Coal Gas Production Research Articles

Experimental study on variation characteristics of combustion heat load in circulating fluidized bed under fuel high-temperature preheating modification

This study introduces an innovative application of fuel high-temperature preheating modification technology to circulating fluidized bed (CFB), intending to enhance the variable load rate of CFB and reduce its NOx emissions. The variable combustion heat load (CHL) experiments were conducted on a novel CFB experimental platform comprising a preheating modification device (PMD) and CFB. The findings indicate that implementing fuel high-temperature preheating modification technology allows the CFB to operate stably within the range of 30%–100% CHL while maintaining superior combustion efficiency. Moreover, it reduces NOx emissions by over 28% compared to conventional combustion. The decrease in NOx emissions can be attributed to the fuel's preheating modification process inhibiting NOx production and establishing conditions conducive to NOx reduction in CFB. Furthermore, after employing the fuel high-temperature preheating modification technology, the CHL change rate of CFB reached 1.79%/min and 2.27%/min for the transition from 50% CHL to 75% CHL and from 75% CHL to 100% CHL, respectively. These rates represent an increase of 1.59 and 1.80 times compared to the rates observed in conventional combustion processes. The increase in the CHL change rate of different CHL variation intervals is primarily due to the production of high-temperature coal gas and modified char following fuel preheating modification. High-temperature coal gas exhibits a rapid combustion rate, while modified char has a smaller particle size, more developed pore structure, and enhanced reactivity than raw coal.

Coal permeability evolution and gas production performance prediction under the coupling action of stress-residual water-pulverised coal

Coal permeability evolution and gas production performance prediction under the coupling action of stress-residual water-pulverised coal

Determinants of carbon emissions disclosure: Study of mining companies of the Indonesian stock exchange

In recent years, countries around the world have faced the problem of climate change. Carbon emissions from human activities, including company operations, play a significant role in this phenomenon. Mining companies, whose operations primarily burn fossil fuels such as coal, oil, and natural gas production, are among the largest greenhouse gas (GHG) emitters among other industries. This study analyzes the factors thatinfluence the disclosure of carbon emissions in mining companies listed onthe IDX during the 2018-2022 period, with a focus on environmentalperformance and board characteristics. The research sample includes 230 companies. This research uses a panel data approach to analyze data, with Eviews as an analysis tool. The findings of this study indicate that both environmental performance and board size play a significant role in encouraging companies to be more open in informing their carbon emissionsdata. This finding suggests that ISO 14001 certification can help companiesmanage their environmental performance so that they can calculate, monitorand report their carbon footprint. In addition, a larger board size will be moreeffective in the supervision process and increase corporate accountability towards environmental disclosure issues.

Coal permeability evolution and gas production performance prediction under the coupling action of stress-residual water-pulverised coal

Coal permeability evolution and gas production performance prediction under the coupling action of stress-residual water-pulverised coal

A Study on the Production Simulation of Coal–Shale Interbedded Coal Measure Superimposed Gas Reservoirs under Different Drainage Methods

To study the influence of different drainage methods on the production performance of coal measure gas wells, the interbedded reservoir composed of coal and shale in the Longtan Formation of the Dahebian block was used as the research object. Considering the influence of coal and shale matrix shrinkage, effective stress, and interlayer fluid flow on reservoir properties such as fluid migration behavior and permeability, a fluid–solid coupling mathematical model of coal measure superimposed gas reservoirs was established. Numerical simulations of coal measure gas production under different drainage and production modes were conducted to analyze the evolution of reservoir pressure, gas content in the matrix, permeability, and other characteristic parameters of the superimposed reservoir, as well as differences in interlayer flow. The results showed that, compared to single-layer drainage, cumulative gas production increased by 33% under multi-layer drainage. Both drainage methods involve interlayer energy and substance transfer. Due to the influence of permeability, porosity, and mechanical properties, significant differences exist in reservoir pressure distribution, preferential flow direction, gas content in the matrix, and permeability ratio between coal and shale reservoirs under different drainage and production modes. Multi-layer drainage effectively alleviates the influence of vertical reservoir pressure differences between reservoir layers, facilitates reservoir pressure transmission in shale reservoirs, enhances methane desorption in shale matrices, promotes matrix shrinkage, and induces the rebound of shale reservoir permeability, thus improving overall gas production.

