Friday, April 4, 2008
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A Shell & Tube heat exchanger potentially expose to the risk of internal failure results a complete tube rupture. Read Criteria for Requirement of Pressure Relief Device for Tube Rupture for criteria lead to tube rupture. In determining the required relieving flow rate, API Std 521 - ISO 23251, Fifth edition, Jan 2007, "Pressure-relieving and Depressuring Systems ", section 5.19.3. can be referred
5.19.3 Determining the required relief flow rateIn practice, an internal failure can vary from a pinhole leak to a complete tube rupture. For the purpose of determining the required relieving flow rate for the steady-state approach, the following basis should be used.a) The tube failure is a sharp break in one tube.
b) The tube failure is assumed to occur at the back side of the tubesheet.
c) The high-pressure fluid is assumed to flow both through the tube stub remaining in the tubesheet and through the other longer section of tube.A simplifying assumption of two orifices may also be used in lieu of the above method, since this produces a larger relief flow rate than the above approach of a long open tube and tube stub.
How to determine a maximum area for relieving flow in Plate & Frame heat exchanger (PHE) which is having rather different structure in construction ?
A Plate & Frame Heat Exchanger is constructed by putting many corrugated plates together likes a sandwich and allowing fluids passing the channels (opening area between plate). Hot and cold will take the channel between plate in "sandwich" format e.g. first channel is hot fluid in upward direction, second channel is cold fluid in downward direction, third channel is hot fluid in upward direction again, etc... Detail may refer HERE...
Cross sectional view of the plate heat exchanger is as follow.
Refer to following image.
From above limit, maximum relief flow shall be taken as equivalent to the leakage rate through a pinhole of a cross sectional area equal to twice the maximum area of a "tube" cross sectional area. This maximum "tube" cross sectional area may be advised by PHE vendor.
Related Topic
A Plate & Frame Heat Exchanger is constructed by putting many corrugated plates together likes a sandwich and allowing fluids passing the channels (opening area between plate). Hot and cold will take the channel between plate in "sandwich" format e.g. first channel is hot fluid in upward direction, second channel is cold fluid in downward direction, third channel is hot fluid in upward direction again, etc... Detail may refer HERE...
Cross sectional view of the plate heat exchanger is as follow.
Refer to following image.
From above limit, maximum relief flow shall be taken as equivalent to the leakage rate through a pinhole of a cross sectional area equal to twice the maximum area of a "tube" cross sectional area. This maximum "tube" cross sectional area may be advised by PHE vendor.
Related Topic
- Complicated Tube Rupture Scenario... Nightmare in Sizing a PRD
- Two-third (2/3) rule or Ten-thirteen (10/13) rule ?
- Tube Rupture : Pressure Relief Valve (PSV) or Rupture Disk (RD) ?
- Criteria for Requirement of Pressure Relief Device for Tube Rupture
- Requirement of Overpressure Protection Device on "Final Vessel"
- FREE & Reliable Pressure Relief Valve Sizing Software
- Extra Caution When Eliminating Overpressure by Fire Attacks
- Should maximum recommended wall temperature (Tw) for carbon steel vessel used as design temperature ?
- Should we install Butterfly valve for Pressure Relief Valve (PSV) isolation ?
Labels: Heat Exchanger, Overpressure Protection, PHE, Plate Heat Exchanger
Wednesday, August 1, 2007
Plate Heat Exchanger having narrow channel most probably "not recommended" for fluid contains solid and/or slurry services. However, there are still many success story of using PHE in abovementioned services.
There are some rule-of-thumbs to gage if a plate heat exchanger suitable for fluid contains solid or slurry :
i) 80% of the particles are less than 70% of the interplate gap on the heat exchanger.
ii) 100% of the particles are less than 90% of the interplate gap
iii) Flowing velocity is below erosional velocity (causes premature plate failure)
iv) The minimum wall temperature is above a point where crystal growth is expected.
