I. First Understand the "Temper" of the Scale
Hard and brittle calcium carbonate and rust scale suit chemical dissolution; loose dust and slime suit physical flushing; a mixture of both requires a combination. Before cleaning, it is best to take a scale sample to judge, avoiding "wrong medicine."
II. Chemical Cleaning
- Acid washing: Hydrochloric, citric, sulfamic acid, etc. dissolve carbonates and oxides; requires a corrosion inhibitor to protect the metal;
- Alkali washing: Sodium hydroxide, sodium carbonate remove grease, biological slime, and silica scale;
- CIP (clean-in-place): No disassembly, circulating cleaning fluid, suitable for food, pharmaceutical, and other frequent-cleaning scenarios.
Advantages: Reaches dead corners, friendly to complex channels; Risks: Corrodes the base metal, waste liquid treatment, residues affecting the medium. Strong-acid cleaning must have a corrosion-inhibition plan and strictly control time and concentration.
III. Physical Cleaning
| Method | Applicable | Feature |
|---|---|---|
| High-pressure water jet | Shell-and-tube tube interior, plate surface | Direct and effective, requires shutdown and disassembly |
| Online brushing (sponge ball) | Shell-and-tube condenser tubes | No shutdown, periodic circulating brush |
| Ultrasonic/vibration | Precision, fragile parts | Gentle, removes weakly adhered scale |
Physical cleaning has no chemical pollution and does not damage the base metal, but is often inadequate for "tightly bitten" hard scale and narrow channels.
IV. How to Choose: A Decision Table
- Removable plate, loose scale → Disassemble and use high-pressure water + brushing, cleanest;
- Non-removable, hard scale → Chemical cleaning (with corrosion inhibitor);
- Continuous production cannot stop → Online brushing / online chemical circulation;
- Food and pharmaceutical → Prefer CIP, compliant and auditable.
The goal of cleaning is to "restore K," not to "soak the equipment rotten." Chemical cleaning always puts corrosion inhibition and waste liquid treatment first.