Sulfuric Acid Mist Scrubber

Product Model	Acid and Alkali Mist Spray Absorption Tower Series
Category	Waste Gas Treatment Equipment
Reference Price	Price on request

Hot Customizable for Working Conditions 10 Technical Parameters

Product Overview

The acid mist scrubber is a specialized spraying absorption equipment designed for acid mist and certain alkaline gases generated in processes such as pickling, electroplating, and chemical engineering. The tower body is welded using PP or PPs plate materials, offering acid and alkali corrosion resistance. Acid mist-containing exhaust air is drawn into the tower by a fan, where it comes into countercurrent contact with alkaline absorbent (typically sodium hydroxide solution) sprayed from the nozzle layers. Acidic pollutants are captured by liquid droplets and liquid films on the packing surface and undergo neutralization reactions. The purified gas is discharged after demisting, while the absorbent is recycled in the sump at the bottom of the tower, with periodic replenishment of alkali solution and replacement.

The acid mist scrubber is effective against various water-soluble gases, with common treatment targets including hydrogen chloride, nitric acid mist, hydrofluoric acid mist, sulfuric acid mist, chromic acid mist, hydrogen cyanide, ammonia gas, sodium hydroxide vapor, and hydrogen sulfide. Acidic gases are neutralized using alkaline absorbents such as sodium hydroxide, while alkaline gases like ammonia are treated with acidic absorbents. The equipment features high purification efficiency, corrosion resistance, high strength, low noise, low power consumption, compact size, easy disassembly and maintenance, and is the most commonly used acid-alkali exhaust gas treatment equipment in electroplating, surface treatment, metallurgical pickling, and chemical industries.

Xicheng Environmental can design acid mist scrubbers based on exhaust gas types, concentrations, and treatment airflow rates. The configuration includes packing layers, spraying layers, demisting devices, circulation pumps, and dosing systems. Tower diameter and height are calculated based on airflow, with PP or PPs plate materials available. Multi-tower串联 configurations are supported for high-concentration or mixed pollutant exhaust gas treatment, and pH automatic dosing control is provided to ensure stable and compliant purification effects.

Working Principle

The acid mist scrubber operates based on acid-alkali neutralization and gas-liquid absorption principles. Acid mist-containing exhaust air enters the tower and rises through the packing layer. The circulation pump delivers alkaline absorbent to the top spraying pipes, where it is uniformly sprayed downward through nozzles, forming liquid films and fine droplets on the packing surface. The exhaust air comes into countercurrent contact with the absorbent in the packing voids, where acid mist particles are washed and captured by liquid droplets. Acidic gases dissolve in the liquid film and react with the alkali solution to form salts, transferring gaseous pollutants to the liquid phase and purifying the gas.

The direction of the neutralization reaction depends on the pollutant: acidic gases use alkaline absorbents, such as hydrogen chloride reacting with sodium hydroxide to form sodium chloride and water, while sulfuric acid mist and nitric acid mist follow similar reactions. Alkaline gases like ammonia are treated with acidic absorbents such as dilute sulfuric acid. The packing layer provides a large gas-liquid contact area, enhancing absorption efficiency. The purified gas rises with liquid droplets, which are dehydrated and demisted by demisting plates (baffles or mesh) at the top or outlet before being discharged by the fan. Pollutant-absorbed liquid falls into the sump at the bottom of the tower for recycling. The salt concentration gradually increases, and absorption capacity is maintained through periodic effluent discharge, water replacement, and fresh absorbent replenishment. The wastewater is then sent to a wastewater treatment system.

Structural Components

The acid mist scrubber consists of a tower body, inlet section, packing layer, spraying layer, demisting layer, circulation sump, circulation pump, and dosing system. The tower body is a cylindrical welded structure made of PP or PPs plate卷, with external reinforcement rings. The bottom of the tower is the circulation sump, with an inlet at the lower tangential or frontal section and an outlet at the top or side.

