RU2544994C1 - Method and unit for oil preliminary distillation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the method of the preliminary oil distillation, where during oil distillation in atmosphere and vacuum rectifiers with production of the benzene and diesel fractions, atmosphere and vacuum gasoil and tar the first and second atmosphere rectifiers are equipped with semi-dead trays, that are connected by pipelines, respectively with the second atmosphere rectifier and vacuum column ensuring creation of the additional liquid refluxing.

EFFECT: reduced power consumption for the process and rational use of heavy oil fraction removed from semi-dead tray of the second atmosphere column.

3 cl, 1 dwg, 3 tbl

Description

The invention relates to methods of primary oil refining to obtain straight-run fractions and can be used in the oil refining industry.

A known method of distillation of oil sequentially in atmospheric and vacuum columns to obtain distillate fractions and the residue of distillation. One of the important indicators of the efficiency of distillation is an increase in the depth of selection of these fractions, which is achieved at the stage of vacuum distillation by deepening the vacuum, increasing the temperature, and using an evaporating agent (Kreimer M.L., Sat. Refinery Handbook, L., Chemistry, 1986, p. 68 -69; Akhmetov S.A. Technology for the deep processing of oil and gas, Ufa, Gilem, 2002, p. 222-224). All these methods have a number of limitations: deepening the vacuum is limited by the increase in energy consumption and the existing level of vacuum technology, the temperature increase is limited by insufficient thermal stability of the distillation residue, the increase in the amount of evaporating agent is limited by a concomitant decrease in the temperature of the residue, which leads to a decrease in the partial pressure of hydrocarbon vapors and a corresponding decrease in the efficiency of their stripping . In this regard, various methods are proposed for increasing the efficiency of the distillation process as a whole.

There is a known method of distillation of oil to obtain straight-run fractions and the distillation residue, according to which the diesel fraction and residue (fuel oil) obtained in the atmospheric column are sent to the vacuum column, the diesel fraction being supplied to the distillation section and acting as an evaporating agent, and the fuel oil to the zone power supply (patent for the invention RU No. 2043387, C10G 7/06, claimed 02.12.1992, published 10.09.1995). Straight-run diesel and gas oil fractions and the final distillation residue, tar, are removed from the vacuum column, which is sent to an additional vacuum evaporator to remove hydrocarbons of the evaporating agent. The use of a diesel fraction as an evaporating agent increases the cost of distillation of oil as a whole, since the formation of this fraction into a product stream — into commercial diesel fuel — is carried out twice in an installation, first in an atmospheric column and then in a vacuum. In addition, the need for secondary evaporation of the tar is a disadvantage of this method.

There is also known a method of oil distillation sequentially in atmospheric and vacuum columns, according to which the distillate fraction (diesel fraction) and residue (fuel oil) obtained in the atmospheric column are sent to the vacuum column, the fuel oil being fed into the feed zone, and the distillate fraction is divided into steam and the liquid part, after which the steam part is fed into the distillation section and acts as an evaporating agent, and the liquid part is used as one of the target products (patent for invention SU No. 1685974 A1, C10G 7/06, application n July 11, 1989, published October 23, 1991). Distillate fractions are removed from the vacuum column and the final distillation residue is tar. The evaporating agent - the light part of the diesel fraction - together with hydrocarbons stripped from the tar, is removed from the top of the vacuum column. Moreover, the presence of such an evaporating agent in the total vapor stream in the upper part of the column leads to a corresponding increase in the cost of condensing the vapor stream, which is a drawback of the scheme as a whole.

There is also known a method of distillation of oil closest to the claimed invention, including regenerative heating of oil, its partial topping in the first atmospheric column with the selection of light gasoline fraction from the top of the column, heating the remainder of the first atmospheric column in the furnace with its supply to the feed zone of the second atmospheric column for separation of the topped oil to the heavy fraction of gasoline, kerosene, diesel fuel and fuel oil, then sent as a raw material to a vacuum column with its preliminary heating in an oven, with selection from a moat of atmospheric side-stream column, which is taken from the bottom half-deaf plate of the reinforcing section of the column, with a heavy straight-run fraction taken from the second atmospheric column, side taken of the bottom half-deaf plate of the reinforcing section (patent RU No. 2484122, C10G 7/02, B01D 3/14, announced March 20, 2012, published June 10, 2013). The disadvantages of this invention are the need for additional energy-intensive processing of the heavy straight-run fraction withdrawn from the second atmospheric column with a side stream from the bottom half-deaf plate of the reinforcing section in the secondary processes of catalytic or thermal cracking and the possibility of partial contact of the side overhead components that are taken from the bottom half-deaf plate of the reinforcing section sections of the first atmospheric column.

