RU2419480C2 - Plant to separate c1-4еc5 hydrocarbons and higher from water - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to oil and gas treatment and may be used in oil-and-gas industry. Proposed plant comprises housing, internal perforated tube and external perforated shell ring, tightly separated chambers receiving initial gas mix and cooling water and discharging cooling water, C₅ fraction discharge branch pipe and C_1-4 hydrocarbon fraction discharge branch pipe, rotary filter and filter cooling system made up of cooling tubes. Rotary filter is made up of cylindrical cartridges filled with sorbent from polyolefin fibers and arranged between, internal tube and external perforated shell ring. Cartridges are fitted one into another and arranged between cooling tubes tightly connected with upper cooling water distributor and cooling water drain hollow shaft. Cartridge sidewalls are made from perforated metal with cell size of 1-3 mm. Proposed plant comprises also absorber for afterpurification of C_1-4 hydrocarbons consisting of two columns filled with sorbent, condensate collector, C_1-4 fraction discharge branch pipe and system to feed compressed gas for regeneration purposes.

EFFECT: higher quality of gas purification and C_1-4 fraction separation by simple procedure in continuous processing conditions.

2 cl, 3 dwg

Description

The invention relates to techniques for the preparation of oil and gas for transport through pipelines and can be used in gas and oil industries.

When preparing gas for transport, it is necessary to extract water and C ₅ and higher hydrocarbons from it, since water vapors and C ₅ and higher hydrocarbons condense with decreasing temperature, forming liquid, ice and hydrate plugs in pipelines.

To achieve the objectives, operations are performed cleaning, drying, compressing gas, extracting gasoline fractions from raw gas [Churakaev A.M. Oil refining. - M .: Nedra, - 1983, - 279 p.].

The following devices and methods are known for gas separation and purification:

- gas separation system for several adsorbents [Application No. 0248720, MKI 4 B01D 53/04, publ. 12/09/1987, Bull. No. 50];

- removal of impurities C ₅ and above by their absorption [Application No. 0247585, MKI 4 B01D 53/14, publ. 12/02/1987, Bull. No. 49. A.S. No. 835461, MKI B01D 19/00, publ. 1981, Bull. No. 21. A.S. No. 1068141, MKI B01D 19/00, publ. 01/23/1984, Bull. Number 3];

- separation on gas-liquid separators [A.S. No. 585856, MKI B01D 17/06, publ. 1977, bull. No. 48. A.S. No. 801855, MKI B01D 45/08, publ. 1981, Bull. No. 5. A.S. No. 860829, MKI B01D 45/18, publ. 1981, Bull. No. 33];

- the use of filter nozzles on adsorption columns [A.S. No. 1068142, MKI B01D 19/00, publ. 01/15/1984, Bull. No. 2. A.S. No. 2323835, MKI B01D 3/00, publ. 02/14/1985, Bull. No. 2].

The disadvantage of all these devices is multi-stage, high energy intensity and the lack of the ability to conduct simultaneous separation of water and hydrocarbons C ₅ and above from the fraction C _1-4 . The equipment is large, metal-intensive and has a great cost.

Closest to the proposed installation is a device for cleaning gas from impurities according to the patent of the Russian Federation No. 2095122, MKI 6 B01D 45/12, publ. November 10, 1997, containing a vertical cylindrical body with a tangential inlet pipe, a gas outlet pipe and a liquid discharge fitting, a horizontal partition and a rotor made in the form of a perforated glass. Two shells are installed coaxially and with a gap in the perforated cup, one of which adjacent to the perforated cup is solid and the other perforated, while both shells do not reach the bottom of the perforated cup and are adjacent to the outer and inner diameters of the annular tray mounted under them. The end of the drain pipe is brought into the cavity of the vertical cylindrical body. The disadvantages of the device include a low degree of purification of C _1-4 gases from other hydrocarbons. In addition, a separate dehydration step is required, for example, using diethylene glycol.

The objective of the invention is to improve the quality of gas purification and ensuring the separation of the C _1-4 fraction from water and heavier hydrocarbons in continuous mode "condensation of water and C ₅ and higher hydrocarbons with subsequent removal of condensate from the installation", the installation can also be used in oil preparation processes transport for its degassing.

The technical result of the present invention is the creation of an inexpensive and easy to maintain installation for the separation of hydrocarbons using fibrous sorbents from polyolefins. In such a sorbent, capillary forces are acting that retain hydrocarbons at a cassette rotation speed of less than 600 rpm; the fibrous sorbent is not deformed under the action of centrifugal forces arising from cassette rotation at a speed of less than 3000 rpm. When using higher rotation speeds, the density of the packing of the cassettes with fiber should be increased to 240 kg / m ³ . The possibility of using polyolefin fibers as sorbents, their physico-chemical characteristics and optimal parameters of the fibrous filter nozzles in relation to the inventive installation have been experimentally studied and obtained by the applicant. These results are partially published in the works of [S.V. Bordunov, V.V. Bordunov. "Fibrous materials from waste thermoplastics for filtering water and air." Anniversary scientific readings "White Nights 2008". Materials of international scientific readings. Part 1. St. Petersburg-2008, pp. 424-426 and V.V. Bordunov, S.V. Bordunov, V.V. Leonenko. "Water purification from oil and oil products." Ecology and industry of Russia. August 2005, p.8-10].

