SDG Dry Acid Mist Adsorption Box

Product Model	SDG Dry Acid Gas Adsorption Unit
Category	Waste Gas Treatment Equipment
Reference Price	Price on request

Hot Customizable for Working Conditions 10 Technical Parameters

Product Overview

The SDG Dry Acid Mist Adsorption Box is a water-free and non-circulating chemical dry acid gas purification equipment. It is filled with SDG composite acid gas adsorbents (a dry adsorption filter material composed of alkaline and porous mineral materials) inside the box. Acid mist-containing exhaust gas passes through the adsorbent layer under the action of a fan, where acidic gases are adsorbed and chemically reacted with the adsorbent, fixed in the filter material, and then directly discharged. It is primarily used for purifying various acidic gases such as sulfuric acid mist, hydrochloric acid mist, nitric acid mist, and hydrofluoric acid mist. It is particularly suitable for applications where water washing is not feasible, in cold regions, or where wastewater generation is undesirable.

Compared to spray washing towers, the SDG Dry Adsorption Box has distinct features: First, it can purify multiple acid gases simultaneously, showing good removal efficiency for common inorganic acid gases; Second, it has high purification efficiency, with the thickness and loading of the filter layer designed according to treatment requirements; Third, it is simple to maintain, requiring no pumps, nozzles, or circulating water systems, only periodic replacement of adsorbents; Fourth, it has no freeze protection requirements, and dry operation eliminates pipeline and tank cracking issues in winter in northern regions; Fifth, it is safe to use, operating without water or chemical solutions; Sixth, it produces no secondary pollution, generating no wastewater, and exhausted filter materials are treated as solid waste.

Xicheng Environmental can design SDG Dry Acid Mist Adsorption Boxes according to the type of acid gas, concentration, and treatment airflow. The filter material type, loading, layer thickness, and replacement cycle are determined. The box body can be made of PP, PPs, or anti-corrosion carbon steel. The filter material is loaded and replaced via drawer or filter cartridge systems, and it can be used alone or in series with spray towers and activated carbon boxes to form multi-stage treatment processes.

Working Principle

SDG Dry Adsorption is a process where chemical and physical adsorption work together. The SDG adsorbent is a porous alkaline composite material with a large specific surface area and reactive active components. As acid-containing exhaust gas passes through the filter layer, acidic gas molecules first diffuse into the adsorbent pores and are physically adsorbed. Subsequently, they undergo acid-base chemical reactions with the alkaline active components, forming stable salts that are fixed within the adsorbent, thereby permanently removing them from the gas phase. For example, sulfuric acid, hydrochloric acid, nitric acid, and hydrofluoric acid gases react with the alkaline components to form corresponding salts, and the reaction products do not volatilize, resulting in purified gas.

As the reaction progresses, the active components in the adsorbent are gradually consumed, forming a reaction zone from the inlet side to the outlet side of the filter layer. When the reaction zone advances to the end of the filter layer and the outlet acid gas concentration reaches the breakthrough value, the filter material becomes ineffective and needs replacement. A thicker filter layer and longer residence time allow for more thorough contact between acid gases and the adsorbent, resulting in higher purification efficiency. Therefore, the loading amount and layer thickness of the filter material can be designed to ensure high purification efficiency and a reasonable replacement cycle. The entire process is dry, without water spraying or circulating liquid, so no wastewater is generated, no nozzle clogging or winter icing occurs, no pumps or chemical dosing systems are required, and equipment operation and maintenance are greatly simplified.

Structural Composition

The SDG Dry Acid Mist Adsorption Box consists of a box body, an adsorbent bed, filter material support, airflow distribution plate, inspection door, and inlet and outlet ports. The box body is a rectangular sealed box with PP, PPs, or anti-corrosion carbon steel material, reinforced outer walls, and one end for inlet and the other for outlet. Inside the box, one or more adsorbent beds are installed, composed of support grating, porous plates, and filter screens, with SDG adsorbents loaded into the bed frame.

