The original cost for a distillation tower is $24,000 and the useful life of the tower is estimated to be 8 years. The sinking-fund method for determining the rate of depreciation is used (see Example 5), and the effective annual interest rate for the depreciation fund is 6 percent. If the scrap value of the distillation tower is $4000, determine the asset value (i.e., total book value of equipment) at the end of 5 years.

Example 5

Estimation of filtering area required for a plate-and-frame filtration operation. A plate-and-frame filter press is to be used for removing the solid material from a slurry containing 5 lb of dry solids per cubic foot of solid-free liquid. The viscosity of the liquid is 1 centipoise, and the filter must deliver at least 400 ft3 of solid-free filtrate over a continuous operating time of 2 h when the pressure-difference driving force over the filter unit is constant at 25 psi. On the basis of the following data obtained in a small plate-and-frame filter press, estimate the total area of filtering surface required.
Experimental data: The following data were obtained in a plate-and-frame filter press with a total filtering area of 8 ft2:

The slurry (with filter aid) was identical to that which is to be used in the large filter. The filtrate obtained was free of solid, and a negligible amount of liquid was retained in the cake.