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now i want to answer any thing related to design of thermosyphon reboilers...
you can ask from me. i am waiting for your questions.
thank you
ali dasmeh ( an Iranian Designer of thermosyphons)
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Vertical Thermosyphon Reboiler Design
Started by dasmeh_ali, Aug 24 2005 04:25 PM
7 replies to this topic
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#1
dasmeh_ali
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Posted 24 August 2005 - 04:25 PM
now i want to answer any thing related to design of thermosyphon reboilers...
you can ask from me. i am waiting for your questions.
thank you
ali dasmeh ( an Iranian Designer of thermosyphons)
#2
Guest_jsw_*
Guest_jsw_*
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Posted 25 August 2005 - 05:23 PM
I'll take you up on that offer. I need a thermosyphon reboiler made from stainless steel. Will be subject to fouling so must be cleanable. Hot side saturated steam 150degC, flow rate as needed to achieve that below. I want to condense this stream but not necesarily cool it - final temperature not very important.
Cold side is a weak chemical solution but can be considered water for now, at 127 degC. Want to turn this to steam at 127 degC (20 psig), 3500 kg/hr. With regard to performance, cost and maintenance, is shell and tube or plate HXR likely to be best? Any other information you are able and willing to provide is appreciated.
Thanks! jsw
now i want to answer any thing related to design of thermosyphon reboilers...
you can ask from me. i am waiting for your questions.
thank you
ali dasmeh ( an Iranian Designer of thermosyphons)
Cold side is a weak chemical solution but can be considered water for now, at 127 degC. Want to turn this to steam at 127 degC (20 psig), 3500 kg/hr. With regard to performance, cost and maintenance, is shell and tube or plate HXR likely to be best? Any other information you are able and willing to provide is appreciated.
Thanks! jsw
QUOTE (dasmeh_ali @ Aug 24 2005, 04:25 PM)
now i want to answer any thing related to design of thermosyphon reboilers...
you can ask from me. i am waiting for your questions.
thank you
ali dasmeh ( an Iranian Designer of thermosyphons)
#3
dasmeh_ali
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Posted 28 August 2005 - 11:12 AM
QUOTE (jsw @ Aug 25 2005, 06:23 PM)
I'll take you up on that offer. I need a thermosyphon reboiler made from stainless steel. Will be subject to fouling so must be cleanable. Hot side saturated steam 150degC, flow rate as needed to achieve that below. I want to condense this stream but not necesarily cool it - final temperature not very important.
Cold side is a weak chemical solution but can be considered water for now, at 127 degC. Want to turn this to steam at 127 degC (20 psig), 3500 kg/hr. With regard to performance, cost and maintenance, is shell and tube or plate HXR likely to be best? Any other information you are able and willing to provide is appreciated.
Thanks! jsw
now i want to answer any thing related to design of thermosyphon reboilers...
you can ask from me. i am waiting for your questions.
thank you
ali dasmeh ( an Iranian Designer of thermosyphons)
Dear jsw
About your question :
Based on your process description , every things refers to a PHE . in a same duty application , PHE is better than SH&T HXR because of :
1- good operation in fouling services
2- higher performane
3- low volume
4- low weight
5- low space
6- good control in corrosive conditions.
But there is a fact , that construction and design of a PHE related to specific companies , and design criterias such as correlation and methodes of construction did not issued such as SH&T heat exchangers in the literature.
If it is possible for you to evalute the economics of a PHE , you can judge between use of PHE and SH & T . in the case of maintenance I think with a thermosyphon reboiler , PHE and SH&T are not different.
And both of them need a specifiec maintenance care.
So if we would have a statement about this tasc we have :
In performance evaluation , for specified problem I think PHE is better that SH&T but every thing is returns to cost . based on my experiences , the cost of construction of a PHE is higher than SH&T exchanger . but if a company can make PHE cheaper than Sh&T , I think in all of aspects the PHE is more attractive to use for this condition .
Thank you ( ali dasmeh / an Iranian Designer of Thermosyphons)
Cold side is a weak chemical solution but can be considered water for now, at 127 degC. Want to turn this to steam at 127 degC (20 psig), 3500 kg/hr. With regard to performance, cost and maintenance, is shell and tube or plate HXR likely to be best? Any other information you are able and willing to provide is appreciated.
