26 replies to this topic

[Madiha Rashid]

i am designing a fire tube boiler for my project of incineration system...kindly help me with the design specification.its different from shell and tube exchanger, also plz give some link about the logical reasoning of its selection..my boiler specs are 82 bar and 520 degree centigrade.

[breizh]

Hi,
Let you try this resource : Boliers,Evaporators & Condensers by SADIK KAKAC

It may help

Breizh

[ankur2061]

Madiha,

For your application of such high pressure and temperature a fire tube boiler may not be suitable. Refer the link below where a brief description of water tube boilers is provided:

http://en.citizendiu...Steam_generator

Also try to get hold of a book on steam generation which is condsidered the ultimate resource on steam generation using either fossil fuels or nuclear fuel. The book is:

"Steam, Its Generation & Use" by the Babcox & Wilcox Company

Regards,
Ankur.

[Art Montemayor]

Ankur is very correct in pointing out the limitations of a Fire Tube Boiler (also known as a "Scotch Marine" boiler).

I have installed and employed a lot of these types of boilers and have found that the usual top steam pressure generated by this type is approximately 75 to 100 psig (5 to 7 barg). In some cases, I have heard of installations generating 150 psig (10 barg) steam. But certainly 82 barg and 520 oC (968 oF) is totally out of the question. If those are still your steam design conditions, then you must go into a water tube type boiler design. You have no option because of the limitations of the hoop stress placed on a fire tube boiler shell. The smaller the diameter, the larger the allowable pressure in a vessel. Therefore, this is the basic principle by which you arrive at a water tube boiler - since a pipe is the practically smallest vessel diameter that you can use.

The book that Ankur mentions is the classic published by Combustion Engineering, Inc. I got a free copy as a senior Chemical Engineering student in 1959. My copy was edited by Otto de Lorenzi; it was a First Editon, eleventh impression, and second printing at that time. I still have it in my library, but I don't think you find a copy unless you have considerable luck where you are at. I quote from the book, with regards to firetube boilers:

"This is one of the oldest types of firetube boilers. these boilers are built with a combination of welded and riveted construction only, and the design pressure is limited to 250 psig. The capacity range is from 1,000 to approximately 15,000 lb/hr of saturated steam." These boilers do not produce superheated steam.

Good luck.

[Madiha Rashid]

thanx alot to all the members for giving me such valuable and useful guidelines...yes that was the point were i got struck in proceeding that fire tube boiler cant take such high pressure...i am gona work on your guide lines ..thanx to all..anybody having some other info about it plz post it

[Madiha Rashid]

sir i have searched for the book which you have mentioned "combustion engineering", but i could not find it..kindly could you please gine me a free download link of this book.

i shall be very thankful to you..kindly provide me some of you more practical knowledge about water tube boiler because a far as i know when corrosive gases are involved then you prefer to shift them toward tubes, how to justify our use of water tube i this case.

[ankur2061]

Madiha,

The book

"Steam, Its Generation & Use" can be ordered from the link provided below:

http://www.babcock.c...rary/steam.html

Regards,
Ankur

[Madiha Rashid]

Thanx a million sir...your courtesy is highly appreciated..

Regards

Madiha

[Madiha Rashid]

Hy

i have read somwhere that as far as the problem of assigning the corrosive gasses towards the shell(water tube boiler) which is generally not preffered, this problem can be resolved by mounting the boiler vertically so that scaling and other depositions can be peventes..kindly comment on this point of view..

Regards,
Madiha

[Art Montemayor]

Madiha:

Tell us WHERE, exactly, you heard that there is a problem with "the corrosive gases being on the shell side of a water tube boiler". It is important to know this because the claim is nonsensical and illogical - besides being an untruth.

If the combustion gases are corrosive, you will have a corrosion problem regardless whether the gases are on the "shell" side or the tube side. If that were the case, you simply apply corrosion resistant refractory coating on the "shell side" and employ high alloy (expensive) water tubes. The solution is that simple.

