A three dimensional numerical model of the heat exchange during a charge heating process in a pusher furnace, using the finite element method, was used in this study. The radiative heat exchange in ...the furnace chamber was carried out based on two methods: the zone method and the method of basing on the average configuration ratio. In the zone method the flux of radiation energy reaching the surface of the heated charge was determined by performing calculations of brightness in a multi-surface closed system which is the pusher furnace chamber filled with an emitting-absorbing medium. In the second case an average configuration ratio was used by setting the radiation energy flux through linking the walls temperature with the furnace atmosphere temperature.
W pracy wykorzystano trójwymiarowy model numeryczny wymiany ciepła w czasie nagrzewania wsadu w piecu przepychowym przy zastosowaniu metody elementów skończonych. Radiacyjną wymianę ciepła w komorze pieca realizowano w oparciu o dwie metody: metodę strefową oraz w oparciu o średni współczynnik konfiguracji. W metodzie strefowej strumień energii radiacyjnej docierającej do powierzchni nagrzewanego wsadu wyznaczano prowadząc obliczenia jasności w wielo-powierzchniowym układzie zamkniętym jakim jest komora pieca przepychowego wypełnionego ośrodkiem emitująco-pochłaniającym. W drugim przypadku wykorzystano średni współczynnik konfiguracji wyznaczając strumień energii radiacyjnej poprzez powiązanie temperatury ścian z temperaturą atmosfery pieca.
A three dimensional numerical model of the heat exchange during a charge heating process in a pusher furnace, using the finite element method, was used in this study. The radiative heat exchange in ...the furnace chamber was carried out based on two methods: the zone method and the method of basing on the average configuration ratio. In the zone method the flux of radiation energy reaching the surface of the heated charge was determined by performing calculations of brightness in a multi-surface closed system which is the pusher furnace chamber filled with an emitting-absorbing medium. In the second case an average configuration ratio was used by setting the radiation energy flux through linking the walls temperature with the furnace atmosphere temperature.Original Abstract: W pracy wykorzystano trojwymiarowy model numeryczny wymiany ciepla w czasie nagrzewania wsadu w piecu przepychowym przy zastosowaniu metody elementow skonczonych. Radiacyjna wymiane ciepla w komorze pieca realizowano w oparciu o dwie metody: metode strefowa oraz w oparciu o sredni wspolczynnik konfiguracji. W metodzie strefowej strumien energii radiacyjnej docierajacej do powierzchni nagrzewanego wsadu wyznaczano prowadzac obliczenia jasnosci w wielo-powierzchniowym ukladzie zamknietym jakim jest komora pieca przepychowego wypelnionego osrodkiem emitujaco-pochlaniajacym. W drugim przypadku wykorzystano sredni wspolczynnik konfiguracji wyznaczajac strumien energii radiacyjnej poprzez powiazanie temperatury scian z temperatura atmosfery pieca.
El siguiente trabajo muestra un modelo numérico de un horno de recalentamiento tipo empujador, utilizando un programa comercial de dinámica de fluidos (CFD). El modelo acopla las ecuaciones de ...transferencia de calor, dinámica de fluidos y reacción química en estado no estacionario. Para la simulación de la combustión se utilizó el modelo de transportes de especies Eddy-dissipation; para la dinámica de fluidos de los gases se hizo uso del modelo k - e realizable. Se simuló la transferencia de calor considerando los mecanismos de conducción, convección y radiación. El modelo P-1 fue utilizado para simular la radiación que aportan los gases de combustión al calentamiento de la palanquilla. Las historias térmicas simuladas al interior de las palanquillas fueron comparadas con mediciones en planta. El modelo también acopla los modelos de oxidación superficial de la carga (barras de sección cuadrada de acero de 160 mm x 160 mm x 12.7 m). Se caracterizó el historial térmico en estado no estacionario de una palanquilla cuadrada de 16 mm y 12.7 m, durante su desplazamiento en el interior del horno, estas mediciones de temperatura permitieron caracterizar las pérdidas de material por formación de óxidos, en cada tiempo y posición al interior del horno de calentamiento.
The paper deals with the application of roof flat-flame burners in the pusher-type steel slab reheating furnaces, after furnace reconstruction and replacement of conventional torch burners, with the ...objective to increase the efficiency of radiative heat transfer from the refractory roof to the charge. Based on observations and on measurements of the construction and process parameters under operating conditions, the advantages and disadvantages of indirectly oriented radiant heat transfer are analysed in relation to the heat transfer in classically fired furnaces.
Carbon dioxide is a major source of the green house effect and, therefore, fuel saving techniques are expected to reduce emissions. Yet, in some cases, energy saving techniques may result in higher ...CO
2 emissions. For instance, when natural gas is mixed with waste blast furnace gas, energy savings are associated with higher CO
2 emissions. To confirm this proposition we have constructed a model of a furnace by using energy-object network that consists of modules of convective heat exchangers, combustion and stream mixing.
