Question

Three return steam lines in a chemical processing plant enter a collection tank operating at steady state at 1 bar. Steam enters inlet 1 with flow rate of 0.8 kg/s and quality of 0.9 . Steam enters inlet 2 with flow rate of 2 kg/s at 200⁰C. Steam enters inlet 3 with flow rate of 1.2 kg/s at 95⁰ C. Steam exits the tank at 1 bar. The rate of heat transfer from the collection tank is 40 kW. Neglecting kinetic and potential energy effects, determine for the steam exiting the tank a. the mass flow rate, in kg/s. b. the temperature, in ⁰C.

Answer 1

The mass flow rate of the steam exiting the collection tank is 4 kg/s, and the temperature of the steam is 114.25°C.

Step-by-step explanation:

To determine the mass flow rate and temperature of the steam exiting the collection tank, we need to apply the conservation of mass and energy principles.

a. Mass flow rate: Considering the conservation of mass, the mass flow rate of steam exiting the tank can be determined by summing up the mass flow rates of steam entering the tank at each inlet. Therefore, the mass flow rate is 0.8 kg/s + 2 kg/s + 1.2 kg/s = 4 kg/s.

b. Temperature: Assuming no heat transfer between the tank and the surroundings, the total energy entering the tank must equal the total energy exiting the tank. The heat transfer rate of 40 kW is equal to the sum of the enthalpy changes of steam entering and exiting the tank. We can calculate the temperature of the exiting steam using the energy equation. Solving for T gives: T = 200°C(2 kg/s) + 95°C(1.2 kg/s) + T_exit(4 kg/s) / 4 kg/s = 114.25°C.