Boiler Tubes Research Articles

Design and Analysis of Actual Soot Cleaning System for Fire Tube Boiler

Soot blowers are used to control a boiler with high power to release dirt from the heat transfer surfaces towards the gas. They are additionally accustomed to gas pass closure. They are mechanical devices used to clean gas side boiler ash and deposits online on a periodic basis. They dictate To get rid of the ash deposited on the coil and improve the heat transfer power, the operating medium through the nozzle against the soot or ash deposited on the heat transfer surfaces on the boiler. Sort the blowers in boilers in many places such as water walls, super heaters, economists and air preheaters. Watch for heat transfer soot blowers and efficiencies do not improve. Therefore, the design and analysis of soot burners can effectively increase boiler power in power plants.

3-Dimensional Microstructure Investigation of High Temperature Corrosion of Boiler Tube Material

The material of the tubes has suffered localized overheating and corrosion, probably as a result of local heat flux impingement phenomenon, combined with high temperature corrosion. Boiler tubes that experienced failure indications were tubes material SA 213 T22 with the dominant alloy elements is Cr. Materials with these specifications are which should be resistant to corrosion, so it is necessary to carry out laboratory testing to answer suspected indications of failure. The methodology of analysis and identification carried out is by observing the microstructure in 3 dimensions supported by other mechanical tests, namely visual observation, hardness testing, chemical composition testing using SEM and EDAX and testing the chemical composition of the material using a spectrum analyzer. Observation using an optical microscope shows that the microstructure condition of the tube is ferritic and the results of 3D metallography observations show that the tube has undergone micro crack with a measured depth of 1853,28 μm. After the metallography testing is carried out, the hardness test is carried out with the hardness vickers (HV) unit and the minimum hardness is 149 HV and the maximum hardness is 177 HV. Testing of the chemical composition of the deposit showed that there were chemical elements found in seawater that trigger corrosion such as sodium and chlorine which enter the water vapor system. The results showed that the tube had pitting corrosion, which was indicated by the presence of microcrack at the grain boundaries and an oxide deposit had been formed which would cause an overheating phenomenon and deterioration.

Role of Organic and Eco-Friendly Inhibitors on the Corrosion Mitigation of Steel in Acidic Environments-A State-of-Art Review.

Steel has versatile application in chemical, structure and construction industries owing to its mechanical properties. However, it is susceptible to corrosion in acid environments. Thus, it requires to protect the steel from corrosion. Different types of corrosion resistance steel, coatings and inhibitors are developed to mitigate the corrosion, but, inhibitor is the best remedies to control the corrosion of steel in acid condition. Moreover, organic and green inhibitors used in acid condition for descaling, acid pickling, pipelines, boiler tubes and oil-wells. Organic inhibitors reduce the dissolution of steel in acid but, it is hazardous, expensive and needs expertise to synthesize the inhibitor. Therefore, there is utmost required to study and compile the latest research about the eco-friendly corrosion inhibitors, which showed more than 90% corrosion inhibition efficiency. In the present study, I have reviewed the state-of-arts, and compile the latest development in organic and eco-friendly corrosion inhibitor used in acid environment as well as suggested about the future scope and role of green inhibitor for sustainable society, which is economical, less hazardous and readily available from the natural sources.

Failure investigation into the boiler tubes of power plant

Failure of tubes is a very critical problem in boilers. The current study describes the detailed investigation for failure of boiler tubes in the power plants. Different characterization techniques like; metallography/microscopy, hardness, chemical analysis, SEM/EDS were utilized to find out the actual cause of failure. The tubes were failed within one year of its service. It was concluded that the brittle fracture (rupture) of tubes was occurred due to over-heating caused the formation of thermally insulating thick iron oxide scale on the inner surface of the boiler tube. Evidence of hydrogen embrittlement of the boiler tube in the rupture region was also found. Insights of this investigation might be helpful for the prevention of this type of failures in future.