Figure 1 schematically shows an installation for preparing gas for transport by removing water and hydrocarbons of C ₅ and above from the source gas, where:

1 - a stream of liquid water and hydrocarbons With ₅ and above; 2 - guide shelves; 3 - cooling shirt; 4 - external perforated shell; 5 - fibrous sorbent; 6 - cooling pipes; 7 - upper distributor of cooling water; 8 - an internal pipe; 9 - bearings with a seal; 10 - coupling; 11 - upper cooling chamber; 12 - engine; 13 - rotating filter; 14 - pipe water supply; 15 - removable cylindrical cassettes; 16 - pipe outlet fraction _1-4 ; 17 - a stream of gaseous fractions With _1-4 ; 18 - pipe input cooling water; 19 - a hollow shaft of the drain of cooling water; 20 - pipe input of the initial mixture of gases; 21 - lower chamber; 22 - cooling water outlet pipe; 23 - a collection of cooling water; 24 - pipe outlet fractions With ₅ and above; 25 - installation casing; 26 - lattice; 27 - refrigerator; 28 - pipe outlet hydrocarbons With _1-4 ; 29 - gas supply valve for the regeneration of columns; 30 - source of compressed gas; 31 - columns; 32 - condensate collector; 33 - valve discharge into the atmosphere of excess pressure; 34 - valve for supplying gas to the column.

Installation works as follows.

To rotate the filter 13 include an electric motor 12. Sealing and rotation of the filter 13 is provided by bearings with a seal 9, which separate the upper cooling chamber 11 from the engine 12 and the upper cooling water distributor 7. In the lower part of the pipe 8 located inside the hollow shaft 19 and the lower chamber 21, bearings with a seal 9 are also installed. The shaft of the engine 12 is connected to the upper cooling water distributor 7 by a coupling 10. Thus, the filter 13 is rotated and the input mixture entry chambers 21 are sealed hydrocarbons and water from the housing 25. In the housing 25, cooled by the water flowing through the pipe 18 to the cooling jacket 3, an initial mixture of gases is supplied through the pipe 20 and the chamber 21. The gas mixture through the inner pipe 8, hermetically mounted on the upper distributor of cooling water 7, through the upper perforated part of the pipe 8 with a mesh size of 1-3 mm, it enters removable cylindrical cassettes 15 filled with a sorbent 5 of polyolefin fibers, in the pores of which there is capillary condensation of water and hydrocarbons C ₅ and higher. The recommended density of packing cassettes 15 with a fibrous sorbent with a fiber diameter of 30-100 μm is 155 ± 5 kg / m ³ , with a fiber layer thickness in each cassette of 15-20 mm with a total number of cassettes of at least 5. Choice of the number of cassettes, fiber diameter and thickness the sorbent layer is determined based on the composition of hydrocarbons and the pressure of the gas mixture supplied to the installation, and is determined based on the pressure drop (ΔP, Pa) on the filter depending on the volumetric flow rate of the gas mixture (V, m ³ / s) according to the empirical formula

ΔP = 0.55V ^0.5708 ,

derived on the basis of experimental data on the separation of hydrocarbon gas condensate, determined on a filter with a packing density of fiber 155 ± 5 kg / m ³ . Fibers with a diameter of less than 30 microns are undesirable due to an increase in resistance (for a fiber with a diameter of 10 microns, the pressure drop is an order of magnitude higher than for fibers with a diameter of 30 microns), and filters with a diameter of more than 100 microns show a breakdown of heavy hydrocarbons. In the range of fiber diameters from 30 to 100 μm, breakthrough of heavy hydrocarbons is not observed with a total filter thickness of 75-100 mm, which is the reason for the minimum number of cassettes 5 with a minimum thickness of the sorbent layer in each cassette of 15 mm. To increase the sorbent layer in cassettes 15 more than 20 mm is impractical due to the difficulty of cooling it with pipes 6.

