Steam Cracker Naphtha Hydroprocessing to Reduce Fractionator Fouling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Steam cracker fractionators experience fouling due to increased amounts of foulant precursors in the steam cracker feed, leading to decreased efficiency and increased naphtha mass density, which complicates the separation process and requires costly antifouling agents and complex feed system modifications.
Innovation Solution
A steam cracking process where a portion of the steam cracker naphtha is subjected to mild hydroprocessing to dimerize and hydrogenate hydrocarbons, reducing foulant accumulation by reintroducing the hydroprocessed stream as reflux into the fractionator, thereby lessening foulant precursors and fractionator fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If increased amounts of C4- hydrocarbon molecules are added to the steam cracker feed to produce more light olefin, then the yield of light olefin is improved, but the fractionator fouling increases due to increased foulant precursors
Solution Approach 1:
The patent applies preliminary action by hydroprocessing the steam cracker naphtha stream before it enters the fractionator. This pre-treatment removes foulant precursors (such as diolefins and aromatics) from the naphtha stream through hydroprocessing conditions (temperature: 250-450°C, pressure: 50-200 psig, with hydrogen and catalyst), preventing fouling before it occurs in the fractionator while still allowing increased C4- hydrocarbon feed to produce more light olefin.
Solution Approach 2:
The patent extracts the harmful foulant precursors from the steam cracker naphtha stream by conducting a hydroprocessing step that selectively removes diolefins, aromatics, and other foulant-forming compounds. This extracted naphtha stream is then free of the precursors that would otherwise cause fractionator fouling, allowing the beneficial increase in light olefin production to proceed without the fouling penalty.
2Object-affected harmful factors
If conventional methods using antifouling agents are used to prevent fractionator fouling, then the fouling is reduced, but the process complexity and cost increase
Solution Approach 1:
The patent applies self-service by using the steam cracker naphtha stream itself as the source of foulant removal. The naphtha is hydroprocessed to remove its own foulant precursors (diolefins, aromatics) that would cause fractionator fouling. This self-cleaning approach eliminates the need for external antifouling agents and complex feed system modifications, reducing process complexity while effectively preventing fouling.
3Object-affected harmful factors
If the steam cracker feed is modified to reduce foulant precursors, then the fractionator fouling is decreased, but the light olefin production is reduced
Solution Approach 1:
The patent applies segmentation by dividing the steam cracker effluent into separate streams: a light olefin stream (C2-C4 olefins) that is maintained at high concentration for maximum productivity, and a naphtha stream (C5-C12 hydrocarbons) that is hydroprocessed to remove foulant precursors. This segmentation allows the light olefin production to proceed at high levels while the naphtha stream is cleaned to prevent fractionator fouling, resolving the contradiction between productivity and fouling reduction.
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 decreases foulant accumulation and fractionator fouling, improving separation efficiency without the need for antifouling agents or complex feed system modifications, by altering the molecular weight distribution and reducing diolefin content in the reflux stream.
Implementation Method 1
The steam cracker effluent is cooled to condense at least a portion of the vapor phase into a liquid phase
Implementation Method 2
at least a portion of the steam cracker effluent's vapor phase is separated from the liquid phase in at least one fractionator
Implementation Method 3
The rectification region concentrates into the vapor phase those components of the steam cracker effluent having greater volatility, e.g., SCN and light olefin. The stripping region concentrates into the liquid phase those components of the steam cracker effluent having lesser volatility
Implementation Method 4
mild hydroprocessing to dimerize and hydrogenate hydrocarbons
Implementation Method 5
mild hydroprocessing to dimerize and hydrogenate hydrocarbons, reducing foulant accumulation
Data Source
AI summary
The invention generally relates to processes for separating steam cracker products by fractional distillation, and to systems and apparatus useful in such processes. More specifically, the invention relates to decreasing the amount of fractionator fouling that can result from increasing the amount of hydrocarbon molecules in the steam cracker feed having four or fewer carbon atoms.