12   A journal of the AMERICAN Journal of Engineering, Mechanics and Architecture                   www. grnjournal.us  

 
 

AMERICAN Journal of Engineering,  
Mechanics and Architecture 

Volume 01, Issue 10, 2023    ISSN (E): 2993-2637 

 
  

Assessment of the Effectiveness of Industrial Gas Purification with 

Diethanolamine 
 

Asadova Rano Dilmuratovna, Khikmatova Dildora Khumaydullaevna, 

Karimov Saydjon Salohiddin o’g’li, Bolibekova Shaxnoza Yarkulovna
 

Tashkent state technical University Named after Islam Karimov 

 

Abstract: The presented work is devoted to the efficiency of industrial purification of DEA from 

sulfur compounds in gas. To evaluate the efficiency of DEA purification in laboratory 

conditions, studies were carried out that showed the presence of foaming on samples taken 

before entering activated carbon and at the exit after 60 days of carbon adsorption purification. 

To compare the results obtained, a foaming study was also carried out on fresh DEA. The 

content of high-boiling resinous substances in the composition of DEA was studied by 

chromatographic and photocolorometric methods of analysis. 

Keywords: sulfur compounds, foaming, resinous substances, carbon adsorption purification, 

chromatographic and photocalorimetric methods of analysis, diethanolamine. 

 

It is difficult to imagine the modern world economy without energy, transport, light, 

communications, radio, television, computer technology, automation equipment, space 

technology, etc., the basis for the development of which is the fuel and energy complex (FEC). 

The level of development of the fuel and energy complex reflects social, scientific and 

technological progress and often determines state policy. 

Energy resources play a leading role in the modern economy. The level of development of the 

productive forces of each state is determined to a large extent by the scale of energy 

consumption. The important role of energy resources is evidenced by the fact that more than 

70% of the world's mineral resources are energy sources. 

The oil and gas industry in the economy of Uzbekistan occupies one of the priority areas, since it 

largely ensures the well-being of the country's population and affects not only the economic 

development of the country, but also its security and energy independence, therefore the 

formation of tasks facing the oil and gas industry of Uzbekistan is dictated by the need for 

progressive economic development and is associated with solving problems to ensure the 

profitable use of the fuel and energy complex of the republic, since oil and gas occupy the 

leading place in the structure of the country's primary fuel and energy resources - (96%). Along 

with this, special attention is paid to improving purification technology, increasing the stability 

of the physical and chemical properties of sorbents and improving the environmental conditions 

for processing secondary sorbents from oil and gas refineries. 

Absorption desulfurization of gases using aqueous solutions of diethanolamine (DEA), 

monoethanolamine (MEA), triethanolamine (TEA), despite a high degree of purification, has a 

significant drawback associated with foaming of the absorbent and its carryover from absorption 

columns, leading to a decrease in the productivity of installations. The presence of intense 

foaming in the system leads to increased losses of absorbent and deterioration in the quality of 



13   A journal of the AMERICAN Journal of Engineering, Mechanics and Architecture                   www. grnjournal.us  

 
 

commercial gas. These factors, as well as an increased pressure drop in the absorber, can serve as 

evidence of foaming in the system.  

DEA is used for non-selective removal of acidic components and provides the necessary 

purification of gas from H 2 S and CO 2 , however, the disadvantage of DEA is the increased 

foaming of the diethanolamine solution , as well as the heat costs required for the regeneration of 

the absorbent. 

Increased foaming during absorption purification of natural gas from acidic components is a 

whole complex of problems caused by the presence of impurities of various origins in the amine 

solution. This undesirable effect is associated with the accumulation in solutions of tar-like 

substances and amine reaction by-products, which reduce the surface tension of DEA and 

promote the formation of stable foam, with a high volumetric rate of the process and the use of 

coal that has exhausted its adsorption resource. 

Several methods are known to combat foaming: physical, mechanical, technological and 

chemical. Physical methods of combating foaming include: thermal effects (freezing, heating, 

hot steam treatment), electric current, acoustic waves (most often ultrasound), vibration, creating 

high capillary pressure in the foam, etc. The most effective means is the removal of impurities 

from the system by continuously filtering the amine solution. 

The mechanical method of combating foam formation is carried out using various devices - a 

centrifuge, stirrer, etc. However, this method is ineffective. 

Chemical defoaming is the most common and most effective method of combating foam 

formation, in which various antifoaming agents and defoamers are used . The fight against 

foaming is carried out with the help of special additives for extinguishing foam, vacuum 

distillation or extraction of foaming substances, by filtering spent amine solutions, as well as by 

changing the pressure of the medium. 

Defoamers must be highly effective, have a high defoaming rate , work at low concentrations 

and have a prolonged effect; they should not change the properties of the intermediate product 

and complicate subsequent processing, should not have a toxic effect, and should be stable when 

exposed to high temperatures and storage. 

To assess the effectiveness of industrial purification of DEA ohm, two samples were taken, one 

of which was taken before entering the activated carbon, and the other at the exit, after 60 days 

of carbon adsorption purification , and the parameters of their foaming were determined. To 

compare the results obtained, a foaming study was also carried out on fresh DEA. The content of 

high-boiling resinous substances in the composition of DEA was studied by chromatographic 

and photocolorometric analysis methods. 

