JPS6014691B2 - Polymer deposit cleaning equipment - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for cleaning and removing polymers attached to components of equipment that extrudes, solidifies, and molds polymers, such as paper thread equipment for synthetic fibers and plastic molding machines. Regarding cleaning equipment.

[Subject technology] Equipment for extruding, solidifying, and molding polymers, such as various threading machines for synthetic fibers, various molding machines for extrusion molding, blow molding, and injection molding for plastics, and extrusion molding machines for electric wires and cables, etc. Dismantled regularly or irregularly due to deterioration of moldability and moldability (nozzle clogging, increase in furnace pressure, formation of gelled substances, etc.), product or lot changes, etc.
The polymer adhering to the component parts is washed away.

As a subsidiary, a device for cleaning polymers adhering to the component parts of the above-mentioned equipment is a salt bath (in which polymer adhering substances (hereinafter also referred to as polymer adhering parts) are placed in a molten salt of inorganic salts, and the adhering polymer is removed by combustion. ) is widely used. However, the inorganic salts used in salt baths are
Generally, it is a strong oxidizing agent and is dangerous, and in addition to handling and storage risks, there is a risk of explosion due to the spouting of high-temperature molten salt or rapid combustion of the cleaning polymer, and it lacks safety and poses disaster prevention problems. Ta. As an alternative to the above-mentioned salt bath, a cleaning device for polymer-adhered parts using vacuum thermal decomposition has recently been proposed.
This method utilizes the fact that polymers are relatively easily decomposed and vaporized under high temperature and vacuum conditions in a cleaning device for polymer-adhered parts.

In other words, a heater is placed inside a sealable chamber, a heating chamber is equipped with a trap at the bottom for constructing the melted polymer, and a vacuum pump is installed to maintain a vacuum inside the heating chamber. This is a device in which polymer-adhered parts are placed in a heating chamber and the polymer is simply decomposed and vaporized under high-temperature vacuum for cleaning. However, it cannot be said that cleaning can be performed safely and effectively with such a device that simply utilizes vacuum thermal decomposition. This is because the decomposition of polymers already begins in the process of softening under vacuum and high temperatures. Until the polymer melts and carbonizes (hereinafter, the process of softening, melting, and carbonizing the polymer is referred to as the primary decomposition zone), a large amount of flammable gas is generated, and the gas atmosphere inside the heating chamber is normally in the explosive range. Since the heater is located inside or near the heater, there is a risk that the high-temperature heater could become an ignition source and cause an explosion, resulting in a lack of safety. In addition, it is generally said that flame will not propagate under high vacuum even if an explosive mixture is formed, but if the vacuum pump stops due to power outage, or there is an abnormality such as a failure of the vacuum seal, flame may spread into the heating chamber. Air may enter and there is a risk of ignition and explosion. On the other hand, since the cleaning performance is under vacuum, thermal decomposition and vaporization of the polymer occur in a short time.
Most of the adhered polymer is washed away, but after thermal decomposition and vaporization, the carbide adhered to the surface of the polymer-adhered parts is ashed (hereinafter, the process of ashing the carbonized polymer is referred to as the secondary decomposition zone). Furthermore, in parts with pores or complex shapes, such as the nozzle part of a spinneret used for synthetic fibers, complete removal of carbonized polymer may not be possible even after a long period of time. The cleaning performance is so poor that it is almost impossible to remove the carbonized polymer, and in practice, it is necessary to use a salt bath to remove the carbonized polymer.

[Problems to be Solved by the Invention] The present inventors have developed a method based on vacuum thermal decomposition that is safe and has excellent cleaning performance by improving the above-mentioned evaporation points. The present invention was arrived at as a result of various studies regarding cleaning devices for polymer deposits.

[Means for solving problems]

That is, the present invention includes a sealable chamber 1 having at least an opening/closing door, a heater 2 disposed inside the chamber, and a melt-through polymer bridge disposed to communicate with the lower part of the chamber. A heating chamber consisting of a conventional trap 8; a vacuum pump 9 disposed outside the heating chamber; a vacuum pump 9 passing through the heating chamber at a different position than the vacuum pump; Inert gas and air supply devices 19 and 22 disposed outside the heating chamber, and piping that connects the supply device and the heating chamber, with an inert gas supply V Switching valve 2 for switching from air supply to air supply
5 is provided with a gas intake pipe 30.

Furthermore, the heating chamber may have a structure in which a gas dispersion device 29 is connected to the stop end of the gas intake pipe to the heating chamber, or the gas intake pipe may be connected to the inside of the pipe. The structure in which the heating element 32 that heats the flowing gas is provided is effective in further increasing the cleaning effect of polymer deposits.