A unit for primary oil refining is also known, including the first and second atmospheric distillation columns, vacuum distillation columns, strippers, furnaces, boilers, refrigerators, tanks and pumps, interconnected by pipelines, pipelines for inputting initial oil and for outputting oil distillation products, implementing a typical scheme process (patent for invention RU No. 2063999, C10G 7/06, C10G 7/00, B01D 3/14, filed October 12, 1993, published July 20, 1996). The main disadvantage of the installation is the low clarity of the separation of oil hydrocarbons into necessary fractions, which reduces the completeness of the selection of light oil products from their potential content in the original oil.

Also known is a primary oil refining unit closest to the claimed invention, including the first and second atmospheric distillation columns, stripping columns, furnaces, boilers, refrigerators, tanks and pumps, interconnected by pipelines, pipelines for inputting initial oil and for outputting oil distillation products, while atmospheric distillation columns are equipped with half-deaf plates, half-deaf plate of the first atmospheric distillation column is connected by a pipe to a half-deaf plate second atmospheric distillation column, from which atmospheric gas oil is discharged, while the bottom of the second atmospheric distillation column is connected to a vacuum column (patent for invention RU No. 2484122, C10G 7/02, B01D 3/14, filed March 20, 2012, published June 10, 2013) . The disadvantages of this invention are the need for additional energy-intensive processing of atmospheric gas oil and the possibility of getting into it an unevaporated part of hydrocarbons falling on the half-deaf plate of the second atmospheric distillation column from the half-deaf plate of the first atmospheric distillation column, involving them in this case in the reprocessing with the need for additional capital and operating costs .

The task of the invention is to reduce the energy costs of the process and the rational use of the heavy oil fraction discharged from the half-deaf plate of the second atmospheric column.

The problem is solved due to the fact that in the method of primary distillation of oil, including regenerative heating of oil, its partial topping in the first atmospheric column with the selection of light gasoline fraction from the top of the column, heating the remainder of the first atmospheric column in the furnace with its supply to the second atmospheric feed zone columns for separation of stripped oil into a heavy fraction of gasoline, kerosene, diesel fuel and fuel oil, which is then sent as a raw material to a vacuum column with its preliminary heating in a furnace with selection from the first atmospheric side stream column, which is a heavy gasoline fraction, and is taken from the lower half-deaf plate of the reinforcing section of the column, with the side atmospheric gas oil side taken off from the second atmospheric column, which is taken from the lower half-deaf plate of the reinforcing section, the side stream, which is a heavy gasoline fraction , and taken from the lower half-deaf plate of the reinforcing section of the first atmospheric column serves on the plates located above the lower half-deaf plate of the reinforcing with section of the second atmospheric column, the fuel of the second atmospheric column in the vacuum column is divided into gas, diesel fuel, light vacuum gas oil, heavy vacuum gas oil and tar, side overhead of the heavy straight-run fraction taken from the lower half-deaf plate of the reinforcing section of the second atmospheric column is fed to the lower layer for irrigation nozzles of the concentration part of the vacuum column located above the feed zone with the remainder of the second atmospheric column. The proposed transfer of a part of a low-quality product from half-deaf plates from the first atmospheric column to the second atmospheric column and from the second atmospheric column to the vacuum column allows in both cases to lead to the same improvement in the fractionation principle due to the following factors:

- the transfer of a low-quality product as an equilibrium liquid phase from half-deaf plates from a higher pressure column to a lower pressure column allows at least part of this low-quality product to be evaporated without heating it in the furnace, which reduces fuel consumption in the furnace compared to the joint by heating this low-quality product with the remainder of the column, from which lateral overhead is not discharged;

- the introduction of the evaporating low-quality product into the distillation column with a lower pressure leads to an increase, respectively, of steam irrigation in the plate package above the entry position of the evaporating low-quality product and to increase, respectively, liquid irrigation in the plate package below the entry position of the evaporating low-quality product, which will increase the coefficient of useful the actions of these plates and the clarity of the separation of oil on these plates.

