Low-Velocity Steam Mixing for Whole Crude Steam Cracking
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Solution Overview
Problem
Hydrocarbon mixtures with non-volatile components or high end boiling points cannot be directly processed in steam pyrolysis reactors due to rapid coking, and existing methods require separate processing of fractions, which are capital and energy intensive.
Innovation Solution
A process that preheats hydrocarbon feeds below their bubble point and mixes them with steam at low relative velocities to vaporize volatile components without forming small droplets, using co-current or counter-current flow configurations and cyclonic separators to separate vapor and liquid phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hydrocarbon mixtures with non-volatile components are processed directly in steam pyrolysis reactor, then processing simplicity is improved, but coking rate increases rapidly
Solution Approach 1:
The patent applies preliminary action by preheating the hydrocarbon feedstock in a convection zone before it enters the radiant zone for pyrolysis. This preliminary heating step ensures that non-volatile components are partially vaporized and mixed with steam beforehand, preventing them from causing rapid coking in the reactor while maintaining processing simplicity.
2Object-generated harmful factors
If reaction conditions are limited to reduce fouling tendency, then coking is reduced, but yield loss increases significantly
Solution Approach 1:
The patent applies parameter changes by optimizing the temperature profile across different zones - maintaining lower temperatures in the convection zone for gentle preheating and steam mixing, then transitioning to high temperatures in the radiant zone for efficient pyrolysis. This parameter variation allows high yield while controlling fouling through controlled vaporization and steam dilution.
3Reliability
If hydrocarbon mixtures are fractionated into numerous fractions for separate processing, then process control and yield are improved, but capital and energy requirements increase
Solution Approach 1:
The patent applies universality by designing a single steam pyrolysis reactor that can effectively process entire hydrocarbon crudes containing a wide range of boiling points. The multi-zone reactor design (convection zone for preheating and radiant zone for pyrolysis) enables one system to handle the functionality that would otherwise require multiple separate fractionation and processing units, reducing capital and energy requirements.
4Productivity
If steam and hydrocarbons are contacted at high relative velocities to achieve vaporization, then vaporization efficiency is improved, but small liquid droplet formation increases
Solution Approach 1:
The patent applies local quality by creating different flow conditions in different locations - high velocity steam injection zones for efficient vaporization where needed, and lower velocity zones for droplet separation. The reactor design incorporates specific regions where steam and hydrocarbon contacts occur at optimized velocities, allowing vaporization efficiency while minimizing difficult-to-separate droplet formation.
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
Reduces coking and fouling, increases yield, and decreases capital and energy requirements by allowing flexible processing of whole crudes and other hydrocarbon mixtures, while maintaining high olefin production efficiency.
Implementation Method 1
contacting a whole crude having an end boiling point over 550°C with steam to volatilize hydrocarbons therein having a normal boiling point temperature of less than 450°C
Implementation Method 2
separating a vapor phase comprising volatilized hydrocarbons and steam from a liquid phase comprising unvaporized hydrocarbons and steam cracking hydrocarbons in the vapor phase
Data Source
AI summary
A process for steam cracking a whole crude including a volatilization step performed to maintain a relatively large hydrocarbon droplet size. The process may include contacting a whole crude with steam to volatilize a portion of the hydrocarbons, wherein the contacting of the hydrocarbon feedstock and steam is conducted at an initial relative velocity of less than 30 m/s, for example. The resulting vapor phase, including volatilized hydrocarbons and steam may then be separated from a liquid phase comprising unvaporized hydrocarbons. The hydrocarbons in the vapor phase may then be forwarded to a steam pyrolysis reactor for steam cracking of the hydrocarbons in the vapor phase.