ML20043F656: Difference between revisions

From kanterella
Jump to navigation Jump to search
(StriderTol Bot insert)
 
(StriderTol Bot change)
 
Line 16: Line 16:


=Text=
=Text=
{{#Wiki_filter:Emergency Diesel Generator                                                   Engine Lubrication System 5.0 ENGINE LUBRICATION SYSTEM 5.1.1.1 Frictional Surfaces There is no This      chapter    presents    the    major        such thing as a perfectly flat or smooth components of engine lubrication system                surface. If we take a microscopic look at two and explains how the system is necessary              surfaces in contact, as in Figure 5-1, each for the reliable operation of the engine.              surface consists of a series of peaks and valleys. As one surface attempts to move Learning Objectives                                    relative to the other, the peaks contact one another creating a resistance to movement.
{{#Wiki_filter:Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-1 of 27 USNRC HRTD 5.0 ENGINE LUBRICATION SYSTEM This chapter presents the major components of engine lubrication system and explains how the system is necessary for the reliable operation of the engine.
As a result of this lesson, you will be able to:
Learning Objectives As a result of this lesson, you will be able to:
When the force of movement is great
: 1. Define lubrication and the types of friction.
: 1. Define lubrication and the types of                enough, the peaks are forced over each friction.                                          other, wearing away both surfaces. Along with the wearing action is generation of heat.
: 2. State the function of the diesel engine lubrication system.
: 2. State the function of the diesel engine            Types of friction are illustrated in Figure 5-2:
: 3. Identify the major components of the typical diesel engine lubrication system and trace the flow path of lube oil through the engine.
lubrication system.
: 4. State the purpose and describe the operation of the lube oil keep warm and pre-lube system(s) as commonly used on nuclear application diesel engines.
5.1.1.2 Sliding Friction Sliding friction
5.1 Lubrication Fundamentals Diesel engine operation involves the movement of assorted shafts, gears, cams, pistons and levers to transmit forces and loads between components within the engine. As with all types of mechanical equipment, where there is relative motion and forces, there is friction.
: 3. Identify the major components of the                occurs where relative motion exists between typical diesel engine lubrication system          two parallel surfaces.         Sliding friction and trace the flow path of lube oil through        presents the greatest resistance to motion, the engine.                                        and the greatest wear and heat generation.
5.1.1 Friction Friction: The force that acts at the surface of contact between two bodies which causes resistance to their relative motion.
: 4. State the purpose and describe the                  5.1.1.3 Rolling Friction In an attempt to operation of the lube oil keep warm and            reduce friction, it was discovered that by pre-lube system(s) as commonly used                placing a spherical or cylindrical rolling on nuclear application diesel engines.            element between two surfaces, friction was substantially reduced. From this concept of rolling friction came the development of ball 5.1 Lubrication Fundamentals                          and roller type bearings.
5.1.1.1 Frictional Surfaces There is no such thing as a perfectly flat or smooth surface. If we take a microscopic look at two surfaces in contact, as in Figure 5-1, each surface consists of a series of peaks and valleys. As one surface attempts to move relative to the other, the peaks contact one another creating a resistance to movement.
Diesel engine operation involves the                  Rolling friction would seem to present movement of assorted shafts, gears, cams,              almost zero motion resistance, wear, and pistons and levers to transmit forces and              heat generation because no sliding motion loads between components within the                    is present. Such is not the case. If we look engine. As with all types of mechanical                closely at a rolling element, Figure 5-3, we equipment, where there is relative motion              see how it and the surface it contacts deform and forces, there is friction.                        slightly when the load is applied. This changes the configuration from one of pure 5.1.1 Friction                                        rolling contact to a combination of rolling and sliding. Since some sliding does occur, Friction: The force that acts at the surface          there is wear and heat generation. Though of contact between two bodies which causes            less than would occur with sliding friction, resistance to their relative motion.                  some friction is still present.
When the force of movement is great enough, the peaks are forced over each other, wearing away both surfaces. Along with the wearing action is generation of heat.
Rev 3/16                                        5-1 of 27                                USNRC HRTD
Types of friction are illustrated in Figure 5-2:
5.1.1.2 Sliding Friction Sliding friction occurs where relative motion exists between two parallel surfaces. Sliding friction presents the greatest resistance to motion, and the greatest wear and heat generation.
5.1.1.3 Rolling Friction In an attempt to reduce friction, it was discovered that by placing a spherical or cylindrical rolling element between two surfaces, friction was substantially reduced. From this concept of rolling friction came the development of ball and roller type bearings.
Rolling friction would seem to present almost zero motion resistance, wear, and heat generation because no sliding motion is present. Such is not the case. If we look closely at a rolling element, Figure 5-3, we see how it and the surface it contacts deform slightly when the load is applied. This changes the configuration from one of pure rolling contact to a combination of rolling and sliding. Since some sliding does occur, there is wear and heat generation. Though less than would occur with sliding friction, some friction is still present.  


Emergency Diesel Generator                                                   Engine Lubrication System parallel surfaces as before. Oil is supplied 5.1.1.4 Fluid Friction The third type of           to the bearing through the hole in the top.
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-2 of 27 USNRC HRTD 5.1.1.4 Fluid Friction The third type of friction is that which occurs when a solid body moves against a fluid. As the body moves, the fluid shears in layers as it moves away from the body. Fluid friction offers the least resistance to motion with a minimum of wear and heat generation.
friction is that which occurs when a solid body moves against a fluid. As the body               With the shaft stationary, it rests in the moves, the fluid shears in layers as it moves         bearing as shown. There is metal-to-metal away from the body. Fluid friction offers the         contact but with no motion, no wear, nor least resistance to motion with a minimum of         heat build-up.
5.1.2 Lubrication Lubrication is the process whereby sliding friction and rolling friction are converted to fluid friction by placing a viscous film between the two surfaces. With a film of sufficient thickness, the two surfaces are separated and no contact occurs.
wear and heat generation.
5.1.2.1 Laminar Action As shown in Figure 5-4, when the two surfaces are separated by the fluid film and relative motion occurs, the lubricant separates or shears in layers. With this laminar action, fluid friction is the result of the fluid layers moving against each other and not the two solid surfaces.
Initial rotation of the shaft causes it to climb 5.1.2 Lubrication                                     the bearing as shown in middle diagram of Figure 5-6. As the climbing action begins, Lubrication is the process whereby sliding           the oil is pushed into the space between the friction and rolling friction are converted to        shaft and bearing due to the oils ability to fluid friction by placing a viscous film             adhere to both surfaces. The action of the between the two surfaces. With a film of             oil separates the two components, creating sufficient thickness, the two surfaces are           a film of lubrication.
5.1.2.2 Wedge Formation When lubrication is applied between two surfaces which are not parallel and relative motion occurs, a wedge of lubrication is formed. As shown in Figure 5-5, the layers of lubrication are forced through a narrowing space between the two surfaces. This creates an upward force which supports the loads imposed on the shaft while keeping the two surfaces separated.
separated and no contact occurs.
5.1.2.3 Shaft and Bearing The situation shown in Figure 5-6 is typical of a crankshaft and bearing. The diameter of the shaft is slightly smaller than the bore of the bearing.
As the shaft comes up to operational speed, 5.1.2.1 Laminar Action As shown in                 a high pressure wedge is formed, supporting Figure 5-4, when the two surfaces are                 the shaft while preventing metal-to-metal separated by the fluid film and relative             contact. This high pressure area is referred motion occurs, the lubricant separates or             to as a hydrodynamic oil film.
This creates an oil clearance and non-parallel surfaces as before. Oil is supplied to the bearing through the hole in the top.
shears in layers. With this laminar action, fluid friction is the result of the fluid layers     5.1.3 Lubricants moving against each other and not the two solid surfaces.                                       The fluid used to create the separation of internal components of emergency diesel 5.1.2.2 Wedge Formation When                       generators is most frequently a lubricating lubrication is applied between two surfaces           oil specifically formulated to provide long which are not parallel and relative motion           engine life and maximum reliability.
With the shaft stationary, it rests in the bearing as shown. There is metal-to-metal contact but with no motion, no wear, nor heat build-up.
occurs, a wedge of lubrication is formed. As shown in Figure 5-5, the layers of lubrication       5.1.3.1 Lubricant Functions  In order to are forced through a narrowing space                 ensure reliable operation, diesel engine between the two surfaces. This creates an             lubricants must perform four functions.
Initial rotation of the shaft causes it to climb the bearing as shown in middle diagram of Figure 5-6. As the climbing action begins, the oil is pushed into the space between the shaft and bearing due to the oils ability to adhere to both surfaces. The action of the oil separates the two components, creating a film of lubrication.
upward force which supports the loads imposed on the shaft while keeping the two
As the shaft comes up to operational speed, a high pressure wedge is formed, supporting the shaft while preventing metal-to-metal contact. This high pressure area is referred to as a hydrodynamic oil film.
* Provide a film of lubricant between the surfaces separated.                                        moving parts of the engine to prevent metal-to-metal contact, and wear.
5.1.3 Lubricants The fluid used to create the separation of internal components of emergency diesel generators is most frequently a lubricating oil specifically formulated to provide long engine life and maximum reliability.
5.1.2.3 Shaft and Bearing The situation shown in Figure 5-6 is typical of a crankshaft
5.1.3.1 Lubricant Functions In order to ensure reliable operation, diesel engine lubricants must perform four functions.
* Create an oil film between the piston and bearing. The diameter of the shaft is                 rings and cylinder wall to ensure a gas slightly smaller than the bore of the bearing.            tight seal, thereby preventing blow-by.
* Provide a film of lubricant between the moving parts of the engine to prevent metal-to-metal contact, and wear.
This creates an oil clearance and non-Rev 3/16                                      5-2 of 27                                USNRC HRTD
* Create an oil film between the piston rings and cylinder wall to ensure a gas tight seal, thereby preventing blow-by.  


