Question
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In Diesel and VGO hydrotreaters, after feed pump failure, feed introduction is advised to be done within 15minutes, in case feed introduction is not done in 15minutes, it is advised to take normal shutdown by cooling of the reactor. What's wrong in feed introduction after 15minutes at high temperature?
Jun-2023
Answers
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Nasir Hussain, PARCO OIl refinery Pakistan, nasir.mughal3010@gmail.com
When feed charge pump fails, its not safe to introduce feed immediately, due to chances of temperature exotherm or temperature run away. But feed is normally introduced after reducing reactor temperature ~ 30 °C below the normal operating temperature. It takes more than 15 minutes to reduce the temperature.
Sep-2023
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Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br
This recommendation normally is related to concern of catalyst deactivation due to the combination of high temperature and absence of H2S environment due to the lack of feed by long period (above 15 minutes).
It's possible to keep the processing unit under circulation and monitoring the H2S concentration in the recycle gas in order to guarantee the minimum concentration to avoid the desulfiding process of the catalytic bed, but this is necessary to be analyzed case by case once this procediment relies on the severity of the processing unit as well as the feed composition (straight run diesel + VGO, for example).
Jun-2023
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