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Mikko Hupa - One of the best experts on this subject based on the ideXlab platform.

  • effects of reduced Bed temperature in laboratory and full scale Fluidized Bed Boilers particle deposit and ash chemistry
    2013
    Co-Authors: Frida Jones, Fredrik Niklasson, Daniel Lindberg, Mikko Hupa
    Abstract:

    This study focuses on how the temperature of the Bed in a waste-fired Fluidized-Bed Boiler affects the chemical composition of ash and deposits. The aim was to reduce the concentration of corrosive elements in the convection pass, which can lead to both less frequent soot blowing intervals and extended superheater lifetimes. Complementary laboratory-scale tests were carried out in a single-pellet reactor to study online alkali and Zn emissions during temperature changes, using an ICP-MS instrument. The full-scale study was based on full-scale experiments at a plant consisting of two 20 MWth Fluidized-Bed Boilers firing a mixture of municipal solid waste and industrial waste. The Boilers are normally operated at Bed temperatures of about 870 °C. This normal operation was compared in this work to a test case in which the Bed temperature was reduced below 720 °C by altering the air staging and flue gas recycling. The experimental work included collecting samples of fuel, ash, and particles under the two diff...

  • fate of fuel nitrogen in the furnace of an industrial bubbling Fluidized Bed Boiler during combustion of biomass fuel mixtures
    2012
    Co-Authors: Emil Vainio, Mikko Hupa, Anders Brink, Hannu Vesala, Tuula Kajolinna
    Abstract:

    The fate of fuel nitrogen in the furnace of a full-scale bubbling Fluidized Bed Boiler was studied in an extensive measurement campaign. The study of the fate of the fuel nitrogen is based on measurements in the furnace of a 107 MWth bubbling Fluidized Bed Boiler for 3 days, each day with a different fuel blend. During the first day, the Boiler was fired with bark. During the second day, the Boiler was fired with a mixture of bark and sludge. During the third day, bark, sludge, and solid recovered fuel (SRF) were co-combusted. The furnace gas composition was measured from the fuel inlet to the furnace exit level, at seven in-furnace measurement ports in total. The main nitrogen species in the lower furnace, under the fuel inlet, were NH3 and NO, but also some HCN was found. Under reducing conditions in the lower furnace, nitrogen was mainly in the form of NH3, while for oxidizing conditions, the main nitrogen species measured were NO and NH3. The highest NH3 concentrations were observed above the fuel inl...

  • fate of alkali metals and phosphorus of rapeseed cake in circulating Fluidized Bed Boiler part 1 cocombustion with wood
    2010
    Co-Authors: Patrycja Piotrowska, Mikko Hupa, Kent Davidsson, Lars-erik Åmand, Maria Zevenhoven, Vesna Barisic, Edgardo Coda Zabetta
    Abstract:

    This paper is part I in it series of two describing the fate of alkali metals and phosphorus during cocombustion of rapeseed cake pellets in a 12 MW thermal CFB Boiler. In paper I the results of using the mixture of wood chips and wood pellets as a base fuel are descriBed. Up to 45% on energy basis of rapeseed cake was cocombusted during it 4 h test. Two approximately 12 h tests with energy fractions of rapeseed cake of 12 and 18% were performed with limestone as a varying parameter. Fuels were characterized by means of chemical fractionation and standard methods. Elemental mass balances were calculated for ingoing and Outgoing streams of the Boiler. In addition SEM/EDX analyses of ashes were performed. Gaseous (KCl + NaCl) its well its HCl and SO2 were Measured upstream of the convection pass, where deposit samples were also collected with deposit probe. The deposit samples were analyzed semiquantitatively by means of SEM/EDX. The elemental mass balances Show accumulation of alkali metals and phosphorus ill the Boiler. Analyses of Bed material particle cross sections show the presence of phosphorus Compounds within it K-silicates matrix between the agglomerated sand particles, indicating it direct attack of gaseous potassium compounds on the Bed surface followed by adhesion of ash particles rich in phosphorus. Build-up of deposit during the cocombustion tests mainly took place on the windward side of the probe; where in increase of K, Na, and P has been observed. Addition of limestone prevented formation of K-silicates and increased retention of phosphorus in the Bed, most probably due to formation of high-melting calcium phosphates. During the tests with limestone,,in increase of potassium chloride upstream of the convection pass and it decrease of phosphorus in the fly ash fraction could be noticed. Agglomeration and slagging/fouling when cofiring wood with rapeseed cake may be linked to its high content of organically bonded phosphorus-phytic acid salts-together with high contents of water-soluble alkali metals chlorides and sulfates in the fuel mixture.

