Papers by Keyword: Natural Gas

Abstract: The design and energy simulation of carbon dioxide captured process through which Liquefied Natural Gas (LNG) plant has been achieved using Monoethanolamine (MEA) as a solvent. An optimization and technical parameter study for which CO₂ captured process (CCP) from the flue gas of a natural gas liquefaction plant was formed based on absorption/desorption process with MEA solutions, using ASPEN HYSYS. This optimization was aimed at reducing the energy requirement for solvent regeneration, by investigating the effects of CO₂ removal percentage, stripper operating pressure and cooling water flow. Also, the study showed that major energy savings can be realized by optimizing the lean solvent loading the CO₂ transmission phase as well as the stripper operating pressure through the compression and pumping process in the CCP. The specifications, equipment thickness, and cost models were developed based on the principles of conservation of mass and energy, and thermodynamic principles. Aspen HYSYS simulation was carried out on the entire CCP using flue gas of composition carbon dioxide (8.7%), water (17.8%), nitrogen (73.3%), oxygen (0.2%), sulphur dioxide (0.0017%), and nitrox (0.0097%) with input process conditions of pressure 101.6kPa, temperature 150°C and flow rate of 500tons per day. During the study, a minimum thermal energy requirement was found at a lean MEA loading of 0.13, using a 40 wt.% MEA solution and a stripper operating pressure of 130 kPa, resulting in a thermal energy requirement of 1.025 GJ/ton CO₂. Recoveries were done at 75%, 80%, 85%, 90%, 95% and 99% of the simulation process. Suitable correlation models were developed relating to the energy consumption rate per stripper operating pressure and specific thermal energy consumption per solvent flow rate with percentage recoveries. When compared to the simulation result, minimum errors of 0.05% and 2% respectively were obtained. The relationship between the compressor power and CO₂ recovery was linear at a minimum power consumption of 130 kW at 75% recovery while a maximum consumption of 175 kW was obtained at 99% recovery. It was observed that the specific thermal energy consumption per solvent is linearly related to the extent of recoveries, as higher energy was required to recover more CO₂. Compression and pumping with supercritical liquefaction taking the CO₂ above critical pressure of 100bar through three compression sections, inter-cooled to 40°C with water at ambient conditions. Thus, enhancing the high efficiency of the system. The HYSYS simulation results, the process conditions and the characterized flue gas were used for the manual computations to determine the efficiency of the CO₂, the size and specifications of the absorber and the amine regenerator columns. The HYSYS results obtained from the simulation of the entire CCP gave a recovery of 99% of the CO₂ removed from its initial content (8.7%). The energy and thermodynamic analysis of the CCP carried out gave result with the cycle efficiency of 94.92%, an efficient process with 20% energy reduction due to compression and pumping action done by incorporating pumps in the process. The results of the specifications from the material balance of the absorber and amine regenerator columns gave the diameter, height, and number of trays of these units in the CCP as, 2.215m; 10m, and 25, and 2m; 6m, and 20 respectively. While, the thickness results for the ellipsoidal doomed head and cylindrical shell of the absorber and amine regenerator columns were respectively given as, 8.27mm and 8.26mm, and 81.17mm and 78.33mm. The overall cost, including the cost of utilities, for the entire plant was obtained to be $19.629m.

Abstract: The presence of high CO₂ content in natural gas reservoirs is one of the significant threats to the environment. Cryogenic CO₂ capture technology is amongst the emerging technologies used for natural gas purification before customer use. In this research work, the binary CO₂-CH₄ mixture having 75% CO₂ content is studied. Aspen Hysys simulator with Peng Robinson property package is used for the prediction of phase equilibrium data for the binary mixture. The data obtained through the Aspen Hysys simulator is optimized for the S-V two-phase region for maximum CO₂ capture. Response surface methodology is used for the optimization of the predicted data. Optimization of the pressure and temperature conditions is done to obtain maximum CH₄ in the top stream and minimum CO₂ with minimum energy requirement. In this research work, the pressure and temperature ranges selected from the predicted phase equilibrium data for the optimization are 1 to 20 bar and-65 to-150 °C respectively. At atmospheric pressure and-123.50 °C, the desirability value is maximum, which is 0.843. under these conditions, the CO₂ and CH₄ in the top product stream are 1070.72 Kg/hr and 152.04 Kg/hr respectively with an energy requirement of 2.087 GJ/hr.

