Resid Conversion Layout for Cleaner Delayed Coking Products
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing integrated solvent de-asphalting and delayed coking processes face issues with product quality deterioration and yield reduction due to the mixing of recycle fractions, leading to higher coke yield and compromised quality of Heavy Coker Gas Oil (HCGO) and Coker Fuel Oil (CFO).
Innovation Solution
An integrated process that introduces feedstock near the bottom of a fractionator column, separates a mixed feed using a solvent in an extractor, passes the pitch stream through a stripper, heats it to coking temperature, and transfers it to coke drums for thermal cracking, while recycling solvents and optimizing the recycle ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional integration of solvent de-asphalting and delayed coking is employed, then the processing of heavy residue is achieved, but the quality of HCGO and CFO deteriorates due to recycle fraction accumulation
Solution Approach 1:
The invention extracts the harmful recycle fraction from the system by introducing fresh feedstock near the bottom of the fractionator column, below the side draw outlets for HCGO and CFO. This configuration allows the recycle fraction to be separated and removed with the pitch stream to the de-asphalting unit, preventing its accumulation in the product streams and maintaining product quality while enabling higher productivity
Solution Approach 2:
The invention introduces fresh feedstock as an intermediary stream that mixes with the recycle fraction in the lower portion of the fractionator column. This intermediary feed acts as a carrier to transport the recycle fraction to the de-asphalting unit where it can be properly processed and removed, thereby resolving the conflict between maintaining product quality and achieving high productivity
2Reliability
If the recycle ratio is increased to maintain product quality, then HCGO and CFO quality is preserved, but the yield pattern deteriorates and downstream operations are adversely affected
Solution Approach 1:
By extracting the recycle fraction through the de-asphalting unit connection, the invention enables operation at lower recycle ratios while maintaining product quality. This extraction mechanism prevents the recycle fraction from contaminating the HCGO and CFO streams, allowing optimal yield patterns and favorable downstream operations
3Reliability
If solvent de-asphalting is used to remove asphaltenes and produce DAO, then contaminant rejection is achieved, but the choice of solvent is limited by the trade-off between DAO yield and quality
Solution Approach 1:
The integrated process configuration provides multi-functionality by enabling the de-asphalting unit to serve dual purposes: (1) producing high-quality DAO for lube base stock when using light solvents like propane, and (2) processing pitch streams from the fractionator to remove recycle fraction. This universal configuration allows flexible solvent selection based on desired DAO quality and yield requirements without compromising the overall process performance
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
Maintains the quality of HCGO and CFO while increasing yield and reducing the recycle ratio, resulting in improved product quality and efficiency.
Implementation Method 1
solvent de-asphalting is possible because different compounds have different solution affinity for each other and some combination are completely miscible while other combinations are almost immiscible
Implementation Method 2
heating the residual pitch stream in a furnace to a coking temperature to obtain a hot pitch stream
Implementation Method 3
transferring the hot pitch stream to one of a plurality of coke drums where it undergoes thermal cracking reaction to obtain hydrocarbon vapours and coke
Implementation Method 4
passing the hydrocarbon vapours to the fractionator column to obtain product fraction
Data Source
Figure 1
Figure 2~3
AI summary
The present invention relates to resid processing, particularly related to conversion of resid material with maximum recovery of lighter hydrocarbons. The invented process utilizes a novel scheme for integration of solvent de-asphalting and delayed coking processes to maximize the residue conversion to valuable products, with cleaner quality of middle distillates and fuel oil products, in comparison with other integrated solvent de-asphalting and delayed coking schemes. This process also has an additional flexibility to vary the recycle quantity, without impacting fractionator operation of the delayed coking section, which further enhances the product recovery and achieves maximum conversion of the resid feedstock, with minimum impact on liquid product properties.