The Experts below are selected from a list of 1137 Experts worldwide ranked by ideXlab platform
Hui Jin - One of the best experts on this subject based on the ideXlab platform.
-
hydrogen production from Supercritical Water Gasification of soda black liquor with various metal oxides
Renewable Energy, 2020Co-Authors: Changqing Cao, Yupeng Xie, Liuhao Mao, Wenwen Wei, Jinwen Shi, Hui JinAbstract:Abstract Supercritical Water Gasification is an innovative handling method of black liquor, which can also produce hydrogen-rich gases. In this study, the catalytic activity of 14 common metal oxides on SCWG of black liquor were investigated and the catalytic mechanism was studied through X-ray photoelectron spectroscopy (XPS) analysis. All the tested oxides improved the Gasification efficiency and V2O5, WO3 and Co2O3 showed the highest performance. The H2 yields of 21.67 and 21.03 mol/kg were achieved with the presence of Co2O3 and ZnO respectively. The Gasification efficiency increased with the increasing V2O5 amount, but the H2 fraction increased firstly and then decreased. The highest H2 fraction of 44.59% was obtained with V2O5 loading amount of 45 wt%. The increase of reaction time improved the CE, but the further prolongation had little influence. The XPS analysis of CuO and Fe2O3 showed some of them were reduced to metal (Cu) or lower-valence oxides (Cu2O, FeO). The metal oxides probably promoted black liquor decomposition by introducing reactive oxygen, and the generated metal also catalyzed the Gasification. Accordingly, an oxidation reactor could be introduced to recycle the metal oxides, which may help to realize the complete Gasification of black liquor or other refractory wastes at milder temperatures.
-
study on the surface structure development of porous char particles in catalytic Supercritical Water Gasification process
Fuel Processing Technology, 2019Co-Authors: Chao Fan, Hui Jin, Fei Shang, Huifang Feng, Jingli SunAbstract:Abstract Porous structure and its development have significant influence on the heat and mass transfer between char particle and surrounding fluid, and the unique properties of Supercritical Water might make this process different. In this work, the catalytic Supercritical Water Gasification experiments of semi-coke were conducted with K2CO3 as the catalyst at 650 °C to 750 °C, and the porous structure was characterized by nitrogen adsorption and SEM. Both micropores of 1.8 nm and mesopores that were enlarged in the Gasification process were detected. K2CO3 addition was found to obviously promote the development of mesopore structure, while temperature had no obvious influence on structure development. Specific surface area and pore volume increased after Gasification by one to two orders of magnitude, most up to 600 m2∙g−1 and 0.57 cm3∙g−1, respectively. Fractal dimension D increased sharply firstly due to the formation of a large amount of pores in the initial stage and then began to decrease because of the plasticity of char. The obtained structure evolution rules would be used for the establishment and optimization of kinetic models and the study of heat and mass transfer characteristics between char particle and surrounding fluid.
-
evaluation of effect of evaporation on Supercritical Water Gasification of black liquor by energy and exergy analysis
International Journal of Hydrogen Energy, 2017Co-Authors: Changqing Cao, Jia Chen, Wen Cao, Hui JinAbstract:Abstract Supercritical Water Gasification (SCWG) is a promising innovative black liquor handling method. The low concentration of black liquor is a burden for the system scale and investment cost. In this study, we introduced black liquor evaporator to increase the concentration using self-generated steam and power, and studied its influence on the energy and exergy efficiency. The results showed that increasing black liquor concentration from 10 wt% to 20 wt% reduced the energy efficiency but increased the exergy efficiency of the system without evaporator. With the evaporator, an optimal target concentration existed for the exergy efficiency owing to the influence of the target concentration on the balance between the energy consumption and saving brought by the evaporator. With black liquor condensed from 15 wt% to 21.82 wt%, maximum exergy efficiency of the system (41.95%) was obtained. For lower-concentration black liquor, more Water needs to be evaporated to get the optimal concentration and evaporator was more desired because it brought greater improvement on the exergy efficiency. The increasing effect number of multi-effect evaporator shifted the optimal concentration to higher values, which increased from 19.93 wt% to 23.13 wt% when the effect number increased from 4 to 7. The exergy efficiency of the system was also improved, and the improvement was more significant at higher target concentration.