Abstract: It was determined that the current method of the Bakalsk mining department siderite ore preparation for blast-furnace smelting does not allow production of concentrate meeting the state-of-the-art metallurgy requirements. The most perspective method is reducing firing when a metallized product with higher iron content is obtained. It was demonstrated that implementation of this method requires the use of a three-zone shaft furnace having the oxidizing roasting zone, the reduction zone and the reduced product cooling zone. Experiments were carried out on the siderite ore reducing firing on laboratory units. The possibility in principle was demonstrated for production of the reduced product with iron content of 60 – 65% from the siderite ore. After the magnetic dressing the concentrate with iron content of 65 – 75% was obtained. It was determined that firing and reduction in hydrogen atmosphere result in the fired product reduction degree of 97 %. The possibility to produce a product suitable for blast-furnace conversion with the reduction degree of about 60% with the use of natural gas air conversion gas was demonstrated. The obtained results were used in the process development for the siderite ore reducing firing in a three-zone shaft furnace.

Abstract: Results of the design analysis carried out using computer software are presented for boundary data complying with the currently operating state-of-the-art arc steel furnace. Flow of natural gas combustion products and oxygen are reviewed for the radial and tangential burner arrangement in the working space between the wall and the electrodes. Location of high temperature fields is determined and the expected heat transfer to the charge materials through the active surface participating in heat exchange is evaluated. Precipitation degree is determined for the dust participating in scull generation on a wall water-cooled surface and significant reduction of dust effect on electrodes.

Abstract: The oil and gas industry represents an important contributor to CO₂ emissions as offshore platforms are power intensive for producing, processing and transporting hydrocarbons. In offshore rigs CO₂ emissions mainly come from on-site gas-fired power generation for heat and electricity production. The accumulation of atmospheric CO₂ is one of the main causes of the planetary greenhouse effect, thus CO₂ emissions should be minimized. To achieve that, more energy efficient processes for natural gas (NG) conditioning are needed in order to minimize platform power consumption and thus lowering the associated generation of CO₂. In addition, in offshore scenarios gas-hydrate obstructions are a major concern in flow assurance strategies, since thermodynamic conditions favoring hydrate formation are present, such as high pressure, low external temperature and gas contact with free water. To avoid hydrate issues, hydrate inhibition is carried out by the injection of a thermodynamic hydrate inhibitor (THI) in well-heads such that it flows along with production fluids, thus removing the thermodynamic conditions for hydrate formation and ensuring unimpeded flow. Therefore, the three-phase high-pressure separator (HPS) is fed with production fluids, where the HPS splits the feed into: (i) an upper gas phase, (ii) hydrocarbon condensate, and (iii) a bottom aqueous phase. The gas phase goes to NG conditioning for hydrocarbon dew point adjustment (HCDPA) and water dew point adjustment (WDPA) so as to make NG exportable. The hydrocarbon condensate (if present) is collected for stabilization and the bottom aqueous phase consisting of water, salts and THI is sent to a THI recovery unit (THI-RU) for THI re-concentration and reinjection. In conventional plants, WDPA and HCDPA are done by glycol absorption and Joule-Thomson expansion respectively. Moreover, the HPS gas carries some THI such as methanol that is lost in the processing. This work analyses a new process – SS-THI-Recovery – where HPS gas feeds a supersonic separator (SS) with injected water and compares it to the conventional processing. As a result, SS ejects a cold two-phase condensate with almost all water, THI and C3+ hydrocarbons, discharging exportable NG with enough HCDPA and WDPA grades, while the condensate gives aqueous THI returned to the THI-RU and LPG with high commercial value. Thus, SS-THI-Recovery not only avoids THI losses as well as exports NG and LPG. Both conventional gas plant and SS-THI-Recovery alternative coupled to THI-RU were simulated in HYSYS 8.8 for a given NG field and targeting the same product specifications. SS-THI-Recovery presented lower power consumption and thus less associated CO₂ emissions, while potentially increasing the gas plant profitability, as THI losses are significantly reduced and higher flow rate of LPG with higher commercial value is produced in comparison with the conventional alternative. Hence, the higher efficiency of SS-THI-recovery makes it not only more environmentally friendly with lower CO₂ emissions, but also a potential alternative for improving process economics and thus providing an economic leverage that could justify investments in carbon capture technologies, contributing to avoid CO₂ emissions even more with cleaner NG and LPG production.

