mtu Onsite Energy sets new standards with Series 400 gas engines

• Series 400 gas engines for use in generator sets and CHP modules
• Output raised to 420 kWel without increasing engine capacity
• Efficiency rating up to 40%
• Optimized combustion and engine management improve efficiency even with gases with low calorific value

Augsburg/Hanover, 6 November 2009. Energy plant specialist MTU Onsite Energy GmbH Gas Power Systems will be premiering the higher-output version of its Series 400 gas engine for electricity generator sets (gensets) and CHP (combined heat and power) modules at the Agritechnica 2009 agricultural machinery exhibition in Hanover, Germany. With outputs of 120 to 420 kWel and an electrical efficiency up to 40%, the engines set new standards in their power class. They are designed to run on natural gas or biogas.

Higher specific output and improved efficiency

Those advances are due to a whole series of innovations. Higher compression and improved turbocharging produce higher performance from the same engine capacity. The new, cylinder-specific knock detection and ignition timing adjustment allow the economical use of even low-calorific gases. Thus reliable operation of the natural gas engines at rated power is possible even with a methane number of 70 (typical for North Sea natural gas). Biogas-fueled gensets and CHP modules also benefit from the new technology. Due to the optimized engine management, they utilize the gas fuel even more efficiently and in a way that is much easier on the engine. The test results obtained in house are currently being externally verified and the trials phase should be completed by the middle of 2010 for all machine types.

Extended sparkplug and oil change intervals

In addition to the specific power output, the developers at mtu Onsite Energy have also been able to increase reliability. The improved ignition system, for instance, ensures problem-free engine use for extended periods so that one set of plugs can last the length of a service interval or even beyond. The present management system indicates sparkplug condition so that the system operator can maximize plug life.

Formaldehyde limit compliance

Systems based on the new engines also offer convincing environmental credentials. They produce relatively low untreated formaldehyde emissions. Therefore low residual emission levels can be achieved with appropriately developed catalytic converters. That is a significant consideration in view of the higher electricity premium available under Germany’s renewable energy legislation (EEG) and granted to operators of certain biogas plants that are below the formaldehyde limit of 40 mg/m³ i.N. Catalytic converters adapted to the engines are currently undergoing field trials and will soon be available for the new systems. The use of such oxidation catalytic converters demands quasi zero-sulfur biogas. The gas purification thus required can easily be achieved using activated charcoal filters. And they also offer other advantages. Based on practical experience to date, desulphurization also extends the life of the engine oil and sparkplugs. mtu Onsite Energy will shortly be adding optimized gas purification systems to its product range. As a result, customers will be able to purchase a fully integrated and compatible system from fuel purification to exhaust treatment that ensures compliance with the emission limits.

Extensive preassembly and system testing at the factory

Design modifications mean that the installation of gensets or energy modules based on the Series 400 gas engine is now even easier. For example, the gas train is preassembled, wired up and tested together with the unit on the test bench at the Augsburg factory. In addition, shifting the engine sensor systems to the mtu Interface Panel (MIP), has enabled integration of the generator power circuitry (contactor/switch combination) in the mtu MMC engine management system control cabinet. Therefore, the generator can be fully wired and tested at the factory – which saves time during installation and commissioning on site. A space-saving feature is that the power circuitry of the auxiliary drive systems is now integrated in the MMC, which normally eliminates the need for a separate auxiliary drive system control cabinet.

Optimum adaptation to the overall system

For the new generation of gas engine systems an optimized modular system component set has also been assembled. The power circuitry incorporated in the MMC is matched to those components. For biogas machines, the optional system components available include gas compressor kit, emergency cooler (water/coolant mixture), lubrication system, room ventilation, gas warning system, exhaust silencer and sound insulation cover.