scholarly journals Investigation of Low-Temperature Lean Combustion Characteristics in Power Plants with External Heating of Components

2021 ◽  
Vol 2(50) ◽  
Author(s):  
Nikolay Bachev ◽  
◽  
Alena Shilova ◽  
Oleg Matyunin ◽  
Oksana Betinskaya ◽  
...  
Keyword(s):  
Low Temperature ◽  
Combustion Chamber ◽  
Flow Rate ◽  
Turbulent Combustion ◽  
Power Plants ◽  
Lean Combustion ◽  
Relative Flow Rate ◽  
External Heating ◽  
Low Emission ◽  
Relative Flow

An integral part of any open-type gas turbine plant is a low-emission combustion chamber, which is usually two-zone and cooled. One of the ways to reduce emission of harmful substanc-es is organizing low-emission low-temperature lean combustion with external heating of compo-nents. This paper investigates the effect of external heating of air and fuel gas on expansion of the lower combustion limit and stable flame position in a single-zone uncooled combustion chamber of a microgas turbine power plant. Stable position of the flame front in combustion chambers of this type mainly depends on the ratio between the average flow rate of the combus-tible-air mixture and the rate of turbulent combustion. This ratio depends on thermal, gas-dynamic, thermochemical and geometric factors. The purpose of this work is to substantiate the possibility of using the relative flow rate as a generalized characteristic. This goal was achieved in processing a large amount of published experimental data and numerical modeling of low-temperature combustion of lean mixtures. The most significant research result is determination of the range of relative flow rate (gk = 0.3…3.5·10-4 kg⁄s∙N), at which it is possible to ensure sta-ble flame position in a single-zone combustion chamber. Significance of the obtained results lies in the fact that using the relative flow rate makes it possible to quickly determine and analyze the geometric and gas-dynamic parameters and characteristics of turbulent combustion in com-bustion chambers of micro-gas turbine power plants.

scholarly journals COMPUTATIONAL AND EXPERIMENTAL STUDIES OF THE AREA OF SUSTAINABLE COMBUSTION OF NATURAL GAS WITH AIR

2021 ◽  
pp. 47-55
Author(s):  
Alyona Shilova ◽  
◽  
Nikolay Bachev ◽  
Roman Bulbovich ◽  
◽  
...  
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Flow Rate ◽  
Turbulent Combustion ◽  
Average Flow Rate ◽  
Lean Combustion ◽  
Relative Flow Rate ◽  
Excess Air ◽  
Low Emission ◽  
Limiting Values

One of the rational ways of creating low-emission combustion chambers is the organization of low-temperature lean combustion with external heating of the components before they are fed into the combustion chamber. When organizing lowtemperature lean combustion with large excess air ratios, problems may arise with ensuring a stable position of the flame front. Combustion stability to a large extent depends on the ratio of the average flow rate and the rate of turbulent combustion. The rate of turbulent combustion depends on the composition, pressure and temperature of the components supply and the degree of turbulence in the combustion chamber. The average flow rate depends on the excess air ratio (oxidizer and fuel consumption) and the geometric dimensions of the chamber. Earlier it was shown that when developing a low-emission combustion chamber with low-temperature lean combustion, it is advantageous to use the relative flow rate as a generalized characteristic of the intra-chamber process, which takes into account the consumption, geometric and thermodynamic parameters in the combustion chamber. This work is devoted to the analysis of stable combustion of a fuel composition natural gas + air based on the experimental data available in the public domain by the authors from the University of Michigan (USA). With the help of the methods developed by the authors, the experimental data on the limiting feed rates of the components into the atmospheric burner were processed. The limiting flow rates of air and natural gas, the limiting values of the excess air ratio, the longitudinal values of the speed of the fuel-air mixture and the limiting values of the relative flow rate are obtained and analyzed. Areas of stable combustion by the listed parameters at different degrees of air swirl are graphically presented.

scholarly journals Study on SO3 Cooperative Removal Effect of Ultra-low Emission Technology in Coal-fired Power Plants

