scholarly journals NOx Emissions and Nitrogen Fate at High Temperatures in Staged Combustion

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3557
Author(s):  
Song Wu ◽  
Defu Che ◽  
Zhiguo Wang ◽  
Xiaohui Su
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Combustion Zone ◽  
Combustion Temperature ◽  
Stoichiometric Ratio ◽  
Nox Emissions ◽  
Mechanism Analysis ◽  
Staged Combustion ◽  
Atom Concentration ◽  
Reducing Atmosphere

Staged combustion is an effective technology to control NOx emissions for coal-fired boilers. In this paper, the characteristics of NOx emissions under a high temperature and strong reducing atmosphere conditions in staged air and O2/CO2 combustion were investigated by CHEMKIN. A methane flame doped with ammonia and hydrogen cyanide in a tandem-type tube furnace was simulated to detect the effects of combustion temperature and stoichiometric ratio on NOx emissions. Mechanism analysis was performed to identify the elementary steps for NOx formation and reduction at high temperatures. The results indicate that in both air and O2/CO2 staged combustion, the conversion ratios of fuel-N to NOx at the main combustion zone exit increase as the stoichiometric ratio rises, and they are slightly affected by the combustion temperature. The conversion ratios at the burnout zone exit decrease with the increasing stoichiometric ratio at low temperatures, and they are much higher than those at the main combustion zone exit. A lot of nitrogen compounds remain in the exhaust of the main combustion zone and are oxidized to NOx after the injection of a secondary gas. Staged combustion can lower NOx emissions remarkably, especially under a high temperature (≥1600 °C) and strong reducing atmosphere (SR ≤ 0.8) conditions. Increasing the combustion temperature under strong reducing atmosphere conditions can raise the H atom concentration and change the radical pool composition and size, which facilitate the reduction of NO to N2. Ultimately, the increased OH/H ratio in staged O2/CO2 combustion offsets part of the reducibility, resulting in the final NOx emissions being higher than those in air combustion under the same conditions.

High Temperature n- and p-type Doped Microcrystalline Silicon Layers Grown by VHF PECVD Layer-by-Layer Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
A. Gordijn ◽  
J.K. Rath ◽  
R.E.I. Schropp
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
High Temperatures ◽  
Continuous Wave ◽  
Hydrogen Plasma ◽  
Silicon Layer ◽  
Dark Conductivity ◽  
High Deposition Rate ◽  
Layer By Layer ◽  
Microcrystalline Silicon

AbstractDue to the high temperatures used for high deposition rate microcrystalline (μc-Si:H) and polycrystalline silicon, there is a need for compact and temperature-stable doped layers. In this study we report on films grown by the layer-by-layer method (LbL) using VHF PECVD. Growth of an amorphous silicon layer is alternated by a hydrogen plasma treatment. In LbL, the surface reactions are separated time-wise from the nucleation in the bulk. We observed that it is possible to incorporate dopant atoms in the layer, without disturbing the nucleation. Even at high substrate temperatures (up to 400°C) doped layers can be made microcrystalline. At these temperatures, in the continuous wave case, crystallinity is hindered, which is generally attributed to the out-diffusion of hydrogen from the surface and the presence of impurities (dopants).We observe that the parameter window for the treatment time for p-layers is smaller compared to n-layers. Moreover we observe that for high temperatures, the nucleation of p-layers is more adversely affected than for n-layers. Thin, doped layers have been structurally, optically and electrically characterized. The best n-layer made at 400°C, with a thickness of only 31 nm, had an activation energy of 0.056 eV and a dark conductivity of 2.7 S/cm, while the best p-layer made at 350°C, with a thickness of 29 nm, had an activation energy of 0.11 V and a dark conductivity of 0.1 S/cm. The suitability of these high temperature n-layers has been demonstrated in an n-i-p microcrystalline silicon solar cell with an unoptimized μc-Si:H i-layer deposited at 250°C and without buffer. The Voc of the cell is 0.48 V and the fill factor is 70 %.

