燃气互换性与火焰稳定性研究

随着燃气品种增多，品质变化，燃气互换性和火焰稳定性成为燃气燃烧理论与技术中极有意义的课题。本文从火焰稳定、热负荷、排烟量３个方面来研究适合于锅炉动力及工业加热类的气互换性；推荐了ＢＦＧ＋ＣＯＧ置换ＣＯＧ的互换准则。     

多孔介质往复流动燃烧的一维数值模拟

建立了往复流动多孔介质燃烧器的一维数学模型：在该系统中，可燃预混气周期性换向，分别从两端流入燃烧器。假定气相与固相处于局部热平衡状态，考虑了辐射换热的影响。采用有限容积法求解，通过大量数值计算研究了主要工况参数，如半周期、流速、当量比、热损失、多孔介质衰减系数及其热容对该燃烧系统温度分布和反应特性的影响。计算结果与实验结果在定性上吻合良好。     

两段燃烧流化床锅炉的设计方法

一种新型两段燃烧流化床锅炉，能实现燃气、蒸汽联产和减少有害气体的大气的排放，特别适合于中小企业和经济发达的乡镇燃气化和集中供热，文中介绍了两段燃烧系统的运行原理和设计要求以及气化段的热力计算方法，建立了预测燃气成份的气化平衡模型。并进行了计算，计算结果与工业测试数据进行了比较，两者符合较好，根据计算结果与工业测试数据进行了比较，两者符合较好。根据计算结果和理论分析。提出了合理组织两段燃烧的有效措施。     

Pollutant emissions,performance and combustion behaviour assessment of an Si gas engine fuelled with Lcv gas containing carbon monoxide and hydrogen diluted by nitrogen

This paper includes the experimental test data of an SI engine fuelled with simulated LCV gas (Low Calorific Value), which resembles synthesis gas in composition. The LCV gas was simulated by a mixture of carbon monoxide, hydrogen and nitrogen. During the experiment, the lower heating value of the LCV gas was altered by dilution with nitrogen. A single-cylinder Honda GX270 engine was adopted in the experiment to assess the impact of LCV gas on the system performance. This engine is typically used to power various machines and for electrical energy production in small generator sets. A modified engine was connected to an electric generator, which was loaded with an electric resistor. Engine operation was controlled using a microprocessor controller. All tests were performed at constant engine speed (3000 rpm). The engine was working at wide-open throttle for all mixtures. All mixtures were burned at stoichiometric conditions and with fixed value of ignition timing (30 deg bTDC). The indicated performance of the SI engine was evaluated based on the in-cylinder pressure measurements. No significant impact on the main internal parameters of the tested SI engine fuelled with simulated LCV gas diluted by nitrogen was observed. The experimental tests showed that the combustion duration increased for the mixtures with higher content of inert gas. Increase in the LHV raised the specific emissions of NO_x and decreased specific emissions of CO and HC.     

柴油机喷雾混合的场效应分析方法研究

柴油机燃烧系统的设计及匹配一直是柴油机研究的重点.提出了一种新的柴油机燃烧系统场效应分析方法,针对喷雾混合过程进行微观及宏观仿真分析研究.场效应分析方法从燃油浓度场和速度场对混合过程的影响规律入手,将这两个场量对传质的作用通过场效应角进行量化,从而对燃烧系统的优劣进行定量的评价,指导燃烧系统的设计或优化匹配.以喷雾锥角的匹配为例应用场效应分析方法进行了仿真研究,并在单缸机上进行了试验验证,证明了场效应分析方法的有效性和实用性.     

基于遗传算法的燃煤电站锅炉整体燃烧优化方法研究

针对电站锅炉燃烧效率和污染物的排放，提出了一种整体燃烧优化的思想，并结合遗传算法和人工神经网络技术，对整体燃烧优化方法进行了研究。仿真结果表明，采用本文提出的燃烧优化控制方案，不仅能使锅炉节能，还能降低排放的烟气中氮氧化物的含量，减少对环境的污染，具有较强的可行性。     

Industrial scale modelling of the thermochemical energy storage system based on CO2 + 2NH3 ↔ NH2COONH4 equilibrium

The thermochemical storage of energy by the system carbon dioxide, ammonia and ammonium carbamate is studied in detail. In particular, the kinetics and the thermodynamics of the reversible reaction is studied. We give two industrial models for the operation of this system. In the first, the separation of the gases NH₃ and CO₂ is achieved by compression and liquefaction of NH₃. In the second, a method of separation of the gases is proposed which is based on the solubility of NH₃ in ethanol while CO₂ is practically insoluble. The operation of this system is examined both in closed form and in the case in which CO₂ is rejected in the atmosphere, and it is taken from alcoholic fermentation or from the combustion gases of power plants burning lignite. The mass and energy balance is given, for each case, and the amount of energy losses by the use of this storage system is calculated. Finally, we give some estimates for the area of solar collectors and the amount of chemicals which are required in order to cover the energy needs of a community.     