  • the fouling behavior of rice husk ash in Fluidized Bed combustion 1 fuel characteristics
    2005
    Co-Authors: Bengt-johan Skrifvars, Jouni Kinni, Peter Siefen, Patrik Yrjas, Mikko Hupa
    Abstract:

    Rice husk can be considered as an “opportunity fuel” for energy production. However, although rice husk has long been identified as a source for energy production, only limited experience exists from rice husk firing in larger-scale combustors. Only a few units worldwide are reported to be using rice husk as their main fuel. One concern in rice husk firing is the behavior of the ash, i.e., its slagging and fouling tendency, as well as its abrasiveness. This paper presents the very characteristic properties of the rice husk ash, as measured by a variety of laboratory tests and analyses, and compares these characteristics with eucalyptus bark and rice straw, as well as with some other biomass fuels. The paper is the first in a series of two, where we report from a recently finished study on the slagging and fouling behavior of rice husk when fired alone or in combination with other fuels in a Fluidized-Bed Boiler. In the second part of the series, we will report the results of fireside fouling measurements ...

  • the fouling behavior of rice husk ash in Fluidized Bed combustion 2 pilot scale and full scale measurements
    2005
    Co-Authors: Bengt-johan Skrifvars, Jouni Kinni, Tor Laurén, Honghi Tran, Patrik Yrjas, Mikko Hupa
    Abstract:

    This paper is the second in a series of two on the slagging and fouling behavior of rice husk when fired alone or in combination with other fuels in a Fluidized-Bed Boiler. The first paper involved the fuel properties of rice husk, as investigated by a variety of laboratory methods. In this second paper, we report the results of fireside fouling measurements when burning rice husk alone and together with eucalyptus bark in various ratios. This study is based on short-term (3−10 h) deposit samples taken with air-cooled deposit probes in the superheater region of a large-scale (157 MWth) bubbling Fluidized-Bed (BFB) Boiler burning rice husk and eucalyptus bark. Using an entrained-flow type of pilot furnace, we further made more, systematic measurements of the influence of the fuel mixture ratio on the fouling tendency of the fly ash formed. Burning of rice husk alone did not result in any detectable fouling, neither in the pilot furnace nor on the deposit probes in the superheater area of the Fluidized-Bed ...

Hairui Yang - One of the best experts on this subject based on the ideXlab platform.

  • development of a supercritical and an ultra supercritical circulating Fluidized Bed Boiler
    2019
    Co-Authors: Junfu Lyu, Hairui Yang, Wen Ling, Li Nie, Guangxi Yue, Ying Chen, Shilong Wang
    Abstract:

    The supercritical circulating Fluidized Bed (CFB) Boiler, which combines the advantages of CFB combustion with low cost emission control and supercritical steam cycle with high efficiency of coal energy, is believed to be the future of CFB combustion technology. It is also of greatest importance for low rank coal utilization in China. Different from the supercritical pulverized coal Boiler that has been developed more than 50 years, the supercritical CFB Boiler is still a new one which requires further investigation.Without any precedentor engineering reference, Chinese researchers have conducted fundamental research, development, design of the supercritical CFB Boilers independently. The design theory and key technology for supercritical CFB Boiler were proposed. Key components and novel structures were invented. The first 600 MWe supercritical CFB Boiler and its auxiliaries were successfully developed and demonstrated in Baima Power Plant, Shenhua Group as well as the simulator, control technology, installation technology, commissioning technology, system integration and operation technology. Compared with the 460 MWe supercritical CFB in Poland, developed in the same period and the only other supercritical one of commercial running in the word beside Baima, the 600 MWe one in Baima has a better performance. Besides, supercritical CFB Boilers of 350 MWe have been developed and widely commercialized in China. In this paper, the updated progress of 660 MWe ultra-supercritical CFB Boilers under development is introduced.

