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Cement production in rotary kilns requires large amounts of thermal energy, which is provided by combustion of different fuels. Substitution of fossil fuels by refuse derived fuels (RDF) can minimize production costs and reduce CO2 emissions, but often causes displacement of the sintering zone, impacts flame stability and cement quality. The curren...
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Context 1
... widely used for the production of cement clinker. The clinker formation process demands large amounts of thermal energy to heat up the material to sintering temperatures above 1700 K. To provide the energy required, different types of fossil and alternative fuels are commonly fired through the main burner at the material outlet of the kiln (see Fig. 1). Modern kiln burners are often so called multi-channel burners which consist of a ...
Context 2
... widely used for the production of cement clinker. The clinker formation process demands large amounts of thermal energy to heat up the material to sintering temperatures above 1700 K. To provide the energy required, different types of fossil and alternative fuels are commonly fired through the main burner at the material outlet of the kiln (see Fig. 1). Modern kiln burners are often so called multi-channel burners which consist of a number of different primary air and fuel conveyance ducts, allowing the combustion of different types of solid, liquid and gaseous fuels. Additional energy is provided by secondary air, which recuperates heat in the clinker cooler and enters the kiln as ...
Context 3
... rotary kiln is equipped with a typical high-momentum multi-channel burner which injects solid RDF through a central duct (Fig. 3). Pulverized lignite is fed by a co-axial ring channel. Both RDF and lignite are transported by conveying air. Primary air is delivered as jet-air and swirling air. Secondary air is preheated in the clinker cooler (see Fig. 1) and flows around the burner into the rotary kiln. The rotary kiln volume is discretised with approx. 3 million hexahedral cells with a high spatial resolution in the near burner region. The solid material passing the kiln is approximated by a static bed aligned with a dynamic angle of repose of 30 degrees. ...
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This study focuses on the petrographic analysis method to evaluate semi-coke and its combustion behavior in the sintering process, which has been seldom conducted before. Semi-cokes are different in morphological features, porosity, pore structure, and wall thickness, because of differences in the vitrinite and inertinite of the raw coal. Semi-coke...
Citations
... Conducting experiments in industrial facilities can be prohibitively expensive, underlining the extreme importance of modeling to simulate and optimize processes before implementing them in a real-world setting, especially using computational fluid dynamics (CFD) [10][11][12]. Some authors have used CFD modeling to predict the combustion behavior using alternative fuels in industrial cement rotary kilns in terms of flame temperature, flow velocity, flame stability, fuel and oxidant composition, emissions, and calcination reactions [7,10,11,13,14]. Liedmann et al. [7] started to study the influence of operating conditions in cement rotary kilns by co-firing different mixtures of RDF and pulverized coal. ...
... Some authors have used CFD modeling to predict the combustion behavior using alternative fuels in industrial cement rotary kilns in terms of flame temperature, flow velocity, flame stability, fuel and oxidant composition, emissions, and calcination reactions [7,10,11,13,14]. Liedmann et al. [7] started to study the influence of operating conditions in cement rotary kilns by co-firing different mixtures of RDF and pulverized coal. The authors experimentally characterized the different constituents of RDF (2D foils, 3D plastics, paper and cardboard, textiles, and fines) and studied their specific flight paths in an automated drop-shaft to obtain drag and lift coefficients and their corresponding fluctuations. ...
... Nonetheless, it is known that the industry is proactively pursuing ways to transition toward low-carbon practices to promote sustainable and environmentally conscious practices [3,4]. Additionally, the use of refuse-derived fuels (RDF) to substitute fossil fuels is also very appealing in the cement industry, as these have the potential to lower clinker production costs and CO 2 emissions [5][6][7]. The use of RDF in the cement Fuels 2023, 4 456 and particle size distributions. ...
