Cement Rotary Kiln Research Articles

Design and Evaluation Measurements of a Swirl Stabilized Laboratory Burner

This article presents gas velocity and temperature measurements obtained in a versatile multi-fuel swirl-stabilized laboratory burner of 100 kW total thermal input, which was designed as a scale model of a 110 MW coal burner operating in a cement rotary kiln. The laboratory burner is able to produce flames with different aerodynamic characteristics, namely, the independent adjustment of swirl to axial air and to burn a combination of gaseous, liquid, and pulverized solid fuels; only gaseous fuel, i.e. methane, was used in the present investigation. Experimental measurements were obtained in the near-burner region, with and without combustion, under varying operating conditions. The present investigation was mainly focused on the effect of swirl and its interaction with the combustion process.

05/02275 Energy auditing and recovery for dry type cement rotary kiln systems — a case study

05/02275 Energy auditing and recovery for dry type cement rotary kiln systems — a case study

Microstructure and properties of hercynite–magnesia–calcium zirconate refractory mixtures

Refractory manufacturers have focused their investigations on the development of chrome-free products that suitably meet the refractory lining requirements of cement rotary kilns. The experimental development of refractory mixtures based on magnesia and calcium zirconate, to which electrofused hercynite was added, was carried out in this work. Formulations, in which various amounts of hercynite were added to study its influence on MgO–CaZrO 3 microstructure and properties, were prepared. Samples were obtained by compacting powders and sintering in an industrial tunnel kiln. The samples were characterized via XRD and SEM. The strength of the refractory was determined at room temperature. Resistance to attack by cement raw meal at 1300 °C was studied. According to the results, formulations with the addition of hercynite show superior cold crushing strength compared to those without the additive, moreover, all compositions showed good chemical resistance to the presence of cement raw meal.

Sintering of magnesia refractories through the formation of periclase–forsterite–spinel phases

Effect of calcined kaolin additions on sinterability of dead-burned magnesia was studied through additions of Egyptian kaolin. Five batches containing powders of 100/0, 90/10, 80/20, 70/30 and 60/40 magnesia/kaolin, respectively, were mixed, dried and fired up to 1550 °C for 4 h. Their physical (bulk density and apparent porosity), mechanical (cold crushing strength) as well as refractory (thermal shock resistance and refractoriness under load) properties were tested according to the International Standard Specifications. The phase compositions of the fired batches were investigated using X-ray diffraction as well as scanning electron microscope to illustrate the effect of the different developed phases on the above properties compared with the main magnesia source itself. Generally, samples containing 10–20 wt.% kaolin are characterized by their high sintering, mechanical and refractory properties, so they are recommended for use as a lining for different parts of steel furnaces as well as heating zone of cement rotary kilns. Samples containing 30–40 wt.% kaolin with lower refractory properties can be used in the heat exchangers or as kiln furniture in ceramic industries.

Damages of Refractory Bricks in Cement Rotary Kiln

Damages of Refractory Bricks in Cement Rotary Kiln

Energy auditing and recovery for dry type cement rotary kiln systems––A case study

Cement production has been one of the most energy intensive industries in the world. In order to produce clinker, rotary kilns are widely used in cement plants. This paper deals with the energy audit analysis of a dry type rotary kiln system working in a cement plant in Turkey. The kiln has a capacity of 600 ton-clinker per day. It was found that about 40% of the total input energy was being lost through hot flue gas (19.15%), cooler stack (5.61%) and kiln shell (15.11% convection plus radiation). Some possible ways to recover the heat losses are also introduced and discussed. Findings showed that approximately 15.6% of the total input energy (4 MW) could be recovered.

03/01934 Investigaton of energy saving and NO x reduction possibilities in a rotary cement kiln : Akgun, F. International Journal of Fnergy Research, 2003, 27, (4), 455–465

03/01934 Investigaton of energy saving and NO x reduction possibilities in a rotary cement kiln : Akgun, F. International Journal of Fnergy Research, 2003, 27, (4), 455–465

Investigaton of energy saving and NOx reduction possibilities in a rotary cement kiln

In this study, the possibilities of energy saving and NO x reduction achievable by operational changes in a rotary cement kiln system have been investigated. Basic input data were obtained from the field measurements. Analysis has been carried out considering the energy balance and reaction kinetic calculations. Simply controlling the operational parameters, the options of 7.5% energy saving and 15% NO x reduction have been obtained.

