innovative metering pump for polyurethane catalysts and...

Innovative Metering Pump for Polyurethane Catalysts and Additives


Presentation for the 2015 Polyurethanes Conference

October 5 - 7Gaylord Palms ResortOrlando, Florida USA

Donelle CapriottiWanner Engineering, Inc.

Richard (Dick) WernerCannon USA

Copyright © 2015

Cannon USAwww.CannonUSA.com

Wanner Engineering, Inc.www.Hydra-Cell.com/metering

Two-component pumping system to produce polyurethane foam using an external gear pump to deliver a water catalyst.

150˚F (65.6˚C)

100˚F (37.8˚C)

500 psi (34.5 bar)

300 psi (20.7 bar)

Fluid #1Polyurethane Prepolymer

Fluid #2Water-Catalyst Blend

60 gr/s 3.7 gr/s


Polyurethane Foam Production

APPLICATION

The water-catalyst solution is non-lubricating and shear-sensitive. The effective viscosity decreases with pumping shear.


Difficulty

PROBLEM

Normal Viscometer Reading

Vis

cosi

ty

Typical Shear Rate in Pumping System

Shear Rate

The thinning viscosity of the water-catalyst solution effectively increases the “slip” in the external gear pump. A higher rpm is necessary to maintain the desired flow rate.


Occurrence

PROBLEM

80 10060402000

1

2

3

4

5

6

7

8

9

10

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Differential Pressure: psi

Flo

w: g

pm

Po

wer

: bh

p

1 cP Fluid

80 10060402000

1

2

3

4

5

6

7

8

9

10

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Differential Pressure: psiF

low

: gp

m

Po

wer

: bh

p

100 cP Fluid

1750 rpm

1450 rpm

1150 rpm

900 rpm

600 rpm

600 rpm

1750 rpm

1450 rpm

1150 rpm

900 rpm

00000.0.44444

0.6P

ow

2

3

4

Flo

w

900 rpmm

1750 rpm

600 rpm

1750 rpm

600 rpm

The “slip” in the external gear pump effectively reduces the flow rate by nearly 50% when operating at similar rpm. This requires doubling the pump speed to maintain the required flow.


Occurrence

PROBLEM

3.47

Flow: gr/sec

1.81

Dis

char

ge

Pre

ssu

re: p

si

0

25

50

75

100

125

150

175

200

225

250

275

300

325

350

375

Pump Speed = 76.4 rpm

Pump Speed = 78.2 rpm

In an external gear pump, the two gears come in and out of mesh with one another. The tight tolerances of the working parts inside the gear pump are what enable it to pump.

1. As the gears come out of mesh, the liquid is drawn into the teeth.

2. The teeth hold the liquid as the gears rotate against the casing.

3. Before the teeth mesh together again, the liquid is forced out the discharge port of the pump.


Methodology

PROBLEM

1 2 3

Low-viscosity fluids “slip” through the tight spaces from the higher pressure (discharge) side back to the lower pressure (inlet) side of the pump.

The extent of leakage to slip depends on:

• Internal pump clearances

• Differential pressure between the discharge and inlet pressures

• Viscosity of the fluid

In this case, the decrease in the effective viscosity from pump shear and the higher discharge pressures significantly increased the slip. These lowered the overall efficiency of the pump.


Methodology

PROBLEM

High Pressure

DischargeInlet

Fluid leaks from high pressure to low pressure over sides of gears

Low Pressure

The solution was to replace the external gear pump with a Hydra-Cell Metering Solutions Model P200 pump to deliver the water-catalyst blend.


Hydra-Cell Metering Solutions

SOLUTION

The Hydra-Cell P200 is shown operating with electronic flow control (VFD) for accuracy. Liquid end materials of construction include a 316L Stainless Steel pump head and three Aflas® diaphragms.


Capability

SOLUTION

Propane/ Freon Ammonia Polymers Fuels/ D.I. Water Glycols Chlorine Acids/ Glues/ Inks/ Resins Slurries Butane Additives Caustics Adhesives Paints

Hydra-Cell Metering Solutions pumps can handle a broad spectrum of process fluids from thin, low-viscosity fluids to highly viscous resins.


Capability

SOLUTION

The Hydra-Cell P200 metering pump flow rate remains constant throughout the entire pressure range of operation.

Flow: gr/s

Pre

ssur

e: p

si

31 60 91 1210

200

400

600

800

1000

1200

0

Maximum Capacity: 85.17 gr/s

Maximum Discharge Pressure: 1000 psi

Maximum Operating Temperature: 250˚F

Maximum Inlet Pressure: 250 psi


API 675 Performance Standards

SOLUTION

Accuracy - Performance at a Set Point

Flow variation is expressed as a percentage of mean delivered flow under fixed system conditions. Hydra-Cell Metering Solutions pumps meet or exceed the API 675 standard by providing precise steady-state accuracy of ±1% or better.