Coexistence of two distinct fatigue failure mechanisms in Super304H welded joint at elevated temperatures

Super304H steel is a promising candidate for boiler tube materials in thermal power plants operating under ultra-supercritical conditions, and the fatigue properties of its welded joint play a key role in the structural reliability of the thermal power plants. Herein, we report that there is a transition in the fatigue failure location (i.e., fatigue failure mechanism) from the base metal at a high strain amplitude (≥~0.4%) to the weld metal at a low strain amplitude (≤~0.3%) at a constant temperature in the operating range of 500–700 °C, and this leads to a significant reduction in the fatigue resistance of the welded joint as compared to that of the base metal. We found that a longer fatigue test time at a low strain amplitude induces a thermal aging effect that promotes different microstructural evolutions in the base metal and weld metal, deepening material inhomogeneity in the welded joint, and thereby triggering strain localization in the weld metal. With increasing fatigue test time (i.e., thermal aging time), Cr23C6 carbides precipitated in the interdendritic region of the weld metal and at the austenitic grain boundary of the base metal, and Nb (C, N) phases precipitated in the interior of austenitic grain in the base metal, which increased local hardness, whereas there was no significant microstructural change in the dendrite core of the weld metal, retaining its initial hardness. The intensified local hardness inhomogeneity caused the softest zone in the welded joint, wherein strain localization occurred, serving as a crack nucleation site and propagation path, to shift from the base metal to the weld metal (dendrite core). This induced a shift in the fatigue failure location from the base metal to the weld metal with decreasing strain amplitude.

WATERWALL TUBE BOILER DAMAGE ANALYSIS IN A 150 MW STEAM POWER PLANT

Steam Power Plant which uses environmentally friendly types of boilers such as CFB (Circulating Fluidized Bed) type boilers. Failure of the boiler pipe has a big impact on the process or the losses it causes. This study will analyze the failures that occur in the boiler tube waterwall of PT. DSSP Power South Sumatra which suffered damage by testing chemical content, hardness test, tensile test, metallographic testing, and Scanning Electron Microscopy (SEM) testing. The test results show that the composition contained in the boiler tube waterwall is not in accordance with the standards, there are some elements that are lower than the specifications. The mechanical properties of watertube boilers are still in accordance with the standards. Leaks that occur in pipes are caused by creeping cracks and causing fatigue so that the damage begins with 'thermal fatigue' which causes cracks in certain weld seams. These open cracks produce leaks which cause the discharge of high velocity fluids which hit adjacent surfaces creating an 'erosion' failure which then results in thinning of the walls of the tube. The thinning of the walls then causes another leak. Therefore, a series of erosions occurred which resulted in several leaks. The fact is that the failure is preferably located in the area of the weld seam which makes it the root cause of the failure

Analisis Ketersediaan Pasokan Listrik di PT PLN (Persero) UPK Teluk Sirih dengan Metoda Lean Six Sigma

This research was conducted to analyze electricity supply availability from the steam power plant at PLN Teluk Sirih. This electricity supply availability is also called the equivalent availability factor (EAF). The regular efforts made to maintain the EAF at PLN are still corrective, by repairing the damage that has occurred, and no systematic method has been implemented. Accurate analysis is required to achieve high EAF values and precision so that the problem's root cause can be resolved. This can be done by using the lean six sigma method. This method can identify waste and solve problems quickly. The methodology used is Define, Measure, Analyze, Improve, and Control (DMAIC). The waste that occurs is a defect, which is the inability of the power plant to supply electricity to customers (PLN P3BS). The identification results show that the factors that influence EAF are boiler tube leak (41.46%), DS Phase S (20.45%), equipment vibration (5.85%), bottom ash system (5.39%), and other disorders (26.84%). The EAF calculation for the last two years is 70.93%, and the six sigma level is 2.05. The improvement design is expected to eliminate boiler tube leak and increases the EAF by 6.65%. Thus, the EAF value becomes 77.85%, and the six sigma level becomes 2.26.

A review of thermal spray coatings for protection of steels from degradation in coal fired power plants

Abstract In coal fired power plants, the metallic surfaces such as boiler tubes, walls of combustion chambers and other parts degrade by corrosion, erosion and abrasion. It happens due to the hot gaseous environment, steam oxidation and presence of hard minerals and impurities in the coal. It is very important to protect these surfaces from material loss, otherwise it would lead to increased repair and maintenance cost along with decreased plant efficiency. In this paper, the role of thermal spray coatings has been studied for the protection of different steel grades exposed to such degrading conditions at high temperatures, in coal-based power plants. A comprehensive study has been done by analysing and comparing the work done by various researchers. Some recent advancements related to coating materials and modification in coating techniques have also been studied. This paper would be helpful for the researchers to get an idea for selecting an appropriate substrate material and coating material for industrial applications.

