Note that if there is a sulfur slip problem in the feed gas pretreatment system, the
LTS catalyst will take a large hit and may need to be replaced immediately.
Activity of this catalyst cannot be recovered in service.
• Methanator activity
Similar to a LTS catalyst, methanator catalyst will deactivate in a plug-flow
manner. The methanation reaction occurs quickly, producing a sharp temperature rise in the catalyst bed. The position of this sharp rise can be trended
using the available temperature points at different elevations in the bed. The
bed should be replaced when the rise is about 70–80 % of the way through
the bed.
Fortunately, methanator catalyst is fairly robust, so it does not deactivate
quickly.
Catalyst Changeout
Fixed-Bed Reactors
Changeout of the fixed-bed catalysts and sorbents in a hydrogen plant is similar to
changeout of fixed beds in any other process units. There are a few specific points
highlighted below.
• Methanator and hydrotreating catalysts contain nickel and may generate nickel
carbonyl if any CO is present.
– In the methanator, CO may be left by inadequate purging during shutdown.
Refer to comments in the generic shutdown procedure.
– Hydrotreating catalyst that has coke on it can begin low-level combustion and
generate CO. The CO may react with nickel on the catalyst to release nickel
carbonyl.
– In both cases, the reactors should be routinely monitored for CO whenever
work is occurring in or around the reactors.
• PSA adsorbents are normally dense loaded using a method specified by the
technology provider. The pressure drop through each vessel must be as close as
possible to the same value, so care must be taken during the dense loading process.
• PSA adsorbents generate a large amount of heat if they are exposed to water,
even atmospheric moisture. Do not let these materials get wet and do not unload
or load adsorbents in rain.
• Shift catalysts, both HTS and LTS, will probably be self-heating if they contact
air. Monitor the unloading atmosphere to keep them blanketed with inert gas.
• Zinc oxide, carbon adsorbents, and certain other solids used in a hydrogen plant
reactor do not hold up well during handling. They will generate a lot of dust.
Respiratory protection and dust management practices should be employed by
anyone near these materials.
• Because of the high nickel content of methanator catalyst, respiratory protection
must be used by anyone handling either fresh or used methanator catalyst.
Hydrogen Production and Management for Petroleum Processing
611
LTS catalyst will take a large hit and may need to be replaced immediately.
Activity of this catalyst cannot be recovered in service.
• Methanator activity
Similar to a LTS catalyst, methanator catalyst will deactivate in a plug-flow
manner. The methanation reaction occurs quickly, producing a sharp temperature rise in the catalyst bed. The position of this sharp rise can be trended
using the available temperature points at different elevations in the bed. The
bed should be replaced when the rise is about 70–80 % of the way through
the bed.
Fortunately, methanator catalyst is fairly robust, so it does not deactivate
quickly.
Catalyst Changeout
Fixed-Bed Reactors
Changeout of the fixed-bed catalysts and sorbents in a hydrogen plant is similar to
changeout of fixed beds in any other process units. There are a few specific points
highlighted below.
• Methanator and hydrotreating catalysts contain nickel and may generate nickel
carbonyl if any CO is present.
– In the methanator, CO may be left by inadequate purging during shutdown.
Refer to comments in the generic shutdown procedure.
– Hydrotreating catalyst that has coke on it can begin low-level combustion and
generate CO. The CO may react with nickel on the catalyst to release nickel
carbonyl.
– In both cases, the reactors should be routinely monitored for CO whenever
work is occurring in or around the reactors.
• PSA adsorbents are normally dense loaded using a method specified by the
technology provider. The pressure drop through each vessel must be as close as
possible to the same value, so care must be taken during the dense loading process.
• PSA adsorbents generate a large amount of heat if they are exposed to water,
even atmospheric moisture. Do not let these materials get wet and do not unload
or load adsorbents in rain.
• Shift catalysts, both HTS and LTS, will probably be self-heating if they contact
air. Monitor the unloading atmosphere to keep them blanketed with inert gas.
• Zinc oxide, carbon adsorbents, and certain other solids used in a hydrogen plant
reactor do not hold up well during handling. They will generate a lot of dust.
Respiratory protection and dust management practices should be employed by
anyone near these materials.
• Because of the high nickel content of methanator catalyst, respiratory protection
must be used by anyone handling either fresh or used methanator catalyst.
Hydrogen Production and Management for Petroleum Processing
611