RU2189340C2 - Method of storage hydrogen sulphide- and/or mercaptan- containing crude oil, oil products and gas condensate in reservoir in inert gas atmosphere - Google Patents

Abstract

FIELD: gas and oil producing and oil processing industries. SUBSTANCE: method comes to filling of reservoir with oil products and storing them in inert gas atmosphere and giving out. Prior to filling, compressed air is introduced into hydrogen sulfide- and-mercaptan-containing raw material, or oil products, or gas condensate in presence of catalysts at pressure of 0.3-3.0 MPa in amount of 0.06-0.12 nm³ per mole of hydrogen sulfide or 2 moles of mercaptans C₁-C₃. Solution is kept at temperature of 10-65 C for 5-180 min. After oxidizing of hydrogen sulfide and mercaptan by oxygen from air, solution is delivered into reservoir where pressure in reduced to 0.1-0.6 MPa. Waste air dissolved in raw material and containing more than 90% of nitrogen and less than 7% of oxygen is liberated forming nitrogen cushion over liquid. Alkaline water solutions of cobalt phthalocyanines are used as catalysts. NaOH, Na₂CO₃, Na₂S, NH₃ and alkanolamines are used as alkaline agents. Consumption of cobalt phthalocyanine is 0.02-0.2 g, alkaline agent is 0.1-0.6 moles per mole of hydrogen sulfide or 2 moles of mercaptans C₁-C₃.. EFFECT: simplified storage and reduced cost of storage. 6 cl, 3 ex, 1 tbl

Description

 The invention relates to methods for the safe storage of flammable liquids (LVF) in tanks and can be used in the gas and oil and oil refining industries.

 Light fractions of oil products and gas condensates are related to flammable liquids. The content of flammable liquids in oils can reach up to 50 percent or more. It is known that flammable vapors, including hydrocarbon vapors, form explosive mixtures with air.

 In order to reduce the loss of flammable liquids and to eliminate the possibility of the formation of explosive mixtures of flammable vapor with air in reservoirs, expensive storage facilities with a floating roof or with an internal floating roof are being built. In A.S. 137462 (RZh, ser. VII, 3, 1962, 3M255) it is proposed to fill the gas space above the oil in the tank with an inflatable balloon of soft material into which air is pumped; this cylinder fills the entire space above the oil in the tank. More realistic for practical use are methods of coating the surface of a liquid (oil product) in a tank with a protective layer of inert liquid, foam (a.s. 1738323; BI 21, 1992, p. 33) or an elastomer (a.s. 1551627; BI 11, 1990 , p. 85).

 In the patent application of the Russian Federation 96105794/13 dated 03/26/96 (BI 18, 1998, p. 54), it is proposed to fill the reservoir before the oil injection with reservoir water, and the oil injection and selection operation should be carried out simultaneously with the selection and introduction of water into the reservoir from the buffer tank for water. This method eliminates the possibility of air entering the tank when pumping oil and the release of oil vapor into the atmosphere when filling the tank with a fixed roof. The method is quite simple and reliable enough, however, it requires a second water tank and additional pumps for pumping and pumping water, respectively, increasing energy costs.

Known methods for storing flammable liquids in tanks under an inert gas atmosphere (helium, argon, nitrogen, carbon dioxide and mixtures thereof) and methods for displacing flammable liquids from storage under pressure of inert gas supplied from cylinders and gas tanks with compressed inert gas. Besides such inert gases proposed water soluble gases (CO _2, NH _3, H ₂ S, etc.) /A.s. 170,890; RZH "Mining", ser. G, 1966, 3 and 9, 3G333 /.

In US patent 3895098 (publ. 15.07.75) it is proposed to introduce a salt of nitric acid (NaN ₃ ) into the fuel composition. When the fuel ignites, this salt decomposes, as a result, nitrogen (N ₂ ) is released, which fills the air space above the burning fuel and helps to extinguish the flame, prevents the possibility of an explosion. This method does not exclude the possibility of ignition, only contributes to the extinction of the flame.

According to the technical nature and the achieved result, the closest to the proposed invention is a method for storing petroleum products in a tank by feeding liquid carbon dioxide in an amount of 150-300 g per 1 m volume of a vapor-air mixture into the tank volume. Liquid carbon dioxide (CO ₂ ) quickly evaporates, diluting and cooling the vapor-air mixture over the oil product (AS 1604692; BI 41, 1990).

