A schematic representation of an entire process or major part of a process in which unit operations are symbolically represented as blocks in which process material collectively enters for processing and products leave (see Fig. 9). Unlike a process flow diagram, a block diagram has limited information. No information is provided such as flow compositions or details of process conditions within each unit operation. They are useful at the design stage to present how a complex process fits together. It is also known as a schematic flow diagram.

Fig. 9