Hydrocracking & Hydrotreating
Hydrocracking is facilitated by a bifunctional catalyst that is capable of rearranging and breaking C-C bonds as well as adding hydrogen to aromatics and olefins to produce naphthenes and alkanes. The major products from hydrocracking are jet fuel and diesel.
Hydrotreating (mostly known as Hydrodesulfurization or HDS) is a process used to remove mainly sulfur(S) and nitrogen(N) from refined petroleum products by adding hydrogen to breaking C-S and C-N bonds.
The catalyst mostly contains Cobalt/Molybdenum (CoMo) or Nickel/Molybdenum (NiMo) on an alumina support base, aftercarbon burning(regeneration), that needs to be activated by sulfiding. The catalyst in the state of metal oxide is not the active form and must be activated by converting them to metal sulfides.
Critical Control of Process Gas
Catalyst regeneration requests a continuous monitoring of oxygen(O2) concentration of the regenerator off-gas. If O2 is insufficient, the deposited coke may not completely combusted, while an excess O2 will cause over-temperature and reduce the life and activity of the catalyst.
Hydrogen sulfide(H2S) and dewpoint(H2O) in circulating hydrogen are detected to control catalyst sulfiding (mostly EX-SITU sulfiding).
Hydrogen sulfide(H2S) is required to monitor outlet of HDS acid gas scrubber to control desulfurization process.
Challenge of Instrumentation
Traditionally paramagnetic (O2), lead acetate/UV (H2S) and electrochemical/vibrating quartz crystal/chilled mirror (H2O) are used for monitoring process gases of hydrocracking. All the extractive or chemical analyzers are limited by their low adaptability to corrosive gases, and not capable of eliminating cross-interference from other gas species and impurities.
The non-contact laser and sensor of the in-situ LGA combined with continuous purge results in virtually maintenance free. High-speed response (down to 1s) highlights its reliability for continuous catalyst regeneration control.
As for extractive LGA, the extreme monochromaticity of laser spectrum (0.0001nm), in other words intrinsically cross-interference free, already makes it outstanding among all the extractive analyzers. Besides, all-route corrosion proof leads to a well performance in the presence of corrosive gas like H2S.
Regenerator flue gas
Outlet of desulfurization
NOTES: Listed are typical data FPI experienced and backed by field references. Alternate gases and ranges may be available or customizable on request.