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- I started by running some tests on the flocculator program used last semester to try to get an idea of what general range the baffle spacings should be in. I am trying to follow the guideline that Gavg should go from 75 s^-1 to 45 s^-1 to 15 s^-1. These guidelines were created for a flocculator with a depth of 3 m and a b of 45 cm, so L/b is approximately 7. Since our L/b ratio (1.4m/20cm) is also close to 7, this guideline is applicable. The Gavg values for tank A should be about 75 s^-1 .
- I then edited a program that we created in CEE 454 (fall '07) which allows the user to specify the baffle spacing. This program needed to be changed slightly to allow for multiple baffle spacings. This program outputs the ideal number of baffles, the G and G¿ values, the water height throughout the flocculator, a graph of Gmax vs. G¿, and draws a picture of the flocculator.
- I edited Monroe's floc design program since the original program uses G¿ to determine the baffle spacing. Since the first part of the G¿ vs G curve is relatively flat so it might be more reasonable base the baffle spacing G.
- I calculated the total G¿ for all four tanks to make sure it is large enough
- I calculated the force on the first baffle due to the water coming out of the pipe. Its max value is 30 N, and this would only occur if all the water from the pipe directly hit the baffle, which is not the case. Based on this value, it was determined that a surge chamber is NOT necessary.
- The spacing above or below a baffle is supposed to be 1.5b. It is a little more complicated to maintain this distance since the slope is sloped. However, for ease of construction I still decided that it would be best to keep the length of the baffles uniform throughout this section. The spacing above and below with increase slightly through the tank, however the slope is fairly gradual so this increase should not pose a problem to the effectiveness of the flocculator.
- the first baffle spacing will be between 18cm and 20cm. This is the area between the pipe and the first baffle.
Design
Tank | Baffle spacing | No. of baffles | Gmax | Gavg | G¿ | baffle length |
|---|---|---|---|---|---|---|
A | 20 cm | 6 | 176.8 s^-1 | 65.3 s^-1 | 3652 | 110 cm |
A | 23 cm | 8 | 133.7 s^-1 | 52.8 s^-1 | 4534 | 105.5 cm |
A | 28 cm | 8 | 90.2 s^-1 | 39.3 s^-1 | 4102 | 98 cm |
B | 34 cm | 1 | 61.18 s^-1 | 29.319 s^-1 | 465 | |
B | 40 cm | 11? | 53.974 s^-1 | 26.675 s^-1 | 4950 | |
C | 73.35 cm | 1 | 13.855 s^-1 | 9.58 s^-1 | 319 | |
C | 55.25 cm | 3 | 26.72 s^-1 | 15.707 s^-1 | 1130 | |
C | 58.4 cm | 3 | 23.726 s^-1 | 14.363 s^-1 | 1096 | |
D | 60 cm | 1 | 20.953 s^-1 | 13.08 s^-1 | 354 | |
D | 70 cm | 5 | 16.139 s^-1 | 10.746 s^-1 | 1658 | |
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| sum: | 22260 |
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