storage tank, pumps, and pipings

7/30/2019 storage tank, pumps, and pipings

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Design Problem:

volumetric flowrate = 150 L/min

pipeline pressure = 100 psi

outlet pressure = atmospheric pressure

height of faucet = 3 ft

depth of water table = 17 ft

storage time, = 16 hours

liquid : clean water

Design Calculations:

Assume that the temperature of the water flowing through the pipes is 36C or 309.15 K, such that the density of the fluid is 55.07024012

kmol/m3

or 993.684 kg/m3

or 61.9036 lb/ft3

as calculated from constants for water and given equation for density calculation in Table 2-30 of

Perry, 7th

Edition.

The mass flowrate in 1000 lb/hr, W, of the fluid flowing through the pipes is determined.

1. Pipes, Tubing and FittingsThe typical diameter based on typical fluid velocity is calculated by Eq. 2-37 of handout. Thus,

*

The wall thickness of the pipe is indicated by the schedule number which is a function of internal pressure and allowable stress. From

Table 28-2 of Perry 7th

Edition, use Stainless Steel, austenitic 18Cr, 8Ni type for the material of construction of pipes from the pump

discharge up to the faucet. The allowable stress for this type of material at T 90m3, the tank should be field-erected.

Since VL > 10,000 gal, the tank should be vertically mounted on a concrete foundation.

Using API-650 for standards and from Table 2-10 of handout, Thus,


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Since the tank is never more than 90% filled:

a. Shell Thicknessi. One-Foot Thickness

Thickness of the Lower-Course:

Assume that the corrosion allowance is zero since the liquid to be used is clean water.

Since 0.04159944738 < 0.1875, use 0.1875 in. as the lower course thickness.

Thickness of the Upper-Course:

Assume that the corrosion allowance is zero since the liquid to be used is clean water.

* Since 0.01957621053 < 0.1875, use 0.1875 in. as the upper course thickness.

ii. Variable Point MethodThickness of the First Course

* *

Since 0.04601964546 < 0.1875, use 0.1875 in. as the lower course thickness.

Thickness of the Second Course

Since , thus,

where


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Comparing the computed values of x1, x2, and x3,it is apparent that x3is the minimum.

Second Iteration


Third Iteration


Thus, use 0.0434933548in as t2. However, since 0.0434933548 < 0.1875, use 0.1875 in as the upper course thickness.

iii. Tank ElevationSince liquid water is considered to be an incompressible fluid, use Eq. 2-23 of handout for the energy balance from the tank and

faucet.

* Considering the liquid surface of the storage tank as point 2 and the outlet of the faucet as point 1, the energy balance would

reduce to

*


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iv. Roof Design (Roof Thickness)

v. Stiffeners and Annular Plate

* *Thus, there is no need for stiffener. From Table 2-11 of handout, the minimum annular plate thickness is 0.25in since the

thickness of the lower course is 0.1875in. Use 0.25in as the annular plate thickness.

Since L should not be less than 24in, use 24 in for the length of annular plate.

3. PumpSince liquid water is considered to be an incompressible fluid, use Eq. 2-23 of handout for the energy balance from the surface of water in

the water table (pt.3) to the surface of the water in the storage tank (pt. 2). Refer to Figure 1.

*

* The pressure in point 2 is ambient. However, the pressure in point 2 is determined using the Boltzman equation with the assumption thatair is an ideal gas.

Then,

( )

From Eq. 2-26, the total fluid friction can be calculated by,

Consider pt. 4 to pt. 2. From Appendix C-2a, C-2c and C-2d (Foust, 1980),

For standard 90-elbow,

, thus,

For sharp-edged entrance, K=0.5, thus,

For sharp-edged exit, K=1.0, thus,


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To compute for the f, calculate the NRe of the fluid flowing through the pipe. The viscosity of the fluid at 36C or 96.8F, determined

through Appendix 14, p. 1102, McCabe, is interpolated to be 0.70824cp or 4.7593728x10-4

lb/ft-s.

From Appendix C-1, the ft for commercial steel pipes. Thus, From Appendix C-3, at

,

Consider pt. 5 to pt. 3. From Appendix C-2a, C-2c and C-2d (Foust, 1980),

For standard 90-elbow, , thus,

For sharp-edged entrance, K=0.5, thus,

For sharp-edged exit, K=1.0, thus,

To compute for the f, calculate the NRe of the fluid flowing through the pipe. The viscosity of the fluid at 36C or 96.8F, determined

through Appendix 14, p. 1102, McCabe, is interpolated to be 0.70824cp or 4.7593728x10-4

lb/ft-s.

From Appendix C-1, the ft for commercial steel pipes. Thus, From Appendix C-3, at

,

Thus, at a basis of 1hr operation,


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