Weirs, water temperature

To ensure practically no leakage, a leakage test is commonly conducted upon installation. In this test, the weep holes are plugged and the trays are filled with water to the top of the weir. The rate of fall of water level is then measvu ed. It has been recommended that this rate should not exceed 1 in per 20 minutes (48, 86, 257, 371, 409). If the leakage is not critical, a more liberal tolerance can be adopted (48). This test is not always conclusive, because a tray that leaks badly under test conditions may perform satisfactorily at the design temperature and vice versa. 

Steam ejectors Operability of steam ejectors is very sensitive to the stability in the motive fluid (steam) pressure. Prefer vacuum pumps to steam ejectors (H). Keep diameter of pipes = diameter of inlet and discharge flanges of ejectors. As the column overhead mass flowrate increases above design, so will the column overhead pressure and vice versa. Compression ratios per ejector 6 1 to 15 1. If inlet gas temperature < 0 °C or below the triple point of water (0.61 Pa) then add steam jacketing to cope with ice formation. Seal for the hot well submerge > 30 cm. The volume in the hotwell between the pipe and the overflow weir should be 1.5 times the volume in the down spout sealed. Replace any nozzles or diffusers where the area is > 7 % larger than design. 

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