Lime-Gypsum Desulfurization Effluent Spray for SO3 Removal
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Solution Overview
Problem
Existing exhaust-gas treatment systems face challenges in efficiently removing SO3 from combustion exhaust gas at low cost, particularly when using the lime-gypsum method, as they require expensive chemicals and additional facilities, and struggle to integrate the dissolved-salt spray method effectively.
Innovation Solution
An exhaust-gas treatment apparatus and method that incorporates a desulfurization apparatus based on the lime-gypsum method, where desulfurizing effluent containing MgSO4 is sprayed upstream to create atomized droplets that adsorb and fix SO3, allowing for circulation and concentration of dissolved salt without the need for new chemicals, reducing operating costs and facility requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the lime-gypsum method is used for desulfurization, then large-scale exhaust gas processing capability is achieved, but the ability to effectively remove SO3 is lost due to poorly soluble gypsum in the effluent
Solution Approach 1:
The system divides the SO3 removal function into two parts: the lime-gypsum desulfurization apparatus handles SO2 removal and produces effluent, while a separate spray apparatus handles SO3 removal by spraying dissolved salt into the exhaust gas stream. This segmentation allows each component to optimize its specific function without interference from gypsum precipitation.
Solution Approach 2:
The desulfurizing effluent from the lime-gypsum method is given multiple uses: it is sprayed to remove SO3, and then the spent effluent is recirculated back to the desulfurization apparatus. This multi-functionality maximizes the utility of the effluent stream and integrates the two methods effectively.
2Reliability
If a separate small-scale desulfurization apparatus is added to provide dissolved salt, then SO3 removal capability is achieved, but facility complexity and cost increase
Solution Approach 1:
The system merges the SO3 removal function with the existing lime-gypsum desulfurization apparatus by using its effluent as the dissolved salt source. The spray apparatus is integrated into the exhaust gas stream at an optimal position, combining two functions (SO2 removal and SO3 removal) into a unified system rather than adding completely separate facilities.
Solution Approach 2:
The lime-gypsum desulfurization apparatus produces effluent that contains dissolved salts (Na2SO4, MgSO4) as byproducts. This effluent is then utilized by the spray apparatus for SO3 removal, making the system self-sufficient. The dissolved salt needed for SO3 removal is generated internally by the desulfurization process itself, eliminating the need for external chemical supply systems.
3Reliability
If new chemical solutions are introduced to achieve dissolved-salt spray method, then SO3 removal efficiency is improved, but operating cost increases significantly
Solution Approach 1:
Instead of discarding the effluent from the lime-gypsum desulfurization apparatus, the system recovers and reuses it for SO3 removal. The effluent containing dissolved salts is sprayed into the exhaust gas stream to remove SO3, and then the spent effluent is recirculated back to the desulfurization apparatus. This recovery and reuse cycle eliminates the need for continuous chemical input and reduces waste disposal costs.
Solution Approach 2:
The system uses the byproduct effluent from the desulfurization process as the active ingredient for SO3 removal. The dissolved salts (Na2SO4, MgSO4) that would normally be considered waste or require separation are instead utilized as the functional medium for SO3 absorption. This self-service approach eliminates the need to purchase and introduce new chemical solutions.
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 enables efficient SO3 removal with reduced operating costs and facility needs by utilizing the lime-gypsum method and circulating dissolved salt, enhancing adsorption capabilities and reducing chemical usage.
Implementation Method 1
a spray section that sprays desulfurizing effluent from the desulfurization apparatus to an upstream side of the desulfurization apparatus
Implementation Method 2
When sprayed, an aqueous solution containing this dissolved salt is transformed into atomized droplets, and the moisture content about the dissolved salt of these atomized droplets evaporates due to the combustion exhaust gas
Implementation Method 3
a desulfurization apparatus based on a lime-gypsum method that removes SO2 contained in the combustion exhaust gas
Data Source
AI summary
An object is to provide an exhaust-gas treatment apparatus capable of realizing a dissolved-salt spray method easily and at low cost. An exhaust-gas treatment apparatus that removes SO2and SO3contained in combustion exhaust gas includes a desulfurization apparatus based on the lime-gypsum method. Desulfurizing effluent, containing dissolved salt, from the desulfurization apparatus is sprayed to an upstream side of the desulfurization apparatus to remove SO3. A wet electrical dust precipitator may be provided downstream of the desulfurization apparatus. Furthermore, effluent from the wet electrical dust precipitator may be made to merge with the desulfurizing effluent from the desulfurization apparatus.