Measurement device and measurement method using said measurement device

Abstract

To allow for contactlessly and accurately measuring a distance between an upper opening of a reaction tube and solid particles filled in the reaction tube.SOLUTION: A measurement device for contactlessly measuring a distance between an upper opening of a reaction tube and solid particles filled in the reaction tube is provided, the measurement device comprising a laser length meter and a gas supply nozzle connected with the laser length meter to supply a gas into the reaction tube while irradiating inside the reaction tube with laser light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a measuring device for a reaction tube included in a multi-tubular reactor used in the field of petrochemical industry, and a measuring method using the measuring device. [Background technology]

[0002] In the petrochemical industry, multi-tubular reactors containing a large number of reaction tubes are commonly used. To ensure favorable reactions in multi-tubular reactors, it is important to ensure that the heights (packing heights) of solid particles, typically catalysts, packed in each of the reaction tubes are uniform within a predetermined range. If the packing heights of solid particles are not uniform among the reaction tubes, variations in the progress of the reaction among the reaction tubes may occur, resulting in a decrease in the overall reaction rate and yield. Therefore, a measurement method for measuring the packing height of solid particles packed in a reaction tube, i.e., the distance between the upper opening of the reaction tube and the solid particles packed in the reaction tube, and an apparatus applicable to this measurement method have been developed.

[0003] For example, in order to easily and quickly measure the distance from the opening of a reaction tube to solid particles filled in the reaction tube, a distance measuring device equipped with a parallel irradiation mechanism is used for non-contact measurement using laser light, microwaves, etc. (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-012158 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when measuring the distance to the solid particles filled in the reaction tube, conventional distance measuring devices including the distance measuring device disclosed in Patent Document 1 mentioned above sometimes make it difficult to perform accurate measurement due to dust and the like that is inevitably generated during measurement. The present inventors have conducted extensive research to solve the above-mentioned problems, and have found that the above-mentioned problems can be solved by using a measuring device including a gas supply nozzle for irradiating a reaction tube with a laser beam while supplying a gas into the reaction tube, thereby completing the present invention. [Means for solving the problem]

[0006] That is, the present invention provides the following [1] to

[10] . [1] A measuring device for non-contact measurement of the distance between an upper opening of a reaction tube and solid particles packed inside the reaction tube, comprising: A laser measuring instrument, a gas supply nozzle connected to the laser length measuring device for supplying gas into the reaction tube while irradiating the reaction tube with laser light; a measuring device comprising: [2] The measuring device according to [1], further comprising a plug for airtightly sealing an upper opening of the reaction tube in a state where at least a part of the gas supply nozzle is inserted into the reaction tube. [3] The measuring device according to [1] or [2], wherein the gas supply nozzle further includes a partition plate that transmits the laser light emitted from the laser length measuring device. [4] The measuring device according to [3], wherein the distance between the laser light emission surface of the laser length measuring device and the partition plate is 15 mm or less. [5] The measuring device according to any one of [1] to [4], wherein an inner wall of a nozzle portion of the gas supply nozzle is treated to make the laser light emitted from the laser length measuring device substantially non-reflecting. [6] Further including a gas supply source and a connecting pipe; The measuring device according to any one of [1] to [5], wherein the gas supply source is connected to the gas supply nozzle via the connecting pipe. [7] The measuring device according to [6], wherein the connecting pipe further includes a pressure gauge and a gas flow control valve for measuring the pressure drop caused by the solid particles packed in the reaction tube in a non-contact manner simultaneously with the distance. [8] The measuring device according to any one of [1] to [7], wherein the solid particles are at least one type selected from the group consisting of catalysts and inert substances. [9] Using the measurement device according to any one of [1] to [8], a distance between an upper opening of the reaction tube and solid particles packed in the reaction tube is measured in a non-contact manner while supplying a gas from the gas supply nozzle so that the gas linear velocity in the reaction tube becomes 0.01 m / sec or more.

[10] Using the measurement device according to any one of [1] to [8], at least a part of the gas supply nozzle is inserted into the reaction tube, and the distance between an upper opening of the reaction tube and solid particles filled in the reaction tube is measured in a non-contact manner. [Effects of the Invention]

[0007] According to the measuring device of the present invention and the measuring method using the measuring device, the distance between the upper opening of a reaction tube and the solid particles filled inside the reaction tube can be measured in a non-contact manner with high accuracy and efficiency, which can contribute to accurate and rapid implementation of filling (renewal work) of solid particles in a multi-tubular reactor. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram for explaining the configuration of the measurement device of this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the measurement device of this embodiment in a see-through manner from above to explain the positional relationship of the components thereof. [Figure 3] FIG. 3 is a schematic diagram showing components of the measuring device of this embodiment in a see-through manner from the side. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings merely show the shapes, sizes, and arrangements of components in a schematic manner to the extent that the invention can be understood. The present invention is not limited by the following description, and each component can be modified as appropriate without departing from the gist of the present invention. Furthermore, the configuration according to the embodiments of the present invention is not necessarily manufactured or used in the arrangement shown in the drawings.

