Page 21 - Plant design and economics for chemical engineers

4 PLANT DESIGN AND ECONOMICS FOR CHEMICAL ENGINEERS
consists of procurement of the equipment, construction of the plant, startup of
the plant, overall improvements in the operation, and development of standard
operating procedures to give the best possible results.
The development of a design project proceeds in a logical, organized
sequence requiring more and more time, effort, and expenditure as one phase
leads into the next. It is extremely important, therefore, to stop and analyze the
situation carefully before proceeding with each subsequent phase. Many pro-
jects are discarded as soon as the preliminary investigation or research on the
original idea is completed. The engineer working on the project must maintain a
realistic and practical attitude in advancing through the various stages of a
design project and not be swayed by personal interests and desires when
deciding if further work on a particular project is justifiable. Remember, if the
engineer’s work is continued on through the various phases of a design project,
it will eventually end up in a proposal that money be invested in the process. If
no tangible return can be realized from the investment, the proposal will be
turned down. Therefore, the engineer should have the ability to eliminate
unprofitable ventures before the design project approaches a final-proposal
stage.

GENERAL OVERALL DESIGN
CONSIDERATIONS
The development of the overall design project involves many different design
considerations. Failure to include these considerations in the overall design
project may, in many instances, alter the entire economic situation so drastically
as to make the venture unprofitable. Some of the factors involved in the
development of a complete plant design include plant location, plant layout,
materials of construction, structural design, utilities, buildings, storage, materi-
als handling, safety, waste disposal, federal, state, and local laws or codes, and
patents. Because of their importance, these general overall design considera-
tions are considered in detail in Chap. 3.
Various types of computer programs and techniques are used to carry out
the design of individual pieces of equipment or to develop the strategy for a full
plant design. This application of computer usage in design is designated as
computer-aided design and is the subject of Chap. 4.
Record keeping and accounting procedures are also important factors in
general design considerations, and it is necessary that the design engineer be
familiar with the general terminology and approach used by accountants for cost
and asset accounting. This subject is covered in Chap. 5.

COST ESTIMATION
As soon as the final process-design stage is completed, it, becomes possible to
make accurate cost estimations because detailed equipmept specifications and
definite plant-facility information are available. Direct price quotations based-