Patent Application
20050234274
The invention relates to an industrial low-temperature pyrolysis method for separating steel/rubber or similar composite products for recovering carbon granulate, pyrolysis oil, residual gas and metallic components, and to the use of the pyrolysis products.
The method is used for the industrial salvaging, especially of discarded rubber products or rubber-like composite products. In connection therewith, a carbon granulate is produced by low-temperature pyrolysis from, for instance, tires, rubber-coated tread links, steel cable reinforced rubber belts and the like. In addition, pyrolysis oil and residual gas are accumulated as well. The metallic components are recovered.
Pyrolytic methods for treating organic materials and material mixtures are commonly known.
For instance, German patent DE 695 11 626 T2 describes the pyrolysis of waste in an internally heated rotary tube furnace.
DE 199 30 071 C2 discloses a method and an apparatus for pyrolysis and vaporization of organic materials and material mixtures. Here, the organic material is brought into contact with the fluidized bed material of the combustion fluidized bed. Pyrolysis products such as gases with condensable substances and carbon-containing residues are produced.
Patent DE 44 41 423 A1 describes a pyrolysis method and an apparatus for the recovery of useable gas from waste. In connection therewith use is made of a pyrolysis drum.
German laid-open patent specification DE 41 26 319 A1 discloses a method of pyrolysis of vulcanized silicone rubber in which the vulcanized material are heated to 350° C. to 700° C. and the resultant volatile siloxanes are condensed. The products obtained are, in particular, siloxanes and fillers.
German patent DE 40 11 945 C1 describes a low-temperature pyrolysis for degassing organic materials in a heated pyrolysis chamber in which the pyrolysis material is compressed and is fed through chamber in this state. Gaseous products of the pyrolysis are removed.
German patent DE 39 32 803 discloses a pyrolytic method by which organic materials are reacted to coal and graphite in a non-oxidizing atmosphere by addition of boric acid/boric oxide and organic nitrogen compounds.
German patent 28 34 475 C2 sets forth a method of treatment of a pyrolysis heating oil. By application of a promoter liquid, the result of this method is a special carbon (acicular coke).
The hitherto known methods operate with rotary tube furnaces, pyrolysis drums, fluidized bed, under pressure, by compressing the material or in an inert atmosphere. This entails increased expenditures for apparatus, material, energy and logistics.
The use of protective gases (non-oxidizing atmosphere) leads to a reduced throughput capacity relative to comparable units. The generation of a fluidized bed requires more energy since, on the one hand, the fluidized bed has to be maintained and, on the other hand, the materials to be pyrolyzed must be mechanically prepared such that they can effectively contact the fluidized bed. Compressing the raw materials in preparation for, and during, the pyrolytic operation also requires more energy.
It is an object of the invention to develop a novel technology particularly advantageous in terms of energy and economy, for the treatment of different rubbers or rubber-like composite materials with the goal of separating rubber/steel or other composites and recovering essential organic components, such as carbon granulate (soot), organic oils and, where applicable, metallic components.
For effectively practicing the novel method new reaction containers and other novel method modules relating thereto are to be developed and applied at the same time.
By developing modules the throughput is to be incrementally increased to correspond to any given market situation. The solution is to be in conformity with the desire for continuity.
In accordance with the invention, the object is accomplished by the elements of claims 1 and 8. The subclaims set forth further advantageous embodiments of the invention.
As conceived, the sequence of the method in accordance with the invention includes the following operational steps and related components:
The operational control of the system is carried out by a central DDC conveyor system or SPS control. It monitors and controls the operation by way of interfaces. The operations and the decisive parameters are schematically presented on a video monitor. Malfunction signals occur automatically error signals are recorded, printed out in clear text, evaluated and automatically forwarded to operational control.
The pyrolysis furnace used is a car tunnel kiln. For this purpose, converted standard hearth ovens from other fields of application are being used.
The loading with the reaction containers takes place in steps. Initially, it is placed by a forklift onto the furnace carriage of the pyrolysis oven. Upon actuation of a push button or the like the furnace carriage is moved into the furnace. The gate is then closed.
Alternatively, a shaft furnace may be used as a pyrolysis oven for receiving a reaction container.
The shaft furnaces used may be standard equipment converted from other fields of application.
The furnace may be positioned above ground or subterraneously. In that case, the reaction container is inserted by an appropriate lifting apparatus, for instance, by traveling winches or hoists. The reaction container may be constructed such that a special seal at the head of the container positions the container within the shaft and also hermetically seals the furnace.
It is within the scope of the present invention to provide for other solution for the structural exterior shape of the reaction container. The container, for reasons of process technology, has to be structured so as to ensure good heat transfer in its interior so that all pieces of input material are heated equally.
