Natural Gas Combustion Research Articles

Synthesis of Control Systems for Dynamic Pro-cesses in a Boiler Using a Neural Network of Direct Propagation

The article solves an urgent scientific and technical problem of reducing the cost of fuel for combustion in steam boilers by automating the process of adjusting the gas-air ratio, which will significantly reduce the cost of certified fuel and rationally use emissions from industrial installations, such as industrial furnaces, oil refineries, etc. The development of an air flow regulator for natural and blast-furnace gas burners will save valuable natural resources and expand the range of use of emissions as secondary raw materials. Goal. Development on the basis of a neural network of direct distribution of a control system for the supply of natural and blast-furnace gas to the burners of boilers operating on one steam line. Methodology. The synthesis of a neuro-regulator for air supply during the combustion of non-certified gases in a boiler for the generation of thermal energy or electricity was carried out by means of Simulink in the MATLAB system. In order to implement the regulation of the combustion air supply, a neuro-regulator with foresight was used, the operation of which is based on the principle of a receding horizon, according to which the neural network model of the controlled process foresees the reaction of the control object at a certain time interval in the future. The procedure for the synthesis of a neuro-regulator for the supply of air for combustion is given. The values of the parameters that provide the specified indicators of the quality of the dynamic process control system functioning are established. The model is trained offline using the available empirical information regarding the process of gas combustion in the boiler, obtained on the basis of production experience. The settings of the resulting neural network are carried out according to the test data of a real object. Results. The universal possibilities of approximation of multilayer artificial neural networks of direct propagation made it possible to solve the problem of identifying, designing and modeling nonlinear control systems. The implementation of the developed neuro-regulator with the anticipation of the combustion air supply allows the control system to adapt to changes between theoretical and actual indicators and take into account and compensate for the variable parameters of the air supply to the burners. Conclusions. A feed-forward neural network has been successfully implemented in the synthesis of control systems for dynamic processes of regulating the air flow to natural and blast-furnace gas burners.

Методика определения температуры точки росы продуктов сгорания природного газа

Currently, there are various methods to determine the dew point temperature of humid air and combustion products of distinct types of fuels. It is especially important when designing deep flue gas cooling systems in boiler plants that do not consider the composition of a particular type of fuel. In this regard, the urgent issue is the development of a simple method to calculate this value when using natural gas as fuel. The authors have used the methods of thermodynamic analysis of processes in humid air and fuel combustion products, and the results of thermal calculations of fuel combustion processes. The authors have conducted the analysis of existing methods to determine the dew point temperature for natural gas combustion products, since it is necessary to prevent condensation of water vapor in chimneys and chimney flue to ensure their operation conditions, especially during deep cooling. A simple method to calculate this value is proposed, and an example of its use is presented. The authors have analyzed the influence of such factors as the moisture content of air and natural gas, the absolute pressure of combustion products and the air flow coefficient per the dew point temperature. It is shown that the final refinement of the given value can be quite significant, and therefore the use of the method that allows considering these patterns is advisable when designing deep flue gas cooling systems. It is established that the proposed method is quite universal and can be used during combustion of natural gas of various compositions and various values of factors characterizing fuel combustion.

On the Demonstration of a Humid Combustion System Performing Flexible Fuel-Switch From Pure Hydrogen to Natural Gas With Ultra-Low NOx Emissions

Abstract To fight global warming the European Union formulated the objective of completely decarbonizing the energy sector, stimulating the advent of unconventional fuels and the adaption of the corresponding energy infrastructure. The decarbonization strategy identified hydrogen to play a key role as an energy storage medium, making systems capable of pure hydrogen operation essential. This requirement can be fulfilled with humid power cycles which offer additional advantages such as highly efficient and fuel-flexible operation with low emissions. As an integral part of such a cycle, a humid combustion system was presented previously showing promising results with respect to complete combustion with low emissions for a variety of fuels. The current work introduces an upgraded version of that combustion system. The new Double Swirler system is capable of stable and safe combustion of low calorific value biosyngas surrogate, hydrogen, and natural gas, from dry to steam-rich conditions within the required pressure drops. The inclusion of dry operation of the system can benefit the startup procedure of the humid cycle. The combustor's fuel switching performance is demonstrated by a fast fuel switch at full load from pure hydrogen to pure natural gas and vice versa, while maintaining a stable performance with low NOx-emissions at otherwise constant operation parameters.

