scholarly journals Numerical Analysis on Effect of Additional Gas Injection on Characteristics around Raceway in Melter Gasifier

2019 ◽  
Vol 38 (2019) ◽  
pp. 837-848
Author(s):  
Du Kaiping ◽  
Gao Xiangzhou ◽  
Sun Haibo
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Gas Injection ◽  
Coke Oven ◽  
Pure Oxygen ◽  
Small Scale ◽  
Gas Temperature ◽  
Fuel Gas ◽  
Hot Air ◽  
Flow Circulation

AbstractThe raceway plays an important role in the mass and heat transportation inside a melter gasifier. Considering that pure oxygen at room temperature instead of hot air is injected into the melter gasifier, a two-dimensional mathematical model at steady state is developed in the current work to describe the effect of the additional gas injection on the characteristics around the raceway in melter gasifier. The results show that a high-speed jet with a highest temperature above 3500 K could be found in front of tuyere. Furthermore, a small scale of gas flow circulation occurs in front of tuyere that results in a more serious thermal damage to tuyere. In order to decrease the gas temperature in the raceway to prevent the blowing-down caused by tuyere damage, the additional gas, including N2, natural gas (NG) and coke oven gas (COG) should be injected through the tuyere. Compared with N2, additional fuel gas injection gives full play to the high temperature reduction advantage of hydrogen. In addition, considering the insufficient hearth heat after injecting NG and the effective utilization of secondary resource, an appropriate amount of COG is recommended to be injected for optimizing blast system.

The Mechanics and Thermodynamics of Steady One-Dimensional Gas Flow

1947 ◽  
Vol 14 (4) ◽  
pp. A317-A336 ◽  
Author(s):  
Ascher H. Shapiro ◽  
W. R. Hawthorne
Keyword(s):  
Heat Transfer ◽  
Dimensional Analysis ◽  
High Speed ◽  
Gas Flow ◽  
Gas Injection ◽  
Wall Friction ◽  
Analytical Treatment ◽  
Area Change ◽  
One Dimensional ◽  
Recent Developments

Abstract Recent developments in the fields of propulsion, flow machinery, and high-speed flight have emphasized the need for an improved understanding of the characteristics of compressible flow. A one-dimensional analysis for flow without shocks is presented which takes into account the simultaneous effects of area change, wall friction, drag of internal bodies, external heat exchange, chemical reaction, change of phase, injection of gases, and changes in molecular weight and specific heat. The method of selecting independent and dependent variables, and the organization of the working equations, leads, it is believed, to a better understanding of the influence of the foregoing effects, and also simplifies greatly the analytical treatment of particular problems. Examples are given first of several simple types of flow, including (a) area change only; (b) heat transfer only; (c) wall friction only; and (d) gas injection only. In addition, examples of flow with combined effects are given, including (a) simultaneous friction and area change; (b) simultaneous friction and heat transfer; and (c) simultaneous liquid injection and evaporation. A one-dimensional analysis for flow through a discontinuity is presented, allowing for energy, shock, drag, and gas-injection effects, and for changes in gas properties. This analysis is applicable to such processes as: (a) the adiabatic normal shock; (b) combustion; (c) moisture condensation shocks; and (d) steady explosion waves.

scholarly journals Experimental and Numerical Study of a Thermal Expansion Gyroscope for Different Gases

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 360 ◽  
Author(s):  
Guillaume Kock ◽  
Philippe Combette ◽  
Marwan Tedjini ◽  
Markus Schneider ◽  
Caroline Gauthier-Blum ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Gas Flow ◽  
Numerical Study ◽  
Rotational Velocity ◽  
Measurement Range ◽  
Gas Temperature ◽  
Hot Air ◽  
Working Principle ◽  
Set Up ◽  
Different Gases

