脉冲燃烧加热炉的空燃比控制技术

加热炉采用脉冲燃烧控制时,其空燃比控制是一个难点,本文针对此问题,介绍和论述了几种在实际工程中行之有效的空燃比控制方案及其优缺点。     

燃气锅炉燃烧系统的预测控制

国内不少钢铁厂把高炉、转炉产生的煤气混合后用作工业锅炉的燃料,然而由于混合煤气的压力、热值都极不稳定,锅炉的燃烧子系统难以控制,更难以调整到最佳燃烧状态.针对以上问题提出在传统的双交叉PID燃烧控制基础之上,增加单变量预测控制层,根据空燃比和氧含量之间的关系,通过滚动优化在线得到最优空燃比.文章将配比优化问题转变成了控制器设计的问题,这样既可有效克服煤气热值的大范围变动,又能将整个锅炉燃烧系统调整到最佳的燃烧状态.     

燃烧空燃比控制系统性能评估!

保持PID控制器性能的优越性是工厂高效生产的重要前提。分析了燃烧空燃比系统的组成、工作原理和系统存在的问题。采用了递推最小二乘方法对其闭环传递函数进行系统参数辨识。基于最小方差基准,提出利用线性回归算法和遗传算法两种控制方案,对燃烧空燃比系统进行了性能评估对比分析,有效实现了对燃烧空燃比系统的实时监测,提高了燃烧效率。针对管压力波动和阀门黏滞这两种扰动动态,提出了H2范数和权重系数相结合的方法,对燃烧空燃比系统进行了控制器性能评估。基于该方法设计的最优控制器,大幅度提高了系统控制性能,有效解决了由于阀门粘滞对燃烧空燃比系统造成的振荡问题。     

基于智能控制的加热炉自动化系统

通过对国内加热炉控制现状及技术难点的分析．提出采用非线性的模糊控制与线性的PI控制相结合的双模态炉温控制方案，运用神经网络空燃配比寻优技术实现燃烧的最佳化，设计基于数学模型与操作经验的专家系统解决各段炉温的自动设定问题，从而实现了对整个加热过程的全自动智能控制。实际运行结果表明，该系统可靠性强，控制精度高，节能效果明显，对工业炉窑的控制具有一定的推广价值。     

热轧加热炉燃烧控制系统的优化

针对热轧加热炉燃烧控制系统中设定的空燃比与最优空燃比偏差大及氧化烧损高等问题,迁钢2160热轧加热炉在以空气和煤气双交叉限幅自动调节的基础上,引入热值仪进行理论空燃比的计算,根据此理论值进行空气与煤气的比例设定,又根据炉内残氧分析仪测量出的氧气含量对空气过剩系数进行修正,并把空气过剩系数和双交叉限幅系数进行优化,对燃烧的6个控制段进行分区控制,从而改变了炉内各个燃烧段的燃烧过程。通过优化控制实现了设定的空燃比更接近最优空燃比,提高了燃烧效率,氧化烧损也得到了降低。     

基于PCS7的加热炉燃烧控制策略及仿真研究

针对加热炉控制系统中存在的燃烧效率不高,控制响应延迟大的问题.设计了一套基于某公司SIMATIC PCS7控制系统的加热炉燃烧控制策略.系统针对加热炉燃烧控制中的主要参数:物料出口温度,空燃比,炉膛压力分别采用率级双交叉比值限幅控制策略,模糊控制策略和前馈控制策略进行控制.控制过程采用高级多功能过程实训系统(SMPr)仿真加热炉,利用SIMATIC PCS7控制系统实施加热炉的控制方案并利用上位机软件WinCC进行在线的实时监控.控制过程自动运行,根据控制过程和仿真结果表明,方案安全可靠,控制效果和可行性较好.比较于传统的基于数学模型的加热炉控制策略,方案提供了一种新型的控制策略,在很大程度上解决了加热炉燃烧效率不高,控制响应延迟大的问题.     

