RU2456053C2 - Plant to clean oil from hydrogen sulphide and mercaptans - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to oil-and-gas industry and may be used for oil and oil gas cleaning. Proposed plant comprises pipeline of sour petroleum gas. Oil cleaning unit comprises two strippers arranged sequentially along oil transfer provided with extra function of sulphide neutralisation. Said strippers are made up of free cylindrical casing for foam-jet contact between oil and gas, fluid-gas injector with sulfurous oil inlet for said injector and nonsulfurous or low-sulfur oil gas inlet. Downstream of confuser in mixing chamber openings are made to form chamber receiving reagent for neutralisation of sulphides. Purified oil is derived from free casing bottom via hydraulic gate to flow via pipeline into second stripper fluid-gas injector inlet to make working fluid for said injector. Chambers of said reagent are communicated via pipeline and three-way valve with reagent tank. Then, second stripper oil outlet is communicated via pipeline with separation settler inlet wherefrom purified commercial oil is discharged. Besides, proposed plant comprises oil gas cleaner including liquid reagent circulation circuit, fluid-gas injector, liquid reagent separator, rotary pump, refrigerator and, again, fluid-gas injector. Fresh reagent feed injector is arranged between rotary pump and separator. Then, unit forms oil gas circulation circuit including aforesaid injector, purified oil gas manifold with external discharge branch pipes and inlets into strippers. Sulfurous gas manifold has inlets from strippers, separator inlets via injector, sulfurous gas injector, refrigerator and, again, fluid-gas injector of oil gas cleaning unit.

EFFECT: higher efficiency of processing.

1 dwg

Description

The invention relates to the oil and gas industry in relation to the conditions of an oil field.

The following methods are known for refining oil from sulfur compounds:

- multistage separation;

- chemical: direct oxidation of hydrogen sulfide in oil by atmospheric oxygen in the presence of alkaline solutions with a catalyst;

- neutralization of sulfur compounds by mixing oil with liquid reagents;

- rectification;

- oil stripping with sulfurless or low-sulfur hydrocarbon gas.

An analysis of the methods and schemes of installations for them, given in the articles listed below, showed that in the conditions of fishing it is most expedient to independently use multi-stage separation, blowing oil with hydrocarbon gas, under certain requirements, neutralize sulfur compounds with liquid reagents, and a combination of several methods at the same time.

[one]. E.I. Andreeva, S.P. Lesukhina “Development of a process for extracting hydrogen sulfide and stabilizing the oil of the Tengiz field by blowing it with oil gas”. “Problems of development of oil fields with anomalous properties”, Kuibyshev 1983, Giprovostokneft, S. 99-111.

[2]. R.Z. Sakhabutdinova, A.N. Shatalov, R.M. Garifullina and others. "Technology for cleaning oil from hydrogen sulfide." “Oil industry”, No. 7 2008. P.82-85.

[3]. Patent RU No. 2349365 "Installation for the purification of oil from hydrogen sulfide and mercaptans", 09/07/2007. Publ. 03/20/2009.

[four]. Patent RU No. 2305123 "Method for the preparation of hydrogen sulfide-containing oil", 03/20/2006. Publ. 08/27/2007.

[5]. Advertising brochure “Installation of deep oil degassing”, LLC “NT Oil and Gas” 2007. http://www.ntng.ru/index1 5.html.

Schematic diagrams of a complex of installations for the extraction of hydrogen sulfide and oil stabilization, proposed in the article by E.I. Andreeva, S.P. Lesukhina “Development of a process for extracting hydrogen sulfide and stabilizing the oil of the Tengiz field by blowing with oil gas”, “Problems of developing oil fields with anomalous properties”, Kuibyshev, 1983, Giprovostokneft, S.99-111, including separators 1- 2nd С-1, 2nd С-2 and 3rd С-3 separation stages, sedimentation tank, separator of the 4th stage С-4, pump, furnace, two electric dehydrators, separator of the 5th stage С-5, compressors and two columns of blowing K-1 and K-2 with different placement in the schemes. The gas after C-1 is purified from hydrogen sulfide in a high-pressure unit (LDS), the gas after C-2 is purified in a low-pressure unit (LDS). Sulfur gases after C-4, stripping columns, C-5, after compression, are sent to desulfurization at the SND installation.

