PP Scrubber

Product Model	Packing Spray Scrubber Exhaust Gas Absorption Tower
Category	Waste Gas Treatment Equipment
Reference Price	Price on request

Hot Customizable for Working Conditions 10 Technical Parameters

Product Overview

The PP waste gas scrubber is a general-purpose packed tower for liquid absorption treatment of water-soluble waste gases. The tower body is entirely welded with PP or PPs plate, offering excellent corrosion resistance. Waste gas is introduced into the scrubber via ductwork, where it comes into full contact with the absorption liquid through the packing layer, neutralizing pollutants. The purified gas then passes through demisting plates for moisture and mist removal before being exhausted into the atmosphere via a fan. This mature and reliable process is suitable for a wide range of applications and serves as a fundamental equipment for acid-base and water-soluble waste gas treatment in industries such as chemical, electroplating, electronics, and pharmaceuticals.

Compared to specialized towers focused on acid mists, the PP waste gas scrubber is a more versatile platform product. By replacing the absorption liquid formulation and adjusting the packing and spraying configuration, it can handle various water-soluble gases such as hydrogen chloride, hydrogen fluoride, ammonia, sulfuric acid mist, chromic acid mist, hydrogen cyanide, sodium hydroxide vapor, hydrogen sulfide, and some formaldehyde. Acidic gases are absorbed by alkaline solutions, while alkaline gases are treated with acidic solutions. Some organic soluble gases are absorbed by water or specialized absorption liquids. The tower features high standardization and a full range of specifications, available for single-stage or multi-stage series treatment of high-concentration or complex-component gases.

The PP waste gas scrubber supplied by Xicheng Environmental Protection includes the tower body, packing, spraying system, demisting plates, circulating water pump, and dosing system. The tower diameter is series-matched to the treatment airflow, while the tower height and packing layers are designed based on pollutant concentration and purification requirements. It can be equipped with pH automatic dosing and liquid level protection, and supports PPs flame-retardant material for indoor installation, making it the most widely applicable wet scrubber for waste gas purification.

Working Principle

The core process of the PP waste gas scrubber is packed tower liquid absorption. Waste gas is introduced at the bottom of the tower and rises through the packing layer under fan suction. Absorption liquid is pumped to the top of the tower via a spray pipe, where it is uniformly sprayed onto the packing, forming a continuous liquid film that flows downward along the packing surface. The gas-liquid two phases flow countercurrently and make full contact in the packing layer. Pollutants in the gas phase enter the liquid phase through dissolution, absorption, and chemical reactions, purifying the waste gas. The packing provides a large and continuously renewed gas-liquid contact surface, which is key to mass transfer and absorption.

The purified gas continues to rise and passes through demisting plates where the airflow changes direction multiple times. Liquid droplets carried by the gas are captured by the demisting plates under inertial collision and flow down the plate surface to return to the water tank. The gas, now dehumidified and demisted, is exhausted into the atmosphere via the fan through an exhaust stack. The absorption liquid circulates in the water tank at the bottom of the tower, where its effective components gradually deplete and salts accumulate. The dosing system replenishes the absorption agent, while wastewater exchange maintains absorption capacity. The discharged effluent enters the wastewater treatment system. The entire process operates continuously, ensuring stable purification efficiency as long as the absorption liquid concentration, spraying amount, and gas-liquid contact conditions are maintained. The PP material is not corroded by acid-base gases, and the tower body and packing remain rust-free and undamaged even after long-term immersion.

Structural Composition

The PP waste gas scrubber consists of the tower body, inlet section, packing support, packing layer, spraying system, demisting plates, circulation water tank, circulation pump, and dosing device. The tower body is a cylindrical tube welded from PP plate rolls, with reinforcing rings on the outer wall. The bottom of the tower serves as the circulation water tank, with an inlet at the bottom and an outlet at the top or side.

