The Dow Chemical Company has been operating in Stade, Germany for more than 40 years. Nearly three million tons of basic and specialty chemicals are manufactured per year in this ultramodern integrated plant complex, placing high availability and safety demands on all components. That’s why Dow has installed a custom-designed butterfly valve, developed by Neles, to reliably shut off the DME reactor in Stade.
Around 4 billion euros have been invested over the years to optimize existing plants and to build new ones. Experience has shown that every single component matters. The search for the ideal valve solution turned out to be a long and costly task. Gate valves, ball valves and plug valves were installed, tested and rejected over the years.
As SPP coordinator Ludger Michalczak is responsible for making changes to instrumentation and pipework at three of the 16 plants. One of these plants is the chloromethane plant for processing dimethyl ether (DME). The fixed bed reactor must be separated from the nearby process and sealed with a valve when maintenance personnel enter it. The reactor must also be isolated in case of an emergency to prevent emissions.
Challenges: Coke fines and heat
“This valve must close on demand with 100% safety and reliability. The problem is that we have an exothermic catalyst, which is a chemical reaction with heat, which produces coke. Both the coke fines and the heat kept damaging the first valves and causing them to fail.” Ludger Michalczak sums up the problem, “We have extreme processes here, so we need extreme solutions.”