December 2, 2020

4-12.

Turpentine density = 55 lbm/ft3

a. Compute the total volume spilled by the change in liquid level:

b. Determine the maximum spill rate from Equation 4-12:

c. Use Equation 4-18 to determine the time required for the level to drop to 13 ft above

the bottom.

15 ft

13 ft

17.9 ft

7 ft

Leak, 0.1 in diam.

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Substituting:

Solve for t with units of seconds. There are two roots:

4-13. The best approach is to use the steam tables for an isenthalpic flash.

Solve for the fraction flashed by mass:

At the initial conditions.

The quantity flashed is then:

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If we use Equation 4-87 instead,

We can also use Equation 4-91,

From the steam tables

Substituting into Equation 4-91:

This is close to the other values.

4-14. a. The pipe is threaded into the tank. If the pipe breaks off, it usually breaks off just

b. Use Equation 4-12:

Substituting into Equation 4-12:

c. Need to determine the total volume of the vessel.

Then the total draining time, assuming a constant draining rate, is:

d. For a pool on the floor of 1-cm depth,

The area of the pool is then,

e. Use Equation 3-12,

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f. Use Equation 3-9 or Equation 3-14.

Substituting into Equation 3-9,

4-15.

1

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Then it is seen that:

The mechanical energy balance then reduces to:

The various terms are:

The friction term must consider entrance, pipe friction and exit effects. It is given by,

From Equation 4-39,

Substituting,

c

Re 2

g

Returning to the ME balance above,

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PROCEDURE:

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4-20. This is a complicated problem involving a mechanical energy balance. For part a the

velocity can be determined and the solution is direct. However, part b is trial and error

since the velocity is not known.

The geometry for this problem is shown below:

For the crude oil:

The final height of oil in the destination vessel, if all oil transferred, is:

a. The required pipe velocity to move all the oil in 1 hour is:

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We need to size the pump for the worst case pumping situation. In this case, the

b. A 100 HP pump is 74.57 kW. The spreadsheet solution is shown below. All the

c. The conclusion is that this is not a viable method for emergency transfer of liquid

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4-17. a. From a mechanical energy balance for incompressible flow:

The maximum velocity will occur if: a) the pressure drop across the pump is small, b)

no change in height, and c) no friction. Then the ME balance reduces to:

But

Then,

Solving for u,

b. 50 mm diameter = 0.05 m

Substituting into the equation:

The mass flow is: