Determination of Key Parameters Required to Optimize Calcination Process in Ferrous Metallurgy Heating Plants

2021 ◽  
Vol 316 ◽  
pp. 282-287
Author(s):  
Boris Yur'ev ◽  
Vyacheslav Dudko
Keyword(s):  
Heat Transfer ◽  
Ferrous Metallurgy ◽  
Construction Material ◽  
Heat Transfer Process ◽  
Operating Conditions ◽  
Shaft Kiln ◽  
Thermal Calculations ◽  
Carbonate Decomposition ◽  
Rotary Kilns

Lime is the product of calcination. Its formation is always related to removal of carbon dioxide generated in the course of carbonate decomposition. Ferrous metallurgy, construction material, chemical and food industry companies account for about 90 % of lime produced in the country. Ferrous metallurgy is the major consumer of commercial lime using up to 40 % of all produced lime. Currently, despite occurrence of new binding and artificially produced chemical compounds, lime remains the major chemical compound produced by the industry in terms of output. Various units (shaft, rotary tubular kilns and fluidized bed kilns) are used for calcination. Shaft kilns are used the most widely. Considering continuously growing demand for lime, the need occurs for intensification of the burning process and optimization of the shaft kiln operating conditions. This requires knowledge of calcination physicochemical and heat transfer process mechanisms. Thus, the work deals with the issues related to determination of the optimal specific fuel consumption for burning of limestone from a particular deposit. It may be done only basing on thermal calculations for an operating shaft kiln, what, in its turn, causes the need for determination of the whole set of limestone and lime heat transfer properties. The obtained work results may be used to optimize the operating conditions of not only shaft but also rotary kilns intended for limestone heat treatment.

Heat Transfer Characteristics of a Radial Jet Reattachment Flame

1997 ◽  
Vol 119 (2) ◽  
pp. 258-264 ◽  
Author(s):  
J. W. Mohr ◽  
J. Seyed-Yagoobi ◽  
R. H. Page
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Combustion Process ◽  
Local Heat ◽  
Operating Conditions ◽  
Recirculation Region ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Impingement Surface

A Radial Jet Reattachment Combustion (RJRC) nozzle forces primary combustion air to exit radially from the combustion nozzle and to mix with gaseous fuel in a highly turbulent recirculation region generated between the combustion nozzle and impingement surface. High convective heat transfer properties and improved fuel/ air mixing characterize this external mixing combustor for use in impingement flame heating processes. To understand the heat transfer characteristics of this new innovative practical RJRC nozzle, statistical design and analysis of experiments was utilized. A regression model was developed which allowed for determination of the total heat transfer to the impingement surface as well as the NOx emission index over a wide variety of operating conditions. In addition, spatially resolved flame temperatures and impingement surface temperature and heat flux profiles enabled determination of the extent of the combustion process with regards to the impingement surface. Specifically, the relative sizes of the reaction envelope, high temperature reaction zone, and low temperature recirculation zone were all determined. At the impingement surface in the reattachment zone very high local heat flux values were measured. This study provides the first detailed local heat transfer characteristics for the RJRC nozzle.

scholarly journals DETERMINATION OF THE COEFFICIENT OF HEAT TRANSFER DURING COOLING OF SILVER THERMO PROBES, TAKING INTO ACCOUNT THE EFFECTS OF TEMPERATURE-TIME DELAY

2017 ◽  
Vol 39 (5) ◽  
pp. 41-47 ◽  
Author(s):  
E. N. Zotov ◽  
A. A. Moskalenko A.A. ◽  
O. V. Rasumtseva ◽  
L. M. Protsenko
Keyword(s):  
Heat Transfer ◽  
Heat Flux Density ◽  
Cooling Capacity ◽  
Heat Transfer Process ◽  
Special Program ◽  
Nonstationary Heat Transfer ◽  
Density Surface ◽  
Effects Of Temperature ◽  
Temperature Time

Existing methods for determining the characteristics of the nonstationary heat transfer process (temperature field, heat transfer coefficient, heat flux density, surface temperature) are considered and analyzed when cooling silver spherical and cylindrical thermo-probes. New analytical solutions are proposed using a special program IQLab, which increase the accuracy of calculations when testing the cooling capacity of various liquids. The results of the calculations are compared with the experimental data.  

