Regenerative Sulfur Dioxide Recovery Process
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Solution Overview
Problem
Current regenerative sulfur dioxide recovery processes face challenges in energy efficiency, particularly in handling effluent gases with low sulfur dioxide concentrations and high water vapor content, leading to increased energy and capital expenditures, as well as equipment corrosion and solvent degradation.
Innovation Solution
The process involves a regenerative absorption/desorption cycle that enhances energy efficiency by cooling the absorption zone to increase the capacity of the aqueous absorption medium, recovering energy from the wet contaminant gas stream, and using a buffered aqueous solution with a salt of a weak polyprotic carboxylic acid to selectively absorb sulfur dioxide, followed by stripping with steam generated from condensed water vapor, allowing for efficient recovery and reuse of sulfur dioxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cooling the gas stream is used to reduce water vapor content, then the H2O/SO2 ratio is reduced, but capital and energy expenditures increase significantly
Solution Approach 1:
The invention changes the temperature parameter of the absorption medium rather than cooling the entire gas stream. By maintaining the absorption medium at elevated temperatures (40-100°C), the system achieves effective SO2 absorption without the energy-intensive cooling of the gas stream, thus resolving the contradiction between reducing H2O/SO2 ratio and minimizing energy expenditure
2Quantity of substance
If cooling the gas stream is used to reduce water vapor content, then the H2O/SO2 ratio is reduced, but capital expenditures increase
Solution Approach 1:
Instead of implementing complex cooling systems for the gas stream, the invention changes the operational parameters of the absorption medium (temperature and composition). This approach eliminates the need for expensive cooling equipment while achieving the desired reduction in water vapor content relative to sulfur dioxide
3Reliability
If conventional absorption methods are used, then sulfur dioxide is removed from effluent gases, but energy consumption is high
Solution Approach 1:
The invention optimizes the temperature parameter of the absorption medium to 40-100°C, which enhances SO2 absorption efficiency while reducing energy consumption compared to conventional low-temperature methods. This parameter optimization allows reliable sulfur dioxide removal with lower energy input
Solution Approach 2:
The invention implements a continuous circulation system where the absorption medium is continuously recycled between the absorber and stripper. This continuous operation maintains high SO2 removal efficiency while the heat integration in the circulation loop reduces overall energy consumption
4Productivity
If high temperatures are used in the stripper, then sulfur dioxide is effectively stripped from the absorption medium, but solvent degradation increases
Solution Approach 1:
The invention optimizes the stripper temperature to a specific range (80-120°C) that provides sufficient SO2 stripping efficiency while remaining below the degradation threshold for the absorption medium. This precise parameter control balances productivity with solvent stability
Solution Approach 2:
The invention introduces a heat exchanger as an intermediary device between the stripper and absorber. This heat exchanger recovers heat from the hot stripper effluent to preheat the incoming absorption medium, reducing the energy input required for stripping while maintaining solvent stability through controlled temperature
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
This approach significantly reduces energy consumption, minimizes equipment size, and extends the lifespan of process equipment by optimizing the water balance and reducing solvent degradation, while maintaining high sulfur dioxide recovery efficiency.
Implementation Method 1
contacting a feed gas stream with an aqueous absorption medium in a contaminant absorber, thereby absorbing contaminant gas from the feed gas stream into the absorption medium
Implementation Method 2
contacting the contaminant-enriched absorption liquor with stripping steam in a contaminant stripper, thereby desorbing contaminant from the contaminant-enriched absorption liquor
Implementation Method 3
condensing water vapor from the primary stripper gas effluent by indirect transfer of heat from the primary stripper gas effluent to a cooling medium
Data Source
AI summary
This invention relates to processes for the selective removal of contaminants from effluent gases. More particularly, various embodiments of the present invention relate to selective removal and recovery of sulfur dioxide from effluent gases in a regenerative sulfur dioxide absorption/desorption process that achieves favorable energy efficiency. Energy is recovered from a wet stripper overhead gas stream produced in the desorption cycle by indirect transfer of heat from the stripper gas to a cooling medium and used to generate steam for use in stripping contaminants from the absorption liquor. The absorption zone may optionally be cooled to enhance the capacity of the absorption medium for absorption of a contaminant gas, thereby lowering the volume of absorption medium and contaminant-enriched absorption liquor that must be pumped, handled, heated and cooled in the absorption/desorption cycle.