scholarly journals Dynamic Characteristics of Offshore Natural Gas Hydrate Dissociation by Depressurization in Marine Sediments

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Xinfu Liu ◽  
Chunhua Liu ◽  
Jianjun Wu
Keyword(s):  
Natural Gas ◽  
Water Flow ◽  
Marine Sediments ◽  
Flow Rate ◽  
Gas Flow ◽  
Water Flow Rate ◽  
Water Production ◽  
Gas Flow Rate ◽  
Natural Gas Hydrate ◽  
Natural Gas Flow

Dynamic characteristics of offshore natural gas hydrate (NGH) dissociation will provide the theoretical basis to analyze technical issues of oceanic hydrate exploitation. A mathematical model is developed to simulate offshore NGH dissociation by depressurization in marine sediments. Different phase combination statuses are involved in the process of NGH dissociation by taking ice melting and water freezing into account. The proposed methodology can analyze the processes of hydrate and water phase transitions, decomposition kinetics and thermodynamics, viscosity and permeability, ice-water phase equilibrium, and natural gas and water production. A set of an experimental system is built and consists of one 3-D visual reactor vessel, one isothermal seawater vessel, one natural gas and water separator, and one data acquisition unit. The experiments on offshore NGH dissociation by depressurization in 3-D marine sediments are carried out, and this methodology is validated against the full-scale experimental data measured. The results show that during the prophase, natural gas flow is preceded by water flow into the production wellbore and natural gas occupies more continuous flow channels than water under a large pressure gradient. Then, the natural gas flow rate begins to decline accompanied by an increase of water production. During the second phase, natural gas flow rate decreases slowly because of the decreased temperature of hydrate-bearing formation and low pressure gradient. The lower the intrinsic permeability in marine sediments, the later the water flow rate reaches the peak production. And the space interval of the production wellbore should be enlarged by an increase of the intrinsic permeability. The stable period of natural gas production enhances, and the water flow rate reduces with the increase of bottom-hole pressure in production wellbores. The main reason is the slow offshore NGH dissociation under the low producing pressure and the restriction of heat conductivity under the low temperature.

scholarly journals Improving the blast furnace process by raising the natural gas flow rate in the upper heat exchnage stage

2017 ◽  
Vol 15 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Salavat K. Sibagatullin ◽  
◽  
Aleksandr S. Kharchenko ◽  
Vitaly A. Beginyuk ◽  
Valentin N. Selivanov ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Natural Gas ◽  
Flow Rate ◽  
Gas Flow ◽  
Blast Furnace Process ◽  
Gas Flow Rate ◽  
Furnace Process ◽  
Natural Gas Flow

Removal of NO from Gas by Corona Discharge with H2O2 Solution Oxidation

2013 ◽  
Vol 742 ◽  
pp. 323-326 ◽  
Author(s):  
Ji Wu Li ◽  
Zhi Peng Tang ◽  
Jie Yu
Keyword(s):  
Corona Discharge ◽  
Water Flow ◽  
Flow Rate ◽  
Flue Gas ◽  
Gas Flow ◽  
Supply Voltage ◽  
Removal Rate ◽  
Water Flow Rate ◽  
Gas Flow Rate ◽  
No Removal

The effects of the supply voltage, water flow rate, concentration of H2O2absorption and flue gas flow rate on NO removal rate were studied. The chemical reaction mechanism of NO removal was discussed. It was concluded that the NO removal rate increased the increasing of supply voltage, water flow rate and concentration of H2O2, and decreased with the increasing of the flue gas flow rate on the experimental conditions. On the synergy with corona discharge and H2O2solution oxidation, NO removal rate reached 60.2%.

scholarly journals Biogas Upgrading to Biomethane by CO2 Removal using Water Absorber with Microbubble Technique

2021 ◽  
Vol 18 (10) ◽  
Author(s):  
Chananchida DUMRUANGSRI ◽  
Prukraya PONGYEELA ◽  
Juntima CHUNGSIRIPORN
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Gas Flow ◽  
Water Flow Rate ◽  
Operating Conditions ◽  
Experimental Unit ◽  
Co2 Removal ◽  
Gas Flow Rate ◽  
Biogas Upgrading ◽  
Absorption Column

Biogas upgraded to biomethane can be utilized as a renewable energy source to substitute LPG in households and industry. This study explored biogas upgrading by CO2 removal from 20 - 75 % CO2-N2 simulated biogas mixture. The experimental unit using the microbubble technique combined with the water absorption column was set up and used for CO2 removal from the gas. Microbubble sizes of 20 - 30 µm were generated by a venturi ejector and measured with an automated bubble size measurement. The experiments confirmed that a microbubble with an inline mixer could enhance the effectiveness of the absorption process. The tests demonstrated over 85.80 % removal of CO2 from the simulated biogas by the experimental unit. The effects of various parameters, including the size of venturi ejector, gas flow rate, water flow rate, liquid-gas ratio, and initial concentration of CO2, were investigated. The results revealed that 2 L/min gas flow rate, 15 L/min water flow rate, L/G ratio 7.5, and venturi ejector size 0.50 inches are the optimum conditions. The use of the tube absorber gave much higher CH4 recovery than an absorption column. The appropriate operating conditions gave over 96 % CH4 concentration or less than 4 % CO2 concentration, matching the CH4 purity required by biomethane specifications. The results indicated that the new technique demonstrated in this study can upgrade biogas to biomethane.

