KR101299054B1 - The continuous reaction equipments for PTFE pyrolysis using High-Frequency Heater - Google Patents

Abstract

The present invention relates to a continuous polytetrafluoroethylene pyrolysis reactor using a high frequency furnace, and more particularly, to tetrafluoroethylene (TFE) by pyrolysis of polytetrafluoroethylene (PTFE) using a high frequency furnace. It relates to a device for continuously mass production.
To this end, the present invention, at least two PTFE main reservoirs capable of alternating operation; A PTFE secondary reservoir connected to the PTFE primary reservoir and an automatic valve, and temporarily storing the powder or particulate PTFE supplied from the PTFE primary reservoir before entering the process; A vertical screw feeder for quantifying the PTFE supplied from the PTFE auxiliary reservoir into the process; A heat exchanger for blocking and cooling heat of the high frequency heating furnace delivered to the vertical screw feeder; It provides a continuous polytetrafluoroethylene pyrolysis reactor using a high-frequency heating furnace comprising a; high-frequency heating furnace for causing a pyrolysis reaction of PTFE through high-frequency induction heating.

Description

Continuous polytetrafluoroethylene pyrolysis reactor using high frequency furnace {The continuous reaction equipments for PTFE pyrolysis using High-Frequency Heater}

The present invention relates to a continuous polytetrafluoroethylene pyrolysis reactor using a high frequency furnace, and more particularly, to tetrafluoroethylene (TFE) by pyrolysis of polytetrafluoroethylene (PTFE) using a high frequency furnace. It relates to a device for continuously mass production.

In general, there are two methods for preparing tetrafluorethylene (TFE): pyrolysis of CFC-22 and pyrolysis of polytetrafluoroethylene (PTFE).

Since the pyrolysis method of CFC-22 includes a large amount of impurities including hydrochloric acid generated after pyrolysis, a hydrochloric acid absorption tower, a Ca (OH) 2 neutralization tower, a process using a purified sulfuric acid tower to remove trace impurities, and A large scale multi-stage purification process is required, such as distillation to separate TFE from HFP (hexafluoropropylene), OFCB (octafluorocyclobutane) and by-products generated during the pyrolysis reaction. Due to the problem of compression distillation, it is known that it is suitable for a mass production process of at least 3000 annually due to the high capital investment and operating cost.

On the other hand, PTFE pyrolysis, which produces TFE by the pyrolysis of PTFE under vacuum, is much simpler than the CFC-22 pyrolysis method, and consists of PTFE injection process, pyrolysis process, and condensation process of the produced TFE. In view of the stability of the non-transferable TFE, the desired TFE can be obtained through small scale production. However, in most cases, a very small amount of PTFE can be obtained by a batch reaction in a laboratory or injected even when continuously operated. Due to the clogging of the conveying device due to the coagulation of PTFE in powder and particle form in the conveying device, it is difficult to mass produce the TFE for a long time.

In addition, there has been conventionally proposed a pyrolysis method of PTFE using an electric heating furnace, but the electric heating furnace takes a long time to raise and lower the temperature of the heater for supplying heat, requires a lot of energy and has a disadvantage in durability. .

Looking at the process of producing TFE by the pyrolysis of PTFE under vacuum, ① the step of maintaining the entire system in a vacuum of 10 ^-2 torr or less, ② the step of injecting the powder, particulate or scrap PTFE into the reactor, ③ TFE is produced by pyrolysis of PTFE at a pressure of 5torr or less and a high temperature of 500 ° C or higher, ④ condensation and solidification of the produced TFE at a temperature of -142 ° C or lower, and ⑤ heating the obtained TFE to a gas phase. It converts and passes through the absorption tower in which the polymerization inhibitor is added to store as a gas.

The PTFE pyrolysis process is divided into a continuous process (① → ② → ③ → ④ → ⑤) or a batch process (② → ① → ③ → ④ → ⑤) according to the order of step ① and ②.

