Calorific Value Of Producer Gas Research Articles

Design and Development of a Novel Hybrid Gasifier for High Ash Content Coal as feed stock

India has large proven reserve of coal but most of the coal has large quantity of ash. Utilization of this high ash content coal is again a verychallenging task. Presently, gasification of high ash coals has not yet been in application due to the difficulties arising from the ash handlingprocesses. In this work an attempt was made to design a partially fluidized bed reactor that can handle 30 kg/hr coal as a feedstock. By usingan appropriate design procedure a complete design of a hybrid gasifier was studied deeply. The major aim of present research is todetermine the air flow rate for proper gasification, reactor diameter and reactor height, feed particle diameter, nozzle orientation and numbernozzles, reduction zone diameter and height. Experiments were carried out with feeding rate of 9.8 kg/hr with high ash content coal having39.83% ash. Satisfactory results have been found during experiments. The average producer gas generation during trial run was found to be29.8 Nm3/hr while average calorific value of producer gas was about 4500 kJ/Nm3. The work described here favours us understand the realgasification process for high ash content coal and thus facilitates the industrial application of gasification technology.

Advancements and challenges in the fluidized bed gasification system: A comprehensive review

A gasifier employs partial ignition of biomass and conversion to gaseous fuels of high calorific value. Bubbling fluidized bed gasifier is a promising one amongst other gasification technologies like fixed bed, entrained flow etc. It has several noteworthy advantages like large- and small-scale applications, efficient heat and mass transfer rates due its fuel flexibility, low capital and operating costs, etc. However, low mixing rate of biomass feedstock and gasifying agent, high tar content in the product gas and low calorific value of producer gas are some of its limitations which need sincere attention to enhance its performance. The present study analyzes the effect of design variables of the proposed gasifier reactor for different feedstock along with the operating variables on the quality of producer gas. This review paper examines the present global status of biofuels, different types of gasification technologies, approaches adopted for the gasification, different parameters affecting gasification performance, enhancement of product gas conditioning, technical and cost-effective viability and the future prospects of gasification.

Response Surface Methodology to predict the performance and emission characteristics of gas-diesel engine working on producer gases of non-uniform calorific values

Energy generation through gasification technology has received significant attention from policy makers and researchers. To promote government policies on biomass and utilize energy source that are abundantly available in rural areas, suitable technologies must be developed with a focus on popular applications in a place. The biomass in rural areas differs from place to place and they may not generate uniform calorific value (CV) of producer gas (PG). The quality of PG is essential to run engines of power generators with required performance. Hence, in this study, a mathematical investigation was performed on a dual-fuel diesel engine for CV of PG from 3.4 to 6.6 MJ/Nm3. The major objective was to find the impact of the variation in CV of PG from coir pith, rice husk, rubber wood, coconut shell and rubber seed kernel shell on the performance of the engine. Response Surface methodology with suitable tools had been used for developing the model. The model predicted the optimum thermal efficiency, specific energy consumption and diesel replacement rate as 25.8%, 13.95 MJ/kWh and 59.04% respectively while calorific value of PG was 6.57 MJ/Nm3. However, CO and NOx emissions were found increasing with the increase in calorific value of PG.

Spent tea waste as a biomass for co-gasification enhances the performance of semi-industrial gasifier working on groundnut shell

An effective utilization of agricultural waste as an energy source for decentralised power generation and thermal applications can meet the increasing energy demand in rural areas. A substantial number of thermo-chemical conversion systems are used for this purpose; nevertheless, it is significant to improve their efficiency to widen the implementation of this technology for various applications. Groundnut shell is one of the popular agricultural wastes available in many countries like India. Due to its low bulk density and physical nature co-gasification of this feedstock with another biomass is not popular. However, a high carbonaceous powdery biomass like Spent Tea Waste (STW), a waste after brew tea can be suitably mixed with groundnut shell along with some moisture to accomplish this task. To prove this strategy an experimental study has been conducted at various combinations of these two types of biomass as feedstock in a 115 kWth semi-industrial type gasifier, and its performance parameters are studied for possible operating conditions of the gasifier. The observations show that the wet STW can maintain a uniform consistency, when mixing both the biomasses until its composition is 40% of the blend. The results show that the increase in hydrogen composition, calorific value and cold gas efficiency is in the ranges of 9.9–21.5%, 4.1–10.4% and 3.9–9.9% respectively as compared to groundnut shell. Besides, the maximum calorific value of producer gas is 6.68 MJ m−3.

