The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform

David Nilsson - One of the best experts on this subject based on the ideXlab platform.

  • A comprehensive kinetic model for staged combustion of nitrogen doped fuels
    Clean Air, 2002
    Co-Authors: Fabian Mauss, David Nilsson
    Abstract:

    A PSR-PFR series Reactor model has been used with different detailed C/H/N/O reaction mechanisms for the calculation of NO formation during rich-lean staged combustion of ethylene (C 2 H 4 ) with monomethylamine (CH 3 NH 2 ) addition as a model mixture for nitrogen-doped fuels. The PSR model and a PSR-PFR combination have been validated by comparison with measurements on a pilot-scale Reactor system. Good agreement with NO measurements in the Primary Reactor and the flue gas can be obtained with some of the mechanisms reported in literature. For slightly fuel-rich conditions the differences in the results obtained with different mechanisms are reflected in the dissimilar reaction paths leading to NO formation. The N atom flow rates via the major formation and destruction channels in the PSR yield a net minimum production rate at φ = 1.3, which corresponds well with the measured and predicted φ for minimum NO emission. It is also demonstrated that the flue gas NO emission is largely determined already in the PSR, making the sensitivity to PFR conditions quite low.

Akwasi A. Boateng - One of the best experts on this subject based on the ideXlab platform.

  • Rotary Kiln Minerals Process Applications
    Rotary Kilns, 2020
    Co-Authors: Akwasi A. Boateng
    Abstract:

    The processes that employ the rotary kiln as the Primary Reactor are many and they encompass all industries including food, dedicated dryers, and mineral processing. Herein we focus on minerals and materials processing and provide some of the key industrial processes that use a rotary kiln as the Primary workhorse. We start with the cement and lime processes and then move on to describe some of the carbothermic reduction processes that employ the rotary kiln as the Primary device where we examine two processes, iron ore reduction (the SL/RN (acronym for steel-making companies Stelco, Lurgi, and Republic National) process) and ilmenite ore reduction (the Becher process). We then examine the lightweight aggregate process and finally finish the chapter with a case study on biomass carbonization or pyrolysis/torrefaction at low temperatures.

  • 10 – Rotary Kiln Minerals Process Applications
    Rotary Kilns, 2020
    Co-Authors: Akwasi A. Boateng
    Abstract:

    Publisher Summary From the fuel requirement point of view, rotary kilns are the most flexible of all lime kilns. They are successfully fired with natural gas, fuel oil, and pulverized fuels of all types including coal, coke, and sawdust. There are many processes that employ the rotary kiln as the Primary Reactor, encompassing all industries including food, dedicated dryers, minerals processing, etc. This chapter focuses on minerals and materials processing and provides some of the key industrial processes that use a rotary kiln as the Primary workhorse. Rotary kiln technology evolved from the struggles of early engineers and inventors to produce cement and lime in an efficient, safe, and economic way. The cement and lime processes and some of the carbothermic reduction processes that employ the rotary kiln as the Primary device are described. The processes of iron ore reduction (the SLRN process) and illmenite ore reduction (the Becher process) and the lightweight aggregate process are examined. Rotary cement kilns can be classified into wet-process kilns, semi-dry kilns, dry kilns, preheater kilns, and precalciner kilns. The pertinent process chemistry and the heat requirements that drive them so as to be consistent with the transport phenomena theme are shown.

  • Rotary Kiln Minerals Process Applications
    Rotary Kilns, 2016
    Co-Authors: Akwasi A. Boateng
    Abstract:

    From the fuel requirement point of view, rotary kilns are the most flexible of all lime kilns. They are successfully fired with natural gas, fuel oil, and pulverized fuels of all types including coal, coke, and sawdust. There are many processes that employ the rotary kiln as the Primary Reactor, encompassing all industries including food, dedicated dryers, minerals processing, etc. This chapter focuses on minerals and materials processing and provides some of the key industrial processes that use a rotary kiln as the Primary workhorse. Rotary kiln technology evolved from the struggles of early engineers and inventors to produce cement and lime in an efficient, safe, and economic way. The cement and lime processes and some of the carbothermic reduction processes that employ the rotary kiln as the Primary device are described. The processes of iron ore reduction (the SLRN process) and illmenite ore reduction (the Becher process) and the lightweight aggregate process are examined. Rotary cement kilns can be classified into wet-process kilns, semi-dry kilns, dry kilns, preheater kilns, and precalciner kilns. The pertinent process chemistry and the heat requirements that drive them so as to be consistent with the transport phenomena theme are shown.

