Experimental and Modelling Analysis of Char Decomposition: Experiences with Real Scale Gasification Systems

Abstract The main issue to be faced when dealing with gasification processes is the removal of tars in order to obtain a good quality producer gas for later use, either as energy vector or for production of chemicals. Char has been observed to have a high potential for catalytic tar reduction, but the properties that promote this activity are still being investigated. An understanding of the mechanisms involved in the process of tar removal is needed, including the deactivation of the char as a catalyst and its degradation. This work addresses the process of thermal decomposition of char with different operating conditions and under inert atmosphere (N 2 ), in order to determine the mass loss occurring under high temperature treatment. For this purpose, chars collected from local gasification plants have been used. Firstly, a complete characterization of the chars has been carried out to determine their composition, heating value and BET surface area. Secondly, thermogravimetric analyses have been used to calibrate a one-step kinetic model for describing the kinetics involved in the process of char thermal decomposition. The coupling of the kinetics with a CFD model allowed then to consider mass, heat, and momentum transfer phenomena, and to quantitatively estimate the decomposition in a fixed-bed test reactor. The model, whose results have been compared to reference experimental tests, predicts satisfactorily the thermal behavior of the char inside the reactor and its mass loss

Gasification Char as a Potential Substitute of Activated Carbon in Adsorption Applications

Abstract This study points out the similarities between char from biomass gasification and activated carbon and reviews its successful applications in the field of adsorption. Surface area (S BET ) is considered as the standard parameter. Since only few data on biomass gasification char are available in the literature, in this work char residues from different commercial gasification plants were collected and characterized, reporting their S BET values for comparison. The highest values for S BET are associated to dual-stage gasification technologies and are highly affected by the operating temperature

Building Simulation Applications BSA 2015 - Proceedings of 2nd IBPSA-Italy conference

Building Simulation Applications 2015 was the second IBPSA-Italy regional conference on building performance simulation, which took place for the second time at the Free University of Bozen/Bolzano from 4 to 6 February 2015. Almost 100 attendees, 198 authors, 67 presentations, and 4 keynote speakers confirmed not only the interest in building simulation, but also the enhancement of the level of detail, the extension of the size and application range of the domain of investigation and the increase in the level of accuracy and generality of the results. In particular, four sections were devoted to the detailed modelling of phenomena and components (advanced modelling, solar radiation, energy systems and envelope modelling), three to the integrated and non-energy performance analysis (lighting and user behavior), three to the optimization techniques for high performance buildings and retrofit, and two to the development and validation of new tools

Building Simulation Applications BSA 2019 - Proceedings of 4th IBPSA-Italy conference

Unlike the previous editions,the fourth Building Simulation Applications BSA 2019 Conference took place in June, from 19th to 21st, instead of during the winter period. For the biennial conference hosted by the Free University of Bozen-Bolzano, IBPSA Italy had to double its efforts, considering its concurrent commitment to the organization of Building Simulation 2019 in Rome. Even so, BSA 2019 featured more than 60 participants and around 130 different authors, with a significant presence of delegates from abroad and, in particular, from Austria. A different review process was introduced, with the full paper submission and review following the conference. Based on this, only 40 out of the 54 works presented during the conference in two parallel sessions were accepted for inclusion in this proceedings book

Common reeds (Phragmites australis) as sustainable energy source: experimental and modelling analysis of torrefaction and pyrolysis processes

The aim of this study is to apply advanced analytical techniques and kinetic modelling to common reeds (Phragmites australis) to characterize its pyrolysis and torrefaction as possible environmental friendly and sustainable pathways of fuel upgrading. Simultaneous thermogravimetric and differential scanning calorimetry analysis have been carried out on common reeds. The evolved gases during the decomposition process have been analysed by a coupled infrared gas analyser and gas chromatograph/mass spectrometer. Different reed origins (China and Italy) and plant parts (stem and leaves) have been compared. The results have been used to calibrate a torrefaction kinetic model. The model has also been tested simulating a reed torrefaction run occurring in a bench-scale apparatus, supplementing the chemical analysis with a thermal simulation of the reactor carried out through a finite elements approach. The results show that the proposed modelling approach allows the prediction of the reaction products with a satisfying degree of accuracy. Besides its phytodepuration potential, P. australis has proven to be an interesting natural biomass resource for thermochemical conversion processes and energy production both for its suitability and availability

experimental and modeling analysis of air and co2 biomass gasification in a reverse lab scale downdraft gasifier

Abstract This research work aims at investigating the effect of carbon dioxide feed in biomass gasification as a possible way to directly exploit the exhaust gas from the engine of combined heat and power systems to convert carbon dioxide to carbon monoxide via Boudouard reaction and consequently increase the carbon conversion and reduce char yield. The effects on biomass gasification using air, and air diluted with carbon dioxide were assessed in a reverse downdraft lab-scale gasifier utilizing 2 kg of pelletized biomass. This reactor is mounted on a digital weighing balance which enables the recording of mass loss during the gasification process. Furthermore, the mixture of air and CO2 is obtained from two mass flow controllers which enable constant and desired flux of gasifying agents across the gasifier. At the same time, an in-house developed thermodynamic equilibrium model was applied to predict the gas composition and char output. Unlike the classical equilibrium strategy that calculates the gasification products using the Gibbs energy minimization method at fixed temperature and pressure, the current approach is based on the enthalpy of the reactants, analogous to the adiabatic combustion temperature. Also, a correction factor accounting for the heat losses, was implemented. The model outcome shows a good agreement with the experimental results, especially in terms of predicted char yields and trends of the dominant producer gas species. The same strategy was used to describe the behavior of the gasification system and estimate the quality of producer gas and the cold gas efficiency of the system