  • Modeling study of combustion process of oil shale semicoke in a circulating Fluidized Bed Boiler
    2018
    Co-Authors: Yiqun Huang, Junfu Lyu, Man Zhang, Hairui Yang
    Abstract:

    In this paper, the combustion process of oil shale semicoke was investigated by modeling, where intraparticle mass transfer resistance was especially considered. The ash formation and attrition characteristics of oil shale semicoke were also investigated by a laboratory test procedure. The burnout time and residence time of different particle sizes were predicted, and the maximum particle size of which oil shale semicoke could be burned out in a 3 MW circulating Fluidized Bed Boiler was obtained. Keywords: Oil shale semicoke, Combustion, CFB, Ash formation, Attritio

  • effects of different factors on sulfur trioxide formations in a coal fired circulating Fluidized Bed Boiler
    2017
    Co-Authors: Baixiang Xiang, Man Zhang, Wenfeng Shen, Hairui Yang
    Abstract:

    Abstract Experimental and numerical studies were conducted to determine the effects of different factors on homogeneous and heterogeneous formations of sulfur trioxide (SO 3 ) in a coal-fired circulating Fluidized Bed (CFB) Boiler. In the experiments, homogeneous and heterogeneous formations of SO 3 under coal-fired CFB combustion conditions were measured using controlled condensation and S balance, respectively. Meanwhile, homogeneous SO 3 formation under coal-fired CFB combustion conditions was numerically calculated using an improved SO 2 /O 2 /H 2 O/CO 2 /CO/NO kinetic mechanism. Measurement results showed that the effect of fly ash on SO 3 concentration was slightly stronger than that of circulating ash. Both experimental and numerical results showed that SO 3 concentration was apparently affected by SO 2 , O 2 , and H 2 O concentrations and temperature but barely affected by CO 2 concentration.

  • nox emission from a circulating Fluidized Bed Boiler cofiring coal and corn stalk pellets
    2012
    Co-Authors: Hairui Yang, Hai Zhang, Xiaolong Qiu, Shi Yang, Qing Liu
    Abstract:

    The NOx emission from a circulating Fluidized Bed (CFB) Boiler with 50 MW rated thermal output (50 MWth) during the cofiring of anthracite coal and pelletized corn stalk biomass was investigated. Cofiring could improve combustion efficiency and, thus, the thermal efficiency of the Boiler. However, contrary to most results found in bubbling Fluidized Bed (BFB) combustors and the one found in a CFB Boiler burning rice husk, NOx concentration in flue gas and fuel nitrogen conversion ratio increased with the biomass mass fraction. Several causes for such a contradiction were discussed and the configuration in combination with feedstock location of biomass was regarded as the most important one. In a CFB Boiler, fuel is mostly burnt above the dense Bed, opposite to that in a BFB Boiler, and, thus, the average oxygen concentration above the dense Bed, where biomass was fed, was higher. High Bed temperature and high primary air ratio used for burning the anthracite coal increased NOx emission and enhanced the va...

Junfu Lyu - One of the best experts on this subject based on the ideXlab platform.

