小型固体火箭发动机尾部点火设计与实验

根据固体火箭发动机点火器设计经验,选用赛璐珞为点火器盒体材料、黑火药为点火药,并以点火压强作为发动机装药可靠点燃的判据。采用头部点火设计经验公式对端面一侧面燃烧、尾部点火的小型固体火箭发动机点火药量进行了初步估算。为获得点火器的点火压强、点火延迟时间等性能参数,设计、加工了模拟发动机尾部点火空间的试验容器,研究了电点火头、电点火管点火方案在不同条件下的试验情况。结果表明,虽然点火药量相同,但两种点火方案的点火压强、点火延迟时间、喷管堵片的打开方式却存在较大差异,基于发动机可靠性、维修性考虑,将电发火管点火方案作为优选方案,并通过发动机点火试验的成功考核。     

循环流化床锅炉点火系统柴油改天然气应用总结

介绍了山东阳煤恒通化工股份有限公司热电厂锅炉点火系统现状,根据外出考察论证情况,提出了锅炉点火系统改造方案;介绍了锅炉点火系统柴油改天然气后的点火试验情况,并提出锅炉天然气点火的安全措施.改造后,锅炉点火系统完全满足环保要求,节能减排效果显著,有效降低锅炉点火费用.     

浅论循环流化床锅炉的点火

对循环流化床锅炉床上点火和床下点火的具体操作要点进行了分析对比,并讨论了点火中需注意的问题,对确保点火安全、提高点火成功率进行了有意义的探讨和总结。     

带延迟点火部件的发射药点火性能试验研究

为了更好地研究发射药的点火性能,在基于密闭爆发器原理的点火性能测试装置基础上增加了一个延迟点火部件,构建了一个新型点火性能模拟试验装置,根据该装置建立了简单的火药分层点火过程模型,模拟并对比了高能太根-18/1、双芳-3-18/1及NR11-18/1三种发射药的点火性能。结果表明,NR11-18/1发射药较易点火,双芳-3-18/1发射药最难点火,点火时间分别为19和45ms。增加延迟点火部件后,可将点火药的燃烧和发射药的燃烧阶段有效区分,不仅有利于对比点火性能差异较小的发射药之间的区别,还有助于分析发射药低压段的燃烧速度。随着延迟点火部件长度的增加,点火时间也增长。     

固体推进剂点火准则研究进展

为了建立通用的固体推进剂点火准则,分别从实验和模拟两个角度总结了近年来国内外固体推进剂的点火准则。实验层面的点火准则包含判定固体推进剂点火的发火/不发火判据、压力判据、温度判据、光谱辐射强度判据、多参数协同点火判据等。对比分析表明,点火准则均受实验条件以及测试设备的限制,且存在温度等关键点火参数测试难度较大、测试参数延迟等缺陷,因此很难进行拓展应用,但多参数协同的点火判据具有更高的准确性和更大的推广可能性。模拟层面则主要是基于固相、气相、异相点火理论建立的温度点火准则、压力点火准则和化学信号点火准则3类。相较于实验点火准则而言,模拟点火准则更符合固体推进剂的点火理论,但需要从实验获得点火温度、动力学数据等关键参数作为模型输入,且不同种类推进剂的点火理论不尽相同,因此该类点火准则仍需进一步研究。此外,对实验、模拟点火准则进行了关联性和通用性讨论。附参考文献49篇。     

盐酸合成炉自动点火控制方案的技术研发

介绍了盐酸合成炉自动点火系统的组成,分析了自动点火系统点火阶段的控制程序,并结合自动点火系统的特点,阐述了DCS联锁控制系统的设计思路。     

沸腾炉木炭点火

为了坚决贯彻毛主席“备战、备荒、为人民”的伟大战略方针,破除喷柴油点火的陈规,节约用油,东莞化肥厂创造了木炭点火的经验,肇庆化肥厂在学习、运用东莞化肥厂的经验后,也摸出了一套较完整的经验。 木炭点火大大减轻了工人的劳动强度,缩短了点火时间(东莞喷柴油点火需1小时30分钟左右,用木炭点火仅需30分钟;肇庆用柴油点火需35—45分钟,用木炭点火10—15分钟即     

瞬态点火装置及其测试系统的设计

为了研究火炸药在外界点火作用下的点火感度和评价火炸药的使用安全性,设计了一套基于高压放电的瞬态点火装置和基于示波器DPO4054的点火能量测试系统.通过燃料空气炸药的点火试验,测得50%的点火能量为2.443J.为精确测试样品的点火能量提供了一种新途径.     

