RU2315082C1 - Heavy hydrocarbon stock hydrocracking process and reactor - Google Patents

Abstract

FIELD: petroleum processing and petrochemistry.

SUBSTANCE: hydrocracking of heavy hydrocarbon stock is accomplished by feeding preheated feedstock and hydrogen or hydrogen-containing gas to reactor, heating the charge in reactor, and discharging cracking products, which are passed to separation stage. Reactor has two convection chambers with convective and radiation coils disposed therein. Hydrocracking is carried out, in particular, in reactor radiant coil zone with variable-cross section tubes allowing flow rate 50 to 310 m/s at 440-500 flow rate 50 to 310 m/s at 440-500°C.

EFFECT: increased productivity and efficiency of process.

6 cl, 3 dwg, 2 tbl, 3 ex

Description

The invention relates to oil refining, in particular to the cracking of hydrocarbons in the presence of hydrogen (non-catalytic cracking), and are intended to produce light (marketable) oil products from sulphurous oil residues.

A catalytic hydrocracking method is known, in which a mixture of sulphurous petroleum feedstock with hydrogen or a hydrogen-containing gas (WASH) is heated, then passed through a first stage reactor to remove sulfur, after which the gas-raw material mixture, together with a recycle residue and additional hydrogen, enters the second reactor for contact with a hydrocracking catalyst. The products of the second reactor are sent to a high-pressure separator, from where liquid products enter the distillation column for separation (Refinery Handbook. Edited by G.A. Lastovkin, L .: Chemistry, Leningrad Branch, 1886, pp. 152-154). The reactor for carrying out the catalytic hydrocracking process is a column filled with a catalyst.

The disadvantage of this method and device is the high capital and operating costs due to the use of expensive catalysts.

Known non-catalytic method for processing heavy hydrocarbons by thermal hydrocracking (US Pat. RF No. 2169170, on. June 20, 2001, IPC 7 C10G 47/22), according to which hydrocracking is carried out by supplying 20-30% of the mass of hydrogen or VSR in the reaction chamber. to the number of reagents and bring the gas pressure to 10-30 MPa, temperature - up to 1300-1500 ° K. Then in the chamber with heated hydrogen serves the processed raw materials in the amount of 70-80% of the mass. to the amount of reagents and mix it with hydrogen, the mixture is cracked at a total contact time of the raw material with hydrogen of 2-12 ms, then the reaction products are quenched while lowering the temperature and pressure for 5-10 ms and sent to the selection of the target products. The process is conducted in a reactor, which is a cylinder with a piston connected to a drive from an electric motor to communicate with the piston reciprocating motion. The reactor does not have a catalyst filling. The disadvantage of this method and device is its low productivity, due to the frequency of the process and the small volume of the reaction chamber (45 l), which corresponds to a capacity of about 10 thousand tons per year, and low efficiency of less than 40% due to the presence of a drive from an electric motor.

The closest in essential features to the proposed device is a GS-type tube furnace, which is a box-shaped design with an upper flue gas outlet and horizontal pipes (Tube Furnace Catalog, published by TSINTIKHIMNEFTEMASH, Moscow, 1998, p. 8). The furnace includes a convection chamber with convective coils, a radiation chamber with a radiant coil and burners located in the bottom of the furnace. However, the known furnace is designed to heat oil raw materials and is not suitable for operation in the hydrocracking mode due to the removal of the catalyst from the furnace by a high-speed stream of WASH and cracking products and the risk of burnout of pipes.

When creating the invention, the task was to increase the productivity and efficiency of the non-catalytic method of hydrocracking of heavy hydrocarbons with a high sulfur content.

This problem is solved by the method of hydrocracking of heavy hydrocarbon feedstocks, including supplying preheated feedstocks and hydrogen or hydrogen-containing gas to the reactor, subsequent heating in the reactor and withdrawal of cracking products for separation, in which, according to the invention, the reactor includes two chambers - convection with it convective coils and radiation with radiant coils located in it, and the hydrocracking process is carried out in the area of the radiant coil with pipes of variable cross section with zhnosti ensure flow velocity 50-310 m / sec at a temperature of 440-500 ° C.

It is advisable to supply hydrogen or hydrogen-containing gas in an amount of 750 nm ³ / m ^{3 of} raw materials.

