An apparatus for the preparation of catalysts using a plasma arc

Abstract

The application provides a device for preparing a catalyst by using a plasma arc, and relates to the technical field of catalyst preparation, and comprises a calcination box body, a plasma arc generator, a rotating ceramic cage and a gas supply structure. The calcination box body is a closed box structure, the rotating ceramic cage is located inside the calcination box body and is used for containing catalysts to be calcined and has a slow rotation function; the plasma arc generator is located below the rotating ceramic cage and is used for generating a plasma arc to calcine the catalysts on the rotating ceramic cage; and the gas supply structure is in communication with the inside of the calcination box body and is used for providing an inert atmosphere for the inside of the calcination box body. When the catalyst is prepared, active particles are attached to the surface of the catalyst by using methods such as impregnation and hydrothermal treatment, then the plasma arc is used for calcination, so that the active metal is sintered on the catalyst carrier; a temperature control sensor is installed in the middle of the ceramic cage containing the catalyst, a high-voltage power supply is combined to adjust the discharge intensity, so as to control the calcination temperature and make the catalyst be heated uniformly.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and more particularly to an apparatus for preparing catalysts using a plasma arc. Background Technology

[0002] During plasma discharge, a large number of free electrons are generated. These electrons have a high charge-to-mass ratio and can acquire high energy in an electric field. These high-energy electrons collide with other ions or molecules, producing a large number of active particles, such as photons and excited-state atoms, molecules, free radicals, ions, and neutral particles. These active particles increase reactivity, making many reactions that are difficult to occur under normal conditions easier to perform. Therefore, plasma technology is widely used in biomedicine, semiconductor industry, surface treatment of materials, catalyst processing, plasma-assisted combustion, and pollutant treatment. The sintering of the active components of a catalyst is a key step in its preparation process.

[0003] Existing catalyst preparation technologies mainly fall into three categories: First, traditional liquid-phase synthesis processes, such as impregnation, co-precipitation, sol-gel, and hydrothermal synthesis. These processes require large amounts of solvent, resulting in significant wastewater pollution. Subsequent static calcination in a muffle furnace easily leads to catalyst particle agglomeration and sintering, resulting in uneven distribution of active components. Second, conventional plasma preparation equipment, which mostly employs a fixed-bed structure, causing one-sided heating of the material, making precise temperature control difficult, and incurring cumbersome arc ignition operations and rapid electrode wear. Third, precision synthesis technologies such as atomic layer deposition and vapor phase synthesis, while achieving precise component dispersion, suffer from high equipment costs and extremely low single-batch processing capacity, hindering industrial-scale mass production. Existing technologies generally suffer from significant pollution, severe catalyst sintering, difficulty in temperature control, and high mass production costs. This invention proposes a plasma arc calcination device that uses a rotatable ceramic cage to achieve uniform heating of the material. It is equipped with a controllable telescopic arc ignition electrode and a temperature control closed-loop system, allowing for adjustment of plasma discharge intensity. It eliminates the need for large amounts of solvent, solving the problems of catalyst sintering and uneven heating while simultaneously meeting the requirements of low cost and large-scale preparation. Introducing a plasma arc during the calcination process allows the active particles generated during discharge to couple with the active components of the catalyst, which helps to improve the activity of the active components. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an apparatus for preparing catalysts using a plasma arc. In preparing the catalyst, active particles are attached to the catalyst surface using methods such as impregnation or hydrothermal treatment. Then, a plasma arc is used for calcination, causing the active metal to sinter onto the catalyst support. A temperature control sensor is installed in the center of a rotating ceramic cage containing the catalyst, and a high-voltage power supply is used to adjust the discharge intensity, thereby controlling the calcination temperature and ensuring uniform heating of the catalyst.

[0005] The technical means employed in this invention are as follows: An apparatus for preparing catalysts using a plasma arc includes: a calcination chamber, a plasma arc generator, a rotating ceramic cage, and a gas supply structure mounted on the calcination chamber. The calcination chamber is a closed chamber structure. The rotating ceramic cage is located inside the calcination chamber and is used to hold the catalyst to be calcined, and has a slow rotation function. The plasma arc generator is located below the rotating ceramic cage and is used to generate a plasma arc to calcinate the catalyst on the rotating ceramic cage. The gas supply structure is connected to the interior of the calcination chamber and is used to provide an inert atmosphere to the interior of the calcination chamber.