As the need to minimize environmental impacts continues to rise, it is essential to incorporate , advance, and adopt renewable energy sources and materials to attain climate neutrality in industrial operations. It is established that economic growth is built upon infrastructure, where the cement industry plays a crucial role. However, it is also known that this industry is actively looking for ways to transition toward low-carbon practices to encourage sustainable and environmentally conscious practices. To this end, the use of refuse-derived fuels to substitute fossil fuels is very appealing, as these have the potential to lower clinker production costs and CO 2 emissions. Bearing this in mind, the primary objective of this work is to gain insights into the combustion behavior in an industrial rotary kiln by studying real-life scenarios and to assess the potential of substituting alternative fuels for fossil fuels to reduce CO 2 emissions. A 3D CFD turbulent combustion model was formulated in Ansys ® considering a Pillard NOVAFLAM ® burner, where refuse-derived and petcoke fuels were used, and different secondary air mass flows were considered. From the obtained results, it was possible to conclude that the outcome of the combustion process is greatly influenced by the fuel-to-air ratio. Increasing the secondary air mass flow promotes the occurrence of a complete and efficient combustion process, leading to enhanced fuel conversion and the decreased formation of pollutants such as CO, soot, and unburned hydrocarbons. An increase in combustion efficiency from 93% to 96% was observed, coupled with a slight decrease in the pollutant mass fraction in the flue gas.
... However, producing cement clinker is energetically intensive and poses as a significant contributor to CO2 emissions worldwide, but it is known that the industry is proactively pursuing ways to transition towards low-carbon practices to promote sustainable and environmentally conscious practices [3,4]. Additionally, the use of refused derived fuels (RDF) to substitute fossil fuels is also very appealing in cement industry, as these present the potential to lower the clinker production costs and CO2 emissions [5][6][7]. The use of RDF fuels in cement industry is actually a common practice since 1980's. ...
... Conducting experiments in industrial facilities can be prohibitively expensive, underlining the extreme importance of modeling to simulate and optimize processes before implementing them in a real-world setting, especially using computational fluid dynamics (CFD) [10][11][12]. Some authors have used CFD modeling to predict the combustion behavior using alternative fuels, in industrial cement rotary kilns in terms of flame temperature, flow velocity, flame stability, fuel and oxidant composition, emissions and calcination reactions [7,10,11,13,14]. Liedman et al. [7] started to study the influence of operating conditions in cement rotary kilns by co-firing different mixtures of RDF and pulverized coal. ...
... Some authors have used CFD modeling to predict the combustion behavior using alternative fuels, in industrial cement rotary kilns in terms of flame temperature, flow velocity, flame stability, fuel and oxidant composition, emissions and calcination reactions [7,10,11,13,14]. Liedman et al. [7] started to study the influence of operating conditions in cement rotary kilns by co-firing different mixtures of RDF and pulverized coal. The authors characterized experimentally the different constituents of RDF (2D foils, 3D plastics, paper and cardboard, textiles and fines) and studied their specific flight paths in an automated drop-shaft to obtain drag and lift coefficients and their correspondent fluctuations. ...
As the need to minimize environmental impact continues to rise, it is essential to incorporate, advance, and adopt renewable energy sources and materials to attain climate neutrality. It is established that economic growth is built upon infrastructure where cement industry plays a crucial role. However, it is also known that this industry is actively looking for ways to transition towards low-carbon practices to encourage sustainable and environmentally conscious practices. To this end, the use of refused derived fuels to substitute fossil fuels is very appealing, as these present the potential to lower the clinker production costs and CO2 emissions. Bearing this in mind, the primary objective of this work is to gain insights of the combustion behavior in an industrial rotary kiln, studying real-life scenarios and assessing the potential of substituting alternative fuels for fossil fuels to reduce CO2 emissions. A 3D CFD turbulent combustion model was formulated in Ansys® considering a Pillard NOVAFLAM® burner, where refused derived and petcoke fuels were used and different secondary air mass flows were considered. From the obtained results it was possible to conclude that the outcome of the combustion process is greatly influenced by the fuel-to-air ratio. Increasing the secondary air mass flow promotes the occurrence of a complete and efficient combustion process, leading to an enhanced fuel conversion and decreased formation of pollutants as CO, soot, and unburnt hydrocarbons.
... Avoid excessive fuel mix ash. The total ash for a main burner should ideally be below 30 kg ash/ton of clinker [105]. ...
... The calciner must ensure that kiln gases are distributed evenly, have a modest oxygen surplus, and minimize CO emissions [105]. ...
... The use of auxiliary units (reactors), such as Fire Bed Combustors (FBCs) or Step Combustors (SCs), plus efficient combustion in the main burner, should be taken into consideration to obtain the lowest specific fuel cost with the greatest amount of coarse alternative fuel [103]. Remember that the pneumatic portion of the transport line from the AFs to the main burner needs to be as short as possible (ideally, from the main burner platform), and that a straight transport line without any bends to the main burner is highly advised to reduce the amount of transport air and number of pulsation issues [105]. ...