In a car tunnel kiln the closed pyrolysis container is moved on the furnace carriage, unloaded by a forklift and placed on the ground for cooling. The operation with a shaft furnace is similar.
By using reaction containers made of high temperature resistant steel which operate without pressure and without inert media it is possible to operate with discontinuous charges. The process thus offers the possibility of appropriately reacting to the kind of material (e.g. automobile summer tires, automobile winter tires, truck tires, special vehicle tires, rubberized thread links, steel cable reinforced rubber belts). The charging technology is constructed on a modular principle. The newly developed process operation eliminates the use of protective gases or liquids.
Another advantage is the avoidance of complex mechanical pre-treatment processes for the input materials. For instance, the tires are only washed and coarsely cut or shredded.
After the start-up, the conduct of the process is substantially self-sufficient in terms of energy.
Another important advantage is that steel-rubber-composites which heretofore could only be separated by a high application of energy, can now be separated without using much extraneous energy or possible wear, and that the output products may be efficiently recycled in high-quality applications so that resources are spared. This opens up some completely new fields of application of the materials recovered by the method.
The method in accordance with the invention and the apparatus may be advantageously used in the processing of used tires, complete used vehicles, electronic scrap, steel-cable reinforced rubber belts, rummer/nonferrous metal composites, plastic-coated chains, rubberized tread links and various technical rubbers.
Further details, characteristics and advantages will be apparent from the ensuing description of an embodiment with reference to the appended drawings, in which:
The flow diagram of
The washed tires 1 are cut up in a shredder unit 3. Thereafter, the tire parts are dried. The heating register of the drying facility is operated by a heat exchanger which is fed by the pyrolysis process (heat from heat recycling 17).
The temperature control of the drying air is continuous and is carried out by computer-assisted controls which are monitored by a central process control and the target data of which can be changed.
The further process operation includes the following process steps and appurtenant system components:
The further processing of the pyrolysis gas 32 by water cooling 21 leads to the formation of condensed pyrolysis oil 33. From this pyrolysis oil 33, products/aromatics P1 to P3 and residual tank oil P4 will be produced by refining/separating/processing 35. The residual oil P4 may be used for the thermal supply and energy production for one's own and others' purposes. The non-condensable pyrolysis gas is temporarily stored as waste gas 34 in a bell-shaped container and is burnt off in a further process at temperatures above 1,200° C. The dwell time is equal to or longer than 0.3 sec. Downstream from where the burning off of the waste gas 34 is taking place, heat conductors are installed into the waste gas oven which by way of the heat recovery 17 feed any excess heat back to the production process.
The heat from the heat recovery 12 may either be fed to the production process, i.e. the preheater 8 for the reaction container 7 and to the pyrolysis furnace 9 for preheating the combustion air 17.1, or heat 17.2. which has not been used can be used for other purposes, e.g. the heating of buildings.
a and 2b are front and lateral views of a car tunnel kiln 9.1 fi=or the reaction container 7. A given reaction container 7 is placed on a power driven furnace carriage 22. The diameter and height of the reaction container 7 here in use are 1.8 m and 2 m, respectively. The other technical specification of a car tunnel kiln for a reaction container are:
The pyrolysis furnace 9.1 is completely lined and insulated; it is provided with a lifting gate 23 or the like for closing and opening of the furnace 91. The burner facility 24 consists of two special burners with 2 appropriate conduits and devices for natural gas or process gas or process oil, combustion air or electric heating.
Furthermore, there are present:
An waste gas conduit 11 enters into the lid of the reaction container. Above the lid, a cut-off valve mechanically connected to the lid and made of high-temperature resistant and vacuum-proof materials is integrated into the conduit. The connection with the continuing waste gas conduit is established by a rapid connection; thereafter the cut-off valve is opened.
When removing the container the sequence is reversed. The container has to be handled such that good heat transfer is ensured in its interior and that all input pieces are heated equally.
The technical specifications of a shaft furnace for reaction containers are:
The pyrolysis furnace 9.2 is completely lined and insulated. The burner facility consists of two special burners with appropriate pipe conduits for natural gas and process gas or process oil and combustion air. Furthermore, there are present:
Optionally, the lid of the reaction container may be provided with a vacuum-tight recirculation motor. Recirculation leads to particularly uniform drying of the pyrolysis material. Inserts are placed into the pyrolysis container 7 for storing the materials to be pyrolyzed. Spacers and conducting sheets ensure a particularly precise conductance of the pyrolysis gas stream. This ensures a complete and efficient pyrolysis.
