An analysis of the experimental characterization of the three agricultural residues redgram stalk, soyabean stalk, and chilli stalk (biomass) was carried out and the higher heating values (HHV) were determined using the available correlations from the literature. The selected agricultural residues proximate analysis results show moisture about 4.2 to 7.4%, the volatile matter about 79.3 to 85.8%, fixed carbon about 4 to 8.94%, and ash about 2.5 to 5.5%. The ultimate analysis results present elemental compositions such as carbon about 46 to 49%, hydrogen about 5%, oxygen about 30%, and the nitrogen about 3.1 to 3.7% with very low sulfur content. The HHV of agricultural residues varies from 14MJ kg-1 to 19MJ kg-1. The design of the downdraft gasifier to accommodate agricultural residues was carried out taking into account the characteristics of the agricultural residues and the specifications of the internal combustion (IC) engine. The characteristics of the agricultural residues depict that the three agricultural residues are suitable for gasification and can be used in a single gasifier.

Background: Agricultural waste has been proposed as an alternative energy resource to meet fossil fuel crisis, green house emission, and other environmental impacts worldwide. In Iran, rice husk and bagasse are main resources of biomass which can be used to produce syngas. This paper deals with a simplified model of combined gasification of coal and biomass processes considering chemical equilibrium.Results: It should be noticed that the CO2 which is produced from agricultural waste gasification is natural because the biomass absorbs CO2 from nature and gives it back after gasifying; however, mixing agricultural waste with coal leads to enrich syngas quality and gasifier efficiency.Conclusions: In this regard, an advanced coding was developed to simulate the thermodynamics of the co-gasifier and to find the produced syngas composition. The effects of moisture content, steam-to-biomass ratio, and gasifier temperature are then discussed on the system performance. Additionally, co-gasification of rice husk/coal was compared with co-gasification of bagasse/coal. The results indicated that adding coal to biomass increases lower heating value of syngas from 4, 694 kJ/Nm3 to 5, 321 kJ/Nm3 and gasifier efficiency from 71.29% to 77.85%.

In international development programs on improvement of energy supply for cooking in remote regions, where people are dependent on wood as the sole fuel resource, biomass cook stoves have a remarkable place. The thermal efficiency of such stoves are up to 3 times of those of traditional open fire stoves. In this research, a biomass cook stove was manufactured and evaluated according to the emission and performance test protocol. The fire power of the stove was 1. 4 kW, and flaming duration by feeding 400 g of pistachio shell was recorded to be 26 minutes. In order to improve the pyrolysis vapor combustion process, a damper was embedded in the stove, and also the outer wall of the stove was isolated by using a ceramic layer. Results showed that the control index was improved by three folds. Also, burning duration increased up to 57% and the emission of carbon monoxide was found to be in the permissible range.

In this paper, air gasification of Tehran’ s refinery Mazut is investigated. First, Mazut gasification is modeled by the equilibrium method and then, the thermal operating of an entrained flow gasifier is studied experimentally. An entrained flow gasifier is designed and manufactured for 7 kg/h flow rate of heavy fuel oil. The physical/chemical properties of the heavy fuel oil are determined via standard laboratory experiments. A parametric study is conducted by the equilibrium model in order to investigate the effects of equivalence ratio on syngas composition, gasification temperature, and higher heating value for the steady-state condition. Temperature distribution along the gasifier and the solid carbon consumption are effective parameters on syngas composition and gasifier performance. In an experiment, the gasification temperature is measured at different locations along the gasifier. The modeling results show that the values of H2, CO, and HHV have a maximum which is accompanied with complete consumption of solid carbon at equivalence ratio 0. 39. By increasing equivalence ratio, gasification temperature increases which are supported by experimental results. The comparison of modeling and experimental result shows that difference between model and experimental temperatures increases by increasing equivalence ratio. Also, after a short distance from the injector, the temperature is decreased along the gasifier with a constant rate. Finally, in order to provide the optimum gasification operation, a relation between the appropriate gasifier length and operating equivalence ratio is presented based on the water-gas shift reaction.

