0
Research Papers: Energy From Biomass

# Hydrogen Chloride Release From Combustion of Corn Straw in a Fixed BedOPEN ACCESS

[+] Author and Article Information
Xiaohan Ren

School of Energy Science and Engineering,
Harbin Institute of Technology,
Harbin 150001, China;
Mechanical and Industrial Engineering,
Northeastern University,
Boston, MA 02115

Xiaoxiao Meng, Rui Sun

School of Energy Science and Engineering,
Harbin Institute of Technology,
Harbin 150001, China

Aidin Panahi, Emad Rokni, Yiannis A. Levendis

Mechanical and Industrial Engineering,
Northeastern University,
Boston, MA 02115

1Corresponding authors.

Contributed by the Advanced Energy Systems Division of ASME for publication in the JOURNAL OF ENERGY RESOURCES TECHNOLOGY. Manuscript received October 5, 2017; final manuscript received October 17, 2017; published online November 14, 2017. Editor: Hameed Metghalchi.

J. Energy Resour. Technol 140(5), 051801 (Nov 14, 2017) (9 pages) Paper No: JERT-17-1535; doi: 10.1115/1.4038313 History: Received October 05, 2017; Revised October 17, 2017

## Abstract

Chlorine plays an important role in the slagging and corrosion of boilers that burn high-chlorine content biomass. This research investigated the emissions of hydrogen chloride (HCl) gas from combustion of biomass in a fixed bed, as functions of the mass air flow rate through the bed and of the moisture content of the fuel. The biomass burned was corn straw, either raw or torrefied. Results showed that increasing the air flow rate through the bed increased the release of HCl gas, as a result of enhanced combustion intensity and associated enhanced heat release rates. When the airflow through the bed was increased by a factor of six, the amount of fuel-bound chlorine converted to HCl nearly tripled. Upon completion of combustion, most of the chlorine remained in the biomass ashes, with the exception of the highest air flow case where the fraction of chlorine released in HCl equaled that captured in the ashes. HCl emissions from torrefied biomass were found to be lower than those from raw biomass. Finally, drying the biomass proved to be beneficial in drastically curtailing the generation of HCl gas.

<>

## Introduction

Fossil fuels such as coal, oil, and natural gas still remain the dominant source of primary energy in the world [1]. However, due to environmental concerns related to climate change there is a widespread interest in utilizing renewable energy, such as solar, wind, tide, biomass, etc. As biomass combustion can be considered to be a nearly CO2-neutral energy source, its advancement is of current technological interest. Biomass can be co-fired with coal in existing furnaces or burned alone in dedicated furnaces [28].

Combustion is responsible for over 97% of the world's bio-energy generation [5,9]. However, biomass firing in utility boilers faces several issues, one of the most important ones being combustor slagging, fouling, and corrosion caused by the elevated alkali metal content of biomass. Slagging and fouling reduce heat transfer to combustor surfaces and causes corrosion and erosion problems, which influence the lifetime of the equipment [10]. Generally, the high potassium and chlorine contents of many types of biomass can potentially release high levels of gaseous KCl in the flue gas, which can deposit by condensation on cooler furnace surfaces (water tubes, super-heaters, etc.), and the high content of chlorine in those deposits may cause accelerated metal corrosion [11]. Baxter et al. [12] found that chlorine concentration in a fuel often dictates the amount of alkali metal vaporization during combustion more strongly than the alkali concentration in the fuel. In most cases, the chlorine appears to play a shuttle role, facilitating the transport of alkali from the fuel to the cooler combustor surfaces, where the alkalis often form sulfates. Besides, chlorine may cause additional corrosion by the formation of hydrogen chloride (HCl), which can promote scale failure on boiler surfaces. HCl or Cl2 liberating from this process, close to the metal surface, may cause further corrosion at high temperatures [13]. Possible reactions of alkali sulfate formation releasing HCl are listed in Table 3 of Ref. [14]. HCl is a significant contributor to corrosion in the boiler and, if released to the atmosphere, it also contributes to the acidification of the environment [15]. Furthermore, HCl at the presence of different carbon sources can be precursor to dioxin formation [16], and also, it can generate problematic submicrometer particles (PM1), as strong correlations between the PM1 yields and the contents Na, K, and Cl in the volatiles during combustion of biomass have been reported [13].

Jensen et al. [17] reported that a straw, containing 0.41% Cl, was released its chlorine to the gas phase in two steps; about 60% of the chlorine was released when this biomass was pyrolyzed at temperatures 400 °C and most of the remaining residual chlorine was released when temperatures reached 700–900 °C. Knudsen et al. [18] investigated the release of Cl, S, and K during pyrolysis and combustion of six types of biomass in a fixed bed furnace and also found a two-step release of Cl. Again, similar quantities of Cl (20–60%, depending on biomass type) were released at 500 °C, and by the time the temperature reached 800 °C, nearly 100% of chlorine was released. HCl was detected during the devolatilization of biomass. Björkman and Strömberg [16] found that pyrolysis of biomass samples (sugarcane trash containing 0.44% Cl, switch grass with 0.79% Cl, Lucerne with 0.29% Cl, straw with 0.18% Cl, etc.) at a temperature of 200 °C released less than 10% of their chlorine to the gas phase, at 200 °C as much as 20–50% of their chlorine was released. However, in their experiments even at 900 °C, 30–60% of the chlorine was still left in the char. Johansen et al. [19] found that pyrolysis of corn stover (with 0.69% Cl) at furnace temperatures up to 500 °C released ∼50 wt % of the Cl, oxidation at the same furnace temperature released less (∼40 wt %); presumably as HCl formed through ion-exchange reactions with functional groups in the organic matrix. They also reported that complete dechlorination of corn stover was achieved when it was burned at furnace temperatures above 800 °C. Van Lith et al. [20,21] found a high release of Cl (∼85% and ∼99%, respectively) from combustion of spruce (<0.01% Cl) and fiber board (0.05% Cl) at temperatures as low as 500 °C. They suggested that the principal mechanism for the Cl release from wood is from the reaction of metal chlorides with carboxyl groups or other proton-donating sites in the char during pyrolysis, resulting in the formation of HCl(g). Pedersen et al. [22] studied the effect of temperature on the release of metals, S and Cl from four different waste fractions (wood <0.01% Cl, shoes 3.2% Cl and polyvinyl chloride 48.7% Cl) in a lab-scale fixed-bed reactor and found that organically associated Cl (as in polyvinyl chloride) was released at low temperatures (<500 °C) as HCl(g). At higher temperatures, they suggested that the Cl release may be governed by the vaporization of metal chlorides.