Internally, the tower is arranged from bottom to top with packing support grates, packing layers (multi-faced spheres or Raschig rings), spraying pipes, and nozzles, which can be multi-stage. A demisting plate is installed at the upper section. The sump is equipped with water replenishment, overflow, effluent discharge, dosing, and level indicators. The circulation pump draws liquid from the sump and pressurizes it to the spraying pipes. The dosing system includes a dosing drum, metering pump, and online pH meter, automatically replenishing alkali or acid based on the circulating liquid pH. The tower body is equipped with manholes, inspection doors, ladders, and platforms. Observation ports are provided for inspecting spraying and packing conditions. Inlet and outlet ports are fitted with flanges for connection to ductwork and fans.

Specification Model Table

The table below shows the main treatment targets and absorbent configurations for the acid mist scrubber, with specific designs based on exhaust gas composition.

Exhaust Type	Representative Pollutant	Absorbent
Acidic Gas	Hydrogen Chloride Sulfuric Acid Mist Nitric Acid Mist	Sodium Hydroxide Alkaline Solution
Fluorine-Containing Gas	Hydrogen Fluoride Hydrofluoric Acid Mist	Alkaline Absorption
Alkaline Gas	Ammonia Gas	Acidic Absorbent

Product Features

The acid mist scrubber is highly targeted, offers high purification efficiency, and has cost-effective operation, making it a mature equipment for acid-alkali mist exhaust gas treatment. Its main features are as follows.

Alkaline solution neutralization and absorption, achieving high purification efficiency for various acid mists
PP or PPs tower body, corrosion-resistant and long service life
Inverse flow packing contact, ensuring sufficient gas-liquid contact and stable absorption performance
Low noise and power consumption, low operating costs, compact size
Demisting plates for dehydration, minimizing liquid carryover in outlet gas
Modular design with full manholes and inspection doors for easy maintenance
Configurable with pH automatic dosing for unattended stable operation

Material of tower body	PP / PPs sheets
Purification Principle	Alkali Spray Absorption Neutralization
Gas-Liquid Contact	Filler bed counter-current
Object Processing	Acid and Alkali Mists, Water-Soluble Gases
Defogging Method	Dehumidifying Plate Drying
Recirculation Mode	Bottom Tank Circulation
Chemical Dosing Control	pH Automatic Dosing Optional
Corrosion resistance performance	Acid and Alkali Salt Resistance
Structural Features	Easy to disassemble and repair
Specifications and Features	Non-standard design based on airflow

Application Industries

Acid mist treatment for hydrochloric acid and sulfuric acid pickling tanks in electroplating production lines
Acid mist purification in metallurgical and stainless steel pickling workshops
Hydrogen chloride and hydrogen fluoride tail gas absorption in chemical enterprises
Acid-base exhaust gas washing and purification in semiconductor and photovoltaic factories
Acid mist treatment for surface treatment and anodizing processes
Acid-base fume washing in laboratory and testing institution ventilation hoods
Acid-containing exhaust gas treatment for batteries, electronic etching, etc.

Typical Process Locations

The acid mist purification tower is installed in the exhaust system of pollution-emitting points such as pickling tanks and electroplating lines. The acid mist collected by the hood enters the lower inlet of the purification tower through ducts. Inside the tower, the acid mist rises from bottom to top through the packing layer and spray layer, where it is washed by alkaline solution. The purified gas is demisted and then discharged through the top or side outlet of the tower into a corrosion-resistant fan, before being emitted to the atmosphere via an exhaust stack. The circulating pump and chemical dosing device are arranged around the tower body, with the bottom water tank connected to the water replenishment, wastewater discharge, and wastewater treatment systems. The fan is generally installed after the purification tower to maintain negative pressure in the tower and pipelines, preventing acid mist leakage.

During installation, the tower body is vertically fixed on a concrete foundation, with horizontal and vertical alignment meeting requirements. Flexible connections are installed at the duct inlet and outlet. The weight of the tower body and liquid is borne by the foundation. Before operation, the alkaline solution of the specified concentration is prepared, and inspections are conducted to ensure uniform nozzle spray, properly filled packing, and correctly positioned demisting plates. Water pumps should be turned on before fans, and fans should be turned off before water pumps during shutdown. During operation, alkaline solution is replenished according to pH indicators, water is replaced and discharged regularly, and pollutant concentrations at the inlet and outlet are monitored to ensure the absorption liquid concentration and spray volume remain within the design range.

