WATER STORAGE TANK

DESIGN DESCRIPTION

Water storage tanks are containers used to hold and store water

necessary to supply the required amount of water needed in the

production in the washing of raw materials and as a feed in sulfuric acid

dilution tank.

DESIGN SELECTION

The storage tank is a cylindrical tank and with a hemispherical head

and bottom to eliminate sharp corners or regions into which fluid currents

would not penetrate and due to less expensive to produce than spheres.

DATA AND ASSUMPTIONS

1. The capacity of the tank is for 1day operation

2. The mass of water needed in the spray washer and sulfuric dilution

tank is 22395.5985 kg/batch (based on material balance) and a

total of 67186.7955 kg per day operation

3. The density of water at 25C is 997.042 kg/m3 (Perry’s Chemical

Engineering Handbook 8th edition, sec 2-91)

DESIGN CONSIDERATION

1. The filing capacity is 80%

2. Safety factor of 20%

3. The efficiency of tap-welded joints is 80% (Plant Design and

Economics for Chemical Engineers, 5th ed, Peters and Timmerhaus,

pg. 555 Table 12-10)

4. The minimum corrosion allowance is 1/16 in (Process Equipment

Design, Hesse, pg 73)

5. The height to diameter ratio of the tank is 2 (Perry’s Chemical

Engineering, 7th ed. By Perry and Green, pg. 10-139)

6. A stainless steel type 301 materials of construction is used to avoid

negative effect of materials handled and for higher corrosion

resistance (Perry’s Chemical Engineering, 7th ed. 28-31)

7. The maximum allowable tensile stress for steel of temperature up

to 650F is 110000 psi (Process Equipment Design, Hesse, Table 3-3.

Pg 62)

DESIGN REQUIREMENTS

1. Capacity of the Tank

2. Tank Diameter

3. Tank Height

4. Thickness of the Shell

5. Head and Bottom Thickness

DESIGN CALCULATION

1. Capacity of the Tank

V t=67186.7955 kg/day997.042kg /m3

=67.38612m3

At filing capacity

V t=67.38612m3

0.80=84.23265m3

Safety factor

V t=84.23265m3 x 1.20=101.07918m3

2. Tank Diameter

Since H = 2D

V=2π3D3

101.07918m3=2π3D3

D = 3.64084 m

3. Total Tank Height

H t=2D

Since Height for head and bottom is D/2 (Based on 10-140, Table 10-65

Perry’s Chemical Engineering Handbook)

H hb=2×Dt2

=3.64084m

H total=(2 x3.64084m )+(3.64084m)=10.92252m

4. Shell Thickness

(Eq. 4-3, page 85, Process Equipment Design by Hesse)

Where:

= thickness of the plate

P = internal pressure

D = internal diameter

S = allowable working stress

e = efficiency

C = corrosion allowance

)

Su = 11000 psi (Table 3.1 Process Equipment Design page

60)

Fm = 1.00 for high tensile strength carbon steels

Fa = Fr = 1.00 since radiographing and stress relieving is not

required

Fs = 0.25 (Table 4.2, Process Equipment Design by Hesse,

page 84)

Internal Pressure:

Pi=10.92252mx 62.2449

lb

ft 3x3.2808 ft

( 144¿2

ft2 )=15.48973 psi

Pi=15.48973 psi

t s=¿¿

t s=0.56889∈¿14.44981mm

5. Head and Bottom Thickness

t s=PD4 Se

+C

(eq. 4-8 page 86, Process Equipment Design by Hesse for

hemispherical head and bottom)

t s=¿¿

t s=0.31480∈¿7.99592mm

DESIGN SPECIFICATION

WATER STORAGE TANK

Identification

Item: Water Storage Tank

Number of Required Units:

1

Materials handled:

Water

Function: To store water that would supply the required

amount of water for washing and for dilution of sulfuric acid

Materials of Construction:

Stainless Steel Type 301

Design Data

Parameters Proposed

Design

Existing Design

Capacity 101.1

m3

50 m3

Height of the Tank

10.9

m 5 m

Diameter of the Tank

3.7

m 2.44 m

Shell Thickness

14.5

mm

_

Head and Bottom Thickness

8 mm

_

Pressure Head 14.4

psi

_

Accessories

Cost P33,000.00

Source Preheat Engineering and Technical Services

Address 406-C D.Reyes Street

Pasay, Philippines Pasay

1300