scholarly journals Thermodynamics simulation performance of rice husk combustion with a realistic decomposition approach on the devolatilization stage

Author(s):  
Soen Steven ◽  
Pandit Hernowo ◽  
Elvi Restiawaty ◽  
Anton Irawan ◽  
Carolus Borromeus Rasrendra ◽  
...  

Abstract Rice husk has a great potential in its calorific value and silica content in ash which makes its valorization through combustion becomes important and interesting. This study presents the thermodynamics simulation performance of rice husk combustion using a realistic decomposition approach. A non-ideal gas approach and fugacity coefficient were also considered in the calculation. From this study, rice husk is devolatilized to form gases (63.37%), tar (8.69%), char (27.94%), and all of these are then oxidized to form flue gas. The realistic decomposition approach calculated that about 2.6 MJ/kg of specific combustion energy is produced, the maximum combustion temperature is up to 1457oC for perfect insulation condition, and up to 1400oC if there is a heat loss. It is found that combustion equipped with larger excess air could quench the heat produced and reduce the combustion efficiency but could maintain the temperature at 700oC. Furthermore, the thermodynamics simulation expressed that NO emission amount from rice husk combustion is negligible and there is still a probability for CO and H2 to be produced at above 500oC due to Boudouard reaction and homogeneous water gas shift reaction (WGSR). The study showed that a realistic decomposition approach could predict the rice husk combustion performance with a reasonable and logical result. Supplying excess air of about 180–200% is advantageous to keep the combustion temperature at 700oC in order to prevent silica crystalline formation which harms human health, as well as suppressing NO emission and reducing CO emission from the simultaneous Boudouard and WGSR.

Author(s):  
Soen Steven ◽  
Pandit Hernowo ◽  
Elvi Restiawaty ◽  
Anton Irawan ◽  
Carolus Borromeus Rasrendra ◽  
...  

2020 ◽  
Vol 04 ◽  
Author(s):  
Guohai Jia ◽  
Lijun Li ◽  
Li Dai ◽  
Zicheng Gao ◽  
Jiping Li

Background: A biomass pellet rotary burner was chosen as the research object in order to study the influence of excess air coefficient on the combustion efficiency. The finite element simulation model of biomass rotary burner was established. Methods: The computational fluid dynamics software was applied to simulate the combustion characteristics of biomass rotary burner in steady condition and the effects of excess air ratio on pressure field, velocity field and temperature field was analyzed. Results: The results show that the flow velocity inside the burner gradually increases with the increase of inlet velocity and the maximum combustion temperature is also appeared in the middle part of the combustion chamber. Conclusion: When the excess air coefficient is 1.0 with the secondary air outlet velocity of 4.16 m/s, the maximum temperature of the rotary combustion chamber is 2730K with the secondary air outlet velocity of 6.66 m/s. When the excess air ratio is 1.6, the maximum temperature of the rotary combustion chamber is 2410K. When the air ratio is 2.4, the maximum temperature of the rotary combustion chamber is 2340K with the secondary air outlet velocity of 9.99 m/s. The best excess air coefficient is 1.0. The experimental value of combustion temperature of biomass rotary burner is in good agreement with the simulation results.


Author(s):  
Christopher Y. H. Chao ◽  
Philip C. W. Kwong ◽  
J. H. Wang

In many Asian countries Coal is frequently used a major fuel in power plants. Burning coal creates quite a lot of environmental problems when compared to other cleaner fuels such as natural gas. Experimental study of co-combustion of coal and biomass was conducted in a laboratory scale combustion facility to evaluate the combustion and pollutant emission performance under different operation parameters. Rice husk and bamboo were used as the biomass fuels in this study. This paper reported the influence of the biomass blending ratio in the fuel mixture and the excess air ratio on the combustion behavior. It was noted that the combustion temperature and the energy output from the co-firing process were reduced compared to coal combustion alone owing to the fact that biomass has lower heating value compared to coal. However, the high volatile matter (VM) content of biomass improved the combustion time scale so that the carbon monoxide (CO) emissions were reduced substantially. In addition, the fuel nitrogen and sulfur content in biomass were lower than that of coal and hence suppressed the formation of nitrogen oxides (NOx) and sulfur dioxide (SO2) during the cocombustion process. The increase of excess air ratio also affected most of the pollutant emissions. The pollutant emission per unit energy output at different excess air ratios and biomass blending ratios were studied in detail in this paper. Attention should be paid to the high potential of slagging and fouling in the boiler when co-firing coal with biomass.


