SU1699547A1 - Absorbing liquid for cleaning gases of hydrogen sulfide - Google Patents

Abstract

The invention relates to the absorption purification of gases from hydrogen sulfide and may find application in the gas and oil refining industry. The purpose of the invention is to reduce the corrosion activity of the absorbent, while maintaining its sorption properties at a high level. Absorbent for gas purification from hydrogen sulphide includes ethanolamine, tertiary aminonitrile and water, as a tertiary aminonitrile it contains N-dimethylaminopropionitrile in the following ratio of components, in May.%: Ethanolamine 5-35; N-dimethylaminopropionitrile J-2; water - the rest. 2 tab.

Description

 The invention relates to the absorption purification of gases from hydrogen sulfide and may find application in the gas and oil refining industry.

A absorbent is known for purifying gases from hydrogen sulfide, which is an aqueous solution of ethanolamine (20% by weight), diethylene glycol (1-2% by weight) and higher pyridine base (0.05-0.08% by weight).

A disadvantage of the known absorbent is its high corrosivity due to the insufficiently high inhibiting ability of the used corrosion inhibitor - pyridine base, especially at elevated temperatures (120-125 ° C).

The closest to the invention in technical essence and the achieved result is an absorbent for

purification of gases from hydrogen sulfide containing alkanolamine, tertiary aminonitrile and water in the following ratio, wt.%:

Alkanolamine 5.0-35.0 Tertiary aminonitrile0,003-0.09 Water Else In this case, a mixture of diheptyl-, dioctyl- and donylaminopropionitriles is used as a tertiary aminonitrile, which is produced as a corrosion inhibitor.

The main disadvantage of this absorbent is its relatively high corrosivity with respect to carbon steels, especially at high saturation levels of the absorbent with hydrogen sulfide and elevated temperatures. At 125 ° C and degree

about co Stock 1

the hydrogen sulfide saturation of 0.8 mol / mol; the corrosion rate of the steel VST3 sp reaches 0.22–0.33 mm / year.

The aim of the invention is to reduce the% corrosion activity of the absorbent.

y This goal is achieved by the fact that the absorbent for purifying gases from hydrogen sulfide, including ethanolamine, tertiary aminonitrile, and water, contains M-dimethylaminopropionitrile (DMPN) as a tertiary aminonitrile in the following ratio of components, May. 7 ,:

Ethanolamine 5-35

DMPN1-2

WaterEverything

The use of DG1PN concentration of 1-2 wt.% In the composition of absorbents based on aqueous solutions of alkanolamines i with the technical function of a corrosion inhibitor in an alkaline sulfide-containing medium (the medium can significantly reduce i corrosion activity of the used absorbent at high TeMnepaTypak and degrees of saturation with hydrogen sulfide and significantly reduce the degree of corrosion of equipment desulfurization plants.

Used in the proposed DMPN sorbent of the formula (CH3) K-CH2-CH2 - CN is a colorless or slightly yellowish mobile liquid with a density of 870 kg / m1, boiling point of 173 ° C and freezing point of minus 50 ° C, well soluble in water and aqueous solutions of alkanolamines, the MPC in the air of the working area of 10 mg / m3.

The proposed ratio of the components of the absorbent is optimal, since when the concentration of DMPN in the absorbent is less than 1.0 wt.%, The essential required decrease in the corrosivity of the absorbent is not achieved, and an increase in its concentration (more than 2.0 wt.%) Practically does not lead to further a significant reduction in the corrosivity of the absorbent and leads to its appreciation, i.e. economically impractical.

Example 1. Absorbent is prepared by dissolving the components in water. 150 g of monoethanolamine (MEA) is added to 835 g of distilled water with stirring, and then 15 g of DMPN are dissolved. Cooked like this

five

five

0

O

five

0

45

50

55

once absorbent contains, wt% of MEA 15; DMPN 1.5; water the rest.