[0006] Furthermore, the plasma arc generator includes a high-voltage power supply, a discharge electrode, and an arc-initiating electrode. The discharge electrode is fixedly installed at the bottom of the calcining chamber and placed vertically. The arc-initiating electrode is located inside the calcining chamber and placed horizontally. The arc-initiating electrode is connected to a telescopic mechanism, which is fixedly installed on one side wall of the calcining chamber to realize the telescopic movement of the arc-initiating electrode. The high-voltage power supply is fixedly installed at the bottom of the calcining chamber and electrically connected to the discharge electrode to provide electrical energy. When the discharge is started, the arc-initiating electrode is driven to extend and approach the discharge electrode through the telescopic mechanism, generating a plasma arc at the tip of the discharge electrode.

[0007] Furthermore, the discharge electrode is a conical positive electrode, and the cone angle of the conical positive electrode is 30°-60°.

[0008] Furthermore, the high-voltage power supply employs a high-voltage coil.

[0009] Furthermore, the telescopic mechanism includes a spring and an electromagnet. The electromagnet has a coil made of copper wire wound inside, and an iron plunger is placed inside the coil. The plunger extends outside the electromagnet, and the spring is wound around the plunger and located outside the electromagnet. One end of the spring is fixedly connected to the electromagnet, and the other end is fixedly connected to the protruding end of the plunger away from the coil. When the electromagnet is energized, the spring is compressed and in a contracted state. When the electromagnet is de-energized, the spring is released and in an extended state. When the discharge is initiated, the arc-initiating electrode extends and approaches the discharge electrode. After a plasma arc is generated, the arc-initiating electrode retracts.

[0010] Furthermore, the rotating ceramic cage is placed horizontally, with a temperature control sensor installed in the middle to adjust the discharge intensity and control the calcination temperature.

[0011] Furthermore, the temperature control sensor has a high-temperature resistant protective sleeve, which is made of alumina ceramic.

[0012] Furthermore, the distance between the cage rods of the rotating ceramic cage is 2-4 mm.

[0013] Furthermore, the rotating ceramic cage is connected to a motor, which is fixedly installed on the outside of the other side wall of the firing chamber to drive the rotating ceramic cage to rotate.

[0014] Furthermore, the top and bottom of the roasting chamber are respectively provided with a gas outlet and a gas inlet. The gas supply structure includes a gas storage tank, a flow meter and a pipeline. One end of the pipeline is connected to the gas storage tank and the other end is connected to the roasting chamber via the gas inlet. The flow meter is installed on the pipeline to control the flow rate of the inert gas entering the roasting chamber.

[0015] Compared with the prior art, the present invention has the following advantages: 1. The plasma arc catalyst preparation apparatus provided by the present invention is equipped with a rotating ceramic cage that rotates slowly during the calcination process to ensure that the catalyst particles are heated evenly, avoid local overheating or insufficient calcination, and improve the sintering uniformity of the active metal.

[0016] 2. The plasma arc catalyst preparation device provided by the present invention utilizes a plasma arc generator in conjunction with an arc-initiating telescopic mechanism, which provides stable arc initiation, rapid response, adjustable discharge intensity and calcination temperature, and strong controllability of the preparation process.

[0017] 3. The plasma arc catalyst preparation apparatus provided by the present invention has a closed calcination chamber and an inert gas path to form a stable protective atmosphere, prevent high-temperature oxidation of active metals, and ensure catalyst quality.

[0018] 4. The plasma arc catalyst preparation device provided by the present invention consists of basic components such as a high-voltage power supply and a discharge electrode. It has a simple structure, is easy to maintain, is compatible with a variety of catalyst supports and active metals, and has a wide range of applications.

[0019] Based on the above reasons, this invention can be widely applied in fields such as catalyst preparation. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a front structural schematic diagram of the apparatus for preparing catalysts using plasma arc according to the present invention.

[0022] Figure 2 This is a side cross-sectional view of the apparatus for preparing catalysts using plasma arc according to the present invention.

[0023] Figure 3 This is a magnified view of a partial structure of the present invention.