[0010] <Configuration example> The measuring device according to this embodiment is a measuring device for measuring the distance between the upper opening of a reaction tube and the solid particles filled inside the reaction tube in a non-contact manner, and includes a laser distance measuring device and a gas supply nozzle which is connected to the laser distance measuring device and which supplies a gas into the reaction tube and irradiates the reaction tube with a laser beam.

[0011] Here, the reaction tube to which the measuring device of this embodiment is applied is specifically, for example, a reaction tube that can be contained in large numbers in a general fixed-bed multi-tubular reactor used in the petrochemical industry. Typically, several thousand to several tens of thousands of reaction tubes can be contained in one multi-tubular reactor. The outer diameter of such a reaction tube is usually about 10 to 60 mm, the wall thickness of the reaction tube, i.e., the difference between the outer diameter and the inner diameter of the reaction tube, is usually about 1 to 5 mm, and the length of the reaction tube is usually about 0.3 to 10 m. The material constituting the reaction tube is not particularly limited. The reaction tube can be made of any suitable conventionally known material, such as carbon steel or stainless steel.

[0012] In this embodiment, the solid particles to be measured, i.e., the solid particles filled in the reaction tube during measurement, are at least one type selected from the group consisting of catalysts and inert substances. The catalysts among the solid particles to be measured are not particularly limited. Specific examples of such catalysts include catalysts for producing unsaturated aldehydes and unsaturated carboxylic acids, catalysts for producing unsaturated carboxylic acids, catalysts for producing unsaturated nitriles, hydrogenation catalysts, and catalysts for producing chlorine. Among these, it is preferable to measure catalysts for producing unsaturated aldehydes and unsaturated carboxylic acids and catalysts for producing unsaturated carboxylic acids.

[0013] Examples of the catalyst for producing the unsaturated aldehyde and unsaturated carboxylic acid include a catalyst for producing acrolein and acrylic acid by gas-phase catalytic oxidation of propylene with molecular oxygen, and a catalyst for producing methacrolein and methacrylic acid by gas-phase catalytic oxidation of isobutylene or tert-butyl alcohol with molecular oxygen.

[0014] Examples of the catalyst for producing an unsaturated carboxylic acid include a catalyst for producing acrylic acid by gas-phase catalytic oxidation of propane with molecular oxygen, a catalyst for producing acrylic acid by gas-phase catalytic oxidation of acrolein with molecular oxygen, and a catalyst for producing methacrylic acid by gas-phase catalytic oxidation of methacrolein with molecular oxygen.

[0015] Examples of the catalyst for producing unsaturated nitriles include a catalyst for producing acrylonitrile by gas-phase catalytic ammoxidation of propylene or propane with molecular oxygen and ammonia, and a catalyst for producing methacrylonitrile by gas-phase catalytic ammoxidation of isobutylene or tert-butyl alcohol with molecular oxygen and ammonia.

[0016] Examples of the hydrotreating catalyst include a catalyst for removing or reducing the concentration of sulfur compounds and / or nitrogen compounds contained in petroleum fractions by reacting the sulfur compounds and / or nitrogen compounds with hydrogen, and / or a hydrocracking catalyst for lightening heavy oil.

[0017] The catalyst for producing chlorine includes, for example, a catalyst for producing chlorine from hydrogen chloride and oxygen.

[0018] The inert substance among the solid particles to be measured is not particularly limited. Specific examples of the inert substance include ceramics such as alumina, silicon carbide, and zirconia, stainless steel, and iron. Of these, ceramics and stainless steel are preferably used as the measurement targets.

[0019] In this embodiment, the shape of the catalyst or inert substance as solid particles is not particularly limited. The shape of the catalyst or inert substance may be, for example, cylindrical, spherical, or ring-shaped. The bulk density of the catalyst or inert substance is usually 0.8 to 1.5 g / mL, and preferably 0.8 to 1.3 g / mL.

[0020] First, with reference to FIGS. 1 to 3, a specific configuration example of the measurement device 1 and the gas supply source 40 of this embodiment will be described. FIG. 1 is a block diagram for explaining the configuration of the measurement device, FIG. 2 is a schematic diagram showing the components of the measurement device in a transparent manner from above to explain the positional relationship between the components, and FIG. 3 is a schematic diagram showing the components of the measurement device in a transparent manner from the side.

[0021] 1 to 3, the measuring device 1 of this embodiment includes a laser distance measuring device 10, a gas supply nozzle 20 connected to the laser distance measuring device, and a connecting pipe 30 connected to the gas supply nozzle 20. In this embodiment, the measuring device 1 is connected to a gas supply source 40 by the gas supply nozzle connecting pipe 30. This will be explained in detail below.

