Plasma Gasification Process Research Articles

Plasma gasification of carbonaceous wastes: thermodynamic analysis and experiment

Thermodynamic calculations of the plasma gasification process of carbonaceous wastes in air and steam ambient were carried out. A maximum yield of synthesis gas in such processes is predicted to be achieved at a temperature of 1600 K. On a specially developed plasma facility, plasma gasification experiments were performed for carbonaceous wastes. From the organic mass of carbonaceous waste and from its mineral mass, respectively, a high-calorific syngas and a neutral slag consisting predominantly of ferric carbide, calcium monosilicate, silica and iron, were obtained. A comparison between the experiment and the calculations has shown a good consistency between the data.

A review on plasma gasification for solid waste disposal

In this paper a brief review on plasma gasification as a new technology for solid waste disposal is presented. Plasma gasification systems can handle not only biomass but also harmful wastes which can be completely converted into outputs having considerable amounts of useful energy content. There are a variety of plasma gasification systems which have different design and operation characteristics with the utilization of a great range of fuels. The operation and performance evaluation of a plasma gasification system in turn is specified by the required outputs. There is a need for a common approach as a function of fuel, system and process characteristics. Furthermore thermodynamic analysis of plasma gasification process is still one of the current research topics due to the missing general theoretical treatment and terminology compatible for all of the systems. A critical analysis on the available literature in this respect provides a solid contribution to the state of art. An experimental research on the design and performance of a plasma gasification system “MCw gasifier” is on site to fill the determined major gaps of the literature which are outlined in this paper.

Feasibility test of agricultural residues through characterization for utilization in plasma gasification

Agricultural residues were characterized to determine their feasibility as feedstock for plasma gasification. Husk, stalk, straw and shell were selected for the study and proximate analysis, elemental composition analysis, thermal value analysis were carried out using standard procedures. Producer gas generated from these bio-residues is well suited for plasma gasification process where the working temperature is between 1200-2000ºC. These substances have moisture content in the range of 5-12%, and volatile matter content of 58-70%, offering good burning characteristics and conversion to electricity. The fixed carbon content of 13 to 20% contributes significantly to its calorific value. The average calorific value of selected agricultural residues (18.27 MJ/kg) was higher than the calorific value of feedstock (12 to 16 MJ/kg) used in plasma gasification, thus reinforcing their suitability further. It was found that selected agricultural residues could be adopted and promising fuel for plasma generation and deserve further development as a sustainable and renewable alternative.

Numerical Simulation of Thermal Plasma Gasification Process

Numerical analysis of plasma gasification process was carried out base on the combination of magnetohydrodynamics (MHD) and computational fluid dynamics (CFD). A two stage gasification system which consists of a heater and a plasma rector was used to enhance syngas production in the present work. Nitrogen thermal plasma jet generated by a low power plasma torch was analyzed by a self-developed MHD code, and complex thermal flow field in the plasma reactor was simulated with a commercial CFD code. The accuracy of numerical simulation was confirmed from the comparison between numerical results and experimentally measured data of arc voltage and reactor temperature. From the numerical analysis, a high temperature for the thermal cracking of methane was expected in the upper region of the plasma reactor.

Gasification of corn cob using non-thermal arc plasma

With high quality syngas consisting almost completely of H2 and CO, and solid carbon residues with high quality, the plasma treatment technology of biomass has been widely studied with the purpose of generating hydrogen. In this paper, the plasma gasification process of corn cob using non-thermal arc plasma was investigated after comparing various components of biomass, combining the physical truth of agricultural waste. The gas yield can reach 79.0% of the biomass feed without drying conditions at a discharge power of 25.2 W when using nitrogen as carrier gas with energy cost from the decomposition of corn cob is 5328 kJ/kgH2. Meanwhile, carbon conversion rate of 82.9%, CO selectivity of 39.9% and a ratio of H2/CO greater than 1.5 are obtained. It is found that different carrier gases have different impacts upon the reforming performance, and air is more beneficial for higher gas yield and CO selectivity. Besides, the presence of moisture is conducive to improve the gas yield, especially the production of hydrogen, carbon conversion rate and the molar ratio of H2/CO. Also, the varying tendencies of the gas products over the time at different experiment parameters are also discussed. Finally, the results of residual solid products were analyzed.

