RU2482103C1 - Method for obtaining ethane from gas condensate under field conditions - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to gas industry and can be used at gas condensate fields, immediately at sites of gas preparation for transportation or at centralised sites of preparation of instable gas condensate for transportation or processing. The invention refers to the method of obtaining liquid ethane from instable gas condensate, which involves separation of gas condensate in a rectifying column into three flows, two gas ones - methane and ethane, and one liquid - deethanised condensate, ethane gas flow separation with a side shoulder of the rectifying column, which is located on the level of gaseous phase containing ethane free from methane, and further condensation of ethane flow and extraction of liquid ethane from condensed ethane flow.

EFFECT: enlarging the range of products, improving their quality and low-temperature properties.

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Description

The invention relates to the gas industry and can be used in gas condensate fields, directly at the facilities for preparing gas for transport or at centralized facilities for preparing unstable gas condensate for transport or processing. The invention is intended to produce ethane as an independent commercial product and improve the quality of methane gas.

The main component of natural gas produced in the fields is methane. Acceptable amounts of ethane are included in the composition of natural gas, worsening its quality (increasing the dew point of the gas). Valuable components of gas condensate are heavier hydrocarbons than ethane. Ethane contained in the condensate degrades the quality of the condensate (increases the pressure of saturated vapor). That is, ethane can be limitedly discharged into gas and very limitedly into condensate. In fields where only two products are produced (gas and condensate), and natural gas contains a significant amount of ethane, ethane cannot be used rationally. This is one of the main reasons for flaring ethane-containing gas. Moreover, ethane is a valuable raw material for gas chemistry, the demand for which over the past few years has exceeded its supply on the market. One way to solve this problem is to obtain an independent commercial product from ethane. This solution is characterized by high economic efficiency and is of great resource-saving importance.

A known method of field preparation of gas condensate fluid and deethanization of condensate (patent of the Russian Federation No. 2243815), which provides for the production of gas condensate during deethanization, increasing the process pressure of deethanization gas and returning the deethanization gas to the field.

The disadvantage of this method is the irrational use of ethane resources, the maximum output into commercial gas.

A known method of processing gas condensate in the field (patent of the Russian Federation No. 2118337), providing for the receipt in the distillation column of gases that include large amounts of liquid hydrocarbons.

The disadvantage of this method is the irrational use of ethane, discharged into gas and not produced as a commercial product.

A known method and device for the preparation and processing of hydrocarbon raw materials of gas condensate deposits (RF patent No. 21820350), comprising a deethanization column as part of the installation.

The disadvantage of this installation is the irrational use of ethane, discharged into gas and not produced as a commercial product.

The problem to which this invention is directed, is to obtain ethane in the form of a commercial product.

The technical result is to simplify and reduce the cost of the process of producing ethane under field conditions for the processing of gas condensate while improving the quality of the resulting gas and condensate.

The problem is achieved in that the method of producing liquid ethane from unstable gas condensate involves the separation of gas condensate in a distillation column into three streams, two gas condensates - methane and ethane, and one liquid - deethanized condensate, while the ethane gas stream is isolated by a side stream of the distillation column, which is located at the level of the gas phase containing ethane free of methane, subsequent condensation of the ethane stream, and the selection of liquid eth from the condensed ethane stream ana.

The method is carried out by supplying condensate to a distillation column, supplying heat to the bottom of the column, taking gas from the top of the column, and from the bottom of the condensate, in addition, a product containing the main resources of ethane is processed as a side stream from the middle of the column, which is processed separately column with ethane of the required purity.

Gas condensate is processed in a distillation column in which three products are produced: product No. 1 - gas containing all methane resources and some ethane, product No. 2 - gas containing the main resources of ethane, and product No. 3 - deethanized gas condensate. In this case, the withdrawal of product No. 1 from the column is carried out in its upper part, the withdrawal of product No. 2 from the column is carried out with a side shoulder strap from the middle part, and the withdrawal of product No. 3 is carried out from the bottom of the column. Separation of the outlet points for products Nos. 1, 2, and 3 makes it possible to remove all methane resources with product No. 1, the main ethane resources with product No. 2, and heavier hydrocarbons with product No. 3. The resulting product No. 2 is cooled and condensed at a temperature not lower than plus 20 ° C, which does not require the use of low-temperature refrigerants. Condensed product No. 2 is intended to produce ethane of the required purity, which is carried out in a separate column at high pressure (better than 3.6 ÷ 3.8 MPa). High pressure allows you to implement the process in the column and to condense the gas of the top of the column at a temperature of about 20 ° C, which does not require the use of low-temperature refrigerants.

The resulting ethane gas is discharged to the consumer (which may be a gas chemical plant that consumes ethane). If necessary, ethane gas condenses (at a temperature of 17 ÷ 18 ° C), which allows it to be delivered to the consumer by rail or ethane pipeline.

Due to the allocation of ethane as a separate product, the range of products is expanding. In addition, quality improves (methane content increases and low-temperature properties improve - dew point decreases) of product No. 1.

Example (% mass)

The hydrocarbon condensate obtained in the gas field with a content of 3.9% methane, 4.8% ethane with a flow rate of 100%, a temperature of 0 ° C (-10 ÷ + 10 ° C) and a pressure of 3.2 MPa (2.5 ÷ 3, 5 MPa) entered the deethanization column on one of the upper plates. The column produced product No. 1 - 5.6% methane gas with a methane content of about 70%, product No. 2 - 6.4% ethane-containing gas with an ethane content of about 60% and deethanized condensate with an ethane content of 0.3%. Product No. 2 condensed at a temperature of 24 ° C and was discharged into an ethane column. In an ethane column (at an operating pressure of 3.7 MPa (3.5 ÷ 4.0 MPa)), 3.9% of ethane gas containing 96.3% ethane is produced, and bottoms with an ethane content of not higher than 0.5%.

Claims (1)

A method of producing liquid ethane from an unstable gas condensate, which includes the separation of gas condensate in a distillation column into three streams, two gas condensates - methane and ethane, and one liquid - deethanized condensate, while the ethane gas stream is isolated by a side stream of the distillation column, which is located at the gas level a phase containing ethane free of methane, subsequent condensation of the ethane stream, and the selection of liquid ethane from the condensed ethane stream.