No abstract

No abstract

No abstract

This paper presents the results of an experimental study on the combustion process of methane mixed with ammonia (NH3) in flameless mode. At a time of striving for CO2-free power, ammonia became a potential energy storage carrier fuel from renewable sources. Flameless combustion features low emissions and is a very efficient technology used in the power sector, as well as steel production, ceramics, etc. Industrial furnaces were tested in the context of pure methane combustion with an addition of ammonia, up to 5%. Flameless combustion conditions were achieved with a regenerative gas burner system (High Regenerative System- HRS). The burner consists of four ceramic regenerators allowing for continuous preheating of air, even up to 50K lower than the temperature of the combustion chamber wall. Constant power of the introduced fuel was kept at 150kW and the fuel-air equivalence ratio ranged from 0.75 to 0.95. The results have shown a growth of molar fraction of nitric oxides in flue gases when ammonia content in the fuel rose. The increase is more significant for the tests with a higher amount of oxygen in the combustion chamber (a lower fuel-air equivalence ratio). An addition of 5% of NH3 into the fuel caused an emission of nitric oxide at the levels of 113 ppmv and 462 ppmv (calculated to O2 = 0%), respectively for low and high fuel-air equivalence ratios. The calculated conversion factor (CF) of NH3 to fuel nitric oxide has shown extremely low values, equal to 2% (? = 0.95) and 8.4% (? = 0.75), which indeed confirmed that ammonia can be burned with low emissions in flameless combustion technology.

No abstract

The article presents the results of experimental and numerical investigation of turbulent premixed methane flames diluted by carbon dioxide (up to 30%) at atmospheric and elevated pressures (up to 0.5 MPa). The study included the influence of fuel properties and operation parameters on the emission of NOx and CO as well as flame properties. The investigation has been prepared for two combustion system configurations (axisymmetric flames and flames supported by a pilot flame) in a wide range of air/fuel equivalence ratios (ϕ = 0.42 ÷ 0.85). It has been reported that reduction of NOx emission by CO2 fuel dilution reached a level of up to 45% in atmospheric conditions and 30% at elevated pressure, decreasing with a drop in the equivalence ratio. The results have shown influence of pressure on NOx composition, where for pressurized tests, NO2 was doubled compared to atmospheric tests. Carbon monoxide emission rises with CO2 content in the fuel as a result of thermal dissociation, but this phenomenon is mitigated by a pressure increase. Planar laser induced fluorescence (PLIF) study has shown that flame length decreases with an increase in pressure and CO2 content in the fuel. Fuel staging increased NOx emission, especially for richer flames (ϕ > 0.6) at low pressure, while CO increased in the whole range of equivalence ratios.

Application of a pre-combustion chamber (PCC) ignition system is one of the methods to improve combustion stability and reduce toxic compounds emission, especially NO x . Using PCC allows the operation of the engine at lean combustion conditions or the utilization of low calorific gaseous fuels such as syngas or biogas. The paper presents the results of an experimental study of the combustion process in two stroke, large bore, stationary gas engine GMVH 12 equipped with two spark plugs (2-SP) and a PCC ignition system. The experimental research has been performed during the normal operation of the engine in an industrial compression station. It was observed that application of PCC provides less cycle-to-cycle combustion variation (more than 10%) and nitric oxide and carbon monoxide emissions decreased to 60% and 26% respectively. The total hydrocarbon (THC) emission rate is 25% higher for the engine equipped with PCC, which results in roughly two percent engine efficiency decrease. Another important criterion of engine retrofitting was the PCC location in the engine head. The experimental results show that improvement of engine operating parameters was recorded only for a configuration with one port offset by 45 • from the axis of the main chamber. The study of the ignition delay angle and equivalence ratio in PCC did not demonstrate explicit influence on engine performance.

There has been a gradual increase in the field of parts recovery from cars that are withdrawn from use. However, the disposal of automotive shredder residue (ASR) still remains a significant problem. ASR is refuse derived fuel (RDF), which contains mainly plastics, fiber sponges, and rubbers in different proportions, and therefore a thermal treatment of selected waste samples is applied. The presented research includes thermogravimetry (TG) analysis and differential thermogravimetric (DTG) analysis, as well as a proximate and an ultimate analysis of the ASR samples. The obtained results were processed and used as an input for modelling. The numerical calculations focused on the identification of the ASR’s average composition, the raw pyrolysis process product, its dry pyrolytic gas composition, and the combustible properties of the pyrolytic gases. The TGA analysis with three heating rate levels covered the temperature range from ambient to 800 °C. The thermal decomposition of the studied samples was in three stages confirmed with three peaks observed at the temperatures 280, 470, and 670 °C. The amount of solid residue grew with the heating rates and was in the range of 27–32 wt%. The numerical calculation of the pyrolysis process showed that only 0.46 kg of dry gas were formed from 1 kg of ASR. The gas yield increased with the rising temperature, and, at the same time, its calorific value decreased from 19.22 down to 14.16 MJ/m3. This is due to the decomposition of C6+ hydrocarbons and the promotion of CO formation. The thermodynamic parameters of the combustion process for a pyrolytic gas air mixture, such as the adiabatic flame temperature and laminar flame speed, were higher than for methane and were, respectively, 2073 °C and 1.02 m/s.