钢厂热风炉燃烧控制模型的开发与应用

针对热风炉燃烧系统的复杂性、参数不确定性和非线性,以及某钢厂热风炉燃烧控制过程存在的问题。结合国内外操作经验，在分析拱顶温度变化与最佳空燃比关系、废气温度变化与煤气流量关系的基础上，开发了基于模糊控制的热风炉燃烧控制模型。应用结果表明,该模型的应用实现了燃烧过程的自动控制．提高了热交换效率，节约能源．易于实现。     

基于神经网络的加热炉烟气含氧量预测及控制

文中提出一种加热炉烟气含氧量的神经网络预测方法,并将预测结果用于加热炉空燃比设定补偿,从而实现了加热炉烟气含氧量的空燃比预测补偿控制。仿真结果和实践表明,该预测控制方案是可行的,具有很好的控制效果。     

加热炉煤气热值测量及燃烧控制系统

介绍煤气热值测量系统的组成、工作原理及系统特点,利用热值参数参与空燃比控制。系统运行良好,性能稳定,特别是利用热值参数鸽时调节空气、煤气的配比,调节各段温度。     

氧化锆氧量检测器在锅炉燃烧控制中的应用

1前言在我国企业中，尤其是中小型企业中，数以万计的工业锅炉，效率较低，能源浪费较大。效率不高固然有多种原因，但空燃比不合适却是重要因素之一。保持合理的空燃比是实现经济燃烧的关键，而烟气中的含氧量就能较好地反映空燃比是否合适，因此，我们只要检测到了烟气中的含氧量，便可控制空燃比，使燃烧处于较经济状态，从而节约燃料。氧化锆氧量检测器是一种实用的测量烟气含氧量的仪器，但目前使用的不多，我们认为有两个原因，一是空燃比不合适所造成的浪费没有引起人们足够的重视；二是氧量检测器的寿命较短。2使用情况我厂是国家大…     

A method for carbon oxide concentration evaluation in high-temperature combustion processes

A method for evaluating carbon oxide concentration in high-temperature combustion processes is presented. The paper offers an optimizing control problem for fuel combustion process using a stabilizing regulatory controller, which affects the fuel/air ratio with respect to carbon oxide concentration in the firebox. In this connection, an approach is offered to solving this problem subject to the correction factor compensating for the error of carbon oxide concentration measurement.     

玻璃窑炉燃烧过程自寻最优控制

本文论述了用微型计算机对玻璃窑炉的玻璃温度、重油流量、空气流量、重油流量与空气流量之比值等主要工艺参数进行控制的基础上,采用步进搜索自寻最优点控制算法,通过修改二次风(助燃风)流量与重油流量之比值,对二次风流量进行自动搜索,使之工作在最佳值附近,实现燃烧过程的最优控制。     

Control of parallel dry methane and steam methane reforming processes for Fischer–Tropsch syngas

The ratio of hydrogen to carbon monoxide in the synthesis gas required for feeding to the gas-to-liquid Fischer–Tropsch (FT) process to produce liquid transportation fuel is about two. The dry methane reforming (DMR) process feeds carbon dioxide and methane and produces a syngas with a H₂/CO ratio of about unity. The steam methane reforming (SMR) process feeds water and methane and produces a syngas with a H₂/CO ratio of about four. This paper studies the plantwide control of a process with DMR and SMR units operating in parallel to produce FT syngas. The total methane fresh feed is split between the two parallel processes in the appropriate fraction so as to produce the desired H₂/CO ratio in the mixed syngas stream from the process.Both the SMR and DMR reactions are highly endothermic and the reactors are fired furnaces with combustion of fuel providing the endothermic heat of the reactions. Reactor exit temperatures are controlled by manipulating the flowrates of fuel to each furnace, with combustion air ratioed to the fuel. Dynamic reactor models assume tubular SMR and DMR reactors in which heat fluxes are determined by the heat generated in their associated fuel/air combustion reactors.The plantwide control structure effectively handles large 20% disturbances in throughput and large setpoint changes in the desired H₂/CO ratio (1.7–2.3).     

