27451913-Storage-Tank-Design

Pamantasan ng Lungsod ng Maynila College of Engineering and Technology Chemical Engineering Department

WATER STORAGE TANK Design Description: Bulk storage of liquids is generally handled by closed tanks to prevent escape of volatile and contamination. In some instances, such as water storage, where contamination and dilution are not a factor, large reservoirs can be employed. Natural terrain, concrete-walled excavations, or concrete tanks are the typical construction. Reinforced-wall design is required and the concrete must be waterproofed with a suitable paint to prevent any possibility of leaking. Design Selection: This tank is selected to supply the water needed by the spray washer, reactor (degumming machine), the sink – and – float tank and, hot washing tank Design Considerations: 1)

Capacity of the tank

2)

Type of material being handled

3)

Classification of tank to be used

4)

Material of construction

Data and Assumptions: 1)

The amount of water stored in the tank is 2952.77 kg H2O.

2)

The tank is vented for an easy flow of water.

3)

Assume H= 4/3 D, since this is a common ratio used for tank designs.

4)

Allowance of 20% as safety factor is used.

Design Requirements: 1) 2)

Volume of the tank

3)

Height and diameter of the tank

Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


4)

Working pressure

5)

Shell thickness

6)

Head thickness

7)

Depth of the head

8)

Volume of the head

9)

Surface area of the head

10)

Bottom thickness

Design Calculations: The density and the mass of the water are as follows: ρH2O=1000 kg/m3 mH2O=2952.77 kg H2O

Therefore the volume of the tank is, VH2O=2952.77 kg H2O1000 kg/m3 VH2O=2.95 m3

Basis: per batch of operation 1)

Volume of the tank

Calculating for the volume of water in the tank and assuming 20% allowance as safety factor, Vtank=VH2O(1.20) Vtank=3.54 m3

Use 3.60 m3 water storage tank. 2)

Height and diameter

To compute for the standard ration of the water storage, assume H=4/3 D, Vtank=π4D2H

But, H=4/3 D Therefore, the diameter and height of the tank are: Vtank=π3D3 3.54=π3D3 D=1.50 m 4.92 ft;H=2.00 m (6.57 ft)



Use 1.60 m and 2.00 m for diameter and height, respectively. 3)

Working pressure

Ptotal=Poptimum+Hρ

Since the tank is vented, Poptimum= 14.7 psi, and H=2.00m (6.57 ft) Therefore, Ptotal=14.7lbsin2+6.57ftft2144 in262.4 lbsft3 Ptotal=17.55 psi

Use 18 psi as working pressure. Plate Design: 4)

Shell thickness

For shell thickness, use Eqn. 4-3, Process Equipment Design by Hesse and Rushton, p. 85, ts=PD+C2Se-P

Where: S = ultimate tensile strength P = maximum allowable working pressure D = diameter C = allowance for corrosion e = efficiency To find the maximum allowable tensile strength, use Eqn. 4-1 of Process Equipment Design by Hesse and Rushton, p. 84, S=Su×Fa×Fr×Fs×Fm

Where: Su = ultimate tensile strength Fa = radiograph factor Fr = stress relieving factor Fs = ultimate strength factor Fm = material factor Thus, Su = 13000 psi

(for low-carbon nickel steel, PED, p.69)



Fs = 25%

(Table 4-2, PED, p.84)

Fm = 1.00

(for high tensile strength carbon steel, PED, p.81)

Fr = 1.00 Fa = 1.00

(if stress relieving, radiographing is not required,

PED, p.88) Substituting to the equation of maximum allowable tensile strength, S = 13,000 x 1.00 x 1.00 x 1.00 x 0.25 = 3250 psi For double-butt joint, e = 0.80

(based on material factor, PED, p.89)

For corrosion allowance, C = 1/16 in

(Plant

Design

and

Economics

for

Chemical

Engineering by Peters, p. 542) Substituting to the equation, ts=PD+C2Se-P ts=17.55 lbs/in26.57ft12 inft+1/16 in23,250lbsin20.80-17.55lbsin2 ts=0.27 in ≈6.78 mm

Use 7 mm shell thickness of the tank 5)

Head thickness

For thickness of head: A standard dished head was chosen for simplicity and availability th=Plw2Se

Refer to Eqn. 4-6, p.86, PED Since:

Di = 1.50m (59.04 in)

Do=Di+2ts Do=59.58 in

From PED, p.69 Crown radiusL=Di-6 (in in.) L=53.04 in kr=knuckle radius=0.06 Do kr=3.57 in

Calculating the ratio, R = kr/L Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


R=0.07

For the value of W, from table 4-3, p.87, PED W=1.80

With S = 3250 psi, as calculated previously, the value of the head thickness, using the equation 4-6 of PED, th=PLW2Se th=0.32 in ≈8.18 mm

Use 9 mm as head thickness. 6)

Depth of the head (h):

From Eqn. 4-14, p. 92, PED, h=L-L2-D24 h=53.04-53.042-59.0424 h=8.97 in ≈0.23 m

Use 0.30 m as the head depth of the tank. 7)

Volume of the head (V):

From Eqn. 4-15, p.92, PED, V=1.05h23L-h (all values in inches)

Substituting the previously computed values to the above equation would give, V=12685.26 in3≈0.21 m3

Use 0.30 m3 as volume of the head. 8)

Surface area of the head (A):

From Eqn. 4-16, p.92, PED, A=6.28 hL A=2987.83 in2≈1.93 m2

Use 2.00 m2 for surface area of the tank. 9)

Bottom thickness:



The same values and calculation of thickness of head were done on thickness of bottom, since thead = tbottom. Hence, tbottom = 8.18 mm (9 mm).



