Review on Methanation âë†â€™ From Fundamentals to Current Projects

Simulation of a NGCC Power Generation Establish for the Product of Electricity from CO₂ Emissions Part I: The Methanation Reactor ()

Abstract

The final goal of this applied research is to simulate a Natural Gas Combined Bike (NGCC) power plant with a CO_two capture unit of measurement. The originality of this investigation is the integration of a methanation process to produce the natural gas of the power plant from the captured CO₂. The objective of this starting time part of the investigation is to simulate a methanation reactor for the production of methane using 1 kg/hr. of captured carbon dioxide containing 95% mol. CO₂ and five% mol. H₂O. To accomplish this goal, Aspen Plus software and the Redlich-Kwong-Soave equation of state with modified Huron-Vidal mixing rules are utilized. Three parameters are considered in guild to maximize the product of CH₄ production: ane) temperature, varying from 250°C to 300°C, 2) pressure varying between 10 atm to forty atm and 3) [H₂/CO₂] ratio which varies between 2 to 6. The maximum product of methane of 0.875 kmol/hr. was obtained for the following operating conditions: [H_ii/CO₂] ratio of iii.5, at relatively low temperature (250°C - 270°C) and high pressures xxx and 40 atm.

Share and Cite:

Daful, A.G. and Dadach, Z.E. (2019) Simulation of a NGCC Power Generation Institute for the Production of Electricity from CO₂ Emissions Office I: The Methanation Reactor. Journal of Power and Free energy Engineering, seven, one-14. doi: 10.4236/jpee.2019.77001.

ane. Introduction

Electricity production is vital for the economic growth of the UAE. All the same, power generation plants contribute profoundly to the annual CO₂ emissions of the country. For example, these plants released about 33% of the 200 1000000 tons of the total CO_two emitted in 2013 [1] . These emissions can be reduced in four main paths: 1) increasing efficiency of industrial plants; 2) carbon Capture and storage; 3) chemical conversion and utilization of CO_two; 4) use of renewable energies. The actual carbon capture and storage (CCS) strategy has a condom problem due to CO_ii leakage from underground and has too no commercial value to attract potential investors.

The utilization of CO_ii emissions as carbon source for the product of chemicals and fuels is the needed path for a more sustainable use of the resources which tin can indeed atomic number 82 to less consumption of carbon-based fossil resources. Outset, carbon dioxide tin be converted into several value-added chemicals following stoichiometric reactions, thermochemical, electrochemical, photoelectrochemical, photocatalytic paths. Nonetheless, the corporeality of products obtained by conversion of carbon dioxide represents but a few percentages of the full global CO_ii emissions. A skilful example is the use of CO_two for the production of urea, which is used primarily as a fertilizer, past reacting ammonia with carbon dioxide [ii] .

The utilization of CO₂ emissions every bit a feed for the synthesis of fuels is more sustainable that their production from conventional paths with low efficiency. In this perspective, the use of carbon dioxide for the product of methanol is investigated in order to reduce carbon dioxide emissions and decrease dependence on fossil fuels [3] . The utilization of carbon dioxide emissions is crucial and beneficial to maintain a long-term and sustainable production of electricity in the United Arab Emirates. Because natural gas (NG) is the cleanest fossil fuel for electricity production, the Natural Gas Combined Wheel (NGCC) power generation plants are the best engineering in order to run across the United Arab Emirates e'er growing free energy needs and reduce its ecology impact. Nevertheless, even with the UAE'south massive total of proved natural gas reserves, the country still needs to import natural gas in gild to meet the free energy market [iv] . Therefore, the production of synthetic natural gas (SNG) by the methanation of carbon dioxide emissions has the potential to both reduce greenhouse gas emissions and mitigate dependence on natural gas.