A new single-axis gas thermal gyroscope without proof mass is presented in this paper. The device was designed, manufactured and experimentally characterized. The obtained results were compared to numerical simulation. The working principle of the gyroscope is based on the deflection of a laminar gas flow caused by the Coriolis effect. A bidirectional hot air flow is generated by alternating activation of two suspended resistive micro-heaters. The heated gas is encapsulated in a semi-open cavity and the gas expands primarily inside the cavity. The thermal expansion gyroscope has a simple structure. Indeed, the device is composed of a micromachined cavity on which three bridges are suspended. The central bridge is electrically separated into two segments enabling to set up two heaters which may be supplied independently from each other. The two other bridges, placed symmetrically on each side of the central bridge, are equipped with temperature detectors which measure variations in gas temperature. The differential temperature depends on the rotational velocity applied to the system. Various parameters such as the heating duty cycle, the type of the gas and the power injected into the heaters have been studied to define the optimal working conditions required to obtain the highest level of sensitivity over a measurement range of around 1000°/s. The robustness of the device has also been tested and validated for a shock resistance of 10,000 g for a duration of 400 µs.

The Design, Selection, and Application of Oil-Free Screw Compressors for Fuel Gas Service

1995 ◽  
Vol 117 (1) ◽  
pp. 74-80 ◽  
Author(s):  
K. D. Lelgemann
Keyword(s):  
Gas Flow ◽  
Coal Gasification ◽  
Landfill Gas ◽  
Coke Oven ◽  
Lubricating Oil ◽  
Screw Compressor ◽  
Fuel Gas ◽  
Process Gas ◽  
Design Selection ◽  
Shaft Seals

Fuel gas compressors installed in cogeneration systems must be highly reliable and efficient machines. The screw compressor can usually be designed to meet most of the gas flow rates and pressure conditions generally required for such installations. To an ever-increasing degree, alternative sources are being found for the fuel gas supply, such as coke-oven gas, blast-furnace gas, flare gas, landfill gas, and synthesis gas from coal gasification or from pyrolysis. A feature of the oil-free screw compressor when such gases are being considered is the isolation of the gas compression space from the bearing and gear lubrication system by using positive shaft seals. This ensures that the process gas cannot be contaminated by the lubricating oil, and that there is no risk of loss of lubricant viscosity by gas solution in the oil. This feature enables the compressed gas to contain relatively high levels of particulate contamination without danger of “sludge” formation, and also permits the injection of water or liquid solvents into the compression space, to reduce the temperature rise due to the heat of compression, or to “wash” any particulate matter through the compressor.

Stress Relaxation Measurement as a High-Speed Method for Predicting the Long-Term Behavior of Vulcanized Rubber

1983 ◽  
Vol 56 (1) ◽  
pp. 31-50 ◽  
Author(s):  
R. Clamroth ◽  
L. Ruetz
Keyword(s):  
Stress Relaxation ◽  
High Speed ◽  
Elevated Temperatures ◽  
Pure Oxygen ◽  
Relaxation Measurement ◽  
Hot Air ◽  
Vulcanized Rubber ◽  
Relaxation Measurements ◽  
The Times ◽  
Speed Method

Abstract Intermittent stress relaxation is well suited for quantifying aging processes in rubber. For NR, the effects of different antioxidants can be measured by the rates at which the modulus falls. In synthetic rubbers (SBR, NBR, and CR), it can be measured through the modulus increases caused by oxygen crosslinking. Equal-value times, e.g., t0.75 for NR and t1.25 for SBR, NBR, and CR, are the times taken by the modulus to decrease or increase to a given percentage of its original level. They are better measures of aging than the modulus change after a given time. For NR, it has been shown that stress relaxation measurements at elevated temperatures and in pure oxygen correlate with the results of conventional aging methods. Thus the testing times can be drastically reduced—from up to 28 days to 1–8 hours. Discontinuous stress relaxation measurements are considerably more accurate and selective than conventional oxygen aging. For the repeatability of a single equal-value time measurement, we obtained a coefficient of variation (s/x) of 5–10% for stress relaxation measurement and about ±20% for oxygen aging. The degree of selectivity for oxygen aging and stress relaxation was found to be 3.6 and 18, respectively. The correlation between the results of stress relaxation measurements and those of the conventional oxygen and hot air aging tests was investigated for a large number of NR compounds and for some SBR, NBR, and CR compounds. The correlation is not very good, but it must be remembered that the equal-value times determined according to the two methods show relatively pronounced variability. With the conventional aging methods, the results also depend on what quantity is measured, e.g., the change in tensile strength or hardness, and on what equal-value time is chosen, e.g., the time taken by the property concerned to decrease to 90 or 75% of its original value. The conclusion of the investigations described above is that intermittent modulus measurement is an interesting high-speed method for the assessment of aging behavior. It will acquire a firm position in the arsenal of rubber testing methods, but will probably supplement, and not completely replace, the aging methods currently used.