Effect of Pore Pressure on Strain Rate-Dependency of Coal

Viscoelastic strain rate-dependent behaviour of coal is critical in several subsurface engineering applications especially coal seams gas production. Such rate dependency is controlled by the interaction between coal bulk and gas sorption (a sorbing gas) or gas pressure (a non-sorbing gas). Despite the research conducted to date, the gas pressure effect (non-sorbing) on the viscous behaviour of sediments in particular coal remains unexplored. We, therefore, investigate the strain rate-dependent mechanical behaviour of coal under isotropic loading to specifically explore the effect of gas pressure (Helium) on its rate dependency eliminating the sorption effect. We perform a set of triaxial experiments on coal specimens at dry and pressurised gas (Helium) conditions under different strain rates under isotropic loading. The experimental results show that all coal specimens have viscoelastic strain rate dependency at a dry condition where viscous effect increases with strain rate. As a result, the bulk modulus of the specimens increases with the increase in strain rates. This strain rate dependency response, however, reduces with an increase in pore pressure and vanishes at a certain pore pressure under the same effective stress to that of dry specimens. We further employ X-ray micro-Computed Tomography (XRCT) to 3D scan a coal specimen saturated with Krypton gas undergoing different loading rates to shed light on the micro-mechanisms of gas pressure effect on specimens’ rate dependency. The XRCT results show that gas can be trapped in small-scale fractures and pores during the loading process leading to a localised undrained response that can stiffen the specimen and reduce its ability to show viscous rate dependency. The obtained results are significant in optimizing coal seam gas production and coal seam gas drainage applications.

Distributed robust optimization scheduling of a steel plant integrated energy system considering the uncertainty of byproduct coal gas

The steel plant integrated energy system (SPIES) is an important form in the steel industry. Improving the utilization efficiency of steam, electricity, coal gas and other energy flows is of great significance for both economic and environmental benefits. In this paper, a SPIES scheduling model is established according to the operation characteristics of coal gas holders, boilers and other equipment in steel plants. Meanwhile, to cope with the uncertainty of byproduct coal gas, this paper adopts an imprecise Dirichlet model (IDM) to construct a fuzzy set containing multisource coal gas production information. Then, according to duality theory and the big-M method, the original distributed robust optimization (DRO) model is transformed into a traditional mixed integer linear programming (MILP) model, which is solved by the column-and-constraint generation (CC&G) algorithm. Finally, a real steel production system is given in a case study. Case study illustrate that compared with the traditional robust method, the method proposed in this paper for a SPIES can effectively reduce the conservatism of the scheduling decision. Numerical simulation show that the proposed method can reduce total cost by 55,307.1¥, accounting for 1.91% of the total cost compared with robust optimization method and save 1,326.94 s of computational time compared with the stochastic optimization method, thus reaching balance between conservatism and computational efficiency.

Revealing the Effects of Water Imbibition on Gas Production in a Coalbed Matrix Using Affected Pore Pressure and Permeability

The effect of water imbibition on characteristics of coalbed methane reservoirs, such as permeability, gas occurrence state, and gas production, is controversial. According to the mechanism of imbibition, gas and water distribution in blind pores is reconfigured during the fracturing process. Therefore, a new comprehensive model of pore pressure and permeability, based on the perfect gas equation and the weighted superposition of viscous flow and Knudsen diffusion, was established for micro- and nanoscale blind pores during water drainage. Using the numerical simulation module in the Harmony software, the effects of imbibition on coal pore pressure, permeability, and gas production were analyzed. The results showed that (1) water imbibition can increase pore pressure and reduce permeability, and (2) water imbibition is not always deleterious to gas production and estimated ultimate reserve (EUR), when the imbibition is constant, the thicker water film is deleterious to coalbed methane wells; when the thickness of water film is constant, more imbibition is beneficial to gas production and EUR. This research is beneficial to optimize the operation of well shut-ins after fracturing and provides methods for optimizing key parameters of gas reservoirs and insights into understanding the production mechanism of coalbed methane wells.

Economic specialization and demographic development of settlements in the Northern region

The article is devoted to the analysis of impact of economic specialization of settlements in the northern mining region on their demographic dynamics. The object of the study is 58 urban and 725 rural settlements of the Komi Republic in 1897-2020. Use of highly detailed data made it possible to identify spatial and sectoral patterns in demographic development of the settlements. The authors have proposed periodization of economic and demographic development of the Komi Republic in the XX-XXI centuries based on production structure and population movement. The study has identified specifics of demographic dynamics in settlements specialized in coal mining, natural gas and oil production, timber, transportation and multifunctional settlements in northern Russia. The authors show that relationship between the volume of production and demographic dynamics varies depending on the settlement specialization. The relationship between the population size and phase of the natural resource extraction cycle is most pronounced in coal mining settlements. As to rural settlements, in addition to economic specialization, the dominant ethnic group was taken into account. The study shows that the smallest outflow of population is registered in agricultural settlements, as well as settlements with Komi being the dominant ethnic group or settlements with mixed ethnic composition. Impact of spatial remoteness of northern settlements on population size in different time periods has been determined. The results obtained make it possible to predict future changes in population distribution in the northern and Arctic regions.