Experimental investigation on the kinetics of biomass combustion in vertical tube reactor

The paper presents results of experimental investigation performed in order to examine kinetics of loose biomass combustion in vertical tube reactor. The investigation conducted included continuous measurement of the fuel mass loss rate, with two biomass combustion models (piston and batch model) proposed, each relying on appropriate theoretical postulates. Results obtained indicated that piston combustion model had shown better agreement between theoretical and experimental data and was therefore used to further analyse effects of excess-air on the combustion kinetics, as well as associated effects of flue gas recirculation. Recirculation of cold flue gases is used to lower peak temperature inside the furnace, as well as to reduce a zone where ash melting problems may potentially occur. During the investigation performed, effects of flue gas recirculation on the combustion process were simulated by simultaneously injecting nitrogen and air flows into the furnace. This was deemed appropriate to simulate real-life conditions prevailing in the furnace with gas recirculation. Experiments were conducted on specially designed and constructed apparatus that enabled kinetic parameters to be determined for the combustion of different types of biomass. Results obtained have indicated that quantity of air affects kinetics of biomass combustion and that increased recirculation leads to reduced biomass reaction rate. The same conclusion was reached based on the results of experiments conducted with two different types of agro-biomass, namely wheat straw and corn stalks, which are most commonly used for energy generation. Results achieved are deemed particularly important when it comes to design of new plants that utilize cigarette type combustion system, but also for development of numerical models used to simulate combustion of biomass bales, with special emphasis placed on the impact of recirculation gases on the combustion kinetics.     

A regenerative multiple zone model for HCCI combustion

A new conserved scalar approach, the so-called regenerative multiple zone (RMZ) model, is introduced to simulate combustion in homogeneous charge compression ignition (HCCI) engines with significant products of combustion. In this approach, two conserved scalars are introduced, the mixture fraction Z and the initial exhaust gas fraction J, to determine uniquely the state of the reactive system as a function of the two conserved scalars and time. For the numerical solution of the HCCI combustion, the conserved scalar plane is divided into different zones, which represent homogeneous reactors with constant initial exhaust gas level. Particularly, the zones are created based on the distribution of the initial exhaust gases and are mixed and regenerated at every time step during combustion in order to account for the history effects which are due to the finite rate chemistry. A proper methodology to create and initialize the new zones during the combustion, the so-called zone creation strategy (ZCS), is also proposed. For validation, the RMZ model is implemented in the 2DRD code, which is a computational fluid dynamics code that solves the governing equations for a two-dimensional reaction-diffusion problem. Initially, the consistency of the new model is validated in a one-dimensional reaction-diffusion (RD) case. Subsequently, the necessity for a proper zone creation strategy is demonstrated by a two-dimensional RD case. Next, a parametric study is performed to investigate the sensitivity of the new model on the maximum number of zones that is used. Finally, the limitations as well as the advantages of the RMZ model are discussed.     

电站锅炉神经网络燃烧诊断系统应用研究

先进的燃烧诊断技术可以有效地提高电站锅炉运行的经济性和安全性，本文通过对炉膛火焰的图像采集，利用计算机数字图像处理技术及人工神经网络模型分析方法，开发了永安电厂5号炉的火焰图像燃烧诊断系统。该系统为运行人员提供了有意义的定量化特征参数，并对燃烧状况辩识的机理进行了富有成效的探索，为电站锅炉的燃烧诊断和优化控制提供新方法和新途径。     

基于新型测温技术的电站锅炉燃烧优化

为了提高锅炉效率,减少污染物排放,电站锅炉需要进行燃烧优化。以新型测温技术为基础,提出一种包含炉内温度场测量结果的燃烧优化模型,采用模拟退火算法作为燃烧优化控制算法进行优化。以某电厂300 MW锅炉为研究对象,采用仿真的方法对燃烧优化控制算法进行研究,通过对锅炉运行参数受到扰动时的工况进行燃烧优化,验证了模拟退火算法的优化性能。结果表明:在锅炉运行参数受到扰动时,模拟退火算法作为优化算法,能够给出有效的燃烧调整指令,解决扰动产生的问题,使炉膛燃烧状态保持设定的优化状态。     

Calculation of premixed combustion within inert porous media with model parametric uncertainty quantification

