Dab tsi yog Qhov Siab Tshaj Tawm Dej Hardness (ppm CaCO₃) Rau Qib 7 Titanium Sheath rhaub hauv A 5% Sodium Tripolyphosphate Solution Ntawm 90℃Los Tiv Thaiv Calcium Phosphate Scale-Induced Overheating?
Jul 16, 2026
Tso lus
In 5% sodium tripolyphosphate (STPP) at 90°C, calcium ions precipitate as calcium phosphate (Ca₃(PO₄)₂) scale. This scale has low thermal conductivity (0.3–0.6 W/m·K). The maximum allowable water hardness (as CaCO₃) to prevent overheating is 100 ppm. Above 100 ppm, scale thickness exceeds 0.2 mm within 500 hours, causing >30% txo cov cua sov hloov.
Quantitative Scale Formation vs. Dej Hardness
Hauv 5% STPP ntawm 90℃rau 500 teev:
| Hardness (ppm CaCO₃) | Scale Thickness (µm) | Scale Composition | Txo cov cua kub hloov (%) |
|---|---|---|---|
| 0 | 0 | Tsis muaj | 0 |
| 50 | 10–30 | Calcium phosphate | 5–15 |
| 100 | 30–70 | Calcium phosphate | 15–30 |
| 150 | 60–120 | Muaj calcium phosphate | 25–45 |
| 250 | 100–200 | Heavy nplai | 40–60 |
| 500 | 200–400 | Loj loj | 60–80 |
Cov nyhuv ntawm STPP Concentration thiab Kub
| STPP (%) | Kub (degree) | Max Hardness rau<0.1 mm Scale (ppm) |
|---|---|---|
| 3 | 90 | 150 |
| 5 | 80 | 150 |
| 5 | 90 | 100 |
| 5 | 100 | 60 |
| 10 | 90 | 50 |
Dej Hardness Control Guide
| Hardness (ppm CaCO₃) | Pom zoo ua | Cia siab Scale Thickness (µm / xyoo) |
|---|---|---|
| <50 | Tsis muaj | <30 |
| 50–100 | Saib xyuas txhua hli | 30–70 |
| 100–150 | Siv dej softened | 70–120 |
| >150 | Yuav tsum tau dej softener | >120 |
Kev pom zoo engineering
Rau STPP kev pab cuam ntawm 90 degree, tswj cov dej hardness hauv qab 50 ppm siv cov dej softener. Los ntawm kev tswj cov calcium concentration, tus engineer tiv thaiv calcium phosphate scale tsim thiab overheating.
