Boiler Surface Research Articles

Application of Torrefaction for Improved Fuel Properties of Sunflower Husks

Sunflower husk (SFH) contributes 45–60% of the total sunflower seed weight and is a by-product of the sunflower oil industry. Among other elements, SFH ash contains K, Na, Ca and Mg. These elements cause rapid growth of ash deposits on convective heating surfaces of the boiler, resulting in reduced efficiency. The aim of this paper is to examine the possibility of producing quality fuel from SFH by its pretreatment with the technique of torrefaction in a fluidized bed in superheated water vapor. Continuous monitoring of the innovative SFH torrefaction process allowed for the determination of optimal process durations. SFH could be converted into a biofuel, having high calorific value and suitable characteristics for co-combustion with coal. Furthermore, the torrefaction in a fluidized bed of superheated water vapor allowed for a 6-fold reduction in the required process duration in comparison with data reported from the literature for the process of torrefaction in a dense bed, along with a 3-fold reduction in the chlorine content in SFH ash. These effects are beneficial to resolve the problem of corrosion on convective heating surfaces of boilers. However, torrefaction in superheated water vapor did not significantly reduce the content of alkaline and alkaline-earth elements in SFH ash. Still, this issue may be alleviated by significantly increasing the duration of SFH pretreatment.

Increasing the Economic Efficiency of Marine Power Plants Using Waste Heat Boilers with Controlled Flow Separation

Abstract Heat recovery of exhaust gases from main and auxiliary marine diesel engines is an effective way to improve the technical and economic parameters of marine power plants. Improvements in engine efficiency necessitate an increase in the weight-size parameters of the waste heat boilers, which makes it difficult to recover heat. Intensification of the heat transfer process is considered to be an effective way to reduce these indicators. By utilising mathematical modelling, this paper shows the effectiveness of using profiled heating surfaces of waste heat boilers for this purpose. The use of elliptical heating surfaces with a mechanism of controlled flow separation, in the form of a triangular notch, is proposed. This will reduce surface drag and increase the overall thermal-hydraulic efficiency of the heat transfer processes. It is shown that the use of such surfaces in waste heat boilers makes it possible to increase the efficiency of marine power plants in tankers with a deadweight of about 45,500 tons up to 1.5% absolute and container ships with a deadweight of about 122,000 tons up to 2.5% absolute.

Modelling of fly ash viscous deposition and slagging prediction of biomass-fired boiler

In addressing the ash melting-induced slagging on the high-temperature heating surfaces of biomass-fired boiler, a combined experimental and modelling study of biomass ash viscous deposition has been conducted. A comprehensive ash viscous deposition model based on ash fusion and viscosity characteristics and the critical velocity criterion has been proposed. The deposits of the top furnace and high-temperature superheater of a 130 t/h biomass-fired boiler have been sampled for validation, and a modelling study using ANSYS FLUENT with a user defined function (UDF) and dynamic mesh has been performed. The results show that small particles with diameter of 20 μm lead to less viscous adhesion because of faster response to temperature decrease before reaching the heating surfaces. Deposition efficiency and growth rate of deposits are positively correlated with temperature. Slagging in the top furnace area is dominated by the viscous deposition of molten ash. However, the amount of viscous deposition accounts for a low proportion (20.1 %) in the high-temperature superheater, suggesting a change of dominant slagging mechanism from viscous deposition to gaseous condensation and the subsequent capture of fly ash. The model is suitable for predicting ash melting-induced slagging in high-temperature areas of biomass boilers.

The Coal Quality CICS that Increases the Wear Resistance of Heat Exchanger Tubes

The paper discusses the threat of decommissioning of the thermal power plant (TPP) heat exchanger tubes because of erosion and develops a computer-integrated control system (COAL QUALITY CICS THAT INCREASES THE WEAR RESISTANCE OF HEAT EXCHANGER TUBES) for the process of distribution of steam coal flows with different indicators of abrasive materials content, which is based on fuzzy logic. The problem of rapid decommissioning of TPP heat exchanger, particularly abrasive damage to furnace screen tubes, economizer, superheater, etc. This may indicate a discrepancy between the expected fuel ash content and the actual one, as well as a high content of abrasive impurities in steam coal. The work aims to develop a CICS of the wear resistance of the heat exchange surface of a steam boiler of a coal-fired power plant by measuring and fuzzy control of the content of abrasive impurities in steam coal. The problems of damage to the equipment of the TPP boiler are investigated and a system for controlling the wear resistance of the surface by automatic fuzzy control of the quality of coal is developed. In order to investigate the effectiveness of the proposed fuzzy controller, the results were investigated in a specific example, in particular, during coal preparation and combustion in the furnace of a thermal power plant. The model results confirm the feasibility of the fuzzy control method for the system with different coal quality parameters.

