A process flow diagram (PFD) is a diagram commonly used in
chemical and
process engineering to indicate the general flow of plant processes and equipment. The PFD displays the relationship between major equipment of a plant facility and does not show minor details such as piping details and designations. Another commonly used term for a PFD is processflowsheet. It is the key document in process design.[1]
Typical content of a process flow diagram
Typically, process flow diagrams of a single
unit process include the following:
Process flow diagrams of multiple process units within a large industrial plant will usually contain less detail and may be called block flow diagrams or schematic flow diagrams.
Process flow diagram examples
The process flow diagram below depicts a single chemical engineering unit process known as an
amine treating plant:
Multiple process units within an industrial plant
The process flow diagram below is an example of a schematic or block flow diagram and depicts the various unit processes within a typical
oil refinery:
Other items of interest
A PFD can be computer generated from process simulators (see
List of Chemical Process Simulators), CAD packages, or flow chart software using a library of chemical engineering symbols. Rules and symbols are available from standardization organizations such as
DIN,
ISO or
ANSI. Often PFDs are produced on large sheets of paper.
PFDs of many commercial processes can be found in the literature, specifically in encyclopedias of chemical technology, although some might be outdated. To find recent ones, patent databases such as those available from the
United States Patent and Trademark Office can be useful.
Standards
ISO 15519-1:2010(en): Specification for diagrams for process industry — Part 1: General rules
ISO 15519-2:2015(en): Specifications for diagrams for process industry — Part 2: Measurement and control
ISO 10628-1:2014(en): Diagrams for the chemical and petrochemical industry — Part 1: Specification of diagrams
ISO 10628-2:2012(en): Diagrams for the chemical and petrochemical industry — Part 2: Graphical symbols
ANSI Y32.11: Graphical Symbols For Process Flow Diagrams (withdrawn 2003)
SAA AS 1109: Graphical Symbols For Process Flow Diagrams For The Food Industry
^Sinnott, R. K. (2005). Coulson & Richardson's chemical engineering (4th ed.). Amsterdam Paris: Elsevier Butterworth-Heinemann. p. 133.
ISBN978-0-7506-6538-4.
Further reading
Raymond E. Kirk & Donald F. Othmer (2001). Kirk-Othmer Encyclopedia of Chemical Technology (4th ed.). Wiley-Interscience.
ISBN0471419613.
M.S. Ray & M.G. Sneesby (1998). Chemical Engineering Design Project: A Case Study Approach (2nd ed.). Gordan and Breach Science Publishers.
ISBN9056991361.
R. Turton; R.C. Bailie; W.B. Whiting; J.S. Shaeiwitz (2002). Analysis, Synthesis, and Design of Chemical Processes (2nd ed.). Prentice Hall.
ISBN0-13-064792-6.
Fritz Ullmann (2002). Ullman's Encyclopedia of Industrial Chemistry (6th ed.). Wiley-VCH.
ISBN3-527-30385-5.
Srikumar Koyikkal (2013). Chemical Process Technology and Simulation (1st ed.). Prentice Hall India.
ISBN978-81-203-4709-0.