JP7757193B2 - Measurement device and measurement method using said measurement device - Google Patents

Description

The present invention relates to a measurement device for reaction tubes included in multi-tubular reactors used in the petrochemical industry, and a measurement method using the measurement device.

In the petrochemical industry, multi-tubular reactors containing multiple reaction tubes are commonly used. To ensure favorable reactions in multi-tubular reactors, it is important to ensure that the height (packing height) of the solid particles, typically catalysts, packed into each of the multiple reaction tubes is consistent within a specified range. If the packing height of solid particles is not consistent across the reaction tubes, the progress of the reaction may vary from one reaction tube to another, potentially resulting in a decrease in the overall reaction rate and yield. Therefore, a measurement method for measuring the packing height of solid particles packed into a reaction tube, i.e., the distance between the upper opening of the reaction tube and the solid particles packed inside the reaction tube, and an apparatus applicable to this measurement method have been developed.

For example, a known embodiment uses a distance measuring device equipped with a parallel irradiation mechanism to perform non-contact measurements using laser light, microwaves, etc., with the aim of easily and quickly measuring the distance from the opening of a reaction tube to solid particles filled inside the reaction tube (see Patent Document 1).

Japanese Patent Application Laid-Open No. 2021-012158

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 have sometimes made it difficult to perform accurate measurement due to dust and the like which inevitably occurs 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.

That is, the present invention provides the following [1] to [10].
[1] A measuring device for non-contactly measuring the distance between an upper opening of a reaction tube and solid particles filled inside the reaction tube, comprising:
A laser measuring instrument,
a gas supply nozzle connected to the laser length measuring device, for supplying a gas into the reaction tube and irradiating the reaction tube with a laser beam.
[2] The measuring apparatus according to [1], further comprising 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.
[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 separation 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 the 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 comprising 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 filled 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 through the gas supply nozzle so that a 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.

The measuring device and measuring method using the measuring device of the present invention can accurately and efficiently measure the distance between the upper opening of a reaction tube and the solid particles packed inside the reaction tube in a non-contact manner, contributing to the accurate and rapid packing (renewal work) of solid particles in a multi-tubular reactor.

FIG. 1 is a block diagram for explaining the configuration of the measurement device of this embodiment. 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. FIG. 3 is a schematic diagram showing the components of the measuring device of this embodiment in a see-through manner from the side.

Embodiments of the present invention will be described below with reference to the drawings. Note that the drawings merely show the shape, size, and arrangement of the components in a schematic manner sufficient to allow an understanding of the invention. The present invention is not limited to the following description, and each component may be modified as appropriate without departing from the spirit of the present invention. Furthermore, configurations according to embodiments of the present invention may not necessarily be manufactured or used in the arrangement shown in the drawings.

<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.

Here, the reaction tube to which the measuring device of this embodiment is applicable is specifically, for example, a reaction tube that can be contained in large numbers in a typical 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 a single multi-tubular reactor. The outer diameter of such a reaction tube is typically 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 typically about 1 to 5 mm, and the length of the reaction tube is typically 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 conventional material, such as carbon steel or stainless steel.

In addition, 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 catalyst among the solid particles to be measured is 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. Of these, it is preferable to measure catalysts for producing unsaturated aldehydes and unsaturated carboxylic acids, and catalysts for producing unsaturated carboxylic acids.

Examples of catalysts for producing unsaturated aldehydes and unsaturated carboxylic acids include catalysts for producing acrolein and acrylic acid by gas-phase catalytic oxidation of propylene with molecular oxygen, and catalysts for producing methacrolein and methacrylic acid by gas-phase catalytic oxidation of isobutylene or tert-butyl alcohol with molecular oxygen.

Examples of the catalyst for producing unsaturated carboxylic acids include catalysts for producing acrylic acid by gas-phase catalytic oxidation of propane with molecular oxygen, catalysts for producing acrylic acid by gas-phase catalytic oxidation of acrolein with molecular oxygen, and catalysts for producing methacrylic acid by gas-phase catalytic oxidation of methacrolein with molecular oxygen.

