WO1999008849A1

WO1999008849A1 - Apparatus for recycling of old rubber tyres and other products of polymer materials through oxygen-free pyrolysis in a connected continuously operating system

Info

Publication number: WO1999008849A1
Application number: PCT/SE1998/001482
Authority: WO
Inventors: Per-Ivar Nylander
Original assignee: Nylander Per Ivar
Priority date: 1997-08-19
Filing date: 1998-08-17
Publication date: 1999-02-25
Also published as: SE510408C2; SE9702972D0; SE9702972L

Abstract

Apparatus for recovery of old rubber tyres and other products of polymer materials through oxygen-free pyrolysis in a connected continuously operating system. As the pyrolysis process means exposing of hydro-carbonaceous materials temperatures up to about 900 degrees C and moreover involves strongly degreasing carbon black as one of the degrading products, it is necessary to emphasise the safety and environmental protection questions at the analysis and determination of the technical solutions and the overall functionality at all potential operation conditions for the complete apparatus. This has generally been taken care of by drying and preheating of the supported material by the oxygen-poor gases from the heating plant for the pyrolysis process, choice of safely functioning self-inerting locks at the in- and outlets of the slightly over-pressurised pyrolysis oven, directly connected crushing section for the carbon black residual with simultaneous separation of the steel armament and other solid end products and finally the integration of all co-operating elements to a tight standardised module also suited for modularised assemblies for increased capacities. Dispatch of all recovered products - Oil (about 40 weight.% of the supplied tyre quantity), Carbon black (45 %), Gas (10 %), further Steel armament and other remainders can easily be effectuated from separated hold-up storages at minimum manual action and environmental disturbances. The apparatus affords the flexibility to process whole tyres as well as cut and fragmented tyres and other products of polymer materials. The apparatus is controlled and supervised by a comprehensive computerised system and fabricated in standardised prefabricated modules for rational maintenance and international container based deliveries.

Description

DESCRIPTION OF THE INVENTION.

APPARATUS FOR RECYCLING OF OLD RUBBER TYRES AND OTHER PRODUCTS OF POLYMER MATERIALS THROUGH OXYGEN-FREE PYROLYSIS IN A CONNECTED CONTINUOUSLY OPERATING SYSTEM.

1. General.

Increasing demands on recovery of waste products have been established and addressed to actual equipment producers being responsible for proper handling of the waste in accordance with relevant demands under the Environmental protection Act. ° The recovery should be directed towards reuse for new production purposes as much as possible.

Pyrolysis of polymer materials is well known and officially documented. Regarding pyrolysis of rubber, reference is made to the Swedish journal Gumminytt(Rubber news) 2/87. 5 pyrolysis of rubber and also other polymer materials means exposing of hydrocarbonaceous materials to high temperatures with due risk for explosions at relatively small oxygen contents. At the preparation of this innovation simple, functionally safe and pre-inspectable systems-and equipment's designs based on systematic analyses have been chosen, in order to assure high safety and good 0 environmental properties for the operation staff as well as towards the surroundings. Also the fact that the apparatus is performed as a connected complete system from the inlet position for the tyres to the outlets for the dispatch of the separated recovered products contributes to this.

