Energetic study of residual forest biomass using calorimetry and thermal analysis

Summary The European policy on energy focus on the search for alternative and renewable sources of energy where forest biomass plays a significant role. In this article, calorific values of different kinds of forest residues (leaves, thin branches, barks, etc.) are reported. These values were measured by combustion bomb calorimetry with the objective of understanding, through different risk indices, the behaviour of forest waste in the case of wildfires, and also to study the use of forest residues as raw materials to be used as energy sources. The study was complemented with determination of elemental analysis, flammability using a standard epiradiator, thermodegradation analysis, and different mechanical tests trying to get relationships between thermal behaviour and some physical properties. The study was carried out on Eucalyptus globulus Labill and Pinus pinaster Aiton, because these forest formations have both high economical and ecological interest in Galicia (NW Spain).     

Autothermal biodrying of municipal solid waste with high moisture content

To carry out autothermal drying processes during the composting of biomass, a horizontal tubular reactor was designed and tested. A biodrying tunnel of the total capacity of 240 dm³ was made of plastic material and insulated with polyurethane foam to prevent heat losses. Municipal solid waste and structural plant material were used as the input substrate. As a result of autothermal drying processes, moisture content decreased by 50 % of the initial moisture content of organic waste of about 800 g kg⁻¹. In the tested cycles, high temperatures of biodried waste mass were achieved (54–56°C). An appropriate quantity of air was supplied to maintain a satisfactory level of temperature and moisture removal in the biodried mass and high energy content in the final product. The heat of combustion of dried waste and its calorific value were determined in a calorimeter. Examinations of pyrolysis and gasification of dried waste confirmed their usefulness as biofuel of satisfactory energy content.     

Co-combustion characteristics and kinetics of meager coal and spent cathode carbon block by TG-MS analysis

As a hazardous waste, the spent cathode carbon block (SCCB) has a high calorific value while it is difficult to fire, its harmless disposal is a major difficulty at present. Herein, a method of mixed combustion of meager coal and SCCB in a pulverized coal furnace for disposal of SCCB is proposed, and thermogravimetric mass spectrometry (TG-MS) is used to characterize the combustion and gas release characteristics. The effects of the heating rate and mixing ratio on combustion are analyzed as well. The result shows that the comprehensive combustibility index and combustion stability index of SCCB-5 at a heating rate of 50 °C/min are both the highest. Abundant oxygen-containing groups in SCCB promote the co-combustion process. The release of hydrogen fluoride is relatively low below 1000 °C so that the use of pulverized coal boilers meets the temperature requirement for disposal of SCCB. The good melting characteristics of ash after mixing sintering also confirm this point. Finally, the kinetic calculation results show that the combustion activation energy is the lowest when the mixing ratio is 5%, which is in good agreement with the experimental results. The highest activation energy values for the combustion of meager coal, SCCB and SCCB-5 are 46.90, 89.39, 59.87 kJ mol^?1, respectively.     

Thermogravimetric analysis of lignocellulosic and microalgae biomasses and their blends during combustion

Thermogravimetric analysis was used to study and compare the combustion of different blends of corn bioresidues with sunflower, rape and algae bioresidues. Non-isothermal thermogravimetric data were used to obtain the combustion kinetics of these bioresidues. This paper reports on the application of the Vyazovkin and Ozawa–Flynn–Wall isoconversional methods for the evaluation of kinetic parameters (energy activation, pre-exponential factor and order of reaction) for the combustion of the biomasses studied. Differences were found in the TG curves in accordance with the proximate analysis results for the cellulose, hemicellulose and lignin content of biomasses. The activation energy obtained from combustion (E ~ 151.6 kJ mol^?1) was lower than that from the blends (similar values were obtained for corn–sunflower, E ~ 160.5 kJ mol^?1 and corn–rape, E ~ 156.9 kJ mol^?1) whereas the activation energy obtained from the microalgae was higher (E ~ 171.5 kJ mol^?1). Both the Vyazovkin and Ozawa–Flynn–Wall methods yielded similar results.     

