Water Tube Boiler Research Articles

Retrofitting Natural Gas–Fired Boiler for Hydrogen Combustion: Operational Performance and NOx Emissions

Abstract The effects of hydrogen fraction (HF: volumetric fraction of H2 in the fuel mixture of CH4 + H2) from 0% to 100% by volume, on the thermal and environmental performance of a 207-MW industrial water tube boiler, are investigated numerically at a fixed excess air factor, λ = 1.15. This study aims to determine the hardware modifications required for boilers to be retrofitted for pure hydrogen operation and investigates how NOx emissions are affected by hydrogen enrichment. The results showed insignificant increases in maximum combustion temperature with increasing the HF, though the distributions of temperature profiles are distinct. In reference to the basic methane combustion, H2 flames resulted in a positive temperature rise in the vicinity of the burner. Increasing the HF from 0% to 2% resulted in higher average thermal NOx emissions at the boiler exit section from 37 up to 1284 ppm, then it decreased to 1136 ppm at HF = 30%, and later it leveled up to 1474 ppm at HF = 100%. The spots for higher differences in NO formation compared to the reference case are shifted downstream at higher HFs. The effect of hydrogen enrichment on CO2 and H2O as radiation sources, as well as the volumetric absorption radiation of the furnace wall and the heat flux at furnace surfaces, has all been presented in relation to the effect of hydrogen addition on boiler performance.

Operational control of the energy performance of a water-tube boiler using intelligent monitoring of operating variables and parameters

Operational control of the energy performance of a water-tube boiler using intelligent monitoring of operating variables and parameters

Concept Design of the WRB-6 Water-Tube Boiler with a Stepped Grate and a Furnace for Burning Straw Bales in a Cigar System

The article presents the conceptual design of the solid fuel from the forest and sawmill production waste and agricultural waste biomass-fired water boiler. The project was supported by thermal and flow calculations. The designed WRB-6 boiler is a 3-pass unit with a fully screened furnace chamber and is equipment of a local biomass heating plant. It is fired with biomass, transported over no more than 30 km. The furnace has a double function – dual fuel. Both fuels can be burned simultaneously or alternately, depending on seasonal availability. In the front part there is a channel for feeding and burning large bales of cereal straw. The lower closure of the chamber is a mechanically inclined grate for the combustion of wood biomass in the granulation of chips. As part of the work, calculations of the amount of biomass fuels possible to be obtained on the local market with economy of delivery were also performed. As a result of the calculations, the temperatures of water and flue gas at the outlet, boiler efficiency, slagging and impurity indices for biomass were also presented.

Uzroci pojave najčešćih grešaka na kotlovskim membranskim zavarima

The paper describes causes of the most common defects on boiler membrane welds according to EN ISO 12952-5. The research is carried out on water tube boiler manufactured by the company Đuro Đaković Termoenergetska postrojenja d.o.o. This paper elaborates the most common defects like cavities and undercuts that appear on membrane welds.

Power Generation from Utilizing Thermal Energy of Hazardous Waste Incinerators

A large amount of thermal energy is generated from burning hazardous chemical wastes, and the temperature of the flue gases in hazardous waste incinerators reaches up to (1200 °C). The flue gases are cooled to (40°C) and are treated before emission. This thermal energy can be utilized to produce electrical power by designing a system suitable for dangerous flue gases in the future depending on the results of much research about using a proto-type small steam power plant that uses safe fuel to study and develop the electricity generation process with water tube boiler which is manufactured experimentally with theoretical development for some of its parts which are inefficient in experimental work. The studied system generates theoretically (120 kg steam /h at 8 bars) with dry wood as fuel and preheating for the air of combustion and feed water and a diesel engine of (8 hp) four-stroke with single piston converted to steam engine coupled with the electrical generator of (3 kVA). The results are compared with practical values valid in the literature about small power plants of steam capacity (0.1-1) ton/h and operating pressure up to 10 bars. Experimentally, the generated electrical power is little and sufficient to operate a small fan and lump. The current converted steam engine is better than a conventional steam engine in auto lubrication with some operational problems. The boiler efficiency is 63.28%.