SODIUM HYDROXIDE TANK Design Description: Bulk storage of liquids is generally handled by closed tanks to prevent escape of volatile and contamination. Reinforced-wall design is required and the concrete must be waterproofed with a suitable paint to prevent any possibility of leaking. Desin Selection: Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


This tank is selected to store and supply the sodium hydroxide needed in the alkaline sorbing (degumming) process. Design Considerations: 1)

Capacity of the tank

2)


3)

Classification of tank to be used



4)

Material of construction

5)

Quantity of material moved per unit time


The tank is closed to avoid contamination of the NaOH solution.

2)

Density of sodium hydroxide is 2100 kg/m3

3)

Assume H= 4/3 D, since this is a common ratio used for tank designs.



4)

Allowance of 20% as safety factor is used.

5)

Mass of NaOH is 93.60 kg (refer to the material balance)

Design Requirements: 1) 2)

Volume of the tank

3)

Height and diameter of the tank



4)

Working pressure

5)

Shell thickness

6)

Head thickness

7)

Depth of the head

8)

Volume of the head

9)

Surface area of the head

10)

Bottom thickness



Design Calculations: The density and the mass of the sodium hydroxide are as follows: ρNaOH=(2100kgm3) mNaOH=93.60 kg

Therefore the volume of the tank is, VNaOH=93.60 kg 2100 kg/m3 Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


VNaOH=0.04 m3

Basis: five days of operation (15 batches) 1)

Volume of the tank

Calculating for the volume of water in the tank and assuming 20% allowance as safety factor, Vtank=VNaOH1.2(15 batches ) Vtank=0.79 m3 Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


Use 0.8 m3 water storage tank. 2)

Height and diameter

To compute for the standard ration of the water storage, assume H=4/3 D, Vtank=π4D2H

But, H=4/3 D Therefore, the diameter and height of the tank are: Vtank=π3D3 Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


0.79=π3D3 D=0.91 m 2.99 ft;H=1.21 m (3.98 ft)

Use 1.0 m and 1.30 m for the diameter and height of the storage tank, respectively. 3)

Working pressure

Ptotal=Poptimum+Hρ

Since the tank is not vented, Poptimum= 14.7, and H=1.21 m ( 3.98 ft) Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


Therefore, Ptotal=14.7+3.98ftft2144 in2130.92 lbsft3 Ptotal=18.32 psi

Use 19 psi as working pressure. Plate Design: 4.) Shell thickness



For shell thickness, use Eqn. 4-3, Process Equipment Design by Hesse and Rushton, p. 85, ts=PD+C2Se-P

Where: S = ultimate tensile strength P = maximum allowable working pressure D = diameter Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


C = allowance for corrosion e = efficiency To find the maximum allowable tensile strength, use Eqn. 4-1 of Process Equipment Design by Hesse and Rushton, p. 84, S=Su×Fa×Fr×Fs×Fm

Where: Su = ultimate tensile strength Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


Fa = radiograph factor Fr = stress relieving factor Fs = ultimate strength factor Fm = material factor Thus, Su = 9000 psi

(for Stainless steel type 304, Timmerhaus)

Fs = 25%

(Table 4-2, PED, p.84)



Fm = 1.00

(for high tensile strength carbon steel, PED, p.81)

Fr = 1.00 Fa = 1.00

(if stress relieving, radiographing is not required,

PED, p.88) Substituting to the equation of maximum allowable tensile strength, S = 9000 x 1.00 x 1.00 x 1.00 x 0.25 = 2250 psi For double-butt joint, Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


e = 0.80

(based on material factor, PED, p.89)

For corrosion allowance, C = 1/16 in

(Plant Design and Economics for Chemical

Engineering by Peters, p. 542) Substituting to the equation, ts=PD+C2Se-P ts=18.32 psi(35.88 in)+1/16 in22250lbsin20.80-18.32 psi Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


ts=0.18 in ≈4.66 mm

Use 5 mm shell thickness of the tank. 5.) Head thickness: For thickness of head: A standard dished head was chosen for simplicity and availability th=Plw2Se

Refer to Eqn. 4-6, p.86, PED Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


Since:

Di = 0.91 m (35.88 in)

