Introduction to Types of Exhaust Systems in Cleanrooms/Clean Production Plants

(1) General Exhaust System

This system is designed to discharge general waste gas from auxiliary production rooms and living facilities, such as duty rooms and restrooms. In most cases, this type of waste gas requires no special treatment and can be directly emitted into the atmosphere.

(2) Organic Gas Exhaust System

Common purification methods for organic exhaust gas include activated carbon adsorption, liquid absorption, and catalytic combustion:

Activated carbon adsorption is primarily used for treating organic exhaust gas (e.g., benzene and gasoline) with small to medium flow rates, which contains no dust or adhesive substances.

Liquid absorption features simple equipment and low energy consumption but has relatively low absorption efficiency.

Catalytic combustion is mainly applied to treat high-concentration organic exhaust gas, such as that containing benzene, alcohols, esters, and gasoline.

The selection of organic gas treatment devices should be based on the type and concentration of organic substances in the exhaust system.

(3) Acidic Gas Exhaust System

In product production, acidic gases are emitted during processes such as wet chemical etching, acid cleaning, and laboratory operations. For such acidic gas exhaust systems, wet scrubber towers are usually installed to treat the gas before it is discharged into the atmosphere.

(4) Alkaline Gas Exhaust System

When the gas in the exhaust system contains alkaline substances or alkaline chemical reagents are mixed into the exhaust gas, wet scrubber towers are typically used for treatment—similar to the acidic gas exhaust system—before the gas is discharged into the atmosphere. In recent years, due to increasingly stringent atmospheric emission standards, even exhaust gas with low concentrations of alkaline (or acidic) substances must undergo purification to meet the emission requirements.

(5) Hot Gas Exhaust System

Various furnaces, high-temperature sterilization equipment, and other devices in the production process emit hot gas. Since the temperature of the exhaust gas is relatively high, heat recovery or other treatment methods can be adopted in some cases. If the exhaust volume is small or treatment is impractical, the gas can be directly discharged into the atmosphere after necessary thermal insulation measures are implemented.

(6) Dust-Containing Exhaust System

Due to differences in product types and production processes, the nature and concentration of dust in the exhaust gas vary. Dust removal devices should be selected based on the nature and concentration of dust in the exhaust gas; common options include bag filters and filter devices equipped with filter elements.

Such devices can be maintained for long-term use through methods like rapping backblowing or replacing filter elements. For some dust-containing exhaust systems with extremely high dust concentrations, depending on the specific engineering conditions, it may be necessary to install secondary dust removal devices to remove most of the dust before the gas is sent to the aforementioned bag filters or filter dust collectors. This measure is essential to meet atmospheric emission standards and ensure stable, cost-effective operation.

(7) Special Gas Exhaust System

In the production of semiconductor integrated circuits, various special gases are often used—many of which are flammable, explosive, toxic, highly toxic, or corrosive. For such exhaust systems, the following requirements must be met:

First, exhaust systems must be classified according to the type and nature of the special gases to prevent chemical reactions within the exhaust system.

Second, dedicated waste gas treatment devices should be selected; treatment methods for special gas exhaust include dilution, absorption, adsorption, catalytic combustion, and more.

Third, the materials used for equipment and pipelines in the exhaust system must be selected based on the nature of the special gases in the exhaust, ensuring they do not react with the discharged special gases.

(8) Hazardous and Toxic Exhaust System for Pharmaceutical Production

In the production or dispensing of highly sensitizing drugs (e.g., penicillin), certain steroid drugs, as well as highly active and toxic drugs, and at the exhaust outlets of operation areas involving pathogens of biosafety level 2 or higher, high-efficiency air filters (HEPA) must be installed to minimize the risk of pollution. Additionally, the exhaust outlets of such exhaust systems (which discharge into the atmosphere) should be maintained at a certain distance from the fresh air inlets of other purified air-conditioning systems used in pharmaceutical production.