The product of methane by hydrogenation of carbon dioxide, known equally the Sabatier's reaction, is an of import research topic in many enquiry centers and industrial applications around the earth [three] . The beginning commercial synthetic gas plant opened in 1984 and is the Groovy Plains Synfuel plant in Beulah, Northward Dakota, and USA [iv] [5] . The CO_ii methanation process was initially utilized in club to remove trace carbon oxide from the feed gas for ammonia synthesis [6] . Recently, the CO_ii methanation has gained renewed interest due to its awarding in the so-called power-to-gas technology [7] equally well as biogas upgrading. In power-to-gas applied science, hydrogen produced from backlog renewable free energy is reacted with CO₂ (from power plants, industrial or biogenic processes) and chemically transformed to marsh gas, which can be stored and transported through the well-developed natural gas infrastructure already in place [viii] . The originality of this investigation is the integration of the methanation process with a Natural Gas Combined Cycle (NGCC) ability constitute and a CO_ii capture unit. The produced synthetic natural gas (SNG) will be utilized as a flammable for a Natural Gas Combined Cycle (NGCC) power plant for the production of electricity. The flue gas leaving the Heat Recovery Stream Generator (HRSG) of the power plant volition be treated in a CO_two capture plant. The resulting full-bodied carbon dioxide will be recycled and reutilized as the feed for the methanation process. The beginning objective of this written report is to simulate a methanation reactor integrated with a NGCC power plant and a carbon capture unit of measurement. The imitation constitute volition then be utilized in society to investigate the corporeality of electricity produced using i kg/60 minutes. of captured carbon dioxide containing 95% mol. CO₂ and 5% mol. H_twoO.

2. Fundamentals

The Sabatier process is a highly exothermic reaction that releases 165 kJ/mole for the reaction with carbon dioxide and 201kJ/mole for the reaction with carbon monoxide [six] . Information technology is a thermodynamically favorable reaction (∆G = −113, 5 kJ/mole) in a big range of temperatures and pressures [vi] . On the other hand, the reduction of carbon dioxide to methyl hydride is kinetically express [9] . Thus, a catalyst is needed to reach acceptable conversion rates and selectivity to methane. Observed past Paul Sabatier over a Nickel catalyst, the exothermic equilibrium reaction has the following equation [seven] :

${\text{CO}}_{\text{two}}+{\text{4H}}_{\text{2}}\leftrightarrow {\text{CH}}_{\text{four}}+{\text{2H}}_{\text{2}}\text{O}$ (1)

Many general paths take been proposed for the simple chemical reaction (one). In the virtually popular two-steps machinery: carbon dioxide is first converted to carbon monoxide in an endothermic reverse water-gas shift (RWGS) reaction followed by the exothermic methanation of carbon monoxide for production methane [eight] .

Contrary Water-Gas Shift (RWGS):

${\text{H}}_{\text{2}}+{\text{CO}}_{\text{2}}\leftrightarrow \text{CO}+{\text{H}}_{\text{two}}\text{O}\left[\Delta H=41\text{kJ}/\text{mol}\right]$ (two)

Methanation:

${\text{3H}}_{\text{ii}}+\text{CO}\leftrightarrow {\text{CH}}_{\text{4}}+{\text{H}}_{\text{2}}\text{O}\left[\Delta H=-\text{2}0\text{half dozen}\text{kJ}/\text{mol}\right]$ (iii)

Since the reaction is exothermic, the optimal operating window for CO₂ methanation is at depression temperatures, where the conversion of CO₂ and CH₄ selectivity can achieve shut to 100% [7] . On the other mitt, from the kinetic indicate of view, the reaction rate increases with temperature. However, increasing the temperature above 500˚C is favorable for the RWGS (opposite water–gas shift) reaction [7] . In the catalytic methanation reactor, a temperature increase can too generate a thermal rails and catalyst deactivation. To overcome this situation, isothermal reactor, adiabatic reactor with recycling and fluidized bed reactor and add-on of steam are proposed in the literature [10] [11] [12] .

Moreover, According to le Chatelier's principle, the CO₂ methanation is favored at elevated pressures. A force per unit area of 10 to 30 atm. is considered mild in terms of stress on the catalyst and should therefore not cause sintering for the goad [13] . Usually, industrial applications for the methanation of CO and CO₂ take place at reactors of more than to twenty atm. of force per unit area in gild to ensure high conversion rates of reactants and high purity of methane [14] . The most widely studied textile for the hydrogenation of CO₂ is Nickel (Ni). The Ni catalyst is usually supported past another material that plays an of import role in the reaction procedure. The textile affects the catalytic activity and selectivity towards the final products [xv] . The materials used typically every bit supports in Nickel catalysts are oxides. Like TiO_ii, SiO₂, Al₂O_three, CeO_two and ZrO₂₃ [xvi] .

