RU2564276C1 - Method of methanol extraction from mineralised water solution - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method includes rectification of the heated mineralised water-methanol solution in the rectification column, to which the water-methanol pairs with high methanol are supplied, the methanol and steam of the water-methanol solution with low methanol content. From top of the rectification column the methanol vapours are removed, they are cooled, condensed and separated to two parts, one part returns to the main column as live reflux, and balance part is removed as commercial methanol. From bottom of the rectification column the water-salt solution is removed, and from the chimney tray located above the point for mineralised water-methanol solution supply the demineralised water-methanol solution is removed, it is mixed with water and is separated in the stripping column, to its bottom vapours of the water-methanol solution with low methanol content is supplied as vapour reflux, from the top the water-methanol vapours with high methanol content are removed, and from bottom - the water-methanol solution with low methanol content, the later is evaporated and directed as the vapour reflux to the fractionating and stripping columns.

EFFECT: invention simplifies the method due to assurance of the process continuity.

2 cl, 1 dwg

Description

The invention relates to methanol recovery processes and can be used in the oil and gas industry.

A known method of regeneration of methanol from a water-methanol solution [RU 2465949, publ. November 10, 2012, IPC B01D 53/00], including the degassing of a water-methanol solution, separation of free condensate, settling at 20-40 ° С until the fine condensate emulsion is destroyed and mechanical impurities are precipitated, the water-methanol solution is heated by fire and methanol is separated in a distillation column.

The disadvantage of this method is the deposition of salts and solids on heating surfaces and internal devices of technological devices, which reduces the yield of regenerated methanol, impairs heat transfer and entails the need for periodic cleaning of equipment from scaling.

The closest in technical essence to the claimed method is a method of regeneration of methanol from a mineralized aqueous solution [RU 2159664, publ. November 27, 2000, IPC B01D 53/26], which prevents the deposition of salts and solids on heating surfaces and in the fractionation column, and includes the evaporation of a preheated mineralized water-methanol solution to obtain a salt concentrate, salt residue (sludge) and water-methanol vapor rectification of the latter in a fractionating column with acute irrigation to obtain methanol and water, and evaporation is carried out by mixing a pre-heated water-methanol solution with heated recirculation liruemoy part of water-methanol vapor and brine concentrate, wherein the basic water-methanol vapor portion is cooled and fed to the fractionation. Periodically, the process is stopped and the saline slurry is removed.

The disadvantage of this method is its complexity associated with a multi-stage process and the use of a large number of equipment (15 units), as well as the frequency of the process.

The objective of the invention is to simplify the method.

The technical result is to simplify the method by ensuring the continuity of the process, reducing the number of process steps and equipment used by eliminating the formation of salt sludge and periodic stages of its removal.

The specified technical result is achieved by the fact that in the known method, including rectification of water-methanol vapors in a fractionating column with acute irrigation to produce methanol, the feature is that a heated mineralized water-methanol solution is additionally supplied to the middle part of the column, and a demineralized water-methanol solution is withdrawn from the column above the input point of the latter a solution, above the outlet point of which water-methanol vapors with a high methanol content are introduced, while the first stream is fed to the bottom of the column the vapors of a methanol solution with a low methanol content, and water-salt solution is removed from the bottom of the column, then the demineralized water-methanol solution is mixed with water and fractionated in a stripping column, to the bottom of which a second stream of vapors of a methanol solution with a low methanol content is fed, from the top water-methanol pairs are removed with a high methanol content, and from the bottom a water-methanol solution with a low methanol content is removed, which is evaporated, and the vapors are divided into two streams.

It is advisable to heat a mineralized water-methanol solution in order to prevent the formation of scaling to a temperature not exceeding the temperature of its aggregate stability.

The withdrawal of the demineralized water-methanol solution from the column above the point of entry of the mineralized water-methanol solution eliminates the contact of the saline media with heating surfaces, which prevents the deposition of salts on the latter and ensures the continuity of the process.

Separation of a demineralized water-methanol solution in a stripping column makes it possible to obtain water-methanol vapors with a high methanol content and a water-methanol solution with a low methanol content, by evaporation of which vapors are obtained which are used as steam irrigation of columns.

