Page 16 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

Process Planning, Scheduling and Flowsheet Design 3

] . Process material and heat balances. that the process engineer visualize the flow and pro-
2. Process cycle development, correlation of pilot or cessing of the fluids through the system and inside
research data, and correlation of physical data. the various items of equipment in order to ade-
3. Auxiliary services material and heat balances. quately recognize what will take place during the
4. Flowsheet development and detailed completion. process.
5. Chemical engineering performance design for spe- 6. Prepare/ supervise preparation of draft of process
cific items of equipment required for a flowsheet, flowsheets for review by others.
and mechanical interpretation of this to a practical 7. Prepare/supervise preparation of piping or
and reasonable specification. Here the process mechanical flow diagram (or P and ID), with neces-
requirements are converted into hardware details to sary preliminary sizing of all pipe lines, distillation
accomplish the process end results at each step in equipment, pumps, compressors, etc., and repre-
the product production process. sentation of all instrumentation for detailing by
6. Instrumentation as related to process performance, instrument engineers.
presentation and interpretation of requirements to 8. Prepare mechanical and process specifications for
instrument specialists. all equipment, tanks, pumps, compressors, separa-
7. Process interpretation for proper mechanical, struc- tors, drying systems, refrigeration systems. This
iural, civil, electrical, instrument, etc., handling of must include the selection of materials of construc-
the respective individual phases of the project. tion and safety systems and the coordination of
8. Preparation of specifications in proper form and/ or specifications with instrumentation and electrical
detail for use by the project team as well as for the requirements.
purchasing function. 9. Determine size and specifications for all safety
9. Evaluation of bids and recommendation of qualified relief valves and/ or rupture disks for process safety
vendor. relief (including run-a-way reactions) and relief in
case of external fire.
Most of the functions are fairly self explanatory; there- 10. Prepare valve code specifications for incorporation
fore, emphasis will be placed only on those requiring on item 6 above, or select from existing company
detailed explanation. standards for the fluids and their operating condi-
tions (see Figures 1-25 and 1-26).
Role of the Process Design Engineer 11. Select from company insulation standards (or pre-
pare, if necessary) the insulation codes to be applied
Although the working role of the process design engi- to each hot or cold pipe or equipment:. Note that
neer may include all of the technical requirements listed insulation must be applied in some cases only to pre-
above, it is very important to recognize what this entails in vent operating personnel from contacting the base
some detail. The process design engineer, in addition to equipment. See Table 1-1 for typical insulation thick-
being capable of participating in evaluation of research ness from which code numbers can be established.
and pilot plant data and the conversion of this data into a 12. Establish field construction hydraulic test pressures
proposed commercial process scheme, must, also: for each process equipment. Sometimes the equip-
ment is blanked or blocked off, and no test pres-
1. Prepare heat and material balance studies for a sure is applied in the field, because all pressure
proposed process, both "by hand" and by use of equipment must be tested in the fabricators' or
computer programs. manufacturers' shop per ASME Code.
2. Prepare rough cost economics, including prelimi- 13. Prepare drafts of line schedule and/ or summary
nary sizing and important details of equipment, fac- sheets (Figures 1-24 A-D), and equipment summary
tor to an order of magnitude capital cost estimate schedules (Figures 1-27, 1-28, 1-29, 1-30), plus sum-
[34] (see also ll9]), prepare a production cost esti- mary schedules for safety relief valves and rupture
mate, and work with economic evaluation repre- disks, compressors and other major equipment.
sentatives to establish a payout and the financial 14. Prepare detailed process and mechanical specifica-
economics of the proposed process. tions for developing proposals for purchase by the
3. Participate in layout planning for the proposed purchasing department.
plant (see [ 46] [ 47]).
4. Prepare final detailed heat and material balances. The process design engineer actually interprets the
5. Prepare detailed sizing of all process equipment process into appropriate hardware (equipment) to
and possibly some utility systems. It is important accomplish the process requirements. Therefore, the