RU2120464C1 - Method and installation for deodorizing purification of crude oil and gas condensate from hydrogen sulfide and low-molecular mercaptans - Google Patents

Abstract

FIELD: petroleum processing. SUBSTANCE: hydrogen sulfide and low-molecular mercaptans contained in crude oil and gas condensate are oxidized by air oxygen into elementary sulfur and disulfides in presence of water-alkali solution of phthalocyanine catalyst at 25-65 C and 0.5-3.0 MPa pressure for 5 to 180 min. To raw material stream added are: 25-45% aqueous alkali solution containing 0.1-0.8 mole of sodium hydroxide per 1 mole of is hydrogen sulfide and mercaptan sulfur and 0.15- 0.25% solution of phthalocyanine catalyst containing catalyst in amount 0.01-0.1 g/mole. Cobalt compounds of disulfo-, tetrasulfo-, and dichlorodihydrpxydisulfate- octacarboxytetraphenyl and polyphthalocyanine are used as catalyst. Catalyst solution is prepared by dissolving phthalocyanine in preliminarily deoxidized water or 0.5-1.5% aqueous alkali solution by flushing water or alkali solution with inert gas. A portion of reaction mixture containing purified material, exhausted air and water-alkali solution of catalyst is combined with starting material at ratio (0.05- 200):1 at pressure 0.2-0.5 MPa. Installation contains raw material tank and pump, tanks for preparing and storing alkali and catalyst solutions, corresponding pumps, air-supply apparatus, apparatus to mix air with raw material, preheater, hydrogen sulfide and mercaptan-oxidation reactor, settler for collecting reaction mixture, and tank-separator to separate this mixture. Tank for preparing catalyst solution is provided with bubbler to blow through solution with inert gas. Discharge lines of alkali and catalyst solution-supply pumps are connected with suction line of raw material-supply pump, and tank-settler is connected over pipeline and flow regulator to raw material tank. Air-raw material mixing apparatus is installed after raw material-supply pump, and preheater between this apparatus and reactor. To mix air with raw material, pressure injector is used or apparatus constructed in the form of tore with holes oriented against raw material stream at angle 20-30 deg. EFFECT: enabled purification of all types of crude oils and gas condensates. 10 cl, 3 dwg, 3 tbl

Description

 The invention relates to methods and installations for the oxidative purification of oil and gas condensate from hydrogen sulfide and mercaptans and can be used in the gas and oil industry for deodorization of oil and gas condensate.

Up to 0.05% (500 ppm) of hydrogen sulfide and up to 0.1% (1000 ppm) of low molecular weight mercaptans can be present in oils and gas condensates. The presence of hydrogen sulfide and low molecular weight mercaptans creates a foul smell of oil. In case of violation of the tightness of the storage, hydrogen sulfide and low molecular weight (low boiling) mercaptans can enter the atmosphere. The maximum permissible concentration in the residential area is 8 • 10 ^-3 mg / m ³ for hydrogen sulfide, 1 • 10 ^-4 mg / m ^{3 for} methyl mercaptan and 3 • 10 ^-5 mg / m ^{3 for} ethyl mercaptan.

In the oil industry, the removal of hydrogen sulfide from oil is carried out at the stages of separation and stabilization, where hydrogen sulfide at an elevated temperature evaporates along with associated C ₁ -C ₄ gases. Associated gas is purified from hydrogen sulfide at gas processing plants (GPPs) or flared, which leads to environmental pollution with sulfur dioxide. With small volumes of associated gas, the creation of a gas processing plant and gas transportation are uneconomical and require large investments. The possibility of gas leakage and air pollution by hydrogen sulfide is not ruled out.

 To remove hydrogen sulfide, low molecular weight mercaptans and acidic compounds from petroleum products, alkalization is performed. When washing with an aqueous alkali solution, naphthenic acids, phenols, hydrogen sulfide and low molecular weight mercaptans form water-soluble salts and leave with wash water (Oil and Gas Chemistry. Edited by Doctor of Technical Sciences Proskuryakova V.A., L., Chemistry, 1981, p. 318-320). For oil refining this method is not applied.

A technology has been proposed for the purification of oil from low molecular weight mercaptans, the essence of which is the distillation of N.K. - 62 ^o C, cleaning it from mercaptans at the Merox installation and pumping it back into oil. The implementation of this technology requires large capital and operating costs.

 In terms of technical nature and the achieved result, the closest to the proposed invention is the current process (method and installation) for the purification of oils and gas condensates from low molecular weight mercaptans at the Tengiz oil field of the Republic of Kazakhstan. (Mazgarov A.M., Vildanov A.F., Sukhov S.N. et al. A new process for the purification of oils and gas condensates from low molecular weight mercaptans. - KhTM, 1996, N 6, p. 11). The basis of this process is the invention "A method for the purification of oil and gas condensate from low molecular weight mercaptans" (RF Patent N 2087521 C1, 08.20.97).

According to this method, the purification of raw materials from low molecular weight mercaptans is carried out by treating with atmospheric oxygen in an aqueous alkali solution in the presence of a phthalocyanine catalyst, followed by separation of the purified raw material from an aqueous alkali solution. As a catalyst, cobalt dichlorodioxidisulfophthalocyanine is used, which is continuously introduced into the feed in an amount of 0.5 • 10 ^-5 - 2.5 • 10 ^-5 % wt. in the form of a catalyst complex (CPC) prepared by dissolving the catalyst in a 1% aqueous alkali solution, followed by adjusting the concentration of the aqueous alkali solution to 20% by weight, and the process is carried out at 40-60 ^o C and a pressure of 1.0 - 1.4 MPa

From the description of the application for this invention it follows that the process is conducted with recirculation of the aqueous-alkaline solution of the catalyst, i.e. in the feedstock, in addition to the above CPC, the spent CPC is introduced, separated from the purified raw material during sedimentation. With an oil deodorization unit capacity of 2 m ³ / h, the amount of circulating aqueous-alkaline solution of the catalyst in the system is 800 kg, air consumption is 1.2 nm ³ / h, i.e. 0.6 nm ³ / t based on raw materials.

