RU2263704C1 - Method of controlling composition of petroleum cracking feedstock - Google Patents

Abstract

FIELD: petroleum processing.

SUBSTANCE: method consists in determining chemical type composition of petroleum products and coking capability of components of starting petroleum cracking feedstock followed by selection of feedstock composition according to data obtained. Coking capability of each feedstock component is evaluated after coefficient of coking capability (K_cc) found from formula: Kcc = (C_pnh + C_a ²)C_uc ²/(C_ha + C_r), where C_pnh is content of paraffin-naphtene hydrocarbons, C_a content of asphaltenes, C_uc content of unstable compounds, C_hah content of heavy aromatics, and C_r content of resins. Thereafter, composition is selected in such a way as to ensure Kcc value not higher than 0.075. Invention allows reducing time and amount of feedstock, as well as power consumption and time required to evaluate composition of feedstock.

EFFECT: enabled on-line feedstock formation control and enhanced efficiency of installations associated with petroleum feedstock heating.

3 cl, 1 tbl

Description

The invention relates to methods for controlling the composition of petroleum feedstocks intended for thermal processes, and can be used in the oil refining industry, for example, in thermal cracking processes to reduce coke deposits in reaction furnace coils.

A known method of regulating the composition of petroleum feedstock, including determining the group chemical composition of petroleum feedstock and coking ability, which is evaluated by the indicator - heat sensitivity T _h , determined at the pilot plant as the ratio of the absolute decrease in temperature at the outlet of the reactor to the time during which this decrease (G . "University News, Oil and Gas", 1982, No. 11, pp. 40-42). Then, taking into account the obtained indicator T _h experimentally select a raw material composition with such a composition in order to avoid intense coke formation during heating.

The disadvantage of this method is the various kinds of costs associated with the operation of the pilot plant, as well as the great complexity and duration of the determination of coking ability.

A known method of regulating the composition of the raw materials of a thermal cracking installation, including determining the group chemical composition of oil products of the feedstock, as well as its coking ability by the actual time (T _fact ) of coking of the coil of the furnace of the pilot thermal cracking unit at standard temperatures and pressures, followed by experimental selection of the raw material composition based on the data . Moreover, the longer the actual time (T _fact ) of coking of the furnace coil, the higher the rate of coke-forming ability (“Production of motor and boiler fuels from heavy residues of sulphurous oils.” Transactions of BashNII NP, issue X, publishing house “Chemistry”, M. , 1972, p. 63-67).

The disadvantage of this method, as in the previous case, is the significant capital and operating costs associated with conducting experiments on a pilot installation, the high complexity of these experiments, the long duration of determination of coking ability (6-11 hours) and a sufficiently large consumption of raw materials - samples for analysis (up to 2 kg).

Thus, the problem of reducing capital and operating costs, as well as simplifying the method of regulating the composition of petroleum cracked feedstock, arose.

The technical result is a reduction in time and quantity of raw materials (samples for analysis) in determining coking ability.

The specified technical result is achieved by the fact that in the known method for regulating the composition of petroleum cracked feeds, including determining the group chemical composition of petroleum products and the coking ability of the components of the feed petroleum cracking feed, followed by selection of the feed composition in accordance with the obtained indicators, according to the invention, the coking performance of each component of the feed petroleum cracking feedstock coking coefficient, which th determined by the formula

where K _ZS - coefficient of coking ability of the component;

P _N - the content of paraffin-naphthenic hydrocarbons,% mass .;

And _SF is the content of asphaltenes,% mass .;

Ta - the content of heavy aromatic hydrocarbons,% mass .;

Cm is the resin content,% mass .;

C. _HC - the content of volatile compounds,% by weight, and then selection is carried out by the minimum value of the raw composition K _gc provided that K _LC ≤0,075..

It is advisable to determine P _N , A _SF , T _a and C _m by the chromatographic method (the contents of light and medium aromatic hydrocarbons are not taken into account).

The content of unstable compounds, it is advisable to determine the optical density D ₁₆₄₀ , D ₃₄₂₀ , IR spectra.

The method is as follows. Take a sample of petroleum raw materials that can be used in the preparation of compositions (blends) loading furnace thermal cracking process and is carried out analyzes on content of the group of the chemical composition, for example, P _n, T _and C _m, A _sp determined by chromatography, and SNA - by optical density D ₁₆₄₀ , D ₃₄₂₀ , IR spectra.

