Absîract. Liquid Phase Hydrogenation meets the requirement of a process for the utilization of post consumer plastics which is insensitive to chlorine and inert impurities. The product obtained is of high quality and can directly be used as a feedstock for petrochemical processes.
The paper will report on a hydrogenation plant operated by Veba Oe1 AG with a capacity of 200000 tons per year. A quarter of the capacity is used for the conversion of plastics, the remaining for vacuum residue. The plant employs a new developed 'depolymerizer ', in which the post consumer plastics are liquefied so that these can easily be pumped after being blended with the vacuum residue.
Experience generated during the first year of operation and plans to increase the capacity for plastic will be presented. Design features for a new plant including cost estimates will show whether other refineries can apply this technology and use post consumer plastic as a feedstock.
BASICS Wastes containing hydrocarbons are considered to be an environmental problem of increasing significance. At the same time these wastes represent a source to be used as refinery feedstock after adequate pretreatment.
Marketing of heavy fuel oil becomes increasingly difficult in Europe due to restrictive emission limitations to come into force shortly. The main source for heavy fuel oil are vacuum bottoms of crude oils.
The process of liquid phase hydrogenation called Veba-Combi-Cracking (VCC) is capable of converting these residues into high quality distillates achieving high liquid yields. The process can as well be used to convert different kinds of waste material like used lubes, degreasing oils, used solvents and particularly mixed plastic wastes (MPW) in a commingled way of operation.
Hydrogenation in the liquid phase mode takes place at temperatures of 450°C to 490°C and hydrogen partial pressures of 150 to 250 bar. Under these conditions large molecules are cracked, hydrogen is added to the cracked organic bonds and Sulfur, chlorine, nitrogen, etc. after being separated are transferred to their corresponding hydrogen containing components which can be recovered.
Liquid phase hydrogenation is insensitive to solid inerts, which can be separated during hydrogenation by special measures. The main objective of the process is to convert organic materials like coal, bitumen or difficult to handle organic wastes into valuable clean hydrocarbon products.
The cracking process starts at the relatively weak bonds of the molecules. The bond strength decreases from carbon/carbon over sulfur/carbon and nitrogen/carbon to chlorine/carbon bonds. The decontamination of used so