Electron Heat Transfer in a Quiescent Nonequilibrium Plasma

1970 ◽  
Vol 92 (3) ◽  
pp. 447-455 ◽  
Author(s):  
E. V. McAssey ◽  
Hsuan Yeh
Keyword(s):  
Heat Transfer ◽  
Nonequilibrium Plasma ◽  
Spherical Body ◽  
Operating Conditions ◽  
The Body ◽  
Electron Heat ◽  
Wide Range ◽  
Weakly Ionized ◽  
Body Potential

An asymptotic solution has been obtained for the electron heat transfer to a spherical body immersed in a weakly ionized, quiescent plasma. Dimensional analysis of the governing equations shows that the problem can be divided into two regions: charge-separated and quasi-neutral. For the charge-separated region, the equations must be solved numerically, whereas the quasi-neutral solution can be expressed in closed form. From these studies it was found that the extent of the charge-separated region (i.e, sheath) is of the order of Λ2/3. Within the sheath the effects of ionization and recombination are of the order of Λ4/3. The results include the variation of electron flux, electron heat transfer, and current as a function of body potential. The results are presented in a form to permit the easy determination of the electron heat transfer to a body immersed in a quiescent, weakly ionized plasma over a wide range of operating conditions. Furthermore, the electrical characteristics presented here can be used in conjunction with electron heating data to treat the body as a probe for diagnostic purposes.

ΕΞΕΤΑΣΗ ΦΑΙΝΟΜΕΝΩΝ ΘΕΡΜΙΚΗΣ ΑΚΤΙΝΟΒΟΛΙΑΣ ΣΕ ΕΣΤΙΕΣ ΣΤΕΡΕΟΥ ΚΑΥΣΙΜΟΥ

1998 ◽  
Author(s):  
Ιωάννης Μαράκης
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Transfer Equation ◽  
Radiative Transfer Equation ◽  
Operating Conditions ◽  
Radiative Properties ◽  
Band Model ◽  
Combustion Chambers ◽  
Practical Applications

THEMATIC AREA OF THIS THESIS IS THE HEAT TRANSFER IN COMBUSTION CHAMBERS. THE ORIGINALITY ITEMS ARE CONCERNED WITH THE DEVELOPMENT OF ACCURATE METHODS BOTH FOR THE CALCULATION OF THE FLUE GAS AND COMBUSTION PARTICLE RADIATIVE PROPERTIES, AS WELL AS THE SOLUTION OF THE RADIATIVE TRANSFER EQUATION IN FURNACE - LIKE ENCLOSURES. SPECIFICALLY, THIS WORK CONTRIBUTES TO THE EXACT DETERMINATION OF THE INFLUENCE THAT THE TEMPERATURE AND PRESSURE OPERATING CONDITIONS HAVE ON THE RADIATIVE FLUXES AND SOURCE TERMS, THE LATTER BEING THE NET THERMAL ENERGY EMITTED OR ABSORBED PER UNIT VOLUME. THE THESIS INCLUDES THE DEVELOPMENT OF TWO METHODS FOR THE SOLUTION OF THE RADIATIVE TRANSFER EQUATION (A MONTE CARLO VARIANT AND A NEW INTEGRAL METHOD NAMED DIRECT NUMERICAL INTEGRATION),TWO STATISTICAL NARROW BAND AND A WIDE BAND MODEL FOR THE CALCULATION OF THE NON - GRAY GAS SPECTRAL TRANSMISSIVITY, AN ALGORITHM BASED ON MIE THEORY FOR THE DETERMINATION OF THE ABSORPTION AND SCATTERING COEFFICIENTS, THE PHASE FUNCTION AND THE ASYMMETRY PARAMETER OF COAL, CHAR, FLY - ASH AND SOOT PARTICLES AND CORRELATIONS FOR THE RESPECTIVE SPECTRAL OPTICAL PROPERTIES. THE EXACT SOLUTION OF THE THERMAL RADIATION TRANSFER HAS SIGNIFICANT PRACTICAL APPLICATIONS, SUCH AS: 1) DESIGN OF COMBUSTION CHAMBERS AND HEAT TRANSFER SURFACES, 2) DETERMINATION OF THE RADIATIVE FLUX AT THE BOUNDARIES OF A GIVEN GEOMETRY (ABSTRACT TRUNCATED)

