SPECIFIC FEATURES OF DETERMINING THE DESIGN OF OXYGEN TUBE TIPS UNDER NON—STATIONARY CONDITIONS OF CONVERTER MELT WITH PRELIMINARY HEATING OF SCRAP

The results of calculating the parameters of the tips of oxygen lances, taking into account the preheating of scrap metal in the converter due to the combustion of solid fuels in the modern raw material conditions of a metallurgical enterprise of Ukraine, are presented. The substantiation of the design of blowing devices is provided. The results of calculating the geometric parameters and the coefficient of off-design for standard and experimental tips of oxygen lances are presented. Using numerical methods, the value of the diameters and length of the supercritical part of the nozzle was obtained. It is shown that with a decrease in the blast flow rate, it is advisable to decrease the length of the supercritical part of the nozzle, which is fully correlated with the literature data. The change in the coefficient of off-design was determined for the studied range of oxygen consumption (600—1100 m3 / min) for standard and experimental handpieces. It is shown that the value of the coefficient of off-design is in the range of 0.52—0.98 and 1.30—2.30, respectively, for 5– and 6–nozzle standard tips. For experimental tips, this figure is 1.00—1.70. Tuyeres with experimental tips, at the pressure available in the shop, reliably operate in the range of oxygen consumption 650—950 m3 / min and allow increasing the oxygen consumption at the beginning of the blowdown to 1000—1100 m3 / min and more, if necessary. The resulting saving effect from the introduction of the modernized tips is: a decrease in the oxidation of the final slag 1.22—1.70 %; reduction in the specific consumption of lime 0.29—1.81 kg / t; reduction of specific consumption of metal charge 0.26—0.38 kg/t.

The Cost-Efficiency Analysis of a System for Improving Fine-Coal Combustion Efficiency of Power Plant Boilers

Hard coal is widely used as a source of energy, and a number of catalysts have been developed to minimize the noxious impact of this fuel on combustion. This paper presents the cost-efficiency analysis of a system for improving the combustion of solid fuels, especially fine coal, in power boilers. The system is provided with a control and supervision device. It has been designed for better accuracy in controlling the boiler operating parameters, with a view to improving combustion efficiency due to the use of catalysts. The tests were carried out for system capacities ranging from 3 to 100 MW. It was found that, depending on the size of the system in the range of 3–100 MW, savings in the fuel consumption ranged from 2% to 8% due to the implementation of novel solutions in the boiler plant operation and from 2 to 6% due to the use of the combustion catalysts. Apart from boosting energy efficiency, the use of catalysts and the efficiency-boosting system resulted in the costs of overhauls being cut by about 20%. The payback time depends on system capacities, and it is between 6.75 and 1.74 years for capacities ranging from 3 to 75 MW and 2.0 years for a 100 MW plant.

Operational tests of an electrostatic precipitator reducing low dust emission from solid fuels combustion

The article presents the continuation of the research aimed at designing, manufacturing and selecting the operating parameters of the electrostatic precipitator for household applications. The tests were carried out in the laboratory and real conditions. The object of the research was a pre-production prototype of the electrostatic precipitator installed in the flue gas duct of a single-family building. The source of exhaust gases was a coal-fired, low-temperature water heating boiler with a nominal power of 21 kW (old generation boiler-year of production: 2007). The obtained results showed that the adopted design of the electrostatic precipitator enables the reduction of dust emissions generated in the combustion of solid fuels in households at relatively low operating costs.

Dependence of the Flue Gas Flow on the Setting of the Separation Baffle in the Flue Gas Tract

With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies.

Study on reaction kinetics of single slime

The study of the combustion characteristics of single slime fuels is the basis for achieving clean combustion of solid fuels. This paper uses a combination of experimental and theoretical analysis, combined with the Coats-Redfen integration method, to study the influence of ash content and heating rate on the kinetic parameters of coal slime, and solve the combustion kinetic parameters. The results show that under the same heating rate, the activation energy gradually increases. As the ash content of coal slime increases, the activity of the coal slime sample decreases, and the reaction activation energy gradually increases.

COMBUSTION SPEED PARAMETERS WHEN SIMULATING BY ANSYS FLUENT PROGRAM OF SOLID FUEL COMBUSTION

The existing difference in the models used to describe the burning rate of solid fuel particles, and, accordingly, the difference in the constants appearing in them, determines the relevance of the formulation of the relation between the constants known from the literature and the parameters that must be set in programs for CFD modeling of heat and power processes. This, in particular, relates to modeling the combustion of solid fuels in the well-known program ANSYS FLUENT. The paper outlines a possible approach to solving this problem. Bibl. 5, Fig. 3.