Previous studies also addressed the chlorine-associated deposition and corrosion in biomass-fired boilers, especially in stoker boilers [23,24]. Due to the difficulties and expense of obtaining detailed in-bed data from full-scale furnaces where solid fuels burn on moving grates, past research relied on the combustion of such fuels (municipal solid waste, coal, or biomass) in grate fixed beds [25,26]. It has been argued before [2736] that combustion of solid fuels on an industrial moving grate can be approximated in the laboratory with combustion in a fixed bed. In the former combustor, the waste is supplied from the top of the moving grate, whereas air is injected from the bottom. The bed is ignited at the top. Incoming fuel is heated by radiation and convection from both the flame above the bed and from the hot walls of the bed. The air stream and the combustion products move upward, while the flame front moves downward. The fixed bed combustion can approximate the moving bed combustion if an imaginary column of fuel is followed as it moves down on the grate (see Fig. 1 in Ref. [27]). Fixed-bed combustion can be used to simulate moving-bed combustion due to the relatively small horizontal gradients (compared to the vertical gradients) in the bed layer [35]. Fuel heat up, drying, devolatilization, combustion of the volatiles, oxidation of the char residue and ash formation initiate at the top surface of the bed and descend toward its bottom. Upon burnout, the remaining ash at the bottom of the bed is discharged to a hopper. To simulate biomass (straw) combustion in grate boilers Zhou et al. [37] developed a one-dimensional unsteady heterogeneous mathematical model for combustion in a fixed bed, while Van der Lans et al. [38], developed a two-dimensional steady-state model to simulate straw combustion in a grate bed, predicting bed temperatures and burning rates. Shanmukharadhya and Sudhakar [39] studied the effect of biomass moisture on the flame front and found a considerable delay to ignition due to the drying of fuel.

Whereas there has been previous research on the combustion of solid fuels in fixed beds, including biomass, there was a scarcity of reports on the release of HCl from biomass combustion therein. Hence, this research investigated the HCl emissions from burning corn straw, and explored (a) the effects of the mass air flow per unit cross section of the bed (mass flux) perpendicular to the bed, and (b) the effects of the moisture content of biomass.

## Biomass Fuel Characterization and Description of the Experimental Apparatus

Air-dried corn straw was selected for these experiments based on its relative high planting rate in the north of China. Corn straw was collected at farms in the vicinity of Harbin Institute of Technology, China. Upon harvesting of the stack, its initial moisture (“as-received”) was 19.4%, and it was air dried (at room temperature) to prevent the growth of microorganisms in the sample. The proximate and ultimate analyses of the air-dried fuel (moisture content—6.2%) are listed in Table 1. Additionally, in order to study the effect of moisture on HCl release during corn straw combustion in the fixed bed furnace, samples of raw biomass were predried to three different degrees to attain three levels of moisture content, from the “as-received” moisture content of 19.4% down to 13.2% and including the aforementioned value of 6.2%.

In order to compare HCl release from raw and torrefied corn straw, torrefaction of corn straw was carried out in a horizontal muffle furnace, depicted in Fig. 1, in nitrogen atmosphere (at flow rate of 3 l per minute) at 250 °C for 20 min. The proximate and ultimate analyses of the torrefied corn straw are listed in Table 2.

A schematic of the one-dimensional fixed bed experimental setup is shown in Fig. 2. The fixed bed has a vertically oriented cylindrical combustion chamber. The chamber is 1.30 m high, with an inner diameter of 180 mm, which is composed of three layers of materials in the wall. The inner layer is made of 50 mm thick high alumina refractory pouring; the middle insulating layer is composed of a 150 mm thick refractory silica wool; the outer protective sleeve is made by 1Cr18Ni9Ti steel. More details about the experimental test rig are given in Ref. [35].

The fixed bed furnace setup consists of three sections: the furnace section, the measurement systems, and the air supply system. During the experiments, heat was supplied to a fixed bed of biomass by burning propane. A gas nozzle was placed at a furnace height of 750 mm away from the grate, tilted to 45 deg. At the beginning of each experiment, the propane torch was ignited, and then, its flow rate was kept at a constant value sufficient to maintain the chamber temperature at around 900 °C. The corn straw was heated by radiation from the high temperature propane flame. The bed temperatures were monitored by armored K-type thermocouples placed at different bed heights (positions 2–8), as specified in Table 3. The measuring range of the armored K-type thermocouples was 270–1379 °C, with a measurement error of ±2.5 °C. Above the grate, three gas-sampling probes were positioned at 208 mm, 298 mm, and 388 mm to monitor the gaseous emissions of combustion. In these experiments, the uppermost sampling probe (at 388 mm) was chosen for continuous monitoring. Primary combustion air was provided to the biomass fuel from the bottom wind-box of the bed, through the porous grate. Its flow was controlled by a flow meter, and its temperature was monitored by the level 1 thermocouple.

The combustion effluent was heated to 180 °C to avoid condensation of H2O, which can absorb HCl. It was then channeled through a fiber filter to collect particles. Thereafter, Fourier transform infra-red (FTIR) spectroscopy (with a GASMET DX4000 instrument) was used to monitor HCl and other gas compounds, such as CO, CO2, and CH4, in the hot and humid sample gas. LabVIEW software running on a microcomputer recorded the FTIR signals through a Data Translation (PCI-6221) data acquisition card. All experiments were repeated in triplicates, the mean values of which and one standard deviation for each case are presented in Sec. 3. The gas species concentration quantifications and the bed temperature's accuracy were determined in a previous paper [35]. Upon termination of each experiment, the corn straw bottom ash and fly ash were collected for analysis with ion chromatography [40]. The ash samples were first dried at 105 °C for 2 h. Then, they were immersed in ultra-high purity (metal impurity content is less than 1ppb) solution (HNO3: 6 ml, H2O2: 2 ml) and kept there for 2 h. After that, a new solution (HNO3:H2O2:HF = 4:2:2) was added to the samples, and thereafter the samples were heated to 120 °C at a rate of 20 °C/min and kept for 5 min. Afterward, the samples were heated to 200 °C with a heating rate of 16 °C/min and kept at the final temperature for 1 h. Finally, the solutions were ready for analysis by ion chromatography with a Dionex ICS-900 instrument.

In these experiments, the corn straw was segmented in chips that were 5 cm long with an average diameter of 1.7 cm, as shown in Fig. 2. An initial quantity of 0.5 kg of fuel was placed in the bed, the bulk density of which was measured to be approximately 81 kg/m3. The initial bed height was about 54 cm, and the diameter was around 18 cm. To investigate the effect of primary air flow on the emissions released during corn straw combustion in a fixed-bed furnace, five different air flow rates were implemented from the bottom of the reactor without preheating the primary air (20 °C) through the grate. The relative flow rate and excess air coefficient were listed in Table 4.