Parametric optimization of wire-EDM machining of nimonic 80a using response surface methodology

Wire electrical discharge machining (WEDM) can machine hard materials with ease. Nimonic 80A is hard and high temperature resistant material which is widely used in the power plant boiler tubes, gas turbines, exhaust valves. This work involves in developing a models for correlating the dependency of various WEDM process parameters of Nimonic 80A like gap voltage, duty factor and feed rate on response factors like rate of material removal (MRR), wire wear ratio and surface roughness (SR). This experiment was carried out on the basis of Response Surface Methodology (RSM) and Grey Relational Analysis (GRA). Using the design of experiments, 20 experiments were conducted. The duty factor of 0.8771, gap voltage 17V and wire feed rate of 17m/min was found to be the optimized process parameter while machining Nimonic 80A.

Study of heat transfer characteristics on steel tube boilers by the application of zinc oxide and graphene coatings

Steel tube boilers play predominant role in many process industries like nuclear power generation, petrochemical, desalination etc. The reliability of heat exchangers is an area which deserves close attention. Requirements for heat exchangers such as improved efficiency, stringent environmental needs, and cost effectiveness demand reliable materials specially for the heat exchanger tubing. Because, thermal efficiency reflects how well the boiler vessel transfers heat. To analyze the heat transfer performance of steel tube boiler, the proposed work implement the application of zinc oxide and graphene coating with an average rate of 8.06 µm and 10.9 µm, respectively. Since these coatings influences the wall thickness of steel tube boiler, the heat transfer characteristics is highly increased with enhanced heat dissipation through wall-surface. For experimental analysis, in boilers the heat transfer rate is measured using a heat transfer setup in which surface temperature and base temperature readings are recorded which in turn will be applied in the heat transfer mathematical equation to acquire the overall heat transfer rate. In addition, RSM, SEM evaluation is carried out to check whether roughness of a zinc oxide or graphene coating surface generates more area causing molecular interaction resulting in higher heat transfer rate.

Investigation on control in oxide scale formation and prevention of peeling off in ultra-supercritical unit

It is a common problem that oxide scale of boiler tube peels off in supercritic al unit. In recent years, many boiler tube burst accidents have been caused by oxide sc ale peeling off and blocking. Therefore, the analysis and research of oxide scale is of g reat significance. In order to control the occurrence of such accidents and reduce the ec onomic losses of thermal power plants, this paper mainly analyzes the factors influenci ng the oxide scale growth rate, peeling off condition and puts forward corresponding p revention and treatment measures.

Water wall tubes failure analysis in a 25-megawatt steam power plant

The failure of water wall tubes in a boiler steam power plant has been analysed. When the first inspection was conducted on the 25-Megawatt steam power plant, leakage was found on several water wall circulating fluidized boiler (CFB) tube. Visual examination, chemical composition analysis, hardness measurement, and metallographic examination on the tube samples cut from the water wall were used to analyse the cause of the failure. Visual examination showed that there is a thick weld joint on the tube inner side that could induce overheat and cause the tube to fracture and, in some locations, there were thick deposits on the tube inner side. A Hardness measurement of the tube near the fracture location showed an increase in the hardness value ranged from 191 – 206 HV. Metallographic examinations showed that there has been some micro-crack along the grain boundary. Composition analysis on the deposit at the inner side of the tube showed a trace of magnesium and calcium indicate that the water quality of the boiler doesn’t meet the standard. To resolve the problem, it is recommended to fix the weld procedure and kept the water quality to meet the standards.