This problem is also solved by the proposed hydrocracking reactor, which is a tubular furnace, including a box-shaped body with convection and radiation chambers, in one of which a convective coil is placed, and in the other a radiant coil, moreover, the convective coil is made of pipes of constant section, and burners installed in the hearth of the furnace, in which, according to the invention, the radiant coil is made of pipes of constant and variable cross-section, and the volume of pipes of variable cross-section is 30-50% of the total pipe volume coil-invariant, the floor heating coil made of a tube of variable cross section, is set in the camera on the frame for vertical movement.

It is advisable to install pipes of variable cross section of the radiant coil on the frame by means of brackets.

The frame can be connected by rods with spring shock absorbers mounted on the furnace body.

Pipes of variable cross-section can be performed, for example, according to A.S. No. 1588747, according to which the pipes are made of conical adapters interconnected by large bases in the following aspect ratio

и

and

1,2d≤D≤3,0d,

where D is the diameter of the larger base of the cone, mm;

d is the diameter of the smaller base of the cone, mm;

h is the length of the section of variable cross-section, mm

The process of non-catalytic hydrocracking (i.e., without introducing a catalyst from the side) of oil sulfur feed in the tubes of a coil of variable cross section at a flow speed of 50-310 m / s is carried out due to the difference in speeds and pressures along the length and cross section of the coil, which intensifies the heat and mass transfer between the vapor and liquid phases. Moreover, as the flow moves along the furnace coil due to an increase in its temperature, cracking and evaporation, accompanied by an exponential increase in volume, the flow velocity increases and approaches the speed of sound, while cavitation processes begin to manifest with a local, dynamic increase in pressure exceeding the static inlet pressure in the furnace coil. The formation of peculiar reaction chambers along the axis of the pipe with a variable cross-section makes it possible to enhance the hydrogenolysis reactions of sulfur and unsaturated compounds formed during the cracking of the oil residue in a hydrogen medium. A high degree of dispersion of the raw material opens up the possibility for hydrogen to access the sulfur and organometallic compounds of the residue, which are catalysts for the desulfurization process under the conditions of the proposed method. High dynamic pressure in the coil section with a variable cross section accelerates the diffusion of hydrogen to these compounds and, as you know, their complete hydrogenation is thermodynamically possible at pressures above 20 MPa and a temperature of 427 ° C. Such parameters are achieved in the proposed method, due to which there is a decrease in sulfur content in sulfur oil feedstocks, as well as a decrease in its viscosity and yield in the case of processing heavy feedstocks (oil residues).

The solution of this problem is to increase the productivity and efficiency of the non-catalytic method of hydrocracking by using a once-through reactor, which is a reaction-heating furnace with a coil from pipes of constant and variable cross-section and replacing the indirect electromechanical method of heating from hydrogen compression by direct (contact) heat transfer from the pipe wall heated by the combustion products of the fuel and the torch of the furnace burner.

The method is as follows. Sulphurous crude oil is heated in heat exchangers to a temperature of 280-300 ° C and sent to a raw material tank to control the quality of the furnace loading by mixing with recirculated gas oil or other diluent (from the side), for example, heavy catalytic cracking gas oil. Raw material capacity is also necessary to ensure the stable operation of the furnace pump. The resulting raw material composition is sent to the coil of the furnace for heat treatment at a temperature of 440-500 ° C in a hydrogen environment. To this end, heated hydrogen or a hydrogen-containing gas (Hash) in a ratio of 750 nm ³ / m ^{3 of} raw material is also fed into the furnace coil. The load, as the furnace coil passes, heats up, reaches the decomposition temperature (420-430 ° С) and enters the section with a variable cross-section, where it is cracked in a hydrogen medium at a temperature of 440-500 ° С. Cracked products from the furnace are sent to a distillation column for separation into gas, gasoline, gas oil-recycle and the residue. Cracked products are removed through feed heat exchangers from the unit in a balance ratio. Gas oil is partially returned to the feed tank as a recirculating diluent, and the remaining amount (if necessary) is sent to the bottom residue of the column. Gas after purification from hydrogen sulfide and concentration using membrane sieves is returned to the process.

The proposed method is illustrated by the examples that are shown in the table. These tables were obtained experimentally by calculation. The experiments were conducted on a pilot hydrobreaking unit at a temperature of 450-500 ° C, a hydrogen supply of 750 nm ³ / m ^{3 of} raw materials. The obtained quality indicators of cracking products, material balance were used to calculate the tubular coil of the furnace with a section of variable cross-section.

Example 1. Raw tar with the following quality indicators: density - 990 kg / m ³ , sulfur content - 2.3%, conditional viscosity at 80 ° C - 250, vanadium content - 0.013%, nickel - 0.004%. Data on hydrocracking on this raw material are shown in table 1.

