Pyrolysis Of Scrap Tires Research Articles

Kinetic study of scrap tyre pyrolysis and combustion

This paper investigates the kinetic of pyrolysis and combustion of scrap tyre using thermogravimetric and derivative thermogravimetric analysis method. Three materials, namely tyre rubber powder, tyre fiber and wood powder were studied and compared with each other. The process parameters show that these three materials exhibit different thermal degradation patterns during pyrolysis and combustion process. Thermal degradation models were proposed to derive the kinetic parameters. It was found that the process and kinetic parameters vary with heating rates but are less dependent on the powder sizes. The simulations by the proposed models agreed well with experimental data.

97/04288 Scrap tyre pyrolysis: Are the effluents valuable products?

97/04288 Scrap tyre pyrolysis: Are the effluents valuable products?

Scrap tyre pyrolysis: Are the effluents valuable products?

Scrap tyre pyrolysis under nitrogen is studied at atmospheric pressure with the aim of producing a solid residue to be burned simultaneously with coal dust in a coal burning power plant. The experimental device maintains isothermal conditions. The temperatures of treatment are: 380, 450 and 550°C. Three phases are obtained after pyrolysis: solid, liquid and gas and their composition is studied in relation to the temperature of the thermal treatment. The solid phase (char)—approximately 40% weight of the initial sample (steel free) mostly constituted of carbon, also contains the main mineral matter initially present in the used tyre. The char produced is brittle and has a high burning power which makes it suitable for burning when mixed with coal dust in coal burning power plants. The stil weave is easily separated from the solid carbon residue after the thermal treatment and recovered without physical or chemical change and can be recycled. The gas phase contains a mixture of light hydrocarbons, dihydrogen and carbon dioxide. The IRTF spectra of evolved gases shows a change in the ratio of every gas while the pyrolysls takes place. The liquid phase is a complex hydrocarbon mixture in which some components have been identified. The chemical valorization of the liquid phase is an alternative to a thermal valorization. The pyrolysis appears to be a technique which is able to reduce a bulky, high polluting industrial waste, while producing energy and/or valuable chemical compounds.

97/01127 Pyrolysis of scrap tires: can it be profitable?

Pyrolysis--the thermal degradation in the absence of oxygen--is one way to reprocess scrap tires. The products are fuel gas, oils, and a solid residue (char), which contains appreciable quantities of mineral matter and low-grade carbon black. The three products have comparable yields by weight. The two most important factors affecting process economics are the tipping fees charged for tire disposal and the selling prices of the products. Selling prices of the products yield low returns because of the low market value of the fuels and the low quality of the recovered char or carbon black. Therefore, to obtain a positive cash flow, it would be desirable to develop a process based on the recovery of value-added products such as high-grade carbon black, activated carbon, or valuable chemicals (e.g., benzene, toluene, and xylene). The authors believe that significant improvement in the economics can be accomplished by upgrading the primary pyrolysis products to secondary products of higher value.

Rheological properties of bitumen modified with pyrolytic carbon black

Pyrolytic carbon black (CBp), a by-product of scrap tyre pyrolysis, was blended with a 150 200 penetration grade bitumen at concentrations ranging from 5 to 30 wt%. The fundamental rheological properties of standard and modified bitumens as well as their classical characteristics were determined. The interactions between CBp and bitumen components using ESCA, i.r. and u.v. spectroscopy were investigated. The results indicate that pyrolytic carbon black can be used as a filler to reduce the influence of temperature on physical response characteristics of the mixtures. The addition of CBp in amounts of 5–30 wt% of the binder changed the rheological properties of the blends positively.

Solid waste pyrolysis in a pilot-scale batch pyrolyser

The pyrolysis of different solid wastes was studied with a pilot-scale batch pyrolyser at different temperatures, fuel/air ratios and reaction times. The temperature distributions of the pyrolyser under control conditions and in the pyrolysis runs were determined. The gas and char yields were determined and the evolved gases analysed. The SO 2 and NO x emissions were low, 8–70 and 0–20 ppmv respectively, even in the pyrolysis of high-sulfur materials. The main combustible component of the pyrogas was acetylene (5–15 vol.%). Significant levels of methane and carbon monoxide, typically 3–10 and 2–5 vol.% respectively, were also found. The concentrations of higher hydrocarbons in the gas phase were very low (< 0.5 vol.%). The heating value of the pyrogas was 8–11 and 5.3–5.6 MJ m −3 for furniture waste and scrap tyre pyrolysis respectively.

Gas from the Pyrolysis of Scrap Tires in a Fluidized Bed Reactor

A fluidized sand bed reactor was used to study the production of gases from scrap tires at four nominal temperatures (ranging from 600 to 900 °C). Yields of 17 pyrolysis products (methane, ethane, ethylene, propane, propylene, acetylene, butane, butylene, 1,3-butadiene, pentane, benzene, toluene, xylenes + styrene, hydrogen, carbon monoxide, carbon dioxide, and hydrogen sulfide) were analyzed as a function of the operating conditions. The results are compared with the data obtained by pyrolysis of tires in a Pyroprobe 1000, where secondary tar cracking is small. Correlations between the products analyzed with those of methane are discussed.