  • analysis of thermal deviations in l shape platen superheaters of a supercritical 600 mw circulating Fluidized Bed Boiler
    2020
    Co-Authors: Junfu Lyu
    Abstract:

    Abstract In circulating Fluidized Bed (CFB) Boilers, L-shape platen superheaters often suffer from poor working conditions with a high risk of tube wall overtemperature. Thermal deviations of an L-shape platen superheater were studied by using a supercritical 600 MW CFB Boiler as reference. Based on the prediction model of thermal deviations and a self-developed software, thermal deviations of the platen superheater were calculated and analyzed under three kinds of heat load distributions. The results show that the heat absorption deviations for steam are related to the heat load and heating area distribution, wherein the heat load is more effective than the heating area. The mass flow rate deviations for steam mainly depend on the header effect and the nonuniform tube length, while the mass flow rate deviations induced by thermal effects are negligible. The mass flow rates of each tube are nearly identical because the header effect offsets the effect of the nonuniform tube length. Therefore, the heat absorption deviations determine the final thermal deviations of the platen superheater. It is suggested to make complete use of the header effect on the mass flow rate distribution; thus, achieving good control of the thermal deviation of platen superheaters.

  • development of a supercritical and an ultra supercritical circulating Fluidized Bed Boiler
    2019
    Co-Authors: Junfu Lyu, Hairui Yang, Wen Ling, Li Nie, Guangxi Yue, Ying Chen, Shilong Wang
    Abstract:

    The supercritical circulating Fluidized Bed (CFB) Boiler, which combines the advantages of CFB combustion with low cost emission control and supercritical steam cycle with high efficiency of coal energy, is believed to be the future of CFB combustion technology. It is also of greatest importance for low rank coal utilization in China. Different from the supercritical pulverized coal Boiler that has been developed more than 50 years, the supercritical CFB Boiler is still a new one which requires further investigation.Without any precedentor engineering reference, Chinese researchers have conducted fundamental research, development, design of the supercritical CFB Boilers independently. The design theory and key technology for supercritical CFB Boiler were proposed. Key components and novel structures were invented. The first 600 MWe supercritical CFB Boiler and its auxiliaries were successfully developed and demonstrated in Baima Power Plant, Shenhua Group as well as the simulator, control technology, installation technology, commissioning technology, system integration and operation technology. Compared with the 460 MWe supercritical CFB in Poland, developed in the same period and the only other supercritical one of commercial running in the word beside Baima, the 600 MWe one in Baima has a better performance. Besides, supercritical CFB Boilers of 350 MWe have been developed and widely commercialized in China. In this paper, the updated progress of 660 MWe ultra-supercritical CFB Boilers under development is introduced.

  • Modeling study of combustion process of oil shale semicoke in a circulating Fluidized Bed Boiler
    2018
    Co-Authors: Yiqun Huang, Junfu Lyu, Man Zhang, Hairui Yang
    Abstract:

    In this paper, the combustion process of oil shale semicoke was investigated by modeling, where intraparticle mass transfer resistance was especially considered. The ash formation and attrition characteristics of oil shale semicoke were also investigated by a laboratory test procedure. The burnout time and residence time of different particle sizes were predicted, and the maximum particle size of which oil shale semicoke could be burned out in a 3 MW circulating Fluidized Bed Boiler was obtained. Keywords: Oil shale semicoke, Combustion, CFB, Ash formation, Attritio

Bo G Leckner - One of the best experts on this subject based on the ideXlab platform.

  • effect of cofiring coal and biofuel with sewage sludge on alkali problems in a circulating Fluidized Bed Boiler
    2007
    Co-Authors: Kent Davidsson, Lars-erik Åmand, Annalena Elled, Bo G Leckner
    Abstract:

    Cofiring experiments were performed in a 12 MW circulating Fluidized Bed Boiler. The fuel combinations were biofuel (wood+straw), coal+biofuel, coal+sewage sludge+biofuel, and sewage sludge+biofuel. Limestone or chlorine (PVC) was added in separate experiments. Effects of feed composition on Bed ash and fly ash were examined. The composition of flue gas was measured, including on-line measurement of alkali chlorides. Deposits were collected on a probe simulating a superheater tube. It was found that the fuel combination, as well as addition of limestone, has little effect on the alkali fraction in Bed ash, while chlorine decreases the alkali fraction in Bed ash. Sewage sludge practically eliminates alkali chlorides in flue gas and deposits. Addition of enough limestone to coal and sludge for elimination of the SO2 emission does not change the effect of chlorine. Chlorine addition increases the alkali chloride in flue gas, but no chlorine was found in the deposits with sewage sludge as a cofuel. Cofiring o...

