Measurement of Thinned Water-Cooled Wall in a Circulating Fluidized Bed Boiler Using Ultrasonic and Magnetic Methods

In this paper, a nondestructive inspection system is proposed to detect and quantitatively evaluate the size of the near- and far-side damages on the tube, membrane, and weld of the water-cooled wall in the fluidized bed boiler. The shape and size of the surface damages can be evaluated from the magnetic flux density distribution measured by the magnetic sensor array on one side from the center of the magnetizer. The magnetic sensors were arrayed on a curved shape probe according to the tube’s cross-sectional shape, membrane, and weld. On the other hand, the couplant was doped to the water-cooled wall, and a thin film was formed thereon by polyethylene terephthalate. Then, the measured signal of the flexible ultrasonic probe was used to detect and evaluate the depth of the damages. The combination of the magnetic and ultrasonic methods helps to detect and evaluate both near and far-side damages. Near-side damages with a minimum depth of 0.3 mm were detected, and the depth from the surface of the far-side damage was evaluated with a standard deviation of 0.089 mm.

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Cross-Sectional Damage Localization and Quantification for Steel Cables Using MFL 3D Imaging Technique

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.281.55 ◽

2013 ◽

Vol 281 ◽

pp. 55-58

Author(s):

Dong Hwan Lee ◽

Ju Won Kim ◽

Chang Gil Lee ◽

Seung Hee Park ◽

Jong Jae Lee

Keyword(s):

Magnetic Flux ◽

Permanent Magnets ◽

Digital Signal ◽

Magnetic Flux Density ◽

Inspection System ◽

Steel Cable ◽

Cross Sectional ◽

Sensor Head ◽

Damage Level ◽

Steel Cables

In this study, a MFL (Magnetic Flux Leakage) based 3D inspection system which is incorporated into a cable climbing robot was investigated to monitor the healthy condition of steel cables. Firstly, a MFL sensor head prototype composed of two permanent magnets and eight hall sensors was designed and fabricated. A steel cable specimen with several types of damage, such as corrosion and cutting, was inflicted and scanned by the MFL sensor head to measure the magnetic flux density of the specimen. The measured MFL signals were used to interpret the healthy condition of the steel cable. For improving the resolution and quantification of the damage level, digital signal processing techniques were performed. In addition, the measured MFL signals were visualized into a 3D MFL map for real-time and online cable monitoring. This visualized MFL map can provide the information about location, shape and size of damages very intuitively. Finally, the results were compared with information on actual inflicted damages to confirm the accuracy and effectiveness of the MFL based cable inspection system.

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Gas Concentration Measurements in the Combustion Chamber of the 235 MWe Circulating Fluidized Bed Boiler Turow No. 3

18th International Conference on Fluidized Bed Combustion ◽

10.1115/fbc2005-78136 ◽

2005 ◽

Cited By ~ 1

Author(s):

E.-U. Hartge ◽

M. Fehr ◽

J. Werther ◽

T. Ochodek ◽

P. Noskievic ◽

...

Keyword(s):

Combustion Chamber ◽

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Wall Layer ◽

Front Wall ◽

Circulating Fluidized Bed Boiler ◽

Penetration Length ◽

Cross Sectional ◽

Gas Concentration ◽

High Concentrations

Local measurements of concentrations of O2, CO2, CO, NO and SO2 were carried out inside the 235 MWe circulating fluidized bed boiler no. 3 Turow power plant. The combustion chamber had a cross-sectional area of 21.1 × 9.9 m2 and a height of 43 m. Water-cooled probes with a length of 4.7 m were used to take samples from inside the boiler. 20 ports in 5 different heights were used to introduce the probes. The penetration depth inside the boiler was up to 3 m. The sampled gas was led to online analyzers. Even though the number of ports and the penetration length was not sufficient to get a full 3-D mapping of the concentrations the measured horizontal and vertical gas concentration profiles of NO, CO, CO2, O2 and SO2 clearly indicate a core/annulus structure with a wall layer thickness of about 0.5–1 m. Significant differences are observed between gas concentrations near the front wall and those near the rear wall which indicate an uneven distribution of fuel. One consequence is the formation of plumes with high concentrations of CO, NO, CO2 and SO2 near the front wall which extend up to the exit region. The fact that nevertheless the stack emissions are still below the legal limits may be attributed to the excellent performance of the cyclones as gas mixers and post combustion reactors.

