Case Study #9:
Plastic Heat Exchangers in Galvanizing
Initial situation
Galvanizing operations demand precise temperature control in their acid pickling tanks, particularly during the colder winter months. Traditional metallic heat exchangers often exposed to aggressive hydrochloric acid require frequent replacement due to corrosion and scale buildup, leading to costly downtime and maintenance headaches. The customer sought a more durable, long-term solution for maintaining optimal tank temperatures in a challenging environment.
Challenge
A leading steel galvanizer needed to heat and maintain one of their hydrochloric acid pickling tanks at a steady 70°F (21°C) during winter. The tank, measuring 57 feet in length, 9 feet in width, and 11 feet in height (operating level 124”), was open-topped and primarily heated via 15 PSI steam. The acid concentration ranged from 4% to 16%, with process material loads up to 10,000 lbs/hour in ambient winter temperatures (25-30F). The solution required:
- A heat exchanger that could withstand hydrochloric acid at varying concentrations
- Corrosion resistance far superior to traditional metal units
- Installation on the tank’s end wall to minimize disruption
- Consistent heating performance, eliminating the need for frequent shutdowns or replacements
Solution
CALORPLAST Immersion-Type Heat Exchangers constructed from high-performance, acid-resistant thermoplastics. The plastic design offers complete immunity to hydrochloric acid corrosion, eliminating the risk of premature failure that plagued metallic exchangers.
Key features included:
- Custom Fit: Heat exchangers were sized to fit the tank’s end wall, maximizing thermal efficiency without obstructing process operations.
- Materials: All-wetted surfaces constructed of corrosion-resistant thermoplastic, ensuring no metal contamination or structural degradation.
- Performance: Units designed for direct immersion, delivering consistent steam heating to maintain the 70°F target, even as fresh, ambient-temperature steel entered the process.
- Longevity: Plastic construction virtually eliminates routine maintenance and replacement, reducing downtime and total cost of ownership.
Result
- Efficient, uniform acid heating ensured optimum conditions for vanadium extraction, improving process yield and throughput.
- Long-term reliability: All-plastic construction eliminated corrosion issues, reducing maintenance and total cost of ownership.
- Operator and plant safety: Engineered safeguards and pressure management features supported safe, continuous operation.
- Quick installation: Skid-mounted and custom manifolding simplified field integration, minimizing production downtime.
By utilizing CALORPLAST PVDF heat exchangers, the facility achieved a durable, efficient, and maintenance-friendly heating solution for its critical extraction process.
