Regenerative Shaft Kiln Sulfur Mobilization Method
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Solution Overview
Problem
Existing methods for producing quick lime in continuous regenerative shaft kilns fail to effectively utilize raw materials and fuels containing sulfur, as sulfur compounds are not adequately reduced to meet the low sulfur content requirements for applications like metallurgy.
Innovation Solution
The method involves monitoring and adjusting parameters such as excessive combustion air, cooling air distribution, and temperature in a regenerative shaft kiln to mobilize sulfur in a gaseous form, specifically by reducing combustion air flow, increasing temperature, and modifying cooling air injection to maintain high SO2 concentrations, thereby reducing sulfur content in the produced lime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sulfur-containing raw materials and fuels are used in regenerative shaft kilns, then production cost is reduced and operational flexibility is improved, but sulfur content in the lime product increases exceeding application requirements
Solution Approach 1:
The patent applies periodic action by alternating the flow direction of combustion air and cooling air between two tanks in a regenerative shaft kiln. During operation, one tank receives combustion air while the other receives cooling air, then they periodically swap roles. This periodic reversal creates alternating zones of high temperature and reduced oxygen availability, which mobilizes sulfur into gaseous form and prevents its incorporation into the lime product, thereby enabling the use of sulfur-containing fuels while maintaining low sulfur content in the final product.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting combustion air flow rates, cooling air distribution, and temperature profiles within the kiln zones. By reducing combustion air flow to create oxygen-deficient conditions and strategically distributing cooling air to maintain temperature gradients, the process transforms sulfur from a harmful impurity into a mobilized gaseous component that can be excluded from the lime product, thus changing the chemical behavior of sulfur through parameter optimization.
2Object-affected harmful factors
If combustion air flow is reduced to mobilize sulfur in gaseous form, then sulfur content in lime is reduced, but combustion efficiency and temperature maintenance become challenging
Solution Approach 1:
The periodic reversal of air flows between tanks ensures that while combustion air is reduced in the active combustion zone to mobilize sulfur, the regenerative heat exchange from the other tank compensates for temperature loss. The alternating pattern maintains overall thermal balance while creating the oxygen-deficient conditions necessary for sulfur mobilization without compromising combustion temperature.
Solution Approach 2:
The patent uses the regenerative heat exchange system as an intermediary to transfer thermal energy between the two tanks. The tank not currently undergoing combustion acts as a thermal buffer, storing heat during one phase and releasing it during the other, thereby mediating the temperature fluctuations that would otherwise result from reduced combustion air flow and ensuring stable operating temperatures despite lower oxygen availability.
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 allows the use of sulfur-containing raw materials and fuels, achieving a significant increase in gaseous sulfur dioxide concentration and maintaining low sulfur content in the lime product, while optimizing energy consumption and operational conditions.
Implementation Method 1
The production of quick lime (CaO) by the decarbonatation of lime stone
Implementation Method 2
specific consumption. Specific consumption is the quantity of heat used to produce one kg of lime
Implementation Method 3
mobilize sulfur in a gaseous form, specifically by reducing combustion air flow, increasing temperature
Implementation Method 4
the sulphur from the fuel is in the majority extracted from the smoke
Data Source
AI summary
The invention relates to a method for producing quick lime from lime stone in a continuous regenerative shaft kiln, characterized in that, starting with standard conditions of excessive combustion air for the operation of this kiln, it especially includes a step where the excessive combustion air is progressively reduced until a content greater than 1000 ppm (in volume) of carbon monoxide is reached in the connection flue between the tanks. An increase in the content of gaseous sulphur dioxide is then observed in the gas flue, with respect to a kiln operated in standard conditions.