[pritishkamat]

Hi,
I'm wondering if these rules also apply to the design of the Waste-Heat Recovery section of a Sulfur Burner.
I'm basically trying to design a sulfur burner, to produce 3 TPH of SO2.
I have questions as:
1. Because im producing SO2 for Sodium Bisulfite mfg, i have very low O2 and SO3 tolerance levels. How can i design the Burner for this?
(will the Lurgi two-stage burning help here?)

2. Also, i need to estimate the amount of steam that can be generated. How does one go about these calculations? what data will i require?

Thanks
pkamat

[Art Montemayor]

pkamat:

What "rules" are you referring to? There haven't been any rules discussed in this thread up to now. What has been discussed is good, sound, experienced heat transfer design engineering - something that is started at the learning stage in university courses.

Sulfur burning and burners are conventional type of equipment in today's state of the art. You should have no problem doing research work in the internet for specific burner information.

You generate sulfur combustion calculations in the normal, logical way that you have been taught as a student. This is a straight-forward combustion calculation routine and should be no problem. It involves basic stoichiometry and leads you directly to the amount of steam that can be generated. The data you require is the lower heating value of Sulfur, of course. This is pretty logical and basic.

If you want to find out more or have further questions on your Sulfur combustion problem, please start your own original thread in this Student Forum so that we don't hijack this thread away from its origninal poster (OP).

[breizh]

Following recommendations from Art and Ankur , you may find info to support your query in the link attached

Babcock and Wilcox Steam Reference

Breizh

[pritishkamat]

Art,
Thanks for the reply and i apologise for 'hijacking' this thread.
The "rules" i mentioned are the basic rules of thumb that you've provided in your former posts. I just wonder whether they apply to a sulfur burner.
I've performed all the basic combustion calcs...but I doubt the % excess (10) that i have used. There's nothing useful on the internet that i can find.
The same regarding the selectivity towards SO3 formation.
Thanks, really appreciate it
pkamat

[Madiha Rashid]

hi

are the calculation for LMTD(log mean temperature for a waste heat boiler) is deifferent from simple exchanger due to phase cahnge?..

for my WHB the gases are on tube side with inlet pressure at 2 bar and temperature at 563 C while the oulet temperature is 325C,while BFW is entering at 126C & 84 bar while saturated steam is generated at 298 C & 83 bar...plz plz tell me for this case my tube sude heat transfer coefficient can be 0.6 W/m2 C,is it possible?

[ankur2061]

Madiha,

Please refer the attachment as a guideline for calculating the heat transfer equation.

Regards,
Ankur

Attached Files

•  Fire_Tube_Boiler.pdf   409.77KB   332 downloads

[Shivshankar]

Madiha,

Refer to this link and attachments, Hope this helps you.

http://www.steamline...la/history.html

http://www.me.ua.edu...ALS/Boilers.pdf


Regards
Shivshankar

Attached Files

•  fire tube boiler.pdf   5.14MB   292 downloads
•  4.1 Boiler.pdf   418.24KB   218 downloads

Edited by Shivshankar, 30 April 2012 - 01:24 AM.

[Madiha Rashid]

Hi
The link you gave me was helpful in calculating tube side coefficient but not for shell side were boiling is taking place,kindly help me with it.i shal be very thankful to you.

[Shivshankar]

Madiha,

Here you can find both tube and shell side coefficient in below link,

http://www.cbu.edu/~rprice/lectures/stcalcs.html

Regards
Shivshankar

[Madiha Rashid]

hi
please provide me the link for downloading Applied heat transfer by v.ganapathy.please

[ankur2061]

Madiha,

Are you asking for a free download link for the book you have mentioned? You are not permitted to solicit free download links as per the rules of the forum. It is strictly prohibited. Please take a note of it.

Regards,
Ankur.

[Madiha Rashid]

give me any link through which i can read this book

[breizh]

<sup>Madiha ,
Let you try this link
http://www.openisbn....iew/0878141820/

Breizh</sup>

[Madiha Rashid]

hi
thanx a million.plx help me members, i have my final year design presentation on boiler(fired tube type)..plx give some material from were i cal clear my concepts on boilers and heat transfer fundamentals.n different terms like critical heat flux, burnout point etc etc.

[breizh]

Let you read post # 13, you should find enough material

Breizh