Quench Tower SO2 Absorption With Acid Recycling and Oxidation
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Solution Overview
Problem
Existing sulfur recovery units have low efficiency in removing sulfur dioxide (SO2) from tail gas streams, leading to high emissions, and the use of amine solutions for gas treatment is costly and energy-intensive.
Innovation Solution
A method involving a quench tower with dilute sulfuric acid to absorb SO2, followed by partial and complete oxidation using electrolysis or liquid oxidants, and subsequent enrichment of the sulfuric acid using reverse osmosis or electrodialysis to enhance SO2 removal efficiency and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a modified Claus sulfur recovery unit is used, then the process is simpler and cheaper, but sulfur recovery efficiency is limited to 98-99%
Solution Approach 1:
The patent introduces a tail gas treatment unit as an intermediary component between the Claus sulfur recovery unit and the environment. This unit contains a hydrogenation catalyst bed that converts residual sulfur compounds (SO2, COS) into H2S, which can then be processed back into sulfuric acid product, thereby increasing overall recovery efficiency without fundamentally redesigning the core Claus process
Solution Approach 2:
The patent changes the chemical parameters of the tail gas stream by adjusting the hydrogenation conditions (temperature, pressure, catalyst composition) to optimize the conversion of SO2 and COS into H2S. This parameter optimization enables higher sulfur recovery efficiency while maintaining process feasibility
2Reliability
If amine solution is used for H2S absorption, then H2S removal is effective, but the solution is costly and energy intensive for regeneration
Solution Approach 1:
The patent changes the absorbent material from amine solution to concentrated sulfuric acid, fundamentally altering the absorption mechanism. Sulfuric acid absorbs H2S through chemical reaction to form hydrogen sulfide gas and sulfuric acid solution, eliminating the need for energy-intensive thermal regeneration required by amine solutions
Solution Approach 2:
The patent uses concentrated sulfuric acid as a disposable or easily replenished absorbent medium. The spent acid solution can be regenerated by distillation or replaced with fresh concentrated sulfuric acid, avoiding the continuous energy input required for amine solution regeneration
3Object-affected harmful factors
If sulfur recovery efficiency is increased to meet environmental regulations, then SO2 emissions are reduced, but the process becomes more complex and costly
Solution Approach 1:
The patent introduces a tail gas treatment unit as an intermediary component between the Claus sulfur recovery unit and the environment. This unit contains a hydrogenation catalyst bed that converts residual sulfur compounds (SO2, COS) into H2S, which can then be processed back into sulfuric acid product, thereby increasing overall recovery efficiency without fundamentally redesigning the core Claus process
Solution Approach 2:
The patent extracts the problematic tail gas stream containing residual SO2 and COS from the main process and directs it through a separate treatment pathway. By isolating and treating only the sulfur-containing compounds in the tail gas, the system achieves higher emission standards without requiring complete process redesign
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 nearly complete conversion of SO2 to sulfuric acid, increasing sulfur recovery unit capacity and reducing emissions effectively and economically.
Implementation Method 1
contacting, in a lower section of the quench tower, the gas stream with a dilute sulfuric acid (H2SO4) aqueous solution, thereby forming a condensed water vapor and dissolving SO2 in the dilute H2SO4 aqueous solution
Implementation Method 2
oxidizing completely, from the partially oxidized stream, the unoxidized dissolved SO2 and H2SO3 in an electrolyzer
Implementation Method 3
The enrichment unit includes a reverse osmosis (RO) membrane
Data Source
AI summary
The technology includes a method for removing sulfur dioxide (SO2) from a gas stream, where SO2 gas is contacted by a diluted sulfuric acid (H2SO4) stream and absorption takes place in a quench tower. The dissolved SO2 reacts with the excess of oxygen in the gas stream, where the oxidation results in the formation of sulfurous acid (H2SO3) and dilute H2SO4. For the complete oxidation of the dissolved SO2, an electrolyzer and/or liquid injectants are used. This results in the formation of diluted H2SO4. The diluted H2SO4 is processed in an enrichment unit to produce concentrated H2SO4 and fresh water. A portion of the diluted H2SO4 and/or fresh water is recycled back to the quench tower for the continued acidic absorption of the incoming SO2 in the gas stream, thereby not relying on an external water source.