The solution to this problem is also achieved by the fact that in the installation, including the system of recuperative heating of oil, the first and second atmospheric distillation columns, stripping columns, furnaces, boilers, refrigerators, tanks and pumps, interconnected by pipelines, pipelines for inputting the initial oil and for distillation products oil, while atmospheric distillation columns are equipped with half-deaf plates, a half-deaf plate of the first atmospheric distillation column is connected by a pipeline with a half-deaf container a second atmospheric distillation column, from which atmospheric gas oil is discharged, while the bottom of the second atmospheric distillation column is connected to a vacuum column, the lower part of the reinforcing section of the first atmospheric column in the half-deaf plate zone is connected by a lateral overhead discharge pipe, which is a heavy gasoline fraction, to the concentration part the second atmospheric column is higher than the position of the half-deaf plate of this column, and the lower part of the reinforcing section of the second atmospheric column in the half-gap zone oh plates associated output conduit atmospheric gas oil with the concentration of the vacuum tower above the injection point in a heated vacuum column in fuel oil furnace.

It is advisable that as a contact device in the vacuum column used cross-head nozzle.

The invention is illustrated in the drawing, where figure 1 shows a diagram of a proposed installation of primary distillation of oil by the proposed method of primary distillation of oil. The scheme of the primary oil distillation installation includes the following items:

10, 20 - the first and second atmospheric columns, respectively,

30 - vacuum column

40, 50 - stripping column,

60, 70, 80 - oven,

90, 100 - heat exchanger,

110, 120 - condenser-refrigerator,

130 - boiler

140, 150, 160, 170 - circulation irrigation,

1-9, 11-19, 21-29, 31-37 - pipelines.

The proposed method for the primary distillation of oil is as follows. The oil heated in heat exchangers and an atmospheric furnace is fed to the first atmospheric column 10, from which the gasoline fraction, liquid side stream and residue (stripped oil) are withdrawn, while the gasoline fraction is sent for further processing, and the liquid side stream, which is a heavy gasoline fraction, and the remainder of the first atmospheric column is sent to the second atmospheric column 20: the liquid side stream by gravity due to the pressure difference in the columns 10 and 20 enters the plates located above the lower half-deaf container ki of the reinforcing section of the second atmospheric column 20, and the residue after heating in the furnace also enters the second atmospheric column 20, from where gasoline vapor condensed in the condenser-cooler 120 is removed from the top. Part of the condensate is returned to the column 20 for irrigation, and the balance part of the condensate Allocated for further processing. Non-condensing vapors are removed from the unit. Side shoulder straps of kerosene and diesel fuel fractions are removed from the reinforcing section of the second atmospheric column to stripping columns, from which kerosene and diesel fuel are removed, and the stripped light fractions from stripping columns are returned to atmospheric column 20. The kerosene is stripped using the lower part of the boiler, and diesel fuel is supplied with steam. From the lower half-deaf plate of the reinforcing section of the second atmospheric column 20, liquid lateral overhead (atmospheric gas oil) is diverted to irrigate the lower layer of the nozzle of the concentration part of the vacuum column 30 located above the feeding zone with the remainder of the second atmospheric column 20, from where fuel oil is transferred to the furnace from the bottom and then to the vacuum column 30, in the lower part of which water vapor is supplied for stripping of fuel oil. Diesel fuel, light and heavy vacuum gas oils and tar are discharged from the vacuum column 30.

