Hydrotreaters also can be debottlecked.
Higher capacity catalyst, activated support balls, dense
loading of the reactor can all increase the reactor capacity.
Once a unit is built, it often is most profitable to maximize
the throughput up to the charge pump hydraulic limits.
Oftentimes, the charge pump spare can be turned on to increase
the oil charge flow. Larger control valves may reduce the
charge circuit pressure drop.
There is usually an incentive to run
hydrotreaters at the highest possible pressure up to the
equipment design pressures. There must be an acceptable safety
margin between the operating pressure and the relief valve set
pressure to handle the minor unit pressure swings so that the
relief valves do not lift. Furthermore, if conventional relief
valves are installed, the operating pressure must be
maintained below approximately 90% of the relief valve set
pressure so that the relief valves do not leak. Pilot operated
relief valves allow operation up to 95% of the relief valve