Description

Temperature measurement in the drying tower

Requirements

  • Chemically resistant PTFE
  • Connection heads available up to IP68

Description

DP Sump level measurement

Requirements

  • Level control

Description

Flow measurement of acid recirculation

Requirements

  • Suited choice of liner materials
  • Conductivity output optional

Description

Flow measurement of the liquid sulphur fed to the burner

Requirements

  • Liquid sulphur specialised instrument
  • Twin instrument option for for highest availability

Description

Flow measurement of steam from heat exchanger upstream of the contact furnace

Requirements

  • Energy/mass flow output
  • Live compensation of pressure and temperature

Description

Flow measurement of acid feed to final absorption

Requirements

  • Suited choice of liner materials
  • Conductivity output optional

Description

Temperature measurement in the absorbers

Requirements

  • Chemically resistant metal thermowells
  • Connection heads available up to IP68

Description

Level switch in buffer tank

Requirements

  • Extra safe with second process seal (ceramic)
  • WHG approval
  • SIL2/3-compliant

Description

Level measurement of tanks with concentrated sulphuric acid as the end product

Requirements

  • Overfilling prevention
  • Tank internal reflections can be eliminated
  • SIL 2/3 certified

Description

Integrated control valve with flow, pressure and temperature measurement of cooling liquid

Requirements

  • Cooling water management
  • local control/ separate DCS not necessary

Overview

Sulphuric acid extraction in inorganic chemicals

Instrumentation for fine-tuned temperature and pressure control

Sulphuric acid is usually obtained in a continuous double contact process. Firstly, liquefied sulphur is combusted as a raw material with dry air to make sulphur dioxide. The second stage involves further catalytically oxidising the sulphur dioxide in the contact furnace, the heart of the plant, using vanadium oxide to make sulphur trioxide. The exothermal balance reaction must be maintained in a temperature range between 400 and 600°C. To this end, the catalyst is layered in the furnace and the gas mixture flowing through the layers is repeatedly cooled to the right temperature by heat exchange and external gas cooling. As it is not usually possible to convert all of the sulphur dioxide in the first contact furnace, the non-absorbed sulphur dioxide is recycled through an intermediate absorber and passes through another contact layer after the first process in the double contact process. This ensures that much of the sulphur dioxide is converted. The sulphur trioxide produced in this way dissolves as sulphuric acid before being poured into tanks.

As the temperature in the contact furnace has to be kept within narrow limits during the reaction, very precise heat management and exact recording of the amounts of substances circulating are crucial for the efficiency of the process. This requires reliable and sturdy measuring equipment, which is what KROHNE has been providing for many years, including for example resistance thermometers with protective fittings and electromagnetic flowmeters for complex process applications with aggressive liquids such as sulphuric acid. These guarantee reliable, high-precision flow measurements, even in extremely harsh process conditions and at high temperatures.

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