The main objective with this work was to investigate techno-economically the opportunity for integrated gasification-based biomass-to-methanol production in an existing chemical pulp and paper mill. Three different system configurations using the pressurized entrained flow biomass gasification (PEBG) technology were studied, one stand-alone plant, one where the bark boiler in the mill was replaced by a PEBG unit and one with a co-integration of a black liquor gasifier operated in parallel with a PEBG unit. The cases were analysed in terms of overall energy efficiency (calculated as electricity-equivalents) and process economics. The economics was assessed under the current as well as possible future energy market conditions. An economic policy support was found to be necessary to make the methanol production competitive under all market scenarios. In a future energy market, integrating a PEBG unit to replace the bark boiler was the most beneficial case from an economic point of view. In this case the methanol production cost was reduced in the range of 11-18 Euro per MWh compared to the stand-alone case. The overall plant efficiency increased approximately 7%-units compared to the original operation of the mill and the non-integrated stand-alone case. In the case with co-integration of the two parallel gasifiers, an equal increase of the system efficiency was achieved, but the economic benefit was not as apparent. Under similar conditions as the current market and when methanol was sold to replace fossil gasoline, co-integration of the two parallel gasifiers was the best alternative based on received IRR.

Increased concerns about particulate matter (PM) and polycyclic aromatic hydrocarbons (PAH) emissions from residential biomass combustion and their potential health effects, motivates detailed emission measurements under controlled conditions. Traditional sampling in raw flue gases can suffer from drawbacks mainly related to transient flows and the condensable nature of organic compounds. Whole flow dilution with constant volume sampling (CVS) is an alternative method but different sampling conditions may, however, influence the emission characteristics. The objective was to design a CVS system for emission measurements in residential biomass fired appliances and determine the influence of dilution sampling conditions on the characteristics and distributions of PM and PAH. Softwood pellets were combusted in a pellet stove with variations in; dilution ratio (3-7x), sampling temperature (45-75°C), dilution tunnel residence time (2-4 s) and fuel load (2.3 and 4.8 kW) according to a statistical experimental design. The sampling conditions did not influence either the emission concentrations of PM, CO and NO or the particle size distribution. Variations in residence time had no significant effect on any studied emission parameter. However, increased concentrations of organic gaseous carbon (OGC) and PAH were observed with increased dilution ratio. The distribution between particulate and semivolatile phase was influenced for 12 of the 37 analyzed PAH compounds, mainly by increased fractions of semivolatile material at higher sampling temperature. No influence of sampling temperature was observed for the concentrations of PAHtot or the dominating PAH compounds, i.e. phenanthrene, fluoranthene and pyrene. The results together with practical considerations also suggest sampling at 50±5°C and 3-4 times dilution as robust and applicable conditions in the presently designed setup. © 2005 Elsevier Ltd. All rights reserved.

Stove performance, characteristics, and quantities of gaseous and particulate emissions were determined for two different pellet stoves, varying fuel load, pellet diameter, and chimney draft. This approach aimed at covering variations in emissions from stoves in use today. The extensive measurement campaign included CO, NOx, organic gaseous carbon, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PMtot) as well as particle mass and number concentrations, size distributions, and inorganic composition. At high load, most emissions were similar. For stove B, operating at high residual oxygen and solely with primary air, the emissions of PMtot and particle numbers were higher while the particles were smaller. Lowering the fuel load, the emissions of CO and hydrocarbons increased dramatically for stove A, which operated continuously also at lower fuel loads. On the other hand for stove B, which had intermittent operation at lower fuel loads, the emissions of hydrocarbons increased only slightly lowering the fuel load, while CO emissions increased sharply, due to high emissions at the end of the combustion cycle. Beside methane, dominating VOCs were ethene, acetylene, and benzene and the emissions of VOC varied in the range 1.1-42 mg/MJfuel. PAH emissions (2-340 μg/MJfuel) were generally dominated by phenanthrene, fluoranthene and pyrene. The PM tot values (15-45 mg/MJfuel) were in all cases dominated by fine particles with mass median diameters in the range 100-200 nm, peak mobility diameters of 50-85 nm, and number concentrations in the range 4 × 1013 to 3 × 1014 particles/MJfuel. During high load conditions, the particulate matter was totally dominated by inorganic particles at 15-25 mg/MJfuel consisting of potassium, sodium, sulfur, and chlorine, in the form of K2SO4, K 3Na(SO4)2, and KCl. The study shows that differences in operation and modulation principles for the tested pellet stoves, relevant for appliances in use today, will affect the performance and emissions significantly, although with lower scattering in the present study compared to compiled literature data. © 2011 American Chemical Society.

