RU2372379C1 - Cleaning method of hydrogen sulfide- and mercaptan bearing oil - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention relates to methods of oil cleaning against volatile sulfur-containing compounds. Invention relates to cleaning method of hydrogen sulfide- and mercaptan bearing oil, with receiving of separator oil, including physical cleaning of oil by means of double concentration of removed components in gaseous phase of distillate by rectification and removal after rectification from bottom of towers of liquid phase, directed into separator oil, chemical cleaning of distillate by means of extraction of hydrogen sulfide and mercaptans from partially condensed secondary concentrate by matched extraction processes, desorption and absorption, implemented in apparatus of column at presence of stripping gas and extracted from oil water, where it is also fed reagent, allowing bactericidal activity to sulphate-restoring bacteria and corrosion-inhibiting action, extracted cleaned phase of secondary concentrate is partially directed into separator oil.

EFFECT: method provides for implementation of nonwaste cleaning technology of oil against hydrogen sulfide and light mercaptan, reduction of reagent consumption, excluding of danger of ingress of reaction products into separator oil and marketable tanks of oil.

5 cl, 3 tbl, 1 dwg

Description

The invention relates to methods for refining oil from volatile sulfur-containing compounds and can be used in the oil industry.

A known method of purification of oil and gas condensate from low molecular weight mercaptans (methyl and ethyl mercaptans), which consists in processing stabilized raw materials with atmospheric oxygen in an aqueous alkali solution in the presence of a continuously introduced catalyst complex with subsequent separation of the raw material from the aqueous alkali solution (chemical cleaning) [1].

One of the disadvantages of the method [1] is the need for the neutralization of sulfide-alkaline effluents.

A known method of preparing hydrogen sulfide- and mercaptan-containing oil, including concentrating the main part of hydrogen sulfide by desorption and removing the concentrate in the gas phase by blowing it with hydrocarbon gas (physical refining of oil) and subsequent neutralization of the residual amount of hydrogen sulfide and light mercaptans in oil using a reaction mixture (chemical refining of oil) [2].

One of the disadvantages of the method [2] is a significant loss of valuable low-boiling gasoline components of oil with gas.

A common disadvantage of the known methods according to patents [1] and [2], based on the purification of stabilized oil by mixing it with a chemically active reagent, is the ingress of reaction products into marketable oil during sedimentation due to the small difference in the densities of the oil and the reagent, as well as the large size the ratio of their costs.

A known method for the preparation of partially stabilized, dehydrated and desalted oil, including the physical purification of raw materials by concentrating low boiling components (including hydrogen sulfide and light mercaptans) in the liquid phase of the distillate by distillation, subsequent (secondary) concentration of them in the gas phase of the distillate by distillation, the selection of this concentrate and unstable gasoline [3].

The method is as follows.

The feedstock heated in heat exchangers is fed to the first column operating in the following mode: pressure 4-6 kgf / cm ² ; top temperature about 100 ° C; bottom temperature 220-260 ° C. The wide gasoline fraction leaving the top of the column is sent to a condenser-refrigerator, where it is mainly condensed. The condensate is rectified in the second column to obtain the distillate in the form of unstable gasoline (if necessary) and gas, and from the bottom - the residue, which is introduced into the stable oil obtained in the first column. Heat is supplied to the bottom of both columns in the form of a hot stream, that is, by circulating through the furnace part of the remainder of the columns. The second column operates in the following mode: pressure 7-12 kgf / cm ² ; top temperature 66-88 ° С; bottom temperature 110-150 ° С.

The disadvantages of this method:

- a high heating temperature at which sulfur-containing oil compounds decompose with the formation of hydrogen sulfide and mercaptans and other aggressive, highly toxic and unpleasant smelling components;

- receipt of untreated and unstable products;

- loss of oil gasoline potential.

A known method of purification of oil from hydrogen sulfide and mercaptans, which consists in the distillation from a stabilized oil fraction N. to. - 62 ° C, cleaning it from mercaptans by the Merox process using an alkaline catalyst solution and air oxygen as an oxidizing agent [4].

The disadvantage of this method is the large volumes of alkaline solutions and subject to neutralization of sulfur-alkaline effluents.

A known method of removing and neutralizing hydrogen sulfide and mercaptans and installation for its implementation [5]. The method consists in isolating the components to be removed in the form of a concentrate (distillate) by hydrocyclone of oil at 60 ° C (physical purification), separation of the concentrate cooled to 15 ° C at a pressure of at least 1.3 psi, contacting the gas phase and the liquid phase of the concentrate (condensate) , as well as hydrocyclone oil with a selective reagent-neutralizer (selectively treating hydrogen sulfide and mercaptans) (chemical treatment). Hydrocyclone is carried out in a special design apparatus, which has heating and a decreasing taper angle, and the concentrate is contacted with the reagent in a separator equipped with a mass transfer nozzle. A 70% aqueous solution of 1-hydroxy-2- [1,3 oxazetidine] -3-yl-ethane having the general formula C ₄ H ₉ O ₂ N [6] is used as a neutralizing reagent.

