A process flow diagram (PFD) is one of the core documents created by process engineers during the design and development of an industrial process. PFDs provide a simplified graphical representation of the important pieces of a process plant such as the major equipment, process streams and the important operating conditions of a process plant. The PFD serves as an overview to help process engineers understand how the overall process works before detailed engineering and the preparation of process and instrumentation diagrams (P&IDs) commence.
The information about what is process flow diagram is is important for anyone starting a career in chemical, petrochemical, pharmaceutical, oil and gas, and other process industries.
What is Process Flow Diagram?
A process flow diagram is an engineering drawing that captures the flow of materials and process streams in various equipments of a process. It illustrates some of the major equipment in a process such as reactors, heat exchangers, columns, vessels and separators.
It is also important to include the following in process flow diagrams based on the requirements of the project: stream flow rates, temperatures, pressures, compositions and equipment identifications.
The main function of a process flow diagram is to capture the process for the overall engineering team.
What Does a PFD Diagram Show?
A PFD diagram shows the major flow lines of the process and equipment. It doesn’t show minor connections and details such as piping sizes, valves, instrumentation details etc., as it would on a P&ID.
PFDs are often used to describe a process that is still under development, allowing information to be exchanged between various sections within the process development team. A PFD typically contains the following information.
- Major process equipment
- Process flow direction
- Major process streams
- Stream Numbers
- Operating temperature and pressure
- Flow Rates and Composition
- Heat and Material Balance Information
- Equipment Tags
- Utility connections, if applicable
By including the information listed above, engineers can quickly determine how raw materials are processed in the plant, and how finished products are removed from the plant.
Why Is A Process Flow Diagram Important?
The PFD is a common reference throughout the course of the project, and serves a number of functions for the process engineer. These functions include equipment and utility sizing, process simulation, and a number of other preliminary design functions. The PFD is also useful when process changes are being reviewed.
Changes that increase the capacity of a process or the introduction of additional process equipment are reviewed and evaluated at the PFD level, before detailed design and engineering work is carried out.
PFDs help process engineers, and other design discipline engineers, understand the process requirements that relate to their discipline.
PFDs and P&IDs
PFDs and P&IDs are related, but different, diagrams. A PFD provides a process overview and shows major equipment and process streams, whereas a P&ID provides process detail and shows piping, instruments, valves, control loops, and other process components.
PFDs show process flow, and P&IDs show process control and connection detail. In short, the PFD explains how a process works, and the P&ID detail shows how a process is controlled and connected.
Learn Process Design and PFD Preparation
Understanding how to create a Process Flow Diagram (PFD) is a skill that process engineers use repeatedly, and hopefully, continuously improves with experience. If you are an aspiring process engineer and want to enhance your practical skills you may want to take a process design online course which includes process simulation, equipment design, heat and material balances, and the development of Process Flow Diagrams (PFDs) and Piping and Instrumentation Diagrams (P&IDs), as well as process safety.
The Energy Learning Institute in Gujarat offers Process Engineering training programs for chemical engineers in Gujarat. The learning of how to read and create Engineering documents, PFDs in particular, can aid students for further process design and related engineering roles.
Conclusion
Process Flow Diagrams show equipment and piping in a process. It shows process fl ow and how equipment is interconnected. It is an engineering document to explain the process structure and how it works. For process engineers, reading and creating process Flow Diagrams, in addition to analysis of the process, helps in equipment design and detailed engineering activities for projects and processing facilities.
