RU2410409C1 - Method for obtaining oil coke by slow coking - Google Patents

Abstract

FIELD: oil and gas industry. ^ SUBSTANCE: invention can be used in oil industry. Initial raw material is heated in tube furnace 2 up to 400 C by supplying water condensate to the inlet part of coil of the tube furnace. Heated raw material is mixed with recirculated substance and light fractions are separated in evaporator 3 so that secondary raw material is formed. Secondary raw material is heated in reaction tube furnace 4 with its further being coked in coking chambers 5 so that coke and distillate products are obtained. Mixture of light fractions obtained in evaporator and distillate coking products are separated in rectifying column 6 into vapour products, light and heavy gas oils and residual oil. ^ EFFECT: invention allows reducing coking of coils of tube furnace for heating of initial coking raw material with simultaneous increase of efficiency of coke obtaining method. ^ 2 cl, 3 tbl, 1 dwg

Description

The invention relates to the field of oil refining, in particular, to the production of petroleum coke by delayed coking.

A known method of producing petroleum coke by delayed coking of oil residue, including heating the feedstock in a tube furnace, separation of heated feedstock in a distillation column in a mixture with distilled coking products formed in the coking chamber into vapor products and bottoms, delayed coking of bottoms as secondary raw materials in the coking chamber with the formation of coke and distillate products [Oil and gas technology, No. 2, February 2005, p. 83].

The disadvantages of this method are low productivity and low coke yield, high energy intensity due to the return of recycled coking products for the formation of secondary raw materials. In addition, the transfer of coke particles together with the foam into the distillation column, and then into the furnace, promotes coking of the equipment and, consequently, a decrease in the overhaul distance of the installation.

Closest to the claimed object is a method for producing petroleum coke by delayed coking of the oil residue, which includes heating the feedstock in a tube furnace, separating the heated feedstock in a mixture with recirculate into light fractions and a heavy residue as secondary feedstock, heating the secondary feedstock in the reaction tube furnaces followed by coking in the coking chamber with the formation of coke and distillate products, separation in a distillation column of light f stock in admixture with coker distillate products in the vaporous products and bottoms. As the recirculate using bottoms [US Pat. RF №2209826, class C10B 55/00, publ. 2003].

The disadvantage of this method is that when the feedstock is heated to 370 ° C and above, coking of the coils of the tube furnace for heating of the feedstock and cessation of the plant for producing petroleum coke are quickly coked, which limits the maximum heating temperature of the feedstock. Accordingly, the maximum temperature of the feed to the evaporator is limited, the heating temperature of the secondary raw materials, which leads to low productivity of the coking method.

The invention is aimed at reducing the coking of the coils of a tubular furnace for heating the feedstock while increasing the productivity of the method for producing coke.

This is achieved by the fact that in the method for producing petroleum coke by delayed coking, which includes heating the feedstock in a tubular furnace, mixing it with recirculate and separating light fractions in the evaporator to form secondary feedstock, heating the secondary feedstock in a reaction tube furnace with its subsequent coking in coking chambers to obtain coke and distillate products, separation in a distillation column of light fractions obtained in the evaporator, in a mixture with distillate coking products into vapor products s, light and heavy gas oils and bottoms, according to the invention, water condensate is fed into the inlet of the coil of the tube furnace to heat the feedstock.

The bottoms or heavy gas oil can be used as recycle.

As experimental data show, the supply of water condensate to the inlet part of the coil of a tubular furnace to heat the feedstock provides not only a decrease in coking of the coil of the tubular furnace to heat the feedstock, but also an increase in the productivity of the coke production method. So, the supply of water condensate in an amount of 1000 kg / h provides an increase in the temperature of heating of raw materials at the outlet of the furnace to 390-410 ° C. This allows you to reduce the amount of residue in the evaporator, as well as to increase the temperature of the secondary raw materials at the entrance to the tube furnace, which makes it possible to increase the productivity of producing coke from the feedstock.

The drawing shows a schematic diagram of an installation for implementing the proposed method for producing petroleum coke by delayed coking.

The installation contains a heat exchanger 1 and a tube furnace 2 for heating the feedstock with the possibility of feeding into the inlet of the coil of the tube furnace for heating the feedstock water condensate, an evaporator 3 for mixing the heated feedstock with recirculate and separating light fractions with the formation of secondary raw materials, a reaction tube furnace 4 for heating secondary raw materials, a coking chamber 5 for coking secondary raw materials, a distillation column 6 for separating light fractions separated in the evaporator 3, in a mixture with distillate coking products for vaporous products, light and heavy gas oils, bottoms. The outlet of the distillation column by heavy gas oil and bottoms is connected to the upper part of the evaporator with the possibility of using heavy gas oil or bottoms as recirculate supplied to the evaporator for mixing with the feedstock.

The method is as follows.

After heating, the feedstock is heated in a heat exchanger 1 in a tube furnace 2, in which water condensate is supplied to the inlet of the coil. The heated feedstock is sent to the evaporator 3, where it is mixed with the recycle and separated into light fractions and secondary feedstock. The secondary raw materials are heated in the reaction tube furnace 4 and fed alternately to the coking chambers 5, where the resulting coke is accumulated and the distillate coking products are separated. The latter are fed to distillation column 6, in which they are mixed with light fractions separated in the evaporator: vaporous products leave on top of the distillation column, light and heavy gas oils are removed from its middle part, and bottoms are removed from the bottom. Heavy gas oil or bottoms obtained in a distillation column is used as the above recycle.

Was carried out delayed coking tar of Arlan oil, the quality of which is shown in table 1, according to the prototype method and the proposed method. Table 2 shows the material balance of coking.

