Municipal Solid Waste Gasification Research Articles

Modeling and process design of municipal solid waste pyrolysis and gasification with a fixed-bed chamber

To design the process of municipal solid waste (MSW) pyrolysis and gasification in a fixed-bed more veritably and effectively, the modeling of this process was proposed based on Gibbs energy minimization by using the Aspen plus software. The proposed model was used to predict and analyze the influences of operating parameters including gasification temperature, air-fuel ratio and steam/MSW ratio on the composition, lower heating value (LHV), carbon conversion efficiency (CCE), heat conversion efficiency (HCE)and flammable gas contents (FGC) of syngas. The results indicate that there is a good agreement between the experimental data and the simulated data obtained using this model. The predicted appropriate gasification temperature was around 900°C while the suitable air-fuel ratio was approximately 0.4, and the beast steam/MSW ratio was around 0.4. A novel configuration of atmospheric fixed-bed chamber is designed for the municipal solid waste pyrolysis and gasification process based on the experimental and simulated results. The designed configuration was feasible with achieved heat balance of the system.

Municipal Solid Waste as a valuable recycled asset for small-scale electricity production in rural communities

Municipal solid waste provides an opportunity for electricity production. This strategy provides the rural communities a potential waste-to-energy opportunity to manage its costly residues problem, turning them into a valuable recycled asset. To address this issue, a techno-economic study of an integrated system comprising gasification of Acacia residues and Portuguese Municipal Solid Waste (PMSW) with an Internal Combustion Engine-Generator (ICEG) for electricity generation at small-scale (100 kW) was developed. Current studies only devote attention to biomass residues and do not explore MSW potential to eschew biomass supply shortage. Conventional systems are generally part of biomass supply chains, limiting flexibility and all year operation for their operators. Experimental data was gathered at a downdraft gasifier to provide a clear assessment of particle and tar concentration in the syngas and levers conditioning a satisfactory ICE operation. Once the potential of using Acacia residues and PMSW has been proven during gasification runs testing, and validation, a set of new conditions was also explored through a high-fidelity CFD model. We find that residues blends have the highest potential to generate high-quality syngas and smallest exposure to supply disruption. Despite both substrates showing potential at specific conditions, they also present individual drawbacks which will be best mitigated by executing a hybrid supply comprising the mix of substrates. An economic model coupling the financial indicators of net present value (NPV), internal rate of return (IRR) and the payback period (PBP) considering a project lifetime of 25 years was developed. Cost factors include expenses with electricity generation, initial investment, amortizations and operation and maintenance (containing fuels costs). Revenues were estimated from electricity generated and sales to the national grid. A sensitivity analysis based on the Monte Carlo method was used to measure the economic model performance and to determine the risk in investing in such venture. The risk appraisal yielded favorable investment projections, with an NPV reaching positive values, an IRR superior to the discount rate and PBP lower than the project life span. This work allowed to confirm the positive effect of the generation of energy from downdraft gasification plants on a small-scale. Regardless of the project’s feasibility, the economic performance depended to a large extent on the electricity prices which present considerable variability and are subject to political decisions.

SNG-electricity cogeneration through MSW gasification integrated with a dual chemical looping process

This paper assesses, from a technical perspective, the conversion of municipal solid waste (MSW) to SNG and electricity through gasification simultaneously with a dual chemical looping process, namely chemical looping air separation and calcium looping CO2 absorption. This novel technology includes five main parts: chemical looping air separation (CLAS), MSW gasification, water-gas shift process with calcium looping for enhancement of CO2 absorption (WGS-CaL), heat recovery steam generator (HRSG) and power island. The performance of CLAS, which presents an advantage over the other mature technologies in capital cost, is examined. WGS-CaL is an efficient method for SNG production and CO2 capturing. The three major factors, Mn/M to MSW (Mn/M), steam to MSW (S/M) and the ratio of syngas introduced to WGS were analyzed. Meanwhile, the exergy destruction analysis of whole process has also been calculated.

