How beginners can understand process flow diagrams with control nodes
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How can beginners understand process flow diagrams with control nodes? It’s mainly represented by symbols; is there a unified standard? Can this standard be found?
The best way to understand process flow diagrams is by combining theory with practice. Theoretically, it is recommended that you consult the \"Common Data Manual for Instruments\" and ASME Y32.11-1961, which covers graphic symbols used in process flow diagrams in the petrochemical industry. I also have an electronic version of JB-T 9170, which deals with graphic symbols for process flow diagrams, though it is intended for the machinery industry. Practical learning* involves going to the workshop to see the actual physical components corresponding to the control nodes shown in the flowcharts, thereby enhancing your practical understanding.
When beginners look at process flow diagrams, my personal advice is to first identify the equipment and understand its functions and key parameters； Next, look at the pipelines to understand the materials and their flow direction; more specifically, it is possible to determine the temperature, pressure, and flow rate of the materials ； Finally, clarify the control points, the function of each valve, interlocks, etc.
As a supplementary note, design institutes usually provide a cover page with legend explanations for the designs; one can also refer to the general guidelines provided there to understand the rules for numbering pipe sections and valves.
I can’t upload screenshots in this post. You can look it up in the \"Chemical Process Design Handbook\"; there are illustrations there. They are basically interconnected in the chemical industry. This post was last edited by lbp on 2009-4-3 21:23]
It is recommended to first look at books on professional process drawing before examining the drawings themselves; otherwise, it will be difficult to understand the basics. Books on process drawing should be easy to find, as such tutorials are generally available to those with a degree in chemistry or related fields at the college level or above
The first sheet of the drawings is usually the title page, on which the methods for representing various valves and the meaning of each letter are described in detail. Next, it is necessary to understand the control scheme for each piece of equipment; for example, in the case of a tower, its operation is controlled by regulating tower pressure, reflux, or some other parameter.
If you want to know what each symbol represents, you should check the legend sheet on the homepage; some abbreviations related to instrument controls may not be listed there (as different organizations use different standards), so you can ask engineers in the relevant field for clarification. To share some of my own experience, I started working last year as a process engineer, and the first difficult task I faced was understanding PID. My approach is to first read the process description, and then use that description along with the PFD (the flow diagram with material numbers) to get a good understanding of the entire process. Only after that do I move on to looking at the PID. This method makes things more organized, but the downside is that it is time-consuming. However, if you want to master a new technique, don’t be afraid to waste time.
First, one needs to be able to read the homepage image and the device list.
In addition to the essential accompanying elements such as the homepage image, pipe layout diagrams, and arrangement plans, it is also useful to refer to the operation manual for this process; it would be even better to go to the site in person to understand the entire setup of the pipelines, which will make it much easier to comprehend the flow diagrams
Based on the material flow and the instructions on the home page, it is generally possible to understand which controls are involved; for a more detailed understanding, one can refer to the unit control diagrams provided by the Ministry of Chemical Industry – they are excellent resources
First, understand the legend for design PI&D; the process legends vary from one design institute to another. HG has a standard one.
You should read the instructions related to the process. At the same time, you should have an English-Chinese dictionary for chemical technologies and equipment. It was compiled by HUANQIU COMPANY; it’s a useful tool worth reading. If you read it carefully, you’ll find it quite easy. You’ll develop a great interest in chemical processes, and you’ll make progress day by day. Good luck! :lol :lol
This might be better: first read the instructions, then look at the process flow diagram; for parts that are not clear, refer to the legend, and finally examine the equipment list and piping list.
I think it’s fine to hold the flowchart and compare it with the actual pipelines on site; once you get familiar with them, it’ll be okay.