The website is back to normal and the “generic money-making link site” harpy is banished. I’ll have some lengthy articles later this month. Sorry for the inconvenience.
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This short checklist will help you when drawings a Process Flow Diagram and the associated heat and material balance (aka stream table). This is a sister article to my Process and Instrumentation Diagram Checklist.
Items to check:
- Page number
- Revision number and revision purpose
- Sign-off information (such a drafter/designer/checker/approver) is correct
- All dates
- Drawing Title-block
- Notes/holds are there and correct. Check spelling, placement. Ensure any project-wide notes and holds are present.
- Stream Table – latest data, correct units of measurement, all necessary streams are listed
- Stream Table – quick logical spot-check: vapor lines don’t have liquid flowrates or vice-versa, low pressures do not flow into high pressures, mass balance closes, two sides of an exchanger have the same change in enthalpy read more…
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This is one of the better beginner’s articles on understanding pump curves and picking a correct pump for your application: “Understand the Fundamentals of Centrifugal Pumps.” Some of the important terms unique to picking pumps are explained.
If you’re already experienced at this, you can skip this article.
Popularity: 3% [?]
It is among the greatest speeches ever made on how to write well for a scientific or technical audience. One of history’s great scientists will lay down a gauntlet: writing well can be as important, if not more important, than doing great science. Do you agree?
Today we listen to Georges-Louis Leclerc, the Comte de Buffon, better known simply as “Buffon”. Buffon was a famous French scientist from the late 1700’s. Although he made important discoveries in many scientific fields, primarily biology and mathematics, he won almost as much acclaim for his impeccable writing style. Frankly, that suited him just fine.
Buffon: shall we remember him as a scientist, writer, or speaker?
When he was invited to the French Academy (of language, not the science one), he gave a famous speech called Discours sur le style (the “Discourse on Style“). Perhaps you can read the original in French, but the English-speaking world barely knows the tag-line: “the style is the man.” Nevertheless, it is one of the most famous talks ever on how to write well.
I have finally found a translation in English. The following comes from The Story of Civilization Volume 10 – The Age of Voltaire, by Will and Ariel Durant. We jump into the middle of their biography on Buffon. The Durants have some commentary before and after the speech, which I’ve left in place. Bolds and links are mine. Enjoy!
…[Buffon] was quite conscious of his literary flair. He delighted to read to his visitors melodious passages from his volumes; and when he was elected to the French Academy he took as his theme, on the day of his reception (August 25, 1753), not some marvel of science, but an analysis of style. That illustrious Discours, as Cuvier said, “gave at once the precept and the example,”… for it was itself a gem of style. From all but the French it is hidden in the mountain of his works, and little of it has come to us but its famous, pithy, cryptic judgment that “the style is the man.” Therefore let us spread it out here, and look at it leisurely. Its brilliance is dulled in translation, but even so, and though cruelly syncopated for our ignoble haste, it can adorn any page. read more…
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Creating an Electrical Area Classification Diagram involves the following basic steps, done by electrical and process engineers:
- Find all systems in the plant using flammable materials like hydrogen, natural gas, propane, butane, gas condensates, ammonia, flammable dusts, etc.
- Along the systems carrying flammables, identify on the plot plan the location of all flammable release sources such as: Open process points (like open tanks), Control valves, Pump seals, Rotating equipment, Seal pots, Drains, Metering points, Sampling points, Vents, PSVs, Rupture Disks. In general, closed metal piping or tubing without valves, fittings or flanges does not need to be considered as a potential source of release
- Get the correct electrical code, e.g. National Electrical Code (NEC) in U.S., or the Canadian Electrical Code (CEC), whatever applies. Classify the release sources identified in step #2 by the standard. For example, possible abnormal operation leak points along a Hydrogen system may be Class 1 Divison 2, Group B. (Meaning Flammable Gases, only occasionally present, gas is hydrogen). In many cases, the rating can be modified based on the quality of ventilation present.
- Create an area classification drawing, clouding the area around the hazards with the appropriate area classification. In some cases elevation drawings may also be required (especially multi-level structures). The area you must classify is often not specified in the electrical code, but depends on industry practice and site-specific tests of concentrations of flammable gases in simulated release scenarios. API 500 & 505 are good resources for determining the area to cloud around a potential hazard.
- If designing a new plant, ensure all equipment in the cloud is built to the standard specified by the cloud. If you are reviewing an existing plant, do a check to ensure that equipment inside the clouds are built for the classification. In some cases it may be possible to get an exception from the regulators for borderline cases
Good reference article: http://www.roe.com/pdfs/technical/practical%20guidelines%20for%20ctg%20power%20plants.pdf
You can hire consulting companies who are masters at steps 3 & 4, and do it easily, but steps 1, 2, and 5 still need the touch of people intimately knowledgeable about the system being drawn.
Popularity: 6% [?]
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