Performance Evaluation and Parametric Optimization of Coal-Fired Water Tube Boiler Using the Grey-Taguchi Method

Industries, district heating companies, and public institutions that use boilers for heating, processing, or power production find it challenging to run at peak efficiencies due to rising fuel prices. Insufficient heat energy production and distribution through boilers contribute to an overall increase in energy expenditure. The performance of a boiler is affected by various controlling parameters, including specific fuel consumption capacity, load, and heat losses. The current study was conducted to evaluate the performance of the coal-fired water tube boiler at D.G. Khan Cement Company Limited, Pakistan. The experimental results were validated with artificial neural network- (ANN-) based predictions, which were observed to have an error of 14% in the regression plot. In this study, the performance parameters of the boiler, including steam temperature (ST), steam pressure (SP), and specific steam flow rate (SSFR), were optimized against fuel consumption (FC) and load using the Grey-Taguchi method. The best-performing parameters, with the best criteria, were observed at an overall grey relational grade (OGRG) of 0.891 and a load of 66%. The findings indicated that the overall performance of the boiler was optimized with an FC of 3.09 kg/s, a load of 66%, ST of 532°C, SP of 9.93 MPa, and SSFR of 21.38 kg/s.

The effect of aluminide coating on the steam oxidation behavior of SS321 steel at 700 °C

Steam oxidation is considered the main attack form involved in the destruction of superheater tubes in the superheater of water-tube boiler. In this work, the effect of an aluminide coating on the way steam reacts with SS321 steel in a superheater was studied. Aluminide coating was done by powder cementation at 800 °C for 7 h and then heat treatment at 900 °C for 1 h. The coating was made with an Al-rich Fe2Al5 phase, with an inner (diffusion) layer of 5 μm and an outer layer of 25 μm. The grains were all the same size, and there were few holes. The samples were subjected to a constant stream of supersaturated water vapor at a temperature of 700 °C. The weight gain of uncoated and coated samples was measured as 1 mg cm−2 and 0.5 mg cm−2 after 20 h, and 2.5 mg cm−2 and 0.7 mg cm−2 after 350 h, respectively. The remarkable weight loss of the coated samples after 20 h and up to 350 h was attributed to the formation of stable Al2O3 oxides. This was although in the uncoated samples, the outer and inner layers of the coating were composed of Fe-rich oxides (magnetite) and Cr-rich oxides (Cr-Fe spinel oxides), respectively. Microstructural studies showed that with the increase in oxidation time, the inner layer (diffusion) increases from 5 μm to 25 μm, which is attributed to the diffusion of substrate particles towards the coating during oxidation.

Novel modelling for a steam boiler under fast load dynamics with implications to control

This paper describes a new nonlinear dynamic model for a natural circulation boiler. The model is based on physical principles, i.e. mass, energy and momentum balances. A systematic approach is followed leading to new insights into the physics of drum water level and downcomer mass flow. The model captures fast dynamic responses that are necessary to describe the operation of a boiler under highly variable load conditions. New features of the model include (i) a multi-compartment model for the risers, (ii) a new model for drum water level, and (iii) a new dynamic model for the flow of water in the downcomers. Implications of the model for control system design are explored in detail. Finally, the suggested improvements are validated in a sugar mill boiler (50 [MW] Babcock & Wilcox water-tube boiler).

Aspects of Two-Phase Flow Boiling Heat Transfer inside Tube of Water Tube Boiler—A Numerical Study

Aspects of Two-Phase Flow Boiling Heat Transfer inside Tube of Water Tube Boiler—A Numerical Study

Environmental and Energy Efficiency of Plywood Production Waste Burning

A comprehensive assessment of the energy and environmental efficiency of using plywood production waste as an energy fuel in steam watertube boilers units with a staged combustion scheme has been carried out. The components of the heat balance and emission of harmful substances are determined. The thermal engineering and granulometric characteristics, as well as the elemental composition of the combustible fuel and the formed focal residues, have been studied. Specific surfaces, porosity of entrainment particles were determined and their microscopic studies were performed. Specific surfaces, porosity of entrainment particles were determined and their microscopic studies were performed. It is concluded that it is necessary to modernize the ash cleaning system, and in the future to reconstruct boilers with the installation of tilt-pushing grids when implementing a layer-vortex combustion scheme.

