Brazilian sugar mills face a descaling problem that changes across the evaporator train. Scale in the first bodies is dominated by calcium phosphate. By the last body, silica becomes the main component. A cleaning programme that treats the whole train the same way will leave silica scale behind in the last effects, and that residual scale becomes a nucleation site for the next cycle.
Innovacorp supplies descaling chemicals for sugar mill evaporators, covering both alkaline cleaning and chelant-based removal. We work with mill process teams to match the cleaning sequence to the actual scale composition in their evaporator train.
The technical literature on sugarcane evaporator descaling is clear on one point: silicate-containing scales are difficult to remove with acid alone. This is not a product limitation — it is a chemistry issue. Silica does not dissolve in acid the way calcium carbonate does.
The effective approach is a two-step sequence. Alkaline cleaning with caustic soda breaks down the organic and silica matrix, converting polymeric silica into a more soluble monomeric form. Then an acid or chelant step removes the remaining mineral scale. Research on sugarcane heat exchanger deposits confirms that the order matters: alkaline first, then acid or EDTA.
A chelating agent like EDTA works differently from acid. It complexes calcium ions, keeping them in solution rather than allowing them to precipitate. For calcium sulfate scale that resists acid dissolution, EDTA can be effective because it works at high pH and targets the calcium directly.
A published case study from a Brazilian cane sugar plant describes the operational reality of evaporator fouling. The plant operates continuously with multiple evaporation stages. Due to high throughput, deposits build up regularly, and cleaning is performed every two to three weeks using 19.1% caustic soda, totaling 47 cleaning cycles per year.
The mill later added a cleaning additive directly to the caustic soda solution. The goal was to reduce caustic concentration and improve cleaning efficiency without changing the cleaning parameters. The case demonstrates that cleaning frequency and chemical consumption are linked to how effectively the alkaline step is designed, not just the acid step that follows.
| Evaporator Body | Dominant Scale | Cleaning Focus |
|---|---|---|
| First bodies | Calcium phosphate | Acid or chelant removal after alkaline conditioning |
| Middle bodies | Mixed calcium salts | Standard alkaline + acid sequence |
| Last body | Silica-heavy | Alkaline step critical to open silica matrix; chelant may be needed |
The same principle applies to juice heaters and vacuum pans. Heaters foul less rapidly because of higher juice velocity, but they still require periodic cleaning. Vacuum pans and crystallizers can accumulate scale that interferes with boiling and crystal growth.
| Product Type | Typical Form | Key Parameter |
|---|---|---|
| Alkaline cleaner | Liquid (caustic-based) | NaOH concentration, additives |
| Acid descaler | Liquid (inhibited) | Active acid content, inhibitor type |
| Chelant (EDTA-based) | Liquid or powder | EDTA concentration, pH |
Specific values depend on the product selected. Final specification to be confirmed before shipment.
Dosage depends on the scale thickness, the evaporator body, and the product selected. The cleaning sequence is as important as the dosage. A typical programme for composite scale follows this order:
For mills using mechanical cleaning with roseta scrapers, the ANP investigation report on an evaporator accident notes that this method requires confined space entry under NR-33, with proper permits and PPE. Chemical cleaning avoids the confined space entry requirement for the tubes, though chemical handling precautions still apply. The anti-scalant for evaporators page covers preventive treatment that can reduce cleaning frequency.
Standard industrial packing. Pack sizes on request.
Store in a cool, dry area away from incompatible materials. Follow standard chemical handling precautions for alkaline and acid products. Keep containers closed when not in use.
We support mill process teams with cleaning sequence design and product selection. Share your scale analysis (if available), evaporator configuration, and current cleaning practices, and we will recommend a starting sequence. Final programme to be confirmed through plant trial.
Scale composition changes across the evaporator train. Calcium phosphate dominates in the first two bodies, while silica becomes the main component in the last body. Silica-containing scales are difficult to remove with acid alone. The effective approach is a two-step sequence: alkaline cleaning (caustic soda) first to break down the organic and silica matrix, converting polymeric silica to a more soluble form, followed by acid or chelant cleaning to remove the remaining mineral scale.
A published Brazilian mill case describes cleaning every two to three weeks using 19.1% caustic soda, totaling 47 cleaning cycles per year. The mill later added a cleaning additive to the caustic soda solution to improve efficiency and reduce caustic concentration. For composite scale, the recommended sequence is alkaline cleaning first, followed by acid or chelant treatment. The order matters because alkaline cleaning opens the deposit structure for the subsequent acid step.
EDTA (ethylenediaminetetraacetic acid) works by complexing calcium ions, keeping them in solution rather than allowing them to precipitate as scale. Unlike acid cleaning, which relies on pH reduction, EDTA works at high pH and is particularly effective for calcium sulfate scale that resists acid dissolution. A Brazilian product for sugar mills uses concentrated EDTA as an anti-scalant to prevent crystal formation. In cleaning applications, EDTA can be used as the second step after alkaline treatment.
Mechanical cleaning methods like roseta scrapers require confined space entry, which falls under NR-33 (Brazilian regulatory standard for confined spaces). The ANP investigation report on an evaporator cleaning accident noted that work in confined spaces with rotating equipment requires proper permits and PPE. Chemical cleaning eliminates the need for confined space entry in the evaporator tubes, reducing this safety risk. However, chemical handling still requires appropriate precautions.
If you are reviewing a descaling programme for a Brazilian sugar mill evaporator train, call +91-9312871070 to discuss your scale composition and cleaning sequence.
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