Pulsation Control in Hi-Temp Coffee Extraction Towers
Industry Served: Food & Beverage
Problem:
The Coffee Manufacturer operates interconnected vertical extraction towers where hot water is circulated at extreme temperatures to produce coffee extract. During operation, the customer observed:
- Rapid water evaporation above 175°C resulting in air pockets inside pipelines
- Slow-reacting temperature instruments, allowing entrained air to persist
- Centrifugal pumps forced to move both air and liquid, leading to:
• Severe water hammer
• Excessive piping vibration
• Damage to plate evaporators and instrumentation
• Partially filled distribution lines on startup, requiring air displacement before flow could stabilize—intensifying water hammer
These issues disrupted extraction quality, compromised equipment life, and increased maintenance cost.
A review of the extraction tower circulation system revealed two primary contributors to the instability:
1. Air Entrapment Due to High-Temperature Evaporation
At 175°C, water rapidly vaporizes. Air and vapor bubbles accumulated in the recirculation lines and plate evaporators. Because the system’s temperature instrumentation responded slowly, air remained trapped far longer than expected—allowing pumps to ingest and compress air repeatedly.
2. Pumping System Not Designed to Handle Vapor Pockets
The 1½” centrifugal pumps recirculating extract between stages were forced to push air through evaporators and distribution lines. This caused major hydraulic consequences:
- Violent pressure spikes (water hammer)
- Resonant vibration in vertical and horizontal piping sections
- Structural stress on evaporators and associated equipment
- This unstable flow environment also threatened extract consistency and overall process quality.
Solution:
To stabilize the process and protect equipment, the following actions were taken:
Installation of BLACOH SENTRY II Pulsation Dampeners
- Volume: 1.40 L
- Pressure rating: 1000 psi
- Material: Stainless steel 316
- Type: Adjustable
Dampeners were installed at the pump discharge of the first three extraction stages, where the majority of vapor formation and air entrainment occurred.
System Benefits
- Smooth, pulse-free flow into plate evaporators
- Meaningful reduction in pipeline vibration
- Significantly improved stability and accuracy of temperature instrumentation
- More consistent, higher-quality coffee extract
Result:
After installation of the BLACOH SENTRY II units, the customer reported:
- Near elimination of pipeline vibration
- Protection of instrumentation and critical evaporator components
- Reduced preventive maintenance, with extended evaporator plate life
- Overall improvement in system reliability and extract quality