Simultaneous Process Monitoring of Sulphuric Acid Concentration and Mass Flow with Non-Intrusive Clamp-on Ultrasonic Technology

摘要

Continuous process monitoring of concentration, density or even mass flow are basic requirements for sulphuric acid production plants and chemical plants which use sulphuric acid as an important part of the production process. This is why approved analysers must be reliable and robust even when measuring aggressive fluids at high temperatures and high pressures in large pipes. Non-intrusive, ultrasonic clamp-on measuring technology is suitable for highly accurate measurement of high concentrations of sulphuric acid and mass flow without wetted parts from outside the pipe. This technology is maintenance-free, does not cause any risk of leakage and is highly cost-effective. Exotic materials of construction for aggressive fluids are not necessary, and equipment costs do not increase with pipe size or pressure ratings. Commissioning can be done directly on the main pipe without the construction of a bypass, nor require a plant shutdown. Given these advantages, ultrasonic technology is the method of choice for measuring the concentration and volume flow of concentrated sulphuric acid and also for a variety of other process liquids. Mass flow measurement is also feasible, and for this reason, is often used as an alternative to Coriolis meters. Replacing such intrusive meters leads to a significant increase in on-line production and energy savings. As well as an introduction to the physical conditions and limitations of the measuring principle, application examples in sulphuric acid production will also be shown. Advantages and limitations will be discussed. A complementary product using the refractive index to determine concentration and density will also be discussed. This complementary instrument measures diluted concentrations in sulphuric acid plants which cannot be monitored by the ultrasonic system. It is practically maintenance-free and allows for cost-effective substitution of other process instruments, such as, for example Coriolis meters.