2. Specific description of the invention applied for. 5 a. Whole tyres.

Attached sketch, figure 1 , shows the scope and principal arrangement of the apparatus. Notations in the description are to be found on the figure. The waste material- normally worn private car tyres of standard sizes- is brought up without rims in good ordered piles. The piles are one after the other put into an inlet funnel(1)furnished with a bottom 0 placed cutting machine(la), which cuts the tyre in two halves falling down astride of a guiding pipe with the cut ends standing on a conveyor(2).This transports the tyres through a closed high-pressure wash- and drying section(3), where the drying is attained by the hot gases from the heating system for the pyrolysis-oven. The transportation of the half tyres leads up to the waiting position(4) at the inlet lock to the pyrolysis oven(5). 5 At this position the support of the oxygen-poor gas from the heating system for the pyrolysis oven takes place, which offers two technically important prerequisites - firstly that the space in front of the inlet lock gets oxygen-poor atmosphere which reduces potential explosion risks- secondly that the tyre will be heated up to about 100 degrees C, i.e.20 degrees below the sticking temperature for the rubber which means the best start-up for the pyrolysis process in the oven with maximum capacity. From the waiting position the half tyre falls down rapidly into the first stage of the inlet lock when the upper damper(5a) is quick- opened and re-closed controlled by the positioning of the tyres in the oven. Since a certain over- pressure reliminary about 300 mm wg) is kept in the oven in relation to the inlet lock and also towards the waiting position and that a valve- furnished bypass connection is arranged between the upper part of the lock over the upper specifically tight damper towards the waiting position, a short automatically controlled exhaust takes place from the oven together with small leakages over the lower dampers through the lock and further via the bypass connection which drains the blow-off gas to the heater serving the pyrolysis oven heating system. After a short standby for the tyre in the inlet lock it is assured that the lock space is poor of oxygen and filled up with gas of the same quality as in the oven. As a further safeguard a supplementary short supply of inert gas(nitrogen) to the lower part of the lock space can be done. The two lower lock dampers(5b and c) are quick-opened thereafter automatically controlled by the tyre positioning in the oven so that the down falling tyre gets a distance to the tyre before of about 10 centimeters in order to facilitate a good energy transport to the tyres during the pyrolysis process. The lower dampers are shut directly after the passage of the tyre. The reason for doubling the lower damper arrangement is partly to attain the necessary heat shield towards the tyre relative to the high oven temperature, 400-500 degrees C in this part of the oven, partly to attain an extra safety for the closing function here. The horizontal driving of the tyres through the oven(6) is done by chain-,screw- or belt-type conveyor(δb) or otherwise based on testing experiences. The driving speed is adjustable and automatically controlled to make sure full pyrolysis of the rubber material before the dispatch of the remainder. Conveyed trough the oven the tyre-halves are passing over a centreline steel pipe(6c) heated by a later described main heating unit or a separate burner. The centreline steel pipe makes a heating complement to a heating cylinder(6d) which surrounds the pyrolysis oven to attain as high energy supply as possible to the pyrolysis process and further the best distribution of the heating capacity to the material in the oven. The heating cylinder is furnished with gas and oil burners. Moreover electric heaters(δe) are added at the outlet end of the oven in order to secure the desired top temperature of about 700-900 degrees C aspired to attain full pyrolysis penetration and the best quality for the carbon black remainder.

The necessary processing time for the tyres in the oven is calculated to about half an hour, in which a transformation occurs into about 40 weight-% Fuel Oil(similar to Eo1/diesel oil), 15% Gas(methane and other hydrocarbons) and 45 % Carbon Black. Additionally comes Steel Reinforcement and Cord fragments(Glass Fibre material). At the discharge end of the oven an internal tilting mechanism is arranged(6f) so that the now carbonised tyre falls down on the upper damper(7a) of a discharge lock(7) whose function is analogue to the lock at the inlet. The carbonised tyre falls after the lock down in a crush chamber(8) with a crushing-mill from which the carbon powder falls down in a carbon silo(9) with discharge device. The reinforcement steel together with cord remainders glides down into a container(IO) prepared for periodic dispatch. Extracted oil and gas from the pyrolysis is led from the bottom drain to the underlying oil and gas tanks(11 and 12) with connected process systems(11a and. 12a) for necessary treatment, partly for the supply need for the heating of the pyrolysis oven, partly before dispatch to customers for reuse of the extracted products. To provide earlier specified overpressure(around 300 mm wg) in the oven in relation to the locks under varying operation conditions a sensible system for pressure balancing through pumping to/fro the gas store respectively inlet of inert gas is foreseen. Moreover safety valves(13) according to regulations are installed. Heating of the oven is intended to make use of the extracted energy products, gas and oil within the lower temperature field up to 500 - 600 degrees C, calculated to represent the greatest part of the energy demand, while the finishing top-heating at the discharge of the oven up to about 700-800 degrees C is intended to be arranged by electric elements. Concerning the choice of material for the oven this may get the consequences that the top-heated part of the oven should be internally lined with ceramic material. This may also be relevant for the discharge lock and thereafter placed parts exposed for the highest temperatures if not as an alternative get protected through cooling arrangements. Those internal parts primarily related to the pyrolysis process are inerted by nitrogen before start-up under simultaneous heating and control of e.g. pressure conditions and gas qualities in different parts of the plant. The plant is furnished with a comprehensive computerised l&C-system similar to modern petrochemical plants. Figure 1 shows the principal arrangement of the apparatus at axial conveying of the tyres. Same principal function can be attained at longitudinal tyre placement, when two or more tyres can move forward in parallel through the apparatus In this case the centrelined pipe(6c) will suitably be replaced by two pipes, one above the other, on each side of the tyres alternatively with electrical elements between the tyre rows moved forward as shown by cut A1-A1 below on the sketch. In planned prototype testing both alternatives intends to be tested and analysed between themselves.

