i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( ) e8 Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he The characteristics of biomass gasification in multistage heating and gradient chain gasifier Jianjun Cai a, Shuzhong Wang a,*, Qingcheng Wang b, Cao Kuang a a School of Energy and Power Engineering, Xi'an Jiao Tong University, Xi'an, 710049, China Institute of Energy and Resources Comprehensive Utilization Research, Shanghai Institute of Technology, Shanghai, 201418, China b article info abstract Article history: The characterization on gasification of biomass briquette in a sectional healing of reactor Received 24 March 2016 was studied in this article The results indicated that the temperature of drying stage was Accepted 19 April 2016 higher than those of oxidizing and reducing stages in multistage heating and gradient Available online xxx chain gasifier (MHGCG) Through comparison with the normal situation, the gasification efficiency was improved significantly with the increase of the temperature of drying stage Keywords: appropriately, and with the decrease of the oxidizing and reducing temperature When the Biomass equivalence ratio (ER) was 0.28 in the oxidizing stage, the weight loss of biomass and the Gasification gasification efficiency was 43% and 56%, respectively The volume fraction of O2, CO2, H2 Optimization and CO was 4%, 10%, 14% and 24%, respectively, and the ultimate volume fraction of NO, Multistage heating and gradient NOX, and SO2 was about 0.024%, 0.025% and 0.032%, respectively In addition, most of the chain gasifier raw biomass (about 95%) was transferred to the discharge port of MHGCG Therefore, the gradient-chain has little effect on the disturbance of biomass briquetting fuel (biomass briquette) in the vertical direction © 2016 Hydrogen Energy Publications LLC Published by Elsevier Ltd All rights reserved Introduction As a renewable and environmentally friendly energy source, biomass (i.e., any organic non-fossil fuel) and its utilization are gaining an increasingly important role in the world wide [1] In addition, biomass has a high utilization potential and is one of the most important energy sources in the future [2e4] Gasification is one of the promising technologies to exploit energy from renewable biomass, which is derived from all living matters, and thus is located everywhere on the earth [5e8] Specially, biomass has the potential to accelerate the realization of hydrogen as a major fuel of the future [9] So biomass has been considered as one of the most promising sources of renewable energy [10] In the open literature, there are many research works using fix bed or fluidized-bed in the area of biomass gasification This study mainly emphasizes the important aspects of the temperature, gasify agent, and biomass type [11e16] The operating conditions of gasification e.g residence time, gasification temperature, and gasifying agent is usually different in the zone of drying, pyrolysis, oxidizing, and reducing Therefore, to optimize this operating conditions needs to consider the different in the zone of drying, pyrolysis, oxidizing, and reducing separately [17,18] However, the knowledge in this area is still limited in the literature We have attempted in this work to research the different demands of gasification temperature in the stage of drying, pyrolysis, oxidizing, and reducing To achieve this objective, the sectional heating furnace was made Based on the furnace, the following experimental work was carried out * Corresponding author Tel.: þ86 2982665157; fax: þ86 29 82668708 E-mail address: szwang@aliyun.com (S Wang) http://dx.doi.org/10.1016/j.ijhydene.2016.04.128 0360-3199/© 2016 Hydrogen Energy Publications LLC Published by Elsevier Ltd All rights reserved Please cite this article in press as: Cai J, et al., The characteristics of biomass gasification in multistage heating and gradient chain gasifier, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.04.128 i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( ) e8 in order to obtain the information about the effect of gasification temperature on different gasification stages made in Shanghai Green New Energy into Technology Services Ltd The ultimate and proximate analysis results are presented in Table The real figure of the MHGCG system is shown in Fig The unique tailor-made configuration of the MHGCG system mainly consists of a instrument control box (Fig 1-A), MHGCG (Fig 1-B), the supply system of gasifying agent (Fig 1-C), and a blower (Fig 1-D) The temperatures, transmission speeds, Experimental