Kiln Plant Research Articles

Comprehensive Analysis of Industrial Solid-Waste-to-Energy by Refuse-Derived Fuel Technology: A Case Study in Shanghai

The prolific generation of industrial solid waste (ISW) in China, coupled with its complex composition, presents significant challenges due to exceeding environmental capacity. Identifying an appropriate approach to maximize the use of ISW, particularly low-value industrial solid waste (LISW), is crucial for addressing environmental issues. This study explores the potential of converting LISW into refuse-derived fuel (RDF), an energy-rich precursor, as a promising method for disposal and reutilization. The advantages of RDF lie primarily in two key areas: management and technology. Regulatory aspects cover principles governing RDF feedstock preparation, storage and transportation requirements, and pollutant emission regulations. Technical considerations include pretreatment techniques, additive selection, and analyzing RDF as a substitute for fossil fuels. To assess the effectiveness of RDF technology in harnessing the remaining energy from LISW, this paper provides an overview of relevant national laws and regulations concerning incineration plants, guiding the utilization of RDF in such facilities. Additionally, using Shanghai as a case study, we evaluate the ISW situation, domestic waste incineration plants, and cement kiln plants to identify potential scenarios for RDF application in future energy systems. Our findings suggest that LISW holds significant potential as a power plant fuel, particularly when blended with higher calorific value materials to produce RDF particles with exceptional combustion performance, density, and storage characteristics.

Innovative Power Generation Technologies for Improved Household Energy Delivery and Sustainable Future: Classical Solutions from ENEA Research Centre, Trisaia Italy

The present communication is focused predominantly on important R&D solutions relevant to renewable energy technologies covering the following: (i) Innovative heat transfer fluid and thermal storage technology based on a molten salt mixture developed by ENEA for large-scale heat storage. The system uses a parabolic trough collector, compared with diathermic oil, which allows higher operating temperature, resulting in significant benefits to the plant’s operation, safety and the environment. (ii) The world’s first solar disk powered by air micro turbine developed by ENEA. (iii) An innovative steam-explosion prototype plant installed at ENEA for the pre-treatment of lignocellulosic biomass and the fractionation of bio components to generate ethanol from lignocellulosic material using hemicellulose and lignin. (iv) The production of hydrogen-enriched biogas using steam as the gasification agent, which helps in obtaining nearly nitrogen-free product gas and with a high calorific value of around 12 MJ/Nm3 dry gas and a high percentage of hydrogen (up to 55%) while using steam as the gasifying agent in the presence of a catalyst. (v) A rotary kiln plant, with the main purpose being to develop and optimize a thermo-chemical process to convert used rubber tyres so as to recover material and energy, as well as other solid products, with high value-added “Activated carbon” and synthesis gas.

Water Hyacinth (Eichhornia crassipes) As a Possible Alternative Energy Source: A Case Study for INSEE Cement Manufacturing Plant in Puttalam, Sri Lanka

Cement manufacturing is typically energy-intensive process and currently using alternative fuels partially or totally to replace fossil fuels to reduce the energy and environmental costs. Biomass is one of the main alternative fuel utilized by the cement industry with the potential to replace up to 20% of total energy demand. Water hyacinth (WH) is a problematic invasive alien species in aquatic ecosystems of all climatic zones in Sri Lanka. Because of it is non-edible, rapid growth, and freely available in larger quantities, WH has the potential to be used as biomass energy. Several countries have been studied for WH as feedstock for bioenergy production while physical and chemical composition of WH biomass has been tested by many researchers. However, biomass physiochemical properties may be varied by different place and conditions and there is no significant study for industrial application of WH biomass to burn in cement plant kiln as alternative energy source. Thus, this study aimed to elucidate the potential of WH biomass as an alternative energy source for the INSEE cement plant in Puttalam. The study was conducted in three selected reservoirs namely, Tabbowa reservoir (TR), Murukkuwatawana reservoir (MR), and Nawadankulama reservoir (NR) located in Puttalam district Northwestern province of Sri Lanka. The quantity of fresh and dry WH biomass was estimated with the WH covered area and fresh and dry weights of WH in unit area.WH covered area of in each reservoir during 2020 and 2021 was digitized directly in Google earth satellite images using Google Earth Pro software with help of visual interpretation techniques. WH biomass per unit area were measured by the subjective sampling method. WH samples from each reservoir were collected for analyzing biomass, and to determine the fuel characteristics such as net calorific value (NCV), Chlorine and Sulfur content, moisture, volatile matter, fixed carbon, and ash content. According to the results, the fresh WH biomass was recorded as 692.62, 389.85, 23.58 tons in 2020 and 3570.82, 584.53, 33.31 tons in 2021 in the TR, MR, and NR respectively, while the dry WH biomass was recorded as 41.65, 24.65, 1.31 tons in 2020 and 214.74, 36.96, 1.85 tons in 2021 in the TR, MR, and NR respectively. NCV of the WH composite sample was 12.02 MJ/kg. Moisture content, ash content, chlorine and sulfur content were recorded as 13.56%, 10.95%, 1.06%, and 0.14% respectively. Except for chlorine content, other parameters agreed with the acceptable limits for using WH as an alternative energy source for cement industry. To replace 1 ton of coal, 2.2 tons of dry WH were required from 35 tons of fresh WH biomass while to produce 1 ton of clinker, 0.32 tons of dry WH were required from 5.2 tons of fresh WH biomass. Since relatively large quantities are freely available and with high volatile content and calorific value, WH is suitable as an alternative energy source for cement industry. However, economic feasibility should be studied prior to the commercial application.
 Keywords: Alternative fuel, Biomass, Water hyacinth, Calorific value