The simplest model studied is a power police (PL) solely because the reaction orders of hydrogen and carbon dioxide [17] :

$r=\mathrm{grand}\cdot p_{{\text{H}}_{\text{2}}}^{n{\text{H}}_{\text{ii}}}\cdot p_{{\text{CO}}_{\text{2}}}^{\mathrm{northward}{\text{CO}}_{\text{2}}}\left(1-\frac{p_{{\text{CH}}_{\text{4}}}\cdot p_{{\text{H}}_{\text{2}}\text{O}}^2}{p_{{\text{H}}_{\text{2}}}^{\mathrm{four}}\cdot p_{{\text{CO}}_{\text{2}}}\cdot K_{eq}}\right)$ (iv)

where the equilibrium constant (K_eq) could too exist approximated by the empirical formula [eighteen] :

$K_{eq}=137\cdot T^{-\mathrm{three.998}}\cdot \exp \left(\frac{158.7\text{kJ}/\text{mol}}{R\cdot T}\right)$ (v)

However, since the methanation process is a catalytic reaction, the rate equation is usually derived from the Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach, which is one of the most normally used ways of deriving charge per unit expressions for fluid solid catalytic reactions. In this approach, the rate equations take into account the surface coverage of the relevant adsorbed species. A charge per unit-determining step is then assumed for the reaction mechanisms and the elementary footstep is considered every bit the slowest reaction step responsible for the overall rate. All other reaction steps are regarded to exist in equilibrium or irreversible [sixteen] . Every bit shown in Equation (vi), the resulting rate equations include the "driving forcefulness" in terms of partial force per unit area of the gas stage species and the "adsorption term", which summarizes the retarding furnishings of the adsorbed reactants and products:

$r=\frac{\text{kineticterm}\times \text{Drivingforce}}{\text{Adsorptionterm}}$ (6)

For a typical range of temperatures (280˚C -380˚C) used for the study of the Sabatier'due south reaction, the values of the equilibrium constant are modest enough (Chiliad_eq = 55.two - xv.1) to include the reverse reaction in the rate of reaction [x] . For the 16 models presented in the literature, the generalized charge per unit equation for the WGS with an adsorbed H₂O can exist written as [sixteen] :

$r_{\text{WGS}}=\frac{k_2\left(K_{\beta }\cdot p_{\text{CO}}\cdot p_{{\text{H}}_{\text{ii}}\text{O}}-\frac{p_{{\text{CO}}_{\text{two}}}\cdot p_{{\text{H}}_{\text{ii}}}}{K_{eq}}\right)}{{\left(\mathrm{i}+\sqrt{G_{{\text{H}}_{\text{2}}}}\cdot p_{{\text{H}}_{\text{2}}}+K_{\text{CO}}\cdot p_{\text{CO}}+K_{{\text{H}}_{\text{ii}}\text{O}}{p}_{{\text{H}}_{\text{2}}\text{O}}+{\mathrm{1000}}_{Cy}\cdot p_{\text{CO}}^{\mathrm{east}}\cdot p_{{\text{H}}_{\text{ii}}}^f\right)}^2}$ (7)

On the other mitt, the values of the equilibrium are very large of the methanation reaction are very big (Thousand_eq > 5.6 × 10⁴ bar^{− 2}) at temperatures beneath 380˚C. The reverse reaction (methane steam reforming) tin can be therefore be neglected in the rate of reaction [16] . Assuming H₂O as adsorbed species, the rate can exist written as

$r_{\text{methanation}}=\frac{k_1\left({\mathrm{One\; thousand}}_{C,\mathrm{10}}\cdot {\mathrm{One\; thousand}}_{{\text{H}}_{\text{2}}}^a\cdot p_{\text{CO}}^b\cdot p_{{\text{H}}_{\text{2}}}^C\right)}{{\left(\mathrm{i}+\sqrt{{\mathrm{Thou}}_{{\text{H}}_{\text{2}}}}\cdot p_{{\text{H}}_{\text{ii}}}+K_{\text{CO}}\cdot p_{\text{CO}}+K_{{\text{H}}_{\text{2}}\text{O}}{p}_{{\text{H}}_{\text{ii}}\text{O}}+{\mathrm{Grand}}_{Cy}\cdot p_{\text{CO}}^e\cdot p_{{\text{H}}_{\text{ii}}}^f\right)}^m}$ (8)

