What happened at the Arkema Plant in Crosby, TX?
As everyone in Houston has heard, the Arkema plant in Crosby has been in a bit of a bind since Hurricane Harvey hit last weekend. The plant makes an organic peroxide which is the intermediate in the Cumene process and used to make phenol and acetone from benzene and propene. Benzene and propene are used in all sorts of things including pharmaceuticals and construction material. This is a pretty useful chemical and process!
At the Arkema plant, they had an inventory of cumene hydroperoxide which is all over the news (See the news story from KHOU). The chemical has not exploded (as of this writing) and started a fire yet, however it is inevitable.
How did they get to this point?
Cumene hydroperoxide is a PSM covered chemical, meaning the process has to have a Process Hazard Analysis (PHA) done on it every 5 years. The PHA looks at all possible issues and helps plants develop a priority for which aspects of the process contain a large amount of risk and which ones have less risk. This one would be a high risk! So, they implemented safeguards to protect the system to mitigate the risk and reduce damage to personnel, the environment, and the plant. They had cooling on the process and they had backup generators to power that cooling. They also utilized liquid nitrogen to keep the process cool. And they had refrigerated containers that they moved the chemical to. But it all depended on having power.
Are you protected against risk at your facility? Contact us to review your PHAs to make sure!
When the emergency generators were inundated with water, they no longer provided that power and they were unable to control the temperature. They had moved the chemicals into a refrigerated container and moved the containers away from the heart of the plant. Then they evacuated the plant. And the local authorities got involved and evacuated a 1.5 mile radius around the plant.
The chemicals are currently decomposing (decomposition starts at 158 deg F) and it is a self-accelerating decomposition, so once it starts, it keeps going and there isn't much to be done to stop it. The hydroperoxide material is decomposing into gas and causing pressure in the container. That container has a Pressure Relief Valve on it (another safeguard), and those have been going off since early Thursday morning. Pressure Relief Valves are generally used as a last line of defense to prevent a tank/container from exploding. However, they can only do so much. And there is no pressure control on the refrigerated containers that the chemicals are in. Hydroperoxides are oxidizers, which means they are capable of igniting flammable and combustible material, even in oxygen-depleted environments as well as increasing the intensity of a fire by adding to the oxygen supply. At that point they also cause ignition and rapid burning of normally non-flammable materials. Eventually, the refrigerated containers will fill with vapor from the decomposed hydroperoxide and that vapor will explode and start a fire.
At this point, fire is their friend. It would be beneficial to have the chemicals burn and accelerate
What else could have been done?
The plant did have Independent Protection Layers (IPL) in place to mitigate this emergency. Without seeing the PHA, it is assumed that the IPLs were sufficient to protect the process. This flood was completely unprecedented and there wasn't history to suggest a flood of this level would happen and cut off all power to the site including emergency backup generators. Other than providing cooling to the system to control the temperature, the other option would have been to provide a neutralizing chemical to react with the hydroperoxide and make it unreactive. However, it needs to be done in a very dilute environment such as a large lake-type area, not in the vessel. Of course, at that point, containment is a big issue as you would need a large surface area to spread out the chemical. A very dilute acid such as hydrochloric acid would help to neutralize it and turn it into water and salt.
Ultimately, they had the right controls in place. This storm was something that no one was able to predict and it dumped more rain than anyone would reasonably design for. It is still a scary situation, especially for those close to the facility, however it will burn itself out hopefully without too much damage to the surrounding community or the environment.
Have you had an incident as a result of Harvey? Contact us to help with your incident investigation or to review your processes and procedures to prevent future issues!