[0022] 1. Measurement equipment (1) Laser length measuring instrument In this embodiment, the wavelength of the laser light emitted by the laser length measuring device 10 included in the measuring device 1 is not particularly limited. Any suitable conventionally known laser length measuring device can be used as the laser length measuring device 10. Examples of commercially available laser length measuring devices that can be suitably used in this embodiment include the LR-TB5000 (laser light wavelength: 660 nm) manufactured by Keyence Corporation, the TOF-L450DN (laser light wavelength: 650 nm) manufactured by Optex FA, and the SA1F-12V (laser light wavelength: 660 nm) manufactured by IDEC Corporation.

[0023] (2) Gas supply nozzle In this embodiment, the gas supply nozzle 20 has a joint portion 22 that can be fixedly connected to support the laser length measuring device 10, can be connected to a connecting pipe 30, and can also be connected to a nozzle portion 24.

[0024] In this embodiment, the joint portion 22 is a short, tubular body. The material, shape, size, and other properties of the joint portion 22 are not particularly limited, provided that they are functional. The joint portion 22 may be formed from, for example, aluminum, iron, stainless steel, or a resin such as acrylonitrile-butadiene-styrene copolymer (ABS), polyphenylene sulfide (PPS), or polyacetal. The inner wall or the entire joint portion may be treated with black anodizing, iron oxide coating, black trivalent chromate coating, or black paint. The joint portion 22 may be integrally formed with the hose connection portion 23 and nozzle portion 24, which will be described later, provided that the purpose of the present invention is not impaired.

[0025] A partition plate 28 that can transmit the laser light emitted from the laser length measuring device 10 is provided at the upper opening of the joint part 22. The partition plate 28 is arranged so that the center (axis) C of the diameter of the upper opening of the cylindrical joint part 22 coincides with the center (axis) C of the partition plate 28 when viewed in the thickness direction, and is fixed so as to airtightly seal the upper opening of the joint part 22 without any gaps.

[0026] The partition plate 28 may be fixed by any suitable means known in the art, such as adhesive, sealing tape, packing, gasket, O-ring, or a combination thereof.

[0027] The partition plate 28 can be made of any suitable material known in the art, provided that it does not impair the required functions, such as being able to transmit the laser light emitted by the selected laser length measuring device 10 and not allowing the gas supplied from the gas supply source 40 to pass through.

[0028] Specifically, the partition plate 28 can be made of, for example, quartz, glass, or a transparent resin such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), vinyl chloride, or polycarbonate. From the viewpoints of laser light transmittance, scratch resistance, availability, and the like commonly used in this technical field, the partition plate 28 is preferably made of quartz or PMMA. From the viewpoint of scratch resistance in particular, the partition plate 28 is more preferably made of quartz.

[0029] The shape, size (outer diameter and inner diameter), etc. of the partition plate 28 are not particularly limited as long as they do not impair the object and effects of the present invention. The shape, size (outer diameter and inner diameter), etc. of the partition plate 28 can be appropriately selected according to, for example, the diameter of the upper opening of the reaction tube and the selected laser length measuring device 10.

[0030] The distance w1 between the laser light emission surface 12 and the partition plate 28 (the laser light incidence surface, which is the upper surface of the partition plate 28) in the laser length measuring device 10 is typically 15 mm or less, and from the viewpoint of improving sensitivity and improving the accuracy of distance measurement, it is more preferably 12 mm or less, even more preferably 8 mm or less, even more preferably 5 mm or less, and particularly preferably 3 mm or less.

[0031] The nozzle part 24 is connected to the opening at the lower end of the cylindrical joint part 22 so as to be airtightly sealed with no gap between them. The nozzle part 24 is a cylindrical body having a diameter smaller than that of the reaction tube, and being longer than the joint part 22 but shorter than the reaction tube.

[0032] There are no particular limitations on the material, size (outer diameter, inner diameter, length), etc. of the joint part 22, provided that the object and effect of the present invention are not impaired. The size of the joint part 22 in particular can be designed, for example, to match the size (outer diameter and inner diameter) of the upper end of the nozzle part 24 that is connected to the joint part 22.

[0033] At least a part of the nozzle part 24 on the side of its lower opening, which is opposite to its upper opening connected to the joint part 22, is inserted into the reaction tube during use. The nozzle part 24, when inserted into the reaction tube, has the functions of guiding a laser beam emitted from the laser length measuring device 10 into the reaction tube via the partition plate 28 and the joint part 22, and further supplying a gas supplied from a gas supply source 40 into the reaction tube via the connecting pipe 30 and further the joint part 22.

[0034] The material, size (inner diameter, outer diameter, length) and the like of the nozzle part 24 are not particularly limited as long as they do not impair the object and effects of the present invention. The size of the nozzle part 24 can be appropriately set in consideration of, for example, the inner diameter of the upper opening of the reaction tube, an expected measurement distance, i.e., an expected distance from the upper opening of the reaction tube to the solid particles in the reaction tube, and the like.

