Double-screw extruder with full-stage heat recovery function

Abstract

The utility model relates to a double-screw extruder with a full-stage heat recovery function. The double-screw extruder comprises a hopper, a screw unit, a melt conveying section, a forming section, an evaporator, a pressure tank, a heat exchange air duct, a switching part, a hot water duct tube nest part and a hot air duct tube nest part, a water inlet pipe and a water outlet pipe of the evaporator are connected with water outlet pipes and water inlet pipes of the screw units respectively. The pressure tank is provided with an air inlet pipeline and an air exhaust pipeline, and the air exhaust pipeline is matched with the hopper. And a heat exchange medium coil pipe main body of the evaporator is arranged in the pressure tank. The heat exchange air duct is arranged outside the forming section and provided with an air inlet pipeline and an air exhaust pipeline. The switching part comprises a first channel part and a second channel part. The hot water channel tube nest part and the hot air channel tube nest part are both fixedly arranged on the periphery of the melt conveying section. The water inlet end of the hot water channel tube nest part communicates with the water outlet pipe of the screw unit, and the water outlet end is connected with the water inlet pipe. The exhaust pipeline is connected with the air inlet end of the hot air channel tube nest part through the second channel part. According to the double-screw extruder, heat released by the double-screw extruder can be recycled.

Description

Technical Field

[0001] The utility model relates to the field of twin-screw extruder equipment, in particular to a twin-screw extruder with a full-stage heat recovery function. Background Art

[0002] When the twin-screw extruder is working, the material first enters the feeding unit for high-temperature drying, and the dried material is fed into the screw unit for extrusion production. The entire extrusion process includes all or part of the feeding section, melting section, melt conveying section, mixing section, air exhaust section, homogenization section, vacuum exhaust section, metering section, etc. During the extrusion production process of the screw unit, because the screw is kept in a high-speed rotating state, the heat energy converted into mechanical energy is much greater than the heat energy required for the material to change state (phase change), so a large amount of waste heat will be generated during the extrusion production process, so the screw unit is equipped with a cooling mechanism. The commonly used cooling mechanism is a water circulation cooling twin-screw extruder screw body. In addition, after the material is extruded by the screw unit, it needs to be kept in a better molten state in the melt conveying section until it reaches the molding unit. Usually, the melt conveying section is equipped with an electric heating mechanism. After the molten material enters the molding section, it is cooled and shaped.

[0003] It can be seen that in the entire production process of the twin-screw extruder, there are complex situations such as some sections need heat energy, some sections generate a lot of heat energy, and some sections need to release and convert heat energy. That is, in the extrusion production process and the molding process of the screw, the temperature of the screw unit and the molding discharge section are both high, and both need to be cooled down. However, the existing twin-screw extruders generally waste a lot of heat in these two processes. Utility Model Content

[0004] In view of the heat waste problem existing in the twin-screw extruder, the utility model provides a twin-screw extruder with a full-stage heat recovery function, which can realize the recovery and utilization of the heat released in the screw unit and the molding unit while ensuring the normal operation of the extruder, so that the heat can be effectively recycled in the production operation process of the twin-screw extruder, and has the advantages of energy saving and environmental protection.

[0005] The technical solution adopted by the utility model to solve its technical problems is: a twin-screw extruder with a full-stage heat recovery function, including a hopper, a screw unit, a melt conveying section, a molding section, an evaporator, a pressure tank, a heat exchange air duct, a switching part, a hot water duct tube section and a hot air duct tube section.

[0006] The screw unit includes a water circulation cooling mechanism, and the water circulation cooling mechanism includes a water inlet pipe and a water outlet pipe. The water inlet pipe is used to feed cold water into the water circulation cooling mechanism, and the water outlet pipe is used to discharge hot water flowing out of the water circulation cooling mechanism.

[0007] The water inlet pipe of the evaporator is connected to the water outlet pipe of the screw unit, and the drain pipe of the evaporator is connected to the water inlet pipe of the screw unit, so that a water circulation system can be established between the water tank of the evaporator and the water circulation cooling mechanism of the screw unit.

[0008] The pressure tank is provided with an air inlet duct and an air exhaust duct connected to the tank cavity, and a duct exhaust fan is provided on the air inlet duct to send outside air into the tank cavity of the pressure tank. The exhaust duct matches the hopper and can send the heated air into the hopper and be used to dry the material.

[0009] The heat exchange medium coil body of the evaporator is arranged in the tank cavity of the pressure tank, and a compressor is arranged on the inlet pipeline of the heat exchange medium coil body, and an expansion valve is arranged on the discharge pipeline of the heat exchange medium coil body.