Removable cartridges 15 are inserted one into another between the inner pipe 8, the outer perforated shell 4 and the cooling pipes 6, are clamped by the upper distributor of cooling water 7 and the hollow shaft of the chilled water drain 19. The distance between two adjacent cartridges 15 is equal to the diameter of the pipe 6. Cooling pipes 6 are installed only between the cassettes 15. The cooling pipes 6 are installed in increments between the centers of the holes of the pipes equal to the two diameters d of the pipes 6 and are hermetically connected to the upper distributor of cooling water 7 and the hollow shaft of the drain cooling water 19. Schematically shown in Figure 2. The side walls of the cassettes are made of perforated metal with a mesh size of 1-3 mm. With smaller cell sizes, the hydraulic resistance increases sharply. In this case, it is necessary to increase the speed of rotation of the cassettes and the density of their packing with fiber, which leads to a decrease in the capacity of the sorbent for hydrocarbons, and with large cell sizes, it is likely that some of the thin fibers will be removed from them. The presence of free space between the cassettes allows you to organize the flow of condensate flowing from the cassettes into the bottom of the rotating filter 13 along the walls of adjacent cassettes. As a result of this, the amount of condensate adsorbed by the sorbent 5 decreases from the center to the perimeter, and the external cassette performs the function of finishing gas purification from water and hydrocarbons C ₅ and higher. Liquid condensate from water and C ₅ and higher hydrocarbons is removed mainly from the bottom of the cassettes, which increases the quality and efficiency of the process of separation of hydrocarbons and removal of water from gases, as in the pores of the upper part of the sorbent in cassettes, starting from the second cassette from the center , there is free space for condensate and the possibility of movement of the non-condensing part of the shared gas mixture.

To cool the rotating filter 13 and the fibrous sorbent 5 and maintain the necessary conditions for the capillary condensation of hydrocarbons C ₅ and above, it is provided with water cooling, which passes through the pipe 14 to the upper cooling chamber 11, the upper water distributor 7, through pipes 6 through the lower cooling water collector 19 v a collection of cooling water 23 and flows through the pipe 22.

The working speed of rotation of the electric motor 12 of the filter 13 with the sorbent 5 is in the range of 700-3000 rpm Under the action of centrifugal forces, a rotating filter 13 through an external perforated shell 4 with a mesh size of 1-3 mm, liquid hydrocarbons are discharged from the filter and flow through the shelves 2, located at an angle of 50-70 ° to the internal axis of the unit, into the condensate outlet pipe 24 . Between the shelves 2 and the housing 25 there is a gap for the condensate to move down 1 to the pipe 24 and the gaseous fraction C _1-4 up 17 to the pipe 16.

Figure 3 shows the adsorber, which is an integral part of the installation. Part of C ₅ and higher hydrocarbons in the form of thin aerosols and gas (which is caused by the vapor pressure of these hydrocarbons at the installation temperature), are carried away by the gas flow C _1-4 through the pipe 16, valves 34, including one or the other adsorber column, are fed into the interlattice space 1/3 of the height from the lower lattice of the column 31, where the final purification of fraction C _1-4 from hydrocarbons C ₅ and higher takes place. The columns contain two gratings 26, the space between which is filled with sorbent 5. The capillary condensation of hydrocarbons C ₅ and higher is carried out in the pore space of the sorbent 5, cooled by water flowing through the refrigerator 27, into which it is introduced through nozzles 18. The hydrocarbon content is C ₅ and higher, entering together with the C _1-4 fraction into the adsorption column does not exceed 0.1-0.3 mass% with respect to the mass of the C _1-4 fraction. These hydrocarbons condense in the volume of the fibrous sorbent 5, which fills the space in the column between the gratings 26, and under the pressure of gases C _{1-4, the} condensate accumulating in the sorbent moves down the pores in the sorbent and then is removed from the column into the condensate collector 32, which is equipped with a discharge valve overpressure atmosphere 33. The fraction C _1-4 purified from hydrocarbons C ₅ and higher is discharged from the column through the pipe 28. One of the columns is in operation, and the second is being regenerated. The regeneration is carried out by the compressed gas supply system 30 (nitrogen, air) to the top of the column using gas supply valves 29. The gas displaces hydrocarbons C ₅ and above into the reservoir 32 from the pore space. The excess pressure from the column and collector is vented through valve 33. After regeneration the columns are switched by a valve system 34.

The degree of separation of hydrocarbons in the installation for the separation of hydrocarbons With _1-4 from other hydrocarbons and water is not less than 99.7%.

Claims (2)

1. Installation for the separation of hydrocarbons C _1-4 from C ₅ and above and water, comprising a housing, an internal perforated pipe and an external perforated shell, characterized in that it contains hermetically separated chambers for introducing an initial mixture of gases, cooling water, cooling water outlet, pipe the output of the fraction C ₅ and higher and the outlet pipe of the hydrocarbon fraction C _1-4 , a rotating filter made in the form of cylindrical cartridges filled with a sorbent of polyolefin fibers and placed between the inner tube and the outer perforated by the shell, while the side walls of the cassettes are made of perforated metal with a mesh size of 1-3 mm, the cooling system of the filter with a sorbent made in the form of cooling pipes placed between the walls of the cassettes, an adsorber for the post-treatment of hydrocarbons C _1-4 , consisting of two columns, filled with a sorbent, containing a condensate collector, a branch pipe of the C _1-4 fraction withdrawal, a compressed gas supply system for regeneration. 2. Installation according to claim 1, characterized in that the rotating filter cassettes are inserted one into the other between the cooling pipes sealed to the upper cooling water distributor and the hollow cooling water drain shaft, the total number of cassettes being at least 5, and the thickness of each fiber layer the adsorbent of polyolefin fibers with a diameter of 30-100 μm, stuffed into cassettes with a density of 155 ± 5 kg / m ³ is 15-20 mm

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