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Sulfuric Acid Process

Acid handling requires state-of-the-art processes. For concentration and purification of sulfuric acid, our tailor-made plants satisfy special requirements by combining the most modern technology with well proven materials.

KBR's sulfuric acid technologies can be used for concentration and purification of contaminated and spent sulfuric acid from many different applications and sources. KBR offers the fully corrosion-resistant sulfuric acid high-concentration SAVACO®-HT heat exchanger, TO-HeX, allowing up to 98 wt% H2SO4 with a proven lifetime of more than 30 years, which is a unique offering to the market and the most advanced technical solution available for this application.

“We have experience and references for our advanced sulfuric acid technologies for all processes requiring handling of spent acids.”

KBR has experience and references across all typical sources and processes that require handling of spent acids including:

  • Nitration processes, such as production of 2-EHN, MNT, DNT, TNT, NB, NCB, DNCB, NGL/NG, DEGN, EGDN, NC, picric acid, etc.
  • Chemical applications, such as production of MEK and sulfonation
  • Production of certain dyes and pigment
  • Chlorine drying
  • Gas purification 
  • Organic synthesis, such as ether production
  • Metallurgical application, such as lithium processing

KBR has already supplied plants for a wide range of applications and therefore is in the position to develop tailor-made solutions, which correspond to state-of-the-art process engineering, to be applied anywhere in the world. We also develop new applications of our technology and operate a lab with pilot plants that allow us to develop and scale up such new applications very reliably and efficiently for our customers.

Based on more than 70 years of experience in the field of acid treatment, KBR provides individual solutions for clients’ needs. We design small-scale plants, in which only a few hundred kilograms of acid per hour are recovered, up to world-scale plants.


Pre-concentration is used when the sulfuric acid stream is fairly diluted (20–60 wt%) to bring concentration up to 70–75 wt%. Pre-concentration is either processed at atmospheric pressure or at vacuum conditions. Different evaporator types can be used. For larger water evaporation capacities, multi-step evaporator systems are often used for energy saving purposes. The vapors of one step are used as heating agent for another process step.

Medium Concentration

This process is used to concentrate sulfuric acid from 70 wt% up to 85 wt%. The medium concentration of sulfuric acid is mainly operated at vacuum of about 80–150 mbar. At these conditions, medium-pressure steam can be used for heating and normal cooling water is used for condensation. In cases where higher temperatures are required — for example, needed in case of decomposition of certain organic contaminants — atmospheric evaporation at operating temperature up to 250°C is possible with our unique SAVACO®-HT TO-HeX heat exchanger.

High Concentration SAVACO®-HT

The PLINKE SAVACO® Process is used to produce high-concentration sulfuric acid up to 98 wt%. PLINKE developed a special heat exchanger operated with thermal oil as heating media at temperatures of up to 250°C showing no corrosion and having a proven lifetime of more than 30 years. At these conditions, the process runs very economically at a reasonable vacuum level, and very pure sulfuric acid is produced. If such high temperatures or concentrations are not required, other vacuum processes with steam-heated heat exchangers are available.


Spent acids from different processes often contain organic and inorganic impurities. These contaminants must be removed or their concentration must be minimized in order to allow for reuse of the sulfuric acid. KBR offers different chemical- and thermal-treatment processes for purification of spent acids, which can be combined with the concentration steps. If the concentrated sulfuric acid product shall be of highest purification grade, the PLINKE SAVAPO® process can be used, where the acid is completely evaporated and condensed, and consequently free of all non-volatile compounds.

Standardized SAVACO®-HT design for Spent Sulfuric Acid from Chlorine Drying

In chlorine manufacturing plants, the produced chlorine gas is dried by the means of sulfuric acid, which is consequently diluted. Typically, such diluted sulfuric acid is leaving this drying step at 75–78 wt% and needs to be re-concentrated to 96 wt% — or even 98 wt% — in order to be able to be reused. KBR has developed standardized sizes and designs for this application, as the capacities and feed, and product specifications are similar all around the world. Thus we are able to provide quick and cost-effective standard solutions for this application to our customers.

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Sulfuric Acid Process Opportunities

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