Influence of the Heat Loss on the Performance of a Two-stage Gasification Reactor

This paper investigates the gasification efficiency of a two stage gasifier, described in all detail in previous works, as a function of the heat loss across the reactor walls. The behaviour of the reactor was simulated using a simple mathematical model already reported in previous papers. The examined heat loss ranges from 0% of the heat produced by the exothermic reactions into the reactor, up to 20%. Calculations have been performed by keeping constant both the injected total oxygen and its partition between the two stages, while different feedstocks have been used, such as landfill gas, municipal solid waste (MWS), willow and rice straw. The results of calculation show that the gasification efficiency at fixed oxygen injection is greatly influenced by the feedstock. The elaboration of the obtained data indicates also that the trend of the gasification efficiency vs. heat loss is a function of the high heating value of the feedstock and of the ratio between the oxygen present into the reactor (injected + the one of the feedstock) and the stoichiometric oxygen necessary to transform the feeding into carbon dioxide and steam.

ANALISIS NILAI KALOR DAN LAJU PEMBAKARAN BRIKET TONGKOL JAGUNG SEBAGAI SUMBER ENERGI ALTERNATIF

ABSTRAKTujuan dari penelitian ini yaitu untuk menghasilkan briket tongkol jagung sebagai alternative sumber energi yang memiliki nilai kalor yang tinggi. Briket tongkol jagung dibuat dari tongkol jagung yang sudah dikeringkan dan dihaluskan sebelumnya dengan ukuran 20 mesh. Masing-masing perlakuan dicetak dengan variasi persentase perekat tepung tapioka yaitu 5%, 10%, dan 15%. Selain variasi perekat dilakukan juga variasi tekanan pembentukannya untuk melihat komposisi terbaik yang menghasilkan nilai kalor yang tinggi dan laju pembakaran yang sesuai. Briket selanjutnya diuji nilai kalor dan laju pembakarannya dengan menggunakan alat bom calorimeter. Hasil penelitian menunjukkan bahwa secara berturut-turut nilai kalor dan laju pembakaran briket dengan persentase komposisi perekat 5%, 10%, 15% yaitu 21,00 kJ, 22,68 kJ, 31,08 kJ, dan 12,00 gram/menit, 13,33 gram/menit, 13,50 gram/menit. Hasil terbaik dihasilkan pada komposisi persentase perekat 15% dengan nilai kalor mencapai 31,08 kJ, dan laju pembakaran 13,50 gram/menit yang tidak terlalu jauh meningkat dibandingkan dengan komposisi persentase perekat lainnya. Kata kunci: briket; tongkol jagung; nilai kalor; laju pembakaran ABSTRACTThe purpose of this research is to produce corn cobs briquettes as an alternative energy source that has a high calorific value. Corn cobs briquettes are made from corn cobs that have been dried and previously mashed with a size of 20 mesh. Each treatment was printed with variations in the percentage of tapioca starch adhesive, namely 5%, 10%, and 15%. In addition to variations of the adhesive, variations in the formation pressure were also carried out to see the best composition that produced a high heating value and an appropriate combustion rate. The briquettes were then tested for calorific value and rate of combustion using a bomb calorimeter. The results showed that the calorific value and burning rate of briquettes with the percentage of adhesive composition 5%, 10%, 15%, were 21.00 kJ, 22.68 kJ, 31.08 kJ, and 12.00 gram/minute, respectively. 13.33 grams/minute, 13.50 grams/minute. The best results were obtained at 15% adhesive percentage composition with a calorific value of 31.08 kJ, and a burning rate of 13.50 gram/minute which was not significantly increased compared to other adhesive percentage compositions. Keywords: briquettes; corn cobs; calorific value; combustion rate

