Rice Husk Gasification Research Articles

Tar removal capacity of waste cooking oil absorption and waste char adsorption for rice husk gasification

ABSTRACTTar removal by oil absorber and char adsorber known as the physical method is a promising technology for cleaning synthesis gas from biomass gasification offering high tar removal efficiency, low cost, uncomplicated operation and waste-free facility. However, it is essential to maintain tar removal efficiency to a satisfying level in order to prevent downstream application breakdown. Therefore, periodic changing of absorbent and adsorbent are highly required. In this paper, the tar removal capacity of waste cooking oil (WCO) and waste char (WC) is investigated to maximize waste utilization for gas cleaning pre-treatment systems. For WCO, the gravimetric tar removal reached the breakthrough point in the second hour and the capacity was 14.4 g-tar/L-WCO (80.6% and 94.6% of gravimetric tar and naphthalene removal performance on average). For WC, the breakthrough point was in the second hour for naphthalene removal and the capacity was 0.15 mg-naphthalene/g-waste char (76% of naphthalene removal performance) while it could also adsorb heavy tar with the capacity of 48.8 mg-tar/g-waste char. This increased the gravimetric tar removal efficiency by 3.1% when connecting the WC bed after the WCO scrubber.

Prediction of Rice Husk Gasification on Fluidized Bed Gasifier Based on Aspen Plus

A biomass gasification model was developed using Aspen Plus based on the Gibbs free energy minimization method. This model aims to predict and analyze the biomass gasification process using the blocks of the RGibbs reactor and the RYield reactor. The model was modified by the incomplete equilibrium of the RGibbs reactor to match the real processes that take place in a rice husk gasifier. The model was verified and validated, and the effects of gasification temperature, gasification pressure, and equivalence ratio (ER) on the gas component composition, gas yield, and gasification efficiency were studied on the basis of the Aspen Plus simulation. An increasing gasification temperature was shown to be conducive to the concentrations of H2 and CO, and gas yield and gasification efficiency reached peaks of 2.09 m3/kg and 83.56%, respectively, at 700 °C. Pressurized conditions were conducive to the formation of CH4 and rapidly increased the calorific value of syngas as the gasification pressure increased from 0.1 to 5 MPa. In addition, the optimal ER for gasification is approximately 0.3, when the concentrations of H2 and CO and the gasification efficiency reach peaks of 23.65%, 24.93% and 85.92%, respectively.

KINERJA PEMBANGKIT LISTRIK DUAL-FUEL KAPASITAS 5 kW BERBASIS GASIFIKASI SEKAM PADI BERUNGGUN TETAP

<p>Abstract: Producer gas from rice husk gasification is the potential gaseous fuel for partially<br />substituting diesel fuel demand as it contains combustible gases (CO, H<br />2<br />). This<br />research examined the effects of air flow rate entering the diesel engine and electrical load on<br />diesel fuel consumption, electrical power of generator, and rice husk specific consumption in<br />gasifier. Gasification process took place in a downdraft air-blown gasifier with 10 cm throat<br />diameter. At rice husk consumption rate of 1 kg/hour and temperature of 827<br />C, the Specific<br />Gasification Rate (SGR) was 81.53 kg/(m<br />.hour) and the solid residue was 36% (w/w) of input<br />biomass. Total combustible gas content in producer gas was 21.6%. It was observed that diesel<br />fuel saving of 9.32% was obtained at air flow rate of 1.55 × 10<br />2<br />-3<br />m<br />/s and electrical load of 95%<br />from maximum generator power. Using producer gas at flow rate of 0.91 × 10<br />3<br />/s caused<br />generator de-rating of 8.33% at electrical load of 10%. Generating 1 kWh of electricity at air flow<br />rate of 2.99 × 10<br />-3<br />m<br />/s and electrical load of 95% required 1.85 kg of rice husk. A kilogram of<br />rice husk may substitute 0.26 L of diesel fuel at this air flow rate and load.<br />3<br />Keywords: rice husk; gasification; dual-fuel; specific consumption; de-rating<br />, and CH<br />4<br />o<br />-3<br />m<br />3</p>

CO-GASIFICATION OF COAL AND BIOMASS – THERMODYNAMIC AND EXPERIMENTAL STUDY

Cogasification of coal and biomass is a new area of research. Cogasification offers several advantages than individual feed gasification. A thermodynamic analysis of lignite coal and rice husk cogasification using only steam was studied by using HSC chemistry software in this paper involving the effect of temperature 500-1200°C and GaCR ratio(1-3) on the product gas composition. The study also focused on calculation of thermoneutral conditions and hundred percent carbon conversion temperature in cogasification of lignite coal and rice husk. Experimental study of co gasification of rice husk and coal was also done at fixed steam to carbon ratio. The experimental study was found to be more kinetically controlled. Keyword: cogasification, rice husk, lignite coal, HSC chemistry software, fixed bed.

