Comparision Of Vfd Operated Pumping System.pdf

..

COMPARISON OF VFD OPERATED PUMPING SYSTEM (Pumps working in parallel with one VFD driven pump Vs All VFD driven pumps for TLF loading gantry)

•'

Comparison of VFD operated pumping systems for Meerut Terminal MECON LTD. ,DELHI

CONTENTS

Chapters

Description

Page No.

1

Introduction

1

2

Pump selection & Q vs H Curve

1-3

3

Pump Sequential operation

4-5

4

Case Study

6-7

5

CAPEX & OPEX

7

6

Summary of comparison

8

7

Recommendation

8

REV

DATE

01

23.08.2018

00

30.05.2018

-

Prepared By

Checked By

Approved By

Ashish Kumar,

Sheshram Patel, S.D.E(O&G)

T.K.Mondal

APE (O&G)

AGM (O&G)

Comparison of VFD operated pumping systems For Meerut Terminal MECON LTD.,DELHI

HPCL 1. Introduction:

A Variable Frequency Drive (VFD) is a motor controller that drives an electric motor by varying the frequency and voltage supplied to the electric motor. Frequency (or hertz) is directly related to the motor's speed (RPM). In other words, the faster the frequency, the faster the RPM go. If an application does not require an electric motor to run at full speed, the VFD can be used to ramp down the frequency and voltage to meet the requirements of the electric motors load. As the application's motor speed requirements change, the VFD can simply turn up or down the motor speed to meet the speed requirement. 1.1 Affinity laws: The affinity laws state that the flow is proportional to impeller speed at a specific point on the pump curve. Head and NPSH are proportional to the square of the speed, while the power is a cubical function of the speed. The hydraulic (pump) efficiency remains constant when the speed is reduced. Flow is proportional to shaft speed 01/02 = N1/N2 Pressure or Head is proportional to the square of shaft speed: H1/H2 = (N1/N2)2 3) Power is proportional to the cube of shaft speed: P1/P2 = (N1/N2)3 1.2 Pumping with variable frequency drives can be separated into three cases. Constant pressure - Variable flow (CE-VF)— To keep pressure relatively constant over range of flow. Constant flow - Variable pressure (CF -VS — To keep varying pressure to keep flow constant. c) Variable pressure — Variable flow(VP-VF) — To keep variable flow & variable pressure. For applications like truck filling gantry the system is designed to supply a wide range of flows Cn-V, pressure at some constant pressure (static discharge head of pump) & is considered booster system. This document will provide a comparison for "pumps working in parallel with one VFD driven pump" & "all VFD driven pumps working in parallel" for truck filling gantry application. 2. Pump selection & Q Vs H Curve: As per OISD-244, to avoid wide variation in pressure leading to hammering in headers it is necessary to choose pumps with flat characteristics curves. 1) 6 Nos. of pumps each of 5200 LPM flow (P1, P-2 & P-3, P-4, P-5 & P-6) are considered for 20 Nos. of HSD Loading points through 16" Header.. Flow requirement shall be: 20 X 2000 X 0.70 (Diversity factor) = 28000 LPM

2018 Mecon Ltd. All rights reserved.



Page 1 of 8

Comparison of VFD operated pumping systems For Meerut Terminal MECON LTD.,DELHI

HPCL

The system requires a constant head of 40 Mtrs (i.e. static discharge head), however friction head will be dynamic & will depend upon variable flow (nos. of loading points working) Pump selected is 5283 LPM (rated flow) & 54 mtrs. head. Power required at rated condition is 60.35KW. NPSH required at rated condition is 160 mtrs. Head required against different flow conditions have been listed in table below.

Flow requirement Sr. No.

Head required (mtrs.)

