Product Origin

In recent years, as the linewidths used in electronic circuit manufacturing have continued to shrink, reaching nanometer-scale dimensions, and given the extremely high density of factory sites in certain regions, cross-contamination from exhaust gases has become a significant concern. As a result, concerns about process-induced environmental pollution have shifted from particulate solid pollutants to gaseous molecular contaminants (AMCs), such as SOx, NOx, CO, NH₃, HCl, and other organic pollutants. While AMCs generated within cleanrooms themselves can be effectively removed by chemical filters installed on fan-filter units (FFUs), external air must rely on MAU chemical filters or water-based humidification systems for purification. Although chemical filters boast high efficiency, they are costly and their expense increases proportionally with the volume of external air processed. Moreover, when the external air contains high concentrations of particulates or is highly humid, the lifespan of these filters is significantly shortened, which has historically limited their widespread adoption in the electronics industry. By contrast, water—a readily available, inexpensive liquid with excellent gas-absorbing properties—has emerged as an ideal solution for removing AMCs. Additionally, water-based humidification systems have proven effective in cooling air and regulating temperature. Consequently, water-based humidification systems have gradually become the mainstream approach for eliminating chemical pollutants in the electronics industry today.

Working principle

Using water as the medium, the water is pressurized by a pump and then atomized into water particles of a specific diameter range through specially designed nozzles. These water particles collide with, mix with, and undergo heat and mass transfer with the flowing air, dissolving airborne AMC, VOC, and particulate matter, thereby effectively removing these contaminants from the air and purifying it. Humidification is merely an ancillary function of this product.

Three basic types

(1) Spray-type: Outside air passes through a flow-distribution plate to achieve uniform airflow, and then is directed through a network of spray nozzles arranged in a mesh pattern, creating a curtain of fine water mist that increases the relative humidity of the air. Finally, the air passes through a water-deflecting baffle to filter out impurities and remove any residual water droplets. Only after this treatment is the air discharged from the outlet. A circulating water pump is required to continuously circulate water between the water tank and the spray nozzles; when the water level drops below a certain threshold, the system automatically replenishes the water. Example: a water-washing humidification system.

(2) Spray-type: Nozzles are evenly distributed, and high-pressure water is atomized into smaller water droplets through the nozzles, facilitating easier contact with air and thereby increasing the humidity of the air. An example is the combination of a high-pressure micro-mist humidification system with a water-deflecting baffle.

(3) Cellular type: For example, a wet-film circulating water system equipped with a water tank.

Function

The primary function of a wash-type humidification system is to filter and purify the air. Cooling and humidification are merely ancillary functions.

Terms of Use

(1) Ambient temperature: 4℃~45℃

(2) Ambient humidity: ≤85% RH

(3) Water quality: Use clean tap water, softened water, with a pH value of 6-7.

(4) Water supply pressure: 0.2–0.6 MPa

(5) Water supply temperature: 4℃–45℃

(6) Airflow velocity: 0.5–3.5 m/s

(7) Inlet air temperature: 4℃–65℃

Main uses

(1) Air washing and electrostatic elimination: wafer fabrication facilities, optoelectronic plants, chemical industries, petrochemical plants, synthetic fiber plants, electronics factories, nuclear power plants, etc.

(2) Agricultural cultivation: greenhouses, inoculation rooms, sterilization rooms, etc.

(3) Drying and humidification: Hospitals, textile mills, printing plants, food processing facilities, etc.

Product components

(1) The water-based humidification system is primarily installed in fresh-air air handling units and packaged air conditioning units. It mainly consists of a circulating water tank, a pressurized water pump, nozzles and piping systems, a flow-distribution plate, a water-deflecting baffle, and a control system.

(2) The circulating water tank is made of stainless steel and is equipped with a circulation pipeline, an automatic water-inlet system, a forced-water-inlet device, a circulating water pump with a filtration system, an automatic overflow device, high- and low-water-level detection devices, and a tank-cleaning system.

(3) The nozzle and piping system can employ single-row spray, double-row spray, or triple-row spray. The number of spray nozzles is determined based on the requirements for the amount of water washing.

(4) The control system includes an LCD display operator (optional), a water level detection system, a water supply system, an automatic cleaning system for pH control, an automatic water supply system, and a pump operation protection and control system.

(5) The flow-distribution plate and water-deflecting plate can be made of ABS or PPS, or alternatively from perforated aluminum alloy or stainless steel.

Pros and Cons and Precautions

1. Operation and maintenance require employees with professional expertise and extensive experience.

2. If used in near-freezing climatic conditions, anti-icing protection equipment must be provided.

3. The machine occupies a small footprint but can handle large-scale air humidification tasks.

4. Although the make-up water is recycled, the frequency of water replacement must be relatively high to prevent the air from becoming excessively polluted. Therefore, it’s important to consider whether the water source is sufficient and whether the water costs are excessively high.

5. Precise control is possible, but it requires the installation of a highly integrated control system, which comes at a considerable cost.

6. If waste heat can be utilized, considerable energy costs can be saved.

7. Dusty and polluted air must be filtered before undergoing the humidification process.

8. Moss and bacteria may grow inside the machine; therefore, regular maintenance, repairs, and chlorine disinfection are required.

9. The horsepower requirement for windmills is significantly higher than that of ordinary ones.