Pathways for low carbon hydrogen production from integrated hydrocarbon reforming and water electrolysis for oil and gas exporting countries

Integrated hydrocarbon reforming processes with H2O electrolysis for H2 production have been developed to reduce greenhouse gas (GHG) emissions in oil and gas exporting countries (OGEC). The developed system includes steam methane reforming (SMR), gas-heated autothermal reforming (GH-ATR), autothermal reforming (ATR) and partial oxidation (POX). Each of these systems operates with H2O electrolysis to increase the H2 production rate and feed O2 to the reformers. The combined systems also incorporate thermophotovoltaic (TPV) units, solar cells, a wind turbine system and a Rankine cycle to convert waste heat to electricity and generate more electrical energy. Parabolic dish concentrators (PDCs) produced thermal energy for endothermic reactions. The introduction of H2 fuel cells replaced the burning of natural gas in power plants to generate electricity. The result of this study reveals that using renewable energy sources and energy recovery units to produce distilled H2O and operate other downstream units, the H2 selling price of the proposed system is expected to be <$2.9/kg. Efficiency improvement by ≥10% for each hydrocarbon reforming method operating with other units was also achieved in contrast to the current hydrocarbon reforming processes. The provided integrated method will provide a high-value chain in the H2 generation industry and promote carbon neutrality in oil and gas rich countries.

Distribution, Sources, and Health Risk of Polycyclic Aromatic Hydrocarbons in Farmland Soil of Helan, China

With the development of industry and agriculture, polycyclic aromatic hydrocarbons (PAHs) in the agricultural sector have gradually increased to different degrees, leading to an escalation in environmental pollution. In turn, this escalation has presented a significant possibility of endangering agricultural practices on farmland and has had a serious impact on regional sustainable development. Therefore, a total of 117 samples of soil were gathered to research the pollution level, distribution, sources, and health risk of PAHs in Helan farmland soils. A reference was used for the identification and quantification of PAH content using high-performance liquid chromatography (HPLC) with an ultraviolet detector, and their spatial distribution was analyzed utilizing the Arc Geographic Information System (ArcGIS). The source of PAHs was analyzed by absolute principal component scores/multiple linear regression (APCS-MLR). The lifetime cancer risk increment model and Monte Carlo sensitivity analysis were used to assess the potential health hazards to humans associated with PAHs in soil. Within the current study area, PAHs were higher in the northwest. The results showed that the total content of PAHs in Helan farmland soil ranged from 17.82 to 1544.73 ng·g−1 with a mean of 408.18 ng·g−1, which indicated the middle degree of pollution in farmland soil. The verification results of the APCS-MLR model showed that the correlation coefficient between the measured values and the predicted values ranged from 0.661 to 0.984, which suggested that the APCS-MLR model demonstrated favorable suitability for conducting source analysis of PAHs in the soil within the study region. Based on the contribution of PAHs from each source, the main sources of PAHs in Helan farmland soil were the combustion source (biomass, diesel, and natural gas combustion) and the transportation source (gasoline for vehicles and traffic exhaust emissions). The health risks’ estimation showed that PAHs in farmland soil did not have potential health risks for adults but represented a carcinogenic risk for children via the main exposure pathway of ingestion with the mean intake of 1.28 × 10−5. Meanwhile, the carcinogenic risks (CRs) of dermal contact for the mean value of adults (9.32 × 10−7) was found to be higher than that for children (3.18 × 10−8). From the Monte Carlo simulation, the soil particle uptake rate was the most sensitive to the health risks of children and adults with risk probabilities of 26% and 52%, and the risk probabilities from body weight were −11% and −1%, whose negative value indicated that the increase in body weight could reduce the health risks to human. These findings could provide reference for the study of soil organic pollution in Helan farmland soil and contribute significantly to the preservation of the ecological environment, maintaining human health and safety, and promoting the sustainable development of regional farmland.

