Horizontal spray tower

▍ Working principle

The working principle of a PP horizontal spray tower is based on a mass transfer process involving full contact between the gas and liquid phases. It primarily uses the scrubbing liquid to absorb, neutralize, or remove harmful components from waste gas. Its workflow is as follows:

1. Waste Gas Introduction: The waste gas to be treated enters the bottom of the tower tangentially or axially through the inlet flange.

2. Primary Purification Zone (Gas Distribution Zone): After entering the tower, the waste gas first passes through an airflow distribution plate or buffer zone, ensuring uniform airflow across the tower's cross-section and preparing for full contact with the scrubbing liquid.

3. Spray Absorption Zone: This is the core purification area. The scrubbing liquid is efficiently atomized through spiral nozzles installed at the top of the tower, forming an extremely fine droplet curtain. As the waste gas passes horizontally through the tower, it comes into counter-current contact with countless tiny droplets sprayed from top to bottom.

● Inertial Collision: Particulate matter in the waste gas collides with the droplets due to inertia and is captured.

● Absorption and Dissolution: Acidic gases (such as SO₂, HCl, HF, H₂S) or alkaline gases (such as NH₃) are absorbed by alkaline (such as NaOH solution) or acidic washing liquids and undergo neutralization reactions.

● Coagulation and Settling: Fine dust particles are encapsulated by liquid droplets, increasing their weight and facilitating settling.

4. Demisting and Dehydration Zone: Before being discharged, the wet exhaust gas after spray washing passes through a demister (usually a hollow sphere demister or a cyclone plate type). This device effectively intercepts and separates tiny liquid droplets and moisture entrained in the exhaust gas, ensuring that the exhaust gas meets emission standards while preventing moisture carryover, protecting downstream pipelines and fans.

5. Clean Gas Emission: The clean gas after demisting and dehydration is discharged into the atmosphere through the outlet flange by the induced draft fan.

6. Circulation and Discharge: After absorbing pollutants, the washing liquid falls into the storage tank at the bottom of the tower. A portion can be pumped back for reuse. When the concentration of pollutants in the liquid reaches a certain value, it is discharged through overflow or outlet for centralized treatment, while fresh washing liquid is added.

▍ Structural features

1. Horizontal Design:

● Low Resistance Drop: Horizontal airflow ensures a smooth path and low system resistance, significantly reducing fan energy consumption.

2. Primary Purification Zone (Gas Distribution Zone): After entering the tower, the exhaust gas first passes through an airflow distribution plate or buffer zone, ensuring uniform airflow distribution across the tower's cross-section and preparing for sufficient contact with the scrubbing liquid.

3. Spray Absorption Zone: This is the core purification area. The scrubbing liquid is efficiently atomized through spiral nozzles installed at the top of the tower, forming an extremely fine droplet curtain. As the exhaust gas passes horizontally through the tower, it comes into counter-current contact with countless tiny droplets sprayed from top to bottom.

● Inertial Collision: Particulate matter in the exhaust gas collides with and is captured by the droplets due to inertia.

● Absorption and Dissolution: Acidic gases (such as SO₂, HCl, HF, H₂S) or alkaline gases (such as NH₃) are absorbed and neutralized by alkaline (such as NaOH solution) or acidic scrubbing liquid.

● Coagulation and Settling: Fine dust particles are encapsulated by liquid droplets, increasing their weight and facilitating settling.

4. Demisting and Dehydration Zone: Before being discharged, the wet exhaust gas after spray washing passes through a demister (usually a hollow sphere demister or a cyclone plate type). This device effectively intercepts and separates tiny liquid droplets and moisture entrained in the exhaust gas, ensuring that the exhaust gas meets emission standards while preventing moisture carryover, protecting downstream pipelines and fans.

5. Clean Gas Emission: The clean gas, after demisting and dehydration, is discharged into the atmosphere through the outlet flange powered by the induced draft fan.

6. Circulation and Discharge: After absorbing pollutants, the washing liquid falls into the storage tank at the bottom of the tower. A portion can be pumped back for reuse. When the pollutant concentration in the liquid reaches a certain value, it is discharged through the overflow or discharge port for centralized treatment, while fresh washing liquid is replenished.

▍ Structural features

1. Horizontal Design:

● Low Resistance Drop: Horizontal airflow ensures a smooth path and low system resistance, significantly reducing fan energy consumption.

2. Primary Purification Zone (Gas Distribution Zone): After entering the tower, the exhaust gas first passes through an airflow distribution plate or buffer zone, ensuring uniform airflow distribution across the tower's cross-section and preparing for sufficient contact with the scrubbing liquid.

3. Spray Absorption Zone: This is the core purification area. The scrubbing liquid is efficiently atomized through spiral nozzles installed at the top of the tower, forming an extremely fine droplet curtain. As the exhaust gas passes horizontally through the tower, it comes into counter-current contact with countless tiny droplets sprayed from top to bottom.

● Inertial Collision: Particulate matter in the exhaust gas collides with and is captured by the droplets due to inertia.

● Absorption and Dissolution: Acidic gases (such as SO₂, HCl, HF, H₂S) or alkaline gases (such as NH₃) are absorbed and neutralized by alkaline (such as NaOH solution) or acidic scrubbing liquid.

