Научная статья на тему 'INFLUENCE OF THE OXIDIZER ON THE FORMATION AND PURIFICATION EFFICIENCY OF ACID GASES PRODUCED DURING ASPHALTENE GASIFICATION'

INFLUENCE OF THE OXIDIZER ON THE FORMATION AND PURIFICATION EFFICIENCY OF ACID GASES PRODUCED DURING ASPHALTENE GASIFICATION Текст научной статьи по специальности «Химические технологии»

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ASPHALTENE / GASIFICATION / SYNGAS / ACID GAS PURIFICATION

Аннотация научной статьи по химическим технологиям, автор научной работы — Ermolaev Denis V., Daminov Ayrat Z.

The relevance of the study is determined by the need to understand the influence of the oxidizer on the formation of acid gases (CO2, H2S, COS and CS2) during thermal decomposition of high-viscosity hydrocarbons. This is important for predicting the purification efficiency of the produced gasification products and estimating the economic costs. The aim: using the simulation to study the effect of an oxidizer in the form of steam on the composition and properties of asphaltene gasification products obtained from natural bitumen, as well as to determine the cleaning efficiency depending on the amount of steam and the absorbent based on NaOH water-alkaline solution. Object: asphaltene of natural bitumen of Ashalchinskoe field of the Tatarstan Republic (Russia), oxidizer in the form of steam, the value of which varied from 0,1 to 1 depending on the amount of asphaltene. Methods: simulation of asphaltene gasification and acid gas absorption taking into account influence of an oxidizer in a form of steam with regard for basic chemical kinetics, ultimate analysis and TGA. Simulation results of gasification and absorption showed that steam used as an oxidizer during asphaltene gasification has a significant influence on the composition and properties of gasification products, as well as on the purification of syngas. With the increase of steam, aparabolic dependence of the concentrations of syngas components is observed, which values decrease with time, except for CO2. The calorific value of syngas decreases from 11,3 to 7,2 MJ/m3 and the cold gas efficiency increases from 53,4 to 62,5 % due to growth of syn-gas yield. As the amount of steam increases, the amount of absorbent decreases and the purification efficiency of acid gases rises. Thus,the amount of absorbed CO2 increases by 20,7 % while the absorbent decreases by 6,7 %. At the same time the amount of absorbed H2Sincreased by 0,39 % with decrease of NaOH by 40,9 %.

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Текст научной работы на тему «INFLUENCE OF THE OXIDIZER ON THE FORMATION AND PURIFICATION EFFICIENCY OF ACID GASES PRODUCED DURING ASPHALTENE GASIFICATION»

UDC 665.775:66.011

INFLUENCE OF THE OXIDIZER ON THE FORMATION AND PURIFICATION EFFICIENCY OF ACID GASES PRODUCED DURING ASPHALTENE GASIFICATION

Denis V. Ermolaev1,

energoed@mail.ru

Ayrat Z. Daminov1,

daminov@list.ru

1 FRC Kazan Scientific Center, Russian Academy of Sciences, 2/31, Lobachevsky street, Kazan, 420111, Russia.

The relevance of the study is determined by the need to understand the influence of the oxidizer on the formation of acid gases (CO2, H2S, COS and CS2) during thermal decomposition of high-viscosity hydrocarbons. This is important for predicting the purification efficiency of the produced gasification products and estimating the economic costs.

The aim: using the simulation to study the effect of an oxidizer in the form of steam on the composition and properties of asphaltene gasification products obtained from natural bitumen, as well as to determine the cleaning efficiency depending on the amount of steam and the absorbent based on NaOH water-alkaline solution.

Object: asphaltene of natural bitumen of Ashalchinskoe field of the Tatarstan Republic (Russia), oxidizer in the form of steam, the value of which varied from 0,1 to 1 depending on the amount of asphaltene.

Methods: simulation of asphaltene gasification and acid gas absorption taking into account influence of an oxidizer in a form of steam with regard for basic chemical kinetics, ultimate analysis and TGA.

Simulation results of gasification and absorption showed that steam used as an oxidizer during asphaltene gasification has a significant influence on the composition and properties of gasification products, as well as on the purification of syngas. With the increase of steam, a parabolic dependence of the concentrations of syngas components is observed, which values decrease with time, except for CO2. The calorific value of syngas decreases from 11,3 to 7,2 MJ/m3 and the cold gas efficiency increases from 53,4 to 62,5 % due to growth of syngas yield. As the amount of steam increases, the amount of absorbent decreases and the purification efficiency of acid gases rises. Thus, the amount of absorbed CO2 increases by 20,7 % while the absorbent decreases by 6,7 %. At the same time the amount of absorbed H2S increased by 0,39 % with decrease of NaOH by 40,9 %.

Key words:

Asphaltene, gasification, syngas, acid gas purification, NaOH. Introduction

According to the International Energy Agency, in 2021 global CO2 emissions increased by nearly 4,8 percent to 33 Gigatons, thereby approaching the 2018-2019 peak [1]. This increase, as noted by the International Energy Agency, is due to a recovery in demand for classic energy sources such as coal, oil and gas in the second year of the Covid-19 pandemic. In this regard, the use of conventional energy technologies will lead to an increase in acid gases, which will not only worsen the environmental situation, but also have a negative impact on energy equipment. One way to solve this problem is to use clean technologies, which reduce the negative impact on the environment by significantly improving energy efficiency, sustainable use of resources or environmental protection activities. Clean technologies include a wide range of technologies related to recycling, renewable energy, etc. In this regard, the use of fuel gasification is a more environmentally attractive technology compared to direct combustion. According to the Global Syngas Technologies Council, there are several hundred gasification plants work in the USA, Europe, Asia, South Africa and other countries which process various raw materials for the production of liquid and gaseous fuels [2]. Oil sands and bitumen are the important sources of raw materials and are being studied in Canada, USA, Venezuela and other countries. According to [3], bitumen reserves are estimated at 5,9 billion tons in the United States, 24,1 billion

tons in Canada, and 36,4 billion tons in Venezuela. A significant amount of bitumen in Russia is concentrated in the Tatarstan Republic (about 7 billion tons). Gasification of bitumen will produce syngas and related products for various industries.

