Visbreaker Residue

Cracking (visbreaking residual oils) TU LG None 470-495 10-30 450 s, 8 LHSV [11]... 

Leuna Methanol Anlage Leuna, Germany Shell 1985 Visbreaker residue (2400 mt/d) Fire-tube boiler 7.2 H2 (42.4 MMscf/d)... 

Pernis Shell IGCC/H2 Rotterdam, Shell Netherlands October 1997 Visbreaker residue (1650 mt/d) Fire-tube boiler 4.7 H2 (100 MMscf/d), power, steam... 

Mitteldeutsche Erdol-Rafflnerie GmbH Germany 1985 Visbreaker residue Shell Rectisol Methanol... 

Coal and pet coke Visbreaker residue PRENFLO Shell... 

SARLUX srl Italy 2001 Visbreaker residue Texaco SelexoP IGCC/Cogen... 

Co.) AgipPetroli/EniPower Italy 2004 Visbreaker residue Shell Aminea IGCC, H2... 

In the partial oxidation for the production of methanol (POX/methanol) complex, a major portion of the visbreaker residue (approximately 670,000 tons per annum) is converted to gas. Part of the syngas produced in the POX is used to cover the hydrogen demand of the refinery. Therefore, a plant producing high purity hydrogen has been installed and is operated by Linde. Another part of the syngas is added to the refinery fuel gas system for consumption in the process furnaces, which are exclusively gas fired. 

These processes may be expressed as resulting in a decrease and an increase in asphaltenes content, respectively. Reactions of condensation of asphaltene precursors (resins, etc.) prevail for light stocks. For heavier stocks, cracking of asphaltenes plays a more significant role. Thus, any increase in asphaltene content takes place mainly due to concentrating them in the visbreaking residue as a result of distillation of the visbroken product. 

Figure 1.13 Processing of plastic wastes in refinery units.19 VVA pre-treated mixed plastic scrap AR residue from the atmospheric distillation process VR vacuum distillation residue VisR visbreaker residue VVR vacuum visbreaker residue.

The different thermal behavior of the different groups of sample may be demonstrated using the TGA curves of the samples No. 8 vacuum residue Kuwait (Fig. 4-12), No. 10 vacuum residue Arabian Heavy (Fig. 4-13), No. 14 atmospheric residue Arabian Light (Fig. 4-14), No. 17 atmospheric residue Kuwait (raw material for sample No. 8) (Fig. 4-15), No. 21 visbreaker residue base Venezuela (Fig. 4-16), and No. 22 residue from thermal cracking, base Iranian Heavy (Fig. 4-17). 

Sample No. 21 Visbreaker Residue (Venezuela Crude) Heating Rate fk 10 K/min Atmosphere Argon 25 cm /min... 

The lower value of the ratio CR/ND for products from conversion processes indicates that considerable amounts of these products have already been cracked and distilled. The high value CR/ND = 0.88 for the visbreaker residue, sample 21, demonstrates on the other hand that in that case the crack conditions were very light. 

In Fig. 4-23 the distillation curves of samples from conversion processes are shown. The fully distilled residues from a cat-cracker (sample 20) and from a thermal cracker (sample 22) do not contain any substances separable by distillation, but do contain approximately 40-50 wt% crackable substances. From the visbreaker residues (samples 19 and 21) about 20 wt% may still be separated by vacuum distillation. Obviously the residue of a thermal cracker (sample 18) has undergone only atmospheric distillation. Approximately 5 wt% may still be gained from that sample by atmospheric distillation, and an additional 65 wt% by vacuum distillation. 

The TGA-curves of the experiments in argon are the same as those in air at lower temperatures. Differences in the slope of the curves first become noticeable in the medium temperature range starting at about 275-400 °C. The curves in air are usually shiftet to higher temperatures (Fig. 4-26, sample 8), which indicates absorption of oxygen. Sometimes a flattening of the curve occurs, as shown in Fig. 4-27, sample 11. Fig. 4-28 demonstrates that the oxidation first starts when about 55 wt% of sample 14, (atmospheric residue from Arabian Light crude) has already evaporated. The behavior of the atmospheric residue of a blend from Tuimaza and Arabian Heavy crudes (sample 16 in Fig. 4-29) is similar. The difference in the evaporated quantities before the start of oxidation is shown in Fig. 4-30 (visbreaker residue, sample 21) and Fig. 4-31 (waxy distillate, sample 23). 

The activation energy of sample 18 (residue from a thermal cracker) rises from 171.9 kJ/Mol at normal pressure to 187.2 kJ/Mol at 10 bar pressure. This increase of only 10 % indicates that a pyrolysis reaction occurs even at 1 bar pressure, especially since the peak maximum temperatures hardly shift. Sample 19 (visbreaker residue) does not exhibit a vaporization peak under these conditions. 

The second, more extensive, investigation on nine vacuum residues (VR) and two derived visbreaker residues (VVR) used reactions at three different temperatures (410 °C, 440 °C, and 460 °C), with a constant residence time of 30 minutes, and cold hydrogen pressure of 90 bar. The aim of this experiment was to investigate the influence of the origin of the eleven residues, from five different oil regions, upon their reaction behavior [4-42]. 

Eleven different distillation residues from five oil regions were used for investigations on the hydrocracking reaction. Vacuum residues (VR) and a visbreaker residue (VVR) produced from each were available from a Mexican and a Libyan erode. The residues and their origins are listed in Table 4-127 their analytical data is given in Table 4-128. It is evident that the content of heteroatoms varies considerably depending on the origin of the samples, whereas the atomic H/C ratio exhibits only small differences (mean value x = 1.415, standard deviation x = 0.022 equals a coefficient of variation V = 1.56 % relative). 

As mentioned above, the height of the DTG peak depends on the homogeneity of the substance, which evaporates or cracks at the average temperature T. Individual substances will have high, narrow peaks whereas multi-component systems have low, broad peaks. For example, the products from the reactions at 440 °C from the Mexican and Libyan vacuum and visbreaker residues all have very broad, flat peaks. 

The kinetic coefficients of the vacuum residues are greater than those of the corresponding visbreaker residues. This indicates that the visbreaker residues are subject to thermal damage. 

Stratiev, D., Nikolaev, N. 2009. Dependence of visbreaker residue properties on unit operation severity and the residual fuel oil specification. Petrol. Coal 51(2) 140-145. 

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