JPWO2013179786A1 - Pyrolysis furnace and method for producing pyrolysis products - Google Patents

Abstract

In the pyrolysis furnace (100) according to one embodiment of the present invention, the reaction tube (1) extends parallel to the bottom surface of the housing (4) and is bent into a U-shape before the side surfaces (20A) and (20B). The burner (2) has a central position between the height position of the lowest part and the height position of the highest part of the reaction tube (1). Since it is provided on the lower side, the temperature in the reaction tube (1) can be kept more uniform.

Description

  The present invention relates to a pyrolysis furnace including a reaction tube and a burner, and a method for producing a pyrolysis product.

  As a method for producing a certain kind of chemical substance, there is a method obtained by thermally decomposing another chemical substance. For example, as a method for producing vinylidene fluoride (VDF), there is a method of thermally decomposing 1-chloro-1,1-difluoroethane (R-142b) (for example, Patent Document 1). In the process of heating R-142b, a pyrolysis furnace may be used (for example, Patent Document 2).

Japanese Patent Gazette "Japanese Patent Publication No. 42-16282 (published September 4, 1967)" Chinese Patent Application Publication No. CN101003460 (released July 25, 2007)

  In the pyrolysis furnace, for example, a liquid or gaseous raw material is passed through a heated reaction tube, and during that time, it is pyrolyzed in the reaction tube to produce a desired product. At this time, from the viewpoint of the decomposition yield, it is preferable to keep the temperature of the raw material and the product in the reaction tube as uniform as possible.

  The present invention has been made in view of the above problems, and its purpose is a pyrolysis furnace that keeps the temperature in the reaction tube more uniform, and thermal decomposition that performs thermal decomposition while keeping the temperature in the reaction tube more uniform. It is to provide a method for producing the product.

  In order to solve the above problems, a pyrolysis furnace according to the present invention includes a housing, a reaction tube housed in the housing, and a burner for heating the reaction tube. In addition to extending in parallel with the bottom surface of the housing in the housing, it bends in a U-shape before the first side surface of the housing and before the second side surface of the housing facing the first side surface. To form a plurality of parallel portions arranged in a direction perpendicular to the bottom surface, and at least one of the burners is located on the side surface of the casing at the height position of the lowest portion of the reaction tube and It is provided below the center position between the height positions of the high portions.

  A method for producing a pyrolysis product according to the present invention is a method for producing a pyrolysis product, in which a raw material is passed through a reaction tube in a pyrolysis furnace and pyrolyzed. It extends parallel to the bottom surface of the body and bends in a U-shape before the first side surface of the housing and before the second side surface of the housing facing the first side surface, thereby The raw material is passed through a reaction tube forming a plurality of parallel portions arranged in a vertical direction, and at least one of the burners is placed on the side surface of the housing at the height of the lowest portion of the reaction tube. The reaction tube is heated by using it below the center position between the height position and the height position of the highest part.

  According to the present invention, it is possible to provide a thermal decomposition furnace that keeps the temperature in the reaction tube more uniform, and a method for producing a thermal decomposition product that performs thermal decomposition while keeping the temperature in the reaction tube more uniform.

It is the partial exploded view seen from the side of the thermal decomposition furnace which concerns on one Embodiment of this invention. It is sectional drawing seen from the pyrolysis furnace which concerns on one Embodiment of this invention. It is sectional drawing seen from the front of the thermal decomposition furnace which concerns on one Embodiment of this invention. It is a figure which shows a part of structure of the burner provided in the thermal decomposition furnace which concerns on one Embodiment of this invention.

[Pyrolysis furnace]
An embodiment of a pyrolysis furnace according to the present invention will be described with reference to FIGS. FIG. 1: has shown the partial exploded view seen from the side of the thermal decomposition furnace in one Embodiment of this invention, the state which looked at the right half from the outer side of the housing | casing, and the left half has shown the state in a housing | casing. . FIG. 2 shows a cross-sectional view of the pyrolysis furnace as viewed from above according to an embodiment of the present invention. FIG. 3 shows a cross-sectional view as seen from the front of the pyrolysis furnace in one embodiment of the present invention. 1 to 3 are schematic views and do not show accurate dimensions and positions.

