Two-Stripper Hydrotreating Process for Energy Recovery
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Solution Overview
Problem
Hydrotreating processes for hydrocarbon streams are energy-intensive due to high temperature and pressure requirements, leading to significant fuel consumption in feed heaters, especially when processing vacuum gas oil (VGO), which contributes substantially to the total utility cost in recovering diesel product streams.
Innovation Solution
Implementing a two-stripper system where the hydrotreated effluent is separated into cold and hot streams, with each stream being stripped in respective columns before being fractionated, allowing the cold stripped stream to bypass the product fractionation column, thereby reducing the feed rate to the heater and minimizing the product fractionation heater duty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single stripper and fired heater system is used for hydrotreated effluent processing, then complete fractionation of diesel products can be achieved, but energy consumption and utility costs increase significantly
Solution Approach 1:
The effluent stream is divided into cold and hot separator streams that are processed through separate stripper columns. The cold stripped stream bypasses the fractionation column entirely and goes directly to the diesel pool, while only the hot stripped stream undergoes fractionation. This segmentation reduces the amount of material requiring energy-intensive heating and fractionation, thereby reducing energy consumption while maintaining diesel product recovery.
2Reliability
If high temperature and pressure conditions are used in hydrotreating, then effective removal of sulfur and nitrogen heteroatoms is achieved, but fuel consumption in feed heaters increases
Solution Approach 1:
The invention extracts and removes the cold stripped stream from the energy-intensive fractionation pathway after stripping but before fractionation. By taking out this stream and directing it straight to the diesel pool, the system avoids the high energy consumption associated with heating and fractionating this portion of the effluent, while the hot stripped stream continues to undergo fractionation to ensure complete product separation.
3Manufacturing precision
If the cold stripped stream is routed through the product fractionation column, then complete product separation is achieved, but the feed heater duty and operational costs increase
Solution Approach 1:
The process segments the effluent treatment pathway into two distinct routes: the cold stripped stream bypasses the fractionation column and is sent directly to the diesel pool, while the hot stripped stream proceeds through the fractionation column for complete product separation. This segmentation allows the system to maintain product separation completeness for the hot stream while avoiding unnecessary energy consumption for the cold stream.
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 significantly reduces the energy consumption and costs associated with the product fractionation heater, allowing for more efficient recovery of diesel products without the need for further treatment or upgrading, thus enhancing energy efficiency in hydrotreating processes.
Implementation Method 1
The cold separator stream is stripped in a cold stripper column to provide a cold stripped stream, and the hot separator stream is stripped in a hot stripper column to provide a hot stripped stream
Implementation Method 2
The hot stripped stream is fractionated in a product fractionation column to recover products such as naphtha, kerosene and diesel
Data Source
AI summary
A process and apparatus is disclosed for recovering hydrotreating effluent from a hydrotreating unit utilizing a hot stripper and a cold stripper. Only the hot hydrotreating effluent is heated in a fired heater prior to product fractionation, resulting in substantial operating and capital savings. The cold stripped stream from the cold stripper bottoms line may be passed directly to a diesel pool when VGO is hydrotreated in the hydrotreating reactor bypassing the product fractionation column.