Search

Publisher Summary This chapter attempts to provide sufficient knowledge to specify burners, critically assess a burner design and optimize furnace performance and heat transfer. The performance of the burners has a huge effect on furnace operation and efficiency, yet it is relatively rarely that burner design is fully integrated with the furnace heat transfer requirements; little wonder then that poor performance is often the result. A burner is a transducer since it transforms one form of energy into another form of energy. In the case of the burner, it transforms the chemical energy in the fuel into heat energy within the furnace using the chemical reactions in a flame. The effectiveness with which this is achieved is a measure of its performance. Gas burners are generally classified as premixed or turbulent jet diffusion burners, such as premixed burners, where the fuel and most of the air are mixed together prior to passing through the nozzle and turbulent jet diffusion burners, where the fuel and most of the air are introduced separately and are mixed within the furnace. Burners and furnaces are also classified by the air delivery system as natural draught, forced draught, induced draught and balanced draught. Oil burners have the added complexity of two-phase flow resulting from the spray of fuel. Pulverized coal firing has many advantages over other forms of coal firing and makes burning coal similar to oil firing from a process viewpoint. Pulverized coal burners are similar to oil burners but the atomizer is replaced with a coal nozzle. The fine coal is air conveyed to the nozzle. Burners are often specified and selected from a catalogue based on little more than the estimated heat liberation required for the furnace, the number of burners needed and the price of the burner.

A shift from coal to liquefied natural gas for electricity generation can mitigate CO2 emissions and respond to the intermittent and variable characteristics of renewable energy. With this objective, numerical simulation was performed in this study to determine the optimal position of the methane injector and evaluate the achievable reduction in NO x emissions before applying methane cofiring to an existing 550 MW tangentially fired pulverized-coal boiler (Boryeong Unit 3). The combustion and NO x reduction in the furnace were intensively analyzed based on the methane cofiring rate (up to 40%). The optimal position of the methane injector was found to be inside the oil port based on the spatial distribution of NO x and the stoichiometric ratio along the furnace height. The NO x reduction rate was logarithmically proportional to the methane cofiring rate, and compared to the base case, a 69.8% reduction was achieved at the 40% cofiring rate. In addition, the fraction of unburned char at the boiler outlet was equivalent to that of the existing boiler as the increase in the flow rates of the close-coupled and separated overfire air improved fuel and air mixing. Simultaneously, methane cofiring led to a reduction in the total fuel loss and CO emissions. Finally, this study showed that the recommended optimum cofiring rate was 20% based on the furnace exit gas temperature. Under the 20% methane cofiring condition, the boiler achieved a 57.3% reduction in NO x emissions and a 7.4% improvement in fuel loss.

Circulating fluidized bed fly ash (CFBFA), the solid waste discharged from thermal power plants using circulating fluidized bed boilers, has significantly different properties to the fly ash produced in pulverized coal boiler (PCFA) units because of the relatively low combustion temperature used. Thus, CFBFA cannot be used as a direct replacement for PCFAs. Nevertheless, the use of CFBFA in construction materials is the most promising method for the large-scale waste-to-resource transformation and disposal of CFBFA. In this review, the CFBFA is classified according to the desulfurization process used in the CFB boiler, and we also summarize the physicochemical properties and hazards of CFBFA, and discuss its potential applications in the construction industry, In particular, we focus on the preparation of aerated or roller-compacted concrete and zero-cement binders, which are ideal methods for recycling CFBFA. Finally, suggestions for future research and the prospects of recycling CFBFA in the construction industry are proposed.

Background: Pulverized coal detection is an indispensable detection measure in the coal industry. The current detection devices can be divided into two types: invasive and non-invasive. The coal dust detection methods and devices based on acoustics, optics, and electricity have been extensively studied. In order to achieve a high-efficiency online detection scheme, improving the accuracy and stability of the detection means is the primary goal of the research. Objective: The general problems and characteristics of coal dust detection device design are summarized, as well as recent technological developments and the need for online testing to predict future research trends. Methods: The current typical detection devices are classified according to the detection principle and whether they invade the target, analyzing its advantages and disadvantages according to the device performance and application scenarios. Results: It has a beneficial effect on the design of the pulverized coal concentration detection device. Conclusion: The paper summarizes and analyzes several representative coal concentration detection device patents in recent years. Then it points out advantages and main problems. On this basis, the main development direction of the coal dust concentration detection device in the future is discussed.