[0024] In the diagram: 1. Gas outlet; 2. Rotating ceramic cage; 3. Temperature control sensor; 4. Discharge electrode; 5. High voltage power supply; 6. Arc ignition electrode; 7. Telescopic mechanism; 8. Gas inlet; 9. Flow meter; 10. Gas storage tank; 11. Motor; 12. Electromagnet; 13. Spring. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0029] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0030] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0031] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0032] Compared to traditional catalyst calcination technologies such as muffle furnaces and tube furnaces, this invention provides an apparatus for preparing metal catalysts using plasma arc, comprising: a plasma arc generator, a rotating ceramic cage 2, a gas supply structure (gas path), a control system, and a calcination chamber; wherein the plasma arc generator is used to generate a high-temperature plasma arc to calcine the catalyst on the rotating ceramic cage 2; the rotating ceramic cage 2 is located inside the calcination chamber and is used to hold the catalyst to be calcined and ensure uniform heating; the gas supply structure is connected to the interior of the calcination chamber and is used to introduce inert gas into the calcination chamber to provide an inert atmosphere; the control system is mainly used to realize the control functions of the system, realize the automated control and parameter adjustment of the entire apparatus, and the calcination chamber provides a closed calcination environment.

[0033] The roasting chamber is a closed chamber structure with a gas inlet 8 and a gas outlet 1 at the bottom and top for the introduction and discharge of inert gas. The gas inlet 8 is connected to the gas storage tank 10 through a pipe.

[0034] The calcination chamber contains a rotating ceramic cage 2, a plasma arc generator, and a temperature control sensor 3. The rotating ceramic cage 2 is placed horizontally, and the plasma arc generator is installed below it to generate a plasma arc during calcination, which is used to calcine the catalyst inside the rotating ceramic cage 2. During plasma arc calcination, the rotating ceramic cage 2 is driven to rotate slowly by a motor 11 fixedly installed on the left outer wall of the calcination chamber to ensure that the catalyst is heated evenly. The temperature control sensor 3 is installed in the middle of the rotating ceramic cage 2 to monitor the calcination temperature in real time and, in conjunction with the high-voltage power supply 5, adjusts the discharge intensity to control the calcination temperature. The red and black wires in the high-voltage power supply 5 input low-voltage DC power, and the self-excited oscillation circuit on the circuit board cuts the stable DC power into high-frequency alternating pulse current and passes it into a primary coil with few turns and a thick wire diameter. The primary coil generates a rapid alternating magnetic field, which couples to a secondary coil with a large number of turns. Relying on the difference in the number of turns of the coil, a high-frequency high-voltage current of several thousand to tens of thousands of volts is generated and delivered to the top conical discharge electrode 4. The control circuit adjusts the power of the primary coil by changing the input current and oscillation frequency of the oscillation circuit, thereby changing the magnitude of the secondary output high voltage and realizing closed-loop control of the plasma arc discharge intensity and calcination temperature.

[0035] The plasma arc generator includes a high-voltage power supply 5, a discharge electrode 4, and an arc-initiating electrode 6. When the discharge is initiated, the arc-initiating electrode 6 approaches the discharge electrode 4, generating a plasma arc at the tip of the discharge electrode 4. The arc-initiating electrode 6 is positioned opposite the discharge electrode 4. The discharge electrode 4 is vertically fixed at the bottom of the roasting chamber, while the arc-initiating electrode 6 is located horizontally inside the roasting chamber. The arc-initiating electrode 6 is connected to a telescopic mechanism 7, which is fixedly installed on the right side wall of the roasting chamber to enable horizontal telescopic movement of the arc-initiating electrode 6. The high-voltage power supply 5 uses a high-voltage coil and is fixedly installed at the bottom of the roasting chamber, electrically connected to the discharge electrode 4. It provides the electrical energy required to generate the plasma arc (the high-voltage power supply relies on primary and secondary coils to convert low-voltage DC to high-voltage electricity, transmitting the generated high-voltage electricity to the discharge electrode to provide the necessary electrical energy).

[0036] The rotating ceramic cage 2 adopts a cage-like frame structure, formed by multiple ceramic cage rods surrounding a central cylindrical cavity. One end of the cavity is equipped with an openable and closable loading end cap for loading and unloading the catalyst; the other end is connected to a motor 11 outside the chamber via a fixing rod passing through the left side wall of the calcining chamber, enabling slow-speed rotation of the cage. A temperature control sensor 3 is installed at the central axis of the hollow cavity.