  • effect of cofiring coal and biofuel with sewage sludge on alkali problems in a circulating Fluidized Bed Boiler
    2007
    Co-Authors: Kent Davidsson, Lars-erik Åmand, Annalena Elled, Bo G Leckner
    Abstract:

    Cofiring experiments were performed in a 12 MW circulating Fluidized Bed Boiler. The fuel combinations were biofuel (wood+straw), coal+biofuel, coal+sewage sludge+biofuel, and sewage sludge+biofuel. Limestone or chlorine (PVC) was added in separate experiments. Effects of feed composition on Bed ash and fly ash were examined. The composition of flue gas was measured, including on-line measurement of alkali chlorides. Deposits were collected on a probe simulating a superheater tube. It was found that the fuel combination, as well as addition of limestone, has little effect on the alkali fraction in Bed ash, while chlorine decreases the alkali fraction in Bed ash. Sewage sludge practically eliminates alkali chlorides in flue gas and deposits. Addition of enough limestone to coal and sludge for elimination of the SO{sub 2} emission does not change the effect of chlorine. Chlorine addition increases the alkali chloride in flue gas, but no chlorine was found in the deposits with sewage sludge as a cofuel. Cofiring of coal and biofuel lowers the alkali chloride concentration in the flue gas to about a third compared with that of pure biofuel. This is not affected by addition of lime or chlorine. It is concluded that aluminum compounds in coal and sludgemore » are more important than sulfur to reduce the level of KCl in flue gas and deposits. 24 refs., 8 figs., 7 tabs.« less

  • potassium chlorine and sulfur in ash particles deposits and corrosion during wood combustion in a circulating Fluidized Bed Boiler
    2007
    Co-Authors: Kent Davidsson, Lars-erik Åmand, Borka Kovacevik, Maria Svane, Magnus Hagstrom, Jan B C Pettersson, Jesper Pettersson, Henrik Asteman, Bo G Leckner, Janerik Svensson
    Abstract:

    The effect of the addition of chlorine and/or sulfur to the fuel on fly ash composition, deposit formation, and superheater corrosion has been studied during biomass combustion in a circulating Fluidized-Bed Boiler. The chlorine (HCl (aq)) and sulfur (SO2 (g)) were added in proportions of relevance for the potassium chemistry. The composition of the bottom and the fly ashes was analyzed. Gas and particle measurements were performed downstream of the cyclone before the convection pass and the flue gas composition was recorded in the stack with a series of standard instruments and an FTIR analyzer. At the position downstream of the cyclone, a deposit probe was situated, simulating a superheater tube. Deposits on the probe and initial corrosion were examined. It is concluded that addition of sulfur and chlorine increases the formation of submicron particles leading to deposition of potassium sulfate and chloride. The results compare well with earlier work based on laboratory-scale experiments concerning effects of chlorine and sulfur on potassium chemistry.

  • distribution of potassium chlorine and sulfur between solid and vapor phases during combustion of wood chips and coal
    2003
    Co-Authors: Heije Miettinen Westberg, Madelaine Bystrom, Bo G Leckner
    Abstract:

    Results are presented on the distribution of some (inorganic) elements between the solid and vapor phases in a circulating Fluidized Bed Boiler during combustion of wood chips and coal. Samples were taken from all input and output solid material streams as well as from the gas phase at different locations in the Boiler. Deposits on a specially designed deposition probe were also measured. An explanation is presented concerning the release and fate of potassium, chlorine, and sulfur during biomass combustion. The explanation is supported by the results from an additional test where hydrogen chloride was added to the combustion chamber. One of the most important factors affecting the reactivity of potassium toward chlorine in the combustion chamber appears to be the moisture content of the fuel.