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples.

In Figures 1 and 2, 1 is a chamber, 2 is a heater provided on the inner wall of the chamber 1, and 3 is a polymer-attached part 4.
5 is an opening/closing door provided in the chamber, 6 is a trolley for loading and unloading the basket 3, 7 is a tray provided on the trolley 6, and 8 is a lower part of the chamber 1. 9 is a water ring type vacuum pump, 10 is a trub for collecting the melted polymer.
11 is a vacuum system pipe connecting the heating chamber and the vacuum pump 9; 11 is a backflow prevention valve provided in the vacuum system pipe; 12 is a vacuum system pipe connecting the heating chamber and the vacuum pump 9;
13 is a water circulation tank for sealing the vacuum pump 9, 13 is a gas-liquid separator, 14 and 15 are piping connecting the vacuum pump 9 and the gas-liquid separator, 13 or the circulation tank 12, respectively, 16 is an exhaust fan, and 17 is a Thermometer, 18 is a vacuum gauge, 19 is an inert gas supply device consisting of a flow rate control valve 20 and a flow meter 21, 22 is an air supply bag line consisting of a flow rate control valve 23 and a flow meter 24, and 25 is a switch operated by a timer. A valve 27 is an oxygen concentration meter, and 28 is a gas sampling vacuum pump for guiding gas to the oxygen concentration meter 27.

Reference numeral 29 denotes a gas dispersion device connected to the gas selection piping 30 for introducing inert gas or air into the heating chamber and installed near the opening/closing door 5 of the chamber. It has a structure in which a large number of holes 31 are bored in an annular pipe so that the water flows around the basket 3.

32 is a gas-gas heat exchanger installed in the vacuum system piping 10, and the high-temperature gas sucked and removed from the heating chamber is sealed in the heating chamber by heat exchange with the inert gas and air flowing in the gas intake piping. This is a preheating device that performs subheating of inert gas or air.

[Effect]

The adhered polymer of the polymer-adhered parts 4 housed in the basket 3 in the heating chamber under vacuum by the vacuum pump 9 is exposed to radiation from the heater 2 heated to a preset temperature depending on the type of the adhered polymer. Heat softens, melts, vaporizes, and carbonizes, but during this time, that is, during the primary decomposition zone, the atmosphere in the heating chamber is always under an inert gas atmosphere (here, inert gas atmosphere is defined as An inert gas such as nitrogen gas is sealed from the inert gas supply device 19 through the gas intake pipe 30 so that the oxygen concentration is 12% or less.

That is, at this time, the flap valve 25 functions so that inert gas flows from the inert gas supply device into the gas intake pipe. The amount of inert gas such as nitrogen gas to be sealed is determined by detecting the oxygen concentration in the heating chamber with an oxygen concentration meter 27, and adjusting the flow rate so that the atmosphere in the heating chamber is maintained at a predetermined oxygen concentration or less. Preferably, it is controlled by a valve 20.

Further, it is preferable that the inert gas to be sealed is preheated by the preheater 32 and further sealed so as to surround the basket 3 by the gas dispersion device 29. The inert gas and air sealed in the heating chamber in this manner flow through the heating chamber toward the vacuum system piping 10 with the mixture of decomposed gas generated by thermal decomposition of the adhered polymer.

Further, the molten polymer that melts down from the polymer-adhered part 4 during the softening and melting process of the adhering polymer temporarily accumulates in the tray 7, is collected in the trap 8 via the tray 7, and is solidified. In addition, the high-temperature gas suctioned and removed from the heating chamber is cooled by the sealing water of the vacuum pump 9, and the high-boiling components in the gas condense, the water-soluble components in the gas splatter in the water, and the gas High boiling point components and water-soluble components are in circulation tank 1
2 is collected. On the other hand, the cooled non-condensable gas and water-insoluble component gas are exhausted by an exhaust fan 26 via a gas-liquid separator 13. The backflow prevention valve 11 prevents a large amount of air from flowing back into the heating chamber when the vacuum pump 9 is stopped due to a power outage, etc., and prevents the atmosphere inside the heating chamber from exceeding a predetermined oxygen concentration. Furthermore, in the case of this embodiment in which a water ring type vacuum pump is used as the vacuum pump, it also has a function to prevent seal water from flowing back into the heating chamber, thereby preventing the danger of steam explosion. As described above, by using a device configured to actively seal inert gas such as nitrogen gas into the heating chamber until the attached polymer softens, melts, and carbonizes (primary decomposition zone), The primary decomposition zone can be operated under an inert gas atmosphere at all times, thereby eliminating the risk of explosion of flammable gas generated in large amounts in the primary decomposition zone.