LPM

m3/hr

1

2000

120

40.35

2

4000

240

41.21

3

6000

360

41.98

4

8000

480

42.59

5

10000

600

43.34

6

12000

720

44.23

7

14000

840

45.24

8

16000

960

46.38

9

18000

1080

47.66

10

20000

1200

49.05

11

22000

1320

50.57

12

24000

1440

52.21

13

26000

1560

52.97

14

28000

1680

53.86

© 2018 Mecon Ltd. All rights reserved.



Page 2 of 8

2.1 Pump curve at various RPM (Fig-1.1 below)

Q VS H@ Various RPM for 5200 1pm HSD pumps

,--

10

JO

IO

,.

'"'

,

.

, Flow{m"hr)

.

,

..

Comparison of

VFD

operated pumping systems for Meerut Terminal

HPCL

MECON LTD.,DELHI

3.0

Pump Sequential operation :

3.1

Case 1- Pumps P-1, P-2, P-3, P-4 ,

P-5 &

P-6 are in parallel

&

only pump P-1 is VFD driven.

One pump (P-1) will be running with VFD and other five pumps (P-2, P-3, P-4, P-5 & P-6) shall have soft starter. The VFD will regulate the speed of only one pump. All the six pump sequential working & power demand shall be as per the table below:

Loading points operating (Nos.)

2

2000 4000

3 4

6000 8000

5 6

10000 12000

7 8 _ 9

14000

1

.

Flow requirement (LPM)

10 11 12 13 14

•

16000

- 18000

20000

22000 24000 26000 28000

Pump actual flow for Sequential operation(m3/hr) P-1 (VFD)

P-2

P-3

P-4

P-5

P-6

134.14 243.23 367.68

0 0 0

0

0 0

0

0

0 0

0

0

0

475.00 138.99

0 450

0 0

0 0

0

0 0 0

288.18 381.82 112.37

450 450 425

0 0 425

232.32 400.00 188.89 350.00

425 400

153.54

425 400 375 350 350

0 0 0 0 0 375 150 350

120.58

317

375

350 350 317

317

0 0 0 0

0 0 0 0 350 317

0

0 0 0 0 0 0 0 0 317

Total (actual)

Total Flow required (m3/hr)

134.14 243.23

120 240

367.68 475.00

360 480

588.99 738.18

600

831.82 962.37 1082.32 1200.00 1313.89 1400.00

720 840 960 1080 1200 1320 1440

Head Required (mtrs.)

Shaft Power required (Kw) P-1 (VFD)

P-2

P-3

P-4

P-5

P-6

38.68

0 0

0 0

0 0

0 0

0 0

0 0

0 0 0

0 0 0

0

0 0

0

0

0 0 0

0 0 0

0 0 0

0 0 0 0

40.35 41.21 41.98

24.75 53.59

0

42.59

77.00

0

43.34 44.23 45.24 46.38 47.66

27.53 45.34 60.01

75 75 75 72 72

1553.54

1560

49.05 50.57 52.21 52.97

1705.58

1680

53.86

27.61 43.34 69.00 40.44 62.50 37.11 34.11

69 64 62.5 62.50 60.35

0 0 0 72 72 69 64 62.5 62.5 60.35

0 0 0 64 62.5 62.5 60.35

62.5 60.35

0 0

60.35

© 2018 Mecon Ltd. All rights reserved. Page 4 of 8

•

Comparison of VFD operated pumping systems for Meerut Terminal HPCL

MECON LTD.,DELHI

3.2 Case 2 - Pumps P-1, P-2, P-3, P-4 , The pump sequential working i

Loading points operating (Nos.) 1 _ 2 _...3 4 5

Flow requirement (LPM) _

&

P-5 &

P-6 are in parallel

&

all the pumps are VFD driven.

power demand shall be as per the table below:

Pump actual flow for Sequential operation(m3/hr P-1 (VFD)

P-2 (VFD)

P-3 (VFD)

P-4 (VFD)

P-5 (VFD)

Total Flow required

Head Required (mtrs.)