Effect of Heat Input in Dissimilar Welding on SS304H and T22 to Hardness Distribution and Delta Ferrite Content with GTAW Process

In this paper, a study was carried out on the effect of various heat input on the hardness distribution and delta ferrite content in dissimilar welding on T22 and SS304H tube boilers in power plants using Gas Tungsten Arc Welding (GTAW). The heat input used in this study is 2.9 KJ/mm, 3.1 KJ/mm and 3.6 KJ/mm. Controlling the heat input parameter is one method to reduce problems in dissimilar welding. The general problem occurs in dissimilar welding is the failure on the weldment to occur due to differences in chemical composition, mechanical properties and thermal coefficients of the two materials where it makes degradation in the microstructure in the fusion zone and creating residual stress than susceptibility to fatigue in material or cracks. All variation of heat input in this study is safe to operate in the welding process and low tendency to hot cracking. Using the lowest variation of heat input 2.9 KJ/mm has the highest value of hardness distribution and lowest FN value.

Effects of Different Turbulators on Heat Transfer in Smoke Tube Boilers and Modeling of These Effects with Machine Learning Algorithms

In smoke pipe boilers, the thermal efficiency of the boiler depends on the smoke pipe diameter, smoke pipe length and the heat transfer between the smoke pipe and the outlet chimney. If the heat in the smoke pipes is effectively transported through the pipes, the heat distribution on the surfaces is balanced and the thermal efficiency of the boiler increases. In this study, the improvement of heat transfer in a solid fuel boiler with 125,000 kcal / h heat capacity with a diameter of 42 mm, chimney diameter of 230 mm and water inlet and outlet diameters of 65 mm was investigated by using 4 different types of strip turbulators. Experiments were carried out with turbulators placed in all the smoke pipes in the boiler. Firstly, experiments were carried out without placing a turbulator inside. In the second step, by placing turbulators in the smoke pipes, experiments were made for each type and heat transfer was calculated. In the experiments, the flow rate of the fan was changed with the help of damper and the reynolds number was calculated between 18000 and 28000. Turbulator experiments for heat transfer improvement have increased by at least %15 and at most %41 compared to turbulator free experiments. For the heat transfer increase values obtained because of calculations, predictive models were obtained using machine learning algorithms SVM (support vector machine) and decision tree (M5P model tree). The resulting models have been analyzed for error analysis and have been shown to successfully predict heat transfer increase values.

Application of artificial neural network to map the performance characteristics of boiler using different algorithms

ABSTRACT The present work demonstrates the real time predictions of the performance characteristics of a 210 MW boiler using artificial neural network (ANN) approach. ANNs have been successfully applied to model the different characteristics such as power, outlet steam pressure, and efficiency of a coal-fired water tube boiler. The training and testing data to develop the ANN were obtained through a number of experiments from the boiler of a thermal power station. Back propagation algorithm was utilized to train the ANN. The inputs considered were coal flow rate, percentage of load, and steam flow rate. The application of the developed model exposed better results in terms of regression value (R2), accuracy, percentage error, and mean square error. The co-efficient of multiple determination value was 0.99874 for the developed model which is very close to 1. It is perceptible that the developed model could be a better tool in predicting the performance of the boiler. In addition, modeling was also done based on radial basis network and compared with the back propagation network. Comparison of results indicates that the back propagation algorithm network performs better than radial basis network.

Three Steps Mixed (Fire Tube–Water Tube) Vertical Boiler to Optimize Thermal Performance

The research aims to design and construct a new mixed vertical boiler (fire tube – water tube) with three gas passes. The strength of this technological innovation is in the best use of the thermic transmission receiving fluid (hot water, steam, thermal oil), this due to its multipurpose function of three steps using alternative fuels (Diesel, Liquid Petroleum Gas LPG, natural gas), by improving the thermal efficiency of the boiler its temperature is reduced with gases at low temperatures, which in turn also reduce environmental pollution. The methodology focuses on calculating the transfer area with the calculation method that will allow dimensioning the boiler, considering the calculation of losses and the fluid speed, with two defined procedures, the first for fire tube and water tube boilers. And another alternative. The results obtained allowed optimizing the thermal efficiency level, achieving very significant thermal efficiency results: With LPG 92.4% for hot water and 92.42% to generate steam in the same way with natural gas 90.25% for hot water and 90.24% to generate steam as well with Diesel 2; 89.21% for hot water and 89.31% to generate steam.