[0035] The outer diameter (and inner diameter) of the nozzle part 24 is set to be smaller than the inner diameter of the reaction tube. The difference between the inner diameter of the reaction tube and the outer diameter of the nozzle part 24 is usually 0.5 mm or more and 10 mm or less, and from the viewpoint of improving operability, measurement accuracy, etc., it is preferably 0.5 mm or more and 1 mm or less, and more preferably about 0.5 mm.

[0036] The length of a part of the nozzle part 24 inserted into the reaction tube during use, i.e., the length from the lower opening of the nozzle part 24 to the upper opening of the reaction tube during use, can be determined taking into consideration the (anticipated) distance from the upper opening of the reaction tube to the solid particles, etc. For example, when the distance from the upper opening of the reaction tube to the solid particles is 300 mm or more and the measurable distance of the laser length measuring device 10 is 60 mm or more, the length from the lower opening of the nozzle part 24 to the upper opening of the reaction tube is usually 60 mm or more and 1000 mm or less, and preferably about 240 mm.

[0037] Examples of materials for the nozzle 24 include metals such as aluminum, iron, and stainless steel, as well as resin materials such as acrylonitrile-butadiene-styrene copolymer synthetic resin (ABS), polyphenylene sulfide (PPS) resin, and polyacetal.

[0038] A part of the gas supply nozzle 20, more specifically, at least the inner wall of the cylindrical nozzle portion 24, is preferably treated to make the laser light emitted from the laser length measuring device 10 substantially non-reflective. The treatment to make the laser light substantially non-reflective may be applied to the entire surface of the nozzle portion 24, or the nozzle portion 24 itself may be made of a material that can make the laser light substantially non-reflective.

[0039] Examples of treatments for making the laser beam substantially non-reflective include black anodizing, iron oxide coating, black trivalent chromate treatment, and black painting. The treatment for making the laser beam substantially non-reflective may be determined taking into consideration the characteristics of the material of the nozzle portion 24 and the wavelength of the laser beam, for example.

[0040] In this way, by applying a treatment to at least the inner wall of the nozzle portion 24 to make the laser light substantially non-reflective, distance measurements can be performed more accurately, and the inner diameter of the nozzle portion 24 can be made smaller, making the nozzle portion 24 and ultimately the measuring device 1 more compact and easier to handle.

[0041] A stopper part 26 is provided on the outer wall of the nozzle part 24, surrounding a part of the outer wall in a doughnut shape and fixed to the outer wall. The stopper part 26 is a member for airtightly sealing the gap between the upper opening of the reaction tube and the inserted nozzle part 24. The stopper part 26 is preferably configured to be movable in the extending direction of the nozzle part 24 and to be fixed at any position in order to adjust the expected measurement distance and the length of the nozzle part 24 inserted into the reaction tube during use.

[0042] The shape of the stopper part 26 is not particularly limited as long as it can perform the required function. In this embodiment, the stopper part 26 has a tapered shape that tapers toward the side (lower end) that is inserted into the reaction tube when fixed to the outer wall of the nozzle part 24. With this configuration, the length of the inserted part of the nozzle part 24 can be set to a predetermined length, and the measuring device 1 can be easily installed.

[0043] The size of the stopper part 26 can be determined in consideration of the inner diameter of the reaction tube, the outer diameter of the nozzle part 24, the overall length of the nozzle part 24, the length of the part of the nozzle part 24 which is inserted into the reaction tube, the size of the region of the stopper part 26 which is inserted into the reaction tube, etc.

[0044] There are no particular limitations on the material of the stopper 26. The stopper 26 can be made of any suitable conventionally known material, such as silicone rubber, natural rubber, synthetic rubber, or fluororubber.

[0045] The nozzle part 24 and the joint part 22 are connected so that the gap between the nozzle part 24 and the joint part 22 is airtightly sealed without any gaps. When connecting the nozzle part 24 and the joint part 22, any suitable conventionally known member for airtight sealing, such as a packing, a sealing tape, a gasket, an O-ring, or an adhesive, may be further used, if necessary.

[0046] A hose connection part 23 for connecting the connecting pipe 30 is provided on the side of the joint part 22, i.e., in a region midway along the extension direction of the cylindrical body. The hose connection part 23 can be made of any suitable conventionally known material. The diameter of the hose connection part 23 can be set taking into consideration, for example, the required gas flow rate and the inner diameter of the hose 32a (32) to be connected.

[0047] The connecting pipe 30 is configured to connect the gas supply source 40 and the gas supply nozzle 20 via the connecting pipe 30, and may further include a pressure gauge 34 and a gas flow rate control valve 36 for measuring the pressure drop caused by the solid particles filled in the reaction tube and the distance between the upper opening of the reaction tube and the solid particles (catalyst (catalyst layer)) in the reaction tube simultaneously in a non-contact manner.