Analyzing the three schemes of the complex of plants in relation to the conditions of a particular field, the authors justify and recommend further development of the third scheme, when, in the direction of the oil flow, one blowing column, the first, is located after the sump, and the second - after the 4th separation stage in front of the pump, furnace, electric dehydrators and C-5, while gas for blowing into the first column is supplied from C-2 without removing hydrogen sulfide, into the second from C-3, C-4 and C-5 from the SND desulfurization unit.

The proposed scheme has, in our opinion, the following disadvantages: the authors, justifying the scheme with corrosion protection equipment following the second blow-off column, simultaneously send sulfur dioxide gas from С-4, the second blow-off column and С-5 to the K-1 gas compressor for compression ; a gas compressor must first be protected against corrosion. The first column will be ineffective, since the stripping gas enters the column not purified from hydrogen sulfide. Assuming the reliability of calculations, the proposed scheme of the complex of installations can be used in the design of new fields with high reservoir oil pressure, since the use of the scheme for the existing field will require serious reconstruction.

The scheme is quite complicated. Installations for cleaning high and low pressure hydrogen sulfide are not disclosed; to increase the gas pressure, two compressor units are used that require qualified service.

Typically, the removal of hydrogen sulfide and mercaptans in the stripping column is carried out after the preparation of the oil. In this case, stripping sulfurless hydrocarbon gas is used from the “side” from the desulfurization unit.

Closest to the proposed installation is the installation of oil purification from hydrogen sulfide and mercaptans: Patent RU No. 2349365 "Installation of oil purification from hydrogen sulfide and mercaptans", 09/07/2007, publ. 03/20/2009, including supply pipelines of sulphurous oil and low-sulphurous or sulphurous hydrocarbon gas, a purification unit in the blow-off column, a unit for neutralizing residual sulphurous compounds in oil, separators, tanks, pumps, control devices, dosing and automation. The installation of a refrigerator, an additional oil and gas separator, gas separator, and two parallel tanks for holding oil for (two or more hours) can improve the quality of marketable oil during temporary shutdown of the blow-off column.

The disadvantages of this installation are:

- single use for blowing sulfurless or low-sulfur oil or natural gas obtained from the "side"; those. prepared outside the installation.

- direction outside the installation ("to the side") of low-pressure sulfur dioxide from the top of the gas separator after the stripping column and from the top of the oil and gas separator for disposal or for flaring with possible atmospheric pollution;

- the need after treatment of oil with stripping gas and aqueous solutions of the reagent, its sedimentation for at least 2 hours in a static state (without filling and emptying) in two or three tanks installed in parallel to continue the work of the reagent, removing water and reaction products.

Industrial tests at the facilities of OAO Tatneft R.Z. Sakhabutdinova, A.N. Shatalov, P.M. Garifullina et al., “Technology for the purification of oil from hydrogen sulfide”, “Oil industry”, No. 7 2008. P.82-85 show that it is not always possible to exclude the negative effect of reaction products on oil quality.

Thus, to ensure the operation of the installation in question, a block for preparing sulfurless or low-sulfur hydrocarbon gas for blowing, a block for utilizing sulfur dioxide, or a flare unit is required “on the side”.

The objective of the invention is the creation of an autonomous installation for working in the field for purification from hydrogen sulfide and mercaptans of prepared oil and at the same time oil gas using equipment that does not require qualified service to produce not only marketable oil and refined compressed oil gas, but also as marketable products the products of the interaction of a water-soluble reagent with sulfur compounds that have an anticorrosive effect in the sulfur-containing th environment and the properties of a bactericide that inhibits the growth of sulfate-reducing bacteria.