The main disadvantage of this method is the need for chemical purification of not only the distillate fraction, but also the residue - hydrocyclone oil. As a result of this, firstly, the reaction products inevitably enter the marketable oil upon sedimentation; secondly, the consumption of an expensive reagent increases, since it is also spent on higher boiling mercaptans, which are advisable to remove during oil refining.

A known method for the comprehensive preparation of oil, which consists in partial (primary) preparation by partial stabilization, partial dehydration, partial desalination and subsequent (secondary) preparation, including physical purification by isolating the distillate in which gas components are concentrated (including hydrogen sulfide and light mercaptans), as well as low-boiling gasoline components in the form of the top product of the stabilization column, chemical purification of the liquid phase of the distillate (unstable gasoline) by extraction with using a chemically active reagent (alkali), the disposal of spent reagent [7]. In technical essence, the closest to the claimed invention is the described method in terms of the secondary preparation of oil (prototype).

The disadvantage of the described method is the reduction in oil potential of valuable low-boiling gasoline components.

The task of the invention is to increase the efficiency of the process of purification of oil from hydrogen sulfide and light mercaptans and the development of non-waste treatment technology.

This technical result is achieved by the described method with the production of marketable oil, including physical purification of oil by double concentration of the removed components in the gas phase of the distillate by distillation and removal after rectification from the bottom of the columns of the liquid phase sent to the marketable oil, chemical purification of the distillate by extraction of hydrogen sulfide and mercaptans from partially condensed secondary concentrate combined processes of extraction, desorption and absorption, carried out in the apparatus of the columns type in the presence of a stripping gas and water extracted from oil, where a reagent with bactericidal activity against sulfate-reducing bacteria and anticorrosive action is also supplied, the separated purified liquid phase of the secondary concentrate is partially sent to marketable oil. Partial condensation of the secondary concentrate is carried out by compression and cooling.

The purified liquid phase of the secondary concentrate is used as an inhibitor of asphalt-resin-paraffin deposits in oil fields and as a demulsifier in oil treatment plants.

As a reagent, compositions with bactericidal activity against sulfate reducing bacteria (biocide) and anticorrosive action [6, 8], mainly a hydrogen sulfide neutralizer, 70% aqueous solution of a substance of the general formula C ₄ H ₉ O ₂ N [6], are used. Disposal of a diluted solution of spent reagent is carried out at oil fields and oil treatment plants as a product with bactericidal activity to sulfate-reducing bacteria and anti-corrosion effect.

As a stripping (stripping) gas, associated petroleum or natural gas predominantly purified from hydrogen sulfide is used.

The application of the proposed method gives the following effect.

Double concentrated components in the gas phase by distillation can significantly (4-10 times) reduce the proportion of low boiling oil components sent for chemical cleaning, reduce the reagent consumption by reducing the proportion of higher boiling mercaptans (starting from isopropyl mercaptan), and improve the conditions for extraction process by increasing the difference in the densities of the concentrate and reagent, as well as reducing the ratio of their volumes and thereby reduce (up to zero) the probability of falling waste spent reagent into marketable oil and associated tanks.

Removing the removed components from the secondary concentrate after partial condensation allows the concentration of hydrogen sulfide mainly in the gas phase, and light mercaptans in the liquid phase.

Combining the processes of extraction, desorption of hydrogen sulfide in the presence of a stripping gas and the absorption of light mercaptans and higher boiling components in a single column-type apparatus makes it possible to intensify the cleaning process as a whole by combining chemical and physical cleaning methods, and also provides flexibility of the regime: it creates the possibility of controlling the flow rate and degree gas purification.

The use of water extracted from oil during the purification process reduces the loss of reagent and low-boiling gasoline components with gas.

Partial condensation of the secondary concentrate by compression and cooling provides the flexibility of the regime when carrying out combined extraction, desorption and absorption processes in a column type apparatus due to the possibility of regulating the gas: liquid ratio, and also creates the possibility of transporting the outgoing liquid flows without the use of pumps.

The use of the purified liquid phase of the concentrate as an inhibitor of asphalt-resin-paraffin deposits in oil fields and as a demulsifier in oil treatment plants allows to reduce the volume of external resources and thereby reduce the unit costs of produced oil; the direction of the remaining part to marketable oil increases the potential of low-boiling gasoline components in it.