Natural gas, associated petroleum gas, syngas may contain acid gaseous components - carbon dioxide (CO2) and hydrogen sulfide (H2S), as well as sulfur compounds - carbonyl sulfide (COS), carbon disulfide (CS2), and other impurities that negatively affect the environment and equipment. For example, the presence of CO2 and H2S creates conditions for metal corrosion and also reduces the efficiency of catalytic processes. In addition, H2S and COS are highly toxic substances. Removal of these acid gases is driven by operational, economic, and environmental factors [4].

Various absorbents and methods, including alkanola-mines [5], organic solvents [6], membrane separation [7], adsorption, and biological methods [8], are used to purify acid gases. One way to purify acid gases in industry is to use aqueous-alkaline solutions, particularly based on sodium hydroxide (NaOH) [9]. One of the advantages of the latter is that it does not contain harmful impurities. Waste NaOH can be used for simple neutralization or in pulp and paper mills after quality control analysis [10].

The use of NaOH today is quite widespread and still relevant. A study [11] described the simultaneous removal of gaseous NOx and SO2 from the flue gases of coal-

DOI 10.18799/24131830/2022/4/3474

215

fired power plants, where NaOH was used as an absorbent in the wet scrubber cleaning process, are described.

In [12] the authors conduct a comparative analysis of the use of different membrane contactor for effective and selective removal of SO2 from the exhaust gases of ships using NaOH.

The authors of [13] used NaOH to reduce H2S concentrations in wastewater collection system wells, which reduced the average H2S content by a factor of about 10.

A work [14] proposes using NaOH in a scrubber to remove H2S from the geothermal fluid in the pilot plant of the Castelnuovo geothermal power plant. Due to the adopted countercurrent scrubber nozzle design, H2S removal efficiency was achieved and allowed high CO2 concentrations to be treated.

One of the recent works related to NaOH concerns its application as a catalyst together with Ni to effectively increase hydrogen production and decompose phenol in the treatment of complex phenolic wastewater [15].

NaOH is mainly used in the form of a solution in liquid form. However, the authors of the work [16] proposed a technology for purification of flue gases of power plants from CO2 and obtaining from it a solid carbonate, which uses NaOH in solid form.

In addition to technical solutions for the use of NaOH, scientific research related to this alkali is being conducted.

Paper [17] presents a method for measuring CO2 in synthetic biogas by passing it through a dilute NaOH solution.

The authors of the paper [18] developed a polarizable sodium hydroxide force field for modeling the structure and thermodynamics of concentrated NaOH solutions. This force field allows us to describe the structural and thermodynamic properties of NaOH salt in aqueous solutions, which is confirmed with experiments for a wide range of concentrations.

In [19] four mass transfer rate models and two enhancement factors were estimated using CFD modeling for CO2 uptake in aqueous NaOH solution by comparing simulation results with previously published experimental data.

The purpose of this work is to evaluate the influence of the oxidizer on the formation of syngas components and the efficiency of its purification from acid gases using NaOH-based aqueous-alkaline solution.

Model development

Model description

Bitumen contains heteroatomic compounds, including sulfur, oxygen, nitrogen, metals, and high-molecular oil hydrocarbons [20]. Asphaltene of natural bitumen of the Ashalchinskoe oilfield (Russia) was chosen as the object of numerical simulation as a substance containing a significant amount of carbon and hydrogen.

The ultimate analysis and properties of asphaltene under study are presented in Table 1. According to work [21] the structural formula of asphaltene was chosen. CHNS contents were determined using elemental analyzer (EuroEA3000, Eurovector SpA, Italy). The calorific value of the sample was determined in an IKA C200 calorimeter (Germany).

Table 1. Ultimate analysis and properties of the asphal-

tene under study Таблица 1. Элементный анализ и свойства исследуемого асфальтена

Formula/Формула C164H150N4O4S3

Carbon/Углерод 84,28 %

Hydrogen/Водород 6,47 %

Oxygen/Кислород 2,73 %

Nitrogen/Азот 2, 4 %

Sulfur/Сера 4,12 %

Molar mass/Молярная масса 2,337 kg/mol/кг/моль

Calorific value/Теплота сгорания 35,4 MJ/kg/МДж/кг

Fig. 1 shows a flow chart of asphaltene gasification and syngas purification. Asphaltene is sprayed in the internal space of the gasifier and interacts with the steam. As a result, syngas and a solid residue in the form of un-reacted hydrocarbon are formed. The produced syngas containing sulfur products is directed to the absorber for purification, where it is purified from acid gases by a NaOH-based aqueous-alkaline solution.

Absorption

Solid residue products

Fig. 1. Flow chart of asphaltene gasification and syngas purification

Рис. 1. Схема газификации асфальтена и очистки синтез-газа

For the numerical simulation, steam was taken as the oxidizer. The steam/asphaltene ratio (S/A) was chosen as a variable parameter, on which the amount of formed gasification products depends. A temperature value of 1400 °C corresponds to the gasification temperature of heavy oil residues according to Texaco technology. The gasification pressure was calculated based on the ideal gas law. The values given in Table 2 were used as operating parameters for asphaltene gasification simulation.

Table 2. Operating parameters of tgasification Таблица 2. Режимные параметры процесса газификации

Gasification temperature Температура газификации 1400 °С

Asphaltene flow rate/Расход сырья 100 kg/h/кг/ч

Oxidizer/Окислитель H2O (steam)/(пар)

Steam/asphaltene ratio (S/АуПар/асфальтен 0,1-1

NaOH-based aqueous-alkaline solution was chosen as an absorbent for purification of acid gases produced during asphaltene gasification simulation. Table 3 shows the absorption specifications based on data from work [22].