  As shown in FIG. 1, the pyrolysis furnace 100 of the present embodiment includes a housing 4, a reaction tube 1, a plurality of burners 2 attached to burner attachment ports (not shown) provided in the housing 4, And an exhaust port 3. Moreover, the lid | cover 10 is attached to the burner attachment port to which the burner 2 is not attached. The pyrolysis furnace 100 is a furnace for producing a pyrolysis product by pyrolyzing a raw material. Although a raw material and its thermal decomposition product are not specifically limited, For example, R-142b is mentioned as a raw material, and it is mentioned that the thermal decomposition product is VDF.

  Details of each component of the pyrolysis furnace 100 will be described below.

(Reaction tube 1)
The reaction tube 1 is a single tube having a U-shaped continuous structure. As shown in FIG. 1, the reaction tube 1 is provided inside the housing 4 of the pyrolysis furnace 100. However, both ends of the reaction tube 1 penetrate the casing 4 and come out of the casing 4. The raw material flows in from the raw material inlet 5 which is one end of the reaction tube 1, passes through the inside of the reaction tube 1, and pyrolysis products, unreacted raw materials and the like from the product stream outlet 6 which is the other end of the reaction tube 1. leak.

  More specifically, the structure of the reaction tube 1 will be described. The reaction tube 1 penetrates the side surface 20A (first side surface) of the housing 4 from the outside of the housing 4 into the housing 4, and extends in parallel with the bottom surface of the housing 4 in the housing 4 so that the parallel portion is formed. It is formed and bent in a U-shape upward (in a direction perpendicular to the bottom surface and away from the bottom surface) before the side surface 20B (second side surface) facing the side surface 20A. Then, it extends again in parallel with the bottom surface of the housing 4 toward the side surface 20A to form a parallel portion, and is bent upward in a U shape before the side surface 20A. Again, it extends parallel to the bottom surface of the housing 4 toward the side surface 20B to form a parallel portion, and is bent upward in a U shape before the side surface 20B. By repeating this, the reaction tube 1 extends in parallel with the bottom surface of the housing 4 in the housing 4 and bends in a U shape in front of the side surface 20A and in front of the side surface 20B. Ascending pipe portion (front half portion) 7 forming a plurality of parallel portions arranged in a vertical direction is configured. When the reaction tube 1 reaches a certain height, it bends in a U shape toward the side surface 20D, and extends in parallel with the bottom surface of the housing 4 in the same manner as the ascending tube portion 7 to form a parallel portion. Before 20B, it is repeatedly bent in a U shape in a downward direction (a direction perpendicular to the bottom surface and approaching the bottom surface). In this way, the reaction tube 1 extends in parallel with the bottom surface of the housing 4 in the housing 4 and bends in a U shape in front of the side surface 20A and in front of the side surface 20B. Downcomer pipe part (second half part) 8 forming a plurality of parallel parts arranged in a vertical direction. The reaction tube 1 passes through the side surface 20 </ b> A from the inside of the housing 4 to the outside of the housing 4 and goes out of the housing 4. In the pyrolysis furnace 100, both ends of the reaction tube 1 protrude from the side surface 20A to the outside of the housing 4, but either the raw material inlet 5 or the product distribution outlet 6 exits from the side surface 20B to the outside of the housing 4. It may be. A raw material inlet 5 is provided at the lowermost stage of the ascending pipe portion 7, and a product distribution outlet 6 is provided at the lowermost stage of the descending pipe portion 8. Further, the uppermost stage of the ascending pipe part 7 and the uppermost stage of the descending pipe part 8 are connected.

  Here, as shown in FIGS. 1 and 3, the ascending pipe part 7 and the descending pipe part 8 are mutually connected so that the parallel part of the ascending pipe part 7 and the parallel part of the descending pipe part 8 are not on the same horizontal plane. They are offset. By arranging the ascending pipe part 7 and the descending pipe part 8 so as to be shifted from each other, there is an advantage that the heat transfer efficiency from the burner 2 to the reaction tube 1 is good. In the pyrolysis furnace 100, the rising pipe portion 7 is arranged so as to be shifted above the downfalling pipe portion 8, but the rising pipe portion 7 may be arranged to be shifted below the downfalling pipe portion 8. . The parallel portions of the folded reaction tubes 1 are arranged in the direction perpendicular to the bottom surface at equal intervals. By being equally spaced, there is an advantage that the temperature uniformity of each stage of the reaction tube 1 can be easily maintained. The number of stages of the ascending pipe part 7 and the descending pipe part 8 is not particularly limited, and may be determined as appropriate according to the dimensions of the housing 4, the inner diameter and length of the reaction tube 1, the raw materials and the thermal decomposition products thereof. As an example, in the pyrolysis furnace 100, the ascending pipe part 7 and the descending pipe part 8 each have 19 stages. That is, the ascending pipe portion 7 constitutes the 1st to 19th stages of the reaction tube 1 from the bottom to the top, and the descending pipe part 8 constitutes the 20th to 38th stages of the reaction tube 1 from the top to the bottom. Yes.