## Experimental Results and Discussion

###### The Effect of Air Flow Rate on HCl Release During Corn Straw Combustion.

The temporal evolution of bed temperatures at different heights in the fixed biomass bed (at locations 2–8) are shown in Fig. 3, for different mass fluxes of air through the bed. The bed temperature increased rapidly as the ignition front propagated downward and reached each embedded thermocouples successively, from T2, at the upper end of the bed, to T8 at the bottom of the bed. After the flame front passed by the location of each thermocouple, the temperature of the smouldering bed that was left behind decreased as heat losses to the surrounding gas and the inner furnace wall exceeded the heat generation [41]. The peak temperature of T2 is lower than T3 partially, because as the flame propagates downward, it leaves behind a progressively thicker layer of smoldering chars and ashes which inhibits heat losses upward in the axial direction, and partially because the side walls of the furnace are progressively getting hotter also impeding heat losses from the bed in the radial direction. Temperatures peak progressively at higher values as the flames reach the bottom of the bed. As the air flow flux through the bed increases, the following phenomena become evident (a) ignition is delayed, as attested by the offset in the onset times of the sequential thermocouple recordings; (b) the flame front travels faster, as attested by the time elapsed between the thermocouple recordings; and (c) peak temperatures are somewhat higher, see Fig. 3. The former observation may be attributed to bed ignition delay by the propane torch, caused by the convective cooling effect of the higher airflow velocities through the bed. The latter two observations are likely caused by the enhanced heat generation at higher airflow fluxes, which provide more oxygen and enhance the burning rate of the biomass fuel.

Figure 4 and Table 5 present the ignition front velocity at different bed heights. The ignition front propagation velocity was calculated based on the timing of the temperature measurements: Vf = s/t, where s is the distance between the adjacent temperature ports, t is the time taken for the ignition front to move between the adjacent temperature ports [35]. As is shown in Fig. 4 and Table 5, with the increase of the mass air flow rate, the ignition front propagation velocity increased and heat generation was higher, resulting in enhanced char burning.

The HCl emission profiles from combustion of biomass in a fixed bed, monitored at a bed height of 338 mm and measured by the FTIR, are shown in Fig. 5 for different air flow rates in the bed. At low flowrates, the HCl profile exhibit two peaks, as explained in an ensuing paragraph. However, as the flowrate was increased, the two HCl peaks became progressively closer, and finally, they overlapped (as shown in Figs. 5(d) and 5(e)). Results in Figs. 5(a)5(e) corresponded to emissions from burning raw biomass, whereas those in Fig. 5(f) corresponded to emissions from burning torrefied biomass.

The experimentally measured mass emissions of HCl, shown in Fig. 5, were integrated with time, were then normalized by the input biomass mass in each case, and they are shown in Fig. 6(a). Therein, it could be observed that mass emissions of HCl were clearly affected by the differing air fluxes in the experiments and the resulting combustion efficiencies. As shown earlier, the peak temperature during corn straw burning was also increased when more oxygen was supplied to the bed per unit time, which means that the combustion of corn straw was intensified, and more energy was released with an increase of the primary air flow. This is typically the case until a critical point is reached, where a further increase in the primary air flowrate results in slowing down the combustion process [36]. This occurs when the approach air flow velocity exceeds the rate of downstream propagation of the flame. The results displayed in Fig. 6(b) show that the conversion of chlorine to HCl is monotonically increasing with increasing the air flowrate, suggesting that the aforesaid critical point was not quite reached in these experiments. An additional likely reason for the increasing trends in Fig. 6 is that the enhanced availability of oxygen at increasing flowrates can produce more proton-donating sites, which may react with metal chloride to release HCl. The error bars displayed in Figs. 6(a) and 6(b) represent one standard deviation of the data points in each case. The variability in the data stems from unavoidable differences in measurement among three consecutive runs in each case.

Hydrogen chloride and CH3Cl have been identified as the main products of Cl release during low temperature biomass pyrolysis [4244]. CH3Cl emissions from biomass pyrolysis and combustion have been ascribed to two processes. One is a free-radical process that takes place during pyrolysis or combustion of cellulose [42,43]. During this process, Cl radicals may also generate HCl. Hence, CH3Cl and HCl are two competing pathways for Cl radicals during biomass pyrolysis or combustion. The other process of forming CH3Cl is the charcoal-catalyzed reaction of gaseous methanol and HCl produced by pyrolysis [44], as shown below: Display Formula

(1)$CH3OH+HCl→charcoal-catalyzedCH3Cl+H2O$

However, the comparatively low temperatures that are typically associated with CH3Cl emissions and the lack of an O2 requirement clearly demonstrate that heating alone, rather than combustion, is sufficient for release of CH3Cl during biomass pyrolysis or burning [45]. It has been reported in the literature that during combustion, Cl radical-generated CH3Cl accounts for ∼3% of the total Cl [46,47]. Therefore, at the presence of oxygen during combustion, the yield of CH3Cl from the first process is expected to be lower, which promotes the HCl release. However, as the yield of HCl from the first process increases, the equilibrium of the reaction shown in Eq. (2) shifts from HCl to CH3Cl. In the high-temperature combustion experiments conducted herein, the CH3Cl emissions were found to be very low, amounting to less than 1% of the total chlorine released.

A comparison of the HCl time-release profiles depicted in Fig. 5, and the bed ignition propagation profiles shown in Figs. 3 and 4 suggest that HCl release during combustion occurred into two steps: one in the process of devolatilization and volatile combustion; the other during char combustion. At locally fuel-rich or stoichiometric conditions, as the flame propagated through the burning fixed bed of corn straw, 388 mm tall (while the total height was 540 mm, the sampling location was 388mm), the temperature at any given location (e.g., T4) increased rapidly due to volatile mater combustion. HCl evolved with the pyrolyzing volatiles. It is possible that evolving HCl underwent secondary reactions with K in the pores of the corn straw to form KCl(s), which was then retained in the char. When sufficient heat accumulated to ignite the corn straw char and its temperature approached or exceeded 700–800 °C, Cl was released as KCl in the gas phase, as Cl is the main facilitator for K release through sublimation of solid KCl [19]. Moreover, the HCl evolution profiles of Figs. 5(a) and 5(b) suggest that more HCl was released during char combustion than during devolatilization and volatile combustion. To verify this observation an additional experiment would be needed to first pyrolyze a bed of corn straw in nitrogen to form chars and then burn the chars with air. Such an experiment would allow to measure HCl separately during pyrolysis and combustion of the char; however, it could not be done in the present facility. Finally, previous research [20] reported that during pyrolysis, the HCl released could also be captured by alkali in the char and, upon char combustion, it could be re-released as HCl Display Formula

(2)$Char-COOH+MCl (s)→Char-COOM+HCl (g)$

where char represents the char matrix, and M represents alkali metals, such as potassium and sodium. This is probably because, during char combustion, KCl may react with carboxyl groups or other proton-donating sites in biomass and release HCl [20].