 A schematic flow diagram of a known installation is shown in FIG. 1. The installation contains an oil heater 1, a feed pump 2, a preliminary alkalization apparatus 3, a mixer 4, a compressor 5, a reactor 6, a sump 7, a coalescer 8, tanks for preparing and storing an alkali solution 9 and CPC 10, a pump 11 for circulation and supply an aqueous solution of alkali from tank 9 to tank 10, a pump 12 for supplying the CPC to the mixer 4, a pump 13 for supplying the spent CPC to the apparatus 3 and the mixer 4.

The feedstock from the feed tank (not shown in Fig. 1) enters the heater 1, where it is heated to 55 ± 5 ^o C, then the feed pump 2 is fed under a pressure of 1.2 MPa to the preliminary alkalization apparatus 3, where selective extraction 1 % aqueous solution of alkali (NaOH) from raw materials of hydrogen sulfide and naphthenic acids in the form of sulfides and naphthenates, the aqueous solution of which is periodically removed from the bottom of the apparatus in the form of sulfide-alkaline effluents (SSS). When neutralizing hydrogen sulfide and naphthenic acids, alkali is consumed and reaction water is released. The alkali concentration in the apparatus 3 is maintained by supplying the spent CPC from the sump 7. The SCW from the bottom of the apparatus 3 are sent to a separate sulfide sulfur neutralization unit. The raw material purified from hydrogen sulfide and naphthenic acids enters the reactor 6, pre-mixed in the mixer 4 with fresh and spent CPC and the air supplied by the compressor 5. The mixer 4 is a cross-shaped pipe, mixing (ineffective) occurs due to the perpendicular supply of the CPC and air to the stream raw materials. The amount of air supplied is calculated based on the equations of the oxidation reaction of mercaptans and taken in 1.5-fold excess, at a pressure of about 1.2 MPa, the air is completely dissolved in the feed.

 The reactor 6 is a column with sieve failure plates. Intensive mixing of raw materials and CPC is carried out in the inter-tray space of the column due to the high rate of fluid outflow through the plate openings.

 On top of the reactor 6, the reaction mixture enters the sump 7, where the feed settles from the spent CPC. From the bottom of the sump 7, the spent CPC pump 13 is fed into the pre-alkalization apparatus 3 or into the reactor 6. The deodorized raw materials on top of the sump 7 are sent to the coalescer 8 to separate the entrained (emulsified) CPC, then to the commodity tanks (not shown in Fig. 1). Exhaust air from deodorized raw materials is isolated in these tanks and sent for disposal. An aqueous alkali solution is prepared in a container 9, the solution is mixed by pump 11 by circulation. A fresh CPC solution is prepared in tank 10 by dissolving the phthalocyanine catalyst powder in a 1% aqueous alkali solution, followed by adjusting the alkali concentration to 10-20%. Fresh CPC is supplied to mixer 4 by pump 12. The aqueous-alkaline solution of the catalyst in reactor 6 is diluted in the process with reaction water. The concentration of reagents in the solution is maintained by continuously feeding concentrated (fresh) CPC from the tank 10 and feeding part of the spent CPC from the sump 7 to the preliminary alkalization apparatus 3.

When the initial oil contains 1.63 ppm hydrogen sulfide and 800 ppm mercaptans in the refined oil, there is no hydrogen sulfide, the content of mercaptans C ₁ -C ₂ decreases by 98-99%, C ₃ by ≈70% and C ₄ by ≈20%. Alkali consumption (NaOH) is 80 g per 1 ton of raw material or 13.5 g (0.3 mol) per 1 mol of oxidized mercaptans. Heavy mercaptans (C ₅ or more) do not oxidize.

 The known method and installation for its implementation have the following disadvantages.

 1. Not suitable for deodorization of oil and gas condensate, forming stable emulsions with alkaline solutions, since in this case it becomes impossible to separate (settle) spent CPC from raw materials and return it to the process, as well as washing hydrogen sulfide with an aqueous alkali solution.

 2. The process is multi-stage, for its implementation requires large capital and operating costs.

3. Requires a large consumption of alkali. For example, to neutralize 340 ppm H ₂ S, 800 g of NaOH is required only at the preliminary alkalization stage.

4. A large volume of SCHS to be neutralized is formed, since hydrogen sulfide from the installation is discharged in the form of a solution of sodium sulfide (Na ₂ S).

 5. A highly effective but expensive catalyst is used - cobalt dichlorodioxidisulfophthalocyanine. A solution of the catalyst in a 20% aqueous alkali solution during storage quickly loses activity, and is oxidized by atmospheric oxygen dissolved in water.

The proposed invention solves the following tasks:
expanding the scope of the method and installation for the purification of raw materials that form stable emulsions with alkaline solutions;
simplification of technology, reduction of the list of equipment, process steps and capital costs;
reduction in alkali consumption per 1 mol of hydrogen sulfide and (or) mercaptan sulfur;
reduction of waste - water-salt effluents;
the use of cheap phthalocyanine catalysts;
increase the stability and shelf life of catalyst solutions.