● Coagulation and Settling: Fine dust particles are encapsulated by liquid droplets, increasing their weight and facilitating settling.

4. Demisting and Dehydration Zone: Before discharge, the wet exhaust gas after spray washing passes through a demister (usually a hollow sphere demister or a cyclone plate type). This device effectively intercepts and separates tiny liquid droplets and moisture entrained in the exhaust gas, ensuring that the exhaust gas meets emission standards while preventing moisture carryover, protecting downstream pipelines and fans.

5. Clean Gas Emission: The clean gas after demisting and dehydration is discharged into the atmosphere through the outlet flange, powered by the induced draft fan.

6. Circulation and Discharge: After absorbing pollutants, the washing liquid falls into the storage tank at the bottom of the tower. A portion can be pumped back for reuse. When the pollutant concentration in the liquid reaches a certain value, it is discharged through the overflow or discharge port for centralized treatment, while fresh washing liquid is replenished.

▍ Structural features

1. Horizontal Design:

● Low Resistance Drop: Horizontal airflow ensures a smooth path and low system resistance, significantly reducing fan energy consumption.

● Easy Maintenance: The tower body typically features large manholes or inspection doors on the side, allowing internal components such as nozzles, packing, and demisters to be easily removed for inspection, cleaning, or replacement, ensuring safety and convenience.

● Suitable for Space Layout: The equipment has a low height, making it suitable for installation in environments with limited height or where horizontal piping is required.

2. High-Quality PP Material:

● Excellent Corrosion Resistance: PP plastic exhibits excellent resistance to inorganic acids, alkalis, and salt solutions (such as hydrochloric acid, sulfuric acid, and sodium hydroxide), fundamentally solving the problems of easy corrosion and short lifespan associated with metal equipment.

● Lightweight and High-Strength: The equipment weighs significantly less than FRP or rubber-lined carbon steel equipment, facilitating transportation and installation with lower foundation requirements.

● Less Prone to Scaling: The smooth inner wall prevents dirt accumulation and clogging.

● Long service life: Under suitable operating conditions, the service life can reach 8-15 years or more.

3. High-efficiency spray system:

● Uses spiral solid cone nozzles made of PP or stainless steel, with a large spray angle (120°), wide coverage area, good atomization effect, and low water consumption.

● Layered spray piping arrangement ensures that the washing liquid completely covers the entire cross-section of the tower, eliminating any dead corners.

4. Modular design:

● Can be designed in multi-stage series (e.g., two-stage spray + one-stage demisting) or parallel configurations according to the air volume and purification requirements, offering high flexibility and easy expansion.

5. Other components:

● Liquid storage tank: Integrated design at the bottom of the tower for storing and settling the circulating liquid.

● Viewing window and maintenance port: Equipped with a transparent PP viewing window for easy observation of the internal spraying and operation; a large maintenance port facilitates personnel access.

● Supporting systems: Typically used in conjunction with circulating water pumps, dosing systems, level control systems, pH monitors, etc., to achieve automated operation.

▍ Core advantages

● **King of Corrosion Resistance:** PP material exhibits exceptional resistance to complex chemical waste gas environments, resulting in extremely low maintenance costs.

● **Low Operating Costs:** Low system resistance and low fan energy consumption; lower pump head requirements also contribute to excellent overall energy efficiency.

● **Large Air Volume Handling Capacity:** The horizontal structure facilitates handling large air volumes, with single-unit capacity ranging from thousands to hundreds of thousands of m³/h.

● **Easy Maintenance:** The side-opening design allows all routine maintenance to be performed from the ground, ensuring safety, saving time and effort.

● **High Purification Efficiency:** The combination of multi-stage spraying and high-efficiency demisting provides high removal efficiency for particulate matter and gaseous pollutants soluble in detergents.

● **Low Overall Cost:** The equipment cost is lower than comparable fiberglass or stainless steel equipment, and its long lifespan and low maintenance result in a significant life-cycle cost advantage.

▍ Scope of application

PP horizontal spray towers are particularly suitable for treating large volumes of low-concentration waste gas. Specific applications include, but are not limited to:

● Chemical Industry: Pretreatment of acid mist, alkali mist, and organic waste gas generated during the production of pesticides, dyes, pharmaceuticals, and resins.

● Electronics Industry: Sulfuric acid, hydrochloric acid, and nitric acid mist generated during etching and pickling processes in semiconductor and PCB manufacturing.

● Metal Processing: Chromic acid mist, cyanide mist, sulfuric acid mist, and nitric acid mist generated during electroplating, pickling, and anodizing processes.

● Waste Gas Pretreatment: As a pretreatment unit for incinerators (RTO/RCO), activated carbon adsorption towers, etc., used for cooling, dust removal, and removal of components that can poison catalysts (such as sulfur dioxide and chloride ions).

● Laboratory Ventilation: Treatment of fume hood exhaust gases in university, research institute, and corporate laboratories; the composition is complex but the concentration is usually low.

● Other Fields: Odor removal in waste transfer stations, deodorization in food factories, and the textile printing and dyeing industry, etc.