For most valves, the change in velocity of the fluid flow is negligible. Apply this principle
to solve the following problems. (10 pts total)
a. A pressure gage on a high-pressure steam line reads 80 bar absolute. A small
quantity of steam is bled out through a valve to atmospheric pressure at 1 bar. A
thermocouple placed in the bleed stream reads 400°C. What is the temperature
inside the high-pressure line?
b. Steam traps are common process devices used on the lowest points of steam
lines to remove condensate. By using a steam trap, a chemical process can be
supplied with so-called "dry" steam, i.e. steam free of condensate. As
condensate forms due to heat losses in the supply piping, the liquid runs
downward to the trap. As liquid accumulates in the steam trap, it causes a float
mechanism to move. The float mechanisms is attached to a valve, and when the
float reaches a control level, the valve opens to release accumulated liquid, then
closes automatically as the float returns to the control levels. Most steam traps
are constructed in such a way that the inlet of the steam trap valve is always
covered with saturated liquid when opened or closed. Consider such a steam
trap on a 7 bar(absolute) line that vents to 1 bar (absolute). What is the quality
of the stream that exits the steam trap at 1 bar?
Fig: 1