To obtain the technical results in the proposed method for the deodorizing treatment of oil and gas condensate from hydrogen sulfide and low molecular weight mercaptans into the feed stream without preliminary purification from hydrogen sulfide, 25-45% alkali aqueous solution and 0.15-0.25% are continuously and simultaneously introduced into the stream while stirring. -th solution of a phthalocyanine catalyst in purified water or a 0.5 - 1.5% aqueous solution of alkali, then a calculated amount of air is introduced into this stream at a pressure of 0.5 - 3.0 MPa, the mixture is heated to 25- 65 ^o C and give exposure for 5-180 minutes After that, part of the reaction mixture containing purified raw materials, dissolved exhaust air and an emulsified aqueous-alkaline solution of the catalyst is directed to mixing with the feedstock, which is carried out at a pressure of 0.2 - 0.5 MPa. The remaining part of the reaction mixture is subjected to separation with the release of purified raw materials, exhaust air and water-salt solution. A 25-45% aqueous alkali solution is introduced at the rate of 0.1-0.8 mol of sodium hydroxide per 1 mol of hydrogen sulfide and mercaptan sulfur. 0.15 - 0.25% solution of a phthalocyanine catalyst is introduced at the rate of 0.01 - 0.1 g of catalyst per 1 mol of hydrogen sulfide and mercaptan sulfur. As a catalyst, cobalt disulfophthalocyanine (DSPA), cobalt tetrasulfophthalocyanine (TSPA), cobalt dichlorodioxidisulfophthalocyanine cobalt (DHDODSFK), cobalt octocarboxythenylphthalocyanine (OKPTFC) and polyphthalocyanine (cobalt) are used as a catalyst. Part of the reaction mixture is sent for mixing with the feedstock in the ratio (0.05 - 2): 1, i.e. 5-200% of the reaction mixture is added to the feedstock.

 Distinctive features of the proposed method.

 1. One-stage purification of raw materials from hydrogen sulfide and low molecular weight mercaptans, that is, their simultaneous oxidation without prior washing of hydrogen sulfide.

 In the known method, hydrogen sulfide is preliminarily washed from the raw material with a 1% aqueous alkali solution, then the low molecular weight mercaptans present in the raw material are oxidized, and SSS from the hydrogen sulfide washing stage containing sodium sulfides are oxidized in a separate installation, i.e. The known method has three stages of purification.

 2. The proposed and known methods are distinguished by the consumption of NaOH per mole of hydrogen sulfide and mercaptans and the composition of SHS, since in the oxidation processes taking place in the known and proposed methods, different reactions are used at different pH environments.

Расход щелочи составляет 2 моль на моль H₂S. На стадии демеркаптанизации расход щелочи составляет 0,3 моль на моль меркаптанов. Окисление меркаптанов происходит по реакциям

Для образования RSNa по реакции 2 требуется pH среды более 11. ДХДОДСФК катализирует реакцию 3 значительно активнее, чем другие фталоцианины, например в 7 раз активнее, чем ДСФК (Горохова С.А. Жидкофазная окислительная демеркаптанизация светлых нефтяных фракций в присутствии фталоцианинов кобальта. - Дис. к.т.н. Казань, 1989, с. 133). В отсутствии катализатора реакция 3 практически не идет.In the known method, hydrogen sulfide is washed from the raw material with an alkali solution, converting it to a water-soluble sulfide:

The alkali consumption is 2 mol per mole of H ₂ S. At the stage of demercaptanization, the alkali consumption is 0.3 mol per mole of mercaptans. Oxidation of mercaptans by reactions

For the formation of RSNa by reaction 2, a pH of more than 11 is required. DCHDODSFK catalyzes reaction 3 much more actively than other phthalocyanines, for example 7 times more active than DSFK (Gorokhova S.A. Liquid-phase oxidative demercaptanization of light oil fractions in the presence of cobalt phthalocyanines. - Dis Ph.D. Kazan, 1989, p. 133). In the absence of a catalyst, reaction 3 practically does not proceed.

Расход кислорода и воздуха рассчитывают по ур. 5 и 7. Количество NaOH берут 0,4 - 0,8 моль на моль H₂S, в присутствии меркаптанов это соотношение может составлять 0,1-0,3 моль NaOH в пересчете на 1 моль суммарной сероводородной и меркаптановой серы. Процесс окисления начинается в присутствии несвязанного сероводорода, т.е. при pH≈7. В процессе NaOH по реакции 5 регенерируется, pH среды возрастает, и при pH>7 начинается реакция 6, и при pH>8 относительно медленная реакция 7. В конечном итоге сероводород окисляется до элементной серы (до 70%) и тиосульфата (до 30%). Если достаточно времени для окисления, то водно-солевые стоки не содержат сульфидов.In the proposed method, the following reactions occur:

The consumption of oxygen and air is calculated by ur. 5 and 7. The amount of NaOH is taken 0.4 - 0.8 mol per mol of H ₂ S, in the presence of mercaptans, this ratio can be 0.1-0.3 mol of NaOH in terms of 1 mol of total hydrogen sulfide and mercaptan sulfur. The oxidation process begins in the presence of unbound hydrogen sulfide, i.e. at pH≈7. In the process, NaOH is reactivated by reaction 5, the pH of the medium increases, and at pH> 7 reaction 6 begins, and at pH> 8, the reaction is relatively slow 7. Ultimately, hydrogen sulfide is oxidized to elemental sulfur (up to 70%) and thiosulfate (up to 30% ) If there is enough time for oxidation, the water-salt effluents do not contain sulfides.

