04 sundyne presentation fscontrol system

8/13/2019 04 Sundyne Presentation Fscontrol System

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CONTROL SYSTEMS


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INTRODUCTION

General, pump curve - System curve

Parallel operation

Series operation

Compressor control

Pump control bulletin


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GENERAL DISCUSSION

Are recurring problems a responsibility of maintenance?

Controls/procedures may result in equipment failure

May need coordination with process group


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CURVE SHAPES

120

100

80

60

40

00 20 40 60 80 100 120 140 160

Flow (Percent)

Head

(Percent)

Full EmissionConcentric Bowl & ETADouble Log Spiral

Z Series


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TOTAL SYSTEM HEAD

Capacity, Q

Head, H

System static head

System friction head

System head


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IMPACT OF VALVE THROTTLING

Capacity, Q

Head, H


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OPERATING SYSTEM

Capacity, Q

Head, H

Q2 Q1


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BY-PASS REQUIRED?

Capacity, Q

Head, H

Bypass Flow


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INTERSECTION OF PUMP AND SYSTEMCURVES

Capacity, Q

Head, H

Under-sized pump

Properly sized pump


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IMPACT OF WEAR

Over a period of time, system and pump characteristics getdeteriorated

After 15 years, friction losses in pipe are 60% more important!

To be taken in account in the choice of the pump

Minor loss for pump performances


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MINIMUM FLOW

2 Types of Minimum flow phenomena:

At start-up

During normal operation


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MINIMUM FLOWat start-up

Start-up shock wave

Water Hammering


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MINIMUM FLOWduring operation

Minimum Continuous stable flow

Minimum Continuous thermal flow


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MINIMUM FLOWFlow surging

May happen if a air/gas pocket is located in the downstream line

Can be seen as a simple spring-mass system

Need a excitation to happen

Can be reduced / solved by having a flow control valve close from thepump discharge

Predominent for compressors


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MINIMUM FLOWSurging reduction

Control valve within 3m of discharge

Flexible lines only after control valve

A straight pipe of at least 10 times diameter length on the discharge

Choose correct size of valve

Install low flow by pass

Eliminate air and gasses trapped

Operate at higher flow


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MINIMUM FLOWMinimum flow control

S FS


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MINIMUM FLOWPhenomenon


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MAXIMUM FLOWPhenomenon


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CONTROLLING

120

100

80

60

40

00 20 40 60 80 100 120 140 160

Flow (Percent)

Head

(Perc

ent)

Full EmissionConcentric Bowl & ETADouble Log SpiralZ Series


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PARALLEL OPERATION

Always use discharge check valve.

Need differential to open check valve

Low gravity fluid may vaporize - Pump deadheaded.

Unstable operation results in equipment damage

Always use bypass control valve.


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PARALLEL OPERATION WITH FLOW

CONTROLLED BYPASS ON EACH PUMP

FLOW SENSOR

CONTROLLER

BLOCK

CHECK

BYPASS

CONTROL

VALVE

CONTROLLER

FLOW SENSOR

BLOCK

CHECK

BYPASSCONTROL

VALVE

THROTTLE

CONTROL

VALVE

A

B

STARTUP SEQUENCE

1. SET EACH BYPASS FORMIN. ALLOWABLE FLOW

2. CLOSE PROCESS FLOW

CONTROL VALVE3. START PRE-LUBE PUMPS

IF APPLICABLE4. START A AND STABILIZE

START B AND STABILIZE5. SET DESIRED PROCESS

FLOW RATE

PARALLEL OPERATION


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SERIES OPERATION

Capacity, Q

Head, H

PUMP A OR B

PUMP A AND B

SYSTEM HEAD CURVE


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SERIES OPERATION

Requires extra measure of care (for second unitespecially)

Pre-lube normally advisable on 2nd unit.

Tandem seal & suitable buffer probably required.

Flange rating to be reviewed

Thurst bearing capacity to be increased


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STARTUP SEQUENCE1. SET BYPASS FOR MIN. ALLOWABLE FLOW2. CLOSE PROCESS FLOW CONTROL VALVE3. START PRE-LUBE PUMPS IF APPLICABLE

4. START 1ST UNIT AND STABILIZE5. START 2ND UNIT AND STABILIZE6. SET DESIRED PROCESS FLOW RATE

BYPASS FLOW

CONTROL

SENSOR CHECK

CHECKCONTROLLER

PROCESS FLOW

CONTROL VALVE

SERIES OPERATION - PREFERRED

04 sundyne presentation fscontrol system

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