3. Literature Review

The furnishings of temperature, pressure, ratios of H₂/CO and H₂/CO₂, and the addition of other compounds in the feed gas on the conversion of carbon monoxide and carbon dioxide, methane selectivity and yield, as well equally carbon degradation were investigated in the literature [16] [18] [19] [xx] . The greatest claiming involved in methanation is the temperature command of the exothermic reactions, pregnant an efficient heat removal. In this perspective, the effects of temperature on the process were investigated by Jiajian Gao, et al. [18] .

For the methanation of carbon monoxide (Effigy ane(a)), the products mainly contain methane, h2o and little carbon dioxide past-product at low temperatures (200˚C - 300˚C) without deposition of carbon. With an increase in reaction temperature, the mole fraction of CH₄ decreases, whereas the unreacted carbon monoxide, hydrogen, carbon dioxide, and deposited carbon increase simultaneously [18] . Methane and water are the primary products of methanation of carbon dioxide (Effigy 1(b)) at low temperatures (200˚C - 250˚C). Raising the reaction temperature above 450˚C, results in the increase of the carbon monoxide by-product, due to the reverse water-gas shift reaction, and meanwhile, unreacted carbon dioxide and hydrogen also increase, along with a subtract in the methane yield [18] . The effects of pressure level on the CO_two conversion were also investigated. The positive effects of increasing the force per unit area are more important at higher temperatures [17] .

In gild to investigate the thermodynamic of the methanation reaction, G. Granitsiotis [21] constructed a Gibbs reactor based using the software Aspen Plus. The reactor was designed based on the experimental atmospheric condition. The force per unit area of the reactor was set at i bar and the composition of the inlet stream was 76.19% N₂, 19.05% H₂ and 4.76% CO_ii. The effects of temperature on the conversion of carbon dioxide were studied. The simulation results betoken that the conversion starts decreasing from 120˚C and the value of conversion at 400˚C is 77.08%. The outputs of the simulation also indicate that, to a higher place the temperature of 200˚C, the pressure influences immensely the performance of reaction.

For case, Kopyscinski [16] presented a LHHW kinetic model of the methanation reaction in a fixed bed reactor using a commercial catalyst Ni/Al_twoO₃ (50 wt% Ni/Al₂O_iii, with a BET (Brunauer-Emmett-Teller) surface area equal to 183 1000^two/1000. Using the same properties of the goad, Hanaâ Er-rbib and Chakib Bouallou modified the equations representing the model in guild to adjust the kinetic model to meet Aspen plus™ requirements. The simulation of the methanation process consisted of three adiabatic reactors with intermediate cooling at 280˚C and i.5 MPa and a recycle ratio of three [nineteen] . The charge per unit for the Water-Gas Shift reaction was described by [19] :

$\begin{array}{l}{R}_{\text{WGS}}\left(\text{mol}/\text{kg}\cdot \text{catalyst}\cdot \text{southward}\right)\\ =\frac{k_2\cdot {\mathrm{ten}}^{-3}\cdot \left({\mathrm{Yard}}_{\mathrm{three}}{p}_{\text{CO}}\cdot p_{{\text{H}}_{\text{2}}\text{O}}\cdot p_{{\text{H}}_{\text{two}}}^{-0.5}-K_4\cdot p_{{\text{CO}}_{\text{ii}}}\cdot p_{{\text{H}}_{\text{2}}}^{\mathrm{0.five}}\right)}{1+K_1{p}_{\text{CO}}^{0.5}+M_2{p}_{{\text{H}}_{\text{ii}}\text{O}}^1{p}_{{\text{H}}_{\text{2}}}^{-0.5}}\end{array}$ (9)

where

$k_2\left(\text{mol}/{\text{bar}}^{\text{1}\text{.5}}\right)=9.62\times {\mathrm{x}}^{14}\times \exp \left(\frac{-161740}{RT}\right)$ (10)

The charge per unit of the carbon monoxide methanation process was represented by the equation [nineteen] :