[0048] Specifically, the connecting pipe 30 includes a tubular pipe to which a pressure reducing valve and a gas flow control valve 36 (not shown) are connected, and to which a pressure gauge 34 is also connected. Any suitable tubular pipe known in the art can be used for this piping. From the viewpoints of mechanical strength and prevention of contamination by foreign matter such as rust, this piping is preferably made of, for example, stainless steel or aluminum.

[0049] In this embodiment, a pressure gauge 34 is connected to this piping closer to the hose connection part 23 and the hose 32a, and a gas flow control valve 36 is connected to this piping closer to the gas supply source 40 and the hose 32b.

[0050] The pressure reducing valve, pressure gauge 34, and gas flow rate adjusting valve 36 that may be included in the connecting pipe 30 may be selected from any suitable conventionally known devices.

[0051] As the pressure reducing valve, for example, an air regulator (RP-1000 manufactured by CKD Corporation) can be used.

[0052] For example, a mass flow type, float type, or orifice type gas flow control valve can be used as the gas flow control valve 36. For example, a mass flow type mass flow controller (SEC-E431X, manufactured by Horiba STEC Co., Ltd.) can be used as the gas flow control valve 36.

[0053] Since the connecting pipe 30 further includes a pressure gauge 34 and a gas flow control valve 36, the pressure loss due to the solid particles filled in the reaction tube can be measured in a non-contact manner, simultaneously with the distance.

[0054] The connecting pipe 30 includes two hoses 32 (32a and 32b) connected to both ends of the piping. The hoses 32 can be made of any suitable conventional material such as rubber, silicone rubber, or polyvinyl chloride, depending on the pressure applied by the gas supply source 40. The materials and structures of the two hoses 32a and 32b may be the same or different.

[0055] In this embodiment, a hose 32a is connected to the hose connection portion 26 of the gas supply nozzle 20, and a hose 32b is connected to a cylinder which is a gas supply source 40.

[0056] 2. Gas supply source The gas supply source 40 may be any suitable conventional gas supply means filled with a gas to be supplied into the reaction tube when measuring the height (filling height) of the catalyst layer formed by the packed catalyst, for example, a cylinder filled with a desired gas. The capacity, shape, size, etc. of the cylinder may be appropriately selected taking into consideration the height of the catalyst layer, the diameter, length, number, etc. of the reaction tube. Alternatively, a gas supply means filled with a compressed gas using a compression device such as a compressor or a bebicon may be used.

[0057] In this embodiment, examples of the gas filled in the cylinder used as the gas supply source 40 include dry air and inert gases such as nitrogen gas and argon gas. As the gas used by filling the cylinder serving as the gas supply source 40, it is preferable to use dry air, since it is easy to obtain and handle. Here, "dry air" means air that has been adjusted to at least reduce the moisture content, and specifically, for example, air with a moisture content of 0.119 g / m 3 (Based on atmospheric pressure dew point of -40°C)

[0058] <Measurement method> The measuring method of this embodiment is a measuring method using the measuring apparatus 1 already explained, in which the distance between the upper opening of the reaction tube and the solid particles packed in the reaction tube is measured in a non-contact manner while supplying a gas from the gas supply nozzle 20 so that the gas linear velocity in the reaction tube becomes 0.01 m / sec or more.

[0059] To carry out the measurement method of this embodiment, first, the previously described measurement device 1 is prepared. At this time, the coaxiality of the outer diameter of the gas supply nozzle 20 with respect to the central axis C of the laser beam of the laser length measuring device 10 is adjusted to 0.1 mm or less.

[0060] Next, the measurement device 1 and the gas supply source 40 are connected to each other via the connecting pipe 30 and adjusted so that measurements can be performed.

[0061] Next, at least a part of the gas supply nozzle 20 is inserted into the reaction tube, and the distance between the upper opening of the reaction tube and the solid particles packed in the reaction tube is measured in a non-contact manner.

[0062] Specifically, in the measurement, first, at least a part of the nozzle part 24 of the gas supply nozzle 20 is inserted into the reaction tube, and the gas supply nozzle 20 is fixed to the reaction tube while airtightly sealing the upper opening of the reaction tube with the stopper part 26. At this time, it is preferable to fix the gas supply nozzle 20 so that the central axis of the reaction tube coincides with the center (axis) C of the gas supply nozzle 20 (center C of the inner diameter of the nozzle part 24).

[0063] Next, the gas is supplied into the reaction tube by adjusting the linear velocity of the gas in the reaction tube to be 0.01 m / sec or more using a pressure reducing valve, a pressure gauge 34 and a gas flow control valve 36 provided on the connecting pipe 30, and the distance between the upper opening of the reaction tube and the solid particles filled in the reaction tube is measured in a non-contact manner using the laser length measuring device 10 while suppressing or preventing generation of dust in the reaction tube due to the solid particles.

[0064] Here, the gas linear velocity will be explained. In this embodiment, the "gas linear velocity" refers to the gas linear velocity in the region of the reaction tube that is not filled with solid particles.