High temperature chlorine corrosion resistance of gradient high entropy alloy coatings prepared by high-velocity-oxygen-fuel spraying

The effect of different gradient structures on the high temperature chlorine corrosion resistance of gradient high entropy alloy coating was studied to improve the service life of the heating surface of a waste-incinerated boiler. NiCrAl ceramic composite coating (NC), high entropy ceramic composite coating (HC), and gradient high entropy alloy coating (TC) were prepared on 12Cr1MoV substrate by high-velocity-oxygen-fuel spraying. The effects of morphology and microstructure of different coatings on thermal shock resistance and high temperature chlorine corrosion resistance were studied. The results indicate that the porosity of NC coating, HC coating, and TC coating decreased in turn. In the thermal shock resistance test from 800°C to room temperature, the average number of thermal shock of TC coating can reach 21. The mass change of TC coating in 650°C high temperature Cl corrosion resistance test is less than 30 mg/cm2 after 50 hours. In summary, the gradient high entropy alloy coating with HEA as the metal bonding phase can improve the density of thermal spraying gradient coating, and enhance the thermal shock resistance and high temperature Cl corrosion resistance of the coating. Based on the comprehensive on-site application results, it can be concluded that the use of high velocity oxygen flame gradient high entropy alloy coating can effectively improve the density, thermal shock resistance, and high temperature Cl corrosion resistance of the thermal spraying gradient coating on the heating surface of the boiler, and has broad application prospects.

Laser modification of heating surfaces: A new approach to reduce boiler slagging

Slagging and fouling of boilers are typical technological problems in the combustion of solid fuels (especially coal and biomass). This study proposes a novel approach based on laser texturing of the near-surface layer of steel used to make heating surfaces of coal-fired boilers. This approach is aimed at improving the resistance of metal surfaces to slagging. The formation of slag deposits on the surfaces of AISI 310 S steel modified by laser radiation has been experimentally studied. The formation of slag melt was analyzed on the surface of modified and polished steel plates during heating to 1400 °C. High-temperature heating and interaction with slag led to a change in the chemical composition of the steel. A significant increase in the chromium content (up to 47%) of the steel surface and the transformation of its texture with the formation of grains up to 2.5 µm in size were established. Laser surface treatment significantly increased the resistance of the steel to such changes and also reduced the grain size to 1.5 µm. As a result of laser modification of surfaces, the temperature of slag formation shifts to higher values (higher by 60–75 °C compared to the unmodified polished surface). The anisotropic texture (cauliflower type) contributed to a decrease in the size of the slag spreading front, and also had by self-cleaning properties from the mineral melt. The latter allows to increase the reliability and energy efficiency of boiler equipment.

An Effective Strategy for Monitoring Slagging Location and Severity on the Waterwall Surface in Operation Coal-Fired Boilers

It is of great importance to obtain the exact location and severity of slagging deposits on the waterwall surface of an operational boiler to avoid aimless soot-blowing and reduce steam consumption. In this paper, an effective waterwall surface temperature monitoring method is proposed to determine the slagging locations. It has been noted that the temperature difference of the waterwall surface before and after soot-blowing varied with the waterwall location, with more than 80 °C covered with slag and less than 20 °C found clean. According to this, a slagging temperature index was developed to describe the severity of slagging deposits on the waterwall surface. Results indicated that the process of slagging deposit growth included four stages, with the slagging temperature fluctuating in the range of about 90–110 °C in stage III, followed by a rapid drop below 60 °C in stage IV. Furthermore, a digital image monitoring system was used to validate the slag growth process and study the relationship between deposit thickness growth and area expansion. This novel approach provides automated and accurate guidance for each soot blower around the furnace, which reduces soot-blowing steam consumption and avoids serious slagging on the waterwall surface.

