JP4851297B2 - Pyrolysis furnace tube inspection method - Google Patents

Description

  The present invention relates to a method for inspecting a pyrolysis furnace tube, and more particularly to a method capable of greatly reducing the number of days required for inspection.

  For example, when producing an olefinic compound, a diluent such as water vapor is added to a saturated hydrocarbon of ethane, propane, butane, pentane, naphtha or a mixture thereof and supplied to a pyrolysis furnace, and the olefinic compound is obtained by pyrolysis. Is obtained (Patent Literature 1, Patent Literature 2).

  For example, as shown in FIG. 5, in the above-described pyrolysis furnace, a plurality of U-shaped coil tubes 100B are passed over two large-diameter header tubes 100A that are parallel to each other, and both ends thereof communicate with the header tube 100A. There is known a system in which a pyrolysis furnace tube 100 is configured by connecting them, and a plurality of pyrolysis furnace tubes 100 are built in the furnace.

  When a new pyrolysis furnace is installed or an existing pyrolysis furnace tube is replaced, the header pipe 100A having a length of 10m to 15m is carried to the site of the pyrolysis furnace, and the header is opened from the opening in the pyrolysis furnace into the pyrolysis furnace. The pipe 100A is taken in and temporarily suspended in a mutually parallel posture, and both ends of a plurality of U-shaped coil tubes 100B are welded to the header pipe 100A as shown in FIGS. . In FIG. 7, 100C indicates a nozzle for connecting both ends of the coil tube 100B to the header tube 100A, and 100D indicates a welding point when the coil tube 100B is manufactured.

  By the way, since a high-pressure fluid such as saturated hydrocarbon flows in the pyrolysis furnace tube, it is necessary to inspect the product quality such as pressure resistance and airtightness after the pyrolysis furnace tube is assembled. Conventionally, when a pyrolysis furnace tube in a pyrolysis furnace is assembled, a metal plate is welded to both ends of the header pipe to seal the header pipe, and in that state, air is supplied into the header pipe, The assembly quality of the pyrolysis furnace tube was inspected from the fluctuation, and then the metal plate was removed.

Japanese Patent Laid-Open No. 09-53060 JP-A-62-218486

  However, in the conventional inspection method, it is necessary to perform inspection in a narrow and inferior environment in the pyrolysis furnace, which not only burdens the operator, but also requires days for the inspection, and the assembly of the pyrolysis furnace tube is completed The number of work days until the operation becomes longer, during which the operation of the pyrolysis furnace has to be stopped, and there is a problem that the product cannot be manufactured during that time.

  This invention makes it a subject to provide the inspection method of the pyrolysis furnace tube which enabled it to shorten the days which an inspection requires in view of this problem.

  The inventors of the present invention have studied various methods for assembling the pyrolysis furnace tube. As a result, a tube block in which the pyrolysis furnace tube is divided into a plurality of parts is manufactured at the factory, and these are transported to the pyrolysis furnace and taken into the pyrolysis furnace. As a result, an assembly method for assembling the pyrolysis furnace tube by connecting the single tubes for the header of the tube block to each other and constructing the header tube was developed.

  In the above assembly method, the pyrolysis furnace tube is divided into a plurality of tube blocks. Therefore, most of the quality inspection of the tube block, that is, the quality inspection of the pyrolysis furnace tube can be performed in the factory. Attention has been paid to the fact that quality inspection work can be greatly reduced.

  The method for inspecting a pyrolysis furnace tube according to the present invention is to manufacture a tube block by connecting both ends of a plurality of coil tubes to a header single tube, and weld the header single tubes of the plurality of tube blocks to each other. When assembling the pyrolysis furnace tube, the first test jig comprising the closing plate and the pressing cylinder is used, and both end openings of the single pipe for the header of each of the plurality of tube blocks are subjected to the first test jig. It is characterized in that the quality of the tube block is inspected by closing it with a tool and supplying air into the header single pipe to detect fluctuations in air pressure.

  One of the features of the present invention is that a tube for header of a plurality of tube blocks is closed at both ends with a first test jig, and air is supplied to the tube for header to detect fluctuations in air pressure. The block quality is inspected. As a result, most of the quality inspection of the pyrolysis furnace tube can be performed in the factory, and the burden on the operator can be greatly reduced.

  Also, the pyrolysis furnace tube inspection method according to the present invention is such that a tube block is manufactured by connecting both ends of a plurality of coil tubes to a header single tube, and the header single tubes of the plurality of tube blocks are welded to each other. When assembling the pyrolysis furnace tube by configuring the header pipe, the cylinder body loosely inserted into the header pipe and the outer peripheral surface of the cylindrical body are provided with a space between each other. Pyrolysis assembled using a second test jig comprising two annular seal members capable of sealing between the inner peripheral surface of the tube and an operating mechanism for expanding and reducing the diameter of the annular seal member Insert the second test jig into the header tube of the furnace tube, position the two seal members on both sides of the welded portion of the header single tube, and expand the diameter of the two seal members by the operating mechanism. Seal the space between the outer peripheral surface of the cylinder and the inner peripheral surface of the header tube, and inspect the quality of the pyrolysis furnace tube by detecting air pressure fluctuations by supplying air between the cylinder and the header tube. It is characterized by doing so.

