Demystifying Sulfur Removal: New Fixes to Old Problems

Did you know that oil refineries in the United States alone produce more than 40,000 tons per day of elemental sulfur? This eye watering figure is a direct result of modern air quality rules that require refiners to remove sulfur compounds that are naturally found in oil and gas deposits. In fact, nearly all sulfur on the market today is produced as a byproduct from the petroleum industry. This capacity is made possible due to the Claus unit where hydrogen sulfide (H2S) is reacted with sulfur dioxide (SO2) to form elemental sulfur which is subsequently condensed from the process stream.

Despite what the production figures may suggest, operating a Claus unit?is no easy task. In order to function optimally, two-parts of H2S must react with one-part SO2. This is done by partially burning the H2S in a furnace to SO2. Process disruptions such as a burst of hydrocarbons in the feed can upset this balance. In this case, the oxygen tends to react with the hydrocarbons first before reacting with the H2S. This will cause the plant to deviate from the optimal stoichiometric ratio for the process.

Plants counteract this problem with an air demand analyzer typically located towards the end of the unit. This tool monitors the ratio of H2S to SO2 to ensure the appropriate amount of air is?being fed to the Claus furnace. Unfortunately, analyzer plugging is a problem that can plague Claus plant operators. A cold spot in the sample line for the analyzer can cause a sulfur plug to form. Sometimes this can cause an analyzer to read zero, or in other cases it can act like a cuvette and hold the sample. No amount of intervention from the operations team will cause the analyzer to respond because it’s no longer representative of the process. Clearing these sulfur plugs is both time consuming and hazardous. Put simply there needs to be a better way to deal with this problem.

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Applied Analytics solved this problem with our revolutionary TLG-837 air demand analyzer and DEMISTER Probe. The design eliminates the requirement for sample lines by performing the measurement in-situ (or in place) inside the DEMISTER probe. It also prevents sulfur plugs by condensing sulfur vapor to a liquid and removing it from the sample stream inside the probe. Be sure to check out our website if you’d like to learn more.