**The Needs for Carbon Dioxide Capture from Petroleum Industry: A Comparative Study in an Iranian Petrochemical Plant by Using Simulated Process Data**

Mansoor Zoveidavianpoor1, Ariffin Samsuri1, Seyed Reza Shadizadeh2 and Samir Purtjazyeri2 *1University Teknologi Malaysia, Faculty of Petroleum & Renewable Energy Engineering 2Petroleum University of Technology, Abadan Faculty of Petroleum Engineering 1Malaysia 2Iran* 

#### **1. Introduction**

80 Greenhouse Gases – Capturing, Utilization and Reduction

Zhang, J.; Webley, P.A. & Xiao, P. (2008). Effect of process parameters on power

requirements of vacuum swing adsorption technology for CO2 capture from flue gas. *Energy Conversion and Management*, Vol.49, No.2, pp. 346-356, ISSN 0196-8904.

> The greenhouse effect is the heating of the earth due to the presence of greenhouse gases. According to the Intergovernmental Panel on Climate Change (IPCC), the ongoing emissions of greenhouse gases from human activities are leading to an enhanced greenhouse effect. This may result, on average, in additional warming of the earth's surface (Houghton and Jenkins, 1990). During 2007, global emission of carbon was 7 billion metric tons (Bt), which are expected to increase to 14 Bt per annum by the year 2050 assuming the demand for fossil fuel keeps increasing because of the growing economies around the world (Bryant, 2007). Carbon dioxide (CO2), is considered as a raw material in chemical industry. So, its recovery from flue gas meets a great prosperity not only for economic point of view but also for its negative effects to the environment. CO2 emission control by its capturing from fossil-fuel combustion sources is applied widespread in power plants and industrial sectors. By utilization of this approach, fossil fuel could be continually allowed to be used with a lesser degree and/or without contributing significantly to greenhouse-gas warming.

> This chapter clearly shows the need for CO2 capture in downstream petroleum industry by demonstrating its health and environmental effects. These effects are briefly discussed the negative impacts of the increasing trend of CO2 emission in Iran. Afterward, a comparative study for capturing carbon dioxide in a petrochemical plant in Iran will be presented.

#### **1.1 CO2 health effects**

At 5% concentration in air (500,000 parts per million (ppm)), CO2 can produce shortness of breath, dizziness, mental confusion, headache and possible loss of consciousness. At 10 % concentrations, the patient normally loses consciousness and will die unless it is removed. With little or no warning from taste or odour, it is possible to enter a tank or a pit full of CO2 and be asphyxiated in a very short time. Long-term exposure at concentrations of 1-2 % can cause increased calcium deposition in body tissue, and may cause mild stress and

The Needs for Carbon Dioxide Capture from Petroleum Industry:

compared with 2008 levels.

Fig. 2. Total energy consumption in Iran

Fig. 3. Overall CO2 emission in Iran

A Comparative Study in an Iranian Petrochemical Plant by Using Simulated Process Data 83

The main resource of CO2 emission is fossil fuels that unfortunately now a day are the basic sources to generate energy in industrial-economic systems. On the other hand, energy is a main factor to achieve economic development, which is highly needed for developing countries. In 2009, Iran consists of 527 million metric tones (Mt) of CO2 emission and is known to be the 9th worst polluter increasing the emissions by 3.2 per cent to 2009,

As shown in Figure 4, the power plant sector with an emission of 28% CO2 is the largest carbon dioxide emissions source in Iran. Although the consumption of gas has increased in this sector during recent years, still more than 50% of the energy consumption comes from the combustion of heavy fuel oil. The industry sector is the second largest contributor to CO2 emissions, with about 133 Mt in 2008. The transport sector accounted for 23% of total CO2 emitted. As Figure 4 shows, the industry sector with about 26% of the total CO2 emissions was the second major contributor in 2008. The breakdown of the industrial CO2 emission in

behavioural changes. The National Institute for Occupational Safety and Health (NIOSH) air quality standard for the protection of occupational health sets the limit for CO2 at 10,000 ppm for 10 hours. The Occupational Safety and Health Administration (OSHA) air quality standards for the protection of occupational health set the limit for CO2 at 5,000 ppm (Webster, 1995).

Human and environmental impacts of solvent-related emissions at a capture and storage of CO2 facility were estimated by Veltman et al. (2010). They stated that, although carbon dioxide capture is relatively well-studied in terms of power generation efficiency, CO2 emission reduction, and cost of implementation, but little is known about the potential impacts on human health and the environment. The U.S. Environmental Protection Agency (EPA) has officially declared that CO2 and other so-called greenhouse gases are dangerous to public health and welfare, paving the way for much stricter emissions standards (EPA, 2009). The 2009 CO2 emission shows that the Middle East accounted for 3.3% of the total world CO2, of which 31% is the share of Iran. Consequently, as shown in Figure 1, the trend of CO2 emission is progressively increased from 1998 to 2009, which certainly endanger all aspects of life in Iran. The urban environment of Iran is becoming increasingly polluted, with adverse impacts on the health, welfare and productivity of the population. Results indicate that pollution in Tehran, where 20% of Iran's population lives, has well exceeded safe levels (EIA, 2000; Asgari et al., 1998; Masjedi et al., 1998).

Fig. 1. Increasing trend of total CO2 emission per Mt from 1980 to 2009 in Iran

#### **1.2 CO2 emission in Iran**

Iran is the second-largest producer and exporter in The Organization of the Petroleum Exporting Countries (OPEC), and in 2008 was the fourth-largest exporter of crude oil globally. Iran holds the world's third-largest proven oil reserves and the world's second-largest natural gas reserves. Figure 2 shows the total fuel consumption in Iran. As it is clear in Figure 3, the combustion of fossil energy contributes with about 84 % to the CO2 emission in Iran.