Emergency Diesel Generator                                               Engine Lubrication System
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-3 of 27 USNRC HRTD
* Remove and dissipate heat from inside
* Remove and dissipate heat from inside the engine, primarily that portion of the heat of internal combustion not removed in the exhaust stream, or cooled by the incoming air charge. This heat is then transferred out of the system via the lube oil heat exchanger.
* Oxidation Resistance  When oil is the engine, primarily that portion of the           subjected      to      extremely      high heat of internal combustion not removed             temperatures such as those of the in the exhaust stream, or cooled by the              pistons, rings and cylinder walls, the incoming air charge. This heat is then               hydrocarbons in the oil combine with the transferred out of the system via the lube           oxygen in the air to produce highly oil heat exchanger.                                 corrosive acids which tend to form gum or lacquer type deposits on the engines
* Help keep the internal surfaces of the engine clean, by carrying away soot and other contaminants.
* Help keep the internal surfaces of the               internal components.
5.1.3.2 Properties of Lubricants For a lubricant to perform the functions listed above, it must possess certain properties.
engine clean, by carrying away soot and other contaminants.                                 If allowed to build up, these deposits can cause corrosive damage to engine parts 5.1.3.2 Properties of Lubricants For a               and lead to sticking of piston rings and lubricant to perform the functions listed               valves. To combat the problems of above, it must possess certain properties.             oxidation, specific chemicals are added to the engine oil which reduces the
* Viscosity The ability of a lubricant (such as oil) to maintain a fluid film between two surfaces when acted upon by load or force. Viscosity is a measure of the oils resistance to flow. The thicker the oil, the higher its viscosity.
* Viscosity The ability of a lubricant               tendency of the hydrocarbons to (such as oil) to maintain a fluid film               combine with oxygen.
* Viscosity Index The viscosity of an oil is affected by temperature. As the oil temperature increases, the viscosity decreases. Viscosity index (VI) is a measure of the ability of the oil to resist the effects of temperature. An oil with a high viscosity index is less subject to change due to temperature than an oil with a low VI. However, manufacturers of very large diesel engines such as used in nuclear plant EDGs recommend multi-viscosity lubricants NOT be used.
between two surfaces when acted upon by load or force. Viscosity is a measure             The terms usually associated with of the oils resistance to flow. The thicker         oxidation resistance are the TBN and the oil, the higher its viscosity.                   TAN numbers. These are obtained when oil is analyzed. An oil in good
* Pour Point Refers to the temperature at which the oil is considered to be too thick to flow. Since nuclear class diesels are housed in a controlled environment that often has supplemental heat to prevent very low temperatures, lube oil pour point is normally a minor concern.
* Viscosity Index The viscosity of an oil           condition has a high TBN (Total Base is affected by temperature. As the oil               Number). As oxidation builds up the temperature increases, the viscosity                 TBN goes down and the TAN (Total Acid decreases. Viscosity index (VI) is a                 Number) goes up. The oil should be measure of the ability of the oil to resist         changed when the TAN becomes larger the effects of temperature. An oil with a           than the TBN.
* Oxidation Resistance When oil is subjected to extremely high temperatures such as those of the pistons, rings and cylinder walls, the hydrocarbons in the oil combine with the oxygen in the air to produce highly corrosive acids which tend to form gum or lacquer type deposits on the engines internal components.
high viscosity index is less subject to change due to temperature than an oil             Some units require lubricating oils that have with a low VI. However, manufacturers             certain unique properties, such as for EMD of very large diesel engines such as             engines with silver conrod / wrist pin used in nuclear plant EDGs recommend             bushings.      Only the manufacturers multi-viscosity lubricants NOT be used.          recommended lube oil should be used in such units, to assure proper performance.
If allowed to build up, these deposits can cause corrosive damage to engine parts and lead to sticking of piston rings and valves. To combat the problems of oxidation, specific chemicals are added to the engine oil which reduces the tendency of the hydrocarbons to combine with oxygen.
* Pour Point Refers to the temperature at which the oil is considered to be too         For highly turbocharged engines, naphthene thick to flow. Since nuclear class diesels       base stock lubricants are recommended, as are housed in a controlled environment            opposed to paraffin based lubricants. While that often has supplemental heat to              paraffinic lubricants tend to be better at prevent very low temperatures, lube oil          lubrication, the paraffin tends to form more pour point is normally a minor concern.          deposits within the engine and turbocharger.
The terms usually associated with oxidation resistance are the TBN and TAN numbers. These are obtained when oil is analyzed. An oil in good condition has a high TBN (Total Base Number). As oxidation builds up the TBN goes down and the TAN (Total Acid Number) goes up. The oil should be changed when the TAN becomes larger than the TBN.
Rev 3/16                                      5-3 of 27                              USNRC HRTD
Some units require lubricating oils that have certain unique properties, such as for EMD engines with silver conrod/wrist pin bushings.
Only the manufacturers recommended lube oil should be used in such units, to assure proper performance.
For highly turbocharged engines, naphthene base stock lubricants are recommended, as opposed to paraffin based lubricants. While paraffinic lubricants tend to be better at lubrication, the paraffin tends to form more deposits within the engine and turbocharger.  


Emergency Diesel Generator                                               Engine Lubrication System 5.2 Lubrication Systems                             Rotation of the gears as shown creates a partial vacuum at the suction side of the Regardless of engine type, the lubrication         pump. This vacuum draws oil from the lube system must provide an adequate supply of           oil sump into the pump where the oil is clean, cool lubricating oil to all key engine       trapped by the gears. Oil is carried around components. A typical engine lubrication           the pump housing to the discharge side. As system is shown in Figure 5-7.                     the gears mesh, the oil is forced out of the housing creating flow needed for engine 5.2.1 Lube Oil Sump                                 lubrication. Pressure is created by the downstream resistance to flow.
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-4 of 27 USNRC HRTD 5.2 Lubrication Systems Regardless of engine type, the lubrication system must provide an adequate supply of clean, cool lubricating oil to all key engine components. A typical engine lubrication system is shown in Figure 5-7.
The lube oil sump stores a sufficient quantity (e.g. 800 gallons) of lubricating oil to meet       5.2.3 Lube Oil Strainers operating needs of the engine. It provides a place where any solids and water in the             Most larger engines are equipped with lube system can separate out while letting any           oil strainers. These are similar to lube oil entrapped air vent off. Depending on the           filters except theyre intended to filter (strain) engines design, there are two types of lube       out larger particles that could damage oil sumps which may be encountered.                 engine parts, particularly main bearings and other close clearance parts. The strainer is 5.2.1.1 Wet Sump In the wet sump                 usually rated to take out particles larger than system, the lube oil sump is the integral part     20  50 micron in size. All the oil going to of the engine directly below the crankshaft.        the engine passes through the strainer.
5.2.1 Lube Oil Sump The lube oil sump stores a sufficient quantity (e.g. 800 gallons) of lubricating oil to meet operating needs of the engine. It provides a place where any solids and water in the system can separate out while letting any entrapped air vent off. Depending on the engines design, there are two types of lube oil sumps which may be encountered.
The sump in this case is referred to as an oil pan or crankcase and is attached to the             Oil from the lube oil pump enters the strainer engine base or block assembly. Oil, having          housing, either before or after the oil has passed through the engine, returns to the          been cooled. Some units have two strainer sump by gravity.                                    units and valving so strainer elements can be removed for cleaning while the engine is 5.2.1.2 Dry Sump  With a dry sump, the            running. The valve should be set to use only oil is stored in one or two separate tanks          one strainer element at a time, thereby located a short distance from the engine. Oil      reserving the other for immediate use if a that has passed through the engine drains          problem occurs. The system should never back to the engine base and returns to the          be able to bypass the strainer elements.
5.2.1.1 Wet Sump In the wet sump system, the lube oil sump is the integral part of the engine directly below the crankshaft.
remote oil sump by gravity.
The sump in this case is referred to as an oil pan or crankcase and is attached to the engine base or block assembly. Oil, having passed through the engine, returns to the sump by gravity.
5.2.4 Lube Oil Filters (Figure 5-9) 5.2.2 Lube Oil Pump (Figure 5-8)
5.2.1.2 Dry Sump With a dry sump, the oil is stored in one or two separate tanks located a short distance from the engine. Oil that has passed through the engine drains back to the engine base and returns to the remote oil sump by gravity.
Lube oil filters, typically rated at 5-10 The lube oil pump is usually a positive            microns, clean the oil by removing any solid displacement gear pump mounted on and              particulates that develop during engine driven by the engine accessory drive. It            operation. These filters usually consist of draws suction from the sump and supplies            replaceable elements with a paper or fibrous the oil through a set of strainers and / or        type media. Oil pressure drop across the filters to the engine main lube oil header.        filter is a good indication of its condition.
5.2.2 Lube Oil Pump (Figure 5-8)
Rev 3/16                                    5-4 of 27                                USNRC HRTD
The lube oil pump is usually a positive displacement gear pump mounted on and driven by the engine accessory drive. It draws suction from the sump and supplies the oil through a set of strainers and/or filters to the engine main lube oil header.
Rotation of the gears as shown creates a partial vacuum at the suction side of the pump. This vacuum draws oil from the lube oil sump into the pump where the oil is trapped by the gears. Oil is carried around the pump housing to the discharge side. As the gears mesh, the oil is forced out of the housing creating flow needed for engine lubrication. Pressure is created by the downstream resistance to flow.
5.2.3 Lube Oil Strainers Most larger engines are equipped with lube oil strainers. These are similar to lube oil filters except theyre intended to filter (strain) out larger particles that could damage engine parts, particularly main bearings and other close clearance parts. The strainer is usually rated to take out particles larger than 20 50 micron in size. All the oil going to the engine passes through the strainer.
Oil from the lube oil pump enters the strainer housing, either before or after the oil has been cooled. Some units have two strainer units and valving so strainer elements can be removed for cleaning while the engine is running. The valve should be set to use only one strainer element at a time, thereby reserving the other for immediate use if a problem occurs. The system should never be able to bypass the strainer elements.
5.2.4 Lube Oil Filters (Figure 5-9)
Lube oil filters, typically rated at 5-10 microns, clean the oil by removing any solid particulates that develop during engine operation. These filters usually consist of replaceable elements with a paper or fibrous type media. Oil pressure drop across the filter is a good indication of its condition.  