Nonlinear Diffusion-Based Multifield Coupling Model for Thermally Enhanced CBM Recovery

Thermal stimulation is a supplementary technique for enhancing gas recovery from coalbed methane (CBM) reservoirs that has received considerable attention worldwide. Investigating gas and heat transfer in coal seams during thermally enhanced CBM recovery is of great significance for predicting gas production and optimizing the extraction method. Gas diffusion in the coal matrix and coupled multiphysics are two of the most important aspects when analyzing gas migration and heat transport. However, previous studies either neglected the nonlinear diffusion process of gas or only assumed that the diffusion coefficient varies with production time. However, considerable experimental results indicate that the gas diffusion coefficient is not only determined by time but also by temperature, which strongly impacts multifield interaction during gas recovery. Thus, prior diffusion models and coupled models must be modified. In this paper, a time-and-temperature-dependent gas diffusion model is established based on fractal theory and experimental data. The proposed diffusion model is embedded into the coupled thermal-hydro-mechanical model to comprehensively describe the behavior of coal deformation, gas migration, and heat transport during CBM recovery. Additionally, both new diffusion model and coupled model were validated with experimental results or field test data, showing that these developed models are applicable for modeling long-term gas diffusion and gas production. Finally, the coupled model was implemented into COMSOL Multiphysics software, and a series of numerical simulations were conducted. The calculation results showed that heat injection could promote gas desorption and diffusion in the matrix while inhabiting gas flow in fractures near the injection well. Gas dynamic diffusion could inhabit gas migration in both matrix system and fracture system at a later production stage. This also means that ignoring the gas nonlinear diffusion process leads to a severe overestimation of coal permeability and gas production.

Emissions from fossil fuels produced on US federal lands and waters present opportunities for climate mitigation

Between 2005 and 2019, a quarter of US fossil fuel production came from federal lands and waters. We estimate that the extraction, transportation and combustion of these fuels resulted in emissions equivalent to roughly 1.4 billion metric tons of carbon dioxide equivalent per year. To better understand their future role in the US emissions profile, we use publicly available data and machine learning to model coal, oil and natural gas production on federal lands and waters to 2030, and calculate associated life cycle climate emissions. We estimate that total emissions from fossil fuels produced on federal lands and waters decline 6% below 2019 levels by 2030; and note that absent additional policy, further reductions may be challenging as some of the cheapest fossil fuels occur on federally owned lands and many are effectively subsidized.

СТАН ТА ТЕНДЕНЦІЇ РОЗВИТКУ СИСТЕМИ ЕНЕРГОЗАБЕЗПЕЧЕННЯ В УКРАЇНІ

The article discusses contemporary issues of ensuring energy security in Ukraine. A brief overview on the modern energy system which comprises power plants of different types, electrical and thermal networks operating in the manufacturing sector, in transmission and distribution of electrical and thermal energy. The study considers the following types of power plants in the energy system of Ukraine: nuclear, thermal, hydroelectric and hydropower stations as well as power plants working with alternative (renewable) energy sources. It is argued that the ratio of energy sources and the energy system balance is the core basis to provide the national energy security and maintain stable power supply subject to different external environment factors. The findings have revealed the dominance of coal and natural gas production in the overall energy balance of Ukraine. However, the study of import and export trends demonstrates the prevalence of energy imports, in particular coal, oil and gas. It is observed that currently, alternative energy sources are at the infant development stage. The study of alternative energy supply in Ukraine shows that over 2018–2020 the capacity of such power plants increased by 7%, in particular, the capacity of wind stations grew by 2.3 times and solar – by 4.3 times, thus exhibiting respective change in energy output. It is also observed that during the period under consideration, the renewable energy output dropped by 17.1% while wind power production increased by 2.8 times and solar – by 5.2 times, respectively. According to the results, over 2018–2020 the capacity of wind power plants increased from 0.9% to 2.0% of the total domestic output, and solar – from 2.3% to 9.4%; as to production, the share of energy generated by wind power increased from 0.8% to 2.4%, and solar – from 0.7% to 4.1%. Given the current trend of increasing energy output generated from alternative sources, there is reason to tap a growing interest in the activities of companies offering power generating equipment in the Ukrainian market. A study on the capacity needs has revealed that the most popular among consumers of autonomous power supply systems, about 70% of total sales refer to low and medium power generators in the range of 8–550 kW. The conclusions resume that the key driver in boosting the alternative energy supply system is the relevant legal framework that encourages further alternative energy supply market development and, accordingly, the market of power generating equipment in Ukraine characterized by a strong upward growth trend.