Numerical simulation of combustor temperature performance of a high-temperature high-speed heat-airflow simulation system

2016 ◽  
Vol 13 (5) ◽  
pp. 422-431 ◽  
Author(s):  
Chaozhi Cai ◽  
Leyao Fan ◽  
Bingsheng Wu
Keyword(s):  
High Temperature ◽  
Temperature Distribution ◽  
High Speed ◽  
Simulation System ◽  
Outlet Temperature ◽  
Gas Temperature ◽  
Fuel Gas ◽  
Content Type ◽  
Gas Ratio ◽  
Airflow Simulation

Purpose This paper aims to understand the outlet temperature distribution of the combustor of a high-temperature, high-speed heat-airflow simulation system. Design/methodology/approach The paper uses numerical simulation to study the temperature distribution of the combustor of a high-temperature, high-speed heat-airflow simulation system. First, the geometrical model of the combustor and the combustion model of the fuel are established. Then, the combustion of fuel in the combustor is simulated by using FLUENT under various conditions. Finally, the results are obtained. Findings The paper found three conclusions: when the actual fuel–gas ratio is equal to the theoretical fuel–gas ratio, the temperature in the combustor of the high-temperature, high-speed heat-airflow simulation system (HTSAS) can reach its highest and the distribution is the most uniform. Although increases in the total temperature of the inlet air can increase the highest temperature in the combustor of the HTSAS, the average temperature of the combustor outlet will decrease. At the same time, it will lead to an uneven temperature distribution of the combustor outlet. When the spray angle of the kerosene droplet is at 30 degrees, the outlet temperature field of the combustor is more uniform. Originality/value The paper presents a method to analyze the combustion performance of fuel and the gas temperature distribution in the combustor. The results will lay the foundation for the gas temperature control of a combustor.

Numerical Simulation and Test Research of Pneumatic Drying on Biomass Fuel

2013 ◽  
Vol 274 ◽  
pp. 479-482
Author(s):  
Xin Hai Wang ◽  
Wei Lv ◽  
De Li Zhang ◽  
Xiao Nan Zhang ◽  
Zhong Xia Zhao
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Horizontal Tube ◽  
Initial Water Content ◽  
Single Factor ◽  
Drying Process ◽  
Test Bed ◽  
Initial Water ◽  
Hot Air ◽  
Pneumatic Drying

Based on the mechanism of mass and heat transfer of the particles and air in drying tube，the mathematics model of pneumatic drying process was established which referred to straw fuel in straight horizontal tube. The simulating results were summed up. Test bed of pneumatic drying was established，the test results were summed up by making single-factor test on the test bed. The results of simulating and single-factor test were coincided, and the pneumatic drying process was divided into two parts which were high-speed drying area and slow drying area. The effect factors were analyzed which were initial water content, hot air temperature, mass of hot air and materiel. The most important factor in gas flow drying on straw fuel was summed up which was the mass of hot air.

An Investigation of the Effects of Flue Gas Injection on Natural Draft Cooling Tower Performance

1997 ◽  
Vol 119 (2) ◽  
pp. 478-484 ◽  
Author(s):  
T. V. Eldredge ◽  
D. J. Benton ◽  
J. W. Hodgson
Keyword(s):  
Flue Gas ◽  
Gas Flow ◽  
Cooling Tower ◽  
Cold Water ◽  
Control Volume ◽  
Gas Injection ◽  
Airflow Rate ◽  
Gas Temperature ◽  
Natural Draft ◽  
Cold Water Temperature

This paper addresses an investigation of flue gas injection on natural draft cooling tower performance through numerical simulation. The control volume finite difference method was used for discretizing the governing equations in axisymmetric form on a boundary-fitted grid. The five independent variables addressed in this study are flue gas flow rate, flue gas temperature, radial injection location, injection orientation, and liquid entrainment in the flue gas. The flue gas temperature was found to have the most significant effect on tower performance (cold water temperature), because it strongly affects the buoyancy within the tower. The total air flow through a tower is driven by buoyancy forces, and the cooling performance is a strong function of the airflow rate.

