Pyrolysis Process Of Oil Shale Research Articles

Exploring the influence of external electric fields on the catalytic pyrolysis of oil shale kerogen molecules

Oil shale is a widely distributed and abundant sedimentary rock that can be converted into shale oil through pyrolysis, providing a supplementary solution to the increasing scarcity of conventional fossil energy. However, the traditional pyrolysis process of oil shale faces problems such as low oil yield, high energy consumption, and poor oil quality. Recent experiments have demonstrated that using an external electric field to catalyze the pyrolysis of oil shale can address these problems. However, due to the complex physical and chemical properties of oil shale and its pyrolysis process, the catalytic mechanisms and effects have not been reasonably explained. To address these issues, this study uses density functional theory to calculate the properties of oil shale molecules under external electric fields of different directions and strengths. The results indicate that at electric field strengths far exceeding experimental conditions, the external electric field does have a certain catalytic effect on oil shale, which varies depending on the molecule. However, at electric field strengths achievable in actual laboratory conditions, the catalytic effect of the electric field on oil shale is not significant. Therefore, the mechanisms revealed by past experiments on the catalytic effects of electric fields on oil shale pyrolysis may be partially flawed. This study not only fills the gap in understanding the mechanisms of external electric field catalysis of oil shale but also provides a theoretical foundation for future applications of electric fields in catalyzing oil shale.

Numerical analysis of microwave-enhanced oil shale pyrolysis by rotation turntable based on the Arbitrary Lagrangian-Eulerian method

Microwave heating technology has great potential for efficient pyrolysis of oil shale. However, the inhomogeneous heating characteristics of microwave heating can lead to secondary cracking of pyrolysis products, thus reducing the overall oil yield. In order to address this issue, a rotational movement of oil shale under microwave heating has been proposed to obtain a uniform temperature distribution of the oil shale. Then, a new coupled three-dimensional electromagnetic-thermal-chemical-hydraulic model incorporating the Arbitrary Lagrangian-Eulerian (ALE) method was developed to investigate the temperature distribution and pyrolysis characteristics of oil shale under the rotational motion during microwave pyrolysis. The effects of rotational speed, rotational direction, and microwave power on the pyrolysis process of oil shale were explored through this model. The results showed that the introduction of rotational movement effectively addressed the uneven temperature distribution within the oil shale. Compared with the static condition, the rotational condition reduced the secondary reactions of oil products during microwave pyrolysis and increased the oil yield of oil shale to 50.12 %. As the rotation speed increased, the temperature distribution within the oil shale became more uniform, but the total oil yield reached its peak at a moderate speed of 180 s/r. Research on microwave power indicated that rotation increased the maximum usable power and highlighted that reducing the residence time of pyrolysis products within the oil shale was key to increasing oil yield. This study provides a novel approach and numerical simulation method for enhancing the microwave pyrolysis efficiency of oil shale, and the findings of this study are applicable to both the ex-situ and in-situ exploitation of oil shale.

Investigation of oil shale pyrolysis process: Physicochemical properties and decomposition products

Investigation of oil shale pyrolysis process: Physicochemical properties and decomposition products

Study on the pore evolution of Xinjiang oil shale under pyrolysis based on joint characterization of LNTA and MIP

During the in-situ exploitation of oil shale, the evolution of pore structure will affect the heat transfer medium and the transport capacity of products. In this study, using the oil shale from Jimsar region of Xinjiang, in combination with the low-temperature nitrogen adsorption experiment (LNTA) and high-pressure mercury injection experiment (MIP), the effect of temperature on evolution law of its pores during pyrolysis were analyzed according to the LNTA and MIP joint characterization results. The results show as follows: the change curve of oil shale porosity with pyrolysis final temperature in Xinjiang shows an “S” shape. The pore volume increases slightly before 300 °C, and it shows an increasing trend in the subsequent temperature range, with the mesopore volume change being the most noticeable. However, the increase slows down after 600 °C. The evolution of full-scale pores in the pyrolysis process of oil shale is reflected by the joint characterization of LNTA and MIP, which indicates that the temperature has a controlling effect on the evolution of pore, and provides basic theoretical support for how to improve the oil recovery rate of exploitation of oil shale.

