Ethanol losses during degassing in fermentation tanks represent one of the least monitored—yet most impactful—phenomena from a technical, economic, and environmental standpoint in sugarcane mills. Experimental studies conducted in Brazil demonstrate that, especially above certain condenser temperature ranges, losses can reach significant values, exceeding millions of reais per harvest.
This article presents a largely technical approach based on continuous analytical instrumentation, using gas-phase ethanol measurement (%LEL), sample conditioning systems, and correlation with process variables. The proposal goes beyond measurement: it transforms analytical data into direct economic indicators, creating a new frontier for operational monetization.
Context of the ethanol loss process during degassing
During alcoholic fermentation, yeast metabolism generates large volumes of CO₂, which carry with them ethanol vapor and other volatile compounds. This gaseous flow is directed to degassing and condensation systems, whose primary objective, historically, is not the recovery of ethanol, but the control of the process.
However, experimental measurements demonstrate that:
- Ethanol losses increase sharply with rising condenser temperatures;
- Above ~50 °C, the losses cease to be residual;
- Small temperature variations generate disproportionate economic impacts.
The biggest challenge has always been the reliable and continuous measurement of these losses in the gas phase.
Limitations of traditional approaches
Conventional methodologies for evaluating degassing losses are generally based on:
- One-off collection campaigns;
- Gas scrubbing and laboratory analysis;
- Indirect inferences over extended periods.
Although technically valid, these approaches have clear limitations:
- They do not allow real-time action;
- They do not create continuous operational indicators;
- They cannot handle day-to-day managerial decisions.
Continuous analytical instrumentation emerges as a natural evolution of this scenario.
Fundamentals of ethanol measurement in %LEL
Ethanol has a Lower Explosive Limit (LEL) of 3,1% vol in air. Measurement in %LEL, widely used for industrial safety, can be applied with high efficiency for quantifying losses when correctly conditioned and interpreted.
Reading in %LEL offers important advantages:
- High industrial robustness;
- Excellent repeatability;
- Compatibility with classified areas;
- Quick response to process variations.
When combined with appropriate sample conditioning systems, the %LEL measurement becomes a reliable quantitative variable for economic analysis.
Conditioning and analysis system
The Alutal solution is structured in three technical layers:
Representative collection
- Continuous extraction of degassing gas;
- Heated lines to prevent condensation;
- Design suitable for mixing CO₂ and ethanol vapor.
Sample conditioning
- Controlled condensate removal;
- Thermal stabilization;
- Fine and coalescing filtration;
- Sample preparation under ideal analyzer conditions.
Analysis and integration
- Gas analyzer calibrated for ethanol (%LEL);
- Integration with PLCs and SCADA systems;
- Continuous data acquisition for loss calculation.
This architecture ensures metrological reliability and system longevity.
Technical conversion: from %LEL to financial impact
One of the distinguishing features of the Alutal approach is the direct conversion of the analytical variable into economic indicators.
Conversion chain
- %LEL → %VOL of ethanol
- %VOL → mg/Nm³
- mg/Nm³ → kg/h
- kg/h → L/h
- L/h → R$/h
With realistic assumptions regarding gas flow and ethanol prices, seemingly low %LEL readings quickly translate into significant losses per day and per harvest.
This conversion transforms analytical instrumentation into a financial management tool.
Correlation with process variables
Continuous measurement enables robust statistical analyses, such as:
- Condenser temperature × %LEL;
- Temperature × L/h of ethanol lost;
- Identifying optimal operating points;
- Evaluation of the efficiency of gas scrubbers.
These correlations allow you to migrate from a reactive operation to a data-driven operation.
Executive dashboard: data that drives decision-making.
The analytical data is consolidated into dashboards that serve two levels:
Efficiency
- Instantaneous and average LEL;
- Deviation alarms;
- Thermal monitoring.
Managerial
- Ethanol lost (L/day and harvest);
- Financial impact (R$/day and R$/crop);
- ESG and environmental indicators.
Thus, the operator acts in the process and management acts in the result.
Analytical instrumentation as a monetization platform
The major paradigm shift is to treat analytical instrumentation not as a cost, but as an economic asset.
The solution allows:
- Justify investments with a payback period of less than one harvest;
- Structuring performance contracts (Shared Savings);
- Create auditable metrics for cost savings generated;
- Aligning industrial efficiency, safety, and sustainability.
- Conclusion
Ethanol losses during degassing are no longer an invisible phenomenon. With appropriate analytical instrumentation, it is possible to measure, correlate, monetize, and reduce these losses in a continuous and structured way.
Alutal integrates process engineering, online analysis, and economic intelligence to transform analytical instrumentation into a strategic asset for sugar and ethanol plants. It's not just about measuring gases, but about generating reliable data that supports operational decisions, reduces losses, and enhances industrial competitiveness.
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Also read the article: learn about the raw material ethanol and find out which one Brazil is a leader in.