Dense glass‐ceramics by fast sinter‐crystallization of mixtures of waste‐derived glasses

AbstractDense glass‐ceramics were obtained by cold pressing and sinter‐crystallization of a glass originated from the plasma gasification of municipal solid waste (“Plasmastone”) mixed with recycled soda‐lime glass and kaolin clay. The optimum mixture featured 45% Plasmastone/45% soda‐lime glass/10% kaolin clay and it was sintered according to a fast heat treatment (30 minutes at 1000°C with heating and cooling rates of approximately 40°C/min), mimicking that of industrial ceramic tiles. The fast treatment avoided extensive crystallization during heating, promoting the viscous flow. In this way, dense glass‐ceramics with a water absorption below 0.7% could be produced. The developed tiles presented mechanical properties comparable to those of commercial ceramic tiles. Finally, the environmental impact assessment performed on these materials showed that the leaching of hazardous elements was particularly limited. Microprobe analyses indicated that heavy metals were incorporated in newly formed crystals, consisting mainly of hedenbergite, wollastonite, and iron oxide‐rich “islands” surrounded by residual glass. The results show that Plasmastone, combined with recycled soda‐lime glass and kaolin clay, may be converted in building materials, with a possible commercial exploitation.

Kinetics of Gaseous Species Formation During Steam Gasification of Municipal Solid Waste in a Fixed Bed Reactor

Surrogate municipal solid waste (MSW) has been prepared to represent high plastic content waste with low fixed carbon in order to be utilized for feedstock for the gasification and pyrolysis. The major components are plastic (PE and PP), food and kitchen waste, and paper, whereas the minor components are textile, rubber, and biomass. Reactions were conducted in small drop tube fixed bed reactor with isothermal reaction temperature at 700, 800, and 900 °C. Steam was supplied as the gasifying agent for the main purpose of producing hydrogen-rich gas. Pyrolysis was also conducted at the same condition to observe the characteristic differences. Producer gas, including H2, CH4, and CO, of both the reactions was a function of the temperature, whereas CO2 showed a reversed trend when the reaction temperature was increased. Simple kinetic models of those gaseous formations were studied for describing the related parameters. It is challenging to determine the kinetics of the individual gas generation while most kinetic studies have focused on mass deterioration. The commonly used kinetic model of nucleation of Avrami–Erofe'ev (A2) could well predict the mechanism of the gas formation of gasification. In parallel, the pyrolysis conformed to the A3 model due to the slower rate of char and tar decomposition when the gasifying agent was absent. The activation energy of each gaseous species and the fitting of experimental data with the selected models are examined in this study.

The role of plasma in syngas tar cracking

Gasification of biomass and municipal solid waste is a technology that has been proposed as a dual-purpose solution for mitigating environmental impacts as well as for producing syngas, a very useful intermediary product for energy valorization and organic synthesis. However, the presence of pollutants, notably tar, hampers this raw syngas (producer syngas) to be used in high-efficient energy applications such as jet engines and fuel cells or in Fischer-Tropsch synthesis, limiting its economic value. For reducing tar, a lot of scientific and technical effort has been devoted. In this paper, the state of the art of plasma tar removal from syngas is done, focusing on the use of plasma in tandem with existing technologies, underlining its advantages and the remaining challenges. The most promising ways to get a syngas with very low tar levels using plasma seem to be (i) tandem tar cleaning techniques (e.g. secondary plasma enhanced catalytic unit) and (ii) secondary thermal plasma cracking units.

Enhanced H2 Production from Municipal Solid Waste Gasification Using Ni–CaO–TiO2 Bifunctional Catalyst Prepared by dc Arc Plasma Melting

The gasification of municipal solid waste (MSW) in the presence of a Ni–CaO catalyst is a promising approach for in situ CO2 capture along with enhanced H2 syngas production. However, the instabili...

Modeling low temperature plasma gasification of municipal solid waste

Abstract Plasma gasification requires high energy input and temperature, hindering adoption for commercial applications. In this study, a model of low-temperature plasma gasification is investigated to convert municipal solid waste (MSW) into syngas. The model was employed at reactor temperatures of 1,500, 2,000, and 2,500 °C to assess effects on syngas composition and system performance with air as the plasma medium. At plasma temperatures of 1,500, 2,000, and 2,500 °C, the model generated syngas lower heating values of 5.41, 6.02, and 6.45 MJ/Nm3, respectively, with energy inputs of 2,358, 2,775, and 3,245 kW per kg/s of MSW, respectively, and plasma gasification efficiencies of 49.6, 49.2, and 48.9%, respectively. In comparison to conventional non-plasma air gasification of MSW, syngas generated from low-temperature plasma gasification contained higher concentrations of hydrogen and carbon monoxide, resulting in higher heating value of the syngas.