A Photoconductance Mechanism for Oil Shale Pyrolysis Process Detection

Abstract Kerogen in oil shale plays a crucial part in the shale oil and gas generation. Here, photoconductive measurement was used to evaluate the decomposition process of Huadian oil shale. The photoconductivity of the semi-coke is a clear indicator of different pyrolysis stages, including moisture evaporation, primary pyrolysis of kerogen, decomposition of asphalt monomer, and mineral decomposition. Furthermore, the distribution model of electrical resistance (R) and photoconductance (ΔI) for Huadian oil shale is plotted, indicating an inverse proportion between R and ΔI. We believe that the photoconductive measurement will be a valuable means for the nondestructive characterization of oil shale pyrolysis, which is helpful to optimize the comprehensive utilization of this unconventional resource.

Pore Structure of Oil Shale Heated by Using Conduction and Microwave Radiation: A Case Study of Oil Shale from the Fushun in China

To examine the evolution of the internal pore structure of and the law of changes in oil shale under different heating modes but at the same temperature, this study subjected φ 20 mm × 20 mm specimens of oil shale to temperatures in the range of 20°C ~500°C by using a muffle furnace and a microwave pyrolysis device. We carried out experiments on the pyrolysis reaction under different temperatures and used scanning electron microscopy, backscattering, the mercury intrusion test, and MATLAB for a refined characterization of the specimens. The results showed that the microwave pyrolysis of oil shale was much shorter than its conduction-induced heating. As the microwave power increased, the time required to reach the target temperature decreased. The phenomenon of “hole blocking” was observed at 400°C ~500°C during conduction-based heating but did not occur in the microwave pyrolysis of oil shale. The porosity of oil shale heated by conduction was 3.4 times higher than its original porosity, whereas that of oil shale heated by microwave radiation was 4.9 times higher than its original value. It can be seen that compared with conduction heating, radiant heating makes the pyrolysis of organic matter in oil shale more complete. During the pyrolysis process of oil shale, the complete reaction of organic matter causes the thermal fracture of the oil shale to produce a large number of pores and interconnected cracks. Thereby, a seepage channel for pyrolysis gas and oil is formed, and the recovery rate of oil and gas is increased.

Evolution of Biomarker Maturity Parameters and Feedback to the Pyrolysis Process for In Situ Conversion of Nongan Oil Shale in Songliao Basin

In the oil shale in situ conversion project, it is urgent to solve the problem that the reaction degree of organic matter cannot be determined. The yield and composition of organic products in each stage of the oil shale pyrolysis reaction change regularly, so it is very important to master the process of the pyrolysis reaction and reservoir change for oil shale in situ conversion project. In the in situ conversion project, it is difficult to directly obtain cores through drilling for kerogen maturity testing, and the research on judging the reaction process of subsurface pyrolysis based on the maturity of oil products has not been carried out in-depth. The simulation experiments and geochemical analysis carried out in this study are based on the oil shale of the Nenjiang Formation in the Songliao Basin and the pyrolysis oil samples produced by the in situ conversion project. Additionally, this study aims to clarify the evolution characteristics of maturity parameters such as effective biomarker compounds during the evolution of oil shale pyrolysis hydrocarbon products and fit it with the kerogen maturity in the Nenjiang formation. The response relationship with the pyrolysis process of oil shale is established, and it lays a theoretical foundation for the efficient, economical and stable operation of oil shale in situ conversion projects.

