Process technology equipment and systems chapter 5 & 6

Process technology equipment and systems chapter 5 & 6, Compressor, Turbines & Motors

O BJECTIVES

After studying this chapter, the student will be able to:

Explain the principles of compression

compressors use a compression ratio in the 3 to 4 range, with the same approximate sion ratio in each stage For example, if the desired discharge pressure is 1,500 psia, a 4-stage compressor with a 3.2 compression in each stage might be used The pressure at the discharge

compres-of each stage would be: 1st 5 47 psia, 2nd 5150 psia, 3rd 5 480, 4th 5 1,536 psia

a chemical desiccant, which adsorbs the water

posi-tively displace gases

the piston

multistage compressor

exist between a piece of equipment and the fluid in it

Compressor Applications and Classification

The compression of gases and vapors in the process industry is very tant Compressors are used in a variety of applications In a modern plastics facility, compressors are used to transfer granular powders and small plastic pellets from place to place In natural gas plants, compressors are used to establish feed gas process pressures Compressors also provide clean, dry air for instruments and control devices In a refinery or chemical plant, com-pressors are used to compress gases such as light hydrocarbons, nitrogen,

impor-hydrogen, carbon dioxide, and chlorine These gases are sent to headers,

from which they are distributed to a variety of applications

There are three basic designs for compressors (Figure 5.1): dynamic,

posi-tive displacement, and thermal Dynamic compressors include centrifugal

(radial flow) and axial (straight-line) flow compressors Positive

displace-ment compressors include rotary and reciprocating compressors Dynamic

compressors accelerate airflow by drawing air in axially and spinning it

outward (centrifugal compressors) or in a straight line (axial flow

com-pressors) Positive displacement compressors compress gas into a smaller

volume and discharge it at higher pressures Thermal compressors use

ejectors to direct high-velocity gas or steam into the process stream,

en-training the gas, and then converting the velocity into pressure in a diffuser

assembly This chapter focuses primarily on dynamic and positive

displace-ment compressors

A compressor is part of a much larger system The system’s resistance to

flow typically dictates compressor performance Minor problems are

occa-sionally experienced with compressor systems These troubles are usually

the result of dirt, adjustment problems, liquid in the system, or

inexperi-ence in operating the system Experiinexperi-enced technicians can quickly fix the

problem by making the proper adjustment, cleaning the equipment,

replac-ing a minor part, or removreplac-ing an adverse condition

Figure 5.1 Compressor Family Tree

Helical Lobe Straight Lobe

Integral Gear

Fixed Stator Vanes VariableStatorVanes Multistage

Liquid Ring Sliding Vane

Piston Compressor Diaphragm Reciprocating

Dynamic

Thermal

Balanced/Opposed Single/Multistage

Single/Multistage Horizon/Vert Split

Ejectors Single/Multistage

Scroll

The principles of compression are:

Gases and vapors are compressible

• Compression decreases volume

• Compression moves gas molecules close together

• Compressed gases will resume their original shape when

• released

Compressed gases produce heat because of molecular friction

• The smaller the volume, the higher the pressure

• Force

• 4 Area 5 Pressure

Gas volume varies with temperature and pressure

• Liquids and solids are not compressible (except under

• tremendous pressures)

Dynamic Compressors

Dynamic compressors are classified as either centrifugal or axial flow Both types operate by changing the velocity of gas and converting energy to pressure

Centrifugal Compressors

During operation, gas enters a centrifugal compressor at the suction let and is accelerated radially by moving impellers (Figures 5.2 and 5.3) Centrifugal compressors have one moving element, the driveshaft and im-peller In a centrifugal compressor, the impeller discharges into a circular,

in-narrow chamber called the diffuser This in-narrow opening completely

sur-rounds the impellers As back-pressure builds in the impeller, gas velocity

is accelerated through the diffuser assembly and into a circular volute As high-velocity gas moves through the diffuser and into the volute, kinetic