P-6 (VFD)

Total (actual)

120.0

40.35

(m3/hr)

Shaft Power required (Kw) P-1

P-2

P-3

P-4

P-5

P-6

(VFD)

(VFD)

(VFD)

(VFD)

(VFD)

(VFD)

24.8

0.0

0.0

0.0

0.0

0.0

2000

134.1

0.0

0.0

0.0

0.0

0.0

134.1

4000

243.2

0.0

0.0

0.0

0.0

0.0

243.2

240.0

41.21

38.7

0.0

0.0

0.0

0.0

0.0

6000

367.7

0.0

0.0

0.0

0.0

0.0

367.7

360.0

41.98

53.6

0.0

0.0

0.0

0.0

0.0

8000

475.0

0.0

0.0

0.0

0.0

0.0

475.0

480.0

42.59

0.0

0.0

319.9

0.0

0.0

0.0

0.0

639.9

600.0

43.34

47.7

0.0

0.0

0.0 0.0

0.0

319.9

77.0 47.7

0.0

10000

58.1

58.1

0.0

0.0

0.0

0.0

0.0

6

12000

377.8

377.8

0.0

0.0

0.0

0.0

755.6

720.0

44.23

7

14000

291.4

291.4

291.4

0.0

0.0

0.0

874.2

840.0

45.24

46.9

46.9

46.9

0.0

0.0

0.0

46.38

52.7

52.7

52.7

0.0

0.0

0.0

47.66

50.0

50.0

50.0

50.0

0.0

0.0

53.3

53.3

53.3

0.0

0.0

8

16000

330.6

330.6

330.6

0.0

0.0

0.0

991.7

960.0

9

18000

297.8

297.8

297.8

297.8

0.0

0.0

1191.2

1080.0

10

20000

304.2

304.2

304.2

304.2

0.0

0.0

1216.8

1200.0

49.05

53.3

11

22000

270.1

270.1

270.1

270.1

270.1

0.0

1350.5

1320.0

50.57

53.0

53.0

53.0

53.0

53.0

0.0

274.3

274.3

274.3

0.0

1371.7

1440.0

52.21

55.5

55.5

55.5

55.5

55.5

0.0

254.7 278.6

254.7

254.7

254.7

1528.5

1560.0

52.97

53.6

53.6

53.6

53.6

53.6

53.6

278.6

278.6

278.6

1671.5

1680.0

53.86

58.1

58.1

58.1

58.1

58.1

58.1

12

24000

274.3

274.3

13

26000

254.7

254.7

14

28000

278.6

278.6

Note Similar sequence in reverse manner will be followed for case-1

&

2 when loading demand falls from 14 loading points to one loading point.

(t) 2018 Mecon Ltd. All rights reserved. Page 5 of 8

4.0 Case Study: Following have been considereD for working out CAPEX & OPEX for VFD driven pumps for HSD system at Terminal: 1) Assumed per day throughput of HSD is 672 KUday 2) Considered effective loading hours per day shall be 5 hours (1 shift). 3) Considered average tank trucks of capacity to be filled will be of 12 KL & average filling time of 30 minutes. 4)

No. of trucks to be filled simultaneously per hour= 672/(5*12)= 56 Truck per Shift or 11.2 tanker trucks per hour.

5) Considering irst hour as peak hour, no. of loading points wcrking will be 8. i.e. 8 X 2= 16 Nos HSD tanker trucks.. 6)

For next 4 hours no. of loading points working shall be 5 per hours. i.e. 5 X 2= 10 Nos HSD tank trucks per hour. Hence total no. of trucks filled will be 10 X 4= 40

4.1 Power requirement for above cases shal be as per table below: •

Case 1- Pumps P-1, P-2. P-3. P-4. P-5 & P-6 are in parallel & only pump P-1 is VFD driven.

Loading point (Nos.)