Semi-supervised adaptive PLS soft-sensor with PCA-based drift correction method for online valuation of NOx emission in industrial water-tube boiler

The use of soft sensors for the prediction of Nitric Oxides (NOx) emissions to meet quality regulations has become increasingly attractive from the economic point of view. However, implementation of the standard adaptive PLS soft sensors such as the conventional adaptive block-wise recursive PLS (BW-RPLS) and just in time block-wise recursive PLS (JIT-BW-RPLS) to industrial boilers that are not equipped with an in-line hardware analyzer is impractical. This is due to the limited ability of the adaptive soft sensor to recalibrate without feedback from the actual NOx measurement. Hence, in this paper, a PCA-based drift correction method is proposed for an industrial water-tube boiler in which an in-line hardware analyzer is unavailable. The proposed drift correction factor is used to detect when drift happens and subsequently estimate the corrected NOx value to be used in a semi-supervised manner by the conventional BW-RPLS and JIT-BW-RPLS. Both the proposed semi-supervised BW-RPLS and JIT-BW-RPLS with PCA-based drift correction and estimation methods have displayed an additional 10–20% improvement in prediction accuracy relative to the performance of the conventional supervised BW-RPLS method and 50% prediction improvement compared to offline PLS model, during significant drifts in the industrial boiler operation. All the case studies have been performed using actual industrial data of a water-tube boiler.

АНАЛІЗ СИСТЕМИ ПАРАЛЕЛЬНОГО НЕЙРОУПРАВЛІННЯ ДИНАМІЧНИМИ ОБ'ЄКТАМИ

The article analyzes the effectiveness of the neural network control system, which together with the PIDcontroller implements the principle of parallel control of a dynamic object. As a rule, most industrialfacilities are characterized by non-linear dependencies, the presence of uncontrolled noise anddisturbances, frequent changes in equipment operating modes, and the presence of significant non-linearities. The model of the blowing subsystem of a water-tube steam boiler was used as an object ofresearch. The training of the neural network controller (NMC) and neuroemulator (emulator) was carriedout on the ACS model with a PID controller using the method of expert adjustment of tuning coefficients:proportionality, constant integration and differentiation based on the analysis of the quality indicators ofthe transition process. The change in the values of the object model parameters along the control anddisturbance channels corresponded to the dynamic modes of operation of the steam boiler in the range ofsteam load (25-110%) from the nominal one. The analysis of transient processes obtained on the basis ofcomputer modeling allows us to assert that the trained neural network control system compensates fordisturbances over the entire range of changes in the values of the object parameters along the control anddisturbance channels (simulation of changes in the steam load), as well as when the parameter values ofthe models go beyond the range study sample. Thus, the neural network controller can successfully perform the functions of an adaptive circuit tuned tothe most unfavorable disturbances in the ACS of parallel action by a complex production facility. And theimplementation of a neural network system of parallel action together with typical regulators in thetechnological processes of heat energy can reduce emergency situations associated with frequent changesin the steam load of power units caused by military actions in our country.

A generalised approach to the dynamic modelling of a water tube boiler

A generalised approach to the dynamic modelling of a water tube boiler

Metallurgical Case Studies of Early-in-Life Failures in Two Water-Tube Boilers

Metallurgical Case Studies of Early-in-Life Failures in Two Water-Tube Boilers

Analisis Efisiensi Water Tube Boiler Berbahan Bakar Fiber dan Cangkang Sawit di PT Dhamasraya Palma Sejahtera

Palm oil mill processing companies in their operations use Water Tube Boilers which are fueled by shells and fiber. Boiler or Steam Kettle is a container that contains water or other fluids to be heated. Boiler with a capacity of 30 tons. In general, every machine produced by the factory is always equipped with a handbook/instruction book on how to install, maintain and operate it. Likewise with the boilers in the Company there are manuals regarding specifications for operation, maintenance, installation, and others. of various kinds of boiler fuel mixtures for combustion can produce different thermic efficiencies depending on the percentage of the mixture, in this study the results of laboratory tests obtained the calorific value of the fuel mixture of 70% fiber and 30% shells had the highest calorific value, namely 4604.7 Cal /g. The highest boiler efficiency value produced was 53.9% using 100% shell fuel, the efficiency using 100% fiber fuel was 51% and the lowest boiler efficiency value produced was 49.5% using a mixed fuel of 70% fiber and 30 % shell.

Use of High-Frequency Ultrasound Waves for Boiler Water Demineralization/Desalination Treatment

Isolated ultrasonic vibrations were used to treat feed water from a 20 bar steam-producing water tube boiler. Physical treatments such as ultrasounds and reverse osmosis (RO) are recommended as the most eco-friendly for this purpose. A novel bench-scale prototype delivering 6 L/h of treated water was designed and built. The ultrasonic atomization of raw water with 1.7 MHz piezoelectric transducers and subsequent humidification and dehumidification of drag airflow was the innovating sequence of operations used as a treatment technique. To ensure greater humidification capacity to the drag air, the energy available from the thermal inertia of the liquid column (raw water) in the prototype vaporization chamber was used to heat this air flow. After a single pass of raw water through the bench-scale prototype, a 98.0% reduction in conductivity and a 99.0% decrease in the content of total dissolved solids were obtained at a drag air temperature of 70 °C. Compared to RO, two of the main advantages of the proposed ultrasonic wave method are the elimination of the use of chemical agents in the pre-treatment phase and a significant reduction in maintenance costs by membrane replacement.

