造气全烧小粒煤总结

针对造气试烧小粒煤过程中出现的问题 ,通过具体分析 ,调整工艺指标 ,改造部分设备 ,优化操作条件等措施 ,实现了造气全烧小粒煤 ,年创经济效益

造气全烧小粒煤总结

介绍小氮肥厂造气炉由烧大、中块煤改为烧小粒煤过程中存在的一些问题,并加以解决,经运行后效果明显。

Advances in LES of Two-phase Combustion(Ⅱ) LES of Complex Gas-Particle Flows and Coal Combustion

Large-eddy simulation(LES) is under its rapid development and is recognized as a possible second generation of CFD methods used in engineering.Large-eddy simulation of two-phase flows and combustion is particularly important for engineering applications.Some investigators,including the present authors,give their review on LES of spray combustion in gas-turbine combustors and internal combustion engines.However,up to now only a few papers are related to the state-of-the-art on LES of gas-particle flows and combustion.In this paper a review of the advances in LES of complex gas-particle flows and coal combustion is presented.Different sub-grid scale(SGS) stress models and combustion models are described,some of the main results are summarized,and some research needs are discussed.

Influence of sulfur content in raw materials on oxidized pellets

The influence of sulfur content in raw materials on oxidized pellets was studied. The results show that most sulfur exists in the form of elementary sulfur in pyrite cinder, and over 95% sulfur is removed in producing pyrite cinder oxidized pellets. The compressive strength of fired pellets drops from 3 186 N to 2 405 N when the ratio of pyrite cinder increases from 40% to 70% under the conditions of preheating at 900℃ for 9 min and firing at 1 230 ℃ for 15 min. The porosity and microstructures of fired pellets prove that the higher ratio of pyrite cinder is given, and the more holes and cracks are achieved, leading to the better reducibility index （RI） and reduction swelling index （RSI）, and the lower compressive strength of fired pellets and the worse reduction degradation index （RDI）.

Conversions of fuel-N, volatile-N, and char-N to NO and N_2O during combustion of a single coal particle in O_2/N_2 and O_2/H_2O at low temperature

Oxy-steam combustion is a promising next-generation combustion technology.Conversions of fuel-N,volatile-N,and char-N to NO and N2O during combustion of a single coal particle in O2/N2and O2/H2O were studied in a tube reactor at low temperature.In O2/N2,NO reaches the maximum value in the devolatilization stage and N2O reaches the maximum value in the char combustion stage.In O2/H2O,both NO and N2O reach the maximum values in the char combustion stage.The total conversion ratios of fuel-N to NO and N2O in O2/N2are obviously higher than those in O2/H2O,due to the reduction of H2O on NO and N2O.Temperature changes the trade-off between NO and N2O.In O2/N2and O2/H2O,the conversion ratios of fuel-N,volatile-N,and char-N to NO increase with increasing temperature,and those to N2O show the opposite trends.The conversion ratios of fuel-N,volatile-N,and char-N to NO reach the maximum values at 〈O2〉=30 vol%in O2/N2.In O2/H2O,the conversion ratios of fuel-N and char-N to NO reach the maximum values at 〈O2〉=30 vol%,and the conversion ratio of volatile-N to NO shows a slightly increasing trend with increasing oxygen concentration.The conversion ratios of fuel-N,volatile-N,and char-N to N2O decrease with increasing oxygen concentration in both atmospheres.A higher coal rank has higher conversion ratios of fuel-N to NO and N2O.Anthracite coal exhibits the highest conversion ratios of fuel-N,volatile-N,and char-N to NO and N2O in both atmospheres.This work is to develop efficient ways to understand and control NO and N2O emissions for a clean and sustainable atmosphere.

Numerical Analysis on the Characteristics of Soot Particles in C2H4/CO2/O2/N2 Combustion

The purpose of this study is to investigate the characteristics of soot particles in C2H4/CO2/O2/N2 com- bustion at equivalence ratio of 3.0-5.0. As the oxidant is switched from conventional air to CO2/O2/N2 mixture, the key species C2H2, C3H3 responsible for formation of first aromatic ring, the apical aromatics and 4zring aromatics total production rate all decrease greatly. In addition, with CO2 mole fraction from 0.2 to 0.5 in the mixture, the soot particle number density, volume fraction, surface area density, which are three most important parameters to soot oarticle orooertv, are suooressed obviously. Furthermore, the increasing content of C02 in the oxidizer influences mostly H, OH radical concentrations by two reactins CO ＋ OH == CO2＋ H and H ＋ O2===O＋ OH, and the procluction rate ofvo reactions declined, which revealed that C02 in mixture has an inhibiting ef- fect on soot particle generation.