Agglomeration of bed material may cause severe operating problems during fluidized bed combustion. The attack or coating layers that are formed on the bed particles during combustion play an important role in the agglomeration process. To reduce bed agglomeration tendencies, alternative bed materials may be used. In this paper, bed agglomeration characteristics during the combustion of biomass fuels using a relatively new bed material (iron blast-furnace slag) as well as ordinary quartz sand were determined. Controlled agglomeration tests lasting 40 h, using five representative biomass fuels (bark, olive residue, peat, straw, and reed canary grass) were conducted in a bench-scale fluidized bed. The bed materials and agglomerates were analyzed using SEM/EDS and X-ray diffraction. Chemical equilibrium calculations were performed to interpret the experimental findings. The results showed that blast-furnace slag had a lower tendency to agglomerate than quartz sand for most of the fuels. The quartz particles showed an inner attack layer more often than did the blast-furnace slag. The blast-furnace slag had a lower tendency to react with elements from the fuel. The outer coating layer had similar characteristics and thickness for both bed materials when the same fuel was combusted. However, the inner attack layer thickness was larger for quartz particles. SEM/EDS analyses of the agglomerates showed that the inner Ca-K-silicate-rich attack layer was responsible for the agglomeration of quartz sand. The composition of blast-furnace slag agglomerate was similar to the outer coating layer. Chemical equilibrium calculations showed that the original composition of the blast-furnace slag was close to the equilibrium composition, and hence there was no major driving force for reactions between that bed material and K and Ca from the fuel. The homogeneous silica-rich attack layer (with a low melting temperature) was not formed to the same extent for blast-furnace slag, thus explaining the lower bed agglomeration tendency. © 2004 American Chemical Society.

Abstract In this work, the radiative heat transfer conditions in a 400 kW<inf>fuel</inf> test furnace were studied. The test furnace is a scaled pilot of a rotary kiln furnace used in iron ore pellet production. In particular, the study focuses on the choice of fuel and the subsequent effect on temperature and radiative conditions in the flame. Several co-firing flames of coal and biomass were investigated and also other fuels such as heavy fuel oil and natural gas. The test furnace was used in the experiments, and radiative intensity was measured with a narrow angle radiometer. Detailed radiation modelling was performed using spectral models for gas and particle properties. The results show that all co-firing flames give a shorter radiating flame length. Based on the radiation modelling, it was also shown that the particle radiation dominates the heat transfer from the flames. Due to the high pre-heating temperature of the combustion air (1100°C), the flame temperatures were generally very high. The flame temperature in the natural gas flame was likely around 2000°C while the coal flame temperatures were estimated to 1500-1600°C. The two coals tested, having almost identical fuel specifications, resulted in a substantial difference in the radiation intensity emitted by the flame. This emphasizes the need of direct radiation measurements to evaluate fuel changes in industrial processes that are highly dependent on the heat transfer conditions.

Black liquor gasification is a new process for recovery of energy and chemicals in black liquor from the Kraft pulping process. The process can be combined with catalytic conversion of syngas into motor fuels. The potential for motor fuel production from black liquor in Sweden is to replace about 25% of the current consumption ofgasoline and diesel. For Finland the figure is even higher while for Canada it is about 14% and for the USA about 2%. © 2009 American Institute of Chemical Engineers Environ Prog, 28: 316-323, 2009.

Pressurized entrained flow high temperature black liquor gasification can be used as a complement or a substitute to the Tomlinson boiler used in the chemical recovery process at kraft pulp mills. The technology has been proven on the development scale, but there are still no full scale plants. This work is intended to aid in the development by providing computational tools that can be used in scale up of the existing technology. In this work, an existing computational fluid dynamics (CFD) model describing the gasification reactor is refined. First, one-dimensional (1D) plug flow reactor calculations with a comprehensive reaction mechanism are performed to judge the validity of the global homogeneous reaction mechanism used in the CFD simulations in the temperature range considered. On the basis of the results from the comparison, an extinction temperature modification of the steam-methane reforming reaction was introduced in the CFD model. An extinction temperature of 1400 K was determined to give the best overall agreement between the two models. Next, the results from simulations of the flow in a 3 MW pilot gasifier with the updated CFD model are compared to experimental results in which pressure, oxygen to black liquor equivalence ratio, and residence time have been varied. The results show that the updated CFD model can predict the main gas components (H 2, CO, CO2) within an absolute error of 2.5 mol %. CH 4 can be predicted within an absolute error of 1 mol %, and most of the trends when process conditions are varied are captured by the model. © 2011 American Chemical Society.

In this work two types of lignocellulosic biomass particles, European spruce and American hardwood (particle sizes from 100 μm to 500 μm) were pyrolysed with a continuous wave 2 W Nd:YAG laser. Simultaneously a high-speed camera was used to capture the behavior of the biomass particle as it was heated for about 0.1 s. Cover glasses were used as a sample holder which allowed for light microscope studies after the heating. Since the cover glasses are not initially heated by the laser, vapors from the biomass particle are quenched on the glass within about 1 particle diameter from the initial particle. Image processing was used to track the contour of the biomass particle and the enclosed area of the contour was calculated for each frame.