The Impact of Oxidation-Induced Degradation on Materials Used in Hydrogen-Fired Microturbines

Abstract Hydrogen-fueled microturbines are being considered as part of the future green microgrid. However, the use of hydrogen as a fuel presents new challenges for selection and development of suitable high temperature materials for hydrogen combustion. The burning of hydrogen is expected to result in higher operating temperatures and higher than typically observed water vapor contents in exhaust gases versus burning natural gas. In this work, foil specimens of various Fe- and Ni-based alloys were oxidized in air + 10% H2O and air + 60% H2O for up to 5000 h at 700 °C to simulate the exhaust atmosphere of natural gas and hydrogen-fueled microturbines. The impact of alloy composition and water vapor content on the oxidation/volatilization induced loss of wall thickness was experimentally evaluated. Enhanced external oxidation and volatilization of Cr2O3 and Ti-doped Cr2O3 scales were observed in air + 60% H2O compared to air + 10% H2O. No significant impact of the higher water vapor content was observed on Al2O3 scales formed on Fe-based alumina-forming austenitic alloys. Lifetime modeling was employed to predict the combined effects of water vapor content, gas flow rates, temperature, and alloy composition on the oxidation-induced lifetime of the investigated materials.

Experimental investigation of various burner heads in residential gas stoves tested with hydrogen and natural gas blends

The current study is designed to investigate the effect of five different burner head geometries of gas stoves. The amounts of heat required for boiling 380 grams of water in a pot for a stove for these several burner heads are measured. The flow rates are set to be 3 L/min and 6 L/min for experimental tests. These experimental results show that the burner head with three lateral sets of holes and two circular sets of holes at the top gives the minimum heating time when burning natural gas alone. Once the hydrogen-natural gas mixture is used, the burner head with one lateral and three top circular sets of holes shows the best performance among others regarding heating time. The effect of the flow rate increase is also investigated. Once the flow rate doubles, the burner head with three lateral sets of holes offers the best performance. Based on the findings of the experiments, it can be said that burner heads with lateral sets of holes operate better than other geometries. When natural gas is utilized as fuel, it is observed that the burner head with three lateral sets of holes and two circular sets of holes at the top provided a 12% reduction in heating time compared to the conventional burner head. For the natural gas and hydrogen blends, the conventional burner head achieves the best in terms of heating time.

Thermoacoustic Characterization of a Premixed Multi Jet Burner for Hydrogen and Natural Gas Combustion

Abstract In this study, the acoustics and flame dynamics of a prototype multi jet burner with 19 individual mixing tubes for operation with pure hydrogen and pure natural gas are experimentally investigated. The burner transfer matrix (BTM) of the jet burner is determined from experimental data and acoustic network modeling, showing very good agreement. The burner plate and attached mixing tubes are shown to be well approximated with an acoustic model of a perforated plate with bias flow. Accordingly, the burner is found to feature a high level of acoustic damping. A comparison of the flame dynamics of the two fuels considering mass flow and equivalence ratio variation reveals that the flame transfer functions (FTFs) are dominated by a convective mechanism originating from the upstream end of the mixing tubes where the fuel is injected. Consequently, these are most likely fluctuations in the equivalence ratio that feature two characteristic time scales: the convection time in the mixing tubes and along the flame. The overall qualitative shape of the FTFs for hydrogen and natural gas at equal thermal power is found to be similar, with the dynamics of the natural gas flames being more responsive to acoustic excitation, as evident in generally higher gain values. Distinctly less pronounced phase decays are observed for hydrogen compared to natural gas operation. Moreover, the FTFs for H2 are found to change only slightly across the considered range of equivalence ratios. At the same time, we observe only small changes in the corresponding static flame shapes. These observations are consistent with the hypothesis of a dominant convective mechanism. In conclusion, the study provides valuable information on the acoustics and flame dynamics of multi jet burners for flexible fuel operation.

Investigation on the Combustion Characteristics and Environmental Effects of Hydrogen-doped Natural Gas for Domestic Water Heaters.