Gasification of Rice Husk in a Downdraft Gasifier: The Effect of Equivalence Ratio on the Gasification Performance, Properties, and Utilization Analysis of Byproducts of Char and Tar

Rice husks (RH) are a potential biomass source for bio-energy production in China, such as bio-gas production by gasification technology. In this paper, a bench-scale downdraft fixed bed gasifier (DFBG) and a tar sampling system were designed. The effect of equivalence ratio (ER) on gasification performance in terms of the temperature in the gasifier, the composition distribution of the producer gas, and the tar content in the producer gas was studied. The maximum lower heating value of 4.44 MJ/Nm3, minimum tar content of 1.34 g/Nm3, and maximum cold gas efficiency of 50.85% were obtained at ER of 0.211. In addition, the characteristics of gasification byproducts, namely bio-char and bio-tar, were analyzed. The proximate and ultimate analysis (especially of the alkali metal), the surface morphology, the surface area, and the pore size distribution of the rice husk char (RHC) were obtained by the use of X-ray fluorescence (XRF) and scanning electron microscopy (SEM), as well as by using the Brunauer-Emmett-Teller (BET) method. The components of light tar and heavy tar were obtained by using gas chromatography-mass spectrometry (GC-MS).

Effect of rice husk gasification residue application on herbicide behavior in micro paddy lysimeter.

Effects of rice husk gasification residues (RHGR) application on the fate of herbicides, butachlor and pyrazosulfuron-ethyl, in paddy water were investigated using micro paddy lysimeters (MPLs). The dissipation of both herbicides in paddy water was faster in the RHGR treated MPL than in the control MPL. The average concentrations of butachlor and pyrazosulfuron-ethyl in paddy water in the lysimeter treated with RHGR during 21 days were significantly reduced by 51% and 48%, respectively, as compared to those in the lysimeter without RHGR application. The half-lives (DT50) of butachlor in paddy water for control and treatment were 3.1 and 2.3 days respectively, and these values of pyrazosulfuron-ethyl were 3.0 and 2.2 days, respectively. Based on this study, RHGR application in rice paddy environment is an alternative method to reduce the concentration of herbicide in paddy field water and consequently to reduce potential pollution to aquatic environment.

Energy and exergy analyses of syngas produced from rice husk gasification in an entrained flow reactor

Energy and exergy can be used to evaluate energy sources. The detailed energy and exergy of syngas produced from rice husk gasification in an entrained flow reactor were investigated at various reactor temperatures and equivalence ratios. The results showed that the exergy values of syngas were lower than their energy values and they followed well with the energy values. However, the detailed energy and exergy distributions of syngas were different at various reactor temperatures and equivalence ratios. This indicates that the contributions of gas components to the energy and exergy of syngas are different from gas to gas. Energy and exergy analyses therefore should be conducted appropriately according to evaluation purposes. The results also showed that the highest energy and exergy of syngas were achieved about 10,062 and 7990 kJ per kg of fuel at the reactor temperature of 1000 °C and equivalence ratio of 0.25, respectively. The results obtained from this study can help understand the energy and exergy of syngas produced from biomass gasification as well as thermochemical conversion processes of biomass fuels.

Catalyst and process parameters for the gasification of rice husk with pure CO2 to produce CO

A process for preparing CO with CO2 as gasification agent and rice husk as raw material in the presence of metal oxide catalyst was reported in this paper. Five kinds of catalysts (Fe2O3, CoO, NiO, CuO, and ZnO) supported on γ-Al2O3 were compared in the catalytic gasification, and the effects of reaction temperature, system pressure, catalyst loading, space velocity, and rice husk particle size were also studied. The results show that ZnO/γ-Al2O3 obtained at a calcination temperature of 650°C exhibits the highest activity. The optimal conditions are: 800°C, 0.1MPa, ZnO loading of 7.5%, space velocity of 240h−1, and rice husk particle size of 0.20–0.30mm. Under such conditions, 22.1% of CO content, 22.4% of CO2 conversion, and 71.7% of rice husk conversion are obtained.

