Development of a Coupling Oil Shale Retorting Process of Gas and Solid Heat Carrier Technologies

Oil shale is one of the most potential alternative resources for crude oil. Its exploration and exploitation are of increasing interest. In China, oil shale is mainly used by retorting technology. Fushun-type retorting technology, a typical gas heat carrier retorting technology, accounts for the largest proportion in China. However, this retorting technology is only applicable of coarse oil shale particles bigger than 10 mm in diameter. A lot of fine oil shale particles are discarded, resulting in waste of resources. Besides, this technology is criticized by low economic benefit. The main objective of this paper is to develop a coupling oil shale retorting process. The novel process can use fine oil shale particles as the raw materials of solid heat carrier retort to produce more shale oil. The novel process is modeled, and next, the simulation is carried out to build its mass and energy balance. From the techno-economic point of view, the advantages of the novel process are demonstrated by comparison to the traditional Fushun-type oil shale retorting process. Results indicate that the novel process is promising because coupling the two retorting process can increase the shale oil production from 13.86 to 17.34 t/h, the exergy efficiency from 32.46 to 38.01%, and the return on investment from 11.04 to 18.23%

Development of a Coke Oven Gas Assisted Coal to Ethylene Glycol Process for High Techno-Economic Performance and Low Emission

Developing a coal to ethylene glycol (CtEG) process is of great interest to many countries, especially China. However, because the hydrogen to carbon ratio of the coal-gasified gas is far less than the desired value, the CtEG process suffers from high CO₂ emission and wastes precious carbon resources. At the same, most coke oven gas (COG) is discharged directly or used as fuel, resulting in a waste of resources, serious environmental pollution, and economic loss. To develop efficient and clean utilization of coal and COG resources, we propose a novel coke oven gas assisted coal to ethylene glycol (CaCtEG) process. The proposed process introduces the hydrogen-rich COG to adjust the hydrogen to carbon ratio and reduce CO₂ emission by integrating a dry methane reforming unit. Key operational parameters are investigated and optimized based on the established mathematical model. The advantages of the process are studied by a detailed techno-economic analysis. Results show that, compared with the conventional CtEG process, the CaCtEG process is promising since it increases the carbon element and exergy efficiency by 18.35% and 10.59%. The CO₂ emission ratio of the proposed process is reduced from 2.58 t/t-EG to 0.44 t/t-EG. From an economic point of view, the CaCtEG process can save production costs by 5.11% and increase the internal rate of return by 3.41%. The capital investment, however, is slightly increased because of the two additional units

Conceptual Design and Analysis of a Natural Gas Assisted Coal-to-Olefins Process for CO₂ Reuse

Olefins have been regarded as one of the most important platform chemicals. The production of olefins and their derivatives are highly subject to oil. Developing coal-to-olefins processes is therefore of great interest to many countries, especially China. However, people have to face and pay for the severe environmental problems resulting from coal-to-olefins development. Of these problems, high CO2 emission of a coal-to-olefins process, always attracts the most attention since it is about five to six times of that of an oil-to-olefins process. For this problem, this paper proposes a new natural gas assisted coal-to-olefins process integrating CO2 recovery gasification and CH4/CO2 reforming techniques. The former technique increases the amount of syngas from the gasifier, while the latter one uses additional natural gas reacting with CO2 to produce H2-rich syngas. Key parameters are studied during the simulation of the new process. The advantages of the process are manifested by comparison with a conventional coal-to-olefins process from the techno-economic point of view. Results show that the new process is promising since it reduces the CO2 emission by 29.9% and increases the carbon efficiency and the energy efficiency by 20.7% and 7.8%. With the high market price of natural gas, the product cost of the new process is slightly higher than the coal-to-olefins process. But the new process will be more competitive if considering that the carbon tax is larger than $18.2/t CO2 or that shale gas is available in China

Development of an Oil Shale Retorting Process Integrated with Chemical Looping for Hydrogen Production

The increasing demand of crude oil is in conflict with the shortage of supply, forcing many countries to seek for alternative energy resources. Oil shale is welcomed by many countries that are short of conventional fossil fuels. China mainly uses retorting technology for shale oil production. Fushun-type oil shale retorting technology takes the largest share in the oil shale industry. However, this technology is always criticized by its unsatisfactory economic performance. It is caused by many reasons. One of the most important problems is the inefficient utilization of retorting gas. The idea of our research is to utilize the retorting gas to produce higher valued chemicals. For this, chemical looping technology is integrated into the retorting process for hydrogen production. This proposed process is modeled and simulated to build its mass and energy balance. Techno-economic analysis is conducted and compared to the analysis of the Fushun-type oil shale retorting process. The results show that the exergy destruction of the proposed process is 235.62 MW, much lower than that of the conventional process, 274.76 MW. In addition, the proposed process is less dependent on shale oil price. Two shale oil price scenarios have been investigated, showing that the proposed process can still be of benefit, 10.62% ROI, at low shale oil price, while the ROI of the conventional process is −2.07%