The main resource of CO2 emission is fossil fuels that unfortunately now a day are the basic sources to generate energy in industrial-economic systems. On the other hand, energy is a main factor to achieve economic development, which is highly needed for developing countries. In 2009, Iran consists of 527 million metric tones (Mt) of CO2 emission and is known to be the 9th worst polluter increasing the emissions by 3.2 per cent to 2009, compared with 2008 levels.

Fig. 2. Total energy consumption in Iran

82 Greenhouse Gases – Capturing, Utilization and Reduction

behavioural changes. The National Institute for Occupational Safety and Health (NIOSH) air quality standard for the protection of occupational health sets the limit for CO2 at 10,000 ppm for 10 hours. The Occupational Safety and Health Administration (OSHA) air quality standards for the protection of occupational health set the limit for CO2 at 5,000 ppm

Human and environmental impacts of solvent-related emissions at a capture and storage of CO2 facility were estimated by Veltman et al. (2010). They stated that, although carbon dioxide capture is relatively well-studied in terms of power generation efficiency, CO2 emission reduction, and cost of implementation, but little is known about the potential impacts on human health and the environment. The U.S. Environmental Protection Agency (EPA) has officially declared that CO2 and other so-called greenhouse gases are dangerous to public health and welfare, paving the way for much stricter emissions standards (EPA, 2009). The 2009 CO2 emission shows that the Middle East accounted for 3.3% of the total world CO2, of which 31% is the share of Iran. Consequently, as shown in Figure 1, the trend of CO2 emission is progressively increased from 1998 to 2009, which certainly endanger all aspects of life in Iran. The urban environment of Iran is becoming increasingly polluted, with adverse impacts on the health, welfare and productivity of the population. Results indicate that pollution in Tehran, where 20% of Iran's population lives, has well exceeded

safe levels (EIA, 2000; Asgari et al., 1998; Masjedi et al., 1998).

Fig. 1. Increasing trend of total CO2 emission per Mt from 1980 to 2009 in Iran

combustion of fossil energy contributes with about 84 % to the CO2 emission in Iran.

Iran is the second-largest producer and exporter in The Organization of the Petroleum Exporting Countries (OPEC), and in 2008 was the fourth-largest exporter of crude oil globally. Iran holds the world's third-largest proven oil reserves and the world's second-largest natural gas reserves. Figure 2 shows the total fuel consumption in Iran. As it is clear in Figure 3, the

(Webster, 1995).

**1.2 CO2 emission in Iran** 

Fig. 3. Overall CO2 emission in Iran

As shown in Figure 4, the power plant sector with an emission of 28% CO2 is the largest carbon dioxide emissions source in Iran. Although the consumption of gas has increased in this sector during recent years, still more than 50% of the energy consumption comes from the combustion of heavy fuel oil. The industry sector is the second largest contributor to CO2 emissions, with about 133 Mt in 2008. The transport sector accounted for 23% of total CO2 emitted. As Figure 4 shows, the industry sector with about 26% of the total CO2 emissions was the second major contributor in 2008. The breakdown of the industrial CO2 emission in

The Needs for Carbon Dioxide Capture from Petroleum Industry:

2011)

**2. CO2 capture technologies** 

A Comparative Study in an Iranian Petrochemical Plant by Using Simulated Process Data 85

Fig. 6. Prediction of the total average of temperature annual and seasonal changes from 2025 to 2100 based on the results of an applied scenario for different regions of Iran (Roshan et al.

Fig. 7. Prediction of the CO2 concentration per Mt till 2100 in Iran (Roshan et al. 2011)

As reported by the United Nations Intergovernmental Panel on Climate Changes (UNIPCH) (1995), CO2 level has risen 30% to nearly 360 ppm from a pre-industrial era level of 280 ppm.

Iran (Figure 5) shows that the petrochemical industry in Iran has more emission contribution in contrast with the other industries such as cement, steel, and gas processing plants. Boilers, process heaters, and other process equipment are the major CO2 emissions producers in a petrochemical plant. The data presented in Figure 2 through Figure 5 were extracted from different literature; Moradi et al. (2008), Avami and Farahmandpour, (2008), and NIOC (2011).

Fig. 4. Iran's Energy Sectors contributed to CO2 emission in 2008

Fig. 5. The breakdown of industrial CO2 emission in 2008

According to the recent study performed by Roshan et al. (2011), the country's temperature annual trend increment would have an increase of maximum 5.72°C to minimum 3.23°C, while considering the most optimistic case, the country's annual temperature would increased by 4.41 °C till 2100. Figure 6 shows the prediction of the total average of temperature annual and seasonal changes from 2025 to 2100 based on the results of an applied scenario for different regions of Iran. According to Figure 7, the highest amount of CO2 density, which has been forecasted for the year 2100 is 570 ppm.

Iran (Figure 5) shows that the petrochemical industry in Iran has more emission contribution in contrast with the other industries such as cement, steel, and gas processing plants. Boilers, process heaters, and other process equipment are the major CO2 emissions producers in a petrochemical plant. The data presented in Figure 2 through Figure 5 were extracted from different literature; Moradi et al. (2008), Avami and Farahmandpour, (2008),

Fig. 4. Iran's Energy Sectors contributed to CO2 emission in 2008

Fig. 5. The breakdown of industrial CO2 emission in 2008

CO2 density, which has been forecasted for the year 2100 is 570 ppm.

