Hydrocracking Recycle Stream HPNA Removal via Oxidation
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Solution Overview
Problem
Current hydrocracking processes face inefficiencies due to the formation of heavy poly-nuclear aromatic (HPNA) compounds, which accumulate in recycle streams, leading to equipment fouling and reduced catalyst lifespan, and existing methods for removing these compounds are either costly or less effective.
Innovation Solution
A process involving the use of an oxidation agent to convert HPNA and HPNA precursor compounds into aromatic oxides, which are then separated from the hydrocracked bottoms fraction, allowing for their removal and recycling of the reduced HPNA portion, thereby reducing fouling and extending catalyst life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrocracking processes are used to process heavy feedstocks, then higher economic value products are produced, but heavy poly nuclear aromatic (HPNA) compounds accumulate in recycle streams causing equipment fouling and catalyst deactivation
Solution Approach 1:
The patent applies preliminary action by oxidizing HPNA compounds in the recycle stream before they enter the hydrocracker. This pre-treatment step converts HPNA into more oxygenated compounds that are less harmful to the catalyst, preventing catalyst deactivation before it occurs during the main hydrocracking process.
Solution Approach 2:
The patent extracts harmful HPNA compounds from the recycle stream through an oxidation step. By removing these problematic compounds through chemical transformation and separation, the system prevents them from accumulating and causing equipment fouling and catalyst deactivation in the hydrocracker.
2Productivity
If higher operating temperatures and pressures are used to process feedstocks with impurities, then conversion efficiency improves, but energy consumption and operational costs increase
Solution Approach 1:
The oxidation of HPNA compounds in the recycle stream is a preliminary action that reduces the burden on the main hydrocracking process. By pre-treating the recycle stream to remove harmful compounds, the system can operate at lower temperatures and pressures while maintaining high conversion rates, thus reducing energy consumption.
3Reliability
If conventional methods are used to remove HPNA compounds, then equipment fouling is reduced, but the methods are either costly or less effective
Solution Approach 1:
The patent uses strong oxidants to accelerate the oxidation of HPNA compounds in the recycle stream. This approach is more effective than conventional removal methods and can be implemented using readily available oxidation agents, providing a cost-effective solution that significantly reduces equipment fouling while maintaining operational reliability.
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 method enhances the efficiency of hydrocracking operations by effectively removing HPNA compounds, improving catalyst lifespan, and maintaining process efficiency while reducing operational costs.
Implementation Method 1
contacting the hydrocracked bottoms fraction with an effective quantity of an oxidation agent to promote reaction with HPNA and/or HPNA precursor compounds to produce corresponding aromatic oxides
Data Source
AI summary
Hydrocracked bottoms fractions are treated to separate HPNA compounds and/or HPNA precursor compounds and produce a reduced-HPNA hydrocracked bottoms fraction effective for recycle, in a configuration of a single-stage hydrocracking reactor, series-flow once through hydrocracking operation, or two-stage hydrocracking operation. A process for separation of HPNA and/or HPNA precursor compounds from a hydrocracked bottoms fraction of a hydroprocessing reaction effluent comprises contacting the hydrocracked bottoms fraction with an effective quantity of a oxidizing agent to produce corresponding oxidized HPNA compounds and/or oxidized HPNA precursor compounds, and to form an oxidized hydrocracked bottoms fraction. The oxidized hydrocracked bottoms fraction is separated into an HPNA-reduced hydrocracked bottoms portion and an oxidized HPNA portion. All or a portion of the HPNA-reduced hydrocracked bottoms portion is recycled within the hydrocracking operation.