How can sulfur corrosion in flue gas expansion joints be solved or mitigated?

When processing crude oil with a high sulfur content, the high-temperature decomposition of sulfides leads to a significant increase in the levels of SO2 and SO in the flue gases under conditions of high oxygen content. At low temperatures, these substances combine with steam present in the flue gases to form sulfuric acid, which then condenses on the surface of metals at or below the dew point temperature of the flue gases, thereby corroding the metals. Additionally, at low temperatures, the dew-point corrosion caused by Cl- also poses a serious threat to bellows, as these components not only have thin walls but are also prone to accumulating liquid. 1) Improve the material of the expansion joint bellows by using FN-2 high-alloy steel or Incoloy 800; these materials can effectively resist pitting and intergranular corrosion, and are suitable for corrosive environments involving sulfides such as polysulfuric acids in combination with Cl-. They belong to the Fcr-Ni series of high-alloy materials. 2) The expansion joints are subjected to strict solution treatment in accordance with standards before leaving the factory, in order to eliminate the deformation stress and residual stress generated during the manufacturing of the bellows ； The aluminum silicate fiber mat between the wave shell and the inner guide cylinder is removed; a stainless steel sealing mesh sleeve is installed at the open end of the guide cylinder and pressed tightly to increase the surface temperature of the wave shell, preventing water vapor from condensing inside it and thus avoiding the adsorption and concentration of CL- ions. 3) The installation of expansion joints shall be carried out strictly in accordance with the plan; pre-deformation methods shall be used to reduce assembly stress, and welding procedures shall be followed rigorously to minimize welding stress as much as possible. 4) During the start-up, shutdown, heating, and cooling processes, as well as when increasing the amount of cooling steam to the wheel disc for safe operation, it is necessary to open the flue ducts and the drain valves at the bottom of the smoke extractor as much as possible, in order to prevent the accumulation of corrosive substances.

I agree with the 1# opinion! As a supplementary note: Nowadays, when processing high-sulfur crude oil, a sulfide transfer agent is generally used in a regenerator. Bring the sulfides in the flue gas to the reactor, and they are carried away with the oil and gas. Sulfur is produced after purification.

Thank you, 2nd floor! Learned * again! As a supplementary point: In typical catalytic units, a standby unit is brought online, or the flue gas exhaust system is not activated at first; this is done to keep the temperature of the flue expansion joints low, thereby reducing the risk of dew point corrosion! The smoke machine should be turned on as soon as possible to raise the temperature!

The bellows material should be FN-2 or B315

The points raised by the previous posters are quite good; I would just add that effort should be made to prevent steam from entering the flue gas system. The corrosion caused by sulfur in flue gas is mainly acid corrosion resulting from the reaction of sulfur dioxide, sulfur trioxide, and water vapor. It is also best to raise the temperature at the expansion joint to avoid the dew point corrosion temperature.

Our device primarily reduces sulfur corrosion by raising the temperature of the expansion joint, that is, by adding a thick insulating layer on the outside.

Since the flue gas contains high levels of sulfur, Inconel625 is chosen as the material for the bellows due to its strong corrosion resistance; it is manufactured through hydraulic forming, which provides excellent corrosion protection.