-
system analysis of pulping process coupled with Supercritical Water Gasification of black liquor for combined hydrogen heat and power production
Energy, 2017Co-Authors: Liejin Guo, Hui Jin, Changqing Cao, Wen Cao, Yi Jia, Xiangdong YaoAbstract:Supercritical Water Gasification is an innovative black liquor treatment method for hydrogen production. In the present study, an integrated system of pulping and SCWG of black liquor was simulated. Combined hydrogen, power, MP and LP steam are produced for pulping process. The gas product after H2 extraction was burned with imported natural gas to supply more heat. For a reference pulp mill producing 1000 ADt pulp/day, potentially 37126 Nm3/h hydrogen can be produced. The generated MP and LP steam can fully meet the requirement of pulping process. Using air as oxidant in gas combustion is more energy-efficient than using oxygen for being free of oxygen production process. In the case of using air, 22604 kW power can be exported after balancing the consumptions and 219 kgce energy can be produced with 1t pulp production. While using oxygen, 10723 kW power needs be imported and 288 kgce energy can be consumed to produce 1t pulp. However, using air as oxidant may bring N2 and NOx in the exhaust gas, posing a challenge to the subsequent processing. Scaling-up of the system improved the energy efficiency, but the influence is very small when the capacity is above 250ADt/day.
-
Supercritical Water Gasification of coal with waste black liquor as inexpensive additives
Energy & Fuels, 2015Co-Authors: Liejin Guo, Hui Jin, Changqing Cao, Jiarong Yin, Wen Cao, Yi Jia, Xiangdong YaoAbstract:Black liquor is a major wasteWater generated from the pulping process that has a detrimental impact on the environment. This work assessed the potential of black liquor to be an inexpensive resource of alkali catalyst in Supercritical Water Gasification of coal through thermodynamic analysis and experimental study. The experiments were performed in a fluidized-bed reactor at 550 °C and 25 MPa, and the products were characterized by gas chromatography, X-ray fluorescence, X-ray diffraction, and gas chromatography-mass spectrometry. In the Gasification of coal and black liquor mixtures, the presence of coal can improve the H2 production under the equilibrium state. Both the inherent alkalis and lignin in black liquor played a role of improving the Gasification efficiency of coal. The alkalis also accelerated the Water–gas shift reaction and increased the H2 fraction. The high total mixture concentration inhibited the Gasification, and the reactor was plugged with a concentration of 25 wt %. The presence of ...
Cataldo De Blasio - One of the best experts on this subject based on the ideXlab platform.
-
techno economic feasibility of Supercritical Water Gasification of black liquor
Energy, 2019Co-Authors: Karhan Ozdenkci, Cataldo De Blasio, Jukka Koskinen, Golam Sarwar, Kristian Melin, Ville AlopaeusAbstract:Abstract The objective of this study is to investigate the techno-economic feasibility of Supercritical Water Gasification (SCWG) of black liquor integrated to a Kraft pulp mill. The process simulations have been performed through Aspen Plus software. The assessment includes five integration scenarios: stainless steel 316 or Inconel 625 as the reactor materials and hydrogen or combined heat and power (CHP) as the target products. The results illustrates that Inconel reactor is more profitable for CHP production than stainless steel as well as providing lower production cost of hydrogen. Inconel is also more robust against loss of pulping chemicals and changes in the energy price. However, the assessment uses the experimental yields even though surface-to-volume ratio of the reactor will reduce in the industrial scale. Therefore, the results should be validated in pilot scale as well before implementation. Nevertheless, a special reactor configuration can increase surface area. The techno-economic results can be improved by comprehensive investigations of process conditions including also residence time, the concentration of reactor inlet and heterogeneous catalyst. In addition, the SCWG process integrated to a pulp mill can also receive feedstocks from other biomass sectors. This would improve the economic and environmental performances of those sectors as well.
