Hydrocracking Dual Stripping Columns Heat Integration
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Solution Overview
Problem
Current hydrocracking recovery processes are inefficient in recovering petrochemical feedstock from hydrocracked distillate stocks, relying heavily on external utilities for heating and requiring multiple columns that increase energy consumption and capital expenses.
Innovation Solution
The integration of reboil heating in both cold and hot stripping columns, where sufficient distillate and lighter naphtha products from hydrocracking provide the necessary heat, potentially using a single furnace for both columns, thereby reducing the need for external heating sources and eliminating the requirement for separate deethanizer and naphtha splitter columns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple stripping columns and separate fractionation columns are used, then complete separation of hydrocracked products is achieved, but capital expenses and device complexity increase
Solution Approach 1:
The patent combines the stripping column and fractionation column into a single integrated unit. The stripping section removes hydrogen sulfide and light gases from the hydrocracked distillate, while the fractionation section simultaneously separates the stripped liquid into naphtha and LPG products. This integration eliminates the need for separate deethanizer and naphtha splitter columns, reducing device complexity while maintaining complete product separation.
2Reliability
If external utilities are used to provide heater duty for fractionation columns, then reliable heating is ensured, but energy efficiency decreases
Solution Approach 1:
The integrated column uses its own internal heat integration to provide the necessary heating for fractionation. The reboiler at the bottom of the column vaporizes a portion of the bottoms stream, and this vapor rises through the column to provide heat for condensation on the trays. This self-generated heat circulation eliminates or reduces the need for external utility heating, significantly improving energy efficiency while maintaining reliable operation.
Solution Approach 2:
The patent utilizes phase transitions (vaporization and condensation) within the integrated column to transfer heat internally. The reboiler vaporizes liquid at the bottom, and the rising vapor condenses on trays at different heights, releasing latent heat for fractionation. This internal phase transition-based heat transfer system provides reliable heating while minimizing external utility requirements.
3Manufacturing precision
If steam stripping is used to separate volatile materials, then effective stripping is achieved, but energy consumption increases
Solution Approach 1:
The stripping section of the integrated column uses the hydrocracked distillate feed itself as the stripping medium rather than requiring external steam. The feed is introduced near the top of the stripping section and flows downward, contacting the liquid stream to strip out volatile components like hydrogen sulfide and light gases. This self-stripping approach eliminates the energy consumption associated with steam generation while achieving effective separation.
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 enhances energy efficiency by minimizing external utility usage, reduces capital expenses by eliminating unnecessary columns, and improves the recovery of valuable products like LPG and naphtha, while maintaining or improving product quality.
Implementation Method 1
A reboiler is used to heat and vaporize a portion of the liquid hydrocracked stream
Implementation Method 2
A stripping column strips hydrogen sulfide off of a liquid hydrocracked stream with a steam stream
Implementation Method 3
The product fractionation overhead stream and the deethanizer column bottoms stream are fractionated in a debutanizer fractionation column
Data Source
AI summary
A process and apparatus for hydrocracking a hydrocarbon stream and with heat integration between two stripping columns. Both stripping columns use a reboiler for heat input to avoid steam recovery and dew point issues in the overhead. A hot stripped stream can provide heat to the cold stripping column by heat exchange. Additionally, as few as two heaters that rely on external utilities may be required for reboiling fractionator column bottoms.