CC BY
34
ISSN 2522-1841 (Online) AZERBAIJAN CHEMICAL JOURNAL № 2 2022 107
ISSN 0005-2531 (Print)
UDC 620.193
INVESTIGATION OF ANTI-CORROSION PROPERTIES OF NEW
MULTIFUNCTIONAL REAGENTS AGAINST INTERNAL CORROSION
IN MAIN GAS PIPELINES
U.E.Hasanova
Oilgasscientificresearchproject Institute, SOCAR
Received 03.09.2021 Accepted 17.11.2021
Compositions of amide synthesized based on oleic acid and aminoethylethanolamine (AEEA) with cis-1-((4-(-(benzoyloxymethyl)-1,3-dioxolan-2-yl) methyl)-1H-benzo[d][1,2,3]triazol-1-ium acetate synthesized based on benzotriazole were prepared (Reag - A, B, C, D), and their properties against hydrogen sulfide and microbiological corrosion were studied in various concentrations. It has been determined that the ratio of the components contained in the Reag-C is optimum since the reagent completely kills bacteria and shows 95.2% inhibition efficiency against hydrogen sulfide corrosion.
Keywords: biocide, bacteria, corrosion inhibitor, benzotriazole, amide, composition, pipeline, oleic acid.
doi.org/10.32737/0005-2531-2022-2-107-112
Introduction
Microbiologically induced corrosion (MIC) is a corrosion type that is harmful to most engineering materials. Oil, gas and shipping industries are also seriously affected by MIC. MIC deteriorates the metal surface through the metabolic activity of microorganisms. Since the 19th century, scientists have been trying to explain the role of microorganisms in corrosion. The damage due to MIC is divided into a three-step process: the creation of biofilm, change of environment on the metal surface, and deterioration of the metal [1]. The common bacteria associated with MIC are sulfate-reducing bacteria (SRB), hydrocarbon-oxidizing bacteria (HOB) and iron-reducing bacteria (IRB) [2-4]. The most common forms of corrosion influenced by MIC are pitting corrosion, crevice corrosion, and stress corrosion cracking [5].
At each stage of oil processing starting from its exploitation, transportation, processing and ending with the storage, it can be subject to the action of microorganisms [6]. They use hydrocarbons contained in crude oil as a source of carbon and modify the properties of this material, thus reducing its value. It is extremely difficult to prevent microbiological contamination of oil because it is impossible to maintain sterile conditions during the extraction, transport and storage of crude oil [7]. An essential condition for the growth of microorganisms in oil, or in
products of crude oil refining is the presence of water in the production well, accumulation of water in the pipelines during transmission or at the bottom of the tanks during storage. Microbiological contamination of natural gas, crude oil and the products of crude oil refining represents a major problem in economic terms. Among the methods currently used for suppression of biodegradation of crude oil and petroleum products, the following can be distinguished:
• physical and mechanical methods,
• chemical methods [8].
The article focuses on the second group of these methods - chemical control of microbiological contamination of natural gas and petroleum - using chemical agents (biocides) and prevention of hydrogen sulfide corrosion of metal and metal alloys. The use of inhibitor-biocides is one of the most important methods for the protection of carbon steel against microbiological and hydrogen-sulfide corrosion. Of all inhibitors, the most important are the organic ones, also called adsorption inhibitors [9, 10]. Many organic compounds containing polar groups including nitrogen, sulphur and oxygen and heterocyclic compounds with polar functional groups and conjugated double bonds have been reported to inhibit corrosion of carbon steel in various aggressive environments [11, 12]. The inhibiting action of these organic compounds is usually attributed to their interactions
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with the metal surface by adsorption. The effect of some triazole derivatives has been reported earlier as corrosion inhibitors for steel, and they reveal that the inhibition efficiencies of these compounds are much better than those of the corresponding amines and aldehydes [13-19].
There are few reports about the successful use of benzatriazole and its derivatives as corrosion inhibitors for carbon steel in various environments and biocidal effects of some di-oxalan derivatives were determined [20]. In industry, it is very common to use more than one chemical compound to inhibit the corrosion process of a metal or alloy. When two or more corrosion inhibitors are added to a corrosive environment of a metal or an alloy, the inhibition efficiency of the mixture may be better than the efficiency of the individual additive. This is a synergistic effect [21].