According to the recent study performed by Roshan et al. (2011), the country's temperature annual trend increment would have an increase of maximum 5.72°C to minimum 3.23°C, while considering the most optimistic case, the country's annual temperature would increased by 4.41 °C till 2100. Figure 6 shows the prediction of the total average of temperature annual and seasonal changes from 2025 to 2100 based on the results of an applied scenario for different regions of Iran. According to Figure 7, the highest amount of

and NIOC (2011).

Fig. 6. Prediction of the total average of temperature annual and seasonal changes from 2025 to 2100 based on the results of an applied scenario for different regions of Iran (Roshan et al. 2011)

Fig. 7. Prediction of the CO2 concentration per Mt till 2100 in Iran (Roshan et al. 2011)

#### **2. CO2 capture technologies**

As reported by the United Nations Intergovernmental Panel on Climate Changes (UNIPCH) (1995), CO2 level has risen 30% to nearly 360 ppm from a pre-industrial era level of 280 ppm.

The Needs for Carbon Dioxide Capture from Petroleum Industry:

cooled further before it re-enters the absorber.

determine the equivalent height to theoretical plate.

equations.

**3. Amine-based CO2 capture plant: Process description** 

A Comparative Study in an Iranian Petrochemical Plant by Using Simulated Process Data 87

In section 3, the applied process in this study for Amine-based CO2 capture will be described. The results of this work will be presented in Section 4 and discussed in Section 5.

Amine process is the best and commonest choice for separation of CO2 from flue gases. Driving force of this process is the reaction between CO2 and amine in which CO2 with high purity is acquired by one stage process. This process starts with cooling flue gases applying a water cooler to lessen some of their impurities such as NOx and SOx to an acceptable value. Then the chilled gas is pressurized with a blower to the absorption column. Temperature ranges at the top and bottom of the column are about 40-45 and 50-60 °C, respectively. Flue gases and the lean amine are contacted, and CO2 is absorbed in the amine solution through the absorber. Rich amine at the bottom of the column is pumped into a cross heat exchanger, where its temperature reaches to about 100 °C exchanging heat with the effluent fresh amine of stripping column. Then this solution introduced to the top section of the stripping column. Operating temperature at the top and bottom of the column, operating pressure

Finally, based on different criteria, the selected alkanolamine will be demonstrated.

and column pressure gradient are 110 °C, 120 °C, 1.3 bar and 0.17 bar, respectively.

Required energy for stripping column is supplied from saturated steam at 45 psia. The rich solution of amine and steam are contacted in stripper, and CO2 is separated from amine. The gas stream containing CO2 and water steam is exhausted from the top of the column to a condenser where its temperature is lowered to 45 °C. Almost the whole steam is condensed in the condenser and recycled to the top of the column. CO2 is recovered in a flash drum, then dried and finally compressed to an acceptable pressure. The CO2-lean solution leaves the reboiler and enters the cross heat exchanger where it is cooled. The solution is then

Packed columns are often employed in the removal of impurities from gas streams and also the removal of volatile components from liquid streams. The dimensionless Robbins correlation factor is actually the Dry Bed Packing Factor issued to calculate the gas and liquid loading factors, which are in turn used to calculate the pressure drop, particularly with newer packing materials. As shown in Table 3 and Table 5, Robbins packing correlation was used as a default correlation. The Height Equivalent to a Theoretical Plate (HETP) relates to packed towers. The value refers to the height of packing that is equivalent to a theoretical plate. As shown in Table 3 and Table 5, Frank correlation was used to

The entire schematic diagram of the CO2 absorption process is illustrated in Figure 9. The flow sheet represents a continuous absorption/regeneration cycling process. Note that the reactions of these alkanolamines and CO2 are mainly occurred by electrochemical reaction in the aqueous solution. Typical reaction mechanism of MEA and CO2 are as in the following

2RNH2 + CO2 + H2O ↔ (RNH3)2CO3 (1)

(RNH3)2CO3 + CO2 + H2O ↔ 2RNH3HCO3 (2)

Judkins et al. (1993) believed that in order to avoid major climate changes, human-generated emissions of CO2 will have to be reduced by as much as 50-80%. As a result, three strategies had proposed for CO2 emission control: (1) Exploiting the fuels more efficiently. (2) Replacing coal by natural gas. (3) Recovering and sequestering of CO2 emissions.

By considering the greenhouse gas effects, it is accepted that natural gas is preferable to other fossil fuels such as coal, and oil. Indeed, removal of CO2 from natural gas is considered as a practical and more convenience step toward reduction of CO2 emissions. Removals of CO2 from gaseous streams have been a current procedure in the chemical industry. Because of the increasing trend of energy consumption globally, removal of CO2 from natural gas is not easy to be achieved; this task, obviously, required an integrated approach based on modern capturing technologies. The choice of a suitable technology (Figure 8) depends on the characteristics of the flue gas stream, which depend mainly on the chemical or power plant technology. Figure 8 shows the technologies which are currently used for CO2 capturing.

Fig. 8. CO2 capture technologies

Chemical solvent absorption is based on reactions between CO2 and one or more basic absorbents such as aqueous solutions of Monoethanolamine (MEA), Diethanolamine (DEA) and Methyldiethanolamine (MDEA). An advantageous characteristic of absorption is that it can be reversed by sending the CO2-rich absorbent to a stripper where the temperature is raised.