2018 ◽  
Vol 53 ◽  
pp. 04005 ◽  
Author(s):  
Ding Yang ◽  
Yi Luo ◽  
XingLian Ye ◽  
WeiXiang Chen ◽  
Jun Guo ◽  
...  
Keyword(s):  
Low Temperature ◽  
Flue Gas ◽  
Power Plants ◽  
Electrostatic Precipitator ◽  
Removal Rate ◽  
Flue Gas Desulfurization ◽  
Paper Briefly ◽  
Low Emission ◽  
Electrostatic Precipitators

SO3 is one of the main precursors of atmospheric PM2.5, and its emission has attracted more and more attention in the industry. This paper briefly analyzes the harm of SO3 and the method of controlled condensation to test SO3. The effect of cooperative removal of SO3 by ultra-low emission technology in some coal-fired power plants has been tested by using the method of controlled condensation. The results show that the cooperative removal of SO3 by ultra-low emission technology in coal-fired power plants is effective. The removal rate of SO3 by low-low temperature electrostatic precipitators and electrostatic-fabric integrated precipitators can be exceeded 80%, while the removal rate of SO3 by wet flue gas desulfurization equipment displays lower than the above two facilities, and the wet electrostatic precipitator shows a better removal effect on SO3. With the use of ultra-low emission technology in coal-fired power plants, the SO3 emission concentration of the tail chimney reaches less than 1 mg / Nm3.

scholarly journals INFLUENCE OF HEATING OF A GAS-AIR MIXTURE ON THE CHARACTERISTICS OF COMBUSTION OF FUEL GASES

2021 ◽  
pp. 83-90
Author(s):  
Alyona Shilova ◽  
◽  
Nikolay Bachev ◽  
Roman Bulbovich ◽  
◽  
...  
Keyword(s):  
Low Temperature ◽  
Flame Front ◽  
Power Plants ◽  
Combustion Products ◽  
Concentration Limit ◽  
Low Temperature Combustion ◽  
K Value ◽  
Stable Position ◽  
Excess Air ◽  
External Heating

For a stable position of the flame front in the combustion chambers of gas turbine power plants, the fresh gas-air mixture must be heated to the ignition temperature during the entire operation process. With air excess coefficients in the interval between the upper and lower concentration limits, reverse currents from the zone of developed combustion successfully cope with this task. When organizing low-temperature combustion near the lean limit, the contribution of reverse currents to heating the fresh gas-air mixture turns out to be insufficient and additional external heating of the components in special heaters with exhaust gases from the turbine is required. The temperature characteristics of the fresh gas-air mixture at the inlet to the chamber and in the zone of return currents, as well as combustion products in the developed flame zone, were obtained from the solution of the energy balance equations. The modes of low-temperature lean combustion with excess air coefficients exceeding the lower concentration limit α = 2 are considered. The calculations were carried out for two values of the ejection coefficient in the zone of reverse currents K = 0.14 and K = 0.30. A K value of 0.14 was obtained using empirical relationships. The value K = 0.30 was obtained from the condition that during stoichiometric combustion, the gas-air mixture is heated completely by reverse currents. It is shown that with an increase in the excess air ratio to ensure a stable position of the flame front, the role of external heating of components increases.

scholarly journals Increase fish protective efficiency constructions of meliorative water intake

2020 ◽  
pp. 69-73
Author(s):  
Svetlana Mikhailovna Dragunova ◽  
Yevgeniy Vladimirovich, Кuznetsov ◽  
Anna Yevgenievna Khadzhidi
Keyword(s):  
Physical Model ◽  
Water Intake ◽  
Flow Rate ◽  
Juvenile Fish ◽  
Protective Efficiency ◽  
Irrigation Systems ◽  
Relative Flow Rate ◽  
Reclamation System ◽  
Relative Flow ◽  
Fish Protection

The article solves the problem of increasing the level of protection of juvenile fish to a standard indicator by the modernization of individual elements of fish protection of ameliorative water intake of irrigation systems. The design of an integrated fish-protecting structure with a logging boom adapted to hydrology and the rhythm of migration of juvenile fish from irrigation sources has been proposed. The results of studies on a physical model, taking into account the costs of the reclamation system, show an increase in the efficiency of the combined fish protection structure with a harbor for reclamation water intakes in the range of 78,5–84,0 %, depending on the relative flow rate on the shelf of the sanctuary.