This paper aims to indicate the inhibitor-biocidal effects of compositions prepared by amide synthesized based on oleic acid and ami-noethylethanolamine (AEEA) and sis-1-((4-(-(benzoyloxymethyl)-1,3-dioxolan-2-yl)methyl)-1H-benzo[d][1,2,3]triazol-1-ium acetate synthesized based on benzotriazole in different mass ratios.
Experimental part
The compositions were prepared in methanol in different mass ratios and their bactericidal-inhibitory properties were studied.
Gas and water condensate samples were taken from the outlet lines of the Hovsan GCP-Garadagh-North GRES" MGP to identify corrosive and aggressive components for testing. Chemical and microbiological analyses of these samples were performed as follows. The chemical composition of the gas samples was analyzed via Agilent 7890A chromatograph. The chromatograph determines the gas chemical composition in accordance with ISO 6974-4. The results of the analysis are given in Table 1.
The amount of hydrogen sulfide in the gas was analyzed in accordance with GOST 22387.2-97 as follows.
This method is based on the iodometric titration of the gas through cadmium chloride or cadmium acetate solutions. 50 cm of a solution of cadmium acetate with a mass fraction of 10%
is added to two glass vessels. Gas is sequentially passed through the containers and the volume is measured by a gasometer. The amount of gas passing through the solution is defined in accordance with the conditions given in the standard. At the end of the experiment, 10 cm3 of iodine solution is added to the gas-absorbing solution, titrated with sodium thiosulfate solution until the light yellow color is obtained, and after the addition of starch, the solution is titrated until the blue color disappears. The concentration of hydrogen sulfide in gas is calculated as follows:
X =
c 17(V - Vt) K~V7
V - the volume of sodium thiosulfate solution used for titration of control absorbing solution (control study), cm3; V1 - the volume of sodium thiosulfate solution used for titration of the gas-absorbing solution, cm3; C - concentration of sodium thiosulfate solution for titration, mol/dm3; 17 - the mass of hydrogen sulfide corresponding to 1 cm3 of sodium thiosulfate solution, mg; V2 -the volume of gas measured by the gas meter, dm3; K - the coefficient for calculating the volume of gas under standard conditions.
In addition, the moisture content of the gas samples taken for analysis was determined using a Condumax II transportable device. The results of the analysis conducted in accordance with the above-mentioned methodologies are given in Table 1.
Chemical analysis of the water separated from the gas in separators was performed in accordance with GOST 26449.1-85 (Table 2).
Determination of hydrogen sulfide in the water was carried out in accordance with the normative document OST 39-234-89 in the following order and the results obtained are given in Table 3.
To determine the amount of hydrogen sulfide, in approx. 20 ml of the distilled water, 1g KJ of and 1ml HCl (p=1.12g/cm3) are added to 250 ml conical flask and mixed. Titrated solution of 10 ml iodine and the appropriate amount of water to be analyzed is added.
Table 1. Analysis results of the gas taken from the outlet lines of "Hovsan GCP-Garadagh-North GRES" MGP
Chemical name Mol, % The maximum heat capacity, kJ/mol The minimum heat capacity, kJ/mol Note
N-Hexan 0.18 7.75 7.18 Average molecular
Propane 0.70 15.45 14.23 weight is 17.50,
I-Butane 0.27 7.74 7.14 density is 0.7290
N-Butane 0.25 7.23 6.68 kg/m3, upper limit
i-Pentane 0.16 5.73 5.30 of wobby number is 49.63 MC/m3, the
n- Pentane 0.08 2.71 2.51
Carbon dioxide 1.38 0.00 0.00 amount of H2S is 0.023 g/m3, the absolute humidity is 212.6 mg/m3, the dew point is 2.100C.
