7 replies to this topic

[chau]

DeAR All

Great salutation.

I been told by some experts to prefer to go for fire tube boiler in case of waste heat rceovery system. Idont know what could be the culprit to incline towards the fire tube boiler, but there have been saying that for a larger flow gas fire tube is recomended as the gas passage is on tube side and water flow on shell side to get the desirable steam.

Now my concern is what is the mountable reason that one should go for fire tubeboiler. Objectively this waste heat recovery boiler has to used in cement plant where we get high flue gas from preheatre and cooler gas.
The input parameter is

SOURCE-1(PH) SOURCE-II(COOLER GAS)
1) Mass flow 338792 kg/hr 206554 kg/hr
2) Temp 716 F 482 F

Now above depicted parameter sounds for the more mass flow .

I appreciate to get addressed to my concern , whether we should go for fire tube or water tube boiler

If it is firetube than what could be the concrete reason to support the proposed boiler

hary

[djack77494]

hary,
I find your query confusing but may still be able to offer you some help. When I think of fire-tube or water-tube boilers, I envision a fired device (i.e. a combustion process) with the fire contained in either a firetube or a firebox. When I think of a waste heat recovery boiler, I think of a device resembling a kettle style shell & tube heat exchanger. Based on my understanding of your process, with the combustion process occuring outside this device and with the hot flue gas temperature in the range of 600F to 650F, I think you want the waste heat recovery (S&T) boiler; I would not refer to this device as either a fire-tube or a water tube boiler. Please advise if my understanding is not correct.

[chau]

Dear djack

How are you.

Normlly to keep the nomenclature in engineering things coonstant , could patronage the things easy to concive. The point is you are absolutly right at your path to concieve the firetube boiler with combustion process. But to keep the things more understandable we call the firetube in waste heat recovery system as teh tube where gas flow will take place. To your information , the concept does not have any combustion gas, instead the hot gas comong out of cement plant . In essence to To utilize the heat duty of the same gas by getting the embraced and handsome opoer o/p by getting steam , we use WHR system. Basically you can call it as a heat exchanger

harry

[Padmakar Katre]

Dear,
Instead to seek the readymade answer just google the keyword Water Heat Boiler (Fire Tube) and find tonns of materials available.

[djack77494]

harry,
I'm not sure I'm getting your point. It seems to me like what you should really be asking is whether to put the hot gas on the tubeside or shellside. Is that your real question? If it is, then I can answer you by saying that the hot gases should go on the tube side of the exchanger with boiling water on the shell side. I would never refer to this exchanger as a firetube boiler, however, but if you know what you want then what matter the name you give it?

[chau]

harry,
I'm not sure I'm getting your point. It seems to me like what you should really be asking is whether to put the hot gas on the tubeside or shellside. Is that your real question? If it is, then I can answer you by saying that the hot gases should go on the tube side of the exchanger with boiling water on the shell side. I would never refer to this exchanger as a firetube boiler, however, but if you know what you want then what matter the name you give it?

HI DJACK

Tonns of thanx for your reply.

You rightly said the gas should be in tube side. I been told from my boiler fellow that the gas will on shell and water on tube side. Idont no what culprit he envisaged to go with this proposal, but can you enlighten me why the gas should be in tube and water in shell side

harry

[djack77494]

You rightly said the gas should be in tube side. I been told from my boiler fellow that the gas will on shell and water on tube side. Idont no what culprit he envisaged to go with this proposal, but can you enlighten me why the gas should be in tube and water in shell side

Whenever I am faced with questions like this, I start by trying to determine what other very clever fellows before me have done. So please, don't just take my word for it but find similar applications and see what was done before.

The main reason for my recommendation is because it takes space to separate two phases. You have a boiling liquid that must be separated into steam and water. You need disengagement space to accomplish this. That is why K-type (kettle) heat exchangers are commonly used when one of the fluids is a boiling liquid. The enlarged section of the kettle provides the space needed to permit any entrained liquid to complete its separation from the outgoing steam. Furthermore, the highest temperature fluid (i.e. the source of your waste heat) is on the tube side of the exchanger.

I'd recommend that you try to obtain a table of considerations for selection of sides of a heat exchanger. You will see that various factors lead the designer to select which side of the exchanger will be best for which fluid. Often the criteria conflict. (That is true in this case because one of the criteria is to prefer the tubeside [steam] for the higher pressure fluid.) You must wade through the criteria and select "the optimum". In this case, I suspect that a kettle exchanger with steam generation in the shell is best.

[chau]

You rightly said the gas should be in tube side. I been told from my boiler fellow that the gas will on shell and water on tube side. Idont no what culprit he envisaged to go with this proposal, but can you enlighten me why the gas should be in tube and water in shell side

Whenever I am faced with questions like this, I start by trying to determine what other very clever fellows before me have done. So please, don't just take my word for it but find similar applications and see what was done before.

The main reason for my recommendation is because it takes space to separate two phases. You have a boiling liquid that must be separated into steam and water. You need disengagement space to accomplish this. That is why K-type (kettle) heat exchangers are commonly used when one of the fluids is a boiling liquid. The enlarged section of the kettle provides the space needed to permit any entrained liquid to complete its separation from the outgoing steam. Furthermore, the highest temperature fluid (i.e. the source of your waste heat) is on the tube side of the exchanger.

I'd recommend that you try to obtain a table of considerations for selection of sides of a heat exchanger. You will see that various factors lead the designer to select which side of the exchanger will be best for which fluid. Often the criteria conflict. (That is true in this case because one of the criteria is to prefer the tubeside [steam] for the higher pressure fluid.) You must wade through the criteria and select "the optimum". In this case, I suspect that a kettle exchanger with steam generation in the shell is best.

Dear DJACK

Thnx for your concious coverage , can you send me the table for consideration for selection of side of heat x

harry