$R_{\text{Methanation}}\left(\text{mol}/\text{kg}\cdot \text{catalyst}\cdot \text{s}\right)=\frac{k_1\cdot {10}^{-\mathrm{iii}}{\mathrm{Thou}}_{\mathrm{one}}{p}_{{\text{H}}_{\text{two}}}^{0.5}{p}_{\text{CO}}^{0.5}}{\mathrm{i}+K_{\mathrm{one}}{p}_{\text{CO}}^{0.5}+K_2{p}_{{\text{H}}_{\text{2}}\text{O}}^1{p}_{{\text{H}}_{\text{2}}}^{-0.5}}$ (11)

where

${\mathrm{grand}}_{\mathrm{one}}\left(\text{mol}/\text{kg}\cdot \text{catalyst}\cdot \text{s}\right)=3.34\times {\mathrm{ten}}^{\mathrm{half\; dozen}}\times \exp \left(\frac{-74000}{RT}\right)$ (12)

In Equations (half-dozen) to (9), the force per unit area is expressed in Pa and the temperature in One thousand. The equilibrium constants were presented by [nineteen] :

$\ln \left(K_i\right)=A_i+\frac{B_i}{T}$ (thirteen)

The values of A_i and B_i are given in Tabular array 1:

This kinetic model operates in a temperature range of [473 - 673] Thou and high force per unit area [19] . The methanation of carbon monoxide was simulated past Hanaâ Er-rbib and Chakib Bouallou using Aspen plus software. The process consisted of three adiabatic reactors with intermediate cooling at 280˚C and ane.5 MPa. and a recycle ratio of three [15] . Information technology is found that for storing 10 MW of renewable electricity, methanation unit is composed of three adiabatic reactors with recycle loop and intermediate cooling at 553 Thousand and 1.5 MPa. The methanation unit of measurement generates 3778.half dozen kg/h of steam at 523.2 K and 1 MPa (13.67 MW). The model was validated past comparing the simulated results of gas limerick (CH₄, CO, CO₂ and H₂) with industrial information.

J. Porubova et al. [xx] studied three procedure models of the methanation of carbon dioxide using the Aspen Plus^® program: 1) adiabatic methanation; two) adiabatic methanation scheme of the CO₂ extraction and three) Isothermal methanation. For the 2 adiabatic processes, a heat exchanger was added upstream of

Table ane. Parameter values for the equilibrium constants.

each of the three reactors. In order to control the temperature, it was besides necessary to have a partial gas recirculation downstream of the showtime methanation reactor. For the adiabatic reaction, CO_two concentration had a significant impact on the methanation reaction. On the other hand, In the case of isothermal methanation, an increment of CO₂ concentration only affected the flow of carbon monoxide, and other parameters, such as yield of marsh gas and hydrogen, remained unchanged [20] . It was concluded that at constant temperature, CO₂ concentration does not affect the efficiency of the methanation process.

The aim of this start part of this study is to simulate the methanation procedure in an adiabatic Plug flow (PF) reactor. The model incorporates the catalytic reaction kinetics for the methanation reaction. The furnishings of temperature, pressure level and H₂/CO₂ ratio on the yield of methyl hydride will be investigated. In the 2d function of this investigation, the produced constructed natural gas (SNG), based on the optimum operating atmospheric condition, volition be utilized as flammable for a Natural Gas Combined Bike (NGCC) power plant for the product of electricity. The flue gas leaving the Heat Recovery Stream Generator (HRSG) of the power institute will be treated in a CO_two capture establish. The resulting concentrated carbon dioxide will exist recycled and reutilized as the feed for the methanation procedure. It volition be assumed, in this investigation, that the hydrogen gas needed for the methanation reaction is provided by a Reforming Catalytic Reactor followed by a sweetening process to remove the acid gases.

iv. Simulation Tool and Selection of Operating Weather condition

Aspen Plus^® model of the methanation process is developed and false in this piece of work. The thermodynamic and send properties of the following Compounds, Water (H_twoO), carbon dioxide (CO₂), methane (CH₄), hydrogen (H2) and carbon monoxide (CO) are calculated using a property method of RKSMHV2 along with their all needed binary interaction parameter values. The RKSMHV2 property method is based on the Redlich-Kwong-Soave equation of state with modified Huron-Vidal mixing rules. This model is used for mixtures of non-polar and polar compounds, in combination with light gases. The kinetic charge per unit equations for the methanation and water gas shift reaction are considered as shown in Equations (2)-(10). An adiabatic fixed bed reactor is modeled on a Plug Flow Reactor (PFR), as shown in Figure 1.