Stage # 3

energy is converted into pressure as gas speed slows in the ever-widening

volute before exiting the discharge port

Because compressor performance is linked to the compressibility of the

gas it is moving, centrifugal compressors are more sensitive to density and

fluid characteristics than are reciprocating compressors Most centrifugal

compressors are designed to operate at speeds in excess of 3,000 RPM

Recent advances in technology have resulted in the development of a

cen-trifugal compressor that runs at speeds in excess of 40,000 RPM

Centrifugal compressors can be single-stage or multistage Single-stage

compressors (Figure 5.4) compress the gas once, whereas multistage

compressors deliver the discharge of one stage to the suction of another

stage Single-stage centrifugal compressors are designed for high gas flow

rates and low discharge pressures; multistage compressors are designed

Figure 5.3

Centrifugal Compressor

Diffuser Plates

Diffuser

Impeller

Packing Packing Gland

Casing

Drive Shaft Diffuser Passage

Discharge

Suction Port

Figure 5.4

Single-Stage Centrifugal Compressor

for high gas flow rates and high discharge pressures Centrifugal sors are also used for transferring wet product gases that typically damage positive displacement compressors.

suction pressure (psia) Frequently, the desired discharge pressure is very high, over 100 times that of the inlet pressure When a gas is compressed, the temperature of the gas increases If a gas was compressed in one stage

to a pressure 100 times that of the inlet pressure, the gas temperature would

be extremely high Multistage compressors, with cooling between stages, are used to develop high pressures to allow for the heat of compression The compression ratio normally runs in the 3 to 4 range, with the same ap-proximate compression ratio in each stage For example, if the desired dis-charge pressure is 1,500 psia, a 4-stage compressor with a 3.2 compression

in each stage might be used The pressure at the discharge of each stage would be: 1st 5 47 psia, 2nd 5150.5 psia, 3rd 5 481.7, 4th 5 1,541.4 psia The simple calculation used to calculate the pressure increase on each stage is:

Stage One 14.7 psia 3 3.2 5 47.04 psiaStage Two 47.04 psia 3 3.2 5 150.528 psiaStage Three 150.528 psia 3 3.2 5 481.689 psiaStage Four 481.689 psia 3 3.2 5 1541.407 psiaThe basic components of a centrifugal compressor are shown in Figure 5.2 The part of the impeller vane that comes into contact with gas first is

called the suction vane tip The part of the impeller vane that comes into contact with the gas last is called the discharge vane The driver is an

electric motor or turbine

The basic types of impellers used on centrifugal compressors are the open backward-bladed impeller, open radial-bladed impeller, and closed back-ward-bladed impeller Figure 5.5 illustrates various impeller designs

Centrifugal compressors are considered to be the workhorses of the chemical-processing industry They are chosen more often than other types for new installations because they have a very low initial installation cost, low operation and maintenance cost, simple new piping installations, inter-changeable drivers, large volume capacity per unit of plot area, and long service life In addition, they can deliver much higher flow rates than posi-tive displacement compressors

Axial Flow Compressors

In the industrial environment, axial compressors are the compressor

of choice for jobs where the highest flows and pressures are required like centrifugal compressors, axial compressors do not use centrifugal force

Un-to increase gas velocity An axial flow compressor is composed of a roUn-tor

that has rows of fanlike blades (Figure 5.6) Airflow is moved axially along

the shaft Rotating blades attached to a shaft push gases over stationary

blades called stators The stators are mounted on or attached to the casing

As the rotating blades increase the gas velocity, the stator blades slow it

down As the gas slows, kinetic energy is released in the form of pressure

Gas velocity increases as it moves from stage to stage until it reaches the

discharge scroll Multistage axial compressors can generate very high flow

rates and discharge pressures

As a general rule, an axial compressor requires twice as many stages as

a centrifugal compressor to perform the same operation; however, axials

are 8% to 10% more efficient Axial compressors are limited to

approxi-mately 16 stages because of temperature and equipment stress Axial flow

compressors are often used in series flow with centrifugal compressors

because they are capable of operating at greater capacities The primary

application of axial compressors involves the transfer of clean gases such

as air The internal components of an axial flow compressor are extremely

sensitive to corrosion, pitting, and deposits

The stator blades in an axial compressor can be fixed, individually

adjust-able, or continually variable Individually adjustable stator blades can be

adjusted from outside the casing Continually variable blades are adjusted

by a drive ring linked to a driveshaft that is automatically actuated by a

In contrast to a centrifugal compressor, axial compressors accelerate and compress gas in a horizontal, straight-through motion, without the turbu-lent changes in direction characterized by centrifugal compressors Pound for pound, axial compressors are lighter, more efficient, and smaller than centrifugals A 23,000-hp axial produces as efficiently as a 25,500-hp cen-trifugal Even so, axial flow compressors are not as common as reciprocat-ing and centrifugal compressors One main use of axial compressors is in gas turbine applications.

