Pyrolysis technologies

The different technologies involve indirect heating and are characterized by the method of heat transfer to the material and by the method used for mixing the charge in the furnace. Slow pyrolysis can be performed in rotary kilns, or in static furnaces equipped with moving 

The dimensions of these kilns are related to the nature of the material input and the capacity. Different furnace modelling approaches are recently proposed in the literature [65-67]. The design of the kiln is calculated to obtain complete carbonization of the product. Then, the power of the boiler is dimensioned according to the energy valorization choice. So, a plant is characterized either in terms of output power, or in terms of capacity for a defined wasfe input. Table 10.25 gives examples of different rotary kiln dimensions 

Rotary kilns are commonly used for different waste streams such as contaminated soils, petroleum residues, car shredder refuse, municipal solid waste (MSW) mixed with sludge and industrial waste, used tyres, etc. 

Waste nature Capacity (t/h) Length (m) Diameter (m) Constructor 

The furnaces are generally heated by the exhaust gases issued from the combustion of the pyrolitic gases. Cosa adopted an electrical heating system and Pyrovac a circulating molten salt system. 

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J. M. Femandez-Baujin and S. M. Solomon, "An Industrial Apphcation of Pyrolysis Technology Lummus SRT-III Module," paper presented at... 

Three recycling news items are very briefly reported upon a Canadian-developed pyrolysis technology that converts plastics scrap into alpha-olefins, a scrap-plastics-to-monomers system under construction in Scotland, and statistical forecasts on chemical recycling in Germany for 1996. 

The respective flash pyrolysis technologies are depicted in Figure 6.16 see Meier and Faix.103... 

Low-temperature pyrolysis technologies have shown increased refractory life and reduced maintenance requirements. 

It has been demonstrated that the deep pyrolysis technology used to prodnce HSGD can be applied to other carbonic sorbents made from granular synthetic, natural and fibrous raw materials. 

Figure 1 shows a computational framework, representing many years of Braun s research and development efforts in pyrolysis technology. Input to the system is a data base including pilot, commercial and literature sources. The data form the basis of a pyrolysis reactor model consistent with both theoretical and practical considerations. Modern computational techniques are used in the identification of model parameters. The model is then incorporated into a computer system capable of handling a wide range of industrial problems. Some of the applications are reactor design, economic and flexibility studies and process optimization and control. 

These two goals will be discussed separately with reference to pyrolysis technology on the one hand and to free radical mechanisms and processes on the other. 

Most papers dealing with pyrolysis technology begin with a statement on the well-recognized free radical nature of these reactions, but do not mention free radicals further. From a methodological point of view, a mechanistic approach would be the most satisfactory. Goossens et al. [77—79] have built up such a reaction model which, at least in principle, is compatible with both fundamental rigour and practical requirements... 

To achieve a catalytic layer on base materials is the core process for DSA-electrode fabrication. To ensure the layer stability, it is important to try to make the layer better adhesion with the base surface. We have tried several methods in the electrode preparation, including pretreatment, pyrolysis technologies, and electrodeposition. Till now, our research revealed that the electrode service life and the behaviors have been influenced by the electrode preparation methods and technological factors. 

Seglin, L., and Bresler, S. A., Low-Temperature Pyrolysis Technology, in Chemistry of Coal Utilization, M. A. Elliott (Ed.), Second Supplementary Volume, pp. 785-846, John Wiley Sons, New York, 1981. 

Kellogg Brown Root Ethylene Ethane/propane/butane/ naphtha/gas oils Millisecond pyrolysis technology produces ethylene and propylene 63 1996... 

Pyrolysis of tyres is a feasible, yet technically difficult operation. The handling of the remnants of the steel carcass, the carbon black, the zinc oxide, as well as the tendency to repolymerize of the major products are serious stumbling blocks. Various rubber pyrolysis technologies have been developed, using, e.g. fluid bed, rotary kiln (Sumitomo Cement), molten salts, or cross-flow shaft systems (WSL/Foster Wheeler). 

Fast pyrolysis (and flash pyrolysis) needs a very high heat transfer to and inside the material. Fluidized-bed technology is therefore well adapted for this purpose [68-70], New developments in this fleld involve vortex ablative pyrolysis technology. In both cases, high heat transfer within the material needs strict charge preparation (fine grinding). 

A. V. Bridgewater and S. A. Bridge A review of biomass pyrolysis and pyrolysis technologies, ln A. V. Bridgewater and G. Grassi (eds) Biomass Pyrolysis Liquids. Upgrading and Utilization. Elsevier Applied Science, London (1991). 

H. Tachibana, Current situation and future aspect of chemical recycling of waste plastics, especially for pyrolysis technology. Plastics Age, 49, (2003). 

H. Tachibana, Current situation of waste plastics pyrolysis technology, 6th FSRJ, Hokkaido University, 30 September 2003. 

This book provides an overview of the science and technology of pyrolysis of waste plastics. The book will describe the types of plastics that are suitable for pyrolysis recycling, the mechanism of pyrolytic degradation of various plastics, characterization of the pyrolysis products and details of commercially mature pyrolysis technologies. 

The major advantage of the pyrolysis technology is its ability to handle unsorted, unwashed plastic. This means that heavily contaminated plastics such as mulch film (which sometimes contains as much as 20% adherent dirt/soil) can be processed without difficulty. Other normally hard to recycle plastics such as laminates of incompatible polymers, multilayer films or polymer mixtures can also be processed with ease. 

TABLE 8.12 Typical Biomass Pyrolysis Technologies, Conditions, and Major Products"... 

Biomass pyrolysis technology is being developed very intensely in the last ten years and is now on the edge from the research phase to the demonstration phase. Up to now, some few tests have been done successfully with a low speed, heavy duty Diesel engine in the UK. In this paper it is anticipated, that the further RTD work with pyrolysis oil Diesel engines will be successful. 

Fast pyrolysis is not an equilibrium process. During fast pyrolysis dramatic changes occur in specific volume between the reactants (biopolymers) and the products (by a factor of x 500) causing the volatile products to leave the pyrolysis zone at considerable velocities. This results in the entrainment of solid particles and aerosols, which normally would not volatilise at the process temperature. All these phenomena have important inqilications on pyrolysis technologies and are discussed in this paper. 

Liquid yields of 35-50% on dry feed are typically obtained with higher char yields than fast pyrolysis systems. Conversely, the liquid yields are higher than in slow pyrolysis technologies because of fast removal of vapours from the reaction zone,... 

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