Two-Stage Hydrocracking for Low Nitrogen Middle Distillates and FCC Feedstock
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current two-stage hydrocracking processes require high severity operations to reduce nitrogen and sulfur content in heavy hydrocarbon feedstocks, leading to shorter catalyst lifetimes, increased hydrogen consumption, and higher construction and operating costs, while also producing HVGO that is over-processed for fluidized catalytic cracking units.
Innovation Solution
A refining process that includes hydrotreating and hydrocracking stages with optimized catalysts and operating conditions to produce middle distillates with reduced nitrogen and sulfur content, allowing for a 900°F+ HVGO stream suitable for fluidized catalytic cracking units, while minimizing hydrogen use and operating severity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high severity hydrocracking operations are used to reduce nitrogen and sulfur content, then product quality improves, but catalyst lifetime decreases
Solution Approach 1:
The hydrocracking process is divided into two distinct stages: a first stage hydrocracker operating at high severity to achieve maximum nitrogen and sulfur removal, and a second stage hydrocracker operating at lower severity to finish conversion. This segmentation allows the first stage catalyst to handle the harsh conditions and poisoning effects, while the second stage catalyst operates in a more favorable environment, extending overall catalyst lifetime while achieving the required product quality specifications.
2Productivity
If high severity hydrocracking operations are used, then conversion rate improves, but hydrogen consumption increases
Solution Approach 1:
The first stage hydrocracker operates at high severity with excessive hydrogen consumption to achieve rapid initial conversion and remove the majority of nitrogen and sulfur. The second stage hydrocracker then operates at lower severity with reduced hydrogen consumption to complete the conversion. This partial action approach optimizes the overall hydrogen efficiency by concentrating the high hydrogen demand in the first stage where it is most effective, while reducing hydrogen usage in the second stage where less severe conditions suffice.
3Manufacturing precision
If high severity operations are used, then product quality improves, but operating costs increase
Solution Approach 1:
The two-stage hydrocracking configuration segments the severe operating conditions to only the first stage, allowing the second stage to operate under more economical conditions. This reduces overall operating costs compared to running a single stage at high severity, while still achieving the required product quality. The segmentation also allows for more flexible equipment design and operation, potentially reducing construction costs.
4Productivity
If heavy hydrocracking conversion is achieved, then middle distillate yield improves, but HVGO quality for FCC feedstock deteriorates
Solution Approach 1:
The process extracts the heavy hydrocracking conversion function primarily in the first stage, allowing the second stage to operate at lower conversion rates. This extraction approach produces the required middle distillate yield while preventing over-processing of the HVGO stream. The HVGO from the second stage retains appropriate quality characteristics for FCC feedstock because the severe conversion conditions are concentrated in the first stage rather than applied continuously.
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 extends catalyst life, reduces hydrogen consumption, and lowers construction and operating costs by producing higher-quality middle distillates and HVGO, with the HVGO being only minimally processed to meet FCC unit specifications, thus avoiding over-saturation and prolonging catalyst life.
Implementation Method 1
catalytic hydroprocessing refers to petroleum refining processes in which a carbonaceous feedstock is brought into contact with hydrogen and a catalyst, at a higher temperature and pressure, for the purpose of removing undesirable impurities
Implementation Method 2
catalytic hydroprocessing refers to petroleum refining processes in which a carbonaceous feedstock is brought into contact with hydrogen and a catalyst
Implementation Method 3
atmospheric distillation of the hydrocracked first stage effluent in a distillation column
Data Source
AI summary
The present invention is directed to a refining process for producing hydroprocessed distillates and a heavy vacuum gas oil (HVGO). The process produces middle distillates that have reduced nitrogen and sulfur content, while simultaneously producing a 900° F.+ (482° C.+) HVGO stream useful as a fluidized catalytic cracking (FCC) unit feedstock.