W16-056_Rhys Forgie Questions
1. Could you please provide a mass balance for this design? We would like to see flow rates and concentrations of the contaminants (at a high-level is okay for now). a. Please keep in mind we should not need the hybrid cooling tower at all times in the year, such as winter. Will this solution still work when the cooling tower blowdown flow is absent? Could you please provide a mass balance for both scenarios? See appendix. I am currently out of the office with no access to AutoCAD so this is the cleanest way to present the mass balance I could think of. Please let me know if you’d like me to change the format. 2. Equipment all designed for our expected flow, ~30 gpm. Pump capacities are much higher at 50 gpm. Would these pieces of equipment work correctly with the lower flow as well (i.e. no cooling tower water)? The air-diaphragm pumps will work fine at lower flows. Other pumps such as centrifugal or positive displacement pumps will be difficult to maintain a prime on the line. However, we prefer air- diaphragm because they are very forgiving. We will also be sure to select pumps that can handle the temperature and pH of the wastewater streams. I’ve seen applications where pumps fail almost immediately. We obviously try to avoid this be any means possible. 3. Stage 2: OWS – Noted that RME/tar treatment will not be provided. This is okay for us since we intend to send the content of the RME holding tank to a burner. a. The char burner can accept biodiesel (RME) and tars with up to 5% water in this stream. Please confirm your design will be able to separate RME/tar with 5% or less water in the RME tank (i.e. how much water is collected in skimming?). In theory there should be no water in the oil skimming. If there is more than 5% water in the oil collection of the OWS then it is most likely being hydraulically overloaded. However, with the sizing we proposed it is extremely unlikely that this could happen. b. Will there be components expected in this tank other than RME/tar? The OWS will skim off the oil, but what will be skimmed off the top of the DAF and would this be miscible with the RME tank components? Yes. However, it will mostly be inorganic components that shouldn’t have drastic effect on chemical conditioning. I believe there is note in the RFP that there will be wash-down in the feed stream. This can be a high variable if they are anticipating introducing high/low pH streams, but otherwise shouldn’t be a major concern. 4. Stage 2: OWS – Noted that we will have to take care of disposing the solids collected in the solids holding tank, and likely this will require an additional filter press. a. What will this solid stream look like? Like a sludge or slurry? How much moisture should we expect? The solids stream will most likely be approximately 10% solids coming into the collection tank. It will look more like slurry than viscous sludge. In order to properly dewater it will most likely need to be dosed with a flocculant, which can be done in line to dewatering or in the conical solids holding tank.
b. Do you have a recommended vendor for the additional filter press?
If a filter press is the agreed solution we can easily integrate into our proposal to furnish one from our vendor Micronics. We have preferred pricing and a good relationship with this manufacturer and have furnished presses as part of an equipment package. We have
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