The Autothermal Pyrolysis of Waste Tires

Abstract The growing amount of rubber waste, such as that from tires and cables, has resulted in serious environmental problems. Since rubber waste is not easily biodegradable even after a long period of landfill treatment, material and energy recovery is the preferable alternative to disposal. The potential offered by waste tire pyrolysis for solving both energy and waste treatment problems is widely recognized. Pyrolysis is one method of inducing thermal decomposition without using any oxidizing agent, or using such a limited supply of the agent that oxidization does not proceed to an appreciable extent. The latter may be described as autothermal pyrolysis and will be studied in the present work. The main objective of this research was to study the operating parameters of autothermal pyrolysis of scrap tires in a laboratory-scale fluidized bed reactor with a 100-cm bed height (10 cm I.D.) and a 100-cm freeboard (25 cm I.D.). Scrap tires were pyrolyzed in a limited oxygen supply, so that the heat for pyrolysis of the scrap tires was provided by combustion of some portion of the scrap tires. The operating parameters evaluated included the effect on the pyrolysis oil products and their relative proportions of (1) the air factor (O.O7–O35); (2) the pyrolysis temperature (370–570 °C); and (3) the catalyst added (zeolite and calcium carbonate). The results show that: (1) the composition of the liquid hydrocarbon obtained is affected significantly by the air factor; (2) the higher operating temperature caused a higher yield of gasoline and diesel; (3) the yield of gasoline increased due to the catalyst zeolite added, and the yield of diesel increased due to the addition of the catalyst calcium carbonate; (4) the principal constituents of gasoline included dipentene and diprene.

Numerical model for the vacuum pyrolysis of scrap tires in batch reactors

AbstractA quantitative model for scrap tire pyrolysis in a batch scale reactor developed comprises the following basic phenomena: conduction inside tire particles; conduction, convection, and radiation between the feedstock particles or between the fluids and the particles; tire pyrolysis reaction; exothermicity and endothermicity caused by tire decomposition and volatilization; and the variation of the composition and the thermal properties of tire particles. This model was used to predict the transient temperature and density distributions in the bed of particles, the volatile product evolution rate, the mass change, the energy consumption during the pyrolysis process, and the pressure histoiy in a tire pyrolysis reactor with a load of 1 kg. The model predictions agree well with independent experimental data.

Reactive coprocessing of scrap tires and heavy oil

Abstract The reactive coprocessing of scrap tires and heavy oil was carried out at temperatures of 375, 400, 425, and 450°C. The ultimate yields from the following process cases were determined: scrap tires without oil, SAE 50 weight oil without scrap tire, and scrap tires in the presence of SAE 50 weight oil. Kinetic constants were obtained for all three cases. The values of activation energy showed that the coprocessing of scrap tires and heavy oil is a more favorable reaction pathway for decomposing these waste materials to more useful products than the pyrolysis of tires alone. The distillates produced by the processing of these materials were analyzed using gas chromatography/mass spectroscopy. The analysis of the three cases showed that coprocessing scrap tires and heavy oil yields more toluene compared to the pyrolysis of the individual waste materials. Therefore, it was concluded that the coprocessing of scrap tires plus heavy oil occurs at a lower temperature and produces higher-value products than the pyrolysis of scrap tire without heavy oil.

Recycling of polymers by pyrolysis

The pyrolysis of plastic waste, scrap tires and other polymeric materials in a fluidized bed has been carried out based on a scale up program (laboratory plants 70 g/h, 500 g/h, 3000 g/h, and pilot plant 20-50 kg/h). The fluidized bed shows short residence times and high heat and mass transfers, and is heated indirectly up to 600-800°C. In the case of poly(methylmethacrylate) (PMMA) or polystyrene as feedstock up to 97 wt.% of the monomer can be recovered. Other polymers give a more unspecific product spectrum. Depending on the process parameters between 30 and 60% of the polymeric material could be recovered as oil which is comparable to that of a mixture of light benzene and bitumious coal tar if the pyrolysis gas is used as fluidizing gas. The other fractions are gas and a residue containing fillers and impurities (heavy metals). The gas fraction contains mainly methane, ethane, ethene, and propene, the oil fraction benzene, toluene, xylene, and naphthalene

Pyrolysis of scrap tires and conversion of chars to activated carbon

AbstractThe primary objective of this work was to demonstrate the conversion of scrap tires to activated carbon. We have been successful in this endeavor, producing carbons with surface areas greater than 500 m2/g and significant micropore volumes. Tire shreddings were pyrolyzed in batch reactors, and the pyrolysis chars activated by reaction with superheated steam. Solid products of pyrolysis and activation were studied with nitrogen adsorption techniques. We find that the porosity development during steam activation of tire pyrolysis char is similar to that reported for various other chars. A maximum in micropore volume is observed as a function of conversion, but the total surface area increases monotonically with conversion. We suggest that the activation process consists of micropore formation, followed by pore enlargement. The process conditions used in this study are a good starting point from which to optimize a process to convert tires to activated carbon.