Thermal characteristics of the combustion process of biomass and sewage sludge

The combustion of two kinds of biomass and sewage sludge was studied. The biomass fuels were wood biomass (pellets) and agriculture biomass (oat). The sewage sludge came from waste water treatment plant. The biomass and sludge percentage in blends with coal were 10 %. The studied materials were characterised in terms of their proximate and ultimate analysis and calorific value. The composition of the ash of the studied fuels was also carried out. The behaviour of studied fuels was investigated by thermogravimetric analysis (TG, DTG and DTA). The samples were heated from an ambient temperature up to 1,000 °C at a constant three rates: 10, 40 and 100 °C min^?1 in 40 mL min^?1 air flow. TG, DTG and DTA analysis showed differences between coal, biomass fuels and sewage sludge. 10 % addition of studied fuels to the mixture with coal changed its combustion profile in the case of sewage sludge addition. The combustion characteristics of fuel mixtures showed, respectively, qualitative summarise behaviour based on single fuels. Evolved gaseous products from the decomposition of studied samples were identified. This study showed that thermogravimetric analysis connected with mass spectrometry is useful techniques to investigate the combustion and co-combustion of biomass fuels, and sewage sludge, together with coal. Non-isothermal kinetic analysis was used to evaluate the Arrhenius activation energy and the pre-exponential factor. The kinetic parameters were calculated using Kissinger–Akahira–Sunose model.     

Financial and energy costs of supplying woody biomass to conversion sites

A series of short rotationPopulus plantations involving four management strategies were evaluated in tandem with alternate harvest and storage strategies to determine the least cost method for supplying biomass to conversion sites. All inputs were itemized on both a financial and energy basis to establish the unit output costs for commercial-scale systems. The control strategy had the lowest production costs, at $28.74 Mg^-1 (ovendry), and 5,455 MJ Mg^-1(OD). The addition of harvest and storage costs, based on existing and proposed technologies within the forest product industries, increased the total supply cost for biomass to $59.61 Mg^-1(OD) and 7,233.1 MJ Mg^-1(OD). On a financial basis, the proposed cost was 17% more expensive than a projected price for biomass from an ethanol plant and was also higher than the general prices for aspen from domestic markets. However, on an energy basis, the gross heat of combustion for thePopulus biomass was 2.7 times greater than its total energy costs.     

Thermo-valorisation in integrated waste management

In 2002, approximately 25 million tons of Municipal Solid Waste (MSW) were produced in Italy, but no more than 5.5 million were collected separately. Data analysis shows that despite the progress in differentiated waste collection and in the process of quality recovery, dumps are still the most common means of disposal.With reference to thermo-valorisation, although the number of active thermal plants and the amount of thermo-valorised waste has increased (by over 10% from 1999 to 2000), total processed waste appears to be excessively low compared to the amount of waste produced. Moreover, it is below the EU average.Our objective was to analyse three different scenarios for the quantity of thermally valorisable waste through to 2005.We have also evaluated the incineration of MSW taking into account the technological, environmental and economic factors in different plant types (with and without energy and heat recovery) considering emission quantity and quality with possible CO₂ recovery.The most economical and environmental solution might be the transformation of waste to synthetic gas for use as an energy and heat source in a conventional power plant in the future.From current information we understand that today thermo-destruction with energy recovery and a combined energy–heat cycle could be an option with great benefits for the environment, and could even be competitive compared to other solutions for replacing some energy sources.     

A New Approach for the Determination of Organobromine in Harmful Waste

Determination and estimation of organic sulphur, nitrogen, phosphor and halides in harmful chemical waste and estimation of emission of SO₂, NO_X, HCI, HBr or HI during incineration are the primary task of risk assessment. In our paper we present a new analytical approach for determination of bromine in a heterogeneous sample. The method applied is based on combustion of chemical waste under oxygen atmosphere (pressure 20 bars) and transformation to corresponding anions. These anions can be measured by ion chromatography. Using this method all hetero atoms can be transformed to corresponding anions (except for oxygen) and can be measured by ion chromatography. In this paper we report of determination of bromine content of chemical waste. During the combustion of organobromine compounds different types of inorganic bromine are formed. All types of bromine must be converted to Br^–. To fulfil it the above, ascorbic acid solution was used for absorbing and transforming all types bromine compounds to Br^–. We will discuss all the details about this new approach and give all the parameters to get efficient conversion from organic bromine to bromide anions.This revised version was published online in November 2005 with corrections to the Cover Date.     