Medium oxygen-enriched blast furnaces that utilize reducing gas injections are a feasible new ironmaking process that can significantly reduce the coke ratio and carbon dioxide emissions. To better inject the reducing gas into the blast furnace, two injection methods were designed in this study, and the effects of the reducing gas on the combustion of pulverized coal in three types of medium oxygen-enriched processes were studied using a three-dimensional lance-blowpipe-tuyere-raceway model. The reducing gas was injected into the blowpipe from a sleeve spray lance, which was suitable for injecting a small amount of reducing gas. The optimal coal burnout was 6% higher than that of a traditional blast furnace (TBF). The reducing gas was also directly injected into the raceway from a spray lance, which was suitable for injecting a large amount of reducing gas. The optimal coal burnout was 13% higher than that of a TBF using this system.

The state of and development prospects for the technology of selective noncatalytic reduction (SNCR) of nitrogen oxides in the combustion products of organic fuels are considered. Its advantages and disadvantages and factors influencing the efficiency of its application for gas purification of technological furnaces for natural gas conversion at power and waste incineration boilers are analyzed. The results of experimental studies into the process of reducing nitrogen oxides by products of thermal decomposition of carbamide are presented, depending on the temperature, flow rate, and the method of introducing the reagent into the flue gases. The results of pilot tests and industrial implementation of the technology are shown. The possibility of increasing the technical and economic indicators of SNCR plants by organizing a multizone injection of the reducing mixture into the gases to be cleaned with a flow rate less than the stoichiometric one is substantiated, which makes it possible to achieve high technology efficiency with a minimum ammonia slip. Relatively low capital costs for the construction of SNCR plants and the manufacture of main equipment at domestic enterprises and the small area required for equipment placement can significantly reduce emissions of nitrogen oxides into the atmosphere, even at operating boilers in a short time. It is advisable to widely introduce SNCR technologies at pulverized coal TPPs and enterprises for thermal waste disposal as one of the best available technologies.

This article presents the statistical data of power steam boilers installed at combined heat and power plants in Russia. This work also summarizes the experience of creating Russian boilers, starting from the first Ramzin straight-through boiler and ending with powerful boilers for a 1200-MW gas/oil unit and 800-MW pulverized coal unit. Notably, following the main global tendencies, Russian boiler plants are ready to create modern boilers for both ultra-supercritical parameters and circulating fluidized bed units and boilers for burning nonconventional fuels.

During coal and coal gangue combustion, many heavy metal pollutants are emitted and cause serious environmental problems. In this paper, the environmental effect values of As and Pb emission during coal gangue and coal combustion in the 330 MW pulverized coal boiler, 50 kW circulated fluidized bed boiler and laboratory were calculated by ReCiPe2016. The results show that when coal combustion in 330 MW pulverized coal boiler, the environment effect values of as for bottom slag, fly ash and flue gas are 3.28×10−6, 2.68×10−5 and 3.89×10−3 respectively; while the environment effect value of Pb for bottom slag, fly ash and flue gas are 8.57×10−6, 6.00×10−5 and 4.83×10−2, respectively. The environmental effects of As and Pb in bottom slag are lower than those in the fly ash; and the environmental effects of As and Pb on air are higher than those on soil. Moreover, when coal combustion in the 50 kW circulated fluidized boiler, the effect values of As and Pb in fly ash on environment are 3.26×10−5 and 1.28×10−4; and the effect values of As and Pb in bottom slag are 1.16×10−6 and 1.43×10−5 respectively. The results also show that when coal gangue combustion in the laboratory, the effect values of As and Pb emission increase with increasing of the temperature; and the proportions of total environmental effects of As and Pb on air are higher than those on soil. Besides that, this study also indicates that the effect of Pb emitted into environment is higher than that of As at the same conditions during coal combustion both in circulated fluidized boiler and pulverized coal boiler. The results may provide basic data for predicting the environmental effects of As and Pb during coal gangue combustion in circulating fluidized bed for life cycle impact assessment.