Thanks! jsw
QUOTE (dasmeh_ali @ Aug 24 2005, 04:25 PM)
now i want to answer any thing related to design of thermosyphon reboilers...
you can ask from me. i am waiting for your questions.
thank you
ali dasmeh ( an Iranian Designer of thermosyphons)
Dear jsw
About your question :
Based on your process description , every things refers to a PHE . in a same duty application , PHE is better than SH&T HXR because of :
1- good operation in fouling services
2- higher performane
3- low volume
4- low weight
5- low space
6- good control in corrosive conditions.
But there is a fact , that construction and design of a PHE related to specific companies , and design criterias such as correlation and methodes of construction did not issued such as SH&T heat exchangers in the literature.
If it is possible for you to evalute the economics of a PHE , you can judge between use of PHE and SH & T . in the case of maintenance I think with a thermosyphon reboiler , PHE and SH&T are not different.
And both of them need a specifiec maintenance care.
So if we would have a statement about this tasc we have :
In performance evaluation , for specified problem I think PHE is better that SH&T but every thing is returns to cost . based on my experiences , the cost of construction of a PHE is higher than SH&T exchanger . but if a company can make PHE cheaper than Sh&T , I think in all of aspects the PHE is more attractive to use for this condition .
Thank you ( ali dasmeh / an Iranian Designer of Thermosyphons)
#4
Guest_Ahmed Vawda_*
Guest_Ahmed Vawda_*
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- guestGuests
Posted 31 August 2005 - 05:53 PM
QUOTE (dasmeh_ali @ Aug 28 2005, 11:12 AM)
QUOTE (jsw @ Aug 25 2005, 06:23 PM)
I'll take you up on that offer. I need a thermosyphon reboiler made from stainless steel. Will be subject to fouling so must be cleanable. Hot side saturated steam 150degC, flow rate as needed to achieve that below. I want to condense this stream but not necesarily cool it - final temperature not very important.
Cold side is a weak chemical solution but can be considered water for now, at 127 degC. Want to turn this to steam at 127 degC (20 psig), 3500 kg/hr. With regard to performance, cost and maintenance, is shell and tube or plate HXR likely to be best? Any other information you are able and willing to provide is appreciated.
Thanks! jsw
now i want to answer any thing related to design of thermosyphon reboilers...
you can ask from me. i am waiting for your questions.
thank you
ali dasmeh ( an Iranian Designer of thermosyphons)
Dear jsw
About your question :
Based on your process description , every things refers to a PHE . in a same duty application , PHE is better than SH&T HXR because of :
1- good operation in fouling services
2- higher performane
3- low volume
4- low weight
5- low space
6- good control in corrosive conditions.
But there is a fact , that construction and design of a PHE related to specific companies , and design criterias such as correlation and methodes of construction did not issued such as SH&T heat exchangers in the literature.
If it is possible for you to evalute the economics of a PHE , you can judge between use of PHE and SH & T . in the case of maintenance I think with a thermosyphon reboiler , PHE and SH&T are not different.
And both of them need a specifiec maintenance care.
So if we would have a statement about this tasc we have :
In performance evaluation , for specified problem I think PHE is better that SH&T but every thing is returns to cost . based on my experiences , the cost of construction of a PHE is higher than SH&T exchanger . but if a company can make PHE cheaper than Sh&T , I think in all of aspects the PHE is more attractive to use for this condition .
Thank you ( ali dasmeh / an Iranian Designer of Thermosyphons)
Cold side is a weak chemical solution but can be considered water for now, at 127 degC. Want to turn this to steam at 127 degC (20 psig), 3500 kg/hr. With regard to performance, cost and maintenance, is shell and tube or plate HXR likely to be best? Any other information you are able and willing to provide is appreciated.
Thanks! jsw
QUOTE (dasmeh_ali @ Aug 24 2005, 04:25 PM)
now i want to answer any thing related to design of thermosyphon reboilers...
you can ask from me. i am waiting for your questions.
thank you
ali dasmeh ( an Iranian Designer of thermosyphons)
Dear jsw
About your question :
Based on your process description , every things refers to a PHE . in a same duty application , PHE is better than SH&T HXR because of :
1- good operation in fouling services
2- higher performane
3- low volume
4- low weight
5- low space
6- good control in corrosive conditions.
But there is a fact , that construction and design of a PHE related to specific companies , and design criterias such as correlation and methodes of construction did not issued such as SH&T heat exchangers in the literature.
If it is possible for you to evalute the economics of a PHE , you can judge between use of PHE and SH & T . in the case of maintenance I think with a thermosyphon reboiler , PHE and SH&T are not different.