 Thus, the oxidation process without preliminary purification of raw materials from hydrogen sulfide can reduce alkali consumption by more than 2 times, and the effluent does not contain sulfides and does not require additional purification from sulfide sulfur.

 3. The effect of phthalocyanine catalysts on the reaction rate 5 is not so significant as on reaction 3, and the catalytic effect of various phthalocyanines is manifested approximately in the same order; therefore, various catalysts can be used in the proposed method: cobalt disulfo-, tetrasulfo- and polyphthalocyanines, as well as OKTPFK and DHDODSFK. The first three are dissolved in water, the last two in a 0.5-1.5% aqueous alkali solution. Water and an aqueous solution of alkali are preliminarily purified from dissolved oxygen by purging with an inert gas (nitrogen). The catalyst solution is directly injected (metered) into the feed stream. In parallel, 25-45% aqueous alkali solution is dosed in the feed. In the known method, a highly effective, but expensive catalyst, DHDODSFK is used, which is first dissolved in 1% alkali, then the concentration of the aqueous alkali solution is adjusted to 10-20% and this solution is introduced into the raw material.

From literature data it is known that phthalocyanines in strongly alkaline solutions oxidize rather quickly, the catalytic activity of solutions during storage decreases due to irreversible decomposition processes, and this process proceeds the faster, the higher the alkali concentration and oxygen access (Kundo N. N. Catalytic purification methods Sulphurous Emissions and Sulfur Production. - Dis.D. Kh.N .: Novosibirsk, 1991, p. 64). For example, in a 20% aqueous solution of NaOH in the presence of oxygen at 30 ^° C, DSPA is destroyed by about 25% in 1 h (Gorokhova S.A. Liquid-phase oxidative demercaptanization of light oil fractions in the presence of cobalt phthalocyanines. - Diss. Science: Kazan, 1989, p. 63). The preparation of aqueous and slightly alkaline solutions of phthalocyanine catalysts in water previously purified from oxygen and their storage under a nitrogen pad makes it possible to sharply increase the survivability (shelf life without loss of activity) of the catalyst.

 4. The reduced consumption of alkali and the introduction into the feed of concentrated solutions of alkali and catalyst in the proposed method increases the water content in the feed by no more than 0.1%, there is no need to separate this water from the feed in cases of formation of difficult to separate emulsions. Therefore, the proposed method can be used for refining heavy oils.

 5. In the known method, the process is carried out with recycling of the CPC. In the proposed method, the process is carried out with recirculation of part of the reaction mixture containing purified raw materials, the exhaust air dissolved therein and emulsified CPC. This mixture is mixed with the feedstock in the ratio (0.05-2): 1 at a pressure of 0.2-0.5 MPa.

The return to the process of part of the reaction mixture gives the following technical results:
not only unreacted alkali and catalyst are returned to the process (this is known), but with purified raw materials, elemental sulfur — the mercaptan oxidizing agent in reaction 6 — comes into the process, which speeds up the process;
Exhaust air containing more than 90% nitrogen enters the feed tank with the reaction mixture. When mixed with the feedstock and reducing the pressure to 0.2-0.5 MPa, this dissolved air is released, and nitrogen is mainly released, since the solubility of oxygen in the feed is almost two times that of nitrogen. Oxygen basically remains in solution. In a mixture of raw and purified raw materials, dissolved oxygen in the presence of emulsified CPC begins to react with hydrogen sulfide, oxidizes it to elemental sulfur in excess of hydrogen sulfide, reactions 5 and 6 proceed, and the resulting NaOH reacts 4. Since the residence time of the raw material in a large tank is hours , the results of these reactions become tangible (see table. 1);
allows you to reduce the necessary pressure in the reactor and the reaction tank. For example, with a content of 0.1% H ₂ S and 0.1% C ₁ -C ₂ mercaptans in the feed, for their oxidation, about 6 nm ^{3 of} air per 1 ton of feed is required, and for dissolving this air in the feed, the pressure is ≈5.5 MPa If the feedstock is diluted in a 1: 1 ratio with purified feedstock, then these 6 nm ^{3 of} air are already dissolved in 2 tons of feedstock, and a pressure of 2.8 MPa is sufficient for this.

The return of a part of the reaction mixture after the oxidation process to mix with the feedstock is not known, is not described in the literature, it allows oxidation under mild conditions (under reduced pressure), and the return of the main hydrogen sulfide oxidation product, elemental sulfur, accelerates the demercaptanization process. In addition, elemental sulfur with sulfides (NaSH, Na ₂ S) forms polysulfides, which are catalysts for the oxidation of hydrogen sulfide itself.

6. In the proposed method, alkali and catalyst solutions are introduced into the feed stream, they are mixed, then air is introduced into the stream, and in the known method CPC and air are introduced simultaneously. The positive effect of pre-aging the catalyst in a reducing medium is known from the literature. Thus, it was found that during the oxidation reaction of mercaptans (mercaptoethanol) in an aqueous alkali solution, the predominant form of the catalyst Pc (cobalt sulfophthalocyanine) is the dimeric form of the adduct with oxygen. It has an assumed structure of RS ^- Co ^III PcO ₂ Co ^III PcRS ^- . Mercaptide ion RS ^- acts as a stabilizer of the state of Co ^III . The restoration of this state with mercaptoethanol is a limiting step in the process. When kept in a reducing environment, the formation of Co ¹ Pc forms. If the catalyst is introduced into the oxidizing zone after aging in a reducing medium, the reaction rate increases sharply until a less active complex containing Co ^{III is formed} . Polysulfides, which are formed during the oxidation of hydrogen sulfide in the presence of sulfur, have a strong reducing effect (Kundo N.N. Catalytic methods for purifying sulfur dioxide emissions and producing sulfur. - Diss. Doctor of Chemical Sciences, Novosibirsk, 1991, p. 87).