и определяют коэффициент закоксовывающей способности компонентов и композиций. Причем состав композиций подбирают таким образом, чтобы обеспечить минимальную величину К_ЗС, но не более 0,075. Рециркулят в загрузке печи представляют как один из компонентов в композиции с показателями качества, подобными идентичным продуктам термокрекинга, например, тяжелого газойля. Коэффициент закоксовывающей способности композиций предварительно определяют расчетным путем, исходя из принципа аддитивности исходных показателей соответствующих исходных компонентов. Также он может быть проверен путем определения тех же показателей инструментальным методом для фактических проб соответствующих композиций. После накопления практических данных, как правило, делается положительный вывод об исключении последнего дополнительного мероприятия.The obtained data is substituted into the formula for determining the coking ability of an oil product:

and determine the coefficient of coking ability of the components and compositions. Moreover, the composition of the compositions is selected in such a way as to ensure a minimum value of K _ZS , but not more than 0.075. The recycle in the furnace charge is presented as one of the components in the composition with quality indicators similar to identical products of thermal cracking, for example, heavy gas oil. The coking coefficient of the compositions is preliminarily determined by calculation, based on the principle of additivity of the initial indicators of the corresponding initial components. It can also be checked by determining the same indicators by instrumental method for actual samples of the respective compositions. After the accumulation of practical data, as a rule, a positive conclusion is made on the exclusion of the last additional event.

By the value of K _ЗС, all components and compositions are distributed in a row from a larger to a smaller (or vice versa) value and conclusions are drawn about the state of the resources of thermal cracking raw materials, the possibilities for their processing, and the need for correction of technology, the range of raw materials and thermal cracking products.

The attached table provides specific examples of the method and shows a comparison with the prototype.

From the table it follows that there is good convergence between the data of the proposed method and the prototype. So, the best indicator is the coke-forming ability of component 3: K _ss = 0.03668, T _fact = 280 min. The data show that the time spent on analysis and evaluation of the quality of raw materials by the proposed method is 4.5-7 times less than the prototype. The weight of the sample for analysis is two orders of magnitude less than that of the known method. The analysis of K _{ss of} various types of raw materials shows that components 3, 4, 5 and composition 8 having K _ss <0.075 are preferred for thermal processes.

Thus, the proposed method allows to reduce energy consumption and the time required to evaluate the composition of the raw materials, which makes it possible to quickly control the formation of raw materials — loading the furnace of thermal processes, and ultimately to increase the efficiency of installations associated with heating of oil raw materials.

Table
The results of the determination of coke forming ability No. Raw materials loading Group chemical composition,% mass. Coking Capacity Index Analysis time, min Sample weight for analysis, kg Paraffin-naphthenic hydrocarbons, Mon Heavy aromatic hydrocarbons, resins (Ta + Cm) Asphaltenes, A _sf Unstable connections, With _ns K _ss To _ss *,% relates Oven coking time, T _fact , min (prototype) The proposed method Prototype The proposed method Prototype 1. Component 1 45.5 26.8 - 0.311 0.1642 447 thirty 100 450 0.002 0.2 2. Component 2 51.5 26.7 - 0.259 0.1295 353 98 100 520 0.002 0.7 3. Component 3 16.8 42.6 - 0,305 0,03668 100 280 100 700 0.002 1.9 4. Component 4 45,2 49.4 - 0.252 0.05810 158 240 100 660 0.002 1,6 5. Component 5 19.1 42.84 - 0.334 0,0497 136 250 100 670 0.002 1.7 6. Component 6 26.6 41 0.7 0.40 0.1057 288 144 100 560 0.002 0.96 Composition 7 7. - component 3 - 39.74% - component 2 - 35.48% - component 1 - 24.78% 37.61 31.92 0.2866 0.096789 264 160 100 580 0.002 1,0 Composition 8 8. - component 6 - 28.25% - component 5 - 71.75% 24.32 39.8 - 0.32 0.0629 171 228 100 648 0.002 0.3

* Relative values of K _{ss are} determined by the equation:

Claims (3)

1. The method of regulating the composition of petroleum cracked feedstock, including determining the group chemical composition of petroleum products and the coking ability of the components of the original petroleum cracking feedstock followed by selection of the feed composition in accordance with the obtained indicators, characterized in that the coking ability of each component of the petroleum cracked feedstock is evaluated by the coking ability coefficient defined by the formula

where K _ss - coefficient of coking ability of the component; P _n - the content of paraffin-naphthenic hydrocarbons, wt.%; And _sf is the content of asphaltenes, wt.%; Ta is the content of heavy aromatic hydrocarbons, wt.%; C _m - resin content, wt.%; With _ns - the content of unstable compounds, wt.%, and then the composition is selected in such a way as to provide a value of K _{ss of the} raw material composition of not more than 0.075. 2. The method according to claim 1, characterized in that the content of paraffin-naphthenic hydrocarbons (P _n ), asphaltenes (A _sf ), heavy aromatic hydrocarbons (Ta) and resins (C _m ) are determined by chromatographic method. 3. The method according to claim 1, characterized in that the content of unstable compounds is determined by the optical density D ₁₆₄₀ , D ₃₄₂₀ infrared spectra.