In the present study, simulation of a CO2 capture from fuel gases of one of the petrochemical plants in Iran was performed by using MEA, DEA and MDEA. In this work, a process by using alkanolamines including CO2 capture from flue gases was simulated and optimized in a petrochemical plant in Iran. The simulation has been conducted using a commercial software. The required data such as the composition of three type of alcanolamines, were derived in the laboratory. This work consists of six important variables as the output of the simulation process; (1) the amount of CO2 recovery, (2) amine consumption, (3) mechanical and operational characteristics of the absorption column, (4) CO2 purity in the stripper column effluent, (5) required energy of the stripper, and (6) mechanical and operational features of the stripper.

In section 3, the applied process in this study for Amine-based CO2 capture will be described. The results of this work will be presented in Section 4 and discussed in Section 5. Finally, based on different criteria, the selected alkanolamine will be demonstrated.

#### **3. Amine-based CO2 capture plant: Process description**

86 Greenhouse Gases – Capturing, Utilization and Reduction

Judkins et al. (1993) believed that in order to avoid major climate changes, human-generated emissions of CO2 will have to be reduced by as much as 50-80%. As a result, three strategies had proposed for CO2 emission control: (1) Exploiting the fuels more efficiently. (2)

By considering the greenhouse gas effects, it is accepted that natural gas is preferable to other fossil fuels such as coal, and oil. Indeed, removal of CO2 from natural gas is considered as a practical and more convenience step toward reduction of CO2 emissions. Removals of CO2 from gaseous streams have been a current procedure in the chemical industry. Because of the increasing trend of energy consumption globally, removal of CO2 from natural gas is not easy to be achieved; this task, obviously, required an integrated approach based on modern capturing technologies. The choice of a suitable technology (Figure 8) depends on the characteristics of the flue gas stream, which depend mainly on the chemical or power plant technology. Figure 8 shows the technologies which are currently used for CO2 capturing.

Chemical solvent absorption is based on reactions between CO2 and one or more basic absorbents such as aqueous solutions of Monoethanolamine (MEA), Diethanolamine (DEA) and Methyldiethanolamine (MDEA). An advantageous characteristic of absorption is that it can be reversed by sending the CO2-rich absorbent to a stripper where the temperature is

In the present study, simulation of a CO2 capture from fuel gases of one of the petrochemical plants in Iran was performed by using MEA, DEA and MDEA. In this work, a process by using alkanolamines including CO2 capture from flue gases was simulated and optimized in a petrochemical plant in Iran. The simulation has been conducted using a commercial software. The required data such as the composition of three type of alcanolamines, were derived in the laboratory. This work consists of six important variables as the output of the simulation process; (1) the amount of CO2 recovery, (2) amine consumption, (3) mechanical and operational characteristics of the absorption column, (4) CO2 purity in the stripper column effluent, (5) required energy of the stripper, and (6) mechanical and operational

Replacing coal by natural gas. (3) Recovering and sequestering of CO2 emissions.

Fig. 8. CO2 capture technologies

features of the stripper.

raised.

Amine process is the best and commonest choice for separation of CO2 from flue gases. Driving force of this process is the reaction between CO2 and amine in which CO2 with high purity is acquired by one stage process. This process starts with cooling flue gases applying a water cooler to lessen some of their impurities such as NOx and SOx to an acceptable value. Then the chilled gas is pressurized with a blower to the absorption column. Temperature ranges at the top and bottom of the column are about 40-45 and 50-60 °C, respectively. Flue gases and the lean amine are contacted, and CO2 is absorbed in the amine solution through the absorber. Rich amine at the bottom of the column is pumped into a cross heat exchanger, where its temperature reaches to about 100 °C exchanging heat with the effluent fresh amine of stripping column. Then this solution introduced to the top section of the stripping column. Operating temperature at the top and bottom of the column, operating pressure and column pressure gradient are 110 °C, 120 °C, 1.3 bar and 0.17 bar, respectively.

Required energy for stripping column is supplied from saturated steam at 45 psia. The rich solution of amine and steam are contacted in stripper, and CO2 is separated from amine. The gas stream containing CO2 and water steam is exhausted from the top of the column to a condenser where its temperature is lowered to 45 °C. Almost the whole steam is condensed in the condenser and recycled to the top of the column. CO2 is recovered in a flash drum, then dried and finally compressed to an acceptable pressure. The CO2-lean solution leaves the reboiler and enters the cross heat exchanger where it is cooled. The solution is then cooled further before it re-enters the absorber.

Packed columns are often employed in the removal of impurities from gas streams and also the removal of volatile components from liquid streams. The dimensionless Robbins correlation factor is actually the Dry Bed Packing Factor issued to calculate the gas and liquid loading factors, which are in turn used to calculate the pressure drop, particularly with newer packing materials. As shown in Table 3 and Table 5, Robbins packing correlation was used as a default correlation. The Height Equivalent to a Theoretical Plate (HETP) relates to packed towers. The value refers to the height of packing that is equivalent to a theoretical plate. As shown in Table 3 and Table 5, Frank correlation was used to determine the equivalent height to theoretical plate.

The entire schematic diagram of the CO2 absorption process is illustrated in Figure 9. The flow sheet represents a continuous absorption/regeneration cycling process. Note that the reactions of these alkanolamines and CO2 are mainly occurred by electrochemical reaction in the aqueous solution. Typical reaction mechanism of MEA and CO2 are as in the following equations.

$$\text{2RNH}\_2 + \text{CO}\_2 + \text{H}\_2\text{O} \leftrightarrow \text{(RNH}\_3\text{)}\text{2CO}\_3\tag{1}$$

$$\text{(RNHI)}\\\text{2CO} + \text{CO}\_2 + \text{H}\_2\text{O} \leftrightarrow \text{2RNHJ}\text{HCO}\_3\tag{2}$$

The Needs for Carbon Dioxide Capture from Petroleum Industry:

Table 4.

