I have a water remediation stripper than was used to strip out 1,1,1-tricholorethane as well as dichloroethane and dichloroethene. For the past few years, though, it has been turned off. The original design of this is nowhere to be found, so I'm having to reconstruct the design from bits of data I can collect. The governing environmental authority is now requiring a restart, but at a different target flowrate than before the shutdown.
The flow rate before shutdown was approximately 50 gpm. I believe the original tower design had 120 gpm or so, which was likely changed to 50 gpm approximately a decade ago.
Now, the environmental authority is wanting to restart with a 8-15 gpm. To my mind, this presents some issues with mixing and channeling in the tower due to the extremely low flow. I have a few questions and concerns, detailed below:
First, some data on the stripper. The inlet concentrations in the liquid phase are dilute - in the 10-50 ug/L (ppb) range. The tower is a 3' OD with 3.5 LANPAC random packing, approximately 15' of packed height. The nozzle is a BETE Fog NC3096, with a flow of approximately 150 gpm at 20 psig and 64 gpm at 3 psig. The blower is unknown, but is a 1HP reverse blade blower. Likely air flow rate is in the 1,500 - 2,000 cfm range. Henry's constant, from NIST, for 1,1,1-TCE is 1.47*10^(-6)/bar.
Question 1
For stripping, is the equilibrium slope (the term "m" in EQN 14-28 in Perry's 7th Edition) simply the Henry's law constant? I.e. yi = H * xi?
Question 2
In the absence of experimental data, Perry's seems to rely on estimations of H(OL) from various sources. Would these references even be valid for such a low turndown case? In essense, 8-15 gpm will trickle out of the current nozzle in a stream and only distribute itself over a little bit of the packing, essentially channeling down the column and not contacting much of the air. Thus, my thinking is that any assumption of an L/G ratio will not be correct due to this channeling.
Question 3
If channeling in Q2 above is indeed an issue, would putting on a new spray nozzle to distribute the liquid across the full 3' be sufficient to treat this as a normal column calculation? If so, would contacting LanPac directly be the best way to estimate the HL (height of the liquid phase transfer unit)?
Ultimately I'm trying to figure out if we need to increase flow back to the original 50 gpm, change the spray nozzle to get good coverage, or get a new, smaller stripper tower.
The flow rate before shutdown was approximately 50 gpm. I believe the original tower design had 120 gpm or so, which was likely changed to 50 gpm approximately a decade ago.
Now, the environmental authority is wanting to restart with a 8-15 gpm. To my mind, this presents some issues with mixing and channeling in the tower due to the extremely low flow. I have a few questions and concerns, detailed below:
First, some data on the stripper. The inlet concentrations in the liquid phase are dilute - in the 10-50 ug/L (ppb) range. The tower is a 3' OD with 3.5 LANPAC random packing, approximately 15' of packed height. The nozzle is a BETE Fog NC3096, with a flow of approximately 150 gpm at 20 psig and 64 gpm at 3 psig. The blower is unknown, but is a 1HP reverse blade blower. Likely air flow rate is in the 1,500 - 2,000 cfm range. Henry's constant, from NIST, for 1,1,1-TCE is 1.47*10^(-6)/bar.
Question 1
For stripping, is the equilibrium slope (the term "m" in EQN 14-28 in Perry's 7th Edition) simply the Henry's law constant? I.e. yi = H * xi?
Question 2
In the absence of experimental data, Perry's seems to rely on estimations of H(OL) from various sources. Would these references even be valid for such a low turndown case? In essense, 8-15 gpm will trickle out of the current nozzle in a stream and only distribute itself over a little bit of the packing, essentially channeling down the column and not contacting much of the air. Thus, my thinking is that any assumption of an L/G ratio will not be correct due to this channeling.
Question 3
If channeling in Q2 above is indeed an issue, would putting on a new spray nozzle to distribute the liquid across the full 3' be sufficient to treat this as a normal column calculation? If so, would contacting LanPac directly be the best way to estimate the HL (height of the liquid phase transfer unit)?
Ultimately I'm trying to figure out if we need to increase flow back to the original 50 gpm, change the spray nozzle to get good coverage, or get a new, smaller stripper tower.