Biofuels

The article presents results of thermogravimetric measurements of the pyrolysis of dry biomass materials such as: grains and oats and triticale straw, energy plants called cukrosorgo. The initial phase of dry decomposition visible on the DTG curve is evaporation of moisture. The process of evaporation for the studied types of agro biomass occurred at temperatures of 65.9?°C (triticale straw) to 82?°C (oat grain). The next stage of the process concerned major transformations that for the studied cases were conducted in temperatures of 200?C400?°C, and the maximum speed of transformations (the second peak is visible in the DTG graph) refers to the temperature range from 299.1?°C (oat grain) to 323.9?°C (triticale straw). The last phase of the process is characterized by the absence of mass loss, which in the case of dry biomass distribution determines the conditions of carbonizate formation. The calorific values of formed process gases ranged from 4,884 to 6,302?kJ/Nm³. Gases of such calorific values are defined as low calorific, despite the fact they can be successfully used for energy purposes, this is for burning in boilers and gas turbines. Carbonizates are characterized with high-calorific values from 24,100 to 27,900?kJ/kg. This type of high-calorific fuels is recommended to be burnt in the boiler furnaces in a mix with fuels with a lower calorific value such as pulverized coal or wet biomass. In these processes, the combustible gas is obtained, which can be burned in power boilers and gas turbines.     

Study of pyrolysis kinetic of green corn husk

In this paper, it was suggested the use of green corn husk, which is a biomass from agro-industry, as an alternative source of energy through its pyrolysis. Green corn husk characterization was done through immediate and elemental analysis of its components: cellulose, hemicelluloses, and lignin. It was also measured its higher calorific value. The pyrolysis study of green corn husk was done by the isoconversion and the Master plots method. Thermogravimetric plots were obtained at heating rates of 5, 10, 15, and 20 °C min^?1. The pyrolysis kinetics parameters were studied through the Flynn–Wall–Ozawa (FWO), Kissinger, and Friedman models. The Master plots method was used to determine the pyrolysis reaction order. The results of the reaction energy activation were found to be in the range 105.21–157.46 kJ mol^?1 by the FWO method, 150.50 kJ mol^?1 by the Kissinger method, and ranged 120.66–163.81 kJ mol^?1 by the Friedman method. The Master plots method showed a three-way-transport diffusional kinetics for the biomass de-volatilization process. The higher calorific value found for green corn husk was 16.14 MJ kg^?1. The simulation showed correlation between the experimental data and the proposed model for conversion values up to 0.8.

     

Thermodynamique de composes azotes. VII. Etude thermochimique du pyrazole et de l'imidazole

Enthalpies of sublimation for pyrazole and imidazole have been obtained by calorimetry at 298.15K. The ΔH⁰_sub (298.15 K) values for these two compounds are, respectively, 69.16 ± 0.32 and 74.50 ± 0.40 kJ mole^?1. From literature data obtained by combustion calorimetry for ΔH⁰_f (c, 298.15 K), the enthalpies of formation of these compounds in the gaseous state (pyrazole: 185.1 ± 2.3 kJ mole^?, imidazole: 133.0 ± 1.7 kJ mole^?1) have been derived. Several energy values related to the molecular structure of these two compounds (as resonance energy, enthalpy of isomerization, …) have been determined. The study of pyrazole has enabled us to contribute to the evaluation of some characteristics of the NN bond.     

Study on thermodynamic properties of glyphosate by oxygen-bomb calorimeter and DSC

The combustion enthalpy of glyphosate was determined by XRY-1C oxygen-bomb calorimeter at a constant volume. The standard mole combustion enthalpy and the standard mole formation enthalpy have been calculated to be ?1702.19 and ?1478.36 kJ mol^?1, respectively. For testing the reliability of instrument, glycine and naphthalene were used as reference materials by comparing the measured values with the literature values, the absolute error and relative error are 2.58 kJ mol^?1 and 0.26 % for glycine, respectively, and these of naphthalene are 4.08 kJ mol^?1 and 0.08 %, respectively. Moreover, the constant-pressure heat capacities c _p of glyphosate were measured by differential scanning calorimetry in the temperature range 303.15–365.15 K, and the relationship between c _p and temperature was established. These related studies can provide a thermodynamic basis for their further application.     