The main observations are: There is a significant difference between how much surface energy is needed to pyrolyses the spruce (about 75% more) compared to the hardwood. The oil-like substance which appeared on the glass during the experiment is solid at room temperature and shows different levels of transparency. A fraction of this substance is water soluble. A brownish coat is seen on the unreacted biomass. The biomass showed insignificant swelling as it was heated. The biomass particle appears to melt and boil at the front that is formed between the laser beam and the biomass particle. The part of the particle that is not subjected to the laser beam seems to be unaffected.

Stem wood powders were fired in a mullite-lined pilot-scale oxygen-blown pressurized entrained-flow gasifier. During repeated campaigns involving increases in fuel load and process temperature, slag formations that eventuated in the blockage of the gasifier outlet were observed. These slags were retrieved for visual and chemical characterization. It was found that the slags had very high contents of Al and, in particular, high Al/Si ratios that suggest likely dissolution of the mullite-based refractory of the gasifier lining due to interactions with the fuel ash. Possible causes for the slag formation and behavior are proposed, and practical implications for the design of future stem wood entrained-flow gasifiers are also discussed.

In this work, predictions from a reacting Computational Fluid Dynamics (CFD) model of a gasification reactor are compared to experimentally obtained data from an industrial pressurized black liquor gasification plant. The data consists of gas samples taken from the hot part of the gasification reactor using a water cooled sampling probe. During the considered experimental campaign, the oxygen-to-black liquor equivalence ratio (λ was varied in three increments, which resulted in a change in reactor temperature and gas composition. The presented numerical study consists of CFD and thermodynamic equilibrium calculations in the considered λ-range using boundary conditions obtained from the experimental campaign. Specifically, the influence of methane concentration on the gas composition is evaluated using both CFD and thermodynamic equilibrium. The results show that the main gas components (H 2, CO, CO2) can be predicted within a relative error of 5% using CFD if the modeled release of H2S and CH4 are specified a priori. In addition, the calculations also show that the methane concentration has large influence on the reactor outlet temperature and final carbon conversion.

The main objective was to explore the potential for gasifying Scots pine stump-root biomass (SRB). Washed thin roots, coarse roots, stump heartwood and stump sapwood were characterized (solid wood, milling and powder characteristics) before and during industrial processing. Non-slagging gasification of the SRB fuels and a reference stem wood was successful, and the gasification parameters (synthesis gas and bottom ash characteristics) were similar. However, the heartwood fuel had high levels of extractives (≈19%) compared to the other fuels (2-8%) and thereby ≈16% higher energy contents but caused disturbances during milling, storage, feeding and gasification. SRB fuels could be sorted automatically according to their extractives and moisture contents using near-infrared spectroscopy, and their amounts and quality in forests can be predicted using routinely collected stand data, biomass functions and drill core analyses. Thus, SRB gasification has great potential and the proposed characterizations exploit it. © 2011 Elsevier Ltd.

A future shortage of biomass fuel can be foreseen. The production of rapeseed oil for a number of purposesis increasing, among others, for biodiesel production. A yproduct from the oil extraction process is rapeseed meal (RM), presently used as animal feed. Further increases in supply will make fuel use an option. Several energy companies have shown interest but have been cautious because of the scarcity of data on fuel properties, which led to the present study. Combustion-relevant properties of RM from several producers have been determined. The volatile fraction (74 ± .06%wt ds) is comparable to wood; the moisture content (6.2-11.8%wt) is low; and the ash content (7.41 ± 0.286%wt ds) is high compared to most other biomass fuels. The lower heating value is 18.2 ± 0.3 MJ/kg (dry basis). In comparison to other biomass fuels, the chlorine content is low (0.02-0.05%wt ds) and the sulfur content is high (0.67-0.74%wt ds). RM has high contents of nitrogen (5.0-6.4%wt ds), phosphorus (1.12-1.23%wt ds), and potassium (1.2-1.4%wt ds). Fuel-specific combustion properties of typical RM were determined through combustion tests, with an emphasis on gas emissions, ash formation, and potential ash-related operational problems. Softwood bark was chosen as a suitable and representative co-combustion (woody) fuel. RM was added to the bark at two levels: 10 and 30%wt ds. These mixtures were pelletized, and so was RM without bark (for durability mixed with cutter shavings, contributing 1%wt of the ash). Each of these fuels was combusted in a 5 kWfluidized bed and an underfed pellet burner (to simulate grate combustion). Pure RM was combusted in a powder burner. Emissions of NO and SO2 were high for all combustion tests, requiring applications with flue gas cleaning, economically viable only at large scale. Emissions of HCl were relatively low. Temperatures for initial bed agglomeration in the fluidized-bed tests were high for RM compared to many other agricultural fuels, thereby indicating that RM could be an attractive fuel from a bed agglomeration point of view. The results of grate combustion suggest that slagging is not likely to be severe for RM, pure or mixed with other fuels. Fine-mode particles from fluidized-bed combustion and grate combustion mainly contained sulfates of potassium, suggesting that the risk of problems caused by deposit formation should be moderate. The chlorine concentration of the particles was reduced when RM was added to bark, potentially lowering the risk of high-temperature corrosion. Particle emissions from powder combustion of RM were 17 times higher than for wood powder, and the fine-mode fraction contained mainly K-phosphates known to cause deposits, suggesting that powder combustion of RM should be used with caution. A possible use of RM is as a sulfur-containing additive to biomass fuels rich in Cl and K for avoiding ash-related operational problems in fluidized beds and grate combustors originated from high KCl concentrations in the flue gases © 2009 American Chemical Society.

