Numerical simulation of the processes of atomization and combustion of a coal-water slurry in different-scale installations

Numerical simulation of atomization of a coal-water suspension (CWS) by a pneumatic nozzle is carried out, taking into account the processes of secondary breakup of droplets. The characteristic parameters of atomization were obtained (the dispersed jet opening angle, the size and velocity of the droplets). The data obtained were used to simulate atomization and combustion of the CWS on the firing stand. The results obtained are in good agreement with experimental data. The proposed numerical technique allows research on the introduction of advanced technologies and the improvement of existing different-scale installations (from stands to pilot industrial boilers).

Water Suspension and its Effect on Total Light Attenuation in Lake Waters

The paper presents the data obtained by the authors in 2012-2021 during field trips to freshwater reservoirs of Altai Krai. According to hydro-optical measurements, values of light attenuation index in the range of 400-800 nm calculated using the natural logarithm varied greatly within 2.3-19.7 m-1 and 2.9-35.0 m-1 in the surface layer of lakes Lapa and Krasilovskoye during the study period. The relative spectral contribution of water suspension and contributions of yellow matter, chlorophyll, and pure water constituents at wavelengths of 430, 550, and 670 nm were estimated to assess the optical effect of water suspension on the total light attenuation index. The calculation results demonstrated that water suspension had the maximum effect on light attenuation in waters of eutrophic lake Lapa during the autumn-winter period. The maximum effect at all three wavelengths was observed in autumn of 2015, and the contribution of water suspension to light attenuation reached 88.5%, whereas its minimum (1.8-2.4 %) was recorded in 2017. The maximum contribution of water suspension on light attenuation in waters of eutrophic-hypereutrophic lake Krasilovskoye slightly exceeded the value of 70% during the winter of 2014. The next maximums were revealed during the spring of 2014 and had values of 71.3 % at λ =430 nm and 71.1 % at λ =550 nm. Optical microscopy was used to estimate the size and concentration of water suspense particles. The average weighted value of radius for water suspense particles in the surface layer of lakes Lapa and Krasilovskoye was found to be 1.2 and 1.4 microns, respectively. The average particulate count for water suspense during the observation period varied in the range of 0.2·106 cm-3-14.7·106 cm-3 with values of 3.3·106 cm-3 for lake Lapa and 3.0·106 cm-3 for lake Krasilovskoye.

Inactivation of Acanthamoeba Cysts in Suspension and on Contaminated Contact Lenses Using Non-Thermal Plasma

Water suspensions of cysts of a pathogenic clinical isolate of Acanthamoeba sp. were prepared, and the cysts were inactivated either in suspension or placed on the surface of contact lenses by the non-thermal plasma produced by the DC corona transient spark discharge. The efficacy of this treatment was determined by cultivation and the presence of vegetative trophozoites indicating non-inactivated cysts. The negative discharge appeared to be more effective than the positive one. The complete inactivation occurred in water suspension after 40 min and on contaminated lenses after 50 min of plasma exposure. The properties of lenses seem to not be affected by plasma exposure; that is, their optical power, diameter, curvature, water content and infrared and Raman spectra remain unchanged.

Changes in chemical element composition of Betula pendula litter during decomposition in a laboratory experiment simulating leaching and salinization

The aim of the study was to estimate changes in chemical composition of the white birch litter during decomposition in a laboratory experiment simulating leaching and salinization. Location and time of the study. Fresh litter of Betula pendula leaves were collected in the forest-steppe zone of Priobskoe plateau (40 km to the east of Novosibirsk, Russia) in October 2016. The incubation experiment was carried out in the laboratory of Agrochemistry of the Institute of Soil Science and Agrochemistry of the Siberian Branch of the Russian Academy of Sciences (Novosibirsk, Russia) during 105 days (24.05.2017–06.09.2017) at 24˚С). Methodology. Distilled water (50 ml) or the same volume of NaCl, Na2SO4, FeCl3, Fe2(SO4)3 solutions with concentrations of 0.3, 0.5, 0.7 and 1% were added to 2 g of air-dried birch litter (leaves). The litter was placed into 100 ml plastic cups. The salt concentration in solutions was chosen according to the soil salinity gradation, i.e. 0.3% as weak (0.2–0.4%), 0,5% as medium (0.4–0.6%), 0,7% as strong (0.6–0.8%), and 1% as solonchak (Classification…, 1977). After 24 hours surplus water or salt solutions were decanted and filtered, and the birch litter was air-dried. After that 5 ml soil-water suspension (soil:distilled water 1: 2.5 m/v) was added into half of the cups with litter, whereas another half of cups with litter received 5 ml of distilled water. The variant with litter and no water was also included, designated as “dry birch litter”. The cups with litter were closed up and incubated during 105 days in the thermostat (+24 °С) with periodic ventilation. After incubation the litter was air-dried and weighed. The litter mass loss after decomposition was calculated as a difference between a sample mass at the beginning and at the end of the experiment and expressed as percentage. Concentrations of Na, Fe, K, Ca, Mg, Zn, Cu, Ni were determined by atomic-absorption spectrophotometry (AAnalyst 400, Perkin Elmer Inc., USA) in water samples, 0,3–1% salt solutions and birch litter. The total number of cups with litter in the experiment was 150. The term «under leaching» refers to the decrease in chemical element concentration in the litter after incubation with water. The term «under salinization» refers to the increase of Na or Fe concentrations in the litter after incubation with salt solutions. The litter mass loss presented as air-dry mass, concentration of chemical elements in the litter and ash content are expressed on the oven- dry mass basis. Results. Under leaching the concentration of chemical elements was increased in water extracts (especially К, Са, Mg) and decreased in birch litter in the row: Na (3.6 times) –>К (2.4 times) –> Ni (1.9 times) –> Mg (1.4 times) –> Zn and Cu (1.3 times). In comparison with water, the interaction between litter and Na and Fe salt solutions (concentrations 0.3–1%) led to intensive leaching and, correspondingly, to the 1.3 times lower litter К content, as well as 1.2–1.5 times and 1.5-2.2 times lower Са and Mg content, respectively. The highest concentration of Са, Mg, Zn, Cu, Ni was detected in FeCl3 solutions at the start of the experiment. The maximal mass and ash content losses were detected in the dry birch litter. On average, leaching was found to decrease 1.4 times mass loss and ash content in the litter. The minimal mass and ash content losses under salinization were found after litter incubation with FeCl3 (0.3–1%) solutions. The difference in mass loss between variants litter-water and litter-soil water suspension was not detected, although litter ash content after addition of soil water suspension was 1.1–1.3 times higher. Conclusions. The interaction birch litter with water and Na and Fe salt solutions (0,3-1%) led to modification of elemental chemical composition of plant litter as a result of leaching of chemical elements (especially К, Са, Mg) from litter and increased concentrations of Na, Fe and some other elements (depending on the salt used). It led to the decrease in plant litter decomposition rate, which under the natural conditions in the south of West Siberia can take place as a result of temporary overwetting of the forest litter (for instance, in autumn or spring) as well as in areas occupied by saline soils.