火炮同步点火管的燃烧实验和数值模拟

为增加火炮点火的同步性，对一种爆轰波传火的火炮同步点火管进行了燃烧实验，测量了点火管不同位置的压力一时间曲线。在考虑火药燃烧过程中同步点火特征、气体湍流和新增燃气质量流流入的基础上，建立了点火管内的燃烧计算模型，用CFD软件对点火管的燃烧过程进行了三维数值模拟计算，并将计算得到的压力一时间曲线与实验曲线进行对比分析。结果表明，点火管具有很高的点火同步性，模拟计算的压力一时间曲线与实验结果基本吻合。     

焦载热褐煤气化试验装置点火试验研究

介绍了褐煤温和气化及热半焦连续高温气化工艺流程及其扩大试验装置，着重研究了该装置的燃烧点火设备和点火过程．根据点火试验升温曲线，将点火过程分为加热、着火和燃烧３个阶段并作了讨论，最后对点火试验本身进行了评述．     

Effect of fuel properties on biomass combustion: Part I. Experiments—fuel type,equivalence ratio and particle size

Moving bed combustion is commonly used for energy conversion of biomass. Conditions on the moving bed can be conveniently represented by a time dependent fixed bed. The present work experimentally investigates the combustion of four biomass materials having different fuel properties in a fixed bed under fuel-rich conditions. Temperature, gas composition and mass loss curves identified two distinct periods as the combustion progresses in the bed: the ignition propagation and char oxidation. The effects of bulk density, particle size and air flow rate on the combustion characteristics during the two periods are interpreted by using the ignition front speed, burning rate, percentage of mass loss, equivalence ratio and temperature gradient. Different channelling of air was observed for small miscanthus pellets and large wood particles due to the fast propagation of the ignition front around a channel. The elemental ash composition was also analysed, which explained the sintered agglomerates of miscanthus ashes in terms of alkali index.     

The ignition temperature of lignite char in a fluidized bed combustor

This paper summarises the experimental and modelling work carried out for the variation of bed ignition temperature of a fluidized bed combustor with the char particle diameter and the fluidizing velocity. A lignite char was used and its reactivity was represented using data from Field (1967) and Turnbull and Davidson (1984). The modelling involved solving the steady state heat balance around the fluidized bed combustor at the ignition temperature. A correlation of the total area of char ignited per unit bed mass was determined as a function of the char particle diameter and the fluidizing velocity. This correlation was used to determine the ignition temperature of the fluidized bed combustor operating at different conditions. The fluidized bed combustor heat balance was then solved for the bed ignition temperature which was influenced by both the rate of heat loss from the bed and the reactivity of the char. A sensitivity analysis suggests that the chemical rate reaction coefficient is the most prominent variable when determining the ignition temperature of a fluidized bed combustor.     

油贡岩在流化床锅炉内着火和燃烧特性的试验研究

介绍了在自行设计的电加热流化床小型试验台上进行的桦甸油页岩着火、燃烧特性的试验结果,研究了床层温度、燃料粒径对桦甸油页着火指数的影响,并结合油页岩的元素分析、工业分析结果对实验结果进行分析。研究结果对燃用油页岩流化床锅炉的设计、优化流化床锅炉的启停和运行具有一定的参考价值。     

Experimental study of ignition and extinction waves and oscillatory behavior of a tubular nonadiabatic fixed bed reactor for the oxidation of carbon monoxide

An experimental study of axial temperature profiles in a nonadiabatic tubular fixed bed reactor has been made under the transient operation. The catalytic carbon monoxide oxidation occurring on a Pt/alumina catalyst has been used. Ignition and extinction waves have been studied both in a short and a long catalyst bed. It is shown that in a short bed ignition and extinction occur at the reactor outlet while for a long bed the ignition and extinction process takes place inside the reactor and is not influenced by the outlet part of the reactor. A systematic measurement indicates that in a narrow range of inlet parameters the integral nonadiabatic nonisothermal reactor may operate in an oscillatory state. These oscillations can be periodic or aperiodic.     

Study of coal and coke ignition in fluidized beds

Ignition tests were conducted with delayed and fluid petroleum cokes, a high volatile bituminous coal and their blends in bench- and pilot-scale fluidized bed combustors. In the bench-scale FBC tests, a visual inspection ignition criterion was developed based on the ‘CO–CO₂’ profiles obtained as a function of time and bed temperature. In the pilot-scale unit, the rapid increase in SO₂ levels was used as the indicator of fuel ignition. In addition to the fluidized bed ignition tests, thermogravimetric analysis (TGA) measurements were made on all fuels and their chars. The results showed that, while the fluid coke (which has the lowest volatile content) was the most difficult to ignite, ignition was not a simple function of volatile content. Further, different test methods and ignition criteria demonstrated significantly different ignition temperatures, with the largest variation arising between bench- and pilot-scale equipment. Finally, tests on mixtures of petroleum coke and coal showed that there was no interaction between these two fuels, and that the coke ignited only when it achieved its own ignition temperature.     