The disadvantage of this method is the complexity of the process associated with the receipt, storage and supply of liquid CO ₂ to the tank.

 The objective of the present invention is to simplify and reduce the cost of the method of safe storage of petroleum products, oil and gas condensate under inert gas.

According to the invention, the task is achieved by storing hydrogen sulfide and / or mercaptan-containing oil, oil products and gas condensate in a tank, including filling, storage under an inert gas atmosphere and issuing, characterized in that before filling in hydrogen sulfide and / or mercaptan-containing oil, or oil products, or gas condensate is injected with compressed air at a pressure of 0.3-3 MPa in the presence of a catalyst, after which it is held for 5-180 minutes. at a temperature of 10-65 ^o C, and the filling is carried out at a pressure in the tank of 0.1-0.6 MPa, followed by the formation of a nitrogen atmosphere over the stored raw materials.

During continuous operation, oil or gas condensate is piped through one or different mixing devices, such as nozzles, to continuously feed the catalyst mixture and compressed air. In the pipeline to reservoirs several kilometers long, for 5-180 min, H ₂ S and RSH are oxidized with dissolved oxygen under a pressure of 0.3-3.0 MPa. If the pipeline is short and the residence time of the raw materials in it is insufficient or heating and efficient mixing are required, then an additional reactor is installed.

В качестве катализаторов применяют водно-щелочные растворы различных фталоцианинов кобальта: дисульфо-, тетрасульфо-, дихлордиоксидисульфо- и полифталоцианин кобальта. В качестве щелочного агента используют едкий натр, карбонат натрия, сульфид натрия, аммиак и органические алканоламины (моноэтаноламин, триэтаноламин и метанолэтаноламины). Водно-щелочной раствор фталоцианинового катализатора вводят в исходное углеводородное сырье из расчета 0,1-1,6 молей щелочного агента и 0,01-0,2 г фталоцианина на 1 моль сероводорода или на 2 моля меркаптанов C₁-С₃ (СН₃SН, C₂H₅SH, С₃Н₇SН). Воздух вводят в количестве 0,06-0,12 нм³ на 1 моль сероводородной серы или на 2 моля меркаптановой (C₁-С₃) серы.The basis of the proposed method is the well-known oxidation reaction of hydrogen sulfide and mercaptans with dissolved atmospheric oxygen in the presence of catalysts or a mixture (solutions) of catalysts:

As catalysts, water-alkaline solutions of various cobalt phthalocyanines are used: disulfo-, tetrasulfo-, dichlorodioxidisulfo- and cobalt polyphthalocyanine. As the alkaline agent, sodium hydroxide, sodium carbonate, sodium sulfide, ammonia and organic alkanolamines (monoethanolamine, triethanolamine and methanol ethanolamines) are used. An aqueous-alkaline solution of the phthalocyanine catalyst is introduced into the hydrocarbon feed at the rate of 0.1-1.6 moles of an alkaline agent and 0.01-0.2 g of phthalocyanine per 1 mole of hydrogen sulfide or 2 moles of mercaptans C ₁ -C ₃ (CH ₃ CH, C ₂ H ₅ SH, C ₃ H ₇ CH). Air is introduced in an amount of 0.06-0.12 nm ³ per 1 mol of hydrogen sulfide sulfur or 2 moles of mercaptan (C ₁ -C ₃ ) sulfur.

The qualitative and quantitative composition of the catalyst solutions and the conditions for reactions 1 and 2 (with the aim of purifying the raw materials from H ₂ S and RSH) are given in RF patents 2087521, 2120464 and 2114896.

When cleaning petroleum distillates from hydrogen sulfide and light mercaptans C ₁ -C ₃ by oxidizing them with atmospheric oxygen (air is dissolved in the feed under pressure), solid catalysts can also be used - cobalt phthalocyanines and heavy metal salts (Co ⁺³ , Ni ^{+ 2} , Cu ^{+ 2} , Fe ^{+ 2} , Mn ^{+ 2} ) deposited on a solid support (activated carbons, carbon fiber fabrics, polymers, etc.). The use of solid catalysts in the purification of petroleum distillates from H ₂ S and RSH is described in RF patents 2076892 [BI 10, 1997, p. 148], 2110555 [BI 13, 1998, p. 310], 2106387 [BI 7, 1998, p. 234] and application 96116491/04 [BI 12, 1998, p. 55].

