Oct. 2019: The Superior Refinery is committed to keeping the community up to date on what's happening as the rebuild begins.

HF Neutralization

To prepare for the installation of additional safety features at the alkylation unit, which houses the hydrogen fluoride (HF), and to enable construction to proceed as safely as possible, the Refinery neutralized the HF that was stored at the facility.

Why neutralize the HF?

  • Facilitates the installation of additional safety measures at the alkylation unit, which houses the HF.
  • Enables construction to proceed as safely as possible.

What is neutralization?

  • In general, neutralization is a reaction between an acid and a base that results in the formation of a salt and water.
  • The HF (the acid) stored at the Refinery was mixed with potassium hydroxide (the base, commonly known as lye) and water. The reaction produces potassium fluoride salt and water. 

Understanding the process

  • The Refinery used a neutralization system designed and operated by industry experts.
  • The major components included a Neutralization Container, several Neutralized Solution Containers and connecting piping.
  • The reaction occured in the Neutralization Container; the resulting potassium fluoride salt and water was stored in the Neutralized Solution Containers.

 

HF Neutralization
  • The neutralization process

Step #1 – A solution of potassium hydroxide and water is placed in the Neutralization Container.

Step #2 – Nitrogen (a gas that does not react with HF) is pumped into the HF Storage Drum to facilitate the flow of HF to the Neutralization Container.

Step #3 – The Isolation Valves are opened; the Control Valve controls the flow rate of HF being transferred to the Neutralization Container.

Step #4 – A Sparge Bar is submerged in the potassium hydroxide solution to help evenly distribute the HF in the Neutralization Container; the HF is neutralized upon contact with the potassium hydroxide solution.

Step #5 – Reaction conditions, such as the HF flow rate and the temperature, are monitored during the process. When the potassium hydroxide has been used up, or spent, the remotely operated valves are closed and the transfer of HF ceases.

Step #6 –The end products – potassium fluoride salt and water – are transferred from the Neutralization Container to a Neutralized Solution Container.

Step #7 – The cycle is repeated, starting with Step #1 until all the HF is neutralized.

Each cycle takes about 3 hours and all the HF is expected to be neutralized in about 3 days. Once the neutralization process is completed, the Refinery will dispose of the potassium fluoride salt and water at a permitted disposal site.

Safety measures and procedures

  • Safety is at the center of all the Refinery's activities.
  • The neutralization work was conducted during daylight.
  • The Refinery used both existing and additional safety measures during the neutralization process.
  • Existing multiple layers of protection around the HF Storage Drum include a water curtain and water cannons; an overview of the safety measures is provided in the HF Alkylation & Safety video.  
  • Additional safety measures during neutralization included enhanced leak detection, water cannons, and air monitoring.
  • Refinery personnel consulted with local and regional first responders and the Refinery's Emergency Response Team was on-site.