Packing type

**Component**

types of amines are listed in Table 5.

Table 3. Specification of absorption column

A Comparative Study in an Iranian Petrochemical Plant by Using Simulated Process Data 89

Many other technologies used for CO2 capture are based on the MEA process, with changes made in either solvent choice or absorption/stripping methodology. Specifications of the absorber for three types of amines are listed in Table 3. Type and amount of packing are selected so that the maximum recovery is obtained using the minimum consumption of amine. Composition of exit gas and rich amine leaving absorption column is presented in

**Parameter MEA DEA MDEA**  Section diameter (m) 5.944 6.096 6.401 Max flooding (%) 67.4 13 68.985 68.147 X-sectional area 27.745 29.186 32.178 Section height 29.871 42.999 61.086 Section ΔP(kPa) 2.727 10.114 12.072 ΔP per length (kPa) 0.112 0.288 0.242 Flood gas velocity (m3/m2h) 14798.038 9479.649 9141.451 Flood gas velocity (m/s) 4.111 2.633 2.539

HETP(m) 0.853 0.860 0.873 HETP correlation Frank Frank Frank Packing correlation Robbins Robbins Robbins

> **MEA DEA MDEA** Exit gas Rich amine Exit gas Rich amine Exit gas Rich amine

Gcmpak (metal random) No.\_2

Gempak (metal structured) 2 A

Gempak (metal structured) 0.75 A

N<sup>2</sup> 99.995 0.005 99.982 0.018 99.98 0.02 CO<sup>2</sup> 3.351 96.649 2.062 97.938 30.394 69.606 O<sup>2</sup> 99.991 0.009 99.966 0.034 99.961 0.039 H2O 6.62 93.38 0.459 99.541 0.434 99.566 MEA 0.226 99.774 Nil Nil Nil Nil DEA Nil Nil Nil 100.00 Nil Nil MDEA Nil Nil Nil Nil Nil 100.00

As it can be seen almost all the CO2 in flue gas is recovered by MEA and DEA (above 96 and 97% for MEA and DEA, respectively) through one stage, whereas MDEA amine is observed to be unsuitable for one stage CO2 recovery (about 30% recovery). Rich amine at the bottom of the column is pumped to a heat exchanger then, achieving appropriate thermal specifications, it is introduced into the stripping column. Specifications of stripper for three

Table 4. Upstream and downstream composition of absorption column

2RNH2 + CO2 ↔ RNHCOONH3R (3)

Fig. 9. Flowchart for CO2 capture from flue gases using MEA, DEA and MDEA.

#### **4. Results**

Three different alkanolamines (MEA, DEA, and MDEA) were used in the simulation investigation of CO2 capture in this work. Composition and thermal specifications of feed (flue gas and amine), entering the first tray at the bottom of the absorber are presented in Tables 1 and 2 respectively.


Table 1. Flue gas composition


Table 2. Thermal specification of feed

Many other technologies used for CO2 capture are based on the MEA process, with changes made in either solvent choice or absorption/stripping methodology. Specifications of the absorber for three types of amines are listed in Table 3. Type and amount of packing are selected so that the maximum recovery is obtained using the minimum consumption of amine. Composition of exit gas and rich amine leaving absorption column is presented in Table 4.


Table 3. Specification of absorption column

88 Greenhouse Gases – Capturing, Utilization and Reduction

2RNH2 + CO2 ↔ RNHCOONH3R (3)

Fig. 9. Flowchart for CO2 capture from flue gases using MEA, DEA and MDEA.

Three different alkanolamines (MEA, DEA, and MDEA) were used in the simulation investigation of CO2 capture in this work. Composition and thermal specifications of feed (flue gas and amine), entering the first tray at the bottom of the absorber are presented in

**Component Molar flow rate (kgmol/h) Mol .fraction**  N2 7691.244 0.782 CO2 1208.637 0.123 O2 205.463 0.021 H2O 728.561 0,074 **Sum 9833.906 1.000** 

**Property Flue gas MEA DEA MDEA**  Vapor fraction 1 00 00 00 Temperature *(*°*C)* 45.0 35.0 35.0 *35.0* Pressure (kPa) 130.0 105.5 105.5 105.5 Mass flow (kg/h) 288351.8 596633.4 2010937.5 1990020.5

**4. Results** 

Tables 1 and 2 respectively.

Table 1. Flue gas composition

Table 2. Thermal specification of feed


Table 4. Upstream and downstream composition of absorption column

As it can be seen almost all the CO2 in flue gas is recovered by MEA and DEA (above 96 and 97% for MEA and DEA, respectively) through one stage, whereas MDEA amine is observed to be unsuitable for one stage CO2 recovery (about 30% recovery). Rich amine at the bottom of the column is pumped to a heat exchanger then, achieving appropriate thermal specifications, it is introduced into the stripping column. Specifications of stripper for three types of amines are listed in Table 5.

The Needs for Carbon Dioxide Capture from Petroleum Industry:

Fig. 10. CO2 recovery (%) for three types of amine s process.

significant handicap (Chapel and Mariz, 1999).

process.

considering mechanical aspects.

smaller than other amine plants (about one tenth).

the optimum process.

cannot be used for one stage processes.