Investigation on the Effect of Atmosphere on the Pyrolysis Behavior and Oil Quality of Jimusar Oil Shale

High-temperature H2O and CO2 can improve the pyrolysis behavior of oil shale. Therefore, in this paper, Jimusar oil shale was selected as the research object and the effect of the reaction atmosphere (H2O, CO2, and N2) on its pyrolysis behavior, pyrolysate distribution, and pyrolysis oil quality was fully compared and studied. The results showed that compared with the N2 atmosphere, the presence of H2O and CO2 both increased the weight loss and weight loss rate during pyrolysis of oil shale and the existence of H2O advanced the initial precipitation temperature of volatiles by 17°C. The comprehensive release characteristic indices of volatiles during pyrolysis of oil shale in the CO2 and H2O atmospheres increased by 49.34% and 114.35%, respectively, which significantly improved its pyrolysis reactivity. Both H2O and CO2 atmospheres improved the pyrolysis oil yield of oil shale, and the pyrolysis oil yield in the H2O atmosphere performed better than that in the CO2 atmosphere. Especially, the H2O atmosphere could increase the pyrolysis oil yield by 41.42%. The existence of CO2 prevented methyl radicals from accepting hydrogen radicals during pyrolysis and reduced the alkane yield, while CO2 participated in the addition reaction of alkane, which increased the alkene yield. High-temperature H2O provided more hydrogen source, which increased the alkane yield and inhibited the alkene formation. Both H2O and CO2 atmospheres promoted the cracking of polycyclic aromatics and increased the yield of small-molecular aromatics in the pyrolysis oil. During the pyrolysis process of oil shale, CO2 and H2O underwent reforming reaction with the heavy oil, which increased the light component fraction, thereby increasing the H/C ratio of pyrolysis oil. Thus, the existence of H2O and CO2 atmospheres improved the quality of pyrolysis oil and the effect of H2O was better than CO2. The H2O and CO2 atmosphere promoted the formation of a well-developed pore structure, which was conducive to mass and heat transfer during pyrolysis of oil shale.

Real-time monitoring of the oil shale pyrolysis process using a bionic electronic nose

Accurate and rapid prediction of thermal maturity during oil shale exploitation is important to optimize pyrolysis processes and decrease production costs. Then, a bionic electronic nose (BEN) was used for the first time for the real-time monitoring of the oil shale pyrolysis process. The results show that the calculated Easy%Ro change, unlike that of the measured vitrinite reflectance (%Ro), was small (±0.004) in decomposition stages (dewatering, hydrocarbon generation stage and inorganic matter decomposition) at the different heating rate. This time–temperature-related parameter made it a perfect intermediary to associate the thermal maturation process with the BEN signal during oil shale pyrolysis. The monitoring of the pyrolysis process of oil shale in real time was divided into two steps: 1) qualitatively checking whether the oil shale had entered the hydrocarbon generation stage, and 2) when entering this stage, quantitatively predicting the Easy%Ro evolution. Combined with different feature extraction methods, a support vector machine (SVM) as a classifier was used to complete the first step, which had the best recognition rate of 91.13%. For the second step, random forest (RF) was applied to quantitatively measure the Easy%Ro values, with an R2 reaching 0.95. During the verification stage, the established integration model was used to recognize a heating rate, which, between the trained heating rate in the algorithm model, performed much better in the first step (SVM, 92.96%) than in the second step (RF, 0.57), and those results were given in 38 to 125 s. Thus, the BEN technique can be applied in the real-time detection of oil shale exploration.

Constrain on Oil Recovery Stage during Oil Shale Subcritical Water Extraction Process Based on Carbon Isotope Fractionation Character

