Page 152 - Analysis, Synthesis and Design of Chemical Processes, Third Edition

Methane Product: The methane produced in the process leaves in the fuel gas, Stream 16. Tactic 2 is
applied to each system containing the fuel gas product, in backward progression.
System -m-: Consists of m-105, m-104, E-105, T-101, V-104, P-102, s-103, E-104, E-106, E-103,
V-102, V-103, and s-102. This is the smallest system that can be found that contains the
fuel gas product stream and has a single input.
System -n-: Includes the system identified above plus exchanger E-102 and compressor C-101. The
inlet to E-102 contains all the methane in the fuel stream. This is Stream 9, which leaves

the reactor.

In the first step of tracing methane, including only m-105 was attempted. This unit had two input streams,
and it was not possible to determine which of these streams carried the methane that made up the product

stream. Thus, Tactic 2 could not be used. In order to move ahead, additional units were added to m-105 to
create a system that had a single input stream. The resulting system, System -m-, has a single input, with
the unidentified stream coming from exchanger E-102. An identical problem would arise if the procedure
used in Example 5.1 were implemented. Figure 5.3 shows the primary paths for the hydrogen and
methane.

Figure 5.3 Primary Chemical Pathways for Methane and Hydrogen in the Toluene Hydrodealkylation
PFD