Carbon rejection

Ammonia-free water may be prepared in a conductivity-water still, or by means of a column charged with a mixed cation and anion exchange resin (e.g. Permutit Bio-Deminrolit or Amberiite MB-1), or as follows. Redistil 500 mL of distilled water in a Pyrex apparatus from a solution containing 1 g potassium permanganate and lg anhydrous sodium carbonate reject the first 100 mL portion of the distillate and then collect about 300 mL. 

There are commercial processes for the direct upgrading of residues under high severe hydroconversion conditions. Other alternatives consider the previous hydrotreatment of the residue, so that the hydrocracking stage does not need to be so harsh. Otherwise, residue conversion could also proceed via carbon rejection methods, these processes fall out the scope of the present book and will not be considered here. However, it is important to mention than VR coking is seen as a more economical alternative than HDP, especially for the more heavy crudes, for which concentrations of metals and nitrogen would require the toughest conditions. 

The physical methods include dilution, emulsification, addition of surface active agents, etc. Chemical conversion includes those methods involving carbon rejection and those of hydrogen addition . So far, there has not been any bioconversion process that has accomplished the developmental stage however, there have been some MEOR initiatives, which could be taken as inspiration for upgrading routes. Some of them will be mentioned here as examples, but will be specifically identified as MEOR alternatives. 

Both hydrogen addition and carbon rejection processes will be necessary in any realistic scheme of heavy oil upgrading (Suchanek and Moore, 1986). Most coker products require hydrogenation and most hydrotreated products require some degree of fractionation. For example, to maximize yields of transport fuels from Maya crude, efficient carbon rejection followed by hydrogenation may be necessary. There are various other approaches to the processing of other heavy oil residua (Bakshi and Lutz, 1987 Johnson et al., 1985). As of now, it is not known which combination of processes best converts a heavy feedstock into salable products. 

Carbon rejection processes, visbreaking, steam cracking, fluid catalytic cracking, and coking. 

Technologies for upgrading heavy crude oils such as heavy oil, bitumen, and residua can be broadly divided into carbon rejection and hydrogen addition processes (Chapter 8). Briefly, carbon rejection processes are those processes in which a carbonaceous by-product (coke) is produced along with distillable liquid products. On the other hand, hydrogen addition processes involve reaction of the feedstock with an external source of hydrogen and result in an overall increase in H/C ratio of the products as well as a decrease in the amount of coke produced. 

Carbon rejection processes upgrading processes in which coke is produced, e.g., coking (q.v.). 

All around the world there exists an installed capacity to process residue utilizing solvent deasphalting as a carbon rejection technology followed by hydrotreatment of the deasphalted oil (DAO) or the residual. Severity of the hydrotreating stage depends on the downstream use of the hydrotreated DAO or the residual, which can be used as feedstocks to catalytic cracking/ hydrocracking or as components of low sulfur fuel. 

The two major process concepts in refining are carbon rejection (also known as coking) and addition of hydrogen ( hydroprocessing ). 

Resid catalytic cracking (RFCC) (carbon rejection)... 

Hydrogen addition and carbon rejection technologies for upgrading of... 

The main characteristics of carbon rejection technologies are (Solari et al., 1997 ... 

Eigures 2.5 and 2.6 show the combinations of these carbon rejection technologies. The final products coming from the different processes are integrated, when possible, to produce upgraded oil. 

Combination of Both Hydrogen Addition AND Carbon Rejection Technologies... 

Figures 2.8 and 2.9 illustrate some of the process schemes of technologies based on carbon rejection and hydrogen addition that can be combined. Figure 2.10 shows other possible combinations between the different upgrading technologies.

Solari, R.B., Marzin, R., Zbinden, H. 1997. Comparison of carbon rejection and hydrogen addition processes in production—Upgrading complexes. In 15th World Petroleum Congress, Beijing, China, October 12-17. 

Aguilar, R.A., Ancheyta, J., Trejo, F. 2012. Simulation and planning of a petroleum refinery based on carbon rejection processes. Fuel 100 80-90. 

Chapter 2 reports some aspects of the commercially available process options for upgrading of heavy petroleum. The common carbon rejection and hydrogen addition routes as well as combined process schemes are described. Recent technologies without commercial application are also covered. 

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