Modeling fine particles and alkali metal compound behavior in a kraft recovery boiler

TAPPI Journal ◽  
2012 ◽  
Vol 11 (7) ◽  
pp. 9-14 ◽  
Author(s):  
AINO LEPPÄNEN ◽  
ERKKI VÄLIMÄKI ◽  
ANTTI OKSANEN
Keyword(s):  
Alkali Metal ◽  
Computational Models ◽  
Fine Particles ◽  
Black Liquor ◽  
Melting Behavior ◽  
Metal Compound ◽  
Effect Of Temperature ◽  
Particle Model ◽  
Boiler Furnace ◽  
Recovery Boiler

Under certain conditions, ash in black liquor forms a locally corrosive environment in a kraft recovery boiler. The ash also might cause efficiency losses and even boiler shutdown because of plugging of the flue gas passages. The most troublesome compounds in a fuel such as black liquor are potassium and chlorine because they change the melting behavior of the ash. Fouling and corrosion of the kraft recovery boiler have been researched extensively, but few computational models have been developed to deal with the subject. This report describes a computational fluid dynamics-based method for modeling the reactions between alkali metal compounds and for the formation of fine fume particles in a kraft recovery boiler furnace. The modeling method is developed from ANSYS/FLUENT software and its Fine Particle Model extension. We used the method to examine gaseous alkali metal compound and fine fume particle distributions in a kraft recovery boiler furnace. The effect of temperature and the boiler design on these variables, for example, can be predicted with the model. We also present some preliminary results obtained with the model. When the model is developed further, it can be extended to the superheater area of the kraft recovery boiler. This will give new insight into the variables that increase or decrease fouling and corrosion

scholarly journals Improving recovery boiler availability through understanding fume behavior

TAPPI Journal ◽  
2016 ◽  
Vol 15 (3) ◽  
pp. 187-193 ◽  
Author(s):  
AINO LEPPÄNEN ◽  
ERKKI VÄLIMÄKI
Keyword(s):  
Flow Field ◽  
Alkali Metal ◽  
Flue Gas ◽  
Inorganic Compounds ◽  
Black Liquor ◽  
Computational Method ◽  
Metal Vapors ◽  
Recovery Boilers ◽  
Recovery Boiler ◽  
Elemental Release

Unexpected recovery boiler shutdowns are rare, but they can cost millions of dollars in lost income. Sometimes the inorganic compounds in black liquor can cause sudden fouling or plugging problems that could not be predicted beforehand. The ash particles can be divided into two main types and size classes: carryover and fume. This paper focuses on the smaller fume particles that form through the condensation of alkali metal vapors and that deposit via different mechanisms than carryover. The location of fume deposition depends on several factors, such as flue gas and superheater temperatures, black liquor composition, and the flow field in the boiler. This paper presents results obtained with a computational method that simulates fume formation in recovery boilers. The paper focuses on the effect of black liquor composition and elemental release on fume behavior and suggests how these observations should be taken into account when designing new boilers or retrofits. Moreover, the paper introduces the possible applications of the modeling method. These include, for example, troubleshooting of fouling problems in existing boilers, designing superheater configurations for new boilers, and positioning soot blowers.

Dimensioning a recovery boiler furnace using mathematical optimization

TAPPI Journal ◽  
2015 ◽  
Vol 14 (2) ◽  
pp. 119-129 ◽  
Author(s):  
VILJAMI MAAKALA ◽  
PASI MIIKKULAINEN
Keyword(s):  
Radial Basis Function Network ◽  
High Capacity ◽  
Mathematical Optimization ◽  
Optimization Procedure ◽  
Optimization Method ◽  
Performance Criteria ◽  
Boiler Furnace ◽  
Starting Point ◽  
Recovery Boiler ◽  
Base Design

Capacities of the largest new recovery boilers are steadily rising, and there is every reason to expect this trend to continue. However, the furnace designs for these large boilers have not been optimized and, in general, are based on semiheuristic rules and experience with smaller boilers. We present a multiobjective optimization code suitable for diverse optimization tasks and use it to dimension a high-capacity recovery boiler furnace. The objective was to find the furnace dimensions (width, depth, and height) that optimize eight performance criteria while satisfying additional inequality constraints. The optimization procedure was carried out in a fully automatic manner by means of the code, which is based on a genetic algorithm optimization method and a radial basis function network surrogate model. The code was coupled with a recovery boiler furnace computational fluid dynamics model that was used to obtain performance information on the individual furnace designs considered. The optimization code found numerous furnace geometries that deliver better performance than the base design, which was taken as a starting point. We propose one of these as a better design for the high-capacity recovery boiler. In particular, the proposed design reduces the number of liquor particles landing on the walls by 37%, the average carbon monoxide (CO) content at nose level by 81%, and the regions of high CO content at nose level by 78% from the values obtained with the base design. We show that optimizing the furnace design can significantly improve recovery boiler performance.