And both of them need a specifiec maintenance care.
So if we would have a statement about this tasc we have :
In performance evaluation , for specified problem I think PHE is better that SH&T but every thing is returns to cost . based on my experiences , the cost of construction of a PHE is higher than SH&T exchanger . but if a company can make PHE cheaper than Sh&T , I think in all of aspects the PHE is more attractive to use for this condition .
Thank you ( ali dasmeh / an Iranian Designer of Thermosyphons)
#5
Guest_Ahmed Vawda_*
Guest_Ahmed Vawda_*
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- guestGuests
Posted 31 August 2005 - 06:35 PM
[quote=Ahmed Vawda,Aug 31 2005, 05:53 PM][quote=dasmeh_ali,Aug 28 2005, 11:12 AM][quote=jsw,Aug 25 2005, 06:23 PM]I'll take you up on that offer. I need a thermosyphon reboiler made from stainless steel. Will be subject to fouling so must be cleanable. Hot side saturated steam 150degC, flow rate as needed to achieve that below. I want to condense this stream but not necesarily cool it - final temperature not very important.
Cold side is a weak chemical solution but can be considered water for now, at 127 degC. Want to turn this to steam at 127 degC (20 psig), 3500 kg/hr. With regard to performance, cost and maintenance, is shell and tube or plate HXR likely to be best? Any other information you are able and willing to provide is appreciated.
Thanks! jsw
[quote=dasmeh_ali,Aug 24 2005, 04:25 PM]
now i want to answer any thing related to design of thermosyphon reboilers...
you can ask from me. i am waiting for your questions.
thank you
ali dasmeh ( an Iranian Designer of thermosyphons)
[/quote]
Dear jsw
About your question :
Based on your process description , every things refers to a PHE . in a same duty application , PHE is better than SH&T HXR because of :
1- good operation in fouling services
2- higher performane
3- low volume
4- low weight
5- low space
6- good control in corrosive conditions.
But there is a fact , that construction and design of a PHE related to specific companies , and design criterias such as correlation and methodes of construction did not issued such as SH&T heat exchangers in the literature.
If it is possible for you to evalute the economics of a PHE , you can judge between use of PHE and SH & T . in the case of maintenance I think with a thermosyphon reboiler , PHE and SH&T are not different.
And both of them need a specifiec maintenance care.
So if we would have a statement about this tasc we have :
In performance evaluation , for specified problem I think PHE is better that SH&T but every thing is returns to cost . based on my experiences , the cost of construction of a PHE is higher than SH&T exchanger . but if a company can make PHE cheaper than Sh&T , I think in all of aspects the PHE is more attractive to use for this condition .
Thank you ( ali dasmeh / an Iranian Designer of Thermosyphons)
Hello JSW
I had a similar requirement a couple of years ago, but dealt with it in a different way.There is a paper on steam transformers published in pipingdesign.com which you may find interesting.
As our esteemed Iranian colleague mentioned, PHEs have many advantages over the S&T, price being one of the more critical one.
In your particular case, I would recommend a welded plate heat exchanger, purely because I dont trust gaskets at the temperature and pressure you have available. Boiling shall take place in between the plates and water will flow through the unit by natural circulation.
The water feed inlet will be from the bottom and a two phase mixture of water and evaporated vapour will leave the unit through the upper nozzle. as you know two phase flow is a tricky situation and care must be taken to ensure the stability of the fluid flows.
The total pressure drop must be less than the static height of the liquid level in the vessel to ensure sufficient circulation.
The two-phase mixture from the PHE should enter the tank well above the maximum upper liquid level.
I have guestimated that the HE will produce 3.5 t/h if the circulating liquor is at boiling point. If the circulating fluid is less than its boiling point, the steam consumption will increase to take this into account. The available delta T is about 23 deg C and I have estimated that your heat exchanger requires about 100 m2 of heating surface.
You can expect OHTC in excess of 3 kW/m2/h.
I recommend that you bounce this concept off a PHE manufacturer and after you agree on a suitable fouling factor for your product, a price will be quoted.
Ahmed Vawda
www.unitedsugar.com
Cold side is a weak chemical solution but can be considered water for now, at 127 degC. Want to turn this to steam at 127 degC (20 psig), 3500 kg/hr. With regard to performance, cost and maintenance, is shell and tube or plate HXR likely to be best? Any other information you are able and willing to provide is appreciated.
