Buffalo State College

Mechanical Engineering Technology

Senior Design Project Proposal

Spring 2015

Centrifugal Compressor Impeller

Tip-to-Shroud Measurement System

Sponsor: FS-Elliott Co. LLC

Date Presented: March 10, 2015

Design Team:

Morgan Allis _________________________

Chuck Mantell _________________________

Bradley Brooks _________________________

Jeff Villont _________________________

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ABSTRACT

This project will introduce sensor technology to measure impeller-tip-to-shroud clearance

into FS-Elliotts Polaris+ centrifugal air compressor model P300. FS-Elliott Co., LLC, is a

leading centrifugal air compressor manufacturer with manufacturing locations around the world.

FS-Elliott is seeking solutions to maximize efficiency of their compressors by controlling and

monitoring distances between impeller blade tip and compressor shroud; the first step to this is

installing a sensor to measure impeller tip clearance. This project will explore different sensing

options to measure blade tip to shroud clearance. FS-Elliott will receive a package including

optimal sensing recommendations, product installation into their P300 compressor, and cost

analysis.

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TABLE OF CONTENTS

Section Title Page Number

LIST OF FIGURES 1.0 4

LIST OF TABLES 2.0 5

INTRODUCTION 3.0 6

P300 COMPRESSOR 4.0 8

GUIDELINES 5.0 12

SENSOR TECHNOLOGY 6.0 13

CAPACITIVE 6.1 13

INDUCTIVE 6.2 15

LASER DOPPLER 6.3 16

EDDY-CURRENT 6.4 18

FIBER OPTICAL 6.5 20

VARIABLE RELUCTANCE SENSOR (VR) AND HALL EFFECT 6.6 22

Variable Reluctance 22

Hall Effect 23

PHOTOELECTRIC SENSOR 6.7 25

MICROWAVE DISTANCE SENSOR 6.8 27

RESTRICTIONS 7.0 28

CHOSEN DESIGN 8.0 28

CAUSE AND EFFECT MATRIX 8.1 29

PROJECT MANAGEMENT 9.0 30

APPENDIX 10.0 31

REFERENCES 11.0 32

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LIST OF FIGURES 1.0

FIGURE 3.1. A CENTRIFUGAL COMPRESSOR IN THE MANUFACTURING PROCESS 6

FIGURE 3.2. AN INTERNAL VIEW OF A COMPRESSOR BEING ASSEMBLED AT FS-ELLIOTTS MANUFACTURING

FACILITY 7

FIGURE 4.1. FS-ELLIOLTTS P300 COMPRESSOR SHOWING OUTBOARD (A.) AND INBOARD (B.) VIEWS 8

FIGURE 4.2. A LOOK AT INTERNAL COMPONENTS OF FS-ELLIOTTS P300 COMPRESSOR 9

FIGURE 4.3. TYPICAL OPERATION FLOW-DIAGRAM OF FSES P300 COMPRESSOR 10

FIGURE 5.1. SENSOR PROBE INSTALLATION ANGLE 12

FIGURE 6.1.1. POSSIBLE CAPACITIVE SENSOR PROBES 14

FIGURE 6.2.1. INDUCTIVE SENSOR PROBE 15

FIGURE 6.3.1. FIBER OPTIC LASER DOPPLER SYSTEM 17

FIGURE 6.4.1. TWO BODY STYLE EDDY-CURRENT PROBES 19

FIGURE 6.5.1. PHOTO OF MONARCH OPTICAL SENSOR 21

FIGURE 6.6.1. IN A VR SENSOR, THE RESULTING ANALOG SIGNAL MUST BE FILTERED AND

THRESHOLDED TO YIELD A USEFUL PULSE OUTPUT 22

FIGURE 6.6.2. IN A HALL-EFFECT SENSOR, ALL LOW-LEVEL SIGNAL PROCESSING IS PERFORMED ON

THE SILICON CHIP HOLDING THE TRANSDUCER 23

FIGURE 6.6.3. WAYS THAT SENSORS TAKE THEIR READING FROM ROTATING OBJECT 24

FIGURE 6.7.1 PHOTO OF PHOTOELECTRIC SENSOR 26

FIGURE 6.8.1 MICROWAVE SENSOR DIAGRAM 27

FIGURE 8.1. SIMPLIFIED SCHEMATIC OF HB-01 30

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LIST OF TABLES 2.0

Table 8.1 Cause and Effect Matrix 29

Table 9.1. Gantt chart for project management section of our design 31

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INTRODUCTION 3.0

FS-Elliott Co., LLC is a leading manufacturer of oil-free centrifugal air and gas

compressors with sales, service, and manufacturing locations around the world. They

manufacture a variety of air compressors that range from 450 HP (335 kW) to 2500 HP (1864

kW) and 2090 CFM (987 l/sec) to 11500 CFM (5430 l/sec), As shown in FS-Elliott Co., LLC

Polaris+ (2014). Markets and industries they serve include air separation,

chemical/petrochemical, electronics, general industry, medical, mining, oil and gas,

pharmaceutical, and refining.

