Modelling of syngas production from municipal solid waste (MSW) for methanol synthesis

Abstract

Approximately 1 300 Gt of municipal solid waste (MSW) are produced worldwide every year. Most of it is disposed of in landfills, which is very hazardous for the environment. Up to 10 % of produced MSW are incinerated. However, incineration is not very effective and requires specific conditions for preventing emissions. Gasification and pyrolysis are more effective processes which can be used not only for heat and electricity generation but also for fuel and valuable chemicals production. MSW can be transformed into refuse-derived fuel (RDF) which has higher heat of combustion. Synthesis gas produced by RDF gasification can be utilised in methanol production. Methanol is a very lucrative chemical which can be used as renewable liquid fuel or as a reagent in organic syntheses. Gasifier design and process optimisation can be done using a reliable mathematical model. A good model can significantly decrease the number of experiments necessary for the gasification process design. In this work, equilibrium model for RDF gasification was designed in Aspen Plus environment and the flow of oxygen and steam as gasification agents were optimised to achieve the highest theoretical methanol yield. Impact of the recycle of unreacted steam and produced tar on the methanol yield was evaluated. The highest theoretical methanol yield (0.629 kg MEOH /kg RDF ) was achieved when the steam and tar recycle were switched on, the ratio between oxygen and RDF feed was 0.423 kg/kg and that between the steam and RDF feed was 0.606 kg/kg. In this case, fresh steam represented only 12 % of the total steam fed to the reactor, the rest consisted of recycled steam. Optimal gasifier temperature was 900 °C.

Performance of Catalysts of Different Nature in Model Tar Component Decomposition

“…In case of waste material recycling, process gas is the desired product of RDF gasification. Process gas contains mainly methane, carbon oxides, hydrogen, nitrogen and water vapor [4,5]. Further RDF gasification products are char and tar.…”

Intensity of the Process Gas Emission from the Thermal Treatment of the 60–340 mm MSW Fraction under Steam

“…Considering gasification, a variety of processes may be applied for municipal solid waste (MSW) treatment; they are usually classified in view of the gasifying agent, reactor design, heat supply, pressure, temperature and form of solid residue [1]. However, majority of gasification-based plants, e.g., listed in [2], use air, not steam, as a gasifying agent, presumably due to negative energy balance of the process and specific technical problems of the such units. On the other hand, there were reported pilot, demonstration or industrial pyrolysis plants using indirect heating, some of them combining pyrolysis, gasification and melting operations [3].…”

“…This last one was based on the results of experiments in a semi-industrial fluidized bed gasifier, or conversion of MSW to SNG (Synthetic Natural Gas) [19]. Generally, researchers' attention was paid especially (but not only) to the gas quality, e.g., the syngas for methanol synthesis [2] or concentration of hydrogen [9,10,12,[20][21][22]. It should be noted that thermodynamic modeling and simulation plays an important role in the analysis and technological assessments of gasification processing of waste, as was presented in papers on the syngas production from MSW in a bubbling fluidized bed [23], on the mathematical modeling of the MSW gasifier [24], in the CFD model (Computational Fluid Dynamics) of syngas production in a semi-industrial MSW gasification facility [25] and related CFD modeling of hydrogen production from MSW in comparison to biomass [26].…”

Solar-Assisted Monetization of Municipal Solid Waste

“…Gasifier feed: O 2 :RDF mass ratio = 0.42 [27]. /MWh e for electric energy from the power plant using natural gas and from solar systems, respectively [16,30].…”