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

Examples of the hydrotreating catalyst include catalysts used to react sulfur and/or nitrogen compounds contained in petroleum fractions with hydrogen to remove or reduce the concentration of sulfur and/or nitrogen compounds, and/or hydrocracking catalysts used to lighten heavy oil.

Examples of the chlorine production catalyst include catalysts for producing chlorine from hydrogen chloride and oxygen.

There are no particular restrictions on the inert substances among the solid particles to be measured. Specific examples of such inert substances include ceramics such as alumina, silicon carbide, and zirconia, stainless steel, and iron. Of these, it is preferable to measure ceramics and stainless steel.

In this embodiment, the shape of the catalyst or inert substance as solid particles is not particularly limited. The catalyst or inert substance may be formed into, for example, a cylindrical, spherical, or ring shape. The bulk density of the catalyst or inert substance is typically 0.8 to 1.5 g/mL, and preferably 0.8 to 1.3 g/mL.

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 measuring device, FIG. 2 is a schematic diagram showing the components of the measuring 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 measuring device in a transparent manner from the side.

As shown in Figures 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 via the gas supply nozzle connecting pipe 30. This is explained in detail below.

1. Measuring Device (1) Laser Length Measuring Device 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.

(2) Gas Supply Nozzle In this embodiment, the gas supply nozzle 20 has a joint portion 22 that can be fixed and 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.

In this embodiment, the joint portion 22 is a short, tubular body. The material, shape, size, etc., of the joint portion 22 are not particularly limited, provided that functionality is ensured. The joint portion 22 may be formed from raw materials such as aluminum, iron, stainless steel, or resins such as acrylonitrile-butadiene-styrene copolymer synthetic resin (ABS), polyphenylene sulfide (PPS) resin, and polyacetal. The inner wall or the entire portion may be treated with black anodizing, iron oxide coating, black trivalent chromate treatment, black paint, etc. The joint portion 22 may be integrally formed with the hose connection portion 23 and nozzle portion 24, described below, provided that the purpose of the present invention is not impaired.

A partition plate 28 that allows the laser light emitted from the laser length measuring device 10 to pass through is provided at the upper opening of the joint part 22. The partition plate 28 is positioned 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 in place to hermetically seal the upper opening of the joint part 22 without any gaps.

The partition plate 28 may be fixed using any suitable means known in the art, such as adhesive, sealing tape, packing, gaskets, O-rings, or combinations thereof.

The partition plate 28 can be made of any suitable conventionally known material, provided that it does not impair the required functions of transmitting the laser light emitted by the selected laser length measuring device 10 and blocking the gas supplied from the gas supply source 40.

Specific examples of the partition plate 28 include quartz, glass, or transparent resins such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), vinyl chloride, and polycarbonate. From the standpoints of laser light transparency, scratch resistance, availability, and other properties commonly used in this technical field, it is preferable to construct the partition plate 28 from quartz or PMMA. It is even more preferable to construct the partition plate 28 from quartz, particularly from the standpoint of scratch resistance.

The shape, size (outer diameter and inner diameter), etc. of the partition plate 28 are not particularly limited, provided that they do not impair the purpose and effects of the present invention. The shape, size (outer diameter and inner diameter), etc. of the partition plate 28 can be selected appropriately to match, for example, the diameter of the upper opening of the reaction tube and the selected laser length measuring device 10.

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 distance measuring device 10 is typically 15 mm or less, and from the perspective of improving sensitivity and distance measurement accuracy, 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.

The nozzle part 24 is connected to the lower opening of the cylindrical joint part 22 so as to be airtightly sealed with the joint part 22 without any gaps. The nozzle part 24 is a cylindrical body that has a smaller diameter than the reaction tube, is longer than the joint part 22, and is shorter than the reaction tube.

The material, size (outer diameter, inner diameter, length), etc. of the joint portion 22 are not particularly limited, provided that they do not impair the purpose and effects of the present invention. The size of the joint portion 22 in particular can be designed to match the size (outer diameter and inner diameter) of the upper end of the nozzle portion 24 that connects to the joint portion 22, for example.

During use, at least a portion of the nozzle part 24, on the side of its lower opening opposite its upper opening connected to the joint part 22, is inserted into the reaction tube. When inserted into the reaction tube, the nozzle part 24 guides the laser light emitted from the laser length measuring device 10 into the reaction tube via the partition plate 28 and the joint part 22, and also supplies gas supplied from the gas supply source 40 into the reaction tube via the connecting pipe 30 and the joint part 22.

