Failure Of Boiler Research Articles

Research on the Mechanism and Preventive Measures of Heat Transfer and Coking in Boilers

Boilers are one of the most important power supply sources in the chemical industry. The irreplaceable nature of its products requires boilers to maintain stable long-cycle operation during the production process. However, boiler failures occur from time to time and necessary measures need to be taken to reduce the chances of failure. Among these failures, metal corrosion and tube failures are particularly prominent. Due to the fact that the thermal calculation results do not match the actual; the coefficients in the design are not reasonably selected, and the hearth and boiler shape are not properly selected; the structural design of the superheater system and the arrangement of the heated surface are not reasonable; and the wall temperature calculation method is not perfect, which leads to the improper selection of materials and so on. These will make the fire-side heat exchange system produce wall temperature super-high, tube bundle burst and other failure phenomena. These phenomena cause a certain degree of hidden danger to the safe production of the boiler.

Data-driven modeling-based digital twin of supercritical coal-fired boiler for metal temperature anomaly detection

The flexible operation of coal-fired boilers deteriorates the heat transfer capacity of tubes, leading to localized overheating, tube cracking, and even boiler failure. This study presents a digital twin (DT) for detecting the metal temperature anomaly of a coal-fired boiler by predicting the metal temperature time series using data-driven methods. A data-based model adopting an extreme gradient boosting algorithm tuned by a particle swarm optimization algorithm is proposed to predict the metal temperature with an output sequence of 6 min. The predicted metal temperature is then transformed into an interval based on statistical distribution and confidence level to improve the robustness of the model. Moreover, a histogram is used to determine the benchmark of metal temperature anomaly with respect to varying operating conditions. The proposed DT is applied to a 600-MW on-duty supercritical coal-fired boiler. Results indicate that the proposed DT can accurately predict metal temperature and is useful for detecting metal temperature anomalies in advance.

Hazard assessment of hot water boiler at thermal power plant

Our world and every person require a huge amount of energy, both electric and thermal, which are produced mainly at various types of power plants, but mostly on thermal. During the production of electricity and heat at the thermal power plants different potential hazards are occurring: chemical, environmental, fire or explosion. In accordance with the identified hazards on thermal power plants, possible six emergency situation scenarios are suggested. The failure tree method was used for determining the potential danger of a hot water boiler being one of the elements of thermal power plant. Given the conditional probabilities of events, it is obtained that the failure of the hot water boiler is possible. For reducing the probability of failure and improving the hot water boiler safety – safety barriers (functional and symbolic) are proposed. After the safety barriers are inserted, the probability of a hot water boiler failure in our case is almost incredible. Many people live near thermal power plants, which may have a potential risk of harm to their health. An approach for determining the potential risk indicator of the health harm (R) near thermal power plants is proposed. It is provides the division of risk levels into four classes: extremely high degree of potential hazard – R>0.1; high degree of potential hazard – 0.1>R>0.001; average degree of potential hazard – 10−3>R>10−5; low degree of potential hazard – R>10−5.

The Effects of Laser Cladding Surface Treatment on Surface Degradation Properties :a Review

Surface degradation due to hot corrosion and erosion in thermal power plants and gas turbines, is one of the primary concerns for many researchers, scientists and surface engineers. Hot corrosion is considered as a serious problem in coal-based thermal power plants which fulfill approximately 58.3% of the total electricity demand of India. The practice of using low-grade fuels at high functional temperatures is the overriding reason for accelerated hot corrosion. A case study stated that approximately 56% of boiler failures occur due to hot corrosion that may lead to reduced economical efficiency of the thermal power plants. Fortunately, this problem can be controlled by some preventive measures, and surface modification is one of the effective methods to enhance the lifespan of boiler components. Surface modification can be done through different surface coating processes like plasma spray, HVOF and D-gun etc. In this paper, we will discuss the effects of Laser cladding surface coating process to develop the corrosion resistance surface properties of different substrate materials

Elicitation of Conditional Probability Table (CPT) For Risk Analysis of Biomass Boiler in Energy Plant