In this work, Huadian oil shale was extracted by subcritical water at 365 °C with a time series (2–100 h) to better investigate the carbon isotope fractionation characteristics and how to use its fractionation characteristics to constrain the oil recovery stage during oil shale in situ exploitation. The results revealed that the maximum generation of oil is 70–100 h, and the secondary cracking is limited. The carbon isotopes of the hydrocarbon gases show a normal sequence, with no “rollover” and “reversals” phenomena, and the existence of alkene gases and the CH4-CO2-CO diagram implied that neither chemical nor carbon isotopes achieve equilibrium in the C-H-O system. The carbon isotope (C1–C3) fractionation before oil generation is mainly related to kinetics of organic matter decomposition, and the thermodynamic equilibrium process is limited; when entering the oil generation area, the effect of the carbon isotope thermodynamic equilibrium process (CH4 + 2H2O ⇄ CO2 + 4H2) becomes more important than kinetics, and when it exceeds the maximum oil generation stage, the carbon isotope kinetics process becomes more important again. The δ13CCO2−CH4 is the result of the competition between kinetics and thermodynamic fractionation during the oil shale pyrolysis process. After oil begins to generate, δ13CCO2−CH4 goes from increasing to decreasing (first “turning”); in contrast, when exceeding the maximum oil generation area, it goes from decreasing to increasing (second “turning”). Thus, the second “turning” point can be used to indicate the maximum oil generation area, and it also can be used to help determine when to stop the heating process during oil shale exploitation and lower the production costs.

Bionic Layout Optimization of Sensor Array in Electronic Nose for Oil Shale Pyrolysis Process Detection

In order to meet the requirements for miniaturization detection of oil shale pyrolysis process and solve the problem of low sensitivity of oil and gas detection devices, a small bionic electronic nose system was designed. Inspired by the working mode of the olfactory receptors in the mouse nasal cavity, the bionic spatial arrangement strategy of the sensor array in the electronic nose chamber was proposed and realized for the first time, the sensor array was used to simulate the distribution of mouse olfactory cells. Using 3D printing technology, a solid model of the electronic nose chamber was manufactured and a comparative test of oil shale pyrolysis gas detection was carried out. The results showed that the proposed spatial arrangement strategy of sensor array inside electronic nose chamber can realize the miniaturization of the electronic nose system, strengthen the detection sensitivity and weaken the mutual interference error. Moreover, it can enhance the recognition rate of the bionic spatial strategy layout, which is higher than the planar layout and spatial comparison layout. This bionic spatial strategy layout combining naive bayes algorithm achieves the highest recognition rate, which is 94.4%. Results obtained from the Computational Fluid Dynamics (CFD) analysis also indicate that the bionic spatial strategy layout can improve the responses of sensors.

Kinetics and thermodynamics evaluation of carbon dioxide enhanced oil shale pyrolysis

The pyrolysis process of oil shale is significantly affected by atmospheric conditions. In this paper, the pyrolysis experiments of oil shale under non-isothermal conditions are carried out using nitrogen and carbon dioxide as heat-carrying fluids. The results show that the activation energy of the second stage of oil shale pyrolysis under carbon dioxide is less than that under nitrogen. The thermodynamic analysis of the second stage of oil shale pyrolysis shows that Gibbs free energy, activation enthalpy and activation entropy are higher under carbon dioxide than those under nitrogen, which obeys the law of carbon dioxide promoting oil shale pyrolysis. In addition, the volatile release characteristics of oil shale in the second stage of pyrolysis were analyzed, which proves that the volatile release characteristics of oil shale under carbon dioxide are higher than that under nitrogen. Therefore, carbon dioxide is helpful to promote the pyrolysis of oil shale and increases the release of volatile substances during pyrolysis.

Modeling and Performance Analysis of Shale Oil and Methane Cogeneration by Oil Shale Pyrolysis Integrated with a Pyrolysis Gas Methanation Process

Shale oil is regarded as an alternative to crude oil, and the use of this resource can relieve the crude oil supply shortage. China has abundant oil shale resources, and the conventional shale oil production process is based on oil shale pyrolysis (OSP). However, oil shale pyrolysis suffers from unsatisfactory technoeconomic performance. The process has many constraints, among which the most important constraint is the inefficient utilization of oil shale pyrolysis gas. The driving force determining the energy-efficient and economically beneficial use of pyrolysis gas calls for chemical conversion for high-value chemical production instead of direct combustion for power generation. A new process of shale oil and methane cogeneration by oil shale pyrolysis integrated with pyrolysis gas methanation is therefore proposed. The pyrolysis gas is first separated to obtain olefins, and then, it is used to produce methane by methanation technology. This conversion can significantly improve the energy efficiency and economic benefits. Technoeconomic analysis shows that the exergy efficiency of the new process is increased by 14.52% and the return on investment is increased by 23.33% in comparison with the conventional oil shale pyrolysis process. The proposed process provides a promising method for the efficient utilization of pyrolysis gas in the oil shale pyrolysis industry.

