SU1763210A1 - Equipment for polytetrafluoroethylene processing - Google Patents

Description

one

(21) 4872722/05

(22) 09/10/90

(46) 09/23/92. Bul No. 35

(71) Institute of Chemistry, Far Eastern Branch of the USSR Academy of Sciences

(72) A.K. Tsvetnikov, A.A. Uminsky and V.A. Tsarev

(56) Recycling of polymeric materials. / Ed. Lyubeshkina E.G. - M .: Himi, 1985, p. 100-103.

Steinberg et al. Linear pyrolysis of fluoroplastic chips. Theoretical foundations of chemical technology. / Sat. Works under the editorship of Gifenova V.V., GIPH, L., 1980, pp.58-62. h

(54) INSTALLATION FOR PROCESSING POLYTETRAFTORETHYLENE

(57) Use: Disposal of waste polytetrafluoroethylene or other organofluorine polymers. SUMMARY OF THE INVENTION: The installation is equipped with a tubular preheating furnace, a screw feeder for continuous feeding

polytetrafluoroethylene into the reactor, two refrigerators, a centrifugal fan0 and vortex traps. Preheating furnace installed at the vertical inlet of the reactors. The feeder is located at the entrance to the reactor. One of the coolers is installed at the vertical inlet of the reactor below the preheating furnace in the zone where the product is introduced into the reactor. Another refrigerator is located on the lid of the reactor. The centrifugal fan is mounted on the lid aligned with the reactor. The vortex traps and the reactor are interconnected by inlet and outlet pipelines. The installation is also equipped with a melt level sensor and a thermocouple installed in the reactor and a gaseous product utilization unit. Commodity thermal decomposition, connected by pipeline to the reactor. In addition, the installation is equipped with a reactor connection pipe installed at the reactor. 3 z.p, f-ly. 2 Il.

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The invention relates to the processing of organofluorine polymers, specifically. polytetrafluoroethylene (PTFE) or fluoroplast-4, and can be used to dispose of the waste of this polymer in order to obtain finely dispersed PTFE and other products.

A known facility for lyrolitic decomposition of PTFE waste in a stream of dry nitrogen at temperatures up to 500 ° C. being a reactor made in the form of a quartz tube with connections for

and exhaust gases, equipped with a heater (1).

The disadvantage of the installation is the almost complete decomposition of PTFE to gaseous monomers and, accordingly, a very low yield of finely dispersed PTFE.

The closest in technical essence and the achieved result is the installation for processing polytetrafluoroethylene, containing a reactor with a vertical inlet and inlet and outlet

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pipelines for the supply and removal of gases and the furnace (2).

As a result of thermal decomposition of fluoroplastic at a temperature above this installation, up to 85% of tetrafluoroethylene (ToE) is obtained in about 10% hexafluoropropylene (HFP) and about 5% of powdered polytetrafluoroethylene (PTFE).

The drawbacks of the installation are the low yield of fine PTFE powder and the need to periodically reboot the reactor.

The aim of the invention is to increase the yield of fine polytetrafluoroethylene and to ensure the possibility of continuous operation of the plant.

The goal is achieved by installing a tubular preheating furnace installed on the vertical inlet of the reactor with a screw feeder for continuously supplying polytetrafluoroethylene to the reactor at the inlet of it, two refrigerators, one of which is installed on the vertical inlet of the reactor preheating furnaces in the zone of introduction of polytetrafluoroethylene into the reactor, and the other on the reactor lid, with a centrifugal fan installed on the Lid coaxially with the reactor, and a vortex There are traps for collecting fine powder, and the reactor and the vortex traps are interconnected by inlet and outlet pipelines.

 The installation is also equipped with a melt level sensor and a thermocouple installed in the reactor, connected to the reactor of the unit for the utilization of gas products of thermal destruction and connected to the reactor pipe for supplying the reaction gases,

FIG. 1 is a schematic diagram of the installation: FIG. 2 - the same, top view.

A polytetrafluoroethylene processing unit contains a reactor 1 with a vertical inlet, a lid 2 and inlet and outlet pipes 3, 4 and 5. b for supplying and discharging gases and a furnace 7. The installation is also equipped with a preheating tube furnace 8 installed at the vertical inlet of the reactor 1, a new feeder 9 for continuous supply of polytetrafluoroethylene and reactor 1. located at the entrance to it, two refrigerators 10 and 11. One of which is installed at the non-vertical entrance of the reactor 1 below the furnace 8. heating, and the other on the lid 2 of reactor 1, a centrifugal fan

12 mounted on the lid 2 coaxially with the reactor 1. and vortex traps 13 and 14 for collecting fine powder,

Reactor 1 and traps 13 and 14 are connected

between each input and output pipelines 3. 4 and 5, b.

The installation is also equipped with a melt level sensor 15 installed in the reactor 1 and a thermocouple 16 connected to

0 by the reactor 1 through the pipe 17 and the pipe 18 by the block 19 utilization of gaseous products of thermal destruction.

In order to provide the possibility of obtaining a modified finely dispersed

5 polytetrafluoroethylene installation equipped with installed on the reactor 1 pipe 20 for supplying the reaction gases.

