MATHEMATICAL MODELLING OF UTILIZATION WASTE GASES FROM INDUSTRIAL FURNACES

Combustible waste gases are by-products of many technological processes. They vary in their calorific value and are used to decrease the usage of gases whose calorific value is higher. Coke oven gas from the coking process and process gases from an electric furnace in a copper plant are examples of such gases. Composition and calorific value of coke oven gas depend on coking parameters as well as on the type and quality of coal. The most common process where the coke oven gas is used is the process of heating combustion air in a heat regenerator. The gases from the electric furnace (due to low calorific value) require post combustion at the beginning of their disposal process. The paper addresses mathematical modelling of a coke oven battery regenerator as well as mathematical modelling of post combustion and cooling the electric furnace process gases. The regenerator mathematical model was elaborated for the simplified geometry of a real object making the assumptions for the heat transfer equations. The post combustion and cooling processes of the electric furnace gases are modelled with the aid of the Ansys software. This software was used for both elaborate simplified geometry of the analysed object and carry out the simulations. Mathematical description of occurring processes includes in this case combustion, turbulence and heat transfer

Determination of the Interzonal Airflows in Naturally Ventilated Dwellings Based on Concentration Measurements of the Metabolic Carbon Dioxide

The role of interzonal airflows is especially pronounced in naturally ventilated buildings. In such buildings, reversed airflows in the ventilation stacks might occur as well. This affects the air exchange rate and contaminant distribution in buildings. A significant increase in carbon dioxide concentration is a characteristic phenomenon for poorly ventilated rooms. This paper demonstrates the application of metabolic carbon dioxide concentration measurements for interzonal airflow estimation in naturally ventilated buildings. The presented method is based on the continuous measurements of CO2 concentration at one point in each zone. These measurements are used to estimate airflow pattern in a multizone building by applying an inverse analysis. The developed methodology employs an iterative Levenberg-Marquardt procedure to maximise the nonlinear likelihood function. The validity of the method was verified against measurements carried out in a single naturally ventilated room. Further, the method was applied to calculate the airflow pattern in two apartments in Poland, containing 4 and 6 zones. The obtained results revealed very poor ventilation in both investigated apartments and reversed airflow in exhaust ducts. The amount of fresh air entering the rooms was insufficient to ensure good indoor air quality. The developed methodology can be effectively used as a diagnostic tool to identify the potential problems with ventilation systems

Application of inverse methodology to estimation of chloride diffusion coefficient in concrete of prestressed precast slab

Work presents an investigation of chloride penetration of HC-500 prestressed concrete slabs made of precast concrete. This type of concrete slabs is widely used to construct floors in steel or reinforced concrete framing buildings. In such solutions ceiling can be considered as a simple-supported beam. Considered precast concrete was made of C50/C60 concrete with use of Portland cement CEM II 52.5 R. Investigated specimens were sampled directly from the upper part of prestressed concrete slabs. The process of chloride penetration in concrete can be described by the non-linear diffusion equation. In the paper Bayesian inverse technique was applied to estimate diffusion coefficient of chloride in concrete treated as a saturated porous material. Unknown distribution of estimated parameters was sampled with use of Metropolis-Hastings algorithm which allowed us to obtain unknown values and their error bounds. Obtained values of diffusion coefficient were confronted against values obtained with use of norms: NT BUILD 443 and ASTM C 1556 - 03 and against previously developed methodology based on the analytical solution of the diffusion equation

Numerical Analysis of the Impact of the Use of Personal Protective Equipment on the Face in the Process of Pollutants Spreading Emitted During Breathing

The study presents the results of a numerical analysis of the effectiveness of the use of personal protective equipment of various designs on the spread of pollutants marked with CO2 emitted during human breathing. In the study of 3D geometry the upper part of the human torso and head was developed. The simulated person was supplied with different personal protective equipment covering the human face (PPE). Two types of face shields worn at a different distance from the face and one fabric face mask was analysed. The reference geometry with no personal protective equipment was also analysed. Transient calculation with full breathing model including breath-in and breath-out and species transport were simulated. The results showed that different PPE generates different airflow patterns in the vicinity of the human face. The most efficient in reducing infection risk is by wearing a face mask or face shields at a small distance from the face, as they most effectively reduce CO2 concentration in the surrounding air. However, they also increase the re-inhalation risk of high CO2 concentration which affects human well-being

Numerical modelling and experimental validation of the pneumatic powder injection into liquid alloys

322-328The pneumatic powder injection is well-known and widely used with injection lances submerged into metal bath. However, sometimes better is to not introduce the lance below the liquid metal surface because of the metal splashing and introducing of gases into metal volume. In such a case non-submerged lance is used but the problem with particles jet penetration into the metal volume appears. This paper presents the results of the studies on the pneumatic powder injection with non-submerged lance. The high-speed camera recording of the model diphase jet leaving the lance is carried out. Then image analysis is performed to estimate real particles motion parameters. Furthermore, the jet cone is analysed to check its character of development and compared with the reported results in the literature. The results are obtained that the particles real velocity is smaller than calculated from typically used formulas. The same with cone angles – it seems to be different than quoted in the literature. Next stage is numerical modelling using AnSys software. The results were compared with the experiments and the model is adjusted. The next stage is ferroalloy “cold” injection and again the computer modelling. The last stage is FeSi injection into grey iron experiments. The analysis of the results is combined both with the laboratory results and modelling then compared with previous data. As a consequence the validated numerical model is obtained which can be helpful for the injection process planning in industrial conditions

Experimental and numerical analysis of the biomass innovativ solar pyrolysis process

Paper present the experimental and numerical analysis of biomass photopyrolysis process. The experimental tests is performed on the solar pyrolysis installation, designed in Institute of Thermal Technology, Gliwice. It consist of the copper reactor powered by artificial light simulating sun. The paper shows the result of the solar pyrolysis of wood. The yield of the main fraction as a function of the process temperature is presented. Additionally the gas composition is determined. The numerical model is prepared in the Ansys Fluent 18.2 software, which allow at the same time for capturing geometry of the real system and easy change of input data. The results indicate that both the product yields (liquid, solid and gaseous) and gas components shares are strongly influenced by pyrolysis parameters and feedstock composition