The material, size (inner diameter, outer diameter, length), etc. of the nozzle portion 24 are not particularly limited, provided that the purpose and effects of the present invention are not impaired. The size of the nozzle portion 24 can be appropriately set taking into consideration, for example, the inner diameter of the upper opening of the reaction tube and the expected measurement distance, i.e., the expected distance from the upper opening of the reaction tube to the solid particles inside the reaction tube.

The outer diameter (and inner diameter) of the nozzle portion 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 portion 24 is typically 0.5 mm or more and 10 mm or less. From the viewpoint of improving operability and measurement accuracy, it is preferably 0.5 mm or more and 1 mm or less, and more preferably about 0.5 mm.

The length of the portion of the nozzle portion 24 inserted into the reaction tube during use, i.e., the length from the lower opening of the nozzle portion 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. For example, if 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 portion 24 to the upper opening of the reaction tube is typically 60 mm or more and 1000 mm or less, and preferably about 240 mm.

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.

It is preferable to apply a treatment to a portion of the gas supply nozzle 20, more specifically, at least the inner wall of the cylindrical nozzle portion 24, 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 makes the laser light substantially non-reflective.

Examples of treatments that can be used to substantially eliminate reflection of laser light include black anodizing, iron oxide coating, black trivalent chromate treatment, and black painting. The treatment that can be used to substantially eliminate reflection of laser light can be determined taking into account characteristics such as the material of the nozzle portion 24 and the wavelength of the laser light.

In this way, by treating at least the inner wall of the nozzle portion 24 to make it substantially non-reflective to laser light, distance measurements can be performed with greater accuracy, and the inner diameter of the nozzle portion 24 can be made smaller, making the nozzle portion 24, and ultimately the measurement device 1, more compact and easier to handle.

The outer wall of the nozzle portion 24 is provided with a stopper portion 26 that surrounds a portion of the outer wall in a donut shape and is fixed to the outer wall. The stopper portion 26 is a member that seals the gap between the upper opening of the reaction tube and the inserted nozzle portion 24 airtightly. The stopper portion 26 is preferably configured to be movable in the extension direction of the nozzle portion 24 and to be fixed at any position so that the expected measurement distance and the length of the nozzle portion 24 inserted into the reaction tube can be adjusted during use.

The shape of the stopper portion 26 is not particularly limited, provided that it can perform the required function. In this embodiment, when the stopper portion 26 is fixed to the outer wall of the nozzle portion 24, it has a tapered shape that narrows toward the side that is inserted into the reaction tube (the lower end). This configuration allows the length of the inserted portion of the nozzle portion 24 to be set to a predetermined length, making it easy to install the measuring device 1.

The size of the stopper portion 26 can be determined taking into consideration the inner diameter of the reaction tube, the outer diameter of the nozzle portion 24, the overall length of the nozzle portion 24, the length of the portion of the nozzle portion 24 that will be inserted into the reaction tube, and the size of the portion of the stopper portion 26 that will be inserted into the reaction tube.

The material of the stopper portion 26 is not particularly limited. The stopper portion 26 can be made of any suitable conventional material, such as silicone rubber, natural rubber, synthetic rubber, or fluororubber.

The nozzle portion 24 and the joint portion 22 are connected so that the gap between them is airtightly sealed. When connecting the nozzle portion 24 and the joint portion 22, any suitable conventionally known member for airtight sealing, such as packing, sealing tape, gaskets, O-rings, or adhesives, may be used, if necessary.

A hose connection portion 23 for connecting the connecting pipe 30 is provided on the side of the joint portion 22, i.e., in a region midway along the extension direction of the cylindrical body. The hose connection portion 23 can be made of any suitable conventional material. The diameter of the hose connection portion 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.

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 control valve 36 for non-contactly measuring the pressure loss due to the solid particles filled in the reaction tube, as well as the distance between the upper opening of the reaction tube and the solid particles (catalyst (catalyst layer)) inside the reaction tube.

