水泥窑灰塑性混凝土防渗墙材料基本性能试验研究

基于无侧限抗压强度试验、直剪试验和渗透试验,研究了水泥窑灰取代水泥配制土–膨润土–水泥窑灰塑性混凝土的基本性能。结果表明：配制的塑性混凝土14天和28天龄期的无侧抗压强度分别在2.82 ~ 12.81 MPa和3.76 ~ 14.98 MPa之间;其无侧限抗压强度随粉土含量增加有所降低,但降幅不明显;膨润土和水泥窑灰含量增加,其无侧限抗压强度有明显提高;该塑性混凝土14天和28天龄期的黏聚力分别在0.3 ~ 2.1 MPa和0.2 ~ 2.1 MPa之间,内摩擦角分别在23.7° ~ 55.5°和20° ~ 48.5°之间;黏聚力随粉土、膨润土和水泥窑灰含量的增加均呈增加趋势;内摩擦角随粉土、膨润土和水泥窑灰含量的增加而减小;该塑性混凝土14天和28天龄期的渗透系数在1.62×10-7 ~ 1.79×10-8 m/s和1.54×10-7 ~ 1.01×10-8 m/s之间,且随粉土、膨润土和水泥窑灰含量的增加呈降低趋势;粉土、膨润土和水泥窑灰掺量为15%时比较合适。     

声波清灰器在电除尘器上的应用

山东铝业公司水泥厂5 号水泥窑极线肥大,二次放电电流降低,引起电晕闭塞,粉尘排放状况严重恶化,大大超过国家标准。6 号水泥窑生产氧化铝熟料,电除尘器在运行过程中,经常出现窑灰结拱现象,导致灰斗蓄满,窑灰撒地,无法正常送电和除灰,粉尘排放状况严重超标,大量碱粉流失,使生产成本上升。5 号水泥窑安装声波清灰器后,经5 个月的实际运行,电除尘器粉尘排放已达到国家标准,极线的二次电流提高1 倍左右。6 号水泥窑安装声波清灰器后,电除尘器烟尘排放浓度可达80 mg/ m3 以下,已安全运行9 个月,未发生1 起因窑灰结拱造成蓄灰撒地事故。每年因减少碱粉流失,可节省费用30 万元。     

A Computer Model for the Cement Kiln

A dynamic model for a cement rotary kiln is proposed. It is simple enough for computer application, yet takes into account all the operational parameters actually encountered in real practice, and thus is capable of identifying the effective controlling decisions in order to realize a desired gas temperature profile, essential for optimal clinker production. The model is built in two parts. The first represents the solid-gas interchange. Its solution yields the gas temperature profile needed for good clinkering. The second represents the gas-coal dust interchange. Its solution yields the operating parameters needed to realize the desired gas temperature with a good burning of coal dust and minimal coal waste. The first part of the model is made of two and the second part of three nonlinear partial differential equations, with the independent variables being the time t and the longitudinal position x along the kiln. Boundary conditions are dictated by the operating conditions. Initial conditions are obtained by solving the static model. An example is worked out to show how the model helps to choose the coal dust input, the coal dust diameters, and other operational parameters for a good operation of the kiln. It also shows to what extent the burning of coal dust and the resulting gas temperature profile are influenced by the various operational parameters.     

Cement kiln dust (CKD) methods for reduction and control

Cement kiln dust (CKD) is a waste product generated during the manufacture of Portland Cement. Volatile compound buildup in cement kilns results in the need to purge the system which stabilizes the process or brings the product quality within specifications. This paper outlines a stepwise approach for reducing CKD generation. The present cost penalties for generating CKD along with potential future liabilities of stored dust should make CKD reduction a main priority. Many cement plants have gone through similar investigations in the past, however most could benefit from re-examining their present dust wasting situation and applying new testing programs now available. This investigative process can be relatively simple and should be a high priority on any cement plant's agenda. Following a stepwise, organized approach can often result in large reductions in dust wasting. Today's technology allows the improved sampling and rapid chemical analysis needed for each plant to establish and follow a volatile management program resulting in the reduction of CKD generation     

The Production of Electrical and Thermal Energy from the Exhaust Gas Heat of Preheater Kilns

It is shown, by means of an example, i.e., a 1600-ton/day four-stage suspension preheater kiln of a cement factory, that the waste heat present in the exhaust gases can be converted into useful electrical and thermal energy. This is possible even though the exhaust gases are heavily loaded with dust. The heat recovery system installed in 1981/1982 in a Swiss cement plant and the respective production line are described in detail. A comprehensive explanation is given concerning the experience of the first operating year, the iqteraction of the new plant with the existing production facilities, and the current measured technical data. The performance limits for economic operation are explained and the decision criteria quoted. Further applications of the successfully tested heat recovery system can be expected wherever beat sources in the form of heavily loaded gases are available.     

