Are you using the fiber mist eliminator in the dry scrubber correctly?

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In recent years, I have visited many sulfuric acid plants, and a common phenomenon is that at the outlets of the dry absorption three-tower mist eliminators in many of these plants, the acid mist levels are within acceptable limits; however, there is a significant amount of acid present in the downstream pipelines and gas-to-gas heat exchangers. The aforementioned situations include two aspects. First, it is not possible to determine the performance of a demister solely based on the test data of acid mist at its outlet. It should be noted that in China’s sulfuric acid industry, the cotton ball method is still primarily used for collecting acid mist (an ion chromatography system costs dozens of thousands of yuan, which is unaffordable for small and medium-sized factories). An acid foam separator is often installed before the six-ball device, which results in lower values when testing the acid mist (foam). Secondly, the phenomenon of secondary entrainment in fiber mist eliminators is often overlooked by many people working in the sulfuric acid industry. In the case of a vertically installed cylindrical mist eliminator, acid mist is captured by the fiber bed on the inside, resulting in the formation of acid droplets; these droplets create a liquid film on the outside of the bottom of the cylindrical mist eliminator. When this liquid film is broken apart, secondary entrainment occurs. Therefore, when using fiber mist eliminators, two points need to be kept in mind: first, the performance of the mist eliminator cannot be judged solely based on the acid mist test results; second, attention must be paid to secondary entrainment by the mist eliminator. A good fiber mist eliminator will be equipped with a secondary entrainment prevention layer.