The addition of hydrogen to natural gas is an effective approach to broaden the range of applications for hydrogen and address the issue of global warming. However, the inclusion of hydrogen alters the combustion properties of natural gas. The paper established a simplified mechanism consisting of 19 components and a 67-step reaction for hydrogen-doped natural gas combustion. With this simplified mechanism, the effects of hydrogen doping and the utilization of porous media combustion techniques on the combustion characteristics of natural gas were investigated numerically. The results suggested that the utilization of porous media combustion technology is beneficial for achieving the complete combustion of hydrogen-doped natural gas and reducing pollutant emissions. Additionally, the total gas cost and environmental impact of domestic gas water heaters with hydrogen-doping natural gas were estimated. The findings show that the use of 20% hydrogen-doped natural gas contributes to a decrement in fuel costs and reduced emissions of CO by 25.4%, NOX by 53.9%, and CO2 by 6.78%.

Optical Study on the Effects of Methane Equivalence Ratio and Diesel Injection Mass on Diesel-Ignited Methane Combustion Process

Pilot diesel ignition is an effective approach for achieving efficient and clean combustion of natural gas. In this study, a rapid compression and expansion machine (RCEM) was constructed for examining diesel-ignited premixed methane combustion. The effects of the methane equivalence ratio and pilot diesel mass on the combustion process of diesel-ignited premixed methane gas were investigated. The results show that the combustion process can be divided into two stages: diesel dominance and premixed methane combustion. An increase in the methane equivalence ratio inhibits diesel combustion, leading to delayed CA10 and OH radical generation. However, it enhances premixed methane flame propagation and improves the heat release rate, resulting in a shorter combustion duration. An increase in the pilot diesel mass contributes to a larger flame area and higher OH generation intensity in the ignition region; however, too large a diesel mass inhibits methane flame propagation towards the diesel nozzle due to an extended injection duration. In conclusion, a larger pilot diesel mass can achieve better overall combustion performance, but excessive amounts may be counterproductive.

Results of the testing of an automated control system and the application of natural gas burners

Purpose. Testing an automated control system to improve the accuracy of calculating natural gas costs in coalfields and provide reliable information to suppliers and consumers regarding mutual settlements. Research methods. The conditions of operation of the mine degassing system and the methods of monitoring its operational indicators for effective management of the technical condition of the object in the real conditions of the mine environment are considered. Approaches to continuous monitoring of well parameters using structural modules of the ACS of the DSH have been determined. Findings. The DSH ACS module was implemented in the real conditions of the mine environment, which made it possible to carry out automatic monitoring of the methane-air mixture, measurement and preparation for issuing to the operational personnel the current values of pressure drops on the diaphragms, absolute pressure, temperature and volume flow of gas. Originality. A new method of increasing the accuracy of commercial accounting of natural gas of coal deposits has been developed, which consists in constant monitoring of the technical condition of the degassing system and automated accounting of natural gas based on the «DIYA» measuring complex. The average hourly values of gas mass flow were obtained, as well as the difference between the data of the channel of the operating ASUTP KS and the channel of the "Ergomera"-126.MU controller in the complex with the "DIYA" operator station. Practical implications. A mine experiment was conducted on monitoring and control of mine degassing gas pipelines using innovative technical solutions for the rapid and systematic delivery of information about the parameters of the mine degassing system to the dispatch service. The structure, principle of operation, methodology for calculating the consumption of natural gases and coal field gases were developed, and industrial tests of an experimental sample of the ACS of the DSH were carried out with automatic entry of results into electronic reporting journals.

Quantification of fossil fuel CO2 from combined CO, δ13CO2 and Δ14CO2 observations

Abstract. We present a new method for partitioning observed CO2 enhancements (CO2xs) into fossil and biospheric fractions (Cff and Cbio) based on measurements of CO and δ13CO2, complemented by flask-based Δ14CO2 measurements. This method additionally partitions the fossil fraction into natural gas and petroleum fractions (when coal combustion is insignificant). Although here we apply the method only to discrete flask air measurements, the advantage of this method (CO- and δ13CO2-based method) is that CO2xs partitioning can be applied at high frequency when continuous measurements of CO and δ13CO2 are available. High-frequency partitioning of CO2xs into Cff and Cbio has already been demonstrated using continuous measurements of CO (CO-based method) and Δ14CO2 measurements from flask air samples. We find that the uncertainty in Cff estimated from the CO- and δ13CO2-based method averages 3.2 ppm (23 % of the mean Cff of 14.2 ppm estimated directly from Δ14CO2), which is significantly less than the CO-based method which has an average uncertainty of 4.8 ppm (34 % of the mean Cff). Using measurements of CO, δ13CO2 and Δ14CO2 from flask air samples at three sites in the greater Los Angeles (LA) region, we find large contributions of biogenic sources that vary by season. On a monthly average, the biogenic signal accounts for −14 to +25 % of CO2xs with larger and positive contributions in winter and smaller and negative contributions in summer due to net respiration and net photosynthesis, respectively. Partitioning Cff into petroleum and natural gas combustion fractions reveals that the largest contribution of natural gas combustion generally occurs in summer, which is likely related to increased electricity generation in LA power plants for air-conditioning.