2019 ◽  
Vol 947 ◽  
pp. 195-199
Author(s):  
Zainathul Akhmar Salim Abdul Salim ◽  
Aziz Hassan ◽  
Hanafi Ismail ◽  
Nor Hafizah Che Ismail

This study highlighted the effect of incorporation of rice husk silica (RHS) on the tensile properties and dynamic mechanical behaviour of natural rubber (NR) compounds. High purity RHS was synthesised by solvent-thermal extraction method, which was inspired by TAPPI T204 cm-97 and TAPPI T264 cm-97 standards with some modifications. The extraction method had successfully produced RHS with 99.9% of silica content and surface area of 234.25 m2/g. The incorporation of RHS in NR showed increment in tensile properties compared to unfilled NR. Further improvement was recorded by surface modification of RHS with 1 wt. % bis (triethoxysilylpropyl) tetrasulfide (TESPT). The modification of RHS with TESPT increased the rubber-filler interaction between RHS and NR matrix, hence enhancing the strength-related properties. The modified RHS-NR also recorded highest storage modulus, and the presence of RHS in the NR compound had slightly shifted the glass transition temperature (Tg) to a higher value. This confirmed that the strong rubber-filler interaction had increased the rigidity of the compounds and restricted the mobility of the rubber chains.


Tibuana ◽  
2020 ◽  
Vol 3 (01) ◽  
pp. 47-52
Author(s):  
Yanatra budi Pramana ◽  
M. Amin Pahlevi ◽  
Zhulianto Ashari ◽  
M. Fariz Effendi ◽  
Fibra Gilang Ramadhan

Utilization of rice husks in Indonesia in general is still very limited. Utilization of silica contained in rice husk ash, which has been used, among others, in the manufacture of sodium silicate. Silica compounds themselves can be used in and manufacturing basic materials for electronic and ceramic equipment, glass, rubber, cosmetic products, and pharmaceuticals. The addition of Mg can increase the silica content (SiO2) in rice husk ash. The best results show an effective Mg ratio of Mg addition to increase silica content is 1: 1. produces the highest amount of silica which is 58.12% of the rice husk ash with a size of 140 mesh


Author(s):  
Kerich K. Daniel ◽  
Zachary O. Siagi ◽  
Julius O. Ogola

Aims: This study investigated the use of agro-wastes for the production of briquettes. It was carried out to investigate the effect of formulation, binder and compaction pressure of rice husk-Bagasse briquettes on thermal and physical properties. Study Design: The experimental design for this study was 6x5x2 Randomized Complete Block Design Place and Duration of the Study: Rice husks and bagasse were collected from Lake Basin Development Authority’s rice mill and Kibos sugar and Allied company respectively. The binders were sourced locally in Kisumu. The study was conducted between March 2019 and February 2020. The fabrication and laboratory analysis were carried out in the engineering and laboratory departments of Kenya Industrial Research and Development institute, Kisumu. Methodology: The experimental design for this study was 6x5x2 Randomized Complete Block Design. This study involved six formulations ratios (0:100, 20:80, 40:60, 60:40, 80:20, 100:0), five compaction pressure levels (108kPa, 180kPa, 253kPa, 325kPa, 397kPa) and two binders (clay, cassava) They were arranged in Randomize Complete Block Design with three replications per experiment. Results: The briquettes bulk density was in the range of 849 to 1001 kg.m−3, while the calorific value ranged from 5.541 kcal/g for 100% Rice husk clay binder to 7.345 kcal/g 20% Rice Husk cassava binder. Briquettes with blend ratio of 40-60% Rice Husk took longer time to burn. Briquette formulations with clay binder had burning rates ranging from 0.28 g/min to 0.15 g/min while with cassava binder from 0.52 g/min to 0.37 g/min. The ignition time of the briquettes ranged from 62 sec to 95 sec with cassava binder and 110 sec to 191sec with clay binder. The shatter index ranged from 0.94 to 0.99 with cassava and 0.9 to 0.98 with clay binder. Conclusion: Higher compaction pressures and use of cassava binder produced stronger briquettes with higher calorific values. Briquettes with higher percentage of bagasse had low ignition time and low bulk densities. The bulk densities and ignition time showed significant rise with increase in the compaction pressure but inversely affected the burning rate. The binder used significantly affected both the thermal and physical properties of all the formulations.