Blowers and Fans

Blowers and fans are simple devices typically classified as compressors The two basic designs are axial flow and centrifugal flow Most blowers and fans are single-stage devices designed to perform a specific function Single-stage, centrifugal blowers are used for low-pressure air systems, refrigeration units, leaf blowing, ventilation systems, or laboratory hoods Fans can be used to direct airflow into or out of industrial equipment such

as cooling towers, flares, boilers, furnaces, HVAC (heating, ventilating, and air conditioning) systems, or air-cooled heat exchangers, or they can be used for ventilation of confined spaces

Figure 5.6 Axial Flow Compressor

Suction Line

Discharge Line Stator

Blades

Shaft

Rotor Blades

Seals Bearings

Inlet Guide Vanes

First Stage Second Stage

Cover

Motor

Side View

Top View

Fans can be classified as centrifugal, propeller, tube-axial, or vane-axial

Centrifugal fans are designed to move gases over a wide range of

condi-tions Propeller fans consist of a propeller and a motor mounted on a ring

This fan is primarily designed to operate over a wide range of volumes at

low pressures and to move air from one enclosed area into another

Tube-axial fans are mounted directly in the pipe cylinder and are designed to

move air or gas at medium pressures The vane-axial fan resembles the

tube-axial fan The motor and fan are mounted directly in the tube A

se-ries of vanes help direct flow over a wide range of volumes and pressures

Each of these four fans can be direct drive or belt driven

Positive-Displacement Compressors

Positive-displacement compressors operate by trapping a specific amount

of gas and forcing it into a smaller volume They are classified as either

rotary or reciprocating Rotary compressors are further classified as rotary

screw, sliding vane, lobe, or liquid ring Reciprocating compressors are

classified as piston or diaphragm

Positive-displacement compressors remove a set volume of gas for every

rotation or stroke of the primary transfer elements In process systems

where fluid density and suction pressures vary, positive displacement

de-vices provide steady service Rotary compressors can deliver pressures

between 100 and 130 psia Reciprocating compressor discharge

pres-sures that range from 0 to 30,000 psig

Rotary Compressors

Rotary compressors take their name from the rotating motion of the

trans-fer element A good case could be made that centrifugal compressors are

rotary Centrifugal compressors do rotate, but they do not positively

dis-place or compress the gas In contrast, the rotating elements of a rotary

compressor displace a fixed volume of fluid inside a durable casing on

each rotation

Rotary Screw Compressors

The rotary screw compressor is commonly used in industry This device

closely resembles the lobe compressor and operates with two helical

ro-tors that rotate toward each other, causing the teeth to mesh (Figure 5.7)

As the left rotor turns clockwise, the right rotor rotates counterclockwise,

forcing gas to become trapped in the central cavity Rotary screw

compres-sors are designed with an inlet suction line and an outlet discharge port

The two rotors are attached to a driveshaft, timing gears, and a driver that

provides the energy to operate

Flow enters the device and is moved axially toward the discharge port The majority of compression takes place very close to the compressor outlet The moving elements of the rotary screw compressor do not touch each other or the inner wall A set of timing gears allows the power rotor to turn the alternate rotor Because of this design, the rotating elements do not require lubrication, making them a perfect choice for dry gas service Be-cause of the small tolerances that exist between the moving elements, some internal slip occurs during operation.

Rotary screw compressors operate at speeds between 1,750 and 3,600 RPMand have capacity ratings above 12,000 cfm (cubic feet per minute) on the inlet volume and discharge pressures between 3 and 20 psig Some rotary screw units can operate between 60 and 100 psig Another feature associ-ated with the rotary screw compressor is its ability to be used as a vacuum device This system is designed to handle 500 to 10,000 cfm on the suction side and to pull a vacuum between 5 and 25 inches of mercury

Sliding Vane Compressors

The sliding vane compressor uses a slightly off-center rotor with sliding vanes

to compress gases The major components of a sliding vane compressor are shown in Figure 5.8 The gas inlet port is positioned so that gas flows into the vanes when they are fully extended and form the largest pocket As the vanes turn toward the discharge port, the gases are compressed

