Tray aeration method

The tray aeration method is a simple, low-maintenance method of aeration that does not use forced air.19 Water is allowed to cascade through several layers of slat trays to increase the exposed surface area for contact with air (Figure 18.9). Tray aeration is capable of removing 10 to 90% of some VOCs, with a usual efficiency of between 40 and 60%.53 This method cannot be used where low effluent concentrations are required, but could be a cost-effective method for reducing a certain amount of VOC concentration prior to activated carbon treatment. 

There are many methods to introduce fresh air for air stripping, including diffused aeration, tray aerators, spray basins, and packed-towers methods. 

The second term takes into account the pressure drop through the aerated liquid over and around the dispenser correspond to the clear liquid height. This pressure drop has a relationship with the liquid height on a tray. The method, commonly used, defines an aeration factor p, such that. 

Klein [201] has developed the correlation based on published data of others (his citations) as shown in Figure 8-149. Because the method of aeration between sieve trays [205] and valve trays is different [201], the same aeration correlation cannot be used, because valve trays have lower... 

The classical Chinese method consists of inoculating steamed rice grains spread on big trays with a strain of Monascus anka and incubating in an aerated and temperature-controlled room for 20 days. In these types of cultures, moisture content, oxygen, and carbon dioxide levels in the gas environment, as well as cereal medium composition, are the most important parameters to conhol. 

The purpose of a tray is to mix vapor and liquid. This produces aerated liquid—or foam. The purpose of a reboiler is to produce vapor. In a circulating reboiler, the reboiler effluent flows up the riser as a froth. Of course, the flow from the bottom of the tower is going to be a clear liquid. Foam cannot be pumped. But there will always be some ratio of foam to clear liquid in the bottom of the tower, and we have no method of determining this ratio, or even the density of the foam. 

Pressure Drop. Since efficiency depends on hydraulic factors, a method will first be given for estimating pressure drop across a sieve tray. The total drop across the tray is taken as the sum of the drop through the holes plus the drop through the aerated mixture ... 

Methods for determining equilibrium stages for azeotropic distillation are the same as those discussed in Section 5.3. As indicated in Fig. 5.5-3, the distillation path may cross over into the two liquid phase legion, and one mast be cantious about the design of contacting equipaienl when this condition is present. Research has shown that with good aeration, conventional trays may be used when two liquid phases are present. ... 

Hydraulic head In the perforated region of the tray, the liquid is in the form of a froth. The equivalent depth of clear liquid is an estimate of that which would obtain if the froth collapsed. That is usually less than the height of the outlet weir, decreasing with increased gas rale. Some methods of estimating A use a specific aeration factor to describe this [87). In Eq. (6.38), which is the recommended relationship (49), the effect of the factor is included as a function of the variables... 

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