Abstract: Open burning of natural gas when using gas equipment in the premises of residential buildings is considered, taking into account the formation of combustion products, depending on the coefficients of excess air. Theoretical and experimental studies of combustion processes are presented. To determine the aerodynamic process in the ventilation duct, theoretical calculations of the dependence of the discharge at the entrance to the ventilation duct from the outside temperature of the atmospheric air were made. Graph-analytic method of evaluating the effectiveness of natural ventilation is carried out.

Abstract: The technology of transportation and storage of gas in a gas-hydrated form under atmospheric pressure and slight cooling – the maximum cooled gas-hydrated blocks of a large size covered with a layer of ice are offered. Large blocks form from pre-cooled mixture of crushed and the granulated mass of gas hydrate. The technology of forced preservation gas hydrates with ice layer under atmospheric pressure has developed to increase it stability. The dependence in dimensionless magnitudes, which describes the correlation-regressive relationship between the temperature of the surface and the center gas hydrate block under its forced preservation, had proposed to facilitate the use of research results. Technology preservation of gas hydrate blocks with the ice layer under atmospheric pressure (at the expense of the gas hydrates energy) has designed to improve their stability. Gas hydrated blocks, thus formed, can are stored and transported during a long time in converted vehicles without further cooling. The high stability of gas hydrate blocks allows to distributed in time (and geographically) the most energy expenditure operations – production and dissociation of gas hydrate. The proposed technical and technological solutions significantly reduce the level of energy and capital costs and, as a result, increase the competitiveness of the stages NGH technology (production, transportation, storage, regasification).

Abstract: The present study has been attempted to systematically perform a visualizing analysis plan which can improve the flow rate, velocity and mass flow rate as a function of the size of the welding section in the injector as a key for the determination of the injection amount and time of the fuel (CH₄) system for natural gas. As the setting conditions for the analysis, a minimum pressure of 2 bar and a maximum pressure of 8 bar were set to be the total pressure values in the case of the inlet, while 0 bar was set for opening drain to represent the state in the atmosphere in the case of the outlet. As a result, the characteristics with an increase in velocity could be affirmed as strong flow separation and eddy current were produced according to the model with a large size of welding section. An excellent performance with an improvement in the performance of velocity flow rate by about 40% could be affirmed in the model where the size of the welding section was designed to be 6 EA.

Abstract: Current engines are readily available for CNG bi-fuel conversions because it requires only minor engine modifications. However, CNG flame speed is lower than gasoline, therefore reducing the power and range of the vehicle when operating on CNG. This situation can be improved by increasing the flame speed via higher turbulence generated by swirl motion. A computational fluid dynamics (CFD) model was used to analyse the swirl generated by dissimilar valve lift (DVL) profiles on the intake valve. A 3D engine simulation shows differences in swirl motion and turbulence between the original symmetric valve lift profile and the DVL. The swirl before combustion was found to increase almost 25%. The higher swirl number can increase the turbulence kinetic energy (TKE) level which improves better fuel mixing. The 1 mm DVL proved to be the better choice from CFD analysis and later was tested on a K3-VE engine. Pressure analysis shows peak pressure increased by 5.6% and burn rate shows CNG had a slower burning speed on the small engine

Abstract: Biogas is a fuel made from the anaerobic digestion of organic material to form methane. It can be used to power a stationary engine to generate electricity making it a viable method of decentralised power generation from renewables. However, biogas is a mixture of methane and carbon dioxide, and other trace gases such as hydrogen, hydrogen sulphide and oxygen. As such the quality can vary and setting the air-fuel ratio for efficient combustion can be problematic under these conditions. The Wobbe Index, or Wobbe Number, is a quality of combustible gases that allows the air-fuel requirement to be determined. This work presents a novel type of Wobbe Index sensor based on a miniaturised capillary viscometer that can be used with biogas. The sensor is validated at a biogas cogeneration plant which uses a stationary engine and the results are compared to a methane sensor installed at the plant.