Study on The Improvement of Heat Recovery Steam Generator Efficiency – A Review

Boilers are widely used in industries to produce steam. In some sectors, the steam generated is utilized directly in the production line for heating. Certain industries use steam to produce electricity. Fire tube boilers are limited to generating steam for processing; meanwhile, water tube boilers are widely used in electricity generation besides steam generation for processing lines. Subcritical boilers, supercritical boilers, and Heat Recovery Steam Generator (HRSG) are types of boilers commonly used to produce high capacity steam. This review article focuses on the optimization of HRSG operational efficiency. Industry players are keen on the improvement of operational efficiency since these directly influence the operating cost. Steam pressure, steam output, heat transfer efficiency and temperature distributions are key areas comprehensively reviewed in this article. Generally, improvement studies on boilers are not feasible to conduct during operation. Therefore, the scaled-down model used in the experiment or the boilers CFD models are simulated to understand the characteristics of the boilers. This review article is expected to overview HRSG boiler efficiency improvements and factors influencing boiler operational parameters.

Dynamic modeling of a water tube boiler

AbstractThe present work aims to develop an integrated heat transfer and hydrodynamic model for the study of boiler dynamics in fluctuating load conditions. A transient heat transfer model has been developed to estimate water side heat transfer and it is directly integrated with the hydrodynamic model. Two independent natural circulation circuits for furnace water wall and convection tube bank have been considered due to differences in heat transfer, dryness fraction, and void fraction. The transient heat transfer model calculates the heat transfer and water wall temperature of the various sections to calculate total gas side heat transfer, gas temperature profile, and waterside heat transfer in the furnace water wall and convection tube bank. Mass momentum and energy conservation equations are generated for both natural circulation circuits using the estimated value of waterside heat transfer of the transient heat transfer model. These equations are integrated with mass and energy conservation equations for the drum below water level and drum above water level to generate a system of equations to estimate drum pressure and water level fluctuation. This model has been extended for boiler feedback control systems, including the load management and the water level control system.

Permeation Behavior of Oxide Bonded SiC Ceramics at High Temperature and Prediction of Pressure Drop in Candle Filters

Oxide-bonded silicon carbide supports of porosity ranging from 33% to 47% were prepared by heating powder compacts (SiC, clay and alumina) at 1400°C in air with graphite acting as a pore former. The supports were spray-coated with an aqueous slurry of fine SiC powder (d50=15 μm), then sintered to produce a filtering layer with thickness ranging from 116 to 200 μm and average pore size ranging from 5 to 20 μm. Airflow tests were performed on both supports and coated filters at temperatures ranging from 25° to 700°C and superficial velocities ranging from 0.02 to 0.9 m.s−1. Experimental permeability coefficients were used to simulate the pressure drop behavior of hypothetical candle filters for industrial combustion/gasification processes (biomass combustion in water-tube steam boilers (BCSB), pressurized fluidized-bed combustion (PFBC) and integrated gasification combined cycle (IGCC)). The simulated permeation properties of the hypothetical candles were compared to those of commercial hot gas filters.

An innovative conversion of a district heating water-tube boiler for cogeneration of electricity and heat

The primary goal of combined heat and power (CHP) generation is to increase the overall efficiency of the process, which is primarily achieved by reducing energy losses associated with a single generation. The research aims to verify the possibility of adapting the district heating hot water cycle into the CHP plant through thermodynamic and techno-economic analyses. A complete layout of the innovative conversion as well as technical limits and possibilities are discussed. The manuscript presents a method of obtaining cogeneration conditions, therefore simultaneous production of heat and electricity in a cycle where the heat source is a water boiler. The solution from the thermodynamic and financial point of view has been proven on the example of the WR25 stoker boiler, for which the system produces 0.5 MWe with a simultaneous increase in the efficiency of the unit and no additional restrictions on its operation. At the same time, methods for further increasing the electric power without additional modernizations in the system were presented.