As can be seen from table 1, in all examples of the proposed method there is a decrease in sulfur content in the residue of + 180 ° C in 1.04-2.37 times, viscosity - 1.1-32 times.

Example 2. The raw material mixture of tar with heavy gas oil in a ratio of 1: 1 with the following quality indicators: density 926 kg / m ³ , sulfur content - 1.7%, nominal viscosity at 80 ° C - 2.1, metal content - 0 , 0085%. Data on hydrocracking on this raw material are shown in table 2.

As can be seen from table 2, the yield and sulfur content in the residue of + 180 ° C decreased due to the ease of raw materials, while the coefficient of decrease in sulfur content in the residue of + 180 ° C at the same parameters also decreased by 5-25%, which due to a twofold decrease in the metal content in the feedstock. At the same time, however, the positive effect of desulfurization of the feedstock remains. The viscosity of the initial feed mixture of tar and gas oil is less than the required indicators for commercial boiler fuel M40 and M100, therefore this indicator is excluded from consideration.

Example 3. Raw materials - heavy gas oil with the following quality indicators: density 0.9306 kg / m ³ , sulfur content - 1.28%, does not contain organometallic compounds. In this example, the sulfur reduction coefficient is equal to unity for all parameters of the above examples, that is, the desulfurization process does not occur here, which indicates that the organometallic compounds in the proposed method play the role of a catalyst.

Figure 1 presents the proposed hydrocracking reactor, a side view in section; figure 2 is a front view; figure 3 is a section aa of figure 2.

The hydrocracking reactor for implementing the proposed method is a tubular furnace, including a box-shaped body 1 with thermal insulation 2, a convection chamber 3 with convective coils 4, 5 from pipes of constant cross-section, and a radiation chamber 6 with a radiant coil made up of pipes 7 of constant cross-section and pipes 8 of variable sections. Burners are installed in the furnace hearth 9. Radiant tubes of variable cross section 8 of the coil are mounted on the frame 10 using brackets 11. The frame 10, in turn, is connected by rods 12 with spring shock absorbers 13 mounted on the housing 1. In addition, the furnace is equipped with a chimney 14, line 15 for introducing raw materials into the furnace coil, by a hydrogen-containing gas input line 16, a raw material input line from the convection chamber to the radiation chamber, and a cracking product output line 18 from the furnace to the column (not shown in the figure).

The furnace operates as follows. After starting the installation and heating the furnace with starting gas oil, instead of the starting product, the raw material composition (for example, a mixture of tar and recycle) is fed to the coil of the furnace — stream 15 and hydrogen-containing gas 16 with a temperature of 280-300 ° C. The two-phase flow passes through the pipes 4 of the convection chamber 3, where it is heated due to the heat of the exhaust gases of fuel combustion to a temperature of 370-390 ° C and enters through the overflow 17 into the pipes 7 of the radiation chamber 6, where it is heated by the flame of the burning fuel mixture (fuel-air water vapor) leaving the burner 9 into the furnace furnace space. With the passage of pipes of a constant section of the radiation chamber (approximately 50% along their length), the temperature of the stream increases to the value of decomposition of the raw material (420-430 ° C) and the stream enters the reaction zone made of pipes of variable cross section 8. When cracking the raw material by exponential the volume of the flow increases, accordingly, the flow rate increases and cavitation processes increase. Flow motions, heat and mass transfer processes acquire an avalanche-like character. Under these conditions, during the thermal destruction of high molecular weight sulfur and organometallic complexes, which play the role of catalysts for the desulfurization process, the hydrogenolysis of organosulfur and unsaturated compounds intensifies.

The cracked products of raw materials in a hydrogen medium are withdrawn via line 18 from the furnace and sent to the separation column (not shown in the drawing).

The products of fuel combustion before being released into the atmosphere through the chimney 14 are additionally cooled to a temperature of 220 ° C by removing heat to heat the water passing through the convection coil 5 located in the upper part of the convection chamber 3 of the furnace.

The present invention allows for hydrocracking of sulphurous petroleum feedstock in a hydrogen medium without introducing a catalyst from the side. At the same time, hydrocracking of heavy types of raw materials makes it possible, in addition to desulfurization, to reduce the conditional viscosity at 80 ° C to 12-16, which corresponds to commercial M100 grade boiler fuel, reduce the yield of the residue to 72.5-80% (for raw materials) and increase the yield of gasoline (NK-180 ° C) up to 11.3-16.5%. The productivity of the proposed reactor will be 500 thousand tons / year, which is an order of magnitude higher than that of the prototype, and the efficiency will be at least 90%, which is 2 times higher than that of the prototype.