Introduction. International experience provides many examples of highly efficient use of biomass for heat and electricity production in coal-fired boilers. For Ukraine that has large coal deposits and a potential of solid plant biomass, such technology has not been implemented yet. Problem Statement. Given the scarcity of anthracite group coal, searching for new non-project fuels for thermal energy is an urgent task in the view of Ukraine’s commitment to increase renewable energy production and the need to comply with strict European emission standards. Purpose. Development of optimal technological and operational conditions for co-firing of anthracite group coal and solid biomass. Materials and Methods. The objects of research are pulverized Ukrainian coal and solid biomass of plant origin. Experimental research methods with laboratory and pilot plants, as well as CFD modeling have been used. Results. Blends of coal and biomass burning conditions have been studied; optimal scheme for TPP-210A coal-fired boiler has been recommended; balance calculations in the joint torch that burns anthracite and solid biofuels have been made; according to the chosen design scheme a burner for biomass and coal co-firing for coal-fired boilers TPP-210A have been implemented and preliminary design of the burner has been prepared. The project can be used at any TPP-210A power boiler units, and with minor changes at most boilers that burn anthracite and lean coal. Conclusions. The use of 8-12% of biomass by heat can essentially intensify the processes of anthracite coal. It is recommended to supply biomass pellets from a separate tank via a special mill to the burner where fuel is injected into the pipeline with a conical divider at output. 3D modeling of co-firing has shown a temperature flow and a fuel burn-out growth. A preliminary design of the boiler burner TPP-210A for co-combustion of anthracite and 10% biomass has been made.

In order to reduce the CO2 emission of an existing 600MWe power plant in Hubei Province of China, a 30MWth biomass CFB gasifier was built to co-fire of the product gas in the pulverized coal boiler. Experiments were conducted with rice husks as the fuel. Different operation conditions, temperatures and loads, are investigated for their effects on the compositions, calorific properties, gasification efficiencies, carbon conversions and tar production. It was found that under the different working condition, the temperature curves along the riser height are similar, and temperatures at the bottom are higher than the top temperatures. The combustible components, calorific value and gasification efficiency of gas first increase and then decrease with temperature rise. The maximum calorific value and the maximum gasification efficiency of gas were 5751 kJ/Nm3 and 73.41%, respectively, at 789°Cand 814 °C. The gasification system runs smoothly under different loads, and the best gasification condition occurs at 30 MWth.

Coal gasification fine ash (CGFA) having high carbon content is produced in large quantity as a by-product from coal gasifiers in China. CGFA is usually disposed of by landfill as a solid waste, wh...

The problems of using pulverized coal to save coke during iron smelting in the NLMK blast furnaces are considered. The iron smelting technology was implemented in two stages: (i) commissioning of the pulverized-coal preparation and charging system and (ii) selection of charging system and blast conditions that ensure the maximum utilization of pulverized coal and required output. An analysis of the dynamics in the consumption of coke and fuel additives showed that the total fuel carbon consumption has decreased, despite the difference in the amount of carbon charged with natural gas and pulverized coal. The calculations based on a mathematical model showed that with increase in the consumption of pulverized coal and decrease in the consumption of natural gas, the gas-to-coke replacement ratio increases by 0.09 kg of coke per 1 m3 of natural gas on average.

The chemical properties of coal extracts play a crucial role in understanding coal structure, constructing coal model, and developing clean coal technology. However, there is little knowledge about...

The possibility of increasing the reactivity of low grade Kansk-Achinsk brown coal 2 BR from the Irsha-Borodino deposit due to mechanically activated micronizing by means of special mill disintegrators has been shown on the 5-MW experimental firing stand at the Institute of Thermophysics SB RAS (IT). This coal is used in the coal-fired PK-38 boiler of station 2B of the Krasnoyarsk State District Power Station-2 (SDPS-2). The experimental studies to ensure ignition and achievement of stable autothermal coal combustion have yielded the minimum operation time of the gas ignition device; to determine the effect of temperature on the ignition and combustion, the temperature of the burner muffle wall was controlled. In accordance with the experimental data on burning the coal with increased reactivity and the economic efficiency evaluation, the coal can be recommended for replacement of highly reactive fuel oil for ignition and lighting of the boiler considered.

In Japan, a feed-in tariff was introduced to promote and expand the renewable energy ratio to 22-24% by FY 2030. Biomass is one of important renewable energy. Recently, several biomass projects for not only fluidized bed boilers, but also pulverized coal fired boilers, are being planned around the world to reduce CO2 emissions as the main reason. The required particle size of woody biomass for combustion in a pulverized coal fired boiler is around 1mm, while that of coal is several tens of m. Woody biomass particles grinded by a mill are sent to burners via a fuel pipe by air. It is important to measure the particle size distribution in order to understand combustibility and grindability. However, it was unknown whether the particle size distribution could be measured by the same sampling method for pulverized coal. We conducted sampling tests of woody biomass particles in a fuel pipe using the isokinetic sampling method. As a result, we observed that the flow of woody biomass particles in the pipe was significantly non-uniform to the influence of the upstream elbow. It is necessary for woody biomass to measure at a pitch of at least 45 in order to obtain the particle size distribution in a fuel pipe.