-
concerning operational aspects in Supercritical Water Gasification of kraft black liquor
Renewable Energy, 2019Co-Authors: Cataldo De Blasio, Massimo Santarelli, Sabino De Gisi, Antonio Molino, Marco Simonetti, Margareta BjorklundsankiahoAbstract:Abstract Kraft Black Liquor (KBL) is an aqueous solution of lignin residues, hemicelluloses and inorganic chemicals produced during the pulping process. It is sometimes classified as waste even if this definition is wrong in most of the cases where the BL is reutilized (recovered) by using it as fuel in recovery boilers. In this process, the pulping chemicals are recovered and sent again to the cooking process of wood. BL has more than half of the energy content of the inlet wood. KBL is generally used as an energy source although recovery boilers are still quite thermally inefficient compared to coal or gas fired power producing ones. Among the various solutions, Supercritical Water Gasification (SCWG) enables bio-fuels and value products to be obtained from KBL. The present study deals with the KBL SCWG by using a plug-flow reactor operating continuously at 250 bar pressure and variable temperatures in the range 500–700 °C. The objective was to identify the experimental conditions that lead to the development of operational problems and to document them accurately. In this study, real time visualization of online measurements has been conducted by means of the LabView software. In order to highlight the differences in behavior, tests were conducted on two different substrates, the sucrose and KBL. Results highlight how tests were carried out without problems at 500 °C resulting in a total gas yield of 18.31 g-mol/kgfeed, consisting mainly of H2 (7.87 g-mol/kgfeed), CO2 (5.84 g-mol/kgfeed), H2S (2.29 g-mol/kgfeed) and CH4 (1.96 g-mol/kgfeed). On the contrary, in the case of KBL SCWG the test was interrupted at 600 °C because of salt deposits and consequent clogging in the entrance of the reactor. The LabView software showed particularly rapid pressure drops which were not addressed to technical problems in the layout. However, the recording of the pressure drop was only the final symptom of this occurrence. The saline content in the investigated inlet KBL also suggested the need of a pre-treatment for the removal of the inlet salts in the case where a non-catalytic reactor would be used.
-
a study on Supercritical Water Gasification of black liquor conducted in stainless steel and nickel chromium molybdenum reactors
Journal of Chemical Technology & Biotechnology, 2016Co-Authors: Cataldo De Blasio, Gaetano Lucca, Karhan Ozdenkci, Michela Mulas, Kurt Lundqvist, Jukka Koskinen, Massimo Santarelli, Tapio WesterlundAbstract:BACKGROUND This study presents Supercritical Water Gasification (SCWG) as an alternative treatment process for black liquor: investigating the impacts of black liquor constituents, temperature and catalyst. The preliminary experiments include SCWG of sucrose and isoeugenol in stainless steel reactor, as model compounds of sugars and lignin. Then, the experiments of SCWG of black liquor are performed in stainless steel and INCONEL 625 reactors. RESULTS The results illustrated the impacts of temperature, black liquor constituents and nickel catalyst on the SCWG process. Temperature and the INCONEL reactor promoted Gasification efficiency and hot gas efficiency: over 80% hot gas efficiency was reached for black liquor in the INCONEL reactor at 700 °C. Experiments on model compounds have shown that sugars generate more carbon dioxide, while lignin generates more methane. Hydrogen fraction and yield increased with temperature; nevertheless, black liquor generated hydrogen-rich gas. The INCONEL reactor increased hot gas efficiency despite no significant impact on carbon Gasification efficiency: hydrogen is promoted dramatically. In addition, temperature and the INCONEL catalyst reduce tar and char formation as well. CONCLUSIONS Supercritical Water Gasification (SCWG) is potentially a suitable treatment for black liquor: it has no evaporation requirement and high hot gas efficiency. This process can be a solution for non-wood mills and can increase the product spectrum of Kraft mills by operating as a parallel treatment. On the other hand, sulphur balance is to be investigated for integration with Kraft mills together with a detailed feasibility study. © 2015 Society of Chemical Industry
Youjun Lu - One of the best experts on this subject based on the ideXlab platform.