The primary oil distillation unit operates as follows: incoming desalted and dehydrated oil through pipeline 1 is preheated in a recuperative heat exchanger 90, then desalted and dehydrated oil heated to a predetermined temperature through pipeline 2 enters the first atmospheric column (pre-evaporation column) 10, from the top of which vapors of gasoline, water and gas are sent through pipeline 3 to an air condenser-cooler 110, then to a separator (shown in Fig. 1), from where it is diverted through pipeline 4 GSI gas through conduit 5 and condensed liquid (light gasoline), a part of it through the line 6 back to the first atmospheric column 10 as reflux acute and the remainder removed through line 7 as a light gasoline to further processing. The first atmospheric column 10 is provided in the reinforcing section with a half-deaf plate and connected by a pipe 8 to the second atmospheric column 20. From the bottom of the first atmospheric column 10, the pipe 9 is connected to the furnace coil 60, the outlet of which is connected by a pipe 11 to the first atmospheric column 10, and to the heat exchanger inlet 100, the output of which is connected to the coil of the furnace 70, the output of which is connected by a pipe 13 to the lower part of the second atmospheric column 20, into the lower part of which water vapor is supplied through the pipe 28. From the top of the second atmospheric column 20, gasoline vapors are discharged through a pipe 14, which are cooled and condensed in a condenser-cooler 120, then sent to a separator (not shown in Fig. 1), after which gases are discharged through a pipe 15, and condensed gas through a pipe 16 , part of which is returned via pipeline 17 to the upper plate of the second atmospheric column 20, and the balance amount of gasoline is withdrawn from the process through pipeline 18. The middle part of the reinforcing section of the second atmospheric column 20 is piped the output of the kerosene and diesel fractions 19 and 23 is connected to stripping columns 40 and 50, respectively, from the top of which the pairs through pipelines 21 and 24, respectively, are returned to the second atmospheric column 20. The kerosene fraction is stripped using a boiler 130 located in the lower part stripping column 40, and stripping of the diesel fraction - with the supply of water vapor to the lower part of the stripping column 50. The bottom of the stripping columns 40 and 50 is equipped with pipelines output kerosene and diesel fuel, respectively 22 and 25. The second atmosphere The column 20 is equipped with two circulating irrigation 140 and 150 along the height of the column, that is, the flow is diverted from the column, cooled in heat exchangers and returned to the side output plates, in the lower part of the reinforcing section of the second atmospheric column 20, a half-blind plate, which is connected by a 27 s pipe a vacuum column 30. A pipe 29 connects the lower part of the second atmospheric column 20 to the coil of the furnace 80, the outlet of which is connected by a pipe 31 to the lower part of the vacuum column 30. From the top of the vacuum column 30 through a pipe non-condensable gases and water vapor are discharged to water 32; tar is pumped out from below through a conduit 37. Two circulating irrigations 160 and 170 are organized along the height of the reinforcing section of the vacuum column 30. Diesel fuel, light and heavy vacuum gas oils, respectively, are discharged by side shoulder straps from the vacuum column 30 through pipelines 33, 34 and 35.

Comparison of the proposed method of primary distillation of oil with the prototype was carried out by mathematical modeling of the process of primary oil refining in relation to the distillation of West Siberian oil. Partially stripped in the first distillation column and heated to a temperature of 352 ° C, oil in an amount of 440 t / h is sent to the second atmospheric column - both according to the prototype and the proposed method. At the bottom of the second atmospheric column serves 1.0 t / h of water vapor. The temperature in the upper part of the second atmospheric column is 164 ° C, and the pressure is 0.17 MPa, the temperature in the lower part is 336 ° C. A gasoline fraction with a boiling point of 180 ° C is removed from the top of the second atmospheric column, diesel fuel and atmospheric gas oil are removed from the side straps, fuel oil is heated from the bottom of the second atmospheric column, which is heated to 390 ° C in a vacuum oven and fed to the vacuum column. To ensure objectivity in comparing the operation of the columns according to the prototype and according to the proposed method, the operating mode of the vacuum column is selected in such a way as to obtain the same quality of all products, the corresponding indicators are shown in tables 1 and 2. According to the data presented in table 1, according to the proposed method, it is possible to increase the production of diesel fuel in a vacuum column from 13.4 to 33.4 t / h, i.e. by 149%, as well as vacuum gas oil from 50 to 80 t / h, i.e. by 60%, by supplying atmospheric gas oil, bottom to ugluhoy plates rectifying section atmospheric second column in an amount of 50 t / h to reflux of the lower layer part of the vacuum nozzle of the concentration column. The total yield of diesel fuel in the installation compared with the prototype increased from 142.7 to 162.7 t / h, that is, 14.8%, the fractional composition of the total diesel fuel according to the claimed invention almost coincides with the prototype (table 2). In this case, additional equipment for the processing of atmospheric gas oil is not required.