Plasma gasification of refuse derived fuel in a single-stage system using different gasifying agents

The renewable evolution in the energy industry and the depletion of natural resources are putting pressure on the waste industry to shift towards flexible treatment technologies with efficient materials and/or energy recovery. In this context, a thermochemical conversion method of recent interest is plasma gasification, which is capable of producing syngas from a wide variety of waste streams. The produced syngas can be valorized for both energetic (heat and/or electricity) and chemical (ammonia, hydrogen or liquid hydrocarbons) end-purposes. This paper evaluates the performance of experiments on a single-stage plasma gasification system for the treatment of refuse-derived fuel (RDF) from excavated waste. A comparative analysis of the syngas characteristics and process yields was done for seven cases with different types of gasifying agents (CO2+O2, H2O, CO2+H2O and O2+H2O). The syngas compositions were compared to the thermodynamic equilibrium compositions and the performance of the single-stage plasma gasification of RDF was compared to that of similar experiments with biomass and to the performance of a two-stage plasma gasification process with RDF. The temperature range of the experiment was from 1400 to 1600K and for all cases, a medium calorific value syngas was produced with lower heating values up to 10.9MJ/Nm3, low levels of tar, high levels of CO and H2 and which composition was in good agreement to the equilibrium composition. The carbon conversion efficiency ranged from 80% to 100% and maximum cold gas efficiency and mechanical gasification efficiency of respectively 56% and 95%, were registered. Overall, the treatment of RDF proved to be less performant than that of biomass in the same system. Compared to a two-stage plasma gasification system, the produced syngas from the single-stage reactor showed more favourable characteristics, while the recovery of the solid residue as a vitrified slag is an advantage of the two-stage set-up.

Environmental and economic performance of plasma gasification in Enhanced Landfill Mining

This paper describes an environmental and economic assessment of plasma gasification, one of the viable candidates for the valorisation of refuse derived fuel from Enhanced Landfill Mining. The study is based on life cycle assessment and life cycle costing. Plasma gasification is benchmarked against conventional incineration, and the study indicates that the process could have significant impact on climate change, human toxicity, particulate matter formation, metal depletion and fossil depletion. Flue gas emission, oxygen usage and disposal of residues (plasmastone) are the major environmental burdens, while electricity production and metal recovery represent the major benefits. Reductions in burdens and improvements in benefits are found when the plasmastone is valorised in building materials instead of landfilling. The study indicates that the overall environmental performance of plasma gasification is better than incineration. The study confirms a trade-off between the environmental and economic performance of the discussed scenarios. Net electrical efficiency and investment cost of the plasma gasification process and the selling price of the products are the major economic drivers.

Tar evolution in a two stage fluid bed–plasma gasification process for waste valorization

This work focuses on systematic studies of the plasma reforming of newly evolved vapors from a fluid bed gasifier, and on the resulting evolution of individual gaseous cracking products to hydrogen-rich syngas. The aim of this study is to compare some previously developed mechanisms of thermal cracking and to identify the main elementary reactions and the most sensible ones for tar decomposition in a two-stage process. Evaluation of plasma chemistry is performed by a comparison between experimental data and thermal kinetic predicted results. Distribution analysis of condensable organics shows that for all the representative species, the levels of tars are distinct in the first stage and almost negligible after the plasma treatment. Under the given reaction conditions, the organic cracking products such as methane and C2-species are completely converted to carbon monoxide and hydrogen, and no soot significantly formed. Oxygen atoms initially formed from CO2 were identified as the major active species involved in the oxidative decomposition of hydrocarbon intermediates and soot precursors. As a result, a two-stage system shows better reforming results, large treatment capacity and almost complete carbon conversion.