Ethane 2.66 41.53 38.01
Oxygen 0.01 0.00 0.00
Nitrogen 0.14 0.00 0.00
Methane 94.17 838.73 755.83
Total 100 926.87 836.89
Table 2. Results of chemical and microbiological analysis of a water-condensate mixture
Cations, g/l Anions, g/l Type of water Quantity of bacteria, cell/ml
Ca2+ Mg2+ Na++K+ Fe3+ Cl- SO42- HCO3- CO32- SRB KOB FeB
0.210 0.461 2.661 0.536 3.898 1.863 0.612 - NHK 105 10' 108
Note: density of water - 1.007 g/sm3, H2S - 2.06 g/l, pH - 7.3, total minerality - 10.234 g/l
Table 3. Influence of various bactericidal-inhibitory compositions on the rate of corrosion and bacterial growth at a
concentration of 100 mg/l in the water taken from the separator at "Hovsan GCP-Garadagh-North GRES" MGP
Name of composition Mass ratio Hidrogen sulfid corrosion The amount of bacteria, cell/ml
Metal loss, g Corrosion rate, g/m2-h Delay factor Protective effect, %
SRB FeB HOB
In the presence of inhibitor
- 0.0191 2.06 - - 105 107 108
In the absence of inhibitor
Reag-A 19:1 0.0015 0.173 11.9 91.3 104 103 104
Reag-B 18:2 0.0018 0.195 10.5 90.4 102 101 103
Reag-C 17:3 0.0021 0.233 8.8 88.6 10° 100 100
Reag-D 16:4 0.0022 0.269 7.6 86.9 10° 100 100
The amount of water to be taken for quantitative analysis and the normality of the iodine titrated solution are determined according to the relevant table in the standard. Excess of I is titrated with Na2S2O3 at the same concentration. When the color of the solution is straw-yellow, 1 ml of 0.5% aqueous solution of starch is added to the solution and titration is continued until the blue color disappears. The total amount of H2S and associations are calculated according to the following formula:
17040 (V1-K1-V2-K2)-N-Kr Vn
(2)
Vi - the volume of I added, ml; Ki - correction factor (to accurately express the concentration of I); V2 - volume of Na2S2O3, ml; K2 - correction
factor (to accurately express the concentration of Na2S2O3); N - normality of thiosulfate and iodine titrated solution; Vp - the volume of water analyzed, ml; Kr - when a preservative reagent (NaOH solution) is added, the coefficient is equal to 1.01.
NACE TMO194-2014 standard was used to determine the amount and type of bacteria in the water that affects the occurrence of microbiological corrosion (sulfate-reducing bacteria (SRB), hydrocarbon oxidizer (HOB) and iron bacteria (FeB)). The results of the analysis are given in Table 2.
Results and discussion
As can be seen from the analysis (Table 1), the amount of corrosive components in the gas samples is CO2-1.38%, O2-0.01/, H2S-
110 U.E.HA
0.023 g/m3. The
amount of bacteria and H2S in the water separated from the gas in the separators, as well as the rate of corrosion is high. This causes premature failure of the main gas pipeline and separators, as well as a major threat to the environment. It would be more effective to regularly use inhibitory bactericides in these pipelines. For this purpose, we prepared compositions of amide synthesized on the basis of oleic acid and ami-noethylethanolamine (AEEA) with sis-1-((4-(-(benzoyloxymethyl)-1,3-dioxolan-2-yl)methyl)-1H-benzo[d][1,2,3]triazol-1-ium acetate synthesized based on benzotriazole in different mass ratios (19:1, 18:2, 17:3, 16:4) and studied their inhibitory bactericidal properties (Table 3). Methanol was used as a solvent in the preparation of the compositions. This also plays an important role in preventing hydration in gas pipelines.
As can be seen from Table 3, the Reag-A composition has a high protective effect against hydrogen sulfide corrosion and a low efficiency
against microbial corrosion. In contrast, the Reag-D composition has lower protection efficiency against hydrogen sulfide corrosion and a higher protective efficiency against microbial corrosion. Reag-C is a composition prepared in more optimal proportions. Thus, this reagent destroys bacteria and has an 88.6% inhibition efficiency against hydrogen sulfide corrosion. The bactericidal-inhibitory effect of Reag-C at different concentrations was studied to determine the optimal consumption rate (Figure 1, Table 4).
The protective effect of Reag-C against hydrogen sulfide and various types of bacteria at a concentration of 25-175 mg/l was tested and the optimal consumption rate of the reagent was determined. The results are shown in Figure 1 and Table 4. The bactericidal and inhibitory properties of the reagent were studied in the water samples taken from the separator at Hovsan GCP-Garadagh-North GRES.
