Hydrogen Recovery from Hydroprocessed Liquid via Medium Pressure Separator
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Solution Overview
Problem
Hydrogen loss and inefficient recovery of light hydrocarbons, such as LPG and naphtha, from hydroprocessed effluent streams in hydroprocessing units, particularly due to hydrogen being dissolved in hot flash liquid streams and LPG being lost in cold flash gaseous streams, which are typically blended into refinery fuel gas and burned, reducing overall hydrogen consumption and recovery efficiency.
Innovation Solution
Implementing a process that includes a medium pressure separator to recover hydrogen from hydroprocessed liquid streams, followed by a medium pressure flash drum to separate hydrogen-rich gases from liquid streams, and utilizing a PSA unit for further hydrogen purification, while also recovering LPG and naphtha through a series of scrubbing and fractionation columns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If hydrogen is recovered from hydroprocessed effluent streams using conventional separation methods, then hydrogen recovery is achieved, but hydrogen loss occurs due to dissolution in hot flash liquid streams
Solution Approach 1:
The separation process is divided into multiple stages: a first separator performs initial separation of the hydroprocessed effluent stream into gaseous and liquid phases, while a second separator further separates the liquid stream from the first separator. This multi-stage segmentation allows for more effective hydrogen recovery by capturing hydrogen that would otherwise be lost in the hot flash liquid stream, thereby reducing hydrogen loss while maintaining productivity.
2Loss of substance
If conventional separation processes are used to separate hydroprocessed effluent, then basic separation is achieved, but light hydrocarbons like LPG and naphtha are lost in fuel gas streams
Solution Approach 1:
The separation process is divided into multiple stages: a first separator performs initial separation of the hydroprocessed effluent stream into gaseous and liquid phases, while a second separator further separates the liquid stream from the first separator. This multi-stage segmentation allows for more effective hydrogen recovery by capturing hydrogen that would otherwise be lost in the hot flash liquid stream, thereby reducing hydrogen loss while maintaining productivity.
Solution Approach 2:
The patent extracts valuable components (hydrogen, LPG, and naphtha) from the hydroprocessed effluent stream at different stages of the separation process. By taking out these components selectively through multiple separators and recovery units, the process prevents their loss in fuel gas streams while managing the increased complexity through structured extraction stages.
3Productivity
If multiple separation stages are implemented to recover hydrogen and light hydrocarbons, then recovery efficiency improves, but process complexity increases
Solution Approach 1:
The separation process is divided into multiple stages: a first separator performs initial separation of the hydroprocessed effluent stream into gaseous and liquid phases, while a second separator further separates the liquid stream from the first separator. This multi-stage segmentation allows for more effective hydrogen recovery by capturing hydrogen that would otherwise be lost in the hot flash liquid stream, thereby reducing hydrogen loss while maintaining productivity.
Solution Approach 2:
The separation system is designed with multi-functional units that handle multiple separation tasks. The first and second separators collectively perform both initial and further separation functions, while the hydrogen recovery unit and light hydrocarbon recovery unit work together to recover different valuable components. This multi-functionality approach manages complexity by having integrated units that perform multiple roles rather than requiring entirely separate systems for each function.
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 enhances hydrogen recovery by 8 wt % and effectively recovers LPG and naphtha, reducing overall hydrogen consumption and improving refinery profitability by utilizing a medium pressure separator and PSA unit to isolate and purify hydrogen and light hydrocarbons from hydroprocessed streams.
Implementation Method 1
A medium pressure separator is used to recover a gaseous stream from a hydroprocessed liquid stream
Implementation Method 2
A medium pressure flash drum may further remove liquid components from the gaseous stream prior to hydrogen recovery
Implementation Method 3
Pressure swing absorption (PSA) units are useful for purifying hydrogen by adsorbing larger molecules from the hydrogen stream at high pressure
Data Source
AI summary
A medium separator is used to recover a gaseous stream from a hydroprocessed liquid stream for hydrogen recovery in a hydrogen recovery unit. A medium flash drum may further remove liquid components from the gaseous stream prior to hydrogen recovery in the hydrogen recovery unit.