Emergency Diesel Generator                                                   Engine Lubrication System Very often the lube oil filter does not filter all     Some engines such as the Fairbanks Morse of the engine oil and may also be run along           Pielstick engines have a separate lube oil with the keep warm system during periods               header system that supplies lubricating oil to when the engine is not running. The filter is         the valve rocker assemblies located in the intended to take out the very fine particle           cylinder head covers. This separate system such as the soot load that accumulates in           receives oil from the main lubrication system the oil sump. These particles will pass               but has a separate tank to store the oil along through the engine without doing damage               with a separate pumping system. In this but it is desirable to remove them as, they           way, oil that might become contaminated contribute to buildup of acids and lacquers           with water or sediments, etc. is not returned to the main lube oil system.
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-5 of 27 USNRC HRTD Very often the lube oil filter does not filter all of the engine oil and may also be run along with the keep warm system during periods when the engine is not running. The filter is intended to take out the very fine particle such as the soot load that accumulates in the oil sump. These particles will pass through the engine without doing damage but it is desirable to remove them as, they contribute to buildup of acids and lacquers The lube oil filter may also be duplexed with valving to allow the filters elements to be changed out while the unit is in operation.
The lube oil filter may also be duplexed with valving to allow the filters elements to be           5.2.7 Pressure Relief Valve (Figure 5-11) changed out while the unit is in operation.
Most filter elements are throw-away types, while others may be cleaned or refurbished.
Most filter elements are throw-away types,             Many engines use a simple spring-loaded while others may be cleaned or refurbished.           pressure relief valve located on the lube oil pump or at the downstream end of the main 5.2.5 Lube Oil Cooler (Figure 5-10)                   oil header. This valve limits oil pressure by opening when the pressure exceeds a As oil travels through the engine it picks up         specified value.
5.2.5 Lube Oil Cooler (Figure 5-10)
heat from various engine components such as pistons, piston rings, bearings, cams, and         Lube oil pressure from the main oil header valve operating mechanism. If this heat is            or pump is applied to the bottom of the valve allowed to build up, the oil will eventually          as shown in Figure 5-11. The maximum overheat, leading to chemical breakdown                lube oil pressure is set by adjusting the pre-and loss of lubricating ability.                      load of the spring which acts to hold the valve closed. When the lube oil pressure The lube oil cooler removes this excess heat          exceeds the force of the spring, the valve and transfers it to a suitable cooling medium          lifts and the excess pressure is returned to such as the engine jacket water cooling                the lube oil sump.
As oil travels through the engine it picks up heat from various engine components such as pistons, piston rings, bearings, cams, and valve operating mechanism. If this heat is allowed to build up, the oil will eventually overheat, leading to chemical breakdown and loss of lubricating ability.
system. The cooler is normally a shell and tube type with cooling water passing through          The opening pressure and rated flow for the the tubes while oil, also in the shell, passes        valve is determined by the engine over the outside of the tubes.                        manufacturer to protect its lube oil system from over-pressurization, particularly during 5.2.6 Lube Oil Header                                  cold starts when the oil temperature is low and oil viscosity is high.
The lube oil cooler removes this excess heat and transfers it to a suitable cooling medium such as the engine jacket water cooling system. The cooler is normally a shell and tube type with cooling water passing through the tubes while oil, also in the shell, passes over the outside of the tubes.
The lube oil header or headers, along with internal and external piping, deliver lube oil        5.2.8 Pressure Regulating Valve to all the critical engine components.                        (Figure 5-12)
5.2.6 Lube Oil Header The lube oil header or headers, along with internal and external piping, deliver lube oil to all the critical engine components.
System ancillary piping is typically designated ANSI Class 33, designed for                Some larger engines may use a spool type seismic loading.                                      pressure regulating valve at the inlet to the Rev 3/16                                        5-5 of 27                              USNRC HRTD
System ancillary piping is typically designated ANSI Class 33, designed for seismic loading.
Some engines such as the Fairbanks Morse Pielstick engines have a separate lube oil header system that supplies lubricating oil to the valve rocker assemblies located in the cylinder head covers. This separate system receives oil from the main lubrication system but has a separate tank to store the oil along with a separate pumping system. In this way, oil that might become contaminated with water or sediments, etc. is not returned to the main lube oil system.
5.2.7 Pressure Relief Valve (Figure 5-11)
Many engines use a simple spring-loaded pressure relief valve located on the lube oil pump or at the downstream end of the main oil header. This valve limits oil pressure by opening when the pressure exceeds a specified value.
Lube oil pressure from the main oil header or pump is applied to the bottom of the valve as shown in Figure 5-11. The maximum lube oil pressure is set by adjusting the pre-load of the spring which acts to hold the valve closed. When the lube oil pressure exceeds the force of the spring, the valve lifts and the excess pressure is returned to the lube oil sump.
The opening pressure and rated flow for the valve is determined by the engine manufacturer to protect its lube oil system from over-pressurization, particularly during cold starts when the oil temperature is low and oil viscosity is high.
5.2.8 Pressure Regulating Valve (Figure 5-12)
Some larger engines may use a spool type pressure regulating valve at the inlet to the  


Emergency Diesel Generator                                             Engine Lubrication System main oil header. This type valve responds         Figure 5-13 shows a basic lube oil system to flow and pressure demands to maintain a         that includes the pre-lube and keepwarm constant oil supply to the engine or its           system components for a typical engine.
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-6 of 27 USNRC HRTD main oil header. This type valve responds to flow and pressure demands to maintain a constant oil supply to the engine or its accessories that need oil pressure limited.
accessories that need oil pressure limited.
Lube oil under pressure enters through the sleeve near the center of the spool valve.
5.2.9.2 Pre-lube/KeepWarm Pump  The Lube oil under pressure enters through the         pre-lube or keepwarm pump is an sleeve near the center of the spool valve.         electrically driven, positive displacement This pressure is also directed to the sensing     pump which draws suction from the lube oil chamber where it acts against the end of the       sump and supplies oil to the main lube oil spool valve. The desired lube oil pressure         header and other selected points.
This pressure is also directed to the sensing chamber where it acts against the end of the spool valve. The desired lube oil pressure for the engine is set by pre-loading the spool valve spring with the adjusting screw. As oil pressure reaches the set-point, pressure overcomes the spring force, causing the spool valve to move to the right. As it does, the valve opens to allow excess oil pressure to bypass through the ports at either end of the sleeve and return to the oil sump.
for the engine is set by pre-loading the spool valve spring with the adjusting screw. As oil     A relief valve is provided to protect the pressure reaches the set-point, pressure           system from over-pressurization. Metering overcomes the spring force, causing the           valves are often installed at specific spool valve to move to the right. As it does,      locations such as the turbocharger oil inlet, the valve opens to allow excess oil pressure       to prevent localized flooding.
5.2.9 Pre-lube/Keep-Warm-System (Figure 5-13)
to bypass through the ports at either end of the sleeve and return to the oil sump.             5.2.9.1 KeepWarm Heater  To further protect the engine during startup, a 5.2.9 Pre-lube / Keep-Warm-System                 thermostatically controlled immersion type (Figure 5-13)                             heater is placed either in the lube oil sump or in a bypass tank. This heater maintains When an engine is shut down or in standby         the lubricating oil at or near its normal mode, most of the lubricating oil drains away     operating temperature.
When an engine is shut down or in standby mode, most of the lubricating oil drains away from engine components and returns to the lube oil sump. Therefore, when first started, there is minimal lubrication available to protect vital components. It takes time for the lube system to develop the required pressure and flow.
from engine components and returns to the lube oil sump. Therefore, when first started,     If the keepwarm heater becomes there is minimal lubrication available to         inoperable, the diesel generator is not protect vital components. It takes time for       degraded as long as the engine lubricating the lube system to develop the required           oil temperature remains above the minimum pressure and flow.                                 acceptable temperature specified by the manufacturer for operability (e.g. greater The lube oil pre-lube / keepwarm system           than 110oF).
The lube oil pre-lube/keepwarm system provides a metered flow of temperature-controlled oil to selected engine components. This reduces the wear and damage 'dry' starts can cause. Oil flow is metered to prevent excess oil from flooding areas of the engine such as cylinder heads, or upper pistons on the opposed piston engine. Excess oil flow through engine bearings, when theyre stationary, can erode grooves or channels in precision bearing surfaces, as they are fairly soft.
provides a metered flow of temperature-controlled     oil   to   selected   engine     5.2.9.3 Pre-lube / KeepWarm Filters and components. This reduces the wear and             Strainers  Strainers and filters similar to damage 'dry' starts can cause. Oil flow is         those used in the main lubrication oil metered to prevent excess oil from flooding       systems are also installed in the pre-areas of the engine such as cylinder heads,       lube/keepwarm system to protect the or upper pistons on the opposed piston             engine components from damage by engine. Excess oil flow through engine             abrasive particulates.
Figure 5-13 shows a basic lube oil system that includes the pre-lube and keepwarm system components for a typical engine.
bearings, when theyre stationary, can erode grooves or channels in precision bearing           5.2.9.4 Check Valve - The check valve is surfaces, as they are fairly soft.                installed to prevent the flow of main Rev 3/16                                    5-6 of 27                            USNRC HRTD
5.2.9.2 Pre-lube/KeepWarm Pump The pre-lube or keepwarm pump is an electrically driven, positive displacement pump which draws suction from the lube oil sump and supplies oil to the main lube oil header and other selected points.
A relief valve is provided to protect the system from over-pressurization. Metering valves are often installed at specific locations such as the turbocharger oil inlet, to prevent localized flooding.
5.2.9.1 KeepWarm Heater To further protect the engine during startup, a thermostatically controlled immersion type heater is placed either in the lube oil sump or in a bypass tank. This heater maintains the lubricating oil at or near its normal operating temperature.
If the keepwarm heater becomes inoperable, the diesel generator is not degraded as long as the engine lubricating oil temperature remains above the minimum acceptable temperature specified by the manufacturer for operability (e.g. greater than 110oF).
5.2.9.3 Pre-lube/KeepWarm Filters and Strainers Strainers and filters similar to those used in the main lubrication oil systems are also installed in the pre-lube/keepwarm system to protect the engine components from damage by abrasive particulates.
5.2.9.4 Check Valve - The check valve is installed to prevent the flow of main  