The use of a known hydrogen sulfide neutralizing agent, a 70% aqueous solution of a substance of the general formula C ₄ H ₉ O ₂ N 6], which forms a new substance when in contact with mercaptans that has bactericidal activity against sulfate-reducing bacteria and has an anticorrosive effect, makes it possible to exclude from technological Schemes of oil refining stage of regeneration of spent reagent.

The utilization of a diluted solution of spent reagent in oil fields and oil treatment plants by using its bactericidal activity to sulfate-reducing bacteria and its anti-corrosion effect makes this process as easy as possible by using reservoir pressure maintenance and oil preparation systems.

The combination of distinctive features ultimately allows implementing a non-waste technology for cleaning oil from hydrogen sulfide and light mercaptans, reducing reagent consumption, maximally preserving the potential of low-boiling gasoline components in marketable oil, reducing the amount of external resources involved in the extraction and preparation of oil, and almost completely eliminating the risk of ingress of reaction products into commodity oil and commodity oil reservoirs.

Schematic diagram of one of the possible variants of the method is presented in the drawing (pumps and auxiliary units are not shown).

One of the possible options for the method

Partially prepared oil, to be cleaned of hydrogen sulfide and light mercaptans, is fed to the unit through line 1. The main part of the oil is sent through line 2 to the heat exchanger 3, then through line 4 to the furnace 5 and through line 6 is introduced into the middle zone of the distillation column 7 equipped with disk-type contact devices and a battery. The rest of the oil is sent along line 8 (without heating) to the top of column 7 as liquid irrigation. Steam is supplied via line 9 to the bottom of this column as a stripping agent. From the top through line 10, the distillate is taken in the vapor-gas phase, from the bottom along line 11 the liquid phase of the oil is purified from the removed components by the physical method. The oil flow after cooling in the heat exchanger 3 is sent via line 12 to the buffer tank for refined oil 13. From the accumulator of the column 7, all liquid is discharged via line 14, which is sent to the middle zone of the column 15, equipped with disk-type contact devices and intended for secondary distillation of the distillate.

Steam is supplied via line 16 to the bottom of column 15 as a stripping agent. The remainder of this column is withdrawn along line 17 and sent to the bottom of column 7 or to the heat exchanger 18, then along line 19 to the air cooler 20 and along line 21 to the buffer tank 13.

The gas-vapor mixture from the top of the column 15 is sent via line 22 to mixing with a similar column stream 7. This mixture is fed via line 23 to an air-cooled condenser 24, and the resulting vapor-gas mixture is sent via line 25 to a three-phase separator 26. The gas stream is also sent via line 27 to this phase from the buffer tank 13.

The light (hydrocarbon) part of the liquid is fed through line 28 to the top of the column 15, the heavy phase of the liquid (water condensate) is discharged through line 29. The gas phase (concentrate of removed components) is discharged through line 30 and fed to compressor 31, the flow leaving it is directed along line 32 to the air-cooled apparatus 33. The resulting gas-liquid mixture is introduced via line 34 to the separator 35. After separation of the gas phase from the liquid phase, these flows are fed to sections of column type 36, equipped with disk-type contact devices, of different height na, accumulator and a sump with a coalescer at the bottom of the apparatus, respectively along the lines 37 and 38; the gas phase is introduced below. Water condensate 29 is supplied to the top of the apparatus 36 from a three-phase separator 26, a stripping gas purified from hydrogen sulfide (associated petroleum or natural gas purified from hydrogen sulfide) is introduced via line 39 under the lower plate (above the battery).

The reagent is served on several plates above the point of entry of the liquid phase from the separator 35 through line 40 or below the point of entry of the gas phase from the separator 35 through line 41.

From the top of the apparatus, a gas is discharged via line 42, which is a carbon dioxide concentrate (in the embodiment with reagent inlet via line 40), which is sent to the furnace or for amine treatment, or a carbon dioxide and hydrogen sulfide concentrate (in the embodiment with reagent inlet via line 41) . The last of these options is used when the content of hydrogen sulfide is high in oil to reduce reagent consumption by concentrating most of the hydrogen sulfide in the gas, which is sent for amine purification.

A mixture of the liquid phase of the distillate (concentrate) with the spent reagent is withdrawn from the battery of the apparatus 36, which is sent through line 43 to the lower section, the coalescer settler 44, where the mixture is separated by settling into two phases: light (hydrocarbon) and heavy (aqueous solution of spent reagent).

