RU2585333C1 - Method for preparation of associated petroleum gas - Google Patents

Abstract

FIELD: gas industry.

SUBSTANCE: invention relates to method of preparing hydrocarbon gas by low-temperature condensation and can be used in gas industry. Method for preparation of associated oil gas involves separation and successive cooling gas prepared gas and third-party coolant with condensation of reflux, countercurrent contact between gas and condensate after each cooling stage. Gas is premixed with weathering gas, compressed to transportation or processing to produce cooled liquid hydrocarbons and mixed with stabilization gas. Cooling of obtained mixture is carried out in conditions of its partial condensation, besides, condensate is stabilized with receipt of stabilization gas, reduced and separated with production of weathering gas and stabilized.

EFFECT: invention increases output of treated gas, improving quality of condensate and preparation of associated petroleum gas of low pressure.

1 cl, 1 dwg

Description

The invention relates to methods for the preparation of hydrocarbon gases by low-temperature condensation and can be used for the preparation of associated petroleum gas in the oil and gas industry.

A known method for the preparation of hydrocarbon gas [RU 2202079, publ. 04/10/2003, IPC F25J 3/00], which includes step-by-step separation with intermediate gas cooling, separation of hydrocarbon condensate from the initial stages of separation, its cooling with low-temperature separation condensate and mixing with gas as an absorbent, as well as cooling with external refrigerant, reduction and low-temperature separation of the resulting mixture.

The disadvantages of this method are losses with condensate of light hydrocarbons and low quality of the condensate due to the high pressure of its vapor.

Closest to the technical nature of the proposed invention, the method of preparation of hydrocarbon gas [RU 2460759, publ. September 10, 2012, IPC C10G 5/06, C10G 5/04, C07C 7/00, C07C 7/11, F25J 3/00, F25J 3/08], which consists in low-temperature gas separation and includes separation carried out in one apparatus and sequential cooling of the gas with the prepared gas and external refrigerant with condensation of the liquid phase (reflux) and contacting the gas and reflux in countercurrent after each cooling stage. When preparing wet gas, it is preliminarily dried by hydrate inhibitors or moisture sorbents.

The disadvantages of this method are the low yield of the prepared gas due to losses of light gas components with hydrocarbon condensate and the low quality of the condensate due to the high pressure of its vapor. In addition, the method cannot be used for the preparation of associated petroleum gas and requires its preliminary compression.

The objective of the invention is to increase the yield of prepared gas, improving the quality of the condensate and the preparation of associated petroleum gas of low pressure.

When implementing the proposed method as a technical result is achieved:

- increasing the yield of prepared gas and improving the quality of the condensate due to the recirculation of light gas components extracted from the condensate during its stabilization and weathering, as well as by increasing the efficiency of fractionation by cooling the gas under reflux,

- Preparation of associated low-pressure petroleum gas by compressing its mixture with weathering gas to the pressure of transportation or processing.

The specified technical result is achieved by the fact that in the known method, including the separation and sequential cooling of the gas with the prepared gas and external refrigerant with condensation of reflux, countercurrent contacting of the gas and reflux after each cooling stage, the feature is that the gas is pre-mixed with the weathering gas, compressed to transportation or processing pressure to obtain a cooled compress and mixed with stabilization gas, while cooling the resulting mixture is carried out in conditions of its reflux, in addition, the condensate is stabilized to produce a stabilization gas, reduced and separated to obtain a weathering gas and stabilized condensate.

To prevent hydrate formation, it is advisable to apply a hydrate inhibitor or moisture absorbent to one of the cooling or contacting stages, which is then removed for regeneration. The place of supply and flow rate of the hydration inhibitor or moisture absorbent is determined by calculation depending on the temperature and pressure conditions of preparation and gas composition.

Stabilization is carried out by one of the known methods, for example, by distillation of light components in a heated film stabilizer, and reflux, for example, by condensation of reflux in gas cooling units equipped with heat and mass transfer elements with a large vertical size of the outer surfaces.