Biomass Briquetting Fuel (BMF) with particle size of  20 mm is used as the feedstock in the tests The BMF is Table e Proximate and ultimate analysis of BMF Proximate analysis FC 15.36% Ultimate analysis VM Ash M C H O S N 74.92% 1.81% 7.91% 46.88% 5.27% 37.94% 0.05% 0.14% Fig e The real figure of the MHGCG system Fig e The distribution of TCs in the MHGCG system Please cite this article in press as: Cai J, et al., The characteristics of biomass gasification in multistage heating and gradient chain gasifier, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.04.128 i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( ) e8 Table e The description of the MHGCG system No Position No Position TC01 TC02 TC03 TC04 Gas outlet Gas outlet Above the pyrolysis zone Above the oxidizing zone TC05 TC06 TC07 TC08 The drying zone Below the pyrolysis zone Below the oxidizing zone The reducing zone residence time, and the opening degree of blower at different zones (e.g drying, pyrolysis, oxidizing, and reducing) are controlled by the instrument control box Compared with the traditional fixed bed gasification [9,19e21], the MHGCG has the following advantages: The operating conditions of gasification (e.g residence time, gasification temperature, and gasifying agent in the zone of drying, pyrolysis, oxidizing, and reducing) are easily controlled by MHGCG Therefore, this operating conditions is Table e The experimental parameter of MHGCG system Terms Drying Pyrolysis Oxidation Reduction Thickness of BMF (m) 0.03 Weight of BMF (kg) 0.945 Volume of air (m3) Residence time (min) 3.57 Flow rate of air (m3/h) 100 Temperature ( C) 0.03 0.945 3.57 100 0.03 0.945 3.9 3.57 4.57 600 0.03 0.945 3.57 400 considered separately in the zone of drying, pyrolysis, oxidizing, and reducing It is suitable for large batch of the raw biomass gasification The requirement of raw biomass size is not strict in MHGCG The MHGCG has lots of other preferences e.g simple structure, good sealing performance, flexible process layout and lower power consumption The distribution of thermocouples (TCs) is shown in Fig The MHGCG system totally has thermocouples They are located on different positions These positions are listed in the Table The flue gas analyzer (E4400-S) is made in America E-Instruments ltd It is used to measure the composition of flue gas e.g O2, CO, CO2, NO, NO2, and SO2 The temperature of flue gas (T flue), the temperature of air (T air), the efficiency of biomass gasification (Efficiency), and the rate of biomass weight loss (Losses) also can be measured by E4400-S Based on theoretical calculation and practical considerations for suitable MHGCG gasification regime, the experimental parameters of MHGCG are shown in Table Fig e The temperature of TC01-04 collected vs the residence time Please cite this article in press as: Cai J, et al., The characteristics of biomass gasification in multistage heating and gradient chain gasifier, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.04.128 i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( ) e8 1) To assure the flow rate of gasifying agent at different zones According to the ultimate analysis of BMF, the theoretical air of BMF (L0) is 4.31 m3/kg In all experiments, air is injected in the oxidizing zone Initial height of BMF in the oxidizing zone is 0.03 m, and the weight of BMF is 1.89 kg The porosity of biomass one the chain is 0.5 Therefore, the actual weight of biomass is 0.945 kg According to the rotating speed of transmission shaft, the residence time is 3.57 at different zones When ER is 0.28, the actual volume of air (L) is 1.09 m3 Therefore, the flow rate of air is 4.57 m3/h 2) To assure the heating temperature at different zones In the oxidizing zone, the fix carbon is oxidized by the reaction of oxidation, and large heat is released to the furnace Therefore, the heat is used to dry BMF, as well as, to increase the temperature of the pyrolysis and reducing zones Moreover, the temperature are measured by K-type thermocouples As shown in Table 3, the drying, pyrolysis, oxidizing, and reducing zone is preset as 100  C, 100  C, 600  C, 400  C, respectively Results and discussion Figs and shows the temperature of TCs (TC01~08) collected In 0e24 min, the pre-heating temperature was collected by TCs, as show in the region of A Figs and As the actual temperature of MHGCG’ furnace was heating up to the preset temperature, the motors of transmission were opened in the zone of pyrolysis, oxidation, and reduction In addition, when the residue time had been set up, the motors of transmission in the