Preparation of glass–ceramic foams from the municipal solid waste slag produced by plasma gasification process

The glass–ceramic foams were prepared using high content of municipal solid waste (MSW) slag (50–70%) generated by plasma gasification process. Calcium carbonate and sodium borate were used as foaming agent and flux agent, respectively. The effects of different sintering temperature on the density, mechanical strength and crystalline phases were discussed. The results showed that the glass–ceramic foams with 70wt% MSW slag sintered at 920°C exhibited an excellent strength-to-density ratio (crushing strength exceeding 2.5MPa, with a density below 0.3g/cm3), due to the precipitation of micro-crystals. The preparation of foams utilizing high content of MSW slag eliminates the problem of its disposal and displays huge commercial interests.

Hazardous Waste Vitrification by Plasma Gasification Process

Hazardous Wastes Control is one of the major problems of waste management companies and governmentand environment and disposal of such hazardous wastes is critical and problematic. Current method of hazardous waste disposal,which include mass burn or incineration, and landfilling create new problems to the environment. Vitrification of such wastes by thermal plasma gasification process appears to be a solution to hazardous waste disposal that does not create further problems to the environment. The energy generated by plasma arcs has been recently applied to hazardous waste vitrification. The technology involves subjecting waste material to high temperatures with the purpose of immobilizing nonvolatile chemical species into a nonleachable matrix. Plasma arc gasification and vitrification processes are well known for special waste disposal requirements. This paper presents the high tech plasma gasification processas an efficient technological tool for hazardous waste destruction, such as hospital wastes, nuclear wastes, pyrotechnic smoke assemblies, thermal batteries, and other military wastes. Results show that thermal plasma gasification process is effective in hazardous waste vitrification.

Plasma Arc Gasification for Waste Management and Sustainable Renewable Clean Energy Generalization

Plasma gasification in waste to energy is one of the novel applications that were introduced many years ago. Landfill sites and incineration continue to be the primary methods used to dispose wastes with significant negative impact on the environment. Landfill releases methane which is 21 times more dangerous as a greenhouse gas than carbon dioxide. Incineration is often pushed as an alternative to land filling. However, it is a known fact that incinerator ashes are contaminated with heavy metals, unburned chemicals and new chemicals formed during the burning process. These ashes are then buried in landfill or dumped in the environment. Rather than making waste disappear, incinerators create more toxic waste that pose a significant threat to public health and the environment. Sustainable and successful treatment of MSW should be safe, effective, and environmentally friendly. In this application, plasma arc gasifies the carbon-containing materials in the waste to produce synthesis gas (syngas) composed primarily of carbon monoxide and hydrogen, which can be used to produce energy through reciprocating engine generators - gas turbines and steam boilers in integrated gasification combine circle (IGCC), and/or liquid fuels. The in-organic waste materials are vitrified and runs out of the vessel’s bottom as glass-like slag and reusable metal. The double benefit of waste management and energy production is realized from plasma gasification process

Efficiency Evaluation of RDF Plasma Gasification Process

The waste management in Greece is a very important issue by virtue of the increasing of waste material. This paper is concerned with the efficiency evaluation of a plasma gasification process using RDF (Residual Derived Fuel) to produce Syngas. Plasma gasification is an advanced waste management and thermal treatment technology with exceptional environmental and energy performance. This process converts materials such as coal, biomass or other organic waste into carbon monoxide and hydrogen using very high temperatures with an amount of oxygen and/or steam (Leal-Quiros, 2004). Regarding to the previous studies and using a previous thermodynamic chemical equilibrium model, we devised a new to be appropriate for the RDF to study the efficiency of the plasma gasification process. The total amount of waste materials was supposed 300 tn/day and the produced synthesis gas was composed of CO, H2, CH4, H2O, CO2, N2, S and H2S. Then, at constant temperature and humidity parameters and oxygen, using the results of thermodynamic analysis, is calculated the efficiency of the process according to the thermodynamics laws. Conclusively, the thermodynamic modeling of plasma gasification process for the RDF treatment resulted in positive energy values. These energy results, along with the environmental characteristics of the process, demonstrate that the plasma gasification process is very useful technology for waste treatment and electricity production.