To load pre-shredded polytetrafluoroethylene into reactor 1

0 use the bunker 21, from where the material on

inclined tube 22 under its own weight

poured into a screw chamber 23 and further

screw feeder 9 is fed to the reactor.

The installation works as follows. Before starting work, the installation through the pipe 17 is blown with dry nitrogen or tetrafluoroethylene obtained in the previous work cycles; in order to remove alagi in order to avoid the formation of explosive fluorine peroxides during thermo treatment. Then water is supplied to refrigerators 10 and 11, and the heating of furnaces 7 and 8 is turned on, controlling the temperature in reactor 1 using a thermocouple 16. After heating the furnaces 7 and 8 to 450 ° C

5 include feeding the crushed PTFE with a screw feeder 9 from the bunker 21. The crushed polytetrafluoroethylene (PTFE) from the screw chamber 23 enters the inlet of the reactor 1, first through the zone,

0 cooled by the cooler 10 and then through the zone heated by the preheating tube furnace 8, whereby the polymer melts.

The flow of material into the reactor 1 from the bottom

5, passing it first through the cooled zone, and then through the preheating zone, makes it possible to isolate the reaction zone from the atmosphere by forming a dynamic tube of solidified melt flowing from the melting zone. The tube furnace 8 of pre-heating the polymer to melt state allows thermal destruction with a lower temperature gradient. The heater 10, installed under the furnace 8, prevents the screw chamber 23 from heating and promotes the formation of a sealed plug of solidified polymer. After filling the reactor 1 with melt to the required level, controlled by sensor 15,

the supply is stopped and the heating of the furnace 7 is increased to the temperature of thermal decomposition (500 + 10 ° C), simultaneously turning on the centrifugal fan 12. As a result of the thermal destruction of polymer molecules, heavy molecules are carried by monomers into the gas phase, they are cooled in the refrigerator 11 area and condensed as a result of the flow of cold gas produced by the fan 12 rotating in the reactor 1 above the surface of the polymer melt, the thermal decomposition products through pipelines 5 and b are transferred to the vortex traps 13 and 14. where the fine gas accumulates and accumulates particulate polytetrafluoroethylene and ohlazhdennyegazoobraznyeprodukty thermodestruction again fed via conduits 3 and 4 into the reactor 1 and by the high molecular weight gases such as treraftoretilen, hexafluoropropylene. and low temperatures prevent further thermal destruction of the PTFE polymer molecules carried into the gas phase, thereby providing a significant increase in the yield of PTF fine powder. An excess of gaseous products of thermal decomposition through pipe 17 via pipe 18 is fed to recycling unit 19, where it is processed into various fluorine-containing products by known methods using equipment commonly used for these purposes.

This unit for the processing of polytetrafluoroethylene and, predominantly, its waste, makes it possible to obtain up to 50% of finely dispersed PTFE during thermal destruction, which is a valuable product due to its beneficial properties. Fine PTFE is an effective additive to oils, anti-friction composites, etc. In addition to this product, utilization of gaseous products of thermal destruction can be obtained with TPV and HPF for the purpose of their subsequent use in the synthesis of polymers and freons or for their further processing as hydrofluoric acid and sodium bifluoride NaFr HF.

The installation allowed to increase the yield of fine PTFE powder 10 times. create a continuous technology for recycling polytetrafluoroethylene waste, ensure the tightness of the installation and, as a result, safety and environmental cleanliness of the process

The installation has the following advantages: due to the fan returning the cooled gaseous products of thermal destruction to the reaction zone v of preheating the raw material up to 450 ° C, it was possible to increase the yield of the target product 10 times. By supplying crushed fluoroplastic-4 with a screw to the reactor from below, it was necessary to ensure the tightness of the installation during its continuous operation.

Claims (4)

Claim 1, A polytetrafluoroethylene processing facility comprising a reactor with a vertical inlet part, a lid and inlet and outlet pipelines  Supply and removal of gases and furnace, distinguish so that, in order to increase the output of fine polytetrafluoroethylene and the possibility of continuous operation of the installation, it is equipped with a tubular 1 preheating furnace installed on the vertical inlet of the reactor, with a screw feeder for 5 continuous supply of polytetrafluoroethylene to the reactor, located at the entrance to it, two refrigerators, one of which is installed on the vertical inlet of the reactor below the preheating furnace in the zone of introduction of polytetrafluoroethylene to the reactor, and the other on the reactor lid, a centrifugal fan installed on the lid coaxially with the reactor and vortex traps for collecting 5 fine powder, and the reactor and the vortex traps are interconnected by the input and output pipelines. 2. Installation under item 1, characterized by - 0 with the fact that it is equipped with in the reactor, the melt level sensor and thermocouple. t 3. The installation according to claim 1, characterized by the fact that it is equipped with a unit for utilization of gaseous products of thermal destruction, connected by a pipeline to a reactor, 4. Installation according to claim 1, characterized in that, in order to provide the possibility of obtaining modified fine polytetrafluoroethylene, it is equipped with a nozzle installed at the reactor for supplying the reaction gases.  i N l / 4 / i. " g / 10 19 / // / / QZ7V / -: / /