Table 1. Performance indicators of a hydrocracking reactor. No. Parameters of the furnace coil Technological mode ^*) Yield,% mass. on raw materials The quality of the residue, + 180 ° C The coefficient of decrease in the quality index of PC raw materials / PC residue + 180 ° C

Temperature ° C Flow rate, m / s gasoline residue, + 180 ° C
^**) sulfur content,% viscosity, WU 80 ° С sulfur viscosity one 0.6 3 440 fifty 8.3 86.2 2.15 200 1,07 1.3 2 0.6 3 480 fifty fifteen 74.8 1.55 60 1.48 four 3 0.6 3 500 fifty 15,5 74,2 1,2 27 1.9 9 four 0.6 3 440 180 8 86.7 1.98 138 1.16 1.8 5 0.6 3 480 180 14.5 75.8 1.29 36 1.78 7 6 0.6 3 500 180 16 73,2 1,08 17 2.13 fifteen 7 0.6 3 440 310 11.3 81.2 1.84 86 1.25 3 8 0.6 3 480 310 15.6 74 1.10 twenty 2.09 13 9 0.6 3 500 310 16.5 72.5 0.97 8 2,37 32 10 0.6 1,2 440 fifty 3.6 94 1.97 205 1.16 1,2 eleven 0.6 1,2 480 fifty 12.6 79 1,6 65 1.4 3.9 12 0.6 1,2 500 fifty 14.5 75.8 1.29 36 1.78 7.1 13 0.6 1,2 440 180 6.6 89 2.05 163 1.12 1,5 fourteen 0.6 1,2 480 180 fourteen 76.7 1.37 43 1.68 5.9 fifteen 0.6 1,2 500 180 15.6 74 1.13 22 2 11.6 16 0.6 1,2 440 310 9.5 84.2 1.92 115 1,2 2.2 17 0.6 1,2 480 310 14.6 75.6 1,2 39 1.9 6.5 eighteen 0.6 1,2 500 310 16 73 1,02 12 2.2 21 19 0,035 3 440 fifty 3 95 2.19 215 1.05 1,2 twenty 0,035 3 480 fifty 12 80.1 1.74 76 1.3 3.3 21 0,035 3 500 fifty 13.8 77 1,52 56 1,5 4,5 22 0,035 3 440 180 3,7 93.8 2.18 212 1.05 1,2 23 0,035 3 480 180 12,2 79.7 1.68 72 1.37 3,5 24 0,035 3 500 180 fourteen 76.5 1.45 51 1,58 5 25 0,035 3 440 310 3 94.8 2.18 210 1.05 1,2 26 0,035 3 480 310 13 78 1,64 68 1.4 3,7 27 0,035 3 500 310 fourteen 76.7 1.38 45 1,6 5,6 28 0,035 1,2 440 fifty 2,4 96 2.21 225 2.21 1,1 29th 0,035 1,2 480 fifty 11,4 81 1.84 85 1.84 3 thirty 0,035 1,2 500 fifty 12.3 79.5 1,67 70 1,67 3.6 31 0,035 1,2 440 180 2.7 95.5 2.2 219 1,04 1,1 32 0,035 1,2 480 180 11.3 81.2 1.81 83 1.27 3 33 0,035 1,2 500 180 13.3 77.8 1,63 67 1.4 3.8 34 0,035 1,2 440 310 3.2 94.7 2.18 213 1.05 1,2 35 0,035 1,2 480 310 11.6 80.6 1.78 80 1.29 3.2 36 0,035 1,2 500 310 13.5 77.5 1,57 62 1.46 4.1 ^*) Specific hydrogen consumption 750 nm ³ / m ^{3 **) the} rest: gas + losses

Table 2. Performance indicators of a hydrocracking reactor. No. Parameters of the furnace coil Technological mode ^*) Yield,% mass. on raw materials The sulfur content in the residue + 180 ° C,% Coefficient of decrease in sulfur content in the residue + 180 ° С, S raw materials / S residue + 180 ° С