[0037] The control system adjusts the discharge intensity based on the temperature monitored by the temperature sensor 3 and the high-voltage power supply 5, thereby precisely controlling the roasting temperature.

[0038] Preferably, the discharge electrode 4 is conical, serving as a conical positive electrode, with a cone angle of 30°-60°, and is made of materials such as tungsten, copper, or stainless steel.

[0039] Preferably, the telescopic mechanism 7 consists of a spring 13 and an electromagnet 12. The electromagnet 12 has a coil formed by winding copper wire inside, and an iron plunger (armature) is placed inside the coil, extending outside the electromagnet 12. The spring 13 is wound around the plunger and located outside the electromagnet 12, with one end of the spring 13 fixedly connected to the electromagnet 12 and the other end fixedly connected to the protruding end of the plunger away from the coil. The electromagnet 12 is connected to an existing external power supply. When the electromagnet 12 is energized, it compresses the spring 13, placing it in a contracted state. When the electromagnet 12 is de-energized, the spring 13 releases, placing it in an extended state. That is, when current flows, the coil becomes a magnet, with the magnetic field at the center of the coil being the strongest, causing the plunger to move towards the center and compress the spring 13; when the power is turned off, the plunger returns to its initial position under the pressure of the spring 13. When discharge is initiated, the telescopic mechanism 7 drives the arc-initiating electrode 6 to extend and approach the discharge electrode 4. After generating a plasma arc, the arc-initiating electrode 6 retracts. Specifically, during the discharge phase, the electromagnet 12 is de-energized, and the spring 13 pushes the arc-initiating electrode 6 forward, narrowing the gap between it and the conical discharge electrode 4. After the gap is reduced, the electric field strength between the electrodes increases sharply. The high-voltage electric field impacts and ionizes the inert gas molecules in the gap, generating a large number of electrons and ions. The originally insulating gas becomes a conductive plasma channel, and the current continues to conduct, stably forming a plasma arc. After the arc is generated, the electromagnet 12 is energized, pulling the arc-initiating electrode 6 back to widen the gap. At this time, the plasma has maintained a conductive path and can continue to discharge without close proximity.

[0040] Preferably, depending on the size of the catalyst, the distance (gap) between the ceramic cage rods of the rotating ceramic cage 2 is 2-4 mm, which allows the plasma arc to directly contact the catalyst surface (the plasma arc can directly contact the cylindrical cavity through the gap to calcine the catalyst inside the cavity).

[0041] Preferably, the rotating ceramic cage 2 is installed on the side wall of the calcining chamber, and a motor 11 is fixedly installed on the outer side of the left side wall of the calcining chamber, driving the rotating ceramic cage 2 to rotate. The motor 11 can be equipped with a housing depending on the actual working conditions and usage requirements.

[0042] Preferably, the top and bottom of the roasting chamber are respectively provided with a gas outlet 1 and a gas inlet 8. The gas supply structure includes a gas storage tank 10, a flow meter 9, and a pipeline. One end of the pipeline is connected to the gas storage tank 10, and the other end is connected to the roasting chamber via the gas inlet 8. The flow meter 9 is installed on the pipeline to control the flow rate of the inert gas entering the roasting chamber. The gas outlet 1 is connected to an existing external waste gas treatment device, which can be selected according to the laboratory conditions.

[0043] Preferably, the temperature control sensor 3 has a high-temperature resistant protective sleeve on its outer side, and the protective sleeve is made of alumina ceramic material.

[0044] Preferably, the control system can be a PLC. The high-voltage power supply, electromagnet, temperature sensor, and motor are all electrically connected to the control system. The control system controls the start / stop and output power of the high-voltage power supply 5 to generate and regulate the plasma arc. The control system controls the on / off state of the electromagnet 12 to extend and retract the arc-initiating electrode 6. The temperature sensor 3 is installed in the middle of the rotating ceramic cage 2, feeding back a temperature signal to the control system, which adjusts the discharge intensity accordingly to control the calcination temperature. The motor 11 is installed on the outer side of the left wall of the calcination chamber; the control system controls the start / stop and speed of the motor 11, driving the rotating ceramic cage 2 to rotate slowly.

