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Writer's pictureTaliya Mammadhasanzada
Sep 1, 20204 min read

Separators- part 1🧪

Warm greetings to all🧬 in the 28th post on #Day28 ! Today, we will start to learn about separators. Here we go🚿,




🗡P.S: New information will be included with more examples.


General Information🚀

Separators are essential components in industrial refrigeration systems. Separators (also known as suction traps, knock-out drums, low pressure receivers, accumulators, recirculators) are pressure vessels that may serve multiple functions including separation of liquid from a liquid-vapor stream (to protect compressors from liquid carry-over), maintain adequate supply of liquid for mechanical pumps, and to provide a buffer for accumulation of liquid during transient system operation. With the application of refrigerant separators in ammonia refrigeration systems, the catastrophic or accelerated failure of compressors due to liquid-carry over has been greatly reduced. Virtually all of the liquid-vapor refrigerant separators used in the ammonia refrigeration market today rely on gravity forces to “knock out” or separate liquid from vapor (so called gravity separators).


  • Separator in Oil&Gas Industry




 

  • Three Phase Separator




Vapor-Hydrocarbon- Water Liquid 🚀

Gravity Settling

The majority of the process vessels we see in the plant are gravity, vapor-liquid separators. Their main purpose is to settle out droplets of entrained liquid from the up-flowing gas. Factors that affect the settling rate of these droplets are

  • Droplet size. Big droplets settle faster than little droplets. Contrary to that nonsense we were taught in school, cannonballs do drop faster then BBs—if one accounts for the resistance of air (BBs are small spheres of lead shot used in air guns).

  • Density of vapor. The less dense the vapor, the faster the droplet settling rate.

  • Density of liquid. The more dense the liquid droplets, the faster the droplet settling rate

  • Velocity of vapor. The slower the vertical velocity of the vapor, the faster the settling rate.

  • Viscosity of the vapor. The lower the vapor viscosity, the faster the settling rate.

🚀All these ideas have been put into one equation, called Stokes’ law. Nothing against Sir Frederick Stokes, but vapor viscosities are almost always so small that they do not affect settling rates. Also, we never know the particle size distribution of the droplets. There is a more fruitful way to look at the settling tendency of droplets of liquid in an up-flowing vapor stream, as shown in Fig. 39.1. The method states

1. The lifting force of the vapor is proportional to the momentum of the vapor.

2. The lifting force of the vapor is inversely proportional to the density of the liquid, which we will call DL (lb/ft3).


🚀Equation and Figure 39.1 are given below:


For more watch this:


Water-Hydrocarbon Separations🥰

Figure 39.3 shows a reflux drum serving a distillation column. We have a reflux drum because

  • The drum provides a few minutes of holdup for the overhead product and reflux. This prevents the reflux pump from losing suction should the amount of liquid discharging from the pump briefly exceed the amount of liquid draining from the condenser.


• The reflux drum separates liquid and wet gas by gravity settling. A horizontal vapor-liquid separator works in much the same way as the vertical KO drum.

• The horizontal reflux drum also separates hydrocarbon liquid from water.


🤔Why do we usually want to separate water from the reflux stream, as shown in Fig. 39.3? Some of the bad things that happen to the distillation tower if water persistently entrains into the reflux are


• The distillation tray efficiency is reduced. The water may settle out beneath the hydrocarbon liquid on the tray. This reduces contact between the up-flowing vapor and the downflowing, internal reflux.

• The tray may flood. Water and hydrocarbon mixing on the tray deck, stirred up by the flowing gas, creates an emulsion. The emulsion does not separate as readily as clear liquid from the gas. Premature downcomer backup followed by tray deck flooding result.

• Tray deck, downcomer, and vess wall corrosion is increased. Water conducts electricity a thousand times better than do liquid hydrocarbons. Corrosion involves the transfer of electrons between steel and inorganic molecules.