[0065] In this embodiment, for example, if the selected gas flow control valve 36 is a mass flow type, the mass flow rate is adjusted by the gas flow control valve 36. In this case, the mass flow rate over the entire region in the reaction tube becomes equivalent to the mass flow rate that can be measured near the gas flow control valve 36, and therefore the gas linear velocity can be adjusted by adjusting the mass flow rate by the gas flow control valve 36. Furthermore, for example, if the selected gas flow control valve 36 is a float type or an orifice type, the volumetric flow rate is adjusted by the gas flow control valve 36. In this case, the volumetric flow rate near the gas flow control valve 36 is converted into the gas linear velocity in the reaction tube taking into account the size of the reaction tube, thereby calculating the gas linear velocity, and the gas linear velocity can be adjusted based on the calculated gas linear velocity.

[0066] The linear velocity of the gas in the reaction tube is set to 0.01 m / sec or more. From the viewpoint of effectively suppressing or preventing the generation of dust in the reaction tube due to solid particles during measurement, the linear velocity of the gas is preferably set to 0.01 m / sec or more, more preferably 0.1 m / sec or more, and is preferably set to 20 m / sec or less, more preferably 10 m / sec or less, and is preferably set to 0.01 m / sec or more and 20 m / sec or less, and more preferably 0.1 m / sec or more and 10 m / sec or less.

[0067] According to the measuring method of this embodiment having the above-mentioned aspect, generation of dust in the reaction tube due to solid particles during measurement can be effectively suppressed or prevented, and therefore, sensitivity can be further improved, and consequently, measurement accuracy of the distance between the upper opening of the reaction tube and the solid particles (catalyst (catalyst layer)) can be further improved. Furthermore, according to the measuring method of this embodiment, measurement efficiency can be further improved in measurements of a plurality of reaction tubes, and pressure loss can be measured simultaneously with distance measurement, thereby enabling measurement of pressure loss (packing density) in the reaction tubes. Therefore, efficiency of catalyst renewal work in a multi-tubular reactor can be significantly improved, and consequently, this can contribute to improvement of production efficiency of products produced in a multi-tubular reactor and reduction of production costs. [Example]

[0068] The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples.

[0069] <Measuring equipment> In this example, the laser length measuring instrument 10 used was an LR-TB5000 (laser light wavelength: 660 nm) manufactured by Keyence Corporation. As the gas supply source 40, dry air was used, which was obtained by compressing atmospheric air using a compressor and drying it in a dehumidifier to a dew point of −40° C. or less at atmospheric pressure. The nozzle portion 24 of the gas supply nozzle 20 was an aluminum tube having an outer diameter of 20 mm, an inner diameter of 16 mm, and a length of 300 mm, the inner wall of which was treated with black anodizing, a process to make the laser light emitted from the laser length measuring device 10 substantially non-reflective.

[0070] A plug 26 made of silicone rubber was provided on the outer wall of the nozzle part 24 near the upper end opening thereof to airtightly seal the gap between the outer wall of the nozzle part 24 and the inner wall of the reaction tube when the nozzle part 24 was inserted into the reaction tube.

[0071] In this example, a gas supply nozzle 20 was used in which a disk-shaped quartz glass partition plate 28 having a visible light transmittance of approximately 92%, a diameter of 25 mm, and a thickness of 3 mm was fitted into the upper opening of a short tubular joint portion 22 made of aluminum, the entirety of which, including the inner wall, was black anodized, so as to seal the upper opening airtight without any gaps with a silicone rubber packing, a nozzle portion 24 was connected to the lower opening of joint portion 22 so as to be airtightly sealed with joint portion 22 without any gaps, a hose connection portion 23 having an inner diameter of 6 mm was provided on the side of joint portion 22, the gap between nozzle portion 24 and joint portion 22 was sealed with a silicone rubber packing, and the gap between joint portion 22 and hose connection portion 23 was airtightly sealed without any gaps with sealing tape.

[0072] The connecting pipe used was a connecting pipe 30 in which the pressure reducing valve and the gas flow control valve 36 were connected by a stainless steel pipe with an inner diameter of 9 mm, and rubber hoses 32 were connected to both ends of the stainless steel pipe.

[0073] An air regulator (RP-1000, manufactured by CKD) was used as the pressure reducing valve. As the gas flow rate control valve 36, a mass flow controller (SEC-E431X, manufactured by Horiba Estec Co., Ltd.) was used.

[0074] First, the rubber hose 32 (32b) on the gas flow control valve 36 side of the connecting pipe 30 was connected to the cylinder, which was the gas supply source 40, and then the rubber hose 32 (32a) on the pressure reducing valve side of the connecting pipe 30 was connected to the hose connection part 26 of the gas supply nozzle 20.

