Multi-Shaft Kiln CO2 Capture via Buffer and Oxygen Combustion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The lime production process generates significant CO2 emissions due to the decarbonation of limestone, and existing CO2 capture technologies face challenges in adapting to intermittent processes like parallel flow regenerative kilns, leading to increased energy consumption and production costs.
Innovation Solution
A decarbonation process in a multi-shaft vertical kiln with oxygen-enriched combustion and a buffer system to maintain continuous exhaust gas flow, allowing for high CO2 concentration and efficient CO2 recovery, which is then purified for sequestration or utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If parallel flow regenerative kilns are used with intermittent combustion cycles, then energy consumption is reduced to 3.6 GJ per ton of lime, but CO2 capture becomes difficult due to intermittent exhaust gas flow
Solution Approach 1:
The buffer system is prepared in advance to store exhaust gas during combustion phases, ensuring continuous supply to CO2 capture units during reversal phases when combustion is interrupted. This preliminary storage action resolves the intermittency issue before it affects CO2 capture operations.
Solution Approach 2:
A buffer system acts as an intermediary between the intermittent exhaust gas flow from the regenerative kiln and the continuous operation requirements of CO2 capture technology. The buffer decouples these two processes, allowing the kiln to operate on its efficient intermittent cycle while maintaining continuous CO2 capture.
2Quantity of substance
If conventional air combustion is used, then CO2 concentration in flue gas is limited to 15-20 vol %, but if oxygen-enriched combustion is used, then energy consumption increases
Solution Approach 1:
The combustion process parameters are changed by enriching the comburent with oxygen instead of using conventional air. This parameter change increases the CO2 concentration in the exhaust gas from 15-20 vol% to potentially much higher levels, improving the efficiency of subsequent CO2 capture operations.
3Object-generated harmful factors
If CO2 capture technology is implemented, then CO2 emissions are reduced, but production costs increase due to additional energy consumption and equipment investment
Solution Approach 1:
The buffer system enables continuous operation of the CO2 capture unit by maintaining a continuous supply of exhaust gas, even when the kiln operates in intermittent combustion cycles. This continuity improves the efficiency and economics of CO2 capture by avoiding repeated startup and shutdown of the capture equipment.
Solution Approach 2:
Oxygen-enriched combustion is used to accelerate the oxidation process and increase CO2 concentration in the exhaust gas. This produces a more concentrated CO2 stream that is easier and more economical to capture and process, reducing the energy and equipment costs associated with CO2 capture.
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 continuous CO2 capture with high decarbonation grade and reduced energy consumption, minimizing the production costs associated with CO2 capture and storage while maintaining high production throughput of quicklime.
Implementation Method 1
featuring a buffer for accumulating exhaust gas from the first and second shafts
Implementation Method 2
a CO2 purification unit for purifying CO2 from the exhaust gas
Implementation Method 3
heating carbonated materials by a combustion of at least one fuel with at least one comburent, preferably said comburent comprising less than 70% N2 (dry volume), more preferably less than 50% of N2 (dry volume), in particular said comburent being oxygen-enriched air or substantially pure oxygen, up to a temperature range in which carbon dioxide of the carbonated materials is released
Data Source
AI summary
The present disclosure relates to a decarbonation process of carbonated materials, in particular limestone and dolomitic limestone, with CO2 recovery in a multi-shaft vertical kiln (MSVK) comprising a first and a second shaft with preheating, heating and cooling zones and a cross-over channel between each shaft. The method includes alternately heating carbonated materials by a combustion of at least one fuel with at least one comburent, up to a temperature range in which carbon dioxide of the carbonated materials is released, the combustion of the fuel and the decarbonation generating an exhaust gas. Decarbonated materials are cooled in the cooling zones with one or more cooling streams. The process further includes extracting the exhaust gas from the multi-shaft vertical kiln and feeding a buffer with the extracted exhaust gas.