scholarly journals Thermo-Elasto-Hydrodynamic Characteristics Analysis of Journal Microbearing Lubricated with Rarefied Gas

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 955
Author(s):  
Yao Wu ◽  
Lihua Yang ◽  
Tengfei Xu ◽  
Wei Wu
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Load Capacity ◽  
Hydrodynamic Characteristics ◽  
Small Scale ◽  
Damping Coefficients ◽  
Stiffness Coefficients ◽  
Characteristics Analysis ◽  
Lubrication Characteristics

Temperature rise and elastic deformation are unavoidable issues occurring in high-speed gas microbearings due to the dominant small-scale fluid dynamics in rarefied gas flow applications. In this paper, thermo-elasto-aerodynamic analysis requires simultaneously solving the modified Reynolds equation, modified energy equation, temperature–viscosity relationship and the elasticity equations for predicting the lubrication characteristics of microbearings. A thermo-elasto-aerodynamic lubrication is systematically investigated by using the partial derivative method, finite difference formulation and the finite element approach. The results indicate that, compared with rigid microbearing which has a constant viscosity gas lubricant, the temperature effect increases the load capacity, friction coefficient and stiffness coefficients, and it decreases the attitude angle and damping coefficients of the microbearing. The flexibility of the bearing pad also leads to the increase in load capacity and direct stiffness coefficients, while it remains to further decrease the direct damping coefficients on the basis of thermo-aerodynamic performance. The present study is conducive to accurately analyze the microscopic flow properties in a microbearing-rotor system.

Analysis of Exhausting Flue Gas Temperature Abnormal Accompanied with the Boiler Load Changing

2013 ◽  
Vol 805-806 ◽  
pp. 1836-1842
Author(s):  
Qing Feng Zhang ◽  
Zhen Xin Wu ◽  
Zhen Ning Zhao
Keyword(s):  
Heat Transfer ◽  
Power Plant ◽  
Flue Gas ◽  
Gas Flow ◽  
Thermal Power ◽  
Transfer Principle ◽  
Air Leakage ◽  
Gas Temperature ◽  
Boiler Load ◽  
Hot Air

Based on the heat-transfer principle of air pre-heater, the influence mode of the changes of the air flow, the flue gas flow, the air leakage in different locations, to the temperature of the hot air and the exhausting gas was researched. The problem of a pulverized coal fired boiler, No.2, of a Thermal Power Plant, which the deviation of exhausting flue gas temperature increased to an abnormal extend when the boiler load rise up quickly was analyzed, the fault position and fault reason were located exactly, and the fault was eradicated by equipment maintenance at last. The results of this study have a certain significance to solve similar problems.

The Design, Selection, and Application of Oil-Injected Screw Compressors for Fuel Gas Service

1995 ◽  
Vol 117 (1) ◽  
pp. 81-87
Author(s):  
S. Tsutsumi ◽  
J. Boone
Keyword(s):  
Gas Turbines ◽  
Gas Flow ◽  
High Reliability ◽  
Slide Valve ◽  
Screw Compressor ◽  
Gas Temperature ◽  
Fuel Gas ◽  
Discharge Gas ◽  
Design Selection ◽  
Environmentally Sound

Fuel gas compressors installed in cogeneration systems must be highly reliable and efficient machines, like the other main components, such as gas turbines, gas engines, etc. In the range of gas flow rate and pressure conditions generally required for such systems, the oil-injected screw compressor is often the most suitable compressor type for these requirements. Advantages of oil injected screw compressors are: improved compression efficiency; low discharge gas temperature; high reliability; simple mechanical construction; which all result from injection of lubricant into the compressor. Injected lubricant is discharged together with compressed gas on the high-pressure side but the oil is separated by a fine oil separation system down to a level that causes no problems for the downstream combustion equipment. The oil-injected screw compressor is equipped with an integral stepless capacity control by means of a slide valve, which makes part-load operation possible with reduced power consumption and improves overall system efficiency. As cogeneration systems, which are energy efficient and environmentally sound, are now increasing in number, so oil-injected screw compressors are expected to be used more widely.

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