Spontaneous ignition of wood, char and RDF in a lab scale packed bed

Many municipal waste combustors use preheated primary air in the first zone to dry the waste. In most cases the preheat temperature does not exceed 140 °C. In previous experiments it is found that at temperatures around 200 °C, in some circumstances, self- or spontaneous ignition can be achieved. Using preheated air can be a powerful tool to control the ignition and combustion processes in a waste combustion plant. To use this tool effectively, the influence of the preheated air on the fuel bed needs to be well understood. The present work is done to investigate in a systematically way the spontaneous ignition behaviour of a packed bed heated with a preheated air stream. Experiments on a lab scale packed bed reactor are carried out for various fuel types. Because MSW is an highly inhomogeneous fuel, wood and char are used as model fuels. To include the inhomogeneous character of MWS, also experiments are carried out with RDF. Parameters such as primary air flow velocity and temperature, addition of inert material, moisture content of the fuel (wood chips) and particle size (char) have been changed to see their effect on the spontaneous ignition temperature and on the minimum air temperature needed for ignition. The spontaneous ignition temperature is defined as the bed temperature at which a transition takes place from a negligible or slow fuel reaction rate to a rapid oxidation of either the volatiles or the solid fuel without an external source such as a spark or a flame. The minimum or critical air temperature is defined as the lowest air temperature at which ignition can be obtained. It is found that the type of fuel has influence on the ignition temperatures. Besides both the critical air temperature needed for the spontaneous ignition and the spontaneous ignition temperature increase with an increase in the primary air velocity (between 0.1 and 0.5  m/s) and increasing the added inert fraction (between 0 and 40 wt%), irrespective of the fuel type. The effect of air flow velocity and temperature and also the effect of inert on both the critical air temperature and the spontaneous ignition temperature can be explained qualitatively by using Semenov’s analysis of thermal explosions. Semenov’s theory is quantitatively applied to predict the spontaneous ignition and the critical air temperatures for wood.     

Further studies of the spontaneous ignition behaviour of activated carbon

A laboratory scale study has been made of the spontaneous ignition behaviour of activated carbon, type 207B, + 1.5% KI, which is used exclusively in the gas filters of UK nuclear power plant. The effects of bed depth, velocity and direction of air flow, and lube oil contamination have been investigated, together with inert gas preheating of the bed. Preheating in nitrogen or carbon dioxide results in a marked lowering of spontaneous ignition temperature (SIT), as does the presence of lube oil at concentration levels above about 1 % by weight. Increasing the bed depth produces only a modest decrease in SIT; reversal of the air flow has no effect. Air velocities below 4 m min^?1 significantly increase SIT. An hypothesis based on the role played by active sites is presented to account for the phenomena observed. It is concluded that the influence of lube oil on ignition is exerted mainly through a hydrocarbon gas-phase reaction.     

Bedding ignition,vertical flame spread and subsequent thermal impact on underlying mattress

The ignition of bedding and subsequent vertical spread of fire along the side of a noncombustible surrogate bed set was investigated. One‐hundred‐eight (108) tests were conducted to assess the ignition timeline and subsequent vertical flame spread of bedding up the side of a bed along with the thermal impact of the bedding fire on the underlying bed set. The ignition source for all tests was comprised of the flame from a book of matches placed on bedding at floor level at the base of the bed. The bedding consisted of combinations of a cotton/polyester blend sheet and bedspread. Ignition occurred in 3 to 10 seconds for the majority of the test. The speed of subsequent vertical flame spread, assessed through video frame analysis tools, was dependent on the exposed bedding material with an exposed sheet exhibiting faster spread. Thermal exposure from the burning bedding to the vertical sides of the bed set was assessed with an array of thermocouples embedded at the surface of the sides of the underlying bed set. The time to thermal exposure was found to be a function of the vertical flame spread and thickness of the bedding material(s).     

流化床内煤着火特性实验研究

为了对当前大量应用的带有床下启动燃烧器 CFB锅炉的启动运行提供指导 ,以及为从事循环流化床技术和煤燃烧理论研究提供参考 ,在电加热的小型流化床燃烧系统上 ,采用热烟气炉下点火的方式来研究煤粒在流化床内的燃烧特性 .测定了福建龙岩无烟煤的着火特性 ,分析了粒径、床温对着火点的影响 .并提出了煤颗粒在流化床内着火点测定的实验规范 .     

Determination of reactivity and ignition behaviour of solid fuels based on combustion experiments under static and continuous flow conditions

The reactivity and ignition behaviour of solid fuels is a major parameter for combustion and gasification processes, but also for a safe transport and storage of pyrophoric solids. In this work, seven non-isothermal methods were compared with respect to characterise the ignition behaviour as well as to calculate kinetic parameters; for comparison also ‘classical’ isothermal measurements were done. Different methods and reactors (fixed and fluidised bed, thermogravimetry, oven heating tests) were used and tested under static and continuous flow conditions, taking charcoal, activated carbon and blast furnace coke as model solid fuels. The accuracy of all tested methods to determine kinetic data is reliable within a range of confidence of about ±50 K (with respect to the temperature needed to reach a certain level of reactivity). For a fast and relative simple determination of kinetic data, the ignition test in a small lab-scale fixed bed reactor can be recommended. Additional calculations show that the critical parameters with respect to ignition during transport and storage can also be calculated quite accurately based on this method, i.e. no elaborated basket heating tests are needed.