The process of making cement clinker uses a lot of energy and produces a lot of pollution. Currently, cement companies use a combination of traditional fossil fuels and alternative fuels (AF-Fuels) to lower their energy consumption and environmental footprint by improving the pyro-system. In a calciner, AF-Fuels can reach a thermal substitution rate (TSR) of up to 80–100%. However, a kiln burner can only achieve a TSR of 50–60%. High TSR values have been provided by improvements in multi-channel burners, proper AF-Fuel feeding point setups, and various AF pre-combustion methods. Significant modeling of the calciner burner and system has also improved TSRs. However, the cement industry has encountered operational problems such as kiln coating build-up, reduced flame temperatures, higher specific heat consumption, and incomplete combustion. There is growing interest in waste substitution, a promising source of AF-Fuel that needs to be integrated into the current cement plant design to solve the calciner operational problems of the cement industry. This study discusses the latest developments and different experimental and modeling studies performed on the direct burning/co-firing of AF-Fuel in the cement industry as well as the incorporation of gasification in cement manufacturing. Based on this, a technically and environmentally improved solution is proposed. The characteristics of both approaches towards pre-calciner function and optimization are critically assessed. The many in-line cement calciner integration technologies and their various configurations for the long-term problems of cement plants are discussed. This project report also focuses on the necessity of creating appropriate calciner models for forecasting calciner production based on various AF-Fuels and their feeding positions in the calciner.
... Cement production is a major source of environmental pollution due to high energy consumption and pollutant emissions [1][2][3]. To reduce its impact, studies have focused on using waste-derived fuels and biomass, as well as oxy-fuel and oxy-coal combustion technologies. ...
... To reduce its impact, studies have focused on using waste-derived fuels and biomass, as well as oxy-fuel and oxy-coal combustion technologies. CFD modelling has been used to investigate the co-combustion of different fuels in cement rotary kiln [1][2][3][4][5][6][7][8]. ...
... Waste materials have also been used as alternative fuels in cement rotary kilns, due to the depletion of fossil fuels and an increase in their cost [4]. If thermochemical processes in clinker formation want to be modelled, a mathematical model is necessary to understand and quantify the different processes occurring inside clinker bed, particularly the homogeneous processes taking place in the freeboard of the bed of material being processed [3,4,6,7]. The impact of coating layers on the clinker production process within a rotary kiln burning both coal and Refuse Derived Fuel (RDF) was investigated in one study [7], showing that a thin coating profile increases the gas phase temperature in the kiln (due to the insulation effect) reducing free lime content of the final clinker product. ...
... Because the calculation model is distributed symmetrically, the calculation model only uses one third of the original model for model building and meshing to reduce the calculation load. [22][23][24][25] The model uses a hexahedral grid, and the area with a large velocity gradient and the inner part of the oxygen lance nozzle are refined. The number of grids in the calculation model is 3 × 10 6 . ...
Oxygen lance is the key piece of equipment for iron and steel smelting. During the entire steelmaking process, the performance of the oxygen lance determines the occurrence of decarburization, slagging, heating, and splashing. In this paper, the influence of structural and process parameters on converter steelmaking is studied using a six-nozzle staggered oxygen lance and the traditional six-nozzle oxygen lance by performing jet tests, numerical simulation, and water model experiments. The research results show that, compared with the traditional oxygen lance nozzle, a stepwise fusion of the jet streams of the staggered oxygen lance nozzles occurs, which increases the fusion distance to varying degrees, reduces the amount of splash at the furnace mouth, and increases the effective impact area. For the six-nozzle staggered oxygen lance nozzle, the most ideal structure and maximum performance are obtained at an inner nozzle angle of 14° with a flow ratio of 55% and an outer nozzle angle of 18° with a flow ratio of 45%. The results show that the fusion distance of the inner nozzle and outer nozzle is 2.1 and 2.25 m, respectively; compared to the traditional oxygen lance nozzle, the splash amount of 0.19 g at the furnace mouth is reduced to only 16%, while the effective impact area has doubled to reach a value of 0.47 m ² . With the increase in the oxygen lance position, the effective impact area of the jet of the oxygen lance nozzle on the molten pool first increases and then decreases, and the best position of the traditional and staggered oxygen lance nozzles is determined as 30.0 and 35.0–37.5 de, respectively.