  In the present specification, the “U-shaped continuous structure” refers to a structure in which one pipe is bent into a U shape at two or more locations. The reaction tube having a U-shaped continuous structure may be a tube produced by bending a single tube a plurality of times, or may be a single reaction tube formed by welding or the like. Therefore, the reaction tube 1 of the pyrolysis furnace 100 may be prepared, for example, by separately preparing the rising pipe portion 7 and the downfalling pipe portion 8 and welding them. In addition, each stage of the reaction tube may or may not be in contact with other stages.

  The dimensions of the reaction tube 1 are not particularly limited. For example, the inner diameter is 41 mm to 103 mm and the length is 100 m to 400 m, preferably the inner diameter is 53 mm to 90 mm, and the length is 150 m to 300 m, and particularly preferably the inner diameter is 78 mm. It is about 230m.

  The material of the reaction tube 1 is not particularly limited, but nickel, stainless steel, titanium and the like are preferable from the viewpoint of corrosion resistance at high temperatures, and nickel is more preferable.

  Since the reaction tube 1 has a U-shaped continuous structure, the length that can be accommodated in the housing 4 can be increased. Therefore, the residence time of the raw material can be lengthened. By increasing the residence time of the raw material, the reaction temperature can be set lower than before.

(Burner 2)
The burner 2 is used to heat the reaction tube 1. The burner 2 raises the temperature in the reaction tube 1 by heating the reaction tube 1. In this specification, “to heat the reaction tube” means to apply heat to the reaction tube, to directly apply flame to the reaction tube and to apply heat to the reaction tube, or to directly apply flame to the reaction tube. Without increasing the temperature of the space around the reaction tube and applying heat to the reaction tube by radiant heat.

  Each burner 2 is provided on the side surface 20 </ b> C or the side surface 20 </ b> D of the housing 4 with the flame irradiation port 31 facing the inside of the housing 4. The burner 2 may be a known burner used in a furnace (for example, a pyrolysis furnace). The burner 2 is preferably of a type in which the flame spreads. By using a burner of a type in which the flame spreads, the temperature in the reaction tube 1 can be kept more uniform than when irradiating concentratedly at one point. An example of a specific structure of the burner 2 is shown in FIG. FIG. 4 shows a part of the burner 2. The burner 2 shown in FIG. 4 is a flat frame burner. Examples of the fuel for the burner 2 include air and LNG (for example, methane, ethane, propane, and the like), and may be selected according to the type of the burner 2 to be used. When the burner 2 is a type in which the flame does not spread, it is preferable to provide a wire mesh for spreading the flame between the flame irradiation port 31 and the reaction tube 1.

  The number of burners 2 is not particularly limited and is one or more. In the pyrolysis furnace 100, a total of 16 burners 2 are provided, 8 on the side surface 20C and 8 on the side surface 20D. On the side surface 20C and the side surface 20D, four burners 2 are provided in the lower stage and four in the middle stage, respectively.

  Here, in both the lower and middle burners 2, the lowest position of the reaction tube 1 (the height corresponding to the bottom of the 38th stage in FIG. 3) and the highest position (FIG. 3). In this case, it is provided below the center position (hereinafter referred to as “the 50% height position of the reaction tube 1”) between the first position and the height position corresponding to the upper portion of the 19th stage. The lower and middle burners 2 can efficiently heat the lower portion of the reaction tube 1. Since the warmed gas has a low density and tends to move upward, the air around the reaction tube 1 heated by the lower and middle burners 2 flows upward. Therefore, the part in the position higher than the middle stage in the reaction tube 1 can be heated by the heat from the air. Therefore, the temperature difference in the reaction tube 1 can be suppressed and the temperature in the reaction tube 1 can be kept more uniform.