The effect of repeated cold exposure of the hand on the reactivity of digital vessels

1969 ◽  
Vol 47 (3) ◽  
pp. 261-265 ◽  
Author(s):  
Peter Gaskell ◽  
Kathleen L. Long
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Cold Exposure ◽  
Opening Pressure ◽  
Relative Flow Rate ◽  
Opposite Hand ◽  
Critical Opening ◽  
Before And After ◽  
Relative Change ◽  
Relative Flow

One hand of each of 10 subjects was immersed in stirred water at 4 °C for 1 h per day, 5 days per week, for 3 weeks, to produce local acclimatization to cold. The opposite hand was immersed at the same time in water at 32 °C. The reactivity of digital vessels in a finger of each hand was measured as the increase in the critical opening pressure of the vessels in response to an intravenous infusion of noradrenaline at 2 and 5 μg/min. The reactivity of digital vessels in the test hand was compared with that in the control hand both before and after the repeated cold exposure of the test hand to see whether the cold exposure altered the reactivity of vessels in the test hand relative to that in the control hand. No evidence of such a relative change was obtained. Resting blood flow at 21 and 32 °C in the test hand was compared with that in the control hand both before and after the repeated cold exposure. No change in the relative flow rate in the two hands was observed as a result of the cold exposure. Roentgen studies of the hands did not reveal any effect of the repeated cold exposure on the mineralization of the bones of the hands.

scholarly journals Biological treatment of drippers clogged by the use of treated domestic wastewater

2016 ◽  
Vol 20 (7) ◽  
pp. 595-599
Author(s):  
Danniely O. Costa ◽  
Rafael O. Batista ◽  
Hudson S. M. Vale ◽  
Amanda B. de Sousa ◽  
Solange A. G. Dombroski ◽  
...  
Keyword(s):  
Flow Rate ◽  
Biological Treatment ◽  
Statistical Difference ◽  
Domestic Wastewater ◽  
Rate Reduction ◽  
Relative Flow Rate ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
Different Doses ◽  
Relative Flow

ABSTRACT This study aimed to recover the flow rate of clogged drippers with different doses and permanence times of the product MaxBio. The experiment was conducted in a completely randomized design in split-split-plot scheme, where the plots corresponded to product doses (80, 160, 240 and 320 mg L-1), subplots to the applied treatments (T1 - without biological treatment, T2 - 1st application of the product, and T3 - 2nd application of the product) and in sub-subplots the types of emitters (Plastro Hydrodrip Super, Netafim Tiran and Netafim PCJ-CNJ), with three replicates. The four irrigation units operated with treated domestic wastewater for 400 h in order to clog the emitters. After applying the product MaxBio, the flow rate of the drippers and the relative flow rate reduction were determined to express the unclogging levels. There was significant effect of T2 and T3 on the recovery of the flow rate of the drippers, while for the reduction of relative flow rate, the doses of the product did not show statistical difference regarding the types of drippers.

scholarly journals EFFECT OF OXIDANT RELATIVE FLOW RATE ON OBTAINING RAW MATERIAL FOR PULVERIZED COAL PRODUCTION FROM HIGH-SULFURIC LOW GRADE COAL

2017 ◽  
Vol 11 (2) ◽  
pp. 236-241 ◽  
Author(s):  
Mariіa Shved ◽  
◽  
Serhiy Pyshyev ◽  
Yuriy Prysiazhnyi ◽  
◽  
...  
Keyword(s):  
Flow Rate ◽  
Pulverized Coal ◽  
Raw Material ◽  
Low Grade ◽  
Coal Production ◽  
Relative Flow Rate ◽  
Relative Flow

Investigation of Hydrodynamic Focusing in a Microfluidic Coulter Counter Device

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Muheng Zhang ◽  
Yongsheng Lian ◽  
Cindy Harnett ◽  
Ellen Brehob
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Coulter Counter ◽  
Hydrodynamic Focusing ◽  
Relative Flow Rate ◽  
Advection Diffusion Equation ◽  
Sample Stream ◽  
Voltage Signal ◽  
The Impact ◽  
Relative Flow

