DRIVE GP-ACCESSORY 2622762 - Caterpillar

Landfill Gas
The decomposition of organic material produces landfill gas. The composition of landfill gas depends on the materials that are in the landfill. The gas is collected through a grid of pipes that are laid out within the landfill.Landfill gas may contain contaminants that can cause harmful effects on engines:
Chlorine
Fluorine
Siloxanes
Sulfur
Water vaporFuel analysis is required in order to provide guidelines for treatment of the fuel.The sulfur compounds in landfill gas cause the same engine problems as sulfur in sour gas. When landfill gas is used, follow the precautions that are recommended for sour gas.Landfills can also contain chlorine and fluorine compounds in the form of volatile organic compounds and chlorofluorocarbons. When these substances are burned in engines, corrosive hydrochloric acid and hydrofluoric acid can be produced.Landfill gas can corrode both the equipment that handles the gas and the engine. Vapor is produced by combustion. If that vapor condenses in the crankcase, a solution that is potentially corrosive to the engine can form.Landfill gas and digester gas can contain siloxanes. Siloxanes are formed when silica ions attach to the methane hydrocarbon chain. These gaseous compounds enter the combustion chamber with the fuel. This creates deposits in the cylinders.In addition, calcium from engine oils contributes to deposits. Hence, deposits in the combustion chamber are generally a combination of these materials: silicon, calcium and some traces of other elements.Siloxane particles can be abrasive to exhaust valve faces and to valve seats. This causes the valves to become pitted and indented. The particles can also build up on the valve seat. The buildup can cause guttering of the valves.Deposits also form on the pistons and on the bottom deck of the cylinder heads. These deposits can increase the compression ratio, which can lead to detonation and/or preignition. Detonation and/or preignition can loosen the deposits. The deposits that are loosened can be trapped between the valve and the valve seat. The valve will be held open. Guttering of the valve will result.The formation of deposits depends on the following factors:
Composition of the fuel
Operating conditions
Type of lubrication oilMost landfill applications will generate some deposits in the combustion chamber and in the turbocharger. Siloxanes are a major contributor to these deposits. The fuel requires treatment in order to remove the siloxanes. For information on equipment for processing landfill gas, refer to the most current revision level of Special Publication, LEBW4977, "Gaseous Fuels - Application and Installation Guide".Note: The amount of silicon in the fuel can be measured with a test that was developed by Caterpillar and by Bio-Engineering Services. The test kit enables a sample of the fuel to be analyzed. The fuel can also be analyzed for other harmful contaminants such as chlorines, fluorines, sulfur, and halides. The Portable Silicon Evaluation Unit (#SI 110V) is used to process fuel samples on site, and the Silicon Sample Sets (#SI 20) are the fluid sets that are processed by the Portable Silicon Evaluation Unit. The processed fluid sets are then sent to the laboratory for analysis. Details