SO2 Catalytic Oxidation and Quench Absorption for Sulfuric Acid Recovery
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Solution Overview
Problem
Existing sulfur recovery methods, such as the Shell Claus Off Gas Treatment (SCOT) process, are costly due to the use of proprietary amines and additional treatment steps, necessitating the development of cost-effective and sustainable methods for removing sulfur-containing compounds from emissions.
Innovation Solution
A method involving the use of an oxidative catalytic converter with alkali metal-promoted catalysts to oxidize sulfur dioxide (SO2) to sulfur trioxide (SO3), followed by absorption in a quench tower with diluted aqueous acid to generate sulfuric acid (H2SO4), and subsequent processing in a water treatment unit to produce concentrated sulfuric acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Shell Claus Off Gas Treatment (SCOT) process is used to remove sulfur-containing compounds, then sulfur recovery efficiency is improved, but operational cost increases due to proprietary amines and additional treatment steps
Solution Approach 1:
The patent extracts and eliminates the need for proprietary amines by using a quenching liquid that absorbs SO3 directly. The harmful SO3 is taken out of the gas stream through absorption in the quenching tower, replacing the complex amine-based scrubbing system with a simpler aqueous absorption system that achieves the same sulfur removal function without the high operational costs of proprietary chemicals
Solution Approach 2:
The patent changes the chemical parameters of the absorption medium from proprietary amines to diluted aqueous acid (water or dilute sulfuric acid). This parameter change transforms the system from requiring expensive, specialized chemicals to using inexpensive, readily available materials, thereby reducing operational costs while maintaining effective sulfur compound removal
2Device complexity
If thermal oxidizer effluent is directly discharged, then operational complexity is reduced, but environmental compliance deteriorates due to SO2 emissions
Solution Approach 1:
The patent converts the harmful SO2 emissions into beneficial sulfuric acid product. The thermal oxidizer effluent containing SO2 is passed through a catalytic converter that oxidizes SO2 to SO3, which is then absorbed in the quenching tower to produce sulfuric acid. This transforms the harmful emission into a valuable chemical product, simultaneously reducing environmental impact and creating economic value
Solution Approach 2:
The patent introduces a catalytic converter as an intermediary device between the thermal oxidizer and the quenching tower. This intermediary converts SO2 to SO3 through catalytic oxidation, enabling the subsequent absorption process to effectively remove sulfur compounds while producing sulfuric acid, thus bridging the gap between simple operation and environmental compliance
3Reliability
If catalytic oxidation is used to convert SO2 to SO3, then sulfur compound removal efficiency is improved, but process complexity increases due to additional treatment steps
Solution Approach 1:
The patent merges the quenching function with the sulfur absorption function into a single integrated quenching tower. The tower simultaneously cools the thermal oxidizer effluent and absorbs the generated SO3 using the same quenching liquid, eliminating the need for separate cooling and absorption units. This integration reduces equipment complexity while maintaining high sulfur compound removal efficiency
Solution Approach 2:
The quenching liquid serves multiple functions: it cools the hot effluent gas, absorbs the SO3 generated by catalytic oxidation, and produces sulfuric acid as a valuable product. This multi-functionality reduces the number of separate treatment steps and equipment needed, simplifying the overall process while achieving effective sulfur compound removal
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
Achieves high sulfur recovery efficiency with reduced costs by transforming SO2 into sulfuric acid, enabling efficient sulfur compound removal and monetization, while meeting stringent environmental regulations.
Implementation Method 1
passing the thermal oxidizer effluent through the oxidative catalytic converter to contact the thermal oxidizer effluent with the alkali metal-promoted catalyst, thereby oxidizing at least a portion of the SO2 to sulfur trioxide (SO3) with the O2 from the thermal oxidizer effluent
Implementation Method 2
contacting the cooled exit stream with a diluted aqueous acid quench stream in the quench tower to dissolve the SO3 and the rest of the portion of the SO2 in the diluted aqueous acid quench stream, thereby generating sulfurous acid (H2SO3), hydrated sulfur dioxide, and sulfuric acid (H2SO4)
Implementation Method 3
oxidizing the H2SO3 and the hydrated sulfur dioxide with the O2 from the thermal oxidizer effluent in the one or more packing zones, thereby generating a diluted aqueous acid product stream containing H2SO4 leaving the quench tower
Implementation Method 4
cooling the oxidized gas stream in a waste heat recovery system to generate a cooled exit stream
Data Source
AI summary
Provided herein are methods and systems for treating a sulfur dioxide-containing gaseous stream. The method includes combusting a tail gas in an excess of oxygen gas to yield a thermal oxidizer effluent containing sulfur dioxide and oxygen. The thermal oxidizer effluent is introduced to an oxidative catalytic converter to convert sulfur dioxide to sulfur trioxide, thereby forming an oxidized gas stream. The oxidized gas stream is routed to a quench tower and contacted with a dilute aqueous acid quench stream to yield sulfurous acid, hydrated sulfur dioxide, or both. The sulfurous acid or hydrated sulfur dioxide is oxidized with the excess of oxygen from the thermal oxidizer effluent to yield sulfuric acid.