Designing and Performance Evaluation of Biochar Production in a Top-Lit Updraft Up-scaled Gasifier

The Original Belonio Rice Husk Gasifier (OBRHG), initially of height of 0.6 m, diameter of 0.15 m and thickness of 0.025 m was tested for biochar production through air gasification of rice husk (RH) and the design was upscaled to height of 1.65 m, diameter of 0.85 m and thickness of 0.16 m. A total of 27 experiments were conducted to monitor the gasifier performance and the system can operate with the centrifugal blower operating at a power input of 155 W and a maximum flow rate of 1450 m3/hr regulated according to the air requirement. Building the UBRHG is simple and inexpensive to fabricate and with the fairly satisfactory performance and ease of construction along with the convenience of operation, the UBRHG with RH as feed would find abundant avenues of applications in a rural setting for biochar production alongside thermal, mechanical and electrical energy delivery.

Hydrogen-rich gas production via CaO sorption-enhanced steam gasification of rice husk: a modelling study

Gasification is a thermochemical process in which solid or liquid fuels are transformed into synthesis gas through partial oxidation. In this paper, a kinetic model of rice husk gasification has been developed, which is interesting for the applications of the syngas produced. It is a zero-dimensional, steady-state model based on global reaction kinetic, empirical correlation of pyrolysis and is capable of predicting hydrogen yield in the presence of sorbent CaO. The model can also be used as a useful tool to investigate the influence of process parameters including steam/biomass ratio, CaO/fuel ratio (CaO/Fuel), and gasification temperature on hydrogen efficiency, CO2 capture ratio (CCR), and average carbonation conversion (Save). Similar to hydrogen formation, CCR also increases with increasing CaO/Fuel, but an opposite trend is exhibited in Save. Model predictions were compared with available data from the literature, which showed fairly good agreement.

Air gasification of rice husk in bubbling fluidized bed reactor with bed heating by conventional charcoal

An experimental study of air gasification of rice husk was conducted in a bench-scale fluidized bed gasifier (FBG) having 210mm diameter and 1600mm height. Heating of sand bed material was performed using conventional charcoal fuel. Different operating conditions like bed temperature, feeding rate and equivalence ratio (ER) varied in the range of 750–850°C, 25–31.3kg/h, and 0.3–0.38, respectively. Flow rate of air was kept constant (37m3/h) during FBG experiments. The carbon conversion efficiencies (CCE), cold gas efficiency, and thermal efficiency were evaluated, where maximum CCE was found as 91%. By increasing ER, the carbon conversion efficiency was decreased. Drastic reduction in electric consumption for initial heating of gasifier bed with charcoal compared to ceramic heater was ∼45%. Hence rice husk is found as a potential candidate to use directly (without any processing) in FBG as an alternative renewable energy source from agricultural field.

Utilization of Fire Dynamics Simulator Model to Study Rice Husk Gasification in Fixed-bed Gasifier

Computational Fluid Dynamic (CFD) modeling applications of the biomass gasification process help to optimize the gasifier. This study aims to investigate the impact of several physical parameters on the behavior of gasification in a fixed-bed downdraft gasifier. To that end, the study presents a comparison of the results computed using the Fire Dynamics Simulator (FDS) model with experimental results of biomass gasification. Therefore, different sets of simulations and experiments have been performed to examine the effects of initial moisture content, equivalence ratio, high heating value (HHV), and cold gas efficiency (CGE). At the optimum operation, the equivalence rate is 0.3, the HHV can reach 5.71 MJ/m3, and the produced hydrogen concentration is 26.53 vol%. For an initial moisture content of 11.18%, the measured CGE is 66.85%, which is within the range of 65.07% to 70.44%. In general, the initial moisture content of the rice husks is suggested to be below 18%. The overall results indicate that the FDS model can effectively simulate and analyze gasification performance inside the gasifier, and the performance of an improved downdraft gasifier system (IDGS) is improved by higher cold gas efficiency.