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 conventional tubular pipe can be used for this pipe. From the standpoints of mechanical strength and prevention of foreign matter such as rust, it is preferable that this pipe be made of materials such as stainless steel or aluminum.

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

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

For example, an air regulator (CKD Corporation, RP-1000) can be used as a pressure reducing valve.

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

By including a pressure gauge 34 and a gas flow control valve 36 in the connecting tube 30, the pressure loss due to the solid particles filled in the reaction tube can be measured non-contactly, along with the distance.

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

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 the gas supply source 40.

2. Gas Supply Source As the gas supply source 40, any suitable conventionally known 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 can be used, for example, a cylinder filled with a desired gas. The capacity, shape, size, etc. of the cylinder can 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.

In this embodiment, examples of the gas filled into the cylinder used as the gas supply source 40 include dry air and inert gases such as nitrogen gas and argon gas. Dry air is preferably used as the gas filled into the cylinder that is the gas supply source 40 because 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, the moisture content may be adjusted to about 0.119 g/m ³ (based on a dew point of −40°C under atmospheric pressure).

<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 filled 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.

To carry out the measurement method of this embodiment, first prepare the measurement device 1 described above. 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 light from the laser length measuring device 10 is adjusted to 0.1 mm or less.

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.

Next, at least a portion 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 filled in the reaction tube is measured in a non-contact manner.

Specifically, when performing the measurement, first, at least a portion of the nozzle portion 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 hermetically sealing the upper opening of the reaction tube with the stopper portion 26. At this time, it is preferable to fix the gas supply nozzle 20 so that the central axis of the reaction tube and the center (axis) C of the gas supply nozzle 20 (center C of the inner diameter of the nozzle portion 24) coincide with each other.

Next, the gas is supplied into the reaction tube using the pressure reducing valve, pressure gauge 34, and gas flow control valve 36 installed on the connecting tube 30, adjusting the gas linear velocity within the reaction tube to 0.01 m/sec or greater. While suppressing or preventing dust generation within the reaction tube due to solid particles, the laser distance measuring device 10 non-contactly measures the distance between the upper opening of the reaction tube and the solid particles packed in the reaction tube.

Here, we will explain the gas linear velocity. 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.

In this embodiment, for example, if the selected gas flow control valve 36 is a mass flow type, the mass flow rate will be adjusted by the gas flow control valve 36. Therefore, in this case, the mass flow rate throughout the entire region within the reaction tube will be equivalent to the mass flow rate that can be measured near the gas flow control valve 36, and the gas linear velocity can be adjusted by adjusting the mass flow rate with the gas flow control valve 36. Furthermore, for example, if the selected gas flow control valve 36 is a float type or orifice type, the volumetric flow rate will be adjusted by the gas flow control valve 36. Therefore, in this case, the volumetric flow rate near the gas flow control valve 36 can be converted into the gas linear velocity within the reaction tube, taking into account the size of the reaction tube, to calculate the gas linear velocity. Therefore, the gas linear velocity can be adjusted based on the calculated gas linear velocity.

The linear gas velocity within the reaction tube is 0.01 m/sec or greater. From the perspective of effectively suppressing or preventing the generation of dust within the reaction tube due to solid particles during measurement, the linear gas velocity is preferably 0.01 m/sec or greater, more preferably 0.1 m/sec or greater, and preferably 20 m/sec or less, more preferably 10 m/sec or less, and is preferably 0.01 m/sec or greater but 20 m/sec or less, and more preferably 0.1 m/sec or greater but 10 m/sec or less.

The measurement method of this embodiment, which is configured as described above, can effectively suppress or prevent the generation of dust inside the reaction tube due to solid particles during measurement, thereby further improving sensitivity and, ultimately, the measurement accuracy of the distance between the upper opening of the reaction tube and the solid particles (catalyst (catalyst layer)). Furthermore, the measurement method of this embodiment can further improve measurement efficiency when measuring multiple reaction tubes, and can measure pressure loss simultaneously with distance measurement, thereby measuring the pressure loss (packing density) inside the reaction tube. This can significantly improve the efficiency of catalyst renewal work in multi-tubular reactors, which in turn can contribute to improving the production efficiency of products produced in multi-tubular reactors and reducing production costs.