... Several researchers have developed and validated kiln models as discussed further. Liedmann et al. [108] modelled the co-firing of RDF in kiln burner, focusing on RDF burnout behaviour and local heat release through CFD simulation. Out of the nine simulations performed, the base case showed a low RDF conversion rate of around 40%, with material falling onto the clinker bed. ...
Refuse-derived fuel (RDF) from municipal solid waste (MSW) is an alternative fuel (AF) partially replacing coal/petcoke in a calciner/kiln of cement plant. The maximum thermal substitution rate (TSR) achieved through RDF is 80–100% in the calciner, while it is limited to 50–60% in the kiln burner. Different AF pre-combustion technologies, advancements in multi-channel burners, and new satellite burners have supported high TSR. Extensive efforts in modelling kiln burner and calciner lead to enhance TSR. However, the cement industry faces operational issues such as incomplete combustion, increased specific heat consumption, reduced flame temperature, and kiln coating buildup. There is an interest in RDF gasification, a promising alternative to eliminate the operational issues of the cement industry, which needs to be integrated with the existing cement plant. The article reviews the integration of gasification in cement production and various experimental and modelling studies of the direct firing of AF/RDF in the kiln/calciner. The features and technology status of both approaches are compared. The different gasification integration technologies with varied configurations for cement plant calciner are highlighted. The article emphasizes the need to develop suitable calciner/kiln-gasifier models for predicting calciner output based on different RDFs.
Graphical Abstract
... Many chemical reactions and complex phase transformations occur inside the RCK due to simultaneous processes not well understood [14,15]. Over time, various models have been used to describe this behavior [4,[16][17][18][19][20][21]. ...
Los hornos rotatorios son ampliamente utilizados en la industria del cemento, dentro de este tipo de equipos industriales ocurren reacciones químicas mientras la materia prima se mueve en el interior del horno. El perfil de temperatura en el interior del horno y el tiempo de permanencia son dos parámetros importantes para controlar la calidad del cemento, así como el tipo y la calidad de las materias primas utilizadas para formular el cemento. La fuente de energía es la mezcla de gases de combustión que viajan en contracorriente. En este estudio se empleó el software de CFD Ansys Fluent® para analizar el proceso de combustión dentro del horno rotatorio y su interconexión con la cámara de humo. El dominio virtual del horno se dividió en pequeños volúmenes de control interconectados; para cada uno se aplicaron las ecuaciones de conservación de materia y energía y las reacciones químicas de combustión para estimar el desempeño del horno rotatorio de cemento. En este trabajo se estudia la fluidodinámica dentro del horno cementero considerando el perfil de temperatura y velocidades de los gases, así como la pérdida de energía a través de las paredes del horno. El modelo Euleriano-lagrangeano de Revista Internacional de Investigación e Innovación Tecnológica Página principal: www.riiit.com.mx Vol. 9, No. 53 Noviembre-Diciembre 2021 28 combustión en estado estable desarrollado se utilizó para simular el uso de lodos de depuradora y biogás como combustibles alternativos para la producción de cemento, resultando ser una herramienta con potencial para encontrar el efecto térmico de la implementación de mezclas de combustibles alternativos con baja y alta liberación de energía en el horno rotatorio en estudio. Se presenta una comparación entre productos de combustión estimados por el modelo y valores reales obtenidos del proceso. Los resultados se limitan a las condiciones del horno cementero en estudio. El uso de herramientas de modelado y simulación computacional son elementos clave para mejorar el desempeño de la industria cementera. Palabras clave: cemento, CFD, combustión de carbón, horno rotatorio, lodos depuradora, biogas. Abstract Rotary kilns are widely used for the cement industry; into this kind of industrial ovens occurs chemical reactions while raw material moves through the kiln shell. Temperature profile inside the Kiln shell and permanence time are two critical parameters to control the cement quality, as well as the type and quality of raw materials to formulate the cement. The energy source is from the combustion gases traveled counter flow. In this study a CFD software Ansys Fluent was used to analyze the combustion process inside the rotatory kiln and its interconnection with the smoke chamber. The virtual domain of the kiln was divided into small interconnected volumes as "control volumes"; the conservation equations for matter and energy and the combustion chemical reactions were applied to each "control volumes" to estimate the performance of the rotatory cement kiln. In this work the fluid dynamics inside the kiln is studied considering the temperature and gases velocity profile, as well as the loss energy trough the kiln walls. The steady state Eulerian-Lagrangean combustion model developed was used to simulate the use of sewage sludge and biogas as alternative fuels for cement production and proved to be a tool with the potential to find the thermal effect of the implementation of alternative fuel blends with low and high energy release in a rotary kiln. A comparison is presented between combustion products estimated and real values obtained from the process. The results are limited to the conditions of the kiln studied. The use of modeling tools and computational simulation are crucial elements to improve the performance of the cement industry.