Biosludge Incineration in a Recovery Boiler

1999 ◽  
Vol 40 (11-12) ◽  
pp. 195-200 ◽  
Author(s):  
P. Harila ◽  
V.-A. Kivilinna
Keyword(s):  
Black Liquor ◽  
Pulp Mill ◽  
Effluent Treatment ◽  
Attractive Alternative ◽  
Net Energy ◽  
High Moisture ◽  
Primary Sludge ◽  
Start Up ◽  
Combustion Emissions ◽  
Recovery Boiler

An activated sludge process is an effective tool against effluent emissions in a pulp mill. It has only a few features which can be regarded deficiences. One of them is that effluent treatment of a modern pulp mill creates some 10-20 tonnes dry solids of biosludge per day. This sludge is difficult to burn due to its high moisture content. The most common way is to mix biosludge with primary sludge, to dewater the mixture in presses and finally to burn it in a solid fuel boiler. This type of sludge treatment incurs rather high costs and does not produce any net energy. Also combustion emissions vary depending on the boiler type. The Metsä-Botnia Kemi Pulp Mill was the first mill in the world to burn biosludge in a recovery boiler. The system start-up was in 1993 and it has been in operation ever since. Mechanically dewatered biosludge is mixed with weak black liquor and concentrated in a conventional evaporation plant equipped with a pressurized superconcentrator unit. In a modern recovery boiler, firing conditions are well controlled and monitored. Better emission control than in most bark fired boilers is achieved. Accumulation of nonprocess elements, corrosion, plugging, scaling and some other operational problems were expected. A lot of experience has been gathered during the years of operation and reviewed in this presentation. The achieved benefits of the system are discussed. Disposal of biosludge in a recovery boiler offers an economically and environmentally attractive alternative. Probably the best evidence from this is the fact that Metsä-Botnia has applied the same process solution in the recent reconstruction of the recovery departments at the Jouteno Mill.

Numerical modeling for the effects of gravel permeability coefficient based on DEM and CFD method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Anan Zhang ◽  
Jie Yang ◽  
Chuihui Ma ◽  
Lin Cheng ◽  
Liangcai Hu
Keyword(s):  
Permeability Coefficient ◽  
Fine Particles ◽  
Simulation Method ◽  
Test Sample ◽  
Treatment Method ◽  
Particle Model ◽  
Equal Weight ◽  
Content Type ◽  
Seepage Characteristics ◽  
Element Method

Purpose The purpose of this paper is to form a numerical simulation method for permeability coefficient that can consider the characteristics of gravel gradation and further explore the effects of indoor test factors and gradation characteristics on the permeability coefficient of gravel. Design/methodology/approach The random point method is used to establish the polyhedral gravel particle model, the discrete element method (DEM) is used to construct the gravel permeability test sample with gradation characteristics and the finite element method is used to calculate the permeability coefficient to form a DEM-computational fluid dynamics combined method to simulate the gravel seepage characteristics. Then, verified by the indoor test results. Based on this method, the influence of sample size, treatment method of oversize particles and the content of fine particles on the permeability coefficient of gravel is studied. Findings For the gravel containing large particles, the larger size permeameter should be used as far as possible. When the permeameter size is limited, the equal weight substitution method is recommended for the treatment method of oversized particles. Compared with the porosity, the pore connectivity has a higher correlation with the permeability coefficient of the sample. Research limitations/implications Insufficient consideration of the movement of gravel particles in the seepage process is also an issue for further study. Originality/value The simulation method described in this paper is helpful for qualitative analysis, quantitative expression of pore size and makes up for the defect that the seepage characteristics in pores cannot be observed in laboratory tests.

scholarly journals Final technical report. In-situ FT-IR monitoring of a black liquor recovery boiler

1999 ◽  
Author(s):  
James Markham ◽  
Joseph Cosgrove ◽  
David Marran ◽  
Jorge Neira ◽  
Chad Nelson ◽  
...  
Keyword(s):  
Black Liquor ◽  
Technical Report ◽  
Ft Ir ◽  
Recovery Boiler ◽  
Black Liquor Recovery Boiler

Mechanism of Alkali Metal Compound-Promoted Growth of Monolayer MoS2: Eutectic Intermediates

2019 ◽  
Vol 31 (3) ◽  
pp. 873-880 ◽  
Author(s):  
Peng Wang ◽  
Jiayu Lei ◽  
Jiafan Qu ◽  
Shengyong Cao ◽  
Hu Jiang ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Metal Compound ◽  
Monolayer Mos2

Measurements in and Modeling of a Black Liquor Recovery Boiler

2008 ◽  
Vol 180 (3) ◽  
pp. 494-508 ◽  
Author(s):  
P. Fontes ◽  
M. Costa ◽  
J. L. T. Azevedo
Keyword(s):  
Black Liquor ◽  
Recovery Boiler ◽  
Black Liquor Recovery Boiler

Computational Models for High-Temperature Multilayered Composite Plates and Shells

1992 ◽  
Vol 45 (10) ◽  
pp. 419-446 ◽  
Author(s):  
Ahmed K. Noor ◽  
W. Scott Burton
Keyword(s):  
High Temperature ◽  
Computational Models ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Composite Plates ◽  
Effect Of Temperature ◽  
Temperature Sensitive ◽  
Composite Models ◽  
Sandwich Plates And Shells ◽  
Plates And Shells

The focus of this review is on the hierarchy of composite models, predictor-corrector procedures, the effect of temperature-dependence of material properties on the response, and the sensitivity of the thermomechanical response to variations in material parameters. The literature reviewed is devoted to the following eight application areas: Heat transfer; thermal stresses; curing, processing and residual stresses; bifurcation buckling; vibrations of heated plates and shells; large deflection and postbuckling problems; and sandwich plates and shells. Extensive numerical results are presented showing the effects of variation in the lamination and geometric parameters of temperature-sensitive angle-ply composite plates on the accuracy of thermal buckling response, and the sensitivity derivatives predicted by nine different modeling approaches (based on two-dimensional theories). The standard of comparison is taken to be the exact three-dimensional thermoelasticity solutions. Some future directions for research on the modeling of high-temperature multilayered composites are outlined.

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