Numerical Investigation of the in Situ Oil Shale Pyrolysis Process by Superheated Steam Considering the Anisotropy of the Thermal, Hydraulic, and Mechanical Characteristics of Oil Shale

The in situ pyrolysis process of oil shale by superheated steam is a complex process that is affected by the thermal-hydraulic-mechanical coupled process. Meanwhile, oil shale’s physical properties show strong anisotropy in the thermal, hydraulic and mechanical characteristics due to the mineral arrangements and sedimentary structures. To accurately simulate the in situ oil shale pyrolysis process, the anisotropic thermal, hydraulic, and mechanical characteristics at different temperatures were first determined through laboratory experiments. Then, a thermal-hydraulic-mechanical coupled model that considers the anisotropic thermal-hydraulic-mechanical characteristics was established to simulate the in situ pyrolysis process of oil shale by superheated steam. The distributions of the pore pressure, temperature, stress, deformation, permeability and production during the in situ pyrolysis process were analyzed. The main results are as follows: (1) the temperature field distributions in oil shale reservoirs ...

An optical mechanism for detecting the whole pyrolysis process of oil shale

Pyrolysis is one of the most widely applied method for oil shale. Although an accurate exploration of the pyrolysis mechanism of oil shale is of utmost importance to optimize the pyrolysis parameters and decrease energy cost, the typically used pyrolysis techniques fail to provide comprehensive information of entire pyrolysis process. Terahertz time-domain spectroscopy (THz-TDS), a new optical method with different sensitivities to oil, water, gas, and minerals, was used to characterize the physical properties of oil shale’s pyrolysis products The confirmed collected tendency combined with the obvious turning points indicated the four stages during the pyrolysis of oil shale, which solves the acknowledgeable difficulty in identifying the organic decomposition and the mineral reaction. Water and kerogen, which highly absorbed THz waves, were volatized and then decomposed due to the continuous increasing of THz transmittance with THz signal varying by 27.9% and 18.6% from room temperature (∼22 °C) to 500 °C. In particular, the THz signal then decreased by 153%, indicating that the more sensitive calcium oxide crystals in THz range were obtained due to the decomposition of calcite. The THz results were validated by the combination of the material analysis techniques, including thermogravimetric analysis, mass spectrometry, scanning electron microscopy, and energy-dispersive spectrometry. The results proved the ability of this spectroscopic technique to be applied in the key detection of oil shale in the petroleum industry.

Oil shale reactor: process analysis and design by CFD

The oil shale pyrolysis process using a moving bed reactor was investigated with a three-dimensional mathematical model considering turbulent and multiphase flow in a porous moving bed, under non-isothermal and reactive conditions. Mass, heat and momentum balances involving chemical reactions of interest were formulated following a Eulerian approach to represent the process behavior. In the present approach, the shale bed was modeled as a porous medium and the advection due to its movement was implemented. Process analysis via CFD enabled the location of the drying, heating, reacting and cooling zones to be identified in the pilot-scale reactor. Moreover, it was possible to analyze in detail the conversion of organic matter to products, according to the reaction mechanism. The effects of heat and mass transfer inside the reactor were assessed through parametric sensitivity analysis, considering five parameters and five response values. The results were analyzed using the response surface method, which established the influence of each variable. The best values obtained for the thermal-energy consumption and the mechanical-energy consumption were 126.16 and 12.39kJ/kg, respectively. Considering the best operational conditions, scaling-up effects were also evaluated to shed light on the technical viability as well to carry out the design and analysis of the process.

