Twin Shaft Regenerative Kiln Inversion Time Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing calcination processes in twin shaft regenerative kilns for lime production are inefficient due to long stress relieving times, which are prolonged by the need to maintain blowers with frequency converters running continuously, leading to increased cycle times and energy consumption.
Innovation Solution
Implementing a process where blowers with frequency converters are stopped during certain steps of the calcination cycle, allowing pressure release through filters and eliminating the need for releasing and by-pass valves, thereby reducing inversion time and optimizing air and fuel management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blowers with frequency converters are kept running continuously during stress relieving process, then the furnace pressure can be maintained and controlled, but the inversion time is significantly prolonged and energy consumption increases
Solution Approach 1:
The pressure relief valve is opened in advance before the blower stops, allowing the furnace pressure to be gradually released through the valve rather than requiring the blower to run continuously during the entire stress relieving process. This preliminary action enables the system to maintain pressure control while significantly reducing the time the blower needs to operate.
2Loss of time
If blowers with frequency converters are stopped frequently during calcination cycles, then inversion time is reduced and energy consumption decreases, but the blowers require more frequent starting and stopping which may affect their reliability
Solution Approach 1:
The pressure relief valve is opened before the blower stops, allowing pressure to be released passively without requiring the blower to run continuously. This enables the blower to be stopped during the stress relieving process, reducing inversion time and energy consumption while maintaining system reliability through the valve's pressure management.
3Speed
If releasing and by-pass valves are used for stress relieving, then furnace pressure can be released quickly, but the process requires additional valves and increases device complexity
Solution Approach 1:
The pressure relief valve is designed to serve multiple functions: it acts as both a pressure relief device during stress relieving and a by-pass valve for air flow management during normal operation. This multi-functionality eliminates the need for separate releasing and by-pass valves, reducing device complexity while maintaining fast pressure release capability.
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 cycle times by 30-40%, increases production efficiency by 3-5%, minimizes noise, prevents powder release, and lowers electric energy consumption by approximately 35,000 Euros per year, while maintaining precise air adjustments for varying production levels.
Implementation Method 1
the blowers provided with frequency converters... continue working during the whole working cycle... the working system adjusts automatically the speed of each blower so that it is defined and reached the exact quantity of air calculated for each set of production
Implementation Method 2
thanks to the frequency converters installed on all the interested blowers, it is possible to adjust promptly the same to provide the exact quantity of combustion and cooling air needed for the process at any level of production
Implementation Method 3
fuel injection and combustion... the material... is subjected to a calcination process, i.e. it is introduced in suitable furnaces or limekilns where it is heated gradually to 800-1000°C
Implementation Method 4
a chemical reaction known as calcination reaction occurs, from which carbon dioxide is released and calcium oxide or burnt lime is produced; CaCO3 → CaO + CO2
Data Source
Figure 1
Figure 2~3
AI summary
Method for the production of lime carried out in a suitable twin shaft regenerative calcination furnace, said furnace comprising one or more blowers, all provided with frequency converters, and a plurality of process valves among which at least one releasing valve and at least one by-pass valve, said method, cyclically and alternately between the two shafts, comprising a step of fuel injection and combustion, a step of combustion nozzles washing and a step of lime discharge and limestone load, characterized in that during the washing, discharge and load steps, said releasing and by-pass valves are not moved since said blowers are kept off with consequent reduction of the furnace inversion time. As a consequence there are provided the following improvements in terms of efficiency as the inversion time reduction and the consequent increase in production, a total air flow rate according to the air excess, the absence of noise and powder coming from the releasing and stress relieving valves and a lower electric energy consumption.