Biomass fuelled integrated gasification/gas turbines (BIG/GTs) have been found to be one of the most promising technologies to maximise electricity output in the sugar industry. However, biomass fuels contain alkali metals (Na and K) which may be released during the gasification processes and cause deleterious effects on the downstream hardware (e.g. the blades of gas turbines). Much research has therefore been focused on different kinds of gas cleaning. Most of these projects are using a fluidised bed gasifier and includes extensive gas cleaning which leads to a high capital investment. Increasing alkali retention/separation during the gasification may lead to improved producer gas quality and reduced costs for gas cleaning. However, very little quantitative information is available about the actual potential of this effect. In the present work, comparative bench-scale tests of bagasse gasification were therefore run in an isothermal fluidised bed gasifier and in a cyclone gasifier to evaluate which gasification process is most attractive as regards alkali retention/separation, and to try to elucidate the mechanisms responsible for the retention. The alkali retention in the fluidised bed gasifier was found to be in the range of 12-4% whereas in the cyclone gasifier the alkali separation was found to be about 70%. No significant coating of the fluidised bed's bed material particles could be observed. The SEM/EDS and the elemental maps of the bed material show that a non-sticky ash matrix consisting of mainly Si, Al and K were distributed in a solid form separated from the particles of bed material. This indicates the formation of a high temperature melting potassium containing silicate phase, which is continuously scavenged and lost from the bed through elutriation. © 2001 Elsevier Science Ltd. All rights reserved.

A method for avoiding excessive amount of alkali compounds and carryover particles in producer gas from gasification of sugar cane residue has been studied and evaluated. The cane sugar residue is gasified in a two-stage combustor at atmospheric pressure, where the first stage is a cyclone gasifier. The cyclone works as particle separator as well. This paper covers the results obtained for gasification of bagasse. Bagasse powder was injected into the cyclone with air and steam as transport medium. The gasification tests were made with two feeding rates, 39 and 52 kg/h. Seven experiments were conducted with the equivalence ratio being varied. The heating values of the producer gas are sufficient for stable gas turbine combustion. About 60-70% of the alkali input with fuel was separated from the producer gas in the cyclone. However the total alkali contents of the producer gas was found to be higher than in ABB Stal PFBC gas turbines and at least an order of magnitude higher than what is required by most gas turbine manufacturers for operation of a gas turbine. The carryover particles concentrations in the producer gas were found to be in the range of that for PFBC gas turbines, but higher than what is required by most gas turbine manufacturers for operation of a gas turbine. Samples studied with scanning electronic microscope give indication that most of the carryover particles are below 10 μm in size. Fly ash-melting tests have not shown any major ash melting up to 1200°C, but it was found that some of the particles entrained with producer gas were partially melted. Integrated experiments with a gas turbine need to be done for accurate evaluation of the possibilities to use the producer gas from the gasification of bagasse to run a gas turbine without problems of hard deposits and corrosion on the turbine blades. In part 2 of this two-part paper the results from cane trash gasification tests are reported. © 2001 Published by Elsevier Science Ltd.