Environmental Risk Assessment of Hydrocarbon-Rich Sludge of a Gas Refinery Using the Integrated Approach of PMBOK Standard Risk Management and FMEA Technique: A Case Study

Background: The present study aimed to assess the potential hazards of hydrocarbon-rich gas refinery sludge from the South Pars Gas Complex-First Refinery, Iran, and to analyze how these risks could impact the project goals based on the Project Management Body of Knowledge (PMBOK) guidelines. Methods: Statistical population of this analytical, cross-sectional survey was 31 health, safety, and environment (HSE) experts from the study refinery selected by purposeful sampling. Environmental, health, safety, and technical risks were categorized and identified using the PMBOK guidelines. Delphi method and 5-point Likert scale questionnaire were employed to assess the significance of each risk. Priority one risks within each category were determined using Primavera Risk Analysis version 8.7 software. Results: Following three Delphi steps, 17 out of 77 primary risks were identified and finalized. The first rank with the highest weight corresponded to time and cost group (the risk of soil contamination via sludge stored in the burn pit due to aliphatic and aromatic hydrocarbons), human resources group (radioactive materials accumulated on the inner surfaces of pipes, valves, pumps, heat exchangers, tanks, boilers and other equipment and the risk of these materials being hazardous for human health), and quality group (failure to supply equipment and quality control systems and personal protective equipment). Conclusion: The research findings pinpointed 17 risks within various domains, encompassing time and cost, human resources, quality, contract, scope, and communication. These identified risks necessitate a comprehensive, integrated approach to risk management for effective mitigation and resolution.

Assessment of the Slagging Tendency in Power Plant Boiler Furnaces Depending on the Physical-Chemical Characteristics of Ash and Coal

The purpose of the work is to select replacing design coal possible options for low slagging potential reasons in the furnace and on adjacent heating surfaces. Solved problems: the main slagging indices (SI) are summarized, based on considering the two main parameters of the formation of ash deposits, namely viscosity and fusibility. An analysis of existing methods for assessing slagging processes of heating surfaces in steam power boilers was carried out. The scientific goal is achieved by the proposed method of ranking coals according to their slagging tendency on power boiler heating surfaces based on their physicochemical properties. The methodology is based on the slagging potential dependence of the fusibility and viscosity ash characteristics, considering the ratio of the ash percentage content to the heating value of coal. The most important result is ranking of 28 coals of various grades (subbituminous, bituminous, anthracite) burned at Russian power plants according to their tendency to form ash deposits on the furnaces of power boilers. The significance of the results obtained lies in the identification of two coal deposits, subbituminous Irsha-Borodinsky and Berezovsky in Easten Siberia and Kuznetsky bituminous in Western Siberia, which are universal during the transition to burning non-design fuel from the slagging potential point of view. The dependences of the change in ash viscosity and SI on the 2 2 3 / SiO Al O and 2 3 2 / Fe O SiO ratios in ash for Irsha-Borodinsky and Moscow region coals were under consideration. It was concluded that the value of the SI is directly proportional to the load ash content r A and could differ more by an order of magnitude for different coal.

Automated solid fuel quality control and monitoring system

The article describes the development of a computer-integrated coal quality management system that allows to increase the service life of heating surfaces in boilers of coal-fired power plants. The need for such a system arises due to erosion caused by abrasive impurities in coal, which leads to deterioration of the boiler infrastructure. Existing methods are mostly manual, time-consuming and error-prone. The aim of the work was to increase the service life of the surface wear resistance of heat exchange tubes of a steam generator of a thermal coal-fired power plant by synthesizing and analyzing a computer-integrated coal quality management system by distributing coal flows between different coal supply sources, unloading conditions and coal quality inspection from suppliers to minimize costs. To achieve this goal, a mathematical model was developed that describes the boiler unit in terms of ash flows in the form of a system of equations. A computer-integrated coal quality control system has been developed that allows to increase the service life of heating surfaces of power boilers by distributing coal flows between coal supply sources and conditions of unloading and checking the quality of coal from suppliers to minimize costs. A computational experiment was conducted to test the operation of the computer-integrated control system and confirm its effectiveness. The results proved the value of the developed computer-integrated control system for increasing the service life of the boiler unit's heating surfaces by timely responding to changes in the quality of coal from different suppliers. It was found that with a computer-integrated control system, the service life of the pipes could be more than doubled (from 3.06 years to 7.39 years). Overall, the introduction of a computer-integrated control system is a transformational solution for managing the distribution of costs between fuel and equipment repair costs. The integrated system, together with the use of mathematical modeling and computational experiments, offers a comprehensive approach to monitoring, predicting, and controlling the factors that affect the durability of heat exchanger tubes. This research makes a significant contribution to the power industry, potentially transforming maintenance and life extension practices for critical infrastructure in thermal power plants. Further researchis needed to refine the system and explore its wider applicability in different operational scenarios.

