duct. The same applies to the other values.

This allows for the reliable supply of fuel gas to the combustion chamber of existing coke ovens that have deteriorated over time, without requiring large-scale repairs.

~Overview of burner piping for repairs~
Figure 2 shows a schematic example of the repair burner piping configuration. Assuming the total length of the repair burner piping 1 is approximately 6m, twelve insertion pipes of approximately 500mm in length are connected.

In the illustrated example, the structure consists of 10 ceramic tubes 10 and 2 metal tubes 30. Joints are provided between the insertion tubes. These joints can be made of ceramic 20 or metal 40. In the illustrated example, ceramic joints 20 are placed between the ceramic tubes 10, metal joints 40 are placed between the ceramic tubes 10 and metal tubes 30, and metal joints 40 are placed between the metal tubes 30.

At a minimum, the uppermost insertion tube connecting to the combustion chamber is preferably made of ceramic. While the combustion chamber reaches high temperatures (e.g., 1000-1400°C), even ceramic tubes can achieve heat resistance of over 1500°C.

However, ceramic tubes 10 are more expensive than metal tubes and have inferior load-bearing capacity. When the insertion tubes are connected vertically, the weight of the tube itself becomes a significant factor at the bottom. Furthermore, in areas where the expected temperature does not exceed 1000°C (for example, below 800°C), ceramic tubes are not necessary. For these reasons, it is preferable that at least the lowest insertion tube be made of metal. Metal tubes 30 can reduce costs and withstand the weight of the connected insertion tubes.

The materials for the insertion tube and joint described above are examples only; they should be appropriately selected within the scope of the invention's technical concept (see the modified examples below).

～Detailed configuration of connection structure～
Figures 3 and 4 are detailed diagrams of the connection structure of the repair burner piping. Figure 3 is a schematic perspective view, and Figure 4 is a schematic plan view.

The joint 20 consists of upper and lower insertion portions 21, 21 and a pipe end face receiving portion 22 provided between the insertion portions 21, 21. The insertion portions 21 are inserted into the ceramic pipe 10. The end face of the ceramic pipe 10 abuts against the pipe end face receiving portion 22 via a heat-resistant packing 28 and heat-resistant putty 29.

While the joint 20 may externally insert the ceramic pipe 10, if the external insertion structure becomes too large compared to the pipe diameter, insertion into the existing fuel supply duct may become difficult. An internal insertion structure, where the insertion portion 21 is internally inserted into the ceramic pipe 10, is preferable as it facilitates the insertion of the repair burner piping 1 into the existing fuel supply duct.

In the internal insertion structure of the ceramic tube 10 and the joint insertion portion 21, it is preferable to have an appropriate amount of play 25. The play 25 is formed circumferentially between the inner circumference of the ceramic tube 10 and the outer circumference of the insertion portion 21.

In the illustrated example, when the inner diameter of the ceramic tube 10 is 42 mm, the outer diameter of the insertion portion 21 is 40 mm, and a 1 mm (total 2 mm) of play 25 is provided at both ends. The play ratio is approximately 2/42 = 5%. A play ratio of 2 to 12% is preferable. Furthermore, a play ratio of 4 to 8% is even more preferable. If the play ratio is too small, the angle adjustment function (details described later, see Figures 5 and 6) will be insufficient. If the play ratio is too large, the connection will be insufficient, leading to a risk of gas leakage.

In the prototype example, the risk of gas leakage became significant when the play ratio exceeded approximately 5/42 = 12%.

The insertion length of joint 20 should preferably be around 10 to 20 mm. If the insertion length is too short, the connection will be insufficient, and there will be a risk of gas leakage. If the insertion length is too long, the angle adjustment function (details described later, see Figures 5 and 6) will be insufficient.

The insertion tubes 10 and 30 of this invention are highly rigid and inflexible, but the play 25 compensates for this lack of flexibility.

However, intentionally creating a gap 25 reduces airtightness. Therefore, a heat-resistant packing 28 and heat-resistant putty 29 are provided between the end face of the ceramic pipe 10 and the pipe end face receiving portion 22.

The heat-resistant packing 28 is primarily composed of materials such as alumina fibers or glass fibers, and is expected to withstand temperatures of approximately 1400°C. The heat-resistant packing 28 maintains airtightness while following the movement of the end face of the ceramic tube 10.

