 |  Plant Design and Economics for Chemical Engineers, 5/e Max S. Peters,
University of Colorado
Klaus Timmerhaus,
University of Colorado, Boulder
Ronald E. West,
University of Colorado, Boulder
Reactor Equipment - Design and Costs
Chapter OverviewC
hemical reaction engineering is one of two fields unique to chemical engineering,
the other being separation processes. The large variety of chemical reactions
and reactors and the general methods of analysis available in reactor
design provide many opportunities for creativity. The complex nature of chemical reaction
engineering often requires extensive and repetitive calculations that can only be
carried out by sophisticated computer models now available to the design engineer for
the analysis of most reactions and the selection and arrangement of reactor types.
To produce a desired product, a reaction path is required that indicates the reaction
or reactions necessary to convert the starting materials to the desired product. The
reaction path selected as part of the design process may need to be established by a
research and development program, or be prespecified, or be limited by the availability
of specific starting materials. The reaction path combined with the reactor performance,
in turn, determines many other process conditions, such as the nature, quantity, and
purity of feed streams, operating temperatures and pressures, catalysts, safety issues,
and product separation and purification requirements. Once a reaction path has been
defined, a complete process flowsheet is developed, as discussed in Chap. 4.
The process involving the design and selection of chemical reactors and reactor systems
commences in the following manner. First, the reactor type or types to be evaluated
must be established. Then the reaction mixture or the catalyst volume is determined by
solving the appropriate design equation(s), utilizing kinetic and thermodynamic data.
The volume establishment step of the design process can present problems because
the required kinetic data may not be available and may require experimental determination.
From the reaction mixture or catalyst volume, plus ullage or void volume, the
dimensions of the reactor are established. This is followed by a determination of the
heating and cooling requirements established from reactor/reaction mass and energy
balances. The materials of construction for the required equipment are then established, as discussed in Chap. 10, from the character of the species in the reaction mixture and the
temperature and pressure. All this information is then used to estimate the equipment and
utility costs for the reactor system. Once the various possible designs and their associated
costs are identified, a determination of the optimal design can be made. Amore graphical
description of chemical reaction design is illustrated in flowchart form in Fig. 13-1.
The central role of the reactor in so many chemical processes indicates that the reaction
path, reactor selection, and design may play a key role in the complete process
design, as well as in the overall economics of the process. It is therefore possible that
the reaction path and reactor type selection may be the key variables in the structural
optimization of a process. |
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2003 McGraw-Hill Higher Education