The amount of steam consumed by the reactor at different reaction temperatures
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One reactor undergoes a cracking reaction, heated by steam (with a trap at the outlet of the reactor shell side). The reaction temperature ranges from 170 to 210 degrees; as the catalyst’s activity gradually decreases, the reaction temperature rises over time. In the first few months, the reaction temperature was 170 degrees, and it increased month by month until it reached 210 degrees. The steam used is saturated steam at 2 MPa and 215 degrees. Is the amount of steam at the start (reaction temperature of 170 degrees) roughly the same as that at the end (reaction temperature of 210 degrees)? (Under the same conditions of other flow rates, pressures, etc.). In terms of the cracking reaction, the required cracking energy is essentially the same; can it be assumed that the amount of steam remains roughly constant? The issue is the temperature difference between the two; it was 45 degrees at first and then 5 degrees, so there is a significant difference in the heat transfer rate (with the heat exchange area and K value remaining constant in the same reactor), and therefore the amount of heat transferred also differs greatly. Please have an expert analyze which of the two situations I mentioned is correct
It can be analyzed step by step: 1) The temperatures before and after, the energy released during the pyrolysis reaction is the same； 2) As the catalyst is used for a longer period of time, a higher activation energy for the catalyst reaction is required ； 3) The same amount of material requires heat to raise its temperature ； It can be seen that the energy required for the process itself is increasing; therefore, the 210-degree reaction will definitely consume more steam. Additionally, the energy carried away by the condensate is also increasing. Therefore, it is inevitable to increase the amount of steam used.
You already said that the catalyst’s activity has decreased; to overcome the same reaction energy barrier, more heat is naturally required