Thanks! jsw
[quote=dasmeh_ali,Aug 24 2005, 04:25 PM]
now i want to answer any thing related to design of thermosyphon reboilers...
you can ask from me. i am waiting for your questions.
thank you
ali dasmeh ( an Iranian Designer of thermosyphons)
[/quote]
Dear jsw
About your question :
Based on your process description , every things refers to a PHE . in a same duty application , PHE is better than SH&T HXR because of :
1- good operation in fouling services
2- higher performane
3- low volume
4- low weight
5- low space
6- good control in corrosive conditions.
But there is a fact , that construction and design of a PHE related to specific companies , and design criterias such as correlation and methodes of construction did not issued such as SH&T heat exchangers in the literature.
If it is possible for you to evalute the economics of a PHE , you can judge between use of PHE and SH & T . in the case of maintenance I think with a thermosyphon reboiler , PHE and SH&T are not different.
And both of them need a specifiec maintenance care.
So if we would have a statement about this tasc we have :
In performance evaluation , for specified problem I think PHE is better that SH&T but every thing is returns to cost . based on my experiences , the cost of construction of a PHE is higher than SH&T exchanger . but if a company can make PHE cheaper than Sh&T , I think in all of aspects the PHE is more attractive to use for this condition .
Thank you ( ali dasmeh / an Iranian Designer of Thermosyphons)
Hello JSW
I had a similar requirement a couple of years ago, but dealt with it in a different way.There is a paper on steam transformers published in pipingdesign.com which you may find interesting.
As our esteemed Iranian colleague mentioned, PHEs have many advantages over the S&T, price being one of the more critical one.
In your particular case, I would recommend a welded plate heat exchanger, purely because I dont trust gaskets at the temperature and pressure you have available. Boiling shall take place in between the plates and water will flow through the unit by natural circulation.
The water feed inlet will be from the bottom and a two phase mixture of water and evaporated vapour will leave the unit through the upper nozzle. as you know two phase flow is a tricky situation and care must be taken to ensure the stability of the fluid flows.
The total pressure drop must be less than the static height of the liquid level in the vessel to ensure sufficient circulation.
The two-phase mixture from the PHE should enter the tank well above the maximum upper liquid level.
I have guestimated that the HE will produce 3.5 t/h if the circulating liquor is at boiling point. If the circulating fluid is less than its boiling point, the steam consumption will increase to take this into account. The available delta T is about 23 deg C and I have estimated that your heat exchanger requires about 100 m2 of heating surface.
You can expect OHTC in excess of 3 kW/m2/h.
I recommend that you bounce this concept off a PHE manufacturer and after you agree on a suitable fouling factor for your product, a price will be quoted.
Ahmed Vawda
www.unitedsugar.com
Attached Files
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PHE_Thermosyphon.doc 76.5KB
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#6
Guest_jsw_*
Guest_jsw_*
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Posted 06 September 2005 - 08:29 PM
Thank you for your thoughts AV. I will take your advice except on the welded HE - it is important to take the HE apart and clean so will have to discuss sutability of gaskets with manufaturer.
Thanks
jsw
Thanks
jsw
#7
Sadananda Konchady
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Posted 14 September 2005 - 07:55 AM
Would larger diameter tubes (for example 38.1 mm. OD tubes instead of 25.4 mm OD tubes) be more economical for vertical thermosiphon reboilers with vacuum conditions (0.3 bar(a) ) on the tube side?
Thank you,
Escape
Thank you,
Escape
#8
kemathut
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Brand New Member
Posted 31 October 2009 - 03:18 AM
Dear ali dasmeh ( an Iranian Designer of thermosyphons)
I would like to ask for your suggestion sir :
At my plant, I have a vertical thermosyphon reboiler which after i calculate the level in the reboiler (based on the column level), the level seem to be lower than the upper tubesheet of the reboiler. Should I try to increase this level to the upper tubesheet or not. Is there any advantage or drawback to increase the liquid level in the reboiler. Please give me you comment sir
Regards
Kemathut
I would like to ask for your suggestion sir :
At my plant, I have a vertical thermosyphon reboiler which after i calculate the level in the reboiler (based on the column level), the level seem to be lower than the upper tubesheet of the reboiler. Should I try to increase this level to the upper tubesheet or not. Is there any advantage or drawback to increase the liquid level in the reboiler. Please give me you comment sir
Regards
Kemathut
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