  The burner 2 may be further provided in the upper stage above the 50% height position of the reaction tube 1, but is preferably provided only in the lower stage and the middle stage. This is because the temperature difference in the reaction tube 1 is smaller when the burner 2 is not provided (or is used but not used) at the upper stage than when the burner 2 is provided at the upper stage (the following implementation). See also example). If the burner 2 is not provided in the upper stage (or provided but not used), the temperature rise at a higher position in the reaction tube 1 is suppressed. Therefore, compared with the case where the upper burner 2 is provided and used, the heating power of the lower and middle burners 2 can be increased. Therefore, the temperature at a low position in the reaction tube 1 can be further increased. Therefore, the temperature difference in the reaction tube 1 can be further suppressed, and the temperature in the reaction tube 1 can be kept more uniform.

  For example, when the height from the bottom surface of the housing 4 to the highest position of the reaction tube 1 is 500 cm and the height from the bottom surface to the lowest position of the reaction tube 1 is 10 cm, the middle burner 2 is It is provided below (500 cm-10 cm) × 0.5 + 10 cm = 255 cm from the bottom surface. The position of the burner 2 is based on the position of the center of the flame irradiation port 31 of the burner 2.

  In the pyrolysis furnace 100, the middle stage is below the 50% height position of the reaction tube 1, and is between the lowest position of the reaction tube 1 and the 50% height position of the reaction tube 1. Above the middle position (25% height position of the reaction tube 1), and the lower stage is lower than the middle stage. Since the height of the burner is two, the temperature control in the reaction tube 1 becomes easier. Moreover, it is because the temperature difference in the reaction tube 1 can be further suppressed and the temperature in the reaction tube 1 can be kept more uniform. Furthermore, since the middle stage is at the above-described height position, a portion of the reaction tube 1 located above the middle stage is efficiently heated. For this reason, since the heating power of the lower burner 2 can be suppressed as compared with the case where the middle stage is not at the above-described height position, the energy efficiency is improved and the life of the reaction tube 1 is also prolonged.

  The lower stage is preferably at a lower position. Since the warmed gas has a low density and tends to move upward, the air around the reaction tube 1 heated by the lower burner 2 flows upward. For this reason, the reaction tube 1 tends to have a low temperature at a low position. By providing a burner at the same height as the lowermost stage of the reaction tube 1, the temperature of the lowermost stage can be raised, the temperature difference in the reaction tube 1 is further suppressed, and the temperature in the reaction tube 1 is kept more uniform. Can do.

  Further, the burner 2 on the side surface 20C and the burner 2 on the side surface 20D, which are at the same height, are arranged at positions shifted in the horizontal direction as shown in FIG. By disposing at a position shifted in the horizontal direction, the temperature in the reaction tube 1 can be kept more uniform than when the same part is intensively heated from both side surfaces.

  Although the distance between the burner 2 and the reaction tube 1 is not particularly limited, in the pyrolysis furnace 100, the burner 2 is disposed at a distance where the flame does not directly hit the reaction tube 1. That is, the pyrolysis furnace 100 increases the temperature of the space around the reaction tube 1 by the flame of the burner 2 and heats the reaction tube 1 by radiant heat. Thereby, compared with the case where the flame of the burner 2 hits the reaction tube 1 directly, it can suppress that the temperature of one point of the reaction tube 1 rises intensively. Therefore, compared with the case where the flame of the burner 2 directly hits the reaction tube 1, the temperature in the reaction tube 1 can be kept more uniform. There is also an advantage that the reaction tube 1 lasts longer.

  A burner attachment port 9 that is an opening for attaching the burner 2 is provided on the side surface 20C and the side surface 20D of the housing 4. A known part capable of fixing the burner 2 may be attached to the burner attachment port 9. Moreover, the burner 2 may be removable from the housing | casing 4, and the well-known components for closing the burner attachment port 9 from which the burner 2 was removed may be provided. In FIG. 3, burner attachment ports 9 are provided in the lower, middle and upper stages, the burner 2 is attached to the lower and middle burner attachment openings 9, and the upper burner attachment opening 9 is closed by the lid 10. Indicates the state.

  In the pyrolysis furnace 100 according to this embodiment, the burner 2 can be attached in two stages (lower stage and middle stage) or three stages (lower stage, middle stage, and upper stage), but is not limited thereto. That is, in another embodiment, the burner 2 may have a configuration that can be attached to only one stage or four stages or more, or the burner 2 may be attached to one stage or four stages or more.

