Conversion of methanol to formaldehyde is an endothermic reaction. In an existing process, methanol vapor at 100 degrees C is further preheated to 250 by 60 bar steam, then fed to the reactor. Sufficient steam heating is added through coils in the catalyst bed to maintain an outlet temperature of 150 degrees C. The steam coils have been a constant maintenance headache. The coils often leak and the plant needs to be shut down for repairs about six times a year. The plant manager would like to eliminate the need for steam supply to the reactor, to avoid the unplanned shutdowns.
You propose that, instead of supplying steam to the reactor, some of the hydrogen that is produced in the reactor be burned.
H2+ (1/2)O2 ------> H2O
To do this, air (79%N2, 21%O2) at 100 degrees C will be mixed with the methanol vapor at 100 degrees C. The reactor feed and outlet temperatures remain the same. Assume that all the added oxygen is consumed.
A) Calculate the amount of hydrogen (gmol/min) that needs to be burned in order to completely eliminate the need for addition of heat to the reactor.
B) Identify one safety concern associated with the proposed change in operation, and suggest a method to reduce this hazard. What is the environmental impact of the proposed change? Will there be a net change in CO2 emissions?