Start-Up and Shutdown Procedure of CPO

Alternatively, one can introduce either NH3 or H2 with air and either decrease or eliminate the need for preheat. These reactions will proceed at much lower temperatures and provide the heat necessary to warm the catalyst before switching to the desired fuel. When the catalyst temperature is high enough, NH3 or H2 can be incrementally replaced with the desired fuel. It should be stressed that the feed composition should always be outside the flammable range in order to avoid upstream flames. In fact, in practical design, flashback protection and temperature alarms are common in the upstream portion of CPO reactors. 

Yet another approach to initiate a CPO reaction is by the use of spark ignition. This technique uses an electric spark situated slightly upstream of the catalyst to ignite a stoichiometric mixture of methane and air for combustion. This feed composition is then altered to the desired composition. This technique has been used for rapid-start application and has been reported to achieve production of syngas in -5 s.58 

Because CPO reactors are normally operated in the fuel-rich regime, the proper way to shut them down is to remove the oxidant and thus avoid feed compositions that are within the flammable range that could potentially lead to explosions. 

Another potential concern of proper shutdown is the potential formation of coke on the catalyst or in the reactor itself. Coke formation could occur if the 02/C ratio is maintained too low in the absence of steam for an extended period of time. In order to ensure a safe shutdown, the oxidant is removed from the system while fuel and steam continue to flow for a short period to ensure all oxidizants have been removed from the system. Subsequently, the reactor can be blanketed with an inert gas for cooldown. 

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