Supercritical foaming kettle

Abstract

The utility model discloses a supercritical foaming kettle which comprises a horizontal kettle body, an air inlet connecting pipe, a pressure measuring connecting pipe and a plurality of temperature measuring connecting pipes are arranged on the outer wall of the kettle body, a kettle cover and a hoop are arranged at a kettle opening, an inner circulating fan is arranged at the kettle bottom, and an upper air duct, a middle air duct and a lower air duct are arranged in the kettle body. A plurality of outer fin heating pipe groups are respectively arranged in the upper air duct, the middle air duct and the lower air duct along the trend of the kettle body, heat-conducting oil inlet pipes and heat-conducting oil outlet pipes of the outer fin heating pipe groups penetrate through the kettle wall and are connected with a heat-conducting oil circulating pipeline outside the kettle body, and a plurality of pressure relief connecting pipes are arranged on the outer wall of the kettle body on two sides of the middle air duct along the length direction of the kettle body; an inner pressure relief pipe for communicating the pressure relief connecting pipes on the side is arranged on the inner wall of the kettle body on the two sides of the middle air channel along the length direction of the kettle body; and a plurality of pressure relief holes are formed in the wall of the inner pressure relief pipe at equal intervals. The heating efficiency of supercritical fluid in the kettle body of the supercritical foaming kettle is high, the temperature difference between the upper layer and the lower layer in the kettle body is small, and materials loaded in the kettle body cannot be scattered due to pressure relief of the kettle body.

Description

Technical Field

[0001] This utility model relates to a pressure vessel, and more particularly to a foaming kettle that uses supercritical fluid to foam thermoplastic polyurethane elastomer rubber. Background Technology

[0002] Supercritical foaming involves immersing a supercritical fluid into the interior of a thermoplastic polyurethane elastomer in a foaming vessel, then rapidly releasing the pressure. The supercritical fluid inside the thermoplastic polyurethane elastomer expands rapidly, forming a porous structure within the elastomer, thus achieving the foaming effect. CN 219522831 U discloses a foaming reactor for supercritical foaming molding, relating to the field of supercritical foaming molding. It includes a reactor body, a reactor lid, and a heating jacket. The reactor body has a loading port, a pressurizing port, and a pressure relief port. The reactor lid is located on the loading port. The heating jacket has a heat transfer oil inlet and a heat transfer oil outlet. The reactor lid has a heating coil. A centrifugal fan for heat homogenization is located on the side of the reactor body away from the reactor lid. The casing of the centrifugal fan is located inside the reactor body, with its air inlet opposite the reactor lid. An air supply pipe is located inside the reactor body, with one end connected to the air outlet of the centrifugal fan and the other end extending to the reactor lid. The drive motor of the centrifugal fan is located outside the reactor body, and the output shaft of the drive motor passes through the reactor body and is connected to the impeller of the centrifugal fan. This invention can achieve temperature uniformity and minimal difference at different locations within the reactor body, meeting the temperature requirements of the supercritical foaming process, and producing high-quality foamed products with a low scrap rate. However, in actual use, because the heating jacket of this supercritical foaming molding kettle is located on the outer wall of the kettle body, the gas inside the kettle is heated by the kettle wall. Since the kettle wall is usually a smooth metal wall, the contact and heat exchange area with the gas is limited, resulting in low heating efficiency. Secondly, when the diameter of the foaming kettle is large, the temperature distribution in the vertical direction inside the kettle is uneven, exhibiting a characteristic of high temperature at the top and low temperature at the bottom. This causes different foaming expansion effects between the upper and lower layers of products in the same kettle, affecting product quality. In addition, when the volume of the foaming kettle is large, in order to meet the requirements of instantaneous pressure relief, the diameter of the pressure relief pipe needs to be increased. However, increasing the diameter of the pressure relief pipe will cause a high-speed airflow to form inside the kettle body during the instantaneous pressure relief. The concentrated and rapid flow of airflow towards the pressure relief pipe can cause the material inside the kettle to detach from the hanger or rush towards the pressure relief pipe opening, making unloading difficult. Utility Model Content

[0003] The technical problem to be solved by the utility model is to overcome the aforementioned defects of the prior art and provide a supercritical foaming kettle. The supercritical fluid in the kettle body has high heating efficiency, small temperature difference between the upper and lower layers inside the kettle body, and the pressure relief of the kettle body will not cause the material loaded inside to scatter.

