K. N. Sheeba

The Reaction Kinetics for Coir Pith Pyrolysis in Thermogravimetric Analyzer

Abstract The decomposition behavior of biomass when subjected to thermal stress is different for each kind of biomass. Modeling a pyrolysis or gasification process is complex because the mechanism of decomposition is highly dependent on its mass loss characteristics. The decomposition behavior of coir pith using thermogravimetric analysis is studied for heating rates of 20 and 25 K/min, and the kinetics are predicted using the well known Arrhenius relationship. It is found that the decomposition characteristics of coir pith can be divided into three different zones designated as moisture removal, pyrolysis zone I, and pyrolysis zone II. The kinetic parameters for each zone are validated using a continuous pyrolyzer. It is found that the predicted kinetic parameters well represented the experimental pyrolysis process within an error of ±15%.

Prediction of pyrolysis and gasification characteristics of different biomass from their physico-chemical properties

ABSTRACT Thermochemical and biochemical routes are the two potential energy recovery modes from biomass. Irrespective of the methods employed, a better understanding of biomass fuels is essential as it projects storage, handling, and transportation issues. Knowledge on the properties of biomass also helps in the design of process equipment, prediction of product distribution and product components, etc. In this work, some essential analyses such as proximate, ultimate, sieve, bulk density, heating value, wet chemical, and thermogravimetry of some locally available biomass feedstock are performed and interpretation of the analysis findings in the context of pyrolysis and gasification is elaborated here.

Generation of fuel char through biomass slow pyrolysis

ABSTRACT As coal is fast depleting, suitable means of substituting coal need to be explored. In this work, a feasibility study of co-firing lignite with char was investigated. Some locally abundant biomasses were slow pyrolysed. The pyrolysed chars were characterized and their fuel properties were compared with that of Neyveli lignite. The study indicated that the heating value of chars (except rice husk char) were higher than Neyveli lignite. The study also revealed that the properties of chars were on superior to Neyveli lignite and can be substituted to Neyveli lignite.

Experimental Studies on Biomass Pyrolysis Using Microwave Radiation

The present work on microwave pyrolysis of bagasse aims at maximizing the bio-oil and gas yield by optimizing reaction time, biomass to microwave absorber ratio, and microwave input power. Further, the performance of two microwave absorbers, glycerol and char, are compared. Experiments are conducted with varying: contact time (5, 10, 20, 30, and 60 min), microwave input power (480, 640, and 800 W), and biomass absorber ratios (1:0.25, 1:0.5, and 1:0.75). The maximum bio-oil and gas yield is obtained at reaction time of 30 min, biomass absorber ratio of 1:0.75, and microwave power of 800 W.

Performance Evaluation of a Flat Plate Collector Coupled Solar Still System

The comparative performance of a solar still and a solar still-flat plate collector system has been studied for the actual environmental conditions of Trichy, Tamilnadu, as a measure to improve the efficiency of the solar still. Performance of a solar still with fresh tap water and saline water has been studied followed by a combined solar still-flat plate collector system. It is observed that the combined solar still-flat plate collector daily efficiency was 20.4 and 23.6% more than still alone fresh water and saline water system, respectively. The productivity was 20.8 and 24.1% more than still alone fresh water and saline water system, respectively.

A Study on the Underwater Performance of a Solar Photovoltaic Panel

Photovoltaic cells are prone to thermal degradation as surface temperature exceeds critical value. Temperature reduction is one of the options for efficiency improvement. An attempt is made to analyze the cooling effect on temperature drop. At different depths and for various flow rates of water in underwater environment, the best performance is observed with a maximum efficiency of 21.6% at a depth of 4 cm and 17.4% for a flow rate of 30 ml/sec at an optimized depth. An average reduction in temperature of 43.1% for no flow conditions and 47.6% for flow conditions has been observed in comparison with dry panel conditions.

Comparison study of fuel characteristics of slow pyrolyzed chars with Neyveli lignite

ABSTRACT As coals are fast depleting, suitable means of substituting coal need to be explored. In this work, a feasibility study of co-firing lignite with char was investigated. Some locally abundant biomass were slow pyrolyzed. The pyrolyzed chars were characterized and their fuel properties were compared with that of Neyveli lignite. The study indicated that the heating value of chars (except rice husk char) were higher than Neyveli lignite. The study also revealed that the properties of chars were on superior to Neyveli lignite and can be substituted to Neyveli lignite.

The effect of temperature and hemicellulose-lignin, cellulose-lignin, and cellulose-hemicellulose on char yield from the slow pyrolysis of rice husk

ABSTRACT In this work, the effect of temperature on the char yield of untreated rice husk, cellulose removed (hemicellulose + lignin), hemicellulose removed (cellulose + lignin), and lignin removed (cellulose + hemicellulose) is investigated. The work compares the performance of acid and alkaline hydrolysis in the context of lignin removal as well. The effect of hemicellulose-lignin, cellulose-lignin, and cellulose-hemicellulose on char yield during slow pyrolysis of rice husk is also studied. The study reveals that only low temperatures favor char yield. Alkaline hydrolysis effects better lignin removal than acid hydrolysis. The effect of hemicellulose-lignin on char yield is more than cellulose-lignin and cellulose-lignin.

Effect of Co-firing Coals of Varying Fuel Characteristics

Utility and industrial steam generators in India are designed to burn coal for generating electricity, due to coal availability and economy. Rapid increase in coal-fired power projects increased the gap in demand and supply and therefore necessitated using available coals rather than plant design coal. Studies in different capacity boilers using coals of varying properties like gross calorific value, fixed carbon, volatile, moisture and mineral matter up to 100% in gross calorific value and 200% in mineral matter more than that of designed coal has been conducted. Performances of boilers were different than predicted due to variations in the fuel characteristics.

Steam Gasification Characteristics of Coir Pith in a Circulating Fluidized Bed Gasifier

The effect of steam/biomass ratio, oxygen/carbon ratio on gas composition, gas heating value, gas yield, tar yield, carbon conversion, cold gas thermal, and overall thermal efficiency on a circulating fluidized bed biomass (coir pith) gasifier has been presented. The presence of steam altered the composition of product gas. A hydrogen yield of 43% has been observed for a steam/biomass of 4.5 and a temperature of 1,008°C due to the presence of potassium oxide in larger quantities in coir pith ash. As the steam/biomass increased, gas heating value decreased, the gas yield decreased, tar yield increased, and carbon conversion decreased.