How to online calibrate zero drift and temperature compensation for loss-in-weight feeders and Coriolis mass flow meters in high-viscosity fluids?

● Push: displace dope A under laminar flow (Re < 2000) with high-purity solvent until a clear interface forms to maximize physical displacement.

● Clean (CIP): run preset CIP using the same or compatible solvent for the next dope B for forced circulation flushing.

● Verify: inline sampling with UV spectrophotometer or inline viscometer; when key indices (e.g., absorbance) reach baseline and stabilize, cleaning passes.

● Quantification: optimize CIP time, flowrate, and solvent volume based on verification data to achieve minimal consumption with assured effectiveness.

● Anti-plugging: install low-speed bottom agitators (5–10 rpm) with ultrasonic anti-settling (28 kHz, 100 W) to prevent sedimentation. Add inline filters (50 μm) and schedule regular back-blow cleaning.

● Steady-state control: link a mass flow meter (±0.2%) with a VFD pump for real-time control, keeping flow fluctuation ≤ 1%. Example: in PVDF/DMAc, this cut spinning diameter CV from 8% to 2%.

● Dissolving area: ISO 7; 22°C ± 1°C; RH ≤ 60%; dew point ≤ 15°C. Dehumidifier with ±1°C dew point control to limit solvent-driven humidity increases.
● Feeding room: ISO 6; 20°C ± 0.5°C; RH ≤ 55%; dew point ≤ 12°C. Local laminar flow hoods (0.45 m/s) to keep the feeding process clean.

● Spinning room: ISO 5; 18°C ± 0.3°C; RH ≤ 50%; dew point ≤ 10°C. Dual-stage filtration (pre + HEPA) and constant T&RH AHU to maintain ultra-clean conditions.

● Pulsation damping: install pulsation dampers at pump outlet (N2 charge at ~60% of system pressure) to reduce flow ripple from ±15% to ±2%. For viscous PSf dopes, this markedly stabilizes spinning.
● Resonance isolation: conduct modal analysis to find natural frequencies of pump–piping; shift pump speed away from resonance (e.g., 50 Hz → 35 Hz). Add flexible compensators (length ~5× pipe ID) to attenuate vibration transmission.

● Semi-automatic: time = manual disassembly (T1) + cleaning (T2) + reassembly (T3). Example: PVDF/DMAc to PES/NMP, T1 = 45 min, T2 = 60 min (3× line volume flush), T3 = 30 min; total 135 min.
● Fully automatic: time = automatic flush (T4) + system self-check (T5). Example with integrated CIP/SIP: T4 = 20 min (1.5× volume), T5 = 10 min; total 30 min.

● Solvent consumption:
● Semi-automatic: mass = line volume (V) × flush factor (n) × solvent density (ρ). Example: V = 50 L, n = 3, ρ = 0.95 g/cm³ → 142.5 kg.

● Fully automatic: with optimized segmented/variable-flow flushing, n can drop to 1.2 → 57 kg; ~60% saving.

● Pressure-gradient method: install pressure sensors across the filter to compute ΔP. Warn at 150% of initial ΔP; force shutdown/replacement at 200%. In PVDF hollow fiber production, this yields ~92% accuracy in filter life prediction.
● Particle counting: install a laser particle counter downstream to monitor ≥ 5 μm counts. If counts jump by 50%, initiate backflush; if post-flush counts remain > 100/mL, declare filter failure.
● Maintenance window optimization: model clogging rate with historical data (e.g., ΔP/t = kC, C = contaminant concentration) to adjust cleaning intervals dynamically. For high-solids PAN solutions, this can reduce unplanned downtime by 70%.