In order to achieve a continuous process, which is a commercially available process, it is necessary to quantitatively / continuously inject powder or particulate PTFE in a vacuum state.

Due to the low glass transition temperature, PTFE has a phase change caused by mechanical heat generated during transfer of PTFE for pyrolysis of PTFE or heat conducted during high temperature pyrolysis. There is this.

In addition, in the case of PTFE in the form of powder or granules, pores are formed in the particles during the manufacturing process, so that the natural agglomeration is difficult due to agglomeration even at extremely low pressure.

The present invention has been invented to solve the above problems, it is possible to continuously mass-produce TFE by pyrolyzing PTFE without interruption of transport by continuously or quantitatively injecting powder or particulate PTFE into the high frequency furnace under high vacuum. The purpose of the present invention is to provide a continuous polytetrafluoroethylene pyrolysis reactor using a high frequency furnace.

In order to achieve the above object, the present invention, at least two PTFE main reservoir capable of alternating operation; A PTFE secondary reservoir connected to the PTFE primary reservoir and an automatic valve, and temporarily storing the powder or particulate PTFE supplied from the PTFE primary reservoir before entering the process; A vertical screw feeder for quantifying the PTFE supplied from the PTFE auxiliary reservoir into the process; A heat exchanger for blocking and cooling heat of the high frequency heating furnace delivered to the vertical screw feeder; It provides a continuous polytetrafluoroethylene pyrolysis reactor using a high-frequency heating furnace comprising a; high-frequency heating furnace for causing a pyrolysis reaction of PTFE through high-frequency induction heating.

Preferably, the high frequency heating furnace is characterized by using a frequency of 10KHZ ~ 100KHZ band.

Also preferably, the automatic valves interlock with the optical sensor to automatically regulate the flow of PTFE.

More preferably, the heat exchanger is installed to have an angle of 70 ° or more with the horizontal direction of the upper surface of the vertical high frequency heating furnace.

Also preferably, a jacket for cooling is installed in the PTFE auxiliary reservoir and the vertical screw feeder.

More preferably, the circulating refrigerant of the jacket is characterized by using a refrigerant maintained at -5 ± 5 ℃.

According to the pyrolysis reaction apparatus of the present invention, powder or particulate PTFE can be continuously or quantitatively injected into a high frequency heating furnace, and continuous mass production of TFE is possible through pyrolysis of PTFE using such a high frequency heating furnace.

That is, to overcome the disadvantages of the conventional method of producing TFE by pyrolyzing PTFE and stopping the degradation of the pyrolysis reaction and frequent dismantling and maintenance of the productivity due to the poor feed (fusion, fixation, etc.) of PTFE. do.

In addition, according to the present invention, the temperature and cooling time is shorter, energy consumption is reduced, and convenience and durability are higher than those of the conventional electric heating furnace. Equipment investment and operating costs can also be reduced.

1 is a schematic configuration diagram showing a continuous polytetrafluoroethylene pyrolysis reaction apparatus using a high frequency heating furnace according to the present invention
2 is a view showing a conventional high frequency heating furnace applicable to one embodiment of the present invention

The present invention relates to a pyrolysis reactor for the continuous mass production of tetrafluoroethylene (TFE) from polytetrafluoroethylene (PTFE), which is handled to produce TFE by continuous PTFE injection and pyrolysis under high vacuum. And by providing a means to effectively produce and transport TFE, which is very dangerous and difficult to transport, the PTFE pyrolysis reaction makes it possible to mass-produce highly industrially available TFE at a lower cost and convenience at a desired place of use.

In particular, the present invention uses a high-frequency furnace to continuously mass-produce TFE through PTFE pyrolysis, and enables high-volume production of TFE by operating the high-frequency furnace under vacuum.