Emergency Diesel Generator                                               Engine Lubrication System lubrication oil into the pre-lube / keepwarm         the crankcase. Since there is also air in the system when the engine is operating and             crankcase, it can become a combustible the system is shut down.                             mixture in the crankcase. Then, if a hot spot develops such as a hot bearing, this could 5.2.9.5 System Operation - The pre-lube/             ignite the vapor-air mixture and cause an keepwarm system is operational during the           explosion within the crankcase.
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-7 of 27 USNRC HRTD lubrication oil into the pre-lube/keepwarm system when the engine is operating and the system is shut down.
periods when the engine is in the standby mode. An engine start causes the system to          The crankcase must be strong enough to be de-energized and, after the engine is             withstand such an explosion. But, it is also shut down, the system is again energized,           desirable to mitigate the possibility of such via thermostatic controls.                           an explosion. This is generally done by venting the crankcase so that vapors will not Some EDGs have separate pre-lube and                 build up to the point of becoming a keepwarm systems. The keepwarm system               significant combustible mixture. On most provides metered, temperature-controlled oil         large engines, the crankcase is put under a at all times when the engine is in standby.         slight vacuum by having a connection on the The separate pre-lube system employs a full         crankcase which is connected to a source of flow pre-lube pump manually activated for a         vacuum. This vacuum may be provided by short period prior to a manual engine start.        an ejector system or by a motor driven blower / pump.
5.2.9.5 System Operation - The pre-lube/
The Fairbanks Morse Opposed Piston (OP) engine has a keepwarm system designed to             Also, there are combustion gases entering keep lube oil from pooling above the upper           the crankcase from imperfect sealing of the piston, where it might leak down past the rings     combustion space, at the junction of piston and cause hydraulic lock. The system has             rings to cylinder wall. As the piston rings special controls that supply warm lube oil to       wear over time, the volume of combustion the lower crankshaft but not the upper crank.        products entering the crankcase increases.
keepwarm system is operational during the periods when the engine is in the standby mode. An engine start causes the system to be de-energized and, after the engine is shut down, the system is again energized, via thermostatic controls.
(This is accomplished by pressure limiting.)         Some of the elements in these blow-by Shortly before a planned start the local control     gases may be combustible.
Some EDGs have separate pre-lube and keepwarm systems. The keepwarm system provides metered, temperature-controlled oil at all times when the engine is in standby.
panel operator can manually toggle a switch to pre-lube the upper crankshaft. In the event       Crankcase vacuum should be routinely of an unplanned (ESF) start, the upper OP           monitored. Keeping the crankcase under a crankshaft is not pre-lubed.                         slight vacuum (0.5 to 1.5 inches of water) has two beneficial aspects:
The separate pre-lube system employs a full flow pre-lube pump manually activated for a short period prior to a manual engine start.
5.3 Crankcase Vacuum
The Fairbanks Morse Opposed Piston (OP) engine has a keepwarm system designed to keep lube oil from pooling above the upper piston, where it might leak down past the rings and cause hydraulic lock. The system has special controls that supply warm lube oil to the lower crankshaft but not the upper crank.
: 1. Air is drawn into the crankcase through The cylinders of most engines are not                    clearances such as engine end bearings intentionally fed lube oil. The system relies            and incompletely sealed gaskets such as on oil being splashed onto the lower end of              at the crankcase cover doors. This draft the cylinders by the flailing of oil off the            of air helps prevent lube oil from leaking crankshaft and connecting rods or by the                out of the crankcase at those same drain down from the pistons. This flailing              locations.
(This is accomplished by pressure limiting.)
also results in the build-up of oil vapors in Rev 3/16                                      5-7 of 27                              USNRC HRTD
Shortly before a planned start the local control panel operator can manually toggle a switch to pre-lube the upper crankshaft. In the event of an unplanned (ESF) start, the upper OP crankshaft is not pre-lubed.
5.3 Crankcase Vacuum The cylinders of most engines are not intentionally fed lube oil. The system relies on oil being splashed onto the lower end of the cylinders by the flailing of oil off the crankshaft and connecting rods or by the drain down from the pistons. This flailing also results in the build-up of oil vapors in the crankcase. Since there is also air in the crankcase, it can become a combustible mixture in the crankcase. Then, if a hot spot develops such as a hot bearing, this could ignite the vapor-air mixture and cause an explosion within the crankcase.
The crankcase must be strong enough to withstand such an explosion. But, it is also desirable to mitigate the possibility of such an explosion. This is generally done by venting the crankcase so that vapors will not build up to the point of becoming a significant combustible mixture. On most large engines, the crankcase is put under a slight vacuum by having a connection on the crankcase which is connected to a source of vacuum. This vacuum may be provided by an ejector system or by a motor driven blower/pump.
Also, there are combustion gases entering the crankcase from imperfect sealing of the combustion space, at the junction of piston rings to cylinder wall. As the piston rings wear over time, the volume of combustion products entering the crankcase increases.
Some of the elements in these blow-by gases may be combustible.
Crankcase vacuum should be routinely monitored. Keeping the crankcase under a slight vacuum (0.5 to 1.5 inches of water) has two beneficial aspects:
: 1. Air is drawn into the crankcase through clearances such as engine end bearings and incompletely sealed gaskets such as at the crankcase cover doors. This draft of air helps prevent lube oil from leaking out of the crankcase at those same locations.  


