Thread Content
Our country is a major coal-consuming nation, and it generates large amounts of sulfur dioxide each year. In the atmosphere, this sulfur dioxide combines with water vapor and oxygen to form sulfuric acid, resulting in acid rain and acid fog. People fear these phenomena, referring to them as the \"death from the sky.\" The pollution and damage caused by them pose a serious threat to people’s lives and livelihoods. Proper treatment of acidic gases in exhaust gases is an essential measure for controlling air pollution. Acid mist absorption towers can help control air pollution and reduce the hazards in a company’s production environment, thereby improving the conditions in the workshops as well as those under which workers operate. Generally, the acid gas generated during pickling has an acid mist concentration of 3210 mg/m3 under standard conditions, with an exhaust gas temperature of 60°C. According to the purification design plan, a complete set of equipment is required, whose basic components include: gas collection hood, air ducts, purification equipment, acid-resistant fans, and chimney. 1) Collection hood: A collection hood is used to capture polluted air currents. Its performance has a direct impact on the technical and economic indicators of the purification system. Due to the differences in the structure of pollution source equipment and production processes, the forms of gas collection hoods are diverse. 2) Ducts: In a purification system, the pipes used to convey air currents are called ducts; they enable the various devices and components of the system to be connected as a whole. 3) Purification equipment: To prevent air pollution, when the concentration of pollutants in the exhaust gas exceeds the emission standards, purification equipment is required to treat it; only after meeting the emission standards can the gas be released into the atmosphere. That is, the packing absorption tower in this system. 4) Acid-resistant fans: Acid-resistant fans are the power devices that drive gas flow in the system. To prevent wear and damage to the fan, it is usually placed after the purification equipment. 5) Chimney: The chimney is the exhaust device of the purification system. Because it still contains a certain amount of pollutants after purification, these pollutants spread, dilute, remain suspended in the air, or settle to the ground. To ensure that the ground concentration of pollutants does not exceed the environmental air quality standards, chimneys must be of a certain height. According to the design documents, the waste gases generated mainly include steam, acid mist, and harmful gases. The liquid absorption method is used for purification here. A 5% NaOH solution can be used to absorb sulfuric acid fumes in a packed tower. Under the operating conditions, the gas-phase mass transfer coefficient kGa = 144 kmol/(m3·h·atm), and the liquid-phase mass transfer coefficient kLa = 0.7 h^-1. The recommended liquid-to-gas ratio under standard conditions is L/G = 2.5–4 L/m3. This exhaust gas purification system includes an acid-washing exhaust gas collection hood, air ducts, a packed tower, an acid-resistant fan, and a chimney. As mentioned above, the fan is a key power device in this system, serving to convey corrosive media. The exhaust gases transported include steam, acid mist, and harmful gases, with temperatures of 60°C or even higher; this means that ordinary fiberglass or plastic fans are not suitable for use. To ensure the proper operation of the system, it is recommended to use ceramic fans. The ceramic fan housing and end caps are made of acid-resistant ceramics, with an iron armor layer on the outside. All parts that come into contact with acidic gases are constructed from various corrosion-resistant materials. The impeller can be made of fiberglass-reinforced plastic, engineering plastics, or stainless steel as needed. This design offers light weight, high efficiency, fast rotation speed, as well as resistance to corrosion, wear, and high temperatures, making it an ideal fan device for transporting corrosive fluids in waste gas treatment applications.