Highways play an important role in developing the country. Highways affect directly on the economy, society, culture and security, so the scientists are looking for developing the performance of highways and low maintenance cost. The main objective of this study is to modify the bituminous mixed by utilization of waste industrial materials. , There are many wastes industrial materials can be used in bitumen. A study has been carried out in this search to illustrate the use of fly ash, (byproduct of combustion Pulverized coal in power plants , it produced during combustion of coal in bituminous paving mixes), Silica Fume,( by- product of producing silicon metal or ferro silicon alloys in smelters using arc furnaces) . For comparison, control mixes with modified bituminous mixes has been considered. Marshall Test has been conducted for the purpose of mix design as well as appreciation of paving mixes. It is observed that the mixes with fly ash and silica fume as modifiers modify the properties compared to control mixes. In this paper Silica Fume and Fly Ash are used as a modifier. Marshall stability test was conducted according to( ASTM D 6927-06 ). The percentages of modified mixtures used are 2, 4, 6, 8 and 10 % by bitumen weight. The results showed that the Marshall stability modified with SF and F.A were increased by 18.4% and 22.3 % respectively. So, we can concluded that adding SF and FA to asphalt binder success in improving the properties of bituminous mixes for flexible pavement. Hence, it has been recommended to utilize Silica Fume and Fly Ash wherever available, not only reducing the cost of construction, but also solve the bituminous mixes properties. Keywords: Marshall Stability test, S.F, F.A, bituminous mixes, waste industrial material

Partial substitution of pulverized coal (PCI) by renewable biocarbon for blast furnace injection is a practical approach to reduce GHGs in the steel production sector. For using biocarbon as feedst...

Circulating fluidized bed (CFB) boilers has realized the clean and efficient utilization of inferior coal like gangue and coal slime, high sulfur coal, anthracite, petroleum coke, oil shale and other resources. As a country with the largest amount of CFB boilers and the largest installed capacity in the world, China has 440 100–600 MWe CFB boilers with a total capacity of 82.29 GWe, including 227 units of 135 MWe, 95 units of 300 MWe, and 24 supercritical units. The statistics of typical 100–300 MWe CFB boilers showed that the average number of unplanned shut-down was only 0.37 times per year, among which the 135 MWe was 0.26 times per year and 300 MWe was 0.46 times per year. The auxiliary power ratio of some 300 MWe CFB boilers based on flow-pattern reconstruction can be reduced to about 4%, which is closed to the same level of pulverized coal (PC) boilers. This paper summarizes the development process and application status of China’s large-scale CFB boilers, analyzes the characteristics and technical performance of the iconic units, and introduces solutions to the problems such as water wall wear and bottom ash cooling.

The utilization of agricultural wastes in existing pulverized coal power plants is an attractive option to alleviate environmental pollution and reduce over-exploitation of fossil fuels. A coupled system model of biomass gasification coupled to a coal-fired boiler is established in Aspen Plus and successfully validated by experimental data. A 20 t/h straw gasifier operates at the rated capacity and the straw gas is introduced to the boiler running at different loads. The co-firing ratio increases with the reduction of boiler load. Results indicate that the main parameters, such as furnace combustion temperature, flue gas temperature, and NO and SO2 emission decrease with the reduction of boiler load. Compared to pure coal combustion, co-firing can reduce the furnace combustion temperature and increase the flue gases temperature. More importantly, the coal consumption, and NO and SO2 emissions are reduced at all loads, especially at lower loads. The excess air ratio should be adjusted to obtain the optimum combustion performance in the furnace, but there is still a slight drop of around 0.2% in boiler efficiency when co-firing. Meanwhile, the coupled system efficiency at various loads can reach slightly more than 84% under optimum conditions.

Currently, volatile matter is generally treated as a postulate substance or a mixture of light gases and tar with given proportion in pulverized coal combustion (PCC) simulation. Whether those trea...

This article considers the industrial cases of a blast furnace operated with scull slipping and channeling. A set of measures for preventing major violations in the run of blast furnaces operated on pulverized coal injection is developed and adopted.

