As the scale of domestic chemical industry construction continues to expand, national environmental protection standards have set higher requirements for the emissions of waste gases into the atmosphere. The new environmental protection technology of using spray tower packing to chemically absorb toxic and harmful components from industrial emissions has been promoted and applied. This article summarizes the absorption principle of spray towers and, combined with engineering practice, determines the specific methods for the design of the spray tower packing and the issues that should be paid attention to during the design process.

     Section 1: Spraying Tower Absorption Principle
The main equipment room for absorbing gaseous pollutants includes absorption towers, Venturi scrubbers, and bubble reactors of various types. Within the absorption unit, the mixed gas containing the absorbable pollutant "a" contacts the absorbent "S" in a countercurrent (or cocurrent) manner, completing the absorption process. The purified gas (comprising the undissolved component "b" and the remaining "a") and the absorbent liquid (containing "a" and "S") are then discharged from the unit for further treatment. The purification efficiency of gaseous pollutants is quite related to the structure, performance of the absorption unit, and the gas-liquid equilibrium during the absorption process.
The direction and limit of the absorption process are related to the gas-liquid equilibrium of the solute between the gas and liquid phases. For any gas, under certain conditions, when it reaches equilibrium in a solvent, the partial pressure of the gas in the vapor phase is constant and referred to as the equilibrium partial pressure, denoted as p*. During the absorption process, when the actual partial pressure p of the solute in the vapor phase is higher than the partial pressure of the solute in equilibrium with the liquid phase (i.e., p > p*), the solute transfers from the vapor phase to the liquid phase, initiating the absorption process. The greater the difference between p and p*, the stronger the driving force for absorption, and the faster the absorption rate. Conversely, if p < p*, the solute transfers from the liquid phase to the vapor phase, representing the reverse process of absorption, known as desorption (or deabsorption).
The absorption process is a phase-boundary mass transfer mechanism, primarily involving theories such as the double-membrane theory, thin-film theory, solute penetration theory, surface renewal theory, and interface dynamic state theory. Each of these theories has its unique strengths in studying and describing the interface conditions during phase-boundary mass transfer and the influence of fluid mechanics factors. Different types of absorption towers adopt different mass transfer mechanisms as their theoretical models. However, it is still not possible to perform calculations for mass transfer equipment or solve other practical problems based on this.
During absorption operations, absorption processes accompanied by significant chemical reactions are referred to as chemical absorption. For example, the absorption of CO2, SO2, or H2S using aqueous solutions of NaOH, Na2CO3, or NH3OH all fall under chemical absorption.

Therefore, when purifying gaseous pollutants by absorption, it is essential to select an appropriate absorbent based on the properties of the gas to be absorbed, and to adopt chemical absorption methods (such as acid-base reactions) as much as possible.

Section Two: Design of the Sprinkler Tower Structure
The Absorber Tower is the core device for waste gas absorption. Compared to other types of absorber towers, such as packed towers and jetted sparge towers, the spray tower boasts advantages like simple structure, low resistance, and lower investment costs. During the absorption process, the waste gas enters from the bottom of the absorber tower, where it comes into reverse contact with the atomized spray of the circulating absorbent in the spray zone, leading to a chemical reaction. The toxic and harmful components of the waste gas are absorbed, and the dust in the waste gas is also removed.