Do=Di+2ts Do=36.24 in

From PED, p.69 Crown radiusL=Di-6 (in in.) L=29.88 in kr=knuckle radius=0.06 Do Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


kr=2.17 in

Calculating the ratio, R = kr/L R=0.07

For the value of W, from table 4-3, p.87, PED W=1.80

With S = 2250 psi, as calculated previously, the value of the head thickness, using the equation 4-6 of PED, Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


th=PLW2Se th=0.27 in ≈6.95 mm

Use 7 mm as head thickness. 1)

Depth of the head (h):

From Eqn. 4-14, p. 92, PED, h=L-L2-D24 Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


h=29.88-(29.88)2-35.8824 h=5.99 in ≈0.15m

Use 0.2 m as the head depth of the tank. 2)

Volume of the head (V):

From Eqn. 4-15, p.92, PED, V=1.05h23L-h (all values in inches) Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


Substituting the previously computed values to the above equation would give, V=3151.44 in3= 0.05 m3

Use 0.1 m3 as volume of the head. 3)

Surface area of the head (A):

From Eqn. 4-16, p.92, PED, Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


A=6.28 hL A=1124.00 in2=0.73m2



Use 0.80 m2 as the surface area of the head. 4)

Bottom thickness: The same values and calculation of thickness of head were done on

thickness of bottom, since thead = tbottom. Hence, tbottom = 6.97 mm (7 mm).



BELT CONVEYOR WITH SPRAY WASHER Design Description: Belt conveyor, as the name suggests, consists of endless belts, suitably supported and driven, which carry or transport solids from place to Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


place. Belts are made of canvas, reinforced rubber or balata and strip steel. Strip steel is employed for conveying materials through furnaces. Belt conveyors are adapted to wide varieties and quantities of materials; require relatively low power and can transport solids for a long distance. The width of the belt varies from 14 to 16 in, and the number of idlers varies correspondingly. This spacing ranges from about 5 feet for narrow belts



down to 3 feet for the widest belts. This conveyor is designed with a built-in spray washer. Design Selection: The belt conveyor is selected to transport the water hyacinth stalks to the pressing equipment. It is designed with built – in spray washer to wash the stalks at the same time they are being conveyed. Design Considerations: Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


1)

Capacity of the belt conveyor

2)

Length of travel/length of the belt

3)


4)

Speed of the conveyor

5)

Number of spray nozzles


Capacity based from material balance is 968.80 kg



2)

Normal speed range of belt conveyor is between 200 to 400 ft/min (from Unit Operations by Brown, p. 55) 3)

4)

Ratio of feed to wash water is 1:2

The belt width is 36 in (3 ft) (from Perry’s Chemical Engineering Handbook section 21-10 5)

The spray washer has 9 nozzles



6)

The lump size of feed is 18 in for 36 in width belt conveyor (Unit Operations by Brown, p. 58)

7)

The safety factor for belt conveyor is 15 % (Timmerhaus, p. 36) Design Requirements: 1)

Capacity of spray nozzles

2)

Capacity of belt conveyor

3)

Power requirement



Design Computations: From material balance: Inlet capacity is 968.80 kg/batch of water hyacinth stalks 1) Capacity of spray nozzle: V=MD

Where:

M= mass of water D = density of water



Since water to feed ratio is 2:1, M=2(968.80 kg) M=1937.60 kg H2O D=1000 kg/m3 V= 1.94 m39 nozzles V= 0.22m3nozzle

Use 0.30 m3 of water per spray nozzle for washing. Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


2) Capacity of the belt conveyor (T) T=968.80 kgbatch×1 batch8 hours×2.2lbskg×1 ton2000 lbs T=0.13tonhr 266.42kghr

Giving an allowance factor of 15%, for future expansion, T=0.13tonhr(1.15) T=0.15tonhr 305.90kghr Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


Use 310 kg/hr as belt conveyor capacity. 3) Power requirement Using equations for power requirement (Unit Operations by Brown, p.58) for plain bearings, Hp=FL+LoT+0.03WS+T∆z990

Where:

Hp = horsepower required F=

friction factor, 0.05 for plain bearings



L=

length of conveyor between terminal pulleys, ft.

Lo = 100 for plain bearings S=

speed of belt, fpm

T=

capacity of belt conveyor, ton/hr

∆z = increase in elevation of material, ft W = mass of moving parts including belts and idlers per foot distance centers of terminal pulleys (both runs), lbs Spinning of Alkaline Sorbed Fibers from Eichhornia Crassipes (Water Hyacinth) Stalks and Extruded Polyethylene Terephthalate (PET) Bottles for the Production of Textile Yarn


Computing for W, From table 16, Unit Operations by Brown, p.58 Approximate weight of belt conveyors = 1.0 lb/in of width per running foot W=1lbin-ft36 in(2 runs) W=72lbsft



Assuming L = 30 ft, since the length of the conveyor should be greater than the length of the spray washer, Hp=0.0530ft+1000.15tonhr+0.0372lbsft200 ftmin +(0)0.15990 Hp=2.84 hp

Use 3 Hp since it is commercially available.


27451913-Storage-Tank-Design

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