Studying plasma gasification of solid municipal waste

The paper presents the results of mathematical and experimental studies of the process of gasification of municipal solid waste in a plasma electric furnace. The energy consumption for gasification of SMW with the organic and inorganic components of morphological composition was investigated during these studies. The effect of reducing the energy consumption during waste gasification, excluding the inorganic component of SMW was also investigated. The paper presents the results of computational and experimental studies of SMW gasification and reveals the effect of the inorganic part on the energy balance of an electric plasma furnace.

Analysis of the Composition and Properties of Municipal Solid Waste and Their Use as Carbonaceous Feedstock in Underground Coal Gasification Process

The development of new technological solutions in municipal solid waste management will reduce the adverse impact on the environment and human health. There are different methods of thermal disposal of municipal solid waste, such as incineration, pyrolysis,and gasification. The most effective and environmental method of thermal disposal is the gasification of solid wastes. This paper discusses the possibility of municipal solid waste gasification in underground coal gasification process and the prospects of gasification method following on from the analysis of the composition and properties of municipal solid waste. Municipal solid waste is a valuable carbonaceous feedstock that can be used in an underground coal gasification process to increase the life cycle of the underground gasifier, to produce additional volumes of synthesis gas, to stow the ash of municipal solid waste in mined-out space of underground gasifier. Operations of municipal solid waste preparation need to improve the efficiency of the gasification process. A considerable volume of municipal solid waste is an alternative carbonaceous resource, which can provide the needs of power and chemical industry for synthesis gas.

Future district heating plant integrated with municipal solid waste (MSW) gasification for hydrogen production

Characterizing municipal solid waste (MSW) is a critical step in planning, designing, operating, or upgrading solid waste management systems. For a theoretical investigation of hydrogen production by gasification and water-gas shift reaction, we characterized Norwegian MSW and used the data. Three different gasification setups, named as ‘A-1’, ‘A&S-2’, and ‘S-3’ were modeled using Aspen plus simulation software for direct and indirect gasification processes according to the different gasification agents. The MSW characterization result showed a reasonable agreement with existing studies in different countries. The maximum hydrogen yield achieved in setup ‘S-3’ was around 94% of the maximum theoretical hydrogen yield from the specified MSW. At a steam to syngas ratio of 0.5, 199.6 g of hydrogen could be produced per one kg of MSW, with 4 L of water at 100 °C for district heating. The study indicates integrating an indirect gasifier in preexisting MSW-fired plants can play a significant role in recovering energy from MSW in the form of energy carrier hydrogen. However, if it is necessary to construct a new waste incinerator, the study results indicate building a direct gasification system.

Process optimization and robustness analysis of municipal solid waste gasification using air‐carbon dioxide mixtures as gasifying agent

Process optimization and robustness analysis of municipal solid waste gasification using air‐carbon dioxide mixtures as gasifying agent

Characterization and adsorption performance evaluation of waste char by-product from industrial gasification of solid refuse fuel from municipal solid waste

This study investigated the effect of steam and air flowrate combinations on the syngas efflux, physicochemical properties and adsorption performances (on congo red, CR and crystal violet, CV removal) of waste char by-product from the industrial gasification of solid refuse fuel from municipal solid waste. The BET surface area (11.4 m2/g), porosity (74.7%), fixed carbon content (25.8 wt%) and hydrophilicity (0.09) were enhanced with lower steam rate and higher air supply rate combination (MSWC-L) than for the higher steam rate and lower air supply rate combination (MSWC-H). Adsorption performances were higher for MSWC-L than MSWC-H on both CR (35.7–49.7 mg/g) and CV (235 to 356 mg/g) removal, suggesting that, higher air supply rate (214 Nm3/h; at 0.36 equivalence ratio) with lower steam rate (37 kg/h) were more effective gasification process conditions. Results showed that, syngas efflux was more sensitive to air supply rate than steam supply rate. Reactions in the combustion zone were not only limited to the pyrolysis gas vapours but to the char also. In conclusion, the waste chars from municipal solid waste gasification showed good potential as adsorbents in wastewater treatment.