Fabian Mauss - One of the best experts on this subject based on the ideXlab platform.

  • A comprehensive kinetic model for staged combustion of nitrogen doped fuels
    Clean Air, 2002
    Co-Authors: Fabian Mauss, David Nilsson
    Abstract:

    A PSR-PFR series Reactor model has been used with different detailed C/H/N/O reaction mechanisms for the calculation of NO formation during rich-lean staged combustion of ethylene (C 2 H 4 ) with monomethylamine (CH 3 NH 2 ) addition as a model mixture for nitrogen-doped fuels. The PSR model and a PSR-PFR combination have been validated by comparison with measurements on a pilot-scale Reactor system. Good agreement with NO measurements in the Primary Reactor and the flue gas can be obtained with some of the mechanisms reported in literature. For slightly fuel-rich conditions the differences in the results obtained with different mechanisms are reflected in the dissimilar reaction paths leading to NO formation. The N atom flow rates via the major formation and destruction channels in the PSR yield a net minimum production rate at φ = 1.3, which corresponds well with the measured and predicted φ for minimum NO emission. It is also demonstrated that the flue gas NO emission is largely determined already in the PSR, making the sensitivity to PFR conditions quite low.

Jae Do Kwon - One of the best experts on this subject based on the ideXlab platform.

  • Fracture Toughness with Thermal Aging in CF8M/SA508 Welds
    Key Engineering Materials, 2006
    Co-Authors: Jae Do Kwon, Young Hwan Choi
    Abstract:

    In a Primary Reactor cooling system, a dissimilar weld zone exists between cast stainless steel (CF8M) in a pipe and low-alloy steel (SA508 cl.3) in a nozzle. Thermal aging is observed in CF8M as the RCS is exposed for a long period of time to a Reactor operating temperature between 290 and 330, while no effect is observed in SA508 cl.3. The aged specimens are prepared by an artificially accelerated aging technique maintained for 300, 1800 and 3600 hrs at 430, respectively. The specimens for elastic-plastic fracture toughness tests are prepared two types, which notch is created in the center of deposited zone and the heat affected zone of CF8M. From the experiments, the plastic-elastic fracture toughness values (JIC) with the increase of aging time decrease as the notch is created in the HAZ of CF8M, while that is different slightly as the notch is created in the deposited zone. Also, JIC values in the deposited zones are smaller than the HAZ of CF8M at all aged specimens.

  • Evaluation of the Fracture Characteristics with Thermal Aging on Dissimilar Welds in Reactor Coolant System
    Key Engineering Materials, 2005
    Co-Authors: Jae Do Kwon, Young Hwan Choi
    Abstract:

    A dissimilar weld zone exists between the pipe and nozzle in a Primary Reactor cooling system (RCS). Thermal aging is observed in cast stainless steel, CF8M used in a pipe as the RCS is exposed for a long period of time to a Reactor operating temperature between 290 and 330°C. No effect is observed in low-alloy steel. SA508 cl.3 is used in a nozzle. The artificially accelerated aging specimens are prepared to maintain for a temperature of 430°C for 300, 1800, and 3600hrs, respectively. Then, various mechanical tests such as hardness, tension, impact test, are performed in virgin and aged specimens in order to determine the existence of dissimilar weld zones. The specimens for elastic-plastic fracture toughness tests are prepared for one type, where a notch is created in the heat affected zone of CF8M. From the experiments, it was found that J-integral values decrease as age increases.

