Analysis Of Fischer Tropsch Synthesis Process: Production Of Synthetic Fuel Question and Answer

Key Steps and Calculations in Fischer Tropsch Fuel Production

Question 1: Identification of the Raw Materials

The process associated with the production of various types of synthesis gases or syn-gas has now increased over the past few years. These syn-gas primarily contain two main particles which are H2 and CO. Although these syn-gases possess a vital amount of H2O and CO2 also. It was found that these synthesis gases are the primary components of the production of a wide variety of synthetic fuels and chemicals (Bahmanpour et al. 2021). These syn-gas are different from other gases which are produced within low-temperature processes. The identification process of raw materials which are essential for the production of these syn-gas required the proper analysis of the characteristics of these gases. It was examined that the different characteristics of the syn-gas have the capability to grow different consequences which is also related to the gathering of raw materials.

The primary aspect that was identified as most crucial for the selection of raw materials for the production of synthetic gases is the composition of syn-gas and its calorific importance.

Figure 1: Composition of syngas

The compositions of these syn-gas are contained by the development of various factors such as the gasifiers, size of the production, fed stocks, catalysts etc (dos Santos and Alencar, 2020). It can be understood with the help of this above-mentioned figure that the primary component is Nitrogen having 53% of the total volume also CO which has 24% of the total volume.

Raw Materials

The development and production of the syn-gas include a wide variety of components such as Natural gases, coal and also biogases. The most used natural gas which is used for the production of synthetic gases is the fed stocks. These are mainly different types of energies which are gathered from different fossils (Andrei et al. 2020). The primary component of these feedstocks is Methane (CH4). Coal is also widely used as the raw material in various production factories of syn-gas. With the help of the Coal-gasification process fuel industries collect H2 and CO which are the primary components of the syn-gas. The other raw materials which can be used for the manufacture of syn-gas are the biomass. These biomasses are different types of biological components which are used for the development of biofuels and biogases for energy generation. Examples of these biomasses include algae biomass, corps biomass, municipal wastes etc.

These above-mentioned raw materials are analyzed as potential raw materials for synthetic gases and fuel production with the help of the Fischer Tropsch technology.

Question 2: Descriptions of Possible Reactions and Explanation of Required High-Temperature

The process and techniques are associated with the development and manufacturing process of various synthetic gases including the utilization of the steam reformer process. From the very beginning, the production of syn-gas contains the use of methane's (CH4) as the primary raw material. The development of syn-gas requires the process of a steam reformer or more specifically methane steam reformer (Liu et al. 2020). The process of steam reformer with the help of methane includes a wide variety of chemical reactions such as reactions of hydrocarbons with H2O. The primary objective of this steam reformer process produce hydrogen which is a primary component of syn-gas. It was examined that this specific method of steam reformer includes three different endothermic reactions. Although, the starting of the steam reformer process requires the development of the Pre-reforming procedure. This particular technique is used for breaking down assorted components such as propane and butane into methane (CH4) for the steam reformer system.

Steam Reformer Possible Reactions

• The first reaction which might happen in the steam reformer procedure with the help of CH4 is the water-gas transformation reaction.

CH4 + H2O= CO + 3H2

In this particular reaction, the methane molecules are getting engaged with a water molecule producing one molecule of Carbon Monoxide (CO) and three molecules of hydrogen (H2). For this particular water-gas transformation reaction water is used in the vaporized form (Condori et al. 2021). It was identified that this specific reaction is very widely used by various industries for the production of ammonia and methanol which are the primary fuels which are the primary examples of synthetic fuels.

• However, there can be different additional reactions that might happen in the procedure of steam reformer with the help of Methane (CH4). This second additional reaction can be the subclass of the water-gas transformation reaction.

CH4 + H2O= CO + H2

In this particular reaction, the primary components are the same which are vaporized water (H2O) and Methane (CH4) (Sukma et al. 2022). However, the developed product contains only one molecule of Hydrogen (H2). It was examined that this specific reaction happens because of the ΔH value which is -41 kJ/mol.

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• The third possible reaction to the stream reforming process including Methane contains the DSR reaction which stands for Direct Stream Reforming.

CH4 + 2H2O= CO + 4H2

In this specific reaction, one molecule of Methane Compound engaged with two molecules of vaporized water which forms one molecule of Carbon Monoxide and four molecules of Hydrogen compound. This specific reaction diversified from the other two reactions because of its ΔH value which is 165 kJ/mol.