Mainly treats acid mists and water-soluble gases that can be absorbed by water or alkaline solutions, such as hydrogen chloride, sulfuric acid mist, nitric acid mist, hydrogen fluoride, chromic acid mist, hydrogen cyanide, hydrogen sulfide, and other acidic gases, using alkaline solutions like sodium hydroxide for absorption; alkaline gases such as ammonia are treated with acidic absorbing solutions. It is not suitable for treating water-insoluble organic exhaust gases (e.g., benzene derivatives, esters, VOCs), which require processes such as activated carbon adsorption and catalytic combustion. When multiple pollutants are present, their solubility and reaction characteristics must be analyzed separately. Multi-stage, multi-process combinations may be necessary if required, with specific configurations determined by exhaust gas composition testing and process design.

Common reasons include: insufficient circulating caustic soda concentration or long-term non-replacement, leading to saturated absorption capacity; insufficient spray volume, nozzle blockage, or uneven spraying, resulting in dry zones in the packing layer; packing blockage, crystallization, or scaling reducing gas-liquid contact area; airflow exceeding design value, high gas velocity, or insufficient contact time; abnormal demisting and wastewater discharge. Regularly test the circulating liquid's pH and density, promptly replenish alkali and replace water, clean and clear nozzles and packing, and verify if the actual airflow exceeds the design. When the single-stage tower is insufficient for high-concentration exhaust gas, increase the number of spray stages or use two-stage towers in series. Do not rely on indefinitely increasing alkali concentration as a solution.

No fixed cycle; it depends on the acid mist generation volume and the saturation level of the circulating liquid. In engineering practice, pH meters and salt concentration (density) are used for control: when the pH drops below the set lower limit, alkaline reagents are automatically added. When the salt concentration in the circulating liquid becomes excessively high, absorption efficiency decreases, or the discharge standard is reached, some or all of the circulating liquid is discharged and replaced with fresh water and fresh alkaline reagents. It is recommended to configure automatic pH dosing and regular discharge systems. Wastewater must be sent to a wastewater treatment facility and cannot be discharged directly. For manual management, pH and liquid level should be tested by shift, and records for reagent dosing and water replacement should be established to avoid long-term liquid replacement based on subjective judgment.

Moisture or white mist discharge may be caused by clogged, damaged, or improperly installed demisting plates, where liquid droplets cannot be effectively separated as air flows through the demisting layer; alternatively, it could result from excessively high gas velocity within the tower or excessive spray volume, carrying liquid droplets out of the tower. In winter, steam condensation can also form visible white mist. Inspect, clean, or replace the demisting plates, control airflow and gas velocity within the design range, adjust spray volume, and increase the demisting section or add a secondary demisting stage if necessary. Water carryover can corrode fans and ducts and cause water dripping from the exhaust stack, requiring prompt treatment upon detection.

Salts generated by acid-base neutralization crystallize on the packing surface, combined with dust accumulation, which increases the resistance of the packing layer, reduces airflow, and decreases purification efficiency. Preventive measures include: enhancing dust control in the front-end hood and ductwork, maintaining clean and filtered circulating water, controlling circulating liquid concentration to avoid supersaturated crystallization, and regularly flushing the packing layer with large amounts of water. If blockage occurs, shut down the equipment and enter through the maintenance door to flush the packing with high-pressure water. Soluble crystallization can be cleaned by circulating appropriate dilute acid or dilute alkali (material and waste liquid treatment must be verified), while severely hardened or broken packing should be removed and replaced, along with cleaning accumulated deposits in the grating and water tank.

Need to provide the types and concentrations of main exhaust pollutants, treatment air volume, exhaust temperature, and humidity/dust conditions, required purification efficiency and emission standards, installation location (indoor or outdoor), and available space, as well as absorption liquid and wastewater treatment conditions. The pollutant types determine the absorption liquid formulation and tower materials, air volume determines the tower diameter, and concentrations and efficiency determine the number of packing layers, spray stages, and tower height. Providing these parameters allows the manufacturer to select the appropriate model and ensure compliance. Basing quotes solely on air volume and tower diameter without verifying pollutant composition can easily result in mismatched treatment capacity.

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