Co-gasification of coal with biomass is a novel way to utilize biomass energy and is a new research focus in clean coal technology. A thorough knowledge of the flow properties of biomass and coal b...

Green concrete is the latest development in the field of construction technology which offers a sustainable and eco-friendly solution as a building material. The cement used in conventional concrete is responsible for releasing high amount of carbon dioxide which is harmful for the environment. The concept of green concrete renders replacement of cement partially or fully by various materials which are either by-products in the production process of other materials or recycled waste. This paper presents the design of green concrete by partially replacing cement by fly ash, which is obtained by burning pulverized coal in electric power generating plants and completely replacing fine aggregate by a 50%–50% combination of glass powder and demolished waste obtained from the construction site and converted to fine powdered form. Further a comparison has been done among the properties of conventional and green concrete followed by a cost/benefit analysis to recommend the use of green concrete as a sustainable building material.

One of the TPP’s electricity cost price components is the fuel cost. An increase in the performance of TPPs is possible by using cheaper alternative coal, the main characteristics of which are close to those of standard quality coal. Recently, there has been a tendency for using other types of coal and nonstandard types of fuel in pulverized coal-fired boilers. Thermal power plants in Finland, France, and Denmark use wood raw-material and paper waste, as well as other biofuels, to generate electricity. The simplest and least costly way of cofiring coal and biomass is to mix them and then feed them into the furnace of a pulverized coal-fired, dry-bottom boiler. In this way, it is possible to burn approximately 5% of biomass in the mixture. In cyclone-furnace boilers, it is possible to burn at least approximately 20% of biomass; however, this will require significant boiler reconstruction. In grate stokers, 100% of the biomass can be burned, but fluidized bed combustion is only suitable for small TPPs. In Russia, oil extraction waste, namely sunflower husks, can be used as biofuel in the form of pellets. The article discusses the experience of burning nonconventional solid fuels in pulverized coal-fired boilers, the advantages and disadvantages of this type fuel, and the problems of arising in its utilization.

CCS (Carbon Dioxide Capture and Storage) is one of the technologies able to adequately displace CO2 from fossil fuel fired power plants and the only technology capable of reducing large-scale emissions. In particular, coal emits a lot of CO2, although it is an important energy resource in terms of energy security. To address this situation, IHI had developed oxyfuel combustion technology to capture CO2 from coal-fired power plants, and the demonstration using a 30MWe unit in Australia was successfully carried out. In order to commercialize the technology widely, how to configure the primary gas system is one of the important examination items. When adding oxygen into the primary gas system, depending on the type of mill, pulverized coal deposited in the mill may ignite spontaneously. To investigate the spontaneous combustion characteristics of the deposited pulverized coal under oxyfuel conditions, therefore, laboratory-scale experiments were carried out. The pulverized coal was deposited in a 100mm square mesh box, and it was installed in a thermostatic chamber. Then the mixed gas of N2/O2 or CO2/O2 was introduced into the chamber, and the temperature in the coal sample was measured. From the results, there was little temperature difference at which spontaneous combustion occurred between N2/O2 and CO2/O2 atmosphere, while there was a tendency that it might be relatively hard to occur under CO2/O2 atmosphere. The results also showed a tendency that the influence of temperature was stronger than the oxygen concentration.

The adverse effect of ultrafine particulate matter (PM) from the combustion of solid fuels calls for fundamental insights to guide effective control strategies. In this work, we investigated the ul...

The method for calculating indicators of blast furnace smelting with replacement of part of coke with additional fuels has been developed on the basis of full and complex compensation and compensating measures. Efficiency of the use of natural gas and pulverized coal in the blast furnace conditions of the Enakievo Metallurgical Plant was calculated and it has been confirmed as rather high. Increase in the consumption of natural gas from the baseline (71.8 m3/t of iron) to 110 m3/t ensures a corresponding increase in productivity of the blast furnace to 107.6 % and a decrease in the consumption of coke to 417.3 kg/t of iron (–38.4 kg/t, –8.42 %). Replacing natural gas with pulverized coal in the amount of 160 kg/t of iron made it possible to completely remove it from the blast. At the same time, coke consumption decreased to 354.59 kg/t of iron (–101.1 kg/t; –22.18 %). Increasing the consumption of pulverized coal fuel up to 200 kg/t of iron with compensation of the blast temperature of1200 °Cand oxygen of the blast of 25 % provides an increase in the productivity of the blast furnace to 105.8 % and reduction of coke consumption to 303.8 kg/t of iron (–151.9 kg/t, –33.33 %). High efficiency of the use of pulverized coal in conditions of the Enakievo Metallurgical Plant is explained by its lower cost compared to natural gas, high carbon content in coal and a significantly lower effecton the theoretical combustion temperature and other technological parameters.