Table 3. Absorption specifications

Таблица 3. Характеристики процесса абсорбции

Absorption temperature Температура абсорбции 25 °С

Ab sorbent/ Абсорбент NaOH

Solution concentration Концентрация раствора 10 % NaOH, 90 % H2O

Molar mass/Молярная масса 0,019 kg/mol/кг/моль

The methodology for evaluating the oxidizer effect on the formation and purification efficiency of acid gases produced during asphaltene gasification included several steps (Fig. 2).

Fig. 2. Flow chart of research

Рис. 2. Алгоритм исследования

Stage 1 - development of the asphaltene gasification

model, including the following tasks:

• gathering information about the gasified feedstock (elemental composition, molar mass, calorific value, formula);

• determination of operating parameters of gasification (temperature, oxidizer, oxidizer/feedstock ratio, flow rates);

• determination of the kinetics of gasification (initial concentrations of reagents, gasification reactions, reaction rate constants);

• obtaining gasification simulation results (concentrations of gasification products, calorific value of syngas, cold gas efficiency, gasification pressure);

• comparison of simulated results with the known data. Stage 2 - development of the syngas purification

model, including the following tasks:

• gathering information about the absorbent (solution composition and concentration, molar mass);

• determination of absorption specifications (temperature, acid gas and absorbent flow rates);

• determination of the absorption kinetics (initial concentrations of reagents, absorption reactions, reaction rate constants);

• obtaining absorption simulation results (concentrations of absorption products);

• comparison of simulated results with the known data. Stage 3 - determination of acid gas purification efficiency depending on the amount of oxidizer and absorbent, including the following tasks:

• determination of maximum permissible concentrations (MPC) of acid gases in accordance with regulatory documents;

• determination of the necessary amount of absorbent to achieve safe values of the acid gas content at different S/A ratios;

• determination of the purification efficiency of acid gases at different S/A ratios.

Model assumptions

In order to simplify the simulation, some assumptions are made as follows:

• The reaction of asphaltene and steam produces syngas and a solid residue in the form of unreacted carbon (reaction R1).

• Part of the carbon interacts with CO2, H2 and steam.

• The produced dry syngas consists of CO, CO2, H2, CH4, N2 and H2S.

Methods

Gasification kinetics

Gasification kinetics can be viewed as a complex of several stages (Fig. 1). Having reached the required spray temperature, fuel and oxidizer continue heating until microcracks form on the asphaltene surface due to water evaporation. As a result, light hydrocarbons are released. Then oxidation-reduction, steam-methane reforming and water-gas shift reactions take place. At this time solid residue and syngas are formed.

In developing the asphaltene gasification model, the following chemical reactions were considered. Chemical reactions with steam and asphaltene:

Asphaltene+H2O^H2+CO+CO2+CH4+H2O+H2S+N2+C (R1)

CH4+2H2O^CO2+4H2 (R2)

H2O^H2+0,5O2 (R3)

Steam-Reforming reaction:

CO+3H2^CH4+H2O (R4)

CH4+0,5O2^CO+2H2 (R5)

Water-gas shift reaction:

CO2+H2^CO+H2O (R6)

Methanation reaction:

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2CO+2H2^CH4+CO2 (R7)

Chemical reaction with carbon:

CH4^C+2H2 (R8)

C+H2O^CO+H2 (R9)

C+2H2O^CO2+2H2 (R10)

C+CO2^2CO (R11)

Chemical reactions with sulfur-containing substances:

CH4+2H2S^CS2+4H2 (R12)

CO2+H2S^COS+H2O (R13)

2COS^CO2+CS2 (R14)

CS2+2H2O^CO2+2H2S Oxidation reaction:

(R15)

C+0,5O2^CO (R16)

To determine the rate constant in the reaction R1, the experiments were carried out to determine the mass change using TGA and DSC methods and a NETZSCH STA 449 F3 thermal analyzer (Germany) [23].

Using the relation from work [24], the rate constant of the second-order reaction was calculated as:

к = -

t is the time, min; c0 is the initial sample mass, kg; c is the sample mass at time t, kg.

The obtained average value of the rate constant for the reaction R1 was 5,997 10-5. This value was used for asphaltene gasification model. For the other reactions R2-R16, the rate constants and equilibria were obtained from the data from the works [25-27].

Kinetics of the absorption process

The absorber is supplied with a water-alkaline solution, which is sprayed onto the incoming gas and captures the acid gases. The purified syngas is used for energy production, and the absorption products are used as feedstock in various industries.

The following reactions occurring in the interaction of hydrogen sulfide and NaOH were used for syngas absorption model [10]:

H2S+NaOH^NaHS+H2O (R17)

H2S+2NaOH^Na2S+2H2O (R18)

The interaction of CO2 with NaOH was based on the following kinetics [22]:

CO2+NaOH^NaHCO3 (R19)

CO2+2NaOH^Na2CO3+H2O (R20)

The produced additional organosulfur compounds also interact with NaOH:

COS+4NaOH^Na2S+Na2CO3+2H2O (R21)

CS2+6NaOH^2Na2S+Na2CO3+3H2O (R22)

According to Kopylov [22] the values of the reaction rate constants for sulfur compounds [R17, R18, R21, R22] were taken as 1,87-W-4 and for CO2 [R19, R20] - 1,23-10-5.

Methods of data analysis

The cold gas efficiency (CGE) is defined as [28]: CGE = (HHVgas-ф) / HHVfeedstock.

Here, ф is the gas yield in m3/kg; HHVgas is the higher heating value of the producer gas in MJ/m3; and HHVfeedstock is the higher heating value of the asphaltene in MJ/kg.

Model Validation

As for validation purpose the results of simulation of asphaltene gasification and syngas absorption were compared with known literature data. The accuracy of the proposed models is estimated by the root mean square error (RMSE) using follow equation:

RMSE=.

Xn=1(ExP< - Mod)2

Here, Exp is the experimental (literary) value; Mod is the simulated value; n is the number of values.