Primjena stropnih radijacijskih gorionika u velikim potisnim pećima. U radu je obrađena primjena stropnih plosnato plamenih plamenika, koji su ugrađeni u zagrijevne potisne peći umjesto ...konvencionalnih bočnih plamenika, u svrhu veće učinkovitosti prijenosa topline zračenjem od vatrostalnog stropa prema ulošku. Na osnovi spoznaja do kojih se došlo promatranjem i mjerenjem konstrukcijskih i procesnih parametara u radnim uvjetima, analizirane su prednosti i nedostatci ovog neizravno orijentiranog načina prijenosa topline zračenjem u odnosu na prijenos topline u pećima zagrijavanim na klasičan način.
Modern heating furnaces use combined modes of heating the charge. At high heating temperatures, more radiation heating is used; at lower temperatures, more convection heating is used. In large ...heating furnaces, such as pusher furnaces, it is necessary to monitor the heating of the material zonally. Zonal heating allows the appropriate thermal regime to be set in each zone, according to the desired parameters for heating the charge. The problem for each heating furnace is to set the optimum thermal regime so that at the end of the heating, after the material has been cross-sectioned, there is a uniform temperature field with a minimum temperature differential. In order to evaluate the heating of the charge, a mathematical model was developed to calculate the heat fluxes of the moving charge (slabs) along the length of the pusher furnace. The obtained results are based on experimental measurements on a test slab on which thermocouples were installed, and data acquisition was provided by a TERMOPHIL-stor data logger placed directly on the slab. Most of the developed models focus only on energy balance assessment or external heat exchange. The results from the model created showed reserves for changing the thermal regimes in the different zones. The developed model was used to compare the heating evaluation of the slabs after the rebuilding of the pusher furnace. Changing the furnace parameters and altering the heat fluxes or heating regimes in each zone contributed to more uniform heating and a reduction in specific heat consumption. The developed mathematical heat flux model is applicable as part of the powerful tools for monitoring and controlling the thermal condition of the charge inside the furnace as well as evaluating the operating condition of such furnaces.
The article presents innovative technology which integrates a metallurgical pusher-type furnace with a waste heat recovery system that consisted of a reactor for torrefaction and pyrolysis of waste ...biomass. The technology is designed for utilizing both liquefied and gaseous by-products (torgas, pyrolysis gas and condensate denoted as TPC) obtained from torrefaction and pyrolysis of waste biomass. TPC is considered to be applied as an additional fuel for a metallurgical furnace as an example of effective energy management in metallurgical industry. In detail, the technology contains waste heat recovery unit installed on the furnace smoke stack as the heat source for the pyrolysis/torrefaction reactor. The analysis was carried out for a pusher furnace, fed optionally with either natural gas or coke gas. Share of this gaseous/liquid TPC fuel from waste in the total fuel mixture fed to the furnace was varied from 5 to 15% by volume. Practical usefulness of TPC fuel was tested on a specially constructed test stand. Financial analysis in energy consumption and economy of using the obtained TPC fuel for co-combustion with coke gas in the metallurgical pusher furnace was carried out on the basis of data from a steel sheet roller combined with the pusher furnace located in one of large steel works. It was shown that the use of this TPC fuel derived from thermal treatment of waste biomass and other organic substances can be considered an effective method of reducing production costs in the analyzed steel company and can lead to increase in the attractiveness of their products and thus strengthen their competitiveness on the global market.
Graphic abstract
The method of calculation of heating of metal in the thermal furnace taking into account pulse system of heating is presented in article. The experimental dataobtained on the pusher furnace, heated ...by high-speed recuperative torches with pulse system of burning of fuel are submitted.
This article presents the results of numerical calculations of chemical composition of flue gas produced by combustion of natural gas in an industrial heating device, i.e., a pusher furnace. In ...calculations of combustion chemistry, the CHEMKIN-PRO program was used. The gas-dynamic of flue gas was modeled with the use of the COMSOL Multiphysics program. In order to check the correctness of the plug flow reactor (PFR) model, as applied in calculations, a preliminary laboratory experiment was conducted. Based on measurement data that were obtained during the research on a laboratory stand, the boundary conditions were formulated and numerical simulations were carried out. The temperature and velocity profiles in the combustion chamber were determined with the use of the COMSOL program and were implemented in the CHEMKIN program. The obtained results of the numerical simulations performed in the experimental chamber showed high compliance with the results of measurements. This, in turn, led us to apply the analysis on a real object. The simulations of the chemical composition of flue gas in the each zone of the furnace were carried out based on the measurements data collected from the real object, i.e., a pusher furnace that is currently working in one of the steel plants located in our country.
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