Delayed Coking Recirculate Fractionation for Coke Quality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing delayed coking methods face challenges in achieving high-quality and high-yield production of anode and needle cokes due to low yield and inconsistent quality, particularly when using low-sulfur oil residues, and high linear vapor velocities that lead to foaming and reduced mechanical strength of the coke.
Innovation Solution
The method involves forming a secondary feedstock by mixing a primary feedstock with a recirculate that excludes gaseous and light boiling products from thermal cracking, which are then directed back into the fractionation column, reducing linear vapor velocities and foaming, and optimizing the coking process parameters such as temperature and recirculation ratios to enhance coke quality and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gaseous and light boiling products from thermal cracking are included in the recirculate, then the recirculation ratio can be maintained, but linear vapor velocities increase causing foaming and reduced coke mechanical strength
Solution Approach 1:
The patent extracts and removes gaseous and light boiling products from the recirculate stream before it is mixed with primary feedstock. This extraction eliminates the harmful components that cause foaming and reduce coke strength, while maintaining the beneficial recirculation of heavier fractions that contribute to coke yield and quality.
2Productivity
If recirculate containing all thermal cracking products is used, then recirculation can be maintained, but foaming occurs in the coking chamber reducing feedstock processing capacity
Solution Approach 1:
The patent converts the potentially harmful effect of light boiling products into a benefit by selectively removing them. The removal of these components prevents foaming and allows the coking chamber to process more feedstock, while the removed light products can be separately handled or utilized in other processes.
3Productivity
If high recirculation ratio is used to increase coke yield, then more feedstock can be converted to coke, but coke quality and microstructure become insufficient
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different recirculate fractions. Instead of uniformly treating all recirculate components, it selectively removes gaseous and light boiling products while retaining heavier fractions, thereby maintaining high coke yield from the retained fractions while ensuring high coke quality by excluding the harmful light components.
4Productivity
If recirculate with gaseous and light boiling products is used, then recirculation system operates continuously, but evaporation of light products in coking chamber reduces energy efficiency
Solution Approach 1:
The patent performs preliminary action by removing gaseous and light boiling products from the recirculate before it enters the coking chamber. This pre-removal prevents the energy-wasting evaporation of these light products during coking, thereby improving overall energy efficiency while maintaining continuous recirculation operation.
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 increases the yield and quality of anode and needle cokes, improves energy efficiency, and enhances the structural organization of the coke, while reducing foaming and increasing the mechanical strength of the resulting coke, allowing for a higher feedstock processing capacity.
Implementation Method 1
heating the secondary feedstock in a reaction furnace
Implementation Method 2
heavy hydrocarbon feedstock is thermally decomposed, or cracked, into coke and lighter hydrocarbon products
Implementation Method 3
the vapor-liquid coking products are directed to a fractionation column and separated into gas, gasoline, light and heavy gas oils, and bottom residue
Implementation Method 4
evaporating the gas, gasoline, and light gas oil from the distillate cracking residue
Data Source
AI summary
The delayed coking method includes directing a heated secondary feedstock, which contains heated primary feedstock and recirculate, from a reaction furnace to a coking chamber. Vapor-liquid coking products formed in the coking chamber are then directed to a fractionation column, which fractionates hydrocarbon gas, gasoline, light and heavy gas oils, and bottom residues. Heavy gas oil from the fractionation column is directed to a thermal cracking furnace, the products of which are cooled by cooled light gas oil and directed to an evaporator for separation. In the evaporator, gases and light boiling products are removed by evaporation and returned to the fractionation column, and the remaining distillate cracking residue is separated and used as a component of the recirculate, along with bottom residues from the fractionation column. The resulting process produces high quality and high yield needle and anode cokes.