(Exhaust port 3)
The exhaust port 3 is an opening for discharging combustion gas (for example, carbon monoxide and carbon dioxide) generated by the combustion of the burner 2 to the outside of the housing 4. In the pyrolysis furnace 100, the exhaust port 3 is provided at a position higher than the reaction tube 1. Since an air flow toward the exhaust port 3 connected to the outside of the pyrolysis furnace 100 is generated around the reaction tube 1, heat from the burner 2 flows toward the exhaust port 3. Here, since the exhaust port 3 is provided at a position higher than the reaction tube 1, the generated heat is likely to flow toward the exhaust port 3. Even heat will be transmitted easily. As a result, the occurrence of a temperature difference in the reaction tube 1 can be kept low, and the temperature in the reaction tube 1 can be kept more uniform. In the present embodiment, the exhaust port 3 is provided immediately above the reaction tube 1. Thereby, the heat from the burner 2 is more likely to flow toward the exhaust port 3 more evenly. Therefore, heat is uniformly transmitted through the reaction tube 1, and the temperature in the reaction tube 1 can be kept more uniform.

  As shown in FIG. 1, in the pyrolysis furnace 100, the exhaust tube 11 is formed by narrowing the side surface of the housing 4 at a position higher than the reaction tube 1. By reducing the area of the exhaust port 3 in this way, an air flow toward the exhaust port 3 can be more easily generated. The shape and dimensions of the exhaust cylinder 11 are not particularly limited, and may be designed according to the reaction temperature, the displacement, the furnace pressure, and the like.

  The exhaust tube 11 includes a damper 12 on the inner side. The damper 12 is a valve for adjusting the exhaust amount to the exhaust port 3. The damper 12 may be a known damper. The shape and dimensions of the damper 12 are not particularly limited, and may be determined according to the shape and dimensions of the exhaust tube 11. Further, the arrangement of the damper 12 in the exhaust tube 11 is not particularly limited. The damper 12 may be manually controlled, or may be automatically controlled according to temperature, displacement, furnace pressure, and the like. By adjusting the damper 12, the temperature of the air around the reaction tube 1 can be controlled. Thereby, the temperature in the reaction tube 1 can be adjusted.

  In addition, the exhaust cylinder 11 includes a gas sampling port 13. The gas sampling port 13 is an opening for collecting gas inside the housing 4 (outside the reaction tube 1). For example, when measuring the residual oxygen amount, gas is collected. Further, the gas sampling port 13 may include a flange (for example, a plate flange) to which a pipe or the like for sending the collected gas to another device such as a gas detector is attached.

(Case 4)
The housing 4 is a container that houses the reaction tube 1. The material of the housing | casing 4 may be a well-known thing used for a pyrolysis furnace. The shape and dimensions of the housing 4 are not particularly limited as long as the above configuration can be realized.

[Production method of pyrolysis product]
An embodiment of a method for producing a thermal decomposition product according to the present invention will be described.

  In the present embodiment, R-142b (raw material) is pyrolyzed using the above-described pyrolysis furnace 100 to produce VDF (pyrolysis product).

First, R-142b is caused to flow from the raw material inlet 5 of the ascending pipe portion 7 of the reaction tube 1. Although the flow rate is not particularly limited in this case, for example, a 90~250Nm ³ / h, is preferably 125~220Nm ³ / h, more preferably 150~190Nm ³ / h.

  R-142b passes through the riser 7 of the reaction tube 1 upward. At this time, since the reaction tube 1 is heated by the lower and middle burners 2, the temperature of R-142b rises as it passes, and a thermal decomposition reaction occurs. Thereby, VDF which is a thermal decomposition product produces | generates gradually.

  In the manufacturing method according to the present embodiment, the reaction tube 1 is heated by using at least the lower and middle burners 2. That is, at least one of the burners 2 is used on the side surface of the housing 4 below the center position between the lowest position and the highest position of the reaction tube 1. To heat the reaction tube 1. The burner 2 may be used in the upper stage, but it is preferable to use only the lower and middle burners 2. As described above, the temperature difference in the reaction tube 1 is smaller when the burner 2 is not used in the upper stage than when the burner 2 is used in the upper stage. Therefore, the temperature difference in the reaction tube 1 can be suppressed, and thermal decomposition can be performed while keeping the temperature in the reaction tube 1 more uniform (see also the following examples). The temperature in the reaction tube 1 may be set in accordance with the raw material in the reaction tube 1 and the type of the thermal decomposition product thereof. For example, the raw material is R-142b and the thermal decomposition product is VDF. In some cases, the temperature is preferably 500 to 600 ° C.