... In this work, the oxygen lance nozzle was modeled based on the Cartesian coordinate system. Since the nozzles are distributed symmetrically, the calculation domain was set to consider only one-third of the entire model for the six-hole oxygen lance and one-fifth of the entire model for the five-hole oxygen lance to simplify the calculation and increase the convergence speed [15][16][17][18]; the model mainly includes two Laval nozzles and a sufficiently large space. e latter consists of a segment of one-third of a cylinder with a radius of 1.2 m and a height of 3 m. ...
The oxygen lance is a piece of special equipment in the converter steelmaking process for blowing oxygen into the molten steel. After more than 80 years of development, the structure and function of the oxygen lance have undergone many changes. In this paper, based on the theory of hydrodynamics, the jet behavior characteristics of a dual-structure oxygen lance for the converter are determined and optimized by CFD simulations and compared with those of the traditional-structure oxygen lance. The research results show that multiple jets deflect to the central axis of the oxygen lance during movement and the inclination angle of the nozzle holes influences the jet deflection. A decrease in the nozzle hole angle results in an increase in the mutual suction between the streams. With the increasing flow rate through the large holes in the new dual-structure oxygen lance, the dynamic radial pressure increases at the middle of the jet. The jet flow characteristics of the new dual-structure oxygen lance are better than those of the traditional oxygen lance. Its impact on the molten pool includes greater momentum, a larger impact area, and a more uniform and powerful stirring of the molten pool. A nozzle angle of 14° combined with a flow rate ratio of 65% and a nozzle angle of 17° combined with a flow rate ratio of 35% are the optimal parameters for the new dual-structure oxygen lance.
1. Introduction
The oxygen lance is an essential piece of equipment in the converter steelmaking process and has been continuously developed since the invention of this process. As the continuous increase of the converter capacity requires larger amounts of oxygen for the smelting reaction, considerable research on the optimization of the oxygen lance structure has been conducted [1–3]. The converter oxygen lance has evolved from a structure with a single hole to three holes and to the current five holes and six holes [4, 5]. The development of oxygen lances includes not only the increase in the number of nozzle holes but also the continuous changes in their diameter and inclination angle to adapt to converters with increasing capacity [6–8]. Cao et al. [9] investigated the highly complex interaction process inside an 80 t converter by a cold model experiment and the corresponding numerical simulation. Nordquist et al. [10, 11] focused their research on the top-blown water model and demonstrated that the nozzle diameter, lance height, aspect ratio, and gas flow rate influence the penetration depth and the swirl phenomena. Liu et al. [12] investigated the jet behavior of interlaced multiple nozzles and the impingement of multiple jets onto the surface of the molten metal bath in a steelmaking converter. The interlaced jet hydrodynamic behaviors such as jet profile, coalescence characteristics, dynamic parameter distributions, penetration depth, and impact area, as well as the time-dependent evolution of the liquid bath are discussed. Wang and Jia et al. [13, 14] investigated the dynamic characteristics of supersonic double-parameter jets and their interaction with the molten pool. The effects of jet inclination angles and gas flow ratios on gas intensity, coalescence characteristics, and dynamic parameter distributions were discussed. Problems of the currently used traditional-structure oxygen lances include insufficient stirring capacity and low oxygen-supply ability. It has become increasingly difficult to change the traditional oxygen lance structure to optimize the jet behavior and improve the steelmaking process. To address these problems, based on the theory of hydrodynamics, the jet behavior characteristics of the dual-structure oxygen lance for the converter are determined and optimized by CFD simulations and compared with those of the traditional-structure oxygen lance. The method of optimizing jet behavior characteristics by changing structural parameters can provide directions for the development of converter oxygen lances.
