Considering the global climate, the market has always been highly concerned about the carbon emissions of various equipment and facilities, and governments have issued strict emission regulations. All this urges the engine industry to study how to make the emission performance of equipment better through technology, one of which is thin combustion technology. Thin combustion engines for power generation can be seen as a timely solution to tougher environmental regulations in the new era, while reducing gas-fired energy consumption and reducing carbon dioxide and nitrogen oxide emissions.

In fact, thin combustion technology is not a new concept, and it is mainly hoped that it can help everyone understand some of the work done by power equipment to save energy and reduce emissions from the principle. Over the years, the application of lean combustion gas engines has been well demonstrated to meet the increasingly stringent standards of reciprocating engines used in power generation, such as gas efficiency, emission performance, atmospheric regulations, reliability, durability and power density.

Comparison of combustion methods: thin combustion and oxygen-rich combustion

Oxygen-enriched combustion engines are characterized by more fuel in the combustion chamber during combustion (oxygen in exhaust is usually in the range of 0.5%-0.6%), while thin combustion engines are characterized by more air in the combustion chamber (oxygen in exhaust is usually > 6%). Thin combustion gas engines can operate at larger loads, providing lower emissions, cleaner, more stable power, higher electrical efficiency, and higher overall efficiency than oxygen-enriched combustion engines that operate in balanced chemical equivalent ratios (in air-fuel ratios or Lambda).

Characteristics of thin combustion and oxygen-enriched combustion

Thin burn

Lower exhaust temperatures, lower NOx and CO2 emissions, higher power density, better gas efficiency,

Oxygen-rich combustion

Higher exhaust temperatures, higher NOx emissions (due to higher exhaust temperatures), higher fuel consumption, lower power density

Thin combustion engines use less fuel in a certain amount of air — typically requiring twice as much air as full fuel combustion — which makes them more cost-effective in terms of gas consumption and the release of fewer greenhouse gases. More air effectively dilutes and reduces peak combustion temperatures in the cylinder, reduces NOx generation and engine emissions, and eliminates the need for posttreatment systems in many applications. This thin combustion process has the advantage of reducing the probability of knocking, allowing for higher average braking effective pressure (BMEP) levels (load) and optimized combustion. This results in higher power density and generally better gas efficiency.

In addition to advanced engine technology, the use of an efficient air-gas management system helps thin gas engines meet government-imposed emissions regulations. This air-gas management system not only helps control emission levels, but also helps control the expensive aftertreatment configurations and costs required for a typical oxygen-enriched combustion system that uses a ternary oxidation catalyst to reduce NOx due to higher cylinder temperatures and can meet sustained, economical and reliable power demands.

Controlling the engine using modern microprocessor-based technologies, such as the Electronic Control Module (ECM) that manages microprocessor-based throttle and air-fuel ratio control, directs premixed air and gas into the engine cylinders and ignites, and provides continuous feedback to the ECM through NOx, temperature and pressure sensors, making the thin combustion engine gas management system more reliable than ever. With the air-gas mixer system, lean combustion engines based on standby and rapid response applications can be loaded at 100% while meeting NFPA requirements.

Regional programmes and sustainability

Strict emissions regulations and rising utility costs have led to a steady increase in demand for gas-fired engine power generation (taking into account the impact of gas price factors in different regions). Hurricane-prone areas, water and wastewater treatment applications, and the risk of diesel contamination from shoreline projects make gas engine/generator set applications more important than ever and ideal for some users, contractors, and engineers.