Co-processing Light Cycle Oil and Heavy Naphtha for Aromatic Yield
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Solution Overview
Problem
Current LCO hydrocracking processes face challenges in maximizing the production of aromatics due to regulatory limits on aromatic content and the reluctance to process naphtha, which is believed to crack down to less valuable lighter hydrocarbons, limiting the yield of valuable xylenes and other aromatics.
Innovation Solution
A process that co-processes a naphtha stream with LCO in a hydroprocessing reactor, where the LCO stream is hydrocracked and the naphtha stream is hydrotreated, then both streams are fractionated to produce a high-concentration aromatic naphtha product, reducing hydrogen consumption and minimizing cracking of naphtha to lighter compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If naphtha is processed in a hydrocracking unit, then the production of aromatics can be increased, but naphtha cracks down to lighter, less valuable LPG and dry gas
Solution Approach 1:
The patent combines naphtha and LCO feeds into a single hydroprocessing reactor, allowing simultaneous processing. The naphtha is hydrotreated while LCO is hydrocracked, and the reactions occur in the same reactor environment. This merging enables the naphtha to benefit from the hydroprocessing conditions without excessive cracking, while LCO provides the desired aromatic production. The combined feed approach allows the naphtha to be processed under conditions that preserve it rather than cracking it to lighter gases.
2Ease of operation
If FCC heavy naphtha is routed to gasoline pool, then it can be used as fuel, but aromatic content exceeds regulatory limits
Solution Approach 1:
The patent changes the chemical parameters of the heavy naphtha by subjecting it to hydroprocessing conditions in the reactor. Through hydrotreating reactions, the aromatic content is reduced and the composition is modified to meet regulatory specifications. This parameter change allows the naphtha to transition from being unsuitable for gasoline blending (due to high aromatics) to suitable for blending (after hydroprocessing reduces aromatic content).
3Productivity
If LCO is hydrocracked separately from naphtha, then aromatics can be produced, but hydrogen consumption increases
Solution Approach 1:
The patent merges the processing of naphtha and LCO in a single reactor system, allowing shared hydrogen consumption. The naphtha hydrotreating and LCO hydrocracking occur simultaneously, and the hydrogen required for both processes is supplied together. This combined approach optimizes hydrogen utilization efficiency compared to separate processing, as the hydrogen can serve dual purposes and the reactor conditions can be optimized for the combined feed composition.
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 approach increases the yield of high-aromatic naphtha, reduces hydrogen consumption, and produces a rich intermediate naphtha product with cyclic compounds, optimizing petrochemical production while adhering to regulatory aromatic content limits.
Implementation Method 1
hydrocracking the LCO stream under hydrocracking conditions to provide a hydrocracked effluent stream
Implementation Method 2
hydrotreating the naphtha stream under hydrotreating conditions to provide a hydrotreated effluent stream
Implementation Method 3
The hydrocracked effluent stream and the hydrotreated effluent stream are passed to a main fractionation column to recover a desired naphtha product
Data Source
AI summary
Processes for co-processing a naphtha stream with a light cycle oil stream are disclosed. The processes include hydrocracking the light cycle oil stream under hydrocracking conditions to provide a hydrocracked effluent stream. A naphtha stream is hydrotreated under hydrotreating conditions to provide a hydrotreated effluent stream. The hydrocracked effluent stream and the hydrotreated effluent stream may be passed to a stripping column to recover a stripping bottom stream. The stripping bottom stream may be passed to a main fractionation column to recover an intermediate naphtha stream.