Analysis of collected fly ashes and bottom ashes (and residual chars) from combustion of corn straw in a fixed bed at different air flow rates, shown in Table 6, indicates that the majority of chlorine remained in the bottom ashes/chars.

As the air flow rate in the bed increases, the amount of Cl retained in fly ash increases, predominately mostly as potassium chloride [18], whereas the amount of chlorine retained in the bottom ash decreases. In each case, the amount of Cl retained in the fly ash was a little higher than the amount of Cl converted to HCl. Finally, at the highest air flow, the chlorine distribution to HCl, bottom ash, and fly ash were almost equal. The amounts of unaccounted chlorine decreased with increasing air flow rates, with the exception of the highest flow rate (200 l/min). These results are in line with the hypothesis that the formation of other species, such as CH3Cl, slows at oxygen-rich atmospheres.

###### Comparison of HCl Release During Raw and Torrefied Corn Straw Combustion.

The proximate and ultimate analyses of raw and torrefied are shown in Tables 1 and 2. Upon torrefaction of the air dried raw corn straw, which contained 6.2% moisture, the moisture content decreased to 2.3%. Correspondingly, its chlorine content decreased from 0.63% to 0.28%. As shown in Fig. 5(f), the peak time of HCl release during torrefied corn straw combustion, at q = 1.18 kg/m2s, occurred earlier, as compared to the raw corn straw burning under the same conditions. Moreover, the integrated HCl mass emissions decreased from the value of 2.15 mg/g of raw corn straw to 0.91 mg/g of torrefied corn straw. This amounts to a reduction by a factor of 2.35, and it can be mainly attributed to the fact that torrefied corn straw has less chlorine than raw corn straw by nearly the same factor. This is a significant reduction in HCl emissions, which is expected to curtail the likelihood of corrosion and slagging in commercial boilers. The fact that the conversion of chlorine to HCl in the case of torrefied corn straw combustion only a little lower than that of the raw corn straw, see Fig. 6(b), may be explained as follows: A the torrefied biomass has a higher K/Cl ratios than its raw biomass precursor, Cl may have a better chance to react with the number-limited proton-donating sites or with water vapor and SiO2, leading to the not too different mass fractions of chlorine in raw and torrefied biomass converted to HCl, see also Ref. [40].

###### Effect of Moisture Content on HCl Release During Corn Straw Combustion.

The effect of the moisture content of the corn straw on the release of HCl was also investigated in this work. As shown in Fig. 7, high moisture corn straw biomass resulted in both longer ignition delay times and longer burn-out times. In all of these experiments, the air flow rate was kept constant at 0.53 kg/m2s. When the moisture content of the biomass was increased to 19.4%, i.e., three times the moisture content the air-dried corn straw which had a moisture content of 6.2%, the ignition of the bed was delayed from 700 s to 2800 s. The corresponding bed burn-out time was almost 4000 s, compared to the 2000 s of the air-dried corn straw, confirming the common knowledge that dried biomass burns faster. Moreover, the HCl mass emissions from the burning bed increased with the moisture content of the biomass, as attested from the conversion of Cl to HCl, depicted in Fig. 8. When the moisture content was increased from 6.2% to 19.4%, the conversion of Cl to HCl increased from 25.2% to 49.5%, i.e., more than twice the conversion in the case of air dry corn straw. This can be attributed to the presence of additional H2O molecules in the pyrolyzates of the moist biomass during pyrolysis and combustion. Yang et al. [36] found that an increase of moisture in the fuel induces a higher flame front temperature at low primary air flow rates. Köser et al. [48] found that during coal combustion with increasing temperature, the chemical equilibrium is shifted from H2O toward OH. Therefore, steamed water at higher combustion temperatures can generate more free radicals, such as OH radicals and H radicals, resulting in more effective collision between such radicals and Cl radicals, from both organic chlorine and inorganic chlorine H2O.

## Conclusions

This laboratory-scale investigation studied the effects of the air flow rate and the fuel moisture content on the HCl emissions during corn straw combustion in a fixed bed furnace. Results revealed that increasing the mass air flow rate was found to significantly increase the flame propagation velocity through the fixed bed of biomass and mildly increase the local bed temperatures, resulting in a dramatic increase on HCl release. Under most conditions, the majority of Cl was retained in ash. Moreover, the amount of HCl released from combustion of torrefied corn straw was lower than that released from combustion of raw corn straw. Finally, reducing the moisture content of the biomass was found to decrease the amount of the HCl released during its combustion.

###### Highlights

1. (1)Experiments addressed the hydrogen chloride (HCl) release from fixed bed combustion of corn straw.
2. (2)High air flow fluxes through the bed enhanced the release of HCl.
3. (3)High air flow fluxes were found to increase the flame propagation velocity through the bed.
4. (4)HCl emissions from torrefied biomass were found to be lower than those from raw biomass.
5. (5)HCl emissions from burning corn straw increased with its moisture content.

## Funding Data

• Financial support of the National Natural Science Foundation of China (Grant No. 51476046) is gratefully acknowledged.