Emergency Diesel Generator                                               Engine Lubrication System
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-8 of 27 USNRC HRTD
: 2. Vapors are drawn from the crankcase               The output of this switch, when operated by and exhausted to the atmosphere, often           an increase in crankcase pressure or a through the engine exhaust piping. With         decrease in crankcase vacuum, will initiate air drawn into the crankcase and vapors         an alarm. If multiple sensors are provided, drawn out, the mixture in the crankcase         (testable, and independently alarmed, with is generally kept too lean to ignite. An oil     coincident logic) a shutdown of the unit will mist monitoring system for large engines         occur, unless the EDG is in an emergency has been developed to warn if crankcase         run.
: 2. Vapors are drawn from the crankcase and exhausted to the atmosphere, often through the engine exhaust piping. With air drawn into the crankcase and vapors drawn out, the mixture in the crankcase is generally kept too lean to ignite. An oil mist monitoring system for large engines has been developed to warn if crankcase vapors are approaching a potentially explosive mixture. It has seen service in marine applications but we are not aware of any nuclear applications yet.
vapors are approaching a potentially explosive mixture. It has seen service in       EDG engines are usually provided with marine applications but we are not aware         crankcase explosion relief panels. In the of any nuclear applications yet.                event of an explosion in the crankcase area these spring-loaded devices are pushed The oil vapor drawn from the crankcase is            open automatically (by the pressure) and as generally put through a wire mesh strainer        soon as its relieved they slam shut to which tends to condense some of the oil              prevent fresh air from entering, as that could vapor droplets, and the condensed liquid is          result in another crankcase explosion, or returned to the crankcase.                          fire. Figure 5-18 is a representative device (actually for a larger, marine diesel engine)
The oil vapor drawn from the crankcase is generally put through a wire mesh strainer which tends to condense some of the oil vapor droplets, and the condensed liquid is returned to the crankcase.
The crankcase pressure / vacuum is                  with the simple, spring-loaded design typical generally monitored and used as an                  of those supplied by all manufacturers.
The crankcase pressure/vacuum is generally monitored and used as an indication of a problem in the engine power parts. For instance, failure of a piston or of piston rings usually results in an increase in blow-by of combustion gasses into the crankcase and an increase in crankcase pressure. A switch is mounted on the crankcase to monitor the crankcase pressure. A tripping of the switch then indicates a problem in the engine.
indication of a problem in the engine power parts. For instance, failure of a piston or of      5.4 Bearing Temperature Monitoring piston rings usually results in an increase in blow-by of combustion gasses into the                EDGs engines may be equipped with crankcase and an increase in crankcase              temperature monitoring of the engine main pressure. A switch is mounted on the                bearings, to provide real-time warning of a crankcase to monitor the crankcase                  developing bearing problem. A typical main pressure. A tripping of the switch then              bearing temperature monitoring device, a indicates a problem in the engine.                  thermocouple or resistance-temperature-detector (RTD), is shown in Figure 5-17. It A cross-section of a typical crankcase              should be noted that the temperature sensor pressure / vacuum switch is shown in Figure          does not touch the crankshaft but only 5-16. The large area of the diaphragm is            monitors the temperature of the back of the used to increase the force (force = Pressure        bearing. If the bearing is in the process of times Area) acting on the switch push-rod.          failing, that temperature will increase rapidly As the pressure goes from slightly negative          enough to alert the operator to the problem to slightly positive, the diaphragm pushes          in time to possibly prevent a total failure of the switch pushrod toward the switch                the bearing, or the crankshaft surfaces.
A cross-section of a typical crankcase pressure/vacuum switch is shown in Figure 5-16. The large area of the diaphragm is used to increase the force (force = Pressure times Area) acting on the switch push-rod.
assembly. This closes the switch contacts, causing a crankcase pressure alarm and perhaps initiating an engine shutdown.
As the pressure goes from slightly negative to slightly positive, the diaphragm pushes the switch pushrod toward the switch assembly. This closes the switch contacts, causing a crankcase pressure alarm and perhaps initiating an engine shutdown.
Rev 3/16                                      5-8 of 27                              USNRC HRTD
The output of this switch, when operated by an increase in crankcase pressure or a decrease in crankcase vacuum, will initiate an alarm. If multiple sensors are provided, (testable, and independently alarmed, with coincident logic) a shutdown of the unit will occur, unless the EDG is in an emergency run.
EDG engines are usually provided with crankcase explosion relief panels. In the event of an explosion in the crankcase area these spring-loaded devices are pushed open automatically (by the pressure) and as soon as its relieved they slam shut to prevent fresh air from entering, as that could result in another crankcase explosion, or fire. Figure 5-18 is a representative device (actually for a larger, marine diesel engine) with the simple, spring-loaded design typical of those supplied by all manufacturers.
5.4 Bearing Temperature Monitoring EDGs engines may be equipped with temperature monitoring of the engine main bearings, to provide real-time warning of a developing bearing problem. A typical main bearing temperature monitoring device, a thermocouple or resistance-temperature-detector (RTD), is shown in Figure 5-17. It should be noted that the temperature sensor does not touch the crankshaft but only monitors the temperature of the back of the bearing. If the bearing is in the process of failing, that temperature will increase rapidly enough to alert the operator to the problem in time to possibly prevent a total failure of the bearing, or the crankshaft surfaces.  


Emergency Diesel Generator               Engine Lubrication System Figure 5-1 Frictional Surfaces Rev 3/16                     5-9 of 27             USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-9 of 27 USNRC HRTD Figure 5-1 Frictional Surfaces


Emergency Diesel Generator                             Engine Lubrication System Figure 5-2 Types of Friction Rev 3/16                           5-10 of 27                     USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-10 of 27 USNRC HRTD Figure 5-2 Types of Friction


Emergency Diesel Generator                             Engine Lubrication System Figure 5-3 Rolling Friction Rev 3/16                           5-11 of 27                   USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-11 of 27 USNRC HRTD Figure 5-3 Rolling Friction


Emergency Diesel Generator               Engine Lubrication System Figure 5-4 Laminar Action Rev 3/16                     5-12 of 27             USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-12 of 27 USNRC HRTD Figure 5-4 Laminar Action


Emergency Diesel Generator               Engine Lubrication System Figure 5-5 Wedge Formation Rev 3/16                     5-13 of 27             USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-13 of 27 USNRC HRTD Figure 5-5 Wedge Formation


Emergency Diesel Generator                             Engine Lubrication System Figure 5-6 Shaft and Bearing Rev 3/16                             5-14 of 27                   USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-14 of 27 USNRC HRTD Figure 5-6 Shaft and Bearing


Emergency Diesel Generator               Engine Lubrication System Figure 5-7 Lube Oil Circulating and Cooling System Rev 3/16                     5-15 of 27             USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-15 of 27 USNRC HRTD Figure 5-7 Lube Oil Circulating and Cooling System


Emergency Diesel Generator               Engine Lubrication System Figure 5-9 Lubricating Oil Filters Figure 5-8 Lubricating Oil Pump Rev 3/16                    5-16 of 27              USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-16 of 27 USNRC HRTD Figure 5-9 Lubricating Oil Filters Figure 5-8 Lubricating Oil Pump  


Emergency Diesel Generator               Engine Lubrication System Figure 5-10 Lubricating Oil Cooler Rev 3/16                     5-17 of 27             USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-17 of 27 USNRC HRTD Figure 5-10 Lubricating Oil Cooler


Emergency Diesel Generator                                   Engine Lubrication System Figure 5-11 Pressure Relief Valve Rev 3/16                               5-18 of 27                       USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-18 of 27 USNRC HRTD Figure 5-11 Pressure Relief Valve


Emergency Diesel Generator                                     Engine Lubrication System Figure 5-12 Pressure Regulating Valve Rev 3/16                               5-19 of 27                       USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-19 of 27 USNRC HRTD Figure 5-12 Pressure Regulating Valve


Emergency Diesel Generator               Engine Lubrication System Figure 5-13 Lube Oil System with Keepwarm Added Rev 3/16                     5-20 of 27             USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-20 of 27 USNRC HRTD Figure 5-13 Lube Oil System with Keepwarm Added


Emergency Diesel Generator                                     Engine Lubrication System Figure 5-14 Pielstick Lube Oil Flow Rev 3/16                                 5-21 of 27                       USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-21 of 27 USNRC HRTD Figure 5-14 Pielstick Lube Oil Flow


Emergency Diesel Generator                                     Engine Lubrication System Figure 5-15 Pielstick Valve Rocker Flow Rev 3/16                                 5-22 of 27                       USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-22 of 27 USNRC HRTD Figure 5-15 Pielstick Valve Rocker Flow


Emergency Diesel Generator               Engine Lubrication System Figure 5-16 Crankcase Diaphragm Type Pressure Monitoring Switch Rev 3/16                     5-23 of 27             USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-23 of 27 USNRC HRTD Figure 5-16 Crankcase Diaphragm Type Pressure Monitoring Switch


Emergency Diesel Generator               Engine Lubrication System Figure 5-17 Bearing Temperature Probe Rev 3/16                     5-24 of 27             USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-24 of 27 USNRC HRTD Figure 5-17 Bearing Temperature Probe


Emergency Diesel Generator               Engine Lubrication System Figure 5-18 Crankcase Explosion Relief Device Rev 3/16                     5-25 of 27             USNRC HRTD
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-25 of 27 USNRC HRTD Figure 5-18 Crankcase Explosion Relief Device