[0075] The laser length measuring device 10 was connected to the joint portion 22 of the gas supply nozzle 20 so that the laser light emitted from the laser length measuring device 10 passed near the center C of the inner diameter of the nozzle portion 24 via the partition plate 28 provided on the gas supply nozzle 20. Here, the laser length measuring device 10 and the gas supply nozzle 20 were connected so that the distance between the center of the laser projection portion (laser light emission surface) of the laser length measuring device 10 and the upper surface (exposed surface) of the partition plate 28 was 3 mm, and a measuring device 1 was prepared.

[0076] Example 1 A carbon steel reaction tube with an inner diameter of 25 mm and a length of 4620 mm was fixed vertically so that the length direction was aligned with the vertical direction, and then an oxide catalyst containing bismuth, molybdenum, and iron was filled into the reaction tube from the upper opening to form a catalyst layer inside the reaction tube.

[0077] First, for comparison, the distance from the upper opening of the reaction tube to the upper end of the catalyst layer was measured using a tape measure.

[0078] Next, the lower 240 mm portion of the nozzle part 24 of the gas supply nozzle 20 of the measuring device 1 described above was inserted into the reaction tube, and then the distance from the upper opening of the reaction tube to the upper end of the catalyst layer was measured in a non-contact manner by irradiating it with a laser beam.

[0079] At this time, the sensitivity of the laser length measuring device 10 was set to "High." Dry air was supplied from the gas supply source 40 to the gas supply nozzle 20 so that the gas linear velocity in the reaction tube became 1.1 m / sec.

[0080] The above-described measurement was carried out five times while changing the packed height of the catalyst layer formed by the oxide catalyst packed in the reaction tube.

[0081] The absolute value of the distance difference was calculated, which is the difference (absolute value) between the measurement value using the tape measure and the measurement value using the measuring device 1. The results are shown in Table 1 below.

[0082] <Example 2> A stainless steel reaction tube with an inner diameter of 30 mm and a length of 5000 mm was fixed vertically so that the length direction was aligned with the vertical direction, and then an oxide catalyst containing molybdenum and phosphorus was filled into the reaction tube from the upper opening to form a catalyst layer inside the reaction tube.

[0083] First, for comparison, a tape measure was used to measure the distance from the upper opening of the reaction tube to the upper end of the catalyst layer (this distance is referred to as the tape measure measurement distance). Next, the lower 240 mm portion of the nozzle part 24 of the gas supply nozzle 20 of the measuring device 1 described above was inserted into the reaction tube, and then the distance from the upper opening of the reaction tube to the upper end of the catalyst layer was measured in a non-contact manner by irradiating it with a laser beam (this distance is referred to as the non-contact measurement distance).

[0084] At this time, the sensitivity of the laser length measuring device 10 was set to "High." Dry air was supplied from the gas supply source 40 to the gas supply nozzle 20 so that the gas linear velocity in the reaction tube was 0.75 m / sec. The above measurement was carried out five times while changing the amount of oxide catalyst packed in the reaction tube, that is, the packed height of the catalyst layer.

[0085] The absolute value of the distance difference was calculated, which is the difference (absolute value) between the measurement value using the tape measure and the measurement value using the measuring device 1. The results are shown in Table 1 below.

[0086] <Reference example 1> The distance from the upper opening of the reaction tube to the upper end of the catalyst layer was measured and the absolute value of the difference in distance was calculated in the same manner as in Example 1, except that when the measurement device 1 was used, dry air was not supplied from the gas supply source 40 to the gas supply nozzle 20. The results are shown in Table 1 below.

[0087] [Table 1]

[0088] Example 3 A stainless steel reaction tube with an inner diameter of 30 mm and a length of 5000 mm was fixed vertically so that the length direction was aligned with the vertical direction, and then an oxide catalyst containing molybdenum and phosphorus was filled into the reaction tube from the upper opening to form a catalyst layer inside the reaction tube.

[0089] First, for comparison, the distance from the upper opening of the reaction tube to the upper end of the catalyst layer was measured using a tape measure. Next, the lower 240 mm portion of the nozzle part 24 of the gas supply nozzle 20 of the measuring device 1 described above was inserted into the reaction tube, and then the distance from the upper opening of the reaction tube to the upper end of the catalyst layer was measured in a non-contact manner by irradiating it with a laser beam.

[0090] At this time, the sensitivity of the laser distance measuring device 10 was set to "High." Dry air was supplied from the gas supply source 40 to the gas supply nozzle 20 so that the linear gas velocity in the reaction tube was 1.2 m / sec, and the absolute value of the distance difference was calculated. The results are shown in Table 2 below.

[0091] Example 4 The distance from the upper opening of the reaction tube to the upper end of the catalyst layer was measured and the absolute value of the distance difference was calculated in the same manner as in Example 3, except that dry air was supplied from the gas supply source 40 to the gas supply nozzle 20 so that the gas linear velocity in the reaction tube was 0.02 m / sec. The results are shown in Table 2 below.