## References

Saidur, R. , Abdelaziz, E. A. , Demirbas, A. , Hossain, M. S. , and Mekhilef, S. , 2011, “ A Review on Biomass as a Fuel for Boilers,” Renewable Sustainable Energy Rev., 15(5), pp. 2262–2289.
Baxter, L. , 2005, “ Biomass-Coal Co-Combustion: Opportunity for Affordable Renewable Energy,” Fuel, 84(10), pp. 1295–1302.
Tillman, D. A. , 2000, “ Biomass Cofiring: The Technology, the Experience, the Combustion Consequences,” Biomass Bioenergy, 19(6), pp. 365–384.
Demirbas, A. , 2005, “ Potential Applications of Renewable Energy Sources, Biomass Combustion Problems in Boiler Power Systems and Combustion Related Environmental Issues,” Prog. Energy Combust. Sci., 31(2), pp. 171–192.
Nussbaumer, T. , 2003, “ Combustion and Co-Combustion of Biomass:  Fundamentals, Technologies, and Primary Measures for Emission Reduction,” Energy Fuels, 17(6), pp. 1510–1521.
Van den Broek, R. , Faaij, A. , and Van Wijk, A. , 1996, “ Biomass Combustion for Power Generation,” Biomass Bioenergy, 11(4), pp. 271–281.
Brennan, L. , and Owende, P. , 2010, “ Biofuels From Microalgae—A Review of Technologies for Production, Processing, and Extractions of Biofuels and Co-Products,” Renewable Sustainable Energy Rev., 14(2), pp. 557–577.
Quesito, F. , Santarelli, M. , Leone, P. , and Aggarwal, S. K. , 2013, “ Biogas Combustion in Premixed Flames or Electrochemical Oxidation in SOFC: Exergy and Emission Comparison,” ASME J. Energy Resour. Technol., 135(2), p. 021201.
Demirbas, A. , 2004, “ Combustion Characteristics of Different Biomass Fuels,” Prog. Energy Combust. Sci., 30(2), pp. 219–230.
Romeo, L. M. , and Gareta, R. , 2009, “ Fouling Control in Biomass Boilers,” Biomass Bioenergy, 33(5), pp. 854–861.
Kassman, H. , Broström, M. , Berg, M. , and Åmand, L. E. , 2011, “ Measures to Reduce Chlorine in Deposits: Application in a Large-Scale Circulating Fluidised Bed Boiler Firing Biomass,” Fuel, 90(4), pp. 1325–1334.
Baxter, L. L. , and Miles , T. R. M., Jr. , Jenkins, B. M. , Milne, T. , Dayton, D. , Bryerse, R. W. , and Oden, L. L. , 1998, “ The Behavior of Inorganic Material in Biomass-Fired Power Boilers: Field and Laboratory Experiences,” Fuel Process. Technol., 54(1–3), pp. 47–78.
Nielsen, H. P. , Frandsen, F. J. , Dam-Johansen, K. , and Baxter, L. L. , 2000, “ The Implications of Chlorine-Associated Corrosion on the Operation of Biomass-Fired Boilers,” Prog. Energy Combust. Sci., 26(3), pp. 283–298.
Hindiyarti, L. , Frandsen, F. , Livbjerg, H. , Glarborg, P. , and Marshall, P. , 2008, “ An Exploratory Study of Alkali Sulfate Aerosol Formation During Biomass Combustion,” Fuel, 87(8), pp. 1591–1600.
Reichel, H. H. , and Schirmer, U. , 1989, “ Waste Incineration Plants in the FRG: Construction, Materials, Investigation on Cases of Corrosion,” Mater. Corros., 40(3), pp. 135–141.
Björkman, E. , and Strömberg, B. , 1998, “ Release of Chlorine From Biomass at Pyrolysis and Gasification Conditions 1,” Energy Fuels, 11(5), pp. 1026–1032.
Jensen, P. A. , Frandsen, F. J. , DamJohansen, K. , and Sander, B. , 2000, “ Experimental Investigation of the Transformation and Release to Gas Phase of Potassium and Chlorine During Straw Pyrolysis,” Energy Fuels, 14(6), pp. 1280–1285.
Knudsen, J. N. , Jensen, P. A. , and Damjohansen, K. , 2004, “ Transformation and Release to the Gas Phase of Cl, K, and S During Combustion of Annual Biomass,” Energy Fuels, 18(5), pp. 1385–1399.
Johansen, J. M. , Jakobsen, J. G. , Frandsen, F. J. , and Glarborg, P. , 2011, “ Release of K, Cl, and S During Pyrolysis and Combustion of High-Chlorine Biomass,” Energy Fuels, 25(11), pp. 4961–4971.
Van Lith, S. C. , Alonso-Ramírez, V. , Jensen, P. A. , Frandsen, F. J. , and Glarborg, P. , 2006, “ Release to the Gas Phase of Inorganic Elements During Wood Combustion—Part 1:  Development and Evaluation of Quantification Methods,” Energy Fuels, 20(3), pp. 964–978.
Van Lith, S. C. , Jensen, P. A. , Frandsen, F. J. , and Glarborg, P. , 2008, “ Release to the Gas Phase of Inorganic Elements During Wood Combustion—Part 2: Influence of Fuel Composition,” Energy Fuels, 22(3), pp. 1598–1609.
Pedersen, A. J. , Van Lith, S. C. , Frandsen, F. J. , Steinsen, S. D. , and Holgersen, L. B. , 2010, “ Release to the Gas Phase of Metals, S and Cl During Combustion of Dedicated Waste Fractions,” Fuel Process. Technol., 91(9), pp. 1062–1072.
Michelsen, H. P. , Frandsen, F. , Dam-Johansen, K. , and Larsen, O. H. , 1998, “ Deposition and High Temperature Corrosion in a 10 MW Straw Fired Boiler,” Fuel Process. Technol., 54(1–3), pp. 95–108.
Hansen, L. A. , Nielsen, H. P. , Frandsen, F. J. , Dam-Johansen, K. , Hørlyck, S. , and Karlsson, A. , 2000, “ Influence of Deposit Formation on Corrosion at a Straw-Fired Boiler,” Fuel Process. Technol., 64(1–3), pp. 189–209.
