Plate Heat Exchangers - part 2🚀

Warm greetings to all 🤩in the 23th post on #Day23 ! Today, we will add some information about the baffles and Plate heat exchangers. Here we go🐢,

P.S: In the future, these posts will be extended.

Introduction🌝

An innovative type of heat exchanger that has found widespread use is the plate and frame (or just plate) heat exchanger, which consists of a series of plates with corrugated flat flow passages (Fig. 13–6). The hot and cold fluids flow in alternate passages, and thus each cold fluid stream is surrounded by two hot fluid streams, resulting in very effective heat transfer. Also, plate heat exchangers can grow with increasing demand for heat transfer by simply mounting more plates. They are well suited for liquid-to-liquid heat exchange applications, provided that the hot and cold fluid streams are at about the same pressure.

🤔These exchangers are generally built of thin plates. The plate are either smooth or have some form of corrugations and they are either flow or wound in exchanger. Generally, these exchangers cannot accomodate high pressure/temperature differential relative the tubular exchanger. This type of exchanger is further classified as:

• ✅Gasketed plate

• ✅Fixed plate

• ✅Spiral plate

• Gasketed plate heat exchanger

Gasketed plate heat exchanger (see Fig. 2.9) consists of a series of corrugated alloy material channel plates, bounded by elastomeric gaskets are hung off and guided by longitudinal carrying bars, then compressed by large-diameter tightening bolts between two pressure retaining frame plates (cover plates).

🔰The frame and channel plates have portholes which allow the process flow to enter alternating flow passages (the space between two adjacent-channel plates) Fig.2.10. Gaskets around the periphery of the channel plate prevent leakage to the atmosphere and also prevent process flow from coming in contact with the frame plates. Fig.2.11 shows the plate profil Expansion of the initial unit is easily performed without special considerations. The original frame length typically has an additional capacity of 15-20 percent more channel plates (i.e. surface area). ❗️In fact, if a known future capacity is available during fabrication stages, a longer carrying bar could be installed, and later, increasing the surface area would be easily handled. When the expansion is needed, simply untighthen the carrying bolts, pull back the frame plate, add the additional channel plates, and tighten the frame plate.

• Applications

Most PHE applications are liquid-liquid services but there are numerous steam heater and evaporator uses from their heritage in the food industry. Industrial users typically have chevron style channel plates while some food applications are washboard style. Fine particulate slurries in concentrations up to 70 percent by weight are possible with standard channel spacings. Wide-gap units are used with larger particle sizes. Typical particle size should not exceed 75 percent of the single plate (not total channel) gap. Close temperature approaches and tight temperature control possible with PHE’s and the ability to sanitize the entire heat transfer surface easily were a major benefit in the food and pharmaceutical industry.

• Advantages

• Easily assembled and dismantled

• Easily cleaned both chemically and mechanically

• Flexible (the heat transfer can be changed as required)

• Can be used for multiple service as required

• Leak is immediately detected since all plates are vented to the atmosphere, and the flow split on the flow or rather than mixing with other flow

• Heat transfer coefficient is larger and hence small heat transfer area is required than STHE • The space required is less than that for STHE for the same duty

• Less fouling due to high turbulent flow

• Low hold up volume

• More economical when material cost are high

• Disadvantages

• Low pressure <30 bar (plate deformation)

• Working temperature of < (500 F) [250 oC] (maximum gasket temperature) see table 2.1.

Welded and Brazed-Plate exchanger (W. PHE and BHE) 📚

To overcome the gasket limitations, PHE manufacturers have developed welded-plate exchangers. There are numerous approaches to this solution: weld plate pairs together with the other flow conventionally gasketed, weld up both sides but use a horizontal stacking of plates method of assembly, entirely braze the plates together with copper or nickel brazing, diff bond then pressure form plates and bond etched, passage plates Fig. 2.12 and Fig. 2.13. Typical applications include district heating where the low cost and minimal maintenance have made this type of heat exchanger especially attractive.

📌Most methods of welded-plate manufacturing do not allow for inspection of the heat- transfer surface, mechanical cleaning of that surface, and have limited ability to repair or plug off damage channels. Consider these limitations when the flow is heavily fouling, has solids, or in general the repair or plugging ability for severe services.

Spiral Plate Exchanger (SPHE) 🔎

The spiral-plate heat exchanger (SHE) may be one exchanger selected primarily on its virtues and not on its initial cost. SPHEs offer high reliability and on-line performance in many severely fouling services such as slurries. The SHE is formed by rolling two strips of plate, with welded-on spacer studs, upon each other into clock-spring shape Fig.2.14 and Fig.2.15. This forms two passages. Passages are sealed off on one end of the SHE by welding a bar to the plates; hot and cold flow passages are sealed off on opposite ends of the SHE. A single rectangular flow passage is now formed for each flow producing very high shear rates compared to tubular designs. Removable covers are provided on each end to access and clean the entire heat transfer surface.

• Applications

The most common applications that fi SHE are slurries. The rectan- gular channel provides high shear and turbulence to sweep the surface clear of blockage and causes no distribution problems associated with other exchanger types. A localized restriction causes an increase in local velocity which aids in keeping the unit free flowing. Only fi ers that are long and stringy cause SHE to have a blockage it cannot clear itself. As an additional antifoulant measure, SHEs have been coated with a phenolic lining. This provides some degree of corrosion protection as well, but this is not guaranteed due to pinholes in the lining process.

📌Note:

Additional details to Baffles

📌 https://www.instagram.com/p/CA0X-nPjQfI/?igshid=1d6hetu5qngbl

⠀

📍On the whole, baffles are flow-directing or obstructing vanes or panels used in some industrial process vessels, such as shell and tube heat exchangers ( main focus of this post), chemical reactors, and static mixers. Baffles are an integral part of the shell and tube heat exchanger design. A baffle is designed to support tube bundles and direct the flow of fluids for maximum efficiency. Baffle design and tolerances for heat exchangers are discussed in the standards of the Tubular Exchanger Manufacturers Association (TEMA).⠀

⠀

📍The main roles of a baffle in a shell and tube heat exchanger are to: ⠀

• Hold tubes in position (preventing sagging), both in production and operation

• Prevent the effects of steam starvation (happens when there is not sufficient fluid within the vessel), which is increased with both fluid velocity and the length of the exchanger⠀

• Direct shell-side fluid flow along tube field. This increases fluid velocity (decrease in area) and the effective heat transfer co-efficient of the exchanger ⠀

📌Check out this link for the rest of the post: https://www.instagram.com/p/CA0X-nPjQfI/?igshid=1d6hetu5qngbl

References📖

1. Heat Exchangers: Design, Operation, Maintenance and Enhancement

2. Heat Transfer by Yunus Chengel

3. Coulson&Richardson-Chemical Engineering Design Vol 6

4. https://www.sacome.com/en/heat-exchanger-advantages-uses-applications/

5. https://www.explainthatstuff.com/how-heat-exchangers-work.html

6. http://www.thermex.co.uk/news/blog/160-what-is-a-heat-exchanger

Additional Resources 🧪🔑

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

✏️Note: If you need one of those books or links, you can contact me via my email or LinkedIn profile.

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