Results and discussion

Using Comsol Multiphysics software the following results of the asphaltene gasification and syngas absorption simulation were obtained.

Gasification simulation results

Fig. 3 shows the non-stationary dependences of the concentrations of the syngas components at S/A=0,1, 0,5 and 1. As can be seen from the figure, in the beginning of gasification there is a rapid increase in the concentration of CO and H2, then the process slows down. At the same time, there is an increase in the concentration of CO2. With the increase of steam, a parabolic dependence of the concentrations of syngas components is observed, which values decrease with time, except for CO2.

T ■ c ■ c

n

С, mol/m3 S/A=1

26

24

22

20

16 ■

11 ■

12 ■

10 3

6 ■ 4 /

2 0 /

О 20 40 60

— H2 CO - -C02 CH4 N2

Fig. 3. Dependences of syngas component concentrations on time at S/A=0,1, 0,5 and 1

Рис. 3. Зависимости нестационарных концентраций компонентов синтез-газа при S/A=0,1, 0,5 и 1

Fig. 4 shows the dependence of the calorific value of syngas (HHVgas) on the S/A ratio. It can be seen that as the amount of steam increases, the calorific value decreases from 11,3 to 7,2 MJ/m3. Meanwhile, CGE increases from 53,4 to 62,5 % due to the increase in syngas yield. Fig. 5 shows the dependence of the change in the average gasification pressure on S/A ratio. It can be seen that with increasing steam, the average gasification pressure declines. This is due to a decrease in the initial molar concentrations of the reagents as the S/A ratio increases.

Fig. 4. Dependence of HHV syngas and CGE value on the S/A ratio

Рис. 4. Зависимость теплоты сгорания синтез-газа и КПД газификации от S/A

0.5%0.2%0э%05%<^1%1.3% о.j% о2%0-3%

Н2 СО С02 СН4 H2S Н20

Our results ■ Vaezi et al(2011) Ancheyta [2013)

Fig. 6. Comparison of the results of asphaltene gasification

simulation with the known data Рис. 6. Сравнение результатов моделирования газификации асфальтенов с известными данными

Table 4. Obtained values of acid gas concentrations at different S/A

Таблица 4. Полученные значения концентраций кислых газов при различных S/A

CO2 H2S COS CS2

mg/m3/Mr/M3

0,1 56 109 10 307 0,251 0,936

0,2 84 894 9 042 0,198 0,362

0,3 102 309 8 164 0,165 0,188

0,4 112 446 7 556 0,143 0,115

0,5 119 579 7 046 0,126 0,073

0,6 124 929 6 577 0,111 0,046

0,7 127 965 6 243 0,101 0,032

0,8 130 394 5 901 0,091 0,022

0,9 131 815 5 626 0,084 0,016

1 132 704 5 368 0,077 0,011

MPC/ПДК 27 000 3 10 10

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Fig. 5. Dependence of gasification pressure on S/A Рис. 5. Зависимость давления газификации от S/A

For validation of the results of asphaltene gasification simulation, the concentrations of syngas components were compared with the data [29, 30] at S/A=0,4 and T=1400 °C (Fig. 6). Our results showed good convergence with the results of other researchers (RMSE=4,7 and RMSE=6,13 respectively). The low values of CO and CO2 are related to the deficit of oxygen during steam gasification.

The values of acid gas concentrations obtained during asphaltene gasification simulation at different S/A ratios are presented in Table 4. For comparison, the values of maximum permissible concentrations (MPC) for acid gases according to Sanitary-hygienic standard 2.2.5.2100-06 [31] are also presented. The table shows that concentration of CO2 exceeds the standard by 2-5 times. For H2S this indicator is higher by 3000 times. COS and CS2 concentrations do not exceed MPC, so we did not consider them further.

Absorption simulation results

As a result of syngas purification simulation, the values of purification efficiency and amount of absorbent at different S/A ratios were obtained.

Fig. 7, 8 show the dependences of the absorption degree of acid gases on the amount of absorbent at S/A=0,1, 0,5 and 1. According to results of calculation it is visible that with increase of steam, purification efficiency increases and amount of required absorbent declines. Meanwhile, the curves of CO2 purification efficiency become parabolic with increasing S/A ratio, while for H2S it is closer to a linear dependence.

1.5 2 2.5 3

► S/A=0.1 -*-Si'A=C.5 -e-S/A=1

Fig. 7. Dependence of CO2 absorbed on the absorbent at different S/A

Рис. 7. Зависимость поглощенного CO2 от абсорбента при различных S/A

1.5 2 2.5 3

S'A=n 1 -*-SiA=0.5 ■ Я'Д=1

Fig. 8. Dependence of H2S absorbed on the absorbent at different S/A

Рис. 8. Зависимость поглощенного H2S от абсорбента при различных S/A

For validation the results of syngas purification simulation, we compared them with the known data [32, 33] under similar conditions (Figs. 9, 10) and they showed good convergence (RMSE=3,62 and 4,98 respectively).

the amount of steam increases, there is a decrease in the amount of absorbent and an increase in purification efficiency. Thus, the amount of absorbed CO2 increases by 20,7 % (from 53,68 to 74,38 %) with a decrease in the amount of NaOH for purification by 6,7 % (from 1,5 to 1,4). At the same time, the amount of absorbed H2S increased by 0,39 % (from 96,34 to 96,73 %) with a decrease in NaOH by 40,9 % (from 4,4 to 2,6). The obtained dependence of purification efficiency on the amount of absorbent agrees with the results of Alvarez-Cruz et al. [34].