[0004] The technical solution adopted to solve the technical problem is as follows: A supercritical foaming reactor includes a horizontal reactor body. An air inlet pipe, a pressure measuring pipe, and multiple temperature measuring pipes are provided on the outer wall of the reactor body. A reactor lid and clamps are provided at the reactor mouth. An internal circulation fan is provided at the bottom of the reactor. Parallel upper and lower air duct plates are arranged along the reactor body's direction on the inner wall of the reactor body. The two sides of the upper and lower air duct plates are connected to the inner wall of the reactor body along its length, thereby dividing the reactor body into an upper air duct, a middle air duct, and a lower air duct. At the bottom end of the upper and lower air duct plates, an air duct end plate is provided to close the end of the middle air duct. A central opening of the air duct end plate, with a size and shape matching the air inlet of the internal circulation fan, is located on the center of the air duct end plate. The upper and lower air duct plates are equipped with corresponding air inlets. An axial gap is left between the vessel opening and the vessel cover to allow airflow to enter the middle air duct from the upper and lower air ducts. Multiple external finned heating tube assemblies are installed in the upper, middle, and lower air ducts along the vessel body. The heat transfer oil inlet and outlet pipes of the external finned heating tube assemblies pass through the vessel wall and are connected to the heat transfer oil circulation pipeline outside the vessel body. Multiple pressure relief pipes are installed on the outer wall of the vessel body on both sides of the middle air duct along the length of the vessel body. An inner pressure relief pipe is installed on the inner wall of the vessel body on both sides of the middle air duct along the length of the vessel body, connecting the multiple pressure relief pipes on this side. Multiple pressure relief holes are opened at equal intervals along the length of the inner pressure relief pipe.

[0005] As a further improvement of this utility model: the internal pressure relief pipe is composed of a half-pipe that is welded to the inner wall of the vessel.

[0006] As a further improvement of this utility model: the vessel body is welded together with a cylindrical body and a bottom end cap. A fan mounting pipe coaxial with the cylindrical body is connected to the center of the bottom end cap. A fan cover plate is provided at the outer port of the fan mounting pipe to close the outer port of the fan mounting pipe. An electric wire through-plate sealing assembly is provided on the fan cover plate to allow the external power supply wire to pass through the fan cover plate and enter the inside of the fan mounting pipe. The internal circulation fan is a centrifugal shellless fan consisting of a drive motor and a centrifugal impeller installed on the shaft end of the drive motor. The drive motor is fixed inside the fan mounting pipe. The circular air inlet end face of the centrifugal impeller is close to the air duct end plate and concentrically fitted with the air inlet hole.

[0007] As a further improvement of this utility model: an inner heater is provided on the inner wall of the kettle lid, and the heat transfer oil inlet pipe and heat transfer oil outlet pipe of the inner heater pass through the kettle lid and are connected to the heat transfer oil circulation pipeline outside the kettle body.

[0008] As a further improvement of this utility model: the outer finned heating tube assembly is composed of four outer finned tubes arranged in parallel along the length of the vessel body and connected end to end in sequence. At both ends of the outer finned heating tube assembly, there are welded tubes that penetrate the vessel wall. Between the welded tubes that penetrate the vessel wall and the outer finned tubes, there is a telescopic bend that can absorb the thermal expansion and contraction deformation of the outer finned tubes.

[0009] As a further improvement of this utility model: the outer wall of the outer finned tube is provided with a number of wingless segments for fixing the outer finned tube.

[0010] As a further improvement of this utility model: the heater inside the lid includes an upper main pipe and a lower main pipe arranged in parallel, with multiple external finned tubes connected in parallel between the upper and lower main pipes, a heat transfer oil inlet pipe connected to the upper main pipe, and a heat transfer oil outlet pipe connected to the lower main pipe.