Example 1 (prototype). The feedstock is heated in a heat exchanger to 250 ° C, heated in a tube furnace to 350 ° C and fed to a distillation column. The useful heat load of the furnace for heating the feedstock is 5.8 Gcal / h. The residue from the distillation column in the amount of 12 t / h is also fed to the evaporator. Secondary raw materials are formed in the lower part of the evaporator in an amount of 127 t / h and are fed to a reaction tube furnace with a temperature of 350 ° C, where it is heated to 500 ° C and fed to a coking chamber. The useful heat load of the furnace for heating secondary raw materials is 12 Gcal / h. The maximum productivity of the plant for primary raw materials is 920 thousand tons / year.

Example 2 (by the proposed method). The same feedstock as in Example 1, in an amount of 138 t / h, is heated in a heat exchanger to 250 ° C, and then in a tube furnace to 400 ° C. Water condensate in the amount of 200 kg / h is supplied to the inlet part of the coil of the tube furnace. The useful heat load of the furnace for heating the feedstock is 7.5 Gcal / h. The residue from the distillation column in the amount of 12 t / h is also fed to the evaporator. In the lower part of the evaporator, secondary raw materials are formed in an amount of 165 t / h and are fed to a reaction tube furnace with a temperature of 400 ° C, from where - to a coking chamber. The maximum capacity of the plant for feedstock is 1100 thousand tons / year.

Example 3 (by the proposed method). The feedstock is heated and coked in the same way as in Example 2. Water condensate in the amount of 1000 kg / h is supplied to the input of the coil of the tube furnace for heating the feedstock. The maximum plant capacity for feedstock is 1200 thousand tons / year.

Example 4 (by the proposed method). The feedstock is heated and coked in the same way as in Example 3. Heavy gas oil is fed to the evaporator from a distillation column — 12 t / h. The maximum feedstock productivity is 1230 thousand tons / year.

Table 3 summarizes the initial and obtained comparative data on the prototype method and on the proposed method.

As can be seen from table 3, when coking the same raw material by the proposed method, compared with the method of the prototype, the loading of the coke production plant by the feedstock and the useful heat load (up to 8.4 Gcal / h) of the tube furnace for heating the feedstock are increased, and also increases the temperature of heating the feedstock at the outlet of the tube furnace to 400 ° C, which, in turn, provides an increase in heat supply to the feedstock at the inlet to the evaporator and an increase in the temperature of heating of the secondary feedstock at the inlet of the reaction pipe atuyu oven. Providing a higher inlet temperature, respectively, makes it possible to increase the load of the specified furnace from 127 t / h to 165 t / h. An increase in the furnace load leads to an increase in the productivity of the method for producing coke by 30% (from 920 to 1200 thousand tons / year) with the same heat load (12.0 Gcal / h) of a tubular furnace for heating secondary raw materials.

Thus, the use of the proposed method for producing petroleum coke will allow, in comparison with the prototype, to reduce the coking of the coil of a tubular furnace for heating the feedstock and, as a result, increase productivity.

Table 1 Tar quality of Arlan oil Quality indicators Quality Data

1. Density

1,020 2. Coking ability according to GOST 5987-51,% 18.6 3. Softening temperature according to KiSh, ° C 38 4. The sulfur content,% 4.60 5. The content of asphaltenes,% 13,4 6. Flash point, ° C 289 7. Fractional composition (according to Bogdanov) n.c., ° C 400 boils up to 450 ° C,% of the mass. 13 boils up to 500 ° C,% of the mass. 21 table 2 Material balance of coking tar of Arlan oil Yield, thousand tons / year Products prototype by the proposed method Raw materials 920 1200 1. Coke 267 348 2. Gas according to C ₄ 74 96 3. Fraction C ₅ - 180 ° C 92 120 4. Fraction 180-350 ° C 276 360 5. Fraction 350 - c.k., ° C 202 267 6. Losses 9 9

Table 3 Comparative data of delayed coking of tar Arlan oil by the prototype method and the proposed method Indicators Examples prototype by the proposed method one 2 3 four 1. The temperature of the feedstock at the entrance to the tube furnace, ° C 250 250 250 250 2. The temperature of the feedstock at the outlet of the tube furnace, ° C 350 400 400 400 3. The temperature of the secondary raw materials at the entrance to the furnace, ° C 350 400 400 400 4. The temperature of the secondary raw materials at the outlet of the furnace, ° C 500 500 500 500 5. The amount of water condensate supplied at the inlet to the coil of the tube furnace, kg / h 0 200 1000 1000 6. The consumption of feedstock in a tubular furnace, t / h 115 138 150 150 7. Useful heat load of a tubular furnace for heating secondary raw materials, Gcal / h 12 12 12 12 8. Useful heat load of the tubular furnace for heating the feedstock, Gcal / h 5.8 7.5 8.2 8.4 9. Plant productivity by feedstock, thousand tons / year 920 1100 1200 1230 10. Type of recirculate and consumption, t / h - bottom residue 12 12 12 12 - heavy gas oil - - - - 11. The consumption of secondary raw materials, t / h 127 165 165 165

Claims (2)

1. A method of producing petroleum coke by delayed coking, including heating the feedstock in a tube furnace, mixing it with recirculate and separating light fractions in an evaporator to form secondary feedstock, heating the secondary feedstock in a reaction tube furnace, followed by coking in coking chambers to produce coke and distillate products, separation in a distillation column of light fractions obtained in the evaporator, mixed with distillate coking products into vaporous products, light and heavy gas oil and bottoms, characterized in that the heating of the feedstock is carried out to 400 ° C, while water condensate is supplied to the inlet of the coil of the tube furnace to heat the feedstock. 2. The method according to claim 1, characterized in that the bottom residue or heavy gas oil is used as recirculate.