The conductance of the waste gas is analogous to that of the car tunnel kiln. Connecting pipes for safety valves and a waste gas conduit of about 80 mm diameter and a vacuum-tight high temperature resistant cut-off valve are provided at the lid. The connection of the feed and disposal conduits is preferably established by rapid connections.
Depending upon the density, up to 4.5 tons of input material can be placed into the container 7. The quantity of filled material consisting of rubber tires is about 0.5 tons. At mixed charge (e.g. rubber strips, rubberized treads) the charge will be about 3.5 tons to 4.5 tons. Container modules of different dimensions are also possible.
The thickness of the container wall corresponds to the static requirements.
The pyrolysis oil produced in accordance with the invention is used as an energy source. With electricity and heat, the pyrolysis oil is advantageously used as a heating oil for the self-sufficient supply for the pyrolysis system.
On the other hand, the pyrolysis oil consists of a number of components which are used as synthesis building blocks for the production of chemicals, polymers and other intermediate products.
The pyrolysis oil contains about 0.4 to 0.16% sulphur and is a black, turbid and easily combustible liquid. It characteristically smells of aromatics and contains cyclopentadiene as well as further bicyclenes and aromatics as synthesis building blocks. More particular, aromatic components such as dipentene, toluene, and xylene were detected. The pyrolysis oil is preferably refined into the dipentene, toluene and xylene components.
Dipentene is particular importance. This chemical compound may be grouped with terpenes and has an agreeable lemon-like odor. This component of the pyrolysis oil is used by the chemical industry in large quantities for the production of solvents, resins and perfumes. Furthermore, dipentene may be used as a surrogate for the fluorinated and chlorinated hydrocarbons (FCHC).
Toluene and xylene are also important starter materials for chemical substances of plant protection agents, dye syntheses, solvents, plastic materials and pigments.
The carbon granulate obtained in accordance with the invention is an inactive filler and is especially suitable as a filler for crude rubber in the production of rubber and tires.
As determined by the BET method, the inner surface of the soot produced from carbon granulate is, depending upon process conditions, between about 77 m2/g and 42 m2/g.
The carbon content of the carbon granulate is about 97.8%, the remainder is ash. Furthermore, the carbon granulate is insoluble in cold acids, such a sulphuric acid, nitric acid, hydrochloric acid or in caustic solutions. Solubility in polar or non-polar solvents has also not been detected. Nitric acid spontaneously decomposes into water and nitrous gases which may be traced to catalytic action of the large internal surface.
The carbon granulate is also used as the starter material for the production of dye pigments for printing dyes. The carbon granulate is an ultra-fine powder which satisfies the high requirements placed on dyes.
Another preferred field of application of the carbon granulate is the production of active coal by a method downstream from the pyrolysis method for enlarging the surface of the carbon granulate to up to 1,000 m2/g.
The active coal thus obtained may be used in filters for purifying water or of gas in exhaust systems. Other fields of application reside in the food stuffs industry and in medicine.
Because of its properties, the carbon granulate swims on the surface of water and absorbs oils present on the water. Also, it is oleophilic and may thus advantageously used on the surface of water as an oil binder or agglutinant. It may also be used on mineral oil contaminated soil or cases of damage caused by oil.
The carbon granulate can also be advantageously used where oil is burning. The carbon granulate may be generally used as a fire extinguisher. Oxygen will be removed from a fire covered and thus extinguished by a sufficient quantity of carbon granulate. Coating glass with carbon granulate results in increased fire resistance coupled with a thermal insulation effect.
A further advantageous field of application of the carbon granulate in accordance with the invention is its use in water retention layers. By using the carbon granulate in layer thicknesses less then sand layers water and plant nutrients can be stored and poor soil of low value may be used as planting locations for vegetables and agricultural products. In accordance with a preferred embodiment of the invention, layer thicknesses of 50 to 100 are used to yield a remarkable success.
In this connection, mention is to be made of the property of the carbon granulate that is releases no substances into the water phase and that, therefore, neither soil nor ground water are contaminated by leaching out of contaminants.
A particularly preferred field of use of the carbon granulate obtained by the invention is its use for producing light-weight building elements which display a special thermal insulation effect. Advantageously, a mixture of a ratio of carbon granulate and cement of 2:1 to 5:1 is used. The preferred ratio is 3:1.
A plate of 10 mm thickness of the mentioned material of the preferred ratio resists an illuminated propane gas flame without any measurable increase in temperature at the opposite surface.
List of Reference Characters
| Number | Date | Country | Kind |
|---|---|---|---|
| 102-19-440.8 | Apr 2002 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DE03/01373 | 4/24/2003 | WO | 6/13/2005 |
