Hydrocracking Process Bottom Cut Temperature Control
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Solution Overview
Problem
Conventional hydrocracking processes face issues with maintaining stable product quality due to fluctuations in hydrocarbon oil properties, leading to vicious cycles that affect the yield and quality of kerosene and gas oil base stocks, as the constant flow rate of recovered bottom oil can amplify composition changes, resulting in lighter or heavier products.
Innovation Solution
Controlling the bottom cut temperature of the fractionator at a constant level instead of maintaining a constant flow rate of the bottom oil, allowing the flow rate to adjust based on property fluctuations, and using this flow rate as an indicator to adjust reaction conditions in the hydrocracking step to maintain appropriate hydrocracking progression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the flow rate of bottom oil is maintained at a constant level, then the operational simplicity is improved, but the product quality stability deteriorates due to amplification of composition fluctuations
Solution Approach 1:
The patent changes the control parameter from constant flow rate to constant bottom cut temperature. By maintaining the bottom cut temperature at a constant level, the system allows the bottom oil flow rate to vary naturally in response to composition fluctuations, thereby preventing the amplification of variations while maintaining operational simplicity.
2Stability of the object's composition
If the bottom cut temperature is controlled at a constant level, then the properties of bottom oil are kept constant, but the flow rate fluctuates requiring adjustment of reaction conditions
Solution Approach 1:
The patent implements a feedback control mechanism where the bottom oil flow rate, which fluctuates in response to composition changes, is used as an indicator to adjust the reaction conditions in the hydrocracking step. This feedback loop allows the system to maintain constant bottom oil properties while adapting to varying feedstock composition.
3Productivity
If severe reaction conditions are applied to increase hydrocracking progression, then the conversion of wax fraction is improved, but excessive cracking occurs reducing middle distillate yield
Solution Approach 1:
The patent applies dynamic control of reaction conditions based on the fluctuating bottom oil flow rate. By adjusting the hydrocracking reaction conditions dynamically rather than using fixed severe conditions, the system optimizes the balance between wax fraction conversion and middle distillate yield, preventing excessive cracking while maintaining high conversion efficiency.
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 stabilizes the properties of the hydrocarbon oil supplied to the fractionator, suppressing vicious cycles and ensuring stable quality of the middle distillate product by maintaining constant properties and adjusting reaction conditions accordingly.
Implementation Method 1
a fractional distillation step of supplying the hydrocracked product to a fractionator in which a bottom cut temperature is set to a constant value, and obtaining at least a middle distillate and a bottom oil from the fractionator
Implementation Method 2
a wax fraction hydrocracking step of hydrocracking a wax fraction contained within the liquid hydrocarbons synthesized in the liquid hydrocarbon synthesis step, thereby obtaining a hydrocracked product
Data Source
AI summary
A hydrocracking process for a wax fraction that includes a wax fraction hydrocracking step of hydrocracking a wax fraction contained within liquid hydrocarbons synthesized by a Fischer-Tropsch synthesis reaction, thereby obtaining a hydrocracked product, a fractional distillation step of supplying the hydrocracked product to a fractionator in which a bottom cut temperature is set to a constant value, and obtaining at least a middle distillate and a bottom oil from the fractionator, a recycling step of resupplying all of the bottom oil to the wax fraction hydrocracking step, and a hydrocracking control step of controlling the wax fraction hydrocracking step using a flow rate of the bottom oil as an indicator.