These three reactions are analyzed as the most probable chemical reactions that might occur during the production of syn-gases using the steam reforming process of Methane (CH4).

Explanation of the Required High Temperature (>800 °C)

It was examined that the procedures which are associated with the steam reforming techniques are connected with the production of syn-gases. The process of steam reforming is primarily used during the manufacture of syn-gases in industries. These specific methods are used for the reformation of various types of natural gases such as Methane (CH4). With the help of these approaches, a syn-gas production industry breaks down Methane into Carbon Monoxide and Hydrogen (Chang et al. 2023). These biochemical reactions need a very high amount of heat because these are endothermic reactions. It was found that methane contains a very extensive amount of H/C ratio for this specific reason the reforming process of methane can't be done using 200-300 °C temperature. It requires a temperature of more than >800 °C so that it can effectively break the hydrocarbon bonds which are present in the methane compound properly (C-H). Because of these above-mentioned reasons, this optimum temperature was needed for the development of syn-gases.

Question 3: Identification of Steam Reformer Design

A proper steam reformer system includes a wide variety of factors which are associated with the gasification process and the heat generation process (>800 °C) which is the primary factor for the endothermic reactions (Meloni et al. 2020). Various small-scale power plants which produce syn-gases with the help of methane steam reforming methods include the traditional steam reforming procedure. These specific steam reformers possess a bar pressure between the range of 300 and 600 psi. On the other hand, the minimum temperature required for an effective steam reformer includes 800 to 900 °C.

Steam Reformer Design

• The first component of a steam reformer which will be utilizing the methane compound is the combustion engine. It was examined that with the help of a proper combustion engine a fuel gas plan can utilize the greenhouse gases which are present in the air. With the help of a combustion engine, the steam reformer can manage the waste product in the air (Niu et al. 2020). The reformation process of methane can be done with an effective combustion engine by developing non-methane hydrocarbons into carbon monoxide and hydrogen which is also a plus point of an efficient steam reformer design.
• The second component of the steam reformer will be the cell fuel mechanism. Different types of fuel production plans use fuel cells to provide different types of components to the primary steam reactor.

Figure 2: Gasification Chamber

• The third and most crucial element of an effective steam reformer is the gasification chamber. In this chamber, the methane and other natural gases which are present in biomasses are converted into Carbon Monoxide and Hydrogen compounds (Quirino et al. 2020). This particular chamber consists of four different parts which are the biomass input section, gasification bed, heat generators, and cyclone. This specific section is used for the production of high heat >800 °C for the steam reforming process.

These above-mentioned structural designs will be the most effective and efficient steam reformer which can be used for this specific fuel generation project.

Question 4: Analysis of the Required Power for the Steam Reformer

The calculations of the required power level for the Steam Reformer include various types of identification such as molar value calculation, molar mass conversion etc.

The primary reaction of the stream reaction process includes Methane (CH4)

CH4 + H2O= CO + 3H2

For the manufacture of syn-gas using Methane (CH4) 100 standard m3 reformate/hour we need to calculate the mole values by converting the total volumes of biomass. It can be done using ideal gas laws (n = PV/RT).

Therefore, (1 atm)*(100 m3)/ (0.082 L atm/mol/K)*(273 K) = (100/22.83) = 4.28 mol

It was identified with the reactions that the CO and H2 are produced in a ratio of 1:3. We can calculate their molar values using this ratio (Zheng et al. 2023).

CO (n) = (4.28/4) = 1.07

1.07*3 = 3.21 mole

Mole value of methane (CH4) = 1.07 mole.

Now we need to convert the mole values into total mass values for the identification of required power levels.

Mass of Methane = (1.07 * 16.043 * 1000) = 17166 g = 17.166 kg

As it was analyzed one mole of methane has a mass of 16.23 grams. It is used in this particular calculation.

On the other hand, we need to also calculate the mass value of water using the same formula.

Mass of Water = (1.07 * 18 * 1000) = 19260 g = 19.260 kg

With the help of these above-mentioned calculations the mass of CH4 is identified at 17.16 kg and the total mass of water is calculated at 19.26 kg.

For the calculation of the required power level for this steam reactor, we need to use the formula of energy balance.

Therefore, the rate of energy exchange (Q) = (17.16/3600)* 15625 = 74.48 KJ/s.

So, the required power = 74.48/1000 = 0.074 Kw.