The necessary amount of oxygen for the oxidation of H ₂ S and light mercaptans C ₁ -C ₃ present in the feedstock is calculated according to equations 1 and 2. Since, along with reactions 1 and 2, side reactions of oxidation of sulfur, disulfides, and some other easily oxidized organic substances occur, the actual oxygen consumption exceeds stoichiometric consumption by 20-50%. Therefore, air is taken in excess of 20-50%. The oxidation reaction is carried out under pressure in the liquid phase, i.e. air is completely dissolved in raw materials. The dependences of the solubility of air in oil with a density ρ = 876 and ρ = 825 kg / m ³ and gas condensate (ρ = 780 kg / m ³ ) on overpressure at 40 and 65 ^o C are shown in FIG. 1 and 2.

For the oxidation of one mole of hydrogen sulfide (34 g), reaction 1 requires 0.5 moles (16 g) of oxygen or 16 / 0.23 = 69.6 g of air. The required amount of air with an excess of 20-50% is 83.5-104.3 g or 0.0647-0.0809 nm ³ per 1 mol of H ₂ S or 2 mol of RSH.

нм³ на 1 т сырья, для растворения этого воздуха в нефти требуется давление около 0,3 МПа (см. фиг.1 и 2). Максимальный расход воздуха

нм³ на 1 т сырья.After stabilization, oils and gas condensates contain 50-300 ppm or 0.05-0.03% hydrogen sulfide and 200-1000 ppm or 0.02-0.1% sulfur C ₁ -C ₃ mercaptans. Hence the minimum air flow is

nm ³ per 1 ton of raw materials, to dissolve this air in oil, a pressure of about 0.3 MPa is required (see figures 1 and 2). Maximum air flow

nm ³ per 1 ton of raw material.

Assuming that the permissible amount of oxygen in the exhaust air is 7%, the maximum air flow rate can be increased to (0.0809-0.23) / (0.23-0.07) = 0.12 nm ³ per 1 mol of hydrogen sulfide or 1.9 • 0.2 / (0.23-0.07) = 2.73 nm ³ per 1 ton of raw material. To dissolve 2.73 nm ³ air in 1 ton of oil, a pressure of about 3 MPa is required. After the oxidation reaction, the feed is fed to the tank, when the feed is fed to the tank, the pressure is reduced to 0.1-0.6 MPa, while the dissolved exhaust air is released from the liquid phase into the gas phase, and mainly inert nitrogen is released (evaporated from the feed), since oxygen in the exhaust air is firstly small, secondly, oxygen dissolves in oil products almost twice as much as nitrogen [Handbook of a chemist, vol. 3, M., 1964, p. 323]. Therefore, nitrogen evaporates, and most of the oxygen remains in solution and continues to react with the mercaptans remaining in the feed. In the absence of C ₁ -C ₃ mercaptans, heavier mercaptans react, i.e. mercaptans C ₄ or more.

In a tank of 1 ton of raw materials, with a decrease in pressure to 0.1 MPa, 0.22-2.2 nm ³ nitrogen can be released. If the tank is under overpressure, then the volume of nitrogen released will be lower corresponding to this pressure (see figures 1 and 2).

In the above patents, in order to quickly and completely purify the raw materials from H ₂ S and RSH, air is taken with a large excess (0.1-0.2 nm ³ per 1 mol of total hydrogen sulfide and mercaptan sulfur. At present, oil and oil distillate treatment plants then the exhaust air is sent to the torch or to the calcining furnace, i.e. it is emitted after cleaning from hydrocarbon vapors into the atmosphere.

 In the present invention, a large excess of air is unacceptable, since this leads to an increase in the oxygen content in the exhaust air, respectively, above the liquid hydrocarbon.

 The proposed method for the safe storage of oil, gas condensates and liquid petroleum products is simple to implement and can be combined with the process of purification of these products from hydrogen sulfide and mercaptans used in industry and fields.

