Apparatus for multistage thermal treatment of rubber waste, in particular scrap tires

Abstract

A process for multistage thermal treatment of rubber waste, in particular scrap tires, is proposed. The process comprises several steps of transferring a product granulate of rubber waste into three different sequencing heating zones of a reactor (10). In the heating zones (11a, 11b, 11c) the product granulate is heated at a first temperature between 100 to 200 C., preferably 150 to 180 C., then at a second temperature between 200 to 350 C. and at a third temperature between 300 to 600 C. The temperature is maintained until such time that no further oil is emitted within the respective heating zone. As a final step, the product granulate is removed from the reactor (10) and the desirable solid materials are separated.

Claims

1. An apparatus for multistage thermal treatment of rubber waste comprising: a reactor having: a first heating zone which can be heated to a first temperature in the range of 100 to 200 C., a second heating zone which can be heated to a second temperature in the range of 200 to 300 C., a third heating zone which can be heated to a third temperature in the range of 300 C. to 600 C., and a conveyor arranged for transporting product granulate within and through the reactor, wherein the reactor further comprises an upper portion in which a vapour exhaust is provided, and a cleaner provided within the vapour exhaust, wherein the vapour exhaust comprises a pipe having a length extending from the upper portion of the reactor to a condenser, wherein the pipe has an annular-shaped length, wherein the cleaner is movable within and along the annular-shaped length of the pipe, and wherein the cleaner comprises a chain having an annular-shaped length that extends within and along the annular-shaped length of the pipe, and a brush or brush elements arranged on the chain.

2. The apparatus according to claim 1, wherein the conveyor is a driven conveyor screw.

3. The apparatus according to claim 2, wherein the conveyor screw comprises worms with different pitches to provide different speeds within the reactor.

4. The apparatus according to claim 2, wherein the conveyor screw comprises a shaft, a worm on the shaft having an outer circumference, and supports at the outer circumference of the worm made of nonferrous metal to support an inner wall of the reactor.

5. The apparatus according to claim 4, wherein the reactor comprises a housing which is reinforced in an area of the non-ferrous supports of the conveyor screw.

6. The apparatus according to claim 5, wherein a region of the reinforcement is arranged to be reduced in temperature with respect to the first, second and third heating zones such that oils condensed in association with the reduced temperature provide for lubricating the conveyer screw proximate the supports at the outer circumference of the conveyer screw.

7. The apparatus according to claim 1, wherein the vapour exhaust further comprises sprayers within at least one of the pipe and the condenser for cleaning the cleaner.

8. The apparatus according to claim 1, wherein the housing of the reactor further comprises a longitudinal groove at the vapour exhaust, a side of the pipe is connected to each of the first, second, and third heating zones through the longitudinal groove, and the longitudinal groove provides for guiding the brush or brush elements along the length of the pipe.

9. The apparatus according to claim 8, wherein a perforated sheet along the longitudinal groove comprises a plurality of longitudinal slots within which the cleaner is geared for cleaning the pipe.

10. The apparatus according to claim 1, wherein the reactor further comprises an outlet at which an outlet conveyor screw is arranged.

11. The apparatus according to claim 1, wherein heating mats for heating the heating zones are arranged at the outside of a housing of the reactor.

12. The apparatus according to claim 1, wherein the first heating zone can be heated to the first temperature within the range of 150 to 180 C.

13. An apparatus for multistage thermal treatment of rubber waste comprising: a reactor having: a first heating zone which can be heated to a first temperature in the range of 100 to 200 C., a second heating zone which can be heated to a second temperature in the range of 200 to 300 C., a third heating zone which can be heated to a third temperature in the range of 300 C. to 600 C., and a conveyor arranged for transporting product granulate within and through the reactor, wherein the reactor further comprises an upper portion in which a vapour exhaust is provided, and a cleaner provided within the vapour exhaust, wherein the vapour exhaust comprises a pipe having a length extending from the upper portion of the reactor to a condenser, wherein the cleaner is movable within and along the length of the pipe, and wherein the conveyor screw comprises recesses in which rollers are installed to prevent deposition of the product granulate.

14. The apparatus according to claim 13, wherein the rollers are staggered in the circumferential direction of the conveyor screw.