The proposed installation for the purification of oil from hydrogen sulfide and mercaptans includes pipelines for the preparation of prepared sulphurous oil and sulphurous gas, an oil refining unit, separators, refrigerators, tanks, pumps, control, batching and automation devices, while the oil refining unit contains two in series connected downstream the movement of oil in a gas stripping column with additional functions of neutralizing sulfur compounds with liquid reagents, consisting of a free cylindrical body for foam-jet for oil and gas interaction, the axis of which is installed at the bottom of the liquid-gas injector of the LHG with the input of sulfur dioxide, which serves as the working fluid for the LHG, and with the input of sulfur-free or low-sulfur oil gas, holes are made after the confuser in the mixing chamber of the LHI to form a reagent intake chamber for neutralizing sulfur compounds; at a distance from the bottom of the free casing, a purified oil is discharged through the hydraulic lock, which is piped into the LHI of the second blow-off column, which also serves as the working fluid for the LHI, the reagent supply chambers in the LHI of the blow-off columns are connected by a pipeline through a three-way valve to the reagent tank; further, the oil outlet from the second stripping column is connected by a pipeline to the input of the separator-settler, from which the discharge of refined salable oil is performed;

the installation further comprises an oil gas purification unit, including a liquid reagent circulation circuit, which includes a liquid-propellant liquid fuel, a combined liquid reagent separator, a centrifugal pump, a refrigerator and again a liquid-liquid reagent, an injector is installed between the centrifugal pump and the separator to supply fresh reagent through it; Further, an additional unit forms a circulating circuit of oil gas, which includes a LIG separator, a purified oil gas collector with a tap outside the unit, with taps into the stripping columns, then a sulfur dioxide collector with inputs from the stripping columns, with inputs from the separators through injectors, with an input through sulphurous oil gas injector, refrigerator and again the LHG unit of oil gas purification.

An analysis of the identified technical solutions in the considered area showed that there is no installation similar to the declared one, which allows us to conclude that its criteria of “novelty” and “inventive step” are met.

The drawing shows a schematic diagram of an oil refinery.

Installation includes:

- an oil refining unit, consisting of two stripping columns 1 and 2 connected in series along the direction of the oil flow, a separator-settler 3, a gas separator 4, a container for reagent 5, a three-way valve 6 and a valve 7;

- an oil gas purification unit, consisting of a liquid reagent circulation circuit, which includes a liquid-gas injector 8, a separator 9 for liquid reagent combined with it, an ejector 23 for introducing a liquid reagent from the tank 10 through a pipe 11, a centrifugal pump 12, an air cooler cooling 13; the separator 9 has an output 26 of the balanced average amount of the reagent, an output of 28 condensed hydrocarbons;

- the oil gas purification unit also contains a gas gas circulation circuit, which includes a ZhGI 8 with a separator 9, a purified gas collector 14 with taps 15 and 16 into the blow-off columns 1 and 2 and an outlet 17 “to the side”, a sulfur dioxide collector 18 with inputs into it 19, 20 from the stripping columns 1, 2, with inlets 21, 22 from separators 3, 4 through ejectors 23, inlet 24 through an ejector 23 of oil gas and output 25 through an air-cooled refrigerator 13 in the ZhGI 8 of the oil gas purification unit.

Stripping columns 1 and 2 consist of a free cylindrical body with a conical bottom, along the axis of which there is a LHG with 1.2 sulfurous oil introduced into the chamber of the working fluid entering the LHG through pipeline 27 and with 1.3 sulphurous or low-sulfur oil gas introduced into the ejected gas chamber 1.5. ZhGI columns blowing 1 and 2 are equipped with a nozzle of annular cross-section (not shown). After confuser 1.4, at the beginning of mixing chamber 1.1, a zone of recirculation of the gas-liquid mixture with a reduced pressure is formed. The recirculation zone of mixing chamber 1.1 with holes is covered by chamber 1.5 with input 1.6 for reagent entry. The cylindrical body of the stripping column in the upper part is equipped with a drop eliminator 1.7 and a nozzle for sulphurous gas 1.8, and in the lower part - with a water trap 1.9 with a lead of 1.10 for refined oil. At the top of the water seal there are openings 1.11 to remove gas released from the oil.