Under-Deposit Corrosion on Steel Pipeline Surfaces: Mechanism, Mitigation and Current Challenges

Under deposit corrosion (UDC) is a serious risk in the industry, threatening critical failures in oil and gas pipelines, boiler and heat exchanger tubes, cooling systems and wastewater treatment facilities. Generally speaking, there is no single defined mechanism for UDC as it follows any of many different routes depending on the local chemistry and the nature of the deposits involved. In addition, UDC is frequently combined with microbiologically influenced corrosion (MIC), which adds further complexity to the mechanism and enhances the resulting damage. At the moment, different mechanical and physical techniques are implemented in the industry to combat UDC with varying success. Mitigation of UDC is generally difficult and requires a detailed understanding of the species involved, the deposits present and, finally, the mechanism taking place. This paper aims to provide a brief review of the recent literature on UDC. First, the basic definition, corrosion mechanisms and types of deposits are discussed. Then, the relationship between deposit structure and corrosion mechanism and association with MIC are thoroughly explored. Finally, a general overview of the main mitigation approaches in the oil and gas industry is presented.

A study of T11 boiler steel protection by cold sprayed Inconel 738 coating against high temperature erosion

The failure of boiler tubes, superheater tubes and turbine blades, due to high-temperature erosion, is a serious issue in the power generation industry. The investigation focuses on the applicability of cold sprayed Ni-based coatings for boiler tubes and turbine blades, by improving the erosion resistance of the base material. The present work includes high-temperature solid particle erosion behaviour of Inconel 738 (IN 738) coatings deposited on ASTM SA213 T11 steel substrate, by means of cold spray deposition. A comparison of the temperature effects on the erosion performance of coated and uncoated samples have been examined by an air jet erosion tester. After the erosion tests, both uncoated and coated specimens were characterised using a scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis. Erosion resistance of the coating is approximately three and two times higher than T11 steel at 700°C for 30°and 90° impact angles, respectively. Consequently, cold spray IN 738 coating offers higher resistance to high-temperature erosion than that of the base steel, which is essential in a power plant environment.

Modeling, multi-objective optimization and comparison of fire and water tube heat recovery steam generators for gas engine cogeneration plants

An innovative modeling and optimizing of fire and water tube heat recovery steam generators (HRSG) for gas engine cogeneration plant are performed here. In modeling section, the equations of ɛ-NTU, LMTD and heat transfer coefficients for one-phase flow and two-phase flow are organized to form a nonlinear system of equations. Furthermore, in the next step, two pairs of objective functions (annual expenses—exergy destruction rate and annual expenses—thermal effectiveness) are selected for multi-objective optimization of HRSG by the use of genetic algorithm for one, two and three MW gas engine cogeneration plants. Results for a 2 MW gas engine (as an example) show that the fire tube HRSG total expenses are 50% lower than that for water tube HRSG. In this situation, for water and fire tube boilers, the effectiveness and cost are 0.9, 40,000 ($/year) and 0.9, 20,000 ($/year), respectively. Furthermore, the exergy destruction rates are close and equal to 1373.45 kW and 1366.2 kW for water tube and fire tube boilers, respectively. Moreover, for each gas engine, six equations with thirty constant coefficients are obtained to explain the behavior of HRSG outlet exhaust gas temperature, pinch temperature difference, steam generation mass flow rate, working pressure, thermal effectiveness and exergy destruction rate at partial load.

Investigation on Boiler Grade Tubes and Tube Plate Using FWTPET Process assisted with PCA

Friction Welding of Tube to Tube Plate using an External Tool (FWTPET) is also used to fuse materials from steel in this study. This inquiry involves the existence and absence of a backrest of the SA 213 boiler-grading tube to the SA 387 tube base in FWTPET. Taguchi L9 orthogonal array and Analysis of Variance (ANOVA) are used to determine the best tensile strength and hardness from the input parameter. The Optimization Part has been performed using Principal Component Analysis (PCA) in the welding process parameter. Moreover, both the welds' interface that can create defect-free welds was found in surface morphological studies. The tensile and hardness properties were evaluated, and the values were tabled so that optimum parameters could be calculated.