The body of the compressor is fabricated from cast iron or steel A set of cooling water jackets is fabricated into the initial design and tested for tight-ness The rotor and shaft are made of high-strength alloy steel The rotor

is precision made with slots around the entire rotor The sliding vanes are composed of asbestos-phenolic resin, metal, or high-temperature, durable metal Sliding vane compressors require lubrication between the vane and contact surface Lubricating oil is injected into the suction side of the com-pressor This procedure helps prevent internal slip and provides a positive seal Sliding compressors are typically nonpulsing systems

As gas enters the sliding vane compressor, it is captured in vanes and swept around the casing, filling the chamber As the vanes rotate toward

the discharge, the vane length shortens because of the rotor’s eccentric

position with the shaft, and volume is decreased As volume decreases,

pressure increases until maximum compression is achieved At this point,

the gas is discharged out of the compressor This type of compressor does

not use suction or discharge valves because it is designed to discharge

against system pressure

Lobe Compressors

im-pellers used to trap and transfer gases (Figure 5.9) The close clearances

between the casing and impellers are maintained by a set of timing gears

During operation, the two impellers move in opposite directions on

parallel-mounted shafts as the lobes sweep across the suction port The

paral-lel shafts are composed of a driveshaft and an idler shaft The driveshaft

forces the idler shaft to turn through the gears The gears and bearings are

located on the outside of the compressor Compressed gases are released

to the discharge line

Figure 5.8 Sliding Vane Compressor

Cooling Water Jacket

Vanes in Running Position

Suction

Off-Center Rotor Base

Casing Discharge

Check Valve

Figure 5.9

Lobe Compressor

Suction Discharge Port

Impellers

The internal lobes on a rotary lobe compressor are designed not to touch

A few thousandths of an inch clearing exists between the casing and lobes The design clearances on the internal lobes of a lobe compressor allow some slip The slip is aggravated at high discharge pressure when low-density gases are being pushed Process slip is constant only when system pressure is constant

Lobe compressors are designed to have constant-volume discharge sures and constant-speed drivers Lobe compressors do not use discharge

pres-or suction valves because they are not designed to operate at a specific pressure Discharge pressures are determined by the system’s process pressure

Lobe compressors can be used in wet and dry gas service The rotation of the lobes may be up or down; that is, the discharge port can be at the top

or at the bottom of the unit In dry service, the upward rotation is preferred

In wet service, the downward rotation is recommended so any condensed liquids can escape Lobe compressors can be used as compressors or vacuum pumps

Liquid Ring Compressors

A very unusual compressor design is the liquid ring compressor It bines the centrifugal action of the liquid with a positive displacement, ro-tary action A liquid ring compressor has one moving transfer element and

com-a ccom-asing thcom-at is filled with mcom-akeup wcom-ater or secom-al liquid (Figure 5.10) As the rotor turns, the fluid is centrifugally forced to the outer wall of the elliptical casing An air pocket is formed in the center of the casing As the liquid ring compressor rotates, a small percentage of the liquid escapes out the discharge port Makeup water or seal liquid is admitted into the compres-sor during operation The liquid medium helps cool the compressed gases The off-center position of the rotor creates an offset in the air pocket Lo-cated on the rotor are suction and discharge ports The inlet ports are much larger than the discharge ports As the vanes turn, gases are compressed

in the volute-shaped air pocket

Liquid ring compressors may be found in the following applications:

Hazardous gases

• Toxic gases

• Hot gases and vapors

• Vacuum of 27 to 29 inches of mercury

• Nonpulsing flow

• Jet and surface condenser

• Oil-free gases

•

Scroll Compressors

A scroll compressor (see Figure 5.11) has two interleaved spiral vanes signed to compress fluids into ever decreasing volumes Scroll compressors

de-Figure 5.10

Liquid Ring Compressor

Suction Inlet # 2

Water

Liquid Ring Casing

Casing

Air Cavity

Suction

Suction Discharge

Discharge

Seal Fluid Inlet

Seal Fluid Inlet

Motor

Figure 5.11

Scroll Compressor

run quietly and smoothly at lower volumes, trapping fluid between the scrolls In most cases, one scroll is fixed and one orbits eccentrically with-out rotating.