Experimental assessment of an indirect method to measure the post-combustion flue gas flow rate in waste-to-energy plant based on multi-point measurements

In waste-to-energy plants, the determination of the flue gas flow rate in the post-combustion section is of the utmost importance, e.g., for the verification of the compliance to the minimum residence time requirements (tres>2s) or for the control of flue gas treatment reactant injection, but the harsh conditions (high temperature and content of pollutants) do not allow for a direct measurement. The present work reports an experimental assessment of an indirect approach to estimate the flue gas flow rate in the post-combustion section of a rotary kiln plant with reduced uncertainty. This method consists on the direct measurement of the flow rate at a “colder” section of the plant (the boiler outlet) combined to the simultaneous measurements of flue gas composition measurements upstream and downstream of the boiler. From these measurements it is then possible to determine the mass of false air and to retrieve the actual flue gas flow-rate in the post-combustion chamber. A massive experimental campaign has been conducted at a full-scale medical waste incinerator, in which flue gas flow rate was estimated at different waste loads and ambient conditions. The results show that the percentage of false air can be significant and simply neglecting it can lead to substantial under-performance of the plant. Issues related to the practical implementation of the methods are illustrated in detail and the possibility to extend the methodology towards an online determination of post-combustion flue gas flow rate is discussed.

Experimental investigation on utilization of distillery sludge mixed with coal as a Low-grade fuel in brick kiln industry and product analysis

Energy demand has been considerably increasing since the last few decades. This trend is expected to continue in the coming years and hence alternative energy sources look more attractive and practically feasible. Distillery sludge has emerged as an alternative promising renewable energy source due to its high calorific value, carbon content and volatile matter. Distillery sludge after mixing with coal in different proportion (3:1, 3:2, 1:1 and 1:3) was used in the brick kiln industry as a combustion fuel for the different time of baking. The study results showed that 60 % of coal mixed with 40 % sludge i.e. 3:2 ratio with 4 h baking time was found suitable for the operation of brick kiln plant due to optimum compressive strength (5.35 MPa) and water absorption (17.09 %). On analyzing the flue gas emission characteristics during the operation value of PM (482 mg/Nm3) for coal mixed sludge at the ratio of 3:2, the flue gas emission values were within the prescribed limit of regulatory authority. The other mineralogical properties of bottom ash indicated that it is rich in calcium sulphate and aluminates which can further be used in cement and construction industries. It is recommended that coal mixed sludge in the ratio 3:2 may be utilized as a fuel for partial replacement of coal in the brick kiln industry.

Analysis of the heavy metals (As, Pb, Cu, Zn) by leaching and sequential extraction procedure from a municipal solid waste incinerator fly ash co-processing cement kiln plant.