3 parameters are considered to study for the outcome of CH₄ product: ane) temperature, 2) pressure and iii) [H₂/CO₂] ratio. The post-obit range of values was selected for each parameter based on operating weather reported in literature [5] [17] [22] .

ane) The pressure of the methanation reaction varies from 10 atm to 40 atm.

2) The temperature of the methanation reaction varies from 250˚C to 300˚C.

3) The amount of H₂ fed for the methanation reaction with respect to the CO₂ feed is measured as H₂ to CO_two ratio (H_ii:CO₂ ratio) varies from 2 to half dozen.

As discussed in the introduction section of this paper, the imitation establish will exist utilizing a captured carbon dioxide containing 95% mol. CO₂ and 5% mol. H₂O, where one kmol/hour. of the mixture is used as a base of operations for the simulation.

5. Analysis of Simulation Results

The performance of the methanation reactor is measured past the production charge per unit of CH₄ in kmol/hour. Variation of the three cited operating weather condition are utilized in order to obtain the maximum production of methane. As the methanation reaction is strongly exothermal, the control of the heat of reaction is a key task when designing methanation. 1) The temperature of the reaction is considered to vary 250˚C to 300˚C with an increment of 10˚C. two) The reaction pressure is considered to be 10 atm, 20 atm, thirty atm, xl atm. 3). The tertiary parameter (ratio of moles of H₂ fed relative to the CO_two present), varies from 2 to 6. The simulation results of the present work are shown in from Figure ii to Figure 7. The resulted

Figure one. Flowsheet of a plug flow reactor for methanation reaction.

Figure ii. Molar flow of CH_iv produced at different temperature and force per unit area for the [H₂/CO₂] = 2.

Figure three. Molar flow of CH₄ produced at different temperature and pressure level for [H₂/CO₂] = 2.5.

Figure iv. Molar catamenia of CH₄ produced at dissimilar temperature and pressure level for [H₂/CO₂] = iii.

molar flowrates of CH_iv for dissimilar ratios of H_two:CO₂ are obtained for a feed flowrate 1 kmol/hr of carbon dioxide containing 95% mol. CO₂ and 5% mol. H₂O, which is used as a base for the simulation.

The CH_four molar flow in kmol/hr produced if the H₂ feed to CO₂ ratio is 2.0 shown in Figure 4. The corporeality of CH₄ produced per kmol/hr of CO₂ fed is approximately equal to 0.v kmol/hr. Similarly, the CH₄ molar flowrates in kmol/hr produced per kmol/hour of CO₂ for H₂ to CO₂ ratios of 2.5, three.0 and three.5 are shown in Figures v-vii respectively. On average the amounts of CH_iv produced when the H₂ to CO_ii ratios of 2.5, three.0 and 3.5 are 0.625, 0.75 and 0.875 kmol/hr, respectively. It'south observed that increasing the H_two to CO₂ ratio in the feed increases the production rate of methane (CH₄) as is depicted in Figure 4 through Figure 7.

Figure 5. Molar flow of CH_iv produced at different temperature and pressure level for [H₂/CO_two] = 3.five.

Effigy 6. Molar flow of CH₄ produced at dissimilar temperature and pressure for [H_ii/CO₂] = iv.

Effigy 7. Molar catamenia of H₂ produced at unlike temperature and pressure for [H₂/CO_ii] = iv.

