WO2020022926A1

WO2020022926A1 - Ultrasonic method of unloading a solid bulk material

Info

Publication number: WO2020022926A1
Application number: PCT/RU2018/000503
Authority: WO
Inventors: Artem Grigorievich ABRAMOV; Yury Alexandrovich LENERT; Sergey Petrovich PISKAIKIN; Galina Anatolievna LYSENKO
Original assignee: Public Joint Stock Company "Sibur Holding"
Priority date: 2018-07-27
Filing date: 2018-07-27
Publication date: 2020-01-30

Abstract

The present invention relates to a method of unloading a solid bulk material from a tubular space of a multi-tubular apparatus, comprising exposing the apparatus to ultrasonic vibrations generated by ultrasonic radiators in an acoustic contact with the apparatus. According to the invention, the exposure to ultrasonic vibrations is carried out in a frequency deviation mode, and the acoustic contact is provided by a rigid connection between the ultrasonic radiators and the apparatus. The present method affords optimization of the production process through reduced labor and time spent for unloading a solid bulk material from a multi-tubular apparatus.

Description

ULTRASONIC METHOD OF UNLOADING A SOLID BULK MATERIAL

Technical Field of the Invention

The present invention relates to optimization of production processes involving multi-tubular apparatuses that contain stationary layers of solid bulk materials in the tubular space. More particularly, the invention relates to a method of unloading a solid bulk material from a multi-tubular apparatus using ultrasound.

Background of the Invention

Processes in which gas and/or liquid passes through an apparatus containing a stationary layer of a solid bulk material are widely used in industry. Examples of such processes include processes for production of various substances using a heterogeneous catalyst, such as processes for preparation of cyclohexanone by dehydrogenation of cyclohexanol, processes for production of ethylene oxide by oxidation of ethylene, various adsorption processes, etc.

The apparatus may be a vertically disposed apparatus comprising a plurality of tubes filled with a solid bulk material. Periodically, there arises a need to unload the solid bulk materials from the apparatus. Thus, unloading of solid bulk materials from a multi tubular apparatus is a separate process task, especially when the apparatus has a high height and the solid bulk material is of a complex shape.

Conventional methods for unloading solid bulk materials include hydrodynamic, pneumatic pulse and ultrasonic methods. In addition, sometimes a solid bulk material is unloaded using hand rodding.

Hydrodynamic method of unloading of comprises treating the apparatus with water supplied under a high pressure through hydrodynamic nozzles. The use of hydrodynamic method and unloading methods are described, for example, in

RU2430796, WO2006097887, WO2013166620. Hydrodynamic unloading method requires the use of a large amount of water, resulting in the formation of a large amount of sewage, the process running at a high pressure, the need for substantial modification of a typical apparatus design by the addition of hydrodynamic nozzles, and the necessity to dry the apparatus after unloading (in particular where the apparatus is an adsorption device and the solid bulk material is an adsorbent). Pneumatic pulse method of unloading, in turn, comprises treating the apparatus with a pulsed compressed air jet produced by a pneumatic generator. This unloading method is described, for example, in RU2225761, CN203541004, CN205436487. Pneumatic pulse method of unloading requires a pulsed exposure of a part of the apparatus to an air jet, which can lead to failure of the equipment and, as a result, to premature replacement of the apparatus. In addition, the work with compressed air requires increased attention to safety measures.

Ultrasonic method of unloading features low power consumption, high productivity and absence of destructive effect on the process equipment, and does not require the use of large amounts of water and subsequent drying (as in the hydrodynamic method) or the use of pulsed air jet exposure (as in the pneumatic pulse method).

In particular, the ultrasonic unloading method is widely used in the process of cleaning fuel bundles of nuclear reactors, as described, for example, in RU 104491, RU2487765, etc. Also, the ultrasonic method is used to clean tubes, reactors and other devices that come into contact with aqueous or other solutions, as described e.g. in US 6,652,709. To ensure efficient cleaning of the equipment, ultrasonic unloading is carried out in a liquid medium as this provides for a more intensive propagation of ultrasonic vibrations.