The packing layer is supported by grating plates and filled with PP multi-faceted spheres or Raschig rings. A single or multiple spray pipes with solid conical or spiral nozzles are installed above each packing layer to ensure full cross-sectional coverage. Multi-stage towers have multiple packing layers and spray systems. A demisting baffle is installed above the packing layer. The water tank is equipped with a water replenishment port, overflow port, effluent port, dosing port, level gauge, and manhole. The circulation pump inlets and outlets are fitted with valves and filters. The dosing device consists of a drug storage tank, metering pump, and pH meter. External features include a ladder, maintenance platform, observation port, inspection door, and flanges for inlet and outlet ducts.

Specification Model Table

The table below shows typical treatment targets and absorption liquid selection for the PP waste gas scrubber, configured based on gas composition.

Gas Category	Representative Pollutant	Absorption Liquid
Acidic Gas	Hydrogen Chloride, Hydrogen Fluoride, Sulfuric Acid Mist	Alkaline Solution
Alkaline Gas	Ammonia	Acidic Solution / Water
Other Water-Soluble Gas	Hydrogen Sulfide, Some Formaldehyde	Water / Specialized Absorption Liquid

Product Features

The PP waste gas scrubber features a mature process, wide treatment range, and stable operation, making it the most versatile wet scrubber. Key features include:

Mature liquid absorption process ensures stable and reliable purification effect
Countercurrent gas-liquid contact in packing layer achieves high mass transfer efficiency
Multiple water-soluble gases can be treated by simply replacing the absorption liquid
PP or PPs tower body and packing resist acid-base corrosion with long service life
Demisting plates remove moisture and mist, minimizing liquid carryover in fan exhaust
Circulating liquid reuse reduces water and chemical consumption, enhancing operational economy
Standardized specifications allow multi-stage Series and automatic dosing

Tank Material	PP / PPs Sheet
Purification Process	Liquid Absorption Method
Core Components	Filler layer with spray nozzle
Gas-Liquid Flow Direction	Counter-current contact
Dehydration Components	Defogging Plate
Absorption fluid	Select according to exhaust gas
Circulation Mode	Tank Bottom Water Circuit
Corrosion resistance performance	Acid-alkali-resistant salt
Configuration Form	Single-stage / Multi-stage Cascade
Specifications and Features	By airflow series

Application Industries

Acid-alkali and water-soluble tail gas absorption and treatment in chemical workshops
Centralized exhaust gas washing in electroplating and surface treatment parks
Acid-alkali exhaust air purification in semiconductor, photovoltaic, and electronic factories
Water-soluble component absorption of reaction tail gas in pharmaceutical factories
Acid mist control in pickling and battery industries
Odor gas washing of hydrogen sulfide, ammonia, etc. in wastewater treatment stations
Comprehensive exhaust air centralized wet purification in laboratories

Typical Process Locations

The PP exhaust gas purification tower is installed between the polluting workshop and the fan. The exhaust gas is transported from the hood and duct to the lower inlet of the tower. Inside the tower, the exhaust gas rises from bottom to top through the packing layer, spray layer, and demisting layer, and is purified before entering the corrosion-resistant fan at the top or side outlet for compliant discharge through the exhaust stack. The circulating water pump, chemical addition tank, and control cabinet are arranged near the tower body, and the water tank effluent is connected to the wastewater treatment station. When treating multiple incompatible exhaust gases, they should be processed in separate systems and towers, such as acidic and alkaline exhaust gases, and cyanide-containing exhaust gases cannot be mixed in the same tower or duct to avoid hazardous reactions.

During installation, the tower body is vertically fixed on the foundation, with the weight of the equipment and liquid being supported by the foundation. Flexible connections and independent brackets are installed on the duct. The startup sequence is to first start the circulating water pump to fully wet the packing and ensure normal spraying, then start the fan to draw air; the shutdown sequence is the opposite. Key operational management focuses on maintaining the absorption liquid concentration and level, normal spray pressure, unobstructed packing, and effective demister. Regularly test the inlet and outlet concentrations and circulating liquid indicators, and maintain records of chemical addition, effluent discharge, and maintenance.