An Eulerian–Eulerian-based two-dimensional mathematical modeling approach for bubbling fluidized bed gasifier using FLUENT has been proposed to transfer energy, momentum, and mass between two phases namely solid and gas together with the application of the kinetic theory of solid particle flow. The modeling equation involves eight homogeneous and five heterogeneous reactions kinetics. The eddy dissipation model of FLUENT has been used to incorporate homogeneous reaction kinetics and a user-defined code has been developed that describes the kinetics of heterogeneous reactions. The simulation result shows that the exit syngas composition is in line with the experimental one and has a maximum error of around 4.05% for CO and 2.68% for hydrogen. This model has been used to study the variation in hydrogen concentration in the syngas to maximize hydrogen production based on different operating and design parameters.

The main advantage of a fluidized bed is its capability in excellent gas-fuel mixing. However, due to the lacks of gas radial momentum, its lateral mixing of gas-solid is not adequate. Therefore, this research is focused on fluidized bed hydrodynamics enhancement using the modified gas distributor plate design. For getting an optimum fluidized bed hydrodynamics prediction, three different classical ANSYS Fluent drag models, namely Wen-Yu, Syamlal O’ Brien, and Gidaspow are examined first. Afterward, a novel distributor plate called swirl distributor plate (SDP) is proposed in order to enhance the gas-fuel mixing in vertical and radial directions. In terms of simulation approach, results were presented and compared with the experimental data. It has been observed that better hydrodynamics prediction is achieved by Syamlal O’ Brien drag model. The effect of SDP on gas-solid mixing was then studied numerically and compared with conventional distributor plate (CDP). Compared with CDP, better gas-solid mixing was found while the SDP was used. As a final point, gasification test was conducted in a lab scale system in order to study and compare the composition of produced syngas using both distributor plates. Based on the gasification results, SDP leads to promotion of Hydrogen and Carbon monoxide by 34. 85 and 65. 92 percent, respectively.

Concerning the global warming due to large CO2 emission, the efficient use of coal becomes important for getting sustainable energy production. Coal gasification under CO2-rich condition is expected to be an effective way to produce a concentrated and pressurized carbon dioxide stream, resulting in reduction in separation energy of CO2 for CCS. Moreover, the soot formation, which is of significant environmental concern, is still being neglected in the past studies of coal gasification. A one-step soot formation reaction mechanism is proposed in this study and implemented in numerical simulations of coal gasification with the aim of describing the gasification behaviors in a two-stage entrained-flow gasifier. In addition, the effects of O2 ratio and CO2 concentration on soot concentration, syngas heating value and carbon conversion are numerically studied in an effort to increase the syngas production. The Eulerian–Lagrangian approach is applied to solve the Navier–Stokes equation and the particle dynamics. Finite rate/eddy dissipation model is used to calculate the rate of nine homogeneous gas-to-gas phase reactions including soot formation and soot oxidation. While only finite rate is used for the heterogeneous solid-to-gas phase reactions. It is found that formation of soot enhances the H2 production in the gasifier. Carbon conversion gradually increases with an increase in O2 ratio, while producing a low heating value syngas beyond a certain limit of O2 ratio. In contrast, an increase in CO2 concentration in the gasifier increases heating value of product syngas.

In this paper, numerical simulation of asphalt water slurry gasification process as a heavy fuel oil in a single stage gasifier, using the commercial Ansys fluent software, in a two-dimensional geometry And based on the Eulerian-Lagrangian approach has been done. In this simulation, the distribution of velocity, temperature distribution and molar fraction distribution of synthesis gas species have been calculated. The effect of different devolatalization models, the discrete phase particle size on gasification, and also for the first time, the effect of the use of discrete phase non-spherical particles on gasification parameters has been investigated. The results of this study showed that the water mixture of asphalt can be considered as a suitable feed for gasification. In the study of non-spherical particles it was also found that if the particles with a shape factor of 0. 1, which have the greatest difference with spherical particles, are used, the temperature of the chamber slightly increases and the maximum temperature is more distant than the feed intake.