Plasma gasification of organic containing substances as a promising way of development of alternative renewable power engineering

The paper deals with perspectives of large-scale implementation of the plasma gasification process of solid organic-containing substances as a source of renewable energy. First of all, such substances as wood waste, agriculture waste, solid household waste are considered. Thanks to the process of the plasma high-temperature gasification the energy of their combustion can be completely converted into the energy of the synthesis gas combustion, which use as a fuel for the combined cycle allows electricity generation with efficiency of ∼60 %. Thus, if the psychogenesis production wastes are considered, this technology enables avoiding additional emission of carbon dioxide into biosphere as for production of biomass from biosphere it is extracted the same amount of carbon dioxide as is emitted at its combustion. The report represents the realized and developing designs of plasma gasification, their advantages and deficiencies.

Plasma gasification process: Modeling, simulation and comparison with conventional air gasification

In this study, two methods of gasification are developed for the gasification of various feedstock, these are plasma gasification and conventional air gasification. The two methods are based on non-stoichiometric Gibbs energy minimization approach. The model takes into account the different type of feedstocks, which are analyzed at waste to energy lab at Masdar Institute, oxidizer used along with the plasma energy input and accurately evaluates the syngas composition. The developed model is applied for several types of feedstock, i.e. waste tire material, coal, plywood, pine needles, oil shale, and municipal solid waste (MSW), algae, treated/untreated wood, instigating air/steam as the plasma gas and only air as oxidizer for conventional gasification. The results of plasma gasification and conventional air gasification are calculated on the bases of product gas composition and the process efficiency. Results of plasma gasification shows that high gasification efficiency is achievable using both tire waste material and coal, also, the second law efficiency is calculated for plasma gasification that shows a relative high efficiency for tire and coal as compare to other feedstock. The average process efficiency for plasma gasification is calculated to be around 42%. On other hand the result of conventional gasification shows an average efficiency of 72%. The low efficiency of plasma gasification suggest that if only the disposal of hazard waste material is considered then plasma gasification can be a viable option to recover energy.

Exergoeconomic analysis of hydrogen production from plasma gasification of sewage sludge using specific exergy cost method

The plasma gasification process appears to be a relatively new technology due to its better efficiency, effectiveness and environmental friendliness. The process can essentially be used for sewage sludge treatment and energy production. In this paper, we investigate a plasma gasification process from the literature for hydrogen production analysis purposes. We use the specific exergy cost (SPECO) method to calculate exergy-related parameters and display cost flows for all streams and components. We also determine exergy destructions and their costs in a more specific form as avoidable and unavoidable exergy destructions. We consider six main components: a plasma gasification furnace, a gas cleaning, syngas compressor, two heat exchangers and a pressure swing adsorption (PSA). We calculate that the PSA has the largest exergy destruction rates with 11.66 MW, followed by the plasma gasification components with 6.55 MW. We also determine exergy efficiencies for these components. The lowest exergy efficiency is 4.43% for the PSA. It is found that the maximum exergy destruction cost rates are 338.75 and 46.92 $/h, for the PSA and plasma gasification furnace, respectively, while the unit cost of hydrogen is 208.6 $/h at the outlet of the PSA. We further investigate exergy destruction rates and investment cost rates through an extended exergy analysis and obtain that for the plasma gasification furnace, the avoidable destruction and investment costs are 15.36 and 8.06 $/h, respectively.