The light phase (the purified liquid phase of the distillate) is removed from the system via line 45 as a product (an inhibitor of asphalt-resin-paraffin deposits) separately or fed through line 46 to the buffer tank 13 for mixing with the bulk of the purified oil.

An aqueous solution of the spent reagent is withdrawn from the bottom of the apparatus via line 47 as a product with bactericidal activity against sulfate-reducing bacteria and anti-corrosion effect. The refined oil from the buffer tank 13 is sent along line 48 to the fleet.

The described method is illustrated by the following numerical examples shown in tables 1-3.

Table 1 shows the characteristics of stabilized and partially purified from carbon dioxide and hydrogen sulfide oil (I option) and stabilized oil (II option).

The main operating parameters of the process are shown in table 2.

Table 3 presents the indicators averaged for two oil compositions characterizing the proposed and known methods under comparable conditions.

This example is given to illustrate the advantages of only two distinctive features of the proposed method related to the physical purification of oil, namely the advantages of a double concentration of the removed components in the gas phase of the distillate relative to a single concentration of them in the distillate.

From the data of table 3 it can be seen that under comparable conditions the proposed method, compared with the known one, although it requires some additional costs (additional column, water vapor consumption is 23% more, heat removal from the top of the column is 14%), however, according to the main indicators, surpasses it (reagent consumption is reduced by 2.23 times, there is no danger of the reaction products getting into marketable oil and corresponding tanks, etc.). This is a consequence of a decrease in the consumption of distillate by an average of 6.3 times due to the twofold concentration of the removed components in it.

Information sources

1. RF patent No. 2087521 with a priority of 08.08. 1994, CL 6 С10G 27/10 “Method for the purification of oil and gas condensate from low molecular weight mercaptans” / Mazgarov A.M., Vildanov AF, Bazhirova NG, Nizamutdinova GB, Sukhov SN

2. RF patent №2218974 with priority of 05/07/2002, cl. 7 B01D 19/00, B01D 53/52, C10G 27/06, C10G 29/20, C10G 29/24 “Method for the preparation of hydrogen sulfide and mercaptan-containing oil”.

3. Kasparyants K.S. Field preparation of oil and gas. M .: Nedra, 1973, p. 152.

4. Mazgarov A.M., Viddanov A.F. and others. - Chemistry and technology of fuels and oils, 1996, No. 6, p.11.

5. RF patent No. 2272066 with priority dated 05/05/2004, cl. C10G 29/00 "Method for the removal and neutralization of hydrogen sulfide and mercaptans and installation for its implementation." / Akhsanov P.P., Andrianov V.M., Ramazanov N.R., Murzagildin Z.G., Dalnova O.A.

6. RF patent No. 2173735 with priority from 08.20.1999, cl. C23F 11/12 "Means for inhibiting the growth of sulfate-reducing bacteria." / Andrianov V.M., Aleev R.S., Gafiatullin P.P., Dalnova Yu.S.

7.Tronov V.P. Oil field preparation. - M .: Nedra, 1977, p.227 (prototype).

8. RF patent No. 2318864 with priority dated November 17, 2006, cl. C10G 29/20, C09K 8/54 “Neutralizer of hydrogen sulfide and mercaptans” / Fakhriev A.M., Fakhriev R.A.

Table 1 Oil characteristic Name and dimension of the parameter Parameter value I version of the composition of oil II variant of oil composition Consumption kg / h 500,000 500,000 Density at 20 ° С, kg / m ³ 839.5 844.6 Molecular weight kg / kmol 205.8 193.1 Total content components (fractions),% wt .: - gases 0.2434 0.3164 - boiling up to 36 ° С 0.6991 0.8240 - boiling up to 85 ° С 2.6544 3.7530 - boiling up to 140 ° С 7.7230 11,0152 - boiling up to 350 ° C 61,4396 68,1552 - boiling up to 350 ° C 38,1355 31,3900 -water 0.4249 0.4548