  Thermal decomposition products, unreacted raw materials and the like flow out from the product stream outlet 6 of the downcomer section 8 of the reaction tube 1. When the raw material is R-142b and the thermal decomposition product is VDF, the conversion rate to VDF by the thermal decomposition reaction of R-142b can be, for example, 80 to 90%.

  In addition, in the manufacturing method which concerns on this invention, R-142b and VDF are a suitable example, and a raw material and its thermal decomposition product are not limited to these.

[Summary]
The pyrolysis furnace according to the present invention includes a housing, a reaction tube housed in the housing, and a burner for heating the reaction tube, and the reaction tube is disposed in the housing within the housing. Perpendicular to the bottom surface by being bent in a U-shape before the first side surface of the housing and before the second side surface of the housing facing the first side surface. The at least one burner has a height position of the lowest portion and a height portion of the highest portion of the reaction tube on the side surface of the casing. It is provided below the center position between.

  According to the said structure, it is low among reaction tubes by the at least 1 burner provided below the center position between the height position of the lowest part of the said reaction tube, and the height position of the highest part. The part in position can be heated efficiently. The air around the reaction tube warmed by the burner provided below the center position flows upward. Therefore, the part in a position higher than the center position can be heated by the heat from the air. Therefore, the temperature difference in the reaction tube can be suppressed and the temperature in the reaction tube can be kept more uniform.

  In the pyrolysis furnace according to the present invention, it is preferable that any of the burners is provided below the center position.

  According to the above configuration, the reaction tube is heated only by a burner provided below the center position between the height position of the lowest part and the height position of the highest part of the reaction tube. Is called. Therefore, the temperature rise at a high position in the reaction tube can be suppressed. Thereby, the heating power of the burner can be increased, and the temperature at a low position in the reaction tube can be increased. Therefore, the temperature difference in the reaction tube can be further suppressed, and the temperature in the reaction tube can be kept more uniform.

  In the pyrolysis furnace according to the present invention, two or more burners are provided below the center position, and at least one of the burners below the center position has a first height. It is preferable that at least one of the burners provided at a position below the center position is provided at a second height position different from the first height position.

  According to the above configuration, since there are at least two burner heights, temperature control in the reaction tube becomes easier. Further, the temperature difference in the reaction tube can be further suppressed, and the temperature in the reaction tube can be kept more uniform.

  In the pyrolysis furnace according to the present invention, the first height position is above a center position between a height position of the lowest part and the center position, and the second height position is It is preferable that the position is lower than the first height position.

  According to the said structure, the part located above the center position between the height position of the said lowest part and the said center position among reaction tubes is by the burner provided in the 1st height position. It is heated efficiently. Therefore, it is possible to suppress the heating power of the burner provided at the second height position. Thus, energy efficiency can be better. Also, the lifetime of the reaction tube can be longer.

  In the pyrolysis furnace according to the present invention, the reaction tube has a front half and a rear half, and each of the front half and the rear half extends in parallel with the bottom surface of the casing in the casing. In addition, a plurality of parallel portions arranged in a direction perpendicular to the bottom surface are formed by being bent into a U shape before the first side surface and before the second side surface, and the lowermost step of the front half portion. It is preferable that a raw material inlet is provided, a product distribution outlet is provided at the lowermost stage of the latter half, and the uppermost stage of the former half is connected to the uppermost stage of the latter half.

  According to the said structure, the length of the reaction tube which can be accommodated in a housing | casing is long. Therefore, the residence time of the raw material becomes long. Therefore, reaction temperature can be set lower than before.

  In the pyrolysis furnace according to the present invention, the burner is preferably disposed at a distance where the flame does not directly hit the reaction tube.

  According to the said structure, the temperature of the air around a reaction tube is raised with the flame of a burner, and a reaction tube is heated with a radiant heat. Thereby, compared with the case where the flame of a burner hits a reaction tube directly, it can suppress that the temperature of one point of a reaction tube rises intensively. Therefore, the temperature in the reaction tube can be kept more uniform.

  In the pyrolysis furnace according to the present invention, it is preferable that an exhaust port is provided at a position higher than the reaction tube.