-
hydrogen production from glycerol by Supercritical Water Gasification in a continuous flow tubular reactor
International Journal of Hydrogen Energy, 2012Co-Authors: Youjun Lu, Ximin ZhangAbstract:Abstract In this work, glycerol was used for hydrogen production by Supercritical Water Gasification. Experiments were conducted in a continuous flow tubular reactor at 445∼600 °C, 25 MPa, with a short residence time of 3.9∼9.0 s. The effects of reaction temperature, residence time, glycerol concentration and alkali catalysts on Gasification were systematically studied. The results showed that the Gasification efficiency increased sharply with increasing temperature above 487 °C. A short residence time of 7.0 s was enough for 10 wt% glycerol Gasification at 567 °C. With the increase of glycerol concentration from 10 to 50 wt%, the Gasification efficiency decreased from 88% to 71% at 567 °C. The alkali catalysts greatly enhanced Water-gas shift reaction and the hydrogen yield in relation to catalysts was in the following order: NaOH > Na 2 CO 3 >KOH > K 2 CO 3 . The hydrogen yield of 4.93 mol/mol was achieved at 526 °C with 0.1 wt% NaOH. No char or tar was observed in all experiments. The apparent activation energy and apparent pre-exponential factor for glycerol carbon Gasification were obtained by assuming pseudo first-order kinetics.
-
hydrogen production by Supercritical Water Gasification of biomass explore the way to maximum hydrogen yield and high carbon Gasification efficiency
International Journal of Hydrogen Energy, 2012Co-Authors: Youjun Lu, Ximin Zhang, Chengmeng JiAbstract:Abstract Supercritical Water Gasification (SCWG) is a promising technology for wet biomass utilization. In this paper, orthogonal experimental design method, which can minimize the number of experiments compared with the full factorial experiments, was used to optimize the operation parameters of SCWG with a tubular reactor system. Using this method, the influences of the main parameters including pressure, temperature, residence time and solution concentration on biomass Gasification were also investigated. Simultaneously, in order to further improve the Gasification efficiency of biomass, acid hydrolysis pretreatment of feedstock, oxidizers addition and increasing reaction temperature were employed. Results from the experiments show that in the range of experimental parameters, the order of the effects of the factors on H2 yield of corn cob Gasification in SCW is temperature > pressure > feedstock concentration > residence time. Temperature and pressure have a significant and complicated effect on biomass Gasification. Hydrogen yield increases by the acid hydrolysis pretreatment of feedstock, and oxidizer addition reduces the hydrogen yield but it promotes the increase in carbon Gasification efficiency. Biomass feedstock with high concentration was gasified successfully at high reaction temperature.
-
hydrogen production from Supercritical Water Gasification of alkaline wheat straw pulping black liquor in continuous flow system
International Journal of Hydrogen Energy, 2011Co-Authors: Yunan Chen, Youjun LuAbstract:Abstract Supercritical Water Gasification of alkaline black liquor was investigated in a continuous flow system. The experiments were carried out at 400–600 °C, 25 MPa, with residence times ranging from 4.94 to 13.71 s. The results showed that the increase of temperature and residence time and the decrease of feeding concentration enhanced the Gasification. The gaseous product contained high level of hydrogen (40.26–61.02%). Maximum COD removal efficiency (88.69%) was obtained at 600 °C. The alkalis in black liquor were found to be precipitated in the reactor during the Gasification, which decreased the pH of the effluent to the neutral region (6.4–8.0). The precipitated alkalis were dissolved in the Water when the fluid temperature in the reactor was cooled to about 360 °C which increased the pH of the effluent to 11.0. A simplified kinetic study for COD removal efficiency was done by the pseudo-first order reaction assumption. The apparent activated energy was 74.38 kJ/mol and the apparent pre-exponential factor was 10 4.05 s −1 .
