Study of the possibility of thermal utilization of contaminated water in low-power boilers

The utilization of water contaminated with oil products is a topical problem for thermal power plants and boiler houses. It is reasonable to use special water treatment equipment only for large power engineering and industry facilities. Thermal utilization of contaminated water in boiler furnaces is proposed as an alternative version of its utilization. Since there are hot-water fire-tube boilers at many enterprises, it is necessary to study the possibility of thermal utilization of water contaminated with oil products in their furnaces. The object of this study is a KV-GM-2.0 boiler with a heating power of 2 MW. The pressurized burner developed at the Moscow Power Engineering Institute, National Research University, was used as a burner device for supplying liquid fuel. The computational investigations were performed on the basis of the computer simulation of processes of liquid fuel atomization, mixing, ignition, and burnout; in addition, the formation of nitrogen oxides was simulated on the basis of ANSYS Fluent computational dynamics software packages, taking into account radiative and convective heat transfer. Analysis of the results of numerical experiments on the combined supply of crude oil and water contaminated with oil products has shown that the thermal utilization of contaminated water in fire-tube boilers cannot be recommended. The main causes here are the impingement of oil droplets on the walls of the flame tube, as well as the delay in combustion and increased emissions of nitrogen oxides. The thermal utilization of contaminated water combined with diesel fuel can be arranged provided that the water consumption is not more than 3%; however, this increases the emission of nitrogen oxides. The further increase in contaminated water consumption will lead to the reduction of the reliability of the combustion process.     

微油-少油技术在双旋风燃烧器W形火焰锅炉点火及稳燃试验

结合锅炉燃用难燃煤种需要耗费大量燃油进行点火及低负荷稳燃,把微油-少油技术在W形火焰锅炉双旋风燃烧器上进行了冷态模化、热态试验和工业性试验。试验结果表明:采用带助燃风、分级点火的方法可以实现微油冷态点火,采用少油燃烧器能实现锅炉低负荷稳燃,两种燃烧器均可实现节约燃油的目标。     

外燃式微油点火燃烧器机理及应用

针对火电厂煤粉锅炉冷态节油点火、低负荷稳燃、煤种适应性提高、低NOx运行等要求,开发了新型外燃式微油点火燃烧器,点火燃油量在100 kg/h左右,该燃烧器同时作为主燃烧器使用,并具有低负荷稳燃与低NOx功能。5台锅炉的工业应用结果表明,外燃式微油点火燃烧器可实现锅炉冷态点火,煤粉燃尽率在82%以上,可实现不投油自然停炉,NOx下降率为25%左右,结合燃尽风后NOx下降率达55%左右。中心风是该燃烧器的主要调节手段,数值计算表明,调节中心风可以改变燃烧器出口回流区长度,从而调节煤粉着火点位置。     

新型煤粉燃烧器--PCSB燃烧器的研制及开发

用火焰传播理论对现有燃烧器在稳燃方面存在的问题进行了分析,根据NOx生成机理对挖掘燃烧器的低NOx潜力进行论证。提出PCSB燃烧器的新构思和设计,PCSB燃烧器是根据煤粉气流分步燃烧原理、火焰传播理论以及强制点火原理研制开发的理念新颖,结构简便的新型煤粉燃烧器,阐述其低NOx原理和稳燃原理,归纳了其性能和特点。结合煤种特性总结PCSB燃烧器的设计原则。PCSB系列燃烧器对各种煤具有很好的适应性,非常适宜我国火电厂切圆燃烧锅炉和墙式燃烧锅炉推广应用。     

Study of Sequential Two-Stage Combustion in a Low-Emission Gas Turbine Combustion Chamber

In this paper, we analyzed advanced ground-based power gas turbine units with low-emission combustion chambers used for consecutive two-stage fuel combustion. Such low-emission combustion chambers have a wide range of stable performance modes with reduced emission of harmful substances. The two-stage combustion chambers used in gas turbine units of various capacities—small (for example, M7A-03 with a capacity of approximately 8–10 MW), medium (L20A and L30A with a capacity of 18–30 MW) and large (9HA and GT36 with a capacity of over 300 MW)—showed their universality, efficiency, and good possibilities for scaling. The designs of low-emission combustion chambers for gas turbine units of different capacities are fundamentally similar. They consist of two sequentially located combustion volumes (stages), and each of them has its own burner unit. The first burner unit is typical for low-emission combustion chambers with the combustion of the premixed air-fuel mixture and consists of swirlers, mixing zone, fuel injectors, and igniters. The second burner unit is located downstream, and air-fuel mixtures of a different composition are supplied into it through special holes. The combustion of the mixtures occurs at a lower oxygen content and higher temperature. The ignition, work until idling, and loading before switching to the low-emission mode and switching to it are performed by the operation regulation of the first burner unit. Fuel in the second burner unit is supplied when a certain temperature of the gases arriving from the first combustion stage is achieved, which ensures its self-ignition. The further load is regulated by the fuel supply to the second burner unit. The design implementation of the sequential two-stage combustion scheme and approaches to regulating fuel and air distribution over the stages that ensures stable nonpulsating combustion are different and so they are of great scientific and practical interest.     