Reciprocating Piston Compressors

Their distinctive back-and-forth motion characterizes reciprocating pressors Reciprocating compressors are classified as either piston or dia-phragm Diaphragm compressors utilize a hydraulically pulsed diaphragm that moves or flexes to positively displace gases We discuss only the pis-ton type because it is the most popular design Equipment ratings from fractional horsepower to over 20,000 hp are possible on reciprocating com-pressors Pressure differences of below-atmospheric on the suction side

com-to over 30,000 psi on the discharge side are possible During operation, reciprocating compressors perform best with clean gases Entrained water, dirt, and impurities will cause excessive wear on the piston and cylinder Reciprocating compressors are selected when low flow rates and high dis-charge pressures are required

There are several advantages of using a reciprocating piston compressor They have a flexible pressure range and overall capacity, low power cost, and high efficiency rating They can handle density and gas composition changes, and small volumes and can deliver high pressures

Reciprocating piston compressors work by trapping and compressing cific amounts of gas between a piston and the cylinder wall The back-and-forth motion incorporated by a reciprocating compressor pulls gas in on the suction or intake stroke and discharges it on the other Spring-loaded suction and discharge valves work automatically as the piston moves up and down in the cylinder chamber The basic parts of a piston reciprocating compressor are shown in Figure 5.12

spe-Reciprocating piston compressor design varies from model to model These variations usually occur in the total number of cylinders and in the arrangement of the suction and discharge lines Most piston compressors have one to four cylinders Each cylinder has its own piston, rings, and automatic valves Common crankshafts can be shared with multiple con-necting rods The same cylinder can be equipped with multiple suction and discharge valves in double-acting compressors

Cylinder Design

A cylinder’s material is typically selected on the basis of corrosion tance, thermal shock resistance, pressure rating, and mechanical shock resistance (Thermal shock is a form of stress resulting in metal fatigue caused by large temperature differences between a piece of equipment and the fluid in it.) Common materials used to fabricate cylinders are cast iron

resis-(up to 1,200 psig), nodular iron (1,500 psig), cast steel (1,200–2,500 psig),

and forged steel (over 2,500 psig)

Single-Acting Parallel Arrangement

In a parallel cylinder arrangement (Figure 5.13), two cylinders are lined up

They have separate intakes and a common discharge line This type of

op-eration doubles the flow rate while keeping the pressure constant

Single-Acting Multistage Compressors

A multistage piston compressor has two or more cylinders The first

cylin-der usually is referred to as the first stage Two-stage multistage

compres-sors (Figure 5.14) discharge from the first cylinder into the suction line of

the smaller second cylinder In a multistage compressor, flow rates usually

are low and overall pressure is high

Double-Acting Compressors

Double-acting compressors (Figure 5.15) use a common cylinder and

pis-ton to discharge and take in gases on each side of the cylinder

Double-acting compressor cylinders are equipped with two spring-loaded intake

valves and two spring-loaded discharge valves For example, when the

piston moves to the right, the chamber to the left of the piston fills with gas,

while the chamber to the right of the piston discharges The exact opposite

Figure 5.12 Reciprocating Piston Compressor (Double-Acting)

Piston

Packing Packing Gland

Figure 5.15

Double-Acting

Suction Line

Discharge Line Suction Line

Line

occurs on the reverse stroke This technology doubles the efficiency of the

compressor

Compressor Layout

The layout of a compressor can be determined easily by looking at the

position of the cylinders V- and L-shaped layouts are found frequently (see

Figure 5.14)

Pulsation Control

A common problem found with reciprocating compressors is pulsation

This inherent problem occurs because the suction and discharge valves

open and close during each cycle This problem can be controlled by using

a surge drum, pulsation dampener (Figure 5.16), or volume bottle These

devices provide smooth gas flow, reduce vibration, and prevent

overload-ing or underloadoverload-ing the compressor

Diaphragm Compressors

moves or flexes to positively displace gases This type of compressor is

closely related to a reciprocating compressor This type of compressor is a

combination of several systems; a gas compression system and a

hydrau-lic system Gas compression occurs when a flexible metal diaphragm or

Figure 5.16

Pulsation Dampener

membrane hydraulically flexes In this type of an operation only the brane and the compression chamber come into contact with the gas For this reason the diaphragm compressor is ideal for applications that involve explosive and toxic gases Membranes are designed to be durable and tough and able to withstand high temperatures and a variety of conditions Diaphragm compressors can generate very high pressures and are used

mem-to compress hydrogen, hydrogen chloride, carbon monoxide, compressed natural gas Diaphragm compressors come in one, two, three, or more stages Each stage requires the use of one diaphragm Figure 5.16 illus-trates the basic components of a diaphragm compressor