The results of chromatographic analysis showed that in the DEA solution selected before and 

after carbon adsorption purification, along with the peak of the main substance, there are broad 

peaks of high-boiling resinous substances, which color the DEA solution red-brown. This is 

confirmed by data obtained at FEC -2, when measuring the optical density of solutions before 

and after carbon adsorption purification. 

However, as experience in the operation of coal adsorption plants shows, despite the use of 

carbon adsorption purification, in some cases it is not possible to avoid foaming, which may be 

due to three main reasons: poor adsorption capacity of the AG-3 coal used in relation to large 

molecules of impurities; high linear speeds of the gas absorption process; and with the duration 

of use of coal, which has exhausted its adsorption resource. 

When processing natural gas to purify amine solutions from tarry, corrosive substances and 

decomposition products, the carbon adsorption purification method is widely used , in which 

regenerated amine solutions are passed through a filter filled with activated carbon. Assessing 

the quality of activated carbons used in the process is a primary task in amine desulfurization of 



14   A journal of the AMERICAN Journal of Engineering, Mechanics and Architecture                   www. grnjournal.us  

 
 

natural gas, because they directly affect the performance of the amine system and the quality of 

the resulting product. In addition, activated carbons used in adsorption plants must meet the 

following requirements: 

1. have a high adsorption capacity (absorb a large amount of adsorbent at a low concentration in 

the gas or liquid phase); 

2. have high selectivity (selectively absorb only one component from the mixture). The higher 

the value of the selectivity coefficient, the wider the scope of use, i.e. the possibility of its use 

for purifying gases with low concentrations of acidic components ; 

3. be chemically inert with respect to the components of the mixture being separated; 

4. have high mechanical strength; 

5. easy to regenerate (the ability to restore original adsorption properties) for subsequent reuse; 

6. have a low cost. 

Assessing the quality of activated carbons used in the process is a primary task in amine 

desulfurization of natural gas, because they directly affect the performance of the amine system 

and the quality of the resulting product. 

Foaming experiments were carried out in a laboratory setup. 50 ml of DEA solution was poured 

into a hollow cylinder with a diameter of 35 мм, into the base of which a filter schott was 

soldered, and air was passed through the lower tube using a compressor, which, passing through 

the volume of the solution, formed foam. It was also found that the height of the foam is directly 

dependent on the linear speed and degree of carbon adsorption cleaning. The linear speed of air 

supplied to the laboratory installation was in the range of 0.03 ÷ 0.14 m/s and covered the range 

of linear speeds (0.11 m/s) of the industrial installation. 

Effect of linear speed on the height (cm) of DEA foaming 

 

DEA solutions 

Linear speed, m/s 

0.14 0.07 0.04 0.03 

DEA before cleaning thirty 13 4.5 2.5 

DEA after carbon adsorption purification 29 13 4.5 2.5 

DEA fresh 2 Absent _ Absent _ Absent _ 

Reducing the linear speed by 2-3 times does not eliminate foaming, both in spent and purified 

DEA. In this regard, it was assumed that the coal used, after working for 60 days, does not 

provide the necessary degree of removal of the resulting impurities. 

In addition, by changing the optical density of solutions, the degree of purification and foaming 

of solutions can be determined. To do this, a certain amount of AG-3 coal (0.05 ÷ 1 g) was 

poured into flasks containing 60 ml of spent DEA. The flasks were shaken on the device for 5 

hours, after which the solutions were filtered and their optical density and the amount of foaming 

were determined. 

Another reason for unsatisfactory purification of DEA may be due to the high volume load of 

activated carbon. It has been experimentally determined that effective cleaning is observed up to 

a volume load of 5 h 
-1 

. A further increase in the volumetric load from 5 to 15 h 
-1 

leads to a 

significant deterioration in cleaning, and at higher volumetric velocities practically no cleaning 

occurs. 

This study showed that for effective industrial purification of DEA, it is necessary to reduce the 

operating time of AG-3 carbon, or use activated carbon with a higher adsorption capacity. 

 

 



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List of used literature: 

1. S.V. Nabokov, N.P. Petkina Absorbents for gas purification from H 2 S and CO 2 : experience 

and prospects for the use of ethanolamines at gas processing plants of OJSC Gazprom // 

Scientific and technical collection of Vesti Gazovoy Nauki. 2015. – No. 1 (21). – P.3-8. 

2. Afanasyev A.I., Stryuchkov V.S. Prokopenko Industrial experience in cleaning low-sulfur 

natural gas // Gas industry. – 1987. – No. 5. – P. 14–16. 

3. B.E. Shermatov , M.S. Mansurova , E.Ya. Yalgashev , D.I. Ismatov , I.E. Abdirakhimov 

Innovative work in gas processing // Oil and gas complexida burghilash, kazib olish va kaita 

ishlash zharayonlarining zamonaviy tehnologiya - Republic of ilmiy-technician anjumani. 

Karshi. – 2018. – P. 3-6.