HCK prewetting precautions

After finishing the catalyst loading for the Hydrocracker process unit reactors, Operations with Oil once through flush for 1st and 2nd stage reactors to remove the Catalyst fines is mandatory and must be:

1-?????Circulate Recycle gas (System pressure should be at least 75% of design)

2-?????Introduce feed to the guard reactor and 1st stage reactor and quickly increase the feed rate to at least 80% of design within 1 minute…… Why very fast and in one minute???

When the oil flows over the “dry” catalyst for the first time, a large heat release occurs as the oil adsorbs on the catalyst surface and the temperature may be increased from 6-12°C suddenly

When the temperature wave reaches the bottom of the 1st stage reactor, the feed rate may be reduced to ~50-60% if needed, to avoid filling the 1st stage HHPS and HLPS too quickly.

The prewetting and once through flush should be for 1 Hours and the temperature must be less than 120 C and H2 partial pressure should be less than 60% to prevent catalyst reduction.

Now you can start your sulfiding steps safely. Hope you safe sulfiding