Yukihiko Matsumura - One of the best experts on this subject based on the ideXlab platform.
-
reutilization of algal Supercritical Water Gasification waste for microalgae chlorella vulgaris cultivation
ACS omega, 2021Co-Authors: Puji Rahmawati Nurcahyani, Yukihiko MatsumuraAbstract:Effluents obtained through a Supercritical Water Gasification (SCWG) process at 400 and 600 °C were mixed with Bristol Medium to cultivate Chlorella vulgaris. Improvement of growth rate was observed only for the medium with the effluent at 600 °C. Low non-purgeable organic carbon implied that the inhibiting material was decomposed due to the high temperature of 600 °C. Thus, SCWG effluents might be more suitable for algae cultivation than hydrothermal liquefaction effluents. Phosphorus accumulation in C. vulgaris was improved in the SCWG mixed medium, irrespective of the treatment temperature. The media with SCWG effluents showed 2.5 times higher phosphorus accumulation in the algae, indicating the possibility of using a combination of C. vulgaris and SCWG for nutrient recycling processes.
-
Supercritical Water Gasification of guaiacol with acetic acid as a radical scavenger interaction effect on char formation and gas composition
ACS omega, 2020Co-Authors: Pattraporn Changsuwan, Shuhei Inoue, Yukihiko MatsumuraAbstract:Supercritical Water Gasification (SCWG) of mixtures of guaiacol and acetic acid was carried out in a continuous reactor at 600 °C and 25 MPa with a residence time of 94 s. Different concentrations of acetic acid were employed to investigate the effect of acetic acid on product yield and gas composition. The interaction between guaiacol and acetic acid during SCWG was discussed. Acetic acid, as a radical scavenger, was found to inhibit radical polymerization, resulting in the suppression of char formation.
-
Supercritical Water Gasification of sewage sludge in continuous reactor.
Bioresource technology, 2017Co-Authors: Apip Amrullah, Yukihiko MatsumuraAbstract:Abstract In this study, a process for the continuous recovery of phosphorus and generation of gas from sewage sludge is investigated for the first time using Supercritical Water Gasification (SCWG). A continuous reactor was employed and experiments were conducted by varying the temperature (500–600 °C) and residence time (5–60 s) while fixing the pressure at 25 MPa. The behavior of phosphorus during the SCWG process was studied. The effect of the temperature and time on the composition of the product gas was also investigated. A model of the reaction kinetics for the SCWG of sewage sludge was developed. The organic phosphorus (OP) was rapidly converted into inorganic phosphorus (IP) within a short residence time of 10 s. The gaseous products were mainly composed of H2, CO2, and CH4. The reaction followed first order kinetics, and the model was found to fit the experimental data well.
-
effect of the heating rate on the Supercritical Water Gasification of a glucose guaiacol mixture
Industrial & Engineering Chemistry Research, 2017Co-Authors: Obie Farobie, Shuhei Inoue, Takahito Inoue, Yoshifumi Kawai, Takashi Noguchi, Poomkawee Changkiendee, Hiroaki Tanigawa, Yukihiko MatsumuraAbstract:We herein report the effect of the feedstock heating rate on the Supercritical Water Gasification of a glucose/guaiacol mixture. In the study, glucose was employed as a model compound for cellulose and guaiacol was employed as a model compound for lignin. A mixture of glucose (0.34 wt %) and guaiacol (0.16 wt %) was fed into a laboratory-scale continuous reactor at 600 °C and 25 MPa through a preheater, where the feedstock heating rate could be controlled. Feedstock flow rates of 1 and 2 g/min were employed along with preheaters of three different lengths (i.e., 0.45, 0.9, and 1.8 m). We found that longer preheaters resulted in slower heating rates at the same feedstock flow rate. Studies into the effect of the feedstock heating rate on the Gasification efficiency indicated that a high heating rate enhanced the carbon Gasification efficiency even for a glucose/guaiacol mixture. However, when the heating rate reached ∼25 K/s, a decrease in the carbon Gasification efficiency was observed. This may be due to...