The stage of catalytic oxidation of H ₂ S and RSH with atmospheric oxygen in the present invention basically does not differ from the known methods described in the above patents of the Russian Federation and used in the oil industry, except for a slightly reduced air flow. In contrast to the known in the proposed method, not liquefied inert gases are used, but free nitrogen from the exhaust air. In known methods, this air is emitted into the atmosphere.

 The proposed method was tested in laboratory conditions and on the existing installation of deodorizing oil purification from hydrogen sulfide and mercaptans.

Example 1
Experiments on the oxidation of H ₂ S and RSH contained in oil by atmospheric oxygen in the presence of catalysts to form a mixture of nitrogen (exhaust air) and oil.

A calculated amount of a solution of a catalyst or a heterogeneous (solid) catalyst is placed in a 100 ml flask, a calculated amount of oil cooled to -6 ^o C (25-60 ml) is added, hermetically sealed with a rubber stopper and at a certain temperature (10-65 ^o C) stirred within 5-180 minutes The pressure in the flask is created by the evaporation of hydrocarbons when heated. After it is cooled to 10-15 ^° C and an air sample is taken from the flask with a syringe for chromatographic analysis for the content of Na and O ₂ , then the contents of H ₂ S and mercaptans C ₁ -C ₃ in oil are analyzed.

The results of the experiments are shown in the table. In the experiments, the tables used the most affordable and cheapest, at the same time, the least active of cobalt disulfophthalocyanine (DSFC) catalysts. According to published data, other phthalocyanines are more active than DSFK; when using other phthalocyanines, the oxidation of H ₂ S and RSH is faster and deeper. The costs of the catalyst DSFK are given in g, and the alkaline agent in moles per 1 mol of total sulfur of hydrogen sulfide +0.5 moles of sulfur mercaptans C ₁ -C ₃ .

The table shows that various methods of oxidation of H ₂ S and RSH using various catalysts and different types of raw materials within certain limits of air to hydrogen sulfide (mercaptans) ratios make it possible to produce nitrogen with less than 7% oxygen and create an atmosphere from an inert gas over the purified feed.

Example 2
The experiment is carried out on an industrial installation of deodorizing oil refining of the Tengiz field from hydrogen sulfide and mercaptans. 300 m ³ / h of oil, containing 460 ppm mercaptans C ₁ -C ₃ , with a temperature of 50-55 ^o C, is continuously fed into the reactor (column with sieve plates) with a temperature of 50-55 ^o C. Before entering the reactor, 0.02% a solution of cobalt dichlorodioxidisulfophthalocyanine in a 2% aqueous NaOH solution. The consumption of dichlorodioxidisulfophthalocyanine 0.5 g, NaOH - 50 g per 1 m ³ oil or 0.08 g phthalocyanine and 80 g NaOH per 2 moles of mercaptans. Compressed air in the amount of 180 m ^{3 is} continuously supplied to the bottom of the column under a pressure of 1.0 MPa / hour (~ 0.11 nm ³ per 2 mol of RSH). The temperature in the reactor is 50-55 ^o C, the residence time of the oil is ~ 5 minutes, the pressure is 0.8 MPa. Oil from the reactor enters the separator, where the pressure drops to 0.2 MPa. At the same time, the exhaust air is extracted from oil in an amount of about 100 m ³ / h, containing 5 ± 0.2% oxygen, 90% nitrogen and ~ 4.5% hydrocarbons.

Example 3
Experiments on pumping gas condensate into the tank and pumping it out of the tank:
3.1. 1 m ^{3 of} gas condensate after oxidation of H ₂ S and RSH contained in it at a pressure of 0.8 MPa contains 1.0 nm ^{3 of} dissolved exhaust air (Fig. 1) containing about 93% nitrogen. Gas condensate is fed into a tank with a volume of 1000 m ³ . Suppose, in this case, there is an ideal displacement of the air in the empty tank by the exhaust air, which is released (evaporated) from the gas condensate. After the start of gas condensate intake, a small layer (cushion) of exhaust air is formed above the liquid phase in the reservoir, which gradually increases as the liquid is injected. After 500 m ^{3 of} gas condensate enters the tank, atmospheric air is completely displaced from the tank. After that, the exhaust valve of the tank can be closed, then in the tank to create excess pressure of the exhaust air containing up to 90% nitrogen and about 5% oxygen.