Efficient Utilization of CO₂ in a Coal to Ethylene Glycol Process Integrated with Dry/Steam-Mixed Reforming: Conceptual Design and Technoeconomic Analysis

In the momentum of reducing the CO2 emission of coal to ethylene glycol (CtEG) process, a novel carbon dioxide utilized coal to ethylene glycol (CUCtEG) process is proposed, simulated, and optimized to find the optimal way for simultaneous reduction and utilization of CO2 emissions of conventional coal to ethylene glycol process. The novel process is integrated with coke oven gas and dry/steam-mixed methane reforming technologies to enhance resource and energy efficiencies as well as reduce CO2 emission. On the basis of the rigorous steady-state simulation of the process, the key operational parameters of the proposed process are investigated and optimized. A detailed technoeconomic analysis is conducted to manifest the advantages of the proposed process by comparison with a conventional process. The results show that the optimal feed ratio of coke oven gas to coal is 0.68, and the split ratio of CH4 for steam methane reforming reaction is suggested to be 0.74. Compared with the conventional coal to ethylene glycol process, the direct CO2 emission of the proposed process is significantly reduced by 94.05%, and the carbon utilization efficiency and exergy efficiency are greatly increased by 36.4% and 15.17%. Moreover, the proposed process has a better economic performance and stronger competitiveness since it can save the production cost by 9.72% and improve the internal rate of return by 6.92%. Thus, the proposed process provides a promising way to efficient utilization of CO2 and improve the technoeconomic performance of coal to ethylene glycol industry

Conceptual Design and Techno-Economic Analysis of a Novel Coal-to-Polyglycolic Acid Process Considering Wind–Solar Energy Complementary Features for Green H₂ Production and CO₂ Reduction

The production of degradable polyglycolic acid from coal is a promising route for converting coal to high-end chemicals and can availably alleviate the problem of excess ethylene glycol. However, the traditional coal-to-polyglycolic acid (CtPGA) process wastes a lot of precious CO gases to adjust the H2/CO ratio, simultaneously producing a large amount of CO2 emissions. To address this issue, this work proposes a novel coal-to-polyglycolic acid process integrated with green hydrogen from complementary wind and solar power (GHCtPGA). The complementary characteristics of solar and wind energy are investigated to generate green hydrogen. It is found that the hybrid power of wind–solar energy for the green hydrogen production process can significantly affect the capacity of the energy and hydrogen storage systems. After the modeling and simulation of the whole flowsheet of the CtPGA and GHCtPGA processes, the techno-economic and environmental performance of these processes is analyzed in detail. Compared with the CtPGA process, the GHCtPGA process reduces CO2 emissions by 68.85% and improves carbon and exergy efficiencies by 11.57 and 2.72%, respectively. Furthermore, the economic performance of the GHCtPGA process is more satisfactory because its total capital investment is reduced by 11.32%, the total production cost is saved by 3.59%, and the internal rate of return is improved by 2.83%. Finally, a sensitivity analysis is conducted to explore the effect of coal price, electricity price, power consumption, and carbon tax on the economic advantages of the proposed GHCtPGA process. It indicates that the proposed GHCtPGA process has considerably stronger market risk resistance than the CtPGA process. Therefore, the proposed process provides a valuable PGA production route with low carbon, high efficiencies, and optimal economic trade-offs

Process Development and Technoeconomic Analysis of Different Integration Methods of Coal-to-Ethylene Glycol Process and Solid Oxide Electrolysis Cells

The conventional coal-to-ethylene glycol (CtEG) process is criticized for its high CO2 emissions. Because most CtEG projects are located in areas rich in renewable energy such as wind energy and solar energy, two novel green hydrogen-assisted CtEG processes are proposed and analyzed by the integration of solid oxide electrolysis cell (SOEC) technology: the CtEG process integrated with the SOEC technology of only steam electrolysis (SOEC-CtEG) and that of steam and carbon dioxide electrolysis (CoSOEC-CtEG). The effects of the operating temperature, current density, and inlet gas composition on the electrochemical performance of the solid oxide steam electrolytic and coelectrolytic processes are investigated and compared based on their electrochemical and flowsheet-based models. The thermodynamic and technoeconomic advantages of the two proposed processes are manifested by comparison with a conventional process. The results show that the two proposed processes are promising because they increase the carbon utilization efficiency by 26.13 and 22.48%, increase the exergy efficiency by 14.82 and 17.34%, decrease the total capital investment by 23.60 and 19.38%, decrease the levelized production cost by 20.55 and 27.47%, and increase the internal rate of return by 8.85 and 9.18%. In addition, the sensitivity analysis results show that the two proposed processes have stronger antirisk ability than the conventional process