Preliminary Results of Innovative Two-Stage Torrefaction Technology Applied for Thermochemical Treatment of Sunflower Husk

This article proposes an innovative two-stage technology for biomass torrefaction generating high-quality biochar, more specifically biocoal, as solid fuel, and offering a promising solution to the challenges posed by the combustion of biomass. In particular, the higher quality of biochar as solid fuel reduces the build-up of unmanageable deposits on fired surfaces, as these deposits inhibit heat transfer and reduce the efficiency of biomass boilers. The proposed two-stage technology involves torrefaction in a hearth-type reactor at temperatures up to 250 °C, followed by a subsequent stage of cooling achieved through washing with water. The two-stage torrefaction technology is integrated within a vertical hearth reactor vessel composed of three superimposed trays serving for biomass input, torrefaction, and water washing combined with biomass cooling, respectively. Upon contact with torrefied biomass, cooling water turned into water vapor; hence, eliminating the requirement for subsequent biomass separation and drying. The system was tested on sunflower husk, and results showed a reduction in the content of problematic elements such as alkali metal chlorides or sulfur compounds in biochar ash, suggesting lower corrosion rates of convective heating surfaces of the boiler under ash sediments. It is hypothesized that, while water exited hot biomass in the form of water vapor instead of liquid water, as is typically the case in water-washing processes, a share of undesirable elements may still have been removed from biomass through vaporization, without necessitating any additional process for ash removal. Hence, the index values calculated according to the chemical analysis of biomass ash suggested that sunflower husk biochar (biocoal) resulting from the proposed two-stage torrefaction process may display fuel characteristics similar to biomasses whose combustion ash may form reduced levels of deposits on boiler surfaces. Therefore, the proposed technology holds the potential to improve solid fuel characteristics of biomass, targeting enhanced efficiency and sustainability of biomass-fired power plants.

CALCULATION OF HEAT TRANSFER INTENSITY OF GAS FUEL COMBUSTION PRODUCTS

Link for citation: Mrakin A.N., Afanaseva O.V., Kuleshov O.Yu. Calculation of heat transfer intensity of gas fuel combustion products. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 5, рр.109-115. The relevance of the research is determined by the modern trend in the field of thermal power engineering and heat engineering for the transition from traditional gaseous fuel (methane) to the use of hydrogen, methane-hydrogen mixtures, as well as thermochemical conversion gases. Switching to new non-design fuel is justified by considerations of reducing the negative impact on the environment and increasing the thermal efficiency of fuel combustion plants. In this case, the use of fuels with a composition different from the design one will affect the heat transfer processes. The main aim: carrying out a comparative analysis of indicators of the intensity of radiant and convective heat transfer of combustion products of non-design fuels, such as hydrogen, methane-hydrogen mixture and thermochemical conversion gases. As an assumption in the formulation of the problem and objectives of the study, the constancy of the heat release power in the apparatus due to changes in the amount of fuel burned was taken. Objects: heat exchange surface of a fire-tube hot water boiler. Methods: carrying out numerical calculation using traditional approaches to determine the indicators of the intensity of heat transfer in the system «combustion products – metal wall of the pipe of thermal power plants». We also used the relations tested earlier by other authors to calculate the thermophysical parameters of gas mixtures. Results. According to the results of the performed comparative calculations, we can conclude that the transition from the use of conventional fuel (natural gas/methane) to its thermochemical conversion gases under the considered conditions has almost no effect on the integral heat transfer performance. To a greater extent, this transition is caused by changes in the intensity of heat transfer for products of combustion of hydrogen and methane-hydrogen mixture, which will affect the operation of thermal power and heat technological installations. At the same time, it is necessary to conduct additional research on the combustion kinetics of thermochemical methane conversion gases, their thermophysical properties, etc., because the hardware design, type of the catalyst used and operating parameters of the process will affect the composition of obtained synthesis gas.

Curved coating structures improve the durability of corrosion-resistant coatings on the heated surfaces of coal-fired boilers

Curved coating structures improve the durability of corrosion-resistant coatings on the heated surfaces of coal-fired boilers

Optimising Pulse Combustion Systems for Enhanced Efficiency and Sustainability in Thermal Power Engineering

This study evaluates the potential of pulsed cleaning, an emerging technology, in the maintenance of heating energy and reclamation boilers. Findings suggest that pulsed cleaning presents an effective, energy-efficient and eco-friendly approach to deposit removal. However, there remains a necessity for further investigation to fine-tune the process and understand its long-term implications on boiler performance. The ultimate objective is to establish pulsed cleaning as a reliable, efficient and sustainable cleaning technique for boiler surfaces. The study determined that pulsed cleaning is an encouraging new technology for cleansing the surfaces of heating energy and reclamation boilers. Nevertheless, it was noted that additional research is required to fine-tune the pulsed cleaning procedure and to evaluate its prolonged effects on the efficiency of boilers.