The utilization of Empty fruit bunch (EFB) in energy production has increased in Malaysia over the last two decades. The EFB can be used as a solid fuel in a boiler system for heat and power generation. However, numerous safety and technical issues lead to a lower energy production rate. A holistic probabilistic risk analysis is developed using the Bayesian Belief Network (BBN) to reduce the risk in the boiler system. The Conditional Probability Table (CPT) indicates the influence strength between the parent node and child node in BBN. Due to scarcely available information on EFB boiler, elicitation from the expert’s opinion is vital. The formulation for boiler failures likelihood prediction that relies on experts’ perceptions was developed using the Weighted Sum Algorithm (WSA). A case study from BioPower Plant in Pahang was applied in this project. The model illustrates the relationship between the cause and the effect of the biomass boiler efficiency in a systematic way. Two types of analyses, prediction and diagnostic analysis, were performed. The results facilitated the decision-maker to predict and identify the influential underlying factors of the boiler efficiency, respectively. The result shows that the most important boiler failure factor is combustion stability. It agrees with experts’ experience that most biomass boiler failure was caused by EFB, which contains high moisture content that affects flame stability. The proposed formulation for expert opinions and perceptions conversion can be utilized for risk analysis to benefit the boiler and other infrastructure that relies on experts’ experience.

Steam Package Boiler Expert System for Control and Maintenance of Fertilizer Plants using Rule-Base Fuzzy Logic

Generally, expert systems have been found very useful branch of artificial intelligence that makes extensive use of specialized knowledge to solve complex problems and even in fertilizer plants it has been deployed in handling operations in critical sections, such as material handling systems, online leak detection systems, granulation, air compressor among others. This paper presents research work for steam package boiler expert system for control and maintenance of fertilizer plants using rule-base fuzzy logic hybrid system, which has not been benefited much from expert system. The system handles cause of boiler failures in terms of controlling and maintaining the functional chemical components of the boiler drum and feed water parameters. validation on the system consistency, correctness, and its precision with six (6) steam package boiler parameters test value cases was conducted involving fourteen (14) fertilizer plant boiler domain partitioners. The boiler drum and feed water qualities with less or higher test value worst-cases validates the boiler system, showing each of the parameter’s bar turns red, as displayed on the boiler’s panel, while on test value best-cases, validates the system, displaying green on the boiler’s panel as users entered the right value of parameters per the design specification. We discovered that from 1 to 10 minutes run time for auto system run gives 10.8% errors as compared from 1 to 10 minutes time interval on manual system run that gives 80.2% error, this results to less effort in user interface application usage on auto operations better than manual. The expert system prevents damaged and malfunctioning as control the alkalinity, prevent scaling, both mechanical & chemical corrosion, forming, correct pH values and then the conductivity which deals with the feed boiler water and monitored the level in the boiler drum using the industry measurement parameters (pressure, temperature, level, and flow).

Modeling and analysis of home heating system material performance with induction using solar energy

As a result, in Libya, where temperatures do not drop significantly during the winter months, induction boilers connected to solar panels provide a practical and cost-effective solution for home heating. Because solar energy is utilized to its maximum capacity, the required room temperature can be easily achieved with a boiler with a low resistance capacity. Resistance boilers, on the other hand, have lost their appeal because of frequent failures and the need for considerable effort during the transformation process. Fortunately, the boiler's failure potential is minimal at this point; therefore, water heating using the induction heating principle is a suitable option in this situation. In this research, the goal is to look at water heating technologies as a potential replacement for electric boiler applications. Because of this, a specific method for heating buildings and water heating was developed and put forth for consideration. The electrical connection of the solar panels served as the power source for the planned system and satisfactory results were obtained. The results were verified using theoretical calculation and Computational fluid dynamics (CFD) software. The performance of the heat exchanger was evaluated, and the results showed that the efficiency is improved by decreasing the flow rate, tube diameter, coil diameter, and coil length; moreover, the performance index is enhanced by increasing the tube diameter and decreasing the coil, vessel diameter.

Characteristic analysis of dissimilar metal weld for AISI304 with SA213T22 in super heater coils

Super heater is an inevitable component of any boiler system and failure of super heater leads to breakdown of whole plant. The integration of efficient quality welding technologies for dissimilar metals will be a key component in the successful weld quality for power plant components. In this investigation, an attempt has been made to study the dissimilar material AISI304 and SA213T22 tungsten inert gas welding is performed under different welding conditions current (100, 115, 130 Amps), gas flow rate (6, 8, 10 ltr/min), speed (2, 2.5, 3 mm/sec) and micro structure analysis performed to find influence of fusion heat. The Taguchi analysis is implemented to obtain single response optimization and grey relational analysis used to attain multi response for best yield strength, the ultimate strength, Vickers hardness and the elongation of the metals.

