Deep Hydrogenation of FCC Middle Distillates for Steam Cracking
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Solution Overview
Problem
There is a need for improved processes to convert crude oil into light olefins and higher value chemical production opportunities with greater economies of scale, as conventional refineries are primarily designed for producing transportation fuels and face increasing demands for light olefins and rising costs of conventional feedstocks.
Innovation Solution
An integrated process involving deep hydrogenation of hydrotreated middle distillates to produce a feedstock suitable for steam cracking, which is then processed in a Fluid Catalytic Cracking (FCC) unit to generate light olefins, pyrolysis gasoline, and pyrolysis oil, with the products being further refined to recover ethylene, propylene, and butylenes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional refineries produce transportation fuels (gasoline and diesel), then fuel production is optimized, but light olefin production is insufficient and feedstock costs increase
Solution Approach 1:
The patent merges the steam cracking unit with the existing refinery processing system, integrating light olefin production into the conventional fuel production pathway. The steam cracking unit processes middle distillates alongside the existing naphtha processing, combining multiple functions (fuel production and chemical production) into a single integrated system, thereby increasing light olefin productivity while maintaining feedstock flexibility
Solution Approach 2:
The refinery system is designed to handle multiple feedstocks (naphtha, middle distillates, vacuum gas oil) and produce multiple products (gasoline, diesel, and light olefins) through a unified processing architecture. The steam cracking unit can process various feedstocks and the system can operate in different modes (maximizing fuel production or maximizing chemical production), providing universal functionality that resolves the contradiction between specialized fuel production and versatile feedstock utilization
2Productivity
If middle distillates are subjected to deep hydrogenation followed by steam cracking, then light olefin yield is improved, but process complexity increases
Solution Approach 1:
The middle distillates undergo deep hydrogenation as a preliminary treatment step before steam cracking to remove sulfur, nitrogen, and other contaminants that would interfere with the cracking process and reduce light olefin yield. This preliminary action prepares the feedstock in advance, ensuring optimal conditions for the subsequent steam cracking and maximizing light olefin production while maintaining a manageable process sequence
Solution Approach 2:
Hydrogen serves as an intermediary substance in the deep hydrogenation step, facilitating the removal of heteroatoms and impurities from the middle distillates. The hydrogenation process uses hydrogen as a mediator to convert harmful impurities into removable compounds, thereby preparing the feedstock for efficient steam cracking and increasing light olefin yield without directly complicating the cracking mechanism itself
3Ease of manufacture
If conventional feedstocks are used for light olefin production, then production costs increase, but alternative feedstocks require new processing options
Solution Approach 1:
The patent changes the operational parameters of the steam cracking unit to accommodate different feedstocks (middle distillates, vacuum gas oil, coker gas oil) instead of requiring completely new processing equipment. By adjusting temperature, pressure, and residence time parameters, the system can efficiently process various feedstock types at different stages of the refining process, thereby reducing production costs while avoiding the need for entirely new processing options
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 enables the production of light olefins and other petrochemicals efficiently, optimizing capital expenditures and leveraging economies of scale, thereby addressing the demand for higher value chemical production from crude oil conversion.
Implementation Method 1
deep hydrogenation of hydrotreated middle distillates to produce an effluent that is suitable as a feedstock to a steam cracking complex
Implementation Method 2
Thermal cracking, or steam pyrolysis, is a major type of process for forming these materials, typically in the presence of steam, and in the absence of oxygen
Data Source
AI summary
A feedstock is processed in an FCC unit to produce at least light olefins, FCC naphtha, light cycle oil and heavy cycle oil. Light cycle oil, and in certain embodiments hydrotreated light cycle oil, is subjected to deep hydrogenation to produce a deeply hydrogenated middle distillate fraction. All or a portion of the deeply hydrogenated middle distillate fraction is used as feed to the stream cracking zone to produce light olefins.