The Use of Carbon Monoxide and Other Gases for Process Control

The application of the analysis of trace gas emissions downstream of the process dust filters in a precalciner kiln as the means of controlling the air-fuel ratio is described. This application eliminated the need for a high-temperature probe in the kiln as the kiln excess-air requirement is determined and controlled based on carbon monoxide, nitrogen oxide, and sulfur dioxide concentrations downstream of the bypass dust filter. Control of the excess air in the precalciner is also based on the carbon monoxide concentration downstream of the preheater dust collector. Control by carbon monoxide has shown considerable advantages over the traditional technique of control based on oxygen analysis. These advantages include: 1) simplification of sampling, 2) increased kiln productivity and efficiency, 3) better operator response to analyzer information, 4) precise combustion control showing promise for reducing nitrogen-oxide emissions, and 5) control of clinker quality.     

Trends in Kiln Drives

The heart of the cement plant is the rotary kiln, and continuous quality production of cement clinker depends on the continuous accurate performance of the rotary kiln drive.     

水泥回转窑旋风预热器旋风数字控制系统研制

项目采用闭环控制,应用晶闸管技术对旋风预热器旋风实现数字控制,通过电压反馈来改变可控硅的导通角来控制风机,能得到所需要的理想风量,更充分的利用水泥回转窑的尾气热能,同时也能减少水泥回转窑污染废气排放,利于环保要求。模拟实验与现场运行验证了设计的有效性。     

回转窑筒体热损失测量系统的研究

以回转窑筒体的红外热图为基础,通过分析回转窑简体辐射与对流机理,给出了实际回转简体热损失的计算模型,并采用LabVIEW编程语言,设计开发了一套回转窑筒体热损失测量软件.最后,以某水泥回转窑为例,对所提出的方法进行了测试与分析.结果表明,该系统能获取简体感兴趣区域的轴向温度并正确计算出对应的简体热损失功率;简体的辐射热耗与对流热耗大小相当,且煅烧区简体的热损失约占输入热功率的4％.研究成果为回转窑的节能生产、过程参数优化奠定了基础.     

DC Kiln Drive Motors

The most important considerations in applying dc drive motors and thyristor power supplies to a cement kiln are their procurement, maintenance, and operating costs; and equipment reliability in the cement plant environment. Drive requirements and their effect on motor size are discussed. Efficiency comparisons at several speeds for three different designs of dc drive motors are made. Two motor kiln drives with motors connected in series and also in parallel are discussed. Recommendations for applying each connection with regard to drive horsepower and voltage are made. Included is a brief discussion on applying dc motors by taking a part of the total speed range as constant horsepower rather than taking the entire speed range as constant torque.     

水泥立窑的节能潜力

文章介绍了三种利用水泥立窑余热的方法。实践证明采用该三种余热利用措施后,可有效节约能源,降低水泥生产成本。     

Automatic Kiln Control at Oregon Portland Cement Company's Durkee Plant Utilizing Fuzzy Logic

The basis and experience in automating the control of a 1500- ton/day four-stage preheater cement kiln is described. The control substitutes the coordinative control actions formerly carried out by the kiln operators by utilzing a minicomputer to implement fuzzy logic control strategies. Operating decisions are made more consistent and quantitative and less subjective to human operator control philosophy variations. By making mathematical approximations of the relationship between changes in process variables through linear regression analysis and then by implementing verbally formulated control rules for corrective action, kiln fluctuations are reduced and more stable operation is achieved. The control is based upon a direct correlation between the nitric oxides measured in the kiln exit gases and the liter weight of the clinker in the burning zone. A consistent liter weight is the aim; however, a secondary control program assures the correct temperature/excess air after the preheater tower. Kiln speed and kiln feed are kept constant, and control actions are taken on the kiln draft by speed adjustments of the induced draft (ID) fan and fuel adjustments of a direct-fired coal mill by coal feeder adjustments into the mill. The system was installed durig March and April 1982, and the experience gained through the commissioning period and the first six months of operation is discussed. It appears that with the limited experience to date, a savings of about three to four percent in fuel efficiency is achieved. In addition, indications are that brick savings are substantial, as high as 50 percent.     

Outline of Ishikawajima-Harima Heavy Industry ? Suspension-Heater Flash-Furnace Clinker Burning Process

The suspension-preheater flash-furnace (SF) process for cement clinkering introduces a calcining flash furnace operating as an integral portion of a suspension preheater, rotary kiln, and clinker cooler system. Preheated raw meal from the suspension preheater is calcined in the flash furnace to 80 to 90 percent decarbonation. The capacity of the SF rotary kiln is increased thereby, since its function is limited to sintering rather than sintering and calcining. The flash furnace incorporates vortex flow to accomplish the mixing of fuel, raw meal, and gases. Effective distribution within the flash furnace limits temperature gradients and eliminates localized elevated temperatures that might otherwise lead to coating and material build-up. Hot combustion gases are recovered from the clinker cooler for use in the flash furnace. An orifice in the kiln gas exit duct serves to balance the parallel gas flows through the kiln and secondary air duct. Operating pressures and temperatures are described. The smaller size of the rotary kiln used in the SF process leads to extended refractory life as demonstrated by operating experience. The SF process is adaptable to the control of internal alkali, sulfur, and chlorine cycles through a gas bypass and through a unique material withdrawal arrangement from the flash furnace. Existing plants may be modified to incorporate the SF process. Nearly 20 commercial scale plants are operating or are being constructed.     