Study of Combined Rice Husk Gasifier Thermoelectric Generator

The use of a rice husk gasifier as a cook stove is limited to the domestic sector of developing countries primarily because it needs electrical energy to drive a blower for the gasification process. To solve this problem, we investigated the feasibility of attaching commercial thermoelectric (TE) modules made of bismuth–telluride materials to the gasifier's side wall, thereby creating a TE generator system that utilizes a proportion of the gasifier's waste heat. A rice husk gasifier TE generator (TE-RSG) having an internal diameter of 16cm was fabricated and tested. The TE generator system consisted of two commercial TE modules, a metal sheet wall which acted as one side of the gasifier's structure and served as the hot side of the TE modules and a rectangular fin heat sink at the cold side of the TE modules. A blower was used to suck the ambient air to cool the heat sink and blow the air from the heat sink to the reactor of the gasifier. Gasification was conducted in a temperature range of 500-700°C and gasification agent, air feeding rate of 18.6 m3/h. The results revealed that the electrical power output and the conversion efficiency depend on the temperature difference between the cold and hot sides of the TE modules. At the temperature difference of approximately 60°C, the unit achieved a power output of 3.9W and a conversion efficiency of 2.01%. Through a comparison of results between the theoretic model and the experimental system, the reasonability of this system model has been verified.

Improved Gasification of Rice Husks for Optimized Biochar Production in a Top Lit Updraft Gasifier

Biochar is a solid material obtained from the carbonization of biomass. If properly produced, it is useful for soil application to enrich plant values. Rice husk (RH) waste, an abundant agricultural by-product, was gasified in a top-lit updraft Belonio rice husk gasifier with a biochar yield of 29.0% ± 1.9%. The equivalence ratio (ER) for optimum biochar production was identified and its effect on biochar properties such as pH, volatile matter (VM), fixed carbon (FC) and ash content (AC), electricity consumption, biochar yield, specific gasification rate (SGR) as well as reactor temperature investigated and statistically analyzed. As ER increased from 0.292 ± 0.005 to 0.442 ± 0.016, the SGR decreased from 85.4 ± 4.5 kg/(m2hr) to 51.6 ± 2.4 kg/(m2hr) whereas reactor temperature increased linearly with ER. The original VM content of RH was found to be 76.1% ± 1.2% and decreased with increasing ER from 14.1% ± 0.2% to 10.6% ± 0.3%. The original FC and AC of 5.49% ± 0.22% and 9.10% ± 1.23% increased with ER from 50.5% ± 0.7% to 51.3% ± 0.4% and 33.7% ± 0.4% to 36.7% ± 0.1% respectively. The biochar pH at low, medium and high ER was 9.36 ± 0.11, 9.64 ± 0.03 and 9.42 ± 0.01, respectively. Results revealed a significant change in biochar yield and proximate values as ER changes from low to high.

Prospects of Rice Husk Gasification for Power Generation in Bangladesh

Electricity is the basic requirement to promote socio-economic development. In recent years, Bangladesh is facing severe power crisis all over the country, but the rural areas are the most vulnerable. This acute electricity crisis along with the conventional fuel crunch is affecting every sector of the country and economy is being crippled. To reduce the dependency on fossil fuels, rice husk which are widely abundant agricultural waste from rice industry could play a vital role in this regards. Bangladesh is an agricultural country and produces huge quantity of rice every year. In the year 2011, the total rice production was around 50.63 million tones. Husk is the waste biomass produce during the rice processing, on average it accounts around 20% of the rice produced on weight basis (10.12 million tones). The potential of power generation from rice husk by gasification is around 310 MWe in Bangladesh. The power plant to be installed near the large rice mills `cluster areas’ in Dinajpur, Bogra, Naogaon, Chapainawabganj and Ishwardi with the surplus rice husk. This paper consolidates information from various studies on the availability of rice husk, its characterization and estimates possible power potential that can be realized.