Equally the product (CH₄) will be used equally fuel, it should free of any H_ii, because of its explosive nature. The product (CH₄) stream is costless of H₂, for H_ii to CO₂ ratios are less than iv. If the H₂ to CO₂ ratio is increased to four and above, there will exist a considerable amount of H_two in the product stream. The molar menstruation of CH₄ produced per kmol of CO₂ for H₂ to CO₂ ratio of four.0 is shown in Figure 6, which is approximately 0.95 kmol/60 minutes. The associated amount of H₂ in the product side for H_ii to CO₂ ratio of 4.0 shown in Figure 7 that is about 0.2 kmol/60 minutes. Further increase of the H₂ to CO₂ ratio increases the amount of H₂ in the product stream (not shown hither for the ratio of higher than 4). As the CH₄ production will be used as fuel, it needs to be gratuitous of H_two because of the explosion nature of H₂. Thus, the optimal ratio of H_two to CO_ii in the feed stream is 3.five that gives the maximum possible amount of CH₄ with no H₂. These simulation results are in agreement with Koschany [17] , where the CO_ii to CH₄ conversion is approximately 100% for H₂ to CO₂ ratio of 4 at depression temperatures 200˚C - 300˚C.

The molar fraction of different components in the production stream is analyzed for unlike temperatures and pressures considered in this simulation. The corporeality of CH₄ is observed to increases upon increasing the H₂ to CO₂ tooth ratio, a similar tendency is observed on the amount of water produced. The average tooth fraction of components in the product stream is shown in Figure viii. The amount of CO_ii is observed to decrease upon increasing H_ii to CO_ii molar ratio. The amount of CO is negligibly small in the product stream, not shown in Figure 8. These results are in skillful agreement with results reported in the literature by J. Gao et al. [18] and R. Stefan et al. [5] for the considered range of temperatures and pressures.

Effigy 8. Average molar fraction CH_four, H₂O and CO₂ in the product stream for [H_2/CO₂] molar ratios = ii.0, 2.5, 3.0, and 3.v at the range of temperature and pressure considered.

half dozen. Conclusion

The present piece of work represents the offset part of the simulation of an NGCC Power Plant for the product of electricity from CO₂ emissions. In this paper, the feed of the methanation reactor is the CO₂ stream from the capture unit of the power plant. The optimal conditions of methanation process are identified through the present simulation studies. Based on the simulation results, The [H₂/CO₂] ratio is the most influential parameter that highly affects the production rate of CH₄. Information technology is found that the production of CH₄ is directly proportional to the [H₂/CO₂] ratio at the unlike temperatures and pressures under consideration. Nonetheless, increasing the H₂ to CO_ii ratio college than iii.5 results in the presence of H₂ in the product stream, which is non recommended due to safety in the plant. Thus, the optimum corporeality of CH₄ is obtained for [H_two/CO_2] ratio equal to 3.5. Moreover, low temperature (250˚C - 270˚C) and loftier pressures [30 - 40 atm] as well raise the production of methyl hydride.CH₄ production.

Acknowledgements

The authors would like to give thanks the College Colleges of Engineering (UAE), for supporting this applied research.

Conflicts of Interest

The authors declare no conflicts of involvement regarding the publication of this paper.