Ryu, C. , Yang, Y. B. , Khor, A. , Yates, N. E. , Sharifi, V. N. , and Swithenbank, J. , 2006, “ Effect of Fuel Properties on Biomass Combustion: Part I—Experiments—Fuel Type, Equivalence Ratio and Particle Size,” Fuel, 85(7–8), pp. 1039–1046.
Lin, J. C. M. , 2007, “ Combination of a Biomass Fired Updraft Gasifier and a Stirling Engine for Power Production,” ASME J. Energy Resour. Technol., 129(1), pp. 66–70.
Shin, D. , and Choi, S. , 2000, “ The Combustion of Simulated Waste Particles in a Fixed Bed,” Combust. Flame, 121(1–2), pp. 167–180.
Kuo, J. T. , Hsu, W. S. , and Yo, T. C. , 1996, “ Effect of Air Distribution on Solid Fuel Bed Combustion,” ASME J. Energy Resour. Technol., 119(2), pp. 120–128.
Bragato, M. , Joshi, K. , Carlson, J. B. , Tenório, J. A. S. , and Levendis, Y. A. , 2012, “ Combustion of Coal, Bagasse and Blends Thereof—Part I: Emissions From Batch Combustion of Fixed Beds of Fuels,” Fuel, 96(7), pp. 43–50.
Bragato, M. , Joshi, K. , Carlson, J. B. , Tenório, J. A. S. , and Levendis, Y. A. , 2011, “ Combustion of Coal, Bagasse and Blends Thereof—Part II: Speciation of PAH Emissions,” Fuel, 90(7), pp. 51–58.
Levendis, Y. A. , Atal, A. , and Carlson, J. B. , 1998, “ PAH and Soot Emissions From Combustion of Coal and Waste Tire-Derived-Fuel in Fixed Beds,” Combust. Sci. Technol., 134(1–6), pp. 407–431.
Khor, A. , Ryu, C. , Yang, Y. B. , Sharifi, V. N. , and Swithenbank, J. , 2007, “ Straw Combustion in a Fixed Bed Combustor,” Fuel, 86(1–2), pp. 152–160.
Zhou, H. , Jensen, A. D. , Glarborg, P. , and Kavaliauskas, A. , 2006, “ Formation and Reduction of Nitric Oxide in Fixed-Bed Combustion of Straw,” Fuel, 85(5), pp. 705–716.
Saastamoinen, J. J. , and Taipale, R. , 2000, “ Propagation of the Ignition Front in Beds of Wood Particles,” Combust. Flame, 123(1), pp. 214–226.
Liang, L. , Sun, R. , Fei, J. , Wu, S. , Liu, X. , Dai, K. , and Yao, N. , 2008, “ Experimental Study on Effects of Moisture Content on Combustion Characteristics of Simulated Municipal Solid Wastes in a Fixed Bed,” Bioresour. Technol., 99(15), pp. 7238–7246. [PubMed]
Yang, Y. B. , Sharifi, V. N. , and Swithenbank, J. , 2004, “ Effect of Air Flow Rate and Fuel Moisture on the Burning Behaviours of Biomass and Simulated Municipal Solid Wastes in Packed Beds,” Fuel, 83(11–12), pp. 1553–1562.
Zhou, H. , Jensen, A. D. , Glarborg, P. , Jensen, P. A. , and Kavaliauskas, A. , 2005, “ Numerical Modeling of Straw Combustion in a Fixed Bed,” Fuel, 84(4), pp. 389–403.
Van Der Lans, R. P. , Pedersen, L. T. , Jensen, A. , Glarborg, P. , and Dam-Johansen, K. , 2000, “ Modelling and Experiments of Straw Combustion in a Grate Furnace,” Biomass Bioenergy, 19(3), pp. 199–208.
Shanmukharadhya, K. S. , and Sudhakar, K. G. , 2007, “ Effect of Fuel Moisture on Combustion in a Bagasse Fired Furnace,” ASME J. Energy Resour. Technol., 129(3), pp. 248–253.
Ren, X. , Sun, R. , Chi, H. H. , Meng, X. , Li, Y. , and Levendis, Y. A. , 2017, “ Hydrogen Chloride Emissions From Combustion of Raw and Torrefied Biomass,” Fuel, 200, pp. 37–46.
Zhao, W. , Li, Z. Q. , Wang, D. W. , Zhu, Q. Y. , Sun, R. , Meng, B. H. , and Zhao, G. , 2008, “ Combustion Characteristics of Different Parts of Corn Straw and NO Formation in a Fixed Bed,” Bioresour. Technol., 99(8), pp. 2956–2963. [PubMed]
Palmer, T. Y. , 1976, “ Combustion Sources of Atmospheric Chlorine,” Nature, 263(5572), pp. 44–46.
Eklund, G. , Pedersen, J. R. , and Strömberg, B. , 1988, “ Methane, Hydrogen Chloride and Oxygen Form a Wide Range of Chlorinated Organic Species in the Temperature Range 400 °C–950 °C,” Chemosphere, 17(3), pp. 575–586.
Reinhardt, T. E. , and Ward, D. E. , 1995, “ Factors Affecting Methyl Chloride Emissions From Forest Biomass Combustion,” Environ. Sci. Technol., 29(3), pp. 825–832.
Mcroberts, W. C. , Keppler, F. , Kalin, R. M. , and Harper, D. B. , 2003, “ Chloride Methylation by Plant Pectin: An Efficient Environmentally Significant Process,” Science, 301(5630), pp. 206–209. [PubMed]
Andreae, M. O. , Atlas, E. , Harris, G. W. , Kock, A. D. , Koppmann, R. , Maenhaut, W. , Manø, S. , Pollock, W. H. , Rudolph, J. , Scharffe, D. , Schebeske, G. , and Welling, M. , 1996, “ Methyl Halide Emissions From Savanna Fires in Southern Africa,” J. Geophys. Res.: Atmos., 101(D19), pp. 23603–23613.
Lobert, J. M. , Keene, W. C. , Logan, J. A. , and Yevich, R. , 1999, “ Global Chlorine Emissions From Biomass Burning: Reactive Chlorine Emissions Inventory,” J. Geophys. Res. Atmos., 104(D7), pp. 8373–8389.
Köser, J. , Becker, L. G. , Vorobiev, N. , Schiemann, M. , Scherer, V. , Böhm, B. , and Dreizler, A. , 2015, “ Characterization of Single Coal Particle Combustion Within Oxygen-Enriched Environments Using High-Speed OH-PLIF,” Appl. Phys. B, 121(4), pp. 459–464.
View article in PDF format.