Bayesian Network for Probability Risk Analysis of Biomass Boiler in Renewable Energy Plant

The empty fruit bunches have remarkable potential for utilisation as solid fuel boilers in the production of energy. A well operated boiler with higher efficiency is vital for a good power generation plant. However, there are numerous safety and technical issues that may lead to a lower energy production rate. A simple yet complete probabilistic risk analysis is needed to predict those issues to ensure the biomass boiler operates at its maximum efficiency. In this work, a probabilistic risk assessment model for empty fruit bunch boiler using Bayesian network approach was developed. Bayesian network provides a clear probabilistic model of cause-effect relationships of the biomass boiler system. The conditional probability values were elicitated from experts’ opinion to identify the most influential factors for efficient biomass boiler operation. A case study from Renewable Energy Plant in Pahang was applied. Prediction analysis and diagnostic analysis were performed and the results show that the most important biomass boiler failure factors are corrosion and overheating. These findings are in agreement with existing literature and expert judgement. Thus, the proposed model is useful in maintaining and helping the decision maker for biomass boiler operation as well as increasing its reliability.

Implementation of water chemistry in fossil power plants with drum boilers and in combined cycle/HRSG plants

Current water chemistry practice at fossil power plants with drum-type boilers and heat recovery steam generators includes ammonia dosing into the feedwater train and sodium phosphate or sodium hydroxide into the boiler water. The issues and impact on equipment with the use of phosphate or sodium hydroxide boiler water treatment, as well as optimum conditions for the use of these chemicals are discussed. Another operational issue of boiler unit is associated with flow-accelerated corrosion (FAC) of material, especially in the low-pressure circuit. The major reasons for boiler failures are outlined, with the data on FAC failure locations. An effect of oxygen and ammonia on boiler corrosion processes is discussed.

Performance of different coating materials against high temperature oxidation in boiler tubes – A review

At presently, the failure of a boiler is big hazard to the effectiveness of the boiler in the power plants. In coal fired boilers, erosion and corrosion at high temperature is responsible for the downtimes, which directly affect the economic loss. In the present review report, the current situation of combating the high temperature erosion and corrosion to the boiler surface has been discussed. The thermal spray coating techniques used for protecting the boilers has been studied in regard to the performance of different coating materials deposited using different coating methods. The performance of the developed coatings under high temperature oxidation has been reported. This article may help to researchers to select the best coating combination and method to resist the failure of boiler.

Numerical studies on furnace water walls failure in water tube boiler applications

Boiler as one of the main equipment in steam power plant system that has important function as steam generation for rotating turbine. Failure of boiler result in operational cause lowering the power capacity of the steam power plant system on the whole. From the data observation, boiler failure frequencies because of leakage on boiler tubes. To analyze the boiler tube failure accurately, information of temperature operated on the outer surface tube and temperature distribution on the furnace wall are needed. The main objective of this study is to investigate several areas in which the failure of furnace water walls boiler exists. A combined analysis of thermal and strength of material has been performed, in order to calculate the temperature and velocity fields inside furnace of the water tube boiler. Due to the geometrical complexity of the model, GAMBIT applications was used to generate a computer-based model. All numerical calculations have been performed using the commercial CFD package FLUENT. The results obtained were numerically that failure on furnace water walls in water tube boiler because there is localized overheating.

Flare stacks on agricultural biogas plants - safety and operational requirements

The flare stack is a piece of equipment, which is used as a safety element at a biogas plant. In the case of a cogeneration unit or gas boiler failure, the biogas is redirected to the flare stack where it is burned. When the flare stack fails, the biogas releases to the atmosphere and an explosive mixture can form. The paper is focused on the description of the causes, which can cause the failure of the equipment. For this purpose, the individual components are described and, subsequently, the possibilities of their failure are discussed. In the next part of the work, the following scenario is considered: failure of the cogeneration unit and flare stack, the subsequent leakage of the biogas to the atmosphere. The calculation for determining the consequences of the biogas leakage is carried out. The size of the gaseous cloud and the explosion pressure in the case of a vapour cloud explosion are determined. The calculations were carried out by the software ALOHA (version 5.4.7).

