SU1350447A1 - Method of preparing hydrocarbon gas for transportation - Google Patents

Abstract

The invention relates to pipeline transport, intended for use in the gas and oil industries. The purpose of the invention is to increase efficiency by reducing the consumption of volatile hydrate formation inhibitor (IG). The method includes a step separation, cooling of a hydrocarbon gas (UG) between the separation steps, the introduction of a water-soluble volatile IG into the UG stream, the removal of liquid from the separators and its separation into hydrocarbon and aqueous phases. The aqueous phase, which is an aqueous solution of IG, is fed into the flow of UG directed to one of the previous stages of separation. The method allows to reduce the consumption of fresh and the cost of regeneration of flooded IG. sl sl about 4 vl

Description

The invention relates to the field of preparation for the transportation of hydrocarbon gas, for example, natural or associated petroleum gas, and can be used in the gas and oil industry.

The purpose of the invention is to increase the efficiency of the method by reducing the consumption of the inhibitor.

The drawing shows the installation scheme j, which implements the proposed method

As an inhibitor of hydratoob10

gas phase from water and condensate. The gas is further directed to the second separation stage and a regenerative heat exchanger 2 passes, where it is cooled due to heat exchange with cold separated gas (directed to the main gas pipeline), and enters separator 3. The gas flow coming from the second separation stage and entering the low-temperature stage, an inhibitor of hydrogenation is introduced (highly concentrated methanol, ethanol,

use of volatile water-15 acetone and others). The injection site of the inhibitor soluble organic matter jHan- is determined on the basis of the thermodynamics methanol, ethanol, acetone, the hydrate forming ether conditions, the aldehyde fraction (a by-product of the production of synthetic materials which are realized in this case in the heat exchanger 4 and the separator 5.

ethylene ethylene), etc.

The organization of the process involves the supply of an aqueous solution of the inhibitor to 1 az. In this case, volatilization from this solution

inhibitor and partial gas dosing. This reduces the flow rate of the fresh inhibitor introduced far into the gas. At the same time, its concentration in the aqueous phase decreases in individual cases to a value, at which it is economically inexpedient to regenerate, and its discharge into the formation is admissible.

Consequently, the method involves cyclic (multiple) use of a volatile hydrate formation inhibitor in the gas preparation system due to its evaporation from the liquid phase into the gas stream at the first stages of separation and condensation at subsequent stages. At the same time, the physicochemical features of the solubility of volatile organic matter in a compressed priron gas are effectively used: the temperature dependence and the increase in solubility with increasing pressure are strong (at P 5–7 MPa).

The need to supply a fresh inhibitor is associated with the compensation of its entrainment with gas (entering the gas pipeline), condensate and water (entering the effluent system).

The method is carried out as follows.

Hydrocarbon gas with a temperature of 15-45 ° C and a pressure of 9.0-13 MPa enters the first stage in the separator 1, where the separation takes place

gas phase from water and condensate. The gas is further directed to the second separation stage and a regenerative heat exchanger 2 passes, where it is cooled due to heat exchange with cold separated gas (directed to the main gas pipeline), and enters separator 3. The gas flow coming from the second separation stage and entering the low-temperature stage, an inhibitor of hydrogenation is introduced (highly concentrated methanol, ethanol,

acetone and others). The injection site of the inhibitor is determined on the basis of the thermodynamic conditions of hydrate formation,

which are implemented in this case in the heat exchanger 4 and the separator 5.

In the third (low-temperature) separation stage, the gas is cooled in the heat exchanger 4, throttled at the nozzle 6 and enters the separator 5. Thermodynamic conditions 5

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5 catch it

in the separator: temperature 30–20 ° C, pressure 7–8 MPa. The separated and cooled dry gas through heat exchangers 4 and 2 is directed to the gas pipeline, and the hydrocarbon liquid from the separator 5 goes to the condensate line.

The separated aqueous phase, which is a fairly concentrated inhibitor solution (50–80% aqueous solution), is fed into the gas stream before the heat exchanger 2. If hydrate formation is thermodynamically possible at earlier stages of separation, then the inhibitor solution is also fed to them.

A more dilute aqueous solution of the inhibitor (concentration of 10-30%, depending on the specific conditions), separated in the separator 3 of the second stage, serves 3 separator 1.

To improve the stripping process and more fully saturate the gas phase with an inhibitor, it is advisable to retrofit the upper part of the separator 1 with disc devices or install a section with a nozzle (for example, from Rashig rings) where the aqueous solution of the inhibitor from the separator 2 is fed. separator 1, where the concentration of the inhibitor is further reduced due to the displacement from the vapor separated from the gas.

five

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five

As a variant of the proposed method, it is possible to supply an aqueous solution of the inhibitor from the nickel-temperature separator 5 directly to the separator 1 of the first stage.

An example is Natural gas, consisting mainly of methane and containing up to 7 mol.% C, is undergoing field preparation according to the known and proposed methods.

The parameters of the gas treatment installation are as follows: In separator 1: P 12 MPa, t in separator 3: P 12 Sha, t, c. low-temperature separator 5: P 8 MPa, t.

.In the thermodynamic parameters of the installation, hydrate formation can take place only in the area after the heat exchanger 4.

Taking into account the composition and temperature of the gas, the concentration of methanol in the aqueous solution to prevent hydrate formation in this area should be at least 55% by weight. To ensure a reliable hydrate-free operation, 1.48 kg of methanol per 1000 m of gas is introduced into the gas in front of the heat exchanger 4 ( the concentration of meganol 96 wt.%), which provides the concentration of spent methanol in the separator 5 to 60 wt.%. A solution of this concentration (by a known method) is burned without the presence at the present time of the installation of methanol regeneration.

According to the proposed method, the entire water methanol solution from separator 5 is introduced into the gas stream before the heat exchanger 3. Methanol from the liquid phase is partially transferred to the gas phase, and upon leaving the separator 3

five

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its content in the gas is 0.79 kg / SCHO m3.

In the separator 3, the liquid aqueous phase is separated with a methanol concentration of 11 wt.% And introduced into the upper part of the separator 1, equipped with a section with a nozzle made of Raschig rings. The height of the nozzle layer is 1.2 m. The concentration of methanol in a solid solution after passing the nozzle is 0.1% by weight. The concentration of methanol in the aqueous solution in the lower part of the separator (after mixing with the water released in the separator) is less than 0.03 wt.%.

As in the known process, fresh methanol is required in front of the heat exchanger 4.

The consumption of methanol in the proposed method decreases and is

1.48-0.79 "0.7 kg / 1000m1 where 0.79 kg / 1000 m is the amount of methanol supplied with gas from separator 3,

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Claims (1)

Invention Formula Spo (about preparing hydrocarbon gas for transportation, including step separation, cooling the gas flow between the separation steps, introducing a water-soluble volatile organic hydrate inhibitor into the gas flow, removing liquid from the separators, separating it into a hydrocarbon and aqueous phase, differing in that, in order to increase efficiency, by reducing the consumption of a hydrate inhibitor, the separated aqueous phase is directed to the gas flow entering one of the previous stages of separation. Condensate Fit g} a5Q