Landfill Gas (LFG) Engines
Our landfill gas (LFG) engine oil analysis program monitors your lubricant condition and extends engine life as they work in the highly corrosive working conditions of a LFG-TE environment.
Landfill gas is produced by the anaerobic decomposition of organic matter, volatilization, and chemical reactions in municipal solid waste (MSW). Each landfill facility’s gas composition will be unique based on factors such as: types and age of the buried waste, quantity and type of organic matter in the waste, compaction, moisture, and temperature. The resulting fuel is highly contaminated and corrosive.
Landfill gas engines are specially designed gas engines that operate on these fuels, which have low to moderate levels of hydrogen sulfide (sour gas) or other corrosive compounds. This unique application requires specially designed oil. Aside from normal lubricant functions, LFG engine lubricants must provide maximum protection from contaminants, the biggest threat to LFG engines. Since landfill gas engines cannot handle high ash oils, an effective LFG engine oil must offer maximized acid neutralizing capabilities (TBN) with low to medium ash levels.
IMPORTANT FLUID QUALITIES
- Detergent/dispersant properties
- Corrosion resistance under significant level of acidic condensate
- Deposit control
- Anti-wear performance
- Anti-scuffing properties
- Minimize oil consumption
- Minimize lacquering
MAJOR SOURCES OF PROBLEMS
The predominant cause of problems for LFG engines is contamination. Landfill gas contaminants beyond acceptable levels can cause a wide range of problems to engines. These problems can also affect emissions, which are to follow stringent government standards.
SULFUR COMPOUNDS, HALIDES, and OTHER ACIDS
During combustion, sulfur compounds (notably hydrogen sulfide H2S) combine with water to form sulfuric acid. Although typically weak, the sulfuric acid can accumulate to severely damage critical engine components, especially any copper-containing components. During combustion, exhaust water vapor combine with halogenated hydrocarbons producing halides, such as hydrochloric (HCI) or hydrofluoric (HF) acids. If not controlled, the acids will damage piston rings, cylinder liners, exhaust valve stems, and other critical wear parts.
Water is a natural by-product of combustion and normally seen in low levels. However, water can combine with organic compounds in landfill gas during the combustion process to form harmful acids. Left unchecked, these acids can attack and damage engine components.
Silicon (Si), also commonly known as dirt, sand, or grit, are hard particles that cause abrasion wear. During combustion, they can collect together and form larger particles that cling to exhaust valve faces and seats. Silicon deposits can undermine LFG engine performance, fuel economy, and emissions by shielding electrodes and increasing the voltage required to fire critical spark plugs.
These compounds are found in household products, such as cleaners, shampoos, deodorants, and beauty products. During combustion, these compounds develop into hard silica and silicate deposits, which can cause excessive wear, valve damage, and guttering.
MONITORING LFG ENGINE OIL
Apex Oil Lab provides accurate testing that meet the stringent cleanliness requirements of your LFG system. We offer programs for all LFG engines, including GE Jenbacher and Caterpillar.
To monitor acid formation in landfill gas, TAN and TBN levels must be carefully monitored. Oxidation, nitration, and viscosity will also indicate oil degradation from acids. Silicon is a crucial element to monitor and is often the leading dictator of oil change intervals in landfill gas engines. Wear metals such as iron, chromium, and copper should be closely monitored for abnormal wear caused by impurities.
Each landfill gas facility will have its own unique gas composition based on factors described above. Combined with the workload, environmental conditions, equipment age, and oil type, the maintenance program should be tailored to the needs of that facility. While OEM standards are an excellent foundation for an effective PM program, limits and maintenance schedules need to be set according to the needs of the equipment on-site.