Study of making coal water slurry with lignite Pendopo coal

The Coal Water Slurry (CWS) technology increases the calorific value and changes the phase of coal from solid to liquid. The CWS Plant with a coal capacity of 1.4 t/hour located at Karawang, West Java converts lignite coal to CWS. Coal undergoes pulverizing, upgrading, and slurry-making processes to become CWS. Pulverization is the process of refining coal size into 200 mesh. The upgrading process is through reducing the moisture content in heat exchangers (HE). It occurs in HE where the coal is pressurized to 15 MPa and the temperature is maintained at 330 0C for 30 minutes. The research objective was to determine the CWS characteristics of the South Sumatra Pendopo lignite coal. The method used is through testing where the Pendopo coal is converted into CWS at the CWS Plant. The result shows that Pendopo coal which has a heating value of High Heating Value (HHV) 2,725.00 kCal/kg As Received (AR) has an increase in HHV heating value of 3,218.00 kcal/kg AR when it becomes CWS. The total moisture content of Pendopo coal has decreased from 49.36% to 44.58% when it becomes CWS. The fixed carbon content of Pendopo coal increased from 19.78% AR to 24.01% AR.

Energetic Valorization of Solid Wastes from the Alcoholic Beverage Production Industry: Distilled Gin Spent Botanicals and Brewers’ Spent Grains

In this paper, the authors assess the possibilities of energetic valorization for two solid wastes from alcoholic beverage production. Distilled gin spent botanicals (DGSB) and brewers’ spent grains (BSG) are tested, both by themselves and as co-substrates, for their possibilities as substrates for anaerobic digestion in a system of box-type digesters, suited for the process. While BSGs show a good performance for anaerobic digestion, DGSBs, despite showing an acceptable biomethanogenic potential result as not suitable for the process. Experiments using DGSBs as substrate in the reactors result in failure. And, as a co-substrate, the biomethanogenic digestion process appears to be hampered and lagged. Possible explanations for this behavior are explored, as well as other possibilities for the use of the material as a power source given its high heating value.

Biocrude Production from Hydrothermal Liquefaction of Chlorella: Thermodynamic Modelling and Reactor Design

Hydrothermal liquefaction can directly and efficiently convert wet biomass into biocrude with a high heating value. We developed a continuous hydrothermal liquefaction model via Aspen Plus to explore the effects of moisture content of Chlorella, reaction pressure and temperature on thermodynamic equilibrium yields, and energy recoveries of biocrude. We also compared the simulated biocrude yield and energy recoveries with experiment values in literature. Furthermore, vertical and horizontal transportation characteristics of insoluble solids in Chlorella were analyzed to determine the critical diameters that could avoid the plugging of the reactor at different flow rates. The results showed that the optimum moisture content, reaction pressure, and reaction temperature were 70–90 wt%, 20 MPa, and 250–350 °C, respectively. At a thermodynamic equilibrium state, the yield and the energy recovery of biocrude could be higher than 56 wt% and 96%, respectively. When the capacity of the hydrothermal liquefaction system changed from 100 to 1000 kg·h−1, the critical diameter of the reactor increased from 9 to 25 mm.

Carbon storage and energy production of Eucalyptus urophylla developed in dryland ecosystems at East Nusa Tenggara

The development of Eucalyptus urophylla in dryland ecosystems plays an important contribution to support climate change mitigation and renewable energy diversification. However, the information about the potential of E. urophylla for carbon reduction and energy production is rarely documented, even though it is necessary as fundamental considerations to determine the best strategy for sustainable natural resources management, primarily in dryland ecosystems. This study aimed to quantify the carbon storage and energy production of E. urophylla established in dryland ecosystems at East Nusa Tenggara. The study site is located in a eucalyptus plantation managed by Timor Tengah Selatan Forest Management Unit. Destructive sampling was conducted on 25 sample trees that were evenly distributed from small to big ones. The percentage of carbon content in every tree component, namely stem, branch, and foliage, was determined using elemental analysis, while the calorific value of each tree component was analyzed using a bomb calorimeter. Carbon storage in each component was calculated by multiplying biomass and the percentage of carbon content, while the energy production was computed by multiplying high heating value and biomass from every tree component. The results found the mean carbon storage of E. urophylla in the study site was 55.51 kg tree-1 with a minimum of 6.34 kg tree-1 and a maximum of 184.76 kg tree-1. The percentage of carbon content in the foliage was lower than other tree components by approximately 34.1%. Interestingly, the calorific value of foliage was relatively higher than stem and branch with around 5,252 kcal kg-1. The energy production of E. urophylla ranged from 252.6 to 7,813.3 MJ tree-1 with an average of 2,357.87 MJ tree-1. According to the results, this study concluded the development of E. urophylla in dryland ecosystems demonstrated a meaningful contribution to carbon absorption and energy production at East Nusa Tenggara.