The heat-resistant putty 29, for example, has aluminum hydroxide as its main component and can be expected to withstand temperatures of approximately 1200°C. The uncured putty is plastic and deforms to follow the movement of the end face of the ceramic tube 10 while maintaining airtightness. It hardens in that shape upon heating. For example, a putty with aluminum hydroxide as its main component dehydrates upon heating, becoming ceramic-like aluminum oxide.

Therefore, the heat-resistant packing 28 and heat-resistant putty 29 compensate for the reduced airtightness due to the play 25.

～Operation～
Figure 5 is a detailed diagram of the connection structure for the repair burner piping. For example, if a ceramic pipe 10 with an inner diameter of 42 mm is given a 1 mm gap 25 at each end, and the insertion length of the joint 20 is about 10 to 20 mm, then an angle adjustment of about 3 to 5 degrees (on one side) is possible. An angle adjustment of up to about 10 degrees is possible vertically with the joint 20. Furthermore, if a ceramic pipe 10 with an inner diameter of 42 mm is given a 2 mm gap 25 at each end, and the insertion length of the joint 20 is about 10 to 20 mm, then an angle adjustment of about 5 to 10 degrees (on one side) is possible. An angle adjustment of up to about 20 degrees is possible vertically with the joint 20.

First, the uppermost ceramic pipe 10 is inserted into the existing fuel supply duct. Next, the ceramic joint 20 is placed along with the heat-resistant packing 28 and heat-resistant putty 29, and the next ceramic pipe 10 is inserted into the existing fuel supply duct. This pushes the preceding ceramic pipe 10 upwards.

If the verticality of the existing fuel supply duct is poor, the angle adjustment function of the play 25 will activate, and the preceding ceramic pipe 10 will conform to the inclination of the existing fuel supply duct. Furthermore, the heat-resistant packing 28 and heat-resistant putty 29 will follow the movement of the lower end face of the preceding ceramic pipe 10.

The ceramic pipe 10 and ceramic joint 20 are repeatedly inserted, and metal pipe 30 and metal joint 40 are inserted as needed to connect the pipes and form the repair burner piping 1. At this time, the angle adjustment function of the play 25 is activated each time there is a bend in the existing fuel supply duct.

When the repair burner piping 1 is in place, the heat-resistant putty 29 is uncured and undergoes plastic deformation. However, after installation, it hardens upon heating while maintaining its shape, ensuring airtightness. This finalizes the shape of the repair burner piping 1.

Figure 6 is a further diagram illustrating the operation of the angle adjustment function of the play 25. Figure 5 explained the angle adjustment function of one play 25. By linking the angle adjustment functions of multiple play 25s, it is possible to accommodate complex degraded fuel supply duct shapes.

Figure 6A shows a case where the structure tilts significantly in one direction. The angle adjustment functions of the two "play" sections 25 operate in the same direction, allowing for adaptation to large tilts. By combining multiple "play" sections 25, even larger tilts can be accommodated.

Figure 6B shows a case where the tilt is in a fine S-shape. The angle adjustment functions of the two play sections 25 operate in opposite directions, allowing for adjustment even to fine S-shaped tilts. By combining multiple play sections 25, it is possible to accommodate more complex tilts.

~Effects~
Although it is difficult to identify and predict how the verticality of the existing fuel supply duct has deteriorated, the repair burner piping 1 is inserted while deforming to correspond to the shape of the deteriorated fuel supply duct. At this time, the deteriorated fuel supply duct does not require major repairs. As a result, fuel gas can be reliably supplied to the combustion chamber in existing coke ovens that have deteriorated over time without requiring major repairs.

The ceramic tube 10 and metal tube 30 are highly rigid, making insertion easy.

Furthermore, the ceramic tube 10 and ceramic joint 20 can be positioned in the high-temperature region, suppressing the effects of the high heat in the combustion chamber and enabling relatively long-term operation.

~Variations~
The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the technical concept of the present invention.

In the modified example shown in Figure 7, the repair burner piping 1 is entirely made of ceramic pipes 10 and ceramic joints 20. This modified example can be used when the temperature is relatively high throughout the entire area, the overall length is short, and the effect of self-weight is minimal.