## References

Saidur, R. , Abdelaziz, E. A. , Demirbas, A. , Hossain, M. S. , and Mekhilef, S. , 2011, “ A Review on Biomass as a Fuel for Boilers,” Renewable Sustainable Energy Rev., 15(5), pp. 2262–2289.
Baxter, L. , 2005, “ Biomass-Coal Co-Combustion: Opportunity for Affordable Renewable Energy,” Fuel, 84(10), pp. 1295–1302.
Tillman, D. A. , 2000, “ Biomass Cofiring: The Technology, the Experience, the Combustion Consequences,” Biomass Bioenergy, 19(6), pp. 365–384.
Demirbas, A. , 2005, “ Potential Applications of Renewable Energy Sources, Biomass Combustion Problems in Boiler Power Systems and Combustion Related Environmental Issues,” Prog. Energy Combust. Sci., 31(2), pp. 171–192.
Nussbaumer, T. , 2003, “ Combustion and Co-Combustion of Biomass:  Fundamentals, Technologies, and Primary Measures for Emission Reduction,” Energy Fuels, 17(6), pp. 1510–1521.
Van den Broek, R. , Faaij, A. , and Van Wijk, A. , 1996, “ Biomass Combustion for Power Generation,” Biomass Bioenergy, 11(4), pp. 271–281.
Brennan, L. , and Owende, P. , 2010, “ Biofuels From Microalgae—A Review of Technologies for Production, Processing, and Extractions of Biofuels and Co-Products,” Renewable Sustainable Energy Rev., 14(2), pp. 557–577.
Quesito, F. , Santarelli, M. , Leone, P. , and Aggarwal, S. K. , 2013, “ Biogas Combustion in Premixed Flames or Electrochemical Oxidation in SOFC: Exergy and Emission Comparison,” ASME J. Energy Resour. Technol., 135(2), p. 021201.
Demirbas, A. , 2004, “ Combustion Characteristics of Different Biomass Fuels,” Prog. Energy Combust. Sci., 30(2), pp. 219–230.
Romeo, L. M. , and Gareta, R. , 2009, “ Fouling Control in Biomass Boilers,” Biomass Bioenergy, 33(5), pp. 854–861.
Kassman, H. , Broström, M. , Berg, M. , and Åmand, L. E. , 2011, “ Measures to Reduce Chlorine in Deposits: Application in a Large-Scale Circulating Fluidised Bed Boiler Firing Biomass,” Fuel, 90(4), pp. 1325–1334.
Baxter, L. L. , and Miles , T. R. M., Jr. , Jenkins, B. M. , Milne, T. , Dayton, D. , Bryerse, R. W. , and Oden, L. L. , 1998, “ The Behavior of Inorganic Material in Biomass-Fired Power Boilers: Field and Laboratory Experiences,” Fuel Process. Technol., 54(1–3), pp. 47–78.
Nielsen, H. P. , Frandsen, F. J. , Dam-Johansen, K. , and Baxter, L. L. , 2000, “ The Implications of Chlorine-Associated Corrosion on the Operation of Biomass-Fired Boilers,” Prog. Energy Combust. Sci., 26(3), pp. 283–298.
Hindiyarti, L. , Frandsen, F. , Livbjerg, H. , Glarborg, P. , and Marshall, P. , 2008, “ An Exploratory Study of Alkali Sulfate Aerosol Formation During Biomass Combustion,” Fuel, 87(8), pp. 1591–1600.
Reichel, H. H. , and Schirmer, U. , 1989, “ Waste Incineration Plants in the FRG: Construction, Materials, Investigation on Cases of Corrosion,” Mater. Corros., 40(3), pp. 135–141.
Björkman, E. , and Strömberg, B. , 1998, “ Release of Chlorine From Biomass at Pyrolysis and Gasification Conditions 1,” Energy Fuels, 11(5), pp. 1026–1032.
Jensen, P. A. , Frandsen, F. J. , DamJohansen, K. , and Sander, B. , 2000, “ Experimental Investigation of the Transformation and Release to Gas Phase of Potassium and Chlorine During Straw Pyrolysis,” Energy Fuels, 14(6), pp. 1280–1285.
Knudsen, J. N. , Jensen, P. A. , and Damjohansen, K. , 2004, “ Transformation and Release to the Gas Phase of Cl, K, and S During Combustion of Annual Biomass,” Energy Fuels, 18(5), pp. 1385–1399.
Johansen, J. M. , Jakobsen, J. G. , Frandsen, F. J. , and Glarborg, P. , 2011, “ Release of K, Cl, and S During Pyrolysis and Combustion of High-Chlorine Biomass,” Energy Fuels, 25(11), pp. 4961–4971.
Van Lith, S. C. , Alonso-Ramírez, V. , Jensen, P. A. , Frandsen, F. J. , and Glarborg, P. , 2006, “ Release to the Gas Phase of Inorganic Elements During Wood Combustion—Part 1:  Development and Evaluation of Quantification Methods,” Energy Fuels, 20(3), pp. 964–978.
Van Lith, S. C. , Jensen, P. A. , Frandsen, F. J. , and Glarborg, P. , 2008, “ Release to the Gas Phase of Inorganic Elements During Wood Combustion—Part 2: Influence of Fuel Composition,” Energy Fuels, 22(3), pp. 1598–1609.
Pedersen, A. J. , Van Lith, S. C. , Frandsen, F. J. , Steinsen, S. D. , and Holgersen, L. B. , 2010, “ Release to the Gas Phase of Metals, S and Cl During Combustion of Dedicated Waste Fractions,” Fuel Process. Technol., 91(9), pp. 1062–1072.
Michelsen, H. P. , Frandsen, F. , Dam-Johansen, K. , and Larsen, O. H. , 1998, “ Deposition and High Temperature Corrosion in a 10 MW Straw Fired Boiler,” Fuel Process. Technol., 54(1–3), pp. 95–108.
Hansen, L. A. , Nielsen, H. P. , Frandsen, F. J. , Dam-Johansen, K. , Hørlyck, S. , and Karlsson, A. , 2000, “ Influence of Deposit Formation on Corrosion at a Straw-Fired Boiler,” Fuel Process. Technol., 64(1–3), pp. 189–209.
Ryu, C. , Yang, Y. B. , Khor, A. , Yates, N. E. , Sharifi, V. N. , and Swithenbank, J. , 2006, “ Effect of Fuel Properties on Biomass Combustion: Part I—Experiments—Fuel Type, Equivalence Ratio and Particle Size,” Fuel, 85(7–8), pp. 1039–1046.
Lin, J. C. M. , 2007, “ Combination of a Biomass Fired Updraft Gasifier and a Stirling Engine for Power Production,” ASME J. Energy Resour. Technol., 129(1), pp. 66–70.
Shin, D. , and Choi, S. , 2000, “ The Combustion of Simulated Waste Particles in a Fixed Bed,” Combust. Flame, 121(1–2), pp. 167–180.
Kuo, J. T. , Hsu, W. S. , and Yo, T. C. , 1996, “ Effect of Air Distribution on Solid Fuel Bed Combustion,” ASME J. Energy Resour. Technol., 119(2), pp. 120–128.
Bragato, M. , Joshi, K. , Carlson, J. B. , Tenório, J. A. S. , and Levendis, Y. A. , 2012, “ Combustion of Coal, Bagasse and Blends Thereof—Part I: Emissions From Batch Combustion of Fixed Beds of Fuels,” Fuel, 96(7), pp. 43–50.
Bragato, M. , Joshi, K. , Carlson, J. B. , Tenório, J. A. S. , and Levendis, Y. A. , 2011, “ Combustion of Coal, Bagasse and Blends Thereof—Part II: Speciation of PAH Emissions,” Fuel, 90(7), pp. 51–58.
Levendis, Y. A. , Atal, A. , and Carlson, J. B. , 1998, “ PAH and Soot Emissions From Combustion of Coal and Waste Tire-Derived-Fuel in Fixed Beds,” Combust. Sci. Technol., 134(1–6), pp. 407–431.
Khor, A. , Ryu, C. , Yang, Y. B. , Sharifi, V. N. , and Swithenbank, J. , 2007, “ Straw Combustion in a Fixed Bed Combustor,” Fuel, 86(1–2), pp. 152–160.
Zhou, H. , Jensen, A. D. , Glarborg, P. , and Kavaliauskas, A. , 2006, “ Formation and Reduction of Nitric Oxide in Fixed-Bed Combustion of Straw,” Fuel, 85(5), pp. 705–716.
Saastamoinen, J. J. , and Taipale, R. , 2000, “ Propagation of the Ignition Front in Beds of Wood Particles,” Combust. Flame, 123(1), pp. 214–226.
Liang, L. , Sun, R. , Fei, J. , Wu, S. , Liu, X. , Dai, K. , and Yao, N. , 2008, “ Experimental Study on Effects of Moisture Content on Combustion Characteristics of Simulated Municipal Solid Wastes in a Fixed Bed,” Bioresour. Technol., 99(15), pp. 7238–7246. [PubMed]
Yang, Y. B. , Sharifi, V. N. , and Swithenbank, J. , 2004, “ Effect of Air Flow Rate and Fuel Moisture on the Burning Behaviours of Biomass and Simulated Municipal Solid Wastes in Packed Beds,” Fuel, 83(11–12), pp. 1553–1562.
Zhou, H. , Jensen, A. D. , Glarborg, P. , Jensen, P. A. , and Kavaliauskas, A. , 2005, “ Numerical Modeling of Straw Combustion in a Fixed Bed,” Fuel, 84(4), pp. 389–403.
Van Der Lans, R. P. , Pedersen, L. T. , Jensen, A. , Glarborg, P. , and Dam-Johansen, K. , 2000, “ Modelling and Experiments of Straw Combustion in a Grate Furnace,” Biomass Bioenergy, 19(3), pp. 199–208.
Shanmukharadhya, K. S. , and Sudhakar, K. G. , 2007, “ Effect of Fuel Moisture on Combustion in a Bagasse Fired Furnace,” ASME J. Energy Resour. Technol., 129(3), pp. 248–253.
Ren, X. , Sun, R. , Chi, H. H. , Meng, X. , Li, Y. , and Levendis, Y. A. , 2017, “ Hydrogen Chloride Emissions From Combustion of Raw and Torrefied Biomass,” Fuel, 200, pp. 37–46.
Zhao, W. , Li, Z. Q. , Wang, D. W. , Zhu, Q. Y. , Sun, R. , Meng, B. H. , and Zhao, G. , 2008, “ Combustion Characteristics of Different Parts of Corn Straw and NO Formation in a Fixed Bed,” Bioresour. Technol., 99(8), pp. 2956–2963. [PubMed]
Palmer, T. Y. , 1976, “ Combustion Sources of Atmospheric Chlorine,” Nature, 263(5572), pp. 44–46.
Eklund, G. , Pedersen, J. R. , and Strömberg, B. , 1988, “ Methane, Hydrogen Chloride and Oxygen Form a Wide Range of Chlorinated Organic Species in the Temperature Range 400 °C–950 °C,” Chemosphere, 17(3), pp. 575–586.
Reinhardt, T. E. , and Ward, D. E. , 1995, “ Factors Affecting Methyl Chloride Emissions From Forest Biomass Combustion,” Environ. Sci. Technol., 29(3), pp. 825–832.
Mcroberts, W. C. , Keppler, F. , Kalin, R. M. , and Harper, D. B. , 2003, “ Chloride Methylation by Plant Pectin: An Efficient Environmentally Significant Process,” Science, 301(5630), pp. 206–209. [PubMed]
Andreae, M. O. , Atlas, E. , Harris, G. W. , Kock, A. D. , Koppmann, R. , Maenhaut, W. , Manø, S. , Pollock, W. H. , Rudolph, J. , Scharffe, D. , Schebeske, G. , and Welling, M. , 1996, “ Methyl Halide Emissions From Savanna Fires in Southern Africa,” J. Geophys. Res.: Atmos., 101(D19), pp. 23603–23613.
Lobert, J. M. , Keene, W. C. , Logan, J. A. , and Yevich, R. , 1999, “ Global Chlorine Emissions From Biomass Burning: Reactive Chlorine Emissions Inventory,” J. Geophys. Res. Atmos., 104(D7), pp. 8373–8389.
Köser, J. , Becker, L. G. , Vorobiev, N. , Schiemann, M. , Scherer, V. , Böhm, B. , and Dreizler, A. , 2015, “ Characterization of Single Coal Particle Combustion Within Oxygen-Enriched Environments Using High-Speed OH-PLIF,” Appl. Phys. B, 121(4), pp. 459–464.