Temperature ° C Flow rate, m / s gasoline residue + 180 ° C,% ^**) one 0.6 3 440 fifty 14.3 80.2 1,67 1,02 2 0.6 3 480 fifty 19.7 70.1 1.31 1.3 3 0.6 3 500 fifty 20,4 69.3 0.94 1.8 four 0.6 3 440 180 13.5 81.2 1,60 1.06 5 0.6 3 480 180 19.3 71.0 1.06 1,6 6 0.6 3 500 180 20.8 68,4 0.89 1.9 7 0.6 3 440 310 16.5 76.0 1.55 1,1 8 0.6 3 480 310 20,4 69.2 1,0 1.7 9 0.6 3 500 310 21.5 67.5 0.81 2.1 10 0.6 1,2 440 fifty 9.7 87.9 1,62 1.05 eleven 0.6 1,2 480 fifty 17.8 73.8 1.41 1,2 12 0.6 1,2 500 fifty 19.3 71.0 1.06 1,6 13 0.6 1,2 440 180 13.1 82.5 1,59 1,07 fourteen 0.6 1,2 480 180 19.8 70.9 1.13 1,5 fifteen 0.6 1,2 500 180 21.1 68.5 0.94 1.8 16 0.6 1,2 440 310 15.9 77.8 1,54 1,1 17 0.6 1,2 480 310 19.6 70.6 1.06 1,6 eighteen 0.6 1,2 500 310 21.7 67.3 0.89 1.9 19 0,035 3 440 fifty 9.5 88.5 1.7 1,0 twenty 0,035 3 480 fifty 17.4 74.7 1.55 1,1 21 0,035 3 500 fifty 19.3 71.5 1.30 1.3 22 0,035 3 440 180 10.6 86.9 1.70 1,0 23 0,035 3 480 180 17.9 74.0 1.4 1,2 24 0,035 3 500 180 19.3 71.2 1.3 1.3 25 0,035 3 440 310 10.3 87.5 1.7 1,0 26 0,035 3 480 310 18.3 72.7 1.3 1.3 27 0,035 3 500 310 19.8 70.9 1,2 1.4 28 0,035 1,2 440 fifty 8.9 89.5 0.81 2.1 29th 0,035 1,2 480 fifty 17.8 74.6 1.06 1,6 thirty 0,035 1,2 500 fifty 18.0 73.8 1.13 1,5 31 0,035 1,2 440 180 10.3 87.9 1.7 1,0 32 0,035 1,2 480 180 16.9 75.6 1.55 1,1 33 0,035 1,2 500 180 19.8 71.3 1.41 1,2 34 0,035 1,2 440 310 10.3 87.6 1.7 1,0 35 0,035 1,2 480 310 17.7 74.5 1.48 1.15 36 0,035 1,2 500 310 18,4 72.6 1.31 1.3 ^*) Specific hydrogen consumption 750 nm ³ / m ^{3 **) the} rest: gas + losses

Claims (6)

1. The method of hydrocracking of heavy hydrocarbon feedstock, comprising supplying preheated feedstock and hydrogen or a hydrogen-containing gas to the reactor, subsequent heating in the reactor and output of the cracking products for separation, characterized in that the reactor includes two convection chambers with convection coils placed therein , and radiation, with radiant coils located in it, and the hydrocracking process is carried out on the site of the radiant coil of the reactor with pipes of variable cross-section with the possibility of providing speed and flow 50-310 m / s at a temperature of 440-500 ° C. 2. The method according to claim 1, characterized in that hydrogen or a hydrogen-containing gas is supplied in an amount of 750 nm ³ / m ^{3 of} raw material. 3. The hydrocracking reactor, which is a tubular furnace, including a box-shaped body with convection and radiation chambers, one of which contains a convective coil, and the other a radiant coil, the convective coil made of pipes of constant diameter, and burners installed in the hearth of the furnace characterized in that the radiant coil is made of pipes of constant and variable cross-section, and the volume of pipes of variable cross-section is 30-50% of the total volume of pipes of the radiant coil, while the radiant coil made from pipes of variable cross-section, mounted in the chamber on the frame with the possibility of vertical movement. 4. The reactor according to claim 3, characterized in that the pipes of variable cross-section are mounted on the frame by means of brackets. 5. The reactor according to claims 3 and 4, characterized in that the frame is connected by rods with spring shock absorbers mounted on the furnace body. 6. The reactor according to claims 3 and 4, characterized in that the pipes of variable cross-section are made of conical adapters interconnected by large bases in the following aspect ratio

and 1.2d≤D≤3.0d, where D is the diameter of the larger base of the cone, mm; d is the diameter of the smaller base of the cone, mm; h is the length of the section of variable cross-section, mm

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