Table 5. Safe acid gases values at different S/A Таблица 5. Безопасные значения кислых газов при различных S/A

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S/A О О 33 о £ isls s ® о о CO2 absorbed, % Уловленный CO2, % S ffi S3 O a £ Vs S s S, ,S2 ffi ® H2S absorbed, % Уловленный H2S, %

0,1 1,5 26552 53,68 4,4 2,93 96,34

0,2 1,5 23808 57,05 3,6 2,96 96,38

0,3 1,5 22295 60,42 3,3 2,79 96,43

0,4 1,4 24306 63,79 3,1 2,84 96,47

0,5 1,4 23096 67,16 2,9 2,98 96,52

0,6 1,4 22284 68,61 2,8 2,95 96,56

0,7 1,4 21773 70,05 2,8 2,75 96,60

0,8 1,4 21435 71,49 2,7 2,81 96,65

0,9 1,4 21148 72,94 2,6 2,93 96,69

1 1,4 21056 74,38 2,6 2,78 96,73

1 1.5 2

-Our results -*-Trisnaliani el al (2020)

Fig. 9. Comparison of the dependence of CO2 absorbed

with the known data Рис. 9. Сравнение зависимости поглощения CO2 с известными данными

1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.£

-Our results-» Chen et al (2001)

Fig. 10. Comparison of the dependence of H2S absorbed

with the known data Рис. 10. Сравнение зависимости поглощения H2S с известными данными

Effect of the oxidizer on acid gases

Table 5 shows the safe values of acid gases (below the MPC value) depending on the amount of absorbent, steam and purification efficiency. The table shows that as

Conclusions

It was revealed that steam used as an oxidizer during asphaltene gasification has a significant effect on the composition and properties of gasification products, as well as on the syngas purification.

The results of asphaltene gasification simulation showed that in the beginning of gasification there is a rapid increase in the concentration of CO and H2, then the process slows down. With the increase of steam, a parabolic dependence of the concentrations of syngas components is observed, which values decrease with time, except for CO2. The calorific value of syngas decreases from 11,3 to 7,2 MJ/m3 and the cold gas efficiency increases from 53,4 to 62,5 % due to an increase in syngas yield.

Comparing the obtained concentrations of acid gases with MPC, it was found that the concentration of CO2 exceeds the standard by 2-5 times, H2S - by 3000 times. COS and CS2 concentrations do not exceed the MPC.

The results of syngas purification simulation showed that as the amount of steam increases, there is a decrease in the amount of absorbent and an increase in purification efficiency. Thus, the amount of absorbed CO2 increases by 20,7 % (from 53,68 to 74,38 %) with a decrease in the amount of NaOH for purification by 6,7 % (from 1,5 to 1,4). At the same time, the amount of absorbed H2S increased by 0,39 % (from 96,34 to 96,73 %) with a decrease in NaOH by 40,9 % (from 4,4 to 2,6).

This work was supported by the Ministry of Education and Science of the Russian Federation (project no. FMEG-2021-0001).

REFERENCES

1. International Energy Agency. Global Energy Review 2021. Assessing the effects of economic recoveries on global energy demand and CO2 emissions in 2021. Available at: https://www.iea.org/ re-ports/global-energy-review-2021 (accessed 5 July 2021).

2. Higman C., Van der Burgt M. Gasification. 2n ed. Burlington, VT, USA, Gulf Professional Publ., 2008. 456 p.

3. Kashirtsev V.A., Hein F.J. Overview of natural bitumen fields of the Siberian platform, Olenek uplift, Eastern Siberia, Russia. Heavy-oil and oil-sand petroleum systems in Alberta and beyond: AAPG Studies in Geology. The American Association of Petroleum Geologists, 2013, vol. 64, pp. 509-529.

4. Kohl A.L., Nielsen R.B. Gas Purification. 5th ed. USA, Houston, Gulf Professional Publ., 1997. 1395 p.

5. Rufford T.E., Smart S., Watson G.C.Y., Graham B.F., Boxall J., Diniz da Costa J.C., May E.F. The removal of CO2 and N2 from natural gas: a review of conventional and emerging process technologies. Journal of Petroleum Science and Engineering, 2012, vol. 94-95, pp. 123-154.

6. Tanthana J., Rayer A.V., Gupta V., Mobley P.D., Soukri M., Zhou J., Lail M. Experimental study of a hydrophobic solvent for natural gas sweetening based on the solubility and selectivity for light hydrocarbons (CH4, C2H6) and acid gases (CO2 and H2S) at 298-353 K. Journal of Chemical & Engineering Data, 2019, vol. 64 (2), pp. 545-556.

7. Hedayat M., Soltanieh M., Mousavi S.A. Simultaneous separation of H2S and CO2 from natural gas by hollow fiber membrane contactor using mixture of alkanolamines. Journal of Membrane Science, 2011, vol. 377, pp. 191-197.

8. Castellani B., Rossi F., Filipponi M., Nicolini A. Hydrate-based removal of carbon dioxide and hydrogen sulphide from biogas mixtures: experimental investigation and energy evaluations. Biomass andBioenergy, 2014, vol. 70, pp. 330-338.

9. Tippayawong N., Thanompongchart P. Biogas quality upgrade by simultaneous removal of CO2 and H2S in packed column reactor. Energy, 2010, vol. 35 (12), pp. 4531-4535.

10. Üresin E., Sara9 H.I., Sarioglan A., Ay §., Akgün F. An experimental study for H2S and CO2 removal via caustic scrubbing system. Process Safety and Environmental Protection, 2014, vol. 94, pp. 196-202.

11. Kang M.S., Shin J., Yu T.U., Hwang J. Simultaneous removal of gaseous NOx and SO2 by gas-phase oxidation with ozone and wet scrubbing with sodium hydroxide. Chemical Engineering Journal, 2020, vol. 381, 122601.

12. Xu P., Huang Y., Kong X., Gong D., Fu K., Chen X., Qiu M., Fan Y. Hydrophilic membrane contactor for improving selective removal of SO2 by NaOH solution. Separation and Purification Technology, 2020, vol. 250, 117134.

13. Wiley P.E. Reduction of hydrogen sulfide gas in a small wastewater collection system using sodium hydroxide. Water Environment Research, 2019, vol. 91, pp. 483-490.