[0011] Beneficial Effects: This invention's supercritical foaming reactor utilizes an internal circulation fan within the reactor body. The reactor is divided into upper, middle, and lower air ducts by upper and lower air duct plates. By incorporating end plates for the air ducts and maintaining axial gaps between the reactor openings and the reactor lid, the supercritical fluid is heated in the upper and lower air ducts before converging and circulating in the middle air duct. This effectively avoids the uneven temperature distribution in the vertical direction common in large-diameter foaming reactors, resulting in a more uniform temperature distribution, better consistency in material expansion ratios across different regions, and higher quality foamed products. Furthermore, the use of external finned heating tubes within the reactor body directly heats the supercritical fluid, overcoming the small heat exchange area between the reactor's inner wall and the supercritical fluid. The external finned heating tubes also offer higher heating efficiency and less heat loss. Furthermore, due to the technical feature of installing internal pressure relief pipes along the length of the vessel body on both sides of the central air duct, and having multiple pressure relief holes evenly spaced along the length of the internal pressure relief pipe wall, the pressurized gas inside the vessel body flows into the internal pressure relief pipe through the pressure relief holes during pressure relief, and is then discharged through the pressure relief pipe on the vessel wall. This effectively avoids the formation of high-speed airflow that can easily disperse materials inside the vessel body due to the large diameter of the pressure relief pipe, making the unloading operation of the supercritical foaming vessel of this invention more convenient. By using the aforementioned technical features, the diameter and length of the supercritical foaming vessel of this invention can also be made larger, the effective volume inside the vessel body is larger, the production capacity is greater, and the foaming cost is lower. Because the internal pressure relief pipe is composed of a half-pipe welded to the inner wall of the vessel body, while ensuring the pressure relief effect, the structure of the internal pressure relief pipe is simpler, and its fixation inside the vessel is more secure, resulting in stronger impact and collision resistance. Because the vessel body is constructed by welding a cylindrical body and a bottom end cap, and a fan mounting pipe coaxial with the cylindrical body is connected to the center of the bottom end cap, a fan cover plate is provided at the outer port of the fan mounting pipe to seal the outer port of the fan mounting pipe, and an electric wire through-plate sealing assembly is provided on the fan cover plate to allow external power wires to pass through the fan cover plate and enter the inside of the fan mounting pipe, the internal circulation fan is a centrifugal shellless fan consisting of a drive motor and a centrifugal impeller mounted on the shaft end of the drive motor. The drive motor is fixed inside the fan mounting pipe, and the circular air inlet end face of the centrifugal impeller is close to the air duct end plate and concentrically fitted with the air inlet hole. This technical feature avoids the problem of poor sealing between the motor shaft and the vessel wall when the drive motor is installed outside the vessel body. At the same time, the drive motor installed inside the fan mounting pipe is easier to dissipate heat, and the cooling treatment of the drive motor has less impact on the internal temperature of the vessel body. The use of a heater inside the kettle lid, with the inlet and outlet pipes of the heater connected to the heat transfer oil circulation pipeline outside the kettle body, further improves the uniformity of the temperature distribution of the supercritical fluid inside the kettle.Because the external finned heating tube assembly consists of four parallel external finned tubes arranged along the length of the vessel body and connected end-to-end, with welded pipes penetrating the vessel wall at both ends and expansion bends between these welded pipes and the external finned tubes to absorb thermal expansion and contraction, the heat exchange efficiency of the external finned tubes is ensured while preventing thermal cracking and leakage caused by thermal expansion and contraction. The external finned tubes also feature several finless segments on their outer walls for securing them, making their fixation within the vessel body easier and more secure. Furthermore, the internal heater within the vessel lid comprises a parallel upper and lower main pipe with multiple external finned tubes connected in parallel between them. A heat transfer oil inlet pipe is connected to the upper main pipe, and a heat transfer oil outlet pipe is connected to the lower main pipe, resulting in improved heating performance for supercritical fluids. Attached Figure Description

[0012] The supercritical foaming reactor of this utility model will be further described in detail below with reference to the accompanying drawings.

[0013] Figure 1 This is a schematic diagram of the axial cross-sectional structure of the supercritical foaming reactor of this utility model;

[0014] Figure 2 This is a schematic diagram of the radial cross-sectional structure of the supercritical foaming reactor of this utility model;

[0015] Figure 3 This is a schematic diagram of the structure of the outer finned heating tube assembly in the supercritical foaming reactor of this utility model;

[0016] Figure 4 This is a schematic diagram of the structure of the heater inside the lid of the supercritical foaming reactor of this utility model. Detailed Implementation