 

• Hydrochloric acid to form ferric chlorides

• Hydrogen cyanide to form ferric cyanide

• Carbon dioxide to form iron carbonate

• Hydrogen sulfide to form iron bisulfide


🚀The water acts as a highway for the electrons (the term electrons comes from the word electricity) to move between these potentially corrosive molecules and the vessel wall. Water in reflux tends to get trapped in the tower if the towerbottom temperature is above the boiling point of water at the tower’s operating pressure. The water trickles down the tower and revaporizes off of the hot reboiler tubes. As the water may be saturated with corrosive salts and gases, reboiler tube corrosion can be rapid. In almost every petroleum refinery service, refluxing water is a quick route to reboiler tube leaks.


  • Separation of mixture components by extraction


References📖

  1. A working guide to Process Design and Equipment by Norman Lieberman

  2. GRAVITY SEPARATOR FUNDAMENTALS AND DESIGN by TODD B. JEKEL, PH.D.

Additional Resources 🧪🔑

You can get deep insight about Process/Chemical Engineering from these sources😉:

  1. https://youtu.be/pcGTIRGkEyw Pumps

  2. https://www.facebook.com/SPE.BHOS - SPE BHOS arranges technical, soft skill sessions and shares a lot of quizzes, competitions and related books for petroleum and process engineering students

  3. https://www.instagram.com/p/CAXT-ZhlrRW/ Engineerium Mentoring Center Instagram page

  4. https://www.facebook.com/engineeriummentoringcenter Engineerium Mentoring Center Facebook page

  5. http://www2.eng.cam.ac.uk/~mpj1001/learnfluidmechanics.org/LFM_L6.html

  6. https://www.youtube.com/watch?v=NCvYPclQNWM Heat Exchangers Explanation

  7. https://t.me/ebookstorage/210-Introduction to Process Engineering and Design (2015)

  8. https://t.me/ebookstorage/211-Elementary Principles of Chemical Processes

  9. https://t.me/OilAndGas/18122Valve Sizing Sheet

  10. https://t.me/ebookgate/1127Engineering Fluid Mechanics Book

  11. https://coursemania.xyz/course.html?id=433291 Free course on Fundamentals of Fluid Mechanics

  12. https://t.me/ebookstorage/178 Engineering Heat Transfer

  13. https://t.me/ebookstorage/159 Fundamentals of Engineering Thermodynamics (9th Edition) (2018)

  14. https://t.me/ebookstorage/18 Heat Transfer applications and principles

  15. https://t.me/ebookstorage/171-Design and Operation of Heat Exchangers and their Networks (2020)

  16. https://t.me/ebookstorage/215- Industrial Separation Processes (book)

  17. https://t.me/ebookstorage/214- Advanced Process Engineering Control (book)

  18. https://t.me/OilAndGas- Information about Oil&Gas (mainly arabic lang)

  19. https://t.me/chemical_worlds- Chemical Engineering Books, Quizzes and GATE Study Group

  20. https://t.me/chemical_environmental- Discussion group related to Chemical Engineering Problems

  21. https://t.me/chemicalengineeringworld_cew- Everything related to Chemical Engineering

  22. https://t.me/ebookgate- Chemical Engineering E-books (Telegram Channel)

  23. https://www.youtube.com/channel/UCqioh32NOJc8P7cPo3jHrbg- Piping Analysis

  24. https://www.youtube.com/channel/UCQfMyugsjrVUWU0v_ZxQs2Q -Mechanics of engineered devices

  25. http://chemicalengineeringguy.com/- suggests a wide range of courses in Chemical engineering (you can find free courses on topic of Aspen HYSYS, Aspen Plus)

  26. https://www.youtube.com/user/LearnEngineeringTeam- suggests working principles of every engineered devices, equipment and etch.

  27. https://www.youtube.com/channel/UCR0EfsRZIwA5TVDaQbTqwEQ- suggests great information about pumps, compressors with animation.



😋Today we have started learning about Separators. Now, time to say goodbye👋🏻 until tomorrow and Stay tuned for more content 😉🌝✨!


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