The municipal solid waste incineration (MSWI) fly ash has been a major problem with the rapid development of the cities in China. And the cement rotary kiln co-processing technique is accepted as an effective method to dispose detrimental heavy metals in MSWI fly ash. This study focused on presented the total leaching content and the morphological distribution of the heavy metals in cement solid samples doped with MSWI fly ash. These samples were collected from a MSWI fly ash co-processing cement rotary kiln plant. The leaching test and the sequential extraction procedure were adopted to measure the migration characteristic of As, Pb, Cu, and Zn. In addition, the leachability of clinker samples under different simulated environmental conditions was also detected to analyze the security of the cement product doped with MSWI fly ash. This work demonstrates the feasibility of the cement rotary kiln MSWI fly ash co-processing technique and provides a scientific guidance to related plant.

Experimental study on strength and endurance performance of burnt clay bricks incorporating marble waste

ABSTRACT Burnt clay brick is one of the oldest and most widely used construction materials. The production of burnt clay bricks with various waste materials can help reduce the environmental hazards and improve brick performance at low manufacturing costs, thereby leading towards more sustainable construction. This research aimed to evaluate the effect of using waste marble powder (WMP) in varying percentages, i.e., 0, 3, 6, 9, 12, and 15%, by weight of clay in an industrial brick kiln plant. A range of mechanical and durability tests was performed on the raw material, i.e., clay, WMP, and bricks, to quantify their performance. It was observed that incorporation of WMP resulted in a reduced unit weight of the bricks, making the structure lighter in weight. Moreover, compressive strength and freeze thaw test results for all the brick specimens and sulfate tests for the brick specimens with 12% WMP addition were within the Building Code of Pakistan, and ASTM C67 prescribed limits. Finally, it can be concluded that WMP up to 12% by weight of clay can be incorporated to prepare burnt clay bricks, which can reduce the environmental waste to achieve sustainability and economy for the brick industry.

Thermal treatment of carbon-fibre-reinforced polymers (Part 2: Energy recovery and feedstock recycling).

The use of carbon fibre (CF)-reinforced plastics has grown significantly in recent years, and new areas of application have been and are being developed. As a result, the amount of non-recyclable waste containing CF is also rising. There are currently no treatment methods for this type of waste. Within this project different approaches for the treatment of waste containing CF were investigated. Main subject of the research project were large-scale investigations on treatment possibilities and limits of waste containing CF in high temperature processes, with focus on the investigation of process-specific residues and possible fibre emission. The results showed that the two conventional thermal waste treatment concepts with grate and rotary kiln firing systems are not suitable for a complete oxidation of CFs due to the insufficient process conditions (temperature and dwell time). The CFs were mainly discharged via the bottom ash/slag. Due to the partial decomposition during thermal treatment, World Health Organization (WHO) fibres occurred in low concentrations. The tests run in the cement kiln plant have shown the necessity of comminution for waste containing CF. With respect to the short testing times and moderate quantities of inserted CF, a final evaluation of the suitability of this disposal path was not possible. The use of specially processed waste containing CF (carbon-fibre-reinforced plastic (CFRP) pellets) as a carbon substitute in calcium carbide production led to high carbon conversion rates. In the unburned furnace dust, which is marketed as a by-product of the process, CFs in relevant quantities could be detected.

Knowledge Criticality Assessment and Codification Framework for Major Maintenance Activities: A Case Study of Cement Rotary Kiln Plant

Maintenance experts involved in managing major maintenance activities such as; Major overhauls, outages, shutdowns and turnarounds (MoOSTs) are constantly faced with uncertainties during the planning and/or execution phases, which often stretches beyond the organisation’s standard operating procedures and require the intervention of staff expertise. This underpins a need to complement and sustain existing efforts in managing uncertainties in MoOSTs through the transformation of knowledgeable actions generated from experts’ tacit-based knowledge. However, a vital approach to achieve such transformation is by prioritising maintenance activities during MoOSTs. Two methods for prioritising maintenance activities were adopted in this study; one involved a traditional qualitative method for task criticality assessment. The other, a quantitative method, utilised a Fuzzy inference system, mapping membership functions of two crisp inputs and output accompanied by If-Then rules specifically developed for this study. Prior information from a 5-year quantitative dataset was obtained from a case study with appreciable frequency for performing MoOSTs; in this case, a Rotary Kiln system (RKS) was utilised in demonstrating practical applicability. The selection of the two methods was informed by their perceived suitability to adequately analyse the available dataset. Results and analysis of the two methods indicated that the obtained Fuzzy criticality numbers were more sensitive and capable of examining the degree of changes to membership functions. However, the usefulness of the traditional qualitative method as a complementary approach lies in its ability to provide a baseline for informing expert opinions, which are critical in developing specific If-Then rules for the Fuzzy inference system.