In the modified example shown in Figure 8, the repair burner piping 1 is formed entirely from metal pipes 30 and metal joints 40. As shown in Figure 9B (described later), if it is not necessary to extend the repair burner piping 1 to the combustion chamber, there is no need to place an insertion pipe in the high-temperature region. In such cases, as in this modified example, the entire structure can be made from metal pipes 30 and metal joints 40.

In the modified example shown in Figure 7, all parts are made of ceramics, and in the modified example shown in Figure 8, all parts are made of metal. However, it is acceptable to use ceramics and metal as appropriate.

In the modified example shown in Figure 9A, the bellows tube 50 used in the conventional example may also be used as appropriate. In the present invention, many heat-resistant ceramic tubes can be used. As a result, the bellows tube 50 can be used while avoiding the high-temperature region. The bellows tube 50 is inserted in locations where the angle adjustment function of the play 25 cannot be used. The bellows tube 50 can be made relatively short and easy to handle even with low rigidity.

In the modified example shown in Figure 9B, the repair burner piping 1 does not reach the combustion chamber. The existing fuel supply duct immediately adjacent to the combustion chamber is visible, allowing for assessment of any deterioration. Even if deterioration is present, it can be easily repaired. If it can be confirmed that there is no deterioration at the top of the existing fuel supply duct, extending the repair burner piping 1 to the combustion chamber is unnecessary. For example, the modified example shown in Figure 8 can also be implemented.

The modified example shown in Figure 10 is an external joint. In the above embodiment, for example, it is assumed that an insertion pipe with an outer diameter of 50 mm is inserted into an existing fuel supply duct with a design inner diameter of 65 mm. From the viewpoint of ease of insertion, an internal structure is assumed (see Figure 3). However, if there is sufficient sizing in the existing fuel supply duct, an external structure as shown in the modified example may be used.

In the extrapolated structure, play is formed along the circumferential direction between the inner circumference of the joint and the outer circumference of the ceramic tube.

In the above embodiment, the repair of an existing coke oven fuel duct that has deteriorated over time is assumed. However, for example, the burner piping 1 may be pre-inserted into a newly installed coke oven fuel duct. When deterioration occurs after use, the burner piping can be replaced with new piping as appropriate.

1. Repair burner piping 10. Ceramic pipe 20. Ceramic joint 21. Joint insertion part 22. Pipe end face receiving part 25. Play 28. Heat-resistant packing 29. Heat-resistant putty 30. Metal pipe 40. Metal joint 50. Bellows pipe

Claims (10)

Coke oven burner piping inserted into the combustion gas duct of a coke oven,
The insertion tube is divided into multiple sections,
A joint provided between the aforementioned insertion tubes,
Includes,
Coke oven burner piping characterized by having circumferential play at the connection between the insertion pipe and the joint. The coke oven burner piping according to claim 1, characterized in that the aforementioned play is 2 to 12% of the diameter of the insertion pipe. The coke oven burner piping according to claim 1, further comprising a heat-resistant packing and heat-resistant putty disposed between the end face of the insertion pipe and the pipe end face receiving portion of the joint. The coke oven burner piping according to claim 1, characterized in that the insertion portion of the joint is inserted into the insertion pipe. The coke oven burner piping according to claim 1, characterized in that at least the uppermost of the multiple insertion tubes is made of ceramics. The coke oven burner piping according to claim 5, characterized in that the joint connected to the uppermost ceramic insertion tube is made of ceramic. The coke oven burner piping according to claim 1, characterized in that at least the lowest of the multiple insertion tubes is made of metal. The coke oven burner piping according to claim 7, characterized in that the joint connected to the lowermost metal insertion pipe is made of metal. A method for installing coke oven burner piping, comprising multiple divided insertion pipes and joints provided between the insertion pipes, wherein there is circumferential play at the connection between the insertion pipes and the joints,
The first insertion pipe is inserted into the combustion gas duct of the existing coke oven.
Insert the joint and the next insertion pipe while placing a heat-resistant packing and uncured heat-resistant putty between the end face of the insertion pipe and the pipe end face receiving portion of the joint.
The axial angle of the insertion tube is adjusted through the aforementioned play.
A method for installing coke oven burner piping, characterized by repeatedly inserting and connecting the aforementioned insertion pipe and joint. The method for installing coke oven burner piping according to claim 9, characterized in that the uncured heat-resistant putty hardens after the installation of the coke oven burner piping.