Ignition of the drops of coal–water fuel in a flow of air

Ignition of coal‐water fuel droplets with addition of isopropyl alcohol

“…Even such large (1.5‐3.5 mm) CWF droplets are stably ignited under conditions corresponding to the conditions of boiler combustion chambers. The ignition delay times for droplets of less than 1 mm in size will be significantly less than those obtained for droplets of 1.5 mm in size, as follows from the general theory of ignition of coal‐water fuel droplets 63 …”

“…The ignition delay times for droplets of less than 1 mm in size will be significantly less than those F I G U R E 1 0 Dependences of ignition delay times of CWF droplets (solid lines) and ACWF: A, D ≈ 1.5 mm; B, D ≈ 2.5 mm; C, D ≈ 3.5 mm [Colour figure can be viewed at wileyonlinelibrary.com] obtained for droplets of 1.5 mm in size, as follows from the general theory of ignition of coal-water fuel droplets. 63 Comparing the results of experimental studies of the ignition delay times of single droplets of coal-water suspensions with addition of isopropyl alcohol with a similar characteristic for three-component CWF [64][65][66] with addition of waste oils, we can conclude about the advantages of ACWF according to energy and economic criteria. Table 4 shows the values of the main ignition characteristic for several types of coal-water fuels prepared using coal processing waste, spent petroleum products, and metal powder 66 as the third component (at T = 873 K, D = 1.5 mm).…”

Choice of the Kinetic Scheme of Oxidation Reactions of the Gaseous Products of Coal Pyrolysis during Induction Period at Ignition of the Water–Coal Fuel Particles

“…Figure 2 shows the experiment (according to ref 49) and the results of numerical simulation values of the ignition delay time Experiments 49,50 were carried out on an installation that provides a low level of error in determining the main characteristics of the ignition process (ignition delay time t ign , ambient temperatureT g , and flow rate of the hightemperature oxidizer to the fuel particleV g ). The experimental stand 49 reproduces the conditions that most closely correspond to the in-furnace space of the typical modern boiler units. 85 The studies were carried out according to the following scheme: a drop of water−coal fuel was formed using an electronic metering device and mounted on a ceramic needle holder.…”

“…The latter was also recorded in the experiments. 48,49 Most likely, this is due to the fact that the ignition of volatiles occurs in the pores of the near-surface layer of the fuel particle. In order to compare the results of mathematical modeling and the experiments, 48,49 Figures 4 and 5 show the frame of the videogram of the moment of ignition.…”

“…Physical Formulation of the Problem. The mathematical model used in the numerical simulation has been based on the experimentally established 48,49 laws of the physical processes occurring during the high-temperature heating of the WCF particles.…”