A Comparative Study in an Iranian Petrochemical Plant by Using Simulated Process Data 91

for MDEA is less than 70%. It means that MDEA is weaker than two other amines and

The amount of amine consumption for three types of amines is represented in Figure 11. As can be seen MEA process uses much fewer amines than other processes (about one fourth), i.e. this process is superior to other processes considering economic aspects. The low MEA consumption raises the reboiler duty substantially. The required pump power increases even more. Since the reboiler heat duty is the most important key to operating costs, this is a

Fig. 11. The percentage of alkanolamine consumption (Kg/h) for three types of amines

Mechanical and operational characteristics of absorption column for three types of amines are almost the same, except to column height. Height of absorption column for MEA plant (30 m) is considerably lower than DEA (43 m) and MDEA (61 m) plants. Since, column diameter for all plants are the same, it can be concluded that MEA plant is better than others

Figure 12 indicates that, CO2 purity in stripper column effluent is similar to all types of amines (above 97 %). Hence, this parameter could not be used as a criterion for selection of

As it is shown in the Figure 13, required energy of stripper for DEA plant is significantly


Table 5. Specification of stripping column

#### **5. Discussion**

A brief review on the associated problems of CO2 emission, such as health and environment effects and the increasing trend of its emission, indicate the seriousness of the CO2 capture in Iran's energy sector. The Iranian industry sector with about 26% of the total CO2 emissions was the second major contributor in 2008, and the largest source was the petrochemical industry. The progressively increases of the emission along with its negative effects on the environmental impact, makes the capture of this greenhouse gas a very important issue. The observation of the fact that the combustion of fossil energy contributes with about 84 % to the CO2 emission in Iran, the general acceptance of gas in contrast with coal or oil, and the advantages of developed technologies applied in the Iranian petrochemical industry, make it possible to take advantages of the Amine-based CO2 capture in Iran. In order to capture CO2 from flue gas in one of the petrochemical plants in Iran, three different alkanolamines were utilized in this work.

Today, most of the CO2 used by the chemical industry is extracted from natural wells. As the extraction price is close to that for recovery from fermentation and other industrial processes, it may be that soon CO2 recovered from electric energy generation could find a large application in the chemical industry.

To be able to compare the amine processes, the same general configuration of the process, feed composition and flow rate was applied for alkanolamine plant. The amount of CO2 recovery, amine consumption, mechanical and operational characteristics of absorption column, CO2 purity in stripper column effluent, required energy of stripper and mechanical and operational features of stripper were compared for three types of amines.

The amount of CO2 recovery for three types of amines is represented in Figure 10. According to this Figure, CO2 recovery for MEA and DEA are above 96 % while this value for MDEA is less than 70%. It means that MDEA is weaker than two other amines and cannot be used for one stage processes.

90 Greenhouse Gases – Capturing, Utilization and Reduction

**Parameter MEA DEA MDEA**  Section diameter (m) 9.296 5.486 9.906 Max flooding (%) 69.887 50.882 69.777 X-sectional area 67.877 23 .641 77.070 Section height 20.497 18.288 14.922 Section ΔP (kPa) 4.865 16.835 3.242 ΔP per length (kPa) 0.290 ---- 0.266 Flood gas velocity (m3/m2h) 14736.444 ---- 12316.179 Flood gas velocity (m/s) 4.093 ---- 3.421 Estimation of pieces of packing 146080059.333 ---- 1345560.256 Estimation of mass of packing (kg) 292161.187 ---- 310513.905

HETP (m) 0.976 ---- 0.995 HETP correlation Frank Frank Frank Packing correlation Robbins Robbins Robbins

A brief review on the associated problems of CO2 emission, such as health and environment effects and the increasing trend of its emission, indicate the seriousness of the CO2 capture in Iran's energy sector. The Iranian industry sector with about 26% of the total CO2 emissions was the second major contributor in 2008, and the largest source was the petrochemical industry. The progressively increases of the emission along with its negative effects on the environmental impact, makes the capture of this greenhouse gas a very important issue. The observation of the fact that the combustion of fossil energy contributes with about 84 % to the CO2 emission in Iran, the general acceptance of gas in contrast with coal or oil, and the advantages of developed technologies applied in the Iranian petrochemical industry, make it possible to take advantages of the Amine-based CO2 capture in Iran. In order to capture CO2 from flue gas in one of the petrochemical plants in

Today, most of the CO2 used by the chemical industry is extracted from natural wells. As the extraction price is close to that for recovery from fermentation and other industrial processes, it may be that soon CO2 recovered from electric energy generation could find a

To be able to compare the amine processes, the same general configuration of the process, feed composition and flow rate was applied for alkanolamine plant. The amount of CO2 recovery, amine consumption, mechanical and operational characteristics of absorption column, CO2 purity in stripper column effluent, required energy of stripper and mechanical

The amount of CO2 recovery for three types of amines is represented in Figure 10. According to this Figure, CO2 recovery for MEA and DEA are above 96 % while this value

and operational features of stripper were compared for three types of amines.

(plastic) No.\_2 ------- Ballast Rings

(metal). 3&1\_2\_inch

Packing type Levapacking

Iran, three different alkanolamines were utilized in this work.

Table 5. Specification of stripping column

large application in the chemical industry.

**5. Discussion** 

Fig. 10. CO2 recovery (%) for three types of amine s process.

The amount of amine consumption for three types of amines is represented in Figure 11. As can be seen MEA process uses much fewer amines than other processes (about one fourth), i.e. this process is superior to other processes considering economic aspects. The low MEA consumption raises the reboiler duty substantially. The required pump power increases even more. Since the reboiler heat duty is the most important key to operating costs, this is a significant handicap (Chapel and Mariz, 1999).

