Principle and Design of Spray Aerators: The system consist more spray nozzles, which are connected in a pipe, similarly many set of pipes are well connected like square, circle and rectangle shaped form and those bunch of pipes finally links to common pipe manifold, that pipe grid located over an open-top tank
The water leaves each nozzle in a fine spray and falls through the surrounding air, creating a fountain affect, so simply it is called water fall type.
Spray aerators are usually efficient with respect to gas transfer such as carbon dioxide removal or oxygen addition
Normally spray aeration is successful in oxidizing iron and manganese and is successful in increasing the dissolved oxygen of the water.
but it has certain limitation to using the Spray aerators system
1. Generally it requires large installation area
2. It is difficult to operate freezing weather
3. Dust and polluted Area is not suitable.
4.Nozzle design is important in achieving optimum dispersion of water.
5.short exposure time between water and air, and requires high head.
Design of Spray Aerators
Exposure time for each drop from a spray aerator depends on its initial velocity and trajectory, Drop size and the resulting area-volume ratio, is a function of the dispersing action of the nozzle.
The initial velocity V of a drop emerging from an orifice or nozzle appears in the formula
V = Cv ? 2gh {if ? mark appear in your browser assume it is square root of }
and the discharge by the equation
V = CdA ? 2g
where h = total head on nozzles, ft
g = acceleration from gravity, ft/s2
A = area of opening, ft2
Cv = coefficient of velocity
Cd = coefficient of discharge (Cd = CvCc, where Cc is coefficient of contraction)
Coefficients of velocity, contraction, and discharge vary with the shape and other characteristics of the orifice or nozzle.
The size, number, and spacing of spray nozzles depend on the head of water being used, space available for aeration facilities, and interference between adjacent sprays
Interior and exterior corrosion can be serious problems in aerator piping, corrosion resistant materials should be used wherever possible.