1,2,4-Triazole as a reference material for combustion calorimetry of N-containing compounds

A micro-bomb combustion calorimeter recently designed for samples of mass  ≈ 80 mg has been improved and tested with m -methoxybenzoic acid in order to verify the chemistry of the combustion process and the accuracy of the energy corrections involved in the analysis of results. From measurements in this calorimeter, the standard massic energy of combustion of 1,2,4-triazole was determined to beΔ_cu^o =  − (19200.3  ±  3.4)J · g ^− 1. Some new measurements with our macro combustion calorimeter confirm an earlier result from this laboratory of  − (19203.1  ±  1.2)J · g ^− 1. Determination of the purity by d.s.c. of 1,2,4-triazole purified some 10 years ago reveals that samples of this compound remained unchanged and suggest that 1,2,4-triazole be used as a possible reference material for organic compounds with a high content of nitrogen. From the experimental results with the micro-bomb combustion calorimeter, the actual and earlier results from macro-bomb combustion calorimetry, and those obtained in other laboratories, the standard massic energy of combustion of 1,2,4-triazole was deduced to beΔ_cu^o =  − (19202.5  ±  1.7)J · g ^− 1.     

Energy Properties and Biomass Yield of Miscanthus x Giganteus Fertilized by Municipal Sewage Sludge

The application of municipal sewage sludge as fertilizer in the production of non-food energy crops is an environmentally and economically sustainable approach to sewage sludge management. In addition, the application of municipal sewage sludge to energy crops such as Miscanthus x giganteus is an alternative form of recycling nutrients and organic material from waste. Municipal sewage sludge is a potential source of heavy metals in the soil, some of which can be removed by growing energy crops that are also remediation agents. Therefore, the objective of the research was to investigate the effect of municipal sewage sludge applied at three different rates of 1.66, 3.22 and 6.44 t/ha on the production of Miscanthus. Based on the analyses conducted on the biomass of Miscanthus fertilized with sludge from the wastewater treatment plant in three fertilization treatments, it can be concluded that the biomass of Miscanthus is a good feedstock for the process of direct combustion. Moreover, the application of the largest amount of municipal sewage sludge during cultivation had no negative effect on the properties of Miscanthus biomass. Moreover, the cellulose and hemicellulose content of Miscanthus is ideal for the production of second-generation liquid biofuels. Fertilizer treatments had no effect on the content of cellulose and lignin, while a significant statistical difference was found for hemicellulose.     

Design of an experimental procedure for energy evaluation from biomass

The rational and sustainable exploitation of nature resources is one of the priority objectives of our society. In this article a method is proposed to evaluate and exploit the energetic resources contained in different forest formations. This method is based on the use of a combustion bomb calorimeter to determine the calorific values of the different samples studied. These results were complemented with chemical analysis of the samples and with environmental and geomorphological studies of the zones were samples were taken. The results obtained during the last 3 years for the residual biomass originated from the forest formations existing in Galicia ensure the reliability and usefulness of the method that can be extended to any forest formation all over the world.     

The Intermediate Level Liquid Molybdenum-99 Waste Treatment Process at the Australian Nuclear Science and Technology Organisation

ANSTO manufactures ⁹⁹Mo for radiopharmaceutical use. Alkaline Intermediate Level Liquid Waste (ILLW) from this process, plus legacy acidic waste, are planned to be treated by converting both wastes into stable, solid, waste forms with oxide-basis loadings of 25-35 wt% and 30-50 wt%, respectively. The hot-cell plant design utilises the same unit process steps to treat both wastes. Hot-Isostatic Pressing (HIP) is employed to consolidate the processed waste and achieve substantial waste volume reductions compared to a cementation option. In this paper an overview of the treatment process and selected waste forms for ANSTO's ⁹⁹Mo production ILLW is given.     