[0092] <Reference example 2> The distance from the upper opening of the reaction tube to the upper end of the catalyst layer was measured and the absolute value of the distance difference was calculated in the same manner as in Example 3, except that dry air was supplied from the gas supply source 40 to the gas supply nozzle 20 so that the gas linear velocity in the reaction tube was 0.002 m / sec. The results are shown in Table 2 below.

[0093] [Table 2]

[0094] <Example 5> The measuring device 1 used had a digital differential pressure gauge (GC50, manufactured by Nagano Keiki) further connected as a pressure gauge to the downstream side of the gas flow control valve 36 of the connecting pipe 30 (the side closer to the gas supply nozzle 20).

[0095] A stainless steel reaction tube with an inner diameter of 30 mm and a length of 5000 mm was fixed vertically so that the length direction was aligned with the vertical direction, and then an oxide catalyst containing molybdenum and phosphorus was filled into the reaction tube from the upper opening to form a catalyst layer inside the reaction tube.

[0096] First, for comparison, the distance from the upper opening of the reaction tube to the upper end of the catalyst layer was measured using a tape measure.

[0097] Next, a lower 240 mm portion of the nozzle part 24 of the gas supply nozzle 20 of the measuring apparatus 1 described above was inserted into the reaction tube, and then the pressure drop in the reaction tube was measured while measuring the distance from the upper opening of the reaction tube to the upper end of the catalyst layer in a non-contact manner by irradiating it with a laser beam.

[0098] At this time, the sensitivity of the laser length measuring device 10 was set to "High." Dry air was supplied from the gas supply source 40 to the gas supply nozzle 20 so that the gas linear velocity in the reaction tube was 0.37 m / sec, 0.75 m / sec, or 1.2 m / sec. The results are shown in Table 3 below.

[0099] [Table 3]

[0100] According to the Fanning equation, which is generally used to calculate pressure loss in piping, it is known that pressure loss (ΔP) is ideally proportional to the square of the linear gas velocity.

[0101] Whether or not the pressure drop is accurately measured is determined by measuring the pressure drop at a plurality of gas linear velocities and determining the degree of proportionality between the pressure drop and the square of the gas linear velocity. According to Example 5, the proportionality is good and ideal. Therefore, according to Example 5, it can be said that the differential pressure (density) of the catalyst packed in the reaction tube was also accurately measured simultaneously with the distance measurement. [Explanation of symbols]

[0102] 1. Measuring equipment 10 Laser length measuring device 12. Exit surface 20 Gas supply nozzle 22 Joint 23 Hose connection 24 Nozzle section 26 Plug part 28 Partition 30 Connecting pipe 32(32a, 32b) Hose 34 Pressure gauge 36 Gas flow control valve 40 Gas supply source

Claims

1. A measuring device for measuring the distance between an upper opening of a reaction tube and solid particles filled inside the reaction tube in a non-contact manner, comprising: A laser measuring instrument, a gas supply nozzle fixedly connected to support the laser length-measuring device, for irradiating the reaction tube with laser light while supplying gas into the reaction tube, the gas supply nozzle comprising: a partition plate that transmits the laser light emitted from the laser length-measuring device; a cylindrical joint portion connected to an upper opening so that the partition plate is provided thereto and having a hose connection portion provided on a side thereof; and a nozzle portion connected to a lower opening of the joint portion; a plug for airtightly sealing an upper opening of the reaction tube in a state where at least a portion of the gas supply nozzle is inserted into the reaction tube; and a gas source; a connecting pipe; the gas supply source is connected to the hose connection portion of the gas supply nozzle via the connecting pipe; the connecting pipe further includes a pressure gauge and a gas flow control valve for measuring a pressure drop caused by solid particles filled in the reaction tube in a non-contact manner simultaneously with the distance.

2. 2. The measuring device according to claim 1, wherein the gas supply nozzle further includes a partition plate that transmits the laser light emitted from the laser length measuring device.

3. 3. The measuring device according to claim 2, wherein the separation distance between the laser light emission surface of the laser length measuring device and the partition plate is 15 mm or less.

4. 4. The measuring device according to claim 1, wherein an inner wall of a nozzle portion of the gas supply nozzle is treated to make the laser light emitted from the laser length measuring device substantially non-reflective.

5. 5. The measuring device according to claim 1, wherein the solid particles are at least one kind selected from the group consisting of catalysts and inert substances.

6. Using the measuring device according to any one of claims 1 to 5, a distance between an upper opening of the reaction tube and solid particles packed in the reaction tube and a pressure loss are simultaneously measured in a non-contact manner while supplying a gas through the gas supply nozzle so that a gas linear velocity in the reaction tube becomes 0.01 m / sec or more.

7. Using the measuring device according to any one of claims 1 to 5, at least a part of the gas supply nozzle is inserted into the reaction tube, and a distance between an upper opening of the reaction tube and solid particles packed in the reaction tube and a pressure drop are simultaneously measured in a non-contact manner.

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