2. Simulation Method and Conditions
2.1. Geometric Model and Simulation of the Oxygen Lance
Based on the structural parameters of the traditional five-hole oxygen lance for the 260-t converter industry and the traditional six-hole oxygen lance, a novel dual-structure six-hole oxygen lance nozzle is designed. The two structures are characterized by different flow rates, inclination angles, and center distance designs. The nozzle holes are staggered. The nozzle structure of the oxygen lance is shown in Figure 1. In this figure, D represents the outer diameter of the oxygen lance, α1 and α2 denote the inclination angle between the large and small holes and the central axis, respectively, L1 and L2 correspond to the distance between the large and small holes and the central axis, respectively, d11 and d21 represent the inlet diameters of the large and small holes, d12 and d22 denote the throat diameters of the large and small holes, and d13 and d23 correspond to the exit diameter of the large and small holes. The specific size parameters are shown in Table 1. Cases 1 to 8 refer to the dual-structure oxygen lance nozzle, and cases 9 and 10 to the traditional-structure oxygen lance nozzle. The identifier of a dual-structure oxygen lance nozzle consists of the values for the large-hole angle, small-hole angle, and the proportion of large-hole flow, while the identifier of a traditional-structure oxygen lance nozzle contains the value of the angle and the number of spray holes.
(a)
... In this work, the above-mentioned oxygen lance nozzle scheme was modeled based on the Cartesian coordinate system. Since the six-hole oxygen lance nozzles are distributed symmetrically, in order to simplify the calculation and increase the convergence speed, the calculation domain was set as to consider only one-third of the entire model; [16][17][18][19] the model mainly includes two Laval nozzles and a sufficiently large space. The latter consists of a 1/3 cylinder with a radius of 2 m and a height of 3.5 m. ...
An oxygen lance represents a commonly used piece of equipment in converter steelmaking. Its jet characteristics and the interaction of these jets with the molten pool will directly affect the smelting effect and blowing time. This work investigates the oxygen lance of a 260 t converter in a steel plant. Through numerical simulations and physical experiments, the influence of the operating pressure, ambient temperature, top-blowing flow, lance position, and other operating parameters on the jet flow characteristics of the oxygen lance is studied. Furthermore, the oxygen lance interaction with the molten pool is analyzed. The results show that the operating pressure has little effect on the fusion distance of the jet; however, its size determines the impact force of the jet on the molten pool. In addition, the high-temperature environment causes the density of the jet fluid to decrease, the jet attenuation speed to decrease, the jet fusion speed to increase, and the degree of fusion to attenuate. Furthermore, the spray volume of the furnace mouth continues to increase upon increasing the top-blowing flow; by contrast, the spray volume first increases and then decreases as the gun position increases. The maximum spray volume of the furnace mouth occurs at the 35-de gun position; the diameter of the impact pit varies with the gun position. As the top-blowing flow increases, the depth of the impact pit increases with the decrease in the gun position and the increase in the top-blowing flow. The mixing time gradually reduces with the increase in the top-blowing flow and the decrease in the gun position.
... Meanwhile, the chemical content of the RDF ash is similar to that of silicate cement, so the use of RDF in the cement kilns cannot affect the cement quality. [6][7][8] At present, RDF has been used during the cement production, but the properties of RDF offer a fertile field for study. ...
With the help of pyrolysis gas chromatography–mass spectrometry (Py-GC-MS), high resolution thermogravimetric instrument and CHONS elemental analyzer, the pyrolysis products of refuse-derived fuel (RDF) in different months in one year are studied in this article. And the three kinds of RDF are denoted as A, B and C, respectively. High resolution thermogravimetric tests showed that obvious chemical reactions took place for RDF samples in the temperature ranges of 433–623 K, 623–773 K and 773–1173 K. RDF samples were tested by Py-GC-MS under 623 K, 773 K or 1173 K while He was as the balance gas, and the qualitative and semi-quantitative analysis results were obtained by introducing pyrolysis products into gas chromatography–mass spectrometry. According to the Py-GC-MS tests, the kinds and contents of pyrolysis products increased with the rising of the temperature, and RDF pyrolysis finished prior to 1173 K. Primary discussion for pyrolysis mechanism is progressed according to main pyrolysis products and the change of their relative contents, which can be used to provide the significant fundamental research of homogeneous reduction for NO x removal.