Experimental investigation of imbert downdraft gasifier using rice straw briquettes

ABSTRACT The mechanized harvesting of rice crop has led to open-field burning of rice straw that liberates a large amount of greenhouse gases (GHGs), which have a negative effect on the environment. Gasification is an efficient technology for the conversion of biomass to producer gas with minimal greenhouse gas emissions. The present study was planned to convert the abundantly available rice straw into briquettes and its thermochemical conversion into producer gas for thermal energy utilization. The performance of imbert type gasifier was investigated using rice straw briquettes as fuel by studying the influence of airflow rate on fuel consumption rate and temperature profile inside the combustion zone. The augmentation of airflow rate from 0.0022 to 0.0042 m3/s led to a significant increase in feedstock consumption rate (63.3%). The time taken for boiling of water also increased with an increase in airflow rate which may be attributed to the corresponding decrease in calorific value of producer gas. Rice straw briquettes with cotton stalks as a binder (90:10) can act as a clean alternative fuel for gasification and the producer gas generated can be used for various thermal applications.

Gasification of walnut shells in an open core downdraft gasifier for the producer gas generation

ABSTRACTThis research work depicts the results obtained during the experiment performed for walnut shell gasification process. In order to carry out the gasification process, a downdraft gasifier has been installed in a Thermal Engineering Laboratory of National Institute of Technology, Kurukshetra, India for the purpose of generating a combustible gas popularly known as “Producer gas.” The walnut shells have been gasified with air used as a gasifying agent. In this experimental work equivalence ratio varied from 0.170 to 0.251; subsequently, feedstock consumption rate also varied from 68 to 77 kg/h. Results publicized that at an equivalence ratio of 0.251, cold gas efficiency and calorific value of producer gas has its maximum value of 83.07% and 7.59 MJ/Nm3, respectively. The percentage of methane (CH4) in producer gas reached its maximum value of 7.04% at equals to 0.251. Further, oxidation zone temperature varied in between 700 and 1000°C during this study.

Refining of producer gas using sand filters: An experimental study

The presence of tar in producer gas is a major bottleneck in wide application of biomass gasifier. The tar mitigation can be accomplished by physical methods, catalytic methods and thermal cracking method. The physical tar cracking method is done by passing the gas through sand filter or oil scrubber. In this study the tar refinement using sand filter has been attempted. The issued gas from biomass gasifier was passed across the sand filter positioned at the downstream of the gasifier. Initially experiments were carried out with 100 g of sand and then the quantity of sand was increased up to 500 g in steps of 100 g. As the sand quantity was increased the tar refinement increased from 16.5% to 38%. This experimental study indicated that there is further scope for tar refinement and improving the calorific value of producer gas using the catalytic tar mitigation methods.

Improvement in the Calorific Value of Producer Gas from Rice Husk with Addition of Spent Tea Waste as Secondary Fuel

The need for effective utilization of primary sources of energy across the globe leads to intensive research on renewable energy-based technologies. Biomass gasification is one such technology, and...

Biomass gasification in a fixed bed downdraft reactor with oxygen enriched air: a modified equilibrium modeling study

