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1

Calculation of the furnace exit gas temperature of stoker fired boilers

Rutkowski Łukasz, Szczygieł Ireneusz

Archives of Thermodynamics

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2021

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Vol. 42, no 3

3--24

EN

In the paper the methodology of furnace exit gas temperature calculations by using well known normative standard method CKTI is presented. There are shown changes in methodology approach for three editions of it and in additional developments. Furnace exit gas temperature for two stoker grate boilers is calculated. By using described methods, it was possible to determine their effectiveness by comparing with measurements. Knowledge of the furnace exit gas temperature allows to define the division into irradiated and convection surfaces, which has an impact on the design features of the boiler as well as its dimensions and weight.

2

Mineral movement simulation through the grates and pulp lifter in a SAG mill and evaluation for a new grate design using DEM

Gutierrez Alejandro Guillermo

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 3

617--630

EN

Nowadays computer simulations have been shown to be powerful tools to understand the performance of systems where we have mathematical models that can capture the physics of the problem. In this paper we attempt to simulate the behavior of the particles that move inside a large- scale mine mill, specifically through the grates and the discharge ducts of the material, when small changes are made in the geometry of the grates. Basically, the continuity, energy and momentum conservation equations are the ones that can solve the behavior of the material in that zone. The discrete element method is used to carry out the simulation, under the hypothesis that the restitution coefficient can substitute for the presence of the fluid inside the mill, and that by changing the angle of inclination of the grate slots the performance can improve the classification that they make and in the total discharge flow. A corollary of this study is that the pulp-lifters have a greater impact than the grates in improving the discharge flow. It was possible to quantify phenomena like flow-back and carry-over, effects that are not evaluable experimentally, in this way showing the usefulness of this simulation. The application of the DOE method has allowed to back up statistically the results and indicate that the slot angle increases the mill’s outlet flow.

3

Numerical calculations of WR-40 boiler based on its zero-dimensional model

Hernik B.

Chemical and Process Engineering

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2014

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Vol. 35, nr 2

173--180

EN

Generally, the temperature of flue gases at the furnace outlet is not measured. Therefore, a special computation procedure is needed to determine it. This paper presents a method for coordination of the numerical model of a pulverised fuel boiler furnace chamber with the measuring data in a situation when CFD calculations are made in regard to the furnace only. This paper recommends the use of the classical 0-dimensional balance model of a boiler, based on the use of measuring data. The average temperature of flue gases at the furnace outlet t”k obtained using the model may be considered as highly reliable. The numerical model has to show the same value of t”k. This paper presents calculations for WR-40 boiler. The CFD model was matched to the 0-dimensional t”k value by means of a selection of the furnace wall emissivity. As a result of CFD modelling, the flue gas temperature and the concentration of CO, CO2, O2 and NOx were obtained at the furnace chamber outlet. The results of numerical modelling of boiler combustion based on volumetric reactions and using the Finite Rate/Eddy-Dissipation Model are presented.

4

Model of waste combustion on the grate

Jaworski T.

Architecture Civil Engineering Environment

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2009

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Vol. 2, no. 4

125-130

EN

The algorithm describing mass transport on the reciprocal moving and drum grates have been presented. Three main processes are taken into account: combustion of a single fuel particle, porous structure of the fuel layer and fuel transport on the grate and their mutual relations were analyzed. Each process is described by its own model: reactor, fuel particle, heat transfer and chemical reaction. The model describing the grate is designed as similar to the chemical reactor and the cascade of batch reactors simulates the transport on the grate.

PL

W pracy przedstawiono algorytm opisujący transport masy na rusztach posuwistych, posuwisto – zwrotnych i walcowych. Struktura modelu oparta jest na trzech głównych blokach zagadnień do których należą: spalanie pojedynczego ziarna paliwa, przestrzeń porowata w warstwie oraz analiza ruchu ziaren na ruszcie. Określono system powiązań parametrycznych w/w zagadnień. Każde z zagadnień wymaga opisu za pomocą podmodeli, są nimi: podmodel reaktora, paliwa (odpad/cząstka), transportu ciepła oraz reakcji. Zastosowano podobieństwo modelu rusztu do modelu reaktora chemicznego. Użyto kaskadę reaktorów zbiornikowych w dyskretyzacji warstwy.

5

Konstrukcje nośne z płyt g-k

Rekucki Z.

Izolacje

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2005

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R. 10, nr 2

38--40

PL

Zabudowa z zastosowaniem płyt g-k wymaga wykonania ażurowej konstrukcji nośnej, do której płyta będzie zamocowana. Konstrukcję tę często nazywa się rusztem z racji podobieństwa do tak nazwanego układu statystycznego.