SU799674A3 - Method of producing nongraphitized and graphitized oil coke from low-sulfur oil - Google Patents

Abstract

1380526 Petroleum coke MARUZEN PETROCHEMICAL CO Ltd and CHIBA CARBON RESEARCH CORP Ltd 19 Feb 1973 [1 March 1972] 8091/73 Heading C5E Non-graphitizable and graphitizable cokes are produced by preheating a low-sulphur crude oil to a temperature required for a first coking stage; delay coking in a coking drum at 380-430‹ C., 2-20 kg./em.<SP>2</SP>G to produce a non-graphitizable coke; removing from the uncoked product gases and fractions such as gasoline, kerosene and gas oil to leave a heavy residue; preheating this heavy residue to a temperature required for a second coking stage; delay coking in a second coking drum at 400- 460‹ C., 4-20 kg./cm.<SP>2</SP>G to produce a graphitizable coke, the temperature and pressure conditions in the second coking stage being higher than those in the first delayed coking stage. A layer of coke particles is provided in the bottom of the first coking drum before the start of operation. The heavy residue from the first stage may be vacuum distilled to remove a waxy fraction before coking in the second stage. Thermal tar may be added to the heavy residue to form a feedstock for the second stage.

Description

graphitized coke obtaining sa ,. In addition, the first stage of coking is carried out in the presence of coke particles. The vacuum residue obtained by the vacuum distillation of the heavy residue is directed to the second stage of the delayed coking. 5-50 wt.% Tar with beats are added to the t Asel residue. weighing 1.0-1.12 g / cm, carbon residue 7-20%, asphaltenes content 2-7 wt.%, 5-50% resin with a specific weight of 1.03-1.07 g / is added to the heavy residue cm, carbon residue 7-14%, the content of asphaltenes 0-14 wt.%. In order for crude oil to be suitable for producing graphitized coke, which is used for the production of graphite electrodes, it must have a sulfur content of less than 0.4 wt.%, Preferably less than 0.25 wt.%. Ungrafted coke obtained in the first stage of coking has an amorphous structure similar to activated charcoal. Its CTE is about 4.5-7.5x10 / ° C (at 100-400 ° C when measured on a graphitized sample), which is significantly larger than the CTE of conventional petroleum coke 2-Зх10 ° С and electrode coke 1, 2 l, 8xlOV ° C. Graphitized Coke, obtained in the second stage of coking, has an unusually highly crystalline structure and a much lower KTR index than first-class coke obtained by a known method. Thus, the KTR index of the graphitized coke obtained by the proposed method is lower than 1, usually by 0.98-0.74 (at 100-400 s, when measurements are made on a graphitized sample). The first stage of coking, to which crude oil is directed, should be carried out at 380-430 ° C and a pressure of 2-10 kg / cm in order to achieve complete and effective removal of materials that prevent the formation of graphitized coke. The importance of such a temperature in the first stage of coking for the purpose of implementing the selective formation of non-graphitized coke is evident from the experiment. The experiment is carried out using Lzhatibang crude oil as a raw material, having a specific gravity of 0.880 g / cm (15.4 CF sulfur content 0.11 wt.% And asphaltene content 8.9 wt.%, In comparison with the proposed method, where The first coking stage is carried out at a pressure of 2 kg / cm and varying temperatures (380-480 ° C). Comparative data is given in Table 1. Table 1

The temperature of the first coking.

380 400 410 420 430 440 460 480 Coke yield in the first stage,% 0.5 2.0 5.5 6.1 6.0

KTP coke first stage (x10 / ° C at 100-400 ° C)