Influence of the technique for injection of flue gas and the configuration of the swirl burner throat on combustion of gaseous fuel and formation of nitrogen oxides in the flame

How the points at which the flue gas was injected into the swirl burner and the design of the burner outlet influence the formation and development of the flame in the submerged space, as well as the formation of nitrogen oxides in the combustion products, have been studied. The object under numerical investigation is the flame of the GMVI combined (oil/gas) burner swirl burner fitted with a convergent, biconical, cylindrical, or divergent throat at the burner outlet with individual supply of the air and injection of the gaseous fuel through tubing. The burners of two designs were investigated; they differ by the absence or presence of an inlet for individual injection of the flue gas. A technique for numerical simulation of the flame based on the CFD methods widely used in research of this kind underlies the study. Based on the summarized results of the numerical simulation of the processes that occur in jet flows, the specific features of the aerodynamic pattern of the flame have been established. It is shown that the flame can be conventionally divided into several sections over its length in all investigations. The lengths of each of the sections, as well as the form of the fields of axial velocity, temperatures, concentrations of the fuel, oxygen, and carbon and nitrogen oxides, are different and determined by the design features of the burner, the flow rates of the agent, and the compositions of the latter in the burner ducts as well as the configuration of the burner throat and the temperature of the environment. To what degree the burner throat configuration and the techniques for injection of the flue gas at different ambient temperatures influence the formation of nitrogen oxides has been established. It is shown that the supply of the recirculation of flue gas into the fuel injection zone enables a considerable reduction in the formation of nitrogen oxides in the flame combustion products. It has been established that the locations of the zones of intensive fuel burnout and generation of nitrogen oxides do not coincide over the flame length, and the ambient temperature has a significant impact on the combustion stability at low values and on the concentration of nitrogen oxides in the combustion products at high values.     

少油点火油燃烧器雾化及燃烧特性

为研究少油点火油燃烧器的雾化特性,利用Fluent软件构建油枪喷嘴的三维计算模型,模拟计算不同燃油质量流量下的燃油雾化速度,得出喷嘴出口雾化速度不受燃油质量流量影响的结果。为研究少油点火油燃烧器的燃烧特性,建立油燃烧器三维计算模型,对模拟计算得到的油燃烧室温度和速度分布情况进行分析,得出燃油质量流量越大,燃烧温度和速度越高的结果。分析结果表明:油火焰的温度水平能点燃煤粉,且油耗低。     

W型火焰锅炉燃烧系统的设计与优化

陈述了W型火焰锅炉燃烧系统的特点,介绍了美国BW公司的燃料着火指数(IF),3种燃烧器及其适用的制粉系统,比较了燃烧器与磨煤机4种配置下煤粉的着火温度及着火热量,以及北京巴布科克.威尔科克斯有限公司在燃用低反应特性煤质时燃烧系统设计优化措施。     

褐煤和烟煤火焰检测的比较分析

通过对褐煤和烟煤进行理论分析,得出褐煤的着火热比烟煤大,且褐煤的火焰检测初始燃烧区比烟煤远。并对炉膛火焰燃烧情况进行了分析,得出火焰检测装置应安装在炉膛中心火焰旋转的下游、燃烧器水平中心线的上侧的结论。     

煤粉气流在方管点火室着火过程的试验与数值模拟

研究了一种点火室为方管状的感应式无油直接点火燃烧器。热态试验表明,点火室中煤粉气流浓度变化对于煤粉气流而言有正反两方面的影响,即存在一个最佳的煤粉浓度;环流风给着火后的煤粉气流提供充足的氧气,从而强化燃烧。数值模拟表明,弥散到近壁区域的小颗粒煤粉其燃烧产生的反应热是促成煤粉形成稳定火炬的主要能量。     