PVC filled with vacuum pyrolysis scrap tires‐derived carbon blacks: An investigation on rheological, mechanical, and electrical properties

AbstractPyrolysis of scrap tires produces oil and carbon black (CB). The purpose of this work is to compare pyrolytic CBs with commercial grades as fillers for poly(vinyl chloride) (PVC). Blending of PVC with CB was performed in the melt at 180°C. The compositions prepared were 1,5,10,20, and 30 wt % of CB. The dynamic rheological, mechanical, and electrical properties of the PVC–CB composites were investigated. The results obtained for the storage modulus and complex viscosity of the composites of PVC with the pyrolytic CBs were between those of a high‐grade (Monarch 1100) and a low‐grade (Sterling R) commercial CBs. Intermediate tensile modulus, elongation at break, and electrical conductivity were also obtained. The specific surface area of the CB was shown to influence the composite properties. Reduction of the volatile matter and ash contents of the pyrolytic CB led to better properties of the PVC composites. © 1992 John Wiley &amp; Sons, Inc.

外熱式ロータリーキルンによる廃タイヤ熱分解実験

外熱式ロータリーキルンによる廃タイヤ熱分解実験

Active carbon from scrap tyres

The possibility of producing active carbon by activation at 850 °C of the char obtained from the pyrolysis (at 450 and 600 °C) of scrap tyres has been studied. The activated char showed good adsorbing characteristics, similar to those of typical commercial grades. The yield and the desired adsorbing capacity depend on the activation time. However, the ash content and friability are quite high; therefore the activated char is suitable for applications in powder form in which the ash does not cause problems.

Thermal recycling of polymers

As most plastics are produced from oil, the recycling of plastic and rubber wastes is of increasing importance. Systems for the pyrolysis of plastic wastes with complete exclusion of oxygen use melting vessels, rotary kilns or fluidized bed processes. The pyrolysis of plastic wastes, scrap tyres and other polymeric materials in a fluidized bed has been carried out at the University of Hamburg, based on a three-step scale-up programme (laboratory plant 100 g/h, pilot plant 30 kg/h and prototype plant 150 kg/h). Up to 50% of the input plastic material is converted into liquid hydrocarbons. The product spectrum is comparable to that of a mixture of light benzene and bituminous coal tar, consisting of about 95% aromatics. By addition of lime it became possible to absorb completely the hydrogen chloride evolved from poly(vinyl chloride). The technology in a fluidized bed allows the pyrolysis of whole tyres to include aromatic compounds, gas, carbon black and steel wire. A first commercial demonstration plant using the fluidized bed process with an annual plant capacity of 5000–10,000 t has been erected.

Semi-active carbon and aromatics produced by pyrolysis of scrap tires

Very promising results have been obtained in pyrolysis experiments carried out in a sieve-tray reactor, of our design, in the temperature range 400–700°C, employing a suitable gas stream in order to rapidly remove the pyrolysis products from the reactor and at the same time to activate the char. By pyrolysis of shredded rubber from scrap tires 36–38% of activated carbon, 49-38% of oil products and 15–30% of gas were obtained. The pyrolysis carbon shows specific adsorption, towards dyes for industrial uses, which seems higher than those of commercial active carbon and yields adsorption isotherms with a usual slope. The oils are characterized by high aromatic hydrocarbons and low sulphur contents (0.6% with nitrogen as a carrier gas, 0.2% with carbon dioxide); they could be used as plasticizers for rubber. The pyrolysis gases (mainly methane, hydrogen, ethylene, hydrogen sulphide) have a heat value of 6,000–7,000 kcal m −3.

Pyrolysis of plastic waste and scrap tyres in a fluid bed reactor

An outline of laboratory-scale investigations of pyrolysis is followed by a description of pilot-scale experiments designed to exploit the raw material content of polymeric substances rather than their heating value merely as fuels. Dependent on the feed material, gaseous products (40–60 wt.%, e.g. hydrogen, methane, ethylene, ethane) as well as liquid products (40–60 wt.%, mainly simple aromatics) are obtained. The gas is sufficient to heat the process. Fluid sand beds are surprisingly insensitive to the unit size of the feed material, so that scrap tyres can be pyrolyzed as a whole to avoid the cost of size reduction. Carbon soot and fillers are separated in a cyclone and metal pieces can be removed from the inclined bottom of the reactor. Results for a 2 Mg/day pilot plant are presented and a preview of a 4000 Mg/year plant is given, for which cost—benefit calculations are compared with those of some other scrap tyre pyrolysis processes.