Impact of silica deposition on the performance of gas-fired domestic appliances caused by the combustion of siloxanes in the fuel

Abstract The effects of silica deposition resulting from the combustion of siloxane-containing biomethane on the performance of seven domestic appliances have been studied. The results show that silica deposition increases the flow resistance across the heat exchangers, which consequently reduces the air intake from the surroundings. For the flow-through hot water heater studied, the reduction in air intake in the appliance results in a substantial increase in the CO emission with time, ultimately resulting in a safety risk for the end user. For the fully premixed boilers examined, the increased flow resistance reduces the thermal input, and thus the thermal output, of the appliance. The extent of the reduction in thermal input is seen to depend strongly upon the concentration silicon in the fuel, and the configuration and material of the heat exchanger. For the boilers studied, the ion current measured by the flame safety device decreases with time because silica deposits on the probe used to measure the current in the flame; this ultimately results in boiler failure. Based on the results, extrapolation methods are proposed that can be used to assess the impact of low silicon concentrations in biomethane on appliance performance and safety with time.

Characterization and hot corrosion behavior of D-gun sprayed Cr2O3-75% Al2O3 coated ASTM-SA210-A1 boiler steel in molten salt environment

PurposeHot corrosion is the major degradation mechanism of failure of boiler and gas turbine components. The present work aims to investigate the hot corrosion resistance of detonation gun sprayed (D-gun) Cr2O3-75 per cent Al2O3 ceramic coating on ASTM-SA210-A1 boiler steel.Design/methodology/approachThe coating exhibits nearly uniform, adherent and dense microstructure with porosity less than 0.8 per cent. Thermogravimetry technique is used to study the high temperature hot corrosion behavior of bare and coated boiler steel in molten salt environment (Na2SO4-60 per cent V2O5) at high temperature 900°C for 50 cycles. The corrosion products are analyzed by using X-ray diffraction, scanning electron microscopy (SEM) and field emission scanning electron microscope/energy-dispersive analysis (EDAX) to reveal their microstructural and compositional features for elucidating the corrosion mechanisms.FindingsDuring investigations, it was found that the Cr2O3-75 per cent Al2O3 coating on Grade A-1 boiler steel is found to be very effective in decreasing the corrosion rate in the molten salt environment at 900°C. The coating has shown lesser weight gains along with better adhesiveness of the oxide scales with the substrate till the end of the experiment. Thus, coatings serve as an effective diffusion barrier to preclude the diffusion of oxygen from the environment into the substrate boiler steel.Research limitations/implicationsTherefore, it is concluded that the better hot corrosion resistance of the coating is due to the formation of desirable microstructural features such as very low porosity, uniform fine grains and the flat splat structures in the coating; as compared to the bare substrate under cyclic conditions.Practical implicationsThis research is useful for coal-fired boilers and other power plant boilers.Social implicationsThis research is useful for power generation plants.Originality/valueThere is no reported literature on hot corrosion behavior of Cr2O3-75 per cent Al2O3 coating deposited on the selected substrates by D-gun spray technique. The present work has been focused to study the influence of the Cr2O3-75 per cent Al2O3 coating developed with D-gun spraying technique on high temperature corrosion behavior of ASTM-SA210-A-1 boiler steel in an aggressive environment of Na2SO4-60 per cent V2O5 molten salt at 900°C under cyclic conditions.

Failure Mode and Effect Analysis (FMEA) for Enhancing Reliability of Water Tube Boiler in Thermal Power Plant

Failure mode and effect analysis is one of the QS-9000 quality system requirement supplements, with a wide applicability in all industrial fields. FMEA is the inductive failure analysis instruments which can be defined as a methodical group of activities intended to recognize and evaluate the potential failure modes of a product/ process and its effects with an aim to identify actions which could eliminate or reduce the chance of the potential failure before the problem occur. The purpose of this paper is to evaluate the FMEA research and application in the Thermal Power Plant Industry. The research will highlight the application of FMEA method to water tubes (WT) in boilers with an aim to find-out all the major and primary causes of boiler failure and reduce the breakdown for continuous power generation in the plant. Failure Mode and Effect Analysis technique is applied on most critical or serious parts (components) of the plant which having highest Risk Priority Number (RPN). Comparison is made between the quantitative results of FMEA and reliability field data from real tube systems. These results are discussed to establish relationships which are useful for future water tube designs.

