Pyrolysis Stream Recovery Without Reboiler
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Solution Overview
Problem
Current pyrolysis processes for recycling waste plastics do not produce liquid hydrocarbon products of sufficient yield and quality to be directly fed into chemical cracking furnaces for producing value-adding chemicals like ethylene and propylene.
Innovation Solution
A process involving preheating a pyrolysis stream to 380° C. to 480° C., followed by distillation in a column without a reboiler, cooling in a condenser, and refluxing in a reflux vessel to recover liquid naphtha or naphtha-like products, diesel, and heavy oil, with a system comprising a preheater, distillation column, condenser, and reflux vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional pyrolysis processes are used to convert waste plastics to liquid hydrocarbons, then plastic waste can be recovered and recycled, but the yield and quality of liquid products are insufficient for direct feeding into chemical cracking furnaces
Solution Approach 1:
The patent applies parameter changes by preheating the pyrolysis stream to a specific temperature range (380-480°C) before distillation, and by controlling the distillation process to produce fractions with specific boiling point ranges. These parameter adjustments transform the low-quality pyrolysis output into high-quality liquid products suitable for chemical cracking furnaces, resolving the contradiction between product quality and yield.
2Manufacturing precision
If the pyrolysis stream is directly processed without preheating and distillation, then the process is simpler, but the liquid product quality and yield are insufficient
Solution Approach 1:
The patent segments the pyrolysis stream into different fractions through distillation, separating light ends, naphtha-range liquids, and heavy residues. This segmentation allows each fraction to be processed and recovered separately, improving overall product quality while managing system complexity through structured separation stages.
Solution Approach 2:
The patent applies preliminary action by preheating the pyrolysis stream to 380-480°C before distillation. This preheating step prepares the feedstock for efficient distillation and fractionation, ensuring that the subsequent separation processes operate at optimal conditions, thereby improving product quality without excessively increasing system complexity.
3Device complexity
If heavy-cut liquid products are processed without special treatment, then the process is simpler, but fouling tendencies increase
Solution Approach 1:
The patent extracts heavy-cut liquid products as a separate fraction from the distillation column bottom. By isolating this fraction and routing it through dedicated processing equipment, the system prevents fouling in the main processing line while maintaining overall process simplicity. The heavy fraction is handled separately where appropriate precautions can be taken.
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
This process significantly increases the yield and quality of recovered liquid hydrocarbon products, enabling their use in chemical cracking furnaces to produce value-adding chemicals, while reducing fouling tendencies in heavy-cut-liquid-product processing.
Implementation Method 1
preheating a pyrolysis stream to a temperature ranging from about 380° C. to about 480° C.
Implementation Method 2
distilling the preheated pyrolysis stream in a distillation column to produce one or more streams
Implementation Method 3
cooling the top stream withdrawn from the distillation column in a condenser
Implementation Method 4
refluxing the cooled stream (i.e., the stream that has exited the condenser) in a reflux vessel
Data Source
AI summary
This invention relates to a process for recovering a liquid product from a pyrolysis stream. The process comprises preheating a pyrolysis stream comprising a mixture of hydrocarbons; distilling the preheated pyrolysis stream in a distillation column to produce one or more streams including a top stream at the top of the distillation column; cooling the top stream withdrawn from the distillation column in a condenser; refluxing the stream that has exited the condenser in a reflux vessel; and withdrawing at least part of a liquid product from the bottom of the reflux vessel to recover a liquid naphtha or naphtha-like product. The invention also relates to various recovered liquid products produced from the process described herein. The invention also relates to an apparatus for recovering liquid products from a pyrolysis stream, comprising a preheater; a distillation column that does not contain a reboiler; a condenser; and a reflux vessel.