  • combustion of wood chips in circulating Fluidized Bed Boilers no and co emissions as functions of temperature and air staging
    1999
    Co-Authors: Anders Lyngfelt, Bo G Leckner
    Abstract:

    Abstract Reduction of NO emissions during combustion of wood-chips in a 12 MW circulating Fluidized Bed Boiler was investigated by lowering the air-ratio in the combustor through secondary air addition in the cyclone outlet. This mode of operation was studied at three loads and also in combination with secondary air addition in the cyclone inlet and/or at 2.2 m height. A significant reduction in NO emissions was obtained without high CO emissions. Important for the success of NO abating measures was that the CO emissions should not increase to high levels. Therefore the conditions for CO burnout were studied. The temperature in the duct downstream of the cyclone outlet, the “exit chamber”, was found to be important, as the burnout of CO was not completed in the cyclone, not even under normal operating conditions. The explanation seems to be incomplete mixing of the gases entering the cyclone. There was a clear correlation between the temperature in the exit chamber and the CO emissions, and various measures taken to increase the temperature in the exit chamber were effective in reducing CO emissions.

Marcin Klajny - One of the best experts on this subject based on the ideXlab platform.

  • numerical simulations of the industrial circulating Fluidized Bed Boiler under air and oxy fuel combustion
    2015
    Co-Authors: Wojciech Adamczyk, Pawel Kozolub, Adam Klimanek, Ryszard A Bialecki, Marek Andrzejczyk, Marcin Klajny
    Abstract:

    Abstract Measured and numerical results of air-fuel combustion process within large scale industrial circulating Fluidized Bed (CFB) Boiler is presented in this paper. For numerical simulations the industrial compact CFB Boiler was selected. Numerical simulations were carried out using three-dimensional model where the dense particulate transport phenomenon was simultaneously modelled with combustion process. The fluidization process was modelled using the hybrid Euler-Lagrange approach. The impact of the geometrical model simplification on predicted mass distribution and temperature profiles over CFB Boiler combustion chamber two kinds of geometrical models were used, namely the complete model which consist of combustion chamber, solid separators, external solid super-heaters and simplified Boiler geometry which was reduced to the combustion chamber. The evaluated temperature and pressure profiles during numerical simulations were compared against measured data collected during Boiler air-fuel operation. Collected data was also used for validating numerical model of the oxy-fuel combustion model. Stability of the model and its sensitivity on changes of several input parameters were studied. The comparison of the pressure and temperature profiles for all considered cases gave comparable trends in contrary to measured data. Moreover, some additional test was carried out the check the influence of radiative heat transfer on predicted temperature profile within the CFB Boiler.

  • numerical simulations of the industrial circulating Fluidized Bed Boiler under air and oxy fuel combustion
    2015
    Co-Authors: Wojciech Adamczyk, Pawel Kozolub, Adam Klimanek, Ryszard A Bialecki, Marek Andrzejczyk, Marcin Klajny
    Abstract:

    Abstract Measured and numerical results of air-fuel combustion process within large scale industrial circulating Fluidized Bed (CFB) Boiler is presented in this paper. For numerical simulations the industrial compact CFB Boiler was selected. Numerical simulations were carried out using three-dimensional model where the dense particulate transport phenomenon was simultaneously modelled with combustion process. The fluidization process was modelled using the hybrid Euler-Lagrange approach. The impact of the geometrical model simplification on predicted mass distribution and temperature profiles over CFB Boiler combustion chamber two kinds of geometrical models were used, namely the complete model which consist of combustion chamber, solid separators, external solid super-heaters and simplified Boiler geometry which was reduced to the combustion chamber. The evaluated temperature and pressure profiles during numerical simulations were compared against measured data collected during Boiler air-fuel operation. Collected data was also used for validating numerical model of the oxy-fuel combustion model. Stability of the model and its sensitivity on changes of several input parameters were studied. The comparison of the pressure and temperature profiles for all considered cases gave comparable trends in contrary to measured data. Moreover, some additional test was carried out the check the influence of radiative heat transfer on predicted temperature profile within the CFB Boiler.