Time Series of Combustion Characteristics and Particulate Emission during Combustion of Thai Lignite in a Fixed Bed

The combustion characteristics and particulate emission during combustion of Thai lignite with 30% of secondary air to total air （SA：TA） in a fixed bed combustor have been investigated in real-time. The results have shown that particle formation is governed by competing reaction between the formation of the nucleated sized-particles （Dp 〈 0.1μm） and the coagulated particle （Dp 0.1-1 μm）. Temperature and burning rate are the highest priority factors to control the emission of particulate. Furthermore, the co-firing of coal/rice husks at 60：40% mass fraction with 10%SA：TA could be the alternative options to further reduction of particulate and to be recommended.

Sintering of Pellets, Compound by Fly Ash, Clay and Charcoal in a Fixed Bed Combustion Reactor

Normally, industries in general, produce waste at its majority toxic, such as fly ash, for example, which damage the environment. The aim of this paper is to investigate the evolution of the temperature in a combustion reactor, full of pellets manufactured with fly ash, clay and charcoal powder, after sintering, to obtainment synthetic aggregates for use in civil construction. The pellets were produced in a cement mix. For realization of the work, a co-current combustion reactor was made in order to analyze the temperatures profile and investigate if the values of these temperatures would be sufficient to initiate the process of sintering of the pellets. Temperatures reached in the reactor varied in the range of 800 ℃-1,290 ℃. These values are sufficient to initiate the process of sintering of the pellets. For the experiment realized, parameters such as inlet velocity of the fluid （air）, diameters of the pellets and size of charcoal crushed in a disk mill were varied and the effect of variations of these parameters were analyzed for the experiment. The historical temperatures were recorded by a data acquisition instrument and subsequently plotted for analysis.

Emission Factors of Particulate Matter Emitted from Co-Firing of Thai Lignite and Agricultural Residues in Fixed Bed Combustor

Emission factors （EFs） of particulate matter （PM） derived from mono and co-firing of Thai lignite and agricultural residues have been investigated. Two sampling methods for PM, total filtration （TF） and electrical low-pressure impactor （ELPI）, were used together. The study is focused on the influence of fuel mass fraction, and of secondary air to total air; SA：TA on EFs of PM. The results have shown that EFs of PM in mass-basis given by TF method are 8.9, 5.3 and 8.1 mg/kgfuel, while 3.3, 2.7 and 3.3 mg/kgfuel when using ELPI, for firing at constant SA：TA （30%） of lignite, rice husk and bagasse, respectively. For co-firing with 30%SA of coal/rice husk, higher EFs of PM is observed. They are 7.17 and 10.9 mg/kgfuel （TF） for 40 and 70% rice husk share, respectively, or 4.18 and 5.19 mg/kgfuel （ELPI）. However, lower PM emission; 1-3.3 mg/kgruel （TF） or 0.72-2.83 mg/kgfuel （ELPI） are obtained during co-firing of coal/rice husk with lower degree of air staging （i.e. 0-10% SA：TA）. For the influence of oxygenation state, increasing of SA： TA leads to a low formation of ultrafine particles （Dp 〈 0.1 μm）. Apart from PM, major gases （CO, NO, SO2） will be documented in this paper.

Experimental Studieson Gas－Particle Flows and Coal Combustion in New Generation Spouting－Cyclone Combustor

Based on previous studies,an improved non-slagging spouting-cyclone combustor with two-stage combustion, organized in perpendicularly vortexing flows, is developed for clean coal combustion applied in small-size industrial furnaces and domestic furnaces. The isothermal model test and the combustion test give some encouraging results. In this studyt further improvement of the geometrical configuration was made, a visualizatiou method and a LDA system were used to study the gas-particle flow behavior,and the temperature and gas composition in combustion experiments were measured by using thermocouples and a COSA-6000-CD Portable Stack Analyzer. Stronger recirculation in the spouting zone and the strongly swirling effect in the cyclone zone were obtained in the improved combustor. The combustion temperature distribution is uniform. These results indicate that the improved geometrical configuration of the combustor is favorable to the stabilization of coal flame and the intensification of coal combustion, and it provides a basis for the practical application of this technique.

Fast Ignition and Stable Combustion of Coarse Coal Particles in a Nonslagging Cyclone Combustor

A combustion set-up of an innovative nonslagging cyclone combustor called 'Spouting-Cyclone Combustor (SCC)' ) with two-stage combustion, organized in orthogonal vortex flows, was established and the experimental studies on the fast ignition and stable combustion of coarse coal particles in this combustor were carried out. The flame temperature versus ignition time and the practical faSt ignition procedure were obtained; The stable coal combustion can be achieved after a short period ignition, and the temperature fields in SCC were obtained. These results show that it is possible to obtain highly efficient and clean combustion of unground coal particles by using this technology.