FCC Riser Oxygen Injection for Corrosion-Reducing Process Water
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Solution Overview
Problem
The presence of ammonia, sulfides, and cyanides in process water from fluid catalytic cracking (FCC) units leads to severe corrosion, particularly in partial combustion units, causing equipment damage and safety risks due to hydrogen bubble formation and pH elevation.
Innovation Solution
Injecting air or oxygen-containing gas at the base of the riser and using a catalyst with a maximum noble metal content of 1 ppm to convert ammonia into nitrogen, reducing corrosive contaminants in process water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ammonia, sulfides and cyanides are present in process water, then corrosion occurs leading to equipment damage and safety risks, but controlling pH and diluting contaminants requires additional process complexity and operational adjustments
Solution Approach 1:
The patent converts the harmful effect of ammonia into a beneficial one by utilizing it as a reagent. Ammonia is injected into the combustion gas to react with hydrogen cyanide and form toxic but less corrosive substances, thereby transforming the original harmful contaminant into a useful tool for contamination control.
Solution Approach 2:
The patent introduces an intermediary substance (ammonia) that mediates between the harmful contaminants (hydrogen cyanide) and the combustion gas. This intermediary reacts with the harmful substances to form less harmful products, effectively reducing corrosion without requiring direct pH control or dilution methods.
2Object-affected harmful factors
If pH is controlled in the range of 7 to 8, then corrosion is reduced, but this requires continuous monitoring and adjustment increasing operational complexity
Solution Approach 1:
Instead of controlling pH to reduce corrosion, the patent converts the harmful ammonia into a reactive species that directly neutralizes hydrogen cyanide. This transforms the approach from passive pH control to active chemical neutralization, simplifying operation while maintaining corrosion protection.
Solution Approach 2:
The system performs self-service by using the ammonia already present in the combustion gas to neutralize hydrogen cyanide automatically. This eliminates the need for external pH control systems, continuous monitoring, and manual adjustment, thereby simplifying operation while effectively reducing corrosion.
3Quantity of substance
If contaminants are diluted by wash water, then corrosive contaminants are reduced, but this increases water consumption and requires additional treatment infrastructure
Solution Approach 1:
The patent converts the dilution approach into a chemical reaction approach. Instead of adding water to dilute contaminants, ammonia is injected to react with and neutralize hydrogen cyanide directly. This transforms the problem from requiring water dilution to requiring chemical reagents, reducing water consumption while effectively reducing contaminant concentration.
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 ammonia content in process water, minimizing corrosion and extending equipment life, thereby reducing operational risks and maintenance costs.
Implementation Method 1
injection of air or oxygen-containing gas or even pure oxygen at a base of the riser... use of a combustion promoter with a maximum noble metal content in the catalyst inventory equivalent to 1 ppm on a mass basis in the catalyst... convert ammonia into nitrogen
Implementation Method 2
combustion promoter... catalyst inventory... convert ammonia into nitrogen
Implementation Method 3
use of a combustion promoter with a maximum noble metal content in the catalyst inventory equivalent to 1 ppm on a mass basis in the catalyst
Data Source
AI summary
The disclosure relates to a process for the reduction of corrosive contaminants in process water, mainly through air or oxygen-containing gas or even pure oxygen injection into the riser, converting part of the ammonia carried from the regenerator to the riser into N2, and reducing the ammonia and cyanide content in the process water condensed in the product recovery section.