7.0 7.3 7.0 6.7 6.6 3.8 4.1 4.8 The pressure of the first coking stage depends on the temperature used to achieve optimum results from a technical and economic point of view. Thus, for relatively low temperatures of a certain range, it is preferable to use (use a relatively high pressure to accelerate the coking reaction where the upper limit is determined by the maximum thickness of the coke drum wall acceptable from an economical point of view. For relatively high temperatures, it is preferable to use a relatively low pressure to avoid premature the formation of a part of graphitized coke on the first 8.0 10, O 11, O coking stage together with the formation of non-graphite of coke, which can occur if a higher pressure is used, which leads to a decrease in the yield of graphitized coke in the second stage of coking. If the pressure of the first stage of coking is low, the removal of materials harmful to the formation of graphitized coke is incomplete and the cleaning of the raw material of the second stage is insufficient The lower pressure limit is determined taking into account this fact. The second stage of delayed coking by the proposed method requires the use of the first stage distillate products as a heavy residue. of coking, which

thoroughly cleaned, all materials harmful to the formation of graphite coke are removed, as well as moderate operating conditions: temperatures of 400-460 ° C and pressures of 4-20 kg / cm2. Conditions of temperature and pressure of the second stage of coking depend on each other are determined by the CTE index and the yield of graphitized coke. Thus, the use of a temperature higher than 460 ° C is undesirable, since it affects the quality of the CTE of the graphitized coke, although the yield is high. When the coking temperature is below 400 ° C in the second stage, the coking reaction proceeds very slowly, the coke yield decreases, and

Coking conditions

Temperature, ° С 495

2

Pressure, kg / cm 2 Coke yield .13.1

Coke characteristics

KTR (100-400 ° С)

The method is described using separate independent coke drums for the first and second stages, as proposed.

As can be seen from the table. 2, the proposed method provides an improvement in quality, especially the ability to graphitize and the yield of graphitized coke obtained in the second stage of coking, as compared with the known.

The method is as follows.

way.50

A layer of coke particles is placed on the lower part of the first coke drums before the start of the operation in order to completely prevent the first coking stage from mixing the non-graphite coke from the first coking drum with graphitized coke formed in the second coke drums. The amount and size of the coke particles forming the layer in the first coking drums are determined depending on the size of the coke drums, the nature of the oil and other process variables.

In the first stage of coking, which is carried out with respect to m g-65

the method becomes economically unacceptable. The upper limit of pressure is determined by economic interests, as in the first stage of coking, and the lower limit depends on the yield and density of the coke produced.

Improving the quality and yield of graphitized coke formed in the second stage of coking by the proposed method, as compared with the known, is illustrated by the following experiments.

In tab. Table 2 presents the results of coking by the proposed and known methods using raw materials of 5 Jatibarang crude oil under the conditions indicated in the table.

table 2

415 2 6.0

495 2 4.1

440 9 11.0

Under these conditions, the paraffin content of the product increases significantly, possibly due to the small pyrolysis of components with a relatively high boiling point in the crude oil.