The high frequency heating furnace to be used in the present invention is a heating device that generates a pyrolysis reaction through high frequency induction heating, and can rapidly heat a specific part according to the characteristics of the inductive heating to reduce processing time and cost, heating depth and temperature Precise control is possible, and instant ON / OFF control is possible.

The temperature of the high frequency heating furnace for pyrolysis of PTFE under high vacuum can be supplied through the high frequency heating heater.

In the heating method of the electric heating furnace according to the prior art, the operation interruption occurs due to constraints such as frequent disconnection during rapid heating, whereas the high frequency heating furnace used in the present invention enables stable heating and rapid heat loss even during rapid heating. Less is preferable.

In addition, the thermal efficiency of thermal decomposition using a similar kind of waste plastic is very inefficient, about 20%, but the thermal decomposition using high frequency has the advantage of converting approximately 70% of energy into heat, and decomposes by uniform heating effect. The efficiency can be increased.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the pyrolysis reaction apparatus according to an embodiment of the present invention is a PTFE main storage tank for quantitatively and continuously adding powder or particulate PTFE to a high-temperature vertical high frequency heating furnace 16 under vacuum. (10 or main reservoir), PTFE secondary reservoir (11, or secondary reservoir), the vertical screw feeder 13 and the heat exchanger (15).

The primary reservoir 10 is a reservoir capable of storing powder or particulate PTFE, the lower portion of which has a circular cone shape for the natural transfer of PTFE. At this time, the lower outer peripheral surface of the main reservoir 10 is preferably to have an angle of 60 ° or more horizontal, more preferably to have an angle of 70 ± 5 °.

In addition, the main reservoir (10) is provided with at least two tanks so that when the PTFE of one main reservoir is exhausted in accordance with the transfer and input of the PTFE so as to alternately use and operate the other main reservoir.

The secondary reservoir 11 is a reservoir for temporarily storing the PTFE, which is automatically transferred and supplied from the primary reservoir 10, before being introduced into a pyrolysis process (or inside a high frequency furnace), and is equipped with a jacket for cooling. Has a circular cone shape for the natural conveyance of PTFE, and has a confirmation window to confirm the smooth flow of the injected PTFE.

In addition, the auxiliary storage tank 11 is preferably 50 cm or less in total height, and more preferably 30 ± 5 cm in order to prevent the pressing by the self-weight of the introduced PTFE and smoothly transported.

In addition, the lower outer circumferential surface of the auxiliary reservoir 11 preferably has an angle of 60 ° or more horizontally, more preferably 70 ± 5 °.

The main reservoir 10 and the auxiliary reservoir 11 are connected through an automatic valve 12 (for example, an automatic ball valve), and the automatic valve 12 is the main reservoir 10 and the auxiliary reservoir 11. It is installed in the pipe between) serves to automatically control the flow of powder or particulate PTFE in conjunction with the optical sensor (17).

For example, the optical sensor 17 transmits the amount of PTFE of the auxiliary reservoir 11 to the controller, and the controller adjusts the opening and closing amount of the automatic valve 12 according to the signal of the optical sensor 17.

The vertical screw feeder 13 is a motor-driven metering means equipped with a magnetic drive for metering PTFE, and an introduction tube 14 for conveying PTFE powder is provided at one side.

That is, the screw feeder 13 injects the PTFE powder supplied from the auxiliary storage tank 11 through the introduction pipe 14 into the pyrolysis process (or a high frequency heating furnace) by a driving means such as a motor and a magnetic drive. In this case, it is preferable that the motor of the screw feeder 13 use a step motor or the like capable of adjusting the rotation speed.

The screw feeder 13 may be operated in a state capable of adjusting the rotation speed through a motor and a magnetic drive.

It is preferable that the driving direction of the screw feeder 13 and the introduction pipe 14 (or the vertical length direction of the screw feeder and the vertical length direction of the introduction pipe) maintain an angle of 60 ° or more with the horizontal direction, and more preferably. It is recommended to have an angle of 75 ± 5 °.

