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Application & Installation Guide Crankcase Ventilation Systems

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Application & Installation Guide Crankcase Ventilation Systems Application & Installation Guide Crankcase Ventilation Systems LEBW4958-04 Contents Crankcase Ventilation Systems ...................................................... 1 Crankcase Emissions ................................................................... 2 Blow-by .................................................................................... 2 Crankcase Ventilation .................................................................. 3 Ingestive ................................................................................... 3 Low Pressure Ingestive System ........................................ 3 High Pressure Ingestive System ........................................ 4 Introducing Fresh Air into Crankcase ................................ 5 Water in Engine Oil ............................................................. 5 Crankcase Pressure ............................................................ 5 Non-Ingestive ........................................................................... 6 Diluting Crankcase Emissions ................................................... 11 Reference Material ..................................................................... 12 Foreword This section of the Application and Installation Guide generally describes wide-ranging requirements and options for the Crankcase Ventilation System on Cat® engines listed on the front of this section. Additional engine systems, components and dynamics are addressed in other sections of this Application and Installation Guide. Engine-specific information and data are available from a variety of sources. Refer to the Introduction section of this guide for additional references. Systems and components described in this guide may not be available or applicable for every engine. Below is a listing of crankcase ventilation systems for various Cat engines. Refer to the Parts List for specific options and compatibility. Crankcase Ventilation Systems Application and Installation Guide Crankcase Ventilation Systems Crankcase ventilation systems are designed to control the balance of air pressure between the engine crankcase and atmospheric pressure while processing the accompanying fumes. Crankcase air pressures that are excessively above or below atmospheric pressure can have negative affects on component life, the lubricating oil system and overall engine emissions. Ventilating the engine crankcase is not a difficult process in itself. Controlling emissions and preventing contamination, however, add some complexity to this system. SECTION CONTENTS Crankcase Emissions .............. 2 Measuring Blow-by ............... 11 • Sources • Step-by-step instructions • Harmful Effects • Composition Crankcase Ventilation ............. 3 • Ingestive • Non-Ingestive © 2015 Caterpillar All rights reserved. Page 1 Application and Installation Guide Crankcase Ventilation Systems Crankcase Emissions vapor and traces of sulfates and Blow-by aldehydes. Crankcase emissions result from combustion byproducts and/or Crankcase hydrocarbon emissions exhaust fumes escaping around the are normally 3% of the total exhaust piston rings and into the crankcase. emissions tested at the mid-life of These escaping fumes are the engines. However, due to commonly called blow-by. If not piston ring tolerances, crankcase controlled, hydrocarbon emissions can the blow-by can contaminate the increase to 20% of the total lubricating oil and pressurize the hydrocarbon emissions. crankcase, possibly leading to an The amount of NOX present in the oil leak. blow-by decreases depending on The overall volume of blow-by the air/fuel ratio of the engine. As varies due to cylinder pressure, the air/fuel mixture becomes leaner, piston ring pressure and component less NOX should be present. wear. The sulfates and aldehydes will Venting the emissions to the change depending on the fuel. An atmosphere is a simple solution to engine running on diesel fuel, release the pressure and trapped landfill gas or digester gas will have fumes. Managing the emissions, more sulfides present in the blow- however, adds complexity to by than an engine running on crankcase ventilation systems. natural gas. Elements found in blow-by can As emission laws become more include wear particles, oil, fuel, gas stringent, it is inevitable that and air. The specific composition of crankcase emissions will be the elements varies due to fuel type, included in total system emission engine type, engine speed, load and values. Certain parts of Europe and maintenance history. Typically, California are already counting blow-by is made up of blow-by in the emission numbers. hydrocarbons (HC), carbon In the future, ventilating crankcase