Pre-mixing the demineralized water-methanol solution with water provides the required steam irrigation flow rate, and also helps to reduce the concentration of saline solution, which prevents the deposition of salts in the fractionation column.

The method is as follows (see drawing). After preliminary purification from hydrocarbon condensate and mechanical impurities and heating (not shown in the diagram), a mineralized water-methanol solution (I) is fed into the middle part of fractionation column 1, a demineralized water-methanol solution (II) is discharged from the column above its entry point, and between the outlet points of the latter and introducing acute irrigation (III) water-methanol vapors with a high content of methanol (IV) are introduced, the first stream of vapors of a water-methanol solution with a low content of methanol (V) is fed to the bottom of column 1, and from the bottom t of water-salt solution (VI). The demineralized water-methanol solution (II) is mixed with water (VII) and fractionated in a stripping column 2, to the bottom of which a second stream of vapors of a water-methanol solution with a low content of methanol (VIII) is fed, water-methanol vapors with a high content of methanol (IV) are removed from the top, and from the bottom, a water-methanol solution with a low content of methanol (IX) is removed, which is evaporated, for example, using a riboiler 3 and separated into streams (V) and (VIII). Methanol vapors (X) are removed from the top of column 1, cooled and condensed, for example, in a refrigerator-condenser 4, separated, for example, in a capacitive separator 5, exhaust (XI) is removed, and the condensed methanol is divided into two parts, one of which ( III) returned to column 1 as acute irrigation, and the other (XII) is withdrawn as commercial methanol.

The efficiency of the proposed method is illustrated by the following example. 1.0 t / h of a mineralized water-methanol solution containing 60 wt.% Methanol and 35 g / l of salts heated to 62 ° C is subjected to rectification in a fractionation column, which also serves 3.2 t / h of high methanol water vapor methanol content, 6.2 t / h of methanol as acute irrigation and 1.35 t / h of water vapor methanol solution with a low methanol content as steam irrigation. Methanol vapors are removed from the top of the fractionation column, which are cooled, condensed and divided into two parts, one of which is returned to the main column as acute irrigation, and 0.61 t / h of the balance part is removed as commodity methanol with a concentration of 96 wt.% From the bottom of the fractionation column, 0.82 t / h of a water-salt solution containing 1 wt.%, Methanol and 43 g / l of salts are taken and removed from the installation, and 4 are removed from the half-deaf plate located above the point of entry of the saline water-methanol solution. 2 t / h demineralized water methanol solution, which is mixed with 0.46 t / h of water and separated in a stripping column, at the bottom of which 2.5 t / h of vapors of a water methanol solution with a low methanol content are supplied as steam irrigation, from the top of which water-methanol vapors with a high methanol content, and from the bottom - 3.85 t / h of a methanol-low water methanol solution, which is evaporated and sent as steam irrigation to fractionation and stripping columns. The process is carried out continuously using 5 pieces of equipment.

Thus, the present invention allows to simplify the process of separation of methanol from a mineralized aqueous solution and can find application in the oil and gas industry.

Claims (2)

1. The method of separation of methanol from a mineralized aqueous solution, including the distillation of water-methanol vapors in a fractionating column with acute irrigation to produce methanol, characterized in that the heated mineralized water-methanol solution is additionally fed into the middle part of the column, and a demineralized water-methanol solution is withdrawn from the column above the entry point of the latter, above the outlet point of which water-methanol vapors with a high methanol content are introduced, while the first stream of water-jet vapor is fed to the bottom of the column of a solution with a low methanol content, and water-salt solution is removed from the bottom of the column, then the demineralized water-methanol solution is mixed with water and fractionated in a stripping column, into the bottom of which a second stream of vapors of a methanol solution with a low methanol content is fed, from the top water-methanol pairs are removed with high methanol content, and from the bottom a water-methanol solution with a low methanol content is removed, which is evaporated, and the vapor is divided into two streams. 2. The method according to p. 1, characterized in that the mineralized water-methanol solution is heated to a temperature not exceeding the temperature of its aggregate stability.

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