14. Colucci V., Niknam P.H., Fiaschi D., Talluri L., Manfrida G. Acid gas removal in a geothermal pilot power plant via caustic scrubbing system: the case study of Castelnuovo. The 12th European Congress of Chemical Engineering. Florence, 2019. pp. 1-3.

15. Zhang H., Zhang R., Ling Z., Li W., Yan Y., Gong M., Ma J. Partial oxidation of phenolic wastewater using NaOH and Ni addition for hydrogen production and phenolics degradation in supercritical water. Separation and Purification Technology, 2021, vol. 268, 118685.

16. Ruiz C., Rincón L., Contreras R.R., Sidney C., Almarza J. Sustainable and negative carbon footprint solid-based NaOH technology for CO2 capture. ACS Sustainable Chemistry & Engineering, 2020, vol. 8, pp. 19003-19012.

17. Fahim F., Shayegan J. CO2 measurement of synthetic biogas by passing it through dilute NaOH solution. Iranian Journal of Chemistry and Chemical Engineering, 2020, vol. 39 (3), pp. 107-116.

18. Coste A., Poulesquen A., Diat O., Dufreche J.-F., Duvail M. Investigation of the structure of concentrated NaOH aqueous solutions by combining molecular dynamics and wide angle X-ray scattering. The Journal ofPhysical Chemistry B, 2019, vol. 123, pp. 5121-5130.

19. Junda L., Ping Z., Liu L., Si C., Yanpo S., Hongjie Y. CFD modeling of reactive absorption of CO2 in aqueous NaOH in a rectangular bubble column: comparison of mass transfer and enhancement factor model. Chemical Engineering Science, 2020, vol. 230, 116218.

20. Read J., Whiteoak D. The Shell bitumen handbook. London, U.K., Thomas Telford Publ., 2003. 464 p.

21. Ancheyta J. Modeling and simulation of catalytic reactors for petroleum refining. Hoboken, New Jersey, John Wiley & Sons, Inc., 2011. 528 p.

22. Kopylov A.Y. Tekhnologii podgotovki i pererabotki sernistogo uglevodorodnogo syrya na osnove ekstraktsionnykh protsessov. Dis. Dokt. nauk [Technologies of the preparation and processing of sulfur hydrocarbon feedstocks based on extraction processes. Dr. Diss.]. Kazan, 2010. 396 p.

23. Ermolaev D.V. The prediction of the concentrations of syngas components produced during non-catalytic steam gasification of bitumen. Petroleum Science and Technology, 2018, vol. 36 (5), pp. 392-397.

24. Pismenko V.T., Kalukova E.N. Kinetika khimicheskikh reaktsiy. Opredelenie konstanty skorosti i energii aktivatsii reaktsiy. Metodicheskie ukazaniya k laboratornoy rabote [Kinetics of chemical reactions. Determination of the rate constant and the activation energy of the reactions. Methodological instructions for laboratory work on physical chemistry]. Ulyanovsk, UlSTU Publ., 2002. 20 p.

25. Nikolsky B.P. Spravochnik khimika. T. 3. Khimicheskoe ravnovesie i kinetika svoystva rastvorov [Chemist's Handbook. Vol. 3. Chemical equilibrium and kinetics of the properties of solutions]. Moscow; Leningrad, Khimiya Publ., 1965. 1006 p.

26. Luo Y.-R. Comprehensive handbook of chemical bond energies. Boca Raton, London; New York, CRC Press, 2007. 1688 p.

27. Mingaleeva G.R., Ermolaev D.V., Galkeeva A.A. Physico-chemical foundations of produced syngas during gasification process of various hydrocarbon fuels. Clean Techn Environ Policy, 2016, vol. 18 (1), pp. 297-304.

28. Hu Y., Qiurong Cheng Q., Wang Y., Guo P., Wang Z., Liu H., Akbari A. Investigation of biomass gasification potential in syngas production: characteristics of dried biomass gasification using steam as the gasification agent. Energy Fuels, 2020, vol. 34, pp. 1033-1040.

29. Vaezi M., Passandideh-Fard M., Moghiman M., Charmchi M. Gasification of heavy fuel oils: a thermochemical equilibrium ap-proaslide Fuel, 2011, vol. 90 (2), pp. 878-885.

30. Ancheyta J. Modeling of processes and reactors for upgrading of heavy petroleum. USA, Boca Raton, CRC Press, Taylor & Francis Group, 2013. Vol. XXIII, 524 p.

31. GN 2.2.5.2100-06 Predelno dopustimye kontsentratsii vrednykh veshchestv v vozdukhe rabochey zony [Sanitary-hygienic standard 2.2.5.2100-06 Maximum permissible concentrations of harmful substances in occupational air]. Moscow, Ministry of Health of the Russian Federation, 2006. 3 p.

32. Trisnaliani L., Pranata D.E., Fatria Tahdid Ridwan K.A., Alfarizi M.N., Lumbantoruan M.P. The Effect of flowrate and NaOH concentration to CO2 reduction in biogas products using absorber. Journal of Physics: Conference Series, 2020, vol. 1500, 012054.

33. Chen L., Huang J., Yang C.-L. Absorption of H2S in NaOCl caustic aqueous solution. Environmental Progress, 2001, vol. 20 (3), pp. 175-181.

34. Álvarez-Cruz R., Sánchez-Flores B.E., Torres-González J., Anta-ño-López R., Castañeda F. Insights in the development of a new method to treat H2S and CO2 from sour gas by alkali. Fuel, 2012, vol. 100, pp. 173-176.

Received: 8 April 2022.

Information about the authors

Denis V. Ermolaev, Cand. Sc., senior researcher, Institute of Power Engineering and Advanced Technologies, FRC Kazan Scientific Center, Russian Academy of Sciences.

Ayrat Z. Daminov, Cand. Sc., leading researcher, Institute of Power Engineering and Advanced Technologies, FRC Kazan Scientific Center, Russian Academy of Sciences.