The present study focuses on uncertainties existing in porous media parameters and in the inlet reactant mixture conditions of solid oxide fuel cell off-gas combustion. Propagation of uncertainty from the model input parameters to the output stochastic variables is quantified using a non-intrusive spectral projection method based on polynomial chaos expansion. The non-intrusive nature of this method allows the solution of the stochastic problem to be obtained directly from the deterministic model without requiring modification of the governing equations. Quantification of uncertainty is investigated in a one-dimensional model for premixed combustion within inert porous media. The model includes detailed chemistry and solves the gas- and solid-phase energy balances coupled by convective heat exchange, including radiative heat transfer in the solid-phase. The results denote that the uncertainties in the porous media heat transfer parameters are relevant and originate a relatively high error bar on the CO emission and burning velocity. When the inlet reactant mixture uncertain conditions is also accounted for, it overcomes the influence of the other uncertain parameters on the gas- and solid-phase temperatures error bar. Both types of parametric uncertainty sources (inlet conditions and porous media parameters) are important in order to establish the error bar on the CO emission and burning velocity predictions.     

Research on optimizing control model of hydrogen fueled engines based on thermodynamics and state space analysis method about nonlinear system

With its obvious advantages, hydrogen is expected to be greatly used as a new energy, which can reduce vehicle emissions effectively and efficiently. Besides, it can be adopted as an alternative fuel for petroleum fuel of internal combustion engine. However, due to its unique physical and chemical characteristics, hydrogen often leads to abnormal combustion and decay of power, which can be effectively dealt with by optimal control. In this paper, thermodynamic analysis methods, like mass transfer and energy transfer, is combined with state space analysis methods of nonlinear control system, so that an optimal control model of nonlinear combustion control system for hydrogen fueled engines can be established. Through illustrating the inner relations between combustion and energy transfer of hydrogen fueled engines and operating parameter, state parameter and performance index, this paper provides theoretical analysis and found experimental research for promoting abnormal combustion and performance index after controlling operating parameters optimally and changing state parameters of the cylinder. Based on nonlinear programming theory and multi-objective genetic algorithm, the methods of establishing the optimal control model and carrying out the optimal value of operating parameters are shown in this paper. What’s more, some new ways are proposed to integrate the optimal control aspects of multi-variate, multiple targets and multiple constraints for hydrogen fueled engines by changing the multi-objective and multi-constraint optimal control into the single-target integrated optimal control.     

Monitoring combustion systems using HMM probabilistic reasoning in dynamic flame images

In this paper, a novel method of on-line flame detection in video is proposed. Processing the data generated by an ordinary camera monitoring scene, it aims to early detect the current state of the combustion system and prevent the system from further degradation and occurrence of failure. Due to the dynamic change of the combustion system, the turbulent flame flicker produces images with different spatial and high temporal resolutions. The proposed method consists of hidden Markov model (HMM) and multiway principal component analysis (MPCA). MPCA is used to extract the cross-correlation among spatial relationships in the low dimensional space while HMM constructs the temporal behavior of the sequential observation. Although the prior process knowledge may not be available in the operation processes, the probability distribution of the normal status can be trained by the images collected from the normal operation processes. Subsequently, monitoring of a new observed image is achieved by a recursive Viterbi algorithm which can find the transition state sequence from series of observed image data. The proposed method, like the philosophy of traditional statistical process control, can generate simple probability monitoring charts to track the progress of the current transition state sequence and monitor the occurrence of the observable upsets. The advantages of the proposed method, data from the monitoring practice in the real combustion systems, are presented to help readers delve into the matter.     

Thermal performance analysis on a two composite material honeycomb heat regenerators used for HiTAC burners

Honeycomb heat regenerators do not only reduce the fuel consumption in a high temperature air combustion (HiTAC) burning system but also provide the necessary high temperature of combustion air. A two-dimensional simulation model was developed to numerically determine the dynamic temperature and velocity profiles of gases and solid heat-storing materials in a composite material honeycomb regenerator. Consequently, the energy storage and the pressure drop are calculated and the thermal performance of honeycomb heat regenerator is evaluated at different switching times and loading. The model takes into account the thermal conductivity parallel and perpendicular to flow direction of solid and flowing gases. It considers the variation of all thermal properties of solid material and gases with temperature. Moreover, the radiation from combustion flue gases to the storage materials was considered in the analysis. The results are presented in a non-dimensional form in order to be a design tool as well. These analyses were applied on a regenerator made of two layers of ceramic materials, one is pure alumina and other is cordierite. This regenerator is contained in a 100 kW twin-type regenerative-burning system used for HiTAC. The effectiveness and the energy recovery rate were 88% and 72% respectively at nominal operating range of the regenerator and the pressure drop across the twin regenerator system was 1.16 kPa. The periodic steady state condition is reached after about 11 min and it takes only 2 min of operation until the temperature of combustion air remains above the self-ignition temperature that is required for HiTAC. Furthermore, these mathematical analyses show good agreement with experiments made on the same regenerator. In the experiments, the dynamic behavior of the heat regenerator operation was considered in order to compensate measurement readings for this effect.     