The basic components of a diaphragm compressor include:

Inlet and outlet gas check valves

• Hydraulic fluid check valve

• Diaphragm or membrane

• Hydraulic injection pump

• Hydraulic piston

• Sight glass

• Piston rods

• Crankshaft

• Crankcase frame

Diaphragm or Membrane

Suction Discharge

Hydraulic Injection Pump

Hydraulic Overpump Valve

Overpump Sightglass

Check Valves

XX

Supporting Equipment in a Compressor System

When compressors are used in a process system, a wide assortment of

supporting equipment is required (Figure 5.18) Some of this equipment—

such as filters, drivers, and seals—has been described elsewhere Here we

will describe intercooler and aftercooler heat exchangers, safety valves,

silencers, demisters, and dryers

Intercooler and Aftercooler Heat Exchangers

The compression of gases creates heat in a compressor Shell and tube

heat exchangers (intercoolers and aftercoolers) have been added to the

design to control high temperatures As gas is discharged out of the first

stage of a compressor, the intercooler lowers the temperature This cooled

gas is directed into the suction line of the second-stage compressor As

this gas is compressed (creating more heat), it is discharged into the

after-cooler before going to the receiver

Safety Valves

Safety valves and pressure relief valves are used to relieve excess

pres-sure that could damage operating equipment and hurt operating

person-nel These valves are sized to handle specific flow rates and should not be

Figure 5.18 Compressor System

Instrument Air Header

I P

PE PT

PIC

replaced without ensuring that the replacement valves meet engineering specifications Some safety valves automatically reseat; other types must

be removed and mechanically reset

Be-Dryer

For extremely dry air service, the discharge of a compressor is run through

a dryer Dryers filled with moisture-adsorbing chemicals are called

types of chemicals used in dryers Typical dryer operation uses parallel or series dryers Both arrangements allow one dryer to be in service while the other is being regenerated The regeneration process uses dry, clean, heated gas to strip the moisture out of the spent dryer

Other Supporting Equipment

receiver is the tank in which compressed gas is stored

Startup, Shutdown, and Troubleshooting

of Compressor Systems

Figure 5.18 presents a simple illustration of a multistage centrifugal pressor and a liquid ring compressor system Each system is equipped with similar instrumentation and piping The primary equipment found in this system is a compressor, receiver, dryer, air header, and modern pro-cess instrumentation Only one system should be used at a time

com-Tables 5.1 and 5.2 illustrate typical startup and shutdown procedures

Ta-bles 5.3 and 5.4 illustrate trouTa-bleshooting charts for identifying and solving

compressor problems

Table 5.1 Starting Up and Shutting Down a Dynamic Compressor

Procedure Comments

1 Perform valve lineups on compressor

and associated equipment.

Ensure that each valve is in the proper position before startup.

2 Check oil levels and bearing-cooling

6 Open suction line to compressor Opening the suction line should load

up the compressor as gas flow is established.

7 Monitor equipment until process fills lines.

Table 5.2 Starting Up and Shutting Down a Positive-Displacement

Compressor

Procedure Comments

1 Perform valve lineup on compressor

and associated equipment

Ensure that each valve is in proper position before startup.

2 Line up cooling water to exchangers.

3 Check oil levels and bearing-cooling

6 Press start button on panel Allow compressor to warm up.

7 Check for abnormal conditions on

compressor

Check temperature, pressure, noise, and excessive vibrations.

Table 5.3 Troubleshooting a Centrifugal Compressor

Problem Possible Cause

Excessive vibration • Misaligned shaft

Damaged coupling

• Damaged rotor

• Bearing or seal damage

• Discharge pressure low • Leak in piping

Low suction pressure

• System demand exceeding design limits

• Compressor not up to speed

• Lube oil pressure low • Oil level low

Incorrect pressure setting

• Lube oil pump failure

• Dirty filter or strainer

• High temperature on bearing oil • Restricted flow

Oil needs to be changed

• Bearing failure

• Water in lube oil

• Fouling in oil coolers

• Driveshaft misalignment • Foundation shift

Loose bolts on foundation

• Piping strain

• Grouting washed out

• Water in oil system • Ruptured tube in heat exchanger

Condensation in oil reservoir

• Rain water

• Steam tracing leak