zone of dry was opened later Meanwhile, the biomass feeding was started from the hopper, the temperature at this moment in MHGCG system was shown in the region of B in Figs and When BMF had exhausted in the hopper, the temperature was collected by TCs at this moment, as shown in the region of C in Figs and The average temperature at different positions is shown in Fig The temperature of the region below the oxidizing zone (TC07 collected) was highest, and followed by the temperature of the region above the oxidizing zone (TC04 collected), but the temperature of the region flue gas outlet (TC01 collected) was lowest Theoretically, the rang of temperature in the drying, pyrolysis, oxidizing, and reducing zone is 200e300  C, 500e600  C, 1000e1200  C, and 700e900  C, respectively However, in the MHGCG system, the highest temperature was found in the region of oxidation (as show in Figs 3e5 the TC 04 and TC 07 collected, about 607.5  C), followed by the region of pyrolysis (as show in Figs 3e5 the TC 03 and TC 06 collected, about 549.5  C), and the lowest temperature was found in the region of reducing (as show in Figs 3e5 the TC 08 collected, about 466  C) The gap between the experimental results and the theoretical results is shown Table The average experimental temperature for pyrolysis was lightly lower than the Fig e The temperature of TC05-08 collected vs the residence time Please cite this article in press as: Cai J, et al., The characteristics of biomass gasification in multistage heating and gradient chain gasifier, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.04.128 i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( ) e8 Fig e The average temperature of different TCs collected Table e The contrast analysis of experimental and theoretical temperature Terms Experimental temperature ( C) Theoretical temperature ( C) Temperature difference ( C) Absolute percentage (%) drying Pyrolysis Oxidation Reduction 572.4 549.5 250 550 322.4 129 À0.5 0.09 607.5 1100 466.0 800 À492.5 À334.0 44.8 41.8 theoretical temperature, and the average experimental temperature for reduction was obviously lower than the theoretical temperature, but the average experimental temperature for drying, oxidizing, were obvious higher than the theoretical temperature Specially, the average experimental temperature for drying was obvious higher than the theoretical temperature Therefore, the storage security of BMF decreased Compared with the theoretical temperature, the average experimental temperature for oxidizing and reducing were lower 44% and 41%, respectively The plausible reason of this phenomenon could be explained that the flue gas with high temperature largely flow form the zone of oxidation into the zone of drying and pyrolysis However, the zone of reduction located in the end of the chain In addition, there was virtually nonexistent the flue gas with high temperature Therefore, the temperature of reducing zone decreased sharply Through comparison with the normal situation, the gasification efficiency was improved significantly with increase the temperature of drying zone appropriately, and decrease the temperature of oxidizing and reducing zone The experimental results indicated that the MHGCG system still played positive roles in BMF gasification The content of the results of this research should be detail analyzed in the further research The concentration of gas flue components in the tested is shown in Fig With the residue time increasing, the volume fraction of O2 decreased initially and then kept stable gradually But the volume fraction of CO2 increased initially and then kept stable gradually In addition, increasing the residue time in the tested range obvious increased the volume fraction of H2 and CO When the experiment was beginning, the BMF feeding was started from the hopper Because of the residues time was 3.57 at the zone of dry and pyrolysis respectively, BMF was transferred to the zone of oxidation at the time of 7.14 At the same time, the volume fraction of CO2 was increased sharply, but the volume fraction of O2 was decreased, but a large amount of energy was liberated Therefore, the volume fraction of H2 and CO was increased In addition, ER was 0.28 at the zone of oxidation, and the fixed carbon was combusted incompletely Therefore, the volume fraction of CO was increased slowly With BMF was transferred to the zone of oxidation continuously, the volume fraction of O2, CO2, H2 and CO kept stable gradually At this point, the volume fraction of O2, CO2, H2 and CO was 4%, 10%, 14% and 24%, respectively In