INFLUENCE OF VAPOR AND CRYSTAL FORMATION PROCESSES ON HEAT EXCHANGE IN FILM VAPORATORS

2021 ◽  
pp. 32-40
Author(s):  
O. Koshelnik ◽  
V. Pavlova ◽  
T. Pugacheva ◽  
O. Kruglyakova ◽  
O. Dolobovska
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Energy Consumption ◽  
Heat Exchange ◽  
Solid Phase ◽  
Heat Transfer Process ◽  
Operating Conditions ◽  
Crystal Formation ◽  
Phase Content ◽  
Three Phase

Evaporators for changing the concentration of solutions have a different design, depending on the type of processed substance. Significant energy consumption in such equipment is associated with the need for removing large quantity of liquid phase. Multiple-effect evaporators are used to reduce the energy consumption of the evaporation process, but such equipment is quite expensive. Evaporators with secondary vapor heat reusing that operate in film mode can be an alternative to multi-effect evaporators. This equipment can operate efficiently across minimal temperature differences due to secondary vapor compressors. The disadvantage of this device is strict requirements for impurities in solutions. Impurities create deposits (incrustations) of various substances on the heat transfer surfaces, which worsens the operating conditions. If crystallizing solutions are used in evaporators with reusing of secondary vapor heat, then one of the ways to reduce the rate of heating surfaces incrustation is to add a solid phase to the initial solution. A mathematical model is proposed to describe the processes of heat and mass transfer during the film flow of crystallizing solutions, which are accompanied by a change in the physical characteristics of the solution and the formation of deposits. The model considers a three-phase liquid suspension with a varying phase content. Two stages of vaporization including vaporization on the surface of the liquid and on the surface of heat exchange are presented. The mathematical model involves the equations of continuity, energy and heat transfer, as well as the equations of motion of a three-phase flow with a changing phase content for both stages of vaporization, taking into account that solid phase turbulizes the flow and intensifies the heat transfer process. This mathematical model makes it possible to study the effect of the solid phase on heat transfer processes and the rate of incrustation in evaporators with reuse of secondary vapor heat.

scholarly journals Experimental determination of the heat transfer coefficient in internally rifled tubes

2019 ◽  
Vol 23 (Suppl. 4) ◽  
pp. 1163-1174
Author(s):  
Slawomir Gradziel ◽  
Karol Majewski ◽  
Marek Majdak
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Experimental Determination ◽  
Transfer Process ◽  
Circulating Fluidized Bed ◽  
Thermal Power ◽  
Heat Transfer Process ◽  
The Heat Transfer Coefficient

Development of the heat transfer surfaces on the tube inside makes it very difficult or even impossible to determine the heat transfer coefficient analytically. This paper presents the experimental determination of the coefficient in an internally rifled tube with spiral ribs. The tests are carried out on a laboratory stand constructed at the Institute of Thermal Power Engineering of the Cracow University of Technology. The tube under analysis has found application in a supercritical circulating fluidized bed boiler. The heat transfer coefficient local values are determined for the Reynolds numbers included in the range of ~6000 to ~50000 and for three ranges of the heating elements power. As the medium flows through internally rifled tubes with spiral ribs, the heat transfer process gets intensified compared to similar processes taking place in smooth tubes. Based on the obtained experimental data, a correlation is developed enabling determination of the dimensionless Chilton-Colburn j factor. The equation form is selected so that a comparison with existing results of tests performed on rifled tubes can be made. Comparing the Nusselt number values calculated based on the developed correlation with those obtained using other correlations described in the literature, it can be observed that the criterial number is about twice higher. The research results confirm the thesis that the element internal geometry has a sub-stantial impact on the heat transfer process.