Emergency Diesel Generator                                             Engine Lubrication System WALKAROUND SESSION 5                               The instructor will discuss the pre-lube keepwarm oil system and its components.
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-26 of 27 USNRC HRTD WALKAROUND SESSION 5 5.0 ENGINE LUBRICATION SYSTEM Purpose The purpose of this session is to complement classroom instruction of Chapter 5.
5.0 ENGINE LUBRICATION SYSTEM                      The presentation will include the fact that the engine cylinder can become hydraulically Purpose                                            locked so that the engine would not start and engine damage might occur. The cylinder The purpose of this session is              to    test cocks need to be opened to roll the complement classroom instruction            of    engine over prior to all planned starts to Chapter 5.                                        purge cylinders of lube oil and water.
Learning Objectives Upon completion of this lesson you will:
Licensees procedures need to insure the Learning Objectives                                opening and closing of these cocks for standby operation.
* Be familiar with the appearance, location, function, and operation of the lube oil system and its components.
Upon completion of this lesson you will:
5.1 Lube Oil Flow Path The instructor will use the rotatable cutaway OP to show the oil flow paths:
The instructor will discuss the problem of
* From the engines lube oil sump through the engine-driven oil pump to the thermostatic valve then either through the lube oil cooler or directly to the duplex oil strainer/filter
* Be familiar with the appearance,                lube oil accumulation in exhaust manifolds location, function, and operation of the        with seepage and lube oil fires outside the lube oil system and its components.            exhaust manifold near the governor. Also fires inside the exhaust manifold with the 5.1 Lube Oil Flow Path                            possibility of turbocharger damage from the blowtorch effect.
* Into the main lube oil header(s)
The instructor will use the rotatable cutaway OP to show the oil flow paths:                    The instructor will show differences in the 4-stroke cycle engine lube oil flow paths which
* From the header(s) to and from the turbochager back to the engine
* From the engines lube oil sump through        include lubrication of the cylinder head valve the engine-driven oil pump to the              rocker arm assemblies.
* From the header to the main bearing caps then through drilled passages to the crankshaft journals and connecting rod bearings
thermostatic valve then either through the lube oil cooler or directly to the          Based upon typical oil consumption rates for duplex oil strainer/filter                      the OP and ALCO engines, he will tell students how much lube oil the engines will
* Through the connecting rod drilled passages to piston wrist pin bearings through holes into the piston cocktail shaker with its drain back to the sump The instructor will discuss the pre-lube keepwarm oil system and its components.
* Into the main lube oil header(s)                consume at rated load each day / week, how and when lube oil sump level should be
The presentation will include the fact that the engine cylinder can become hydraulically locked so that the engine would not start and engine damage might occur. The cylinder test cocks need to be opened to roll the engine over prior to all planned starts to purge cylinders of lube oil and water.
* From the header(s) to and from the              checked, and how to add lube oil to a turbochager back to the engine                  running engine sump. He will point out the crankcase exhauster location and discuss
Licensees procedures need to insure the opening and closing of these cocks for standby operation.
* From the header to the main bearing            its source of power and its exhaust flow.
The instructor will discuss the problem of lube oil accumulation in exhaust manifolds with seepage and lube oil fires outside the exhaust manifold near the governor. Also fires inside the exhaust manifold with the possibility of turbocharger damage from the blowtorch effect.
caps then through drilled passages to the crankshaft journals and connecting          The instructor will show the location, rod bearings                                    function, and operation of the crankcase sump pressure relief blowout covers and
The instructor will show differences in the 4-stroke cycle engine lube oil flow paths which include lubrication of the cylinder head valve rocker arm assemblies.
* Through the connecting rod drilled how the covers are checked for proper passages to piston wrist pin bearings operation.
Based upon typical oil consumption rates for the OP and ALCO engines, he will tell students how much lube oil the engines will consume at rated load each day/week, how and when lube oil sump level should be checked, and how to add lube oil to a running engine sump. He will point out the crankcase exhauster location and discuss its source of power and its exhaust flow.
through holes into the piston cocktail shaker with its drain back to the sump Rev 3/16                                    5-26 of 27                            USNRC HRTD
The instructor will show the location, function, and operation of the crankcase sump pressure relief blowout covers and how the covers are checked for proper operation.  


Emergency Diesel Generator                             Engine Lubrication System 5.2 Components The instructor will show cutaways and discuss the functioning of the following components:
Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-27 of 27 USNRC HRTD 5.2 Components The instructor will show cutaways and discuss the functioning of the following components:
* Gear-driven lube oil pump
* Gear-driven lube oil pump
* Thermostatic valve
* Thermostatic valve
Line 158: Line 188:
* Brown Boveri turbocharger with its separate oil sump
* Brown Boveri turbocharger with its separate oil sump
* Elliot turbocharger with its engine-supplied lube oil
* Elliot turbocharger with its engine-supplied lube oil
* Piston with oil control rings Rev 3/16                                    5-27 of 27            USNRC HRTD}}
* Piston with oil control rings}}

Latest revision as of 15:12, 19 December 2024

Training Material for E-111 Emergency Diesel Generator Course, Chapter 5 (3-16), Engine Lubrication System
ML20043F656
Person / Time
Issue date: 02/12/2020
From:
Office of the Chief Human Capital Officer, Woodard Corp
To:
Gary Callaway
Shared Package
ML20043F634 List:
References
Download: ML20043F656 (27)
v • d • e


Text

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-1 of 27 USNRC HRTD 5.0 ENGINE LUBRICATION SYSTEM This chapter presents the major components of engine lubrication system and explains how the system is necessary for the reliable operation of the engine.

Learning Objectives As a result of this lesson, you will be able to:

1. Define lubrication and the types of friction.
2. State the function of the diesel engine lubrication system.
3. Identify the major components of the typical diesel engine lubrication system and trace the flow path of lube oil through the engine.
4. State the purpose and describe the operation of the lube oil keep warm and pre-lube system(s) as commonly used on nuclear application diesel engines.

5.1 Lubrication Fundamentals Diesel engine operation involves the movement of assorted shafts, gears, cams, pistons and levers to transmit forces and loads between components within the engine. As with all types of mechanical equipment, where there is relative motion and forces, there is friction.

5.1.1 Friction Friction: The force that acts at the surface of contact between two bodies which causes resistance to their relative motion.

5.1.1.1 Frictional Surfaces There is no such thing as a perfectly flat or smooth surface. If we take a microscopic look at two surfaces in contact, as in Figure 5-1, each surface consists of a series of peaks and valleys. As one surface attempts to move relative to the other, the peaks contact one another creating a resistance to movement.

When the force of movement is great enough, the peaks are forced over each other, wearing away both surfaces. Along with the wearing action is generation of heat.

Types of friction are illustrated in Figure 5-2:

5.1.1.2 Sliding Friction Sliding friction occurs where relative motion exists between two parallel surfaces. Sliding friction presents the greatest resistance to motion, and the greatest wear and heat generation.

5.1.1.3 Rolling Friction In an attempt to reduce friction, it was discovered that by placing a spherical or cylindrical rolling element between two surfaces, friction was substantially reduced. From this concept of rolling friction came the development of ball and roller type bearings.

Rolling friction would seem to present almost zero motion resistance, wear, and heat generation because no sliding motion is present. Such is not the case. If we look closely at a rolling element, Figure 5-3, we see how it and the surface it contacts deform slightly when the load is applied. This changes the configuration from one of pure rolling contact to a combination of rolling and sliding. Since some sliding does occur, there is wear and heat generation. Though less than would occur with sliding friction, some friction is still present.

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-2 of 27 USNRC HRTD 5.1.1.4 Fluid Friction The third type of friction is that which occurs when a solid body moves against a fluid. As the body moves, the fluid shears in layers as it moves away from the body. Fluid friction offers the least resistance to motion with a minimum of wear and heat generation.

5.1.2 Lubrication Lubrication is the process whereby sliding friction and rolling friction are converted to fluid friction by placing a viscous film between the two surfaces. With a film of sufficient thickness, the two surfaces are separated and no contact occurs.

5.1.2.1 Laminar Action As shown in Figure 5-4, when the two surfaces are separated by the fluid film and relative motion occurs, the lubricant separates or shears in layers. With this laminar action, fluid friction is the result of the fluid layers moving against each other and not the two solid surfaces.

5.1.2.2 Wedge Formation When lubrication is applied between two surfaces which are not parallel and relative motion occurs, a wedge of lubrication is formed. As shown in Figure 5-5, the layers of lubrication are forced through a narrowing space between the two surfaces. This creates an upward force which supports the loads imposed on the shaft while keeping the two surfaces separated.

5.1.2.3 Shaft and Bearing The situation shown in Figure 5-6 is typical of a crankshaft and bearing. The diameter of the shaft is slightly smaller than the bore of the bearing.

This creates an oil clearance and non-parallel surfaces as before. Oil is supplied to the bearing through the hole in the top.

With the shaft stationary, it rests in the bearing as shown. There is metal-to-metal contact but with no motion, no wear, nor heat build-up.

Initial rotation of the shaft causes it to climb the bearing as shown in middle diagram of Figure 5-6. As the climbing action begins, the oil is pushed into the space between the shaft and bearing due to the oils ability to adhere to both surfaces. The action of the oil separates the two components, creating a film of lubrication.

As the shaft comes up to operational speed, a high pressure wedge is formed, supporting the shaft while preventing metal-to-metal contact. This high pressure area is referred to as a hydrodynamic oil film.

5.1.3 Lubricants The fluid used to create the separation of internal components of emergency diesel generators is most frequently a lubricating oil specifically formulated to provide long engine life and maximum reliability.

5.1.3.1 Lubricant Functions In order to ensure reliable operation, diesel engine lubricants must perform four functions.

  • Provide a film of lubricant between the moving parts of the engine to prevent metal-to-metal contact, and wear.
  • Create an oil film between the piston rings and cylinder wall to ensure a gas tight seal, thereby preventing blow-by.

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-3 of 27 USNRC HRTD

  • Remove and dissipate heat from inside the engine, primarily that portion of the heat of internal combustion not removed in the exhaust stream, or cooled by the incoming air charge. This heat is then transferred out of the system via the lube oil heat exchanger.
  • Help keep the internal surfaces of the engine clean, by carrying away soot and other contaminants.

5.1.3.2 Properties of Lubricants For a lubricant to perform the functions listed above, it must possess certain properties.