УДК 665.775:66.011

ВЛИЯНИЕ ОКИСЛИТЕЛЯ НА ОБРАЗОВАНИЕ И ЭФФЕКТИВНОСТЬ ОЧИСТКИ КИСЛЫХ ГАЗОВ, ПОЛУЧЕННЫХ В ПРОЦЕССЕ ГАЗИФИКАЦИИ АСФАЛЬТЕНА

Ермолаев Денис Васильевич1,

energoed@mail.ru

Даминов Айрат Заудатович1,

daminov@list.ru

1 Федеральный исследовательский центр «Казанский научный центр Российской академии наук», Россия, 420111, г. Казань, ул. Лобачевского, 2/31.

Актуальность исследования определяется необходимостью понимания влияния окислителя на образование кислых газов (CO2, H2S, COS и CS2) в процессе термического разложения высоковязких углеводородов. Это важно для прогнозирования эффективности очистки полученных продуктов газификации и оценки экономических затрат.

Цель: с помощью математического моделирования исследовать влияние окислителя в виде пара на состав и свойства продуктов газификации асфальтена, полученного из природных битумов, а также определить степени очистки в зависимости от количества пара и абсорбента на основе водно-щелочного раствора NaOH.

Объект: асфальтен природного битума Ашальчинского месторождения Республики Татарстан (Россия), окислитель в виде пара, величина которого варьировалась от 0,1 до 1 в зависимости от количества асфальтена.

Метод: математическое моделирование процессов газификации асфальтенов и абсорбции кислых газов при воздействии окислителя в виде пара с учетом основ химической кинетики, элементного и термогравиметрического анализов. Результаты моделирования процессов газификации и абсорбции показали, что пар, используемый в качестве окислителя при газификации асфальтенов, оказывает существенное влияние на состав и свойства продуктов газификации, а также на очистку синтез-газа. С увеличением пара наблюдается параболическая зависимость концентраций компонентов синтез-газа, значения которых со временем уменьшаются, за исключением СО2. Теплотворная способность синтез-газа снижается с 11,3 до 7,2 МДж/м3, а КПД газификации повышается с 53,4 до 62,5 % за счет увеличения выхода синтез-газа. По мере роста количества пара уменьшается количество абсорбента и увеличивается эффективность очистки синтез-газа от кислых газов. Таким образом, количество поглощенного СО2 увеличивается на 20,7 % при снижении абсорбента на 6,7 %. При этом количество поглощенного H2S выросло на 0,39 % при снижении NaOH на 40,9 %.

Ключевые слова:

Асфальтен, газификация, синтез-газ, очистка кислых газов, NaOH.

Работа выполнена при поддержке Министерства образования и науки Российской Федерации (Гос. задание № FMEG-2021-0001).

СПИСОК ЛИТЕРАТУРЫ

1. International Energy Agency. Global Energy Review 2021. Assessing the effects of economic recoveries on global energy demand and CO2 emissions in 2021 // Docslide. 2021. URL: https://www.iea.org/reports/global-energy-review-2021 (дата обращения 05.07.2021).

2. Higman C., Van der Burgt M. Gasification. 2nd ed. - Burlington, VT, USA: Gulf Professional Publishing, 2008. - 456 p.

3. Kashirtsev V.A., Hein F.J. Overview of natural bitumen fields of the Siberian platform, Olenek uplift, Eastern Siberia, Russia. Heavy-oil and oil-sand petroleum systems in Alberta and beyond: AAPG Studies in Geology // The American Association of Petroleum Geologists. - 2013. - V. 64. - P. 509-529.

4. Kohl A.L., Nielsen R.B. Gas Purification. 5th ed. - USA, Houston: Gulf Professional Publishing, 1997. - 1395 p.

5. The removal of CO2 and N2 from natural gas: a review of conventional and emerging process technologies / T.E. Rufford, S. Smart, G.C.Y. Watson, B.F. Graham, J. Boxall, J.C. Diniz da Costa, E.F. May // Journal of Petroleum Science and Engineering. - 2012. - V. 94-95. - P. 123-154.

6. Experimental study of a hydrophobic solvent for natural gas sweetening based on the solubility and selectivity for light hydrocarbons (CH4, C2H6) and acid gases (CO2 and H2S) at 298-353 K / J. Tanthana, A.V. Rayer, V. Gupta, P.D. Mobley, M. Soukri, J. Zhou, M. Lail // Journal of Chemical & Engineering Data. - 2019. - V. 64 (2). - P. 545-556.

7. Hedayat M., Soltanieh M., Mousavi S.A. Simultaneous separation of H2S and CO2 from natural gas by hollow fiber membrane contactor using mixture of alkanolamines // Journal of Membrane Science. - 2011. - V. 377. - P. 191-197.

8. Hydrate-based removal of carbon dioxide and hydrogen sulphide from biogas mixtures: Experimental investigation and energy evaluations / B. Castellani, F. Rossi, M. Filipponi, A. Nicolini // Biomass and Bioenergy. - 2014. - V. 70. - P. 330-338.

9. Tippayawong N., Thanompongchart P. Biogas quality upgrade by simultaneous removal of CO2 and H2S in packed column reactor // Energy. - 2010. - V. 35 (12). - P. 4531-4535.

10. An experimental study for H2S and CO2 removal via caustic scrubbing system / E. Uresin, H.I. Sara;, A. Sarioglan, §. Ay, F. Akgun // Process Safety and Environmental Protection. -2014. - V. 94. - P. 196-202.

11. Simultaneous removal of gaseous NOx and SO2 by gas-phase oxidation with ozone and wet scrubbing with sodium hydroxide / M.S. Kang, J. Shin, T.U. Yu, J. Hwang // Chemical Engineering Journal. - 2020. - V. 381 - P. 122601.