Enhancing the efficiency of a cement plant kiln using modified alternative fuel

The high combustion performance, combined with reduced emissions of harmful substances, depend on the use of alternative fuels (AFs). In this study, an innovative waste management protocol was applied to a cement plant, replacing coal with a mix of rice husk and refuse-derived fuel (RDF, 0 %–5 %). The effects of this replacement on the setting time and compressive strength of clinker were studied, and nitric oxide (NOx) and sulfuric oxide (SOx) emissions were evaluated. The results revealed that coal use could be reduced by 17 % and the addition of the RDF and rice husk mix effectively reduced electrical power consumption by 13 %. Furthermore, NOx and SOx emissions decreased. Thus, these findings demonstrate the impacts of AFs on improvement of combustion, pollution emissions and the generation of financial growth sources. This study contributes to the optimization of renewable energy applications in the cement industry. Future studies should focus on further reducing emissions and addressing challenges associated with climate change.

Emission and Heavy Metal Content Characteristic of Densified Refused Derived Fuels of Oil Sludge and Biomass Combination as an Alternative Fuel for Cement Plant

Hazardous Waste such Oil Sludge combined with biomass (coconut shell and rice husk) was utilized as an alternative fuel in cement plant in form of Densified-Refused Derived Fuel (D-RDF). D-RDF were Co-Processed with primary fuel into Rotary Kiln in order to reduce usage of fossil fuel and eliminate the hazardous waste by thermal treatment, meanwhile to recover the energy contained in the D-RDF, the utilization of these waste are expected without causing adverse effect into the environment. Co-Processing of D-RDF as alternative fuels into cement plant kiln must follow the regulation applied in Indonesian Environment and Forestry Minister regulation 19/2017 and European Union for Responsible Incineration and Treatment of Special Waste (EURITS). Based on previous research, D-RDF composition of oil sludge and biomass at 1:1 ratio with 5% starch addition was choose as they give best calorific value at 6000 kcal/kg. The objective of these research are to observe the emission caused by the utilization of these D-RDF and potential effect into cement or clinker product. The result show NOx and CO value are meet the standard requirement by government regulation meanwhile SO2 value which are 1251 mg/Nm3 and 1500 mg/Nm3, over the regulation standard which is 650 mg/Nm3. This issue could be overcome in the plant with pre treatment of D-RDF and utilization of Bag House Filter or Electostatic Precipitator before release the emission to the stack. Trace element analysis of D-RDF ashes (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Se, Sn dan Zn) show the result are meet the EURITS regulation, which mean utilization of D-RDF will not give quality deffect to cement or clinker product.

Development and Evaluation of Mathematical Model based Region of Interest for Rotary kiln Burning Zone Temperature in Cement Industry by Digital Image Processing

Industrial processes particularly cement manufacturing unit consumes about 7% of total fuel used in the industry and hence there are strenuous efforts to reduce the fuels and lower the production costs by applying Optimal Control Algorithms. In order to achieve these parameters in the Rotary Kiln Plant, we need to continuously monitor the temperatures of the burning zone inside the rotary kiln at Regions of Interest (ROI) in real-time. In this image processing setup a thermal camera samples the temperatures inside the kiln at a rate of 5 frames per 2 seconds. The images which are highly sensitive to red and green wavelengths provide sufficient resolution to differentiate between various burning temperatures. The present burning zone temperature measurement obtained from the radiation pyrometer is not reliable on the one hand and indicates temperature information about particular point in the burning zone on the other hand. This is inadequate for optimizing the operation the kiln where a kiln furnace camera has been already installed at the plant for watching the burning status the inside the kiln. Software will be developed to determine the temperature T, for the video captured from the camera. Presently real time video from the camera is displayed in a computer monitor at kiln control room. We will tap the video signal from the setup and the calculate the burning zone temperature at the Region of Interest utilizing real time Image Processing Technologies. The temperature signal so estimated will be validated using the radiation pyrometer signal obtained from the field. The graphical tool developed in MATLAB automatically converts the receiving color images to temperature measure by proposed algorithms and also interactively analyzes the temperatures in a neat graphical user interface, in less than 2 seconds duration. ROI can be selected by a movable and re-sizable window which acts like a probe on the kiln temperatures at this instant, then displays the summary statistics of the temperatures. The tool is extended to provide a real-time graph of average temperature in the ROI over a long time when the probe is fixed at a particular region. However, the developed temperature tool and the point burning zone temperature measured by a proposed mathematical model as like thermocouple in the plant. The results are carried out by MATLAB software and benefits will be quantified in terms of enhancement in the Production efficiency, Energy efficiency, Pollution Control and clean environment.