[0010] The evaporator can transfer the heat energy carried by the hot water output by the screw unit to the air in the pressure tank, so that a large amount of hot air is accumulated in the tank cavity of the pressure tank.

[0011] The heat exchange air duct is arranged outside the forming section. The heat exchange air duct is provided with an air inlet pipeline connected with its annular cavity and a fan is arranged on the air inlet pipeline, and the fan can send external air into the annular cavity of the heat exchange air duct.

[0012] An exhaust pipe communicating with the annular cavity is provided on the heat exchange air duct, and a pipeline fan 2 and a check valve are provided on the exhaust pipe;

[0013] The transition part includes a channel part one and a channel part two.

[0014] The hot water channel tube array part and the hot air channel tube array part are both fixedly arranged on the outer wall of the melt conveying section.

[0015] The water inlet end of the hot water channel tube section is connected to the water outlet pipe of the screw unit, and the water outlet end is connected to the channel section and finally connected to the water inlet pipe of the evaporator through a connecting pipe.

[0016] The exhaust pipe on the heat exchange air duct is connected to the air inlet end of the hot air duct tube section through the second channel section.

[0017] Optionally, the exhaust end of the hot air duct array is connected to the air inlet duct of the pressure tank through a return air duct. At this time, a one-way valve or a check valve can be set on the air inlet duct so that the air in the duct can only flow into the tank cavity of the pressure tank.

[0018] Optionally, the hot water channel tube section is fixedly mounted on the outer wall of the melt conveying section. The hot air channel tube section is either sleeved outside the hot water channel tube section or wrapped around the hot water channel tube section.

[0019] Optionally, the hot water channel tube section and the hot air channel tube section are directly fixed on the outer wall of the melt conveying section; a solenoid valve 1 is provided at the air inlet end of the hot air channel tube section; an exhaust branch is formed on the exhaust duct and a solenoid valve 2 is provided on the exhaust branch.

[0020] The electromagnetic valve 1 arranged at the air inlet end of the hot air duct tube array part can control the opening and closing of the air inlet end. The electromagnetic valve 2 arranged on the exhaust branch can control the conduction state and the closed state of the exhaust branch.

[0021] Optionally, the exhaust branch is connected between the second duct fan and the check valve.

[0022] The beneficial effect of the utility model is that the utility model can realize the recovery and utilization of the heat released in the screw unit and the molding unit while ensuring the normal operation of the extruder, so that the heat can be effectively recycled in the production operation process of the twin-screw extruder, which has the advantages of energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of the first embodiment of the present utility model.

[0024] Figure 2 This is a structural schematic diagram of the second embodiment of the utility model.

[0025] In the figure: 1 hopper; 2 screw unit, 2.1 water outlet pipe 1, 2.2 water outlet pipe 2, 2.21 first branch, 2.22 second branch, 2.23 connecting pipe; 3 melt conveying section; 4 molding section; 10 evaporator, 11 water inlet pipe, 12 drain pipe, 13 compressor, 14 expansion valve; 20 pressure tank, 21 air inlet duct, 211 duct fan 1, 202 one-way valve, 22 exhaust duct; 30 heat exchange duct, 31 air inlet duct, 32 exhaust duct, 321 duct fan 2, 322 check valve; 40 adapter, 41 channel section 1, 42 channel section 2; 50 hot water channel tube section; 60 hot air duct tube section, 61 return air duct. DETAILED DESCRIPTION

[0026] The structures, proportions, sizes, etc. illustrated in the drawings of the specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the utility model, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effect and purpose that can be achieved by the utility model, should still fall within the scope of the technical content disclosed by the utility model. At the same time, the terms such as "upper", "lower", "front", "back", "middle" and so on quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the utility model. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the utility model without substantial change of the technical content.

[0027] like Figure 1 , Figure 2 A twin-screw extruder with full-stage heat recovery function is shown, comprising a hopper 1, a screw unit 2, a melt conveying section 3, a molding section 4, an evaporator 10, a pressure tank 20, a heat exchange air duct 30, a switching part 40, a hot water duct tube section 50 and a hot air duct tube section 60.

[0028] The screw unit 2 includes a water circulation cooling mechanism and the water circulation cooling mechanism includes a water inlet pipe and a water outlet pipe (i.e., water outlet pipe 1 2.1 and water outlet pipe 2 2.2 shown in the figure). The water inlet pipe is used to supply cold water into the water circulation cooling mechanism, and the water outlet pipe is used to discharge hot water flowing out of the water circulation cooling mechanism.