Building Simulation Applications BSA 2017 - Proceedings of 3rd IBPSA-Italy conference

Building Simulation applications (BSA) 2017 was the third IBPSA-Italy conference on building performance Simulation to take place at the Free University of Bozen-Bolzano, from 8th to 10th February 2017. The main topics dealt with were the impact of micro-climate conditions on building performance, detailed modelling of physical phenomena and building system components, optimization techniques for high performance buildings, energy retrofit and advanced HVAC controls, integrated performance analysis, and visual and thermal comfort assessment.It featured more than 100 participants and more than 75 presentations, about 40 % of which from abroad – Austria, US, South Korea, Ireland, Switzerland and the UK, among the first contributors. In addition, besides researchers, it also hosted a half-day special roundtable discussion about the potential and limitations of a set of simulation tools, attended by about 80 practitioners, to discuss the opportunities opened up to professionals by the use of building simulation, as well as the main barriers preventing its broader diffusion

Synthesis of char-based acidic catalyst for methanolysis of waste cooking oil: an insight into a possible valorization pathway for the solid by-product of gasification

Gasification-based char from a commercial small-scale gasification plant was converted into an acidic catalyst for methanolysis of waste cooking oil (WCO). The char-based acidic catalyst was synthesized by the sulfonation of gasification char with sulfuric acid. Functional groups, acid density, morphological and surface properties were characterized and measured by using Fourier transform infrared red spectroscopy, ammonia temperature programmed desorption, field emission scanning electron microscope and Brunauer-Emmett-Teller, respectively. Wood char based acid catalyst showed higher surface area of 337 m2/g and acid density of 2.94 mmol/g. The reaction variables such as methanol/oil molar ratio, catalyst loading, reaction time and temperature, were studied. The optimum reaction conditions, 9:1 methanol/oil ratio, 6 wt% catalyst loadincxg, 130 min reaction time at 65 °C, gave 96% of ester conversion. The recovered catalyst was washed and reused without any activation (calcination), still giving 81% of ester conversion after five reaction cycles. Furthermore, fuel properties of WCO methyl esters were determined as per the ASTM and EN biodiesel standards. The utilization of char from biomass gasification for the synthesis of an acid catalyst for biodiesel production allows achieving a twofold objective. On the one side, the valorization of a material which is presently wasted. On the other side, the production of a catalyst that can effectively convert WCO into biodiesel in a single step process, therefore allowing a simplified procedure and lower operational temperatures. In addition, the obtained catalyst showed an interesting efficiency in decreasing free fatty acid of WCO and a considerable recyclability of the catalyst

Hydrothermal carbonization of off-specification compost: A byproduct of the organic municipal solid waste treatment

International audienceh i g h l i g h t s HTC of off-specification compost at 180, 220, 250 °C and 1, 3, 8 h reaction time RT. The increase in hydrochar HHV with respect to raw feedstock from 7% to 61%. Hydrochar elemental composition similar to that of peat and lignite for T = 250 °C. Hydrochar thermal stability greatly increased at T = 250 °C and at T = 220 °C when RT = 8 h. HTC results were highly dependent on T, while the effect of RT was much lower. a b s t r a c t The possibility to apply the hydrothermal carbonization (HTC) process to off-specification compost (EWC 19.05.03) at present landfilled was investigated in this work. The aim was to produce a carbonaceous solid fuel for energy valorization, with the perspective of using HTC as a complementary technology to common organic waste treatments. Thus, samples of EWC 19.05.03 produced by a composting plant were processed through HTC in a batch reactor. Analytical activities allowed to characterize the HTC products and their yields. The hydrochar was characterized in terms of heating value, thermal stability and C, H, O, N, S and ash content. The liquid phase was characterized in terms of total organic carbon and mineral content. The composition of the gas phase was measured. Results show that the produced hydrochar has a great potentiality for use as solid fuel

Techno-economic assessment of turning gasification-based waste char into energy : a case study in South-Tyrol

In the South-Tyrol region (Italy), 46 gasifiers are currently operating and €200,000 are annually paid to dispose of as a waste 1300 tons of char. Therefore, there is a considerable interest in finding alternatives for the valorization of this solid by-product. The aim of this work is to assess the potential of char as energy source and to compare two scenarios. The first scenario considers the possibility of exploiting char in a dedicated burner integrated in the gasification plant. The second scenario assumes that all the char is collected from South-Tyrol and co-fired with biomass in an existing combustion-ORC plant. An economic analysis was performed evaluating the discounted payback time and both scenarios were modeled using Aspen Plus®. The results reveal that substantial savings in the operating costs of the plants can be achieved. In the first scenario the owners of the gasification plants could save from 50% to 94% of the char disposal costs with a payback time ranging between 3 and 7 years. In the second scenario, the owner of the plant could save approximately €235k per year with a payback time of approximately 7 years. The present study provides a basis for further techno-economic studies on char combustion. The results can be helpful for the owners of the gasification plants in determining the most cost-effective way to dispose char and to avoid disposing it of as a waste. Furthermore, it is demonstrated how char could be used as a renewable fuel, with better performance than raw biomass