Project: Air Handling Fresh Air Unit System for a Polysilicon Reduction Workshop in Ningxia

Project Overview

A polysilicon reduction workshop in Ningxia requires a controlled indoor environment with a relative humidity of 50%-70% and a temperature of 24-26°C. However, the reduction furnaces continuously release significant amounts of process waste heat during production, leading to a substantial temperature rise and creating a massive heat load. The production process necessitates a large exhaust system and a dedicated fresh air air-conditioning treatment system. Simultaneously, a certain cleanliness level must be maintained to prevent air dust and other contaminants from affecting product quality. Therefore, to ensure the required production environment and meet the stable temperature, humidity, and cleanliness requirements, energy-efficient and environmentally friendly fresh air unit air-conditioning equipment was selected for the design.

Solution Application

This project involves the deployment of 12 Aolan evaporative cooling clean-type composite wet-pad fan fresh air units. These are specifically designated for the fresh air cooling and humidification system serving the reduction halls of three workshops (A, B, and C) within this polysilicon project. Each reduction hall is equipped with 4 units, with a single unit rated for a supply air volume of 100,000 m³/h.

The equipment integrates comprehensive air handling functions including ventilation, cooling, heating, humidification, air purification, and noise attenuation. The summer cooling system employs a "surface cooling pre-cooling + wet-pad cooling" strategy. The pre-cooling section uses surface coolers with 4/7°C chilled water as the coolant; outdoor fresh air is pre-cooled by the surface cooler and then further cooled and humidified by passing through the wet pads. The heating section utilizes high-temperature hot water produced via steam exchange to meet winter heating demands. The humidification system incorporates triple modes: high-pressure micro-spray humidification, wet-pad humidification/cooling, and steam humidification (interface reserved), ensuring precise control of workshop humidity.

The units feature an intelligent control system that can flexibly operate different functional modules based on actual operational requirements to achieve energy savings and reduced consumption.

Performance Results

The project was completed, installed, commissioned, and put into operation in 2023. After system optimization, the equipment operates stably and reliably. Measured data shows that under local summer design conditions for temperature and humidity, the outlet air temperature from the units meets the design requirement of 20°C ± 2°C. The workshop environment consistently maintains the required relative humidity of 50%-70% and temperature of 24-26°C. These environmental conditions are also met under winter design conditions.

The air filtration system configured within the units – comprising primary, medium-high, and high-efficiency filters – ensures that the air cleanliness level in the reduction halls is consistently maintained at the Class 100,000 standard. All unit parameters meet the client's process and safety requirements.

The application of Aolan's evaporative cooling air handling fresh air units has effectively regulated the workshop temperature and humidity parameters, significantly improved indoor air quality, greatly reduced the impact of high temperatures, dust, and odors on operators, comprehensively optimized the working environment, and enhanced personnel comfort. This provides a solid guarantee for the safe and stable operation of polysilicon production.