Optimal Operations and Resilient Investments in Steam Networks

Steam is a key energy vector for industrial sites, most commonly used for process heating and cooling, cogeneration of heat and mechanical power as a motive fluid or for stripping. Steam networks are used to carry steam from producers to consumers and between pressure levels through letdowns and steam turbines. The steam producers (boilers, heat and power cogeneration units, heat exchangers, chemical reactors) should be sized to supply the consumers at nominal operating conditions as well as peak demand. First, this paper proposes an Mixed Integer Linear Programing formulation to optimize the operations of steam networks in normal operating conditions and exceptional demand (when operating reserves fall to zero), through the introduction of load shedding. Optimization of investments based on operational and investment costs are included in the formulation. Though rare, boiler failures can have a heavy impact on steam network operations and costs, leading to undercapacity and unit shutdowns. A method is therefore proposed to simulate steam network operations when facing boiler failures. Key performance indicators are introduced to quantify the network’s resilience. The proposed methods are applied and demonstrated in an industrial case study using industrial data. The results indicate the importance of oversizing key steam producing equipments and the value of industrial symbiosis to increase industrial site resilience.

Power Plant Boiler Failure Analysis of Main Components

This paper briefly introduces the basic condition of power station boiler operation and failure analysis of the necessity of power plant boiler failure types and main components of power plant boiler failure types of main components. Illustrates the failure analysis of the main analysis method, and introduces the failure analysis of the role of failure analysis.

Hot Corrosion Behaviour of Detonation Gun Sprayed Al2O3-40TiO2 Coating on Nickel Based Superalloys at 900°C

Hot corrosion is the major degradation mechanism of failure of boiler and gas turbine components. These failures occur because of the usage of wide range of fuels such as, coal and oil at the elevated temperatures. Nickel based superalloys having excellent mechanical strength and creep resistance at elevated temperature are used under such environment but they lack resistance to hot corrosion at high temperature. To overcome these problems hot corrosion resistant coatings are deposited on these materials. In the current investigation Al2O3-40%TiO2 powder has been deposited on Superni 718 and AE 435 superalloys by Detonation Gun method. The hot corrosion performance of Al2O3-40%TiO2 coated as well as uncoated Superni 718 and AE 435 alloys has been evaluated in aggressive environment Na2SO4-82%Fe2(SO4)3 under cyclic conditions at an elevated temperature of 900°C. The kinetics of the corrosion is approximated by weight change measurements made after each cycle for total duration of 50 cycles. Scanning electron microscopy was used to characterize the hot corrosion products. The coated samples imparted better hot corrosion resistance than the uncoated ones. The AE 435 superalloy performed better than Superni 718 for hot corrosion in a given environment.

Co-combustion of Animal Waste, Peat, Waste Wood, Forest Residues, and Industrial Sludge in a 50 MWth Circulating Fluidized-Bed Boiler: Ash Transformation, Ash/Deposit Characteristics, and Boiler Failures

In strive to lower the energy conversion cost and CO2 net emission, more complex biofuels are used. The combustion of these fuels often creates aggressive and problematic fireside environments in boilers, resulting in reduced availability, which, in turn, may lead to increased usage of fossil fuel in backup boilers. The objective of the present work was to contribute to the efforts of maximizing the availability of a 50 MWth circulating fluidized-bed (CFB) boiler firing complex fuels with high amounts of P, Ca, S, Cl, N, K, and Na. In the present work, ash and deposit samples collected from the flue gas system of a CFB boiler were further analyzed with X-ray powder diffraction, complementing earlier analysis made on the same sample set with scanning electron microscopy equipped with energy-dispersive spectrometry. Thermodynamic calculations were also made. The results clarify details about the ash speciation and transformation as well as effects on boiler operation. A suggestion of a control strategy to minimize corrosion rates in superheaters and SO2 emission to downstream cleaning equipment in full-scale industrial boilers is made. An equation for rough estimation of fuel mix corrosion tendencies is also presented.