In Part 1 of this two-part paper, results from gasification of bagasse in a cyclone gasifier have been reported. In this paper results from gasification of cane trash in the same cyclone gasifier are presented. The cane trash powder is injected into the cyclone with air as transport medium. The gasification tests were made with two feeding rates, 39 and 46 kg/h at two equivalence ratios of 0.25 and 0.20 and the gasification temperature ranging from 820°C to 850°C. It was found that the heating value of the producer gas is in the range of 4.5-4.8 MJ/Nm3(dry gas), which is sufficient for stable gas turbine combustion. Significant alkali separation has been achieved in the cyclone stage. However, the alkali levels and carryover particle concentrations in the producer gas were found to be higher than allowable in a gas turbine. Despite high ash melting temperatures found by the TGA-DTA, deposition problems cannot be excluded since some carryover panicles in the producer gas seem to have been melted and since some gasification of K and Na compounds is indicated. As an overall assessment, cane trash appears as a more problematic fuel than bagasse for this application. Integrated experiments with a gas turbine need to be done for accurate evaluation of the possibilities to use the producer gas from the gasification of cane trash to run a gas turbine without problems of hard deposits and corrosion on the turbine blades. © 2001 Published by Elsevier Science Ltd.

This paper presents a methodology to quantitatively measure H2S, So2 and NO2 fractions in gaseous CO2 by using broadband absorption spectroscopy at 1 and 40 bar. The mole fractions of binary- And 3-component mixtures of H2S, So2 and NO2 in CO2 with known fractions ranging from 35-250 ppm are successfully derived from the measured absorption spectra. The difference between the fitted and experimental mole fractions is less than 10% for all studied mixtures. The results successfully demonstrate that low fractions of H2S, So2 and NO2 in gaseous CO2 can be accurately measured at pipeline conditions by using broad band absorption spectroscopy.

The development of biomass-based energy conversion technologies has gradually been intensified throughout the last decade. The route based on pressurized entrained flow biomass gasification has an important role in this development. However, the issues of logistics and handling of the biomass requires thorough and detailed process integration studies in order to find optimal ways of imple- mentation of this technology. An interesting approach is to liquefy the biomass via fast pyrolysis to produce a bio-oil, which then could be disintegrated into the gasifier. In order to better understand how a generic type of externally gas-assisted atomizer performs for pyrolysis oil, spray characteriza- tion based on high-speed photography and case-independent image analysis were performed. Three different parameters were varied in order to study the atomization performance for the considered nozzle: The ambient pressure, the pyrolysis oil temperature, and the length of external extension of the prefilming center bluff body in the nozzle. It was found that an increase in ambient pressure and corresponding load as well as an extension of the center bluff body of the nozzle led to degradation in atomization performance. On the other hand, a moderate temperature increase that affects the fluid properties in a favorable way improved the atomization performance. In all considered cases for the tested nozzle, a notable fraction of the droplets in the spray were found in the large-size tail of the size distributions and it is uncertain whether this may have an effect on the fuel conversion in the gasification process.

Short particle residence time in entrained flow gasifiers demands the use of pulverized fuel particles to promote mass and heat transfer, resulting high fuel conversion rate. The pulverized biomass particles have a wide range of aspect ratios which can exhibit different dispersion behavior than that of spherical particles in hot product gas flows. This results in spatial and temporal variations in temperature distribution, the composition and the concentration of syngas and soot yield. One way to control the particle dispersion is to impart a swirling motion to the carrier gas phase. This paper investigates the dispersion behavior of biomass fuel particles in swirling flows. A two-phase particle image velocimetry technique was applied to simultaneously measure particle and gas phase velocities in turbulent isothermal flows. Post-processed PIV images showed that a poly-dispersed behavior of biomass particles with a range of particle size of 112–160 µm imposed a significant impact on the air flow pattern, causing air flow decelerated in a region of high particle concentration. Moreover, the velocity field, obtained from individually tracked biomass particles showed that the swirling motion of the carrier air flow gives arise a rapid spreading of the particles.

Soot creates technical challenges in entrained flow biomass gasification processes, e.g. clogging of flow passages, fouling on system components and reduced efficiency of gasification. This paper demonstrates a novel soot reduction method in a laboratory-scale entrained flow reactor by forced dispersion of biomass particles. Gasification of small biomass particles was done in a flat flame burner where a steady stream of biomass was sent. The flat flame burner was operated with a premixed sub-stoichiometric methane-air flame to simulate the conditions in an entrained flow gasifier. The dispersion of biomass particles was enhanced by varying the flow velocity ratio between particle carrier gas and the premixed flame. Primary soot particles evolved with the distance from the burner exit and the soot volume fraction was found to have a peak at a certain location. Enhanced particle separation diminished the peaks in the soot volume fraction by 35-56% depending on the particle feeding rates. The soot volume fraction was found to decrease towards an asymptotic value with increasing inter-particle distance.

