基于多尺度相关和机理建模的炉膛压力分析

借鉴小波分析思想，设计了简单滤波器组，将信号分解为不同频率尺度的分量，对不同信号的各个分量之间进行相关分析，比较不同频率尺度下频率分量间的相关性特征，从而大致判断出信号间的影响关系及类型．利用多尺度频率相关分析方法对电站锅炉炉膛压力等信号进行分析，发现炉膛压力低、中频段分量分别与燃料量、送风量的中、高频段分量呈现出明显的正相关性．建立了燃料量、送风量和引风量与炉膛温度和压力间的简化动态模型，并进行机理分析．结果表明：炉膛压力信号与锅炉燃烧率之间具有带通滤波特性，炉膛压力能够在较宽的负荷范围和频带内反映锅炉燃烧强度的变化．     

燃烧扰动下炉膛压力的特性分析

采用机理分析和数据分析的方法,建立了炉膛压力与锅炉燃料量、送风量和引风量之间的非线性动态数学模型.在不同锅炉负荷下,对模型进行了线性化处理,得到燃料量对炉膛压力的传递函数,并对其进行了频域特性分析.结果表明:在燃料量扰动下,炉膛压力对象的频率特性在不同负荷下均呈现带通滤波特性,且燃烧扰动的主要频率分布在其通带内,控制系统本身难以直接对燃烧扰动进行有效抑制;在低负荷工况下,炉膛压力波动增大是由于对象自身的非线性特性造成的.     

锅炉运行应注重引风机电流值的变化

在锅炉运行中,引风机电流值的变化有什么规律?临控引风机电流有什么意义?许多锅炉房作业人员不甚了解,一些专业书里介绍也不够,本文就此作一阐述。 一般工业锅炉都是采取微负压机械通风方式。以火床标高划分界面,火床以前的风道阻力由送风机压头来克服,火床以后的炉膛和烟道阻力由引风机和烟囱的抽力来克服。为了维持炉膛微负压,不致炉门正压喷火,送风量须与引风量相匹配。送风机风门开度不但取决于燃烧工     

基于风粉在线监测锅炉燃烧优化控制

在经过对一次风在线监测作了深入地研究后,在此基础上提出了锅炉燃烧优化控制的方案,即按照进入炉膛燃烧的燃料对其所需的空气量进行合理地配风和引风,从而在保证炉膛负压稳定的状况下实现锅炉优化燃烧,达到保证锅炉安全,提高锅炉效率的目的。     

燃煤热水锅炉监控系统的设计

该控制系统按控制功能分两大部分：一是锅炉燃烧系统的监测与控制；二是远程用户温度采集系统。控制中心则依据实测环境温度的变化（考虑风天的影响）和用户室内实测温度综合规划热源管理和控制运行。锅炉自控系统包括了锅炉变负荷运行、安全运行、监控管理、锅炉节能燃烧自控和热网自动调节的全部内容。该系统对锅炉的各项参数（供热量、压力、温度、流量、炉膛温度、排烟温度等）实时监测监视。对给煤量、送风量和炉膛负压进行优化控制管理。针对华北油田3台7MW链条燃煤热水锅炉特点，     

锅炉通风及其控制

在锅炉运行中,最重要而又为人误解的概念之一是炉膛的通风。无论是燃用天然气、油或者煤,要实现正常燃烧的目的,必须维持合适的锅炉炉膛通风。通风这个术语,简单地讲是一种指标,它表示烟气(燃烧产物)排出锅炉的速度相对于燃烧空气和燃料输入锅炉速度的大小。如果烟气的排出速度高于燃料及空气的输入速度,则锅炉炉膛内的压力便低于大气压力。在这种情况下,炉膛内将出现负压通风。     

锅炉蒸汽压力模糊控制器的设计

锅炉燃烧过程是一个具有强干扰的非线性、时变的多变量过程,各个通道时延不同.由于锅炉燃烧过程存在比较紧密的祸合关系,给被控变量和操作变量的配对带来一定难度.一般是将燃烧系统分解成几个相对独立的调节对象,较少考虑耦合,相应设置独立的调节回路,主要控制回路有蒸汽压力控制回路、空燃比控制回路、炉膛负压控制回路,由于蒸汽压力控制...     

