The first section of this book consists of a single chapter. Chapter 1 covers the important diagrams which are routinely used by chemical engineers to help design and understand chemical processes. We start the book with this section and chapter because nearly all the technical information that we present in the remainder of the book is, in some way, related to the three principal diagrams which are presented in Chapter 1. These three diagrams are the block flow diagram, (BFD), process flow diagram, (PFD), and the piping and instrument diagram, (P&ID).

      Design is an evolutionary process which can be represented by the sequence of process diagrams describing it. A chemical engineer might begin the design process by sketching out a very crude block flow diagram in which only the feed and product streams are identified. This diagram is sometimes known as an input-output diagram. From this simple starting point, the engineer might then break down the process into its basic functional elements such as the reaction and separation sections. The engineer would also identify recycle streams and consider additional unit operations in order to obtain the desired temperature and pressure conditions required by the reactor and separator sections. By identifying these basic elements, a generic process block flow diagram can be drawn. After material balance calculations have been performed, a preliminary block flow diagram (BFD) can be drawn, and estimates of process flows can be made. As more complete material and energy balances are performed and preliminary equipment specifications are calculated, the diagram becomes more sophisticated, and a process flow diagram (PFD) comes into being. Finally, as the mechanical and instrumentation details of the process are considered, this information is recorded in the piping and instrumentation diagram (P&ID). The existence of the latter three levels of diagrams (BFD, PFD, and P&ID) is universal among the chemical process industry, and it is extremely important that the chemical engineering student be familiar with them and be able to use them without fear.

      The input-output diagram, the generic process flow diagram which deals with the structure (in terms of the topology of the process) and the conditions chosen for a given piece of equipment or unit operation, are not covered in Chapter 1. This information is addressed in Section 2. Only the information contained in the three principal flow diagrams and the general conventions used in constructing these diagrams are considered in this section. However, to obtain a full understanding of the evolutionary process of design that results in these diagrams, it is recommended that Section 2 also be consulted.

      The technical diagrams commonly used by chemical engineers are presented. These diagrams include the block flow diagram, BFD, the process flow diagram, PFD, and the process and instrumentation diagram, P&ID. A standard method for presenting a PFD is given and illustrated using a process to produce benzene via the catalytic hydrodealkylation of toluene.