Both are essentially packed spray absorption towers, with the same working principle and structure. The main differences lie in their positioning and configuration focus: the acid mist purification tower is optimized for acid mist treatment, with the absorption liquid primarily being alkaline, emphasizing the treatment of acidic gases such as hydrochloric acid mist and sulfuric acid mist; the PP exhaust gas purification tower is a more general platform product, capable of treating acidic, alkaline, and other water-soluble exhaust gases by selecting different absorption liquids, with a broader scope of treatment targets. When selecting, there is no need to be overly concerned with the name; the key is to determine the absorption liquid, packing, and tower configuration based on the exhaust gas composition, concentration, and airflow, with the manufacturer completing the process design.

It is generally not recommended to mix acidic and alkaline exhaust gases in the same tower for simultaneous treatment, as the absorbent can only maintain one pH level, and certain gas mixtures pose safety risks. For example, mixing cyanide-containing exhaust with acidic gases may produce highly toxic hydrogen cyanide gas, while ammonia mixing with acid mist can form ammonium salt crystals that block the system. The correct approach is to separately collect, transport via dedicated pipelines, and treat acidic, alkaline, cyanide-containing, and organic exhaust gases in individual towers, each using the corresponding absorbent. Shared equipment can only be considered when the components are compatible and the process allows for alternating operation. Specific requirements must be determined by process design in accordance with safety regulations.

A single-stage packed tower has its absorption capacity limit. When the exhaust gas concentration is high, the required removal efficiency is high, or the solubility of pollutants is low, the gas-liquid contact time and mass transfer stages are insufficient, and a single tower cannot meet the standards. In engineering, two-stage packed spray Series , increasing the packing height and spray volume, or increasing the liquid-to-gas ratio can be adopted. Intermediate circulation can be set between the two stages of the tower to allow pollutants to be absorbed step by step. Whether multiple stages are needed should be determined by designers based on material balance and absorption calculations, and cannot be simply scaled up from a single tower. High concentration and fast-reacting gases can be handled with a single stage, while difficult-to-absorb or strictly regulated emissions often require multiple stages.

Airflow reduction is typically caused by increased system resistance, with the most common cause being the blockage of the packing layer by salt crystallization, dust, and sludge. The next most common causes are fouling and blockage of demisters, nozzle blockage leading to increased liquid carryover resistance in the tower, and liquid accumulation in ducts. Check the pressure drop and blockage locations section by section: clean or replace the packing, clean the demisters, clear the nozzles, drain the sediment from the sump, and enhance pre-treatment dust removal and circulating liquid filtration. Fan belt slip and impeller scaling can also reduce airflow, requiring simultaneous inspection of the fan. Establishing a regular flushing and pressure drop monitoring system can detect blockages before a significant drop in airflow occurs.

Fog Grid (Dehumidifier) is used to capture and purify liquid droplets carried by the purified gas, returning the droplets to the water tank, protecting downstream fans and ducts, reducing water carryover and chemical loss in the exhaust stack, and is an essential component of wet scrubbers. Removing the fog grid will allow alkaline or acidic liquid droplets to enter the fan, corroding the impeller and ducts, causing fan vibration, and leading to water dripping and white smoke in the exhaust stack. Fog grids are available in baffle and mesh types. Regular cleaning should be performed during operation to prevent blockage, and damaged grids should be replaced promptly. Do not remove the fog grid due to concerns about blockage.

To confirm the complete composition and concentration of the exhaust gas (including dust content, oil content, water content, and temperature), treatment air volume and fluctuation range, emission compliance standards, available absorbents, and wastewater treatment destination, installation site, and fire safety requirements. The composition determines the absorbent and whether mixed towers are feasible, concentration and standards determine the tower diameter, packing stages, and liquid-to-gas ratio, temperature determines material selection and whether pre-cooling is required, and dust and oil content determine whether pre-treatment is necessary. Installing equipment without clear conditions may lead to issues such as incorrect absorbent selection, undersized tower diameter, packing blockage, and non-compliant treatment. In such cases, exhaust gas testing should be conducted before design.

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