Phase Relations in the MgO-Rich Region of the System MgO-Fe2O3

Fe2O3-added magnesia-spinel brick, in replacing magnesia-chrome brick, has been recently used as a basic refractory for the burning zone in cement rotary kiln. According to the system MgO-Fe2O3 phase diagram, the phase change and the separation with temperature fluctuation in the kiln may damage the microstructure of the magnesia-spinel brick, which leads to the quality deterioration. The MgO-rich region of this system has been investigated by using a high-temperature X-ray diffraction (XRD) apparatus in air. The change from MgOss to MgO accompanied by the exsolution of Fe3+ occurs possibly around 1010°C based on the phase diagram. However, MgOss was found to still exist at room temperature in this study. Also, it was proved that the formation temperature of the solid-solution including 5-20mass%Fe2O3 shifted to a higher temperature compared to the conventional result. The unknown edge of the boundary line between MgOss and MgOss+MgFe2O4 on the MgO-Fe2O3 composition line was estimated in the system MgO-FeO-Fe2O3 phase diagram by considering the oxygen partial pressure of the atmosphere as 0.1MPa. The lattice constant of MgOss was altered by the change of the electronic spin state of Fe3+ from low-spin state to high-spin state around 1100°C on a temperature-elevated process, together with the solution quantity of Fe3+ and heating temperature. Furthermore, the crystal strain of MgOss and MgFe2O4 increased remarkably upon this spin alternation. However, the reverse-change of the spin state could not be recognized on a cooling process, then MgOss was considered to be metastable due to this slow reverse-change. The existence of MgOss single phase in the system MgO-Fe2O3 became clear under expanded conditions, which certainly contributes to the realization of the long life time of magnesia-spinel bricks.

Determination of Cu and Ni incorporation ratios in Portland cement clinker

Cu and Ni are metals found in galvanic sludges; these sludges are considered hazardous due to their heavy metal content. The main objective of this work is to determine the incorporation amount of Cu and Ni in Portland clinker when a galvanic sludge containing these metals is added to the clinker raw-material. The influence of this addition on the clinkering reactions is evaluated as well as the possibility of co-incinerating galvanic sludges containing Cu and Ni in rotary cement kilns. This study also characterizes the galvanic sludge. Samples were prepared by additions from 0.25 to 5 wt.% of a galvanic sludge to an industrial clinker raw-material. The clinkering process was simulated in a laboratory device. The following techniques were applied to characterize the raw materials and the products of the tests: chemical analysis, differential thermal analysis (DTA) and thermogravimetric analysis (TG). Leaching tests were performed in the produced clinker samples in order to verify the incorporation of the studied metals in the clinker structure. The results led to the conclusion that additions of up to 2 wt.% of a galvanic sludge containing 2.4 wt.%Cu and 1.2 wt.% Ni to clinker raw-material do not affect the clinkering reactions and that these metals are totally incorporated into the clinker.

A theoretical analysis on combustion intensification for blended coal in rotary cement kiln

A theoretical analysis on combustion intensification for blended coal in rotary cement kiln

Chloride influence on the incorporation of Cr 2O 3 and NiO in clinker: a laboratory evaluation

Co-incinerating wastes in cement rotary kilns may introduce elements not usually found in the raw material into the process or even increase the quantity of some minor elements. Chromium and nickel are present in some electroplating sludges. These wastes are hazardous and must be treated and disposed of in a controlled landfill. The objective of this work was to study the incorporation of chromium and nickel oxides when they were added to clinker raw meal. The clinker raw meal used in this study was prepared by mixing pure compounds in the ratio that made it possible to obtain the same phases of an industrial Portland clinker at the end of the heating process. Twelve samples were prepared by adding 0.05, 0.1, 0.3, 0.5, 0.8 and 1.0 wt.% of Cr 2O 3 and 0.05, 0.1, 0.3, 0.5, 0.8 and 1.0 wt.% of NiO to the base charge. Also, four more samples were prepared with additions of 0.6% Cr 2O 3 and 0.1% NaCl, 0.7% Cr 2O 3 and 0.1% KCl, 0.8% NiO and 0.1% NaCl and 0.8% NiO and 0.1% KCl. In order to study the Cr and Ni incorporation, thermogravimetric (TG) tests were performed, as well as tests in an assembled experimental device. The products were characterized by X-ray fluorescence chemical analysis, microprobe analyses by energy disperse scanning (EDS) and leaching tests. The results showed that the chromium and nickel added were incorporated into the clinker, even when chlorides were present.