The prior art most closely related to the present invention is a method for unloading a solid bulk material, in particular a catalyst, disclosed in US2009252658. Catalyst is unloaded from microchannels (tubes) of the apparatus using ultrasonic vibrations; the apparatus microchannels have an inner diameter of from 1 pm to 10 mm and a length of from 1 cm to 100 cm, and the catalyst particles to be unloaded have a size of not more than 20% of the inner diameter of the channels (tubes). The catalyst unloading system comprises a microchannel apparatus 1 and an ultrasound-producing head (radiator) 2 disposed at the top of the apparatus (Fig. 1). Acoustic contact between the microchannel apparatus and the ultrasound-producing head is provided either by applying a pressure or by placing a special conductive material between the ultrasound- producing head and the apparatus microchannels. The method of unloading catalyst particulates comprises applying ultrasonic vibrations produced by the ultrasound- producing head to the apparatus, the application being carried out in a pulsed manner: the ultrasound-producing head is turned on/off within 5 minutes with an interval of 10-20 seconds.

However, the ultrasonic unloading method taught in US2009252658 is employed for powdered particulates with a size not exceeding 20% of the inner diameter of the channel. Implementation of this method in apparatuses where the solid bulk material has a more complex shape with a particle size exceeding 20% of the inner diameter of the channel will be unsuccessful in unloading the solid bulk material from the apparatus. Furthermore, the acoustic contact methods complicate the apparatus structure and produce an additional load on the apparatus. Moreover, the application of pressure to provide an acoustic contact reduces the service life of the equipment, and the use of a conductive material reduces the effectiveness of ultrasonic vibrations due to air gaps between the ultrasonic radiator and the material and between the material and microchannels of the apparatus.

Therefore, no method for unloading a solid bulk material from multi-tubular apparatuses is currently known in the art, which could be used for a solid bulk material having a complex shape and a size of more than 20% of the inner diameter of a tube of the apparatus.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a high-performance method for unloading solid bulk materials including particles that have, inter alia, a complex shape from multi-tubular apparatuses.

The technical effect afforded by the present invention includes optimization of the production process through the reduced time and labor spent for unloading a solid bulk material from a multi-tubular apparatus. A further technical effect is that a typical multitubular apparatus does not require significant upgrading of its structure to implement unloading according to the inventive method, and no additional steps are needed to clean the apparatus for subsequent use.

The object of the present invention and the technical effect are attained by unloading a solid bulk material from a tubular space of a multi-tubular apparatus, comprising: exposing the apparatus to ultrasonic vibrations generated by ultrasonic radiators that are in an acoustic contact with the apparatus, characterized in that said exposure to ultrasonic vibrations occurs in a frequency deviation mode, and said acoustic contact is provided by a rigid connection between the ultrasonic radiators and the apparatus.

"Frequency deviation mode" hereinafter refers to a mode of constant forced variation of instantaneous operating frequency of ultrasonic vibrations within a specified frequency range with a set discreteness level (period), i.e. a mode of controlled frequency vibrations per unit time within a specified frequency range with a set discreteness level (period).

"Specified frequency range" hereinafter refers to a frequency range corresponding to the ultrasonic range.

"Discreteness level" hereinafter refers to the amount of variation in the instantaneous frequency.

The inventors have found that the efficiency of unloading a solid bulk material from a multi-tubular apparatus depends to a large extent on the mode of exposure to ultrasonic vibrations. For example, unloading of a solid bulk material with a particle size of from 20% to 60% of the inner diameter of the tubes in the mode of exposure to ultrasonic vibrations with a constant wave frequency or in the mode of pulsed exposure (as in the closest prior art) is accompanied by compaction of the bulk material, preventing its efficient unloading. At the same time, the frequency deviation mode promotes constant shaking of particles of the solid bulk material in the tube, ensuring their continuous movement which prevents the material from compacting.

A method of unloading solid bulk materials from a multi-tubular apparatus according to the present invention comprises applying ultrasonic vibrations to an apparatus comprising a plurality of tubes containing a solid bulk material; said ultrasonic vibrations being applied in a frequency deviation mode, i.e. a mode of constant forced variation of the instantaneous operating frequency of ultrasonic vibrations within a specified frequency range with a set discreteness level (period).

In the context of the present invention, the term "unloading" refers not only to withdrawal of a solid bulk material from an apparatus, but also to cleaning the equipment having deposits in the form of solid particles on its inner walls. The equipment to be cleaned may comprise tubes, devices having a plurality of tubes, bulk capacity vessels, etc. To intensify the process, the cleaning is preferably carried out in a liquid medium.