A theoretical study on municipal solid waste plasma gasification

Gasification is an innovative and effective process which reduces the amount of waste produced by society and affords a synthetic gas with diverse applicability. In this plasma gasification study at high temperatures, a previously developed Aspen Plus model was used for municipal solid waste (MSW). The study is focused on the behavior of the equivalence ratio (ER), steam to MSW (S/MSW) ratio and gasification temperature (T), as a function of three gasification agents (air, O2 and steam), assessing the final syngas composition. The model was validated with results from literature. The highest hydrogen yield reached 64% (molar fraction), when steam was used as gasification agent, lower values corresponding to O2 utilization. Instead, a CO-enriched syngas was achieved under O2 atmosphere (58%). Enhanced lower heating value (LHV) was obtained for the syngas produced when ER = 1, under oxygen atmosphere at 1500 °C (13 MJ/Nm3). This is due to the formation of CO, promoted by O2, which constitutes an important factor in enhancing syngas LHV. Tar presence in the gasification process normally implies significant complications, but in this study, no problems were noticed since gasification occurred at higher temperatures.

Potential of tire pyrolysis char as tar-cracking catalyst in solid waste and biomass gasification

Municipal solid waste (MSW) disposed in landfills is a serious environmental hazard and waste of potential source of reusable resources and energy as only a small portion of MSW is incinerated. Pyrolysis and gasification of MSW is an alternative to commercial combustion for the recovery of valuable chemicals and production of heat and electricity. Tar formation is a serious problem in the gasification process. Tar content in the product gas has to be decreased to a certain level required by the downstream production line. This can be achieved by the application of a suitable catalyst. However, commercial catalysts are expensive, prone to fast deactivation and sintering. Char from waste tire pyrolysis is a suitable catalyst for tar decomposition as it contains a significant amount of metals and has relatively large specific surface area. The advantage of this catalyst is its low price and no need for its regeneration as it can be simply combusted after losing its activity. In this work, catalysts prepared from tire pyrolysis char were activated at three different temperatures. The impact of activation temperature on the properties of prepared catalysts was analyzed. Tar cracking activity of the prepared catalysts was tested in a continuous tubular reactor and toluene was used as a model tar compound. Char activated at 900 °C achieved the highest toluene conversion and the lowest tar yield, so it was selected for application in batch gasification of refuse-derived fuel (RDF). During RDF gasification, the presence of a selected catalyst in the secondary reactor led to a decrease in the total amount of produced tar by 92.3% compared to non-catalytic (thermal) decomposition.

Three municipal solid waste gasification technologies analysis for electrical energy generation in Brazil.

In Brazil, in 2016, 196,050 tonnes day-1 of municipal solid waste (MSW) were collected, which means a waste generation of 1.035 kg per capita per day. Only 59.1% of the waste has adequate destination in sanitary landfills, whereas the remaining 40.9% has inadequate destination in controlled landfills and open dumps (ABRELPE, 2018). Among all the states in the country, the State of São Paulo has the biggest per capita generation: 2.290 kg. Today, the only waste destination practiced in the country is deposition in landfills, but other possibilities can be considered. Among thermal treatment routes, the gasification of MSW is an interesting alternative to be studied, because of its versatility and relatively low emissions. The aim of this work is to evaluate the potential of electricity generation through MSW gasification in Santo André city, Brazil, comparing three waste gasification technologies: TPS Termiska Processer AB, Carbogas and Energos. These alternatives have operated commercially for a few years, and data are available. Specific characteristics of each technology were taken into account, such as the reactor type and fuel properties. For the electricity production scheme, two energy conversion systems were assumed: an internal combustion engine and a steam power cycle. From the process parameters adopted, the results showed that Carbogas technology, coupled to internal combustion engines, presents the highest efficiency of electricity generation (30%) and also the lowest cost of electrical energy produced (US$65.22 MWh-1) when Santo André's gate fee is applied.