[0017] like Figure 1 , Figure 2As shown, the supercritical foaming reactor of this utility model includes a horizontal reactor body. An air inlet pipe 4, a pressure measuring pipe, and multiple temperature measuring pipes 16 are provided on the outer wall of the reactor body. A reactor cover 20 and a clamp 19 are provided at the reactor opening. An internal circulation fan is provided at the bottom of the reactor body, where the bottom refers to the end of the reactor body away from the reactor opening. Parallel upper air duct plates 12 and lower air duct plates 13 are arranged along the direction of the reactor body on the inner wall of the reactor body. The two side edges of the upper and lower air duct plates are respectively connected to the inner wall of the reactor body along the length of the reactor body, thereby dividing the reactor body into an upper air duct 8, a middle air duct 9, and a lower air duct 10. An air duct end plate that closes the end of the middle air duct is provided at the bottom end of the upper and lower air duct plates. 7. An air inlet hole 24, corresponding to the size, shape and position of the air inlet of the internal circulation fan, is opened at the center of the air duct end plate. An axial gap is left between the vessel mouth end of the upper air duct plate and the vessel cover to allow airflow to enter the middle air duct from the upper air duct and the lower air duct. The air outlet of the internal circulation fan is connected to the upper air duct and the lower air duct. When the internal circulation fan is working, the supercritical fluid enters the upper air duct and the lower air duct through the air outlet of the internal circulation fan. The supercritical fluid flows towards the vessel mouth in the upper air duct and the lower air duct, and merges into the middle air duct at the vessel mouth end. It flows towards the bottom of the vessel in the middle air duct and enters the air inlet of the internal circulation fan, thus circulating inside the vessel.

[0018] Multiple external finned heating tube assemblies are installed along the direction of the vessel body in the upper air duct, middle air duct and lower air duct respectively. The heat transfer oil inlet pipe and heat transfer oil outlet pipe of the external finned heating tube assembly pass through the vessel wall and are connected to the heat transfer oil circulation pipeline 22 outside the vessel body. Multiple pressure relief pipes 15 are installed on the outer wall of the vessel body on both sides of the middle air duct along the length of the vessel body. The pressure relief pipes are welded to the vessel wall radially along the vessel body. An inner pressure relief pipe 17 is installed on the inner wall of the vessel body on both sides of the middle air duct along the length of the vessel body, which connects the multiple pressure relief pipes on this side. Multiple pressure relief holes 18 are opened at equal intervals along the length of the inner pressure relief pipe wall.

[0019] Preferably, the internal pressure relief pipe is composed of a half-pipe that is welded to the inner wall of the vessel.

[0020] Preferably, the vessel body is welded together from a cylindrical body 14 and a bottom end cap 5. A fan mounting pipe 3, coaxial with the cylindrical body, is connected to the center of the bottom end cap. A fan cover plate 2 is provided at the outer port of the fan mounting pipe to close the outer port of the fan mounting pipe. An electric wire through-plate sealing assembly 1 is provided on the fan cover plate to allow external power wires to pass through the fan cover plate and enter the inside of the fan mounting pipe. The internal circulation fan is a centrifugal shellless fan composed of a drive motor 21 and a centrifugal impeller 6 installed at the shaft end of the drive motor. The drive motor is fixed inside the fan mounting pipe. The circular air inlet end face of the centrifugal impeller is close to the air duct end plate and the air inlet hole is concentrically fitted.

[0021] Preferably, an internal heater 23 is provided on the inner wall of the vessel lid. The heat transfer oil inlet and outlet pipes of the internal heater pass through the vessel lid and are connected to the heat transfer oil circulation pipeline outside the vessel body. Figure 4As shown, the heater inside the vessel lid includes an upper main pipe 29 and a lower main pipe 32 arranged in parallel. Multiple external finned tubes 30 are connected in parallel between the upper and lower main pipes. A heat transfer oil inlet pipe 28 is connected to the upper main pipe, and a heat transfer oil outlet pipe 31 is connected to the lower main pipe.

[0022] like Figure 3 As shown, the outer finned heating tube assembly consists of four outer finned tubes 11 arranged in parallel along the length of the vessel body and connected end to end. At both ends of the outer finned heating tube assembly, there are welded tubes 25 that penetrate the vessel wall. The welded tubes are inserted into the openings in the vessel wall and welded to the vessel wall. Between the welded tubes and the outer finned tubes, there is a telescopic bend 26 that can absorb the thermal expansion and contraction deformation of the outer finned tubes.

[0023] Preferably, the outer wall of the outer finned tube is provided with a plurality of finless segments 27 for fixing the outer finned tube, and the outer finned tube is fixed to the inner wall of the vessel body by using clamps on the finless segments of the outer finned tube.