12.40

12.38

12.36

12.34

12.32

12.30

12.28

12.26

12.24

12.22

12.20

12.18

12.16

12.14

12.12

12.10

12.08

12.06

12.04

12.02

12.00

Time(Capacity measurements taken every 20 minutes.)

Flo

w: g

ph

Set Point (12.22 gph)

-0.5% of Set Point

-1% of Set Point

+0.5% of Set Point

+1% of Set Point

API 675 ±1% of Set Point Hydra-Cell ±0.5% of Set Point

All parameters remain unchanged (NPSH, pressure, temperature, etc.).



SOLUTION

Linearity - Speed/Flow Rate Relationship

The degree to which performance or response deviates from the flow rate compared to the capacity setting. Hydra-Cell Metering Solutions pumps meet or exceed the API 675 standard by providing linear flow within ±3% or better.

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

Capacity Setting: motor rpmBest Fit Line is drawn through the Measured Flow data points, taken at 100%, 75%, 50%, 25%, and 10% of Rated Capacity (12.25 gph).

Flo

w: g

ph

10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0%

API 675 ±3% of Rated Capacity

Hydra-Cell Measured Flow

Best Fit Line

Pressure is constant. Maximum flow over a turndown ratio of 10:1.



SOLUTION

Repeatability - Return to Set Conditions

The reproducibility of pump flow rate under a given set of conditions when the capacity setting is varied and then returned to the set point. Hydra-Cell Metering Solutions pumps meet or exceed the API 675 standard by always returning to a ±3% or better set point condition.

12.50

12.00

11.50

11.00

10.50

10.00

9.50

9.00

8.50

8.00

7.50

7.00

6.50

6.00

5.50

5.00

4.50

4.00

3.50

3.00

2.50

2.00

1.50

1.00

0.50

0.00

Capacity Setting: motor rpm

Flo

w: g

ph

1200 600 240 1200 1800 1200 2400 1200

API 675 ±3% of Rated Capacity

Measured Flow at Set Point

Measured Flow of Capacity Variation

Rated Capacity: 12.54 gph


Efficiency

RESULTS

External Gear Pump

Due to leakage-to-slip, the gear pump operated at 51% to 65% volumetric efficiency. Greater pump speeds were required to deliver the expected flow at the designated pressure.

Expected Measured Discharge Pump Speed Pump Volumetric Flow (gr/s) Flow (gr/s) Pressure (psi) (rpm) Efficiency

1.63 1.00 165 43.72 61% 1.86 1.20 187 49.97 65% 2.31 1.45 235 62.19 63% 2.77 1.55 285 74.54 56% 3.23 1.80 330 86.90 56% 3.69 1.90 380 99.12 51%


Efficiency

RESULTS

External Gear Pump

The graph illustrates the data from the chart on the previous page where the gear pump does not achieve expected flow without increasing pump speed.

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

43.72 49.97 62.19 74.54 86.90 99.12

Flo

w: g

r/s

Pump Speed: rpm

165 psi

187 psi

235 psi

285 psi

380 psi

%

Expected Flow

Measured Flow

Pump Volumetric Efficiency

61%

65%

63%56%

56%51%

330 psi


Efficiency

RESULTS

Hydra-Cell P200 Metering Pump

The Hydra-Cell P200 maintains the expected flow (and 100% volumetric efficiency) at lower pump speeds throughout entire pressure range.

Expected Measured Discharge Pump Speed Pump Volumetric Flow (gr/s) Flow (gr/s) Pressure (psi) (rpm) Efficiency

1.63 1.64 165 14.03 101%

1.86 1.87 187 16.02 100%

2.31 2.33 235 19.97 101%

2.77 2.77 285 23.99 100%

3.23 3.23 330 28.00 100%

3.69 3.69 380 32.02 100%


Efficiency

RESULTS

Hydra-Cell P200 Metering Pump

The graph illustrates the data from the chart on the previous page showing that the Hydra-Cell P200 metering pump achieves the expected flow rate at lower pump speeds.

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Flo

w: g

r/s

14.03 16.02 19.97 23.99 28.00 32.02

Pump Speed: rpm

165 psi

187 psi

235 psi

285 psi

330 psi

380 psi

%

Expected Flow

Measured Flow

Pump Volumetric Efficiency

101%

100%

101%

100%

100%

100%


Conclusion

RESULTS

The Hydra-Cell model P200 replaced the external gear pump and improved performance.

• Low efficiency experienced by the gear pump was eliminated.

• Difficulty processing a shear-sensitive, non-lubricating fluid was resolved.

• Flow accuracy, linearity, and repeatability met the stringent requirements of the polyurethane foam production process.

• Hydra-Cell P200 pumps have now replaced all of the external gear pumps for the application.


Richard (Dick) WernerCannon USA1235 Freedom RoadCranberry Twp., PA 16066 USAPhone: 724-772-5600www.CannonUSA.com

Donelle CapriottiWanner Engineering, Inc.1204 Chestnut AvenueMinneapolis, MN 55403 USAPhone: 612-332-5681www.Hydra-Cell.com/metering

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