Equipment for the treatment of petrochemical pyrolysis waste gas such as contaminated oil and sludge in Xinjiang and Inner Mongolia

4.32 Secondary alkali washing tower spray absorption technology

The filling spray method is used for treatment, and the spray tower utilizes the suction system to provide power for the gas flow throughout the system. A suction fan is a mechanical device that relies on input mechanical energy to increase gas pressure and discharge gas. It is a passive fluid mechanical absorption principle to achieve the purpose of treating exhaust gas.

Absorption treatment is the process of using liquid absorbents to remove one or more gases from a gas mixture. During this process, there will be a physical effect of certain gases dissolving in the solution, which is physical absorption. Chemical reactions also occur between chemical substances in gas-liquid mixtures, which is known as chemical absorption. Absorption is commonly used for the treatment and recovery of gas pollutants.

The characteristic of absorption method is that it can absorb harmful gases and remove dust from exhaust gas. Absorption method is divided into physical absorption and chemical absorption. Physical absorption is a pure physical dissolution process in which harmful gases and vapors are absorbed by liquids. It is suitable for harmful gases and vapors with high solubility in water,The absorption efficiency is generally low. Chemical absorption is accompanied by significant chemical reactions during the absorption process,It's not a pure dissolution process. High chemical absorption efficiency,It is currently the most widely used method for treating harmful gases.

The acid-base waste gas extracted from the workshop process section enters the washing tower under the action of the centrifugal fan. Inside the washing tower, the neutralizing solution is sprayed down through the spray system and undergoes neutralization reaction with acidic or alkaline gases in the exhaust gas, thereby achieving purification effect. In order to improve the purification efficiency of the purification tower, a special packing material is used for the waste gas scrubbing towerPPBall ring is used to increase the gas-liquid contact area. In order to keep the neutralizing solution in an optimal stateThe absorption concentration is reduced and manual operation is minimized. This system adopts an automatic dosing system to supplement the washing tower with sodium hydroxide. Each system includes1An automatic dispensing box, each automatic dispensing box includes1aPHCalculate,1A metering pump,PHAccording to the absorption liquid inside the purification tower boxPHThe value is used to control the switch of the metering pump, thereby achieving automatic dosing. The exhaust gas purified by the exhaust gas scrubbing tower is discharged through the chimney to meet the standard.

4.3.3Activated carbon adsorption treatment technology

Adsorption method for purifying organic waste gas is a widely used traditional treatment process technology, especially with the excellent adsorption performance of activated carbonIt is widely used. The reason is that other adsorbents have polarity. Under the coexistence of water vapor, water molecules and polar molecules of the adsorbent combine, thereby reducing the adsorption performance of the adsorbent. However, activated carbon molecules are not easily combined with polar molecules, thereby improving the adsorption capacity of organic waste gas. Activated carbon has good adsorption and purification effects on non methane total hydrocarbons, toluene, and VOCs.

(1) Adsorption phenomenon is a phenomenon that occurs at two different phase interfaces. The adsorption process is a diffusion process at the interface, which occurs on the solid surface due to the residual attractive force on the solid surface. Adsorption can be divided into physical adsorption and chemical adsorption; Physical adsorption, also known as van der Waals adsorption, is caused by the electrostatic force or van der Waals attraction between the adsorbent and the adsorbate molecules. When the molecular attraction between solid and gas is greater than that between gas molecules, even if the gas pressure is lower than the saturation vapor pressure corresponding to the operating temperature, gas molecules will condense on the solid surface. Physical adsorption is an exothermic process. Chemical adsorption, also known as active adsorption, is caused by the chemical reaction force between the surface of the adsorbent and the adsorbate molecules. It involves the destruction and recombination of chemical bonds in the molecules. Therefore, the adsorption heat in the chemical adsorption process is greater than that in the physical adsorption process. In the adsorption process, there is no strict boundary between physical adsorption and chemical adsorption. The same substance may undergo physical adsorption at lower temperatures, while chemical adsorption often occurs at higher temperatures. Activated carbon fiber adsorption is mainly based on physical adsorption, but due to the presence of surfactants, there is also a certain degree of chemical adsorption.Utilizing the adsorption properties of activated carbon with multiple micropores to adsorb organic waste gas is an effective industrial treatment method. Honeycomb shaped activated carbon has the advantages of stable performance, corrosion resistance, and resistance to high-speed airflow impact. With its excellent adsorption efficiency for odors, it mainly plays a role in controlling excessive exhaust gas at the end. After purification treatment, the exhaust gas can meet the corresponding gas emission standards.