Air gasification of digestate and its co-gasification with residual biomass in a pilot scale rotary kiln

In this study energy recovery of digestate from a biogas plant was investigated via air gasification. Gasification tests were executed in a pilot scale rotary kiln plant having a nominal biomass feeding rate of about 20 kg/h. The equivalence ratio was varied from 0.22 to 0.39 with the goal to approach the autothermal condition. Tests were carried out for 5 h in steady state condition. Syngas composition, char and gas yields were measured. To improve the cold gas efficiency of the process, a mixture of digestate and almond shells (60:40 wt%) was gasified. Autothermal condition was reached with the mixture using equivalence ratio of 0.30 where the corresponding cold gas efficiency achieved the maximum value of 55%. The raw gas had a lower heating value of 4–5 MJ/Nm3. To evaluate possible improvements in the produced gas properties, in this work the effect of steam injection was also investigated.

Measurement of the residence time distribution of a cohesive powder in a flighted rotary kiln

The rotary kiln is an essential device in chemical and metallurgical industries, with applications in a wide range of solids manufacturing processes. In particular, in the preparation of industrial chemical catalysts, the kiln has become a popular reactor for continuous calcination of catalysts ranging from millimeter-sized extrudates to micron-sized powders. As granular and powder flow behaviors are difficult to characterize, the design and scale-up of rotary calcination processes are often performed empirically. The goal of this research is to improve the fundamental understanding of powder flow in rotary kilns to aid in optimization of the continuous calcination process. For successful calcination to occur, the residence time of the particles must exceed the time required for heating and subsequent treatment. For uniform treatment of the feed, the particles must also exhibit low axial dispersion. In this work, the mean residence time and axial dispersion coefficient for a cohesive fluid catalytic cracking powder were determined in a pilot plant kiln by measuring the residence time distribution. This study utilized a pulse test developed by Danckwerts. Results were fit to the Taylor solution of the axial dispersion model and compared to the Sullivan prediction for mean residence time. It was found that the mean residence time decreases as the feed rate, kiln incline, and rotation rate increase. It was also found that the axial dispersion coefficient increases with speed of rotation and angle of incline. However, the axial dispersion coefficient decreases as the feed rate is increased.

Assessment of the Application of a Ca-Looping Cycle for CO2 Capture in an Egyptian Cement Kiln Plant

The mathematical model of mass and heat balance around a carbonator and calciner of a calcium looping cycle for capture of CO2 has been established. Such a model has been applied to evaluate the thermal energy requirement for the capture of CO2 evolved with preheater exit gases of an Egyptian cement kiln plant. Potentials for heat recovery from the outlet heat flows of the system have been assessed. The kiln plant operates with 15% kiln gas by pass ratio; the specific heat consumption attains 3151 kJ/kg of clinker. The entire CO2 emitted from the kiln plant attains about 0.7 kg CO2/kg of clinker or 4427.6 t CO2/d CO2/d; most of this (≈ 98%) evolves with the preheater gases. For the mass ratio of absorbant/CO2 ranging from stoichiometric (1.27) to 5, 100% CO2 capture degree and zero purged flow, heat consumption in the calciner has been estimated to be in range 5629–6790 kJ/kg CO2, corresponding to 3873–4671 kJ/kg of clinker. Fuel consumption would increase by about 20% for every kg purged CaCO3. It has been estimated that heat recovery from the cycle, e.g., through cooling of the outlet gas streams from 650 or 950°C to 150°C with 70% efficiency attains 2000–3442 kJ/kg of clinker, which represents more than 73% of the fuel consumption in the calciner. The increase of efficiency for heat recovery is accompanied by much regain of heat and better fuel economy.