Question 5: Description of the size of the heat exchanger

This particular section of this research work includes the identification of the heat chamber's size. This particular calculation can be done using different types of mathematical equations (Chen et al. 2020). With the help of question number 4, we have identified the rate of heat transfer and the total required power which are 0.074 Kw and 15625.

Overall heat transfer coefficient = 20 W/m2K

The temperature will be 1500 K.

We can assume the input and output temperature will be 200 K and 300 K.

Therefore, the size of the heat exchanger = [0.074*(1500/20)]/ [0.004*500] = 2.75 m^2.

Question 6: Identification of required oxygen for the process

In this particular section the calculations which are essential for the required oxygen amount are done appropriately.

We have previously identified the mole value of methane (CH4) which is 4.28 mol. The combustion reaction of this specific steam reformer will be the same as the previous which is

CH4 + H2O= CO + 3H2

The mole value of CO = 1.07 mol and the mole value of H2 = 3.21 mol

Therefore the mass of CH4 = (1.07 * 35 * 1000) = 37450 g

On the other hand, the required amount of oxygen will be (1.07 * 32 * 1000) = 34,240 g = 34.24 kg.

It was identified that this particular steam reformer for methane will require a total amount of 34.24 kg of oxygen compound to produce syn-gas (Meloni et al. 2020).. Although, the amount can be changed by the total mass of Methane (CH4).

References

Journals

• Andrei, V., Reuillard, B. and Reisner, E., 2020. Bias-free solar syngas production by integrating a molecular cobalt catalyst with perovskite–BiVO4 tandems. Nature Materials, 19(2), pp.189-194.
• Bahmanpour, A.M., Signorile, M. and Kröcher, O., 2021. Recent progress in syngas production via catalytic CO2 hydrogenation reaction. Applied Catalysis B: Environmental, 295, p.120319.
• Chang, Y.J., Chang, J.S. and Lee, D.J., 2023. Gasification of biomass for syngas production: Research update and stoichiometry diagram presentation. Bioresource technology, p.129535.
• Chen, K., Zhao, Y., Zhang, W., Feng, D. and Sun, S., 2020. The intrinsic kinetics of methane steam reforming over a nickel-based catalyst in a micro fluidized bed reaction system. International Journal of Hydrogen Energy, 45(3), pp.1615-1628.
• Condori, O., García-Labiano, F., de Diego, L.F., Izquierdo, M.T., Abad, A. and Adánez, J., 2021. Biomass chemical looping gasification for syngas production using ilmenite as oxygen carrier in a 1.5 kWth unit. Chemical Engineering Journal, 405, p.126679.
• dos Santos, R.G. and Alencar, A.C., 2020. Biomass-derived syngas production via gasification process and its catalytic conversion into fuels by Fischer Tropsch synthesis: A review. International Journal of Hydrogen Energy, 45(36), pp.18114-18132.
• Liu, Y., Tian, D., Biswas, A.N., Xie, Z., Hwang, S., Lee, J.H., Meng, H. and Chen, J.G., 2020. Transition metal nitrides as promising catalyst supports for tuning CO/H2 syngas production from electrochemical CO2 reduction. Angewandte Chemie International Edition, 59(28), pp.11345-11348.
• Meloni, E., Martino, M. and Palma, V., 2020. A short review on Ni based catalysts and related engineering issues for methane steam reforming. Catalysts, 10(3), p.352.
• Niu, J., Wang, Y., Qi, Y., Dam, A.H., Wang, H., Zhu, Y.A., Holmen, A., Ran, J. and Chen, D., 2020. New mechanism insights into methane steam reforming on Pt/Ni from DFT and experimental kinetic study. Fuel, 266, p.117143.
• Quirino, P.P., Amaral, A., Pontes, K.V., Rossi, F. and Manenti, F., 2020. Modeling and simulation of an industrial top-fired methane steam reforming unit. Industrial & Engineering Chemistry Research, 59(24), pp.11250-11264.
• Sukma, M.S., Zheng, Y., Hodgson, P. and Scott, S.A., 2022. Understanding the behavior of dicalcium ferrite (Ca2Fe2O5) in chemical looping syngas production from CH4. Energy & Fuels, 36(17), pp.9410-9422.
• Zheng, L., Ambrosetti, M., Marangoni, D., Beretta, A., Groppi, G. and Tronconi, E., 2023. Electrified methane steam reforming on a washcoated SiSiC foam for low?carbon hydrogen production. AIChE Journal, 69(1), p.e17620.