Sulfuric Acid

Air drying occurs in towers, with the air crossing packing beds in countercurrent with sulfuric acid, which is highly hygroscopic and separates water from air. The packing bed consists of conventional ceramic packing, MaxiSaddles, or high capacity, MaxiSaddles BPC, which increases the capacity of plants with existing towers or reducing the diameter of new towers to the same capacity as the plant.

For the packing to be properly irrigated, high efficiency liquid dispensers will be needed above the drying bed, with MaxiFlow Tubes or MaxiFlow CD. In this way, the dry air reaches the top, but still with acid droplets resulting from the intimate contact of air and acid. The drops of acid are mainly responsible for corrosion throughout the plant. Therefore, a MaxiMesh mist eliminator must be installed before the air moves on to the plant.

The highly aggressive environment inside the towers, they may be in carbon steel coated with ceramic or metallic in CSX (UNS 32615). There are several important differences between both projects, but both are equally possible.

Consult Clark Solutions for more information.

Random packing| MaxiSaddle

Random packing | MaxiSaddle BPC

Liquid distributor | MaxiFlow

Mist eliminator | MaxiMesh

Gas absorption in towers involves the use of sulfuric acid to absorb SO3, increasing the concentration of the acid. Beds filled with MaxiSaddles or MaxiSaddles BPC are used to improve efficiency. Liquid distributors, such as MaxiFlow Tubes or MaxiFlow CD, ensure adequate irrigation. FiberBed mist eliminators are needed to remove acid droplets and fine mists. The towers can be made from coated carbon steel or CSX metal, both of which are viable options.

Mist Eliminator | MaxiMesh : MaxiMesh® mist eliminators consist of a mesh formed by extremely fine knitted (or co-knitted) threads that have a very high percentage of void.

Liquid distributor | MaxiFlow : Clark Solutions’ MaxiFlow® CD liquid dispensers are designed to optimize the transfer of gas-liquid mass to random ceramic packing.

Clark Solutions has developed compact, modular and highly efficient sulfuric acid plants, ideal for small-scale production. The plant uses direct sulphur burning, with SO3 absorption and gas washing. Its energy efficiency is higher than conventional plants, reaching 2 kg steam/kg acid. Composed of six to seven modules organized into eleven to twelve skids, it allows for easy transport and assembly in the field.

Clark Solutions’ sulfuric acid unit is a major energy generator, recovering around 70% in the form of high-pressure steam. To increase energy reuse, the company has developed a system that reuses energy from the recirculation line of the intermediate acid columns. This system is simple, safe and adaptable to existing units, minimizing initial investments.

The system involves transferring heat from the acid line to the turbogenerator condensate, avoiding any contact between the acid and the condensate. It is made of materials compatible with sulphuric acid and has integrated controls to ensure safety. The modular and compact skid facilitates installation with defined connections to the existing plant.

SAFEHR is a sulphuric acid cooling system that uses an indirect cooling circuit with inert fluid to increase safety, minimizing damage from leaks and the generation of hydrogen through corrosion. Consisting of two heat exchangers, the system cools the hot acid and heats the boiler water, increasing heat recovery and energy generation. SAFEHR can replace conventional chillers or connect to heat recovery towers, improving operational safety.

SAFEHX™ heat exchanger technology enhances the SAFEHR® process with a three-fluid design, maximizing heat exchange and minimizing the intermediate circuit. Using a safety fluid with an intermediate boiling point, SAFEHX™ promotes internal convection through density gradients, where the buffer fluid boils on the hot side, condenses on the cold side and returns. This continuous latent heat exchange process is more efficient than sensible heat exchange, allowing effective heat recovery without the need for an extra circuit, reducing the size of the system.

Clark Solutions has developed CSX and 310M materials as ideal for contact with sulfuric acid in equipment such as pipes, mist eliminators, distributors and tanks. These materials help control corrosion, ensuring superior durability and performance.

Acid pipes can have reduced diameters due to the lower acid velocity requirements in cast iron, and flexibility studies are carried out to avoid leakage problems. MaxiFlow liquid distributors and MaxiMesh mist eliminators can be manufactured in CSX or 310M, depending on the application.

Towers and tanks in CSX or 310M offer logistical and economic advantages, such as lower weight, faster manufacturing and reduced downtime costs, as they do not require additional coating.

After years of experience with coating towers for service in extreme conditions, having come into contact with various problems related to the coating and what causes failures, Clark perfected the technique of coating towers for sulfuric acid.

Made up of layers, the coating consists of stages for mechanical, thermal and, above all, chemical protection of the entire surface of the tower in contact with acid and gas. These steps are:

• Abrasive blasting
• Primer – Primary paint
• PTFE film
• Ceramic fiber mesh
• Anti-acid bricks

The composition of the layers and the specification of the materials have been developed over many years by understanding the mechanisms of wear and penetration of layers by acid during operation.

Our bricks follow the specifications for acid-resistant bricks, as defined by ASTM or DIN, with silica, alumina and contaminant contents strictly controlled. Bricks with different compositions will fail prematurely, posing risks to installation and operation.

(Português BR) O conteúdo residual de SO2 no gás de exaustão deve ser tratado quando sua concentração excede os limites ambientais, o que pode ocorrer em plantas de absorção simples, com regulamentações ambientais rigorosas ou baixa conversão. O SO2 pode ser recuperado com ou sem a geração de coprodutos. No primeiro caso, são utilizadas soluções de lavagem, como soda cáustica, peróxido de hidrogênio ou amônia, que reagem com o dióxido de enxofre para produzir compostos de alto valor agregado. No segundo, sistemas regenerativos com depuradores e strippers recuperam o SO2 sem gerar coprodutos, utilizando vapor de baixa pressão. A Clark Solutions oferece uma variedade de opções de dessulfurização, com tecnologias e equipamentos personalizados para cada aplicação, incluindo distribuidores de líquido MaxiFlowTM, recheios estruturados Maxipac® ou 3-PackTM e eliminadores de névoa MaxiMesh®.

(Português BR) O circuito ácido utilizado no manuseio de ácido sulfúrico conta com tanques e tubulações de materiais resistentes à corrosão. A Clark Solutions tem empregado aços inoxidáveis de alto teor de silício (HSSS), como o CSXTM, devido à sua alta resistência à corrosão em diversas temperaturas e concentrações de ácido, além de manter suas propriedades estruturais.

Tanques de ácido sulfúrico feitos dessa liga são mais leves (até 60% em comparação com opções revestidas de tijolo) e podem ser instalados rapidamente, sem a necessidade de aplicação de revestimento, o que é vantajoso em cronogramas apertados. A diluição de ácido é cuidadosamente estudada com simulações computacionais para otimizar a durabilidade dos tanques.

Clark Solutions também substitui tubulações de ferro fundido por HSSS, trazendo benefícios como menor risco de vazamentos, facilidade de manuseio, melhor qualidade do produto, e manutenção simplificada. O segredo do sucesso do CSXTM HSSS está em sua camada passiva de óxido de silício, que oferece alta resistência ao ácido e durabilidade em condições agressivas.