kim pedersen - Academia.edu (original) (raw)

Papers by kim pedersen

Combustion and Flame, Feb 1, 2010

ABSTRACT

Energy & Fuels, Sep 25, 2011

Chemical Engineering Science, Sep 1, 2015

External and internal mass transfer limits the initial reaction between CaO/SO 2. CO 2 inhibits t... more External and internal mass transfer limits the initial reaction between CaO/SO 2. CO 2 inhibits the CaO/SO 2 reaction. Recirculation of CaO in the cement preheater does not influence SO 2 emission.

Chemcatchem, Apr 21, 2022

Supporting information for this article is given via a link at the end of the document.

ChemCatChem

The high fuel efficiency of natural gas makes it an attractive alternative to coal and oil during... more The high fuel efficiency of natural gas makes it an attractive alternative to coal and oil during the transition towards renewable energy resources. Natural gas engines are needed to ensure a stable power grid that can accommodate fluctuations in renewable energy production. Unfortunately, these engines emit as much as 3–4 % of the methane (CH4) in the natural gas under learn‐burn conditions. This methane slip has a high environmental cost since CH4 is a potent greenhouse gas. Complete catalytic oxidation of CH4 can potentially control the emission. Unfortunately, the best performing Pd/Al2O3 catalysts suffer from severe deactivation under operating conditions. After decades of little progress, zeolite‐supported catalysts have recently attracted increased attention. Here, we review the current status, challenges, and prospects for controlling methane emissions from large engines using zeolite‐based catalysts. The determining factors for catalytic activity and stability are the zeoli...

Chemical Engineering Science, 2015

External and internal mass transfer limits the initial reaction between CaO/SO 2. CO 2 inhibits t... more External and internal mass transfer limits the initial reaction between CaO/SO 2. CO 2 inhibits the CaO/SO 2 reaction. Recirculation of CaO in the cement preheater does not influence SO 2 emission.

Fuel Processing Technology, 2009

The wide implementation of low-NOx combustion technologies in pulverized coal combustion can lead... more The wide implementation of low-NOx combustion technologies in pulverized coal combustion can lead to higher levels of carbon in fly ash and increase the adsorptivity toward surfactants of the carbon. Consequently, the air entraining agent (AEA) requirements of the fly ash used for concrete production increases, which can complicate the stabilization of entrained air. In this study, a low-NOx tangential

Energy & Fuels, 2011

In this work, a model for the nitrogen chemistry in the oxy-fuel combustion of pulverized coal ha... more In this work, a model for the nitrogen chemistry in the oxy-fuel combustion of pulverized coal has been developed. The model is a chemical reaction engineering type of model with a detailed reaction mechanism for the gas-phase chemistry, together with a simplified description of the mixing of flows, heating and devolatilization of particles, and gasÀsolid reactions. The model is validated by comparison with entrained flow reactor results from the present work and from the literature on pulverized coal combustion in O 2 /CO 2 and air, covering the effects of fuel, mixing conditions, temperature, stoichiometry, and inlet NO level. In general, the model provides a satisfactory description of NO formation in air and oxy-fuel combustion of coal, but under some conditions, it underestimates the impact on NO of replacing N 2 with CO 2. According to the model, differences in the NO yield between the oxy-fuel combustion and the conventional combustion of pulverized coal can mostly be attributed to the recycling of NO (reburning effect) and to changes in the mixing patterns between fuel and oxygen. For pulverized-fuel combustion at high temperatures, we think that NO is mainly reduced by heterogeneous reactions involving both char and soot. Here, the tar yield of the volatiles is mainly converted to soot and H 2 , limiting the concentration of hydrocarbons and thereby the importance of gas-phase removal of NO. Our work emphasizes the need for accurate descriptions of mixing, volatile composition (fate of tar), and heterogeneous reactions. Furthermore, more work is desirable on the reduction of NO by CO on char at higher temperatures.

Energy & Fuels, 2009

The residual carbon in fly ash produced from pulverized coal combustion can adsorb the air-entrai... more The residual carbon in fly ash produced from pulverized coal combustion can adsorb the air-entraining admixtures (AEAs) added to enhance air entrainment in concrete. This behavior of the ash can be suppressed by exposing the fly ash to oxidizing species, which oxidizes the carbon surface and thus prevents the AEA to be adsorbed. In the present work, two fly ashes have been ozonated in a fixed bed reactor and the results showed that ozonation is a potential post-treatment method that can lower the AEA requirements of a fly ash up to 6 times. The kinetics of the carbon oxidation by ozone was found to be fast. A kinetic model has been formulated, describing the passivation of carbon, and it includes the stoichiometry of the ozone consumption (0.8 mol of O 3 /kg of C) and an ineffective ozone loss caused by catalytic decomposition. The simulated results correlated well with the experimental data.