炉膛负压异常波动变正压的故障分析与处理

炉膛负压是反映燃烧工况稳定与否的重要参数,是运行中要控制和监视的重要参数之一。炉内燃烧工况一旦发生变化,炉膛负压随即发生相应变化。当锅炉的燃烧系统发生故障或异常时,最先将在炉膛负压上反映出来,而后才是火检、火焰等的变化,其次才是蒸汽参数的变化。因此,监视和控制炉膛负压对于保证炉内燃烧工况的稳定、分析炉内燃烧工况、烟道运行工况、分析某些故障、事故的原因均有极其重要的意义。大多数锅炉采用平衡通风方式,     

降低锅炉飞灰、灰渣含碳量的技术应用

提高二次风与炉膛差压,调整燃烧器上部二次风量,采用">"型燃烧技术,采用"对冲"型燃烧技术,有利于保证锅炉燃烧稳定,使煤粉燃烧充分,进而降低锅炉飞灰、灰渣含碳量,提高锅炉效率。     

某中温次高压垃圾焚烧炉结焦原因及对策分析

生活垃圾作为垃圾焚烧炉的燃料,其品质直接影响炉膛温度、配风量等锅炉燃烧工况的调整操作,易造成烟气携带的熔融灰分粘附在炉膛受热面形成结焦,炉内结焦影响锅炉安全、环保、经济、稳定运行。在对某生活垃圾焚烧发电厂中温次高压垃圾焚烧机械炉排炉结焦原因分析的基础上,提出提高燃料品质、控制炉膛温度、合理配风量、及时清灰打焦和加强运行管理等应对措施,有效改善炉膛结焦问题,提高机组运行效率。     

双燃料发动机的燃烧模型

针对双燃料发动机燃烧特性，建立了柴油喷雾扩散燃烧子模型和气体燃烧均质混合气火焰传播燃烧子模型，应用该模型研究了双燃料发动机燃烧机理，计算结果和实验结果相当吻合。计算表明：当引燃柴油比例较大时，双燃料发动机燃烧过程以喷雾混合控制燃烧为主，柴油喷雾扩散燃烧模型与实测较吻合；当柴油比例较小时，该过程以均质混合气火焰传播燃烧为主，均质混合气火焰传播燃烧模型与实测软吻合。计算结果表明，引燃柴油量对双燃料发动机性能影响较大，引燃柴油减少，着火滞燃期延长，缸内最大爆发压力升高。     

用光学纹影摄影术观察分析定容燃烧室内氢燃料的燃烧过程

论述了采用纹影摄影术和高速摄影法观察分析氢气和空气预混合燃料在定容燃烧室内的火花点火燃烧过程,定性地分析了预混合氢气燃料的火焰形态和变化过程,以及燃烧室内的初始压力和空燃比对火焰传播速度及其燃烧压力的影响,通过采用纹影摄影术方法,初步揭示了预混合氢气燃料在定容燃烧室内燃烧时火焰初期紊流产生的机理,以及由开始的层流状火焰发展到湍流状火焰的过程,研究结果表明,预混合氢气燃料燃烧的火焰传播速度及燃烧压力明显地受燃烧室内的初始压力和空燃比的影响。     

200‐MW chemical looping combustion based thermal power plant for clean power generation

The present study demonstrates a possible configuration of a 200 MW chemical looping combustion (CLC) system with methane (CH₄) as fuel. Iron oxide‐based oxygen carriers were used because of its non‐toxic nature, low‐cost, and wide availability. We analyzed the effects of different variables on the design of the system. For the air reactor (oxidizer), bed mass is independent, and for the fuel reactor (reducer), it decreases with increase in the conversion difference between the air and fuel reactors. On the other hand, the pressure drop in the air reactor is unchanged, whereas for the fuel reactor, it decreases with the same increase of conversion difference between air and fuel reactors. Also, entrained solid mass flow rate from the air to fuel reactor shows a decreasing trend. Bed mass, bed height, pressure drop, and residence time of the bed materials decrease with increase in the conversion rates in the air and fuel reactors. Residence time of bed material in the air and fuel reactor reduces with increase in the temperature of the air reactor. Copyright © 2011 John Wiley & Sons, Ltd.     

启喷压力对直喷式柴油机燃烧的影响

作者介绍了启喷压力对采用低惯量喷油器的直喷式柴油机性能影响的研究结果。通过采用激光全息和高速摄影等技术对燃油喷雾与气缸内燃烧过程的观察与分析，揭示启喷压力与燃油喷雾，混合气形成，扩散燃烧间的重要关系。根据研究结果，提出了直喷式柴油机采用低惯量喷油器启喷压力的一般方法。     

Experimental investigation on the effect of intake air temperature and air–fuel ratio on cycle-to-cycle variations of HCCI combustion and performance parameters

Combustion in HCCI engines is a controlled auto ignition of well-mixed fuel, air and residual gas. Since onset of HCCI combustion depends on the auto ignition of fuel/air mixture, there is no direct control on the start of combustion process. Therefore, HCCI combustion becomes unstable rather easily, especially at lower and higher engine loads. In this study, cycle-to-cycle variations of a HCCI combustion engine fuelled with ethanol were investigated on a modified two-cylinder engine. Port injection technique is used for preparing homogeneous charge for HCCI combustion. The experiments were conducted at varying intake air temperatures and air–fuel ratios at constant engine speed of 1500 rpm and P-θ diagram of 100 consecutive combustion cycles for each test conditions at steady state operation were recorded. Consequently, cycle-to-cycle variations of the main combustion parameters and performance parameters were analyzed. To evaluate the cycle-to-cycle variations of HCCI combustion parameters, coefficient of variation (COV) of every parameter were calculated for every engine operating condition. The critical optimum parameters that can be used to define HCCI operating ranges are ‘maximum rate of pressure rise’ and ‘COV of indicated mean effective pressure (IMEP)’.     