Biomass conversion by gasification process is increasingly becoming attractive, especially for ceramic making industry, to transform biomass materials into combustible fuel gas called producer gas. This producer gas can then be used to fully or partially substitute liquefied petroleum gas in ceramic firing process. However, air gasification is known to generate low calorific value of gaseous fuel (3-6 MJ/Nm3) which may not be able to generate sufficiently high temperature (> 1200 oC) flame required by ceramic firing process. Use of oxygen enriched air is therefore of great interest if medium to high calorific value producer gas is required. In this work, a modified equilibrium model of global gasification reactions is developed to predict the resultant distribution of combustible gas species in the producer gas and to study the effect of operating parameters (oxygen content in air, and equivalence ratio) in a gasification process of agro-residues in a fixed bed downdraft gasifier at a fixed temperature. The modified equilibrium model of global gasification reactions developed in this work is based on thermodynamically stoichiometric approach due to its simplicity and reduced computational time. Model predictions of reaction kinetic constants for gasification reactions and gas concentration are validated by comparing with available experimental data. Simulation of influence of oxygen content in air (21-50%) and equivalence ratio (0.15-0.35) on composition of combustible gas and its heating value is carried out. The preliminary model simulation is found to give good qualitative prediction of experimental results. For maximum calorific value of producer gas generated, oxygen content in air should be 50%, and the equivalence ratio should be 0.15, respectively. For better accuracy of this modified equilibrium model, unconverted char and tar should be further considered.

Hydrogen production from biomass gasification; a theoretical comparison of using different gasification agents

In the present paper hydrogen production from biomass gasification using various agents is investigated and compared theoretically, from the viewpoints of the first and second thermodynamics laws. Gasification of wood and paper, as two types of common biomass feedstocks, is assessed using four gasification agents namely: air, oxygen-enriched air, oxygen and steam. Thermodynamic equilibrium model is employed to simulate the gasification process, the results of which are validated using available theoretical and experimental data in literature. The NOx and SOx emissions from the biomass gasification are also considered in the model and a sensitivity analysis is performed to determine the accuracy of the results regarding to the uncertainties of the input data. A parametric study is conducted to assess the effects of key operating parameters on the hydrogen concentration and calorific value of producer gas, energy and exergy efficiencies of the process and exergy destruction rate at different operating conditions. The results indicate that the higher values of hydrogen production is associated respectively with using steam, oxygen, oxygen-enriched air and air as the gasification agents. Also, it is concluded that for the gasification process the highest value of sensible energy efficiency is obtained for air gasification, while the highest exergy efficiency, as a rational criterion, is obtained for steam gasification for which the calorific value of the producer gas can reach to higher than 11 MJ/Nm3.

Comparison of downdraft and updraft gasification of biomass in a fixed bed reactor

The aim of this study was to compare and analyze the gasification process of beech wood. The experimental investigation was conducted inside a gasifier, which can be operated in downdraft and updraft gasification system. The most important operating parameter studied in this paper was the influence of the amount of supply air on the temperature distribution, biomass consumption and syngas calorific value. The results show that the amount of air significantly influences the temperature in the combustion zone for the downdraft gasification process, where temperature differences reached more than 150 °C. The increased amount of air supplied to the gasifier caused an increase in fuel consumption for both experimental setups. Experimental results regarding equivalence ratio show that for ER below 0.2, the updraft gasification is characterized by a higher calorific value of producer gas, while for ER=0.22 a similar calorific value (6.5 MJ/Nm3) for both gasification configurations was obtained. Above this value, an increase in ER causes a decrease in the calorific value of gas for downdraft and updraft gasifiers.

Utilization of coal gasification producer gas for power generation using 10 kw spark ignition engine

Coal gasification is the process of converting coal into gas to ease its use and more environmentally friendly. Research and Development Center for Mineral and Coal Technology (tekMIRA) has been researching, designing, and developing a small-capacity gasifier with the brand of GasMin. This study discusses GasMin design and utilization for power generation using internal combustion engine type spark ignition engine. The result of laboratory analysis shows that the calorific value of producer gas was 1,013 kcal/Nm3, tar content was 4.04 mg/Nm3, particulate content was 11.17 mg/Nm3 and temperature of gas was 36oC. Based on characteristic of producer gas, it can be used for fuel in internal combustion engine. The internal combustion engine generator set (genset) used in this research was 10 kW spark ignition type. To be used for gas producer, some modifications were made on genset engine by replacing the function of the carburetor into mixing chamber for air and producer gas, and placed before mixing gas entering the combustion chamber.The results ofthis researchshow that the power generated was 4.8 kW, which was about 53% of maximum power on fuel. It isin accordance with the literature whichstates that de-rating of the genset engine ranges from 40-50%.