The use of a 25-45% aqueous alkali solution is justified by the fact that at low concentrations of alkali, a lot of water is forced to be introduced into the feedstock, which means that when separation is impossible, the water content in the purified feedstock increases, and when the alkali concentration is above 45%, the probability of solidification, precipitation from the solution increases solid phase when the temperature drops below 10 ^o C. Domestic industry produces a 40-45% solution of alkali, this solution can be applied without dilution. When the alkali consumption is less than 0.1 mol per mol of hydrogen sulfide and mercaptan sulfur, the required degree of purification is not achieved, and there is no need to increase the consumption of more than 0.8 mol.

 The concentration of the catalyst is 0.15-0.25% in solutions due to their solubility in water or 0.5-1.5% aqueous alkali solution. With the introduction of a catalyst of less than 0.01 g per mole of hydrogen sulfide and mercaptan sulfur, the required purification of the feedstock is not achieved, and there is no need for a flow rate of more than 0.1 g.

A minimum pressure of 0.5 MPa is necessary for dissolving up to 0.5 nm ^{3 of} air in the feed and for transferring part of the reaction mixture from the settling tank to the feed tank for mixing with the feedstock. There is no need to increase the pressure above 3.0 MPa. At high air flow rates (more than 3.5 nm ³ / t), it is more economical to achieve the dissolution of the required air volume by increasing the amount of purified raw materials returned to the process, and not by increasing the pressure (installing a two-stage compressor and containers operating under high pressure). Heating the reaction mixture to 25-65 ^o C and holding for 5-180 minutes are necessary and sufficient conditions for the oxidation process. At a temperature below 25 ^o C or a time of less than 5 min, the required degree of purification of the raw material is not achieved, and there is no need to increase the temperature above 65 ^o C and a time of more than 180 min, since during this time, even at a temperature of 25 ^o C, the required degree of purification of the raw material is achieved .

The minimum volume of 5% of the feedstock of the returned reaction mixture is sufficient if the spent CPC is separated from the purified feed, since with these 5% the spent CPC separated in the settling tank will return to the process. A return of up to 200% to the feed of the reaction mixture is necessary in the case of the formation of a non-separable emulsion and a very high content of hydrogen sulfide and low molecular weight mercaptans in the feed, when a large volume of air is required for their oxidation. For example, for 1 ton of feed oil containing 0.1% H ₂ S and 0.1% mercaptans C ₁ -C ₂ , ≈6 nm ^{3 of} air is required. If this 1 ton of initial oil is mixed with two tons of refined oil, then 6 nm ^{3 of} air is dissolved in 3 tons of oil, for which 2 MPa of pressure is sufficient. Receive 3 tons of refined oil, and of which 2 tons (200%) are returned back to mixing with the original oil. Their mixing is carried out at a pressure of 0.2-0.5 MPa. At a lower pressure, almost all the air dissolved in the reaction mixture is released from the feedstock and oxygen is low for the oxidation reaction to occur, and at pressures above 0.5 MPa, little nitrogen is released from the mixture to create a nitrogen pad in the feed tank.

To achieve the aforementioned technical results, a device is proposed for deodorizing the purification of oil and gas condensate from hydrogen sulfide and low molecular weight mercaptans (Fig. 2), which contains a feed tank 1, a feed pump 2, an air inlet device 3, a heater 4, a reactor 5, and a settling tank for collecting the reaction mixture 6, the separator 7, the capacity of the alkali solution 8, the capacity of the catalyst solution 9, the pump for supplying the alkali solution 11, the pump for supplying the catalyst solution 12. In contrast to the tank the catalyst solution 9 is equipped with a bubbling device 10 for purging the solution with an inert gas, for example nitrogen, the discharge lines of the alkali solution supply pumps 11 and the catalyst 12 are connected to the suction line of the raw material pump 2, the device 3 for mixing air with raw materials is installed after the raw material pump, and the lower part a settling tank 6 for collecting the reaction mixture is connected by a pipeline through a flow regulator 13 to a feed tank 1. A heater 4 is installed between the air input device 3 and the reactor 5. As e of device 3 for supplying air and mixing it with raw materials, a pressure injector is installed or a compressor is installed for supplying compressed air, and a device is installed for mixing it with raw materials (Fig. 3) made of a pipe in the form of a torus with holes directed against the flow of raw materials at an angle of 20-30 ^o C. Compressed air is fed through these holes against the flow of raw materials, which provides additional mixing and dissolution of air in the feed. The injector is placed at an air flow rate of up to 1 nm ³ per 1 m ^{3 of} liquid supplied to the injector. At an air flow rate of more than 1 nm ³ , a compressor is installed.

