Sulfuric Acid

Knight Material Technologies can provide sulfuric acid manufacturers assistance in solving mass transfer and operational problems in the gas cleaning, drying and absorption towers. We have helped customers increase their tower’s capacity and improve gas-liquid distribution while providing longer service life with lower pressure drop.

From simple tower packing and internal change-outs to complex tower upgrades with high-efficiency tower packing to complete new design and construction, we offer a complete turnkey package from a single system supplier.

Select a numbered area on the image to learn more.

1.Multi-Point Trough Distributors

Liquid Distributors deliver continuous and precise distribution of acid for optimum absorption efficiency, minimum mist generation and maximum service life of downstream equipment in sulfuric acid plants.

Corrosion resistant alloy Liquid Distributors reduce installation, maintenance, and lifecycle costs. They have significantly lower lifecycle costs than conventional designs in cast iron.


FLEXISADDLE® Ceramic Random Packing

This is the most widely used random, mass transfer media on the market today. Its unique form provides a highly effective surface area and a low resistance to the air flow for mass and heat transfer optimization. Due to its high quality, it provides economic value for applications worldwide:

  • Random packing is a spray catcher that removes large acid droplets before the candles
  • Available in various sizes
  • Void spaces from 69%-77%


Flexeramic® Ceramic Structured Packing

Structured media with geometrically arranged corrugated sheets offering superior operation over saddle random media. Our proprietary media designs provide greater resistance to fouling than random or monolithic media:

  • Reduce bed depth
  • Minimize plugging
  • Maximize gas distribution in the bed
  • Increase capacity in the unit
  • Reduce fuel costs
  • Lower pressure drop
  • Utilize entire bed instead of a fraction
  • Uniform gas distribution

4. Cross Partition Rings

Cross Partition Rings Used with Random Packing

Rings with a cross-shaped septum have a high resistance to acids (>99.6%), virtually no water absorption (<0.5%) and a resistance to at least 10 heat cycles. Ceramic rings have high throughput and low pressure drop. This reduces the energy costs for pushing a gas mixture through the column and increasing the tower efficiency.


Knight-Ware® KPS Self-Supporting Dome and Packing Support

Our Self-Supporting Domes provide more than 60% open area before the tower packing is installed, offering a significantly increased open area over standard grid bar designs and providing:

  • Reduced pressure drop
  • Less maintenance
  • Ease of retrofit and new construction applications

6. DURO Acid Brick®

Duro® Acid Brick and Chemical-Resistant Mortar

Our bricks maintain corrosion resistance in high-temperature and strong acid concentration environments, conforming to ASTM 279 specifications. DURO® brick is manufactured in standard and custom shapes and sizes. Our proprietary mortars are formulated to bond our brick lining systems to meet most corrosion requirements. We offer a variety of mortar types and formulations to service most strong acid and high temperature process environments.

7. PTFE (Polytetrafluoroethylene)

PTFE (Polytetrafluoroethylene) Duply Liner

PYROFLEX® Duply lining consists of PYROFLEX® membrane with a PTFE overlay. The PTFE overlay is installed on top of the PYROFLEX® to provide an additional layer of protection and acid resistance.


Pyroflex® Acid-Resistant Membrane

PYROFLEX® Acid-Resistant Membrane is a flexible, uniformly thick sheet membrane used as an acid-resistant barrier between acid-resistant brick and corrosion prone carbon steel. PYROFLEX® is fused directly to a properly cleaned and primed surface without the use of an adhesive to provide a continuous, uniform lining with no joints. It also acts as an expansion-absorbing material between the masonry and the steel or concrete shell.

9. Carbon Steel Shell

In direct contact with acid, the Carbon Steel Shell, that constitutes the main structure of the tower, is not resistant to acid attack, progressively deteriorates and therefore requires protection.


Markets and Applications


Quench Vessels  |  Drying Towers  |  Intermediate Towers  |  Inter-Pass Absorption Towers  |  Final Absorption Towers  |  Pump Tanks  |  Phosphoric Acid Reactor  |  Surface Protection

Frequently Asked Questions

Drying towers are used in sulfuric acid plants to remove water from the incoming gas either produced by burning sulfur or as a cleaning process in a metallurgical plant.  The droplets are created by spraying liquid acid onto packing where the air is being run countercurrent. This step is crucial to obtain a dry gas to go into the converter.

Absorbing towers are designed to remove sulfur trioxide from the gas.  In a single absorption acid plant there is only one tower located before the stack.  In a double absorption plant, there are two Absorber Towers, the first generally located after beds 2 or 3 of the converter and the second tower – final -located before the stack.   The absorption of SO3 by the circulating acid stream increases the acid concentration and through the process of dilution, the product of concentrated sulfuric acid is produced.

In practice, the acid concentration and temperature are varied within the range to achieve the best tower performance.  Each tower seems to have its unique operating point at which it performs best.

Materials used in an absorption tower depend on the specific application and the chemicals involved. Common materials include various types of corrosion-resistant plastics, metals such as stainless steel or alloy materials, and lining materials like rubber, resinous membranes, or Teflon covered by a layer of brick. The choice of material is critical to withstand the corrosive nature of the chemicals involved in the absorption process.

Increasing the production of sulfuric acid can be achieved by optimizing process efficiency by using more advanced mass transfer media like structured packing, upgrading equipment, and improving catalysts in the converter. Process improvements, such as heat recovery and environmental control, can also enhance production while minimizing energy consumption and emissions.

The absorption tower in a sulfuric acid plant is a critical component of the process. It is designed to absorb sulfur trioxide gas (SO3) from the gas stream generated during the combustion of sulfur or from a byproduct in the roasting process or flash smelters to produce sulfuric acid. This tower typically contains a liquid absorbent, usually diluted sulfuric acid, in which the water diluent reacts with the SO3, leading to the formation of concentrated sulfuric acid.

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