Development of a methodology to assess the footprint of wastes

The ecological footprint (EF) is a widely used indicator to assess the sustainability of people, regions or business activities. Although this metric has grown in interest and popularity over the years, it has also been the subject of criticism and controversy. The advantages of an aggregated indicator are often overshadowed by the shortcomings of its corresponding methodology. One weakness of the EF is that it does not account for toxic or hazardous pollutants and wastes, which cannot be part of a closed biological cycle. The methodology developed in the present work estimates the EF of toxic and hazardous wastes considering a closed cycle modeled through a plasma process; a phenomenon that naturally occurs in stars and volcanoes. Wastes from industry can be treated in a thermal plasma gasification process, and, by developing a methodology to describe this process, the EF of hazardous wastes was calculated. A value of 56.5 gha was obtained, a figure on the same order of magnitude as that obtained in a previous study where a conventional ecological footprint methodology was applied to the same production process.

Why Plasma?

The waste that society generates can be converted into various energy products using new conversion technology. This article highlights the benefits of one promising conversion technology known as plasma gasification, which can be used to generate clean fuels, chemicals and clean electric power. A comparison of plasma gasification to conventional gasification technology is also discussed. Implementation of plasma gasification has the potential to dramatically reduce emissions, including greenhouse gas (GHG) emissions, relative to conventional waste disposal and treatment methods. The plasma gasification process is a significant move to a more sustainable approach to waste treatment and renewable energy production.

Why Plasma? Evaluating New Energy-from-waste Technologies

The waste that society generates can be converted into variousenergy products using new conversion technology. This article highlightsthe benefits of one promising conversion technology known as plasmagasification, which can be used to generate clean fuels, chemicals andclean electric power. A comparison of plasma gasification to conventionalgasification technology is also discussed. Implementation of plasma gas-ification has the potential to dramatically reduce emissions, includinggreenhouse gas (GHG) emissions, relative to conventional waste disposaland treatment methods. The plasma gasification process is a significantmove to a more sustainable approach to waste treatment and renewableenergy production.

Modelling and performance analysis of an integrated plasma gasification combined cycle (IPGCC) power plant

The waste management is become a very crucial issue in many countries, due to the ever-increasing amount of waste material, both domiciliary and industrial, generated. The main strategies for the waste management are the increase of material recovery (MR) which can reduce the landfill disposal, the improvement of energy recovery (ER) from waste and the minimization of the environmental impact. Recent studies have focused on an innovative technology, the plasma gasification, that has been demonstrated as one of the most effective and environmentally friendly methods for solid waste treatment and energy utilization. In this paper, a plasma gasification process based on plasma torch technology has been investigated by developing a thermochemical model (EPJ, EquiPlasmaJet) able to estimate both the syngas composition and the energy required for the gasification reactions. The EPJ model has been employed to predict the syngas composition and the energy balance of a RDF (refuse derived fuel) plasma arc gasification reactor using air as plasma gas, and, in order to define the optimal operating conditions three different configurations have been investigated. Results show that, in the better plant solution, the plasma gasification efficiency is 69.1% (LHV) and the lower heating value of the syngas generated is about 9 MJ/kg. Furthermore in order to evaluate the suitability of this technology for energy recovery from solid wastes, the integration of the optimum plasma gasification system (PGS) with a gas turbine combined cycle (GTCC) has been analysed and the performance of the resulting integrated plasma gasification combined cycle (IPGCC) has been evaluated. The system efficiency (31% LHV) is very high in comparison with the efficiency of conventional technologies based on waste incineration (20%).

Plasma gasification of sewage sludge: Process development and energy optimization

The plasma gasification process has been demonstrated in many of the most recent studies as one of the most effective and environmentally friendly methods for solid waste treatment and energy utilization. This method is applied here to the treatment of sewage sludge. Results are presented for a case study concerning the Athens’ Central Wastewater Treatment Plant, at Psittalia Island. An integrated process is proposed that includes also pre-drying of the sludge. By optimizing the process with the use of the GasifEq equilibrium model, it is demonstrated that plasma treatment of 250 ton/day sewage sludge with 68% moisture results in a net production of 2.85 MW electrical energy.