After the first-stage uncoked coking product undergoes degassing and atmospheric distillation to remove cracking gases and light oil fractions, including gasoline, kerosene and light gas oil, in the usual way, the heavy residue is subjected to vacuum distillation to remove heavy gas that is rich in paraffin, and then the vacuum residue, which is diluted with the light gas oil fraction, is directed to a second delayed coking. This technique provides the production of useful vacuum distillates with a high paraffin content, an improved yield, and provides the production of both non-graphite and graphitized coke. Paraffin distillates have been found to have a higher paraffin content than those obtained from crude oil. The raw material subjected to the second delayed coking is a heavy residue obtained by first slowly coking a low-sulfur crude oil under certain mild conditions, followed by the removal of cracked gas and light oil fractions from the resulting coked product. such as gasoline, kerosene and light gas oil, and then removing the paraffin fraction by vacuum distillation. However, to the same residue, a thermal resin may be added to feed to the second coking stage in an amount of 550% by weight. Preferred thermal resins include a heavy residue with a specific gravity of 1.03-1.07 g / cm L cocoa residue 7-14 wt.% And asphaltene 0.14 wt.%, Which is obtained as a by-product of cracking at high oil temperature. to produce ethylene, thermal resins with a specific weight of 1.01–1.12 g / cm, a coke residue of 7–20 wt.%, and an asphaltene content of 2–7 wt.%, which are obtained from gas oil cracking of uncoked first and second stage products. coking by the proposed method by further thermal cracking and subsequent distillation. Example 1. As raw materials, crude oil is used from Lkatibaranga with a specific weight of 0.880 g / cm (15.4 C) with a sulfur content of 0.11% by weight and asphaltenes by 8.9% by weight. Crude oil is heated, then fed to the first coking drum, where the first delayed coking is carried out at 415 ° C and a pressure of 2 kg / cm for 36 hours to obtain non-graphitized coke Fieprokokvavysyyus, but the cracked oil is distilled at atmospheric pressure to remove cracked gases ( 5.4 wt.%) Gasoline fraction U2.3 wt.%) And the kerosene-gas fraction (25.0 wt,%). VAT residue after distillation with beats. weighing 0.901 g / cm (15.4 s), with a sulfur content of 0.11 wt.% and asphaltenes 0.55 wt.% are heated and fed to the second coking drum, where the second delayed coking is conducted at 435 ° C and pressure 9 kg / cm - for 28 hours with the emission of graphitized coke. The coking drums of the first and second stages after the end of the delayed coking are rinsed with superheated steam at 600 ° C to clean them of the remaining petroleum products. Petroleum coke, obtained in the first stage of coking, is amorphous, the degree of its graphitization is equal to one, and the CTE at 10 О-4 О С parallel to the extrusion direction 6, The coke yield is 6.0% of the weight of the supplied crude oil. Petroleum coke obtained in the second stage of coking with a yield of 10% of crude oil has the following properties: True density, g / cm 2,15 Apparent to density in water (8-12 mesh), g / cm 2,102 Crush strength, % 58 CTE at 100-400 ° С x10 Parallel to extrusion 0.98 Parallel to 3.33 Thickness of graphitization 5.0 Specific resistance, X 10 Ohm / cm 69 True density, apparent density, crushing strength, and degree of graphitization are the same as in calcined coke, and KTR, magnetic resistance and resistivity are the same as in graphite residue. The crushing strength and magnetic resistance are determined as follows. About 30 g of granulated calcined coke (5-12 mesh) is placed in a cylindrical form of stainless steel with a diameter of 30 mm and a length of 100 mm. After the piston head is installed on the coke surface, a pressure is applied to the head, creating pressure up to 100 kg / cm for 30 s, then the load is held for another 30 s. Then the coke is removed from the mold and sieved through a 12 mesh sieve minus. The remaining coke is weighed. The ratio of remaining granular coke to the initial quantity is expressed as crush strength as a percentage by weight. Example 2. In this experiment, crude oil from Sariya (North- / Africa) with a specific gravity of 0.841 (15.4 s), with a sulfur content of 0.20 wt.% And asphaltenes 6.5 wt. Is used ;. Crude oil is slowly coked in two stages analogously to example 1. Coke, obtained from the first stage of coking with a yield of 4% for crude oil, has a degree of graphitization of 2.0 and CTE of 4.5 x 10 / s at 100-400 ° C, and coke obtained in the second stage of coking with a yield of 9% in crude oil, it has a degree of graphitization of 5.2, a thermal expansion coefficient of 0.81x10 ° C at 100–400 ° C parallel to the extrusion direction, and a thermal expansion coefficient of 2.83x107 ° C at 100–400 ° C, in parallel thickness, resistivity 60x10 Ohm / cm. Example 3. Crude oil from Jatibarang with a specific weight of 0.883 (15.4 C), with a sulfur content of 0.13 wt.% And asphaltenes of 8.0 wt.