Example 2. In order to determine the corrosion activity of an absorbent by a gravimetric method, according to RTM 26-01-21-68, the corrosion rate of carbon steel VStsp in the medium of the absorbent saturated with hydrogen sulfide to 0.8 mol / mol at 125 ° C and the duration of the sample exposure was measured at 125 ° C. 100 hours

The compositions of the tested absorbents and the averaged results of determining the corrosion rate in the environment of the proposed and known (compounds 5-7) absorbent.

Example 3. In order to determine the sorption property of the proposed absorbent, gas is cleaned from hydrogen sulfide in a laboratory setup with a 650 mm high glass absorber with a diameter of 20 mm. Raschig glass rings 5x5x1 mm in size are used as nozzles. 80 ml of absorbent are loaded into the absorber and, at atmospheric pressure and at room temperature (), are passed from a gasometer with a volumetric rate of 90 h 4 nitrogen, containing hydrogen sulfide. The purified gas after the absorber is analyzed for hydrogen sulfide content by potentiometric titration.

The results of gas purification from hydrogen sulfide under the described conditions with the use of a known absorbent (compounds 4, 5) and proposed are given in table. 2

From the table. 1 and 2 of the data shows that the absorbent of the proposed composition in comparison with the known has a significantly lower corrosivity while maintaining the sorption capacity with respect to hydrogen sulfide at a high level. When using the absorbent of the proposed composition, the corrosion rate of steel decreases 8-times in the liquid phase and 3-5 times in the vapor-gas phase, which makes it possible to extend the service life of the equipment for the installation of gas cleaning from hydrogen sulfide.

Form u.la and inventions

Absorbent for gas purification from hydrogen sulphide, including ethanolamine, tertiary aminonitrile and water, is characterized by the fact that, in order to reduce its corrosivity, it contains N-dimethylaminopropionitrile as a tertiary aminonitrile, with the following ratio of components, wt.%:

Ethanolamine 5-35

N-Dime tilamine opro-pionitrile1-2

WaterEverything

Table 1

1 2 3 4 5

6- 7 8 9 10

steel

and n and m if

tl

||

It

0.042

0.033

0.030

0.026

0.335

0.303,

0.261

0.195

0.080

0.025

0.076

0.071

0.068

0.063

0.328

0.270

0.225

0,213

0.103

0.062

table 2

Claims (1)

Claim An absorbent for the purification of gases from hydrogen sulfide, including ethanolamine, tertiary aminonitrile and water, which is deprived of the fact that, in order to reduce its corrosive activity, it contains N-dimethylaminopropionitrile in the following ratio of components, wt.%: Ethanolamine 5- 35 N-Dimethylaminopropionitrile 1-2 Water Else Table 1 Absorbent composition The content of components, wt.% IEA DIPP Tertiary aminonitrile Water Corrosion rate, mm / year. liquid phase vapor phase 1 15.0 1, θ - Rest 0,042 0,076 2 15.0 1,5 - \ -. ⁿ - 0,033 0,071 3 15.0 1.8 - 0,030 0,068 4 15.0 2.0 - 0,026 0,063 5 15.0 - 0.01 - 0.335 0.328 6 15.0 -. 0,03 0,303.- 0.270 7 15.0 - 0.09 0.261 0.225 8 15.0 0.09 - 0.195 0.213 9 15.0 0.5 . - - ⁿ - 0,080 0.103 10 15.0 3.0 - 0,025 0,062 table 2 Composition Content Comp wt.% Hydrogen sulfide rate Power absorptive ——— ’----— in gas ^ vol.% cleaning benta IEA dmpn Tertiary Water | gas% aminonitrile before cleaning 1 after cleaning 1 20,0 1,0 - Rest 18 0.02 99.9 2 20,0 1,5 - - 18 0.02 99.9 3 20,0 2.0 - 18 0.02 99.9 4 20,0 0.01 18 0.02 99.9 5 20,0 - 0.09 18 0.02 99.9