The adsorbent can be loaded via drawer-type filter frames or filter cartridges, which are pushed into the box along rails and sealed tightly. For replacement, old filter frames are removed, and new ones are installed, offering convenient operation. An airflow distribution plate on the inlet side ensures uniform passage of acid gas across the entire filter layer cross-section, preventing bypass and premature breakthrough. The box is equipped with an inspection door, a differential pressure gauge port, and a sampling port to monitor filter layer resistance and outlet concentration. The bottom is fitted with legs and a dust discharge port, while the inlet and outlet ports are connected to ducts via flanges. For multi-stage purification, different functional filter layers can be arranged inside the box.

Specification Model Table

The following table compares the characteristics of SDG Dry Adsorption and Spray Washing, with selection based on site conditions.

Item	SDG Dry Adsorption	Spray Washing
Medium	Dry composite adsorbent	Water and absorbent
Wastewater	Does not produce wastewater	Has circulating wastewater
Freeze Protection	No freeze protection required	Needs freeze protection in winter
Maintenance	Periodic filter replacement	Pipe, pump, and chemical maintenance

Product Features

The SDG Dry Acid Mist Adsorption Box features dry purification, multi-acid treatment, and simple maintenance, making it an ideal equipment for acid mist control in water-free and cold regions. Its main features are as follows.

Simultaneous purification of multiple acid gases, wide applicability
Chemical adsorption fixes acid gases, high purification efficiency
Filter material loading and layer thickness can be designed as needed
Dry operation without water, no wastewater or secondary pollution
No pumps, nozzles, or chemicals, simple maintenance and low failure rate
No freeze protection required, suitable for cold and water-scarce regions
Safe to use, with convenient drawer-type filter replacement

Box material	PP / PPs / Corrosion-Resistant Carbon Steel
Purification Medium	SDG Composite Adsorbent
Purification Principle	Dry Physical Chemical Adsorption
Object Processing	Multiple acidic gases
Operating Mode	Dry, no water required
Filling Method	Drawer-type Filter Frame
Wastewater Generation	No wastewater
Freeze Protection Requirements	No antifreeze requirements
Replace Basis	Export Concentration / Pressure Difference
Specifications and Features	Designed based on airflow

Application Industries

Acid Mist Treatment in Cold Northern Regions (Freeze-Proof)
Acid Gas Purification in Water-Shortage or Difficult Drainage Areas
Multi-Acid Gas Mixed Exhaust Treatment in Chemical and Pharmaceutical Workshops
Dry Acid Mist Purification in Laboratories and Testing Institutions
Acid Mist Treatment in Metallurgical Pickling and Battery Industries
Acid Gas Treatment Where Waste Water Generation is Unwanted
Series Equipment for Deep Acid Gas Purification After Spraying Tower

Typical Process Location

SDG Dry Adsorption Box is installed between the acid gas collection duct and fan or after the fan. The exhaust gas passes through necessary pre-treatment (dust and mist removal to ensure the gas entering the filter medium contains no significant dust or droplets) before entering the adsorption box. The gas flows horizontally or vertically through the filter layer, where acid gas is adsorbed and purified. The purified gas is discharged through an exhaust stack. The equipment can be used in single-stage for treating moderately concentrated acid gas, or arranged after a spraying tower as a deep purification barrier. The former is suitable for low-concentration waterless scenarios, while the latter is used for high-concentration acid gas requiring high removal rates.

During installation, the box is positioned and leveled. After inserting the filter frame, the sealing gaskets are compressed to ensure the airflow passes completely through the filter layer without bypassing. Inlet and outlet ports are connected according to airflow direction markings. Before operation, record the filter loading date, initial pressure drop, and outlet concentration baseline. During operation, monitor pressure drop changes (to detect dust blockage) and outlet acid gas concentration (to detect breakthrough). When replacement criteria are met, remove the filter frame to replace SDG adsorbent. Waste adsorbent contains reaction-generated salts and residual acid. It should be properly disposed of as solid waste according to its properties and local regulations, with replacement records retained.