Investigation of the Characteristics of Catalysis Synergy during Co-Combustion for Coal Gasification Fine Slag with Bituminous Coal and Bamboo Residue

As a kind of solid waste from coal chemical production, the disposal of coal gasification fine slag poses a certain threat to the environment and the human body. It is essential for gasification slag (GS) to realize rational utilization. GS contains fewer combustible materials, and the high heating value is only 9.31 MJ/Kg, which is difficult to burn in combustion devices solely. The co-combustion behavior of the tri-fuel blends, including bituminous coal (BC), gasification slag (GS), and bamboo residue (BR), was observed by a thermogravimetric analyzer. The TGA results showed that the combustibility increased owing to the addition of BC and BR, and the ignition and burnout temperatures were lower than those of GS alone. The combustion characteristics of the blended samples became worse with the increase in the proportion of GS. The co-combustion process was divided into two main steps with obvious interactions (synergistic and antagonistic). The synergistic effect was mainly attributed to the catalysis of the ash-forming metals reserved with the three raw fuels and the diffusion of oxygen in the rich pore channels of GS. The combustion reaction of blending samples was dominated by O1 and D3 models. The activation energy of the blending combustion decreased compared to the individual combustion of GS. The analysis of the results in this paper can provide some theoretical guidance for the resource utilization of fine slag.

Medical Peat Waste Upcycling to Carbonized Solid Fuel in the Torrefaction Process

Peat is the main type of peloid used in Polish cosmetic/healing spa facilities. Depending on treatment and origin, peat waste can be contaminated microbiologically, and as a result, it must be incinerated in medical waste incineration plants without energy recovery (local law). Such a situation leads to peat waste management costs increase. Therefore, in this work, we checked the possibility of peat waste upcycling to carbonized solid fuel (CSF) using torrefaction. Torrefaction is a thermal treatment process that removes microbiological contamination and improves the fuel properties of peat waste. In this work, the torrefaction conditions (temperature and time) on CSF quality were tested. Parallelly, peat decomposition kinetics using TGA and torrefaction kinetics with lifetime prediction using macro-TGA were determined. Furthermore, torrefaction theoretical mass and energy balance were determined. The results were compared with reference material (wood), and as a result, obtained data can be used to adjust currently used wood torrefaction technologies for peat torrefaction. The results show that torrefaction improves the high heating value of peat waste from 19.0 to 21.3 MJ × kg−1, peat main decomposition takes place at 200–550 °C following second reaction order (n = 2), with an activation energy of 33.34 kJ × mol−1, and pre-exponential factor of 4.40 × 10−1 s−1. Moreover, differential scanning calorimetry analysis revealed that peat torrefaction required slightly more energy than wood torrefaction, and macro-TGA showed that peat torrefaction has lower torrefaction constant reaction rates (k) than wood 1.05 × 10−5–3.15 × 10−5 vs. 1.43 × 10−5–7.25 × 10−5 s−1.

Determination of Time-to-ignition and Flaming Duration of Biomasses in a Muffle Furnace

Measuring the energy characteristics of solid biofuels can help to determine the most suitable species for combustion. The objective of this study is to propose a new methodology for determining the ignition time and flaming duration in lignocellulosic biomass. A muffle furnace was used, instead of an epiradiador, to measure the variables. The optimal oven temperature was defined according to the average time-to-ignition of biomasses in the literature. Ten biomasses were analyzed to obtain their high heating value, volatile matter, fixed carbon content, ash content, time-to-ignition, and flaming duration. The results showed a high correlation between the biomass volatile content, time-to-ignition, and flaming duration. In the literature, it is described that high levels of volatile materials accelerate the ignition of the material. Thus, the association between the volatile matter and the variables analyzed justifies the use of the muffle furnace methodology. Furthermore, biomasses with high levels of volatile matter have longer flaming durations than other solid biofuels.