Scale pyrolysis processes

Other large-scale coal pyrolysis process developments were carried out by the Tosco Corp., with its TOSCO AT, process (36). Essentially a direct copy of Tosco s rotating kiln technology that was developed for pyrolysis of oil shale, this slow heating scheme achieved tar yields at maximum temperatures of 482—521°C that were essentially identical to those obtained by a Eischer assay. 

The performance of a novel microwave-induced pyrolysis process was evaluated by studying the degradation of HDPE and aluminiutn/polymer laminates in a semibatch bench-scale apparatus. The relationship between temperature, residence time of the pyrolytic products in the reactor, and the chemical composition of the hydrocarbon fraction produced was investigated. 28 refs. 

The application of a selective pyrolysis process to the recovery of chemicals from waste PU foam is described. The reaction conditions are controlled so that target products can be collected directly from the waste stream in high yields. Molecular beam mass spectrometry is used in small-scale experiments to analyse the reaction products in real time, enabling the effects of process parameters such as temperature, catalysts and co-reagents to be quickly screened. Fixed bed and fluidised bed reactors are used to provide products for conventional chemical analysis to determine material balances and to test the concept under larger scale conditions. Results are presented for the recycling of PU foams from vehicle seats and refrigerators. 12 refs. 

A plant operating according to the Hamburg University pyrolysis process was built at Ebenhausen, with a capacity of 5000 tonnes per year. The feasibility of converting poly-oleflns by pyrolysis was successfully demonstrated, with yields from PE/PP mixtures of typically 51% (m/m) gas, 42% (m/m) liquids and the balance unaccounted for. However, the gas to liquids ratio is very sensitive to pyrolysis temperature. Since gas and oil are the major pyrolysis products, economic viability crucially depends on the price of crude oil. Under present conditions, profitability and economic viability are unsatisfactory at this small scale of operation. 

A full-scale pyrolysis-catalytic process in which the catalytic cracking zone is directly connected to the pyrolysis zone was developed in Japan (Fuji Process) [19]. In this process, after separation of PVC and impurities by wet techniques, waste plastics are thermally pretreated at 300°C for dechlorination and then introduced into the pyrolysis reactor and thermally cracked at 400°C. Subsequently, degradation products are fed directly to the fixed-bed reactor using a ZSM-5 catalyst. 

A series of industry-scale processes for recovery of liquid fuel from waste plastics have been developed and applied in countries such as the United States, Japan, Germany and England. Some of the processes, such as the Veba process, the BP process, the Fuji process and the Hunan University process have been applied widely and successfully in industry. Some typical pyrolysis processes are listed in Table 28.6. 

Chapters 7-9 deal with the process aspects of pyrolysis to produce epbba. The first discusses the use of aerospace technology to simulate an unconventional process. The second discusses the results of recent attempts to develop computer models for large scale pyrolysis of hydrocarbons and the third discusses recent process and furnace design advances. 

The experimental system used to carry out this work is a bench-scale installation based on Waterloo Fast Pyrolysis Process (WFPP) technology (19,20). The biomass feeder supplies a continuous biomass flow rate of between 5 and 100 g/h. Thermal decomposition of biomass occurs in a fluidized bed reactor with an inner section of 4.35 cm. ... 

The following are the key uncertointies related to the scale-up of bagasse fast pyrolysis processes ... 

Over the last ten years, the vacuum pyrolysis process has been developed at the bench and pilot scales at the Universite Laval and Pyrovac Institute Inc. in Quebec, Canada. This thermal decomposition process enables a large variety of solid and semi-Uquid wastes to be transfoimed into useful products. Vacuum pyrolysis is typically carried out at a temperature of 400-500°C and a total pressure of 2-20 kPa [1], These vacuum conditions allow the pyrolysis products to be rapidly withdrawn from the hot reaction chamber, thus preserving the primary fragments originating from the thermal decomposition reactions. 

Based on the above three models, a dynamic model to scale-up the vacuum pyrolysis process was developed, which correlates the temperature and the mass of feedstock at any position on top of the heating plates inside the reactor, as a function of heat transfer, panicle flow and pyrolysis kinetics phenomena. The energy conservation in the reactor is the foundation of the model. It assumes i) steady flow, ii) one dimensional terr erature variation and, iii) feedstock thermal properties vary as a function of temperature T. 

The purpose of this study is to maximize the fraction of arsenic in wood charcoal while minimizing mass reduction of the bio-oil. Lab-scale pyrolysis was conducted in order to determine mass balances of yield and percentage of arsenic over the total system The experimental set-up was built to examine the influence of process parameters such as pyrolysis temperature and total pyrolysis time. The optimum combination of temperature and total pyrolysis time, at which the amount of arsenic retained in the wood charcoal is maximized and that in oil is minimized, was tried to be found. 

The optimisation of the bio-oil was aimed at adjusting the operating conditions of the fast pyrolysis process to maximize the concentration of these reactive groups in the bio-oil, while maintaining a high overall oil yield. Figure 1 shows the main part of the small-scale production facility for small amounts of the oil. It consists of the biomass feeder, the reactor and a bio-oil collection system. Before each experiment, a batch of sand was preheated inside an electrical furnace to about bOO°C, where after it is mixed with cold sawdust in the bottom of the cone. The produced vapours could be immediately removed from the hot reactor, and collected in several water-cooled vessels. 

The pyrolysis process for waste recycling is frequently done at larger scale than analytical pyrolysis. However, analytical pyrolysis studies are performed independently for the understanding and the optimization of such processes [10,16-19]. Also, model mixtures can be used in parallel with real samples. For example, the comparison of thermal degradation products from real municipal waste plastic and model mixed plastics can help understand the compounds generated in waste incinerators. In one such study [20], analytical pyrolysis of real municipal plastic waste obtained from Sapporo, Japan and model mixed plastics was carried out at 430 °C in atmospheric pressure by batch operation. The chlorinated hydrocarbons found in degradation liquid products of poly(ethylene)/poly(propylene)/ poly(styrene)/poly(vinyl chloride) and other polymeric mixtures were monitored. It was determined that the presence of poly(ethylene terephthalate), in addition to chlorinated plastics in the waste, facilitates... 

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