Calcium Sulfide Decomposition via Controlled Carbon Oxidation
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Solution Overview
Problem
Current methods for decomposing calcium sulfide (CaS) into calcium oxide (CaO) and sulfur dioxide (SO2) are inefficient due to high energy demands and incomplete conversion, often requiring high temperatures and resulting in the formation of unwanted calcium sulfate (CaSO4), which complicates the process and increases environmental impact.
Innovation Solution
A process involving a reactor with calcium sulfide and a source of carbon, where carbon is oxidized to generate carbon dioxide (CO2), facilitating the decomposition of CaS into CaO and SO2 under controlled oxygen and carbon stoichiometry, with specific mass ratios of C/CaS between 0.15 and 0.35 and O2/C between 5 and 25, utilizing the exothermic carbon oxidation reaction to provide energy for the endothermic decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If carbon oxidation is used to provide energy for CaS decomposition, then energy requirements are reduced, but controlling the reaction to avoid CaSO4 formation becomes more difficult
Solution Approach 1:
The invention changes the chemical composition parameters by introducing carbon as a reducing agent alongside the carbonation process. By controlling the C/CaS mass ratio between 0.15-0.35 and O2/C mass ratio between 5-25, the process modifies the reaction environment to prevent CaSO4 formation while maintaining energy efficiency through carbon oxidation.
Solution Approach 2:
Carbon acts as an intermediary substance that serves dual functions: it provides energy through oxidation and simultaneously prevents CaSO4 formation by creating a reducing atmosphere. The carbon intermediates the reaction between oxygen and calcium sulfide, ensuring the process proceeds through the desired pathway without harmful byproducts.
2Productivity
If high temperatures are used to maintain reactor operation, then decomposition reactions proceed efficiently, but energy consumption increases significantly
Solution Approach 1:
The process implements self-service by using carbon oxidation within the reactor to generate the heat required for decomposition. The exothermic oxidation of carbon provides endothermic heat for the decomposition reactions, creating a self-sustaining thermal environment that reduces external energy input while maintaining high decomposition efficiency.
Solution Approach 2:
The invention merges the energy generation function with the decomposition process by combining carbon oxidation (exothermic) with CaS decomposition (endothermic). This integration allows the heat from carbon oxidation to directly supply the thermal energy needed for decomposition, eliminating the need for separate external heating systems.
3Productivity
If oxidation conditions are used to convert CaS to CaO and SO2, then conversion occurs, but CaSO4 forms as an unwanted byproduct
Solution Approach 1:
The invention applies local quality by creating different chemical environments in different zones of the reactor. Carbon is introduced to create localized reducing conditions that prevent CaSO4 formation, while oxidation conditions are maintained in other areas to enable CaS conversion. This spatial differentiation of reaction conditions allows simultaneous achievement of high conversion and minimal byproduct formation.
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 achieves favorable CaS conversion to CaO and SO2 with reduced energy requirements and minimizes CaSO4 formation, allowing for efficient recycling of CaO and utilization of SO2 in sulfuric acid production, while maintaining reactor temperatures between 900°C and 1200°C.
Implementation Method 1
The oxidation reaction of carbon (C) into carbon monoxide (CO) then carbon dioxide CO2 is exothermic. The process of the invention uses the carbon dioxide CO2 and the energy produced by this exothermic reaction to carry out the reaction of decomposition of the calcium sulfide CaS, which is an endothermic reaction.
Implementation Method 2
reacting the calcium sulfide with said carbon dioxide so as to produce calcium oxide (CaO), sulfur dioxide (SO2) and carbon monoxide (CO) according to the following reaction: CaS+3CO2→CaO+SO2+3CO wherein the oxygen and carbon contents in the oxidation step are chosen such that: (i) the mass ratio C/CaS is comprised between 0.15 and 0.35 and (ii) the mass ratio O2/C is comprised between 5 and 25.
Data Source
AI summary
The present invention relates to a process for decomposing calcium sulfide (CaS) into calcium oxide (CaO) and sulfur dioxide (SO2), comprising:—providing a reactor containing calcium sulfide and a source of carbon,—oxidizing the source of carbon so as to generate carbon dioxide (CO2),—reacting the calcium sulfide with said carbon dioxide so as to produce carbon oxide (CaO), sulfur dioxide (SO2) and carbon monoxide (CO) according to the following reaction: CaS+3CO2˜CaO+SO2+3CO wherein the oxygen and carbon contents in the oxidation step are chosen such that: (i) the mass ratio C/CaS is comprised between 0.15 and 0.35 and (ii) the mass ratio O2/C is comprised between 5 and 25.