A Review on the Production of Light Olefins Using Steam Cracking of Hydrocarbons

Light olefins are the main building blocks used in the petrochemical and chemical industries for the production of different components such as polymers, synthetic fibers, rubbers, and plastic materials. Currently, steam cracking of hydrocarbons is the main technology for the production of light olefins. In steam cracking, the pyrolysis of feedstocks occurs in the cracking furnace, where hydrocarbon feed and steam are first mixed and preheated in the convection section and then enter the furnace radiation section to crack to the desired products. This paper summarizes olefin production via the steam cracking process; and the reaction mechanism and cracking furnace are also discussed. The effect of different operating parameters, including temperature, residence time, feedstock composition, and the steam-to-hydrocarbon ratio, are also reviewed.

Study of SCC of X70 Steel Immersed in Simulated Soil Solution at Different pH by EIS

An electrochemical study of stress corrosion cracking (SCC) of API X70 steel in a simulated soil solution at different pH values (3, 8 and 10) was carried out. The stress conditions were implemented by slow strain rate stress test (SSRT) and the SCC process was simultaneously monitored by electrochemical impedance spectroscopy (EIS). Fracture surface analysis and corrosion product analysis were performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results show that the susceptibility to SCC was higher as the pH decreases. In the acid solution, hydrogen evolution can occur by H+ and H2CO3 reduction, and more atomic hydrogen can diffuse into the steel, producing embrittlement. EIS results indicated that the anodic dissolution contributed to SCC process by reducing the charge transfer resistances during the SSRT test. While SEM micrographs shown a general corrosion morphology on the longitudinal surface of samples. At higher pH (pH 8 and pH 10), the SCC susceptibility was lower, which it is attributed to the presence of corrosion products film, which could have limited the process. Using the angle phase (φ) value it was determined that the cracking process started at a point close to the yield strength (YS).

Pengaruh Perbandingan Katalis ZSM-5 dengan Katalis Alumina terhadap Pembentukan Biofuel dengan Bahan Baku Minyak Jelantah

The average consumption rate of cooking oil in Indonesia on 2019 was 61 million litre. Because of that makes the waste cooking oil produces very high to. To prevent the consument littering the waste cooking oil, we can recycle it to be biofuel with many fraction such as biodiesel, biogasoline, and biokerosene. There are many ways to process the waste cooking oil to be, biofuel one of them is catalytic cracking. This study is induct by observe the biofuel that form from the catalytic cracking process with cooking oil as the base material using a hybrid catalyst ZSM-5/Alumina. The purpose of this study is to observe the influence of ZSM-5 and Alumina ratio as heterogenic catalyst and also the used of the catalyst frequently. The highest conversion of liquid product was produce with value 41,67% at alumina variation of 17,5%. The used of catalyst frequently will affect the decrease amount of liquid product that produce. The analysis of chemical properties using GC-MS obtained the amount of kerosene 29,917 %; gasoline 3,996 %; and diesel 10,1 %. The other product was carboxylics acids,alcohol, and unidentified compound. Keyword : Cooking oil, biofuel, ZSM-5, Alumina, catalytic cracking

Effect of Recycled Polymer Waste on Paraffinic Oil

Plastics has become the necessity of our daily life. Its production and consumption has been rising rapidly due to its wide range of application in the domestic and industrial usage. But due to its non-biodegradable nature, it cannot be easily decomposed in the environment and hence is a major issue of Environment pollution. So, nowadays new technology is being used to treat the waste plastic by a known chemical reaction - pyrolysis. Under the pyrolytic conditions and cracking process, the plastic wastes can be decomposed into three different states thereby the converted product can be reused in different processes. The waste plastics consisting of high-density polyethylene (HDPE) was pyrolyzed using catalyst and the recovered crude was analyzed and used as flow improvers. The liquid hydrocarbons obtained from the Pyrolysis of waste polymer products was used as diluent to change the characteristics of crude oil. The aim of the research work is to evaluate the change in the flow when blended with the Crude oil of different place. The Crude oil was Blended with the recycled diluents were in different fractions of 5%, 15%, and 25% of diluent. The plastic pyrolysis oil were then tested in a with fractions of 5, 10 and 15 volume% of diluent and their performance and characteristics analyzed and compare with it. Keywords: Catalyst, Paraffinic Oil, Recycled waste, Pour Point, Blended Oil

A Spiral Distributed Monitoring Method for Steel Rebar Corrosion

This paper proposes a novel spiral-wound, optic-fiber sensor to monitor the corrosion of steel bars. At the same time, the winding parameters, such as winding angle and pitch, were first theoretically deduced. Then, to decrease light loss, a practically distributed sensor wound onto the protective mortar layer was developed by increasing the winding curvature radius. The spiral distributed sensors were experimentally verified for their feasibility. Experimental results showed that the spiral fiber strain depended on the thickness of the protective mortar layer. Furthermore, the spiral distributed strain well reflected the cracking process of concrete. In addition, the concrete cracking time depended on the thickness of the protective concrete layer. Accordingly, this method is feasible for evaluating the initial and final cracking behaviors of concrete structures and provides a sight for steel bar corrosion.

Effect of Salt Content on the Evaporation and Cracking of Soil from Heritage Structures

The degree of damage to heritage structures in arid areas can be particularly serious due to long-term exposure to a harsh arid climate. In this paper, the characteristics of evaporation and cracking of soil taken from heritage structures with different NaCl concentrations are experimentally investigated by subjecting saturated soil samples taken from the Wang-Jing tower in Weihui City, Henan Province. Making soil sample of water content of 110% is used to test the rate of evaporation at a constant temperature and humidity, through which the changes in the evaporation rate, water content, fracture development, and fracture fractal dimension are obtained. The results show that, (1) with higher water content, NaCl can affect the evaporation process by increasing the matrix suction of the soil of the Wang-Jing tower and then affect the cracking process of soil. When 0%, 1%, 2%, and 4% NaCl are added, the residual water content of the samples is 3.15%, 4.23%, 4.82%, and 5.89%, respectively, which show an obvious trend of increasing water content; (2) the period with a stable fracture fractal dimension of the samples is shortened with an increase in NaCl concentration, and its maximum fractal dimension is reduced in turn; and (3) at a lower water content, NaCl crystallizes and precipitates in the pores of the soil, which provide a cementitious effect among the soil particles, thus inhibiting crack development.

Feedback Analysis and Prevention & Control Strategy of the Real Causes of the Gallery Cracks in Super-High Arch Dam

Gallery cracks occur commonly in concrete dams, but their cracking mechanism has yet to be effectively revealed. In this paper, the actual temperature, stress change history and cracking process of a gallery area were uncovered, based on the safety monitoring data of cracks in a super-high arch dam. In addition, the basic development and change laws, as well as the corresponding cracking mechanism, were analyzed, and the real causes and influential factors of cracks at the site were revealed, which will provide a reference for the prevention of cracks in similar projects in the future.