An Overview of the Downdraft Rice Husk Gasifier Technology for Thermal and Power Applications

An overview of the downdraft rice husk gasifier (DDRHG) for thermal and power applications is herein presented. The different designs of the downdraft rice husk gasifier with reactor diameter ranging from 0.10 meter to 1.20 meter are discussed in detail. Smaller units of the DDRHG were found to have performed well in fixed bed. Larger units of the gasifier, on the other hand, are suited for moving-bed type making possible continuous operation without discharging and recharging the reactor. Present thermal applications of the gasifier includes: domestic cookstove, bakery oven, dryers, rotary kiln, steam boiler, and torrefyer. The DDRHG is also used to run surplus gasoline engines for driving water pump, micro-mill, and electric generator without any modification. The advantages and limitations of the gasifier as well as its environmental and socio-economic benefits over the use of conventional fossil-fueled systems are enumerated. At present, the investment cost for the gasifier ranges from PHP2,000 to 2,500.00 (USD 1 = PHP40.00) per kWt for thermal application and PHP20,000.00 to 30,000 per kWe for power generation. The cost of using the gasifier is much cheaper than that of the conventional fossil fuel and the investment can be recovered in a shorter period.

Energy generation from fluidized bed gasification of rice husk

Though gasification of biomass in fluidized bed system is an efficient way of biomass utilization, limited experimental data on the fluidized bed biomass gasification are available in open literature. Therefore, an experimental study of biomass gasification is conducted using a laboratory scale bubbling fluidized bed gasifier. Rice husk is used as the biomass material and air-steam mixture is used as the gasifying agent. As the non-granular nature of rice husk makes it difficult to fluidize, silica sand is used as the inert bed material to help in fluidization. Parametric studies are performed to determine the effects of reactor temperature, equivalence ratio, and steam-to-biomass ratio on the product gas composition and the heating value. The results show that both hydrogen percentage and the heating value of the product gas increase with increase in gasification temperature and steam-to-biomass ratio, but they decrease with increase in equivalence ratio. The maximum heating value (4.26 MJ/Nm3) and hydrogen percentage (13.1%) are obtained at the gasification temperature of 850 °C, equivalence ratio of 0.35 and the steam-to-biomass ratio of 0.8.

The Impact of Biochar Application on Soil Properties and Plant Growth of Pot Grown Lettuce (Lactuca sativa) and Cabbage (Brassica chinensis)

The effect of rice-husk char (potentially biochar) application on the growth of transplanted lettuce (Lactuca sativa) and Chinese cabbage (Brassica chinensis) was assessed in a pot experiment over a three crop (lettuce-cabbage-lettuce) cycle in Cambodia. The biochar was the by-product of a rice-husk gasification unit and consisted of 28.7% carbon (C) by mass. Biochar application rates to potting medium of 25, 50 and 150 g kg−1 were used with and without locally available fertilizers (a mixture of compost, liquid compost and lake sediment). The rice-husk biochar used was slightly alkaline (pH 7.79), increased the pH of the soil, and contained elevated levels of some trace metals and exchangeable cations (K, Ca and Mg) in comparison to the soil. The biochar treatments were found to increase the final biomass, root biomass, plant height and number of leaves in all the cropping cycles in comparison to no biochar treatments. The greatest biomass increase due to biochar additions (903%) was found in the soils without fertilization, rather than fertilized soils (483% with the same biochar application as in the “without fertilization” case). Over the cropping cycles the impact was reduced; a 363% increase in biomass was observed in the third lettuce cycle.

Hot Utilization of Fuel Gas in Fluidized Bed Biomass Gasification

The characteristics of hot gas utilization are analyzed in the thesis and experiments on rice husk were done in 6 MW bubbling fluidized-bed positive pressure gasification system. The results showed that the positive rice husk gasification system can work well and no tar condensed on the pipes. As sensible heat of hot gas accounting for 11.7% of fuel, the method of hot utilization of fuel gas can make full use of gas energy.

Characteristics of cyclone gasification of rice husk

Abstract The gasification characteristics of the rice husk were studied in a cyclone gasifier using air as the gasifying medium to generate the fuel gas with available heating value and less tar content. The influence of equivalence ratio on temperature profiles, composition and low heating value of the produced gas, tar content, carbon conversion and cold gas efficiency was investigated. The equivalence ratios considered in this study were 0.20–0.32. The results show that the optimal equivalence ratio is 0.29 and the maximum temperature of gasification should be lower than 1000 °C. In order to optimize the performance of the cyclone gasifier, the main body of the gasifier was lengthened and air staged gasification was carried out. The low heating value of the produced gas, carbon conversion, cold gas efficiency and tar content are 4.72 MJ/Nm 3 , 57.5%, 37.3% and 1.85 g/Nm 3 , respectively.