  • the study on effects of thermal aging of dissimilar weld zone in a Primary Reactor cooling system
    Key Engineering Materials, 2004
    Co-Authors: Jae Do Kwon, Youn Choi
    Abstract:

    In a Primary Reactor cooling system(RCS), a dissimilar weld zone exists between austenitic-ferritic duplex cast stainless steel(CF8M) in a pipe and low-alloy steel(SA508 cl.3) in a nozzle. Thermal aging is observed in CF8M as the RCS is exposed for a long period of time to a Reactor operating temperature between 290 and 330°C, while no effect is observed in SA508 cl.3. An investigation of the effect of thermal aging on the various mechanical properties of the dissimilar weld zone is required. The purpose of the present investigation is to find the effect of thermal aging on the dissimilar weld zone. The specimens are prepared by an artificially accelerated aging technique maintained for 100, 300, 900, 1800 and 3600 hrs at 430°C, respectively. The various mechanical tests for the dissimilar weld zone are performed for virgin and aged specimens.

  • Effects of thermal aging on the low cycle fatigue behavior of austenitic-ferritic duplex cast stainless steel
    Nuclear Engineering and Design, 2001
    Co-Authors: Jae Do Kwon, Joong-cheul Park, Youn-won Park
    Abstract:

    Abstract Thermal aging is observed in a Primary Reactor cooling system (RCS) made of cast stainless steel. The observation occurs when the RCS is exposed for a long period of time to a Reactor operating temperature between 290 and 330°C. An investigation of the effect of thermal aging on the low cycle fatigue characteristics of CF8M is required. The purpose of the present investigation is to find the effect of thermal aging of CF8M on a low cycle fatigue life. The specimen of CF8M is prepared by an artificially accelerated aging technique maintained for 300 and 1800 h at 430°C, respectively. The low cycle fatigue tests for the virgin and two aged specimens are performed at room temperature for the strain amplitudes ( e ta ) of 0.3, 0.5, 0.8, 1.0, 1.2 and 1.5%. In the experiment, it is found that the fatigue life is rapidly reduces with an increase of aging time. The experimental fatigue life estimation formula, between the virgin and two aged specimens are obtained.

Young Hwan Choi - One of the best experts on this subject based on the ideXlab platform.

  • Fracture Toughness with Thermal Aging in CF8M/SA508 Welds
    Key Engineering Materials, 2006
    Co-Authors: Jae Do Kwon, Young Hwan Choi
    Abstract:

    In a Primary Reactor cooling system, a dissimilar weld zone exists between cast stainless steel (CF8M) in a pipe and low-alloy steel (SA508 cl.3) in a nozzle. Thermal aging is observed in CF8M as the RCS is exposed for a long period of time to a Reactor operating temperature between 290 and 330, while no effect is observed in SA508 cl.3. The aged specimens are prepared by an artificially accelerated aging technique maintained for 300, 1800 and 3600 hrs at 430, respectively. The specimens for elastic-plastic fracture toughness tests are prepared two types, which notch is created in the center of deposited zone and the heat affected zone of CF8M. From the experiments, the plastic-elastic fracture toughness values (JIC) with the increase of aging time decrease as the notch is created in the HAZ of CF8M, while that is different slightly as the notch is created in the deposited zone. Also, JIC values in the deposited zones are smaller than the HAZ of CF8M at all aged specimens.

  • Evaluation of the Fracture Characteristics with Thermal Aging on Dissimilar Welds in Reactor Coolant System
    Key Engineering Materials, 2005
    Co-Authors: Jae Do Kwon, Young Hwan Choi
    Abstract:

    A dissimilar weld zone exists between the pipe and nozzle in a Primary Reactor cooling system (RCS). Thermal aging is observed in cast stainless steel, CF8M used in a pipe as the RCS is exposed for a long period of time to a Reactor operating temperature between 290 and 330°C. No effect is observed in low-alloy steel. SA508 cl.3 is used in a nozzle. The artificially accelerated aging specimens are prepared to maintain for a temperature of 430°C for 300, 1800, and 3600hrs, respectively. Then, various mechanical tests such as hardness, tension, impact test, are performed in virgin and aged specimens in order to determine the existence of dissimilar weld zones. The specimens for elastic-plastic fracture toughness tests are prepared for one type, where a notch is created in the heat affected zone of CF8M. From the experiments, it was found that J-integral values decrease as age increases.