Water Cooling with Air

The data on cooling water with air are usually presented in the literature as Ka values. In using this information the units should be checked very carefully. 

When cooling water with air in an adiabatic process, the Lewis relation applies reasonably well and equation (8-28) can be simplified. Assuming a thoroughly irrigated tower packing, aH = aM = ah, and application of the Lewis relation, the left-hand side of equation (8-28) can be written as... 

Equation (8-32) is the design equation for water-cooling towers. The integral corresponding to the number of transfer units, N/G, is evaluated numerically following the procedure illustrated in Chapter 5 for absorbers and strippers if the individual coefficients hL and ky are known. The equilibrium curve for cooling water with air at 1 atm is that shown in Figure 8.2. 

Figure 6-36. Typical capacity increases gained when a vacuum pump sealed with relatively cool water handles air saturated with water vapor. By permission, Nash Engineering Co.

Process temperatures below those attainable with cooling water or air are attained through refrigerants whose low temperatures are obtained by several means ... 

For pressure separations, the controlling factors are usually the first favorable and first unfavorable effects. The pressure is usually set at the lowest possible pressure that permits satisfactory condensation using cooling water or air. A satisfactory temperature approach between the coolant and distillate is normally 10 to 20T with cooling water, and 30 to 50°F with air. 

By recycling the diphenyl (5), its total production is minimized to the advantage of increased benzene production. The reactor effluent is cooled by exchange with feed followed by cooling water or air (6) and sent to the flash drum (7) where hydrogen-rich gas separates from the condensed liquid. The gas phase is compressed (8) and returned to the reactor as quench, recycle H2. 

Splitting the cooling step for ammonia condensation also offers advantages when the recycle gas is compressed together with the makeup gas. This applies especially at synthesis pressures above about 25 MPa (250 bar). At these pressures, a greater portion of the ammonia formed can be liquefied by cooling with cooling water or air (see Fig. 92 D). 

The power supply furnishes the electrical power necessary to generate the plasma. The power required ranges from 50 watts to 5000watts, depending on the size of the reactor. The larger generators are usually cooled, either with air or water. 

The turbine generator condenser is a surface-type, double-flow and single-pass with respect to cooling water, with lateral suction of the air-steam mixture. 

---