Advanced cracking evaluation

In steady-state FCC operation with heavy cycle oil (HCO) recycling, it is conceivable that some hydrocarbon molecules could go through the riser multiple times. We developed a two-pass scheme that combines the Davison circulation riser (DCR) and advanced cracking evaluation (ACE) unit to simulate the recycling operation. 

Catalyst hydrothermal deactivation was carried out in two different equipments a lOOg capacity fixed bed steamer was used for the advanced cracking evaluation (ACE) unit tests and a 5 kg capacity fluidized bed steamer was used for the other testing protocols. Steaming conditions in the two cases were the same 788°C for 5 hours under 100% steam flow. Although conditions were similar, higher pressure buildup in the fixed bed steamer led to lower surface area retentions. 

An advanced cracking evaluation-automatic production (ACE Model AP) fluidized bed microactivity unit was used to study the catalyst and feed interactions. The fluidized bed reactor was operated at 980°F (800 K). Every feed was tested on two different catalysts at three cat-to-oil ratios 4, 6, and 8. Properties of laboratory... 

Advanced testing for extensive evaluation of selected catalysts and feedstocks was carried out in a fixed fluid bed of about one liter cracking catalyst capacity. This provided us with representative yields and large volumes for product quality testing including octane numbers. In construction and operation, this test equipment was similar to that used much earlier to develop the semisynthetic catalysts of the 1950s.(7)... 

Several hydrocarbon processes are available for upgrading resid hydrotreating, Fluid Catalytic Cracking (FCC), coking etc., some more capital intensive than others. The most widely prevalent process is the FCC process. Therefore any advances in processing resid in FCC units will have wide application. This paper deals with concepts for developments in resid cracking, particularly in resid FCC development, evaluation and application. 

The use of CeOs-based materials in catalysis has attracted considerable attention in recent years, particularly in applications like environmental catalysis, where ceria has shown great potential. This book critically reviews the most recent advances in the field, with the focus on both fundamental and applied issues. The first few chapters cover structural and chemical properties of ceria and related materials, i.e. phase stability, reduction behaviour, synthesis, interaction with probe molecules (CO. O2, NO), and metal-support interaction — all presented from the viewpoint of catalytic applications. The use of computational techniques and ceria surfaces and films for model catalytic studies are also reviewed. The second part of the book provides a critical evaluation of the role of ceria in the most important catalytic processes three-way catalysis, catalytic wet oxidation and fluid catalytic cracking. Other topics include oxidation-combustion catalysts, electrocatalysis and the use of cerium catalysts/additives in diesel soot abatement technology. 

Zhang Shihai, Qin Weizu and Zhang Tao. Evaluation on cracking performance of concrete at early age-the advances of uniaxial restrained test method. China Concerete and Cement Products 2002 ... 

The evaluation of the specimens in any corrosion test must be appropriate for the type of corrosion that actually occurs on the samples. In many cases, the actual sample evaluation requirements will not be known until the samples are retrieved and examined visually. This can complicate the administration of the testing program as the cost of specimen evaluation and the time to perform the evaluation cannot be planned in advance. For example, if general corrosion is the only form of corrosion experienced, the cost of sample evaluation by mass loss measurement is relatively inexpensive, whereas a form of corrosion such as stress corrosion cracking may require a high cost evaluation. 

In certain zones such as embedded items areas would create where stresses in concrete are unacceptable reinforcement may be arranged to reduce these stresses. Due to temperature hot spots may occur in concrete zones which could be unacceptable. The stresses could be high. By providing some of these local reinforcement will reduce stresses to acceptable values in concrete. The most appropriate technique is to use advance analytical means such as finite element. Stress trajectories with and without reinforcement could be developed. These stress trajectories would determine the sizes and the zones to which these reinforcement could form shapes. The extent of such reinforcement will have bond lengths between 24 and 48 diameters of the bar. Obviously these reinforcement would be evaluated under prestressing anchorages too to avoid cracks under stressing loads. 

In addition, crack advance occurs in environmental conditions that may be very different from those that prevail on free surfaces, and this is to be considered when evaluating the relevance of a SCC mechanism. 

Figure 5-47. Film rupture/slip dissolution mechanism Evaluation of crack advance using Faraday s law (Ford, 1982 b).

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