Co-production of cement and carbon nanotubes with a carbon negative footprint

C2CNT (CO2 to carbon nanotube) cement plants are introduced and analyzed with a significant economic incentive to eliminate current plant CO2 greenhouse gas emissions. The exhaust from partial and full oxy-fuel cement plant configurations are coupled to the inlet of a C2CNT chamber in which CO2 is transformed by electrolysis in a molten carbonate electrolyte into CNTs at a steel cathode and pure oxygen at a nickel anode that is looped back in improving cement line energy efficiency and production rate. A partial oxy-fuel process looping O2 back through the plant calcinator has been compared to a full process in which it enters through the plant kiln. The first provides easier retrofit; the second maximizes efficiency by minimizing N2 throughput. Providing an economic impetus to carbon dioxide removal, per ton CO2 avoided the C2CNT cement plant consumes $50 electricity, emits no CO2, and produces $100 cement and ∼$60,000 of CNTs.

The effect of operating conditions on the residence time distribution and axial dispersion coefficient of a cohesive powder in a rotary kiln

While continuous rotary calcination is a widely used thermal treatment in large-scale catalyst manufacturing, the process's heat and mass transfer mechanisms remain a challenge to characterize and to predict. Thus, the goal of this research is to improve fundamental understanding of rotary calcination to aid in the creation of a scientific methodology for process design and scale-up. For successful calcination to occur, the residence time of the particles must exceed the time required for heating and calcination at a set temperature. The optimal residence time therefore depends on both of these competing time scales, each of which is function of feed material properties, kiln geometry and kiln operating conditions. For uniform treatment of the feed, the particles must also exhibit low axial dispersion. In this work, the residence time distribution and axial dispersion coefficient for a dry cohesive fluid cracking catalyst powder were measured in a pilot plant kiln using a tracer study developed by Danckwerts. Results were successfully matched to the Taylor fit of the axial dispersion model and the Sullivan prediction for mean residence time. It was found that an increase in feed rate, kiln incline and rotary speed decreased mean residence time and overall axial dispersion. Such results have been established previously for free-flowing material like millimeter-sized extrudates, but have not been previously reported for the cohesive powders such as the one used in our work. As in free-flowing material, the axial dispersion coefficient was found to vary with kiln conditions. The values of the axial dispersion coefficients were lower for the powder than for free-flowing material, showing a dependency of axial dispersion on material properties as well as bulk flow behavior.

Manufacturing of sustainable clay bricks: Utilization of waste sugarcane bagasse and rice husk ashes

Burnt clay brick is one of the major and widely used building unit in masonry construction around the globe. The manufacturing of burnt clay bricks using waste materials can minimize the environmental overburden caused by waste deposition on open landfills and would also improve the brick performance at low production cost leading to more sustainable construction. This study aims to evaluate the effect of the waste addition produced from two major crops: sugarcane and rice in clay bricks manufacturing. In this study, sugarcane bagasse ash (SBA) and rice husk ash (RHA) were collected locally from a sugar mill and bull’s trench kiln, respectively. Brick specimens were manufactured at an industrial brick kiln plant using various dosages (5%, 10% and 15% by clay weight) of SBA and RHA. Mechanical and durability properties of these bricks were studied. It was observed that clay bricks incorporating SBA and RHA exhibited lower compressive strength compared to that of clay bricks without SBA and RHA. However, compressive strength of bricks with 5% of SBA and RHA satisfied the Pakistan Building Code requirements (i.e. >5MPa). Scanning electron microscopy (SEM) analysis confirms the porous microstructure of the brick specimens incorporating SBA and RHA, which resulted into lesser unit weight leading to lighter and economical structures. Furthermore, resistance against efflorescence was improved in all the tested bricks incorporating SBA and RHA. Based on this study, it can be concluded that the brick specimens incorporating lower dosage of SBA and RHA (i.e. 5% by clay weight) will not only relieve the environmental burden but also result into a more sustainable and economical construction.

For Waste to Energy, Assessment of Fluff Type Solid Refuse Fuel by Thermal Characteristics Analyses

