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Fuel gas quality is no longer as constant as it once was.
The growing injection of biomethane into the gas grid, the evolution of distribution networks and the natural variability of gas composition can all affect the characteristics of the fuel supplied to a gas engine CHP system. Even relatively small changes in the concentrations of ethane, propane, butane and other heavier hydrocarbons can reduce the Methane Number and increase the risk of engine knocking.
Knocking is an abnormal combustion phenomenon that generates uncontrolled pressure waves inside the cylinder. If it occurs repeatedly, it can increase mechanical stress, reduce engine efficiency and accelerate wear on critical components such as pistons, valves and cylinder heads.
Continuous Methane Number monitoring is therefore becoming increasingly important to ensure the reliability, efficiency and operational continuity of gas engine CHP plants.
For gas engines, the Methane Number is comparable to the octane rating used for petrol engines: it indicates the fuel’s resistance to knock. A high value identifies a more stable gas with a lower tendency to knock, while lower values require closer attention to engine operating conditions.
Real-time knowledge of this parameter makes it possible to:
eKnock is the analyser developed by SMI PREI for continuous monitoring of the Methane Number and the main energy-related parameters of the fuel supplied to gas engine CHP systems.
Unlike solutions based on gas chromatography, eKnock uses an innovative measurement technology combining MEMS sensors for gas viscosity, thermal conductivity detectors (TCD), infrared CO₂ measurement and proprietary mathematical algorithms. This architecture eliminates the need for carrier gas, chromatographic columns and complex switching systems, significantly reducing maintenance requirements and operating costs.
In addition to the Methane Number, eKnock calculates several parameters that support effective fuel and engine management, including:
eKnock is not intended to replace a gas chromatograph when a complete compositional analysis is required. Its purpose is to provide the information that is most relevant to engine control, continuously and through a simpler, more reliable and more cost-effective solution.
The main benefits include:
The evolution of gas networks and the growing use of biomethane make it increasingly important to know the quality of the fuel supplied to the engine. Monitoring the Methane Number makes it possible to respond before changes in gas composition lead to reduced efficiency, alarms or mechanical damage.
With eKnock, the Methane Number becomes a continuously available real-time parameter that can be integrated into supervisory systems and used to support plant control and protection strategies.