Further reading
Labels: Heat Exchanger, PHE, Plate Heat Exchanger, Rule-Of-Thumb, Slurry, Solid
Saturday, July 21, 2007
Tubular Exchanger Manufacturers Association (TEMA) has developed a series of fouling factor for Shell and Tube (S&T). These fouling factor are generally higher than Plate Heat Exchanger (PHE), why not use S&T fouling factors to size PHE ?
Isn't this approach conservative and guarantee the performance ?
Reason being...
- Oversized Plate Heat Exchanger (PHE) required extra CAPEX and extra Space for oversized PHE
Tubulence minimise fouling tendencies in correctly sized PHE. Oversized PHE results low actual velocity and increase potential fouling and inefficient heat transfer
HTRI studies showed PHE fouling significant lower than Shell & Tube Heat Exchanger (S&T)...factor of 6.7
GUIDELINE : Do not oversized PHE more than 25% against required area.
Further reading :
- Do Not Overspecified Fouling Factor s for PHE
- Why Lower Fouling in Plate Heat Exchanger ?
- Heat Exchanger Fouling Mechanism, Prevention and Treatment
- PHE - Remove some plates, will pressure drop increase ?
Labels: Fouling, Heat Exchanger, PHE, Plate Heat Exchanger
Thursday, June 21, 2007
Plate heat exchanger - Remove some plates...will the pressure drop across the exchanger increase or decrease ?
In a Plate heat exchangers, there are number of plates for the 'hot' fluid and given number of plates for the 'cold' fluid. The cold fluid flows through the cold layers in a parallel type arrangement, same for the hot fluid. The hot fluid layers are typically laid counter-current to the cold layers. By removing plates, you will effectively be reducing the free flow area. This will increase the velocity, which is proportional to the square root of the pressure drop, it is anticipated an increase in pressure drop.
If you benefits from this post...buy me some sweets
Labels: Brazed Plate Heat Exchanger, Heat Exchanger, PHE, Pressure Drop, Velocity
Monday, June 11, 2007
Many months ago, i have attended it seminar on vacuum system. Pretty professional in vacuum and heat transfer area...
FREE articles available for engineers...
Plate heat exchangers (PHE) consist of a series of thin corrugated plates hung from a carrying bar and clamped between a fixed and movable head plate. The corrugated plates or heat transfer plates are normally stainless steel or other materials ductile enough to allow pressing. Each heat transfer plate is fitted with an elastomeric gasket, partly to seal and partly to distribute the process fluids. Connections in the fixed or movable head plates permit the entry of the process fluids into the plate pack...
Heat Exchangers in Municipal Wastewater Treatment Plants
Spiral heat exchangers have been shown to be economical and reliable for handling municipal wastewater treatment plant sludge heating duties. These exchangers are able to operate reliably when fed with solid and fiber laden fluids, such as sewage sludge. Plate heat exchangers provide an economical option for basic liquid-to-liquid service. Compactness, efficiency, reliability, ease of maintenance, and low initial investment make this exchanger design the choice for many wastewater treatment applications...
Using PC Software to Predict Heat Exchanger Performance
Heat exchanger designers establish operational constraints when they develop a system. In practice, these constraints are conservatively stated, although rarely experienced, during the useful lifetime of a system. Usually, a designer assumes worst-case conditions with respect to the inlet cooling-water temperature and fouling. However, when operational variables change, such as thermal load and cooling-tower temperature, it is necessary to predict exchanger performance under the new conditions so that the impact on all variables in the process loop can be determined...
Heat exchanger designers establish operational constraints when they develop a system. In practice, these constraints are conservatively stated, although rarely experienced, during the useful lifetime of a system. Usually, a designer assumes worst-case conditions with respect to the inlet cooling-water temperature and fouling. However, when operational variables change, such as thermal load and cooling-tower temperature, it is necessary to predict exchanger performance under the new conditions so that the impact on all variables in the process loop can be determined...