Installation of oil refining works as follows. Prepared (degassed, dehydrated and desalted) sulphurous oil under pressure through a pipe 27 enters the blow-off column 1 - into the inlet 1.2 of the chamber of the working fluid of the ZhGI. At the same time, through the outlet 15 from the collector 14, the purified petroleum gas enters the inlet 1.3 of the chamber of the ejected gas LHI. Expiring from an annular nozzle (not shown), the oil forms a finely divided oil ring fan stream, which, interacting with the ejected oil gas at the beginning of mixing chamber 1.1, will create a gas-liquid mixture when the gas is completely dispersed in the oil. Having passed the diffuser part of the mixing chamber, the gas-liquid jet flows into a free cylindrical body and forms a circulating foam layer of oil and gas. Throughout the close interaction of oil and gas, the process of desorption of sulfur compounds from oil to gas proceeds. Sulphurous petroleum gas, having passed the droplet eliminator 1.7, continuously leaves through the nozzle 1.8 to the input 19 and to the sulfur dioxide gas collector 18. There is also a continuous removal of refined oil through airlock 1.9 and conclusion 1.10. The output position 1.10 provides a certain oil height at the bottom of the cylindrical body to provide a foam contact mode. Standing out in the water seal 1.9. gas is removed through openings 1.11. The column of oil stripping 1 can be taken as the first stage of purification. Under certain conditions, it is also possible to supply a reagent to the stripping column as an addition to lowering the concentration of sulfur compounds in oil.

Oil from the stripping column 1 enters the gas separator 4, from where the separated sulfur dioxide gas enters the sulfur dioxide collector 18 through the inlet 22 and the ejector 23. The refined oil enters the stripping column 2 - the second stage of purification - into the inlet 1.2 of the working fluid chamber. In the chamber 1.4 of the ejected gas, purified gas simultaneously enters through the outlet 15 from the purified gas manifold 14. The process described for the stripping column 1 is repeated in the stripping column 2. into which the purified gas enters through the outlet 16. The refined oil from the stripping column 2 enters the separator-settler 3, from where the oil leaves the unit as commodity through a water trap. The released sulfur dioxide through the inlet 21 is discharged into the ejector 23, and then into the sulfur dioxide oil collector 18. In all cases of combining flows of different pressure levels, a simplified design of the ejector 23 is used to reduce hydraulic losses.

In cases of low concentrations of sulfur compounds, one stripping column may be used for oil refining. Oil supply to it is shown by a dashed line. At increased concentrations of sulfur compounds in oil, the reagent can be supplied either to the first or second column, or both at once. A double effect on oil is ensured - the removal of sulfur compounds by blowing with sulfur-free hydrocarbon gas and binding with a reagent, which increases the reliability of the process of more complete removal of sulfur compounds from oil.

The supply of reagent from the tank 5 is regulated by the position of the valve 6. In position 6 a - supply to both columns, 6 to - to the second column, 6 s - to the first column. The valve 7 serves to completely shut off the supply of reagent to the columns of the blower.

As a neutralizer of sulfur compounds in oil and gas, water-soluble reagents can be recommended (RU 22416884, RU 2242499, Delisalf; Ismagilova ZF, etc. “Development of the production technology of new absorbers of hydrogen sulfide and mercaptans for the oil and gas industry”, YII Congress of Russian Oil and Gas Industrialists, Materials of the International Scientific and Practical Conference, "Oil and Gas Refining and Petrochemicals - 2007", May 22-25, Ufa, s.266-267), which passed positive tests and manufactured by Tekoil CJSC (Ufa) according to TU 2458-009033818307- 2005. The resulting non-toxic products of the interaction of the reagent with sulfur compounds remaining in the oil do not affect its further processing. Selective chemisorption interaction with hydrogen sulfide and mercaptans occurs almost instantly in a wide range of hydrogen sulfide concentrations, pressures and flow rates. The combined effect of desorption and chemisorption processes on sulphurous oil will make it possible to increase the reliability and efficiency of its purification from hydrogen sulfide and mercaptans, to some extent, to achieve independence of the overall process from the concentration of sulfur compounds. Expected decrease in costs of stripping gas and reagent. The amount of supplied reagent is determined by the content of hydrogen sulfide and mercaptans in the oil. So for the removal of 1 g of hydrogen sulfide, the consumption of the Delisalf reagent does not exceed 4 g.