Design and finite element analysis of a wet cycle cement rotary kiln

The finite element method (FEM) is applied to the nonlinear analysis of a cement rotary kiln for the Raı̈s Hamidou factory (Algeria). The nonlinearity is due to contact conditions between the kiln body, tyres and foundations. The FEM is first used in a reduced model of the kiln in order to obtain the meshing criterion for the global model. Then, an overall FEM analysis is performed for the different operating and live loads at different positions of the rotary kiln. Stress and displacement components are evaluated based on the ASME rules (Asme Boiler and Pressure Vessel Code. VIII. Division 2—Alternative Rules. The American Society of Mechanical Engineers, 1995). Finally, in this work, the main design criterion is the out-of-roundness values at the kiln shell so that the thickness of the kiln shell is smaller in the central bend span than the values at the tyres.

Basic Refractories for Cement Rotary Kiln

Basic Refractories for Cement Rotary Kiln

A theoretical analysis on combustion intensification for blended coal in rotary cement kiln

Blended coal that consists of 70% anthracite and 30% bituminous coal is cheaper than pure bituminous coal, but it is very difficult to burn in the rotary cement kiln. To burn the blended coal, a new kind of burner, which is called the burner with velocity difference jets, is used to intensify combustion. However, combustion intensification and the formation of stable sintering layer should be ensured simultaneously in the cement industry. To compromise the above two aspects, the better burner construction is decided by simulation. The combustion processes in the rotary cement kiln are simulated by means of improved multi-fluid model for two-phase turbulent flows with reaction. The results of integral simulation show that the ignition of blended coal is slower than that of bituminous coal, but the flame of blended coal is longer than that of bituminous coal. Thus the use of blended coal not only reduces the cost but also more suits wet kiln.

Defragilization in optimal design and its application to fixed structure LQ controller design

In this work, we present a general methodology to address the recently debated fragility issue in optimization-based modern control systems design. Based on this methodology we have developed a defragilization procedure which is applied to fixed structure linear quadratic (LQ) control design. Issues regarding computational efficiency of the procedure and the relationship between controller fragility and controller parameterization are discussed via two examples taken from practical applications. The first example is based on a rotary cement kiln control application and the latter example on a wing flutter control application. The procedure could also be used in design problems with specifications which are related to controller nonfragility requirements, e.g., so as to allow some degree of controller online tuning.

Simulating the Impact of Oxygen Enrichment in a Cement Rotary Kiln Using Advanced Computational Methods

This work presents the simulation of a rotary kiln used to produce cement clinker. The effort uses an original approach to kiln operation modeling. Thus, the moving cement clinker is accurately simulated, including exothermal reactions into the clicker and advanced heat transfer correlations. The simulation includes the normal operation of a cement kiln, using coal in an air-fired configuration. The results show the flame characteristics, fluid flow, clinker and refractory characteristics. Two types of coal are employed, one with medium-volatile and one with low-volatile content, with significant differences noted in the kiln operation. A specific goal of this effort is to study the impact of oxygen enrichment on the kiln operation. For this purpose, oxygen is lanced into the kiln at a location between the load and the main burner, and the impact of oxygen enrichment on the kiln operation is assessed. Different oxygen injection schemes are also studied. Thus, varying the angle of the oxygen lance enables to handle various problems as reducing conditions, overheating in the burning zone or refractory wall. It is concluded that oxygen has a beneficial role in the fuel combustion characteristics, and its impact on refractory temperature and the clinker is negligible, in conditions of increased productivity and overall efficiency. The paper presents the impact of dust insufflation into the kiln, such as reduced temperature profile, resulting in a less stable combustion process. The work shows the beneficial influence of oxygen enrichment on kiln operation in the presence of dust, leading to an increase in the amount of dust capable of being insufflated into the kiln. The paper presents the impact of dust insufflation into the kiln, such as reduced temperature profile, resulting in a less stable combustion process. The work shows the beneficial influence of oxygen enrichment on kiln operation in the presence of dust, leading to an increase in the amount of dust capable of being insufflated into the kiln.

プラズマ処理によるマグクロ廃煉瓦のリサイクル

A large amount of magnesia-chromia waste bricks have been reclaimed after the use in high temperature furnace such as cement rotary kilns, steel refining furnaces and so on. For the recycle of these waste bricks, the carbon deoxidization and metal recovering was tested with high temperature plasma furnace.

Evaluation of damage caused in bricks by condensed alkali salts in cement rotary kilns

Evaluation of damage caused in bricks by condensed alkali salts in cement rotary kilns

The Lining for Rotary Cement Kilns

The main accent in the study of cement clinker-based refractory materials was placed on an optimum choice of the clinker-to-cement proportion, on a rational chemical, mineral, and granulometric composition of the clinker, on the development of techniques for laying and fixing the lining, on an optimum choice of water-to-cement ratio, on the use of various additions for increasing the heat resistance of the concrete, etc.