Plastic wastes refinery processing

Furthermore, a study of the behaviour of a fluidized-bed reactor is very important as one of the options for a possible commercialization of such a pyrolysis recycle process is to co-feed plastic waste into the FCC cracker unit of an oil refinery. Studies of plastic being a fraction of the feed of a cracking process have been carried out by Ng et al. [7] and Arandes et al. [12, 27, 28]. They not only showed the applicability of the method, but discovered a synergetic effect on the cracking of the oil decreasing the amount of aromatics. 

In particular, as far as the plastic catalytic degradation is concerned, there are various possible scenarios. In large urban areas the best approach probably is to build a plastic waste pyrolysis plant in an acceptable near area at not to great distance, in order to minimize transport cost of the plastic waste. In that case, safety and environmental concerns of such a new plant should first be denied with satisfactorily before the new plant can get the go-ahead. Near refineries however, the best approach might be to co-feed plastic waste with oil fractions into refinery crackers, or even have a unit of pure thermal pyrolysis first with the produced wax-type fraction to be upstaged in another reactive refinery process. In the first case of co-feeding, a lot of research has to be carried out, addressing aspects of defluidization mainly, before an alteration of a process of the scale of FCC units can go ahead. 

Several petrochemical companies have considered the possible feedstock recycling of plastic wastes in existing refinery facilities, which would avoid the need to invest and build new processing plants.19-21 This alternative is based on the similarity of elementary composition between plastics and petroleum fractions. Moreover, taking into account the differences in production between plastics and the total of petroleum-derived products, plastic wastes could be incorpo-... 

Figure 1.13 Processing of plastic wastes in refinery units.19 VVA pre-treated mixed plastic scrap AR residue from the atmospheric distillation process VR vacuum distillation residue VisR visbreaker residue VVR vacuum visbreaker residue.

The possible thermal processing of plastic wastes directly in refinery units is also an alternative that has been considered by some companies.112,113 In this case, the plastic wastes must be dissolved and mixed, generally in low proportions, with petroleum fractions. For this approach to be feasible the most important criterion is that the addition of the plastic wastes must not lead to any significant variation in the process parameters of the refinery unit. The... 

Liquid fuels can be produced by carbon hydrogenation. Plastics waste is ground into small pieces and introduced into a reactor where it is depolymerised by heat at high pressure in an excess of hydrogen [52]. The result is a high-quality petrochemical feedstock that can be cracked into saturated hydrocarbons and syncrude. This is in turn is used in the synthesis of new polymer. The advantage with this process is the ease of separation of side products such as heavy metals, sulphur and chloride. Furthermore existing oil refinery units, such as thermal... 

Thermal recycling of plastics waste can be carried out by pyrolysis or various refinery processes. Specific examples of thermal recycling processes include ... 

The Hamburg University process is a low temperature fluidized bed pyrolysis system meant for pyrolysis of plastics waste. The original objective of the process was the production from plastics waste of a gas with high heating value and liquid hydrocarbons containing mainly benzene, toluene and xylene. Production of olefins from plastics waste with high content of polyolefins and use of these olefins as feedstock in the refinery processes was also considered. The schematic of the process is shown in... 

Recycling of Plastics Waste Through Refinery Processes... 

A 20ft-high mini plant has been built at BP s refinery at Grangemouth, near Edinburgh, as an experiment by several leading European petrochemical companies to address the difficult issue of plastic recycling. The 7501/ y pilot plant accepts mixed plastics ground into pieces a maximum of 2cm across and passes them over hot sand which converts them into a gas. This is distilled back into plastic feedstock which can be fed back into the petroehemical plant to make fresh plastic. This process eould be replieated at many small plants, located at ehemieal works or even beside municipal waste tips. 

Coprocessing of waste plastics with heavy petroleum fractions have considerable interest in feedstock recycling. In this study, we aimed to investigate the processing of municipal waste plastics (MWP) in presence of conventional and non-conventional catalysts in a refinery stream. For this purpose, the hydrocracking of MWP in vacuum gas oil (VGO) over metal loaded active carbon and conventional acidic catalysts (HSZM-5, DHC-8) was carried out to obtain liquid fuel. 2 refs. 

Large amounts of nitrosamines leak into the environment from the pharmaceutical and food industries, plastics industry, textile industry, waste transport (motor vehicles), industrial effluents (dyes, lubricants, mbber), and the production of solvents. Fuel manufacturing plants and oil refineries are also important emitters of nitrosamines, as well as landfills and fossil fuel combustion processes (to produce heat and power). These compounds naturally penetrate the environment through animal droppings. 

Gebauer et al. [38] suggest visbreaking of waste plastics with vacuum residue. This is a thermal process, applied in refineries in order to convert partially atmospheric vacuum residue and decrease viscosity and melting temperature. According to the authors, addition of 5% of waste plastics in laboratory tests does not influence noticeably the process parameters and final products properties. As in the case of LCO and VGO fractions the application of vacuum residue and mixture of waste plastics is applicable in refineries. 

The liquid product obtained from thermal cracking can be either catalytically cracked/ hydrocracked or co-processed with a refinery feed. Since the catalytic cracking of oil derived from MWP is more or less problematic, any cracking catalyst can be applied to oil derived from pyrolysis of plastics. But the yield and the quality of gasohne obtained from cracking step vary with the type of catalyst and the properties of the pyrolytic oil derivated from waste plastics. 

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