[0029] The water inlet pipe 11 of the evaporator 10 is connected to the water outlet pipe of the screw unit 2. The drain pipe 12 of the evaporator 10 is connected to the water inlet pipe of the screw unit 2 (not connected together in the figure), so that a water circulation system can be established between the water tank of the evaporator 10 and the water circulation cooling mechanism of the screw unit 2 to achieve the purpose of recycling the heat carried by the hot water.

[0030] The pressure tank 20 is provided with an air inlet duct 21 and an air exhaust duct 22 connected to the tank cavity thereof, and a duct exhaust fan 211 is provided on the air inlet duct 21. The duct exhaust fan 211 can be used to send external air into the tank cavity of the pressure tank 20. The exhaust duct 22 matches the hopper 1, and can send the heated air in the pressure tank 20 into the lower part of the hopper 1 and be used to dry the material. Specifically, an annular cavity is formed on the wall of the hopper 1, and the exhaust duct 22 is connected to the annular cavity. A plurality of hollow tubes are arranged in the bucket bin of the hopper 1, and a large number of through holes are distributed on the tube wall of the hollow tube. The hollow tube is connected to the annular cavity provided on the hopper 1, and can introduce the hot air sent to the annular cavity through the exhaust duct 22 into the bucket bin of the hopper 1, and is used to dry the material contained in the bucket bin.

[0031] The heat exchange medium coil body (not shown) of the evaporator 10 is arranged in the tank cavity of the pressure tank 20, and a compressor 13 is arranged on the inlet pipeline of the heat exchange medium coil body, and an expansion valve 14 is arranged on the discharge pipeline of the heat exchange medium coil body, so that the heat exchange between the hot water and the air in the pressure tank 20 can be achieved, and the purpose of heating the air in the pressure tank 20 is achieved. That is, the evaporator 10 can transfer the heat energy carried by the hot water output by the screw unit 2 to the air in the pressure tank 20, so that a large amount of hot air is accumulated in the tank cavity of the pressure tank 20.

[0032] The heat exchange air duct 30 is sleeved on the outside of the forming section 4. The heat exchange air duct 30 is provided with an air inlet pipeline 31 and an air outlet pipeline 32 connected with its annular cavity. The air inlet pipeline 31 is provided with a fan (which can be a duct fan or a conventional fan), which can send cold air from the outside into the annular cavity of the heat exchange air duct 30.

[0033] A duct fan 2 321 and a check valve 322 are provided on the exhaust pipe 32 on the heat exchange air duct 30 .

[0034] The adapter portion 40 includes a channel portion 1 41 and a channel portion 2 42 , and the channel portion 1 41 and the channel portion 2 42 are two independent channels.

[0035] The hot water channel tube section 50 and the hot air channel tube section 60 are both fixedly arranged on the outer wall of the melt conveying section 3. The water inlet end of the hot water channel tube section 50 is connected to the water outlet pipe of the screw unit 2, and the water outlet end is connected to the channel section 1 41 and finally connected to the water inlet pipe 11 of the evaporator 10 through the connecting pipe 2.23. The exhaust pipe 32 on the heat exchange air channel 30 is connected to the air inlet end of the hot air channel tube section 60 through the channel section 2 42.

[0036] A configuration situation where both the hot water duct tube section 50 and the hot air duct tube section 60 can be in direct contact with the outer wall of the melt conveying section 3. At this time, by arranging a temperature sensor near the outlet end of the exhaust air pipeline 32, whether to send hot air into the hot air duct tube section 60 is controlled according to the temperature. If the hot air temperature near the outlet of the exhaust air pipeline 32 is lower than the temperature required by the melt conveying section 3, then (by controlling the solenoid valve arranged on the pipeline) the supply of hot air into the hot air duct tube section 60 is stopped. At this time, a branch needs to be arranged on the exhaust air pipeline 32 for discharging the hot air of the exhaust air pipeline 32; alternatively, a pressure relief valve can also be arranged on the channel section two 42, and when the accumulated internal pressure of the hot air sent into the channel section two 42 by the exhaust air pipeline 32 exceeds the pressure value of the pressure relief valve, the accumulated hot air is discharged through the pressure relief valve.

[0037] There can also be a configuration situation where the hot water duct tube section 50 is in direct contact with the outer wall of the melt conveying section 3, and at the same time, the hot air duct tube section 60 is sleeved outside the hot water duct tube section 50. At this time, the hot air duct tube section 60 plays a role in blocking the direct contact between the hot water duct tube section 50 and the outside world and has a heat insulation and heat preservation effect.

[0038] The exhaust end of the hot air duct tube section 60 can directly discharge hot air (relatively low in temperature) to the outside. It can also be recycled through the following settings (because it is dry hot air, so it is suitable as the air source for drying materials), that is, the exhaust end of the hot air duct tube section 60 is connected to the air inlet pipeline 21 of the pressure tank 20 through a return air pipeline 61. At this time, a check valve 212 or a non-return valve can be arranged on the air inlet pipeline 21 to make the air in the pipeline flow only into the tank cavity of the pressure tank 20.