NICROFER 5520 Co

Alloy Digest ◽  
1995 ◽  
Vol 44 (3) ◽  
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Temperatures ◽  
Heat Treating ◽  
High Temperature Corrosion ◽  
Creep Properties ◽  
Nickel Chromium ◽  
Temperature Performance

Abstract NICROFER 5520 Co is a nickel-chromium-cobalt-molybdenum alloy with excellent strength and creep properties up to high temperatures. Due to its balanced chemical composition the alloy shows outstanding resistance to high temperature corrosion in the form of oxidation and carburization. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Ni-480. Producer or source: VDM Technologies Corporation.

CARLSON ALLOY C601

Alloy Digest ◽  
1994 ◽  
Vol 43 (7) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Stress Corrosion ◽  
Tensile Properties ◽  
High Temperatures ◽  
Stress Corrosion Cracking ◽  
Heat Treating ◽  
Resistance To Stress ◽  
Extended Exposure ◽  
Sulfur Containing

Abstract Carlson Alloy C601 is characterized by high tensile, yield and creep-rupture strengths for high temperature service. The alloy is not embrittled by extended exposure to high temperatures and has excellent resistance to stress-corrosion cracking, to carburizing, nitriding and sulfur containing environments. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on forming, heat treating, machining, and joining. Filing Code: Ni-458. Producer or source: G.O. Carlson Inc.

INCOTHERM TD

Alloy Digest ◽  
2005 ◽  
Vol 54 (11) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Oxidation Resistance ◽  
High Temperatures ◽  
Rare Earths ◽  
Temperature Performance

Abstract Incotherm TD is a thermocouple-sheathing alloy with elements of silicon and rare earths to enhance oxidation resistance at high temperatures. This datasheet provides information on composition, physical properties, and tensile properties as well as deformation. It also includes information on high temperature performance and corrosion resistance as well as forming. Filing Code: Ni-628. Producer or source: Special Metals Corporation.

HASTELLOY ALLOY X

Alloy Digest ◽  
1954 ◽  
Vol 3 (12) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Oxidation Resistance ◽  
High Temperatures ◽  
Heat Treating ◽  
Operating Conditions ◽  
Molybdenum Alloy ◽  
High Temperature Strength ◽  
Nickel Chromium

Abstract HASTELLOY Alloy X is a nickel-chromium-iron-molybdenum alloy recommended for high-temperature applications. It has outstanding oxidation resistance at high temperatures under most operating conditions, and good high-temperature strength. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on forming, heat treating, and machining. Filing Code: Ni-14. Producer or source: Haynes Stellite Company.

KUBOTA ALLOY HT

Alloy Digest ◽  
2011 ◽  
Vol 60 (11) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Nickel Alloy ◽  
Oxidation Resistance ◽  
High Temperatures ◽  
Temperature Performance ◽  
Iron Chromium

Abstract Kubota Alloy HT is an iron-chromium-nickel alloy that has both strength and oxidation resistance at high temperatures. This datasheet provides information on composition, physical properties, and tensile properties as well as creep. It also includes information on high temperature performance as well as casting and joining. Filing Code: SS-1108. Producer or source: Kubota Metal Corporation, Fahramet Division.

KENTANIUM K138A

Alloy Digest ◽  
1964 ◽  
Vol 13 (7) ◽  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
High Temperature ◽  
Titanium Carbide ◽  
Physical Properties ◽  
Engineering Design ◽  
High Temperatures

Abstract Kentanium K138-A is a high temperature titanium carbide that greatly widens the scope of the engineering design where conditions of intermittent or continuous high temperatures in oxidizing atmospheres are combined with abrasion, and compressive or tensile loads. This datasheet provides information on composition, physical properties, hardness, elasticity, and compressive strength as well as fracture toughness, creep, and fatigue. It also includes information on machining and joining. Filing Code: Ti-40. Producer or source: Kennametal Inc..

RA 309

Alloy Digest ◽  
1963 ◽  
Vol 12 (4) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Temperatures ◽  
Heat Treating ◽  
Corrosion Resistant Steel ◽  
Resistant Steel ◽  
Corrosion Resistant ◽  
Temperature Performance

Abstract RA 309 is a chromium-nickel heat and corrosion resistant steel recommended for high temperatures applications. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-142. Producer or source: Rolled Alloys Inc..

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