In the clean room for microelectronics and the clean room for pharmaceutical production, it is often used or produced in the production process of various acidic and alkaline substances, organic solvents and general gases, special gases; in allergenic drugs, certain steroids The production process of body drugs, highly active and toxic drugs will also discharge or leak corresponding harmful substances into the clean room. For this reason, the production process equipment or process for the above-mentioned products may discharge various harmful substances, gases or dust Set up local exhaust device or full room exhaust device. According to the type of exhaust gas discharged from the production process, the exhaust device (system) can be roughly divided into the following types.

(1) General exhaust system

This refers to the general exhaust gas discharged in production auxiliary rooms and living rooms, such as duty rooms, toilets, etc. In most cases, it can be directly discharged into the atmosphere without special treatment.

(2) Organic gas exhaust system

When all kinds of organic substances and solvents are used as raw materials, auxiliary materials or cleaning agents in the production of products, the gas of organic substances and solvents will be emitted in the relevant places or equipment. Exhaust devices should be provided for such places or equipment . Under normal circumstances, the concentration of organic gas in the organic exhaust system is very low. If it can reach the atmospheric emission standard specified in the national standard, it can be directly discharged into the atmosphere without the need for an exhaust gas treatment device; when the organic gas concentration in the exhaust system When it exceeds the regulation, it shall be equipped with an organic gas treatment device, and it can only be discharged into the atmosphere after reaching the standard. The purification treatment of organic exhaust gas includes activated carbon adsorption method, liquid absorption method and catalytic combustion method. The activated carbon adsorption injection is mainly used for the treatment of small and medium flow benzene and gasoline organic exhaust gas without dust and sticky substances; liquid absorption Method, the equipment is simple, the energy consumption is low, but the absorption efficiency is not high; the catalytic combustion method is mainly used for the treatment of organic exhaust gas with higher concentrations of benzene, alcohols, lipids, gasoline and the like. The organic gas treatment device should select the corresponding treatment equipment according to the variety and concentration of the organic substances contained in the exhaust system.

(3) Acid gas exhaust system

In the production of wet chemical corrosion, acid cleaning, and acid gas discharge in the laboratory, the exhaust system of such acid gas is usually equipped with a warm scrubber absorption tower, which is discharged into the atmosphere after treatment, Figure 5- 56 is a form of several absorption scrubbers. In the actual design, the appropriate absorption liquid and the form of absorption tower should be selected according to the type and concentration of acid gas [20].

(4) Alkaline gas exhaust system

The gas in the exhaust system contains alkaline substances or alkaline chemicals are mixed in the exhaust gas. Similar to the acid gas exhaust system, it is usually treated with a wet scrubber absorption tower and discharged into the atmosphere. In recent years, due to the increasingly strict atmospheric emission standards, it is necessary to purify the exhaust gas containing low concentrations of alkaline substances (or acidic substances) in order to meet the emission standards. The gas (or acidic exhaust gas) can only be discharged into the atmosphere after reaching the standard. This kind of adsorbent is generally disposable, and it should be treated centrally after use. It is usually treated as solid waste by the urban garbage disposal site.

(5) Hot gas exhaust system

Hot air is discharged from various furnaces and high-temperature sterilization equipment in the production process. Due to the high exhaust temperature, heat recovery may sometimes be used. If the exhaust volume is small or it is inconvenient to handle it, take After necessary heat insulation measures are directly discharged into the atmosphere.

(6) Dust-containing exhaust system

In view of the different product varieties and different production processes, the dust properties and concentrations in the exhaust gas are different, and various types of dust removal devices should be selected according to the dust properties and concentration in the exhaust gas. Generally, a bag filter and a filter with filter elements are used Device [21], Figure 5-57 is a filter dust collector with filter element,

This type of device can take the way of backflushing or replacing the filter element, so that the dust removal device can be used for a longer period of time. For some exhaust systems with high dust concentration, according to the specific conditions of the project, it is necessary to install a secondary dust removal device to remove most of the dust before sending it to the aforementioned bag or filter dust removal device. In order to meet the requirements of the atmospheric emission standards, Therefore, it runs stably and economically.

(7) Special gas exhaust system

In the production of semiconductor integrated circuits, it is often necessary to use some special gases, many of which are flammable, explosive, toxic or even highly toxic or corrosive. For this type of exhaust system, the type and nature of the special gas should be first To divide the exhaust system, it is necessary to prevent the chemical reaction in the exhaust system; secondly, special waste treatment equipment should be selected. The special gas exhaust treatment equipment consists of the dilution method, absorption method, adsorption method, catalytic combustion method, etc. The materials of the exhaust system equipment and piping must be selected according to the characteristics of the special gas in the exhaust, and must not react with the discharged special gas.

Special gas treatment equipment, first of all, in the catalytic reaction section, the harmful components are catalyzed (burned), and then sent to the adsorption section to remove various types of catalytic reaction products, and discharged into the atmosphere after reaching the emission standard. The adsorbent is periodically regenerated and activated to restore the adsorption capacity according to the design requirements.

(8) Harmful and toxic exhaust system in pharmaceutical production

In the production or distribution of strong allergenic drugs such as penicillin, certain steroid drugs and rooms with high activity and toxic drugs, the exhaust vents in the operating area of Class II hazards should be installed with high-efficiency filters to cause these drugs The risk of pollution is reduced to a minimum. In addition, the air outlet of this type of air exhaust system should be separated from the fresh air inlet of the purified air conditioning system for other pharmaceutical production.