Air Preheater for Large Blower Units in Pharmaceutical Factories

Air Preheater for Large Blower Units in Pharmaceutical Factories

Process Purpose

Preheat the air entering the blower to reduce subsequent heating energy consumption (e.g., drying, sterilizing link) and improve energy utilization.

Avoid cold air to cause blower blade condensation, corrosion, prolong the life of the equipment.

Special industry requirements

Cleanliness: in line with GMP (Good Manufacturing Practice), to avoid secondary air pollution, the material needs to be corrosion-resistant, no leakage, easy to clean.

Safety: to prevent cross-contamination, may come into contact with drug dust or corrosive gases, need to be resistant to high temperature and media erosion.

Stability: to adapt to the continuous operation of the pharmaceutical process needs to reduce the frequency of downtime maintenance.

Air preheater type and selection recommendations

1. Plate air preheater (recommended first choice)

Advantages:

High-efficiency heat transfer: plate corrugated structure to increase the heat transfer area, heat transfer coefficient of up to 2-3 times that of the tubular heat exchanger, suitable for large flows of air to warm up quickly.

Compact structure: the volume is more than 50% smaller than the tube type, saving installation space, suitable for the compact layout of the blower group.

Convenient cleaning: removable plate design (such as all-welded + removable combination structure), easy to disassemble and clean regularly, in line with the pharmaceutical industry health requirements.

Optional materials: 316L stainless steel, titanium alloy and other corrosion-resistant materials, smooth surface is not easy to accumulate dust, to avoid the adhesion of drug dust.

Applicable scenes: air flow ≤ 50000 m³/h, heat source is steam, hot water or low temperature waste heat (temperature ≤ 200 ℃).

2. Tubular Air Preheater (Reliability Priority)

Advantages:

High Pressure / High Temperature Resistance: Steel tube structure can withstand high air pressure (e.g. blower outlet pressure ≥ 50kPa), suitable for high temperature heat source (e.g. thermal oil, flue gas waste heat, temperature ≤ 400℃).

Strong anti-scaling ability: the air flow rate in the tube can be optimized design to reduce the accumulation of dust, suitable for air conditions containing a small amount of particles.

Disadvantages: heat transfer efficiency is lower than plate type, larger volume, cleaning requires special tools (such as mechanical blowing or chemical cleaning).

Design Key Points

1. Heat Source Matching and System Integration

Type of Heat Source:

Steam Heat Source: Use spiral plate or tube heat exchanger, design condensate discharge system to avoid water hammer effect.

Waste heat recovery (such as boiler flue gas, dryer exhaust): the need to set up a pre-filtering device to prevent dust blocking the channel, the material selection of corrosion-resistant flue gas corrosion of ND steel or enameled pipe.

Control logic:

linkage blower frequency conversion system, according to the air flow automatically adjust the flow of heat source, to avoid overheating or insufficient heat exchange.

2. Material and surface treatment

Main body material:

Sheet/tube: 316L stainless steel (acid and alkali resistant), 304 stainless steel (dry and clean air), Hastelloy is optional for contact with corrosive gases.

Seals: food-grade silicone rubber or polytetrafluoroethylene (PTFE), temperature resistance ≥ 200 ℃ and no volatiles.

3. Anti-pollution and maintenance design

Anti-dust deposition structure:

Plate heat exchanger adopts large angle corrugated plate (such as herringbone corrugation) to enhance airflow disturbance and reduce dust deposition; Tube heat exchanger can be equipped with removable tube box for easy mechanical cleaning.

Online monitoring:

Installation of differential pressure sensors, real-time monitoring of heat transfer resistance, triggering an alarm when the standard is exceeded, prompting cleaning or overhaul.

Typical Application Scenarios in Pharmaceutical Industry

Drying Process of API

The blower provides hot air for the fluidized bed dryer, and the air preheater uses steam to preheat the air from 20℃ to 80-120℃, which reduces the steam consumption by about 15%-20%.

Ventilation system for aseptic workshop

Preheat the fresh air to maintain constant temperature in the workshop, using stainless steel plate heat exchanger with high efficiency filters to ensure air cleanliness up to ISO 7 standard.

Exhaust gas treatment system

preheats organic waste gas entering RTO (Regenerative Thermal Incinerator), utilizes waste heat recovery from incineration exhaust gas, reduces energy consumption of the blower and improves the efficiency of waste gas treatment.