[0045] The principle of this invention is that, during catalyst preparation, active particles are attached to the surface of the catalyst using methods such as impregnation and hydrothermal treatment, and then calcined using a plasma arc to sinter the active metal onto the catalyst support. A temperature control sensor is installed in the middle of a rotating ceramic cage containing the catalyst, and the discharge intensity is adjusted in conjunction with a high-voltage power supply to control the calcination temperature and ensure that the catalyst is heated uniformly.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An apparatus for preparing a catalyst using a plasma arc, characterized in that, include: The calcination chamber includes a plasma arc generator, a rotating ceramic cage (2), and a gas supply structure installed on the calcination chamber. The calcination chamber is a closed chamber structure. The rotating ceramic cage (2) is located inside the calcination chamber and is used to hold the catalyst to be calcined. It has a slow rotation function. The plasma arc generator is located below the rotating ceramic cage (2) and is used to generate a plasma arc to calcinate the catalyst on the rotating ceramic cage (2). The gas supply structure is connected to the inside of the calcination chamber and is used to provide an inert atmosphere to the inside of the calcination chamber.

2. The apparatus for preparing catalysts using plasma arc according to claim 1, characterized in that, The plasma arc generator includes a high-voltage power supply (5), a discharge electrode (4), and an arc-initiating electrode (6). The discharge electrode (4) is fixedly installed at the bottom of the calcining chamber and placed vertically. The arc-initiating electrode (6) is located inside the calcining chamber and placed horizontally. The arc-initiating electrode (6) is connected to a telescopic mechanism (7). The telescopic mechanism (7) is fixedly installed on one side wall of the calcining chamber to realize the telescopic movement of the arc-initiating electrode (6). The high-voltage power supply (5) is fixedly installed at the bottom of the calcining chamber and electrically connected to the discharge electrode (4) to provide electrical energy. When the discharge is started, the arc-initiating electrode (6) is driven to extend through the telescopic mechanism (7) and approach the discharge electrode (4) to generate a plasma arc at the tip of the discharge electrode (4).

3. The apparatus for preparing catalysts using plasma arc according to claim 2, characterized in that, The discharge electrode (4) is a conical positive electrode with a cone angle of 30°-60°.

4. The apparatus for preparing catalysts using plasma arc according to claim 2, characterized in that, The high-voltage power supply (5) uses a high-voltage coil.

5. The apparatus for preparing catalysts using plasma arc according to claim 2, characterized in that, The telescopic mechanism (7) includes a spring (13) and an electromagnet (12). The electromagnet (12) has a coil made of copper wire inside. An iron plunger is placed inside the coil and extends to the outside of the electromagnet (12). The spring (13) is wound around the plunger and located outside the electromagnet (12). One end of the spring (13) is fixedly connected to the electromagnet (12), and the other end is fixedly connected to the protruding end of the plunger away from the coil. When the electromagnet (12) is energized, the spring (13) is compressed and is in a contracted state. When the electromagnet (12) is de-energized, the spring (13) is released and is in an extended state. When the discharge is started, the arc-initiating electrode (6) extends and approaches the discharge electrode (4). After the plasma arc is generated, the arc-initiating electrode (6) retracts.

6. The apparatus for preparing catalysts using plasma arc according to claim 1, characterized in that, The rotating ceramic cage (2) is placed horizontally, with a temperature control sensor (3) installed in the middle to adjust the discharge intensity and control the calcination temperature.

7. The apparatus for preparing catalysts using plasma arc according to claim 6, characterized in that, The temperature control sensor (3) has a high-temperature resistant protective sleeve, which is made of alumina ceramic.

8. The apparatus for preparing catalysts using plasma arc according to claim 1, characterized in that, The distance between the cage rods of the rotating ceramic cage (2) is 2-4 mm.

9. The apparatus for preparing catalysts using plasma arc according to claim 1, characterized in that, The rotating ceramic cage (2) is connected to a motor (11), which is fixedly installed on the outside of the other side wall of the calcining chamber and is used to drive the rotating ceramic cage (2) to rotate.

10. The apparatus for preparing a catalyst using a plasma arc according to claim 1, characterized in that, The top and bottom of the roasting chamber are respectively provided with a gas outlet (1) and a gas inlet (8). The gas supply structure includes a gas storage tank (10), a flow meter (9) and a pipeline. One end of the pipeline is connected to the gas storage tank (10), and the other end is connected to the roasting chamber via the gas inlet (8). The flow meter (9) is installed on the pipeline to control the flow rate of the inert gas entering the roasting chamber.

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