-
inhibition of char deposition using a particle bed in heating section of Supercritical Water Gasification
Korean Journal of Chemical Engineering, 2016Co-Authors: Soichi Hirota, Shuhei Inoue, Takahito Inoue, Yoshifumi Kawai, Yasutaka Wada, Takashi Noguchi, Yukihiko MatsumuraAbstract:Supercritical Water Gasification (SCWG) has attracted attention as a technology for utilizing wet biomass. We used a fluidized bed of alumina particles to prevent blockage of a SCWG reactor. A glucose solution was heated in the reactor with and without fluidized alumina particles. In the absence of alumina particles, char particles formed homogeneously in the reactor, but the use of a fluidized bed resulted in accumulation of char particles at the reactor’s exit rather than inside the reactor. Therefore, the fluidized bed was effective at preventing blockage of the reactor. However, the alumina particles did not remove deposits from the reactor’s walls. Instead, the fluidized bed caused larger char particles to form, preventing their adhesion to the reactor’s wall.
Changqing Cao - One of the best experts on this subject based on the ideXlab platform.
-
hydrogen production from Supercritical Water Gasification of soda black liquor with various metal oxides
Renewable Energy, 2020Co-Authors: Changqing Cao, Yupeng Xie, Liuhao Mao, Wenwen Wei, Jinwen Shi, Hui JinAbstract:Abstract Supercritical Water Gasification is an innovative handling method of black liquor, which can also produce hydrogen-rich gases. In this study, the catalytic activity of 14 common metal oxides on SCWG of black liquor were investigated and the catalytic mechanism was studied through X-ray photoelectron spectroscopy (XPS) analysis. All the tested oxides improved the Gasification efficiency and V2O5, WO3 and Co2O3 showed the highest performance. The H2 yields of 21.67 and 21.03 mol/kg were achieved with the presence of Co2O3 and ZnO respectively. The Gasification efficiency increased with the increasing V2O5 amount, but the H2 fraction increased firstly and then decreased. The highest H2 fraction of 44.59% was obtained with V2O5 loading amount of 45 wt%. The increase of reaction time improved the CE, but the further prolongation had little influence. The XPS analysis of CuO and Fe2O3 showed some of them were reduced to metal (Cu) or lower-valence oxides (Cu2O, FeO). The metal oxides probably promoted black liquor decomposition by introducing reactive oxygen, and the generated metal also catalyzed the Gasification. Accordingly, an oxidation reactor could be introduced to recycle the metal oxides, which may help to realize the complete Gasification of black liquor or other refractory wastes at milder temperatures.
-
Supercritical Water Gasification of black liquor with wheat straw as the supplementary energy resource
International Journal of Hydrogen Energy, 2019Co-Authors: Changqing Cao, Wenwen Wei, Yi Zhang, Gaoyun Wang, Ce BianAbstract:Abstract Supercritical Water Gasification (SCWG) is a new treatment of black liquor (BL) for both energy recovery and pollution management. To provide more energy for the pulp mill, it is proposed to use the pulping raw material as supplementary energy source because it is readily available, inexpensive and renewable. In this study, co-Gasification of BL and wheat straw (WS) in Supercritical Water was investigated. The synergistic effect was observed in the co-Gasification because the addition of wheat straw can make better use of the alkali in BL. The maximum improvement of the Gasification by the synergistic effect was obtained with the mixing ratio of 1:1. The influences of the temperature (500–750 °C), reaction time (5–40 min), mixture concentration (5.0–19.1 wt%), mixing ratio (0–100%) and the wheat straw particle diameter (74–150 μm) were studied. It was found that the increase of temperature and reaction time, and the decrease of concentration and wheat straw particle size favored the Gasification by improving the hydrogen production and Gasification efficiency. The highest carbon Gasification efficiency of 97.87% was obtained at 750 °C. Meanwhile, the H2 yield increased from 12.29 mol/kg at 500 °C to 46.02 mol/kg. This study can help to develop a distributed energy system based on SCWG of BL and raw biomass to supply energy for the pulp mill and surrounding communities.
