Hydrocracking Prefractionator Integrating Stripped Streams
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Solution Overview
Problem
There is a need to improve the efficiency of processes for recovering petrochemical feedstock from hydrocracked distillate stocks, as existing methods rely heavily on external utilities for heating and require multiple columns for fractionation, which increases energy consumption and capital expenses.
Innovation Solution
A process and apparatus that feeds a cold stripped stream and a hot stripped stream to a product fractionation column with a prefractionator, eliminating the need for separate naphtha splitter and deethanizer columns by producing three products: light naphtha, heavy naphtha, and unconverted oil, and integrates heat recovery between stripping column reboilers to reduce steam usage and heater duty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple fractionation columns (deethanizer, naphtha splitter) are used to separate hydrocracked streams, then product separation precision is improved, but device complexity and capital expenses increase
Solution Approach 1:
The patent combines the functions of the deethanizer column and naphtha splitter column into a single integrated fractionation column. This column performs both light ends removal (C1-C4) and naphtha splitting (light naphtha vs. heavy naphtha) in one unit, thereby reducing the total number of columns from three (including both original columns) to one, while maintaining the required product separation precision through internally designed fractionation zones.
Solution Approach 2:
The integrated fractionation column is designed to perform multiple functions simultaneously: it acts as both a deethanizer (removing light ends) and a naphtha splitter (separating light and heavy naphtha). This multi-functional design eliminates the need for separate dedicated columns for each separation task, reducing device complexity while preserving separation capabilities.
2Reliability
If external utilities are used to provide heater duty for fractionation columns, then fractionation process reliability is improved, but energy efficiency deteriorates
Solution Approach 1:
The patent implements a self-sufficient thermal system where the fractionation column utilizes its own overhead vapor for heating purposes. The overhead vapor, which contains significant thermal energy, is condensed and the resulting condensate is used as heating medium in heat exchangers to preheat feed streams, eliminating or reducing the need for external utility heaters and improving overall energy efficiency while maintaining process reliability.
Solution Approach 2:
Instead of discarding the overhead vapor from the fractionation column as waste stream, the patent recovers its thermal energy by condensing it and using the condensate for heating feed streams. This recovery of thermal energy reduces the demand for external utilities and improves the energy balance of the process.
3Manufacturing precision
If steam stripping is used to separate volatile materials from heavier hydrocarbons, then separation efficiency is improved, but steam consumption and energy costs increase
Solution Approach 1:
The patent recovers the thermal energy contained in the overhead vapor from the fractionation column by condensing it and using the condensate for heating purposes. This recovery reduces the need for additional steam generation for heating operations, thereby reducing steam consumption while maintaining effective separation through the integrated fractionation process.
Solution Approach 2:
The patent changes the thermal parameters of the process by utilizing the overhead vapor at its condensation temperature as a heating medium, rather than generating additional steam at high temperatures. This parameter change allows for effective heat transfer and heating of feed streams while significantly reducing steam consumption compared to traditional steam stripping and heating methods.
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 reduces steam consumption, lowers energy costs, and eliminates the need for additional columns, thereby saving capital and operational expenses while achieving efficient separation and recovery of petrochemical products.
Implementation Method 1
Stripping columns typically rely on steam stripping to separate volatile materials from heavier hydrocarbon materials
Implementation Method 2
A product fractionation column separates the stripped liquid hydrocracked stream into an overhead fractionated stream comprising naphtha
Implementation Method 3
integrates heat recovery between stripping column reboilers to reduce steam usage and heater duty
Data Source
AI summary
A process and apparatus for hydrocracking a hydrocarbon stream that feeds a cold stripped stream and a hot stripped stream to a prefractionator from which a prefractionated overhead stream and a prefractionated bottoms stream are passed to a product fractionation column. The product fractionation column may produce three products, light naphtha, heavy naphtha and distillate omitting the need for a naphtha splitter column. Data may be received from a stream in fluid communication with the foregoing process and apparatus.