Investigation into the Distribution of Erosion-Corrosion in the Furnace Tubes of Oil Refineries

Crude oil is one of the most important sources of energy in the world. To extract its multiple components, we need oil refineries. Refineries consist of multiple parts, including heat exchangers, furnaces, and others. It is known that one of the initial operations in the refineries is the process of gradually raising the temperature of crude oil to 370 degrees centigrade or higher. Hence, in this investigation the focus is on the furnaces and the corrosion in their tubes. The investigation was accomplished by reading the thickness of the tubes for the period from 2008 to 2020 with a test in every two year, had passed from their introduction into the work. Where the thickness of more than one point was measured on each tube in the same row and the corrosion rate was extracted for three furnaces, starting from the area of ​​heat transfer by radiation to the heat transfer area of ​​the convection in three different operating units. It was found that the highest percentage corrosion value between the standard tube thickness and the thickness of conduction position was 37% with the conduction zone, and 31% with radiation zone. There, the tubes specification was tested. Five percent Cr-0.5 Moly and the temperature of radiation zone was 578 °C to 613 °C and the stack temperature was 410 °C to 450 °C. So, the results show that the maximum erosion occur at the convection zone.

Mathematical modeling of heating of coal particle within the space between electrodes of arc-heating reactor

A mathematical model of heating of coal particles that move in the initial section of a submerged gas jet within the space between electrodes of reaction chamber of arc-heating reactor is created. The model takes into account convective heat transfer and heat transfer by radiation from a sphere (particle) – circle (anode) system. The temperatures of particles on mechanical trajectory are obtained depending on particle diameters and the initial coordinate of nozzle leaving.

Numerical Calculation of Radiative Heat Transfer in Two-dimensional Rectangular Zone

The accuracy of the P1-approximation of the spherical harmonic’s method and the S2-approximation of the discrete ordinate method for calculating heat transfer by radiation are analyzed. The cases of an isotropically scattering homogeneous medium and a homogeneous absorbing medium are considered. The calculation results are compared with the exact solution, the P3-approximation and the zonal method. It is shown that the accuracy of the S2-approximation is higher compared to the P1-approximation at small and intermediate values of the optical thickness of the medium.

Radiation of Heat in an Insulating Vacuum Layer

The paper is motivated by the previous research concerning the heat transfer in a heat accumulation device. The device had been explored, built up and tested with the aim of utilization of cheap solar energy and its storage. In this heat storage system, a vacuum-like gap between two concentric containers acts as an insulating layer, radiation being the predominant heat transfer type in the gap. The better knowledge and understanding of the heat exchange by radiation, the more effectiveness of the insulation of the layer can be reached. Heat transfer by radiation is explored in the paper, mathematical model is set up, the algorithm of non-linear transient computation is introduced, and some illustrative results of this computation are performed.

EXPERIMENTAL ANALYSIS OF THE INFLUENCE OF HEAT SINK GEOMETRIC PARAMETERS ON NATURAL CONVECTION

In this work, the steady state heat transfer by natural convection in heat sinks with rectangular fins positioned vertically and horizontally was studied. The heat transfer by radiation was also considered. Several analyses were performed to determine the optimal number and position of the sensors used to measure the temperature on the heat sinks horizontally and vertically positioned. These analyses confirmed an almost uniform temperature distribution in the heat sink. This uniformity allowed the use of thermocouples only in the center of the heat sink. Twelve heat sinks were designed to study how their geometric parameters such as height, spacing and thickness of the fins, influence the heat transfer by free convection. In addition, in this work, two correlations using the dimensionless parameters Nusselt and Rayleigh are proposed. These correlations were obtained by using the results from the 12 heat sinks vertically and horizontally positioned considering a temperature range between 20 °C and 100 °C. Furthermore, studies were done to identify which of the 12 analyzed heat sinks managed to remove the greatest amount of heat in a given temperature range. The results were compared with those obtained from empirical correlations found in literature.