Hydrocracking Recovery Simplification via Stripping Columns
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Solution Overview
Problem
Current hydrocracking recovery processes are inefficient and require external utilities for heating, leading to high energy consumption and operational costs, particularly in regions with lower diesel demand where distillate hydrocracking is prioritized.
Innovation Solution
A process and apparatus that eliminates the need for a debutanizer column, naphtha splitter column, and sponge absorber column by using a cold stripping column, hot stripping column, deethanizer column, product fractionation column, and a chiller system, which reduces the reliance on external utilities for heating and enhances LPG recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a typical hydrocracking recovery section with six columns including debutanizer, naphtha splitter, and sponge absorber is used, then complete separation and recovery of products is achieved, but device complexity and operational costs increase significantly
Solution Approach 1:
The patent removes the debutanizer column, naphtha splitter column, and sponge absorber column from the traditional six-column configuration. This extraction of unnecessary components simplifies the device while maintaining product separation completeness through the optimized cold and hot stripping columns working in conjunction with the deethanizer and product fractionation columns.
Solution Approach 2:
The patent combines the functions of multiple columns into a more integrated system where the cold stripping column and hot stripping column work together with the deethanizer and product fractionation columns. The cold stripping column operates at lower temperatures to prevent unwanted reactions, while the hot stripping column handles heavier components, creating a merged functional system that replaces multiple separate units.
2Reliability
If external utilities are used to provide heater duty for vaporizing fractionation materials, then fractionation process is maintained, but energy consumption and operational costs increase
Solution Approach 1:
The patent implements a self-service energy system where heat is generated within the hydroprocessing unit itself and used for fractionation purposes. The hot stripping column utilizes hot streams from the hydrocracking process to provide the necessary heater duty for vaporizing fractionation materials, eliminating or reducing the need for external utility heaters and significantly lowering energy consumption.
Solution Approach 2:
The patent recovers heat that would otherwise be discarded from the hydrocracking process and reuses it for fractionation operations. By capturing and utilizing the thermal energy from hot process streams, the system converts waste heat into useful heating duty for the fractionation columns, reducing external energy requirements.
3Productivity
If distillate hydrocracking is performed to produce lighter fuel products, then diesel production is reduced, but lighter products such as naphtha and LPG are increased
Solution Approach 1:
The patent changes the operating parameters of the hydrocracking process to favor the production of lighter fuel products. By adjusting temperature, pressure, catalyst composition, and residence time parameters, the process is optimized to crack distillate into lighter molecules such as naphtha and LPG, shifting the product distribution away from diesel toward lighter fractions.
Solution Approach 2:
The patent applies different catalyst properties and operating conditions in different zones or stages of the hydrocracking process to selectively promote lighter product formation. The catalyst composition and reaction conditions are locally optimized to enhance cracking activity and favor the production of desired lighter fuel products in specific process zones.
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 results in a significant reduction in operational expenses, with a 70% decrease in heater duty and operational costs, while maintaining high LPG recovery efficiency, and allows for the production of C3-C5 LPG and C6-C10 heavy naphtha streams suitable for reforming feeds.
Implementation Method 1
A stripping column strips hydrogen sulfide off of a liquid hydrocracked stream with a steam stream
Implementation Method 2
A liquid overhead stripping stream is fractionated in a deethanizer column whose overhead is sponged along with a vapor stripping overhead stream in an absorber column to produce liquefied petroleum gas (LPG)
Implementation Method 3
The product fractionation column separates the stripped liquid hydrocracked stream into an overhead fractionated stream comprising naphtha and a bottoms stream comprising unconverted oil comprising distillate
Implementation Method 4
absorbing acid gases from the fractionated overhead stream to provide an absorbed stream; separating the absorbed overhead stream into an offgas stream and a liquid absorbed stream
Data Source
AI summary
A process and apparatus for hydrocracking a distillate stream and provides for separation into product cuts without a separate debutanizer column, a naphtha splitter column or a sponge absorber column. The product cuts include a C3-C5 LPG stream and a heavy naphtha stream which can be useful as a reforming feed stream. Additionally, as few as two heaters that rely on external utilities may be required for reboiling fractionator column bottoms.