The proposed installation works as follows. In the feed tank 1, mixing in the inlet pipe, the feedstock and the reaction mixture containing purified feedstock and spent CPC and air are supplied. In the feed tank 1 at a pressure of 0.2-0.5 MPa, part of the exhaust air, mainly nitrogen, is released into the gas phase, forming a nitrogen cushion, which prevents atmospheric air from breathing in the feed tank and the formation of an explosive gas-air mixture. The mixture of raw materials from the tank 1 enters the feed pump 2. The alkali and catalyst solutions are continuously introduced into the feed stream before the feed pump by pumps 11 and 12 from the tanks 8 and 9. The mixing (emulsification) of these solutions with the raw materials takes place in the raw material pump 2, i.e., the raw material pump is used both as a pump and as a mixer. Additional mixing takes place in the device - 3 for mixing air with raw materials, for example, in the injector. After the feed pump 2, air is introduced into the feed stream. Air is introduced using a compressor (not shown in Fig. 2) under a pressure of 0.5-3.0 MPa through a device 3 for mixing compressed air with raw materials (see Fig. 3) or sucked into the stream using a pressure injector. The pressure in the stream after entering the air is maintained so as to dissolve all the air in the feed. Next, the flow enters the heater 4, where it is heated to 25-65 ^o C, in the heater 4 there is a partial oxidation of hydrogen sulfide and mercaptans, after which the feed stream enters the reactor 5, where the bulk of the hydrogen sulfide and mercaptans are oxidized, then to the settling tank 6 to collect the reaction mixture, where partial separation of spent CPC from a raw material in the event of the formation of an unstable emulsion can occur, and to a separator tank 7, where, at reduced pressure of 0.1-0.4 MPa, the purified raw material is separated from the spent ozduha and uphold water-salt runoff. The oxidation processes continue in tanks 6 and 7, if they did not end in reactor 5, for example, sodium sulfides are oxidized to thiosulfate and sulfate. Part of the reaction mixture in an amount of 5-200% of the feedstock from the tank 6 through the flow regulator 13 due to the pressure difference is sent to the feed tank 1, at the entrance to this tank it is mixed with the feedstock.

 In the case of the formation of unstable emulsions in the separator vessel 7, a water-salt solution is deposited from the purified raw material, containing mainly sodium thiosulfate, as well as small amounts of sulfate, caustic soda and catalyst. The main product of the oxidation of hydrogen sulfide - elemental sulfur remains in the purified raw material in dissolved form. The volume of water-salt effluents does not exceed 0.1% of the purified raw materials.

 In the case of the purification of oils forming non-separable emulsions with alkaline solutions, water-salt effluents are absent.

 Oxidation time — the residence time of the reaction mixture in apparatuses 4, 5, 6 can reach 180 minutes. The installation of the heater 4 after the input device and mixing air 3 allows partial oxidation during the residence of the raw materials in the heater and reduce the volume of the reactor 5.

Distinctive features of the proposed installation are:
the presence of a bubbler 10 in the tank 9;
the connection of the discharge lines of the pumps 11 and 12 with the suction line of the feed pump 2 and its use as a mixer of raw materials with solutions of alkali and catalyst;
the connection of the settling tank 6 by a pipeline through a flow regulator 13 with a feed tank 13, through which part of the reaction mixture is mixed with the feedstock due to the pressure difference, its flow rate is regulated by a flow regulator;
the presence of a device for efficient mixing of air with raw materials, made in the form of a torus with holes (see Fig. 3) or a pressure injector.

 In the known method, the spent CPC from the sump is pumped to the discharge line of the feed pump, and the combined input device of CPC and air into the feed, the so-called cross-shaped mixer, does not provide for their effective mixing, does not have special mixing elements, thin mixing of the feed with CPC is carried out in the reactor (column with sieve failed plates). When refining oils that form stable emulsions with alkaline solutions, according to the proposed method, it is not necessary to have a column with sieve failed trays; any vessel providing the necessary residence time of the reaction mixture can be used as a reactor.

 In addition, the use of an injector allows you to create a cleaning plant without a compressor, energy costs are reduced.

 In terms of capital costs, the proposed installation is cheaper than the known one, since there is no preliminary alkalization apparatus and a pump for the delivery of spent CPC (see Fig. 1).

 The method was tested in laboratory conditions and in a pilot plant, below are examples and results of experiments.

 Examples 1-7.

 In a funnel-shaped flask with a narrow neck (⌀ = 14 mm), 50 ml of water are taken per 100 ml, nitrogen is passed through a glass tube passed to the bottom of the flask (sparged) for 10 min, then a catalyst sample (DSPC) is introduced into the flask and sparging for another 5 minutes. The solution is stored closed in a dark place, its activity during storage does not decrease during the week.

In a round-bottomed flask with a capacity of 100 ml take calculated weighed portions of a 25-45% aqueous solution of NaOH and 0.15-0.25% aqueous solution of DSFC, add 35-40 ml of oil or gas condensate cooled to 0-5 ^o C containing H ₂ S and RSH. Stirred for 2 minutes. Then the flask is filled with oxygen, tightly closed with a rubber stopper and quickly heated to 25-65 ^o C, the contents are stirred by shaking, kept under stirring for 5-180 minutes After that, the flask is cooled in ice water and samples are taken for analysis according to GOST 22985-90 to determine hydrogen sulfide and the total amount of mercaptan sulfur. The content of low molecular weight mercaptans C ₁ -C ₂ determined chromatographically. The conditions and results of the experiments are given in table. 1. The amount of oxygen provides ≈1.5-fold excess of the calculated according to equations 5 and 7.

 Examples 8 to 18.

The reaction mixture from the previous experiment was introduced into the initial oil or gas condensate in an amount of 5-200%, containing purified raw materials, spent CPC and dissolved oxygen, the mixture was incubated for 1 h at 15-20 ^o C, then cooled to 0-5 ^o C. Then experiments, as in examples 1-7, using this raw material. The conditions and results of the experiments are given in table. 1.