In the context of the present invention, solid bulk material is a material comprising particles of a size less than 60%, preferably less than 50%, most preferably less than 40% of the inner diameter of a tube of the apparatus. Particle size refers to the diameter for spherical particles of the solid bulk material, and to the largest geometric parameter (height of cylinder, outer diameter of ring, etc.) for particles having a more complex shape. In one embodiment of the invention, the solid bulk material is a catalyst or an adsorbent.

According to the present invention, the multi-tubular apparatus is an apparatus comprising at least a plurality of tubes, a housing, and a tube holding device, in particular a tube grate.

The method for unloading a solid bulk material according to the present invention is applicable in any conventional apparatuses comprising a plurality of tubes, in particular a shell-and-tube reactor. The present method can also be used for unloading solid bulk materials from apparatuses regardless of their overall dimensions, number of tubes, amount of curvature and thickness of their walls. In addition to the tubes and the housing, the apparatus further comprises inlet and outlet nozzles for flows of raw material and coolants, a hinged cover and a bottom for loading and unloading a solid bulk material, and a tube grate to hold the tubes and a distribution chamber. The apparatus can further comprise partitions, expansion joints, guide plates, etc.

Preferably, the present method is used for unloading a solid bulk material from apparatuses made of materials that conduct at least 50% of the ultrasonic vibration power. More preferably, the material of the apparatus is steel, most preferably, alloyed steel grades, in particular, 12X18H10T steel grades.

Ultrasonic vibrations are induced in the apparatus by radiation of ultrasonic waves from an ultrasonic radiator. The ultrasonic radiator can be piezoelectric, magnetostrictive, electromagnetic acoustic (EMA) or another high efficiency transducer. Preferably, the ultrasonic radiator can be piezoelectric, made of piezoceramic materials or a quartz monocrystal. To ensure long-term service, the material of the ultrasonic radiator is preferably selected from the materials that exhibit high resistance to corrosion and aggressive media, are dust/moisture proof and provide strong electrical insulation.

The operating frequency range of the ultrasonic radiators according to the present invention is from 18 to 44 kHz, preferably from 20 to 30 kHz, most preferably from 23.5 to 25.5 kHz.

The number of ultrasonic radiators used according to the present invention depends on the weight of the apparatus, the weight of the solid bulk material loaded into the plurality of tubes of the apparatus, and the geometrical arrangement of the tubes. Preferably, the radiators are equidistant from each other to ensure uniform effect of ultrasonic vibrations on the solid bulk material.

The arrangement of ultrasonic radiators according to the present invention can be any one having regard to the convenience of the process. In particular, the radiators are disposed on upper flanges of the apparatus. Preferably, for more effective unloading the ultrasonic radiators are disposed simultaneously on upper and lower flanges of the apparatus. The arrangement of the radiators simultaneously on upper and lower flanges of the apparatus contributes to uniform distribution of ultrasonic vibrations, and this can reduce the time for complete unloading the solid bulk material from the apparatus.

According to the present invention, to provide an acoustic contact while transmitting ultrasonic vibrations, the ultrasonic radiator is rigidly connected to the apparatus, i.e. the radiator has no degrees of freedom. Rigid connection is mandatory to implement unloading of material, because a flexible connection cannot effectively transmit the frequency deviation of ultrasonic radiation, therefore, the use of a flexible connection would not provide the claimed technical effect. Furthermore, a flexible connection increases the level of vibration of the apparatus, leading to damages and premature failure of the equipment. Rigid connection can be provided by welding, collet clamping, etc. Components of the apparatus, on which the ultrasonic radiator can be mounted, include, but not limited to: a screw clamp, a wedge, an end stop. Preferably, the ultrasonic radiator is rigidly connected to a screw clamp, more preferably the ultrasonic radiator is rigidly connected to the apparatus by a collet clamp. Collet clamp is a kind of a chuck related to self-holding attachments because it does not require additional parts. Unloading of a solid bulk material from the apparatus of the present invention is carried out within the operating frequency range of from 18 to 44 kHz, preferably from 20 to 30 kHz, most preferably from 23.5 to 25.5 kHz.

Discreteness of ultrasonic vibrations is from 5 to 100 Hz, preferably from 10 to 70 Hz, most preferably from 15 to 30 Hz.

Current generators are used to produce ultrasonic vibrations from ultrasonic radiators. Current supplied from the generators is fed to ultrasonic radiators, which in turn generate ultrasonic vibrations. Strength of current supplied to the ultrasonic radiators is from 0.5 A to 1 A, preferably from 0.72 A to 0.88 A.