the MHGCG system, the volume fraction of CO was lower than other systems The plausible reason of this phenomenon can be explained by the reaction of Boudouard, water-gas, and steam reforming reduced in the zone of reduction Fig e The concentration of gas flue components vs the residence time at outlet Please cite this article in press as: Cai J, et al., The characteristics of biomass gasification in multistage heating and gradient chain gasifier, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.04.128 i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( ) e8 With the residence time increasing, the volume fraction of NO and NOX decreased initially and then increased lightly, and the changing trend of volume fraction of NO and NOX was accordant The results indicated that most of the flue gas of NOX originated in NO In addition, the plausible reason of this phenomenon can be explained that the the volume fraction of NO and NOX decreases with increasing temperature However, the volume fraction of SO2 increased initially and then kept stable gradually with the residence time increasing The plausible reason of this phenomenon could be explained that BMF was transferred to the zone of oxidation at the time of 7.14 Therefore, most of sulfur in the BMF was then converted to the SO2 The ultimate volume fraction of NO, NOX, and SO2 was about 0.024%, 0.025% and 0.032%, respectively The average temperature of flue gas is shown in Fig Increasing the residue time in the tested range increased the average temperature of flue gas The plausible reason of this phenomenon can be explained that the heat transfer in MHGCG system was not installed leading to poor heat dissipation The content of the optimization of the heat dissipation in the MHGCG system will be detail analyzed in the further research The weight loss rate of BMF in the MHGCG system is shown in Fig With the residue time increasing, the rate of weight loss decreased gradually, and finally kept stable The weight loss of BMF was increased initially and then decreased dramatically in range of time 0e6 Those may be due to the reaction of BMF oxidation happened The weight loss of BMF decreased gradually to 43% at the time 12 The gasification efficiency of BMF is shown Fig In the time 0e7 min, the gasification efficiency of BMF increased gradually At the time min, the gasification efficiency of BMF was beginning to stabilize, about 56% The distribution of ash at different zones is shown in Fig 10 In addition, the distribution of ash at the zone of drying, pyrolysis, oxidation, and reduction is shown in Fig 10-A, B, C, and D, respectively The distribution of ash at the end of the discharge port is shown in Fig 10-E Specially, the partial enlargement of ash at different zones e.g drying, pyrolysis, Fig e The average temperature of flue gas vs the residence time at the outlet Fig e The weight loss of BMF vs the residence time oxidation, reduction, and the discharge port is shown in Fig 10-a, b, c, d, and e, respectively As show in Fig 10-A, BMF still retained the relatively complete appearance But was lightly blackening as show in Fig 10-a This proofs that BMF is little changed to char under the high temperature atmosphere As show in Fig 10- B/b, the appearance of BMF is mostly blackening This proofed that BMF was mostly turned into char As show in Fig 10-C/c, the appearance of BMF was mostly turned into gray white This proofed that BMF was mostly oxidized to ash As show in Fig 10-D/d, the appearance of BMF was mostly turned into gray white This proofed that BMF was mostly turned into white ash But As show in Fig 10E/e, the appearance of BMF still retained lightly block char Overall, BMF was mostly dropped into the discharge port, about 95%, and the shape of ash was strip-like Therefore, the gradient-chain has little effect on the disturbance of BMF in the vertical direction Fig e The combustion efficiency of BMF vs the residence time Please cite this article in press as: Cai J, et al., The characteristics of biomass gasification in multistage heating and gradient chain gasifier, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.04.128 i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( ) e8 Fig 10 e The distribution of ash at different positions Conclusions This work investigated the characteristics of BMF gasification in the MHGCG system Important conclusions drawn from the present study as follows: 1) In the MHGCG system, the temperature of drying zone was higher than the temperature of oxidizing and reducing zones Through comparison with the normal situation, the