Sulphuric Acid Recycle Stream Reduces Molar Flow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing dual desulphurisation processes for producing sulphuric acid face challenges in controlling condensation of sulphuric acid, leading to increased equipment and operational costs due to excess air dilution and higher molar flow, which affects heat recovery and corrosion management.
Innovation Solution
A process is configured to recycle a substream of desulphurised gas, reducing molar flow and dilution requirements, thereby minimizing equipment size and energy consumption, while maintaining non-corrosive conditions by ensuring the recycled gas is heated above the sulphuric acid dew point and used strategically in the desulphurisation plant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If excess air is added to dilute the oxidized process gas to control sulphuric acid dew point, then condensation of sulphuric acid outside the condensation unit is prevented, but the total molar flow increases leading to extra cost and reduced heat recovery
Solution Approach 1:
The process gas stream is segmented into two separate streams: one that is diluted with excess air to control dew point, and another that is recycled back to the sulphur burner. This segmentation allows the system to benefit from dilution without carrying the entire high-flow stream through all process sections, thereby reducing total molar flow in critical sections while still preventing harmful condensation.
Solution Approach 2:
Instead of discarding the excess air dilution requirement to the entire process stream, the invention recycles a portion of the process gas back to the sulphur burner. This recovery approach allows the system to maintain the necessary dilution for dew point control in the condensation section while recovering the flow volume in upstream sections, reducing overall material handling costs and improving heat recovery efficiency.
2Temperature
If excess air is added to dilute the oxidized process gas, then sulphuric acid dew point is controlled, but heat recovery is reduced due to increased flow
Solution Approach 1:
The gas stream is segmented such that only the portion needed for dew point control in the condensation section is diluted with excess air, while the main process stream is recycled upstream. This reduces the volume of gas requiring heat recovery processing while maintaining adequate dilution for dew point management.
Solution Approach 2:
The invention recycles the process gas back to the sulphur burner, recovering the thermal energy that would otherwise be lost in heating and processing a larger diluted stream. This recovery of hot process gas upstream reduces the overall energy input required while maintaining the dilution benefit in the condensation section.
3Object-affected harmful factors
If dual desulphurisation process plants are configured in series to meet emission regulations, then sulphur oxide emissions are reduced to very low concentrations, but equipment requirements and operational costs increase
Solution Approach 1:
The invention merges the function of two separate desulphurisation plants by implementing a recycle stream that connects the second plant back to the first plant's sulphur burner. This integration allows the system to achieve the emission reduction benefits of dual processing while sharing equipment resources, thereby reducing overall device complexity and capital requirements.
Solution Approach 2:
The recycled process gas from the second desulphurisation plant serves multiple functions: it acts as dilution gas for the first plant's combustion process, provides thermal energy recovery, and contributes to further sulphur oxide removal. This multi-functionality reduces the need for separate dedicated equipment for each function, lowering overall equipment requirements.
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 reduces the overall molar flow, decreases equipment size, and optimizes heat recovery, achieving lower sulphur emissions and operational costs while preventing corrosive condensation of sulphuric acid.
Implementation Method 1
oxidation of SO2 to SO3 in the presence of water vapour
Implementation Method 2
condensation to H2SO4, and is sold under the trade name WSA (the Wet gas Sulphuric Acid)
Implementation Method 3
ensuring the recycled gas is heated above the sulphuric acid dew point
Data Source
AI summary
The invention relates to a process for oxidation of SO2 to SO3 comprising the steps of (a) directing a stream of feed gas comprising SO2 and O2 to a catalytically active material, (b) oxidizing an amount of said SO2 in said process gas to SO3 in the presence of the catalytically active material, providing a first oxidized process gas, (c) reacting SO3 with water, (d) condensing H2SO4, (e) withdrawing a first desulphurized process gas and a first stream of sulphuric acid, (f) from the desulphurized process gas withdrawing a recycle stream of desulphurized process gas, wherein the recycle stream is added to said stream of feed gas or said first oxidized process gas with the associated benefit of reducing the molar flow of process gas downstream withdrawal of the recycle stream and upstream the mixing point.