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Oil Refining
Published in Nwanosike-Warren Quinta, Oil and Gas Engineering for Non-Engineers, 2022
Cracking is a refining process used to “crack” hydrocarbons or break them into smaller, less complex, and more valuable molecules using pressure and high temperatures up to 930°F. Hydrocracking uses hydrogen and a catalyst, while catalytic cracking uses an acid catalyst to break down hydrocarbons. Catalytic cracking is carried out in a unit called the fluid catalytic cracker (FCC). Residual oil from the vacuum distillation unit is cracked in a coker unit. Cracking results in production of gasoline, diesel, fuel oil, and petroleum coke. Petroleum coke is a carbon-rich solid. It is used as fuel in place of coal, or to make anodes for the production of aluminum and steel.
Crude Oil Refining—Part 2
Published in Hussein K. Abdel-Aal, Economic Analysis of Oil and Gas Engineering Operations, 2021
Actual refinery operations are very complicated, but the basic functions of the refinery can be broken down into three categories of chemical processes: Distillation involves the separation of materials based on differences in their volatility. This is the first and most basic step in the refining process, and is the precursor to cracking and reforming.Cracking involves breaking up heavy molecules into lighter (and more valuable) hydrocarbons.Reforming involves changing the chemical nature of hydrocarbons to achieve desired physical properties (and also to increase the market value of those chemicals).
Petroleum Wastewater
Published in Arun Kumar, Jay Shankar Singh, Microalgae in Waste Water Remediation, 2021
Cracking is used to convert the distillation fractions of crude oil to produce the required products as per the demand in the market. It could be divided in to thermal and catalytic cracking; in which catalytic cracking is often used. Catalytic cracking involves higher temperatures of 850-950°F and lower pressure of 10-20 psi. The common catalysts such as zeolite, aluminum hydrosilicate, bauxite, silica-alumina, treated bentonite clay and fuller’s earth are used in the form of powders, beads, pellets or shaped materials called extrudites. This process changes the molecular structure of hydrocarbon compounds, and further converts the heavier fractions into lighter fractions such as LPG, kerosene, gasoline, heating oil and petroleum feed stocks. In addition to cracking, there are other catalytic activities like dehydrogenation, hydrogenation and isomerization that are also followed.
Advances and challenges in the generation of bio-based fuels using gasifiers: a comprehensive review
Published in International Journal of Ambient Energy, 2020
Mohit Sharma, Rajneesh Kaushal
Cracking means splitting up of a large molecule into smaller molecules. In this process, heavy aromatic tar breaks into lighter compounds such as carbon monoxide, methane and hydrogen at a temperature around 1000°C (Abuadala and Dincer 2010).Thermal cracking usually takes place at a temperature above 1200°C. The temperature required for thermal cracking depends on the constituents present in tar for example tar rich in oxygen breaks at around 900°C (Stevens 2001). Cracking of tar has also been done with electric arc plasma but with this approach, the gas produced has less energy content. There are several precincts allied with thermal cracking (1) requirement of high-temperature bearable material for cracking equipment. (2) Melting of ash at a higher temperature. (3) The gas produced need to be cooled effectively (Asadullah 2014)
Catalytic pyrolysis of olive cake and domestic waste for biofuel production
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2018
There are several reported routes for turning waste and biomass resources into biofuels such as extraction under continuous pressure shock waves (Maroušek 2013, 2014; Maroušek et al. 2013) and gasification (Aljbour and Kawamoto 2013). In addition, pyrolysis is one of the promising practices for the production of chemicals and/or energy. Pyrolysis can be enhanced under catalytic conditions. Catalysts help in enhancing the pyrolysis reaction kinetics by cracking down higher molecular weight hydrocarbon compounds to lighter hydrocarbon products. It has been reported that the use of the catalyst in pyrolysis systems can greatly influence the composition, quality, and yield of products (Murugan, Ramaswamy, and Nagarajan 2009; Williams 2013). Several examples of catalysts have been reported in the literature for the pyrolysis of biomass and other related wastes (Agblevor et al. 2016; Boxiong et al. 2007; Chusaksri et al. 2004; Kar 2011; Shah, Jan, and Mabood 2009; Williams and Brindle 2003; Zhang et al. 2008).
Effect of mastic specifications on the fatigue and low-temperature performance of hot mix asphalt
Published in International Journal of Pavement Engineering, 2023
Ramin Rasouli, Alireza Khavandi Khiavi
Cracking as the most prevailing distress of asphalt mixture affects pavement performance due to water penetration and poor riding quality (Rahbar-Rastegar and Daniel 2016). Cracking is categorised into two main groups: fatigue and thermal cracking. Fatigue cracking forms due to the critical tension strains under or surface of the asphalt layer (bottom-up cracking) or within the wheel path on the asphalt layer (top-down cracking). Under repetitive loading, those cracks can grow and eventually lead to the deterioration of the pavement. Thermal cracking which appears as transverse cracking at the pavement surface is also the most common failure at low-temperature in asphalt mixture (Rahbar-Rastegar et al.2017, Du et al.2021).