Reducing surface heat loss in steam boilers

Abstract In this study, heat losses occurring on the outer surface of a steam boiler used in the distillation process in a textile company are discussed in detail. All surfaces of the boiler were scanned with a thermal camera to determine the non-insulated or poorly insulated areas. By drawing the schematic image of the boiler, the side surfaces, front cover, back cover, and parts of the smoke pipe were shown in different colors, and the temperature distributions in different parts of the boiler were revealed. Although most of the heat loss occurs on the side surfaces of the boiler, it was observed that these surfaces were already insulated. For this reason, a Pareto diagram was prepared according to the surface temperature to get an idea about where to start the improvement studies. Especially on the front and back cover surfaces, high-temperature values were measured and, it was determined that the heat loss on these surfaces was also at high levels. It was suggested that high-temperature surfaces should be covered with insulating jackets and pads, and sample applications were shown. The energy savings to be achieved and the payback period of the investment was revealed.

Prediction of the Behavior of Sunflower Husk Ash after Its Processing by Various Torrefaction Methods

Biomass can be considered an alternative to coal in the production of heat and electricity. Many types of biomass are waste from agriculture and the food industry. This waste is cheap, readily available, and replenished annually. However, most agricultural and food industry wastes (sugar cane pulp, olive and sunflower oil production wastes, straw, etc.) have ash with a low melting point. This leads to a rapid growth of ash deposits on the heating surfaces of boilers; as a result, the actual efficiency of boilers in which waste from agriculture and the food industry is burned is 45–50%. Known biomass pre-treatment technologies that allow for the fuel characteristics of biowaste. For example, leaching of biowaste in water at a temperature of 80–240 °C makes it possible to drastically reduce the content of alkali metal compounds in the ash, the presence of which reduces the melting point of the ash. However, this biomass pre-treatment technology is complex and requires additional costs for drying the treated biomass. We proposed to use torrefaction for pre-treatment of biomass, which makes it possible to increase the heat of combustion of biomass, increase the hydrophobicity of biomass, and reduce the cost of grinding it. However, we are not aware of studies that have studied the effect of torrefaction on the chemical composition of ash from the point of view of solving the problem of preventing the formation of agglomerates and reducing the growth rate of ash deposits on the convective heating surfaces of boilers. In this paper, the characteristics of sunflower husk subjected to torrefaction in an environment of superheated steam at a temperature of 300 °C and in an environment of gaseous products at a temperature of 250 °C are studied. All experiments were conducted using fluidized bed technology. The resulting biochar has a calorific value of 14.8–23% higher than the initial husk. To assess the behavior of sunflower husk ash, predictive coefficients were calculated. Torrefaction of sunflower husks does not exclude the possibility of slagging of the furnace but reduces the likelihood of slagging by 2.31–7.27 times. According to calculations, the torrefaction of sunflower husks reduces the likelihood of ash deposits on the convective heating surfaces of the boiler by 2.1–12.2 times. According to its fuel characteristics, the husk, after torrefaction in an environment of superheated steam, approaches wood waste, i.e., can be burned separately without additives or mixtures with other fuels with refractory ash.