Radiochemical analyses for the defense waste processing facility startup at the Savannah River Site

Highly radioactive waste from defense-related activities at the Savannah River Site in South Carolina are to be incorporated into a borosilicate glass in the Defense Waste Processing Facility (DWPF) for long-tem geological isolation. Processing and repository safety considerations require the determination of 24 radioisotopes that meet the reporting criteria. These isotopes include fission products, activation products, and daughter nuclei that grow into the waste. Four isotopes,¹³⁷Cs,⁹⁰Sr,²³⁸Pu and²³⁸U will be routinely measured in the DWPF operation for process control. This work shows that the concentrations of the other 20 reportable radioisotopes in the final glass product can be predicted from a thorough characterization of the high level waste (HLW) tanks and a knowledge of the concentrations of the major non-radioactive components in the vitrification process.     

Kinetics investigation on the combustion of waste capsicum stalks in Western China using thermogravimetric analysis

The combustion kinetics of waste capsicum stalk (WCS) in Western China is investigated through thermogravimetric analysis compared with sawdust and coal, and co-combustion of WCS with coal is also investigated. Results show that the ignition characteristics of WCS is better than that of sawdust and coal, and the activation energy E of WCS-volatile combustion and WCS-char combustion are 78.55?kJ?mol^?1 and 44.59?kJ?mol^?1. However, integrating the characteristics of ignition and burnout, the combustion characteristic factor (S _N) of WCS is lower than that of sawdust. With the increasing in the heating rate, the ignition of WCS is delayed. Oxygen concentration $ C_{{{\text{O}}_{2} }} $ affects E and k ₀ of volatile combustion largely under rich-oxygen condition, when $ C_{{{\text{O}}_{2} }} $ increases from 0.2 to 0.8, E has increased threefold and k ₀ also intensively increases from 10⁶ to 10¹³?C10²². Oppositely, effect of $ C_{{{\text{O}}_{2} }} $ on the E and k ₀ of char combustion is little, and there is an exponential relationship $ S_{\text{N}} = 7. 1 2 8 \times 10^{ - 9} \times { \exp }(C_{{{\text{O}}_{2} }} /0. 3 6 8) - 6. 1 2 6 \times 10^{ - 9} $ between S _N and $ C_{{{\text{O}}_{2} }} $ . For the tests of co-combustion, all the experimental and weighted-average curves coincide well, and there is no remarkable synergistic effect. With the increase of mixing ratio that WCS added, E and k ₀ of volatile combustion increase, but correspondingly E and k ₀ of char combustion decrease.     

Construction,calibration and testing of a micro-combustion calorimeter

An isoperibolic micro-combustion calorimeter was designed, built and set up in our laboratory, taking as base a 1107 Parr combustion bomb of 22 cm³ of volume. Taken into account the geometrical form of the bomb, it was designed and constructed a vessel and a submarine chamber in brass. All of the pieces of the calorimeter were chromium-plated to reduce heat loss by radiation. The calorimeter was calibrated by using pellets of standard benzoic acid (mass approximate of 40 mg) leading to the energy equivalent of ε(calor) = (1283.8 ± 0.6) J · K⁻¹. In order to test the calorimeter, combustion experiments of salicylic acid were performed leading to a value of combustion energy of Δ_cu^∘ = −(21,888.8 ± 10.9) J · g⁻¹, which agrees with the reported literature values. The combustion of piperonylic acid was carried out as a further test leading to a value of combustion energy of Δ_cu^∘ = −(20,215.9 ± 10.4) J · g⁻¹ in accordance with the reported literature value. The uncertainty of the calibration and the combustion of salicylic acid and piperonylic acid was 0.05%.     

Waste and fuels from waste

Thermogravimetric studies provide the basis for qualification of materials and suitability of biomass fuels and fuels formed from waste to convert them into fuel gas generated in the generator process. The paper presents the results of the analysis of thermal decomposition (thermogravimetric research) of fuel from waste, sewage sludge and wastes from the agro-food: potato pulp and rapeseed meal. Studies have shown how some biofuels and fuel formed from waste reach the semi-coke and coke structure, which is important later, in modeling industry degassing process. The most effective seems to be using rapeseed meal in generator process, since the thermal decomposition occurs in the form of transformation in the temperature range 200?C500?°C. On the basis of quantity analysis of gaseous transformation products from the above mentioned transformations, the calorific value of after process gases has been calculated. The highest calorific value is represented by a gas resulting from rapeseed meal pyrolysis ~10,040?kJ/Nm³. The solid residue obtained by dry decomposition of potato pulp has the highest energy value when compared with products from other fuels.