De-aromatized Distillate Production via Segmented Hydrotreating
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Solution Overview
Problem
The production of de-aromatized distillates with benzene content less than 1 ppmw from refinery streams is challenging due to varying aromatic content and sulphur levels, especially in the presence of high boiling ranges and stringent product specifications.
Innovation Solution
A process involving hydrotreating catalysts under hydrogen in a reactor system, followed by flashing and separation in high and low-pressure separators, hydrogenation, and fractionation to achieve benzene content below 1 ppmw in de-aromatized distillates, allowing for the use of any refinery stream with a boiling range of 90-350°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional hydrotreating processes are used on refinery streams with high aromatic content (7-40 wt%), then the process can handle various feedstocks, but the benzene content in the product cannot be reduced below 1 ppmw
Solution Approach 1:
The process segments the hydrotreating operation into two distinct stages: a first hydrotreating reactor for bulk aromatic removal and a second hydrotreating reactor specifically targeted at benzene removal. This segmentation allows each reactor to be optimized for its specific function, enabling benzene content reduction below 1 ppmw while maintaining the ability to process various refinery streams with different aromatic contents
Solution Approach 2:
The first hydrotreating reactor performs preliminary aromatic removal, reducing the aromatic content from 7-40 wt% to lower levels before the feed enters the second reactor. This preliminary action prepares the feedstock for the second reactor, making the subsequent benzene removal more efficient and enabling the final product to achieve benzene content below 1 ppmw
2Manufacturing precision
If low sulphur feedstocks are used to meet product specifications, then the aromatic content can be reduced effectively, but the feedstock selection becomes restricted and pretreatment is required
Solution Approach 1:
The dual-reactor hydrotreating system performs self-service by handling both high sulphur and high aromatic feedstocks without requiring external pretreatment. The first reactor is designed to tolerate and process sulphur-containing feeds, converting them to H2S while removing bulk aromatics, thereby eliminating the need for separate feedstock pretreatment units and allowing direct processing of various refinery streams
3Adaptability or versatility
If high aromatic content refinery streams are processed, then feedstock versatility is maintained, but achieving benzene content below 1 ppmw becomes increasingly difficult
Solution Approach 1:
The process utilizes parameter changes by operating the two hydrotreating reactors at different conditions optimized for their respective functions. The first reactor operates with parameters optimized for bulk aromatic removal and sulphur tolerance, while the second reactor operates with parameters specifically optimized for benzene removal. This parameter differentiation enables the system to process high aromatic content streams (7-40 wt%) while achieving benzene content below 1 ppmw in the final product
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 process effectively reduces benzene content to below 1 ppmw and adjusts aromatic content according to product specifications, enabling the production of de-aromatized distillates suitable for various applications without requiring pretreatment of the feedstock.
Implementation Method 1
treating hydrocarbon feedstock over hydrotreating catalyst under hydrogen, in a hydrotreating reactor system (Reactor-1) for converting hetero-atom contaminants into their respective hydrides
Implementation Method 2
flashing the effluent from Reactor-1 in high pressure separator (HPS), followed by withdrawing of off-gas containing un-reacted hydrogen along with inorganic and hydrocarbons compounds from the top of HPS
Implementation Method 3
flashing the liquid hydrocarbon effluent in low pressure separator (LPS) to remove dissolved gases and lighter hydrocarbon fraction
Implementation Method 4
processing LPS effluent in splitter and separating it into two fractions: i) a top fraction consisting of a hydrocarbon stream having a boiling temperature of 70-140° C., wherein said fraction is condensed and collected in a reflux drum, and ii) a bottom cut fraction consisting of a hydrocarbon stream having a boiling temperature of 140° C.-340° C.
Implementation Method 5
hydrogenating the bottom cut fraction in Reactor-2 over hydrotreating catalyst under hydrogen
Implementation Method 6
fractionating effluent from step g) containing hydrocarbon stream having boiling range between 120-340° C. into narrow cuts in a fractionator to obtain de-aromatized distillates with required boiling range and flash point
Data Source
AI summary
A process for the production of ultralow aromatic specialty distillate from different refinery streams particularly high sulfur streams. The process produces de-aromatized distillates with benzene content below 1 ppmw. Hydrocarbon feedstock having boiling temperature in the range of 90 and 350° C., preferably 140 and 320° C. The hydrocarbon feedstocks are obtained from any petroleum-refinery or bio-refinery or any other source producing hydrocarbon streams.