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All You Need to Know About Chemical Absorption Tower

Longben-environmental protection-Learn about Environmental Protection Spray Towers-Longben

Spray towers play a vital role in industrial waste gas treatment. They purify exhaust gas by atomizing liquid to make full contact with waste gas. There are various types of spray towers, differing in treatment efficiency and applicable exhaust gas conditions. How can different industries select the optimal spray tower type according to their own waste gas characteristics?

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Spray Towe

1 Definition and Working Principle

A spray tower, also known as a scrubber, is a type of waste gas treatment equipment. Its working principle is to atomize liquid (usually water or chemical absorbent) into fine droplets. Pollutants in the waste gas come into full contact with the atomized liquid, and are then removed via absorption, adsorption or chemical reaction.
For instance, when the waste gas contains soluble acidic gases such as sulfur dioxide and hydrogen chloride, alkaline absorbents like sodium hydroxide solution in the spray tower will react with them. Taking sulfur dioxide as an example, the reaction equation is:

The acidic gas is absorbed and converted into harmless salts to realize exhaust gas purification. For adsorbable particulate matter or certain organic compounds in waste gas, pollutants can also be adsorbed into the spraying liquid through contact.

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2 Structural Composition

The spray tower is mainly composed of the tower body, packing, spraying system, packing layer (equipped on partial spray towers), demister, water tank and circulation system.

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3 Structural Composition and Classification

a. Classification by Waste Gas Properties

Acid Spray TowerIt is mainly applied to treat industrial waste gas with acidic components such as sulfuric acid mist and hydrochloric acid mist. Alkaline solution is used as the circulating spray liquid inside the tower, which neutralizes acidic pollutants and removes them from exhaust gas.
Alkaline Spray TowerIt targets alkaline industrial waste gas represented by ammonia gas. Acidic spray liquid is adopted for neutralization treatment to achieve gas purification.
Water Spray Tower

It is applicable to exhaust gas with heavy dust or water-soluble harmful gases. Water spray settles water-soluble pollutants and large particles, so as to separate contaminants from clean air.


b. Classification by Equipment Shape

Vertical Spray TowerThe tower is vertically structured with a small footprint, ideal for sites with limited space. Waste gas enters from the bottom, flows through the spray layer and packing layer, and is discharged from the top. With high purification efficiency, it is the most widely used type.
Horizontal Spray Tower

The tower is installed horizontally. It features a longer gas flow path and prolonged gas-liquid contact time for better purification performance. It covers a larger area with relatively complex installation and maintenance, and is mostly used for large-volume waste gas treatment with high purification standards.


c. Classification by Equipment Material

Based on waste gas characteristics including dust content, concentration, ignition point and pH property, common types include PVC scrubber, PP scrubber, FRP (Fiber Reinforced Plastic) scrubber and SUS304 stainless steel scrubber.


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4 Main Design Parameters of Spray Tower

1. Empty Tower Gas VelocityA lower gas velocity is conducive to higher absorption efficiency, with the conventional design range of 1.0~1.5 m/s.

2. Packing Layer ThicknessThe thickness of the packing layer held by the spray section is generally more than 0.6 m, with a maximum of 1.8 m.There is no unified calculation standard for tower height, which is usually determined according to tower diameter. The height-to-diameter ratio (H/D) is controlled within 4~7, and the spray section accounts for more than half of the total tower height.

3. Gas-Liquid RatioThe gas-liquid ratio is the core control parameter closely related to purification efficiency. Under fixed working conditions, a higher water-gas ratio brings better purification effect. The recommended gas-liquid ratio is 0.8~2.0 L/m³.

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Industrial Waste Gas Treatment

1. Widely applied in chemical, electroplating, metallurgy, printing and dyeing industries for the treatment of acidic and alkaline waste gas generated in production processes.In the chemical industry, a large amount of acids and alkalis are used in chemical reactions. Waste gas containing hydrogen chloride, sulfuric acid mist, ammonia and other pollutants can be effectively purified by spray towers.

2. Used for treatment of organic waste gas and paint mist from spraying and coating processes.Although a single spray tower has limited removal efficiency for organic waste gas, it can serve as an ideal pretreatment facility. It removes particulate matter and partial water-soluble organic components in paint mist, laying a foundation for subsequent advanced treatment processes such as macroporous resin adsorption, activated carbon adsorption and catalytic combustion.

Odor Control

Spray towers are widely adopted in sewage treatment plants, waste disposal plants and other sites to treat malodorous gas. Such odor gas usually contains hydrogen sulfide, methyl mercaptan and other harmful substances. By adopting suitable absorbents such as sodium hypochlorite solution, the spray tower can effectively reduce odor emission.

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Guangdong Longben Environmental Design Institute Co., Ltd. is a high-tech environmental protection enterprise integrating R&D, design, manufacturing, sales and operation management of new environmental protection materials, innovative processes and professional equipment.


Since its founding in 1982, Longben Group has been committed to the environmental protection industry for 41 years.It has accumulated rich engineering experience and solid technical strength in fields including waste gas treatment, deodorization engineering, wastewater treatment, industrial wastewater reuse, environmental protection equipment manufacturing and sales, environmental operation services, environmental supervision, environmental impact assessment and environmental consulting services.

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