High-temperature cracking

High temperature cracking or coking, polymer buildup 0.02-0.06 ... 

Manufacture Made by thermal (high-temperature) cracking in the presence of steam of any available low-cost hydrocarbon such as ethane and propane, naphthas (C5-C10), and so-called gas oils (C10-C30). Many other organic compounds are produced during the cracking step, depending on the starting material fed to the reactor (cracker). CH3 CH3 CH2=CH2-PH2... 

In Figures 18.18, 18.19 and 18.20 the experimental data and the calculations based on model I are shown for the high temperature cracking at 360, 397 and 420 T of an Athabasca oil sands bitumen (Drum 20). Similar results are seen in Figures 18.21, 18.22 and 18.23 for another Athabasca oil sands bitumen (Drum 433). The estimated parameter values for model I are shown in Table 18.3 for Drums 20 and 433. 

Table 18.3 Estimated Parameter Values for Model l for High Temperature Cracking of Athabasca Oil Sands Bitumen...

Figure 18.18 Experimental and calculated concentrations of Coke (COK) "a ", Asphaltene (ASP) "o and Heavy Oil -i Light Oil (HO+LO) " at 360 °C for the high temperature cracking of Athabasca oil sands bitumen (Drum 20) using mode /.

Hanson, K. and N. Kalogerakis, "Kinetic Reaction Models for Low Temperature Oxidation and High Temperature Cracking of Athabasca and North Bodo Oil Sands Bitumen", NSERC Report, University of Calgary, AB, Canada, 1984. 

The term volatile matter content (of coal) is actually a misnomer, insofar as the majority of the volatile matter is the volatile product of the thermal decomposition of coal through the application of high temperatures. The extent to which the more volatile smaller molecules of coal (Vahrman, 1970) add to this is dependent on the coal and should be determined by nondestructive methods such as extraction by solvent(s). Relative yields and boiling-point profiles provide the extent to which natural molecules contribute to the volatile matter without any influence from high-temperature cracking. 

Some examples of viscoelastic materials include amorphous polymers, semicrystalline polymers, biopolymers, and metals at very high temperatures. Cracking occurs when the strain is applied quickly and outside of the elastic limit [8],... 

High Temperature Crack Growth in Unreinforced and Whisker-Reinforced Ceramics under Cyclic Loads... 

Since the significant majority of the published literature on high temperature crack growth under static and cyclic loads is predicated upon experiments conducted on alumina and alumina matrix composites, the examples cited in the present review have centered around oxide ceramics and their composites. However, the implications of the results to other classes of ceramics, intermetallics, and brittle matrix composites are also described, wherever feasible, along with any available information in an attempt to illustrate the generality of the concepts developed here. 

In this chapter, we have sought to provide a state-of-the-art review of the mechanics and micromechanisms of high temperature crack growth in ceramics and discontinuously reinforced ceramic composites. Because of the limited amount of experimental data available in the literature which pertains primarily to oxide cermics and SiC reinforcements, the discussions of crack growth rates and fracture mechanisms have centered around alumina ceramics, with and without SiC reinforcements. However, the generality of the mechan-... 

U. Ramamurty, T. Hansson, and S. Suresh, High-Temperature Crack Growth in Monolithic and SiCVReinforced Silicon Nitride Under Static and Cyclic Loads, J. Am. Ceram. Soc., 77[11], 2985-2999 (1994). 

S. V. Nair, K. Jakus, and C. Ostertag, Role of Glassy Interface in High Temperature Crack Growth in SiC Fiber Reinforced Alumina, Ceram. Eng. Sci. Proc., 9[7-8], 681 (1988). 

GTE [Gas To Ethylene] A process for converting methane to liquid fuels. High-temperature cracking first produces acetylene, which is converted to ethylene, which is then oligomerized. Piloted at Texas A M University in 2005 and licensed to Synfuels International. 

The basic conversion rate data for the present study are from experiments on propane cracking made several years ago by one of the authors (K. D. Williamson). The conversion/time/temperature data have been published in graphical form (2). We believe these to be superior to any high-temperature cracking rate data available. The range of decompositions covered (0-80%) is extended by recourse to some older propane data available to us but not previously published. These latter data are of somewhat poorer quality. Previously unpublished data on n-butane and n-hexane conversion (0-99% decomposition) from the Williamson study are used to verify the model. 

---