scholarly journals Optimization of Ventilation Spacer for Direct-Drive Permanent Magnet Wind Generator

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1430 ◽  
Author(s):  
Xiang Zhao ◽  
Yu Fan ◽  
Weili Li ◽  
Dong Li ◽  
Junci Cao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Permanent Magnet ◽  
Heat Transfer Process ◽  
Calculation Model ◽  
Direct Drive ◽  
Thermal Fields ◽  
Wind Generator ◽  
Flow And Heat Transfer ◽  
Thermal Calculations ◽  
Heat Transfer Capacity

As the rated capacity of the Direct-Drive Permanent Magnet Wind Generator (DDPMWG) increases, the heat produced from the generator’s inner components also increases and it becomes difficult to transfer the inner heat to the ambient. The ventilation spacer has a significant influence on the heat transfer process of DDPMWG. Thus, this paper focuses on the optimization of the ventilation spacer on the thermal field of DDPMWG. Firstly, the fluid flow and heat transfer coupled numerical calculation model is established. The physical model, composed of two half-slots and one tooth of DDPMWG, is established due to the structural symmetries to save the calculations. The sources and boundary conditions for the thermal calculations are also given. Five new ventilation spacers, compared with the original one, are proposed to investigate the thermal fields. The pressure drop and temperature field are compared to find the optimized ventilation spacer for the DDPMWG. The criteria are also presented for judging the heat transfer capacity. To validate the optimized ventilation spacer, the temperature rises of the armature winding with original and optimized ventilation spacers are measured. It proves that the armature winding’s temperature rise of the optimized ventilation spacer is about 4.7 K lower than that with the original ventilation spacer.

The dynamic response of towed thermometers

1968 ◽  
Vol 34 (3) ◽  
pp. 449-464 ◽  
Author(s):  
A. G. Fabula
Keyword(s):  
Heat Transfer ◽  
Dynamic Response ◽  
Diffusion Layer ◽  
Water Layer ◽  
Heat Transfer Process ◽  
Operating Conditions ◽  
Temperature Fields ◽  
Small Scale ◽  
Layer Model ◽  
Buoyant Plumes

Small-scale temperature fields in water were used to test the dynamic response of towed thermometers of the platinum film resistance type. Laminar buoyant plumes rising from submerged heaters below the line of motion were the test temperature fields. The analysis of results was based on an approximate ‘diffusion-layer’ model of the dynamic heat-transfer process occurring near the platinum film on the probe tip. The model represents the linear heat transfer into a two-layer semi-infinite medium, with the platinum thin film located at the interface between a water layer of thickness Δ and a semi-infinite substrate of glass. The differences of the thermal properties of water and glass were found to be negligible. The characteristic time Δ2/D, where D is the thermal diffusivity of water, was determined by the ratio of actual to film-indicated plume-peak temperature, assuming a sinusoid approximation to the plume profile. The frequency response for the same operating conditions as the plume tests could then be obtained from the diffusion-layer model.

Determination of Heat Transfer Coefficients Around a Blade Surface From Temperature Measurements

1979 ◽  
Author(s):  
D. K. Mukherjee
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Main Stream ◽  
Blade Surface ◽  
Transfer Coefficients ◽  
Gas Turbine Blades ◽  
Heat Transfer Coefficients

To design cooled gas turbine blades, heat transfer coefficients around its surface are required. The calculated heat transfer data under operating conditions in the turbine are often inaccurate and require experimental verification. A method is presented here to determine the heat transfer coefficients around the blade surface and in the coolant channels. This requires measurements of the main stream and coolant temperatures together with the outer surface temperature distribution at varying mass flows. In order to conduct these tests in a gas turbine, test blades have to be specially prepared allowing the variation and measurement of coolant mass flow.

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