In any event, the best practice for a given refinery is to select header pressures
that result in the best economics, including the cost of compression.
Managing Hydrogen Users
Allocation of Hydrogen
Someone needs to “own” the hydrogen system in a refinery and that person has to be
able to make decisions about the system. Short-term, on-shift decisions are normally made by someone in the shift operations organization. Overall decisions dayto-day are usually a joint effort of the operations and planning staffs. Longer-term
planning and improvements are the purview of engineering staff.
Allocation of hydrogen is especially important when a facility is tight or short of
hydrogen. To maximize the refinery profitability, hydrogen needs to go to the units
that will make the most value per cubic foot (or cubic meter) of hydrogen used. All
impacts need to be considered however. For instance, allocation of hydrogen to a
high value unit that could force a cut in crude rate to the refinery because another
unit was starved for hydrogen would not be wise.
Factors Affecting Usage and Generation
Hydrogen is primarily used to:
• Eliminate sulfur, nitrogen, and other impurities from products or feedstocks.
• Upgrade product values (ULSD, dewaxing, isomerization).
• Crack heavier hydrocarbons (gas oils) to lighter hydrocarbon products (naphtha,
distillates).
• Supply reducing gas to sulfur plants (in some cases).
Changes in crude slate and rates impact all these factors. A heavy, sour crude
will require more hydrogen to refine than a light, sweet crude. Higher rates in a
hydrocracker or gas oil unit (possible due to crude changes) will require more
hydrogen. Deeper HDS or increasing conversion will increase consumption.
On the supply side, lower reformer severity, increasing catalyst age, or less
naphtha available to reform will all reduce cat reformer hydrogen makes. Changes
in SMR hydrogen plant feedstocks, catalyst age, capacity, or firing/recovery limits
may reduce the amount of hydrogen an SMR can make.
It is advisable to have a simple model that predicts hydrogen consumption or
production for each unit based on feed rate and quality to estimate changes. These
models would be incorporated into the material balance model for the system overall.
Overall Planning
Good, active hydrogen management practices will ensure that the least amount of
valuable hydrogen is wasted in a refinery. The operations organization can manage
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S.A. Treese
that result in the best economics, including the cost of compression.
Managing Hydrogen Users
Allocation of Hydrogen
Someone needs to “own” the hydrogen system in a refinery and that person has to be
able to make decisions about the system. Short-term, on-shift decisions are normally made by someone in the shift operations organization. Overall decisions dayto-day are usually a joint effort of the operations and planning staffs. Longer-term
planning and improvements are the purview of engineering staff.
Allocation of hydrogen is especially important when a facility is tight or short of
hydrogen. To maximize the refinery profitability, hydrogen needs to go to the units
that will make the most value per cubic foot (or cubic meter) of hydrogen used. All
impacts need to be considered however. For instance, allocation of hydrogen to a
high value unit that could force a cut in crude rate to the refinery because another
unit was starved for hydrogen would not be wise.
Factors Affecting Usage and Generation
Hydrogen is primarily used to:
• Eliminate sulfur, nitrogen, and other impurities from products or feedstocks.
• Upgrade product values (ULSD, dewaxing, isomerization).
• Crack heavier hydrocarbons (gas oils) to lighter hydrocarbon products (naphtha,
distillates).
• Supply reducing gas to sulfur plants (in some cases).
Changes in crude slate and rates impact all these factors. A heavy, sour crude
will require more hydrogen to refine than a light, sweet crude. Higher rates in a
hydrocracker or gas oil unit (possible due to crude changes) will require more
hydrogen. Deeper HDS or increasing conversion will increase consumption.
On the supply side, lower reformer severity, increasing catalyst age, or less
naphtha available to reform will all reduce cat reformer hydrogen makes. Changes
in SMR hydrogen plant feedstocks, catalyst age, capacity, or firing/recovery limits
may reduce the amount of hydrogen an SMR can make.
It is advisable to have a simple model that predicts hydrogen consumption or
production for each unit based on feed rate and quality to estimate changes. These
models would be incorporated into the material balance model for the system overall.
Overall Planning
Good, active hydrogen management practices will ensure that the least amount of
valuable hydrogen is wasted in a refinery. The operations organization can manage
638
S.A. Treese