An Experimental Investigation on Gasification Characteristic of Pongamia Residue (Shell and De-Oiled Cake) as a Source of Energy for Rural Areas

This paper has been aimed for thermochemical gasification of Pongamia residue (mixture of shells and de-oiled cake) generated from the oil expellers and biodiesel production plants. Pongamia mixture pellets (with 11.5 mm diameter and average length in the range of 10–62 mm) were prepared and gasify in an open top downdraft wood gasifier. The temperature in various zones of the gasifier was measured by using S-type thermocouples. The calorific value of producer gas generated from pellets was in the range of 4.56–5.39 MJ/Nm3. The gasifier conversion efficiency was 94 % for pellets which is higher to that of wood gasification (74 %). Producer gas generated with these pellets was used in the spark ignition engine. The performance and emission characteristics of the engine were evaluated by varying load and spark timings. The engine brake thermal efficiency was 26 % at spark ignition timing 30° before top dead centre (bTDC) at full load condition. However, the de-rating of 4.5 % was observed when working with 100 % producer gas at compression ratio of 10. Emission parameters were on lower side at spark timing 30obTDC. The producer gas generated from the Pongamia mixture pellets could be used for heat and or power generation for rural areas.

Simulation of Biomass Downdraft Gasifier based on Neural Networks

The gasification technology is now considered to be in an advanced stage of development. Hence there is huge expectation from the user industry for its application. This paper presents a Developed Model for Gasification using Neural Network for both Air and steam Gasification and to predict the Calorific Value of producer gas, Composition of producer gas for the given input conditions namely Air Flow Rate, fuel Flow Rate, Steam Flow Rate, Oxidation Temperature, Composition of the Fuel etc. Model is capable of Handling MIMO (Multiple Input & Multiple Output) and Implementation of Real Time Values into the Network and Network has been trained to give expected output

Comparative Analysis of Combustion Vs Auto-gasification of Prosopis Juliflora Sticks for Rural Household Application

In 1870's the concern about deforestation, desertification and fuel wood shortage leading to the introduction of the Prosopis juliflora in India. The pro-line content in Prosopis is high under stress conditions, which helped the plant to thrive under extreme draught. Since Prosopis juliflora is abundantly available in rural areas, Indian rural households mainly depends on firewood for cooking and other thermal application using combustion route. The conversion efficiency of such system is very low and also degrade the environment. This paper analysis the combustion Vs autogasification route of converting Prosopis juliflora strikes into thermal as well as power application due to its high calorific value and ash properties. A novel gasification approach called autogasification has been employed converting solid combustible to gaseous fuel without supplying of oxygen to enrich specific calorific value of producer gas.

Experimental investigation on gasification characteristic of high lignin biomass (Pongamia shells)

Pongamia residue (shells) is the byproduct from the biodiesel processing industry, which is a lignocellulosic biomass material. It is not suitable as feedstock in downdraft wood gasifier due to low bulk density (146 kg/m3) of shells as compared to wood (more than 350 kg/m3). Pelletization and gasification of pelletized shells was carried out in the present work. The heat transfer analysis in pellets of 17 mm and 11.5 mm was also carried out to evaluate thermal properties of this biomass. Shell pellets of 17 mm and 11.5 mm diameter and length in the range of 10–60 mm were gasified in a 20 kWe downdraft wood gasifier. The complete gasification of pellets with 17 mm diameter could not be achieved because of less porosity and presence of larger thermal gradient within the pellets. The gasification efficiency was 73% for 17 mm diameter pellets which is lower than that of 11.5 mm diameter pellets which was 95%. The calorific value of producer gas generated from smaller diameter pellets was higher (4.66 MJ/N m3) as compared to larger diameter pellets (3.98 MJ/N m3). Tar formation during gasification of smaller diameter pellets was low as compared to larger diameter pellets.