нм³ газов. Из жидкой фазы выделяется 720 нм³ газов. Всего в резервуаре находится 600+720=1320 нм³ газов под небольшим избыточным давлением 1320/1000-1=0,32 атмосфер.3.2. In a tank with a volume of 1000 m ³ there is 900 m ^{3 of} gas condensate, 100 m ^{3 of} a gas-vapor mixture containing 90% nitrogen, ~ 5% oxygen and ~ 5% hydrocarbons, under a pressure of 0.6 MPa. The amount of dissolved gases in the gas condensate at 40 ^o C and 0.6 MPa (P _excess. = 5 kgf / cm ² ) is equal to 0.8 nm ³ in one m ^{3 of} condensate (see figure 1). Total dissolved gas 0.8 • 900 = 720 nm ³ . When pumping oil from the reservoir, the volume of liquid in it decreases, and the gas phase increases, and the pressure drops. When the tank is freed from gas condensate, the volume of the gas phase reaches 1000 m ³ ; from 100 m ^{3 of} gas under pressure of 0.6 MPa is formed

nm ³ gases. 720 nm ³ gases are released from the liquid phase. In total, the tank contains 600 + 720 = 1320 nm ³ gases under a slight overpressure of 1320 / 1000-1 = 0.32 atmospheres.

 When this tank is filled with a new batch of gas condensate, the existing gas phase is compressed, in addition, an additional amount of dissolved gas (nitrogen) is released from the gas condensate. Therefore, some of the gases must be released from the tank.

Claims (6)

1. A method of storing hydrogen sulfide and / or mercaptan-containing oil, oil products and gas condensate in a tank, comprising filling, storing under an inert gas atmosphere and emptying from hydrocarbon raw materials, characterized in that before filling in hydrogen sulfide and / or mercaptan-containing oil or oil products, or gas condensate is injected with compressed air at a pressure of 0.3-3.0 MPa in the presence of a catalyst at a rate of 0.06-0.12 nm ³ per 1 mol of hydrogen sulfide or 2 moles of mercaptans C ₁ -C ₃ , after which exposure is carried out for 5-180 min at tamper round 10-65 ^o C, and the filling is carried out at a pressure of 0.1-0.6 MPa in the vessel followed by formation of a nitric atmosphere above a stored feedstock. 2. The method according to p. 1, characterized in that the catalyst used is a water-alkaline solution of cobalt phthalocyanine; cobalt disulfo-, tetrasulfo-, dichlorodioxidisulfo- and polyphthalocyanines are used, and the catalyst solution is introduced into the hydrocarbon feed at the rate of 0.02-0.2 g of phthalocyanine per 1 mol of hydrogen sulfide or 2 moles of mercaptans C ₁ -C ₃ . 3. The method according to one of paragraphs. 1 and 2, characterized in that for the preparation of an aqueous-alkaline solution of a phthalocyanine catalyst using 1-25 wt. % solutions of caustic soda, sodium carbonate, sodium sulfide and ammonia, or 5-35 wt. % solutions of alkanolamines, and the aqueous-alkaline solution of the catalyst is introduced into the hydrocarbon feed at the rate of 0.1-1.6 moles of alkaline agent per 1 mol of hydrogen sulfide or 2 moles of mercaptans C ₁ -C ₃ . 4. The method according to p. 1, characterized in that as a catalyst use 5-95 wt. % solutions of alkanolamines: monoethanolamine, triethanolamine and methanolethanolamines, and solutions in the feed are introduced at the rate of 0.5-5.0 moles of alkanolamine per 1 mol of hydrogen sulfide or 2 moles of mercaptans C ₁ -C ₃ .  5. The method according to p. 1, characterized in that they use a heterogeneous catalyst containing phthalocyanines of cobalt and / or salts of copper, cobalt, iron, nickel and manganese deposited on a polymer-based carrier, or on activated carbon, or on carbon fiber the cloth.  6. The method according to p. 1, characterized in that when filling the tank maintain a pressure of 0.15-1.0 MPa, when emptying the tank from hydrocarbons, the pressure is reduced to 0.1 MPa.

Images