Flash Tower Reducing Fouling in Crude Refining
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Solution Overview
Problem
Fouling in crude oil refining equipment, particularly in preheat exchangers and crude heaters, is exacerbated by elevated phosphorus levels, which are contributed by certain types of crude oil, leading to reduced efficiency and increased maintenance costs.
Innovation Solution
A flash tower design with fractionation trays and a total draw tray system that prevents heavier hydrocarbons containing phosphorus from falling back into the bottom of the tower, allowing them to be routed past the preheat exchanger train and crude heater, thereby reducing phosphorus levels and fouling in downstream vessels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crude oil is heated in preheat exchangers and crude heaters, then the crude oil temperature increases to enable separation, but fouling in the equipment worsens due to elevated phosphorus levels
Solution Approach 1:
The invention extracts phosphorus-containing heavier hydrocarbons from the crude oil stream before they can cause fouling in heat exchangers. The flash tower with fractionation trays separates these contaminants into a distinct phase that is routed separately from the main crude oil flow, removing the harmful component while preserving the heating process benefits
Solution Approach 2:
The invention segments the crude oil stream into different hydrocarbon ranges (lighter and heavier) based on their separation temperatures. By dividing the feed into fractions with different phosphorus contents and routing them through different paths, the system prevents phosphorus-rich heavier hydrocarbons from entering the preheat circuit while maintaining efficient heating of the cleaner lighter fractions
2Productivity
If a flash drum or flash tower is used to remove light hydrocarbons and contaminants, then heat exchange efficiency increases, but phosphorus-containing heavier hydrocarbons may still foul downstream equipment
Solution Approach 1:
The invention introduces fractionation trays as an intermediary separation mechanism within the flash tower. These trays act as a mediator that further divides the flashed vapors into lighter hydrocarbons (safe for heat exchange) and heavier phosphorus-containing hydrocarbons (routed away from heat exchangers), thereby enabling efficient heat exchange without downstream fouling
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
Significantly reduces fouling in preheat exchanger trains and crude heaters by isolating phosphorus-containing hydrocarbons, leading to decreased maintenance and operational costs through enhanced separation and routing of contaminants.
Implementation Method 1
When these hydrocarbons vaporize or flash they carry some amount of heavier hydrocarbons up the tower with them
Implementation Method 2
any liquid that is flashed on entry into the tower will drop back down to the bottom of the tower by refluxing
Implementation Method 3
A flash tower design with fractionation trays and a total draw tray system that prevents heavier hydrocarbons containing phosphorus from falling back into the bottom of the tower
Data Source
AI summary
A method and apparatus for the reduction of fouling in a crude unit. Chemicals containing Phosphorous are understood to be utilized in the production or transportation of certain types of crude oils. It is believed that the elevated levels of phosphorus are contributing to the excessive fouling observed in the preheat exchanger circuits and crude heaters.