Opportunities for CO₂ Utilization in Coal to Green Fuel Process: Optimal Design and Performance Evaluation

Methanol is predominantly produced by a coal-to-methanol process in China. However, this process is criticized by high CO2 emissions because of the high carbon contents of coal. The high CO2 emission and low resource utilization efficiency greatly weaken the competitiveness of the coal-to methanol industry. Coke oven gas, one of the hydrogen-rich resources, is used as fuel or directly discharged. This leads to a waste of valuable resources and serious economic losses. Aiming at effective utilization of CO2 and coke oven gas, this study proposes a novel coal-to-methanol process integrated with CO2 utilization for improving the system performance of the traditional coal-to methanol process. Coke oven gas is introduced to meet the H2/CO2 ratio required for methanol synthesis reaction by integrating with chemical looping technology. The key parameters are analyzed and optimized on the basis of the established model of the novel process. Furthermore, its advantages are manifested in detail in comparison with the conventional coal-to-methanol process. Results show that the novel process has a better comprehensive performance because it can increase the carbon and exergy efficiencies by 47.9 and 15.4% as well as save the investment and production costs by 23.3 and 7.5%. Moreover, the internal rate of return of the novel process is improved by 9.1% and the lifecycle greenhouse gas emissions are reduced from 2.86 to 0.78 t CO2‑equiv per ton of methanol compared with the conventional process

Viable Alternative Prospective Option for Liquid Methanol Industry’s Long-Term and Cost-Effective Development: CO₂ to Methanol Conversion and Ethylene Glycol Coproduction

The CO2-to-methanol (CTM) process can realize the recycling of carbon resources and mitigate the global greenhouse effect. However, the low CO2 conversion rate is a consequence of the thermodynamic equilibrium, which restricts the direct hydrogenation of CO2 to methanol (CTMI). Furthermore, there exists a state of kinetic competition between the reaction that produces methanol and the reaction that reverses the water–gas shift, which leads to the low selectivity of methanol. To solve these problems, a new process of indirect hydrogenation of CO2 to methanol and the coproduction of ethylene glycol (CTMII) was proposed in this paper. The steady state modeling, energy integration, and technoeconomic evaluation of the new process were carried out. It was found that the carbon and hydrogen utilization rates of the CTMII process were 98.95% and 98.63%, respectively, corresponding to increases of 2.99% and 34.21%, respectively, compared to those of the CTMI process. The selectivities of methanol and ethylene glycol in the CTMII process are 47.44% and 52.56%, respectively. Under the current economic conditions (0.35 CNY/kWh electricity, 1.8 CNY/m3 natural gas, 5000 CNY/t ethylene glycol, and 17.5 CNY/kg H2), the production cost of the CTMII process was 2572 CNY/t-CH3OH, 38.82% lower than that of the CTMI process. The net present value was calculated, and a sensitivity analysis of the relationship between hydrogen and production costs was performed. When the H2 price dropped to 13.6 CNY/kg, the product cost of CTMII could compete with that of the coal-to-methanol process, showing great economic potential for the future. This study presented a novel approach for the utilization of CO2 resources and broadened the path for green and low-carbon production of methanol

Enhancing the Photoluminescence Property of Pr³⁺ Ions by Understanding the Polymorphous Influence of the K₃Lu(PO₄)₂ Host

Adjusting the local coordination environment of lanthanide luminescent ions is a useful method to manipulate the relevant photoluminescence (PL) property. K3Lu­(PO4)2 is a phase-change material, and according to the stable temperature range from low to high, the related polymorphs are phase I [P21/m, coordination number (CN) of Lu3+ = 7], phase II (P21/m, CN = 6), and phase III (P3̅, CN = 6), respectively. Based on the temperature-dependent PL analysis of K3Lu­(PO4)2:Pr3+, we find that Pr3+ ions occupy the noninversion sites (Cs) in the two low-temperature phases but preferentially enter into the inversion ones (C3i) in phase III. Compared to Pr3+-doped phase I (78 K), Pr3+ ions in phase III (300 K) manifest a weaker fluorescence intensity (170-fold lower). To enhance the room-temperature PL property of K3Lu­(PO4)2:Pr3+, a polymorphous adjustment strategy was proposed by the use of the ion-doping method. By introducing the Gd3+ ions into the lattice, Pr3+-doped phase I is successfully stabilized to room temperature, manifesting a 27-fold fluorescence increase in comparison to K3Lu­(PO4)2:Pr3+ (0.1 at. %). The finding discussed in this study highlights the significance of site engineering for luminescent ions and also presents the application value of phase-change hosts in the development of high-performance luminescent materials