Choline Salt Neutralizing Agent for Steam Cracker Corrosion
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Solution Overview
Problem
Current neutralizing agents in olefin and styrene production plants, such as caustic and monoethanolamine, face challenges like sodium carry-over causing furnace coking, ammonia contamination leading to catalyst poisoning, and high volatility resulting in fouling and corrosion issues in dilution steam systems.
Innovation Solution
A sodium-free neutralizing agent with a high pKa and low volatility index, specifically a choline salt stabilized with 2-10 wt.% alkanolamine, is injected into the dilution steam system to effectively control pH and prevent fouling and corrosion, minimizing the need for large amounts of neutralizing agents and reducing ammonia contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If caustic (NaOH) is used as neutralizing agent, then cost-effectiveness is improved, but sodium carry-over causes furnace coking and embrittlement
Solution Approach 1:
The invention extracts and eliminates the harmful sodium component from the neutralizing agent system by using alternative alkaline agents (KOH, LiOH, CsOH, RbOH) that do not cause sodium carry-over problems, while maintaining the cost-effectiveness benefit through selective use of these alternatives based on specific operational requirements
Solution Approach 2:
The invention changes the chemical composition parameter of the neutralizing agent from sodium-based (NaOH) to alternative alkali metals (KOH, LiOH, CsOH, RbOH), fundamentally altering the system's behavior regarding carry-over and corrosion while maintaining neutralization effectiveness
2Reliability
If monoethanolamine (MEA) is used as neutralizing agent, then pH control is improved, but large amounts are required and ammonia contamination occurs
Solution Approach 1:
The invention changes the chemical nature of the neutralizing agent from organic amine (MEA) to inorganic hydroxides (KOH, LiOH, CsOH, RbOH), fundamentally altering the pH control mechanism to eliminate buffering effects and reduce the quantity required while preventing ammonia formation
Solution Approach 2:
The invention employs hydroxide agents that act directly and completely without forming stable buffers, effectively 'using up' the neutralizing capacity in a controlled manner that prevents accumulation and reduces the total quantity needed compared to reusable buffer systems
3Speed
If volatile neutralizing agents are used, then pH adjustment speed is improved, but fouling and corrosion in dilution steam system increase
Solution Approach 1:
The invention changes the volatility parameter of the neutralizing agent by selecting hydroxides with appropriate vapor pressures for steam environment, achieving rapid pH adjustment through controlled volatility while minimizing carry-over that causes fouling and corrosion
Solution Approach 2:
The invention applies different hydroxide agents (KOH, LiOH, CsOH, RbOH) with varying volatility characteristics to different operational requirements within the steam system, optimizing the balance between pH adjustment speed and minimization of harmful carry-over effects
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
The solution effectively maintains the pH within protective ranges, reducing corrosion and fouling in equipment, extending furnace run length, and preventing sodium embrittlement, while minimizing the neutralizing agent's presence in the steam phase to avoid catalyst poisoning and fouling.
Implementation Method 1
These acidic byproducts are neutralized with an alkaline agent
Implementation Method 2
the choline salt is stabilized by 2 wt.% to 10 wt.% alkanolamine based on the total weight of stabilized choline salt
Implementation Method 3
Dilution steam promotes the formation of desired olefins by reducing the hydrocarbon partial pressure in the pyrolysis furnace
Implementation Method 4
the pyrolysis of hydrocarbon feedstock
Implementation Method 5
the effluent gases must be rapidly cooled, i.e., quenched, in order to prevent the recombination of the reactive olefins
Implementation Method 6
a portion of the condensate is processed for re-use as dilution steam
Data Source
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AI summary
The present invention generally relates to compositions and methods for neutralizing acidic streams in an olefin or styrene production plant. More specifically, the invention relates to neutralizing agents for dilution steam systems in the steam cracker process and their use for reducing acid corrosion and fouling in such systems.