DEVELOPMENT AND PROSPECTS OF FLOATING SOLAR POWER PLANTS ON THE EXAMPLE OF TASH-KUMYR AND SHAMALDY-SAY DAMS OF HYDROELECTRIC POWER PLANTS

The Kyrgyz Republic is able to fully meet its electricity needs both at present and in the future. The country has large fuel and energy resources. However, the level of their development is currently very low. Over the past 10 years, coal and natural gas production has sharply decreased, due to the low-water period this year Kyrgyzstan faced an energy crisis. Power engineers fear that after the heating season, only 6-7 billion cubic meters of water may remain in the reservoir. This may lead to the shutdown of the Toktogul HPP. In this regard, there is a need to use new sources, resorting to unconventional energy.

Effect of oxygen-staging on fluidized preheating combustion of pulverized coal under O2/CO2 atmosphere

Oxy-fuel combustion with low NOx emission has been received more attention in recent years. In this work, a series of oxygen-staged experimental investigations of Shenmu bituminous coal with the preheated combustion technology was carried out under O2/CO2 atmosphere to obtain the effect of oxygen-staged on combustion and NOx emission. The results showed that the increase of excess oxygen coefficient of the primary air(λPr) decreased the temperature difference at each measuring point in the circulating fluidized bed, promoted the production of coal gas, facilitated the release of elements, and improved the mass conversion ratio of volatile matter up to 92.3%. Besides, the increase of λPr inhibited the conversion process of N-5 to N-6. At the same time, the release of nitrogen-containing volatile matter during the partial gasification process was also reduced. As the λPr increases, reducing the excess oxygen coefficient of the secondary air(λSe) or increasing the oxygen partial pressure of primary air were beneficial to reduce the emissions of NOx to a certain extent.

Evaluation of Coal Pore Connectivity Using N2 Sorption Isotherm and Spontaneous Imbibition Tests

Pore structure and connectivity of coal are critical factors in coal gas migration and production, which can be characterized by studying the kinetics of capillary imbibition behaviour within the pore spaces. In order to investigate them, six typical coal samples from different collieries in China (Yangcun, Changcun, Gengcun, Yanbei, Dongxia, and Yuwu coal) are selected to carry out N2 sorption isotherm and spontaneous imbibition tests. Results from N2 sorption isotherm tests show that there is a great difference between the total specific surface area and total pore volume among the six coal samples. Their total specific surface area varies from 0.302 to 3.275 m2/g, and the total pore volume varies from 1.782 to 10.94 mm3/g. The pore volume relationship of coal sample among them is in order from the large to small: Dongxia>Yangcun>Gengcun>Yuwu>Changcun>Yanbei coal, and the specific surface area is in order from the large to small: Yangcun>Dongxia>Changcun>Yuwu>Gengcun>Yanbei coal. The imbibition characters of six coal samples were matched using explicit the short-time limit t ⟶ 0 and long-time limit t ⟶ ∞ models by Zhmud et al., respectively. The results show that the long-time limit t ⟶ ∞ model is better. Combined with pore structure analysis, it can be qualitatively analyzed that the imbibition capacity of six coal samples is positively correlated with the connectivity of coal pores, which is ranked as Changcun>Yanbei>Gengcun>Yangcun>Dongxia>Yuwu coal. This work will help understand the mechanism controlling fluid loss and ultimate gas/oil recovery in unconventional hydrocarbon exploration.

The Design of Simple Environmentally Friendly A coal Gasifier in Small Scale with Maximum Capacity of 2 Kgs/Hour

The design of a a coal gasification system is a workable unit or device whose work principle to change a coal fuel that has low-calorie value to be gas with a coal gasification system. Gas which is produced from a coal gasification system is a clean gas and environmentally friendly that its gasifier unit is used. The gasification process can be defined as the building process of gas fuel (CO, H2, and N2) in a small sump from a chemical reaction solid fuel characteristically Carbonaceous or Cellulosic, for example, coal, wood, and agriculture rubbish. Reaction process of gasification a chemical going on complexly, with the step as follows: drying, oxidation, and reduction. The aim of making a coal gasification system design is for using gas fuel as replaced solar fuel in the industry. For long time which will be got in this research is the use of a coal that has low-calorie value gasification system design on a big scale with a maximum capacity of more than 50 kgs/hour. The method which is used in this research is the design method and ratio method suitable with the gas that has been produced and go on with designing and existing of a the coal gasification system. The result from this research is drawing design of a coal gasification system and gas production as big as 0,5 kg from burning of a coal fuel as 2 kgs, already formed a fire on the stove, the gas temperature can reach T3 at 400°C and gas pressure is 0,88 Atm.