Incidentally, most of the flammable gas discharged from the inside of the heating chamber to the outside is collected by the seal water of the vacuum pump, and the remaining part is diluted by air from the air intake provided in the exhaust fan 16. Therefore, there is no danger of explosion. moreover,
Since the primary decomposition is carried out in an inert gas atmosphere, that is, in a state where oxygen is very diluted, the carbonized polymer that remains stuck to the polymer-adhered parts at the end of the primary decomposition has not progressed to oxidation on the surface layer, so it cannot be used after that. The carbonized polymer can be more effectively ashed in the ashing process (secondary decomposition zone) of the carbonized polymer.

In addition, in the case of the salt bath used in the conventional method, the entire amount of adhering polymer is burned off, whereas in the vacuum thermal decomposition method, a considerable amount of the adhering polymer is melted down in the primary decomposition zone and collected. Melt it down in a pot for use,
Since it can be recovered as a solid polymer, the absolute amount of adhering polymer to be carbonized can be reduced, which has the advantage of reducing the absolute amount of harmful substances generated in the carbonization process in terms of environmental protection. Furthermore, since primary decomposition is performed under an inert gas atmosphere, oxidation of the molten polymer hardly progresses, so the molten polymer can easily melt into the trap, increasing the amount of recovered polymer in solid form. . This not only further increases the advantages of vacuum thermal decomposition in terms of environmental protection, but also reduces the amount of carbonized polymer that adheres to polymer-attached parts, which is also effective in terms of cleaning performance.
In addition, by preheating the inert gas sealed in the heating chamber with a heating device or further dispersing it with a gas dispersion device, the polymer-attached parts and the polymer attached thereto can be heated by the inert gas sealed in the heating chamber. Partial cooling and partial suppression of decomposition are prevented, and the cleaning effect can be further enhanced.

In addition, if an inert gas is sealed in the heating chamber via a gas distribution device, the inert gas will flow around the basket containing the polymer-attached parts, and will also mix with the decomposed gas generated by the decomposition of the attached polymer. Because it flows uniformly and in a ridge within the heating chamber, it prevents the flammable decomposed gas from stagnation in the heating chamber and promotes the prompt outflow of the generated decomposed gas, thereby reducing the adhesion of polymers. decomposition is further promoted.
That is, by preheating, dispersing, and diluting the above-mentioned filled gas, 1
Washing spots of polymer deposits in the next decomposition zone can be prevented, decomposition can be further promoted, and the cleaning effect can be further enhanced. Next, the switching valve 25 is activated by a timer set to a predetermined time for primary decomposition depending on the type and amount of attached polymer, and the gas sealed in the heating chamber is switched from inert gas to air.
At the same time, the cleaning process for the adhered polymer shifts from primary decomposition to secondary decomposition, and the carbonized polymer remaining stuck to the polymer-adhered parts begins to be ashed.

During the ashing process of the carbonized polymer, that is, the secondary decomposition zone, air is actively introduced into the heating chamber by the air supply device 22 so that the atmosphere in the heating chamber is always an air atmosphere. . At this time, the amount of air that can be taken in is determined by detecting the oxygen concentration in the force acclimatization chamber with the oxygen flow rate meter 27, and increasing the atmosphere in the heating chamber to a predetermined oxygen concentration or higher (usually 20 to 21% or higher). It is desirable that the flow rate be controlled by the flow control valve 23 so that the flow rate is maintained. Further, the air taken into the heating chamber is preheated by a preheating device 32,
Furthermore, it is preferable to enclose the basket 3 with a gas dispersion device 29, and the enclosed air mixes with oxidizing gas generated by oxidation of the carbonized polymer and flows inside the heating chamber toward the vacuum system piping 10. Also,
The high-temperature oxidizing gas suctioned and removed from the heating chamber is cooled by sealing water of the vacuum pump, passes through the gas-liquid separator 13, and is exhausted by the exhaust fan 16. As mentioned above, in the secondary decomposition zone, by using a fermentation device that actively introduces air into the heating chamber,
The subsequent decomposition can be carried out under an air atmosphere.

Therefore, since the carbonized polymer is simply cleaned under vacuum and high temperature, the oxygen is diluted, the oxidation of the carbonized polymer is extremely slow, and ashing takes a long time compared to the case of using conventional equipment. The oxidation of the carbonized polymer is accelerated and the carbonized polymer can be ashed in a relatively short time. In addition, by preheating the air taken into the heating chamber with a preheating device or further dispersing it with a gas dispersion device, the polymer-attached parts and the carbonized polymer attached thereto can be partially cooled by the air. This will further improve the cleaning effect.