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Cross Sectional Suspension Density along the Height of a CFB Riser under Fixed and Variable Bed Inventory Conditions

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.361-363.1882 ◽

2011 ◽

Vol 361-363 ◽

pp. 1882-1886

Author(s):

Jiraroch Somjun ◽

Anusorn Chinsuwan

Keyword(s):

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Average Diameter ◽

Sectional Area ◽

Cold Model ◽

Cross Sectional ◽

Density Profiles ◽

Suspension Density ◽

Bed Material ◽

Cross Sectional Average

Experiments were performed in a cold model circulating fluidized bed riser having a cross sectional area of 100 x100 mm2 and a height of 4800 mm. Sand having an average diameter of 231m was used as the bed material. The cross sectional average suspension density along the height of the circulating fluidized bed system with a smooth exit was investigated under fixed and variable bed inventory conditions. A model is proposed for predicting the density profiles in the two conditions.

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Investigation of Effects of Electrostatics on Cross Sectional Particle Distributionin Triple Bed Circulating Fluidized Bed (TBCFB)

Proceedings of the 5th Asian Particle Technology Symposium ◽

10.3850/978-981-07-2518-1_356 ◽

2012 ◽

Author(s):

Nivash Elango ◽

Alireza Rezvanpour ◽

Cheng Yongpan ◽

Chi-Hwa Wang

Keyword(s):

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Cross Sectional

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Design and Commissioning of the Largest and the Smallest Fluidized Bed Incinerator Ever Built by Lurgi

17th International Conference on Fluidized Bed Combustion ◽

10.1115/fbc2003-007 ◽

2003 ◽

Author(s):

H. Huenchen ◽

L. Pachmayer ◽

O. Malerius

Keyword(s):

Sewage Sludge ◽

Fluidized Bed ◽

Flue Gas ◽

Circulating Fluidized Bed ◽

Waste Material ◽

Design Parameters ◽

Cross Sectional ◽

Gas Cleaning ◽

Bubbling Bed ◽

Cleaning System

Since communities and companies are deciding to dispose sludges of different origin in a safe and nonpolluting way, more and more sludge is burnt either in mono-combustion or co-combustion units. Lurgi Energie und Entsorgung GmbH, one of the most experienced fluidized bed designer, is commissioning two bubbling bed incinerators of totally different incinerator size in 2002. In France the smallest fluidized bed incinerator ever built by Lurgi with a cross-sectional bed area of 4 m2 is designed to burn 750 kg (d.m.)/h sewage sludge. In spite of the small size it consists of all equipment necessary for sewage sludge incineration, including a disc dryer, a thermal oil boiler for heat recovery and a complete state of the art flue gas cleaning system. Air pollutants are removed in a circulating fluidized bed adsorber (CFB) designed in accordance with the new Lurgi CIRCOCLEAN® process. In United Kingdom the largest bubbling bed incinerator ever built by Lurgi with a cross-sectional bed area of 32 m2 is going to start its operation in 2002. The plant burns a mixture of thickened and mechanically dewatered primary and secondary sludge and different plastic residues from waste paper recycling plants. In order to provide sufficient disposal capacity of the waste material generated at the Kemsley Paper Mill site some parts of the installation consist of parallel streams or units (e. g. waste material handling and storage). The overall design throughput rate of mixed waste material is 22.8 t(a.r.)/h, corresponding to a thermal load of 29.1 MW. Due to the specific properties of the paper sludge, the formed ash can be used as an adsorbent/reactive compound for the capture of acidic pollutants. The flue gas cleaning system consists of a zeolite dosing unit to remove dioxins/furanes upstream of a baghouse filter. The paper presents the main design parameters of both disposal facilities and peculiarities of the burnt materials in comparison to other sludges. Since the plants are still in the commissioning phase only problems that might occur during the operation of the plant and tendencies in the operation behavior are described.

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A Model to Predict Radial Solids Holdup and Liquid Velocity Distributions in Liquid-Solid Circulating Fluidized Bed

Chemical Product and Process Modeling ◽

10.2202/1934-2659.1081 ◽

2007 ◽

Vol 2 (3) ◽

Author(s):

Natarajan Palani ◽

Velraj R. ◽

Seeniraj R.V.