gasification efficiency was improved significantly with increase the temperature of drying zone appropriately, and decrease the temperature of oxidizing and reducing zone 2) When ER was 0.28 in the oxidizing zone, the weight loss of biomass and the gasification efficiency was 43% and 56%, respectively In addition, the volume fraction of O2, CO2, H2 and CO was 4%, 10%, 14% and 24%, respectively And the ultimate volume fraction of NO, NOX, and SO2 was about 0.024%, 0.025% and 0.032%, respectively 3) The mostly raw biomass (about 95%) was transferred to the discharge port of MHGCG, and the shape of ash was striplike Therefore, the gradient-chain has little effect on the disturbance of BMF in the vertical direction references [1] vandenBroek R, Faaij A, vanWijk A Biomass combustion for power generation Biomass & Bioenergy 1996;11:271e81 [2] Asadullah M Barriers of commercial power generation using biomass gasification gas: a review Renew Sustain Energy Rev 2014;29:201e15 [3] Parthasarathy P, Narayanan KS Hydrogen production from steam gasification of biomass: influence of process parameters on hydrogen yield e a review Renew Energy 2014;66:570e9 [4] Scholz R, Beckmann M, Pieper C, Muster M, Weber R Considerations on providing the energy needs using exclusively renewable sources: energiewende in Germany Renew Sustain Energy Rev 2014;35:109e25 [5] Tekin K, Karagoz S, Bektas S A review of hydrothermal biomass processing Renew Sustain Energy Rev 2014;40:673e87 [6] Wu X, Zhang Z, Piao G, He X, Chen Y, Kobayashi N, et al Behavior of mineral matters in Chinese coal ash melting during char-CO2/H2O gasification reaction Energy & Fuels 2009;23:2420e8 [7] Zhang G, Reinmoeller M, Klinger M, Meyer B Ash melting behavior and slag infiltration into alumina refractory simulating co-gasification of coal and biomass Fuel 2015;139:457e65 Please cite this article in press as: Cai J, et al., The characteristics of biomass gasification in multistage heating and gradient chain gasifier, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.04.128 i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y x x x ( ) e8 [8] Lv X, Xiao J, Du YZ, Shen LH, Zhou YY Experimental study on biomass steam gasification for hydrogen-rich gas in doublebed reactor Int J Hydrogen Energy 2014;39:20968e78 [9] Kalinci Y, Hepbasli A, Dincer I Biomass-based hydrogen production: a review and analysis Int J Hydrogen Energy 2009;34:8799e817 [10] Lim JS, Manan ZA, Alwi SRW, Hashim H A review on utilisation of biomass from rice industry as a source of renewable energy Renew Sustain Energy Rev 2012;16:3084e94 [11] Gonzalez JF, Roman S, Bragado D, Calderon M Investigation on the reactions influencing biomass air and air/steam gasification for hydrogen production Fuel Process Technol 2008;89:764e72 [12] Sutton D, Kelleher B, Ross JRH Review of literature on catalysts for biomass gasification Fuel Process Technol 2001;73:155e73 [13] Delgado J, Aznar MP, Corella J Biomass gasification with steam in fluidized bed: effectiveness of CaO, MgO, and CaOMgO for hot raw gas cleaning Ind Eng Chem Res 1997;36:1535e43 [14] Manovic V, Anthony EJ Lime-based sorbents for hightemperature CO2 capture-a review of sorbent modification methods Int J Environ Res Public Health 2010;7:3129e40 [15] Gao N, Li A, Quan C A novel reforming method for hydrogen production from biomass steam gasification Bioresour Technol 2009;100:4271e7 [16] Udomsirichakorn J, Salam PA Review of hydrogen-enriched gas production from steam gasification of biomass: the prospect of CaO-based chemical looping gasification Renew Sustain Energy Rev 2014;30:565e79 [17] DiBlasi C Kinetic and heat transfer control in the slow and flash pyrolysis of solids Ind Eng Chem Res 1996;35:37e46 [18] Herguido J, Corella J, Gonzalezsaiz J Steam gasification of lignocellulosic residues in a fluidized-bed at a small pilot scale e effect of the type of feedstock Ind Eng Chem Res 1992;31:1274e82 [19] Sharma AK Experimental study on 75 KWth downdraft (biomass) gasifier system Renew Energy 2009;34:1726e33 [20] Olgun H, Ozdogan S, Yinesor G Results with a bench scale downdraft biomass gasifier for agricultural and forestry residues Biomass & Bioenergy 2011;35:572e80 [21] Dogru M, Midilli A, Akay G, Howarth CR Gasification of leather residues e part I Experimental study via a pilot scale air blown downdraft gasifier Energy Sources 2004;26:35e44 Please cite this article in press as: Cai J, et al., The characteristics of biomass gasification in multistage heating and gradient chain gasifier, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.04.128