Water Evaporator in Alberta

[Neyon]

Hi Guys,

I want to install an indoor gas fired (Natural Gas) water evaporator, do I need simply any smoke, heat or CO detection system?

the building itself unsprinkled.

The work is meant to be in Exshaw Alberta Canada

Thanks

 

[Tmoose]

Who's going to sleep in the truck outside?

http://www.azcentral.com/story/news/nation/2014/05/04/washington-cabin-deaths/8690613/

 

[Neyon]

I forgot to mention that the building is industrial (Cement plant) and 99.5% of the time is not occupied..

Thanks

 

[Neyon]

any news guys...

 

[georgeverghese]

Indoor = poorly ventilated.

Is this a natural draft heater or a forced draft heater ?

In a forced draft heater, the air must be taken from an unclassified ( = well ventilated) location.

For a natural draft heater, I'd talk to an electrical engineer

 

[Neyon]

Thank you "georgeverphese"

it's actually induced draft.

BTW, since you're Chemical, the exhaust (burner gases) will be mixed with the water vapor (steam)and pushed up through the stack, my question is, what's the preferred materials of the stack to be made of? SS 316L or ?? single or double wall?

Thanks again

 

[StoneCold]

Neyon
You will need double wall pipe to try to keep the water from re-condensing and running back down the vent.
A natural gas fired heater will need dampers open to the outside to draw in combustion air. The dampers are sized by BTU/hr/4000= square ft of open area in the dampers.
In the USA NFPA-54 would be appropriate. I don't know the Canadian specification but I am sure there is one.

Regards
StoneCold

 

[Neyon]

Thank you very "StoneCold"

The air-in is already taken care of..

FYI we use NFPA-54 as well along with CSA B149.1 for such applications.

Neyon

 

[georgeverghese]

For an induced draft heater, you may want to check if it is permitted to draw in combustion air from a HAC zone 2 location ( ie poorly ventilated indoors ). I suspect you may be required to make some changes to this heater to make it work as a forced draft unit if you must have it indoors, which may also be the reason for Imoose's cryptic response.

 

[Neyon]

I do have a louver on the wall to get fresh outside air.

the room is meant for 2 standby gen-sets (i think 500MVA each).

the evaporator or what you call it a heater is not continuously on, whenever condensate water from compressed air equipment accumulated and gets to the high-level, they automatic system will start the burner to turn the waste water into steam and out of the building.

normally no personnel is present in the room.

now i might need a gas detector?

"georgeverghese" what the difference forced draft would make? does it have to do with fan to be less susceptible to failures? or something else i'm missing?

Thank you

 

[georgeverghese]

Providing louvres alone does not make a location "well ventilated"

It doesnt matter if the heater is on intermittently or continously.

The statement "not normally manned" may not apply in these situations if there is even a remote chance of personnel entering this building

If you draw in air which is from a HAC Zone 1 or 2 location, you have the possibility of an explosion due to the operation of an induced draft heater.

A forced draft unit wouild draw air from OUTSIDE the building, which is a well ventilated location

In a forced draft unit , a combustion air fan (inside the bldg) draws in air from the outside and delivers it to the burners. In a natural draft unit, combustion air is drawn in naturally through the air dampers which are directly attached to the burner assembly. This natural aspiration occurs because of the draft pressure existing in the combustion chamber in the heater, which in turn is enabled by the static gas head created by the height of the flue stack.

In your case, combustion air will be air from inside the bldg, which has the potential to be air contaminated with fuel gas.

I have not heard of any company which installed gas detectors next to the air dampers on a fired heater to justify the use of a industrial natural draft heater indoors.

 

[Neyon]

great info "georgeverghese"

so i have these options:

- install wall intake fan starts and stops with the burner.
- Change the selection of equipment from induced to forced and duct the outside air right up to the fan intake at the equipment. (hard choice, my customer is buying the equipment)

- build a shack outdoors to put the evaporator in and heat trace all piping. (more expensive)

do you think the first option would be more feasible?

 

[Neyon]

BTW "georgeverghese"

where do I find this statement "If you draw in air which is from a HAC Zone 1 or 2 location, you have the possibility of an explosion due to the operation of an induced draft heater" or similar in the codes or standards?

I think my customer would like to see the code to go with other choices...

I don't recall i read about HAC zone 1, 2 in NFPA-31 "Standard for the Installation of Oil Burning Equipment"

please give me any code or standard refer to that..

Thanks again,

 

[georgeverghese]

Gut reaction tells me these wall fans wont be accepted in option 1

Option 2 looks good to me but you may still need gas detectors indoors since there is fuel gas piping and regulators indoors

For option 3, you may have to conform to what defines an outdoor well ventilated shelter - these would be described in the codes applicable in Alberta

Your first posting said this is a gas fired heater, while now you have looked at the NFPA for oil burning fired equipment ?

Am not an industrial safety or electrical engineer well versed in the local codes for hazardous area classification, so pls ask someone with such experience. My experience is more with equipment specified to operate in accordance with the UK IP code. ( IP = Institute of Petroleum).

Response to your earlier query on the combustion fan : In forced draft application, the fired heater is auto shutdown on comb. fan trip, loss of comb air pressure and in some cases low air fuel ratio.

 

[Neyon]

"georgeverghese" you've really been a great help...

thanks

 

[MikeHalloran]

I'm not understanding why the condensate can't just drain to outdoors. Surrely an electrical heat tape to keep it from freezing, even run all the time, would cost less than converting the water to steam and venting the steam outdoors.

... where the steam condenses and eventually falls on the ground anyway.





Mike Halloran
Pembroke Pines, FL, USA

 

[Neyon]

"MikeHalloran"

it's been drained into the sewer/storm system but recently the inspector did accept that anymore..

the condensate is not really a pure water, it's kind of oily water, you cannot just let seep on the ground.

Evaporators have 2 integral process step to remove the oil before and after steaming.

I have many compressed air equipment all over the plant producing this kind of waste water...

so the customer decided to have evaporators to get rid of this problem.

 

[georgeverghese]

In that case, can you suggest to your customer to change from an oil flooded oil compressor to an oil free air compressor - then you wont have oily condensate water, and you wont need this trouble some evaporator ?

 

[MikeHalloran]

Ah. Trace oil. Now it makes more sense. Thanks.

Reminds me of drawing water from a canal to cool a Diesel under test, and not being allowed to return the slightly heated (and not oily) water to the same canal.

Sorry for the tangent.



Mike Halloran
Pembroke Pines, FL, USA

 

[georgeverghese]

Believe there is now a biodegradeable lube oil that is suitable for oil flooded air compressors, if you are really hooked on oil flooded machines.