Cooling the gas mixture under reflux provides fractionation of the reflux film enriched in light components in contact with a gas enriched in heavy components and moving countercurrent, which helps to reduce the content of heavy components in the product gas and lower its dew point temperature.

Stabilization of the condensate to produce a stabilization gas, its subsequent reduction and separation to produce a weathering gas make it possible to reduce the content of light components in the condensate, return them to marketable gas by recirculating stabilization and weathering gases, thereby increasing the yield of prepared gas and improving the quality of the condensate.

According to the proposed method (see drawing), raw gas 1 is mixed with weathering gas 2, compressed in a compressor station 3, the cooled compress is mixed with stabilization gas 4, separated in the separation zone 5 of the reflux condenser 6 into water condensate 7, hydrocarbon condensate 8 and gas, which passes through section 9, where it is in contact with reflux flowing from the reflux section 10, and section 10, where it is cooled by the prepared gas 11 under reflux conditions. Next, the gas passes through the contact section 12, where it is in contact with reflux flowing from the reflux section 13, section 13, where it is cooled under reflux by external refrigerant 14 and then heated in the reflux section 10 and brought to the consumer. A hydrate inhibitor or moisture absorbent 15 may be supplied to the reflux condenser 6 (indicated by a dotted line). The hydrocarbon condensate 8 is stabilized, for example, in a heated film stabilizer 16 to produce stabilization gas 4 and condensate 17, which are reduced and separated in the device 18 to produce weathering gas 2 and stabilized condensate 19.

When implementing the proposed method 12.5 thousand nm ³ / hour of gas composition,% vol .: nitrogen 1.2; carbon dioxide 3.3; methane 49.0; ethane 12.9; propane 17.1; butane 11.0; pentane 3.1; hexane 1.3; heptane 0.5; octane 0.1; methanol 0.2; water - the rest, at 20 ° C and 0.6 MPa is mixed with the weathering gas, compressed, the cooled compress at 35 ° C and 3.5 MPa are mixed with stabilization gas, separated and subjected to two-stage reflux by cooling with the prepared gas and refrigerant, at countercurrent contacting of the gas and the resulting reflux after each stage of reflux to produce hydrocarbon condensate and 7.92 thousand nm ³ / h of prepared gas with a water dew point temperature of -20.1 ° С and hydrocarbons -10.1 ° С, meeting the requirements STO Gazprom 089-2010. At the same time, 4.6 kg / h of methanol with a concentration of 90% of the mass is fed to the first stage of reflux. The hydrocarbon condensate is stabilized in a film stripping column to obtain 728 nm ³ / h of stabilization gas and condensate, which is reduced to 0.6 MPa and separated to obtain 1729 nm ³ / h of weathering gas and 7.03 t / h of stabilized condensate containing 2, 98% of the mass. C ₁ + C ₂ , which meets the requirements of TU 38.101524-93 for a wide fraction of light hydrocarbons of grade "A" (not more than 3% by weight).

In similar conditions, according to the prototype received 7.43 thousand nm ³ / hour of gas that meets the requirements of the norms, and condensate containing 13.3% of the mass. C ₁ + C ₂ not complying with regulatory requirements.

The above example indicates that the proposed method allows the preparation of associated petroleum gas of low pressure, increase the yield of the prepared gas and improve the quality of the condensate.

Claims (2)

1. A method of preparing associated petroleum gas, including the separation and sequential cooling of the gas with prepared gas and a third-party refrigerant with condensation of reflux, countercurrent contacting of gas and reflux after each cooling stage, characterized in that the gas is pre-mixed with weathering gas, compressed to the pressure of transportation or processing to obtain a cooled compress and mixed with stabilization gas, while cooling the resulting mixture is carried out under conditions of reflux, in addition, the condensate is stabilized to produce a stabilization gas, reduced and separated to obtain a weathering gas and stabilized condensate. 2. The method according to p. 1, characterized in that at one of the stages of cooling or contacting the gas serves a hydration inhibitor or moisture absorbent, which is then removed for regeneration.

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