15. An apparatus for multistage thermal treatment of rubber waste comprising: a reactor including an elongated housing having inner and outer sides and containing three different heating zones located along a longitudinal axis of the elongated housing, a conveyer for transporting product granulate along the longitudinal axis through the three different heating zones, a vapour exhaust comprising a pipe having a length that extends along the housing leading to a condenser and is connected to each of the three different heating zones for exhausting gases and oils recovered from the product granulate from each the three different heating zones, and a cleaner comprising brushes that are movable along the length of the pipe for cleaning the pipe, wherein the pipe has an annular-shaped length with opposite ends connected to the condenser, and the cleaner is movable within and along the annular-shaped length of the pipe and through the condenser, and wherein the brushes are arranged on a chain having an annular-shaped length that extends within and along the annular-shaped length of the pipe and through the condenser for moving the brushes along the annular-shaped length of the pipe.

16. The apparatus according to claim 15, wherein a longitudinal groove is formed in an upper area of the elongated housing, and a side of the pipe is connected to each of the three different heating zones through the longitudinal groove, and the longitudinal groove provides for guiding the brushes along the annular-shaped length of the pipe.

17. The apparatus according to claim 16, further comprising a perforated sheet located along an interface between the longitudinal groove and the side of the pipe for guiding the brushes, wherein the perforated sheet contains a plurality of longitudinal slots within which the brushes are geared for cleaning the pipe.

18. The apparatus according to claim 15, wherein the conveyer is a conveyer screw comprising a shaft, a worm on the shaft having an outer circumference, and supports at the outer circumference of the worm for supporting the conveyer screw at the inner side of the housing.

19. The apparatus according to claim 18, wherein the supports comprise non-ferrous metal supports.

20. The apparatus according to claim 18, wherein the reactor further comprises first and second reinforcing rings arranged around the housing, the first reinforcing ring being located along the longitudinal axis between a first and a second of the three heating zones, the second reinforcing ring being located along the longitudinal axis between the second and a third of the three heating zones, and wherein the supports at the outer circumference of the conveyer screw worm are located proximate the first and second reinforcing rings.

21. The apparatus according to claim 20, wherein the first and second reinforcing rings are located within temperature zones of the reactor that are arranged so as to be reduced in temperature with respect to temperatures in the three different heating zones such that oils condensed in association with the reduced temperature lubricate the conveyer screw proximate the supports at the outer circumference of the conveyer screw worm.

22. The apparatus according to claim 15, wherein the conveyer comprises a conveyer screw in the form of a worm having different pitches to provide different speeds for transporting the product granulate along the longitudinal axis within the reactor.

23. The apparatus according to claim 15, wherein the conveyer comprises a conveyer screw having recesses that extend in a radial direction and rollers that are rotatably mounted within the recesses.

24. The apparatus according to claim 15, further comprising separately controlled heating mats are arranged at an outer circumference of the housing proximate to each of the three different heating zones to allow different temperatures to be maintained within the three different heating zones such that: a first of the three heating zones can be heated to a first temperature in the range of 100 to 200 C., a second of the three heating zones can be heated to a second temperature in the range of 200 to 300 C., and a third of the three heating zones can be heated to a third temperature in the range of 300 C. to 600 C.

25. The apparatus according to claim 24, wherein the first heating zone can be heated to the first temperature within the range of 150 to 180 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic view of the reactor used in the multistage thermal treatment process according to the invention.

(2) FIG. 2 shows a vertical partial section through the reactor of the apparatus according to the invention.

(3) FIG. 3 shows a section along the lines 111-111 in FIG. 2.

(4) FIG. 4 shows a vertical partial section through the reactor of the apparatus according to the invention.

(5) FIG. 5 shows a vertical section along the line V-V of FIG. 4.

(6) FIG. 6 shows a schematic view of the vapour exhaust of the reactor.

(7) FIG. 7 shows a vertical section along the line VII-VII of FIG. 6.

(8) FIG. 8 shows a vertical section along the line VIII-VIII of FIG. 7.

(9) FIG. 9 is a schematic section through the granulate feeder arranged at the inlet of the reactor.

(10) FIG. 10 is a schematic view of the separator arranged at the outlet of the reactor.

