kath1
Civil/Environmental
- Feb 27, 2006
- 1
Soil vapor extraction:
A 250 scfm blower operating at a vacuum of 6" of Hg with a 8.9 hp motor is proposed for a SVE system extracting Total Petroleum Hydrocarbons from a site where there has been a gasoline release.
Scenario A: extracting vapors from sand/gravel unit.
Scenario B: extracting vapors from a silty/sand unit.
Questions:
1) Do blowers/fans apply a vacuum or does the amount of vacuum observed/measured at the wellhead or manifold depend on the formation it is sucking from (e.g. Scenario A, Scenario B)?
2) How does motor hp, rpm of the blower's lobes/blades and the vacuum (in. of Hg) rated for the blower - relate to one another?
3) What variables are dependent on the other(s)? Performance curves show flow rates on the x axis and vacuum in (in of Hg) on the y axis. Does this mean that vacuum is dependent on flow rate? Or is the flow rate dependent on the vacuum achieved?
4)What can the operator vary when running a blower? Is varying the size of the motor (e.g. increasing the hp) the only way to see an increase in the rpm of the blower blades/lobes, thereby resulting in an increase in the flow rate at the blower's inlet?
5) Onion Enterprise paper - has the conversion formula from SCFM to ACFM as follows:
ACFM = SCFM*[(Ps-(RHs*PVs))]/[(Pb-(RHs*PVs))]*[(Ta*Pb/Ts*Pa)]
Where:
Ps = Standard pressure (PSIA)
Pb = Barometric Pressure (PSIA)
Pa = Actual Pressure (PSIA)
RHs = Standard Relative Humidity
RHA = Actual Relative Humidity
PVs = Saturated Vapor pressure of water @Ts
PVa = Saturated vapor pressure of water @Ta
Ts = Saturated temperature(degrees R) R= degrees F +460
Ta = Actual Temperature
Question: What is Pa? Is Pa (the actual pressure in a sucking system) equal to the difference between the barometric pressure (Pb) and the observed or measured vacuum)whereby the observed vacuum would be equal to the applied vacuum of the blower subtract the head losses (due to pipe friction?
Therefore, the formula would be:
Pa = Pb - observed or measured vacuum
Pa = Pb - (applied vacuum - head losses)
5) If a schematic was drawn of a blower with conveyance piping to a well head and then piping down the well to a screened interval (screened interval could consist of slotted PVC piping) - Assume the blower is operating at sea level and the vacuum is measured along various points (e.g. the blower inlet (P1); at the well head (P2); at the top of well screen (P3); and if it could be measured, and at some point away from well out in formation (P4)- what vacuums would you observe for the above scenarios (i.e. is P1's vacuum greater than P2's and P2's greater than P3's and P3's vaccum greater than P4's)? Given that fluid will flow from regions of higher applied positive pressure to regions of lower applied positive pressure. Would the pressure (if it could be measured) out in the formation approximate the atmospheric pressure (e.g. vacuum is negligible)and as you move towards the well (e.g from some point out in the formation to a point at top of well screen elevation to point at top of well head to point at inlet of the blower) the vacuum measured increases?
Where would one measure the greatest vacuum/greatest suction (in inches of Hg,for instance)- P1 at the inlet of the blower? P2 at the wellhead? P3 at the top of the screen interval in the well? or P4 is at a point in the formation some distance away from the well? Intuitively I'd think the higest observed or measured vacuum would be at the inlet of the blower because when you measure vacuums in observations wells some distance from an extraction well to determine the extraction well's radius of influence- we find that the vacuums measured become less and less the further we move away from the extraction well (this is generally true so long as the screened interval in the observation wells are compatible with the screened interval of the extraction well (e.g. at same depth and in the same lithological unit) Help, Help, Help!!!
A 250 scfm blower operating at a vacuum of 6" of Hg with a 8.9 hp motor is proposed for a SVE system extracting Total Petroleum Hydrocarbons from a site where there has been a gasoline release.
Scenario A: extracting vapors from sand/gravel unit.
Scenario B: extracting vapors from a silty/sand unit.
Questions:
1) Do blowers/fans apply a vacuum or does the amount of vacuum observed/measured at the wellhead or manifold depend on the formation it is sucking from (e.g. Scenario A, Scenario B)?
2) How does motor hp, rpm of the blower's lobes/blades and the vacuum (in. of Hg) rated for the blower - relate to one another?
3) What variables are dependent on the other(s)? Performance curves show flow rates on the x axis and vacuum in (in of Hg) on the y axis. Does this mean that vacuum is dependent on flow rate? Or is the flow rate dependent on the vacuum achieved?
4)What can the operator vary when running a blower? Is varying the size of the motor (e.g. increasing the hp) the only way to see an increase in the rpm of the blower blades/lobes, thereby resulting in an increase in the flow rate at the blower's inlet?
5) Onion Enterprise paper - has the conversion formula from SCFM to ACFM as follows:
ACFM = SCFM*[(Ps-(RHs*PVs))]/[(Pb-(RHs*PVs))]*[(Ta*Pb/Ts*Pa)]
Where:
Ps = Standard pressure (PSIA)
Pb = Barometric Pressure (PSIA)
Pa = Actual Pressure (PSIA)
RHs = Standard Relative Humidity
RHA = Actual Relative Humidity
PVs = Saturated Vapor pressure of water @Ts
PVa = Saturated vapor pressure of water @Ta
Ts = Saturated temperature(degrees R) R= degrees F +460
Ta = Actual Temperature
Question: What is Pa? Is Pa (the actual pressure in a sucking system) equal to the difference between the barometric pressure (Pb) and the observed or measured vacuum)whereby the observed vacuum would be equal to the applied vacuum of the blower subtract the head losses (due to pipe friction?
Therefore, the formula would be:
Pa = Pb - observed or measured vacuum
Pa = Pb - (applied vacuum - head losses)
5) If a schematic was drawn of a blower with conveyance piping to a well head and then piping down the well to a screened interval (screened interval could consist of slotted PVC piping) - Assume the blower is operating at sea level and the vacuum is measured along various points (e.g. the blower inlet (P1); at the well head (P2); at the top of well screen (P3); and if it could be measured, and at some point away from well out in formation (P4)- what vacuums would you observe for the above scenarios (i.e. is P1's vacuum greater than P2's and P2's greater than P3's and P3's vaccum greater than P4's)? Given that fluid will flow from regions of higher applied positive pressure to regions of lower applied positive pressure. Would the pressure (if it could be measured) out in the formation approximate the atmospheric pressure (e.g. vacuum is negligible)and as you move towards the well (e.g from some point out in the formation to a point at top of well screen elevation to point at top of well head to point at inlet of the blower) the vacuum measured increases?
Where would one measure the greatest vacuum/greatest suction (in inches of Hg,for instance)- P1 at the inlet of the blower? P2 at the wellhead? P3 at the top of the screen interval in the well? or P4 is at a point in the formation some distance away from the well? Intuitively I'd think the higest observed or measured vacuum would be at the inlet of the blower because when you measure vacuums in observations wells some distance from an extraction well to determine the extraction well's radius of influence- we find that the vacuums measured become less and less the further we move away from the extraction well (this is generally true so long as the screened interval in the observation wells are compatible with the screened interval of the extraction well (e.g. at same depth and in the same lithological unit) Help, Help, Help!!!