Combustion and Flame, 2010

ABSTRACT

Emission Control Science and Technology, 2018

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

Combustion and Flame, Feb 1, 2010

ABSTRACT

Energy & Fuels, Sep 25, 2011

Chemical Engineering Science, Sep 1, 2015

External and internal mass transfer limits the initial reaction between CaO/SO 2. CO 2 inhibits t... more External and internal mass transfer limits the initial reaction between CaO/SO 2. CO 2 inhibits the CaO/SO 2 reaction. Recirculation of CaO in the cement preheater does not influence SO 2 emission.

Chemcatchem, Apr 21, 2022

Supporting information for this article is given via a link at the end of the document.

ChemCatChem

The high fuel efficiency of natural gas makes it an attractive alternative to coal and oil during... more The high fuel efficiency of natural gas makes it an attractive alternative to coal and oil during the transition towards renewable energy resources. Natural gas engines are needed to ensure a stable power grid that can accommodate fluctuations in renewable energy production. Unfortunately, these engines emit as much as 3–4 % of the methane (CH4) in the natural gas under learn‐burn conditions. This methane slip has a high environmental cost since CH4 is a potent greenhouse gas. Complete catalytic oxidation of CH4 can potentially control the emission. Unfortunately, the best performing Pd/Al2O3 catalysts suffer from severe deactivation under operating conditions. After decades of little progress, zeolite‐supported catalysts have recently attracted increased attention. Here, we review the current status, challenges, and prospects for controlling methane emissions from large engines using zeolite‐based catalysts. The determining factors for catalytic activity and stability are the zeoli...

Chemical Engineering Science, 2015

External and internal mass transfer limits the initial reaction between CaO/SO 2. CO 2 inhibits t... more External and internal mass transfer limits the initial reaction between CaO/SO 2. CO 2 inhibits the CaO/SO 2 reaction. Recirculation of CaO in the cement preheater does not influence SO 2 emission.

Fuel Processing Technology, 2009

The wide implementation of low-NOx combustion technologies in pulverized coal combustion can lead... more The wide implementation of low-NOx combustion technologies in pulverized coal combustion can lead to higher levels of carbon in fly ash and increase the adsorptivity toward surfactants of the carbon. Consequently, the air entraining agent (AEA) requirements of the fly ash used for concrete production increases, which can complicate the stabilization of entrained air. In this study, a low-NOx tangential

Energy & Fuels, 2011

In this work, a model for the nitrogen chemistry in the oxy-fuel combustion of pulverized coal ha... more In this work, a model for the nitrogen chemistry in the oxy-fuel combustion of pulverized coal has been developed. The model is a chemical reaction engineering type of model with a detailed reaction mechanism for the gas-phase chemistry, together with a simplified description of the mixing of flows, heating and devolatilization of particles, and gasÀsolid reactions. The model is validated by comparison with entrained flow reactor results from the present work and from the literature on pulverized coal combustion in O 2 /CO 2 and air, covering the effects of fuel, mixing conditions, temperature, stoichiometry, and inlet NO level. In general, the model provides a satisfactory description of NO formation in air and oxy-fuel combustion of coal, but under some conditions, it underestimates the impact on NO of replacing N 2 with CO 2. According to the model, differences in the NO yield between the oxy-fuel combustion and the conventional combustion of pulverized coal can mostly be attributed to the recycling of NO (reburning effect) and to changes in the mixing patterns between fuel and oxygen. For pulverized-fuel combustion at high temperatures, we think that NO is mainly reduced by heterogeneous reactions involving both char and soot. Here, the tar yield of the volatiles is mainly converted to soot and H 2 , limiting the concentration of hydrocarbons and thereby the importance of gas-phase removal of NO. Our work emphasizes the need for accurate descriptions of mixing, volatile composition (fate of tar), and heterogeneous reactions. Furthermore, more work is desirable on the reduction of NO by CO on char at higher temperatures.

Energy & Fuels, 2009

The residual carbon in fly ash produced from pulverized coal combustion can adsorb the air-entrai... more The residual carbon in fly ash produced from pulverized coal combustion can adsorb the air-entraining admixtures (AEAs) added to enhance air entrainment in concrete. This behavior of the ash can be suppressed by exposing the fly ash to oxidizing species, which oxidizes the carbon surface and thus prevents the AEA to be adsorbed. In the present work, two fly ashes have been ozonated in a fixed bed reactor and the results showed that ozonation is a potential post-treatment method that can lower the AEA requirements of a fly ash up to 6 times. The kinetics of the carbon oxidation by ozone was found to be fast. A kinetic model has been formulated, describing the passivation of carbon, and it includes the stoichiometry of the ozone consumption (0.8 mol of O 3 /kg of C) and an ineffective ozone loss caused by catalytic decomposition. The simulated results correlated well with the experimental data.

Combustion and Flame, 2010

ABSTRACT

Emission Control Science and Technology, 2018

 Users may download and print one copy of any publication from the public portal for the purpose... more  Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.