Comparative Analysis of Models of the Combustion Process of Coal Dust in a Turbulent Flow of a Torch of a Charcoal Boiler

This article provides an overview of existing turbulence models. The scheme of combustion of pulverized coal fuel, the construction of a pulverized coal boiler unit and the process of burning coal in the furnace of a boiler unit BKZ-420-140 are considered. We analyzed the existing turbulence models and selected the most optimal mathematical model to study the combustion process of pulverized coal fuel in order to increase the efficiency of the CHPP.

Corporate Social Responsibility and Environmental Protection in the Nigerian Energy Sector: Reflection on Issues and Legal Reform

The abatement of environmental degradation has been an issue which has received growing attention in recent times. Despite the increased attention however, environment pollution has remained unabated in Nigeria with its adverse impacts on the citizens. The question then is, do businesses owe society any social responsibility as it relates to the protection of environment? The Energy sector in Nigeria plays a very crucial role in Nigeria’s development, as the industrial development and innovation necessary for the economic development of any country is directly linked to the management of energy resources. Nigeria is endowed with abundant (fossil fuel) energy resources, such as oil, gas, coal, fuel wood, etc., which are dominantly the fuel sources for electrical energy production, yet, Nigeria is faced with environmental challenges capable of limiting and destroying access to these energy resources without taking cognizance of their environmental control. Therefore, this article attempts at navigating the imperative of Corporate Social Responsibility. Furthermore, the use of Corporate Social Responsibility as a tool for abatement and prevention of environmental damage to the energy sector is considered. Finally, possible recommendations were made as control measure through CSR in Nigeria in order to protect the energy resources and ensure a clean and healthy environment.

MODELING AND MEASUREMENT OF PARTICULATE MATTER (PM) COLLECTION FROM BOILER EXHAUST GAS IN ELECTROSTATIC WATER SPRAYING SCRUBBER

Boiler exhaust gas consists of many components that cause air pollution, such as: particulate matter (PM), SOx, NOx, COx, etc. These pollutants normally are mixed. To eliminate them, an electrostatic water spraying scrubber is used, depending on a coal fuel used for combustion source in the furnace. For PM, new guidelines will be changed from the existing 10 to 2.5 microns within the next few years. The scrubber is widely used for the collection of PM from industrial exhausts because of its low equipment and maintenance costs combined with operational safety and high collection efficiency. This study presents computed and experimented results of PM collection efficiency in an electrostatic water spraying scrubber. In this scrubber electric attraction between charged PM and charged water droplet improves PM collection considerably over conventional scrubber. Computed model takes into account initial liquid momentum, hydrodynamic and electric forces. The effects of operating parameters, such as gas velocity, applied voltage, charge to-mass ratio on PM collection efficiency within the scrubber, were also investigated. Computed results are in good agreement with the experimental data obtained in the laboratory. Compared to inertial scrubbers, the electrostatic water spraying scrubbers can operate at lower flow rate, but total collection efficiency is over 98% of all PM sizes.

Experimental studies of in-line gasification of mechanically activated coal fuel

The 1 MW experimental stand was modernized with a scroll swirler and a crushed fuel supply system. Comparative data on combustion and gasification of coal fuel crushed in high-stress mills - disintegrator, vibrocentrifugal and hammer mill - at a stand with a thermal power of 1 MW were obtained. The experiments used coal of the Kuznetsk Basin, grade D, with technical characteristics: Wr, % = 5.4; Ar, %=22.3; Vr, % = 32.3; Qsr, MJ/kg = 20.0. Elemental analysis showed that: Cr, %=54.6; Hr, % = 4.1; Nr, % = 1.3; Sr, % = 0.5; Or = 11.8. In experiments with grinding coal on a disintegrator mill, the value of H2 = 4.5 vol.% and CO = 9.4 vol.%, when grinding in a vibro-centrifugal mill, the values of H2 = 0.6 vol.% and CO = 5.8 vol.%, when grinding in a hammer mill, the values of H2 = 0.3 vol.% and CO = 2.8 vol.%. When studying the combustion of mechanochemically treated coal samples, it was found that, all other things being equal, the gasification parameters, namely, the gas concentration and the distribution of temperature zones, depend strongly on the type of equipment used for processing. In particular, processing to approximately the same degree of fineness in mechanical mills-activators with constrained impact and in free impact mills (disintegrators) resulted in different flame parameters.

3D-LDA diagnostics of a swirled flow in the model of an improved four-vortex furnace

The three-component Laser Doppler Anemometry method (3D-LDA) was used to study the internal aerodynamics of an experimental model of a promising furnace with a four-vortex scheme for burning coal fuel. Distributions of the averaged velocity and velocity fluctuations are obtained. There are no the pronounced peaks in the spectrum of velocity fluctuations, so we can speak about the stability of the investigated flow. The studied model is characterized by a high level of velocity fluctuations, provided for effective mixing of the pulverized coal mixture in the combustion chamber of the furnace.

