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STACK DESIGN 1
- Thread starter libn999
- Start date
LittleInch
Petroleum
libin,
I can see you're kind of new to this site, but please look at your post and think "how will anyone actually know what on earth I'm on about"
Stack? Stack of what? cards, books, what??
guidelines and codes - Care to tell us which ones?
"resource materials" - do you mean books and guides or what to make it out of?
What are finding difficult / can't understand?
I personally doubt you will actually reply, but if you do, it might be best to start again, be an engineer, assuming you are one, and approach this like a message you would send to someone in your company or a superior, not addressed like you're talking to friend down the pub. Size, usage, location, the thing you don't know or can't understand, some drawings, sketches, links, data sheets....
If you do it right you will get a lot of help here -for free! - but do it wrong - like this - and you won't.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
I can see you're kind of new to this site, but please look at your post and think "how will anyone actually know what on earth I'm on about"
Stack? Stack of what? cards, books, what??
guidelines and codes - Care to tell us which ones?
"resource materials" - do you mean books and guides or what to make it out of?
What are finding difficult / can't understand?
I personally doubt you will actually reply, but if you do, it might be best to start again, be an engineer, assuming you are one, and approach this like a message you would send to someone in your company or a superior, not addressed like you're talking to friend down the pub. Size, usage, location, the thing you don't know or can't understand, some drawings, sketches, links, data sheets....
If you do it right you will get a lot of help here -for free! - but do it wrong - like this - and you won't.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
The last time I tried to draw what a stack should look like, I was slapped.
Chris, CSWA
SolidWorks '15
SolidWorks Legion
Chris, CSWA
SolidWorks '15
SolidWorks Legion
- Thread starter
- #5
Dear All,
I am sorry about the insufficient information.
infact my situation is as follows,
I have a Flue gas expelling stack.
it contain co2, so2, h2o etc.
temperature of inlet gas is 400 degree celsius.
I know the flow rate aslo, 12000Nm3/hr
the cusotmer have given a height of stack as 20meters.
I understand my scope is as follows,
sizing the diemater,
thickness calculation
identifying the requirement of wind girders.
Now I want to know if I miss something.
is there any standards that can give directions.
I hope that now I am clear.
Kindly help.
libin
I am sorry about the insufficient information.
infact my situation is as follows,
I have a Flue gas expelling stack.
it contain co2, so2, h2o etc.
temperature of inlet gas is 400 degree celsius.
I know the flow rate aslo, 12000Nm3/hr
the cusotmer have given a height of stack as 20meters.
I understand my scope is as follows,
sizing the diemater,
thickness calculation
identifying the requirement of wind girders.
Now I want to know if I miss something.
is there any standards that can give directions.
I hope that now I am clear.
Kindly help.
libin
-
1
- #7
georgeverghese
Chemical
Though the stack dia has some influence on pressure drop, there are two main outcomes expected from flue stack setup
a) Provide sufficient draft pressure for the upstream device - is this a fired heater ? It is typical, even on a forced draft fired heater, to ensure that the radiant chamber pressure is negative. You should ask some one experienced to help you with this. There are guidelines for running this calculation in Perry's Chemical Engineers Handbook, I recall.
b) There is SO2 in your flue gas, so you have to ask some one to do a dispersion analysis for this flue gas to ensure that ground level concentration for SO2 is within TWA limits assigned by the appropriate local authority for your location. This has to be done for various wind speeds and wind stability class for your location. Min stack height to be used for this dispersion should not be lower than that calculated for function (a). You may need to go higher. Again, this is a job for a specialist who has computer programs for modelling stack dispersions. They should provide you with a report that you can submit to your local authority as evidence that you have met this TWA limit. If there are 2 or 3 other cases where SO2 concentration is higher, these should be disclosed and described to your modelling specialist in the workscope document to this modelling company. If there are any other objectionable gases in the flue stack, these should also be disclosed.
c) If your flue stack gas is only 400degC, it wont autoignite any other common hydrocarbon sources nearby, if these exist, since autoignition temp fo methane is about 550degC. However, if this stack is nearby some other unit that can leak some chemical component which has a lower autoignition temp approaching 400degC, then the stack may need to be relocated to be outside the LFL contour for this leak source. Information on this may be available with the plant process safety engineer and/or the electrical hazardous area classification drawings for this location around this stack.
d)One minor point - you may need to sort out the rain ingress prevention device configuration on the flue stack exit before you talk to the dispersion specialist - this may have some influence on the results.
e) With SO2 in the stack gas, some kind of external insulation may be necessary to prevent acid gas condensation on the carbon steel inner wall of the stack. Else use some inner coating to protect the stack inner wall from SO2 wet flue gas corrosion.
a) Provide sufficient draft pressure for the upstream device - is this a fired heater ? It is typical, even on a forced draft fired heater, to ensure that the radiant chamber pressure is negative. You should ask some one experienced to help you with this. There are guidelines for running this calculation in Perry's Chemical Engineers Handbook, I recall.
b) There is SO2 in your flue gas, so you have to ask some one to do a dispersion analysis for this flue gas to ensure that ground level concentration for SO2 is within TWA limits assigned by the appropriate local authority for your location. This has to be done for various wind speeds and wind stability class for your location. Min stack height to be used for this dispersion should not be lower than that calculated for function (a). You may need to go higher. Again, this is a job for a specialist who has computer programs for modelling stack dispersions. They should provide you with a report that you can submit to your local authority as evidence that you have met this TWA limit. If there are 2 or 3 other cases where SO2 concentration is higher, these should be disclosed and described to your modelling specialist in the workscope document to this modelling company. If there are any other objectionable gases in the flue stack, these should also be disclosed.
c) If your flue stack gas is only 400degC, it wont autoignite any other common hydrocarbon sources nearby, if these exist, since autoignition temp fo methane is about 550degC. However, if this stack is nearby some other unit that can leak some chemical component which has a lower autoignition temp approaching 400degC, then the stack may need to be relocated to be outside the LFL contour for this leak source. Information on this may be available with the plant process safety engineer and/or the electrical hazardous area classification drawings for this location around this stack.
d)One minor point - you may need to sort out the rain ingress prevention device configuration on the flue stack exit before you talk to the dispersion specialist - this may have some influence on the results.
e) With SO2 in the stack gas, some kind of external insulation may be necessary to prevent acid gas condensation on the carbon steel inner wall of the stack. Else use some inner coating to protect the stack inner wall from SO2 wet flue gas corrosion.
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