Conversion Burner numbers

kcopp

Tim,

 When you did conversion burners what were the numbers you got on set up and what should I be looking at for all the combustion numbers? I have one going in...Mfg is vague as to what to shoot for... CO2 , O2 Stack temp and CO in the flue gas? ty,kpc

Tim McElwain

The ball park figures

are CO2 9.5%. O2 4.5%, CO under 100 PPM air free, Stack temp 350 to 450°F, over-fire draft (which you can take as it was on oil), -.02. Double swing barometric with spill switches stack draft -.02, -.03. Make sure you fire at maximum designed input and adjust accordingly with the gas pressure regulator for best firing. Do not make drastic changes to pressure just very slight ones watching your readings. If CO starts to rise stop and set pressure back to previous point.



Good luck with your adjustments.

Steamhead

Tim, would it not be a good idea

to leave a bit of headroom when setting up a power gas burner? For example, if the CO starts rising when the CO2 percentage goes over 9.5%, would it not be a good idea to go for a slightly lower CO2 reading?



Reason I ask is our local utility is known to spike their gas supply with whatever they can get in the winter, which may raise the BTU/cubic foot content of the gas as received by the customer. This, as I understand it, would require more air to burn without making CO.



I don't have your manuals with me so can't remember if you covered this in them.

kcopp

thanks...

that is helpful...kpc

trackflg

Carlin NG

I just in stalled a Carlin EZ gas head and these are the numbers they call for.



Co2 max 10.4% min 8.5%

O2 max 6.2% min 3.0%

CO must not to exceed 50ppm

gas valve outlet not lower than 3.2 WC max 3.8 wc

Tim McElwain

I use a

higher calculation for BTU per cubic foot of 1050 BTU's to somewhat compensate for this factor (many use 1,000 as the math is easier but that is too low for actual application). If you look on customer bills you will see a monthly average of BTU send out usually in the 1025 to 1030 range. The local utility National Grid has to calculate the Wobbe Index on gas sent out into the distribution lines and they are restricted as to maximum level.

Tim McElwain

I have seen those numbers

on the EZ burner and when you get O2 down to 3% your CO2 will be around 11%. It is not far from getting on the wrong side of the curve and making CO. Remember when O2 goes down CO2 goes up. Low O2 means less excess air but for natural gas we have to have 10 cubic feet of air for every 1 cubic foot of gas (1,000 BTU's) and 4 cubic feet of excess air. The advantage of the power burner is that we can operate at a lot less excess air usually 25% or less. That is the advantage of Power Gas Burners being used to replace Power Oil. Power gas will be more efficient in the oil boiler typically than an atmospheric design gas boiler or furnace. Some boilers can get you up into 84% + combustion efficiency range when the power gas is installed



I have fired some conversion burners at around 2% O2 just to see what they would do and then monitor them on an every two week basis. I eventually however have left them as a final setting at around 4% or more for safety purposes.

kcopp

Well I did the....

Install and it went ok but... The CO2  number is not right and I can't get it down. Incoming pressure is @ 4.1" wc as the Midco ec200 asks for. Air shutter @ 2. Stack temp @ 525. CO 77ppm ,CO2 will not come down from 11.3. Any thoughts?

Tim McElwain

Is that pressure the

inlet or outlet pressure?



What is the input in BTU"s  you are looking for?



Try increasing your air setting that should lower your CO2..



Is that stack temp a net stack or gross?



What is your over-fire draft and draft at the breach?



What is the make of equipment this is installed in?

kcopp

results...

Tim sorry for not getting back to you sooner. The inlet pressure was off... I should invest in a Digital manometer vs my Dial type.

I was shooting for 100k.. That was gross stack(still high) but what do you want for a boiler if that age. Weil-466e.The HO wanted to keep it a few years more.

Here is what I ended up w/  my Wohler335...TS 568, Ta 80.6, o2 4.5, co2 9.2, Eff 78.3% Ea 27%, co 310ppm... The co  seemed  very high but Midco says that it was fine... thoughts?

Tim McElwain

Midco is looking at

the ANSI standard allowable CO in the flue of 400 PPM. You really should be able to get it down to close to 100 but you may have some residual carbon inside the unit that needs to be cleaned out. You will also find when you get it down your efficiency will go up. The rest of the figures look pretty good.

kcopp

Tim... you rock.

I went back today... to re run the numbers.They dropped a SS liner yesterday. The CO number was @ 68ppm. Swapped out the old main vents. The sytem should be much better this winter.TY,kpc

Steamhead

Much better

but what were the rest of the numbers, including the draft? Also, did you clock the meter to cross-check your orifice size (if one was used)?

kcopp

The draft...

was -0.01 wc. No orifice for the 100k output. Manifold pressure was set @ 1" wc or just over to get the numbers to what they were. What other numbers would you like?

Steamhead

W-M 68 boilers

like a bit more draft in the stack, as their tight flue passages create a lot of resistance. Same with the Peerless JO series. We usually set these to -0.04 or so, at least on oil.



If you don't mind, go ahead and list the stack temp, CO2 etc. so we can see how you ended up.

kcopp

they are....

listed above.... about 4 posts ago.

Steamhead

These?

TS 568, Ta 80.6, o2 4.5, co2 9.2, Eff 78.3% Ea 27%, co (was) 310ppm?



I'm curious whether the other readings changed after the liner was installed.

kcopp

the stack....

temp was @ 520F (gross) the the co2 and o2 numbers only moved a couple tenths after the liner was in. The Co number dropped to 68ppm. This was also about two days of running so any residual carbon after the bush and vac had some time to bun off... sound right? looking back i tried to sell the customer on a new gas steamer (weil EG series) but he wanted to save a few dollars and try this route.... the burner will get reused after this one starts leaking..... thats the plan anyhow.

Steamhead

Definitely better

and you may be right about soot that you couldn't get to. We recently converted a Burnham V-73 to gas with an EC-200, and got similar results but the CO was lower. Also tested a V-84 (oversized and down-fired a bit) that someone else had put a Wayne P250 gas gun onto- not my favorite burner but it tuned up OK, still with a stack temp around 500.



It will be interesting to see how these units test out after a year's running.



And that EC-200 will run fine in a Slant/Fin Intrepid, when it comes time to replace the W-M.