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Labels: Design, Heat Exchanger, PHE, Wastewater Treatment
Sunday, June 10, 2007
Many of us may already familiar with this company...
"Alfa Laval is the leading manufacturer of plate heat exchangers in the world. We provide you with compact, modern solutions with the highest thermal efficiency."...read more...
Alfa Laval Plate technology - A detailed look at plate heat exchange (PHE) technology from Alfa Laval
Designing Plate-and-Frame Heat Exchanger - FREE article from ALFA LAVAL...
Labels: Design, Heat Exchanger, PHE, Technology
Saturday, June 9, 2007
Paul Mueller Company, a company incepted in 1940, specializes in the design and manufacture of stainless steel processing systems and equipment for the food, dairy, beverage, pharmaceutical, chemical, biotech, and bottled water industries.Products ranges
Processing Systems and Equipment
In this post, i would like to bring to you it HEAT TRANSFER equipment. MUELLER manufactures :
FREE Sizing program & Articles available in MUELLER :
Accu-Therm Sizing Program
Product Brochures available FREE for download
Ad 375-2
Your Heat Transfer Solutions Provider
Ad 386
Accu-Therm® Plate Heat Exchangers
AT-1601-11
Accu-Therm Plate Heat Exchangers
AT-1607-9
Free-Flow Plate Heat Exchangers
AT-1609-2
Accu-Therm Advantage in Metal Finishing
AT-1610-1
Accu-Therm Back Flush System
AT-1629-3
Accu-Therm Double-Wall Heat Exchangers
AT-1635
Accu-Therm Typical HVAC Cooling Applications
AT-1638-2
Accu-Therm Sanitary Plate Heat Exchangers
AT-1648
New Larger Accu-Therm Plates
BP-1800-1
Brazed Plate Heat Exchangers
O-1453
ASME Plate Heat Exchanger Spec Sheet
O-1454
Non-ASME Plate Heat Exchanger Spec Sheet
TP-103-7
Temp-Plate® Immersion Sections for Metal Finishing Industry
TP-107-2
Temp-Plate Idea Book
TP-108-13
All About Temp-Plate®
TP-111-3
Temp-Plate Energy Banks
TP-406-3
Heat Transfer Solutions
TP-408-3
Double-Embossed Temp-Plate Clamp-On Sections
TP-412-3
Clamp-On Heat Transfer Surface
TP-413-2
Clamp-On Temp-Plate Heat Transfer Surface
TP-433-1
Panel-Coil™
Your Heat Transfer Solutions Provider
Ad 386
Accu-Therm® Plate Heat Exchangers
AT-1601-11
Accu-Therm Plate Heat Exchangers
AT-1607-9
Free-Flow Plate Heat Exchangers
AT-1609-2
Accu-Therm Advantage in Metal Finishing
AT-1610-1
Accu-Therm Back Flush System
AT-1629-3
Accu-Therm Double-Wall Heat Exchangers
AT-1635
Accu-Therm Typical HVAC Cooling Applications
AT-1638-2
Accu-Therm Sanitary Plate Heat Exchangers
AT-1648
New Larger Accu-Therm Plates
BP-1800-1
Brazed Plate Heat Exchangers
O-1453
ASME Plate Heat Exchanger Spec Sheet
O-1454
Non-ASME Plate Heat Exchanger Spec Sheet
TP-103-7
Temp-Plate® Immersion Sections for Metal Finishing Industry
TP-107-2
Temp-Plate Idea Book
TP-108-13
All About Temp-Plate®
TP-111-3
Temp-Plate Energy Banks
TP-406-3
Heat Transfer Solutions
TP-408-3
Double-Embossed Temp-Plate Clamp-On Sections
TP-412-3
Clamp-On Heat Transfer Surface
TP-413-2
Clamp-On Temp-Plate Heat Transfer Surface
TP-433-1
Panel-Coil™
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Labels: Heat Exchanger, PHE, Software