Structure of Wangqing oil shale and mechanism of carbon monoxide release during its pyrolysis

AbstractIn this work, the structural characteristics of Wangqing oil shale were investigated using 13C nuclear magnetic resonance spectroscopy (NMR) and Fourier‐transform infrared spectroscopy (FTIR) techniques. The thermogravimetric‐Fourier‐transform infrared spectroscopy (TG‐FTIR) was used to pyrolyze samples and study their kinetics at four different heating rates. Meanwhile, the peak fitting method was used to study the carbon monoxide (CO) produced during the pyrolysis process. The results indicated that the oil shale was mainly composed of aromatic, aliphatic, hydroxyl, and oxygen‐containing functional groups, among which the aliphatic group was the most abundant. The pyrolysis process of oil shale was divided into four stages, whereas the pyrolysis weight loss and volatilization were concentrated in the second stage. When the number of peaks was 4, the fitting results were the best, which indicated that the precipitation of CO gas was affected by the four different types of reactions and was mainly the result of oxygen group and its side chain fracture.

Detailed physicochemical and thermochemical investigation of Upper Assam oil shale

The present work provides a detailed characterization and kinetic study of oil shale of Upper Assam, India. The physicochemical characteristics of oil shale were studied by proximate analysis, elemental analysis, Fourier transform infrared spectroscopy and X-ray diffraction. The physicochemical study showed the oil shale to be of siliceous type, sour in the presence of aliphatic, aromatic and phenolic compounds. The thermal decomposition of the oil shale was studied using thermogravimetric analysis at heating rates of 10, 20, 30 and 50 °C min−1. The kinetic study of oil shale pyrolysis process was performed on the thermogravimetric data using three model-free isoconversional methods, viz. Friedman, Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose. The reaction mechanisms were determined using the Criado master plot. The understanding of the composition of Indian oil shale and pyrolysis process kinetics can help establishing the experimental parameters for the extraction of valuable products from the oil shale.

ACHIEVING RESILIENCE AND SUSTAINABILITY THROUGH INNOVATIVE DESIGN FOR OIL SHALE PYROLYSIS PROCESS MODEL

Low international oil price, advance in renewable energy technology, development of energy storage technology and strict environmental regulations have presented encumbrance and opportunity for the current oil shale project development. Oil shale industry is at critical stage and facing challenges from competitive conventional energy, clean renewable energy and more strict environmental regulations. Through an innovative design of the oil shale pyrolysis process model by utilizing a developed new advanced technology, the oil shale project could improve its resilience and sustainability with excellent social and economic performance.This paper investigated the shale oil production process in terms of technology selection, utilization of resource, energy efficiency, oil yield, and mining to improve the resilience of oil shale project economic performance facing lower oil price. Innovative design options for the oil shale production process model were discussed from the following aspects: 1) itemized cost analysis and comparison of shale oil production technologies; 2) development of a new oil shale pyrolysis process model with combination of the existing vertical retort process (VRP) and horizontal rotary-kiln retort process (HRRP) technologies to improve the oil shale process economic gain; 3) discussion of innovative design options to improve the economic performance of the process by utilizing the current new advanced energy storage technology. Investigation of the applicability of the energy storage system (ESS) to the oil shale project was carried out with a sensitivity analysis of its cost-revenue.

Characterizing of Oil Shale Pyrolysis Process with Laser Ultrasonic Detection

The laser ultrasonic technique was proposed to characterize the pyrolysis process of the oil shale. The ultrasonic velocity was produced by a noncontact all-optical method in the three regions of Barkol, Yaojie, and Longkou of China. It was found that the ultrasonic velocity was related with the pyrolysis temperature of the oil shale. The pyrolysis process was divided into three stages due to the ultrasonic propagation speed in the oil shale. The ultrasonic velocity had small changes from 20 to 320 °C in the first stage, a sharp decline between 320 and 470 °C in the second stage, and another small change above 470 °C in the third stage. The variation of the velocity was qualitatively explained, which was considered to be closely related with the characteristics of pyrolysis process in oil shale. An empirical equation of the velocity attenuation was proposed to estimate the beginning and the end of the decomposition of the kerogen. It is a new way to characterize the process of the pyrolysis of oil shale b...