Fig. 11. The percentage of alkanolamine consumption (Kg/h) for three types of amines process.

Mechanical and operational characteristics of absorption column for three types of amines are almost the same, except to column height. Height of absorption column for MEA plant (30 m) is considerably lower than DEA (43 m) and MDEA (61 m) plants. Since, column diameter for all plants are the same, it can be concluded that MEA plant is better than others considering mechanical aspects.

Figure 12 indicates that, CO2 purity in stripper column effluent is similar to all types of amines (above 97 %). Hence, this parameter could not be used as a criterion for selection of the optimum process.

As it is shown in the Figure 13, required energy of stripper for DEA plant is significantly smaller than other amine plants (about one tenth).

The Needs for Carbon Dioxide Capture from Petroleum Industry:

separation of CO2 from flue gases in this issue.

Malaysia due to their supports during this study.

**7. Acknowledgment** 

0378-3812

**8. References** 

in this study.

A Comparative Study in an Iranian Petrochemical Plant by Using Simulated Process Data 93

chemical absorption technology for CO2 capture in a petrochemical plant has been selected

In the present work, CO2 capture from fuel gases of one of the petrochemical companies in Iran using three alkanolamines (MEA, DEA and MDEA) was simulated and optimized. Specifications of absorber and stripper and composition of exit gas and rich amine leaving absorber were initially reported as simulation results. Then, these alkanolamines were compared considering some parameters such as CO2 capture amine consumption, mechanical and operational characteristics of absorber and stripper, and CO2 purity and energy consumption. It was found that, MEA and DEA are capable to recover almost all of CO2 from flue gases. Amine consumption in an MEA plant is one-fourth of another amine plant where its energy consumption is the same as MDEA plant and ten times larger than DEA plant. Considering mechanical and operational characteristics, it was realized that MEA plant meets economic and aspects better than other amine plants. Finally, taking all parameters into consideration it was deduced that MEA is the best alkanolamine for

The authors of this chapter would like to express their gratitude to Universiti Teknologi

Al-Baghli, N.A.; Pruess, S.A.; Yesavage, V.F. & Selim, M.S. (2001). A Rate-based Model for

Asgari M., DuBois A., et al. (1998). Association of Ambient Air Quality with Children's Lung Function in Urban and Rural Iran, *Archives of Environmental Health*. No. 53. Avami A. & Farahmandpour B. (2008). Analysis of Environmental Emissions and

Blauwhoff, P. M. M.; Versteeg, G. F. & Van Swaaij, W. P. M. (1984). A Study on the Reaction

Bredesena, R.; Jordal, K. & Bolland, A. (2004). High-Temperature Membranes in Power

Bryant S. (2007). Geologic Storage – Can the Oil and Gas Industry Help Save the Planet, *Journal of Petroleum Technology.* September, pp. (98-105), ISSN: 0149-2136 Chapel, D.G. & Mariz, C.L. (1999). Recovery of CO2 from Flue Gases: Commercial Trends,

Energy Information Administration (2000). United States: Iran; Environmental Issues, Apr.

*Science*, Vol. 39, No. 2, pp. (207-25), ISSN 0009-2509

9, pp. (1129–1158), ISSN 0255-2701

4-6, Saskatoon, Saskatchewan, Canada.

2000, http://www.eia.doe.gov/.

the Design of Gas Absorbers for the Removal of CO2 and H2S Using Aqueous Solution of MEA and DEA, *Fluid phase equilibria*, Vol. 185, No. 1-2, pp. (31-43), ISSN

Greenhouse Gases in Islamic Republic of Iran, *WSEAS TRANSACTIONS on ENVIRONMENT and DEVELOPMENT*, Vol. 4, No.4, pp. (303-312), ISSN: 1790-5079

between CO2 and Alkanolamines in Aqueous Solutions. *Chemical Engineering* 

Generation with CO2 Capture. Chemical Engineering and Processing, Vol. 43, No.

presented at the Canadian Society of Chemical Engineers annual meeting October

Fig. 12. CO2 purity (%) for three types of amines process.

Fig. 13. Energy consumption (Kj/h) for three types of amines process.

Operational features of stripper are alike for all amine plants whereas mechanical characteristics are different to a certain extent. Diameter of MEA, DEA and MDEA stripper columns are 9.3, 5.5 and 10 m and heights of them are 20.5, 18.3 and 15 m, respectively. Taking all parameters into account, it can be concluded that the MEA plant is the best choice for separation of CO2 from fuel gases.

The removal of CO2 from flue gases using an amine depends on the gas-liquid mass transfer process. The chemical reactions that permit diffusion of CO2 in the liquid film at the gas-liquid interface enhance the overall rate of mass transfer. Thus, the CO2 removal efficiency in the absorber is a function of various parameters that affect the gas-liquid equilibrium (e.g., flow rates, temperature, pressure, flue gas composition, CO2 concentration, alkanolamine concentration and absorber design). Similarly, the conditions and detailed design of the stripping column affect the energy requirements and overall performance of the system.

MEA is the most frequently used solvent for CO2 absorption, and the greatest advantage of MEA is its relatively high loading. Two moles of MEA are needed for each mole of CO2 absorbed, which represents the maximum equilibrium pickup and fixes the minimum circulation rate of MEA for completely treating a given quantity of acid gas.