How to reduce nitrogen oxides in coal combustion process has always been a hot and difficult topic in the research process. In this paper, under the condition of circulating fluidized bed air equivalence ratio of 0.61 and gasification temperature of 970 °C, the partial gasification and combustion method is used to study the influence of the secondary air distribution modes on the gasification and combustion characteristics. Three aspects are discussed in this test: partial gasification characteristics, combustion characteristics, and coal-nitrogen migration and transformation characteristics. The experimental results show that under partial gasification conditions of the circulating fluidized bed, nearly 87% of the fuel nitrogen at the outlet of the circulating fluidized bed is converted into nitrogen in the coal gas, and the ratio of fuel nitrogen to N₂ is about 64.11%, the conversion rate of HCN is about twice that of NH₃, and the combustion reactivity of partial gasification fuels increased at the outlet of circulated fluidized bed. Different secondary air distribution modes will affect the combustion process and the temperature distribution of the combustion chamber. When the secondary air is mixed with the high-temperature coal-based fuel in advance, the entire combustion reaction and the maximum temperature point in the combustion chamber will be moved up. When secondary air is injected simultaneously with high-temperature coal-based fuels, NOₓ emissions are approximately 90 mg/m³ (@6% O₂), the conversion rate of fuel nitrogen to NOₓ is 2.09%, and when nearly half or all of the secondary air is directly premixed into the high-temperature coal-based fuel, the NOₓ emissions are about 70 mg/m³ (@6% O₂), the conversion ratio of fuel nitrogen to NOₓ is reduced to about 1.63%.

At present, the world is committed to the development of environmentally friendly, sustainable and industrial safety. The effective treatment of industrial solid waste can be applied in the field of industrial safety. It is one of the ways to apply industrial solid waste to industrial safety to modify industrial solid waste and combine active powder to prepare industrial solid waste-based composite powder explosion inhibitors and apply it to underground coal dust explosion. This paper introduces the modification and preparation methods of industrial solid waste, and analyzes the good explosion suppression effect and good economic benefit of industrial solid waste-based composite powder explosion inhibitors on coal dust explosion. In this paper, four kinds of industrial solid wastes (red mud, slag, fly ash and sludge) were modified, and the modified solid waste materials with good carrier characteristics were obtained. Combined with a variety of active powders (NaHCO3, KH2PO4 and Al(OH)3), the industrial solid waste-based composite powder explosion inhibitors were obtained by solvent-crystallization (WCSC) and dry coating by ball milling (DCBM). Those kinds of explosion inhibitors can suppress the explosion of pulverized coal in 40–50% of cases. Compared with the powder explosion inhibitor commonly used in industry, it has a lower production cost and better explosion suppression effect. Those kinds of explosion inhibitors have a good industrial application prospect.

Metal production, and especially iron ore-based steel production, is characterized by high fossil CO2 emissions due of the use of coal and coke in the blast furnace. Steel companies around the world are striving to reduce the CO2 emissions in different ways, e.g., by use of hydrogen in the blast furnace or by production of iron via direct reduction. To partially replace fossil coal and coke with climate neutral bio-coal products that are adapted for use in the metal industry, e.g., at the blast furnace, is a real and important opportunity to significantly lower the climate impact in a short-term perspective. Top-charging of bio-coal directly to the blast furnace is difficult due to its low strength but can be facilitated if bio-coal is added as an ingredient in coke or to the mix when producing residue briquettes. Bio-coal can also be injected into the lower part of the blast furnace and thereby replace a substantial part of the injected pulverized coal. Based on research work within Swerim, where the authors have been involved, this paper will describe the opportunities and limitations of using bio-coal as a replacement for fossil coal as part of coke, as a constituent in residue briquettes, or as replacement of part of the injected pulverized coal. Results from several projects studying these opportunities via technical scale, as well as pilot and industrial scale experiments and modelling will be presented.