[0024] During operation, the supercritical fluid circulates within the supercritical foaming reactor of this invention, resulting in a uniform temperature distribution within the reactor. When the reactor is rapidly depressurized, the airflow disperses from the reactor body into the depressurization hole, preventing the formation of a high-speed airflow that can disperse materials within the reactor body. This allows the supercritical foaming reactor of this invention to be made larger, with an inner diameter of up to 1 meter and a length of up to 6 meters, resulting in greater production capacity.

Claims

1. A supercritical foaming reactor, comprising a horizontal reactor body, an air inlet pipe, a pressure measuring pipe, and multiple temperature measuring pipes provided on the outer wall of the reactor body, and a reactor lid and clamps provided at the reactor mouth, characterized in that: An internal circulation fan is installed at the bottom of the vessel. Parallel upper and lower air duct plates are arranged along the vessel's inner wall. The two sides of the upper and lower air duct plates connect to the inner wall of the vessel along its length, thus dividing the vessel into upper, middle, and lower air ducts. Air duct end plates, which seal the end of the middle air duct, are located at the bottom ends of the upper and lower air duct plates. An air inlet hole, corresponding to the size, shape, and position of the internal circulation fan's inlet, is located at the center of the air duct end plate. A space is left between the vessel opening of the upper and lower air duct plates and the vessel lid to allow airflow. The axial clearance between the upper and lower air ducts and the middle air duct is provided. Multiple external finned heating tube assemblies are installed in the upper, middle and lower air ducts along the direction of the vessel body. The heat transfer oil inlet and outlet pipes of the external finned heating tube assemblies pass through the vessel wall and are connected to the heat transfer oil circulation pipeline outside the vessel body. Multiple pressure relief pipes are provided on the outer wall of the vessel body on both sides of the middle air duct along the length of the vessel body. An inner pressure relief pipe is provided on the inner wall of the vessel body on both sides of the middle air duct along the length of the vessel body, which connects the multiple pressure relief pipes on this side. Multiple pressure relief holes are opened at equal intervals along the length of the inner pressure relief pipe.

2. The supercritical foaming reactor according to claim 1, characterized in that: The internal pressure relief pipe is composed of a half-pipe welded to the inner wall of the vessel.

3. The supercritical foaming reactor according to claim 1 or 2, characterized in that: The vessel body is constructed by welding a cylindrical body and a bottom end cap. A fan mounting pipe coaxial with the cylindrical body is connected to the center of the bottom end cap. A fan cover plate is provided at the outer port of the fan mounting pipe to seal the outer port of the fan mounting pipe. An electric wire through-plate sealing assembly is provided on the fan cover plate to allow external power wires to pass through the fan cover plate and enter the fan mounting pipe. The internal circulation fan is a centrifugal shellless fan consisting of a drive motor and a centrifugal impeller mounted on the shaft end of the drive motor. The drive motor is fixed inside the fan mounting pipe. The circular air inlet end face of the centrifugal impeller is close to the air duct end plate and concentrically fitted with the air inlet hole.

4. The supercritical foaming reactor according to claim 3, characterized in that: An internal heater is installed on the inner wall of the kettle lid. The heat transfer oil inlet and outlet pipes of the internal heater pass through the kettle lid and are connected to the heat transfer oil circulation pipeline outside the kettle body.

5. The supercritical foaming reactor according to claim 4, characterized in that: The outer finned heating tube assembly consists of four parallel outer finned tubes arranged along the length of the vessel body and connected end to end. At both ends of the outer finned heating tube assembly, there are welded tubes that penetrate the vessel wall. Between the welded tubes that penetrate the vessel wall and the outer finned tubes, there are expansion and contraction bends that can absorb the thermal expansion and contraction deformation of the outer finned tubes.

6. The supercritical foaming reactor according to claim 5, characterized in that: The outer wall of the outer finned tube is provided with several finless segments for fixing the outer finned tube.

7. The supercritical foaming reactor according to claim 4, characterized in that: The heater inside the vessel lid includes an upper main pipe and a lower main pipe arranged in parallel. Multiple external finned tubes are connected in parallel between the upper and lower main pipes. A heat transfer oil inlet pipe is connected to the upper main pipe, and a heat transfer oil outlet pipe is connected to the lower main pipe.

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