12. Hydrophilic membrane contactor for improving selective removal of SO2 by NaOH solution / P. Xu, Y. Huang, X. Kong, D. Gong, K. Fu, X. Chen, M. Qiu, Y. Fan // Separation and Purification Technolog. - 2020. - V. 250. - P. 117134.

13. Wiley P.E. Reduction of hydrogen sulfide gas in a small wastewater collection system using sodium hydroxide // Water Environment Researslide - 2019. - V. 91. - P. 483-490.

14. Acid gas removal in a geothermal pilot power plant via caustic scrubbing system: the case study of Castelnuovo / V. Colucci, P.H. Niknam, D. Fiaschi, L. Talluri, G. Manfrida // The 12th European Congress of Chemical Engineering. - Florence, 2019. -P. 1-3.

15. Partial oxidation of phenolic wastewater using NaOH and Ni addition for hydrogen production and phenolics degradation in supercritical water / H. Zhang, R. Zhang, Z. Ling, W. Li, Y. Yan,

M. Gong, J. Ma // Separation and Purification Technology. -2021. - V. 268. - P. 118685.

16. Sustainable and negative carbon footprint solid-based NaOH technology for CO2 capture / C. Ruiz, L. Rincón, R.R. Contreras, C. Sidney, J. Almarza // ACS Sustainable Chemistry & Engineering. - 2020. - V. 8. - P. 19003-19012.

17. Fahim F., Shayegan J. CO2 measurement of synthetic biogas by passing it through dilute NaOH solution // Iranian Journal of Chemistry and Chemical Engineering. - 2020. - V. 39 (3). -P. 107-116.

18. Investigation of the structure of concentrated NaOH aqueous solutions by combining molecular dynamics and wide angle X-ray scattering / A. Coste, A. Poulesquen, O. Diat, J.-F. Dufreche, M. Duvail // The Journal of Physical Chemistry B. - 2019. -V. 123. - P. 5121-5130.

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19. CFD modeling of reactive absorption of CO2 in aqueous NaOH in a rectangular bubble column: comparison of mass transfer and enhancement factor model / L. Junda, Z. Ping, L. Liu, C. Si, S. Yanpo, Y. Hongjie // Chemical Engineering Science. - 2020. -V. 230. - P. 116218.

20. Read J., Whiteoak D. The Shell bitumen handbook. - London, U.K.: Thomas Telford Publishing, 2003. - 464 p.

21. Ancheyta J. Modeling and simulation of catalytic reactors for petroleum refining. - Hoboken, New Jersey: John Wiley & Sons, Inc., 2011. - 528 p.

22. Копылов А.Ю. Технологии подготовки и переработки сернистого углеводородного сырья на основе экстракционных процессов: дис. ... д-ра техн. наук. - Казань, 2010. - 396 с.

23. Ermolaev D.V. The prediction of the concentrations of syngas components produced during non-catalytic steam gasification of bitumen // Petroleum Science and Technology. - 2018. - V. 36 (5). -P. 392-397.

24. Письменко В.Т., Калюкова Е.Н. Кинетика химических реакций. Определение константы скорости и энергии активации реакций: Методические указания к лабораторной работе по физической химии. - Ульяновск: УлГТУ, 2002. - 20 с.

25. Никольский Б.П., Рабинович В.А. Справочник химика. Т. 3. Химическое равновесие и кинетика свойства растворов. Электродные процессы. - М.; Л.: Химия, 1965. - 1006 с.

26. Luo Y.-R. Comprehensive handbook of chemical bond energies. -Boca Raton; London; New York: CRC Press, 2007. - 1688 p.

27. Mingaleeva G.R., Ermolaev D.V., Galkeeva A.A. Physico-chemical foundations of produced syngas during gasification process of various hydrocarbon fuels // Clean Techn Environ Policy. - 2016. - V. 18 (1). - P. 297-304.

28. Investigation of biomass gasification potential in syngas production: characteristics of dried biomass gasification using steam as the gasification agent / Y. Hu, Q. Qiurong Cheng, Y. Wang, P. Guo, Z. Wang, H. Liu, A. Akbari // Energy Fuels. -2020. - V. 34. - P. 1033-1040.

29. Gasification of heavy fuel oils: a thermochemical equilibrium approach / M. Vaezi, M. Passandideh-Fard, M. Moghiman, M. Charmchi // Fuel. - 2011. - V. 90 (2). - P. 878-885.

30. Ancheyta J. Modeling of processes and reactors for upgrading of heavy petroleum. - USA, Boca Raton, CRC Press, Taylor & Francis Group, 2013. - V. XXIII. - 524 p.

31. ГН 2.2.5.2100-06 Предельно допустимые концентрации (ПДК) вредных веществ в воздухе рабочей зоны. - М.: Минздрав РФ, 2006. - 3 с.

32. The Effect of flowrate and NaOH concentration to CO2 reduction in biogas products using absorber / L. Trisnaliani, D.E. Pranata, K.A. Fatria Tahdid Ridwan, M.N. Alfarizi, M.P. Lumbantoruan // Journal of Physics: Conference Series. - 2020. - V. 1500. -P. 012054

33. Chen L., Huang J., Yang C.-L. Absorption of H2S in NaOCl caustic aqueous solution / // Environmental Progress. - 2001. -V. 20(3). - P. 175-181.

34. Insights in the development of a new method to treat H2S and CO2 from sour gas by alkali / R. Álvarez-Cruz, B.E. Sánchez-Flores, J. Torres-González, R. Antaño-López, F. Castañeda // Fuel. -2012. - V. 100. - P. 173-176.

Поступила 08.04.2022 г.

Информация об авторах

Ермолаев Д.В., кандидат технических наук, старший научный сотрудник лаборатории ЭСТ Института энергетики и перспективных технологий Федерального исследовательского центра «Казанский научный центр Российской академии наук».

Даминов А.З., кандидат технических наук, ведущий научный сотрудник лаборатории ЭСТ Института энергетики и перспективных технологий Федерального исследовательского центра «Казанский научный центр Российской академии наук».

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