  One of the features of the present invention is that a second test jig is inserted into the header tube of the assembled pyrolysis furnace tube, and the welded portion of the header tube is sandwiched between the tube and the header tube. The quality of the pyrolysis furnace tube is inspected by supplying air and detecting fluctuations in air pressure. As a result, the quality of the pyrolysis furnace tube can be inspected to assure the reliability of the assembly, and the quality inspection work in the narrow and inferior pyrolysis furnace can be reduced and the safety of the work can be improved.

  In addition, most of the quality inspection of the pyrolysis furnace tube can be carried out at the factory, resulting in fewer quality inspections in the pyrolysis furnace, resulting in fewer days required for quality inspection and a period of shutdown of the pyrolysis furnace. As a result of shortening, the decrease in the production amount of the product can be greatly reduced.

  Hereinafter, the present invention will be described in detail based on specific examples shown in the drawings. 1 to 4 show a preferred embodiment of a method for inspecting a pyrolysis furnace tube according to the present invention. The pyrolysis furnace tube 200 to which the inspection method of this example is applied spans a plurality of U-shaped coil tubes 200B between two parallel large-diameter header tubes 200A, and both ends of the header tube 200A The header pipe 200A is manufactured by welding a plurality of header single pipes 200A ′ to each other.

  When inspecting the pyrolysis furnace tube 200 of this example, as shown in FIG. 1 and FIG. 2 (a), the header single pipe 200A ′, that is, the length obtained by dividing the header pipe 200A into an appropriate length. Prepare the tube. As shown in FIG. 2B, the header single pipe 200A ′ is placed on a jig 300, and both ends of the header single pipe 200A ′ are placed on the floor by a restraining tool 310 including a chain and a tightening tool. Constrain and apply reverse strain that reduces the effects of weld distortion.

  In this state, the nozzles 200C are welded to a plurality of locations of the header single pipe 200A '. The nozzle 200C is a component for connecting both ends of the U-shaped coil tube 200B to the header single tube 200A '. When the welding operation is completed and the restraint of the restraint tool 310 is released, the reverse strain reduces the influence of the weld strain as shown in FIG.

  Thus, when the nozzle 200C is welded to the header single pipe 200A ′, as shown in FIG. 1B, the body portion of the coil tube 200B is welded and assembled, and the body portion is welded to the nozzle 200C. A tube block 200 shown in FIG. 1A is obtained.

  When the nozzle block 200C is welded to the header single pipe 200A 'during the production of the tube block 200, a welding test of the nozzle 200C is performed using the first test jig 400 as shown in FIG. The first test jig 400 includes a closing plate 400A and an air cylinder (pressing cylinder) 400B. In the welding inspection, the nozzle 200C is sealed with a plug 200E, the closing plate 400A is applied to the opening at both ends of the header single pipe 200A ′, the air cylinder (pressing cylinder) 400B is pressed and sealed, and the air supplied to the factory. Can be pressurized by a compressor and supplied into the single pipe for header 200A ′, and welding inspection of the nozzle 200C can be performed from fluctuations in air pressure.

  After the welding inspection of the nozzle 200C is completed, both ends of the coil tube 200B are welded to the nozzle 200C, and the coil tube 200B is connected to the header single pipe 200A ′. Thus, the tube block 200 is completed, and thus the plurality of coil tubes 200B are cured. Fix each other with tools to prevent damage during transportation.

  When the coil tube 200B is fixed, in the same manner as in the case of the welding inspection of the nozzle 200C, the two openings of the single header pipe 200A ′ are sealed by the closing plate 400A and the air cylinder 400B. Is supplied into the header single pipe 200A ′, and the quality of the tube block 200 is inspected from the fluctuation of the air pressure. The quality of the tube block 200 can be inspected by preliminarily determining the air pressure fluctuation when the welding is within the specified quality and comparing the pressure fluctuation of the supply air of the tube block 200 to be inspected.

  The assembly and quality inspection of the tube block 200 described above can be performed at a factory.

  When the tube block 200 is assembled, it is transported to the assembly site of the pyrolysis furnace. Depending on the size of the block, it is transported to the assembly site by truck, trailer or ship. At the assembly site, the tube block 200 is suspended and moved by a crane, for example, a mobile crane, and taken into the furnace through an opening opened in the ceiling of the pyrolysis furnace.

  Thus, the plurality of tube blocks 200 are taken into the pyrolysis furnace, the tube blocks 200 are laid out in the shape of the pyrolysis furnace tube 100 ′, and the header single pipes 200A ′ of the adjacent tube blocks 200 are welded to each other to form a header pipe. When 200A is manufactured, the pyrolysis furnace tube 100 ′ can be assembled.