% Is subjected to two-stage delayed coking as in Example 1, but previously to the bottom grade (- An iniqui coking drum is placed a layer of coke particles about 1/10 thick of the entire effective height of the drum. Delayed coking conditions in the first stage: temperature 425 ° С, pressure.2 kg / cm, coking time 33 hours, in the second stage - 435 ° C, 9 kg / cm and 20 hours, respectively. Coke obtained in the first stage with a yield of 7.1 V C.% of crude oil is amorphous, its degree of graphitization is 1.2, CTE 7, bx10- / ° C at 100-400 ° C parallel to extrusion. Coke obtained in the second stage with a yield of 9.2 wt.% of crude oil, has a CTE of 0.81x10 ° C parallel to extrusion at 100-400 ° C (and 2.86x10 / ° C parallel to thickness at 100-400 ° C), the degree of graphitization is 5.0, the resistivity is 65x10 Ohm / cm. Coke has good graphitability and the same strength as coke from the second stage of Example 1. Example 4. In this experiment, Minas crude oil with a specific gravity of 0.843 (15/4 ° C) g / cm is used, with a sulfur content of 0.07 wt.% and asphaltenes 0.67 ve with.%. Crude oil is coked in two stages by delayed coking as in example 3, but the coking time in the first stage is 34 hours, and the temperature, pressure and time in the second stage of coking are 440 ° C, 15 kg / cm and 30 hours, respectively. Coke, obtained from the first stage with a yield of 2.5 wt.% For crude oil, has a degree of graphitization of 3.0 and KTP 5, OxlOV ° C at 100-400 ° C parallel to extrusion. Coke from the second stage with a crude oil course of 6.3% by weight has a degree of graphitization of 4.9, a CTE of 0.85x (at 100-400 ° C parallel to extrusion), the same coefficient 2.89x (parallel to the thickness at 100,400 ° С) and specific resistance bЗх х10 Ohm / cm, with a high degree of graphitization. Example 5. In this experiment, Jatibarang crude oil is used, the same as in Example 1. Crude oil is slowly coked in two stages as in Example 1, but the temperature, pressure and coking time in the first stage, coking are 410 ° C, 2 kg / cm and 32 hours, and in the second stage - 440 ° C, 9 kg / cm and 28 hours, respectively; the raw materials for the second coking stage are prepared by atmospheric distillation of the non-coked product from the first coking stage and remove 5.3% of the cracked gases, 9.3% by weight of the gasoline fraction and 23.7% by weight of the light gas fraction by distillation of the bottoms in vacuum heavy gas oil fractions of 24.8 wt.% and mixing the vacuum residue with the light gas oil fraction after atmospheric distillation. The yield and content of paraffin wax in the heavy gas oil fraction is significantly increased compared with heavy gas oil, usually obtained by atmospheric distillation of crude oil from Jatibarang, followed by vacuum distillation of the residue from atmospheric distillation. This is due to the soft pyrolysis of high-boiling heavy fractions of Dzhatibarang crude oil going in the first stage of coking. Thus, the crude oil yield and wax content of the heavy gas oil in this experiment is 24.2% by weight and 72% by weight, while in the heavy gas oil obtained by the usual method they are 18.4% wt.% and 65 wt.%. In this embodiment, the paraffin wax yield is 17.4 wt.% for crude oil, which is 45% more than the yield of this product by the conventional method. Coke, obtained in the first stage with a yield of 5.3 wt.% For crude oil, has a degree of graphitization of 1.2 and KTP 7.0x10 / C parallel to extrusion at 100-400 ° C. Coke obtained in the second stage with a yield of 8.6 wt.% For crude oil, has a degree of graphitization of 5.1 CTE (at 100-4.00 ° C) 0.90x10 / ° C parallel to extrusion and 3.06x10 / ° C It is parallel to the thickness and resistivity of 79x10 Ohm / cm with high graphitability. Example 6. Jatibarang cheese oil with a specific weight of 0.886 g / cm (15.4 s), with a sulfur content of 0.17 wt.% And asphaltenes of 8.0 wt.% Is subjected to two-stage delayed coking as in Example 1. But to raw materials for The second stage of coking is added with 32% thermal tar, which is obtained by pyrolysis at 550 ° C and a pressure of 50 kg / cm in the fraction of the cracked gas oil. weight 0,842 g / cm (15.4 s), obtained from the first and second stages. Ud. the weight of this tar is 1.08 g / cm (15.4 ° С), the content of asphaltenes is 15.1% and 2.2%, respectively. As a result, the coke yield in the second stage increases significantly. Coke obtained in the first stage with a yield of 6 wt.% For crude oil has a degree of graphitization of 0.8 and CTE 6.6xlOV ° C at 100-400С, and coke obtained in the second stage with a yield of 17.2% has a degree of graphitization 5.2 КТР (at 100-400 С) 0.74х10-7 ° С (in the direction of extrusion) and 2, С (parallel to the thickness) and specific resistivity of 64x10 Ohm / cm, with very high graphitizability. Example 7. The same Jatibarang crude as in Example 5 coke slowly in two stages, but in the second stage of coking a mixture of 80 parts by weight of the vacuum residue from example 1 and 20 parts of thermal tar is used as in the comparative experiment of the example 2

