Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 ·...

37
Cosimo Bianchini Gary Mirsky Mitch Frumkin Wind Screen effect on performance, before and after, and comparison with CFD

Transcript of Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 ·...

Page 1: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

Cosimo BianchiniGary Mirsky Mitch Frumkin

Wind Screen effect on performance, before and after,

and comparison with CFD

Page 2: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Gary Mirsky -

Objectives

• Find A Recent Installation

• Verify Reduction in Thermal Deficiency Predicted by CFD Analysis After Wind Screen Installation

• Detail Causes of Deficiency

• Present the Steps of the Structural Analysis

• Changes Required Due to Structural Analysis

• Aerial Photo of APEX 6 x 5

2

Page 3: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Gary Mirsky -

Our candidate for case study

• APEX Power Plant Owned by SCPPA

• LADWP is 100% Participant

• 2 GAS Turbines – Rated at 172 MW Each Gross

• 1 Steam Turbine – Rated at 230 MW Gross

• 531 Net MW

• In Service 2003• Photo Shows Obstructions Caused

by Cable Trays

3

Page 4: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Gary Mirsky -

ACC data• Forced draft A-frame type

– 6 streets per 5 rows

• Design point– Turbine exhaust steam flow 1450∙103 lbm/h– Turbine exhaust steam pressure 10 inHgA– Condensing heat load 1426 Mbtu/h

• 30 Howden fans– 34’ diameter– 5 fiberglass reinforced epoxy blades– 200 ft/s tip speed – 162 BHP power

• Balcke-Durr finned tube bundles– 10 bundles per module– 140 single pass oval finned tubes per bundle

4

Page 5: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Gary Mirsky -

Why were screens installed?

• Best ROI option• Photo Shows

Completed Windscreen Installation. Perimeter Screens Behind Cable Trays

5

Page 6: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Gary Mirsky -

Timeline

• Structural Analysis – Fall 2017

• ACC Cleaned – December 2017

• Screen Installation – Completed Feb. 22, 2018

• Rotor Upgrade – April 19 to June 10, 2018

• Very Narrow Window for Data Comparison

• Perimeter and Cruciform Screens

6

Page 7: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Gary Mirsky -

Presenters

• CFD Analysis– Dr. Cosimo Bianchini

Ergon Research

• Structural Analysis– Mitch Frumkin

P.E./PresidentKipcon Engineering

• Photo of Cruciform Screens

7

Page 8: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

Ergon ResearchVia Campani 50 Firenze

Air Cooled Condenser Users Group 2018Colorado Springs

Presenter:

Cosimo Bianchini

Wind screen effects on performance

Page 9: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Highlights

• Analysis of PI Data: overall improvement in plant production of nearly 10%

– Difficult to discern single contributions

• The aerothermal field around the ACC was computed by means of CFD with and

without the windscreens

– Numerical analysis confirms that windscreens are beneficial

• Thermodynamic benefits

– Low wind scenario: overall gain 5.45%

Ò Reduced thermal recirculation (-4.71%)

– High wind scenario: overall gain 12.06%

Ò Fan flow rate and recirculation significantly improved

• Mechanical benefits

– Computed pressure field permitted to estimate the fluctuating load on the fan blades

– The oscillating mechanical load can be reduced up to 75% of its initial value

9

Page 10: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Analysis of PI Data• Power data:

– Hourly acquisition of plant gross power and fuel consumptionÒ Estimate of plant heat rate

– Data made dimensionless respect to a reference average value after plant revamping

• Comparison of homogeneous time serie before and after revamping– Early summer 2017 and 2018

• Time serie analysis and average daily peak show– Improvement of nearly 10% gross

power– Reduction in the heat rate of 7%

10

Average daily peak

Page 11: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Analysis of PI Data• Weather data:

– Hourly registrations for more than 2 years– Wind direction is mainly aligned with S direction

Ò More than 20% of events at 180°Ò Including neighbor directions nearly 40% of events fall within 45 deg from principal wind

direction– Secondary main direction is ENE with 13% of events

11

Wind speeds in mph

Page 12: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

• Wind: – Principal wind direction S 180° from geographical N

Ò Angle between geographical north and plant north is β=-10.84°Ò Actual wind direction respect to ACC is α=169.16°

Analysis of PI Data

12

E

S

W

N

Wind direction

E

SW

N

β

Geographical north

Plant north

α

Wind direction

Page 13: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Analysis of PI Data• Weather data:

– Principal wind direction (S) data Ò Discrete contributions of wind speed ranges shows negligible events (< 1%) above 15 mphÒ Typical high wind speed condition: 12 mph (5% of events – 90th percentile)Ò Typical low wind speed condition: 3 mph (6% of events – 10th percentile)

– Far field boundary layer uses a power law profile

Ò V y = $%&'× )*+,-

./$%&'0%&'1

13

High wind dayLow wind day

Page 14: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Modelling details• Fan model

– Digitized from manufacturer data– Pressure rise is a quadratic function of fan velocity

• Bundle model– Pressure drop modelled by means of a pressure drop coefficient ! = #$

%.'()*

– Actual value calculated to respect provided resistance curve– Temperature rise across the bundle is assumed at 8K

14

• Duty point– Set at 758.434 m3/s and 101.5 Pa– It does not consider any

additional type of lossÒ Lateral windÒ Neighbour fansÒ Recirculation losses

Page 15: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Wind screen position• Combined wind screen protection

– Suspended perimeter plus ground installed cruciformÒ Cruciform is split on two consecutive axis