[0039] Such as Figure 1 、 Figure 2 For the screw unit 2 in , a water outlet pipe is led out from each of the water circulation cooling mechanisms of the two screws, that is, the first water outlet pipe 2.2 and the second water outlet pipe 2.2. The first water outlet pipe 2.1 is directly connected to the water inlet pipe 11 of the evaporator 10. The second water outlet pipe 2.2 is divided into two branches, that is, the first branch 2.21 and the second branch 2.22. The first branch 2.21 is connected to the water inlet end of the hot water duct tube section 50, and after the hot water flowing out through this pipeline heats and keeps the melt conveying section 3 warm, it is connected to the water inlet pipe 11 through the channel section one 41 and the connecting pipe 2.23. The second branch 2.22 is directly connected to the water inlet pipe 11 of the evaporator 10. Flow control valves can be arranged on the first branch 2.21 and the second branch 2.22 respectively to adjust and distribute the amount of hot water flowing to these two branches. During specific implementation, the ends of the first water outlet pipe 2.2 and the second water outlet pipe 2.2 can be connected to a pipeline or a pipe cavity or a cavity and then connected to the water inlet pipe 11.

[0040] The above embodiments are only illustrative of the principles and effects of the present utility model, and are not intended to limit the present utility model. There are many aspects of the present utility model that can be improved without departing from the overall idea. Persons familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present utility model. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field to which the present utility model pertains without departing from the spirit and technical idea disclosed by the present utility model should still be covered by the claims of the present utility model.

Claims

1. A twin-screw extruder with a full-stage heat recovery function, comprising a hopper, a screw unit, a melt conveying section and a forming section; the screw unit includes a water circulation cooling mechanism, and the water circulation cooling mechanism includes a water inlet pipe and a water outlet pipe; it is characterized in that: It also includes an evaporator, a pressure tank, a heat exchange air duct, a transfer part, a hot water duct tube part, and a hot air duct tube part; The water inlet pipe of the evaporator is connected to the water outlet pipe of the screw unit, and the drain pipe is connected to the water inlet pipe of the screw unit; The pressure tank is provided with an air inlet pipe and an air outlet pipe that communicate with its tank cavity; a pipe exhaust fan I is provided on the air inlet pipe for sending external air into the pressure tank; the air outlet pipe is matched with the hopper and can send the hot air in the pressure tank into the lower part of the hopper bin; the heat exchange medium coil body of the evaporator is arranged in the pressure tank, and a compressor is provided on the inlet pipeline of the heat exchange medium coil body, and an expansion valve is provided on the outlet pipeline; The heat exchange air duct is arranged outside the forming section; an air inlet pipeline and an air outlet pipeline that communicate with its annular cavity are provided on the heat exchange air duct, and a fan is provided on the air inlet pipeline so that the fan can send external air into the annular cavity of the heat exchange air duct; a pipe fan II and a check valve are provided on the air outlet pipeline; The transfer part includes a channel part I and a channel part II; the hot water duct tube part and the hot air duct tube part are both fixedly arranged outside the melt conveying section; the water inlet end of the hot water duct tube part is communicated with the water outlet pipe of the screw unit, and after the water outlet end is communicated with the channel part I, it is then connected to the water inlet pipe of the evaporator through a connecting pipe; the air outlet pipeline on the heat exchange air duct is connected to the air inlet end of the hot air duct tube part through the channel part II.

2. The twin-screw extruder with a full-stage heat recovery function according to claim 1, characterized in that: The air outlet end of the hot air duct tube part is connected to the air inlet pipe of the pressure tank through a return air pipeline.

3. A twin-screw extruder with a full-stage heat recovery function according to claim 1 or 2, characterized in that: The hot water duct tube part is fixedly arranged on the outer wall of the melt conveying section; the hot air duct tube part is either sleeved outside the hot water duct tube part or wound outside the hot water duct tube part.

4. A twin-screw extruder with a full-stage heat recovery function according to claim 1 or 2, characterized in that: The hot water duct tube part and the hot air duct tube part are both directly fixedly arranged on the outer wall of the melt conveying section; a solenoid valve I is provided at the air inlet end of the hot air duct tube part; an air exhaust branch is formed on the air outlet pipeline and a solenoid valve II is provided on this air exhaust branch.

5. The twin-screw extruder with a full-stage heat recovery function according to claim 4, characterized in that: The air exhaust branch is connected and arranged between the pipe fan II and the check valve.

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