Biofuel production from gasified black liquor is an interesting route to decrease green house gas emissions. The only pressurised black liquor gasifier currently in pilot operation is located in Sweden. In this work, synthesis gas was taken online directly from this gasifier, purified from hydrocarbons and sulphur compounds and for the first time catalytically converted to methanol in a bench scale equipment. Methanol was successfully synthesised during 45 h in total and the space time yield of methanol produced at 25 bar pressure was 0.16-0.19 g methanol/(g catalyst h). The spent catalyst exposed to gas from the gasifier was slightly enriched in calcium and sodium at the inlet of the reactor and in boron and nickel at the outlet of the reactor. Calcium, sodium and boron likely stem from black liquor whereas nickel probably originates from the stainless steel in the equipment. A slight deactivation, reduced surface area and mesoporosity of the catalyst exposed to gas from the gasifier were observed but it was not possible to reveal the origin of the deactivation. In addition to water, the produced methanol contained traces of hydrocarbons up to C 4, ethanol and dimethyl ether. © 2011 Elsevier B.V. All rights reserved.

Pyrolysis is a promising thermochemical technology for converting biomass to energy, chemicals and/or fuels. The objective of the present paper was to characterize fast pyrolysis products and to study pyrolysis oil fractionation. The products were obtained from different Nordic forest and agricultural feedstocks in a pilot scale cyclone pyrolysis plant at three different reactor temperatures. The results show that the main elements (C, H and O) and chemical compositions of the products produced from stem wood, willow, forest residue and reed canary grass are in general terms rather similar, while the products obtained from bark differ to some extent. The oil produced from bark had a higher H/Ceff ratio and heating value which can be correlated to a higher amount of pyrolytic lignin and extractives when compared with oils produced from the other feedstocks. Regardless of the original feedstock, the composition of the different pyrolysis oil fractions (condensed and aerosol) differs significantly from each other. However this opens up the possibility to use specifically selected fractions in targeted applications. An increased reactor temperature generally results in a higher amount of water and water insoluble material, primarily as small lignin derived oligomers, in the produced oil.

Slag formation in the grate-kiln process is a major problem for iron-ore pellet producers. It is therefore important to understand the slag formation mechanism in the grate-kiln production plant. This study initiated the investigation by in situ sampling and identifying particles in the flue gas from a full-scale 40 MW grate-kiln production plant for iron-ore pelletizing. Particles were sampled from two cases of combustion with pulverized coal and heavy fuel oil. The sampling location was at the transfer chute that was situated between the traveling grate and the rotary kiln. The particle-sampling system was set up with a water-cooled particle probe equipped with nitrogen gas dilution, cyclone, and low-pressure impactor. Sub-micrometer and fine particles were size-segregated in the impactor, while coarse particles (>6 μm) were separated with a cyclone before the impactor. Characterization of these particles was carried out with environmental scanning electron microscopy (ESEM), and the morphology of sub-micrometer particles was studied with transmission electron microscopy (TEM). The results showed that particles in the flue gas consisted principally of fragments from iron-ore pellets and secondarily of ashes from pulverized coal and heavy fuel oil combustions. Three categories of particle modes were identified: (1) sub-micrometer mode, (2) first fragmentation mode, and (3) second fragmentation mode. The sub-micrometer mode consisted of vaporized and condensed species; relatively high concentrations of Na and K were observed for both combustion cases, with higher concentrations of Cl and S from heavy fuel oil combustion but higher concentrations of Si and Fe and minor P, Ca, and Al from coal combustion. The first fragmentation mode consisted of both iron-ore pellet fines and fly ash particles; a significant increment of Fe (>65 wt %) was observed, with higher concentrations of Ca and Si during heavy fuel oil combustion but higher concentrations of Si and Al during coal combustion. The second fragmentation mode consisted almost entirely of coarse iron-ore pellet fines, predominantly of Fe (∼90 wt %). The particles in the flue gas were dominantly iron-ore fines because the second fragmentation mode contributed >96 wt % of the total mass of collected particles.

Dimethyl ether (DME), is an excellent diesel fuel that can be produced through gasification from multiple feedstocks. One particularly interesting renewable feedstock is the energy rich by-product from the pulping process called black liquor (BL). The concept of utilizing BL as gasifier feed, converting it via syngas to DME and then compensating the withdrawal of BL energy from the pulp mill by supplying biomass to a conventional combined heat and power plant, is estimated to be one of the most efficient conversion concepts of biomass to a renewable fuel on a well-to-wheel basis. This concept has been demonstrated by the four-year BioDME project, including field tests of DME-fueled heavy-duty trucks that are operated commercially. Up till the summer of 2013 more than 500 tons of BioDME has been produced and distributed to 10 HD trucks, which in total has run more than 1 million km in commercial service. © 2014 American Institute of Chemical Engineers Environ Prog, 33: 744–750, 2014