  According to the above configuration, an air flow toward the exhaust port connected to the outside of the pyrolysis furnace is generated around the reaction tube. Therefore, the generated heat can easily flow toward the exhaust port, and heat can be easily transmitted to a higher portion of the reaction tube. Therefore, the temperature difference in the reaction tube can be further suppressed, and the temperature in the reaction tube can be kept more uniform.

  A method for producing a pyrolysis product according to the present invention is a method for producing a pyrolysis product, in which a raw material is passed through a reaction tube in a pyrolysis furnace and pyrolyzed. It extends parallel to the bottom surface of the body and bends in a U-shape before the first side surface of the housing and before the second side surface of the housing facing the first side surface, thereby The raw material is passed through a reaction tube forming a plurality of parallel portions arranged in a vertical direction, and at least one of the burners is placed on the side surface of the housing at the height of the lowest portion of the reaction tube. The reaction tube is heated by using it below the center position between the height position and the height position of the highest part.

  According to the said structure, it is low among reaction tubes by the at least 1 burner provided below the center position between the height position of the lowest part of the said reaction tube, and the height position of the highest part. The part in position can be heated efficiently. The air around the reaction tube warmed by the burner provided below the center position flows upward. Therefore, the part in a position higher than the center position can be heated by the heat from the air. Therefore, thermal decomposition can be performed while suppressing the temperature difference in the reaction tube and keeping the temperature in the reaction tube more uniform.

  In the method for producing a thermal decomposition product according to the present invention, it is preferable to heat the reaction tube by using any of the burners below the center position.

  According to the above configuration, the reaction tube is heated only by a burner provided below the center position between the height position of the lowest part and the height position of the highest part of the reaction tube. Is called. Therefore, the temperature rise at a high position in the reaction tube can be suppressed. Thereby, the heating power of the burner can be increased, and the temperature at a low position in the reaction tube can be increased. Therefore, thermal decomposition can be performed while suppressing the temperature difference in the reaction tube and keeping the temperature in the reaction tube more uniform.

  In the method for producing a thermal decomposition product according to the present invention, the reaction tube has a first half part and a second half part, and the bottom surface of the casing is formed in the casing in each of the first half part and the second half part. And is bent in a U shape before the first side surface and before the second side surface, thereby forming a plurality of parallel portions aligned in a direction perpendicular to the bottom surface. The lowermost part of the part has a raw material inlet, the lowermost part of the latter part has a product distribution outlet, and the uppermost part of the former part and the uppermost part of the latter part are connected to each other. It is preferable.

  According to the said structure, the length of the reaction tube which can be accommodated in a housing | casing is long. Therefore, the residence time of the raw material becomes long. Therefore, reaction temperature can be set lower than before.

  In the method for producing a thermal decomposition product according to the present invention, it is preferable that the flame of the burner is not directly applied to the reaction tube.

  According to the said structure, the temperature of the air around a reaction tube is raised with the flame of a burner, and a reaction tube is heated with a radiant heat. Thereby, compared with the case where the flame of a burner hits a reaction tube directly, it can suppress that the temperature of one point of a reaction tube rises intensively. Therefore, thermal decomposition can be performed while keeping the temperature in the reaction tube more uniform.

  In the method for producing a thermal decomposition product according to the present invention, the raw material is preferably 1-chloro-1,1-difluoroethane, and the thermal decomposition product is preferably vinylidene fluoride.

  According to the above configuration, vinylidene fluoride can be produced more efficiently.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The relationship between the position of the burner and the temperature in the reaction tube (gas temperature) was examined using the pyrolysis furnace shown in FIG. The reaction tube is made of nickel.

(Method)
In Example 1, the reaction tube was heated using 8 burners each provided in the lower and middle stages. In Example 2, the reaction tube was heated using 8 burners each provided in the lower, middle and upper stages. The lower burner is provided at a height position between the second stage and the third stage and at a height position of the 37th stage. The middle burner is provided at a height position between the seventh and eighth stages and a height position of the thirty-second stage. The upper burner is provided at the height position of the 13th stage and the height position between the 26th and 27th stages.

R-142b preliminarily set to about 30 ° C. was introduced from the raw material inlet of the reaction tube at a flow rate of about 125 Nm ³ / h. The operation was continued for 10 days, and the temperatures at the 5, 10, 15, 19, 24, 29, 34, and 38th stages were measured once a day. In both Example 1 and Example 2, the control operation was performed so that the maximum temperature was about 600 ° C.