For the removal of heat in a vacuum column, circulation irrigation is used: in the top of the column and in the middle of the strengthening part at the output level of the vacuum gas oil. The pressure in the upper part of the vacuum column is 6.5 kPa, the top temperature is 198 ° C, and the bottom of the column is 369 ° C. Vapors leaving the top of the column are condensed at 40 ° C, the condensed part is removed as vacuum diesel fuel, non-condensed vapors are sucked off using a vacuum-generating system. To implement this mode of operation of the prototype and the proposed method, the corresponding energy costs are required, the characteristics of which are presented in table 3. Comparing the presented performance indicators of the vacuum column of the prototype and the proposed method, it follows that when the products are of the same quality, the energy costs in the form of additional heat removal in the capacitor and using circulating irrigation in the claimed invention is higher than in the prototype, however, given the low cost of circulating refrigerant in the condenser and the possibility of recuperative use of heat removed by circulation irrigation, as well as an increase in the yield of diesel fuel in the vacuum column by 149% and vacuum gas oil by 60% without the use of additional technological equipment, the proposed technical solution is appropriate.

The proposed method is practically applicable, because it is based on the use of existing devices and known technological methods, while ensuring an increase in the yield of target products without further processing of intermediates.

Claims (3)

1. The method of primary distillation of oil, including regenerative heating of oil, its partial topping in the first atmospheric column with the selection of light gasoline fraction from the top of the column, heating the remainder of the first atmospheric column in the furnace with its supply to the feed zone of the second atmospheric column for separation of the topped oil into heavy fraction of gasoline, kerosene, diesel fuel and fuel oil, which is then sent as a raw material to a vacuum column with its preliminary heating in an oven, with selection of side stream from the first atmospheric column the second one is a heavy gasoline fraction from the lower half-deaf plate of the reinforcing section of the column, with side atmospheric gas oil being taken from the second atmospheric column, which is taken from the lower half-deaf plate of the strengthening section, characterized in that the side stream, which is a heavy gas fraction and taken from the bottom the half-deaf plate of the reinforcing section of the first atmospheric column is served on the plates located above the lower half-deaf plate of the reinforcing section of the second atmospheric column, ma the sludge of the second atmospheric column in the vacuum column is divided into gas, diesel fuel, light vacuum gas oil, heavy vacuum gas oil and tar, the side overhead of the heavy straight-run fraction taken from the lower half-deaf plate of the reinforcing section of the second atmospheric column is fed to the lower layer of the nozzle of the concentration part of the vacuum columns located above the feeding zone with the remainder of the second atmospheric column. 2. The installation of the primary distillation of oil, including the first and second atmospheric distillation columns, stripping columns, furnaces, boilers, refrigerators, tanks and pumps, interconnected by pipelines, pipelines for inputting initial oil and output of products of distillation of oil, while atmospheric distillation columns are equipped with semi-deaf plates, the half-deaf plate of the first atmospheric distillation column is connected by a pipeline to the half-deaf plate of the second atmospheric distillation column, from which atmospheric gas oil, while the bottom of the second atmospheric distillation column is connected to a vacuum column, characterized in that the lower part of the reinforcing section of the first atmospheric column in the area of the half-deaf plate is connected by a lateral overhead discharge pipe, which is a heavy gasoline fraction, to the concentration part of the second atmospheric column above the position of the half-deaf plate of this column, and the lower part of the reinforcing section of the second atmospheric column in the area of the half-deaf plate is connected by an atmospheric outlet pipe ferrous gas oil with the concentration part of the vacuum column above the point of introduction of the fuel oil heated in the furnace into the vacuum column. 3. The primary oil distillation unit according to claim 2, characterized in that a cross-flow nozzle is used as contact devices in the vacuum column.

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