Fast pyrolysis oil can be used as a feedstock for syngas production. This approach can have certain advantages over direct biomass gasification. Pilot scale tests were performed to investigate the route from biomass via fast pyrolysis and entrained flow gasification to syngas. Wheat straw and clean pine wood were used as feedstocks; both were converted into homogeneous pyrolysis oils with very similar properties using in-situ water removal. These pyrolysis oils were subsequently gasified in a pressurized, oxygen blown entrained flow gasifier using a thermal load of 0.4 MW. At a pressure of 0.4 MPa and a lambda value of 0.4, temperatures around 1250 °C were obtained. Syngas volume fractions of 46% CO, 30% H2 and 23% CO2 were obtained for both pyrolysis oils. 2% of CH4 remained in the product gas, along with 0.1% of both C2H2 and C2H4. Minor quantities of H2S (3 vs. 23) cm3 m−3, COS (22 vs. 94) cm3 m−3 and benzene (310 vs. 532) cm3 m−3 were measured for wood- and straw derived pyrolysis oils respectively. A continuous 2-day gasification run with wood derived pyrolysis oil demonstrated full steady state operation. The experimental results show that pyrolysis oils from different biomass feedstocks can be processed in the same gasifier, and issues with ash composition and melting behaviour of the feedstocks are avoided by applying fast pyrolysis pre-treatment.

A residential cereal burner (20 kW) was used study the slagging characteristics of cereal grains with and without lime addition. The deposited bottom ash and slag were analyzed using X-ray diffraction (XRD), to identify the crystalline phases, and environmental scanning electron microscopy, coupled with energy-dispersive X-ray spectroscopy (ESEM/EDS), to study the morphology and elemental composition. Phase-diagram information was utilized to extract qualitative information about the behavior of cereal grain ashes under combustion conditions. Chemical equilibrium model calculations were used to interpret the experimental results. In addition, investigations of the melting behavior of the produced slags were conducted. The results showed significant differences in slagging characteristics between the fuels that were used. The slags consisted of high-temperature melting crystalline phases (calcium/magnesium potassium phosphates) and a potassium-rich phosphate melt for all cereal grains. For oat and barley, cristobalite was also identified in the slag. Furthermore, in these cases, the slags most probably contained a potassium-rich silica melt. The differences in the melting behaviors of the slags had a considerable effect on the performance of the burner. The addition of lime reduced the formation of slag for barley and totally eliminated it for rye and wheat. This occurs because lime contributes to the formation of high-temperature melting calcium potassium phosphates. © 2007 American Chemical Society.

The main objectives of this paper have been to evaluate the use of horse manure and wood-shavings as a fuel for heat production and to provide sets of data on the chemical composition, ash characteristics and ash forming elements of the fuel. Another objective has been to investigate the possibility to use the ash as fertiliser by analysing the heavy metal and nutrient contents. The results showed that the fuel is well suited for combustion for heat production causing low emissions of products of incomplete combustion. The emissions of NOx were however high due to the high content of fuel bound nitrogen. Emissions of CO and NOx were typically in the range of 30-150 mg/Nm3 and 280-350 mg/Nm3 at 10 vol% O2, respectively. The analysis of the ash showed on sufficiently low concentration of heavy metals to allow recycling. © 2009 Elsevier Ltd. All rights reserved.

Black liquor is a mix of organic and inorganic materials that is left after the kraft pulping process. In a modern pulp mill the pulping chemicals and the energy in the black liquor is recovered and used in the pulping cycle by burning the black liquor in a recovery burner. An alternative to the recovery boiler is to gasify the black liquor to produce an energy rich synthesis gas that can be upgraded into synthetic fuels or chemicals. Characterization of black liquor has mostly been done under conditions that are relevant for recovery boilers but the conditions in a gasifier differ significantly from this. In particular the droplets are much smaller and the heating rates are much higher. This paper presents an optical interferometric technique that has the potential to produce data under relevant conditions for gasification. In the paper, results are measured at atmospheric conditions and with relatively low heating rate. However, the method can be applied also for pressurized conditions and at heating rates that are only limited by the frame rate of the digital camera that is used to capture the transient event when the droplets are heated. In the paper the dynamic properties of the gas ejected from and the swelling during conversion of a single droplet are measured.

Pressurized entrained-flow gasification of renewable forest residues has the potential to produce high-quality syngas suitable for the synthesis of transport fuels and chemicals. The ash transformation behavior during gasification is critical to the overall production process and necessitates a level of understanding to implement appropriate control measures. Toward this end, ash deposits were collected from inside the reactor of a pilot-scale O 2-blown pressurized entrained-flow gasifier firing stem wood, bark, and pulp mill debarking residue (PMDR) in separate campaigns. These deposits were characterized with environmental scanning electron microscopy equipped with energy-dispersive X-ray spectrometry and X-ray diffractometry. The stem wood deposit contained high levels of calcium and was comparatively insubstantial. The bark and PMDR fuels contained contaminant sand and feldspar particles that were subsequently evident in each respective deposit. The bark deposit consisted of lightly sintered ash aggregates comprising presumably a silicate melt that enveloped particles of quartz and, to a lesser degree, feldspars. Discontinuous layers likely to be composed of alkaline-earth metal silicates were found upon the aggregate peripheries. The PMDR deposit consisted of a continuous slag that contained quartz and feldspar particles dispersed within a silicate melt. Significant levels of alkaline-earth and alkali metals constituted the silicate melts of both the bark and PMDR deposits. Overall, the results suggest that fuel contaminants (i.e., quartz and feldspars) play a significant role in the slag formation process during pressurized entrained-flow gasification of these woody biomasses.