An Adsorption-Desorption Heat Engine for Power Generation from Waste Heat

According to the United States Department of Energy, waste heat recovery would allow up to a 20% reduction in greenhouse gases (GHG) emission. Most of the waste energy is discharged as a low-grade heat at temperatures less than 250°C. Therefore, the development of new technologies and the enhancement of existing ones to convert low-grade heat into electrical or mechanical energy are of great importance. The working principle of adsorption-desorption heat pumps with cyclic switching between adsorption and desorption is adapted in the proposed heat engine to generate electrical power from low-temperature heat. Thermodynamic analysis of the heat engine cycle is carried out for the pair adsorbant-adsorbent: CO&lt;sub&gt;2&lt;/sub&gt;-activated carbon. Its efficiencies are calculated accepting the ideal gas law and an adsorption-desorption equilibrium at the key points of the cycle. The cycle consists of two isochores and two isotherms like the Stirling engine, but at the same temperature range and without heat regeneration, its thermal efficiency (work per heat supplied) can reach 11.3% vs. 5.0% and specific work 50.7 vs. 3.55 in the latter. The proposed unit has thermal efficiency in the range of Organic Rankine Cycle units and can be utilized in small-scale applications up to 40kWe, where manufacturing cost of turbines or expanders for ORCs increases dramatically. Accounting for quality (temperature) of utilized heat, the proposed cycle’s exergy efficiency, &lt;em&gt;ζ&lt;sub&gt;ex&lt;/sub&gt;&lt;/em&gt; = 34.5% approaches that of water-steam Rankine cycles utilizing natural gas or coal combustion.

Characterization and Source Apportionment of Polycyclic Aromatic Hydrocarbons in PM2.5 in Lanzhou

To study the pollution characteristics and sources of 16 PAHs in PM2.5 in Lanzhou, PM2.5 samples were collected in four seasons. GC-MS was employed to analyze the concentration of PAHs. Positive matrix factorization(PMF), trajectory cluster, and potential source contribution function(PSCF) were used to identify the sources of PAHs. The results indicated that the average concentration of PAHs in PM2.5 in Lanzhou decreased in the order of winter[(118±16.2) ng·m-3]>autumn[(50.8±21.6) ng·m-3]>spring[(22.2±8.87) ng·m-3]>summer[(4.65±1.32) ng·m-3]. The results of correlation analysis showed that PM2.5 and TPAHs in Lanzhou had an extremely significant negative correlation with temperature; an extremely significant positive correlation with atmospheric pressure; and a poor correlation with wind direction, wind speed, and relative humidity. The proportion of PAHs with 4-5 rings was much higher than that of those with 6 rings and 2-3 rings, with similar results across the four seasons. Source apportionment results illustrated that the contribution of industrial emissions and biomass and natural gas combustion were dominant in spring and summer seasons. Industrial emissions and coal combustion were dominant in autumn and winter, respectively. The vehicle emissions had no significant change across the four seasons. Trajectory cluster and PSCF analyses showed that the airflow coming from Mongolia, northeast Xinjiang, and Qinghai had important effects on the ambient air quality in Lanzhou.