 Example 19

 Preliminarily, hydrogen sulfide is extracted from the raw material with 5% alkali, then mercaptans are oxidized, as in examples 1-7. Spent CPC is used to prepare 5% alkali.

The task of deodorization of oil and gas condensate is considered to be achieved if the content of purified hydrogen sulfide does not exceed 20 ppm and mercaptans C ₁ -C ₂ also 20 ppm. Such standards are currently set in the industry. The standards for mercaptans C ₃ and above are not established.

 In examples 1-19, as the phthalocyanine catalyst used the cheapest and most affordable of them - DSPK. Other cobalt phthalocyanines proposed in the invention, according to published data, are more active than DSFK, i.e., if applied, the experimental results would not be lower than in the experiments of Table. 1. The data table. 1 confirm the possibility of deodorization of various oils and gas condensate in the conditions specified in the claims.

 Sludge from spent CPC is observed during deodorization of Tengiz (light) oil and Karachaganak gas condensate. In other cases, the formation of non-separable oil emulsions with solutions of NaOH and catalyst is observed. In experiments Nos. 12 and 18, for mixing with the feedstock, the lower part of the reaction mixture (purified feedstock) enriched with spent CPC is taken, which gives a positive effect even when a small amount (5-10%) of the oxidized reaction mixture is returned to the process. The return of a portion of the purified feedstock and spent CPC to mixing with the feedstock allows one to achieve a better degree of purification at the same reagent costs (experiments N 1-4 and 8-11), or to carry out the process under milder conditions (experiments N 5 and 12), or to achieve the same degree of purification, but at reduced consumption of reagents (experiments N 7 and NN 15-18).

 In experiments N 15 and 16, the consumption of NaOH per 1 ton of the original is 409 g. In experiments N 17 and 18 138 g, and in the known method, in experiment N 19 730 g. In table. 1, the costs of NaOH and DSFC are given per 1 mol of oxidized hydrogen sulfide and mercaptan sulfur during the purification process.

 Examples 20 to 26

 The experiments are carried out, as in examples 1-7, apply 40% NaOH and 0.2% solutions of various catalysts. DHDODSFK and OKTFPK are dissolved in 0.5-1.5% alkali, the rest in water. In experiments N 20-23, analyzes of purified raw materials were carried out after 45 minutes and again after 60 minutes of exposure. The results of the experiments are given in table. 2.

 Example 27

DXDODSFK was dissolved in a 1% aqueous alkali solution, then the alkali concentration was adjusted to 20% and held at 20 ^° C for 3 hours. The experiment was carried out as in Examples 20-26, but using this solution. The result of the experiment is given in table. 2.

 Carrying out the oxidation process in an oxygen atmosphere at 0.1 MPa made it possible to simulate the oxidation process with air at a pressure of 0.5 MPa, since approximately the same amount of oxygen was dissolved in the liquid phase.

Меркаптаны C₁-C₂ в очищенном сырье во всех опытах табл. 2 не обнаруживаются.In the table. Figure 2 shows the consumption of NaOH and catalysts per 1 mol of H ₂ S excluding mercaptans, since the content of low molecular weight C ₁ -C ₂ mercaptans is close to zero, and the total mercaptan content during oxidation decreases slightly. As can be seen from the table. 2, during the oxidation of hydrogen sulfide, the activity of DSPK and PFC is slightly lower than the activity of TSPK and DHDODSFK, but there is no significant difference between them. In the case of using a solution of the catalyst in 20% NaOH prepared according to the known method and after 3 hours of storage, the activity of DHDODSFK decreases from 84 to 76% by the degree of purification from hydrogen sulfide. The degree of purification (C,%) of H ₂ S is calculated by the formula

Mercaptans C ₁ -C ₂ in purified raw materials in all experiments table. 2 are not detected.

 Example 28

 Tests in a pilot plant.

S_RSH=1100 ppm, в том числе сера меркаптанов C₁-C₂ - 15; C₃ - 48 ppm. Общее время пребывания нефти в подогревателе и реакторе составляет 8 мин, в емкости-отстойнике около 3 ч. Пробы нефти на анализ отбирают перед входом в отстойник и на выходе из него, т.е. через 8 мин и 180 мин после введения воздуха, т.е. начала реакции. За 180 мин температура нефти за счет естественного охлаждения в отстойнике снижается до 40^oC. Сжатый воздух подают компрессором через смесительное устройство, выполненное в виде тора (см. фиг. 3), под давлением 1,1 МПа. Давление смеси в подогревателе и реакторе поддерживают равным 1,0 МПа, в отстойнике 0,5 МПа. Из отстойника периодически через каждые 2 ч работы подают в сырьевую емкость очищенную нефть в количестве около 0,2 объемов емкости. Результаты четырех опытов приведены в табл. 3. При указанных в изобретении режимах процесса за 8 мин содержание сероводорода снижается в 7-10 раз, дополнительная выдержка нефти в отстойнике позволяет снизить содержание сероводорода ниже 20 ppm, общее содержание меркаптанов снижается примерно на 200 ppm, низкомолекулярные меркаптаны C₁-C₂ в очищенной нефти не обнаруживаются. Разделение отработанного КТК не происходит, солевые стоки отсутствуют.The experiments are carried out in a pilot plant as shown in FIG. 2 technological scheme with a capacity of 30 m ³ / h of oil. The source oil contains