  When the pyrolysis furnace tube 100 ′ is assembled, as shown in FIG. 4, the quality inspection of the welded portion of the header pipe 200 </ b> A is performed using the second test jig 500. In the second test jig 500, the ring plate 500B is fixed to the inner surfaces of both ends of the cylinder 500A that can be loosely inserted into the header tube 200A, that is, can be inserted with a gap, and the stop ring 500C is fixed to the outer peripheral surfaces of both ends. Has been.

  The retaining ring 500C is opposed to the receiving ring 500F, the opposing surfaces of the retaining ring 500C and the receiving ring 500F are inclined, and a rubber O-ring (seal member) 500G is disposed between the inclined surfaces. 500F is supported by a bolt 500E so as to be able to move forward and backward. The ring plate 500D is fixed to the ring plate 500B by bolts and nuts, and the O-ring 500G is expanded by the bolt 500E, the retaining ring 500C and the receiving ring 500F. An operating mechanism for reducing the diameter is configured.

  The second test jig 500 is loosely inserted into the header pipe 200A, and after the cylinder 500A is pushed to a position across the welded portion W of the header single pipe 200A ′, the bolts 500E are rotated at both ends of the cylinder 500A. When the receiving ring 500F is advanced with respect to the stop ring 500C, the O-ring 500G expands in diameter and comes into close contact with the inner surface of the header pipe 200A, thereby sealing the space including the welded portion W between the header pipe 200A and the cylinder 500A. be able to.

  Therefore, as in the case of the tube block 200, air can be supplied between the header pipe 200A and the cylinder 500A, and the welding quality of the header pipe 200A can be inspected from fluctuations in air pressure.

  As described above, according to the inspection method of this example, both ends of the header single tube 200A ′ of the tube block 200 are closed by the first test jig 400, and air is supplied to improve the quality from fluctuations in air pressure. Since the inspection is performed, most of the quality inspection of the pyrolysis furnace tube 100 ′ can be performed at the factory, and the burden on the operator can be greatly reduced.

  In addition, since the both end openings of the header pipe are not sealed by plate welding as in the prior art, the inspection work is easy.

  Further, the second test jig 500 is inserted into the header tube 200A of the pyrolysis furnace tube 100 ′, and the welded portion W of the header tube 200A is sealed between them. Since the quality of the part is inspected, the inspection in the narrow and poor pyrolysis furnace is easy, the burden on the operator is small, and the safety of the work can be improved.

  In addition, most of the quality inspection of the pyrolysis furnace tube 100 'can be performed at the factory, and as a result of fewer quality inspections in the pyrolysis furnace, the number of days required for quality inspection can be reduced, and the operation of the pyrolysis furnace can be stopped. As a result of shortening the period, it is possible to greatly reduce the decrease in the production amount of products due to the suspension of operations.

It is a figure for demonstrating the assembly method of the pyrolysis furnace tube to which the inspection method which concerns on this invention is applied. It is a figure for demonstrating the said assembly method. It is a schematic diagram for demonstrating one inspection method in preferable embodiment of the inspection method of the pyrolysis furnace tube which concerns on this invention. It is a figure which shows typically the other test | inspection method in the said embodiment. It is a figure which shows the structural example of a pyrolysis furnace. It is a figure which shows the conventional assembly method. It is a figure which shows the conventional assembly method.

Explanation of symbols

100 'pyrolysis furnace tube 200 tube block 200A header tube 200A' header single tube 200B coil tube 400 first test jig 400A closing plate 400B air cylinder (pressing cylinder)
500 Second test jig 500A Cylinder 500C Stop ring (operating mechanism)
500E bolt (operation mechanism)
500F receiving ring (operation mechanism)
500G O-ring (annular seal member)

Claims (2)

When assembling a pyrolysis furnace tube by connecting the both ends of a plurality of coil tubes to a single pipe for header and manufacturing a tube block and welding the single pipe for header of a plurality of tube blocks to each other,
Using a first test jig consisting of a closing plate and a pressing cylinder, both ends of the header single pipe of each of the plurality of tube blocks are closed with the first test jig, and air is supplied into the header single pipe. A method for inspecting a pyrolysis furnace tube, wherein the quality of the tube block is inspected by detecting fluctuations in air pressure. When assembling a pyrolysis furnace tube by connecting the both ends of a plurality of coil tubes to a single pipe for header and manufacturing a tube block and welding the single pipe for header of a plurality of tube blocks to each other,
A cylindrical body loosely inserted into the header pipe, and two annular rings which are provided on the outer peripheral surface of the cylindrical body with a space therebetween and can seal between the outer peripheral surface of the cylindrical body and the inner peripheral surface of the header pipe Using a second test jig comprising a seal member and an operation mechanism for expanding and reducing the diameter of the annular seal member,
The second test jig is inserted into the header tube of the assembled pyrolysis furnace tube, the two seal members are positioned on both sides of the welded portion of the single header tube, and the two seal members are operated by the operation mechanism. The tube is sealed between the outer peripheral surface of the cylindrical body and the inner peripheral surface of the header pipe, and air is supplied between the cylindrical body and the header pipe to detect fluctuations in the air pressure, thereby detecting the pyrolysis furnace tube. A method for inspecting a pyrolysis furnace tube, characterized in that the quality of the furnace is inspected.

Images