OPTIONS FOR PROCESSING TYPICAL CRUDE OIL

N. M. SMOLYANINOVA, K. K. STRAMKOVSKAYA

(Presented by the scientific-methodological seminar of the organic departments)

Typical crude oil is intended for transportation through the Aleksandrovskoye—Anzhero-Sudzhensk oil pipeline and is a mixture of oils from the Samotlor (75.0%), Sovetskoye (11.8%), Megion (6.5%), and Vatinskoye (6.7%) fields of the Nizhnevartovsk arch, taken in proportions corresponding to the production plan for these oils for 1975 (according to data from the Giprotyumenneftegaz Institute).

The crude oil has the following characteristics: specific gravity \((d_4^{20})\) is 0.8589, molecular weight—205, viscosity at \(20^\circ\mathrm{C}\)—8.66 cSt, paraffin content—3.37%, silica-gel resins—9.61%, asphaltenes—1.47%, sulfur—1.33%; yield of fractions boiling up to \(200^\circ\mathrm{C}\)—26.5%, up to \(300^\circ\mathrm{C}\)—50.0%. Data on the fractional composition (rectification on ARN-2) and the curves characterizing the properties of the 3% fractions are shown in Fig. 1.

The gasoline cuts are distinguished by the absence of sulfur compounds and by low octane numbers in the straight-run state (65–45, motor method). The initial boiling point—\(180^\circ\mathrm{C}\) fraction (yield 20.5%), after addition of ethyl fluid in an amount of 0.82 g/kg, satisfies the GOST standard for A-66 motor gasoline.

Narrow gasoline fractions boiling within the ranges \(62\text{—}85^\circ\mathrm{C}\), \(62\text{—}105^\circ\mathrm{C}\), and \(85\text{—}120^\circ\mathrm{C}\) (yields 2.6; 5.6; 5.8%, respectively) contain from 39% to 36% naphthenic hydrocarbons. In the broad fraction (\(85\text{—}180^\circ\mathrm{C}\)) the concentration of naphthenes is 29%. It follows from this that typical crude oil is a favorable source of feedstock for the production of aromatic hydrocarbons by catalytic reforming.

The \(120\text{—}240^\circ\mathrm{C}\) fraction (yield 21.8%) meets, in all indices, the GOST standard for TS-1 jet fuel, and the \(120\text{—}280^\circ\mathrm{C}\) fraction (yield 29.6%) meets the standard for T-1 fuel.

Kerosene distillates, \(150\text{—}280^\circ\mathrm{C}\) and \(150\text{—}320^\circ\mathrm{C}\) (yield 24–92%), have low octane numbers (20–18) and therefore cannot be used as tractor fuel; however, as illuminating kerosene they possess good photometric quality (smokeless flame height 24–23 mm).

Diesel-fuel fractions (\(150\text{—}350^\circ\mathrm{C}\), \(200\text{—}350^\circ\mathrm{C}\), \(240\text{—}350^\circ\mathrm{C}\)), with yields of 37.7; 28.4; 21.0%, respectively, by the value of their cetane numbers (50–53), viscosity level at \(20^\circ\mathrm{C}\) (from 3.35 cSt to 6.25 cSt), pour point (from minus \(42^\circ\mathrm{C}\) to minus \(21^\circ\mathrm{C}\)), and other indices, satisfy the GOST requirements for summer diesel fuel.

Fig. 1. Distillation curves of typical crude oil

The yield of feedstock for catalytic cracking (350–450°C fraction) is 20.6% of the crude oil. It contains 50% paraffinic-naphthenic hydrocarbons, 5.46% aromatics, and 4% resinous substances; the content of impurities that deactivate the catalyst is: sulfur 0.85%, nitrogen 0.25%, vanadium \(0.4 \cdot 10^{-5}\%\), coking value 0.01%.

A study of the potential content of distillate and residual oils by the method of adsorption separation on silica gel showed that from typical crude oil (350–450°C fraction) it is possible to recover 15.5% distillate oils with a viscosity index of 85 and a viscosity at 50°C of 13.25 cSt. From the residue boiling above 450°C, 4.6% oil with a VI of 68 and a viscosity level at 100°C of 21.09 cSt was isolated. From this crude oil 4.7% paraffin slack wax with a melting point of 47°C was obtained.

According to the technological classification (GOST 912–66), the typical crude oil belongs to class II (sulfur content 1.33%) and to type C\(_1\) (yield of fractions up to 230°C—52.7%). In terms of the quantity of base oils, it corresponds to group M\(_3\) (potential content of base oils 20.1%) and subgroup I\(_2\) (viscosity index 68–85). In terms of paraffin content, the crude oil belongs to type P\(_2\) (designation of the typical crude oil \(1\mathrm{T}_1\mathrm{M}_3\mathrm{I}_2\mathrm{P}_2\)).

In view of the above, the indicated crude oil can be processed both along fuel and fuel-and-oil lines. The following processing options may be outlined for it:

Option I. 1) gas through C\(_4\), inclusive—1.7%; 2) component of automotive gasoline (initial boiling point–150°C)—15.0%; 3) diesel fuel (150–350°C)—37.7%; 4) base oil from the fraction (350–450°C) with a viscosity index of 85—15.5%; 5) component of residual oil (resid-

residue above 450°C) with a viscosity at 100°C of 21.09 cSt and VI 68—4.6%; 6) paraffin slack wax 4.7%; 7) feedstock for bitumen production—20.8%.

Variant II. 1) gas through \(C_4\) inclusive, 1.7%; 2) feedstock for pyrolysis (IBP—62°C)—2.2%; 3) feedstock for catalytic reforming (62—120°C)—7.7%; 4) reactive fuel (120—240°C) 21.8%; 5) diesel fuel (240—350°C)—21.0; 6) feedstock for catalytic cracking (350—450°C)—20.6%; tar—25.0.

Variant III. 1) gas through \(C_4\) inclusive—1.7%; 2) motor-gasoline component (IBP—150°C)—15.0%; 3) illuminating kerosene (150—320°C)—31.9; 4) boiler fuel—residue above 320°C—51.4%.

Variant IV. 1) gas through \(C_4\) inclusive—1.7%; 2) motor-gasoline component (IBP—200°C)—24.3%; 3) diesel fuel (200—350°C)—28.4%; 4) feedstock for thermal cracking (above 350°C)—45.6%.

Variant V. 1) gas through \(C_4\) inclusive—1.7%; 2) feedstock for pyrolysis (IBP—180°C)—20.5; 3) diesel fuel (180—350°C)—32.2%; boiler fuel—45.6%.