The entire system of the vertical screw feeder 13 is provided with a jacket for cooling.

The heat exchanger 15 is a kind of cooling means for blocking and cooling the heat transmitted by conduction, convection or radiation in the vertical high frequency heating furnace 16 in which the high temperature is maintained. The screw feeder 13 and the high frequency heating furnace It is installed between the (16) to block the heat of the high-frequency high-frequency heating furnace 16 is transmitted to the screw feeder (13).

The heat exchanger 15 prevents the occurrence of the PTFE scale in the transfer pipe installed between the high frequency furnace 16 and the screw feeder 13 and the blockage of the transfer tube, and the horizontal direction of the upper side of the high frequency furnace 16 and 70 °. The installation is configured to have the above angles.

That is, the heat exchanger 15 serves to prevent the PTFE scale from being formed in the transfer pipe or the transfer pipe is blocked by the heating of the PTFE injected into the vertical high frequency heating furnace 16.

The high frequency furnace 16 is a reactor for producing TFE by pyrolysing PTFE supplied from the vertical screw feeder 13 at high temperature.

Usually the frequency range of use of a high frequency furnace is determined by the type, size, weight, appearance, heating time, heating temperature, ascent rate and depth of penetration of the heating material.

In the present invention, the high-frequency heating furnace 16 induces heating of the reactor using a frequency of 10KHZ ~ 100KHZ band for uniform and efficient pyrolysis, and preferably has a frequency range of 15KHZ ~ 30KHZ.

The high frequency furnace 16 has a good penetration depth when operated and operated in a frequency range of less than 10 KHZ, but has a slow heating rate, and is slightly advantageous to local heating when operated and operated in a frequency range of more than 100 KHZ. It is not suitable because the depth is too small to obtain a uniform pyrolysis effect.

The high frequency heating furnace 16 of the pyrolysis reaction apparatus according to the present invention can be configured as shown in FIG.
That is, the high frequency heating furnace 16 is a coil 20 installed in a structure surrounding the reactor 18 while being supported by the reactor 18 disposed in the center, the coil fixing jig 19 and It is composed of a cover 21 which wraps around the outer circumference of the coil 20.
In addition, the insulating member 22 is formed between the reactor 18 and the coil 20.

In addition, all devices equipped with a cooling jacket in the pyrolysis reaction apparatus according to the present invention are cooled with cooling water of 19 ° C. or less, which is a glass transition temperature of PTFE, for cooling the PTFE, and preferably using a refrigerant of −5 ± 5 ° C. Cooling by preventing the coagulation and seizure of PTFE which can occur inside the device by the temperature rise above the glass transition temperature of PTFE by the external mechanical force during the transfer of PTFE and induces the smooth flow of PTFE.

That is, the circulating refrigerant of the jacket uses a refrigerant maintained at -5 ± 5 ℃.

The pyrolysis reaction apparatus of the present invention continuously and quantitatively supplies powder or particulate PTFE to a high-frequency high-frequency furnace 16 without interruption of transport under high vacuum, thereby enabling mass production of TFE.

Hereinafter, the pyrolysis process of PTFE using the pyrolysis reaction apparatus of the present invention will be described.

The PTFE secondary reservoir (10) is closed and the PTFE primary reservoir (10) is filled with powder or particulate PTFE.

PTFE main reservoir (10), PTFE auxiliary reservoir (11), vertical screw feeder (13), heat exchanger (15), vertical high frequency furnace (16) and TFE using a vacuum pump to remove oxygen in the reaction system. Reduce the pressure in the condenser to 10 ^-3 torr.

The refrigerant is supplied and circulated to cool the PTFE auxiliary reservoir 11, the vertical screw feeder 13, and the heat exchanger 15 to raise the high frequency heating furnace 16 to a desired pyrolysis temperature.