Modeling the impact of energy abundance on economic growth and CO2 emissions by quantile regression: Evidence from China

Based on China’s 30 provinces penal data, from 1990 to 2017, this paper uses the quantile regression model to estimate the impact of fossil energy abundance and clean energy abundance on economic growth and carbon dioxide (CO2) emissions. The findings show that fossil energy abundance exerts a greater impact on economic growth in the intermediate quantile provinces such as Hebei, Jilin, Liaoning, and Shandong because these provinces have larger petroleum processing and coal gas production industries. The CO2 emissions in the upper 90th quantile provinces such as Liaoning, Shanxi, and Shandong, receive the biggest impact from fossil energy abundance because these provinces consume more coal and oil. However, the impacts of renewable energy abundance on economic growth in the 50th-75th, upper 90th, and 75th-90th quantile groups are greater, since their renewable energy industry is growing faster. The influence of renewable energy abundance on CO2 emissions in all quantile groups is positive, meaning it does not play a prominent role in mitigating CO2 emissions. Therefore, each quantile province should formulate specific policies to promote the growth of renewable energy and actively develop strategic emerging industries.

The volatility of natural gas prices - Structural shocks and influencing factors

The paper examines the primary drivers and factors influencing the volatility of natural gas prices in the world from January 2007 to July 2020. In addition to the narrow dependence between crude oil and natural gas prices, the influence of renewable energy production and coal production on the price of natural gas has been studied. For that purpose, the method of multiple linear regression was used. The results show that the volatility of natural gas prices significantly depends on the type of the shock in the natural gas market, and that the total production of energy from renewable sources, production of coal and natural gas and the price of crude oil have a significant impact on the price of gas.

Simulation Analysis of Erosion–Corrosion Behaviors of Elbow under Gas-Solid Two-Phase Flow Conditions

In the production and gathering process of coal gas, the complex composition of the coal gas, harsh environments, the complex medium, and high content of solid particles in slurry cause the equipment malfunctions and even failure because of erosion and corrosion. In the present study, COMSOL multi-physics finite element simulation software is used to simulate the erosion–corrosion behaviors of elbow in key chemical equipments. The electrochemical corrosion, solid particle erosion, chemical reaction, and turbulent flow are coupled together. The particle count method is proposed to clarify the erosion phenomenon. The simulation results show that particles with high turbulent intensity hit the wall of elbow directly, which forms a slanted elliptical erosion zone on the extrados surface at 40°–50°. The chemical reaction in turbulence has a difference in the concentration distribution of substances, and this phenomenon leads to different magnitudes of the corrosion current densities in the tube. Moreover, 1/6 released particles hit the extrados surface of the elbow. These findings are beneficial to understand the erosion–corrosion phenomena and design the elbow in key chemical equipment.

Diverse community energy futures in Saskatchewan, Canada

This research explores peoples’ place attachment and context surrounding power production and energy futures. Facilitated, deliberative focus groups were conducted as comparative case studies in three fossil fuel-dependent cities in Saskatchewan Canada: Estevan (situated next to the provincial centers of coal, oil and gas production), Saskatoon (situated more northerly and furthest from coal, oil and gas production) and the capital city of Regina. (situated between the other two communities). This study supports the conclusions: (1) participants believed the focus groups improved their knowledge surrounding power production; (2) although there is strong support for wind and solar power production, there is a gap in implementation; and (3) place-based location impacts perceptions of power production sources. Participants were surveyed before and after focus group meetings to explore the perceptions and preferences of power productions sources. All three communities favored renewables in the order of solar and wind. Estevan, supported carbon capture and sequestration (CCS) to a greater degree and perceived much lower risk surrounding CCS than the other two communities. This may be explained by information gaps in this community. Participants were far less likely to believe a climate crisis is occurring, and while recognizing health concerns surrounding coal, they spent considerably more time discussing the loss of coal and its impact on their economy. Saskatoon, the community furthest from coal oil and gas production, spent considerable time discussing renewables, and when asked about coal, oil and gas identified the need to transition and retrain dependent workers. Although the uranium sector is present in Saskatchewan and in closer proximity to Saskatoon, there was little knowledge or support for new small modular nuclear reactors.Graphic abstract