Page 19 - Design of Simple and Robust Process Plants

2 Chapter 1 Introduction
± Capabilities for mixed integer design problems are within reach for commer-
cial software. The modeling of flow dynamics is another area where progress
has been made in the understanding and improvement of process design. In
particular the introduction of reaction kinetics and multiphase behavior can
be included in the computations.
± All these modeling capabilities are supported by a strongly increased compu-
tational power. With these modeling technologies it is easier to understand
the process technology and so achieve improved designs and operation.
. The reliability of industrial components. This has also been improved consid-
erably, with the mean time between failures (MTBF) of components having
been increased over the years. This is reflected in the ongoing efforts of ven-
dors to make their products more reliable. Plants often have in-house reliabil-
ity engineers to perform root cause analysis of failures; based on these ana-
lyses, modifications are implemented to achieve higher plant reliability. The
time between turnovers of process plants has increased to more than 4 years.
In cases where systems are subject to process fouling or aging, the reduction
of these problems receives similar attention in order to achieve longer opera-
tional uptimes.
. Higher automation levels and robust control. The introduction of process
computers has resulted in automatic start, stop and regeneration procedures,
with less variability and fewer operational errors. Improved instrument
design, with the development of on-line analyzers and adequate control
design, brings hands-off operation within reach. These improvements in com-
munication technology has made remote monitoring and operation a reality.

These technical capabilities, the economical circumstances, and the environmental
requirements have resulted in the development of more efficient processes with
regard to raw material and energy utilization, together with greater compliance with
more stringent environmental and safety requirements.

Table 1.1. Technical comparison between domestic and industrial refrigerators.

Technical point Domestic Industrial
Safety devices ± 17
Instruments to control system 1 58
Instruments, local ± 20
Control loops 1 9
Valves ± 120
Equipment* 210
Filters ± 5
Reliability Very high To be proven
MTBF (years) >10 1
Spare unit None One
* As experienced by the operator.
MTBF = mean time between failures.