After checking the vacuum level of the entire system for the pyrolysis of PTFE, the vacuum pump is stopped and the entire system is sealed.

Open the ball valve 12 to transfer the PTFE particles in the PTFE primary reservoir 10 to the PTFE secondary reservoir 11 by gravity, and adjust the motor speed of the vertical screw feeder 13 to control the PTFE particles of the desired dose. To the vertical high frequency heating furnace 16 to proceed with pyrolysis.

At this time, the internal pressure of the vertical high-frequency heating furnace 16 is operated to be 5torr or less. As the PTFE particles are pyrolyzed in the vertical high frequency heating furnace 16, the obtained TFE is transferred to a TFE condensing tank maintained at -142 ° C or lower to condense and solidify.

When PTFE particles in one main reservoir are exhausted by the input of PTFE, PTFE particles are continuously supplied by alternately using the other main reservoir.

Hereinafter, various embodiments of manufacturing a TFE using the reaction apparatus of the present invention configured as described above will be described.

Example 1

The PTFE main reservoir was filled with 75 kg of PTFE (M-292, Daikin, Japan), and the entire system was evacuated to 10 ^-3 torr and sealed.

At this time, the circulating refrigerant at -5 ° C is operated to cool the PTFE auxiliary reservoir, the vertical screw feeder, and the cooler (or heat exchanger), and the liquid TFE is cooled to -142 ° C or lower by using nitrogen to simultaneously discharge the gas. Operating in the frequency range 20KHZ, the temperature of the high-frequency furnace was raised to 650 ° C, the ball valve was opened to feed PTFE from the PTFE main reservoir into the PTFE auxiliary reservoir, and the vertical screw feeder was operated to operate the PTFE at a speed of 15 kg / hr. Was put into a high frequency furnace.

At this time, the high-frequency heating furnace can be heated up to 650 ℃ within 5 minutes, but the temperature was raised over 20 minutes for stability. At this time, the pressure of the reactor was 3torr or less.

Pyrolyzed PTFE was continuously stored in a TFE condensing bath cooled with liquid nitrogen.

According to the PTFE exhaust and the TFE storage of the two PTFE main reservoirs, the filling / exhaust operation of PTFE and the evaporation / recooling of TFE were repeated for 100 hours, and clogging in the PTFE feeder did not occur during operation. Did.

The gas obtained was analyzed using GC and GC / MS, and found to be 97.5% TFE and 2.5% HFP, producing trace amounts of carbon and OFCB.

[ Example  2 to 5]

In the same manner as in Example 1, PTFE was introduced into a vertical high frequency furnace at a speed of 15 kg / h, and pyrolysis was carried out by varying the temperature of the vertical high frequency furnace having a frequency range of 25 KHZ to 600 to 900 ° C. as shown in Table 1. The reaction was carried out.

The results of analyzing the composition of the gas obtained are shown in Table 1.

Comparative Example 1

In the same manner as in Example 1, the pyrolysis reaction was carried out by putting crushed PTFE scrap into a vertical high frequency furnace, and the pyrolysis reaction was performed at 700 ° C. by operating the high frequency furnace in the region of 120 KHZ.

As a result of analyzing the composition of the obtained gas, TFE 65%, HFP 25%, OFCB 5%, and Carbon 5% were produced. After disassembling and disintegrating the reactor after the reaction, it was confirmed that PTFE was not completely decomposed and remained inside the reactor. there was.

[ Comparative example  2]

In the same manner as in Example 1, crushed PTFE scrap (average diameter 3mm) was put into a vertical high frequency furnace at a rate of 15 kg / h, and pyrolysis reaction was carried out. Pyrolysis reaction was performed.

It took about 6 hours to raise the internal temperature of the high-frequency furnace to 700 ° C. The composition of the gas was analyzed to produce TFE 92%, HFP 6.2%, OFCB 0.6%, and Carbon 1.2%.

