Process flow chart introduction

A process flow diagram (PFD) is a graphical representation of a chemical engineering process that shows the main process flow path. Instead of showing minor details of the process, it focuses on the equipment used, control valves, and other existing instruments. It helps to illustrate how the major components of a process plant interact with each other to achieve the desired effect. It is also effectively used in other sectors such as business management to understand how different parts of a company work effectively to achieve its specific goals. Frank Gilbreth Sr. was the first person to develop a flow chart in 1921 when he introduced it to the American Society of Mechanical Engineers (ASME).

The most important benefit of drawing a flow chart is that it gives the workers an overall understanding of the entire process. This in turn helps them make the necessary improvements and changes where needed to make it work at its maximum potential. Once all the changes are made, the flow chart serves as a standard for all the people involved to follow. This avoids confusion and also helps prevent errors. These flow charts may not always show the working of the entire plant. It can be used to represent different parts of the plant. This will help to understand in more detail each specific operation being performed such as raw material storage, reactions, separations, purifications, recovery, and product storage. A typical PFD will contain operational data such as temperature, pressure, and mass flow. Pressure relief valves and safety valves are not usually included in the PFD, while control valves are key components. Also keep in mind that these diagrams are not synchronized in size with the actual plant.

PFD symbols are a set of diagrams that show how different parts of a process relate to each other. These symbols also describe the instrumentation used in the process. Examples of symbols include valves, pumps, compressors, reboilers, and heat exchangers. Process lines represent the path of material flow and are represented by various piping symbols. There are also signal lines that are thinner than process lines, which represent the type of signal provided, such as electronic signals or pneumatic signals. Commonly used symbols are specified by organizations such as ISO and ANSI.

The role of PID

1. Use the specified category graphic symbols and text codes:

Represent all equipment, machinery and drivers of the plant process, including spare equipment that needs to be in place and mobile equipment for production, and number and label them. 2. Use the specified graphic symbols and text codes: Detail all required pipelines, valves, main pipe fittings (including temporary pipelines, valves and pipe fittings), utility stations and insulation, etc., and number and label them.

3. Use the specified graphic symbols and text codes to indicate all detection, indication, and control function instruments, including disposable instruments and sensors, and number and mark them.

4. Use the specified graphic symbols and text codes to indicate all process analysis sampling points, and number and mark them.

Matters that need to be explained:

Including the design requirements and key design dimensions of the process system for related disciplines such as automatic control and pipelines.

Through the process pipeline and instrument flow chart, you can understand: 1. The number, name and position number of equipment. 2. The process flow of main materials. 3. The process flow of other materials. 4. Understand the control of the production process through the analysis of valves and control points.

P&ID (Process Piping and Instrument Flow Chart)

That is, Piping Instrument Diagram, abbreviated as PID. PID is based on PFD and is completed by professionals such as process, pipeline installation and automatic control.

It is necessary to draw all equipment, instruments, pipelines and their specifications, insulation thickness, etc., which is the main basis for drawing pipeline layout diagrams.

The PID diagram is formed in the process package stage. As the design stage progresses, it is continuously supplemented, improved and deepened. It is published in stages and editions.

The publication of each edition of PID shows the progress of engineering design and provides timely design information of the corresponding stage for professionals such as process, automatic control, equipment, electrical, telecommunications, piping, pipe machinery, pipe materials, equipment layout and water supply and drainage.

PID is one of the main products in basic design and detailed design. It reflects the comprehensive results of process design flow, equipment design, equipment and pipeline layout design, and automatic control instrument design.

The relationship between the two

In actual production, there are generally only two types of process drawings that we often see to express the process, which are PFD and P&ID as we all know. PFD is actually an abbreviation of the English word, the full name is Process Flow Diagram, which means "process flow chart" in Chinese. P&ID is also an abbreviation of the English word, the full name is Piping and Instrumentation Diagram, and "&" means and in English. The whole sentence is translated as "process piping and instrumentation flow chart". The main difference between the two is the amount of content expressed in the drawing. PFD is simpler than P&ID. A clearer explanation is that the P&ID drawing basically includes all the pipe fittings, valves, instrument control points, etc. on site, which is very comprehensive, while the PFD drawing only needs to clearly express the entire production process, without having to draw all the valves, pipe fittings, and instruments.