Waste to energy could be one of the greatest sources of renewable energy in Korea, especially municipal solid waste as it has high heat recovery rate and high energy density. Various types of waste to energy technology exist, including refining of waste oil, plastic pyrolysis, recovery of waste heat and SRF (Solid Refuse Fuel). Main advantages of waste to energy are commercialization in a short period and treatment of waste alongside energy recovery.SRF could be made from various source including MSW (Municipal Solid Waste), plastic, wood etc.SRF is also used as an auxiliary fuel of fossil fuel for cement kiln plants. Depending on theshape SRF could be fluff type and pellet type. Manufacturing processes of fluff type SRF are composed to screening and drying stages. In this study, an assessment on fluff type SRF made of MSW was conducted by thermal characteristics analyses. Thermal characteristics analyses include elementary analysis, TG (Thermogravimetry) analysis, HHV (Higher Heating Value) measurement and proximate analysis. For comparison, SRF with other fuel samples such as biomass, and coal were selected and we evaluated to determine whether SRF is good as fuel or not. In this experiment, representative of fossil fuel was bituminous coal and representative of biomass was EFB (Empty Fruit Bunch). Results of different characteristics analyses of fluff type SRF compared to other fuels, the feasibility of fluff type SRF to use as alternative fuels by waste to energy technology was good enough.

Rice Husk as a Substitute Fuel in Cement Kiln Plant

A simple mathematical model of heat balance was applied to a cement kiln plant with a precalciner to estimate the effect of using rice husk as a substitute fuel for natural gas on specific heat consumption. Effects of the husk ash on the characteristics of the raw mix and clinker of ordinary Portland cement were also evaluated. Referring to Egyptian kiln plants data, it was found that the weight of rice husk required to supply fuel heat in the precalciner represented about 11-13% of the raw mix weight and about 90% of the total fuel weight (natural gas + husk). Specific heat consumption increased by about 3.7%, and the amount of combustion flue gases increased by about 20% when natural gas was completely substituted by rice husk. The use of rice husk as a substitute fuel in a cement kiln plant was accompanied by a marked decrease of lime saturation factor of the raw mix, a drastic decrease of tricalcium silicate and an increase of dicalcium silicate in the clinker. This data can provide the basis for the formation of a new type of cement such as high belite cement. The raw mix design was adjusted using pyrite as a correcting factor to keep the characteristics of the raw mix and the clinker similar to the factory data. KeywordsAlternative Fuel; Rice Husk; Natural Gas; Raw Mix Design; Clinker Mineral Composition; Raw Mix Parameters; Specific Heat Consumption Nomenclature ms1 = mass of the inlet raw mix to the preheater (kg) hs1 = specific enthalpy of the inlet raw mix to the preheater (kJ/kg) mf = mass of the fuel (kg) hf = low calorific value of the fuel (kJ/kg) hu = specific enthalpy of the fuel (kJ/kg) mA3 = mass of tertiary air from the cooler to the calciner (kg) hA3 = specific enthalpy of tertiary air from the cooler to the calciner (kJ/kg) mA5 = mass of secondary air from the precooling zone in the kiln (kg) hA5 = specific enthalpy of secondary air from the precooling zone (kJ/kg) mA6 = mass of secondary air from the cooler to the kiln (kg) hA6 = specific enthalpy of secondary air from the cooler to the kiln (kJ/kg) mG1 = mass of outlet flue gas from the preheater (kg) hG1 = specific enthalpy of outlet flue gas from the preheater (kJ/kg) ms6 = mass of clinker leaving the firing zone to the cooler (kg) hs6 = specific enthalpy of clinker leaving the firing zone (kJ/kg)  HR.c, HR.K = heat of reactions in the calciner and the kiln, respectively (kJ) Qw.p.c, Qw.k, Qw.c. = wall heat losses from the preheatercalciner, kiln, and cooler, respectively (kJ) Vaf = theoretical amount of fuel combustion air (Nm /kg fuel) Vgf = theoretical amount of fuel combustion gases (Nm /kg fuel)  = excess air factor for fuel combustion MCO2 = mass of evolved CO2 from calcination Cpg, Cpa = specific heat of flue gases and air, respectively (kJ/Nm 3 C) Tg, Ta = temperature of flue gas and combustion air, respectively ( C) h.f.o. = heavy fuel oil cli. = clinker LSF = lime saturation factor SIM = silica modulus AM = alumina modulus C3S = tricalcium silicate C2S = dicalcium silicate International Journal of Energy Engineering Apr. 2015, Vol. 5 Iss. 2, PP. 16-27 17 DOI: 10.5963/IJEE0502001 C3A = tricalcium aluminate C4AF = tetracalcium aluminate ferrite Borders of the heat balance zones, as shown in Fig. 2: [1] [2] = preheating zone [2] [3] = precalciner zone [3] [4] = bottom stage cyclone [4] [5] = heating zone of the rotary kiln [5] [6] = precooling zone [6] [7] = cooler