S _RSH = 1100 ppm, including sulfur mercaptans C ₁ -C ₂ - 15; C ₃ - 48 ppm. The total residence time of the oil in the preheater and reactor is 8 minutes, in the sump tank about 3 hours. Oil samples are taken for analysis before entering and leaving the sump, i.e. 8 min and 180 min after the introduction of air, i.e. the beginning of the reaction. After 180 minutes, the oil temperature due to natural cooling in the sump decreases to 40 ^o C. Compressed air is supplied by the compressor through a mixing device made in the form of a torus (see Fig. 3), under a pressure of 1.1 MPa. The pressure of the mixture in the heater and reactor is maintained equal to 1.0 MPa, in the sump of 0.5 MPa. From the sump, periodically every 2 hours of operation, refined oil is fed into the feed tank in an amount of about 0.2 tank volumes. The results of four experiments are given in table. 3. Under the process conditions indicated in the invention, the hydrogen sulfide content is reduced by 7-10 times in 8 minutes, the additional oil exposure in the sump allows reducing the hydrogen sulfide content below 20 ppm, the total mercaptan content decreases by about 200 ppm, the low molecular weight C ₁ -C ₂ mercaptans Refined oil is not detected. Separation of spent CPC does not occur, there is no salt effluent.

 Example 29

The experiment is carried out in a pilot installation according to the technological scheme of FIG. 2, pressure injectors of type H according to OST B 84-1500-77 are used as devices for supplying and mixing air with raw materials. Raw materials with a flow rate of 2 m ³ / h are fed into the injector nozzle under a pressure of 1.4 MPa. The injector draws in 1 m ³ / h of air, which dissolves in the feedstock in the pipeline after the injector at a pressure of 0.9 MPa. The feed oil contains 16 ppm H ₂ S, 660 ppm S _RSH and 178 ppm C ₁ -C ₂ mercaptans based on sulfur. The consumption of NaOH is 0.3 mol, DSPK 0.3 g per 1 mol of hydrogen sulfide and mercaptan (C ₁ -C ₂ ) sulfur. Temperature 55 ^o C, the oxidation time of 10 minutes The purified raw material contains: H ₂ S - exc., S _RSH = 438 ppm, sulfur mercaptans C ₁ -C ₂ 6 ppm.

Claims (10)

1. The method of deodorizing purification of oil and gas condensate from hydrogen sulfide and low molecular weight mercaptans by oxidizing air oxygen in the presence of an aqueous alkaline solution of a phthalocyanine catalyst, comprising continuously introducing into the raw material the calculated amounts of an aqueous alkaline solution of the catalyst and air, keeping the resulting mixture at a pressure of 0.5 - 3.0 MPa and a temperature of 25-65 ^o C and separation of the reaction mixture with release of the purified feedstock, characterized in that the feed stream without preliminary purification of the hydrogen sulfide at ne while mixing, a 25-45% aqueous alkali solution and a 0.15 - 0.25% solution of a phthalocyanine catalyst in water purified from dissolved oxygen or a 0.5-1.5% aqueous alkali solution are simultaneously introduced, then into the stream air is introduced into the feedstock, the resulting mixture is incubated for 5-180 min, after which part of the reaction mixture containing purified feedstock, dissolved exhaust air and an emulsified aqueous alkaline catalyst solution is directed to mixing with the feedstock, which is carried out at a pressure of 0.2- 0.5 MPa.  2. The method according to claim 1, characterized in that a 25-45% aqueous alkali solution is administered at the rate of 0.1-0.8 moles of sodium hydroxide per 1 mole of hydrogen sulfide and mercaptan sulfur.  3. The method according to claim 1, characterized in that a 0.15-0.25% solution of a phthalocyanine catalyst is introduced at the rate of 0.01-0.1 g of catalyst per 1 mol of hydrogen sulfide and mercaptan sulfur.  4. The method according to claim 1, characterized in that part of the reaction mixture is sent for mixing with the feedstock in the ratio (0.05-2): 1.  5. The method according to PP. 1-3, characterized in that as the phthalocyanine catalyst used disulfo-, tetrasulfo-, dichlorodioxidisulfo-, octacarboxytethenyl- and cobalt polyphthalocyanine.  6. The method according to claim 1, characterized in that the purification of water or 0.5-1.5% aqueous solution of alkali from dissolved oxygen to prepare a 0.15-0.25% solution of a phthalocyanine catalyst is carried out by inert blowing gas, for example, nitrogen.  7. Installation for deodorizing purification of oil and gas condensate from hydrogen sulfide and low molecular weight mercaptans, containing a raw material tank, a raw material pump, containers for preparing and storing alkali and catalyst solution, pumps for supplying them, an air supply device and a device for mixing air with raw materials, a heater , a reactor for the oxidation of hydrogen sulfide and mercaptans, a settling tank for collecting the reaction mixture and a separator tank for separating this mixture, characterized in that the tank for preparing the solution is cat the lyser is equipped with a bubbling device for purging the solution with inert gas, the discharge lines of the alkali and catalyst solution supply pumps are connected to the suction line of the raw material pump, the device for mixing air with raw materials is installed after the raw material pump, and the lower part of the settling tank for collecting the reaction mixture is connected via a flow regulator with raw material capacity. 8. Installation according to claim 7, characterized in that the device for mixing compressed air with raw materials is made in the form of a torus with holes directed against the flow of raw materials at an angle of 20-30 ^o .  9. Installation according to claim 7, characterized in that the heater is installed between the device for mixing air with the feed and the reactor.  10. Installation according to claims 7 and 9, characterized in that a pressure injector is used as a device for supplying and mixing air with raw materials.

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