– Simplified anchoring– Reduced wind load on structure

– Screens are made of 60% solid fabric with known aerodynamic resistanceÒ Recent experiments conducted at Stellenbosch University

15

Perimeter

Lower cruciform

Upper cruciform

Principal wind direction

Page 16: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results

16

• Aerodynamic performance parameters:• Actual mass flow wind loss:

• Change in ACC air mass flow rate respect to low wind speed LW without screens• ($̇%&&'())*+, -.+/ 01**/ − $̇%&&34_+67')**+)/$̇%&&34_+67')**+ : 100

• Relative Gain:• Percentage improvement of ACC air mass flow rate• ($̇%&&4.+/ 7')**+0 − $̇%&&+67')**+0)/$̇%&&+67')**+0 : 100

Page 17: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results

17

• Thermal performance parameters:• Recirculation:

• Percentage increase in temperature at the fan due to recirculation

• R= !"#$% &%'#( )$%*!$"+&#%(!+,%-'#*!$"+&#%(

. 100

• Combined performance parameters:• Bundle thermal power:

• Thermal power extracted at condenser• 3̇ = 5̇677 . 89,;<= . 1 − ? . @=AB − @CDEFGA

+5.45%

+12.1%

Page 18: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results• WS 3 mph:

– Temperature

18

No wind screens

Wind direction

E

W

S N

With wind screens

E

W

S N

Page 19: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results• WS 12 mph:

– Temperature

19

Wind direction

E

W

S N

E

W

S N

No wind screens With wind screens

Page 20: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results• WS 3 mph:

– Vertical velocity w

20

No wind screens

Wind direction

E

W

S N

With wind screens

E

W

S N

Page 21: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results• WS 12 mph:

– Vertical velocity w

21

Wind direction

E

W

S N

E

W

S N

No wind screens With wind screens

Page 22: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results• WS 3 mph:

– Temperature with velocity vectors on plane parallel to wind

22

No wind screens With wind screens

Wind direction

S N S N

Page 23: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results• WS 12 mph:

– Temperature with velocity vectors on plane parallel to wind

23

No wind screens With wind screens

Wind direction

S N S N

Page 24: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results• WS 3 mph:

– Velocity vectors on plane parallel to wind

24

No wind screens With wind screens

Wind direction

S N S N

Page 25: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results• WS 12 mph:

– Velocity vectors on plane parallel to wind

25

No wind screens With wind screens

Wind direction

S N S N

Page 26: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results• WS 3 mph:

– Backward streamlines with temperature

26

No wind screens With wind screens

Wind directionS

N

S

N

Page 27: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results• WS 12 mph:

– Backward streamlines with temperature

27

No wind screens With wind screens

S

N

S

N

Wind direction

Page 28: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results @12 mph

28

• Wind direction effects:

WORST BEST

Dmax = 6.79 %

S

EW

N

Page 29: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results @12 mph• Wind direction = North-East:

– Vertical velocity w

29

Wind direction

E

W

S N

E

W

S N

No wind screens With wind screens

Page 30: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results @12 mph

30

• Wind direction effects:

WORST BEST

Dmax = -5.23 %

S

EW

N

Page 31: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results @12 mph• Wind direction = North:

– Forward streamlines with temperature from fin fan outlet

31

No wind screens With wind screens

S

N

Wind direction

S

N

Page 32: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results @12 mph

32

• Wind direction effects:

WORST BEST

Dmax = 12.06 %

S

EW

N

Page 33: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Results• Oscillating load on blade:

– The blade load was computed examining the pressure values on the fan surfaceÒ Gauge pressure is plotted

– The high wind condition was studied since it is the most criticalÒ Wind blows from S at 12 mph

– Chosen as representative examplesÒ Fan 4_2: severe flow disuniformity Ò Fan 4_5: mild flow disuniformity

33

4_5

4_2Wind direction

Page 34: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Effect of fan positioning• Fan 4_2: severe flow disuniformity

– Windscreens are able to avoid backflow on the upstream fans

34

DPmax = 104 Pa DPmax = 53 Pa

Page 35: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

DPmax = 132 Pa

Effect of fan positioning• Fan 4_2: mild flow disuniformity

– Windscreens are able to further promote flow uniformity on the downstream fans

35

DPmax = 27 Pa

Page 36: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

- ACC UG 2018 - Colorado Springs, Cosimo Bianchini -

Highlights• A CFD campaign was completed to compute the aerothermal field around the ACC

with and without the windscreens– The numerical analysis predicts that windscreens are beneficial both for thermodynamic

and fan blade loadingÒ At low wind thermal recirculation effects are mitigatedÒ At high wind fan flow rate and recirculation are improvedÒ The oscillating fan blade load is largely reduced

– A significant interference with a neighbour heat exchanger is registered when wind is blowing from NorthÒ Worst scenario considered

– Wind screens are optimized for the prevailing wind direction obtaining a 12.06% overall gain

• Analysis of PI Data confirms these benefits– Quantitative improvements due to wind screens only could not be computed

Ò Overall improvement in plant production of nearly 10%

36

Page 37: Wind Screen effect on performance, before and after, and comparison … · 2020-05-05 · performance, before and after, and comparison with CFD - ACC UG 2018 - Colorado Springs,

Ergon ResearchVia Campani 50 Firenze

Air Cooled Condenser Users Group 2018Colorado Springs

Presenter:

Cosimo Bianchini

Questions?

Wind screen effects on performance