Coke, obtained in the first stage of coking with a yield of 6.0% for crude oil, has a degree of graphitization of 1.2 and CTE 6, parallel to extrusion at 100–400 ° C, and coke, obtained in the second stage, q, yield 12% of raw material oil, has a degree of graphitization of 5.0, КТР О, 94x10 / ° С (parallel to extrusion) gri 100-400 s and 3.15х10 ° С (parallel to thickness) and specific resistance bbhu Ohm / cm

Invention Formula

The method of obtaining non-graphitizable and graphitized petroleum coke from low-sulfur crude oil, including the first stage of delayed coking, separation of the finished coke from vapor-liquid coking products, fractionation of the latter into light fractions and a heavy residue, and the second stage of coking a heavy residue, about tons of coal and the fact that, in order to simplify the process, reduce the thermal expansion coefficient of the graphitized coke and increase its

output, the first stage of delayed coking is supplied with crude oil, coking is carried out at 380-420 ° C and a pressure of 2-10, the second stage of delayed coking is carried out at 400-460 ° C and a pressure of 4-20 kg / cm.

2. A method according to claim 1, characterized in that the first stage of coking is carried out in the presence of particles of coke.

3. A method according to claim 1, characterized in that the vacuum residue obtained by vacuum distillation of the heavy residue is directed to the second stage of coking.

4. The method according to claim 1, characterized in that 5-50 wt.% Tar with a specific gravity of 1.0-1.12 g / cm, carbon residue 7-20%, asphaltenes content is added to the heavy residue. 2-7 wt.%.

5. The method according to claim 1, characterized in that 5-50% by weight of resin with a specific gravity of 1.03-1.07 g / cm, carbon residue 7-14% is added to the heavy residue, asphaltene content of 0-14 wt.%.

Sources of information taken into account in the examination

1. US Patent No. 3617480, cl. 208-.50, 1971.

Claims (4)

Claim A method for producing non-graphitizable and graphitizable petroleum coke from low-sulfur oil, including the first stage of delayed coking, separation of the finished coke from vapor-liquid coking products, fractionation of the latter into light fractions and heavy residue, and the second stage of coking of the heavy residue, which is related to that, in order to simplify the process, reduce the coefficient of thermal expansion of graphitized coke and increase its yield, crude oil is poured into the first stage of delayed coking by t at 380-420 ° C and laziness of 2-10 kg / s * m ² , the second stage of cocc davit slow coking is carried out at 5 400-460 ° C and a pressure of 4-20 kg / cm ² . 2. The method according to π. 1, characterized in that the first stage of coking is carried out in the presence of coke particles. . " 3. The method of pop. 1, it is distinguished by the fact that the vacuum residue obtained by vacuum distillation of a heavy residue is sent to the second coking stage. 4. The method according to claim 1, characterized in that 5-50% by weight of tar with a specific gravity of 1.0-1.12 g / cm ³ and a carbon residue of 7-20% are added to the heavy residue. , the content of asphaltenes 2-7 wt.%. 20 5. The method of pop. 1, with the fact that to the heavy residue add 5-50 wt.% Resin with a specific gravity of 1.03-1.07 g / cm ³ , a carbon residue of 7-14%, asphalt content 25 ten 0-14 wt.%.