ข้อสอบสามัญเครื่องกล Pump 3/2548

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1 5 (Pump / Fan / Compressor) 2/2548

6 5 20 1. 20

(X) (20 )1.1 (Centrifugal Type) (Impeller)

. (Diffuser type)

. Vertical Turbine. Screw Pump. Mixed Flow

1.2 (Special Type) 3 Jet Pump, Air-Lift Pump Hydraulic Ram Air-Lift Pump

. Venturi

. .

. ..

1.3

. Air Chamber. Pressure Relief Valve. Air Inlet-Relief Valve. Surge Suppressor

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1.4 150 / TDH 5 TDH 80% 85% (Whp) (Bhp)

. whp = 10 hp , Bhp = 12.5 hp. whp = 12.5 hp , Bhp = 15 hp. whp = 7.12 hp , Bhp = 9.49 hp. whp = 9.57 hp , Bhp = 13.5 hp

1.5 4 . 8.5 kw. 10.9 kw. 12.5 kw. 14 kw

1.6 4 . 64%

. 66%. 68%. 70%

1.7

. Suction lift NPSHa

. . NPSH .

1.8 . . .

.

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1.9 (Priming). . 2 . .

1.10 . (TDH) = (Total Static Head) + (Friction

Head)

. hf = f (D/L) (V2/2g). Whp = (Q TDH)/273. hL = K (V

2/2g)

1.11 . .

. . 2 /

1.12 . (Check Valve). (Butterfly - Valve)

. (Ball Valve). (Globe Valve)

1.13 (Belled-type Intake) . . . .

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1.14 . (Semi-open Impeller). Mixed Flow. Paper-stock Impeller. Radial Flow

1.15 (Cavitation) Axial flow

. . (Suction lift) NPSHa. .

1.16 . (Gear Pump). (Reciprocating Pump)

. Hydraulic Ram.

1.17 Centrifugal . . 90 4

.

. 1.18

.

. 6 .

.

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1.19 . (Suction lift) . . .

1.20 .

. . .

1. . Screw Pump2. .

..

3. . Air Chamber4. . whp = 10 hp , Bhp = 12.5 hp

Q = 150 l/s

Q = (1503600)/1000 = 540 m3/hr

Whp = (QTDH)273 = (5405)273 = 9.89

Whp = 10 Bhp = Whp/Bhp = 10/0.80 = 12.5

5. . 10.9 kwkw = 0.746 Bhp/kw = (0.74612.5)0.85

kw = 10.97 kw

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6. . 68% =

= 0.800.85

= 0.68

= 68%

7. . Suction lift NPSHa8. . 9. . 10. . hf = f (D/L) (V2/2g)11. .

12. . (Globe Valve)13. . 14. . Paper-stock Impeller15. . 16. . (Reciprocating Pump)17. . 90 4

18. . 19. . 20. .

2. 2 1 (20 )2.1 (.)

1. 2.

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(.) 100 / 300 . 1,500 Hazen Williams C 100

(.) 100 / 300 . 1,500

Hazen Williams C

100Q = 100 /D = 300 .

Q = 3.578 10-6 CD2.63 S0.54

S0.54

= 100/[3.587 10-6

100 (300)2.63

]

S0.54

= 1/11.737 = 0.0852 = 8.52 10-2

hf/L = 8.52 10-2

hf = 8.52 10-2 1,500 = 127.8 = 127.8

(.)

1. 2. (Coupling) 3. 4.

5. NPSHa

(Vortex)

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1.

20%

2. 2.2 (.) 10

(.) 2000 180 (Bhp) 90 2,200 Bhp 1,500

(.) 2,000 180 (Bhp)

90 2,200 Bhp 1,500

Q1/Q2 = N1/N2

Q1 = (1,500/2,200) 2,000 = 1,364 gpm

H1/H

2= (N

1/N

2)

2

H1 = (1,500/2,200)2 180

H1 = 83.7

Bhp1/Bhp

2= (N

1/N

2)

3

Bhp1 = (1500/2200)3

90

Bhp1 = 28.52 hp

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(.) 10 1. 2. 3. (Suction Lift) 4. 5. 6. (Viscosity) 7. 8. (Air Pocket) 9. NPSHa NPSHr10. 11.

3. (Q ) 15,000 (A

2) 0.5

(Ps 2

, Static Pressure) 6 (in WG)

(F) 70%

1.1 (V2) (2 )

1.2 (pV2

,Dynamic Pressure) (4 )1.3 (p

t2

, Total Pressure) (4 )

1.4 (pt) (4 )

1.5 (Pf) (4 )1.6 (P) (2 )

, = 1.2 kg/m3 , w = 1,000 kg/m3

, atm = 101 kPa g = 9.81 m/s2

1,2 =

(20 )

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4. (20 )

Centrifugal Fan;Backward Blade

Centrifugal Fan;

Radial Blade

Centrifugal Fan;

Forward Blade

Axial Flow Fan

1.