柴油机可调涡流比燃烧过程三维仿真

在柴油机进气歧管前安装蝶形涡流调节阀,通过调整直气道侧的有效流通面积改变缸内涡流强度。在稳流吹风试验平台,研究涡流调节阀角度对进气道流量因数和涡流比的影响,并结合粒子图像测速（particle image velocimetry,PIV）分析缸内涡流的形成过程。采用计算流体力学（computational fluid dynamics,CFD）评估涡流调节阀角度对缸内混合气体形成过程的影响,计算结果可复现三维 PIV测量的缸内流场结构和相似的涡心位置。随着进气门关闭,涡流比从0.57提高到2.05,油气在周向的相互作用增强,从而加速预混燃烧阶段的放热速度,促使燃烧重心提前、燃烧持续期缩短。在相同进气流量条件下,强涡流运动也促使累积放热量增加。     

Extremum seeking-based optimal EGR set-point design for combustion engines in lean-burn mode

In lean combustion mode, exhaust gas ratio (EGR) is a significant factor that affects fuel economy and combustion stability. A proper EGR level is beneficial for the fuel economy; however, the combustion stability (coefficient of variation (COV) in indicated mean effective pressure (IMEP)) deteriorated monotonously with increasing EGR. The aim of this study is to achieve a trade-off between the fuel economy and combustion stability by optimizing the EGR set-point. A cost function (J) is designed to represent the trade-off and reduce the calibration burden for optimal EGR at different engine operating conditions. An extremum-seeking (ES) algorithm is adopted to search for the extreme value of J and obtain the optimal EGR at an operating point. Finally, a map of optimal EGR set-value is designed and experimentally validated on a real driving cycle.     

Optimization and control of a stand-alone hybrid solid oxide fuel cells/gas turbine system coupled with dry reforming of methane

This paper presents the hybrid solid oxide fuel cells (SOFC)/gas turbine (GT) system coupled with dry reforming of methane (DRM). The DRM is a syngas producer by consuming greenhouse gas. The stand-alone (off-the-grid) power system is developed by using a combination of a post-burner, recuperators and pressurized recycles in place of external energy supplies. To address the stand-alone operation and meet the complete combustion condition for the burner, the optimal operating conditions are initially determined by solving a constrained optimization algorithm for maximizing the hybrid power efficiency, and the dynamic control loops are implemented in a plantwide environment. In the proposed plantwide control strategy, the inventory control framework is added to regulate the plant component inventory, an air/fuel cross-limiting combustion control is added to ensure complete combustion and reduce heat loss, and the power and CO₂ emission control configuration is added to achieve the quality control performance. Finally, the simulation shows that the IMC-based multi-loop control scheme can efficiently regulate the total system power and control CO₂ emissions per kWh of electricity as well.     

Multi-objective model-based control for an automotive catalyst

A model-based feedforward/feedback air fuel ratio controller that optimizes the oxygen storage capacity of the three-way catalyst in automotive emission control systems is presented. This work incorporates a simplified dynamic catalyst model that describes the physical behavior of oxygen chemisorption and reversible deactivation in the catalyst system. A novel aspect of this work is the use of the oxygen storage capability of the catalyst not only to minimize vehicle emissions but also to optimize engine performance and fuel economy during transient engine demand. The feedback/feedforward controller is a nonlinear model predictive controller that incorporates catalyst, engine air fuel ratio controller, and fuel system models to determine the optimal air fuel ratio target trajectory. Feedback is provided by a nonlinear moving horizon estimation strategy for the determination of the oxygen storage level of the catalyst based on air fuel ratio sensors.     

基于分离方法的加热炉燃烧控制策略

针对加热炉燃烧控制中普遍存在的燃气热值不稳定问题,提出一种燃烧控制的新方案--分离控制.该方法保留了传统的温度-燃料流量串级控制,同时按照生产率模型调节空气流量,克服了以往串级比值燃烧控制策略无法解决的燃料热值波动时空燃比难以自动修正的缺陷.实际工业应用结果表明,分离控制不但较好地解决了热值波动时燃烧效率问题,而且改善了炉膛温度的控制质量.