进气温度和过量空气系数对乙醇均质压燃燃烧过程的影响

在一台经过改进的CA6110发动机上,进行了进气温度和过量空气系数对乙醇燃料均质压燃燃烧过程影响的试验研究．结果表明,在转速和供油量一定时,随着进气温度的升高,着火始点提前,燃烧持续期变短,压力升高率变大,缸内的最大燃烧压力变大,指示效率提高,平均指示压力升高．当进气温度一定时,随着过量空气系数的减小,着火始点提前,燃烧持续期逐渐变短,压力升高率变大,缸内的最大燃烧压力变大,指示效率增加．     

Parametric study on combustion characteristics of virtual HCCI engine fueled with methane–hydrogen blends under low load conditions

Homogeneous charge compression ignition (HCCI) is an alternative combustion strategy employed for automotive systems. It has a higher thermal efficiency with lower nitric oxides and particulate matter emissions that are below current emission requirements. However, owing to difficulties associated with combustion control, HCCI engines have disadvantages in terms of combustion instability, such as low-speed-low-load or high-speed-high-load conditions.This study investigates the effects of different parameters on HCCI engine combustion using numerical methods. The parametric study is carried out at low loads (25% part load), and a reference intake temperature of 550 K is used to preheat the air–fuel mixture. The GRI-3.0 chemical reaction mechanism involving 53 species and 325 reactions is used for 1-D simulations describing the combustion process fueled with methane and hydrogen added methane. By changing the variables, including compression ratio, excess air ratio, and hydrogen content, the combustion behavior is investigated and discussed. The results show that an increase in compression ratio resulted in a faster start of combustion and caused higher in cylinder pressure and heat-release rate. When the excess air ratio was increased, the start of combustion was delayed and lower in-cylinder pressure and heat release rate were observed. The results were similar for varying compression ratios.     

直喷式柴油机气缸内喷雾贯穿及分布的研究

本文建立了燃油喷过程及气缸内喷雾特性的统一计算模型。考虑了燃油喷射、气缸内空气运动和燃烧室结构对喷雾贯穿及分布的影响。     

Fuel atomization in gas turbines: A review of novel technology

The atomization of fuel is crucial in the combustion and emission of a gas turbine, and the fuel atomization is continuous without any cycles or strokes. However, to achieve a desired amount of combustion during this continuous process, fuel must be added and mixed with the high‐pressure air exiting the compressor in proper proportions. To make the engine as small and lightweight as possible is a constraint and requires the fuel injection, mixing, and combustion to occur within the smallest volume possible. In most cases, this is inefficient and less practicable. A major drawback is the requirement of high injection pressure with relatively small increase in flow rate. In recent years, research was conducted to improve fuel atomization in a gas turbine by using different novel approaches that were simpler, more adaptable, and efficient to enhance the atomization. However, most of these studies were in isolation without any comprehensive literature on recent trends. Therefore, this review attempts to give an insight on recent development of fuel atomization in a gas turbine. Particular emphasis was given to air‐, plasma‐, ultrasound‐, and supercritical fluid–assisted atomization techniques.     

Shock tube studies on ignition delay and combustion characteristics of oxygenated fuels under high temperature

A comparative study on ignition delay time and combustion characteristics of four typical oxygenated fuel/air mixtures of dimethyl ether (DME), diethyl ether (DEE), ethanol and E92 ethanol gasoline was conducted through the chemical shock tube. The fuel/air mixtures were measured under the ignition temperature of 1100 to 1800 K, initial pressure of 0.3 MPa and the equivalence ratios of 0.5, 1.0 and 1.5. The experimental results show that the ignition delay time of these four oxygenated fuels satisfies the Arrhenius relation. The reaction H + O₂ = OH + O has a high sensitivity in four fuel/air mixtures during high-temperature ignition, which makes the ignition delay lengthen with the increase of the equivalence ratios. By comparing the ignition delay of four fuels, ether fuels have excellent ignition performance and ether functional group has better ignition promotion than hydroxyl group. Moreover, the carbon chain length also significantly promotes the ignition. Due to the accumulation of a large number of active intermediates and free radicals during the long ignition delay time before ignition, the four fuels all have intense deflagration and generate the highest combustion peak pressure at the relatively low ignition temperature (1150-1300 K). For DME, DEE and ethanol, due to the high content of oxygen in their molecules, the combustion peak pressure and luminous intensity increased with the equivalence ratio, and the combustion is intense after ignition. E92 ethanol gasoline with low oxygen content has a lower combustion peak pressure and a longer combustion duration than the other three fuels, and its highest combustion peak pressure appears in the stoichiometric ratio. The combustion process of E92 ethanol gasoline is more oxygen-dependent than the other three fuels.