#### **6. Conclusions**

In this chapter, the needs for CO2 capturing were raised by presenting the negative health and environmental impacts of CO2 emission in Iran. Direct relationship between fossil-fuel consumption and CO2 emission was demonstrated in this study. Results show that CO2 emission, especially from petrochemical plant, will have to be efficiently reduced. So, chemical absorption technology for CO2 capture in a petrochemical plant has been selected in this study.

In the present work, CO2 capture from fuel gases of one of the petrochemical companies in Iran using three alkanolamines (MEA, DEA and MDEA) was simulated and optimized. Specifications of absorber and stripper and composition of exit gas and rich amine leaving absorber were initially reported as simulation results. Then, these alkanolamines were compared considering some parameters such as CO2 capture amine consumption, mechanical and operational characteristics of absorber and stripper, and CO2 purity and energy consumption. It was found that, MEA and DEA are capable to recover almost all of CO2 from flue gases. Amine consumption in an MEA plant is one-fourth of another amine plant where its energy consumption is the same as MDEA plant and ten times larger than DEA plant. Considering mechanical and operational characteristics, it was realized that MEA plant meets economic and aspects better than other amine plants. Finally, taking all parameters into consideration it was deduced that MEA is the best alkanolamine for separation of CO2 from flue gases in this issue.

#### **7. Acknowledgment**

The authors of this chapter would like to express their gratitude to Universiti Teknologi Malaysia due to their supports during this study.

#### **8. References**

92 Greenhouse Gases – Capturing, Utilization and Reduction

Fig. 12. CO2 purity (%) for three types of amines process.

Fig. 13. Energy consumption (Kj/h) for three types of amines process.

for separation of CO2 from fuel gases.

**6. Conclusions** 

Operational features of stripper are alike for all amine plants whereas mechanical characteristics are different to a certain extent. Diameter of MEA, DEA and MDEA stripper columns are 9.3, 5.5 and 10 m and heights of them are 20.5, 18.3 and 15 m, respectively. Taking all parameters into account, it can be concluded that the MEA plant is the best choice

The removal of CO2 from flue gases using an amine depends on the gas-liquid mass transfer process. The chemical reactions that permit diffusion of CO2 in the liquid film at the gas-liquid interface enhance the overall rate of mass transfer. Thus, the CO2 removal efficiency in the absorber is a function of various parameters that affect the gas-liquid equilibrium (e.g., flow rates, temperature, pressure, flue gas composition, CO2 concentration, alkanolamine concentration and absorber design). Similarly, the conditions and detailed design of the stripping column affect the energy requirements and overall performance of the system.

MEA is the most frequently used solvent for CO2 absorption, and the greatest advantage of MEA is its relatively high loading. Two moles of MEA are needed for each mole of CO2 absorbed, which represents the maximum equilibrium pickup and fixes the minimum

In this chapter, the needs for CO2 capturing were raised by presenting the negative health and environmental impacts of CO2 emission in Iran. Direct relationship between fossil-fuel consumption and CO2 emission was demonstrated in this study. Results show that CO2 emission, especially from petrochemical plant, will have to be efficiently reduced. So,

circulation rate of MEA for completely treating a given quantity of acid gas.


**5** 

Pao-Chi Chen

*Taiwan* 

**Absorption of Carbon Dioxide in** 

In the current stage over 85% of world energy demand is supplied by fossil fuels. Coal-fired plants discharged roughly 40% of the total CO2 are the main contributors in CO2 emissions (Kim & Kim, 2004; Yang et al., 2008). Environmental issues caused by exhaust green house gases (GHG) and toxics have become global problems. Through the past studies of five decades, increased GHG levels in atmosphere is believed to cause global warming, in which CO2 is the largest contributors. International Panel on Climate Change (IPCC) predicts that the CO2 content in atmosphere may contain up to 570 ppmv CO2, causing an increase in mean global temperature around 1.9℃ and an increase mean sea level of 38m (Stewart & Hessami, 2005). Also accompanied is species extinction. Therefore, the importance of removing carbon dioxide from exhaust emissions has been recognized around the world. There are three options to reduce total emission into the atmosphere, i. e., to increase energy efficiency, to use renewable energy, and enhance the sequestration or removal of CO2. However, from the viewpoints of coal-fired plants discharged a lot amount of CO2-gas, CO2 gas needs to be removed from the flue gases of such point sources before direct sequestration. There are several processes for CO2 separation and capture processes, including post-combustion, pre-combustion, oxy-fuel processes, and chemical-looping combustion (Yang et al., 2008). In here, we focus on the treatment of post-combustion

For the removal of exhaust CO2-gas, several methods have been proposed, such as chemical absorption, physical absorption, membrane separation, biochemical methods, and the catalytic conversion method. In addition to these methods, the absorption of carbon dioxide in an alkaline solution with crystallization has also been adopted to explore the removal of carbon dioxide from waste gas (Chen et al., 2008). This approach, with the production of carbonate by means of reactive crystallization, has been found to be effective. In order to remove of CO2 gas, several scrubbers were utilized, such as sieve tray column, packed bed column, rotating packed bed and bubble column. Therefore, how to choose an excellent scrubber becomes significant in the removal of CO2 gas from flue gas. The performances of the scrubbers were always estimated by using overall mass-transfer coefficient. Due to this, they found packed bed with structured packing (Aroonwilas & Tontiwachwuthiku, 1997)

**1. Introduction** 

processes since they are typical coal-fired plants.

**a Bubble-Column Scrubber** 

*Department of Chemical and Materials Engineering Lunghwa University of Science and Technology* 

*Graduate School of Engineering Technology* 