[ Comparative example  3]

PTFE pyrolysis was carried out under the same conditions as in Example 1 using a pyrolysis reaction apparatus in which an electric heating furnace was installed instead of the high frequency heating furnace 16 in the apparatus of the present invention as shown in FIG. 1.

The time taken to raise the internal temperature of the electric furnace to 650 ° C. was about 8 hours. As a result of analysis of the gas, TFE 96%, HFP 3.7%, OFCB 0.1%, and Carbon 0.2% were produced.

As a result of looking through the above Examples and Comparative Examples, Examples 1 to 5 subjected to the pyrolysis reaction according to the present invention efficiently decomposed PTFE of the heating furnace to generate TFE, whereas the Comparative Example showed the frequency range of the present invention. When heating the inside of the high-frequency furnace in the outside range did not have a sufficient penetration depth it could be confirmed that the PTFE inside the furnace does not completely decompose or it takes a long time to heat the furnace inside, according to the prior art In the case of using the electric furnace it can be seen that it takes a long time to heat the inside of the furnace.

Accordingly, when using the frequency band outside the frequency band of the present invention or using an electric heating furnace according to the prior art it can be seen that the TFE productivity is lowered and the production cost is increased.

As described above, the reactor of the present invention can continuously and quantitatively inject PTFE particles under high temperature and high vacuum into a high frequency furnace, which is an optimal reactor for pyrolysis reaction of PTFE. Commercial mass production of high TFE is possible.

As a result, it is expected that mass production of high-purity TFE can be efficiently performed at a desired place.

10: PTFE main reservoir
11: PTFE auxiliary reservoir
12: automatic valve
13: screw feeder
14: introduction tube
15: heat exchanger
16: high frequency heating furnace
17: light sensor

Claims (6)

At least two PTFE main reservoirs capable of alternating operation;
A PTFE secondary reservoir connected to the PTFE primary reservoir and an automatic valve, and temporarily storing the powder or particulate PTFE supplied from the PTFE primary reservoir before entering the process;
An automatic valve installed in a pipe between the PTFE primary reservoir and the PTFE secondary reservoir to automatically control the flow of powder or particulate PTFE in conjunction with an optical sensor;
An optical sensor for transmitting the PTFE amount of the PTFE auxiliary reservoir to a controller so that the controller can control the opening and closing amount of the automatic valve according to the signal of the optical sensor;
A vertical screw feeder for quantitatively injecting the PTFE supplied from the PTFE auxiliary reservoir into the process through an introduction tube provided at one side;
A heat exchanger installed between the vertical screw feeder and the high frequency heating furnace to block and cool heat of the high frequency heating furnace transmitted to the vertical screw feeder;
A high frequency heating furnace comprising a coil supported by a coil fixing jig while covering a circumference of a reactor, and a cover which closes an outer circumference of the coil, causing a pyrolysis reaction of PTFE through high frequency induction heating;
Continuous polytetrafluoroethylene pyrolysis reaction apparatus using a high-frequency heating furnace comprising a.
The method according to claim 1,
The high frequency heating furnace continuous polytetrafluoroethylene pyrolysis reactor using a high frequency heating furnace, characterized in that using a frequency of 10KHZ ~ 100KHZ band.
delete The method according to claim 1,
The heat exchanger is a continuous polytetrafluoroethylene pyrolysis reactor using a high frequency heating furnace, characterized in that it is installed to have an angle of more than 70 ° with the horizontal direction of the top of the vertical high-frequency heating furnace.
The method according to claim 1,
The PTFE secondary reservoir and the vertical screw feeder is a continuous polytetrafluoroethylene pyrolysis reactor using a high frequency heating furnace, characterized in that the jacket for cooling is installed.
The method according to claim 5,
The circulating refrigerant of the jacket is a continuous polytetrafluoroethylene pyrolysis reactor using a high frequency heating furnace, characterized in that using a refrigerant maintained at -5 ± 5 ℃.

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