Integrated Pyrolysis Oil Hydroprocessing for Impurity Control
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Solution Overview
Problem
Plastics and solid recovery fuel pyrolysis oils contain high levels of impurities such as diolefins, metals, and halogenated compounds, which cause corrosion, coking, and catalytic deactivation in steam cracking units, leading to operational inefficiencies and reduced yields of light olefins.
Innovation Solution
An integrated process involving selective hydrogenation, hydroconversion in ebullated, entrained, or moving beds, followed by fixed-bed hydrotreatment and optional hydrocracking, without intermediate separation, to purify and upgrade the pyrolysis oils, allowing continuous catalyst addition and removal without unit shutdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pyrolysis oil is used as feedstock for steam cracking unit, then light olefins can be produced, but impurities cause corrosion, coking and catalytic deactivation
Solution Approach 1:
The patent applies preliminary action by implementing a hydrotreatment step before steam cracking to remove impurities (diolefins, metals, halogenated compounds) from pyrolysis oil. This preprocessing eliminates harmful substances that would cause corrosion, coking, and catalytic deactivation in the steam cracking unit, ensuring reliable operation while maintaining light olefin production
Solution Approach 2:
The patent converts harmful impurities into beneficial outcomes through hydrotreatment. Diolefins are hydrogenated to stable alkanes, metals are removed via hydrodemetallization, and halogenated compounds are decomposed. This transforms substances that would cause operational problems into harmless or beneficial components, enabling reliable steam cracking
2Reliability
If fixed-bed hydrotreatment is used, then impurity removal is effective, but catalyst deactivation requires unit shutdown
Solution Approach 1:
The patent applies dynamics by transitioning from a static fixed-bed reactor to a moving-bed reactor for the hydrotreatment step. In the moving-bed configuration, the catalyst continuously moves through the reactor, allowing spent catalyst to be replaced with fresh catalyst without shutting down the unit. This dynamic approach maintains impurity removal efficiency while eliminating production losses from shutdowns
Solution Approach 2:
The patent ensures continuity of useful action by implementing a moving-bed hydrotreatment process where catalyst regeneration and replacement occur continuously without interrupting the pyrolysis oil treatment. The useful action of impurity removal continues uninterrupted, maintaining both reliability and productivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process effectively removes impurities, reduces clogging and corrosion risks, extends catalyst cycle times, and enhances the production of light olefins suitable for steam cracking, improving the efficiency and yield of the pyrolysis oil treatment.
Implementation Method 1
a) selective hydrogenation of said feedstock in the presence of hydrogen and of a selective hydrogenation catalyst to obtain a hydrogenated effluent
Implementation Method 2
b) fixed-bed hydrotreatment of said hydrogenated effluent in the presence of hydrogen and of a hydrotreatment catalyst, to obtain a hydrotreatment effluent
Implementation Method 3
b) hydroconversion of said feedstock or of said hydrogenated effluent obtained from step a) in an ebullated-bed reactor, in an entrained-bed reactor and/or in a moving-bed reactor
Implementation Method 4
c) separation of the hydrotreatment effluent in the presence of an aqueous stream, at a temperature of between 50 and 370° C., to obtain a gaseous effluent, an aqueous liquid effluent and a liquid hydrocarbon effluent
Data Source
AI summary
The invention relates to a process for treating a plastics and/or solid recovery fuel pyrolysis oil, comprising:a) optionally, selective hydrogenation of the feedstock;b) hydroconversion in an ebullated bed, in an entrained bed and/or in a moving bed, to obtain a hydroconverted effluent;c) hydrotreatment of said hydroconverted effluent from step b) to obtain a hydrotreated effluent, without any intermediate separation step between steps b) and c),c′) optionally, hydrocracking of said effluent from step c),c) separation of the effluent from step c) or c′) in the presence of an aqueous stream, to obtain a gaseous effluent, an aqueous liquid effluent and a liquid hydrocarbon effluent;d) optionally a fractionation to obtain at least one gas stream and one cut with a boiling point of less than or equal to 175° C. and one cut with a boiling point of greater than 175° C.