  • Viscosity The ability of a lubricant (such as oil) to maintain a fluid film between two surfaces when acted upon by load or force. Viscosity is a measure of the oils resistance to flow. The thicker the oil, the higher its viscosity.
  • Viscosity Index The viscosity of an oil is affected by temperature. As the oil temperature increases, the viscosity decreases. Viscosity index (VI) is a measure of the ability of the oil to resist the effects of temperature. An oil with a high viscosity index is less subject to change due to temperature than an oil with a low VI. However, manufacturers of very large diesel engines such as used in nuclear plant EDGs recommend multi-viscosity lubricants NOT be used.
  • Pour Point Refers to the temperature at which the oil is considered to be too thick to flow. Since nuclear class diesels are housed in a controlled environment that often has supplemental heat to prevent very low temperatures, lube oil pour point is normally a minor concern.
  • Oxidation Resistance When oil is subjected to extremely high temperatures such as those of the pistons, rings and cylinder walls, the hydrocarbons in the oil combine with the oxygen in the air to produce highly corrosive acids which tend to form gum or lacquer type deposits on the engines internal components.

If allowed to build up, these deposits can cause corrosive damage to engine parts and lead to sticking of piston rings and valves. To combat the problems of oxidation, specific chemicals are added to the engine oil which reduces the tendency of the hydrocarbons to combine with oxygen.

The terms usually associated with oxidation resistance are the TBN and TAN numbers. These are obtained when oil is analyzed. An oil in good condition has a high TBN (Total Base Number). As oxidation builds up the TBN goes down and the TAN (Total Acid Number) goes up. The oil should be changed when the TAN becomes larger than the TBN.

Some units require lubricating oils that have certain unique properties, such as for EMD engines with silver conrod/wrist pin bushings.

Only the manufacturers recommended lube oil should be used in such units, to assure proper performance.

For highly turbocharged engines, naphthene base stock lubricants are recommended, as opposed to paraffin based lubricants. While paraffinic lubricants tend to be better at lubrication, the paraffin tends to form more deposits within the engine and turbocharger.

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-4 of 27 USNRC HRTD 5.2 Lubrication Systems Regardless of engine type, the lubrication system must provide an adequate supply of clean, cool lubricating oil to all key engine components. A typical engine lubrication system is shown in Figure 5-7.

5.2.1 Lube Oil Sump The lube oil sump stores a sufficient quantity (e.g. 800 gallons) of lubricating oil to meet operating needs of the engine. It provides a place where any solids and water in the system can separate out while letting any entrapped air vent off. Depending on the engines design, there are two types of lube oil sumps which may be encountered.

5.2.1.1 Wet Sump In the wet sump system, the lube oil sump is the integral part of the engine directly below the crankshaft.

The sump in this case is referred to as an oil pan or crankcase and is attached to the engine base or block assembly. Oil, having passed through the engine, returns to the sump by gravity.

5.2.1.2 Dry Sump With a dry sump, the oil is stored in one or two separate tanks located a short distance from the engine. Oil that has passed through the engine drains back to the engine base and returns to the remote oil sump by gravity.

5.2.2 Lube Oil Pump (Figure 5-8)

The lube oil pump is usually a positive displacement gear pump mounted on and driven by the engine accessory drive. It draws suction from the sump and supplies the oil through a set of strainers and/or filters to the engine main lube oil header.

Rotation of the gears as shown creates a partial vacuum at the suction side of the pump. This vacuum draws oil from the lube oil sump into the pump where the oil is trapped by the gears. Oil is carried around the pump housing to the discharge side. As the gears mesh, the oil is forced out of the housing creating flow needed for engine lubrication. Pressure is created by the downstream resistance to flow.

5.2.3 Lube Oil Strainers Most larger engines are equipped with lube oil strainers. These are similar to lube oil filters except theyre intended to filter (strain) out larger particles that could damage engine parts, particularly main bearings and other close clearance parts. The strainer is usually rated to take out particles larger than 20 50 micron in size. All the oil going to the engine passes through the strainer.

Oil from the lube oil pump enters the strainer housing, either before or after the oil has been cooled. Some units have two strainer units and valving so strainer elements can be removed for cleaning while the engine is running. The valve should be set to use only one strainer element at a time, thereby reserving the other for immediate use if a problem occurs. The system should never be able to bypass the strainer elements.

5.2.4 Lube Oil Filters (Figure 5-9)

Lube oil filters, typically rated at 5-10 microns, clean the oil by removing any solid particulates that develop during engine operation. These filters usually consist of replaceable elements with a paper or fibrous type media. Oil pressure drop across the filter is a good indication of its condition.

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-5 of 27 USNRC HRTD Very often the lube oil filter does not filter all of the engine oil and may also be run along with the keep warm system during periods when the engine is not running. The filter is intended to take out the very fine particle such as the soot load that accumulates in the oil sump. These particles will pass through the engine without doing damage but it is desirable to remove them as, they contribute to buildup of acids and lacquers The lube oil filter may also be duplexed with valving to allow the filters elements to be changed out while the unit is in operation.

Most filter elements are throw-away types, while others may be cleaned or refurbished.

5.2.5 Lube Oil Cooler (Figure 5-10)

As oil travels through the engine it picks up heat from various engine components such as pistons, piston rings, bearings, cams, and valve operating mechanism. If this heat is allowed to build up, the oil will eventually overheat, leading to chemical breakdown and loss of lubricating ability.

The lube oil cooler removes this excess heat and transfers it to a suitable cooling medium such as the engine jacket water cooling system. The cooler is normally a shell and tube type with cooling water passing through the tubes while oil, also in the shell, passes over the outside of the tubes.

5.2.6 Lube Oil Header The lube oil header or headers, along with internal and external piping, deliver lube oil to all the critical engine components.

System ancillary piping is typically designated ANSI Class 33, designed for seismic loading.

Some engines such as the Fairbanks Morse Pielstick engines have a separate lube oil header system that supplies lubricating oil to the valve rocker assemblies located in the cylinder head covers. This separate system receives oil from the main lubrication system but has a separate tank to store the oil along with a separate pumping system. In this way, oil that might become contaminated with water or sediments, etc. is not returned to the main lube oil system.

5.2.7 Pressure Relief Valve (Figure 5-11)

Many engines use a simple spring-loaded pressure relief valve located on the lube oil pump or at the downstream end of the main oil header. This valve limits oil pressure by opening when the pressure exceeds a specified value.

Lube oil pressure from the main oil header or pump is applied to the bottom of the valve as shown in Figure 5-11. The maximum lube oil pressure is set by adjusting the pre-load of the spring which acts to hold the valve closed. When the lube oil pressure exceeds the force of the spring, the valve lifts and the excess pressure is returned to the lube oil sump.

The opening pressure and rated flow for the valve is determined by the engine manufacturer to protect its lube oil system from over-pressurization, particularly during cold starts when the oil temperature is low and oil viscosity is high.

5.2.8 Pressure Regulating Valve (Figure 5-12)

Some larger engines may use a spool type pressure regulating valve at the inlet to the

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-6 of 27 USNRC HRTD main oil header. This type valve responds to flow and pressure demands to maintain a constant oil supply to the engine or its accessories that need oil pressure limited.

Lube oil under pressure enters through the sleeve near the center of the spool valve.

This pressure is also directed to the sensing chamber where it acts against the end of the spool valve. The desired lube oil pressure for the engine is set by pre-loading the spool valve spring with the adjusting screw. As oil pressure reaches the set-point, pressure overcomes the spring force, causing the spool valve to move to the right. As it does, the valve opens to allow excess oil pressure to bypass through the ports at either end of the sleeve and return to the oil sump.

5.2.9 Pre-lube/Keep-Warm-System (Figure 5-13)

When an engine is shut down or in standby mode, most of the lubricating oil drains away from engine components and returns to the lube oil sump. Therefore, when first started, there is minimal lubrication available to protect vital components. It takes time for the lube system to develop the required pressure and flow.

The lube oil pre-lube/keepwarm system provides a metered flow of temperature-controlled oil to selected engine components. This reduces the wear and damage 'dry' starts can cause. Oil flow is metered to prevent excess oil from flooding areas of the engine such as cylinder heads, or upper pistons on the opposed piston engine. Excess oil flow through engine bearings, when theyre stationary, can erode grooves or channels in precision bearing surfaces, as they are fairly soft.

Figure 5-13 shows a basic lube oil system that includes the pre-lube and keepwarm system components for a typical engine.

5.2.9.2 Pre-lube/KeepWarm Pump The pre-lube or keepwarm pump is an electrically driven, positive displacement pump which draws suction from the lube oil sump and supplies oil to the main lube oil header and other selected points.

A relief valve is provided to protect the system from over-pressurization. Metering valves are often installed at specific locations such as the turbocharger oil inlet, to prevent localized flooding.

5.2.9.1 KeepWarm Heater To further protect the engine during startup, a thermostatically controlled immersion type heater is placed either in the lube oil sump or in a bypass tank. This heater maintains the lubricating oil at or near its normal operating temperature.

If the keepwarm heater becomes inoperable, the diesel generator is not degraded as long as the engine lubricating oil temperature remains above the minimum acceptable temperature specified by the manufacturer for operability (e.g. greater than 110oF).

5.2.9.3 Pre-lube/KeepWarm Filters and Strainers Strainers and filters similar to those used in the main lubrication oil systems are also installed in the pre-lube/keepwarm system to protect the engine components from damage by abrasive particulates.