Keyword(s):

Experimental Data ◽

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Liquid Velocity ◽

Two Phase ◽

Cross Sectional ◽

Operating Variables ◽

Solids Holdup ◽

Cross Sectional Average ◽

Good Agreement

A general expression which is useful for predicting the radial distributions or for analyzing and interpreting experimental data is derived for a liquid-solid circulating fluidized bed. The effect of both the radial liquid velocity and solids holdup distributions are taken into account in the analysis. Both effects are analyzed and are related to the operating variables of superficial liquid velocity, jl, superficial solids velocity, js, and cross-sectional average solids holdup. The results predicted by the analysis are compared with the experimental data obtained for various two-phase flow regimes, when different solids and bed dimensions are applied. The model predictions show good agreements with the experimental data and reasonable trends when different solids and bed dimensions are applied. Stronger non-uniformities in flow structures are found in larger size particles systems, with larger solids density and/or larger diameter columns. Radial solids holdup distribution is related with the cross-sectional average solids holdup. Good agreement with data and reasonable trends are observed.

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Study of Phase Distribution of a Liquid-Solid Circulating Fluidized Bed Reactor Using Abductive Network Modeling Approach

Chemical Product and Process Modeling ◽

10.1515/cppm-2013-0008 ◽

2013 ◽

Vol 8 (2) ◽

pp. 77-91 ◽

Cited By ~ 1

Author(s):

Shaikh A. Razzak

Keyword(s):

Fluidized Bed ◽

Network Model ◽

Circulating Fluidized Bed ◽

Phase Distribution ◽

Network Modeling ◽

Absolute Error ◽

Pilot Scale ◽

Cross Sectional ◽

Modeling Approach ◽

Abductive Network

Abstract This communication deals with the Abductive Network modeling approach to investigate the phase holdup distributions of a liquid–solid circulating fluidized bed (LSCFB) system. The Abductive Network model is developed/trained using experimental data collected from a pilot scale LSCFB reactor involving 500-μm size glass beads and water as solid and liquid phases, respectively. The trained Abductive Network model successfully predicted experimental phase holdups of the LSCFB riser under different operating parameters. It is observed that the model predicted cross-sectional average of solids holdups in the axial directions and radial flow structure are well agreement with the experimental values. The statistical performance indicators including the mean absolute error (~4.67%) and the correlation coefficient (0.992) also show favorable indications of the suitability of Abductive Network modeling approach in predicting the solids holdup of the LSCFB system.

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A 3D Model of Combustion in Large-Scale Circulating Fluidized Bed Boilers

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1135 ◽

2004 ◽

Vol 2 (1) ◽

Cited By ~ 11

Author(s):

Karsten Luecke ◽

Ernst-Ulrich Hartge ◽

Joachim Werther

Keyword(s):

Combustion Chamber ◽

Fluidized Bed ◽

Large Scale ◽

Gas Flow ◽

Circulating Fluidized Bed ◽

Combustion Process ◽

Three Dimensional ◽

Three Dimensional Model ◽

Cross Sectional ◽

Secondary Air

In a circulating fluidized bed (CFB) combustor the reacting solids are locally fed into the combustion chamber. These reactants have to be dispersed across the reactor's cross-sectional area. Since the rate of mixing is limited this leads to a mal-distribution of the reactants and to locally varying reaction conditions. In order to describe the influence of mixing a three-dimensional model of the combustion chamber is suggested. The model is divided into three sub-topics. First, the flow structure in terms of local gas and solids velocities and solids volume concentrations is described. Second, mixing of the solids and the gas phase is quantified by defining dispersion coefficients, and finally the combustion process itself, i.e. the reaction kinetics, is modelled. The model was validated against data from measurements in the large-scale combustor of Chalmers University of Technology in Göteborg/Sweden. Insufficient fuel mixing generated mal-distributions of locally released volatiles, which were the basis for the uneven reactants distribution at steady-state. In the case of two-stage operation, the injected secondary air did not reach immediately the reactor's center but was slowly mixed with the main gas flow. The concentration gradients hardly vanish before the exit of the combustion chamber.

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