Page 93 - Analysis, Synthesis and Design of Chemical Processes, Third Edition

For a plant of this magnitude, a continuous process would probably be chosen. However, we will return
to this issue after considering some process alternatives and see that a hybrid batch/continuous process
should also be considered.

Step 2: Define the Input/Output Structure of the Process

The basic input/output diagram of the process is shown in the process concept diagram of Figure E2.6(a).

Figure E2.6(a) Process Concept Diagram for the Mixed Ethers Process of Example 2.6

First, consider a material balance for the process and estimate the profit margin:

6
6
Required MeOH feed = (2)(1.087 × 10 ) = 2.174 × 10 kmol/y

6
3
Maximum ethylene production = 0.2718 × 10 kmol/y or 7.61 × 10 tonne/y

6
6
Value of DME = (50 × 10 )(0.95) = $47.5 × 10 /y
6
6
Value of DEE (maximum production) = (0.1309 × 10 )(74)(1.27) = $12.30 × 10 /y
6
6
Value of ethylene (maximum production) = (0.2718 × 10 )(28)(0.57) = $4.34 × 10 /y
Margin will vary between (47.5 + 12.3 – 19.54) = $40.26 million and (47.5 + 4.34 – 19.54) = $32.30
million per year.