A Load Of Hot Air!
Apart from having nothing at all to do with bulk solids handling this topic is quite abstract. You are not heating with LPG: you are using air & LPG but you do not mention the air pressure etc etc. The final paragraph appears to answer the first paragraph anyway. ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
Lpg And Different Flow Valves
Hi there!
Posted this before but in the wrong forum I guess:
I have a question regarding different types of control valves used for regulating LPG flow.
Say we have two situations where LPG is burnt to heat up a mass of steel (which is used for fiberizing glass wool - just for your info) and the required fume pressure of LPG (i.e. where the LPG flame is coming in contact with the steel) is about 210 mmWC. In situation one, the gas-flow meter gives a reading of 20m3/hr to give a fume pressure of 210 mmWC. In situation 2, the gas flow meter gives a reading of 40 m3/hr to give exactly the same fume pressure. Now, is it possible that in situation 2, because the control valve was of the type that had a higher pressure loss, the amount of flow required to produce fume pressure of 210mmWC was higher than situation 1 (which had a better valve if you like..i.e. the pressure lost across it was much less)? In other words, is there so much difference between any two valve types that one would cause you to have double the flow-rate to achieve same fume pressure...?? Otherwise there's too much pressure loss in the piping or something wrong with one of the flow-meters.....?
I REALLY NEED TO UNDERSTAND THIS - EVEN ANY LINKS RECOMMENDED WILL BE GREAT!
An aside question: Am I correct in understanding that the temperature of the flame is not dependent on the flow-rate of LPG but the air to fuel ratio; so in both situations above, the temperature of the flame should be the same regardless of the fact that the flow-rate is very different? Now, if you are heating up a mass of steel, then even though with different flow-rates the FLAME temperature will be the same but because the volume (and therefore the TOTAL energy) of exhausted lpg gas and air is different, the STEEL temperature for two different flow-rates will be different ...
Thanks ■
Poor Lost Soul About To Blow Himself Up
As John so eloquently stated, this topic has nothing to do with bulk solids handling.
However, as an engineer who studied how to do engineering with rockets and ended up doing engineering with rocks, I will try to answer this guy's question, and hope that he doesn't blow himself up before he finds the right answer.
There is no such thing as fume pressure, which is why he can't find any relevant information.
The most probable cause of the difference between his flow meter readings is that one of his flow meters is designed for propane (density = 1.7 kg/m3), and the other is designed for natural gas (density = 0.7-0.9 kg/m3).
The factor of 2 difference in the gas density would results in a factor of 2 difference in the flow rate.
If, on the other hand, his flow meters are both properly calibrated for LPG, then the burner with the higher flow rate will not produce a higher temperature, but it will heat the steel twice as fast.
I suggest that the originator of this thread take an extended web-surf through related topics on the Engineer's Toolbox website
http://www.engineeringtoolbox.com/fl...ters-t49.html ■
From Eloquence To Poetry.
Originally Posted by thompson
However, as an engineer who studied how to do engineering with rockets and ended up doing engineering with rocks, .........
I suggest that the originator of this thread take an extended web-surf through related topics on the Engineer's Toolbox website
http://www.engineeringtoolbox.com/fl...ters-t49.html
Your experience is similar to many. I started out developing combustion systems for Concorde jetliners and fighter bombers and finished up down gold mines in Saath Efrika. I've worked with guys who started out designing prosthetic hands and heart valves and turned to rocks. There must be something in the water, or blood. I look back and think what would have happened if I'd never gone into mining. I would probably have been bored for longer.
(I was on a weekend voyage to Holland and standing on the deck observing Hooghovens steelworks. I remarked to a nurse, who I had met the night before, that the steelworks seemed to have run out out of space and that was why the stockpile extension was where it was. She said "Oh, is that what engineers do then." I really enjoyed replying "Well actually, aliens come down and show us what to do.") ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
Re: Lpg, Control Valves And Pressure Loss
Thank you for your replies John and Thompson.
Interesting point Thompson - I checked with our manintenance dept about the meter being designed for natural gas but they said that they are both for LPG (though they didn't look convincing!).
And as for fume pressure, that is what our licensor calls it - the pressure of the combustion gases.....
Anyway I will still continue searching......
Thanks again ■
Re: Lpg, Control Valves And Pressure Loss
Good post. Really informative about the LPG valves and valve pressure. ■
LPG, control valves and pressure loss
Hi there!
I have a question regarding different types of control valves used for regulating LPG flow.
Say we have two situations where LPG is used to heat up a mass of steel and the required fume pressure of LPG (i.e. where the LPG flame is coming in contact with the steel) is about 210 mmWC. In situation one, the gas-flow meter gives a reading of 20m3/hr to give a fume pressure of 210 mmWC. In situation 2, the gas flow meter gives a reading of 40 m3/hr to give exactly the same fume pressure. Now, is it possible that because in situation 2, because the control valve was of the type that had a higher pressure loss, the amount of flow required to produce fume pressure of 210mmWC was higher than situation 1 (which had a better valve if you like..i.e. the pressure lost across it was much less)? EVERYTHING ELSE IN BOTH SITUATIONS IS EXACTLY THE SAME
If indeed control valves can result in a higher consumption of LPG for same fume pressure, are there any links for knowing about good valve selection and sizing for LPG lines (I tried googling for hours but I just can't seem to find exactly what I'm after!!!!)
And what about the effect of pipe size (diameter) on how much flow-rate is required to produce same fume pressure (assuming same length of pipeline)?
An aside question: Am I correct in understanding that the temperature of the flame is not dependent on the flow-rate of LPG but the air to fuel ratio; so in both situations above, the temperature of the flame should be the same regardless of the fact that the flow-rate is very different? Now, if you are heating up a mass of steel, then even though with different flow-rates the FLAME temperature will be the same but because the volume of exhaust is different, the STEEL temperature for two different flow-rates will be different ...
Thanks ■