Do I need an exhaust stack?

[mrmoffitt]

I have a stream of 250F wet air (wet with water not oil) downstream from the clean side of a baghouse. There is a PCV maintaining 20" w.c. on the baghouse that exhausts to atmosphere. The vendor expects the vent to atmosphere to be normally 3000 scfm with excursions up to 8000 scfm. The baghouse is filtering coal dust. My question is, do I need to send this vent to a stack? I haven't found anything yet on temperature limits for exhaust streams to require a stack and since the stream is air with some water in it, I am not convinced we need to erect a 150' stack to vent this stream. The vent is about 16 feet away from a stair tower that is 130' tall.

 

[shvet]

we need to erect a 150' stack to vent this stream
Why 150'? Why not 15' or 1.5'? Is there something behind it?

did you calculate the exhaust plume layout? do you know what happens with neighboring structures and platforms during the relief?

 

[TugboatEng]

I guess it depends on the prevailing wind. Do your workers like being humidified before the job under certain wind conditions?

 

[shvet]

Do your workers like being humidified ...?
humidified and exposed to fine dust

Would I been working at such facility I do not want to be exposed to such 'air', regardless to direction of prevailing wind. I suppose all structures at neighbouhood will be colored by a black dirt less than a year.

 

[TugboatEng]

The purpose of the question is to make the OP reflect on what they are actually asking. The situation is to make workers walk through an exhaust stream on route to site as opposed to routing the exhaust away from the site.

 

[georgeverghese]

How often is this stair tower in use ?
And if the hot thermal plume (which may be some 150degF or more by the time it hits the stairs )were to impinge anywhere along this tower whilst there are personnel on these stairs, do you have any thermal shielding along these stairs ? Or is there an escape route to avoid being roasted?

 

[LittleInch]

"I am not convinced we need to erect a 150' stack to vent this stream. The vent is about 16 feet away from a stair tower that is 130' tall."

Why?

This seems to be both sensible and required by regulations to protect works from being exposed to very hot wet air which would be very uncomfortable / dangerous.

In certain (most?) atmospheric conditions I imagine this would be a plume of steam/ condensed water

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

Why? Just a little bit worse than Dubai.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[pierreick]

HI,
Check with your local EPA and your safety manager.
Pierre

 

[mrmoffitt]

The design is not to allow dust escape, obviously. We have broken bag detectors to check for particles in the stream. But it is a coal processing facility and the whole facility is covered with black dust and while we aren't trying to contribute to that, a certain amount is inevitable. I have not done the plume calculations and that would be the next step to determine if the stair tower will be safe for personnel but we were initially thinking it would dissipate enough by the time it got to the stair tower. In talking further, it would likely create a fog cloud on cold days at the least in the immediate vicinity and still potentially cause harm to personnel. The reason we have to make the stack 150' tall at minimum is because we need to take it over to the stair tower if we are going to do anything and if we take it over there then we need to get it 10' above the highest point which is 140'.

 

[GD2]

OP,The situation you are describing is understandable. You have both health hazard and possibly corrosions on metal parts where the coal dust build up.

The post could be better under the "Chemical Process Design" group.

It's a design study Most likely, the original design was to mix the dust with water and carry it up by hot air (hot air will rise) to disperse it at height. The design is not working because the heavy dust particles falls down unlike combustion gases dispersion in a flare stack.

I don't think even increasing the stack height will help you.

I would suggest you to do a proper third party engineering done for this. You have a serious problem here - how and where to disperse/offload the light weight dust particles and without effecting nearby vegetation, flora, fauna and human habitation.

The good place will be to look at the design of coal-powered power plant exhaust. The difference will be that they will have the flue gas but you can take the clue of separating the dust particles from releasing into air.

Lot depends upon where (country) the facility is located.


GDD
Canada