基于Lonworks现场总线的回转窑分解炉控制系统设计

基于Ｌｏｎｗｏｒｋｓ现场总线技术，构建了一个水泥回转 窑分解炉的分散式智能控制网络系统。对该控制系统的结构特征、控制策略等进行了探讨，并着重介绍了采用模糊控制算法的智能节点设计。     

Modern cement plant design with a view to efficiency and theenvironment

Using today's proven technology we can design a cement plant, which not only will meet many of the emission requirements, but also uses the least possible amount of thermal and electrical energy. Today's modern cement plant design will lower initial capital investment, lower operating costs, and also reduce the burden of the cement plant on the environment. These desirable requirements are achieved either directly by reducing process emissions or indirectly by significantly reducing power and fuel consumption per ton of product produced. The author discusses the following areas of design: raw grinding system, pyro-system design, kiln design, kiln burner design, tertiary air-take-off, and clinker cooler design     

大型多支承回转窑运行状态测试与分析便携式系统

回转窑是冶金、水泥、耐火材料生产中的关键设备，是一种重载、大扭矩、多支点、静不定运行系统。生产中需及时、准确、经常地检测回转窑的运行状态，以便对回转窑合理地进行调整与维护，确保它安全、高效地运行，这是相应生产企业提高经济效益的关键。本文介绍笔者研制的回转窑运行状态测试与分析便携式系统，该系统采用零位移方向键相测量原理测量轴线，克服了现有测量系统安装定位困难、测量操作复杂的缺点。系统结构简单、操作使用方便，能快速地进行回转窑运行轴线测量和运行状态分析，在实际应用中效果很好。     

Modifications to Precalciner Kiln Combustion Systems to Prevent Carbon Monoxide Electrostatic Precipitator Trips

The use of precalcining cement kilns has created a unique problem in both the cement kiln process and in environmental control. The operation of precalciner cement kilns yields a specific pattern of carbon monoxide (CO) generation because of the fuel-combustion process. As a result of this CO generation, automatic explosion protection systems de-energize the electrostatic precipitators (ESP's) used to control particulate matter emissions from the kilns.     

SO2/NOx control compliance with environmentalregulations

The sources of SO₂ and NO_x in a Portland cement kiln system are identified. A brief discussion of several known and theoretical control methods for cement-plant SO₂ and NO _x emissions is presented. The US Portland cement industry is shown to be a minor contributor of SO₂ and NO_x to atmospheric contamination. The anticipated need and/or requirement for continuous monitoring of SO₂ and NO_x is discussed. The political climate for regulation of SO₂ and NO_x is examined. Consideration is given to an emerging environmental issue, the greenhouse effect, to which the carbon dioxide emissions of cement plants may contribute     

Conversion of Existing Cement Kilns to Flash Calciners

Contemporary cement kilns equipped with a suspension preheater provide for efficient operation with the lowest specific heat consumption. The incorporation of a flash calciner reduces the fuel requirement of the rotary kiln, thereby improving refractory life and reducing nitrogen-oxide emissions. The benefits of suspension preheat and flash calcination can be achieved in existing wet or dry process plants. Such modifications can increase kiln production while reducing the specific heat consumption. Several existing long wet and long dry kilns and suspension preheater kiln systems have been modified to flash calciner configurations.     

Reduction of NOx emissions from a dry process preheaterkiln with calciner through the use of the urea-based SNCR process

The post combustion reduction of NO_x using urea has proven to be an effective method in controlling NO_x from various combustion sources, such a reduction process has been successfully demonstrated in a week-long test at Ash Grove's dry process cement kiln system located in Seattle. This system is equipped with planetary coolers, a 5-stage preheater and an air-through-the-kiln calciner. Testing was done under ten different kiln/calciner operating conditions. Using three to four injectors, NO_x was efficiently reduced from 350-600 lb per hour lb/ton of clinker to less than 100 lb per hour. This calculates to a NO_x reduction of greater than 80% for most cases. Chemical utilization was greater than 50% percent. A high degree of mixing and a long residence time at an appropriate temperature present in the preheater tower contributed to these excellent results. An average ammonia slip was four ppm above a baseline level at a normalized stoichiometric ratio of 1. This demonstration confirms expectations that dry process cement kilns with 4+ preheater stages are an ideal application for the selective noncatalytic reduction of NO_x with urea. NO_x was efficiently and effectively reduced with minimal byproduct emissions and virtually no effect on plant operations