CO2 Recycling in the Iron and Steel Industry via Power-to-Gas and Oxy-Fuel Combustion

The iron and steel industry is the largest energy-consuming sector in the world. It is responsible for emitting 4–5% of the total anthropogenic CO2. As an energy-intensive industry, it is essential that the iron and steel sector accomplishes important carbon emission reduction. Carbon capture is one of the most promising alternatives to achieve this aim. Moreover, if carbon utilization via power-to-gas is integrated with carbon capture, there could be a significant increase in the interest of this alternative in the iron and steel sector. This paper presents several simulations to integrate oxy-fuel processes and power-to-gas in a steel plant, and compares gas productions (coke oven gas, blast furnace gas, and blast oxygen furnace gas), energy requirements, and carbon reduction with a base case in order to obtain the technical feasibility of the proposals. Two different power-to-gas technology implementations were selected, together with the oxy blast furnace and the top gas recycling technologies. These integrations are based on three strategies: (i) converting the blast furnace (BF) process into an oxy-fuel process, (ii) recirculating blast furnace gas (BFG) back to the BF itself, and (iii) using a methanation process to generate CH4 and also introduce it to the BF. Applying these improvements to the steel industry, we achieved reductions in CO2 emissions of up to 8%, and reductions in coal fuel consumption of 12.8%. On the basis of the results, we are able to conclude that the energy required to achieve the above emission savings could be as low as 4.9 MJ/kg CO2 for the second implementation. These values highlight the importance of carrying out future research in the implementation of carbon capture and power-to-gas in the industrial sector.

Source Apportionment of PM2.5, PAH and Arsenic Air Pollution in Central Bohemia

The results of air quality monitoring show significantly increased concentrations of polycyclic aromatic hydrocarbons (PAH) and arsenic in the area located near the town of Kladno in Central Bohemia, Czech Republic. The region of interest is historically associated with coal mines and steelworks. Source apportionment using the method of Positive Matrix Factorization (PMF) at three sites has been used to try to explain the reasons of the increased PM2.5, benzo[a]pyrene, and arsenic concentrations in the ambient air. Based on the PMF analysis, nine factors explaining the atmospheric aerosol mass have been identified. The PMF results showed that most of the aerosol mass originated from residential heating (about one third of PM2.5), both primary particles and secondary organic aerosols induced by road traffic (up to approximately 25%), soil and other mineral dust (about 15%), secondary inorganic aerosol ammonium sulfate (up to 16%), ammonium nitrate (up to 14%) and other sulfates (up to 9%). The main source of arsenic and benzo[a]pyrene was residential heating, which accounted for two-thirds and 80% of their total mass, respectively. The results have pointed to the most important measures for effective air quality protection in the area of interest: replacing coal fuel and old boilers used for residential heating in order to reduce arsenic and PAH emissions and mitigate sources of secondary particles precursors to decrease PM concentrations.

Comparative analysis of renewable energy development in the Republic of Buryatia (Russia) and Mongolia

The constantly growing demand for electricity and relatively small energy capacities are forcing the Republic of Buryatia (to a greater extent) and Mongolia, which are limited in some types of economic activity, to look for new sources of energy. One of these restrictions is the ban on the construction of hydroelectric power plants on rivers of the Lake Baikal basin. Therefore, Buryatia and Mongolia have taken the path of building environmentally friendly power plants and have succeeded in many ways. Despite the high costs of setting up clean power plants, infrastructure investments in alternative energy are long-term and expected to be profitable. Investors (including foreign ones) placing their money in a seemingly low-profit project, having long-term expectations. Competent investors do not run after “quick money”, realising that the return period of the constructed power plants will be long, as at the moment of development they have a relatively low efficiency. Despite the criticism of some researchers [1], they invest in green energy, modern infrastructure and a future without emissions (CO2, NO2, SO2 and other gases) from burning coal, fuel oil and firewood. Other experts see in the development of alternative energy a great potential [2-5], refuting arguments of critics about high cost of electricity [6].

INFLUENCE OF BLOWING PARAMETERS AND SLAG REGIME ON SILICON AND SULFUR CONTENT IN BLAST-FURNACE CAST IRON

At two blast furnaces (BF) with a volume of 1386 and 1500 m³, the influence of the parameters of blast and slag modes on the content of silicon and sulfur in cast iron was investigated. The blast mode was evaluated by the consumption of pulverized coal fuel (PCF) and oxygen, the slag mode was evaluated by its basicity CaO / SiO₂. It was found that the injection of pulverized coal into the hearth of 1500 m³ BF in the range of flow rates from 108 to 120 g/m³·s, and in the hearth of 1386 m³ BF in the range from 90 to 110 g/m³·s was accompanied by a decrease in the silicon content in cast iron. The deterioration of the transition of silicon into cast iron with an increase in the consumption of pulverized coal is explained by the complex effect of factors that retard the reduction of its oxides. Extreme relationships were also established between the intensity of melting in terms of oxygen consumption and the silicon content in the cast iron of the furnaces under study. The extreme dependences of the studied variables are due to the dual effect of the melting intensity on the reduction of silicon oxides: a reduction in the time of contact of the metal with furnace gases reduces the possibility of transition of silicon into metal, and an increase in the volume of the silicon reduction zone improves these possibilities. When operating a 1386 m³ furnace on calcium slag in the range of CaO / SiO₂ basicity change from 0.9 to 1.3 without removing the blast furnace operation periods associated with a change in operating conditions, the absence of dependence of the silicon content in cast iron on the CaO/SiO₂ modulus was found/ In its turn this indicated the complexity of factors influencing the reduction of silicon oxides. In the same range of changes in basicity and different operating modes of the furnace, a noticeable effect of basicity on the sulfur content in cast iron was observed, which indicates the decisive role of basicity in the process of blast-furnace desulfurization.