Looking for a push in the right direction...

[justinbeau]

I am untrained in the field of ventilation. I am a recent grad from an environmental engineering technologist program. I am employed at a local landfill, and my job is to run the landfill gas flaring system. 25 gas wells are drilled into the landfill (the landfill is "sealed or a semi-closed system" with a top and bottom liner), and the gas is drawn out of the wells through 10" HDPE pipe with a 900cfm blower.

I have two questions:

1. Where can I find information on basic ventilation on the web? Tutorials, theory, formulas, etc...

2. What would cause my "draw/vacuum" to drop by 25% (from 40" H20 to 30" H2O)?

-No changes were made to the system, blower is on "full".
-Draw was at 40" H2O at 5pm and had dropped to 30" H2O by 12am. It has stayed at 30" H2O since. (Draw reading comes from guage located just before the blower on the intake side.)
-Atmospheric changes were only slight.
-I don't think any air is entering the system... my methane concentration at the blower has risen as the draw/vacuum decreased.

Past experience shows me that as valves to the wells are closed, the draw/vacuum increases... ???therefore as pipes on the intake become clogged/blocked my draw/vacuum should increase????
... and through past experience, as valves to the wells are opened, the draw decreases... ???therefore as pipes become puntured or joints leak my draw/vacuum should decrease???

Again, what would cause a decrease in draw/vacuum other than a hole on the intake piping system? If my outlet piping was clogged, would the draw/vacuum decrease???

Any help, advice, pointers will be appreciated.

Thanks,

Justin

[bradjmx4]

Atmospheric pressure

[flange]

pretend you were sucking on a straw and you had your finger over the other end. you'd be sucking real hard to fill your lungs right? now remove your finger partially, you can breathe much easier right?

[dmedley]

review your dry gas laws. charles,boyles,grahms etc...
as you remove the methane from the ground you should see a deeper vacum as you remove the gas. however if your vaccum is less you could be either clogged or the trash could be producing more methane depending on the composition of the content within the seal. if all the pipes are reading the same vaccum drop...more methane.if only a couple depending on thier location.... clogged.

[traneman1]

hey I know you !

[DrFreeze2000]

I was exposed to this about 15 yr ago working on blower/vac system for Lucayan Utilities in Freeport, Bahammas. I had trouble setting loads on the pumps and did not understand why and when I asked was given the following explanation; Different density of methane gas will occur depending on concentrations. Hence the higher density of methane the harder it is to pump.

Don't know if this helps, but was interesting when I dealt with it.

The system I dealt with used weights on a diapragm operated bypass to control pump load.