Chemistry of hydrocarbon compounds – Production of hydrocarbon mixture from refuse or vegetation – From synthetic resin or rubber
Patent
1998-01-09
1999-10-26
Yildirim, Bekir L.
Chemistry of hydrocarbon compounds
Production of hydrocarbon mixture from refuse or vegetation
From synthetic resin or rubber
585832, 201 25, 201 25, C10G 110, C07C 100
Patent
active
059732172
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for processing recycled or scrap plastics for the purpose of obtaining raw chemical materials and liquid fuel components, by means of depolymerization of the substances being used, at elevated temperature, to produce both a pumpable and a volatile phase, and separation of the volatile phase into a gas phase and a condensate.
2. Description of the Background
In the depolymerization of recycled or scrap plastics, not only melt-viscous depolymerizate, but also a gas phase and a condensate are obtained, and the condensate must be additionally treated with hydrogenation, because of its chlorine content and low stability. With regard to the state of the art, we refer to the PCT application WO 94/22979.
From the aforementioned document, it is evident that the condensable depolymerization products can be subjected to hydrogenating refining on a solid bed catalyst, or also on a moving catalyst, or a bubbling catalyst bed. Such hydrogenating refining represents normal refining processes, which are also referred to as hydrotreating in the technical literature.
The condensates to be subjected to hydrotreating, however, contain non-evaporating components which come from the depolymerizer, because of foaming, spraying, or vapor inclusions, and also those that have been reformed by means of repolymerization, so that direct charging of a catalyst layer arranged in fixed manner in a hydrotreater would result in rapid inactivation of the same, i.e. would result in very high catalyst consumption. In addition, because of the instability of such condensates, coatings would form on heat exchangers, for example pre-heaters, which would prevent sufficiently long times of operation without interruptions. Document WO 94/22979 teaches converting the condensate, for example by hydrotreating it on commercially available Co--Mo or Ni--Mo catalysts arranged in fixed manner, or introducing it directly into chemical, technical or usual refining processes which tolerate chlorine, as a base substance which contains hydrocarbons (syncrude) (see p. 5), where a prior "guard bed" to extend the useful lifetime of the catalyst layer arranged in fixed manner is also taken into consideration (see page 9, line 7, op. cit.).
From the aforementioned state of the art, the technical teaching of a combination of depolymerization, hydrogenating treatment, preferably of distillate components that have been produced, with sump phase hydrogenation, gasification and/or low temperature carbonization can be derived. Here the task of simplifying the process comes up.
A further task is to prevent rapid inactivation of the catalyst charge of the hydrotreating stage.
SUMMARY OF THE INVENTION
Accordingly, with the method indicated at the beginning, the invention consists of the fact that the depolymerizate which remains after separation of the volatile phase is heated, together with the condensate or portions of the condensate, in the presence of hydrogen, under pressure, and after separation of non-volatile components, is subjected to hydrotreating to obtain a syncrude.
DETAILED DESCRIPTION OF THE INVENTION
In this connection, the condensate or the non-volatile fraction of the condensate is heated to above the response temperature of the hydrotreating catalyst, together with the depolymerizate and hydrogen, under pressure.
Here, the process can be carried out in such a way that a sufficient dwell time at an elevated temperature is available in the heating segment, so that further splitting and viscosity reduction of the depolymerizate is achieved.
The process can also be structured in such a way that a dwell-time vessel follows the heating segment. In this way, depolymerization is driven so far that losses due to outward transfer of residues can be kept low.
It is practical if hydrotreating is conducted at the temperature pre-determined by the pre-heater. In this connection, the presence of hydrogen under pressure as well as dilution of the condensate with depolymerizate
REFERENCES:
patent: 4982027 (1991-01-01), Korff et al.
patent: 5061363 (1991-10-01), Farcasiu et al.
patent: 5639937 (1997-06-01), Hover et al.
patent: 5731483 (1998-03-01), Stabel et al.
Hastrich Horst
Hecka Christian
Holighaus Rolf
Niemann Klaus
Strecker Claus
Veba Oel Ag
Yildirim Bekir L.
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