Tar mitigation in biomass gasifiers using nano-structured Ni/SiO<SUB align="right">2 catalyst: an experimental study

The effectiveness of a nano-structured Ni/SiO2 catalyst for tar mitigation in a 15 kW biomass gasifier is investigated. The nano-structured Ni/SiO2 catalyst was synthesised by deposition-precipitation (DP) method. The characterisation of the nano-catalyst has been accomplished using X-ray diffraction (XRD), high-resolution scanning electron microscope (HR-SEM), high-resolution transmission electron microscope (HR-TEM) and Brunauer-Emmett-Teller (BET) method. The average size of nano-catalyst particles was found to be 20 nm. The experiments conducted with the nano-structured Ni/SiO2 catalyst resulted in tar cracking efficiency of 93%. In addition, the H2 and CO composition increased considerably, thereby enhancing the calorific value of producer gas.

Thermal degradation and gasification characteristics of Tung Shells as an open top downdraft wood gasifier feedstock

Tung (Aleurites Fordii) is cultivated in China, Argentina, Paraguay, Africa, India, and United States. Tung oil has various applications like as a drying agent for paints and varnishes, termite control as well as cleaning and polishing compounds. The Tung shell and de-oiled cake are residues after decortications of the Tung seeds. This paper has been aimed for thermal degradation and gasification of Tung shells. Thermal degradation of the Tung shell was carried out at heating rates of 10, 15, and 20 °C/min from room temperature to 750 °C under non-isothermal conditions, and N2 was used as a carrier gas. Based on the thermogravimetric analysis and differential thermogravimetric analysis results, it was found that Tung shells have low thermal stability. These shells were gasified in the downdraft wood gasifier. The calorific value of producer gas was calculated to be 4.75 MJ/Nm3. The conversion efficiency of the gasifier for Tung shells was higher (93 %) as compared to the wood (84 %). The producer gas generated from shells could be used for heat and or power generation for rural areas. Also a solution to reduce the disposal problem of toxic Tung shells generated from oil expellers.

Possibility of biomass gasification in tea manufacturing industries in Assam, India

Tea manufacturing industries in India use natural gas, tea drying oil, wood, and coal for process heat. India is the second largest producer of tea [(1,137.07, China 1,761.00) million kilogram] in 2012. About 0.6–1.2 kg of coal is required to produce one kilogram of dried tea with average moisture of 2.5–3 percentage (w.b.). Biomass gasification is an established renewable energy technology for heat and power applications. Biomass gasifier based tea drying using five biomasses namely shisham (Delbergia sissoo), gulmohar (Delonix regia), bamboo (Banbusea Tulda), dimaru (Ficus lepidosa wall), and neem (Melia Azedarach L) were considered as feedstock for an experimental 10 kW thermal downdraft gasifier cum tea dryer. It was observed that bamboo chips producer gas gave the best calorific value (4.85 MJ Nm–3). Shisham gave average calorific value of producer gas 4.83 MJ Nm–3. Therefore, biomass gasification may be recommended for partial conventional energy substitution in tea manufacturing industries in India.

Drying modelling and experimentation of Assam black tea (Camellia sinensis) with producer gas as a fuel

Thin layer drying kinetics of fermented tea (Camellia sinensis) was investigated at air temperatures (80, 90,100, 110) °C and velocities (0.50, 0.65, 075) m s−1 respectively using a producer gas furnace tea dryer. The tea samples weight, dry and wet bulb temperatures and air velocities were recorded continuously during each experiment. The black tea drying data were fitted to different semi-theoretical models such as Lewis, Page, Modified Page, Henderson and Pabis and Two Term, etc. The modified Page model gave better prediction of thin layer drying kinetics of black tea followed by Lewis model. The diffusivity constant (Do = 0.746 × 10−3 m2 s−1) and activation energy (Ea = 52.104 kJ mol−1) were computed from linear regression analysis. The modified Page model gave drying rate constant (k = 25.91 × 10−4 s−1) and exponent (n = 1) at 100 °C air temperature. Both air temperatures and velocities have influence to enhance drying rate constant (k) and exponent (n) in Page and Modified Page models. The energy consumption was found as 19.01 MJ kg−1 of made tea (3% w.b.) based on calorific value of producer gas (HHV = 4.39 MJ Nm−3). Specific energy consumption of the dryer was approximately 6.274 MJ kg−1 of water removed.