Conversion of a pulverized coal boiler into a torrefied biomass boiler

The aim of the work is to analyze the possibility of converting a pulverized coal (PC) type OP650 boiler to combustion of 100% biomass in the form of torrefied PKS (Palm Kernel Shell). The replacement of hard coal with torrefied biomass in a PC boiler practically eliminates CO2 emissions. It also reduces the problem of coal shortages in the current political situation in Europe. However, it is necessary to solve the problems of changing the fouling of the boiler, grinding new fuel in coal mills, changing NOx emissions, and changing the exhaust gas dew point. We do not deal with torrefaction, assuming that this problem is technically solved and that such fuel can be purchased. The assessment of the boiler conversion to new fuel was based on the measurements of the boiler in its current state during combustion of coal dust. The HVT (temperature measurement by means of high-velocity thermocouple) measurement of temperature was carried out at points in the area of superheaters, on the rear wall and on one of the sidewalls using a water-cooled aspiration probe. The measurements of the growth rate of high-temperature deposits in the area of platen superheater tubes were also performed. On their basis, a 0-dimensional model of the boiler was created and the risk of slagging after replacing coal with torrefied biomass was assessed. Slagging and fouling tendency of heating surfaces during coal and PKS combustion were compared. The final evaluation of the possibility of converting the OP 650 boiler to combustion of 100% biomass in the form of torrefied PKS was performed. With the same ash fouling of the boiler as for coal, replacing coal with a fuel with a slightly lower calorific value and much lower humidity and ash content, such as torrefied PKS, causes a slight increase in the temperature of live and reheat steam, which in the conditions of the given calculation example gives practically nominal values of these temperatures. In the variant simulating increased fouling of the boiler during biomass combustion, the flue gas temperatures increase even more, which may lead to a strong increase in slagging and fouling. Calculations for wet PKS with significant fouling of the furnace still show high flue gas temperatures in the high temperature area of the boiler. In addition, for a fuel with such characteristics, the risk of slagging is very high. To mitigate the possible operating problems, a doping the PKS with Dunino halloysite from the Polish mine Dunino (DH) was considered. This aluminosilicate is recommended to protect against slagging and fouling. Important advantage of DH is the reduction of chlorine corrosion of the boiler surfaces. The results of the calculations show that during the combustion of PKS, the temperature of the flue gas outlet is higher than during the combustion of coal.

Impulse Air Jet Action on the Convective Heat Exchange Tubular Surfaces in Boilers

Calculation and experimental investigations were carried out to determine the parameters of the impulse air jet created by the pneumatic generator of the air-impact system of the cleaning of tubular heat exchangers in boilers. Two configurations (lengthwise and checkerboard) of the arrangement of tubular heat exchangers located at distances from 1.0 m to 2.5 m of nozzle exit were experimentally investigated and the forces acting on them were determined. Numerical modeling of the impulse jet impact on heat exchange tubes was carried out. It was shown that an increase in the pressure of the generated impulse jet to 2.35 MPa makes it possible to significantly increase the acting force from 78 N to 1881 N at a large distance from the exhaust nozzle. The results obtained can be used in the development of specific systems for air impact cleaning systems of boiler units with other sizes and configurations of the heat exchange tubes.

Investigation of biomass, RDF and coal ash-related problems: Impact on metallic heat exchanger surfaces of boilers

The goal of this work was to study the corrosion resistance of boiler steel and protective alloy coatings. Four ashes obtained from wood biomass, straw, refused-derived fuel and coal were analysed. The aggressive components of ash, such as potassium, sodium, sulphur and chlorine, can accelerate the operating problems of heat exchanging surfaces in power boilers, leading to enhanced slagging, fouling, agglomeration of ash, and corrosion. Four boiler steels were chosen for detailed investigation: 16Mo3, P265GH, Inconel 625 and 686. They were covered with ashes, placed in a furnace and heated through 4 months at 750 °C under oxidizing conditions. Multifaceted ash analysis (chemical composition, thermal behaviour, phase composition, and characteristic melting temperatures) was performed. Additionally, both slagging and fouling indices were calculated to predict the sintering properties of the studied ashes. The surfaces of studied steels after the exposure of ash presence were analysed using SEM-EDS technique. The results showed that the corrosive impact of the ashes depended on the aggressive components present in the ash. Furthermore, FactSage thermochemical equilibrium calculations were used to predict the amount of liquid slag and solid phases under the studied conditions and to determine the transformation of the mineral phases of the ash.

Properties of Ceramic Coating on Heating Surface of Waste Incineration Boiler Prepared by Slurry Method.

In order to alleviate the problem of high-temperature fly ash corrosion and slag on the heating surface of a high-parameter waste incinerator, a ceramic coating material that can be prepared in situ on the heating surface by the slurry method was studied. The ceramic coating can be formed by sintering at a lower temperature of 750 °C. Its surface and profile are very dense, and the porosity is less than 1%. The mechanical properties test results show that the ceramic coating can withstand 60 cycles of water-cooled thermal shock at 700 °C, and the bonding strength is 25.14 ± 2.21 MPa. It will not fall off in a large area when subjected to pressure load, and it has a certain degree of processable plasticity. High-temperature wettability experiments show that the ceramic coating has lower liquid-bridge force, smaller adhesion area, and shorter fouling cycle for molten corrosive fouling, and potential self-cleaning properties. Its practical mechanical properties make the coating valuable for production applications and meet expectations, and excellent antifouling properties to reduce average fouling thermal resistance and corrosion.