Page 21 - Design of Simple and Robust Process Plants

4 Chapter 1 Introduction

PV
ECONO-
INTERMEDIATE MIZER CONDENSER C.W.
FLASH DRUM

LV
LV
LV OIL
FROM PV
SEPARATOR
COOLERS
SUCTION SCREW
DRUM COMPRESSOR
DRIVER
LV C.W.
TO
OIL
COOLER
COOLERS
OIL
PUMP
Fig. 1.2. Industrial refrigerator; technical layout.

operated remotely from a central control station. When something goes wrong, the unit
may shut down automatically, while maintenance person next to the operator has
remote access to the system in order to diagnose the cause of the failure.
The operation of air separation plants is also practiced by remote control, and
currently this system is used by the major suppliers of oxygen and nitrogen. Other
examples of remote-operated systems include: compressor stations; water treatment
systems; unmanned oil platforms; and refrigeration systems ± all of these are at dif-
ferent locations and operated by experienced companies in their field. The above-
mentioned applications are not only remotely controlled ± they also have to meet
higher levels of reliability and safety performance in order to permit unmanned
operation.
The design of these process units had to be adapted to meet high standards on
safety, reliability, and operation. I was once told by an air separation engineer that in
order to achieve the remote operation it was necessary to strip the instrumentation
to avoid plant stops caused by instrument nuisance. The concept was:

It is better to have a few good instruments than lots of unreliable ones.

The design of chemical plants needs to make an evolutionary step if it is to approach
the performance of a domestic refrigerator.