The time of unloading a solid bulk material from the apparatus depends on the height of the solid bulk material layer in the apparatus, the shape, size and nature of particles of the solid bulk material, and the shape and dimensions of the apparatus and tubes in the apparatus. Unloading a durable (having a low attrition rate) solid bulk material of a complex shape (ring, cylinder, etc.) takes more time than unloading a brittle spherical solid bulk material.

Brief Description of the Drawings

Fig. 1 is a schematic diagram of a microchannel apparatus 1 and an ultrasonic generator 2 disposed in upper part of the apparatus (apparatus according to the closest prior art).

Fig. 2 is a schematic diagram of an apparatus comprising a plurality of tubes and one of possible arrangements of ultrasonic radiators on the apparatus (on upper and lower flanges), where 1 is housing of the apparatus, 2 is tubular space, 3 is ultrasonic radiator, 4 is control cabinet.

Figs. 3 to 5 show possible arrangements of ultrasonic radiators.

Detailed Description of the Invention

The present invention will be more specifically described with reference to the following examples. The examples are given only to illustrate the present invention and not to limit it. The apparatus is a shell-and-tube reactor comprising 20 tubes having length 7 m, diameter 25 mm, inner diameter 18.5 mm; tubes are made of steel and feature high roughness and curvature.

Solid bulk material is a catalyst consisting of rings 8 mm in diameter and 6-7 mm in length.

Total weight of the solid bulk material is 5.3 kg.

Ultrasonic radiator is piezoelectric (piezoceramic), produced by NPP Ultra-Filter LLC (Moscow).

Example 1 : Comparative

Ultrasonic radiators were disposed on a screw clamp at 0.15 m above the lower flange. Unloading was carried out at frequencies of 19-45 kHz with increments of about 0.1 kHz, the transducer being powered from the ultrasonic generator with inductance adjustment to a load current of 0.6- 1.0 A.

The greatest vibration of the tube was observed at the frequencies of 23.5 kHz and 25.5 kHz with the load current of about 1 A. As a result of operation of the equipment, an insignificant spilling of the catalyst was observed only at the instant of switching the frequency.

Example 2: Comparative

Unloading was carried out according to Example 1 except that ultrasonic radiators were disposed on a screw clamp at a height of 3.5 m from the lower flange (in the tube center).

Spilling of the catalyst was insignificant: about 10% for all the time of the tests with a screw clamp and, as before, at the instants of switching the frequency on the generator.

Example 3: Comparative

Unloading was carried out according to Example 1 except that the ultrasonic radiators were disposed on a screw clamp at a distance of 0.18 m from the upper flange.

Spilling of catalyst was insignificant: about 10% for all the time of the tests with a screw clamp and, as before, at the instants of switching the frequency on the generator. Example 4: Comparative

Unloading was carried out according to Example 1 except that the ultrasonic radiators were disposed on a screw clamp at the distance of 0.18 m from the upper flange and on a screw clamp at the distance of 0.15 m above the lower flange. Ultrasonic radiators operated at a constant frequency.

Spilling of catalyst occurred periodically after turning on the ultrasonic unit. 7% of the catalyst was spilled out in the first 23 minutes. Catalyst was not spilled out completely because an undesirable side effect, such as compaction of the catalyst in the tube, was revealed in the test of operation with a constant frequency of ultrasonic waves.

Example 5: Comparative (according to the closest prior art)

Ultrasonic radiators were arranged in two groups: a first group on the upper flange, and a second group on the lower one. Unloadings were carried out at the constant frequency of 23.5 kHz, the transducer being powered from the ultrasonic generator with the load current of about 1 A. Unloading was performed in the regime of periodic activation of the ultrasonic radiators. Active phase and idle periods were equal and amounted to 30 seconds.

Catalyst was spilled out periodically upon activation of ultrasonic radiators. 35% of the catalyst was spilled out in the first 20 minutes. Catalyst was not spilled out completely because an undesirable side effect, such as compaction of catalyst in the tubular space, was revealed in the test of operation in periodic regime of applying ultrasonic radiation with a constant wave frequency. The fact of catalyst compaction was detected experimentally during subsequent hand rodding of the tubes: the process was more labor and time-consuming than at the standard "manual" unloading of catalyst without prior exposure to ultrasonic radiation.

Example 6:

In Example 6, the first group of ultrasonic radiators was disposed on the upper flange, and the second group was disposed crosswise on the lower flange.

