An Overview of Chemical Reaction Analysis - Bioprocess Engineering: Kinetics, Biosystems, Sustainability and Reactor Design - page 130

(2) Material cost (RM$). All raw materials used in the process will incur a cost. The cost to
raw materials can usually be considered as proportional to its weight or amount and
quality or concentration.
(3) Separation cost (SC$). The products need to be recovered from the product stream and
the catalyst needs to recovered, etc.
(4) Product value (P$). The average price that the product can fetch in an open market is
usually the starting point of consideration. The product value is normally assigned based
on the amount.
(5) Cost to dispose unwanted products (WT$). With the increasing environmental concerns,
unwanted material disposal or turning into useful products will incur a cost to the overall
plan. We normally associate the waste disposal cost to amount of waste material that
needs further process.
(6) Cost to marketing the products (CM$). The products have no value if not claimed by their
intended users. There is a cost to make the products known to their intended users and
helping the intended users to claim the products.
(7) Transportation cost of the product before delivery (DC$). The price of a product is
sometimes for a delivery at certain point. Transportation cost is proportional to the amount
of goods to be delivered as well as the distance between the plant and the delivering point.
(8) Taxes (TX$). For any operations or plants, the governments will collect taxes over site
coordination, utilities, land use, water and air disturbances, etc.
(9) Indirect cost (IC$).

Mathematically, one can write the profit as

Profit ¼ P$ RO$ RM$ SC$ WT$ CM$ DC$ TX$ IC$ (3.144)

Therefore as a bioprocess engineer, we want to make sure that the process we are dealing
with makes a profit. The overall goal of the Bioprocess Systems Engineering is to maximize
this profit.
As one can notice from Eqn (3.144) that the estimation of profit involves many details that
may or may not be always available. As a bioprocess engineer, we frequently base our analysis
on readily available data. We next define the gross profit (GP$) and gross operation cost (GC$):

GP$ ¼ P$ RO$ SC$ RM$ WT$ (3.145)

GC$ ¼ RO$ þ SC$ þ RM$ þ WT$ (3.146)

These two parameters are frequently used to guide the design and operational performance
analyses of bioprocesses. Depends on the amount of knowledge we know associate with the
process, we normally start with maximizing the profit if possible. When not all the informa-
tion is available, we examine the process by maximizing the gross profit (GP$) or minimizing
the gross operation cost (GC$) or minimizing the reactor operating cost (RO$).
Example 3-8: Economic Analysis
We wish to produce R isothermally from the reaction

A / R ; r

1 ¼

k C A (E3-8.1)

1