table 2 Basic operating parameters Name and dimension of parameters (in parentheses is the number of the corresponding stream or device) Parameter value I option II option Suggestion Known way Suggestion Lime. way one 2 3 four 5 Temperature, ° С: - oil for installation (1) 55 55 55 55 - oil from the furnace (6) 195 195 195 195 - top of column I (10) 89 96 109 112 - bottom of column I (11) 191 182 190 183 - top of column II (22) 54 - 56 - - bottom of the II column (17) 124 - 117 - - top of the III column (42) 31 31 33 32 - bottom of the III column (44) 45 42 48 42 - three-phase separator (26) 40 40 40 40 Absolute pressure, kgf / cm ² : - oil for installation (1) 8.0 8.0 8.0 8.0 - oil from the furnace (6) 2.0 2.0 2.0 2.0 - top of column I (10) 1.4 1.4 1.4 1.4 - top of column II (22) 1.4 1.4 1.4 1.4 - top of the III column (42) 5.8 5.8 5.8 5.8 - three-phase separator (26) 1.3 1.3 1.3 1.3 compressor (31) 6.0 6.0 6.0 6.0 Flow rates, kg / h (% wt.): - oil for installation (1), 50,000 500,000 500,000 500,000 (100.0000) (100.0000) (100.0000) (100.0000) including: a) hydrogen sulfide 10 10 161 161 (0,0020) (0,0020) (0,0322) (0,0322) b) light mercaptans 84 84 88 88 (0,0168) (0,0168) (0,0176) (0,0176)

Continuation of table 2 one 2 3 four 5 - water vapor (9 + 16) 700 610 710 530 (0.1400) (0.1220) (0.1400) (0,1060) - stripping gas (39) one hundred one hundred 1000 1000 (0,0200) (0,0200) (0.2000) (0.2000) - fresh reagent (40 or 41) 260 500 300 750 (0.0520) (0,1000) (0,0600) (0.1500) - gas (42) 227 129 1354 1034 (0,0454) (0,0258) (0.2708) (0,2068) - purified liquid distillate phase 3385 17856 3872 32613 (45 or 46) (0.6770) (3.4512) (0.7744) (6,5226) - waste reagent with water 3018 6263 3210 3800 condensate - biocide and inhibitor (0.6036) (0.6526) (0.6420) (0.7600) corrosion (47) - refined (marketable) oil without involving refined distillate (48) 494430 480565 493563 464833 (98.8860) (96.1130) (98.7126) (92.9668) - refined (commercial) oil involving refined distillate (48), 497815 497821 497435 497446 (99.5630) (99.5642) (99.4870) (99.4892) including: a) hydrogen sulfide 0 0 0 0 (0) (0) (0) (0) b) light mercaptans 10.5 10.5 8.0 8.0 (0,0021) (0,0021) (0,0016) (0,0016)

Table 3 Averages Name and dimension of an indicator Indicator value the proposed method known method - the number of columns, pcs. 3 2 - water vapor consumption, kg / h 700 570 - heat removal from the top of the columns, million kcal / h 4,839 4,237 - consumption of distillate, concentrate removed 4028 25261 components, kg / h (% wt.) (0.806) (5,052) - cleaning depth,% wt .: hydrogen sulfide 100.0 100.0 light mercaptans 87.8 87.8 - the content of the removed components in distillate, kg / h (% wt.): hydrogen sulfide 85,2 85.5 (1,960) (0.2705) light mercaptans 71.6 71.9 (1,774) (0.3044) heavy mercaptans 32,0 93.7 (0.849) (0.4022) - reagent consumption, kg / h (% wt.) 280 625 (0.056) (0,125) - danger of ingress of reagent and products reactions to commercial oil and tanks, no Yes well no - flow rate of the liquid phase of the purified 3628 24940 distillate, kg / h (% wt.) (0.726) (4,988) - the possibility of using purified liquid phase distillate in full (without involvement in commercial oil) on Yes no oil fields as an inhibitor, well no

Claims (5)

1. A method of purification of hydrogen sulfide- and mercaptan-containing oil, with the production of marketable oil, including physical purification of oil by double concentration of the removed components in the gas phase of the distillate by distillation and removal after rectification from the bottom of the columns of the liquid phase, sent to the marketable oil, chemical purification of the distillate by extraction of hydrogen sulfide and mercaptans from partially condensed secondary concentrate by combined extraction, desorption and absorption processes carried out in the column apparatus type in the presence of stripping gas and oil extracted from the water, which also serves reagent possessing bactericidal activity toward sulfate-reducing bacteria and anticorrosive effect, the selection phase secondary concentrate purified partially directed in commercial oil. 2. The method according to claim 1, characterized in that the partial condensation of the secondary concentrate is carried out by compression and cooling. 3. The method according to claim 1, characterized in that the purified liquid phase of the secondary concentrate is used as an inhibitor of asphalt-resin-paraffin deposits in oil fields and as a demulsifier in oil treatment plants. 4. The method according to claim 1, characterized in that the known chemical hydrogen sulfide neutralizer is used as a reagent - a 70% aqueous solution of a substance having the general formula C ₄ H ₉ O ₂ N. 5. The method according to claim 1 or 4, characterized in that the utilization of the diluted reagent is carried out in oil fields and oil treatment plants as a product having bactericidal activity to sulfate-reducing bacteria and anti-corrosion effect.

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