Breathing in danger: Unveiling the link between human exposure to outdoor PM2.5-bound polycyclic aromatic hydrocarbons and lung cancer risk in an urban residential area of China

Numerous studies have extensively examined the risk of lung cancer associated with polycyclic aromatic hydrocarbons (PAHs), with particular emphasis on the 16 priority PAHs. However, this may underestimate the actual risk. This study seeks to enhance the current risk assessment framework by integrating four additional parent PAHs such as Dibenzo[a,h]pyrene, Dibenzo[a,l]pyrene, Dibenzo[a,e]pyrene, 7H-benzo[c]fluorene with potentially high risk of causing cancer. By considering their physicochemical properties, metabolism, and bioavailability, the study also examines the relationship between low molecular weight (LMW) - and high molecular weight (HMW)-PAH doses and the risk of developing cancer in the human lungs. The study was conducted in Ningbo, China and identified five PAH sources: natural gas combustion (NGC), vehicular exhaust (VE), coal combustion (CC), biomass burning (BB), and volatilization of unburnt fuel (VUF). This study emphasizes the elevated risk associated with highly carcinogenic PAHs, as they consistently exceed acceptable limits for lung cancer risk throughout the year. Based on the study's estimation, approximately 324 out of every one million individuals exposed to PAHs face an increased cancer risk over their lifetime. This research emphasizes the importance of identifying source specific lung cancer risk in residential areas to protect the exposed population. Moreover, while there is a moderate connection between LMW-PAH doses and lung cancer risk, a strong relationship is observed with HMW-PAHs.

Concentrated solar power integration with refinery process heaters

Crude oil heating is considered an energy-intensive process in the oil industry that requires a huge amount of heat to process the crude oil. There is scarcity of a thorough research that deals with the techno-economic viability of introducing renewable energy solutions to the refinery industry including its environmental benefits. Therefore, a renewable energy solution i.e. a parabolic trough system is reviewed and examined to support minimizing the burning of natural gas in crude heaters and relying on thermal heat from sun radiation to increase crude oil temperature prior to going into the fractionation column. The system is designed to support refinery operation during day time whereas system design and analysis were done from thermal and financial points of view. Furthermore, benefits such as natural gas savings, reduction in CO2 emissions, and total payback period are presented in the paper to reflect the feasibility of constructing such a solution. Moreover, a MATLAB simulation was carried out to define the design points for the solar field and related heat exchanger components. This is to assure that the system can operate during winter and summer seasons given that the direct normal irradiance (DNI) is typically variant throughout the year. It has been concluded that integrating a parabolic trough collector into the operation of an oil refinery, i.e. crude oil heater, can potentially result in natural gas savings of 555,515 MMBtu and can prevent 30,020 tons of CO2 emissions annually. Moreover, the system is anticipated to result in cost savings of approximately 1.65 M $ per year.

Role of biomethane to offset natural gas

The use of biomethane, produced through anaerobic digestion of organic waste, holds promise as an energy source for mitigating climate change. This study quantifies the technical potential of biomethane, considering neither socio-economic nor political constraints, and then compares it to worldwide natural gas use and imports. Furthermore, it calculates the potential emission reduction achieved by substituting natural gas with biomethane. We find that biomethane can offset 29% of natural gas use and two-thirds of natural gas net-imports worldwide. Considering the European energy crisis arising from the Russian-Ukrainian conflict, we analyze the potential for each European country to generate enough biomethane to decrease their reliance on imported Russian natural gas. Our estimates indicate that almost one-third of European countries, including the United Kingdom, France, Spain, Ireland, Slovenia, Romania, Greece, Sweden, and Portugal, have the potential to completely replace their natural gas imports from Russia by utilizing domestic biomethane production. Our study also evaluates how biomethane can reduce greenhouse gas emissions by substituting fossil natural gas, while considering methane leaks in both biomethane and natural gas supply chains and carbon emissions from fossil natural gas combustion. Our results indicate that replacing fossil natural gas with biomethane will decrease emissions from natural gas systems by 11%, equivalent to 1.1 Gt CO2-eq per year. These findings illustrate the potential of biomethane in reducing our dependence on fossil natural gas and mitigating its emissions.

Boil-off recovery system for natural gas stations: an approach to increase energy efficiency and reduce greenhouse gases

AbstractImproving the efficiency of energy use is of utmost importance in the context of climate change. Indeed, greater efficiency in the end-use of energy will make a significant contribution to lowering primary energy consumption and reducing CO2 and other greenhouse gas emissions. This paper presents an approach that enables a compact liquefied natural gas station to operate without being connected to the public electric grid. It is achieved by using the Boil-off gas generated by the vehicle supply process and feeding it to a generator which, together with a photovoltaic (PV) system, can produce electrical energy. Results from a year of trial operations at the station in Escariz, Portugal, demonstrate that it is possible to recover an average of 8.66 kg of Boil-off gas daily while generating a 345% excess of electrical energy when combined with the PV system, enabling the station to be self-sustainable in terms of electricity. Based on the experimental data and calculation methodology, the project was able to earn an estimated monthly revenue of €176.27 throughout the study period while also preventing the emission of 8549 kg of CO2 equivalent from natural gas combustion in vehicles.