-
evaluation of effect of evaporation on Supercritical Water Gasification of black liquor by energy and exergy analysis
International Journal of Hydrogen Energy, 2017Co-Authors: Changqing Cao, Jia Chen, Wen Cao, Hui JinAbstract:Abstract Supercritical Water Gasification (SCWG) is a promising innovative black liquor handling method. The low concentration of black liquor is a burden for the system scale and investment cost. In this study, we introduced black liquor evaporator to increase the concentration using self-generated steam and power, and studied its influence on the energy and exergy efficiency. The results showed that increasing black liquor concentration from 10 wt% to 20 wt% reduced the energy efficiency but increased the exergy efficiency of the system without evaporator. With the evaporator, an optimal target concentration existed for the exergy efficiency owing to the influence of the target concentration on the balance between the energy consumption and saving brought by the evaporator. With black liquor condensed from 15 wt% to 21.82 wt%, maximum exergy efficiency of the system (41.95%) was obtained. For lower-concentration black liquor, more Water needs to be evaporated to get the optimal concentration and evaporator was more desired because it brought greater improvement on the exergy efficiency. The increasing effect number of multi-effect evaporator shifted the optimal concentration to higher values, which increased from 19.93 wt% to 23.13 wt% when the effect number increased from 4 to 7. The exergy efficiency of the system was also improved, and the improvement was more significant at higher target concentration.
-
system analysis of pulping process coupled with Supercritical Water Gasification of black liquor for combined hydrogen heat and power production
Energy, 2017Co-Authors: Liejin Guo, Hui Jin, Changqing Cao, Wen Cao, Yi Jia, Xiangdong YaoAbstract:Supercritical Water Gasification is an innovative black liquor treatment method for hydrogen production. In the present study, an integrated system of pulping and SCWG of black liquor was simulated. Combined hydrogen, power, MP and LP steam are produced for pulping process. The gas product after H2 extraction was burned with imported natural gas to supply more heat. For a reference pulp mill producing 1000 ADt pulp/day, potentially 37126 Nm3/h hydrogen can be produced. The generated MP and LP steam can fully meet the requirement of pulping process. Using air as oxidant in gas combustion is more energy-efficient than using oxygen for being free of oxygen production process. In the case of using air, 22604 kW power can be exported after balancing the consumptions and 219 kgce energy can be produced with 1t pulp production. While using oxygen, 10723 kW power needs be imported and 288 kgce energy can be consumed to produce 1t pulp. However, using air as oxidant may bring N2 and NOx in the exhaust gas, posing a challenge to the subsequent processing. Scaling-up of the system improved the energy efficiency, but the influence is very small when the capacity is above 250ADt/day.
-
Supercritical Water Gasification of coal with waste black liquor as inexpensive additives
Energy & Fuels, 2015Co-Authors: Liejin Guo, Hui Jin, Changqing Cao, Jiarong Yin, Wen Cao, Yi Jia, Xiangdong YaoAbstract:Black liquor is a major wasteWater generated from the pulping process that has a detrimental impact on the environment. This work assessed the potential of black liquor to be an inexpensive resource of alkali catalyst in Supercritical Water Gasification of coal through thermodynamic analysis and experimental study. The experiments were performed in a fluidized-bed reactor at 550 °C and 25 MPa, and the products were characterized by gas chromatography, X-ray fluorescence, X-ray diffraction, and gas chromatography-mass spectrometry. In the Gasification of coal and black liquor mixtures, the presence of coal can improve the H2 production under the equilibrium state. Both the inherent alkalis and lignin in black liquor played a role of improving the Gasification efficiency of coal. The alkalis also accelerated the Water–gas shift reaction and increased the H2 fraction. The high total mixture concentration inhibited the Gasification, and the reactor was plugged with a concentration of 25 wt %. The presence of ...