You are currently viewing: Q&A

---

---

• In caustic (NaOH) regenerator column, the oxidation air nozzle are frequently plugging. The required temperature and caustic concentration are maintained as per design. How to solve the plugging issue permanently?

  Sep-2025

---

Answers

---

• Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br

  The plugging of air nozzles in caustic regeneration towers is a relatively common issue caused by the precipitation of insoluble compounds like mercaptans, sulfides and hydroxides like iron hydroxide. These contaminants are normally produced in the caustic solution due to the oxidation with the air leading to the physical block of the air nozzles causing poor performance of the spent caustic regeneration section. It's important to carry out an analysis of the solids present in the nozzles aiming to identify the composition of these contaminants in order to define the better solution strategy. If the iron content in the solids is high, the corrosion rate in the system tends to be higher than the design limits and actions to put the corrosion rate under control are needed. It's important to verify if the filtering system is adequate and, if there does not exist a filtering system, this should be designed and installed. Another good way to minimize this issue is through the optimization actions, once it is mentioned in the question that the temperature is under control other process variables like adequate air to caustic ratio can solve the issue. Again it's fundamental to verify the filtering systems of air and caustic soda feeds and install these systems if they are not already installed, another important question is related to the air quality, an humidity excess in the air can potentialize the clogging issues in the air nozzles as well as check if the supplier if the air nozzles opening are adequate for the operation conditions, in some cases, a simple change of air nozzles to high opening nozzles can minimize the clogging issues.

   

  Sep-2025