Vent Dust To Atmosphere???? 1

[DoctorBond]

Dear All,

I am trying to decide whether it is possiable to vent 2.5Kg/day of titanium Oxide to atmosphere, or whether this must be collected??? According to UK legislation, 2.5 Kg could be vented to atmosphere if it would be in a concentration of less than it Occupational Exposure Limit (1 Kg/100,000 m3 air).

So in other words it sounds like in order to be allowed to vent to atmoshere, the dust must disperse in more than 250,000 m3 air per day.

So how can i calculate this???? Any ideas??? Anything will be usefull. Many Thanks.

 

[vintage70]

DB

In the US we calculate the maximum allowable stack concentration (MASC) from the hazard limiting value (HLV), e.g., for an 8-hr period it's 300 ug/m^3.

Depending on the height of the discharge point:

20 meters or less, (0.885HLV (X+ 1.08V(0)[0.64])[1.56]/V(0)

V(0) = actual flow rate in m^3/sec

X = 10 meters or distance from discharge point to property But there are other dispersion models out there in air pollution textbooks.

If the stack height is >20 meters the equation is modified slightly.line which ever is greater.

Now this is a USEPA model which may not be applicable for you.

Let me know I will post it. Another way is to monitor the air. What does you regulatory agency require or accept?

Vin

 

[DoctorBond]

Hiya Vin, Thanks for your reply

I tried looking up MASC in an environmental engineering textbook to get a better angle on it, but so far have come up with nothing. Could you breifly explain what is is exactly???

In the uk, the only legislation I can find on the subject is simply that "discharge to atmopshere is permissable, if the particualate can be discharged in a safe concentration (which for TiO2 is 10mg/m3).

I presume based on your equation i would end up with a number (what are the units of the calculation by the way???) which would basically be either higher or lower than the 10 mg/m3.

I am assuming that provided the answer (the MASC) is less than 10 mg/m3, then discharge to atmosphere would be permissable. Am I right???

Luke (aka Dr.Bond)

 

[vintage70]

Luke,

The USEPA establishes the exposure limit. That is the HLV for an 8-hr or 30-hr period, which is the the concentration in the surrounding air. The EPA allows us to calculate based on the height of the discharge point or stack the allowable concentration in the exhaust gas called the MASC maximum allowable stack concentration. This makes it easier to calculate the concentration in your exhaust using say mass balance or liquid/vapor equations. In your case you know the discharge rate convert that to ug/m^3, the result of the equation I posted is in ug/m^3. If the 10 mg/m^3 is the exposure limit use that as the HLV in the equation see what MASC concentration you get. Compare that to the 2.5Kg/day that you converted to a stack concentration. Hopefully you're under. Don't forget though this is a USEPA method that may not apply in the UK. I would suggest asking the regulatory agency if they have a mathematical model, They may have a method or show them this one.

Keep me informed
I'll help as much as I can
Vin