2016 ◽  
Vol 11 (2) ◽  
pp. 93 ◽  
Author(s):  
Nijhuma Kayal ◽  
Nahar Singh

<p>The objective of the work was to develop pure silica with high surface area from rice husk by chemical and heat treatment. The silica samples were characterized in terms of chemical composition, particle size distribution, morphology and surface area. The amount of silica was determined by a modified volumetric method. The trace impurities in silica were quantitatively determined by inductive coupled plasma atomic emission spectroscopy (ICP-AES). A 99% silica powder with surface area 282 m<sup>2</sup>/gm could be produced by chemical and heat treatment at 1000 ºC for 2 h.</p>


2021 ◽  
Author(s):  
V. Pranay ◽  
S. Ojha ◽  
Raghavendra G ◽  
G. Dheeraj ◽  
A. Anjali

Abstract This paper reports the mechanical-erosion wear properties of extracted silica from Biowaste (rice husk) and pure rice husk-filled epoxy composites. A comparison is made on the influence of dispersed silica and rice husk particles on the properties of the epoxy composites. The composites are fabricated by hand lay-up process. The specimens are tested as per the ASTM standards for three different filler loadings of each silica and rice husk separately (2,4 and 6wt%). It is perceived that with the increase in the rice husk filler loading in epoxy, there is a decline in tensile, flexural, and erosion wear properties. It is also evident that, with the increase in silica content until 6%, the tensile and flexural strength have displayed consistent enhancement. Alongside, erosion results confirm that the properties of the pure epoxy had exhibited transition from semi-brittle to ductile nature due to the addition of silica fillers.


2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Eryani . ◽  
Sri Aprilia ◽  
Farid Mulana

<p>Agricultural waste such as rice straw, rice husk and rice husk ash have not been utilized properly. This waste of agricultural produce can actually be used as an alternative to bionanofiller because it contains an excellent source of silica. The silica content contained in the rice waste when combined with the polymer matrix can produce composites having high thermal and mechanical properties. Characterization of bionanofiller from this rice waste is done by SEM, XRF, FTIR, XRD and particle density. The result of SEM analysis from this rice waste is feasible to be used as filler because it has size 1 μm. Likewise with the results of XRF analysis that rice waste contains a high enough silica component that is 80.6255% - 89.83%. FTIR test results also show that bionanoparticles from rice waste have the same content of silica. In the XRD analysis the best selective gain of rice waste is found in rice husk ash which is characteristic of amorp silica at a range of 2ϴ = 22<br />. The largest density analysis of paddy waste was found in rice husk 0.0419 gr / cm , followed by rice straw by of 0.0417 gr / cm 3 and rice hulk ash 0.0407 g / cm 3</p>


2019 ◽  
Vol 22 (6) ◽  
pp. 220-226 ◽  
Author(s):  
Emil Zacky Effendi ◽  
Yudhi Christian Hariady ◽  
Muhammad Daffa Salaahuddin ◽  
Chairul Irawan ◽  
Iryanti Fatyasari Nata

Rice husk (RH) is an agricultural waste that contains cellulose. Rice husk fiber (RHF) can be used as a source of fiber in the manufacture of magnetic nanoparticle biocomposite. The purpose of this study is to synthesize and characterize magnetic nanoparticle biocomposite used as an adsorbent and evaluate its performance on the adsorption of  Mn2+ ions and Total Suspended Solid (TSS) in peat water. Rice husk fiber was delignified to eliminate lignin levels. Furthermore, the biocomposite was made through the solvothermal method with and without the addition of hexanediamine. The products produced are two types of adsorbents, namely magnetic nanoparticle biocomposite with an amino group (RHB-MH) and rice husk fiber biocomposite without an amino group (RHB-M). These biocomposites were used to adsorb Mn2+ ions in peat water. Evaluations were carried out at pH 5, 6, 7, and 8 with an optimum adsorption time of 60 minutes. The solutions at the time of adsorption were evaluated to determine the optimum conditions of the adsorption process carried out. The observation of magnetic nanoparticle biocomposite based on the analysis of Scanning Electron Microscopy (SEM) shows magnetic nanoparticles formed on the surface of rice husk fiber with a diameter of 30-50 nm. X-Ray Diffraction (XRD) analysis showed that the delignification of rice husk increased Crystallinity Index (CrI) by 64.98% and reduced silica content by 78%. Fourier Transform Infra-Red (FT-IR) spectrometer show absorption peak at 570 cm-1 for Fe-O bonds and Fe3O4 peak around 1627 cm−1, indicating the presence of N-H bending. The optimum condition for Mn2+ adsorption was achieved at pH 5 and 60-minutes duration with an adsorption capacity of 54.7 mg/g and 190.78 mg/g for RHB-M and RHB-MH. The TSS reduction achieved the effectiveness of 60.2% and 90.3% for BSP-M and BSP-MH, respectively.


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