References

[ane]	Todorova, V. (2015) UAE Released 200 1000000 Tonnes of Greenhouse Gases in 2013. The National (UAE).
[2]	Krase, N.W. and Gaddy, V.L. (1922) Synthesis of Urea from Ammonia and Carbon Dioxide. Periodical of Industrial and Applied science Chemistry, 14, 611-615. https://doi.org/10.1021/ie50151a009
[three]	Nie, Ten., et al. (2018) Mechanistic Understanding of Alloy Upshot and Water Promotion for Pd-Cu Bimetallic Catalysts in COtwo Hydrogenation to Methanol. ACS Catalysis, 8, 4873-4892. https://doi.org/10.1021/acscatal.7b04150
[4]	Li, W., et al. (2018) A Short Review of Contempo Advances in CO2 Hydrogenation to Hydrocarbons over Heterogeneous Catalysts. RSC Advances, 8, 7651-7669. https://doi.org/10.1039/C7RA13546G
[five]	Rönsch, South., et al. (2016) Review on Methanation—From Fundamentals to Current Projects. Fuel, 166, 276-296. https://doi.org/10.1016/j.fuel.2015.10.111
[6]	Vannice, M.A. (1982) Catalytic Activation of Carbon Monoxide on Metal Surfaces. In: Anderson, J.R. and Boudart, M., Eds., Catalysis: Scientific discipline and Applied science, Springer, Berlin, Heidelberg, 139-198. https://doi.org/x.1007/978-three-642-93223-6_3
[7]	Jürgensen, 50., Ehimen, Eastward.A., Born, J. and Holm-Nielsen, J.B. (2015) Dynamic Biogas Upgrading Based on the Sabatier Process: Thermodynamic and Dynamic Process Simulation. Bioresource Engineering, 178, 323-329. https://doi.org/10.1016/j.biortech.2014.x.069
[eight]	Stangeland, Yard., Kalai, D. and Yu, Z. (2017) CO2 Methanation: The Effect of Catalysts and Reaction Conditions. Energy Procedia, 105, 2022-2027. https://doi.org/x.1016/j.egypro.2017.03.577
[9]	Götz, M., et al. (2014) Country of the Art and Perspectives of CO2 Methanation Process Concepts for Ability-to-Gas Applications.
[10]	Sun, Fifty., Luo, K. and Fan, J. (2018) Production of Synthetic Natural Gas by CO Methanation over Ni/Al2O3 Catalyst in Fluidized Bed Reactor. Catalysis Communications, 105, 37-42. https://doi.org/10.1016/j.catcom.2017.11.003
[xi]	Sudiro, One thousand., Zanella, C., Bressan, L., Bertucco, A. and Fontana, 1000. (2009) Synthetic Natural Gas (SNG) from Petcoke: Model Evolution and Simulation. Chemical Engineering Transactions, 17, 1251-1256.
[12]	Topsøe, H. (2009) From Solid Fuels to Substitute Natural Gas (SNG) Using TREMP. Technical Report, 8.
[xiii]	Gao, J., et al. (2012) A Thermodynamic Analysis of Methanation Reactions of Carbon Oxides for the Product of Synthetic Natural Gas. RSC Advances, 2, 2358-2368. https://doi.org/10.1039/c2ra00632d
[14]	Schaaf, T., Grünig, J., Schuster, Thou.R., Rothenfluh, T. and Orth, A. (2014) Methanation of COii-Storage of Renewable Energy in a Gas Distribution Arrangement. Energy, Sustainability and Society, 4, two. https://doi.org/10.1186/s13705-014-0029-i
[15]	Wang, W. and Gong, J. (2011) Methanation of Carbon Dioxide: An Overview. Frontiers of Chemical Engineering in China, 5, 2-x. https://doi.org/10.1007/s11705-010-0528-3
[16]	Imriska, J. (2010) Production of Synthetic Natural Gas in a Fluidized Bed Reactor.
[17]	Koschany, F., Schlereth, D. and Hinrichsen, O. (2016) On the Kinetics of the Methanation of Carbon Dioxide on Coprecipitated NiAl(O)x. Applied Catalysis B: Environmental, 181, 504-516. https://doi.org/x.1016/j.apcatb.2015.07.026
[18]	Gao, J., Liu, Q., Gu, F., Liu, B., Zhong, Z. and Su, F. (2015) Recent Advances in Methanation Catalysts for the Production of Constructed Natural Gas. RSC Advances, 5, 22759-22776. https://doi.org/ten.1039/C4RA16114A
[19]	Er-rbib, H. and Bouallou, C. (2014) Modeling and Simulation of CO Methanation Procedure for Renewable Electricity Storage. Energy, 75, 81-88. https://doi.org/10.1016/j.energy.2014.05.115
[twenty]	Porubova, J., Bazbauers, Thousand. and Markova, D. (2011) Modeling of the Adiabatic and Isothermal Methanation Procedure. Environmental and Climate Technologies, 6, 79-84. https://doi.org/x.2478/v10145-011-0011-five
[21]	Granitsiotis, M. (2017) Methanation of Carbon Dioxide Experimental Inquiry of Separation Enhanced Methanation of CO2. 86.
[22]	Lim, J.Y., McGregor, J., Sederman, A.J. and Dennis, J.S. (2016) Kinetic Studies of CO2 Methanation over a Ni/γ-Al2O3 Catalyst Using a Batch Reactor. Chemical Engineering science, 141, 28-45. https://doi.org/10.1016/j.ces.2015.10.026

heckexas1941.blogspot.com

Source: https://www.scirp.org/journal/PaperInformation.aspx?PaperID=93494

Share this post