In scenarios with moderate acid gas concentration, low gas volume, water scarcity, or where cold conditions make water washing inconvenient, SDG dry adsorption can be used alone and achieves excellent results without wastewater or anti-freeze issues. However, for high concentration, high-temperature, high-humidity, or exhaust gases containing heavy mist droplets and dust, spray washing offers greater advantages in processing capacity, cooling, and adaptability. In such cases, it is recommended to first treat most of the acid gas with a spray tower, then use an SDG dry adsorption unit for final deep filtration. These two methods are not simple substitutes; they should be selected based on acid gas concentration, gas volume, temperature and humidity, on-site water supply and drainage conditions, and economic factors, and can also be used in series for complementary effects.

The replacement cycle depends on the type of acid gas, concentration, airflow, filter loading, and actual operating time. It can be theoretically estimated based on the adsorbent capacity and acid gas generation rate. During operation, the replacement point is determined by monitoring the outlet acid gas concentration. The filter media should be replaced when the outlet concentration approaches the emission limit (penetration point); it should also be replaced or treated if the pressure drop across the filter bed significantly increases, the filter media becomes clogged with dust, or it becomes hardened. In design, the filter media quantity is determined to ensure purification efficiency and a reasonable replacement cycle (typically lasting several months). During operation, establishing pressure drop and concentration records is more scientific than replacing based on fixed days, avoiding waste from premature replacement or exceeding limits due to delayed replacement.

Yes. Although the SDG process does not have water and scaling issues, if the exhaust gas contains dust, oil mist, or a large number of droplets, dust will adhere to the filter media surface, and liquid droplets will cause the filter media to become damp and cake, leading to increased resistance and uneven airflow distribution. Therefore, dust removal, oil removal, and fog removal pretreatment should be performed before the gas enters the cabinet to maintain relatively dry and clean exhaust gas. If the pressure differential rises, first check whether the pretreatment filter media has failed or whether the filter media surface has accumulated dust. Clean or replace the surface filter media if necessary. Proper pretreatment and airflow distribution are key to extending the service life of SDG filter media and preventing blockages.

The process itself does not use water or generate wastewater. The salt produced during the adsorption reaction is fixed within the adsorbent, and there is no wastewater or mist emission during operation, resulting in minimal secondary pollution. However, saturated SDG adsorbents contain acid reaction byproducts and residual chemicals, which are classified as solid waste requiring regulated management. They should be collected, temporarily stored, and disposed of according to their composition and local environmental regulations (typically handled by qualified units), and should not be dumped arbitrarily or mixed with domestic waste. As long as the waste filter media is disposed of properly, the secondary pollution risk of dry adsorption is significantly lower than that of wet processes that generate wastewater.

Dry adsorbents are suitable for treating acid gases at room temperature with relatively low humidity; excessively high gas temperatures may affect adsorption performance and the lifespan of the housing material, while high humidity and liquid presence can cause the adsorbent to dampen, cake, and increase resistance. Before entering the adsorption chamber, high-temperature gas should be cooled, and high-humidity or foggy gas should be dehumidified and de-fogged. Although the equipment has no anti-freeze requirements (dry operation is not afraid of freezing in winter), condensation and rain should be avoided, and rain protection should be ensured for outdoor installation. The specific temperature and humidity applicability range should be confirmed with the manufacturer and designed according to the exhaust gas conditions.

Please provide the type of acid gas (sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, etc.), concentration, treatment air volume, exhaust gas temperature, humidity, and dust/fume content, the required purification efficiency and emission standards, installation site conditions, and water supply/drainage conditions, as well as the required cabinet material. The type of acid gas determines the adsorbent formulation, concentration and efficiency determine the filter media loading and filter bed thickness, air volume determines the cabinet cross-section, and temperature, humidity, and dust content determine the pre-treatment configuration. Clarifying these parameters is essential to ensure initial purification effectiveness and a reasonable filter media replacement cycle. Do not select based solely on air volume and cabinet size.

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