Hydrocarbon Feedstock Cracking via Flash Separation and Hydrogenation
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Solution Overview
Problem
The production of light olefins from high boiling point hydrocarbon feedstocks is hindered by the formation of coke and the generation of low-value, high viscosity secondary residues during steam cracking, which increases operational costs and environmental concerns, while existing methods often require complex and costly treatments that consume resources unnecessarily.
Innovation Solution
A process involving flash separation steps with intermediate hydrogenation of high boiling point hydrocarbon feedstocks, followed by cracking, which efficiently upgrades the crackable quality of the feedstock, reduces coke formation, and utilizes secondary residues as fuel and hydrogen sources within the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam cracking is applied to high boiling point hydrocarbon feedstocks, then light olefins are produced, but coke formation increases and furnace run-length decreases
Solution Approach 1:
The patent applies preliminary hydrogenation treatment to the high boiling point feedstock before cracking. This preliminary action removes asphaltenes and reduces aromatic content, preventing coke formation during subsequent cracking operations and extending furnace run-length while maintaining olefins production
Solution Approach 2:
The patent segments the feedstock processing into distinct stages: hydrogenation treatment stage and cracking stage. By separating these functions and treating different fractions differently, the process optimizes both olefins yield and furnace operational reliability
2Manufacturing precision
If flash separation is applied to remove heavy components, then crackable quality improves, but low-value high viscosity secondary residues are generated
Solution Approach 1:
The patent converts the harmful high viscosity secondary residues into a beneficial fuel source by combining them with flash vapor for co-cracking. This approach eliminates the waste problem while additional olefins are produced from the previously problematic residue material
3Productivity
If complex treatments are applied to upgrade feedstock quality, then crackable percentage increases, but process complexity and cost increase
Solution Approach 1:
The patent makes the secondary residue serve multiple functions: it acts as fuel for the furnace and simultaneously as additional cracker feedstock. This multi-functionality simplifies the overall process by eliminating separate handling streams while improving crackable percentage
4Ease of manufacture
If heavy feedstocks are used as cracker feed, then economic cost advantage is maintained, but coking rate increases
Solution Approach 1:
The patent applies preliminary hydrogenation to heavy feedstocks before cracking, removing asphaltenes and reducing aromatic content. This preliminary treatment maintains the economic advantage of using inexpensive heavy feedstocks while preventing excessive coking during cracking operations
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 enhances the crackable fraction of the feedstock, reduces the formation of asphaltenes, tars, and coke precursors, and provides a self-sufficient fuel and hydrogen supply, thereby improving process efficiency and reducing environmental impact while maintaining economic viability.
Implementation Method 1
flashing the heated feedstock in a first separation vessel to create a first overhead stream and a first bottoms liquid stream
Implementation Method 2
hydrogenating at least a portion of the first bottoms liquid stream to create a hydrogenated bottoms stream
Implementation Method 3
cracking the first overhead stream and the second overhead stream in a cracking furnace to produce a pyrolysis effluent stream
Data Source
AI summary
In one aspect, the invention includes in a process for cracking a hydrocarbon feedstock comprising: a) feeding a hydrocarbon feedstock containing at least 1 wt % of resid components having boiling points of at least 500° C. to a furnace convection section to heat the feedstock; b) flashing the heated feedstock in a first flash separation vessel to create a first overhead stream and a first bottoms liquid stream; c) hydrogenating at least a portion of the first bottoms liquid stream to create a hydrogenated bottoms stream; d) flashing the hydrogenated bottoms stream in a second flash separation vessel to create a second overhead stream and a second bottoms liquid stream; e) cracking the first overhead stream and the second overhead stream in a cracking furnace to produce a pyrolysis effluent stream. In other embodiments, the process further comprises heating the hydrocarbon feedstock in step a) to a temperature within a range of from 315° C. to 705° C.