Hey,
The platformer unit is design to process heavy to naphtha to convert low octane naphtha to high octane. The platformer is semi-regenerative (fixed bed UOP technology) and it's almost 20 to 30 years old unit.
Usually it run on design feed composition (means only on heavy naphtha). For 2 to 3 months same unit process mixture of medium naphtha and heavy naphtha. In feed major portion is heavy naphtha means we can say 70% heavy naphtha and 30% medium naphtha.
On heavy naphtha (only) the reactor delta T is 85F (first reactor). When mix feed was processed, the first reactor delta T was 98F. On heavy naphtha feed the yield of reformate is to 84 to 86% with that RON is 91 to 92.
When mixed feed was processed the yield was 79 to 81% means make of LPG and gases increased and RON was 88 to 90. As the reactions are endothermic so high delta T must process high octane product and it's yield
Note: All operating parameters were constant on both cases.
What is reason behind it ? Why it happens like that ? What parameter needs to be changed ?