Cement Plant Preheater Gas Extraction for High-CO2 Carbon Capture
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Solution Overview
Problem
The cement industry emits significant amounts of CO2, particularly during the decarbonation of raw meal, and existing carbon capture technologies are inefficient due to low CO2 content in exhaust gases at the stack, making them costly and energy-intensive.
Innovation Solution
Extract exhaust gas from the second highest or highest stage of the preheater string in a cement plant, cool it to <250°C, dedust it, and introduce it into a carbon capture installation where the CO2 content is >25 vol.-%, allowing for efficient CO2 separation and reuse of the CO2 lean gas to dry raw meal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If CO2 capture is performed at the exhaust stack, then CO2 can be captured from the final exhaust gas, but the CO2 content is too low for efficient and cost-effective removal
Solution Approach 1:
The patent applies preliminary action by extracting exhaust gas from the preheater system before it reaches the exhaust stack, where CO2 concentration is already diluted. By capturing CO2-rich gas upstream in the preheater where decarbonation occurs, the system performs CO2 capture before the harmful dilution effect of false air ingress reduces CO2 content to inefficient levels for capture
2Quantity of substance
If exhaust gas is extracted from the preheater string, then CO2 content increases to >25 vol.-%, but the temperature must be reduced to <250°C for carbon capture installation
Solution Approach 1:
The system performs preliminary cooling of the extracted high-temperature exhaust gas before it enters the carbon capture installation. By pre-cooling the gas to <250°C upstream, the subsequent CO2 capture process can operate at optimal temperatures for absorption or adsorption technologies, preventing thermal degradation of capture media while maintaining high CO2 concentration
Solution Approach 2:
The patent introduces a cooling intermediary system between the preheater extraction point and the carbon capture installation. This intermediary cooling mechanism serves as a mediator that transforms the high-temperature exhaust gas into a suitable temperature range for CO2 capture, enabling the connection between high CO2 content source and temperature-sensitive capture technology
3Productivity
If CO2 capture installation is added to increase CO2 removal efficiency, then CO2 capture efficiency improves, but device complexity increases
Solution Approach 1:
The patent merges the CO2 capture installation with existing cement plant infrastructure, particularly integrating it with the preheater system and exhaust gas handling infrastructure. By combining CO2 capture functionality with existing structural elements and process flows, the system achieves high CO2 removal efficiency while minimizing the addition of separate complex equipment
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
Increases the efficiency and reduces the energy consumption of carbon capture by enhancing CO2 content in exhaust gases, thereby improving the overall process efficiency and reducing CO2 emissions.
Implementation Method 1
cooling the exhaust gas to a temperature of <250°C
Implementation Method 2
CO2 is separated from the exhaust gas for obtaining a CO2 lean gas
Implementation Method 3
CO2 can be physically separated from a CO2 containing gas by means of adsorbents
Data Source
AI summary
A method of processing exhaust gas from a cement plant, the cement plant including one or several raw meal mills for milling a cement raw meal, one or several preheater strings, each having a plurality of preheater stages, and a rotary kiln, wherein the one or several preheater strings are for preheating the cement raw meal in counter-current flow with an exhaust gas from the rotary kiln. The method includes extracting the exhaust gas from a second highest or highest stage of at least one of the preheater string(s), cooling the exhaust gas to a temperature of <250° C., dedusting the exhaust gas, introducing the cooled and dedusted exhaust gas into a carbon capture installation, in which CO2 is separated from the exhaust gas for obtaining a CO2 lean gas, wherein the exhaust gas, when being introduced into the carbon capture installation, has a CO2-content of >25 vol.-%.