Organic coal-water fuel: Problems and advances (Review)

The study results of ignition of organic coal-water fuel (OCWF) compositions were considered. The main problems associated with investigation of these processes were identified. Historical perspectives of the development of coal-water composite fuel technologies in Russia and worldwide are presented. The advantages of the OCWF use as a power-plant fuel in comparison with the common coal-water fuels (CWF) were emphasized. The factors (component ratio, grinding degree of solid (coal) component, limiting temperature of oxidizer, properties of liquid and solid components, procedure and time of suspension preparation, etc.) affecting inertia and stability of the ignition processes of suspensions based on the products of coaland oil processing (coals of various types and metamorphism degree, filter cakes, waste motor, transformer, and turbine oils, water-oil emulsions, fuel-oil, etc.) were analyzed. The promising directions for the development of modern notions on the OCWF ignition processes were determined. The main reasons limiting active application of the OCWF in power generation were identified. Characteristics of ignition and combustion of coal-water and organic coal-water slurry fuels were compared. The effect of water in the composite coal fuels on the energy characteristics of their ignition and combustion, as well as ecological features of these processes, were elucidated. The current problems associated with pulverization of composite coal fuels in power plants, as well as the effect of characteristics of the pulverization process on the combustion parameters of fuel, were considered. The problems hindering the development of models of ignition and combustion of OCWF were analyzed. It was established that the main one was the lack of reliable experimental data on the processes of heating, evaporation, ignition, and combustion of OCWF droplets. It was concluded that the use of high-speed video recording systems and low-inertia sensors of temperature and gas concentration could help in providing the lacking experimental information.     

Development of measures to improve technologies of energy recovery from gaseous wastes of oil shale processing

Prospects of the use of oil shale are associated with its thermal processing for the production of liquid fuel, shale oil. Gaseous by-products, such as low-calorie generator gas with a calorific value up to 4.3MJ/m³ or semicoke gas with a calorific value up to 56.57 MJ/m³, are generated depending on the oil shale processing method. The main methods of energy recovery from these gases are either their cofiring with oil shale in power boilers or firing only under gaseous conditions in reconstructed or specially designed for this fuel boilers. The possible use of gaseous products of oil shale processing in gas-turbine or gas-piston units is also considered. Experiments on the cofiring of oil shale gas and its gaseous processing products have been carried out on boilers BKZ-75-39FSl in Kohtla-Järve and on the boiler TP-101 of the Estonian power plant. The test results have shown that, in the case of cofiring, the concentration of sulfur oxides in exhaust gases does not exceed the level of existing values in the case of oil shale firing. The low-temperature corrosion rate does not change as compared to the firing of only oil shale, and, therefore, operation conditions of boiler back-end surfaces do not worsen. When implementing measures to reduce the generation of NO_x, especially of flue gas recirculation, it has been possible to reduce the emissions of nitrogen oxides in the whole boiler. The operation experience of the reconstructed boilers BKZ-75-39FSl after their transfer to the firing of only gaseous products of oil shale processing is summarized. Concentrations of nitrogen and sulfur oxides in the combustion products of semicoke and generator gases are measured. Technical solutions that made it possible to minimize the damage to air heater pipes associated with the low-temperature sulfur corrosion are proposed and implemented. The technological measures for burners of new boilers that made it possible to burn gaseous products of oil shale processing with low emissions of nitrogen oxides are developed.     

Study of flame combustion of off-design binary coal blends in steam boilers

Changes in the structure of the fuel consumption by the thermal power stations of Ukraine caused by failure in supplying anthracite from the Donets Basin are analyzed and the major tasks of maintaining the functioning of the coal industry are formulated. The possibility of using, in the near future, the flame combustion of off-design solid fuels in the power boilers of the thermal power plants and combined heat and power plants is studied. The article presents results of expert tests of the TPP-210A and TP-15 boilers under flame combustion of mixtures of anthracites, lean coal, and the coal from the RSA in various combinations. When combusting, such mixtures have higher values of the combustibles yield and the ash fusibility temperature. The existence of the synergetic effect in the flame combustion of binary coal blends with different degrees of metamorphism is discussed. A number of top-priority measures have been worked out that allow for switching over the boilers designed to be fired with anthracite to using blends of coals of different ranks. Zoned thermal analysis of the TP-15 boiler furnace was performed for numerical investigation of the temperature distribution between the furnace chamber zones and exploration of the possibility of the liquid slag disposal and the temperature conditions for realization of this process. A positive result was achieved by combusting anthracite culm (AC), the coal from the RSA, and their mixtures with lean coal within the entire range of the working loads of the boilers in question. The problems of normalization of the liquid slag flow were also successfully solved without closing the slag notch. The results obtained by balance experiments suggest that the characteristics of the flame combustion of a binary blend, i.e., the temperature conditions in the furnace, the support flame values, and the degree of the fuel burnout, are similar to the characteristics of the flame of the coal with a higher reactive capacity, which proves the existence of the synergetic effect in the processes of cocombustion of coals of various grades.     