Additionally, if air is introduced into the heating chamber via a gas distribution device, the air will flow around the basket containing the polymer-attached parts, ensuring uniform contact between the carbonized polymer and the oxygen in the intake air. , the cleaning effect can be further enhanced. Moreover, the introduced air mixes with the oxidizing gas generated by the oxidation of the carbonized polymer and flows uniformly and in stripes within the heating chamber, preventing gas stagnation within the heating chamber. At the same time, the generated oxidizing gas quickly flows out of the heating chamber, further promoting the oxidation of the carbonized polymer. That is, the above-mentioned child heat, dispersion, and sweep of the intake air make the oxidation of the carbonized polymer uniform, prevent washing spots, and further promote oxidation and ashing. In addition, in the secondary decomposition zone, "only a thin layer of carbonized polymer adheres to the surface of the polymer-adhered part, and the amount of adhered polymer is small, and oxidation of the carbonized polymer proceeds from the surface of the fixed carbonized polymer and is completely Since combustible gases (such as CO) are hardly generated, there is no risk of explosion in the secondary decomposition zone.In fact, by actively introducing air,
Since there is a sufficient amount of oxygen, even the production of flammable gases such as carbon monoxide gas is prevented. It should be noted that the present invention is not limited to the diamond shape of the embodiments described above.

For example, the switching valve that switches from the inert gas supply V supply to the air supply uses a timer method (the method in the above embodiment) that controls when to switch to secondary decomposition based on the elapsed time since the start of primary decomposition. ) is practical, but in addition to this method,
A method may be used in which the switching timing is managed by detecting the amount of combustible gas generated in the primary decomposition zone.
Further, the child heating device may have a structure in which piping for sealing and intake gas is meandered along the inner wall of the heating chamber for preheating. Further, the gas dispersion device may have a structure in which a gas solution is formed in the opening/closing door of the heating chamber and is dispersed in front of the gas crab via a perforated plate. [Effects of the Invention] As mentioned above, in the present invention, in the primary decomposition zone where there is a risk of explosion etc., inert gas such as nitrogen gas is actively filled and the decomposition is carried out in an inert gas atmosphere. In the secondary decomposition zone, the equipment is structured so that air can be actively taken in and the decomposition can be carried out in an atmosphere with sufficient oxygen content, which is safe, has excellent cleaning performance, and also reduces the generation of harmful substances. This makes it possible to wash and remove adhering polymers, which is also effective in terms of environmental protection.

Furthermore, if the device structure is such that the inert gas or air is preheated before being charged or taken in, and the gas is dispersed and flowed within the heating chamber, cleaning spots will be eliminated and the cleaning performance will be further increased. , cleaning can be performed more effectively. Therefore, with the apparatus of the present invention, it is possible to sufficiently clean synthetic fiber weaving nozzles or parts with complicated shapes, which is almost impossible to do with conventional apparatuses that simply perform vacuum thermal decomposition.

[Brief explanation of drawings]

1 and 2 are a longitudinal sectional view and a side view of an apparatus showing one embodiment of the present invention. 1: Chamber, 2: Heater, 3: Basket for storing polymer deposits, 8: Trap for collecting melted polymer, 9: Vacuum pump, 19: Inert gas supply device, 22
: air supply device, 25: switching valve, 29: gas dispersion device,
30: Gas intake piping, 32: Preheating device. Juice 1 Mosai 2lg

Claims (1)

[Claims] 1. At least a sealable chamber having an opening/closing door, a heater disposed inside the chamber, and a burn-through polymer collection disposed in communication with the lower part of the chamber. a vacuum pump communicating with the heating chamber and disposed external to the heating chamber; a vacuum pump communicating with the heating chamber at a different location from the vacuum pump and disposed external to the heating chamber; a supply device for inert gas and air, and a piping that communicates the supply device with the heating chamber, and a switching valve for switching from inert gas supply to air supply is disposed in the middle of the piping. A device for cleaning polymer deposits, characterized by having an intake pipe. 2. The polymer-coated polymer according to claim 1, wherein the heating chamber has a structure in which a gas distribution device is connected to an open end of the gas intake pipe to the heating chamber. Kimono cleaning equipment. 3. The apparatus for cleaning polymer deposits according to claim 1, characterized in that the gas intake pipe is provided with a preheating device for heating the gas flowing inside the pipe.