(result)
The results of Example 1 and Example 2 are shown in Table 1. In addition, the value of Table 1 is an average value for 10 days per time / day.

  In Example 1, the temperature difference in the reaction tube was smaller than that in Example 2. That is, it was found that the temperature in the reaction tube could be kept more uniform by not using the upper burner.

  The pyrolysis furnace and the method for producing a pyrolysis product according to the present invention can be used when pyrolyzing a raw material in a reaction tube to produce a pyrolysis product.

DESCRIPTION OF SYMBOLS 1 Reaction tube 2 Burner 3 Exhaust port 4 Housing | casing 5 Raw material inlet 6 Product stream outlet 7 Rising pipe part (first half)
8 Downcomer section (second half)
9 Burner mounting port 10 Lid 11 Exhaust tube 12 Damper 13 Gas sampling port 20A Side surface (first side surface)
20B side surface (second side surface)
20C side surface 20D side surface 31 Flame irradiation port 100 Pyrolysis furnace

Claims (12)

A housing, a reaction tube housed in the housing, and a burner for heating the reaction tube,
The reaction tube extends in parallel with the bottom surface of the housing in the housing, and U in front of the first side surface of the housing and in front of the second side surface of the housing facing the first side surface. By bending into a letter, it forms a plurality of parallel parts arranged in a direction perpendicular to the bottom surface,
At least one of the burners is provided on the side surface of the housing below the central position between the lowest position and the highest position of the reaction tube. Furnace.   The pyrolysis furnace according to claim 1, wherein any of the burners is provided below the center position.   Two or more burners are provided below the center position, and at least one of the burners below the center position is provided at a first height position, and the center The pyrolysis furnace according to claim 1 or 2, wherein at least one of the other burners below the position is provided at a second height position different from the first height position.   The first height position is above a center position between the height position of the lowest part and the center position, and the second height position is higher than the first height position. The pyrolysis furnace according to claim 3, which is at a low position. The reaction tube
It has a first half and a second half,
In each of the front half part and the second half part, it extends in parallel with the bottom surface of the housing in the housing, and bends in a U shape before the first side surface and before the second side surface, Forms a plurality of parallel portions arranged in a direction perpendicular to the bottom surface,
The bottom half of the front half has a raw material inlet, and the bottom half of the latter half has a product distribution outlet,
The pyrolysis furnace according to any one of claims 1 to 4, wherein the uppermost stage of the front half and the uppermost stage of the latter half are connected to each other.   The pyrolysis furnace according to any one of claims 1 to 5, wherein the burner is disposed at a distance at which a flame does not directly hit the reaction tube.   The pyrolysis furnace according to any one of claims 1 to 6, wherein an exhaust port is provided at a position higher than the reaction tube. A method for producing a pyrolysis product, in which a raw material is passed through a reaction tube in a pyrolysis furnace and pyrolyzed,
A U-shape extending in parallel with the bottom surface of the housing in the housing of the pyrolysis furnace, and in front of the first side surface of the housing and the second side surface of the housing facing the first side surface. The raw material is passed through a reaction tube forming a plurality of parallel portions arranged in a direction perpendicular to the bottom surface, and at least one of the burners is attached to the side surface of the casing. A method for producing a pyrolysis product, wherein the reaction tube is heated by using it below a central position between the height position of the lowest part of the reaction tube and the height position of the highest part of the reaction tube.   The method for producing a thermal decomposition product according to claim 8, wherein any of the burners is used below the center position to heat the reaction tube. The reaction tube
It has a first half and a second half,
In each of the front half part and the second half part, it extends in parallel with the bottom surface of the housing in the housing, and bends in a U shape before the first side surface and before the second side surface, Forms a plurality of parallel portions arranged in a direction perpendicular to the bottom surface,
The bottom half of the front half has a raw material inlet, and the bottom half of the latter half has a product distribution outlet,
The method for producing a thermal decomposition product according to claim 8 or 9, wherein the uppermost stage of the first half and the uppermost stage of the second half are connected.   The method for producing a thermal decomposition product according to any one of claims 8 to 10, wherein the flame of the burner is not directly applied to the reaction tube.   The method for producing a thermal decomposition product according to any one of claims 8 to 11, wherein the raw material is 1-chloro-1,1-difluoroethane, and the thermal decomposition product is vinylidene fluoride.

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