A 0.5 MW class oxy-fuel boiler was developed to capture CO2 from exhaust gas. We adopted natural gas as the fuel for industrial boilers and identified characteristics different from those of pulverized coal, which has been studied for power plants. We also examined oxy-fuel combustion without flue gas recirculation (FGR), which is not commonly adopted in power plant boilers. Oxy-fuel combustion involves a stretched flame that uniformly heats the combustion chamber. In oxy-natural-gas FGR combustion, water vapor was included in the recirculated gas and the flame was stabilized when the oxygen concentration of the oxidizer was 32% or more. While flame delay was observed at a partial load for oxy-natural-gas FGR combustion, it was not observed for other combustion modes. In oxy-fuel combustion, the flow rate and flame fullness decrease but, except for the upstream region, the temperature near the wall is distributed not lower than that for air combustion because of the effect of gas radiation. For this combustion, while the heat flux is lower than other modes in the upstream region, it is more than 60% larger in the downstream region. When oxy-fuel and FGR combustion were employed in industrial boilers, more than 90% of CO2 was obtained, enabling capture, sequestration, and boiler performance while satisfying exhaust gas regulations.

Oxy-combustion is recognized as the cleanest technology which uses coal as an energy source. Flue gas clean-up is essential for sustainable operation. In this work, the optimal selection of the flu...

With ever increasing share of renewable energy sources in the electricity mix, pulverized coal-fired power plants (PCPP) have to participate in peak load regulations frequently and thus, they regularly operate under partial loads. The energy efficiency and eco-efficiency are both significantly affected by such operating patterns. Therefore, the present work aims to establish an overall concept for the estimation of environmental impacts from PCPP under nominal and partial loads with combined thermodynamic analysis and life cycle assessment (LCA) methodology. A 1000 MW supercritical PCPP was modeled using commercial simulation software (GSE for thermodynamic simulation and SimaPro for LCA analysis). Results indicated that global warming was the predominant environmental impact of PCPP, while ozone formation, acidification and eutrophication were also serious concerns attributed to NOx emissions in electricity generation process. The mechanisms of formation, migration and removal of different kinds of pollutant emissions significantly influenced the LCA results. Particularly, the total environmental impact potential considerably increased by approximately 90% under partial/low loads due to reductions in the plant thermal efficiency and NOx removal efficiency. A novel partial load No.0 feedwater preheating system driven by steam ejector was thus proposed for NOx reduction improvement. Operation optimization was carried out based on the guidelines of the LCA framework. It was found that the total environmental impact could be effectively reduced by up to 27.3%. Therefore, the implementation of the No.0 feedwater pre-heater was favorable for environmental performance improvement under partial/low loads.

In recent years, circulating fluidized bed combustor (CFBC) has been regarded as a viable alternative to the conventional pulverized coal combustor (PCC) for utility-scale coal power generation owing to its superior technology for fuel flexibility and supercritical (SC)/ultra supercritical (USC) steam circuit adaptability. The objective of this study is to analyze the economic feasibility of a 600MWe USC CFB boiler, in which coal or a mixture of coal and biomass would be used as fuel. After the demonstration and commercialization of SC CFBC units had succeeded up to 600MWe, USC CFBCs have been widely developed throughout the world. Although high capital costs, high auxiliary power use, and technology maturity have hindered the adoption of USC CFBC for utility power generation, the demand of cleaner environments and energy conversion have driven communities to develop and adopt USC CFBC. Its economic feasibility was evaluated in terms of net present value (NPV), benefit/cost ratio (B/C ratio), and internal rate of return (IRR). In particular, the effect of coal tax and domestic biomass co-combustion on economic efficiency was analyzed.

Reducing CO2 emissions by around 80% by the year 2050 is the central climate goal and requires both energy suppliers and industry to prepare themselves and explore new pathways together. The vision is to move away from carbon via bridging technologies based on natural gas with DRI/HBI production and finally on to the greatest possible use of green hydrogen in steelmaking. Direct reduced iron (DRI) can be used after briquetting in form of HBI in the blast furnace to decrease the consumption of coke and/or pulverized coal as well as to increase the production of hot metal.