The present invention will be explained in more detail below using examples. The present invention is not limited to the following examples.

<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 for making the laser light emitted from the laser length measuring device 10 substantially non-reflecting.

A silicone rubber plug 26 is provided on the outer wall of the nozzle part 24 near the upper opening 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 is inserted into the reaction tube.

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

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

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

First, the rubber hose 32 (32b) on the gas flow control valve 36 side of the connecting pipe 30 was connected to the gas supply source 40, which was a cylinder. Next, 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.

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. 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 the measuring device 1 was prepared.

Example 1
A carbon steel reaction tube having an inner diameter of 25 mm and a length of 4620 mm was fixed vertically so that the length direction coincided 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.

First, for comparison, a tape measure was used to measure the distance from the upper opening of the reaction tube to the top end of the catalyst layer.

Next, the lower 240 mm of the nozzle portion 24 of the gas supply nozzle 20 of the measurement device 1 described above was inserted into the reaction tube, and the distance from the upper opening of the reaction tube to the upper end of the catalyst layer was measured non-contact by irradiating it with laser light.

At this time, the sensitivity of the laser length measuring device 10 was set to "High." Furthermore, dry air was supplied from the gas supply source 40 to the gas supply nozzle 20 so that the gas linear velocity within the reaction tube was 1.1 m/s.

The above measurements were performed five times, varying the height of the catalyst layer formed by the oxide catalyst packed into the reaction tube.

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

Example 2
A stainless steel reaction tube having an inner diameter of 30 mm and a length of 5000 mm was fixed vertically so that the length direction coincided 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.

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, a lower end portion of 240 mm of the nozzle portion 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 a non-contact measurement distance).

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 linear velocity of the gas in the reaction tube became 0.75 m/sec.
The above-described 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.

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

<Reference example 1>
When the measuring device 1 was used, 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 1, except that 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.

Example 3
A stainless steel reaction tube having an inner diameter of 30 mm and a length of 5000 mm was fixed vertically so that the length direction coincided 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.

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, a 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.

At this time, the sensitivity of the laser distance measuring device 10 was set to "High." Furthermore, dry air was supplied from the gas supply source 40 to the gas supply nozzle 20 so that the linear gas velocity within the reaction tube was 1.2 m/s, and measurements were taken to determine the absolute value of the distance difference. The results are shown in Table 2 below.

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 difference in distance 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.

<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 difference in distance 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.

Example 5
The measuring device 1 used was a measuring device 1 in which a digital differential pressure gauge (GC50, manufactured by Nagano Keiki) was 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).

A stainless steel reaction tube with an inner diameter of 30 mm and a length of 5,000 mm was fixed vertically so that its length was aligned with the vertical direction, and then an oxide catalyst containing molybdenum and phosphorus was filled into the upper opening of the reaction tube to form a catalyst layer inside the reaction tube.

First, for comparison, a tape measure was used to measure the distance from the upper opening of the reaction tube to the top end of the catalyst layer.

Next, the lower 240 mm of the nozzle portion 24 of the gas supply nozzle 20 of the measurement device 1 described above was inserted into the reaction tube, and the pressure loss inside 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 laser light.

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 within the reaction tube was 0.37 m/s, 0.75 m/s, or 1.2 m/s. The results are shown in Table 3 below.

According to the Fanning equation, which is commonly 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.

Whether or not pressure loss can be measured accurately is determined by measuring pressure loss at multiple gas linear velocities and determining the degree of proportionality between pressure loss and the square of the gas linear velocity. According to Example 5 above, this proportionality is good and ideal. Therefore, according to Example 5 above, it can be said that the differential pressure (density) of the catalyst packed in the reaction tube was also accurately measured at the same time as the distance was measured.

REFERENCE SIGNS LIST 1 Measuring device 10 Laser length measuring device 12 Emission surface 20 Gas supply nozzle 22 Joint portion 23 Hose connection portion 24 Nozzle portion 26 Plug portion 28 Partition plate 30 Connecting pipe 32 (32a, 32b) Hose 34 Pressure gauge 36 Gas flow rate control valve 40 Gas supply source

Claims (7)

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. 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. 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. 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. 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. 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. 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.