For Problem 23.32, determine whether it is more economical to use the two-stage ejector with intermediate condensation than the noncondensing option given in Example 23.11, Part (b). Use the following information:

To account correctly for the time value of money, you should divide the costs of the exchanger and vessel by a factor of 5 to convert the one-time cost ($) to an equivalent yearly cost ($/y).

Problem 23.32

For Example 23.11, Part (b), rework the problem for the case when the stream leaving the first stage of the ejector is condensed using cooling water (in at 30°C and out at 40°C) with a 5°C approach (leaves the condenser at 45°C). What is the reduction in steam flow to the second stage of the condenser?

You will have to set this problem up and solve it using a process simulator; you should use ideal gas and latent heat enthalpy options.

Example 23.11

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Overall heat transfer coefficient for the partial condenser = 1500W/m²K Cost of steam Cost of cooling water = $15 x 10-6/kg (for AT = 10°C) Cost of heat exchanger = $30,000 40.43 where A = heat exchanger surface area in (m) Cost of L-Vseparator = 20%of cost of heat exchanger = $0.03/kg