Catalyst was unloaded at the basic frequency of 24.5 kHz; the load current was about 1 A in the deviation mode with a discreteness level of 15-30 Hz. Fig. 3 shows a conditional arrangement of ultrasonic radiators on flanges of a simulator.

Spilling of the catalyst started upon activation of the ultrasonic unit. 50% of the catalyst was spilled out in the first 3 minutes, with the central tubes emptied first. After 10 minutes, 70% of the catalyst was spilled out. Upon the expiry of 22 minutes, the catalyst was completely spilled out from the tubes.

Example 7:

Unloading was carried out as in Example 6 except that the ultrasonic radiators were arranged ring- wise as shown in Fig. 4.

Spilling of catalyst started upon activation of the ultrasonic unit. 35% of the catalyst was spilled out in the first 3 minutes. After 10 minutes 2 tubes were emptied. Upon the expiry of 30 minutes the catalyst was completely spilled out.

Example 8:

Unloading was carried out according to Example 6 except that the ultrasonic radiators were arranged in groups as shown in Fig. 5.

Spilling of catalyst started upon activation of the ultrasonic unit. 40% of the catalyst was spilled out in the first 3 minutes. Upon the expiry of 20 minutes the catalyst was completely spilled out.

Examples 1 to 4 (comparative) illustrate that catalyst was not completely unloaded when ultrasonic vibrations were applied at a constant frequency; in this case the arrangement of ultrasonic radiators (top, center, bottom, top and bottom) does not significantly affect the amount of catalyst unloaded.

Examples 6 to 8 (according to the invention) illustrate a method of unloading a catalyst with application of ultrasonic vibrations in a deviation mode. The examples show that the arrangement of ultrasonic radiators (as shown in Figs. 3 to 5) affects the speed of unloading, but the catalyst can be completely unloaded from the apparatus tubes in each case regardless of the arrangement of ultrasonic radiators.

Claims

1. A method of unloading a solid bulk material from a tubular space of a multitubular apparatus, comprising exposing said apparatus to ultrasonic vibrations generated by ultrasonic radiators in an acoustic contact with said apparatus, characterized in that said exposure to ultrasonic vibrations is carried out in a frequency deviation mode, and said acoustic contact is provided by a rigid connection between the ultrasonic radiators and the apparatus.

2. The method according to claim 1, wherein the solid bulk material comprises particles with a size of less than 60% of the inner diameter of a tube of the apparatus.

3. The method according to claim 2, wherein the solid bulk material comprises particles with a size of less than 50% of the inner diameter of a tube of the apparatus.

4. The method according to claim 3, wherein the solid bulk material comprises particles with a size of less than 40% of the inner diameter of a tube of the apparatus.

5. The method according to claim 1, wherein the apparatus is an apparatus comprising at least: a plurality of tubes, a housing and a tube holding device.

6. The method according to claim 5, wherein the tube holding device is a tube grate.

7. The method according to claim 5, wherein the apparatus is a shell-and-tube reactor.

8. The method according to claim 1, wherein the rigid connection is provided by welding or by a collet clamp.

9. The method according to claim 1, wherein said unloading is carried out within the range of operating frequencies of from 18 to 44 kHz.

10. The method according to claim 9, wherein said unloading is carried out within the range of operating frequencies of from 20 to 30 kHz.

11. The method according to claim 10, wherein said unloading is carried out within the range of operating frequencies of from 23.5 to 25.5 kHz.

12. The method according to claim 1, wherein said unloading is carried out with a discreteness of ultrasonic vibrations of from 5 to 100 Hz.

13. The method according to claim 12, wherein said unloading is carried out with a discreteness of ultrasonic vibrations of from 10 to 70 Hz.

14. The method according to claim 13, wherein said unloading is carried out with a discreteness of ultrasonic vibrations of from 15 to 30 Hz.

15. The method according to claim 1, wherein said ultrasonic radiators are disposed on upper flanges of the apparatus.

16. The method according to claim 1, wherein said ultrasonic radiators are disposed on lower flanges of the apparatus.

17. The method according to claim 1, wherein said ultrasonic radiators are disposed on lower and upper flanges of the apparatus.

18. The method according to claim 17, wherein said ultrasonic radiators are disposed on lower and upper flanges of the apparatus using collet clamps.

19. The method according to claim 1, wherein said ultrasonic radiators are disposed on a screw clamp disposed in the center between upper and lower flanges of the apparatus.

20. The method according to claim 1, wherein said ultrasonic radiators are arranged equidistant from each other.