## Figures

Fig. 1

Schematic of the electrically heated horizontal muffle furnace used for the torrefaction of corn straw

Fig. 2

Schematic of the fixed bed furnace for combustion of biomass samples

Fig. 3

Bed temperature history versus time at different heights from the grate. Air mass fluxes increased by a factor of six in the displayed plots from (a) q = 0.18 kg/m2 s to (e) q = 1.18 kg/m2 s: (a) temperature at different heights at q = 0.18 kg/m2 s, (b) temperature at different heights at q = 0.35 kg/m2 s, (c) temperature at different heights at q = 0.53 kg/m2 s, (d) temperature at different heights at q = 0.88 kg/m2 s, (e) temperature at different heights at q = 1.18 kg/m2 s.

Fig. 4

Ignition front propagation velocity at different bed positions and different air fluxes through the bed

Fig. 5

HCl mass emissions (μg/unit gram corn straw) at different mass air fluxes: (a)–(e) raw biomass, (f) torrefied biomass burned with the highest air mass flux in these experiments: (a) HCI mass emissions at q = 0.18 kg/m2 s, (b) HCI mass emissions at q = 0.35 kg/m2 s, (c) HCI mass emissions at q = 0.53 kg/m2 s, (d) HCI mass emissions at q = 0.88 kg/m2 s, (e) HCI mass emissions at q = 1.18 kg/m2 s, and (f) HCI mass emissions at q = 1.18 kg/m2 s

Fig. 6

(a) Integrated HCl mass emissions (mg/gram corn straw) and (b) Cl (%) conversion to HCl during corn straw combustion in a fixed bed furnace, both versus mass flux. Note: 1.18-T means the condition of torrefied corn straw combustion at q = 1.18 kg/m2s.

Fig. 7

HCl mass emissions during corn straw of different moisture content combustion at mass air flow of 0.53 kg/m2 s

Fig. 8

(a) Integrated HCl mass emissions (mg/gram corn straw) and (b) Cl (%) conversion to HCl during corn straw combustion of different moisture contents

## Tables

Table 1 Chemical compositions (wt %) of raw corn straw with different moisture contents
Table 2 Chemical compositions of torrefied corn straw at T = 300 °C
Table 3 Axial position of thermocouples in the fixed bed furnace
Table 4 Air flow rate and excess air coefficient
Note: $λ=actual air/stoichiometric air$.
Table 5 Average ignition front propagation velocity and highest temperature at different mass air flow fluxes
Table 6 Chlorine accounting in combustion of corn straw at different air flow rates

## Discussions

Some tools below are only available to our subscribers or users with an online account.

### Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related Proceedings Articles
Related eBook Content
Topic Collections