1 2 3 4 5 6 7
a Reagent concentratoin, mg/l u Protection efficiency, %
Fig. 1. Protection efficiency of Reag-C at different concentrations (corrosion rate in an inhibitor-free environment is 2.06 g/m2-h).
Table 4. Investigation of bactericidal properties at different concentrations of Reag-C
Name of the composition Name of bacteria The concentration of the reagent, mg/l
25 50 75 100 125 150 175
The amount of bacteria, cell/ml
Reag-C SRB 104 103 101 100 100 100 100
FeB 105 103 102 100 100 100 100
HOB 104 102 101 10° 100 100 100
As can be seen from the figure and table, the optimal consumption of this reagent is 150 mg/l. Thus, although the biocidal effect is high at low levels of this concentration, the protective effect against hydrogen sulfide corrosion is relatively low. At concentrations higher than the accepted optimal consumption rate, there is no significant change in the inhibitory and biocidal effects. It would be more effective to apply this bactericidal inhibitor against internal corrosion in the main gas pipelines. Thus, these inhibitors not only have a bactericidal inhibitory effect but also play an important role in preventing the formation of hydrates in gas pipelines.
Conclusion
The actual condition of the corrosion process and microbiological erosion were studied at Hovsan GCP-Garadagh-North GRES and it was determined that along with the increase of chemical aggression in the environment, the presence of microbiological aggression occurs due to microbiological infections. Synthesized Reag-C was found to have 100% biocidal effect against corrosive bacteria and 95.2% inhibition efficiency against H2S and CO2 corrosion in the optimal concentration of 150 mg/l in the water-condensate sample taken from MGP.
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MAGiSTRAL QAZ XOTTLORiNDO BORUDAXiLi KORROZiYANIN ARA§DIRILMASI VO KORROZiYA OLEYHiNO YENi COXFUNKSiYALI REAGENTiN TODQiQi
U.E.Hasanova
Olein tur§usu va aminoetiletanolamin (AEEA) asasinda sintez edilmi§ amidin benzotriazol asasinda sintez edilmi§ sis-1-((4-(-(benzoiloksimetil)-1,3-dioksolan-2-il)metil)-1H-benzo[d][1,2,3]triazol-1-ium asetatla kompozisiyalari hazirlanmi§ (Reag - A,B,C,D), muxtalif qatiliqlarda ham biosid ham da, hidrogen sulfid korroziyasina qar§i tasirlari oyranilmiijdir. Muayyan olunmu§dur ki, Reag-C daha optimal nisbatlarda hazirlanmi§ kompozisiyadir. Bela ki, bu reagent bakteriyalan tamamila mahv edir va hidrogen-sulfid korroziyasina qar§i isa 95.2 % muhafiza effekti gostarir.
Agar sozlar: biosid, bakteriya, korroziya inhibitoru ,benzotriazol, amid, kompazisiya,boru кэтэп, olein tur§usu.
ИССЛЕДОВАНИЕ АНИТИКОРРОЗИОННЫХ СВОЙСТВ НОВОГО ПОЛИФУНКЦИОНАЛЬНОГО РЕАГЕНТА ДЛЯ БОРЬБЫ С ВНУТРЕННЕЙ КОРРОЗИЕЙ МАГИСТРАЛЬНЫХ ГАЗОПРОВОДОВ
У.Э.Гасанова
Были получены композиции амида, синтезированного на основе олеиновой кислоты и аминоэтилэтаноламина (AEEA) с цис-1-((4-(-(бензоилоксиметил)-1,3-диоксолан-2-ил) метил)-1Н-бензо [d] [1,2,3] триазол-1-ия ацетат, синтезированного на основе бензотриазола (Reag - A, B, C, D), и изучены их свойства против сероводородной и микробиологической коррозии в различных концентрациях. Установлено, что соотношение компонентов в составе Reag-C оптимальное, так как реагент полностью уничтожает бактерии и проявляет 95.2% защитный эффект от сероводородной коррозии.
Ключевые слова: биоцид, бактерия, ингибитор коррозии, бензотриазол, амид, композиция, трубопровод, олеиновая кислота.
