Case study: large pharmaceutical facility solves moisture and contamination issues with new blower-regenerated adsorption dryers (–40°C dew point, oil-free). Equipment supplied, installation, and ROI metrics detailed.
Client Background: Yunnan Baiyao Group Co., Ltd., a leading pharmaceutical manufacturer in Yunnan Province, produces a range of products including traditional Chinese medicine and modern pharmaceutical products, some of which require ultra-clean, dry compressed air. The client’s existing air system served multiple production lines, but the aging dryers could no longer meet stringent ISO 8573-1 Class requirements. The plant operates 24/7, and even brief downtime causes huge losses and product waste.
Pain Points: The customer faced recurring moisture contamination in air lines. Existing refrigerated dryers occasionally allowed condensate carryover, risking sterility. Because the original system used small heatless dryers, huge volumes of purge air were lost (20–25% of throughput), wasting energy. In peak summer conditions, dewpoint spiked above –20°C, below specification. The client needed a dryer upgrade that would:
- Achieve a stable low dew point (≤–40°C) under all load conditions.
- Eliminate purge air loss (zero-purge operation) to cut energy use.
- Maintain oil-free air (since an oil-free screw air compressor upstream could not risk contamination).
- Fit within the existing compressor room layout without major plumbing changes.
Our Solution: We proposed a blower-regenerated, dual-tower adsorption dryer system customized for the plant’s flow. The scope included:
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Equipment: Four large Model HR-350SGRD adsorption dryers (2100 m³/h each, equivalent to 35 m³/min) with heated blower-assisted regeneration. Each dryer has twin stainless-steel towers filled with high-capacity desiccant(activated alumina + molecular sieve). Regeneration is performed by an electric heater (150–200°C) combined with a high-efficiency blower drawing ambient air, eliminating the need for compressed air during the purge process. Cooling is achieved using unheated ambient air through the same blower. As a result, virtually zero compressed air is consumed during operation. The system can consistently achieve a pressure dew point of ≤ –40°C under standard operating conditions, meeting ISO 8573-1 Class 2 requirements for water content.
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Air Filtration: Pre- and after-filters were supplied (0.01 μm FDA-grade coalescing filters) to ensure zero oil carryover.
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Control System: An advanced PLC controller (Sigma Electric Controls) sequences tower switching, monitors dew point (on-line sensor) and pressure, and optimizes blower speed. A touch-screen interface was provided for status and alarms. The system is integrated into the plant DCS for remote monitoring.
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Performance Specs: The dryers guarantee –40°C pressure dew point at full load (–70°C possible at part-load) with oil-free air quality (ISO Class 1 after filters). The blower consumes only 0.10 kW per m³/min, far lower than a heatless dryer’s purge losses.
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Air Filtration: Pre-filters (0.01 μm particulate filters, FDA-compliant materials) remove any residual pipeline dust or compressor wear particles; after-filters (0.01 μm) capture potential desiccant fines from the dryer towers, ensuring sterile-grade air quality for pharmaceutical lines.
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Control System: An advanced PLC controller (e.g., Siemens S7-1200 or equivalent) sequences tower switching, monitors dew point (online sensor) and pressure, and optimizes blower speed. A touch-screen HMI provides status and alarms. The system is integrated into the plant DCS for remote monitoring.
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Performance Specs: The dryers guarantee a stable pressure dew point of ≤ –40°C under full load and typical ambient conditions. The regeneration blower consumes typically 0.10–0.12 kW per m³/min of dryer capacity, which is significantly lower than the 15–25% compressed air purge loss of a heatless dryer. The output air quality meets ISO 8573-1 Class 1 for oil (≤0.01 mg/m³) and Class 2 for water (≤ –40°C PDP).
Figure: Cleanroom production line in a pharmaceutical facility (for illustration).
Delivery & Installation: The project followed a structured timeline: system design and engineering drawings were approved within 4 weeks. Factory Acceptance Testing (FAT) of the assembled dryers was completed in our plant before shipment. Delivery to site occurred 3 weeks after FAT. Installation (shown below) took 2 weeks: mounting, piping, electrical hook-ups, and control wiring.
After installation, we performed a 7-day start-up and commissioning phase, including Site Acceptance Testing (SAT) and documentation of operational qualification (OQ) per pharmaceutical standards. Parameters (dew point, energy use) were logged and showed immediate compliance. Operator training and a final acceptance report were delivered to the client.
Results/Benefits: The new zero-purge dryers resolved all issues. Key benefits include:
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Stable Dew Point: The air dew point is now consistently –45°C under full load, with peaks still below –40°C (vs –20°C previously).
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Energy Savings: Removing the compressed-air purge eliminated ~15% of the compressed air generation energy (i.e., the energy that would otherwise be wasted as purge air). Measured blower power is only ~10% of the additional compressor energy that a heatless dryer would consume due to its purge air loss. Estimated annual electricity saving is ≈¥160,000 (based on local industrial electricity rate of ¥0.8/kWh). For reference, eliminating purge losses typically saves 15–20% of compressor energy, which is significantly higher than the 10–12% savings from heat recovery methods.
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Reduced Maintenance: The blower-regeneration cycle runs continuously with minimal wear (no purge valves cycling). Desiccant life is extended. No unscheduled maintenance or failures have occurred during the first six months of continuous 24/7 operation, indicating strong reliability.
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Contamination Elimination: With oil-free compressors and fine filtration, the customer notes zero oil or moisture incidents since commissioning. Product quality has improved.
The customer is very satisfied with the turnkey solution. Performance metrics were logged to prove ROI: energy cost dropped by ~12%. Compared to the previous heatless dryers, the new system’s specific energy consumption (kW per m³/min) improved by 50%. The system paid for itself in <3 years.
As one plant engineer said: “The new dryers deliver rock-solid dry air and cut our power use – exactly what we needed.”
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