the distribution of products from hydroprocessing canola oil and
camelina oil.
The models built in this study used fired heaters to increase the
reactants’ temperature to 400 C and used compressors and pumps
to increase the reactants’ pressure to 15.2 MPag. An RYield reactor
block simulated the hydroprocessing reactions and several Separator
and PetroFrac unit operation blocks were used downstream of
the reactor to separate the product components. Heat exchangers
were used throughout the model to transfer energy from hot product
streams to cooler feed streams. Detailed process flowsheets, as
well as heat and material balances are given in the Supplementary
information section. The BK-10 property set was used for the models
in this study.
Although Aspen Plus is very versatile, there are several limitations
of the models built in this study. First, the RYield reactor
block is an extremely simple block – it takes a feed stream as input,
and outputs a product stream based on a given product distribution
(w/w %). Although its simplicity makes the block reliable, it
is a disadvantage in terms of economic analysis because the block
cannot be sized and mapped to an actual piece of equipment.
Therefore, a scaled estimate from literature [8] was used to arrive
at the installed cost of the hydroprocessing unit. Second, triglycerides
are not built into the library of components available in Aspen
Plus. However, during hydroprocessing, the triglycerides break
down into fatty acids, CO2, and propane. These components were
used in the feed stream instead of triglycerides, because with the
RYield reactor block, only the mass flow rate of the feed is used
to calculate the mass flow rate of each product. Third, some of
the heavy product components such as C34 and C38 are not available
in the Aspen Plus component library. C32 is the heaviest n-alkane
available in Aspen Plus so it was used to represent any
components heavier than C32. Since C32 is so much heavier than
the other product components, the minor difference in phase
behavior between the C32 and the heavier components is unlikely
to affect the accuracy of the simulation results.