Why Would Anybody Run a Nitrogen/Methanol System?
Once upon a time in North America gas fired Endothermic Generators reigned supreme when it came to atmosphere heat treating. Unreliable and problem plagued they were an easy prey to Nitrogen/Methanol systems which promised to be clean, reliable, simple and low maintenance and consequently 30-40 years ago Nitrogen/Methanol systems slowly captured a larger and larger share of the market. However Advancements in Endo Generator technology removed virtually all of the original headaches and combined with the far lower cost of endo gas as opposed to Nitrogen the end result is that Generators again reign supreme.
This is of course largely ancient history now but what prompted us to mention it today is that we ran across a large captive heat treat earlier this week who were largely unaware of the relative costs of the two systems. In an effort to prove our point that endo generators are a far more cost effective way to go we reached out to one of the largest furnace builders in North America who provided this handy/dandy Nitrogen/Methanol vs. Endo Calculation which shows the relative costs.
At this point we should mention two caveats;
The figures in this example will vary tremendously according to location so this is only designed to show the relative costs as opposed to exact costs.
The comparison between the two atmospheres is assuming that a constant natural gas supply is available. In a location with no gas available Nitrogen/Methanol might well be the only option available.
To return to our original statement “Why Would Anybody Run a Nitrogen/Methanol System?-our answer would be we are not entirely sure why unless no gas is available.
Nitrogen/Methanol vs. Endo Calculation – Generator [4500 CFH]
- Cost of methanol = $2.04/gallon @ 240 ft3/gallon = $0.0085/ft3
- To make 4500 CFH equivalent of endo gas requires 11.25 gallons of methanol + 1800 ft3 of nitrogen
- Nitrogen cost = $.7072/100 ft3 = $0.007072/ft3
- Cost of natural gas @ $9.21/1000 ft3 = $0.00921/ft3
- Cost of electricity = $0.0842/KWH
This computes to:
- Methanol: 11.25 gallons x 240 ft3 x $0.0085 = $22.95 / hour
- Nitrogen: 1800 ft3 x $0.007072 = $12.73 / hour
– Electricity to run methanol pump = .74 KW x $0.07 = $ 0.06 / hour
– TOTAL $35.74 / hour
Endo generator gas
- Natural gas: reaction. = 900 ft3 x 0.00921 = $ 8.29/ hour
- Natural gas to heat generator = 200 ft3 x $0.00921= $ 1.84 / hour
- Electricity to run air pump = 3.54 KW x $0.00842 = $ 0.30 / hour
– TOTAL $ 10.43 / hour
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