FLUID FLOW FOR CHEMICAL ENGINEERING

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1 EKC FLUID FLOW FOR CHEMICL ENGINEERING CHTER 8 (SOLUTION WI EXERCISE): TRNSORTTION SYSTEM & FLUID METERING Dr Mohd zmier hmad Tel: +60 (4) chazmier@eng.sm.my

2 . Benzene at 7.8 o C is pmped throgh the system of Fig. at the rate of 0.0 m /min. The reseroir is at atmospheric pressre. The gage pressre at the end of the discharge line is 45 kn/m. The discharge is 4.48m & the pmp sction.m aboe the leel in the reseroir. The discharge line is 0.5-in. Schedle 40 pipe. The friction in the sction line is known to be 5.45 kn/m & that in the discharge line is 7.9 kn/m. The mechanical efficiency of the pmp is 0.75 (75%). The density of benzene is 865 kg/m, and its apor pressre at 7.8 o C is 6. kn/m. Fig.

3 Calclate (a) Deeloped head of the pmp; (b) Total power inpt. (c) If the pmp manfactrer specifies a reqired NSH of.05 m, will the pmp be sitable for this serice? nswer: a) The pstream station a is at the datm height. V a Z ', a' 0 The elocity at point a is negligible becase of the larger diameter of the tank in comparison with that of the pipe. V b is fond from ppendix 5. For a 0.5 in Sch. 40 pipe, a elocity of ft/s (0.048 m/s) corresponds to a flowrate of gal/min (.578x0 - m /min), V b 0.0m.578x0 / min m / min Χ 0.048m / s.0m / s

4 lso b.0 (trblent) mp work, W p is fond sing Bernolli Eqation. W η p b ' + ρ gz g b' ( ) c b' V + g c b' + h f a ' ρ Χ 0 N / m.0 W p η + (9.8N / kg)(4.48m) + 865kg / m () ( ) Χ kg / m N / m 0.Χ0 N / m 865kg / m 48.87mN / kg ΔH b) The mass flow rate is. m ρ (865 kg/m ) (0.0 m /min) (min/60s) 0.7 kg/s The power inpt is : B m Δ H (0.7)(48.87).5W η 0.75

5 c) Use Eq. 8.7 for NSH p i 0.x0 N / m 7. J / kg ρ 865kg / m NSH g g c p i p ρ h fs Z a Vapor pressre correspond to a head, p 6. x0 N / m 0. J / ρ 865 kg / m kg The friction in the sction line, 5.45 x0 N / m h fs 6. J / kg 865 kg / m The ale of NSH, NSH ( ). 6. m The aailable NSH is considered smaller than the minimm reqired ale of 6.5m, so the pmp is not sitable for the proposed serice.

6 . Gie 4 considerations for pipe selection. nswer: (i) Costs of piping (ii) ower (iii) Maintenance (i) ipe stocking () ipe fittings. What type of joining is needed if the pipes hae : (i) thick wall (ii) thin wall and (iii) pipe of brittle materials nswer: Thick-walled : screwed fittings by flanges or welding Thin-walled : by soldering or compression fittings ipe of brittle materials (carbon or cast iron): by flanges

7 4. Sketch the schematic diagram of (a) orifice meter, (b) entri meter and (c) pitot tbe. nswer: (a) orifice meter (b) entri meter. (c) pitot tbe

8 5. Sketch types of ale plgs with their characteristics. nswer:

9 6. Sketch (i) direct acting and (ii) reerse acting of actator. nswer:

10 7. ositie displacement pmp force the liqid by (i). It can be classified into two general categories; (ii).and (iii) nswer : (i)changing olme (ii)reciprocating pmp (iii)rotary pmp 8. (i), (ii). and (iii) are examples of reciprocating pmp. nswer : iston pmp, plnger pmp and diaphragm pmp

11 9. Centrifgal pmp adds momentm to the flid by means of. nswer: Fast moing blades (centrifgal force) 0. ower lost in the pmp are de to the (i), (ii), (iii) and (i) nswer :. Flid friction which reslt from the mechanical energy conersion into the form of heat.. Leakage which redces the olme of the discharge.. Disk friction occrs between the oter srface of the impeller & the liqid within the casing. 4. Bearing losses occr from the mechanical friction in the bearing & stffing boxes of the pmp.

12 Δ + Δ F W d Z g d (8.9) introdcing correction factor, 0,, ΔZ F W. Show that from continity eqation, the flid pass oer the entri meter can be expressed as: D gh C G ρ nswer: From continity eqation:- constant, is flowrate mass G ρ ρ G (8.0) Where is specific olme (ρ - ) incompressible flid, For ( ) (8.) ( ) ---- (8.) Sbstitte (8.) into (8.9)

13 ( ) G Sbstitte (8.) into (8.0) (8.) Introdcing coefficient of discharge, C D to eliminate &. ( ) C G D ( ) D C G ( ) D C G ( ) D gh C G ρ ρ D gh C G ρ

14 . entri meter of 0 mm diameter at inlet and 85 mm diameter at the throat is sed for measring the flow of water. If the pressre drop at conergence is 60 mmh O and water mass flowrate is.8 kg/s, what is the discharge coefficient at conergence part of entri meter. nswer: π ( 0x0 ) 0. m π ( 85x0 ) 5.67x0 m Sbstitte all ales into Eq. 8.7; C ρ D G gh.8 C (000)(0.0804)( ) D x (9.8)(60x ( 5.67x0 ) ) C D 0.8

15 4. Water is flowing at a elocity of 0.0 m/s in a pipe of 0.5 m in diameter. In the pipe, there is an orifice with a hole diameter of 0.5 m. What is the measred pressre drop across the orifice? μ water x0 - kg/ms; ρ water 000 kg/m. nswer: For incompressible flid, / (0.0)(0.5) /(0.5) m/s Calclating N Re to determine the coefficient of orifice; d ρ (0.5)(0.0556)(000) Re μ x0 840 From the chart, the corresponding C D at β 0.5 is Sbstitte in the Eq.8., Δ ρ (000)(0.0556) 4 4 ( β ) ( 0.6 ).8 kg/ms C D (0.65)

16 5. ir at a density of.5 kg/m is flowing throgh a pitot tbe. The pressre difference gage indicates a difference of 4 kg/ms. What is the air elocity? nswer ( ) ρ ( 4) 4.9m /.5 6. (i)., (ii) and (iii).. are sed for transportation of gases. nswer: Fan, blower, compressor s

EDEXCEL NATIONAL CERTIFICATE/DIPLOMA. PRINCIPLES AND APPLICATIONS of FLUID MECHANICS UNIT 13 NQF LEVEL 3 OUTCOME 3 - HYDRODYNAMICS

EDEXCEL NATIONAL CERTIFICATE/DIPLOMA PRINCIPLES AND APPLICATIONS of FLUID MECHANICS UNIT 3 NQF LEVEL 3 OUTCOME 3 - HYDRODYNAMICS TUTORIAL - PIPE FLOW CONTENT Be able to determine the parameters of pipeline