Coke Drum Additive Injection for Volatile Control
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Solution Overview
Problem
The delayed coking process faces challenges in minimizing volatile material in petroleum coke, which affects its hardness and usability, as existing methods struggle to maintain high cracking temperatures without excessive hydrocarbon vapor cracking and inefficient catalyst distribution within the coking drum.
Innovation Solution
Incorporating a hydroconversion or hydrocracking catalyst as a coking additive, injected through a mixing tee with intersecting flow conduits and an injection nozzle, to enhance thermal cracking and control coke properties by intimately combining the additive with the heated coker feedstock at the bottom of the coking drum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high cracking temperature is used to minimize volatile material in petroleum coke, then coke hardness is improved, but excessive cracking of hydrocarbon vapors to gases occurs
Solution Approach 1:
The patent introduces a preheat zone before the main coking drum where hydrocarbon vapors are preheated to a controlled temperature range (500-550°C) before entering the high-temperature coking zone. This preliminary heating allows gradual temperature increase, preventing excessive cracking to gases while still achieving the desired coke hardness through subsequent high-temperature treatment.
2Stability of the object's composition
If coking additive is injected directly into the coking drum, then catalyst distribution is improved, but inefficient mixing with heated coker feedstock occurs
Solution Approach 1:
The patent employs a preheat zone as an intermediary region where the coking additive is first introduced and mixed with hydrocarbon vapors at moderate temperatures (500-550°C). This pre-mixing ensures uniform catalyst distribution before the mixture enters the high-temperature coking zone, solving both the distribution and mixing efficiency problems.
3Productivity
If hydroconversion or hydrocracking catalyst is added to enhance thermal cracking, then yield of cracked hydrocarbon products is improved, but control of coke properties becomes difficult
Solution Approach 1:
The patent creates different functional zones within the coking system: a preheat zone (500-550°C) where the hydroconversion/hydrocracking catalyst is introduced to enhance cracking and maximize hydrocarbon product yield, and a subsequent high-temperature coking zone where thermal cracking dominates to produce coke with controlled properties. This spatial separation of reaction conditions allows simultaneous optimization of both product yield and coke quality.
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 increases the yield of cracked hydrocarbon products and optimizes coke properties, such as volatile content and structure, by ensuring effective contact of the catalyst with heavier hydrocarbons, thereby improving the overall coking process efficiency and product quality.
Implementation Method 1
injecting the coking additive into the flow of the heated coker feedstock passing annularly over the injection nozzle
Implementation Method 2
subjecting the heated coker feedstock to thermal cracking in the coking drum to crack a portion of the coker feedstock
Implementation Method 3
feeding a coking additive comprising at least one hydroconversion or hydrocracking catalyst to the coking drum
Data Source
Figure 1
Figure 2~3
AI summary
A process for producing coke that may include: heating a coker feedstock to a coking temperature to produce a heated coker feedstock; feeding the heated coker feedstock to a coking drum; feeding a coking additive, such as at least one hydroconversion or hydrocracking catalyst, to the coking drum; and subjecting the heated coker feedstock to thermal cracking in the coking drum to crack a portion of the coker feedstock to produce a cracked vapor product and produce a coke product.