预混气体在多孔介质中往复式超绝热燃烧的数值研究

根据气、固两相局部非热平衡假设，建立了RSCP系统的二维非稳态数学模型，对于固体能量方程中的辐射源项采用辐射传递的有限体积法求解，研究了当量比、换向半周期、混合气流速对温度分布、辐射热流量和放热率的影响，考察了最高温升和可燃极限与这些参数之间的关联．研究表明，燃烧室内温度呈梯形分布，高温区较宽；气体的最高温度明显高于绝热火焰温度；贫可燃极限显著扩展，对提高燃烧效率和节约能源有重要作用。     

Hydrogenoxygen steam generator for a closed hydrogen combustion cycle

The paper deals with the problems of hydrogen combustion in an oxygen environment to produce high-temperature steam to be used in electricity generation at various power stations including nuclear power plants (NPP). For example, the use of H₂/O₂ steam generator within a hydrogen energy complex may allow increasing the NPP power and efficiency under operating conditions due to hydrogen steam superheating of the main working fluid in a steam-turbine unit. In addition, the use of the hydrogen energy complex may allow adapting NPP to variable electric load schedules with the increasing share of such power stations as well as developing environmentally friendly technologies for electricity generation. In the paper, a new solution to the problem of the effective and safe use of hydrogen energy at NPP with a hydrogen energy complex has been proposed.Technical solutions to hydrogen combustion in an oxygen environment using direct injection of cooling water or water steam into combustion products may have a significant weakness, namely the “quenching” phenomenon occurring during water/water steam injection resulting in the recombination efficiency decrease during the cooling of combustion products which is reflected in the increased proportion of non-condensable gases. In this case, the supply of such mixture to the steam-power cycle may be unsafe, as it could result in the increased concentration of unburned hydrogen in the steam turbine flow path. In the paper, a closed hydrogen cycle along with the hydrogen steam superheating system on its basis has been proposed to solve this problem. The closed-circuit system of hydrogen combustion preventing hydrogen permeation into the working fluid of a steam cycle completely as well as ensuring its full oxidation due to some excess of circulating oxygen has been investigated by the authors.Two types of H₂/O₂ combustion chambers for the system of safe hydrogen steam superheating in NPP cycle by using the closed-circuit system of hydrogen combustion in an oxygen environment have been considered in the study. The required parameters of H₂/O₂ steam generator with regard to operating temperature conditions as well as the power range of H₂/O₂ steam generators with the proposed combustion chamber construction design have been determined by mathematical modeling of the combustion and heat-mass-exchange processes.     

链条炉区段烟气再循环对锅炉运行及NOx排放特性影响的工业试验研究

针对一台采用尽早配风方式的29MW链条炉进行分区段烟气再循环对锅炉运行及NOx排放特性影响的工业试验。在挥发分析出及燃烧区段煤层下的一次风室混入再循环烟气将有效强化该区段煤层燃烧，降低该区段煤层以上燃烧空间的氧浓度，控制及消减挥发分N向NOx的转化，同时降低了穿过该区段煤层一次风的氧浓度，抑制焦炭N向NOx转化，NO消减效果最高达到25%。在焦炭燃烧区段煤层下的一次风室混入再循环烟气，能够降低穿过床层气流的氧浓度，抑制焦炭氮向NO的转化过程，该区段烟气再循环低氮效果有限，最大降幅9%。再循环烟气可以替代部分一次风，以维持足够的风室风压，进而降低穿过煤层气流的O2浓度，从而强化链条炉区段燃烧特性的低氮特征，实现链条炉的NOx减排。随着工业锅炉NOx排放指标的不断提高，烟气再循环作为一项有效的前置低氮环节，能有效降低整个低氮系统的投资，进而取得较好的经济性。     

涡流室式LPG柴油双燃料发动机燃烧模型

根据涡流室、主燃室中气体流动过程的质量和能量的交换关系 ,建立了涡流室式 LPG ( liquefiedpetrdeum gas) /柴油双燃料发动机准维燃烧模型的方程 ,提出了如何使两种不同性质燃料的燃烧在同一个燃烧过程中相互联系、相互作用的燃烧模型。根据模型提供的方程 ,对缸内燃烧过程和 NOx 的生成进行了模拟仿真 ,将其同发动机台架试验的结果进行了验证、分析和讨论。