In my unit, which produced formaldehyde from partial oxidation of methanol, we use a reactor (nonadiabtic) for the internal cooling done by thermal oil. The problem is: at startup when we heat the thermal oil, as the temperature of the thermal oil increases, there is a decrease in the temperature. Why is this occurring?
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Jim Grant Forum Moderator 118 Posts
Re: Reactor content temperature versus oil system temperature17 October 2006 at 1:29pmI am not sure whether I understand the question that is being posed. If I understand correctly, you are stating that at startup the reactor contents cool as you increase the heating oil temperature. During startups the dynamics of a system can be quite different than during steady state operation. Depending on the initial temperatures of the hot oil system (vessels, piping plus oil inventory), reactor system (vessels, piping and inventory) and raw material conditions, there could be transients in which the reactor contents are heating the vessel faster than the oil system can heat the reactor contents. This would result in a decrease in reactor contents as you heat the oil system. The system must be analyzed on a transient basis during startup and shutdown in order to understand the time-temperature history of oil, process and equipment.