monoxide (CO), carbon dioxide emissions to the atmosphere will be discouraged or prohibited. (CO2), nitrogen oxides (NOX), water © 2015 Caterpillar Page 2 All rights reserved. Crankcase Ventilation Systems Application and Installation Guide Crankcase Ventilation Crankcase ventilation systems can be classified as either ingestive or non-ingestive. An ingestive system vents the blow-by into the engine where it returns to the combustion process. A non-ingestive system vents blow-by to the atmosphere. Except for some marine pleasure craft applications, Caterpillar does not offer ingestive crankcase ventilation systems on diesel engines. Figure 1 Ingestive The ingestive crankcase As shown in Figure 1, the blow-by ventilation system routes any flows from the crankcase through crankcase emissions into the intake vent tubes, through an oil air stream, where it is re-burned in condensing device (or blow-by the combustion process. filter) and is drawn through the air cleaner by the turbocharger. This system is known as Positive There are a number of threats that Crankcase Ventilation (PCV) in can occur when using an ingestive the automobile industry. PCV system on a turbocharged engine. is economical and efficient in These threats include: automobiles because most are naturally aspirated and do not • Reduced spark plug life in gas have sophisticated air handling engines components found on industrial • Fouled or damaged engines. Turbocharging and other turbocharger or aftercooler intake air handling components can be negatively affected by blow-by • Reduced detonation margin, fumes. This creates additional engine detonation, damaged challenges when using a PCV-type pistons in gas engines system on an industrial engine. • Reduced load capability and There are two ways of re- operation introducing blow-by fumes back • Reduced efficiency into the combustion process on a turbocharged engine. The blow-by • Reduced component life can be put in the system at low In addition, most tests have pressure (before the turbocharger) shown that no matter how effective or at high pressure (after the the blow-by filter, over time, turbocharger). enough Low Pressure Ingestive System oil will be adsorbed to coat the aftercooler. This oil will act as an A low pressure, ingestive system insulator, reducing the cooling involves piping the crankcase capabilities of the aftercooler. emissions into the low pressure side of the turbocharger. © 2015 Caterpillar All rights reserved. Page 3 Application and Installation Guide Crankcase Ventilation Systems Despite these drawbacks, measurements to account for demand for these systems has lead normal engine wear. Caterpillar to offer an optional low • A minimum oil removal rate pressure, ingestive, PCV system on of 99.97% is required. Oil the G3520C engine (Natural GAS removal rate can be engine only). When using calculated as follows: this system, it is recommended that all operation and maintenance Blow-by Concentration (before PCV) – (after PCV) % Removal = procedures are strictly followed. Blow-by Concentration Higher maintenance cost should before PCV also be expected (this system is not for use in landfill applications or applications with corrosive fuels). • Caterpillar recommends that the oil should NOT be If a system not supplied by returned to the crankcase for Caterpillar is used, extreme care a non-approved system. If oil should be observed to make sure is planned to be returned to the system design complies with the crankcase, trend S•O•SSM the following list of samples of recovered oil recommendations for designing a every 100 hours of engine low pressure, ingestive system. operation up to 800 hours to • A cleanable aftercooler certify that the recovered oil should be used and it should does not reach condemning be cleaned regularly. limits. If oil exceeds condemning limits, DO NOT • The blow-by must be sent return oil to the crankcase. through a filtering system prior to entering the • The system must have a turbocharger. bypass to eliminate the possibility of crankcase over • The system must be pressurization if the filter protected from freezing in element clogs. Alarms for low ambient temperature pressure differential are not conditions. supplied by Caterpillar. • The system must ensure the High Pressure Ingestive System draw on the crankcase does A high pressure ingestive not exceed acceptable levels. crankcase ventilation system This may be accomplished involves removing the blow-by by installing a pressure from the crankcase and pumping relief valve between the it directly into the intake plenum as turbocharger and the shown in Figure 2. filtering system. • Blow-by filters should be replaced or cleaned at every oil change. • The system must be designed to handle two times the engine blow-by © 2015 Caterpillar Page 4 All rights reserved. Crankcase Ventilation Systems Application
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