Introduction and Overview ◾  3
The main problem in distillation process control is to separate and purify chemical components in liquid and vapor
streams while shedding the disturbances that are imposed
on the distillation column. The opportunity is to separate the
components from a feed stream into new vapor and liquid
streams that have increased economic value at a cost that is
competitive with other producers. Conducting research in a
large corporation provides the opportunity to apply the results
of improved performance to many distillation towers in many
different businesses.
Distillation is a mature technology that is well developed
and tested by the scientific method. Two comprehensive
books have been written by Kister 1,2 on the design and
operation of distillation columns. The control of distillation columns has been widely studied for many years,
many papers have been written, and several books have
been published on the subject such as the one by Buckley,
Luyben, and Shunta. 3 There is a large body of information to
search and understand in the state of the art of distillation
and process control.
During the last 20 years, there has been a continuing
emphasis on improved product quality, performance, and
reduced operating costs such as energy consumption, lost
product, rework, maintenance, and labor cost per unit of product produced. Computer hardware and computer programs
have been improved dramatically for simulating and modeling the distillation process and the dynamic response for the
hypothesis in Step 3 in the scientific method. The chemical
engineering fundamentals and mathematical hypotheses used
to describe the design and performance of distillation columns
are continually tested for their validity by plant operations in
industry. Ultimately, the results are judged by the business that
is responsible for the quality and profitability of the products
produced by distillation and by the manufacturing department
responsible for operating the process equipment.