2 1 X X

2.

1 2 X X

3.

2 3 1 4

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1 2, 3, 4 X

()1. Radial Blade

Backward Blade Radial Blade Forward Blade Axial Flow Head Overload

2. Backward Blade

Radial Blade Forward Blade Axial Flow Unstable

3. Forward Head

*Note ()

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5. 20 (X) (20 )

5.1 . . .

. 5.2 Standard Air

. ASTM 68F : 14.7 psia : 36%

. Compressed Air Institute 60F : 24.7 psia ()

. Natural Gas Pipeline Industry

24.7 psia : .

5.3 . Actual Capacity . Volumetric Efficiency

. Compression Efficiency

. 5.4 1 2

Vcompressor

= V.N.n. . 1

Vcompressor = nNL4

d2

. 2

Vcompressor (Vth) L/min m

3/hr

d

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L N (rpm)n

.

.

.

. 5.5

. . .

. 5.6

. . . .

5.7 . 1 kgf/cm2.

10 . .

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5.8 . .

.

.

5.9 . (Reciprocating Compressors). (Rotary Screw Compressors). (Centrifugal Compressors).

5.10 . ,

. . .

5.11 (Crank case). , (capbolt), (lock nut) .

. . ,

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5.12 ( (Aftercooler)). (Air vale)

. ,

.

.

5.13 . , (Inlet-Outlet Valve)

, , . (Intercooler)

. , .

5.14 . . . .

5.15 . , , -

. , ,

grand packing. (Intercooler) , Unloader (

(unload))

.

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5.16 . , . . , -,

.

5.17

. . (Automatic Condensate Trap)

(Inter cooler) (After cooler). (Intercooler).

5.18 3,000 5,000 3 6

. , , , . , , , . , , , .

5.19 3 . , , , . , , ,

. , , , .

5.20 . 3% . 5% . 7%

. 10%

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5.1 .

1. (Discharge Pressure)2. (Pressure Rise)3. (Compression Ratio)4. (Clearance) (

) 5.

5.2 . ASTM 68F : 14.7psia : 36%

Standard Air1. ASTM 68F : 14.7

psia : 36%2. Compressed Air Institute

60F : 14.7 psia ()3. Natural Gas Pipeline Industry

14.7 psia :

5.3 . Volumetric Efficiency

1) Actual Capacity

2) Volumetric Efficiency

3) Compression Efficiency

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5.4 .

5.5 . 1.

2. 3. 4.

5.6 . 1.

2. 3.

5.7 . 1 kgf/cm2 1. 1

kgf/cm2

2.

1 3.

4. 5.

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5.8 . 1.

2.

3.

5.9 . (Rotary Screw Compressors)

5.10 . ,

1. ,

2. ,

3. 5.11 . , (capbolt) (lock nut)

(Crank case) , (Capbolt), (lock nut)

5.12 . (Air vale)

1. (Air vale)

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2. (Cylinder jaket),

5.13 . , (Inlet-Outlet Valve) , ,

1. , (Inlet-Outlet Valve) , ,

2. (Intercooler)

3. , 5.14 .

1. 2.

5.15 .

1. , , -

2. , , grand packing

3. (Intercooler), Unloader( (unload)).

5.16 . , -, 1. , -

, 2.

5.17 . 1.

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2. (AutomaticCondensate Trap) (Intercooler) (After cooler)

3. (Intercooler)4.

5.18 . , , , 1. -

2. - ,

3. - 4. - packing

5.19 . , , , 1. -

2. (crankshaft) - 3. - 4. -

5.20 . 5% 5%

25 30% 5%

6. (20 )6.1 6.2 6.3 6.4 25 m3/min 7 bar

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VR =oP

gP

PoCoA

+

Pg = P

O=

CO = m3/min (FAD)

A = A = 1.5 A

3

30 m3/min 6 bar

t =)C(VP

PV

odo

R

Vd = m3/mint = P = bar

6.1 1.

2. 3. 4.

6.2 2 1.

2. 6.3 3

3 1. (Reciprocating Compressors)

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2. (Rotary Compressors)3. (Centrifugal Compressors)

6.4 2 1.

2. 2

6.5 VR =oP

gP

PoCoA

+

Pg+Po = 7+1.013

= 8.013 bar

VR =8.013

1.013253

VR = 9.5 m3

9.5 m3

t =)C(VP

PV

odo

R

VR 9.5 m3

P 7-6 = 1 bar PO 1.013 bar Vd 30 m

3/min

CO 25 m3/min

t =

25)-(301.013

19.5

= 1.9

over load 5 m3/min 1.9

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ข้อสอบสามัญเครื่องกล Pump 3/2548