The Coulter technique enables rapid analysis of particles or cells suspended in a fluid stream. In this technique, the cells are suspended in an electrically conductive solution, which is hydrodynamically focused by nonconducting sheath flows. The cells produce a characteristic voltage signal when they interrupt an electrical path. The population and size of the cells can be obtained through analyzing the voltage signal. In a microfluidic Coulter counter device, the hydrodynamic focusing technique is used to position the conducting sample stream and the cells and also to separate close cells to generate distinct signals for each cell and avoid signal jam. The performance of hydrodynamic focusing depends on the relative flow ratio between the sample stream and sheath stream. We use a numerical approach to study the hydrodynamic focusing in a microfluidic Coulter counter device. In this approach, the flow field is described by solving the incompressible Navier-Stokes equations. The sample stream concentration is modeled by an advection-diffusion equation. The motion of the cells is governed by the Newton-Euler equations of motion. Particle motion through the flow field is handled using an overlapping grid technique. A numerical model for studying a microfluidic Coulter counter has been validated. Using the model, the impact of relative flow rate on the performance of hydrodynamic focusing was studied. Our numerical results show that the position of the sample stream can be controlled by adjusting the relative flow rate. Our simulations also show that particles can be focused into the stream and initially close particles can be separated by the hydrodynamic focusing. From our study, we conclude that hydrodynamic focusing provides an effective way to control the position of the sample stream and cells and it also can be used to separate cells to avoid signal jam.

COMPARATIVE ANALYSIS OF TWO MODELS OF TURBULENT COMBUSTION OF AN IMPERFECTLY PREPARED LEAN MIXTURE OF METHANE AND AIR USING REYNOLDS-AVERAGED NAVIER-STOKES AND SCALE ADAPTIVE SIMULATION METHODS

2020 ◽  
Author(s):  
M. V. Drobysh ◽  
◽  
A. N. Dubovitsky ◽  
A. B. Lebedev ◽  
K. Ya. Yakubovsky ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Combustion Chamber ◽  
Turbulent Combustion ◽  
Navier Stokes ◽  
Simulation Methods ◽  
Lean Mixture ◽  
Adaptive Simulation ◽  
Low Emission ◽  
Harmful Substances ◽  
Reynolds Averaged Navier Stokes

The formation of harmful substances (NOx and CO) during turbulent combustion of a lean imperfectly prepared mixture of methane and air in a low-emission combustion chamber (LECC) is studied numerically.

scholarly journals The Improvement of the Mathematical Model of the Work Process of Borehole Ejection Systems

2020 ◽  
pp. 36-44
Author(s):  
Ye. І. Kryzhanivskyi ◽  
D. О. Panevnyk
Keyword(s):  
Mathematical Models ◽  
Flow Rate ◽  
Hydraulic System ◽  
Pressure Ratio ◽  
Energy Performance ◽  
Maximum Efficiency ◽  
Relative Pressure ◽  
Jet Pump ◽  
Relative Flow Rate ◽  
Relative Flow

The article presents the sequence of deriving the equations which characterize the hydraulic system of jet pumps that carry out suction and injection-suction bottom flushing while drilling the production wells. The nature of flow distribution in the borehole ejection systems of the suction and injection-suction types is analyzed. The analysis is carried out taking into consideration the peculiarities of the calculation of branched hydraulic systems. While studying the movement of the flows in the bottom circulation circuits, the authors take into account the equation of the balance of the flow-rate at nodal points and hydraulic losses in parallel parts of the system. The developed mathematical models are based on the study of the changes in hydrodynamic pressures which occur in characteristic sections of a jet pump. The pressure ratio of mixed, injected and operating flows is presented as non-dimensional relative pressure of the ejection system. The dependence of non-dimensional relative pressure on the relative flow rate determines the characteristic of the hydraulic system of a jet pump. The relative flow rate or injection ratio of a jet pump is defined as the ratio of flow rate to injected and work flow. While analyzing the developed mathematical models, the authors specify the relation between the design and operating parameters of a jet pump. These parameters ensure its operation with maximum efficiency. Based on the study of the influence of the correlation between the diameters of the jet pump nozzles and the flushing system of the bit, the authors specify parameters which are optimal in terms of energy performance. The article provides the example of graphical determination of the operating point of a pumping unit. This determination is based on a simultaneous solution of the equations of the characteristics of the jet pump and the hydraulic system in which it operates. The improved techniques allow to predict the mode parameters of ejection systems and to determine the size of flowing part of the jet pump. They provide maximum energy performance of its workflow.

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