5.2.9.4 Check Valve - The check valve is installed to prevent the flow of main

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-7 of 27 USNRC HRTD lubrication oil into the pre-lube/keepwarm system when the engine is operating and the system is shut down.

5.2.9.5 System Operation - The pre-lube/

keepwarm system is operational during the periods when the engine is in the standby mode. An engine start causes the system to be de-energized and, after the engine is shut down, the system is again energized, via thermostatic controls.

Some EDGs have separate pre-lube and keepwarm systems. The keepwarm system provides metered, temperature-controlled oil at all times when the engine is in standby.

The separate pre-lube system employs a full flow pre-lube pump manually activated for a short period prior to a manual engine start.

The Fairbanks Morse Opposed Piston (OP) engine has a keepwarm system designed to keep lube oil from pooling above the upper piston, where it might leak down past the rings and cause hydraulic lock. The system has special controls that supply warm lube oil to the lower crankshaft but not the upper crank.

(This is accomplished by pressure limiting.)

Shortly before a planned start the local control panel operator can manually toggle a switch to pre-lube the upper crankshaft. In the event of an unplanned (ESF) start, the upper OP crankshaft is not pre-lubed.

5.3 Crankcase Vacuum The cylinders of most engines are not intentionally fed lube oil. The system relies on oil being splashed onto the lower end of the cylinders by the flailing of oil off the crankshaft and connecting rods or by the drain down from the pistons. This flailing also results in the build-up of oil vapors in the crankcase. Since there is also air in the crankcase, it can become a combustible mixture in the crankcase. Then, if a hot spot develops such as a hot bearing, this could ignite the vapor-air mixture and cause an explosion within the crankcase.

The crankcase must be strong enough to withstand such an explosion. But, it is also desirable to mitigate the possibility of such an explosion. This is generally done by venting the crankcase so that vapors will not build up to the point of becoming a significant combustible mixture. On most large engines, the crankcase is put under a slight vacuum by having a connection on the crankcase which is connected to a source of vacuum. This vacuum may be provided by an ejector system or by a motor driven blower/pump.

Also, there are combustion gases entering the crankcase from imperfect sealing of the combustion space, at the junction of piston rings to cylinder wall. As the piston rings wear over time, the volume of combustion products entering the crankcase increases.

Some of the elements in these blow-by gases may be combustible.

Crankcase vacuum should be routinely monitored. Keeping the crankcase under a slight vacuum (0.5 to 1.5 inches of water) has two beneficial aspects:

1. Air is drawn into the crankcase through clearances such as engine end bearings and incompletely sealed gaskets such as at the crankcase cover doors. This draft of air helps prevent lube oil from leaking out of the crankcase at those same locations.

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-8 of 27 USNRC HRTD

2. Vapors are drawn from the crankcase and exhausted to the atmosphere, often through the engine exhaust piping. With air drawn into the crankcase and vapors drawn out, the mixture in the crankcase is generally kept too lean to ignite. An oil mist monitoring system for large engines has been developed to warn if crankcase vapors are approaching a potentially explosive mixture. It has seen service in marine applications but we are not aware of any nuclear applications yet.

The oil vapor drawn from the crankcase is generally put through a wire mesh strainer which tends to condense some of the oil vapor droplets, and the condensed liquid is returned to the crankcase.

The crankcase pressure/vacuum is generally monitored and used as an indication of a problem in the engine power parts. For instance, failure of a piston or of piston rings usually results in an increase in blow-by of combustion gasses into the crankcase and an increase in crankcase pressure. A switch is mounted on the crankcase to monitor the crankcase pressure. A tripping of the switch then indicates a problem in the engine.

A cross-section of a typical crankcase pressure/vacuum switch is shown in Figure 5-16. The large area of the diaphragm is used to increase the force (force = Pressure times Area) acting on the switch push-rod.

As the pressure goes from slightly negative to slightly positive, the diaphragm pushes the switch pushrod toward the switch assembly. This closes the switch contacts, causing a crankcase pressure alarm and perhaps initiating an engine shutdown.

The output of this switch, when operated by an increase in crankcase pressure or a decrease in crankcase vacuum, will initiate an alarm. If multiple sensors are provided, (testable, and independently alarmed, with coincident logic) a shutdown of the unit will occur, unless the EDG is in an emergency run.

EDG engines are usually provided with crankcase explosion relief panels. In the event of an explosion in the crankcase area these spring-loaded devices are pushed open automatically (by the pressure) and as soon as its relieved they slam shut to prevent fresh air from entering, as that could result in another crankcase explosion, or fire. Figure 5-18 is a representative device (actually for a larger, marine diesel engine) with the simple, spring-loaded design typical of those supplied by all manufacturers.

5.4 Bearing Temperature Monitoring EDGs engines may be equipped with temperature monitoring of the engine main bearings, to provide real-time warning of a developing bearing problem. A typical main bearing temperature monitoring device, a thermocouple or resistance-temperature-detector (RTD), is shown in Figure 5-17. It should be noted that the temperature sensor does not touch the crankshaft but only monitors the temperature of the back of the bearing. If the bearing is in the process of failing, that temperature will increase rapidly enough to alert the operator to the problem in time to possibly prevent a total failure of the bearing, or the crankshaft surfaces.

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-9 of 27 USNRC HRTD Figure 5-1 Frictional Surfaces

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-10 of 27 USNRC HRTD Figure 5-2 Types of Friction

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-11 of 27 USNRC HRTD Figure 5-3 Rolling Friction

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-12 of 27 USNRC HRTD Figure 5-4 Laminar Action

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-13 of 27 USNRC HRTD Figure 5-5 Wedge Formation

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-14 of 27 USNRC HRTD Figure 5-6 Shaft and Bearing

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-15 of 27 USNRC HRTD Figure 5-7 Lube Oil Circulating and Cooling System

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-16 of 27 USNRC HRTD Figure 5-9 Lubricating Oil Filters Figure 5-8 Lubricating Oil Pump

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-17 of 27 USNRC HRTD Figure 5-10 Lubricating Oil Cooler

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-18 of 27 USNRC HRTD Figure 5-11 Pressure Relief Valve

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-19 of 27 USNRC HRTD Figure 5-12 Pressure Regulating Valve

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-20 of 27 USNRC HRTD Figure 5-13 Lube Oil System with Keepwarm Added

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-21 of 27 USNRC HRTD Figure 5-14 Pielstick Lube Oil Flow

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-22 of 27 USNRC HRTD Figure 5-15 Pielstick Valve Rocker Flow

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-23 of 27 USNRC HRTD Figure 5-16 Crankcase Diaphragm Type Pressure Monitoring Switch

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-24 of 27 USNRC HRTD Figure 5-17 Bearing Temperature Probe

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-25 of 27 USNRC HRTD Figure 5-18 Crankcase Explosion Relief Device

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-26 of 27 USNRC HRTD WALKAROUND SESSION 5 5.0 ENGINE LUBRICATION SYSTEM Purpose The purpose of this session is to complement classroom instruction of Chapter 5.

Learning Objectives Upon completion of this lesson you will:

  • Be familiar with the appearance, location, function, and operation of the lube oil system and its components.

5.1 Lube Oil Flow Path The instructor will use the rotatable cutaway OP to show the oil flow paths:

  • From the engines lube oil sump through the engine-driven oil pump to the thermostatic valve then either through the lube oil cooler or directly to the duplex oil strainer/filter
  • From the header(s) to and from the turbochager back to the engine
  • From the header to the main bearing caps then through drilled passages to the crankshaft journals and connecting rod bearings
  • Through the connecting rod drilled passages to piston wrist pin bearings through holes into the piston cocktail shaker with its drain back to the sump The instructor will discuss the pre-lube keepwarm oil system and its components.

The presentation will include the fact that the engine cylinder can become hydraulically locked so that the engine would not start and engine damage might occur. The cylinder test cocks need to be opened to roll the engine over prior to all planned starts to purge cylinders of lube oil and water.

Licensees procedures need to insure the opening and closing of these cocks for standby operation.

The instructor will discuss the problem of lube oil accumulation in exhaust manifolds with seepage and lube oil fires outside the exhaust manifold near the governor. Also fires inside the exhaust manifold with the possibility of turbocharger damage from the blowtorch effect.

The instructor will show differences in the 4-stroke cycle engine lube oil flow paths which include lubrication of the cylinder head valve rocker arm assemblies.

Based upon typical oil consumption rates for the OP and ALCO engines, he will tell students how much lube oil the engines will consume at rated load each day/week, how and when lube oil sump level should be checked, and how to add lube oil to a running engine sump. He will point out the crankcase exhauster location and discuss its source of power and its exhaust flow.

The instructor will show the location, function, and operation of the crankcase sump pressure relief blowout covers and how the covers are checked for proper operation.

Emergency Diesel Generator Engine Lubrication System Rev 3/16 5-27 of 27 USNRC HRTD 5.2 Components The instructor will show cutaways and discuss the functioning of the following components:

  • Thermostatic valve
  • Pressure relief valve
  • Duplex filters/strainers
  • Main bearing cap showing drilled oil passages
  • Crankshaft showing drilled oil passages
  • Connecting rod drilled oil passages
  • Piston showing drilled oil passages to the cocktail shaker and its drain back to the lube oil sump
  • Oil cooler
  • Piston with oil control rings
Retrieved from "https://kanterella.com/w/index.php?title=ML20043F656&oldid=4535816"