DETAILED DESCRIPTION

(11) FIG. 1 generally illustrates the multistage thermal treatment apparatus of the present invention. The apparatus comprises a reactor 10, which has a cylindrical housing 19. Along the longitudinal axis of the reactor 10 three different heating zones 11a, 11b, 11c are provided. The first heating zone 11a can be heated to a first temperature between 100 to 200 C., preferably 150 to 180 C. The second heating zone 11b can be heated to a second temperature between 200 to 300 C. The third heating zone 11c can be heated to a temperature between 300 to 600 C., preferably 440 to 550 C.

(12) The reactor 10 further comprises a conveyor screw 20 which is driven by a driving means (not shown). The conveyor screw 20 is arranged within the housing 19 of the reactor 10.

(13) A container 14 takes up product granulate of the rubber waste, in particular scrap tires. The product granulate is transported from the container 14 to the inlet 12 of the reactor 10. The product granulate is transported within and through the reactor 10 by means of the conveyor screw 20. Accordingly, the conveyor screw 20 transports the product granulate through the heating zones 11a, 11b, 11c to the outlet 13. Here, the solid product granulate in particular carbon black 16 is recovered.

(14) The reactor 10 further comprises a vapour exhaust 15 for taking up the vapour phase of the thermally treated products. The vapour phase comprises so-called pyrolysis oil 17 and pyrolysis gas 18.

(15) Within the reactor 10 a low pressure environment with a pressure of about 20 to 50 mbar is provided. The reactor 10 is filled to about 60% of its volume with product granulate.

(16) Within the first heating zone 11a, a first process is carried out for a time period of between 2 to 4 hours until light oils are emitted anymore from the product granulate. The slow and long-lasting process in the first heating zone 11a at low temperatures has the effect that the light oils do not form non-removable products which contaminate the carbon black.

(17) In the second heating zone 11b the product granulate is pyrolized at a second temperature until no medium heavy oils are emitted anymore. Again, the slow and long-lasting process prevents non-removable products which contaminate the carbon black from being formed.

(18) In the third heating zone 11c the product granulate is pyrolized at a third temperature until no heavy oils are emitted anymore.

(19) At the outlet 13 the product granulate is removed from the reactor 10. The desirable solid materials, in particular carbon black and steel remains, are separated.

(20) The carbon black 16 recovered after the third heating zone 11c has a very 20 high purity in particular if the temperature applied in the third heating zone 11c exceeds the threshold of 500 C. In addition the carbon black 16 has a large surface resulting in high adsorption properties. Owing to its structure the carbon black 16 floats on water. Thus, the carbon black 16 received can be used as adsorption material in particular for adsorbing oils and lipids.

(21) If a lower temperature than 500 C. was applied in the third heating zone 11c the carbon black 16 can be refined at high temperatures of about 800 C. at low-pressure conditions for a time period of about 2 hours in order to receive commercial-grade carbon black 16a. The carbon black recovered has a purity comparable with commercial-grade carbon black and can therefore be commercially used.

(22) The properties of the carbon black after the refining process and after the third heating zone 11c (T>500 C.) are listed in table I (see below).

(23) TABLE-US-00001 TABLE I Properties of carbon black after refining or heating at temperatures higher than 500 C. Carbon Black Analysis Chemical Analysis/At % Carbon 95.46-96.02 Oxygen 2.38-2.90 Sodium 0.27-0.5 Magnesium 0.06-0.11 Aluminum 0.12-0.25 Silicon 0.66-1.48 Phosphorus 0.02-0.04 Sulfur 0.24-0.61 Calcium 0.29-0.93 Structure Analysis Particle size 40 nm Structure Blackberry-cluster Location for formation of pores between particles

(24) Details of the multistage thermal treatment apparatus will now be described with reference to the drawings.

(25) FIG. 2 shows a partial section through the reactor 10. As shown, the reactor 10 comprises a cylindrical housing 19 extending along its longitudinal axis 30. Within the housing 19 a conveyor screw 20 is arranged for conveying the product granulate within and through the reactor 10.

(26) The conveyor screw 20 comprises a shaft 21 which is supported by means of bearings 22 at the inlet 12 and the outlet 13 of the reactor 10. The conveyor screw 20 comprises a worm 25 with a variety of pitches to provide different speeds within the reactor 10. At the outer circumference of the worm 25 non-ferrous metal supports 26 are provided in order to support the conveyor screw 20 at the inner side of the housing 19 of the reactor 10.

(27) At the housing 19 reinforcing rings 23 are provided in the area of the supports 26.