Steam Gasification of Municipal Solid Waste in Drop Tube Fixed Bed Reactor

Waste-to-Energy (WTE) technology becomes crucial option for Municipal Solid Waste (MSW) disposal and recovery clean energy. Thermal conversion technology by steam gasification plays important key role for sustainable solution of WTE and enrich the production of Hydrogen. In this work, gasification experiment was conducted in small dropped tube fixed bed reactor by feeding surrogate MSW which including of food & kitchen waste, plastic (polyethylene & polypropylene), paper, rubber & leather, textile and biomass. The experimental conditions were varied at temperature 700, 800 and 900°C. Steam was supplied as gasifying agent with flow rate of 0.1, 0.2 and 0.3 ml/min. The main purpose was to produce hydrogen by water gas-shift reaction, nevertheless, other related producer gas e.g. carbon monoxide, methane, carbon dioxide and light hydrocarbon gas were also examined. The result showed reaction temperature 800°C with steam flow rate 0.2 ml/min offer the optimized hydrogen yield as 34.84 gh2/kgmsw whereas it trended to decrease when reaction temperature increase. In addition, the overall performance of experimental condition was evaluated by energy output and energy conversion efficiency which were calculated from volumetric of combustible gas. The minimum energy output and energy conversion efficiency were 7,638 kJ/kgsample and 31.11%, respectively, obtained at reaction temperature 700°C with steam flow rate 0.2 ml/min while the maximum value was offered by reaction temperature 900°C with same steam flow rate as 17,756 kJ/kgsample and 72.32%, respectively.

Gasification of Municipal Solid Waste Using Tyre Char as Catalyst

Gasification is raised as the most promising technologies of municipal solid waste (MSW) removal as well as energy recovery. The principal problem related with the gasification process is the high amount of tar released during the gasification process that causes environmental and operational problems. The purpose of this study is to investigate the performance of MSW gasification using tyre char as an alternative option for catalytic gasification to produce tar free clean gas. Catalytic performance of tyre char was compared with performance of MSW gasification alone without the tyre char in a bench scale downdraft reactor. The waste tyre char removed 80% of tars in syngas at 700 °C. Analysis of the syngas compositions indicated that concentration of H2 and CO were significantly increased. Therefore, it was concluded that chars especially tyre char can be an effective and inexpensive catalyst for tar removal and syngas production of MSW gasification.

Production of hydrogen enriched syngas from municipal solid waste gasification with waste marble powder as a catalyst

Marble processing leads to the production of high amount of waste marble powder (WMP) as a byproduct, which can be a potential health risk and has hazardous impacts on the surrounding environment. However, marble is composed of calcite making it suitable for the calcium-based catalyst. Moreover, no study has been carried out to utilize this WMP in municipal solid waste (MSW) gasification process. Therefore, there is a need to address its utilization as a potential catalyst/sorbent in the gasification of municipal solid waste (MSW). A laboratory scale batch-type fixed bed reactor was used to study the effect of WMP addition on the CO2 adsorption, steam reforming capability and char gasification in the presence of steam. Produced gas composition, gas yield, carbon conversion efficiency and tar yield were examined at different WMP to MSW ratios. Effect of temperature and steam rate varying from 700 to 900 °C and 2.5–10 ml/min respectively were also considered in this study. WMP showed a good capacity towards hydrogen enriched syngas production as well as CO2 adsorption and tar reforming. The H2 concentration increased significantly with an increase in the WMP to MSW mass ratio, while CO2 decreased. A significant effect of temperature and steam rate was also observed on the produced gas composition, gas yield, and tar content. This study helps us to understand the effect of WMP addition in MSW gasification process and thus assists in the industrial application.

Transformation and migration of cadmium during chemical-looping combustion/gasification of municipal solid waste

The transformation and migration of cadmium during chemical-looping combustion (CLC) and gasification (CLG) of the synthetic municipal solid waste (SMSW) was investigated in a tubular furnace. Both copper-based and iron-based oxygen carriers (OCs) can make elemental cadmium (Cd (g)) into cadmium oxide (CdO) at 850 °C, but their complete reduction products do not have this ability. Cadmium was distributed mainly in the bed material during CLC, but distributed mainly in the fly ash during CLG. After 2 min of reaction, approximately 90% of the cadmium in the bed material distributed in the OC particles, indicating that large amount of cadmium would volatilize from the SMSW particles and migrate to the OC particles at the initial stage of CLC and CLG. As the reducing gas generating later may restore CdO to Cd (g) again during CLG, the cadmium migrating to the OC particles was detached gradually. A two-step-transformation and migration mechanism for cadmium during CLC and CLG was proposed. After five successive cycles of the CLC process, the concentration of cadmium in the OC particles increased linearly from 7.1 mg/kg to 33.3 mg/kg with an average capture efficiency of 85%, while after just one cycle of the CLG process, the high concentration of the cadmium in the OC particles can be removed efficiently. Overall, the cadmium in MSW can be captured by CLC, while be removed by CLG. Therefore, the coupling of CLC and CLG processes may provide an innovative and efficient control, even recycling technology for the cadmium in MSW.