Flow required (LPM)

5 8

Pump actual flow for Sequential operation(m3/hr)

Shaft power required(Kw)

P-1 (VFD)

P-2

P-3

P-4 toP-6

P-1 (VFD)

P-2

P-3

P-4 to P-6

10000

138.99

450

0

0

75

0

112.37

425

425

0

16000

27.53

72

72

0

27.61

I

0

Total power required per day Shaft Power required (Kw) Loading Points (Nos.)

I

5

P-2

P-3

P-4to P-6

27.53

75

0

0

27.61

72

72

0

P-1

(VFD)

Motor Power required (Kw)

Op. hours

Total Motor

Kw

I

Total (KwH) I

P-2

P-3

P-4to P-6

39.32

80.21

0

0

4

119.54

478.15

39.44

77

77

0

1

193.44

193.44

Total

671.15

P-1

(VFD)



L.=

Comparison of VFD operated pumping systems for Meerut Terminal MECON LTD. ,DELHI

HPCL

Case 2 - Pumps P-1, P-2, P-3, P-4 & P-5 are in parallel & all the pumps are VFD driven.

•

Pump actual flow for Flow Loading Sequential operation(m3/hr) requirement point P-3 P-1 I P-2 (LPM) (Nos.) (VFD) (VFD) I (VFD) 10000 16000

5 8

319.95 330.56

319.95 330.56

Shaft Power required(Kw) P-1 (VFD)

P-2 (VFD)

P-3 (VFD)

0

47.74

330.56

52.65

47.74 52.65

0 , 52.65

Total power required per day Shaft Power required(KW) Loadin g points (Nos.)

(VFD)

P-2

P-3

i

5

47.74

47.74

0

8

52.6

52.6

52.6 I

P-4 to p ..6 0

Motor Power required(KW) . P-4 P-2 P-3 : to (VFD) P-6 0 I 0 52 52 57.2

0

57.2

57.2

Op. hours

Total Motor KW

Total (KwH)

4

104

416

171.6

171.6

Total

587.69

5.0 CAPEX & OPEX : 5.1 Capital Expenditure Tentative Cost of both the cases is as under: Case: 1 - One VFD + Soft starter (1 VFD Panel + 6 Soft starters) - INR 27 Lakh. Case: 2 - All pumps with VFD (6 Nos. VFD panel) - INR 30 Lakh 5.2 Operating expenditure As considered in above two cases Sr. No

Cost savings Power Consumption (KWH)

Case-1 671.15

Case-11 587.69

INR 4495.82 INR 5134.29 Price (INR) @ 7.65 INR per KWH 13,48,748.55 INR 15,40,289.25 Opex for 1 year (300 working 3. days) " Savings per day for multiple VFD pump ng system w.r.t to single VFD pumping system will be 83 KWh (units) i.e, INR 639 for HSD loading as considered in case study. *** Savings peryear shall be INR 1, 91,541.25 for HSD loading as considered in case study.

Cc) 2018 Mecon Ltd. All rights reserved.



Page 7 of 8

6.0 Summary of comparison: Sr. No.

I

Basis

1.

Flow& head requirement

2.

Power consumption

3.

Operating & capital cost

II

l

Pumping system with single VFD driven pump

Multiple VFD pumping system with all VFD driven pump

The head rise above static head within the flow range is nearly 14 mtrs., and a very small change in RPM will lead to wide variation in flow.

Pump operation allow a wide range of control for variable flow.

More power consumed by the pumping system for same operating parameters.

Less power consumed by the pumping system for same operating parameters.

•

•

CAPEX: INR 30 Lakhs (Approx)

•

OPEX: INR 13,48,748 per year

•

CAPEX : INR 27 Lakhs (Approx) OPEX: INR 15,40,289.25 per year

7.0 Recommendation: As the results obtained indicate that more power is consumed by pumping system operated with single VFD as compared to all VFD driven pumps for the cases considered & capital cost of single VFD driven pumping system w.r.t multiple VFD driven pumping system have marginal difference, it is recommended to install all VFD driven pumps for TLF gantry loading operation atTerminal.