PVC spray tower

The PVC spray tower is an exhaust gas treatment device made of polyvinyl chloride (PVC). Its operating principle is similar to other spray towers, primarily purifying exhaust gas through gas-liquid contact. Due to the properties of PVC, it has targeted treatment capabilities for specific exhaust gas types. The details are as follows:

I. Operating Principle
Based on gas-liquid absorption and neutralization reactions, the process is as follows:

1. Exhaust Gas Intake: Pollutant-laden exhaust gas enters the tower from the bottom under the fan and flows upward.

2. Absorbent Liquid Spray: The tower's top spray system pressurizes the absorbent liquid (such as water or alkaline/acidic solution) and atomizes it into droplets through a nozzle, spraying them downward to form a dense liquid curtain.

3. Purification Reaction: The rising exhaust gas comes into contact with the falling droplets, removing pollutants through physical adsorption (dust capture) or chemical neutralization (reaction of the acidic and alkaline gases with the corresponding solution).

4. Gas-Liquid Separation: The purified gas passes through the tower's top demister to remove entrained droplets before being discharged from the top of the tower. 5. Waste Liquid Circulation/Treatment: Waste liquid from pollutant absorption is collected in a sump at the bottom of the tower and can be recycled (for reagent replenishment) or treated and discharged.

II. Internal Structure

Mainly composed of PVC components, the structure includes:
- Tower Body: A sealed PVC container (cylindrical or square), serving as the core space for gas-liquid reaction.
- Air Inlet/Outlet: The air inlet is located at the bottom of the tower and connects to the exhaust pipe; the air outlet is located at the top of the tower and connects to the exhaust pipe.
- Spray System: Consists of a circulating water pump, spray pipes, and atomizing nozzles, ensuring uniform spraying of the absorption liquid.
- Packing Layer (optional): Located in the middle of the tower, filled with inert packing (such as PVC ball rings) to increase the gas-liquid contact area and improve efficiency.
- Demister: Located before the air outlet at the top of the tower, it separates liquid droplets from the gas to prevent secondary contamination.
- Sump: The space at the bottom of the tower that collects waste liquid and is equipped with a level control and a drain outlet.

III. Applicable Waste Gas Types
PVC has good acid resistance and some alkali resistance (but poor resistance to strong alkalis), and is relatively low-cost. Therefore, it is primarily suitable for treating the following waste gases:

- Acidic waste gases: such as hydrochloric acid (HCl) and nitric acid (HNO₃) mists generated by electroplating and pickling, and sulfur dioxide (SO₂) and hydrogen fluoride (HF) from chemical production.
- Dusty general waste gases: such as those generated by mechanical and food processing, mixed with dust and small amounts of corrosive gases.
- Low-concentration organic waste gases: such as those from the printing and coating industries containing small amounts of organic solvents (such as ethanol and acetone) (requires the use of a dedicated absorbent).

Note: PVC is not resistant to high temperatures (recommended long-term operating temperature ≤ 60°C) and has poor resistance to strong alkalis. Therefore, it is not suitable for treating high-temperature waste gases, strong alkaline waste gases (such as high-concentration ammonia), or waste gases containing strong solvents.