Results of the testing of an automated control system and the application of natural gas burners

Purpose. Testing an automated control system to improve the accuracy of calculating natural gas costs in coalfields and provide reliable information to suppliers and consumers regarding mutual settlements. Research methods. The conditions of operation of the mine degassing system and the methods of monitoring its operational indicators for effective management of the technical condition of the object in the real conditions of the mine environment are considered. Approaches to continuous monitoring of well parameters using structural modules of the ACS of the DSH have been determined. Findings.The DSH ACS module was implemented in the real conditions of the mine environment, which made it possible to carry out automatic monitoring of the methane-air mixture, measurement and preparation for issuing to the operational personnel the current values of pressure drops on the diaphragms, absolute pressure, temperature and volume flow of gas. Originality. A new method of increasing the accuracy of commercial accounting of natural gas of coal deposits has been developed, which consists in constant monitoring of the technical condition of the degassing system and automated accounting of natural gas based on the «DIYA» measuring complex. The average hourly values of gas mass flow were obtained, as well as the difference between the data of the channel of the operating ASUTP KS and the channel of the "Ergomera"-126.MU controller in the complex with the "DIYA" operator station. Practical implications. A mine experiment was conducted on monitoring and control of mine degassing gas pipelines using innovative technical solutions for the rapid and systematic delivery of information about the parameters of the mine degassing system to the dispatch service. The structure, principle of operation, methodology for calculating the consumption of natural gases and coal field gases were developed, and industrial tests of an experimental sample of the ACS of the DSH were carried out with automatic entry of results into electronic reporting journals.

An Experimental Comparison of Cyclic Variations in Diesel–Natural Gas and POMDME–Natural Gas Dual Fuel Combustion

Abstract Cyclic variations in internal combustion engines are caused by various factors, including combustion mixture stratification, in-cylinder flows, local fluctuations in air-fuel ratio, etc. Cyclic variations have a profound impact on engine performance and emissions. In this study, cyclic variations in dual fuel combustion are analyzed, comparing diesel–natural gas (NG) and polyoxymethylene dimethyl ether (POMDME)-NG dual fuel combustion. Cyclic variability was initially quantified using the coefficient of variation of gross indicated mean effective pressure (IMEPg) computed from experimental cylinder pressure data. The cases analyzed in this study had a coefficient of variation (COV) of IMEPg greater than or around 5%, which was the lower limit of onset of instability for this engine. Experiments were performed at two fixed start of injection (SOI) of high-cetane fuel: 310 CAD and 350 CAD. For all experiments, a constant load of 5 bar IMEPg was maintained, and the intake boost pressure and rail pressure were fixed at 1.5 bar and 500 bar, respectively. For each case, 1000 cycles of cylinder pressure data were recorded, filtered, and processed using an in-house heat release analysis code for each cycle. A comparison between individual cycles and the “ensemble averaged cycle” was made for both diesel–NG and POMDME–NG combustion. For the early SOI of 310 CAD, the peak cylinder pressure fluctuations of individual cycle were found to be ± 15 bar for both fuel combinations, compared to the ensemble averaged cycle, and &amp;lt; 1/10th of the cycles had an IMEPg lower than 0.05 bar of the ensemble averaged cycle. However, the peak pressure fluctuations were found to be lower for POMDME–NG (±3 bar) than diesel–NG dual fuel combustion at 350 CAD SOI, indicating lower cyclic variations. The higher reactivity of POMDME helped reduce fluctuations in combustion phasing at the retarded SOI. The presence of cycles of deterioration and cycles of recovery were also observed with diesel–NG combustion for 310 CAD SOI, and the scatter in the IMEPg return map was similar for both fuel combinations. The IMEPg return map for POMDME–NG combustion was less scattered at the 350 CAD SOI.