SCIENTIFIC AND ENGINEERING PRINCIPLES OF EFFICIENT FUEL USE AND ENVIRONMENTALLY FRIENDLY GAS COMBUSTION IN STOVE PLATES. PART 1. MODERN STATE-OF-THE-ART AND DIRECTIONS FOR IMPROVEMENT THE GAS BURNING IN DOMESTIC GAS COOKERS

2017 ◽  
pp. 3-18 ◽  
Author(s):  
B.S. Soroka ◽  
V.V. Horupa
Keyword(s):  
Natural Gas ◽  
Flow Rate ◽  
Gas Flow ◽  
Renewable Energy Sources ◽  
Combustion Process ◽  
Orifice Diameter ◽  
Firing Process ◽  
Gas Flow Rate ◽  
Gas Combustion ◽  
Gas Stoves

Natural gas NG consumption in industry and energy of Ukraine, in recent years falls down as a result of the crisis in the country’s economy, to a certain extent due to the introduction of renewable energy sources along with alternative technologies, while in the utility sector the consumption of fuel gas flow rate enhancing because of an increase the number of consumers. The natural gas is mostly using by domestic purpose for heating of premises and for cooking. These items of the gas utilization in Ukraine are already exceeding the NG consumption in industry. Cooking is proceeding directly in the living quarters, those usually do not meet the requirements of the Ukrainian norms DBN for the ventilation procedures. NG use in household gas stoves is of great importance from the standpoint of controlling the emissions of harmful components of combustion products along with maintenance the satisfactory energy efficiency characteristics of NG using. The main environment pollutants when burning the natural gas in gas stoves are including the nitrogen oxides NOx (to a greater extent — highly toxic NO2 component), carbon oxide CO, formaldehyde CH2O as well as hydrocarbons (unburned UHC and polyaromatic PAH). An overview of environmental documents to control CO and NOx emissions in comparison with the proper norms by USA, EU, Russian Federation, Australia and China, has been completed. The modern designs of the burners for gas stoves are considered along with defining the main characteristics: heat power, the natural gas flow rate, diameter of gas orifice, diameter and spacing the firing openings and other parameters. The modern physical and chemical principles of gas combustion by means of atmospheric ejection burners of gas cookers have been analyzed from the standpoints of combustion process stabilization and of ensuring the stability of flares. Among the factors of the firing process destabilization within the framework of analysis above mentioned, the following forms of unstable combustion/flame unstabilities have been considered: flashback, blow out or flame lifting, and the appearance of flame yellow tips. Bibl. 37, Fig. 11, Tab. 7.

scholarly journals Research of the Influence of Temperature Factor on Express Control of Natural Gas Combustion Heat

2020 ◽  
pp. 44-50
Author(s):  
O. E. Seredyuk ◽  
N. M. Malisevich
Keyword(s):  
Natural Gas ◽  
Temperature Measurement ◽  
Flow Rate ◽  
Gas Flow ◽  
Flame Temperature ◽  
Operating Conditions ◽  
Gas Flow Rate ◽  
Combustion Heat ◽  
Gas Combustion ◽  
Functional Scheme

The article is devoted to the study of the influence of the qualitative and quantitative composition of gas environments on the flame temperature of the combusted gas at different values of gas flow rate and changes volume ratio gas-air in its combustion. The functional scheme of the developed labo­ratory stand (Fig. 1), which provides temperature measurement during combustion of natural gas or propane-butane mixture, is considered. The design of the developed burner is described and the expe­rimental researches are carried out when measuring the flame temperature of the combusted gas during the operation of the laboratory stand. The opera­ting conditions of different thermocouples in measuring the temperature of the flared gas are investigated (Fig. 2). The temperature instability in the lower and upper flames was experimentally determined (Fig. 3) and its difference from the reference data [12, 13]. The measurement of the flame temperature with a uncased thermocouple and two thermocouples of different types with protective housings is reali­zed. Methodical error of temperature measurement by different thermocouples was estimated (Fig. 5). An algorithm for the implementation of measurement control in determining the heat of combustion of natural gas according to the patented method is outlined [11]. Experimental studies of temperature changes of combusted gas mixtures at different gas flow rates and different ratios with air, which is additionally supplied for gas combustion, were carried out (Figs. 4, 7). The computer simulation (Figs. 6, 8) of the change in the flame temperature was performed on the basis of the experimental data, which allowed to obtain approximate equations of the functional dependence of the flame temperature on the gas flow rate and the ratio of the additional air and gas consumption. The possibility of realization of the device of express control of the heating value of natural gas by measuring the combustion temperature of the investigated gases, which is based on the expe­rimentally confirmed increase in the flame temperature of the investigated gases with increasing their calorific value, is substantiated (Fig. 9). The necessity of further investigation of the optimization design characteristics of the burner and the operating conditions of combustion of the gases under rapid cont­rol of their combustion heat was established (Fig. 9).

scholarly journals Particle deposition characteristics in entrained flow coal gasifier

2012 ◽  
Vol 16 (5) ◽  
pp. 1544-1548
Author(s):  
Sheng Liu ◽  
Ying-Li Hao
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Particle Deposition ◽  
Gas Flow ◽  
Water Flow Rate ◽  
Deposition Process ◽  
The Other ◽  
Central Channel ◽  
Gas Flow Rate ◽  
Coal Gasifier

Cold state experiment and numerical simulation are carried out to study particle deposition process. The deposit mass can be divided into two parts, one directly collides with the wall and the other is brought by the backflow. The deposit flux increases with the increase of gas flow rate or water flow rate or both, and decreases with the increase of the central channel gas flow rate.

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