(28) Heating mats 24a and 24b are arranged at the outer circumference of the housing 19. The heating mats 24a, 24b can be separately controlled in order to provide different temperatures within the heating zones 11a, 11b, 11c.

(29) In the region of the reinforcing rings 23 a reduced temperature prevails. This causes a condensation of oil in the region of the supports 26 whereby the conveyors screw 20 is lubricated. The same effect occurs in the region of the supports 22.

(30) FIG. 3 shows a vertical section along the lines III to III of FIG. 2. As shown, the non-ferrous supports 26 are supported by the housing 19 which is reinforced by the reinforcing ring 23 in this area.

(31) Referring now to FIGS. 4 and 5, the conveyor screw 20 comprises rollers 28 arranged within the worm 25 of the conveyor screw 20. The rollers 28 prevent deposition of the product granulate on the conveyor screw 20.

(32) As best shown in FIG. 5, the worm 25 comprises recesses 27 extending in the radial direction of the conveyor screw 20. Within each of the recesses 27 a rotating roller 28 is mounted.

(33) FIG. 6 shows the vapour exhaust 15 of the reactor 10. The vapour exhaust 15 comprises an annular pipe 31 which is connected to a condenser 35. A cooling device (not shown) is attached to the annular pipe 31. Within the annular pipe 31 a cleaning means 32 is provided. The cleaning means 32 comprise a chain 33 which is driven by a motor 34. Brush elements 36 are arranged on the chain 33 at a distance from each other. When the cleaning means 32 is driven in the direction of arrow 37 the annular pipe 31 is cleaned. Furthermore, sprayers 38 are provided within the condenser 35 and within the annular pipe 31 for cleaning the brush elements by means of pyrolized oil.

(34) FIG. 7 shows a vertical section along the line VII to VII of FIG. 6. The vapour exhaust 15 is located in an upper area of the reactor 10. In this region the housing 19 of the reactor 10 comprises a longitudinal groove 15a taking up and guiding the brush elements 36 of the cleaning means 32.

(35) FIG. 8 shows a vertical section along the line VIII to VIII of FIG. 7. A perforated sheet 15b is arranged at the bottom of the longitudinal groove 15a comprising a plurality of longitudinal slots 15c. When the chain 33 is guided through the annular pipe 33 the brush elements 36 gear into these longitudinal slots 15c and thus clean the annular pipe 31 of the vapour exhaust 15 thoroughly.

(36) FIG. 9 shows the container 14 for the product granulate the outlet of which comprises a conveyor 39 for compressing the product granulate and conveying the same to the inlet 12 of the reactor 10. The conveyor 39 comprises a driven conveyor screw 40. The container 14 is filled with a protective gas, such as argon, to prevent oxygen from entering the conveyer 39. Thus, oxygen is prevented from coming together with the product granulate.

(37) FIG. 9 shows the separator 42 which is arranged at the outlet 13 of the reactor 10. The product granulate is transported by means of a conveyor 41 to the separator 42. The separator 42 comprises a sedimentation basing 43. A mill 45 breaks up the product granulate into particles of about 1 to 10 m and helps to separate the different materials. The solid materials are separated within the separator 42. The steel contained in the pyrolized product is deposited on the bottom of the sedimentation basing 43. Owing to its special structure the carbon black 26 accumulates on the surface of the water and can be removed by a stripper 44.

(38) TABLE-US-00002 LIST OF REFERENCES 10 Reactor 11a First heating zone 11b Second heating zone 11c Third heating zone 12 Inlet 13 Outlet 14 Container 15 Vapor exhaust 15a Longitudinal groove 15b Perforated sheet 15c Longitudinal slots 16 Carbon black 17 Pyrolysis oil 18 Pyrolysis gas 19 Housing 20 Conveyor screw 21 Shaft 22 Bearing 23 Reinforcing ring 24 Heating mat 25 Worm 26 Support 27 Recess 28 Roller 29 Filling level 30 Longitudinal axis 31 Annular pipe 32 Cleaning means 33 Chain 34 Motor 35 Condenser 36 Brush elements 37 Arrow 38 Sprayer 39 Conveyor 40 Conveyor screw 41 Conveyor 42 Separator 43 Sedimentation basing 44 Stripper 45 Arrow 46 Arrow