Turbo machinery is widely used with countless applications. Efficient aerodynamics

makes centrifugal compression ideal for many industrial applications. Centrifugal compressors

produce pressure by transferring energy from a rotating impeller to the air. Centrifugal

compressors are efficient, low maintenance with minimum wearing parts, low vibration, and

have excellent reliability over extended periods of time. FS-Elliott Co., LLC Polaris+ (2014).

Figure 3.1. A centrifugal compressor in the manufacturing

process

at FS-Elliotts manufacturing facility in Export,

PA

This project will specifically deal with FS-

Elliotts Polaris+ P300 centrifugal compressor. This

compressor is a medium to small multi stage compressor with three stages of compression. P300

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compressors range from 250-450 hp (186-335 kW) and flow rates of 900-2090 CFM (424-986

l/sec), and a discharge pressure of 45-150 psi (310-1034 kPa). FS-Elliott Co., LLC Polaris+

(2014).

This project involves introduction of a sensor that will measure impeller tip-to-shroud

clearance on FS-Elliotts P300 centrifugal compressor. Numerous sensing technologies will be

analyzed based on characteristics including cost, size, resolution, temperature rating, surface

area, installation, electronics, durability, life expectancy, sensitivity to contamination, and need

for calibration. FS-Elliott will receive design recommendations based on six-sigma matrix, 3D

model of design, and project management analysis for the project. Successful introduction of

sensor technology into FS-Elliotts centrifugal compressors could lead to further control of

impeller tip-to-shroud distances by means of actuation.

Figure 3.2. An Internal view of a compressor being assembled at FS-

Elliotts manufacturing facility

1. Driving bull gear for centrifugal

compressor

2. Driven pinion gear in which compressor impeller will be mounted

P300 COMPRESSOR 4.0

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FS-Elliotts P300 compressor is a medium to small size, oil free, multi stage compressor,

with three stages of compression. The P300 is the smallest centrifugal compressor that FS-Elliott

manufactures and also has the highest rotational impeller speed as shown in FS-Elliott Co., LLC

P-300 (2008).

Rotational impeller speeds range from 51,310 rpm at low speed and 68,414 rpm at high

speed. The P300 compressor has 15 full and 15 splitter blades in its 1st stage of compression, and

17 blades in its 2nd and 3rd stages of compression. It operates at or below a temperature of 350F

(177C). FS-Elliott Co., LLC P-300 (2008).

Figure 4.1. FS-Ellioltts P300 compressor showing Outboard (a.) and Inboard (b.) views, as shown by Smith, D.,

Tursky, M., Wellek, R. (2013).

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Figure 4.2. A look at internal components of FS-Elliotts P300 compressor, as shown, in Smith, D., Tursky, M.,

Wellek, R. (2013).

1. Pinion (driven gear), attached to the impeller.

2. Bull gear (driving gear), connected to engine output, and drives impeller pinion.

3. Impeller, consisting of 15 or 17 blades, moves air in a rotational direction to

diffuser plates.

4. Diffuser plates, causing a decrease in velocity allowing for pressure to increase.

5. Shroud of compressor, component concerned with impeller tip clearance.

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Operation of the P300 compressor consists of ambient air entering an inlet control into its

first stage of compression. A centrifugal impeller accelerates air and then velocity is slowed and

pressure in increased, by means of a diffuser. Air then enters a bundle tube heat exchanger for

cooling. The following diagram shown in (FSE P300 brochure), demonstrates the typical

operation of FS-Elliotts P300.

Figure 4.3. Typical operation

flow-diagram of FSEs P300 compressor,

as shown in FS-Elliott Co., LLC P-300

(2008).

1. Ambient air entering inlet control

2. Air accelerated by first impeller. Temperature and velocity rise, before a radial

diffuser plate slows velocity and creates pressure.

3. Hot air enters first stage of intercooling. Air passes over water filled tubes with fins.

4. Air makes two 90-degree turns begins to flow upward, allowing separation of

condensed moisture from cooled air.

5. Air exiting heat exchanger and flowing through second inlet control device for

second stage of compression.

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