Collected in the manifold 18, supplied to the installation through the pipeline 24, sulphurous petroleum gas, sulphurous gas from stripping columns 1, 2, from separators 3, 4 and 9 enters the oil gas purification unit, in which water-soluble reagents can be recommended to remove sulfur compounds ( RU 2241684, RU 2359739, Delisalf). The reagent moves in the circulation circuit of the oil gas purification unit and is the working fluid for the liquid-propellant liquid 8. The reagent is dispersed in a gaseous medium and interacts with sulfur compounds. In a circulating aqueous solution of the reactant and reaction products, an average concentration of reaction products is maintained. The balance amount is continuously removed from the separator 9 through terminal 26 and the same amount of fresh reagent is introduced from the tank 10 through the pipe 11 and the ejector 23. It is recommended to use one reagent both for oil and gas purification at the installation. Thus, installation is simplified through the use of a single tank. The reagent, thoroughly mixed in the ejector 23, the centrifugal pump 12, and the pipeline, again enters the ZhGI 8 for spraying, ejecting sulfur dioxide, and neutralizing sulfur compounds. The reaction products with a certain amount of reagent are, as already noted above, a commercial product, can be used not only in the oil and gas industry, but also in metallurgy and industrial ecology. A layer of hydrocarbon liquid may accumulate in the separator 9, which is occasionally removed through the terminal 28 into the separator-settler 3.

Water-soluble reagents (RU 2241684 and Delisalf according to TU 2458-009033818307-2005) can be effectively used for purification of sulfur compounds from both oil and gas. In this case, a single reagent can be used in the installation.

Thus, the proposed invention allows you to: - simultaneously solve two problems: purification of hydrogen sulfide and mercaptans of oil and oil gas by using the modernized design of a simple liquid-gas injector that does not require qualified maintenance, to ensure its multifunctionality as a stripper, as a reactor and as a compressor, namely, the effective contacting of sulfur dioxide and desulfurized gas in the foam-jet mode for the desorption of hydrogen sulfide and mercaptans by blowing and chemical skim their binding reagent with simultaneous compression of gas without using a conventional complex compressors; The functions of the reactor and compressor are also performed by the liquid-gas injector in the sulfur dioxide gas purification unit in the jet-drop mode of gas and reagent contacting.

The installation is easy to maintain, requires only electricity and a reagent solution for operation, and is virtually waste-free, since in addition to refined oil and oil gas, the spent (used) reagent solution is also a commercial product. At the same time, the recommended reagents can be used both for refining oil and gas.

Claims (1)

A unit for purifying oil from hydrogen sulfide and mercaptans, including supply pipelines of sulfur oil and gas, a unit for purifying oil in a gas stripping column, a unit for neutralizing residual sulfur compounds in oil, separators, a refrigerator, tanks, pumps, monitoring, dosing and automation devices, characterized in that a sulphurous petroleum gas pipeline is supplied to the installation, the oil refining unit contains two blowing columns connected in series along the direction of the oil flow with the additional function of neutralizing sulphurous unions, consisting of a free cylindrical body for foam-jet contacting of oil and gas, along the axis of which a liquid-gas injector is installed at the bottom with an input of sulphurous oil serving as a working fluid for a liquid-gas injector, and an input of sour-free or low-sulfur oil gas, after the confuser holes are formed in the mixing chamber of the liquid-gas injector with the formation of a reagent intake chamber for neutralizing sulfur compounds, at a distance from the bottom of the free casing through a water trap p, the refined oil was discharged, which is piped to the inlet of the liquid-gas injector of the second stripping column, which also serves as the working fluid for the liquid-gas injector, and the reagent supply chambers into the liquid-gas injectors of the stripping columns are connected by a pipeline through a three-way valve to the reagent tank, Further, the oil outlet from the second stripping column is connected by a pipeline to the input of the separator-settler, from which the purified crude oil is removed, the installation further comprises a purification unit and oil gas, including a liquid reagent circulation circuit, which includes a liquid-gas injector, a combined liquid reagent separator, a centrifugal pump, a refrigerator and again a liquid-gas injector, an injector is installed between the centrifugal pump and the separator to supply fresh reagent through it , then the block forms a circulating circuit of oil gas, which includes a separator of a liquid-gas injector, a manifold of purified oil gas with a tap outside the installation, with taps into the stripping columns, ollektor sulfur dioxide with the inputs from the stripping column, with the inputs from the separator through the injectors with an injector inlet sour gas, the refrigerator again and the liquid-gas injector gas purification unit.

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