One of the most important issues for modern domestic power industry is the creation and further widespread introduction of solid propellant energy units for super-critical steam parameters with high efficiency (43–46%) and improved environmental parameters. This will significantly reduce the use of natural gas.At the same time, one of the major drawbacks of the operation of pulverized coal power units is the need to use a significant amount of fuel oil during start-up and shutdown of boilers to stabilize the burning of the coal torch in the variable boiler operating modes.In this regard, solid fuel TPPs need to be provided with fuel oil facilities, with all the associated problems to ensure the performance (heating of fuel oil in winter), reliability and safety. All of the above problems increase both the TPP capital construction costs, and the electricity generating cost.A practical solution to the above problems at present is the use of a plasma technology for coal torch ignition based on thermochemical preparation of fuel for combustion. The materials of the developments of JSC “NPO CKTI” on application of plasmatrons in boilers of thermal power plants at metallurgical complexes of the Russian Federation are also considered.Plasma ignition systems for solid fuels in boilers were developed by Russian specialists and were introduced at a number of coal-fi red power plants in the Russian Federation, Mongolia, North Korea, and Kazakhstan. Plasma ignition of solid fuels is widely used in China for almost 30% of power boilers.The introduction of plasma-energy technologies will improve the energy efficiency of domestic solid-fuel thermal power plants and can be widely implemented in the modernization of boilers.During the construction of new TPPs, the construction of fuel oil facilities can be abandoned altogether, which will reduce the capital costs of the construction of thermal power plants, reduce the construction footprint, and increase the TPP safety.

This study investigated nitrogen oxide (NOx) emissions of pulverized coal combustion preheated by a circulating fluidized bed (CFB). During the test process, high-temperature fuel preheated in a CFB was burned in a down-fired combustor (DFC). The effect of air distribution on NOx emissions was studied in the DFC, including three types of secondary air nozzle structures, five secondary air ratios, and three tertiary air position arrangements. Under stable conditions, the conversion ratio of fuel-nitrogen to N2 in the CFB was 41.4%, which resulted in lower NOx emissions in the platform. In this study, secondary air could be injected into the combustor at the top (annular) or through the side wall (circular) of the DFC, both with high combustion efficiency. This means that the secondary air is completely separated from the burner, and burner structure is greatly simplified. NOx emissions from secondary air nozzle structures of center, annular, and circular ports were 565.66, 345.45, and 220.38 mg/Nm3 (@6% O2) respectively. NOx emissions initially decreased then increased with increases in secondary air ratio with the annular nozzle structure. NOx emissions could be further inhibited by rationally arranging tertiary air positions.

Low NOx burner and air staged combustion are widely applied to control NOx emission in coal-fired power plants. The gas-solid two-phase flow, pulverized coal combustion and NOx emission characteristics of a single low NOx swirl burner in an existing coal-fired boiler was numerically simulated to analyze the mechanisms of flame stability and in-flame NOx reduction. And the detailed NOx formation and reduction model under fuel rich conditions was employed to optimize NOx emissions for the low NOx burner with air staged combustion of different burner stoichiometric ratios. The results show that the specially-designed swirl burner structures including the pulverized coal concentrator, flame stabilizing ring and baffle plate create an ignition region of high gas temperature, proper oxygen concentration and high pulverized coal concentration near the annular recirculation zone at the burner outlet for flame stability. At the same time, the annular recirculation zone is generated between the primary and secondary air jets to promote the rapid ignition and combustion of pulverized coal particles to consume oxygen, and then a reducing region is formed as fuel-rich environment to contribute to in-flame NOX reduction. Moreover, the NOx concentration at the outlet of the combustion chamber is greatly reduced when the deep air staged combustion with the burner stoichiometric ratio of 0.75 is adopted, and the CO concentration at the outlet of the combustion chamber can be maintained simultaneously at a low level through the over-fired air injection of high velocity to enhance the mixing of the fresh air with the flue gas, which can provide the optimal solution for lower NOx emission in the existing coal-fired boilers.

We analyze the effect of application of pulverized coal fuel (PCF) and natural gas on the parameters of blast-furnace smelting by an example of operation of blast furnaces in Ukraine (for the best periods of their operation). It is shown that the rational technology of blast furnace smelting performed with the use of PCF enables one to increase the productivity of blast furnaces, reduce the consumption of coke and conventional fuel, decrease the cost of power resources, preserve the ecological characteristics, decrease the consumption of the resources, improve the ecology. At the same time, this leads to an increase in the net amount of fuel required for the blast-furnace process and to a decrease in the yield of secondary energy resources to the consumers. The simultaneous injection of natural gas with PCF increases the lifetime of the furnace, decreases the heat losses, and increases the gas permeability of the charge.