The present work was performed to quantitatively investigate the spray characteristics from a swirling coaxial gasassisted atomizer for moderate industrial flow rates of water, low to medium swirl generation of the assisting air, and high momentum flux ratios at sonic air flow rates at the convergent nozzle exit. In the considered cases, two different liquid to gas mass flow ratios for two different nozzle contraction ratios were studied, with and without the use of swirl. The spray characteristics were obtained by using phase Doppler anemometry and a three-coordinate traversing system, which could accurately position the measurement volume in the spray. For the conditions considered in this paper, it was found that the introduced swirl reduces the axial velocity in the center core of the spray up to 45%. Furthermore, the spreading rate of the resulting spray jet increased when the swirl increased, and the liquid to gas mass flow ratio and the momentum flux ratio were decreased. The largest droplets were found in the center of the spray, and the smallest droplets appeared around the middle radial position of measurement. © 2010 by Begell House, Inc.

Introduction of pressurized gasification of black liquor in the pulping industry has the potential to give a significant increase in energy efficiency. However, uncertainties about the reliability and robustness of the technology are preventing large-scale market introduction. One important step toward a greater trust in the process reliability is the development of a better understanding of the sensitivity of the process to parameter variations. A computational fluid dynamics model for pressurized gasification of black liquor in an entrained-flow gasifier is presented and used for investigation of the effects of uncertainties in the specific heat capacity of black liquor, the radiation absorption coefficient, and the volatile devolatilization rate using factorial design methodology. It is found that all main factor effects, but none of the interaction effects, influence the considered responses: char conversion, maximum temperature, and outlet temperature. However, the main effects are found to be relatively small and the uncertainties in the examined model parameters would not invalidate the results from a design optimization with the presented model. Copyright © Taylor & Francis Inc.

Pressurized high temperature black liquor gasification might significantly improve the efficiency of the energy and chemical recovery cycle in kraft pulping. The process, which is based on the entrained-flow principle, is under development, and a scale-up from an existing pilot gasifier is planned. We developed a self-consistent computational fluid dynamic (CFD) model, in conjunction with pilot gasifier experiments, as a tool for scale-up. This report compares model predictions against experimental pilot gasifier data. The agreement between model and experiments is encouraging in certain areas, but significant discrepancies resulted for other areas. Model predictions of global performance parameters, such as sulfate reduction efficiency and carbon conversion, are in reasonable agreement with the experiments, but the predicted gas composition differed significantly from results of the experiments. Direct measurements of quantities to validate the current model validation are difficult to obtain because of severe conditions in the gasifier, and many of the model comparisons are based on indirect values. Hence, it is difficult to judge whether the errors come from the experiment or the simulation. Before we can draw a definite conclusion about the model's validity, improved in-situ measurements inside the gasifier are necessary and are currently under development. Successful development of a computational fluid dynamic model will further the development of black liquor gasification, leading to improved efficiency of the energy and chemical recovery cycle in kraft pulping.

High temperature pressurised black liquor gasification has the potential to significantly improve the efficiency of energy and chemical recovery in the pulping industry. However, a lack of demonstration of the reliability of the process has delayed its large scale industrial implementation. As an important step towards a greater trust in the process reliability, a self-consistent CFD model has been developed. This paper contains a detailed description of the model and a performance prediction of an entrained flow pilot gasifier for a typical operational condition. Emphasis is put on the modelling of input data for the CFD simulation where eight key assumptions form the basis for a consistent model of the black liquor composition. The results for the pilot gasifier performance with typical values for the design variables indicate that the droplet size should be

Pressurized high temperature black liquor gasification has the potential to significantly improve the efficiency of energy and chemical recovery in the pulping industry and to enable new processes, e.g. production of renewable automotive fuels from the formed synthesis gas. However, the current process is still considered as novel and the interest in validated computer models for scale-up and process optimisation is large. In this paper a sensitivity analysis on the four most important model parameters in the pre-processing 'droplet composition model' for a proposed CFD model has been performed. It was shown that careful measurements of the amount of sulphur released to the gas phase as H2S during devolatilization and the concentration ratio of Na2S and Na2SO4 in the black liquor char under real process conditions are of great importance for calibration of the model. © 2007 Elsevier Ltd. All rights reserved.