• Energy Research

Abstract We present results of an experimental study on long stick wood gasification, in an attempt to reduce wood gathering for gasification. This paper presents the results from experiments and the analyses of gasification using sticks with length ∼68 cm and diameter ∼6 cm. The moisture content of the wood was 25%. This top lit updraft gasifier operates with 180 W of blower power air supply to produce 9–10 kW of thermal energy, an energy yield of ∼50/1. Results were obtained for various flow conditions with airflow rates ranging from 25 to 45 m 3 /h. For modelling, the flaming pyrolysis time for long stick wood in the gasifier is calculated to be 2.1 min. The length of the flaming pyrolysis zone and char gasification zone is found to be 37 cm and 36 cm respectively. The turn down ratio for the gasification is around 2. The rate of feed was between 9 and 10 kg/h and the gasifier operated continuously for 5 h in two runs to study the gasifier reliability. The performance studies in specific gasification rate, equivalence ratio, turn down ratio, superficial velocity, airflow, and gas flow are analyzed. The temperature ranged from 1185 K in the combustion zone to 400 K in the drying zone. The gas and airflows can be converted to the Air/Fuel equivalence ratio, the most important aspect of gasifier operation. The equivalence ratio shows operation in a combustion mode (6.3) at start up; in a flaming pyrolysis mode (1.2) for the middle part of the run; and in the charcoal gasification mode (5.7) at the end of the run. Measurement of the equivalence ratio is a simple way of analyzing the behaviour of the gasifier. From the results of present investigation, it is revealed that the top lit updraft gasifier is more suitable for long stick wood as feed when compared to conventional updraft gasifier.

Based on the experience of the gasifier users on the efforts and energy for wood chip preparation in a typical gasifier, we have embarked on the development of a gasifier suitable to work with long stick woody biomass as the feed materials. In the context of the impact of gasifiers, as decentralized energy delivery devices such an approach, it is hoped, would be an attractive option in rural areas both in domestic and industrial sectors. In the present paper in the gasifier operation, there is a fixed quantity of char that is combusted to gasify a fixed amount of wood, and the gasifier does not operate in a steady state manner. In this present work, focus is made on the development of a gasifier using long sticks of wood as feed materials. With this concept, a 10 kW thermal output power gasifier is designed and constructed. The gas and airflows can be converted to the air/fuel ratio, the most important aspect of gasifier operation. The air/fuel ratio shows operation in a combustion mode at start up, a gasification mode for the middle part of the run and a charcoal gasification mode at the end of the run. Since the interest here is exploring and validating of this concept, a bottom lit updraft gasifier is designed mainly to look at the gas yield and other favourable factors and to use this gas so obtained for thermal applications. The rate of feed was between 9 and 10 kg/h and continuous operation for 5 h was made in a couple of runs to study the performance. In this paper we report the salient features of our efforts and results, yielding a gasifier efficiency of 73%.

AbstractA rotary screw pyro‐oil reactor was designed for powdery biomass for a feeding capacity of 40 kg h−1 with a moisture content of <10%. The pyro‐oil reactor temperature was maintained at 450–550 °C. The pyro‐oil vapors produced were quickly drafted out of the reactor for quenching to yield 16–24 L h−1 from 40 kg h−1 of biomass feed. The flash‐pyrolysis technique, which is capable of directly turning biomass into a liquid fuel, was used to produce liquid fuel (bio‐oil). It was carried out at a pressure at 0.03 bar and at a medium temperature of about 550 °C. The flash‐pyrolysis technique converts the entire biomass matter, excluding the ash. In this method the powdery biomass is converted into three components: bio‐oil (the yield is typically 70% on an energy basis, a powdery biomass feed at a moisture content of 10%); pyrolysis gas (typical yield 14%) and char (typical yield 16%). The temperature of the fixed bed was adjusted in the experiment, but the other variables remained constant, such as the amount of feed, the pyrolysis time of the gas product, the reactor pressure and the bed height. A biomass particle size range of 1–3 mm and a biomass residence time of 20 s in the reactor resulted in optimal bio‐oil production of 70%. This work demonstrated how precise pyrolysis mechanism processes and bio‐oil yields can influence the maximal reaction temperature in the 450–550 °C range. The performance analysis reveals that the fixed bed reaction temperatures of biomass rapid pyrolysis give reliable control over the bio‐oil reactor type and size. This paper provides an overview of the design and thermochemical liquefaction process used to convert powdered biomass to biofuel. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

In India, a considerable quantity of charcoal is used in urban areas for applications ranging from industrial processing to domestic cooking. Unfortunately, field information on various aspects of charcoal production, distribution and consumption is almost non-existent. In order to promote development and proper technical intervention in charcoal production and positive links with social forestry and wasteland development programmes, collection of first-hand information on charcoal markets and marketing practices would be useful. Charcoal-making practices are empirical in nature with a built-in traditional wisdom inherited from one's ancestors. Clear scientific study of the whole process with the interventions for controlling the influencing parameters is lacking. For long-term production of charcoal, using thin but long twigs and similar type of woody biomass seems to be ideal due to the possibility of producing them in wastelands and in a short time-frame. Moreover, reaction times for the batch process in an industrial kiln are typically 8 days. In this article we describe a practical method for manufacturing high-quality charcoal from biomass that realizes yields of 48-83 % on energy basis with a reaction time of about 5 hr, depending on the moisture content of the feed. An experimental study of the conversion by pyrolysis of long-stick wood to charcoal in a partial combustion kiln was conducted to understand and upgrade the process. The present study investigates the process of partial combustion in charcoal kilns. With this concept, a 250-kg capacity metal kiln was designed and constructed. For the test period of 5 hours, 250 kg of long stick wood was converted into 75 kg of charcoal. The average conversion ratio of 3:1 means that 3 kg of air-dried fuel wood is burnt to produce 1 kg of charcoal. The temperature profiles of 456-600$dG C inside the kiln help to understand the process of pyrolysis reactions to obtain charcoal in final form.

Large-size woody biomass is a valuable renewable resource to replace fossil fuels in biorefinery processes. The preprocessing of wood chips and briquettes is challenging to manage, especially in an industrial setting, as it generates a significant amount of dust and noise and occasionally causes unexpected accidents. As a result, a substantial amount of resources, energy, labor, and space are needed. The thermochemical conversion behavior of large-size woody biomass was studied to reduce energy consumption for chipping. Large-size wood was 1.5 m in length, 0.1 m in breadth, and stacked 90 cm in height. This strategy has many benefits, including increased effectiveness and reduced CO2 emissions. The target of this paper presents the thermochemical process, and large-size wood was chosen because it provides high-quality product gas while reducing the preprocessing fuel cost. This review examines the benefits of thermochemical conversion technologies for assessing the likelihood of carbon neutrality.