Both the alternatives are included in the patent applied for. The last presentedalternative means that the extracted pooring oil on the tyre surface will not gasify towards the oven heating pipes to the same extent as in the first described alternative and also that alternative processing of whole tyres respectively cut or fragmented material, which is described in the following section, is judged to be possible to arrange with small adjustment needs, because the same conveyor in the oven can be used in all actual cases

b) Cut and fragmented tyres and other waste products of polymer material. The apparatus can be used also for these forms of products principally in accordance with the above given description, however with the following modifications: -the pre-preparation of the waste product and the transportation device up to the intake lock has to be adapted -the intake lock(5) will be placed in front of the oven and be supplemented by a subsequent hold-up volume with a supply-unit for continuos feeding of the material on the oven conveyor. This arrangement is shown below on the drawing, marked Alt. 2b. c) Main data table/preliminary.

Length of oven modul, net. 7-8 meters(parallel coupling of up to four modules is anticipated) Oven temperature about 400 inlet and 800 outlet end, degrees C

Capacity each module 25-35 whole tires( private car)/hr= 200-250kgs/hr

Power demand 90-110 kW's

3)Competing pyrolysis concepts./Some references.

-The company AEA- Beven, Harwell, Great Britain is marketing a pyrolysis concept for so called batchpyrolysis, where the tyre material first is pyrolysed in a closed container.After cool-down the container is opened for charge taking of the carbon black, steel and remainder products. Thus the process is divided by intervening manual activities.

-The company ECO-2 lnc,Ecological Economics,Florida,USA is marketing a pyrolysis concept basically a continuously operating rotating cylinder where the tyre material is supplied at one end of the externally heated cylinder and the solid products, carbon black, steel and remainders are discharged separated at the other end. The tyres are fine shredded before feeding into the rotating oven.

-The company Crossmac Recycling System AB,L:a Edet, Sweden have patent pending for a total system for recovery of tyres and other polymer materials by pyrolysis. The pyrolysis oven is fed by tyres in shredded or other fragmented forms.

Claims

PATENT CLAIMS.

1. An apparatus for recovery of old rubber tyres and other products of polymer materials through oxygen-free pyrolysis in a connected continuosly operating system c a ra c t e ri z e d b y a complete arrangement for pyrolysis based recycling of charged material to reusable decomposition products performed as follows: -charging devises for tyres and externally fragmented materials, -conveying devises for transportation of the material to the intake lock in front of the process oven under simultaneous washing, drying, pre-heating and inerting of the material by counter-current hot and oxygen poor smoke gases from the heating system for the process oven,

-multi-stage intake lock for tyres and externally fragmented material, -process oven with surrounding and internally arranged heating surfaces connected to separated heating system fired with gas and oil extracted from the pyrolysis process within the temperature interval 500-700 degrees C and at the oven discharge end combined with electric heating elements to optimise the material decomposition in the oven, further drainage of the decomposition products- oil and gasified hydrocarbons- via cooling and condensation arrangements to hold-up tanks for periodic dispatches for reuse, -discharge lock from the process oven to a crush chamber similar to the intake lock for the solid remainders- carbon black, steel armament and woven remainders(cord). -crush chamber with crushing devices and supplementary heating for potential remaining pyrolysis demands including optimisation of the carbon quality, further screening devices for the separation of the carbon component from the steel and remaining solid remainders to separated internal containers with cooling and lock arrangements for periodic dispatch.

2. Arrangement according to patent claim no 1 c a ra c t e ri z e d b y a performance of the multistage lock for the material charging to the process oven with fast operated dampers controlled by the oxygen content in an intermediate chamber with under-pressure held through transfer of the gases to the burner for the process oven heating system for destruction of hydrocarbon gas leakage including smell.

3. Arrangement according to patent claim no 1 c a ra c t e ri z e d b y balancing of the over pressure in the process oven through pulling the discharge pipe for the decomposition products-gas and oil- to emerge a distance under the constantly hold oil level in the low positioned hold-up tank(so called silent cooking arrangement), further that cooling takes place of the oil in this tank, resulting in a primary condensation effect on the discharged gaseous hydrocarbons and also creation of desired over pressure in the process oven related to the intake- and discharge locks.

4. Arrangement according to patent claim no 1 c a ra c t e ri z e d b y placing of the intake lock at processing of externally fragmented charge material in front of the oven and supplementing it with a buffer volume with charging device( for instance screw type) for continuos material charging on the conveyor in the oven.

5. Arrangement according to patent claim no 1 c a ra c t e ri z e d b y delivery of the equipment as a standardised and adjusted complete module for continuos automatic and computerised control and supervision with periodic discharge of de-composition products in "raw condition" to meet high demands on security and environmental qualities as well as good economic competition.