Hydrotreating and Selective Oxidation for High Cetane Diesel from FCC LCO
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Solution Overview
Problem
Low value high aromatic middle distillate range streams from cracker units, such as Light Cycle Oil, are underutilized due to high sulfur, nitrogen, and aromatic content, making them inefficient for diesel pool blending and requiring excessive hydrogen for hydrotreating, while hydrocracking increases naphtha generation and reduces VGO throughput, and existing processes fail to enhance cetane number to Euro-III/IV/V diesel standards.
Innovation Solution
An integrated process involving hydrotreating, hydrocracking, and selective oxidation of diesel cut to saturate and open aromatic rings, followed by separation into distinct cuts and further oxidation to enhance cetane number, producing high octane gasoline, high aromatic naphtha, and high cetane diesel with improved cetane number.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hydrotreating is used to remove sulfur from high aromatic middle distillate streams, then sulfur content is reduced, but cetane number remains below diesel specification and hydrogen consumption is excessive
Solution Approach 1:
The process segments the treatment into two distinct stages: first hydrotreating to remove sulfur and nitrogen, then hydrocracking to improve cetane number. This segmentation allows each process to optimize for its specific function without compromising the other, resolving the contradiction between sulfur removal and cetane improvement.
Solution Approach 2:
The process maintains continuous useful action by feeding the hydrotreated effluent directly into the hydrocracker, ensuring that the stream undergoes both sulfur removal and cetane improvement in sequence. This continuous processing eliminates the need for separate treatment trains and ensures both specifications are met.
2Productivity
If conventional hydrocracking is used to improve diesel yield from high aromatic streams, then diesel yield increases, but naphtha generation increases substantially and VGO throughput is reduced
Solution Approach 1:
The process applies local quality by using a hydrocracker specifically configured for high aromatic streams with adjusted operating conditions (lower temperature, optimized catalyst) that favor diesel production over naphtha generation. This localized optimization of the hydrocracking process resolves the contradiction between diesel yield and naphtha generation.
3Productivity
If high pressure hydrocracking is used to process high aromatic streams, then diesel yield improves, but hydrogen consumption increases and process complexity increases
Solution Approach 1:
The process applies partial action by using moderate pressure hydrocracking rather than high pressure, achieving sufficient diesel yield without excessive hydrogen consumption. The hydrocracker operates at optimized pressure levels that balance diesel production with hydrogen efficiency, resolving the contradiction between productivity and energy consumption.
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 upgrades low value streams into high value products with octane values of at least 84 for gasoline, aromatic naphtha of at least 90, and cetane number of at least 42 for diesel, utilizing hydrogen efficiently and maximizing the potential of aromatic streams.
Implementation Method 1
subjecting a feed to hydrotreating step at a predetermined pressure to obtain a first effluent having a substantially reduced quantity of hetero-atoms compared to the feed
Implementation Method 2
subjecting the first effluent to a hydrocracking step at the predetermined pressure to obtain a second effluent, the hydrocracking step resulting in selective opening of at least one saturated ring of the multi-ring aromatics
Implementation Method 3
subjecting at least a part of the CUT-3 to a selective oxidation step to in presence of catalyst, an oxidizing agent to obtain diesel range product with enhanced cetane number
Data Source
AI summary
An integrated process for production of ultra low sulfur products of high octane gasoline, high aromatic naphtha and high Cetane Diesel from high aromatic middle distillate range streams from any cracker units such as Light Cycle Oil (LCO) stream of Fluid catalytic cracking (FCC) units and subjected to hydrotreating for removal of heteroatoms like sulfur and nitrogen. The effluent from hydrotreating is subjected to hydrocracking at same pressure of hydrotreating step above for selective opening of saturated ring of multi-ring aromatics. The effluent from hydrocracking is separated in CUT-1, CUT 2 in which the monoaromatics and alkylated monoaromatics are concentrated and CUT-3 in which concentration of saturates significantly increased. The CUT-3 is selectively oxidized in selective oxidation step in presence of catalyst, an oxidizing agent and operating conditions such that it results in diesel product with more enhanced Cetane.