R. K. Wilk

The thermal decomposition of the liquid phase during the combustion of heavy oil droplets

Abstract Measurements of the temperatures inside droplets of heavy and light fuels were carried out during combustion. The droplet temperature of heavy fuel increased monotonously, and the extent of thermal decomposition in the droplet was estimated. Kinetic equations for the thermal decomposition were solved and used to calculate the quantities of the separate decomposition products. The results obtained were dependent on the initial droplet diameter and the initial droplet temperature.

Method for the determination of the ignition temperature of oil spray

Abstract Special equipment was constructed to investigate the ignition of oil spray. The oil was atomized by compressed air into a rectangular chamber. A screen (0.75 × 0.75 m) was fixed half way along the chamber, perpendicular to the spray. A hole (6 mm diameter) in the screen made it possible to isolate part of the spray. The spray was ignited by a standard gas flame placed behind the screen. The lowest temperature of the oil causing ignition was assumed to be the ignition temperature of the spray. The experimental set-up facilitated the investigation of the influence of the initial temperature of the atomizing air and the ratio of air to oil on the ignition temperature of the spray. It was shown that the ignition temperature of the spray is less than the flash point by 44–50 K. An increase in the initial temperature of the air decreased the ignition temperature of the spray. This dependence was rectilinear. It was found that the ignition temperature of the spray reached its minimum at a ratio of air to oil of ~ 0.8 for all the oils tested.

Determination of overall burning rate coefficient of coal-oil droplet mixtures

Abstract Theoretical considerations of the combustion of coal-oil droplets were studied, and formulae for the total combustion time of the single droplet and for the overall burning rate coefficient were derived. To verify the formulae, experimental investigations were carried out using forced ignition. The theoretical model gave a good approximation to the experimental data only for the boiler coal. The overall burning rate coefficient was about one quarter that of heavy oil, with 50% gram fracture of coal. For lean coal, the overall burning rate coefficient was of the order of the heavy oil burning rate coefficient.

Safe mole fraction of oxygen during quenching of rails in oil

Abstract Experimental investigations of autoignition and forced ignition of hardening oil (No. 70) in nitrogen-oxygen mixtures were carried out. It was ascertained that the mole fraction of oxygen decreased with the decrease in the mixture flow rate. Taking into account the fire hazard, the limiting mole fraction of oxygen was determined to be 4.7%.

Ograniczenie emisji tlenków azotu poprzez zintegrowanie układu: reaktor zgazowania - kocioł węglowy

Nitrogen oxides can be formed in various combustion systems. Strategies for the control of NOx emissions in hard coal boilers include the primary (during the combustion) and secondary measures (after combustion). Reburning is the one of the most attractive techniques for reducing NOx emissions. In the last several years, reburning technology has been widely studied but almost only in power engineering big load boilers. Nevertheless, NOx emission is an issue that needs to be considered for small capacity boilers. Poland is among the largest coal producing country in Europe. Due to this fact, coal fired boilers are very popular in power engineering and also in the municipal sector. Simultaneously, Poland is characterized by the lack of sewage sludge thermal treatment installation. The paper proposes to link those two Polish features so the aim of the work is an experimental investigation on the reburning process of sewage sludge gasification gas in a small capacity domestic coal-fired boiler. The results obtained show how the addition of the reburning fuel influences on NOx reduction efficiency.