气化小油枪燃烧器在300MW机组中的应用

介绍了一种新型的气化小油枪燃烧器的原理、结构和系统组成,并介绍了其在贵溪电厂300MW中速磨直吹式制粉系统煤粉锅炉上的应用情况。重点论述其在锅炉点火启动和低负荷稳燃过程中的投运步骤、注意事项和应用效果。     

等离子燃烧器火焰检验保护探讨

等离子燃烧技术已在燃煤电厂广泛应用,可实现无油点火,但锅炉冷态点火初期,普遍存在火焰检验波动频繁,导致火焰检验保护无法正常投入的问题,产生此问题的原因是现有火焰检验装置与等离子燃烧器的内燃式点火形式不匹配.针对存在的问题,提出了增设火检探头、逻辑优化及稳燃等措施,既保障了锅炉的正常启动,又满足了燃烧过程安全可控的要求,...     

Development of the technology of using mechanically activated microgrinded coals for firing and lighting of coal boilers of acting thermal power stations

A new technology of using the microgrinded coals in power boilers as well as the results of experimental studies and numerical modeling of microgrinding processes, preparing the air-dust mixture, and combustion of mechanically activated coals are presented. Pilot combustion of microgrinded coals on a firing stand with a power of 5 MW using disintegrator mills showed the possibility of reaching the stable autothermal combustion mode for coals with various degrees of metamorphism. Using mathematical modeling, the design solution for a two-step burner, which provides a stable high level of temperatures of the air-dust mixture at the output from the second step as well as makes it possible to minimize the cost for the production of mechanically activated coal, is suggested. These results indicate the possibility to develop burners intended for using mechanically activated coal, involving the replacement of the highly reactive liquid fuel used for firing the combustion chambers.     

1000MW超超临界机组锅炉燃烧器烧损原因分析及防治

介绍了北疆电厂1 000MW超超临界机组锅炉燃烧器烧损情况,从燃烧器配风、煤着火距离、入炉煤质变化、燃烧器结构及材质等方面分析了燃烧器烧损的原因,结合实际提出了防治燃烧器烧损的办法,并提供了各层燃烧器周界风门的开度优化值,供同类型锅炉的燃烧调整及运行优化借鉴。     

我国电站锅炉新型节油点火燃烧技术现状

减少电站锅炉点火及稳燃用油一直是各国电力科技人员关注的焦点,也是我国当今燃煤锅炉燃烧技术的主攻方向。综述了几种主要无油点火燃烧技术和小油枪点火及稳燃技术的原理、技术特点及国内应用现状,并对等离子、高温空气直接点火技术和小油枪点火及稳燃技术进行了经济技术指标比较。同时,提出以开发新型油雾化技术、性能稳定的劣质煤和无烟煤直接点火技术和低NOx节油点火燃烧技术作为今后研究的重点。     

电厂锅炉应用等离子点火的技术经济分析

等离子点火技术的主要特点是锅炉点火、稳燃时不用或少用燃油，通过等离子直接用电弧点燃煤粉。该技术已在全国几十个电厂的锅炉燃烧器改造及新建锅炉机组上成功应用。本文以600MW新建锅炉机组为例，介绍等离子点火的原理和典型应用方案，并对该技术的应用进行技术经济分析。     

新建火电厂取消燃油系统方案论述

随着燃煤锅炉等离子点火技术的成熟,国电东胜热电厂采用先进的等离子点火和稳燃技术,在国内首创基建期间取消燃油系统方案。该电厂属于坑口电厂,煤质稳定,能够满足等离子点火装置对煤质的要求。在点火和稳燃期间,等离子燃烧器具有等离子点火和稳燃功能;在正常运行期间,它又具有主燃烧器功能。冷态启动所需煤粉,通过邻炉来热风制备。取消燃油系统,可以减少设备购置和维护费用,经济效益和社会效益显著。