Reduced and detailed kinetic models comparison for thermal furnace of sulfur recovery units

Acid gas obtained from oil refineries contains large amounts of hydrogen sulfide, which are not allowed as the off-gas or burned to the atmosphere. The waste gas collected during the processes in the refineries contains a high amount of sulfur-bearing compounds, hence it should be sent to the sulfur recovery unit (SRU). Modified Claus process is the most common sulfur recovery process that is used around the world in the hydrocarbon processing industry. The thermal furnace is the most important part because the majority of the reactions occur in this unit. The aim of the current study is to investigate the possibility of using a reduced kinetic scheme in DSMOKE simulation environment. The hydrogen sulfide conversions are 75%, 80% and 86% obtained from plant data, detailed kinetic model and reduced kinetic model, respectively. Reduced kinetic model results agree with both detailed kinetic model results and plant data by 5% and 6% error

Mitigating carbon dioxide impact of fossil/bio-refineries by acid gas to syngas technology: Sensitivity analysis and techno-economic assessment

Hydrogen sulfide is a highly toxic by-product in the refineries. Traditional sulfur recovery units are already used, but optimization studies on them are still limited. The proposed process evaluates the possibility of a new frontier for sulfur recovery and carbon dioxide emissions reduction in refineries. The technological kernel is the regenerative thermal reactor which allows to convert hydrogen sulfide with another challenging emission, carbon dioxide, to valuable products (syngas) and harmless compound as elemental sulfur and water. The work has compared the effectiveness of the proposed technology with the traditional sulphur recovery units in terms of techno-economics and environmental impacts by proposing several sensitivity analyses on the main process parameters. Results state that it greatly improves the sustainability of the process in terms of quality of syngas produced while limiting the emissions. The economic analysis results look to be very promising for a pilot plant setup

A machine-learning reduced kinetic model for H2S thermal conversion process

H2S is becoming more and more appealing as a source for hydrogen and syngas generation. Its hydrogen production potential is studied by several research groups by means of catalytic and thermal conversions. While the characterization of catalytic processes is strictly dependent on the catalyst adopted and difficult to be generalized, the characterization of thermal processes can be brought back to wide-range validity kinetic models thanks to their homogeneous reaction environments. The present paper is aimed at providing a reduced kinetic scheme for reliable thermal conversion of H2S molecule in pyrolysis and partial oxidation thermal processes. The proposed model consists of 10 reactions and 12 molecular species. Its validation is performed by numerical comparisons with a detailed kinetic model already validated by literature/industrial data at the operating conditions of interest. The validated reduced model could be easily adopted in commercial process simulators for the flow sheeting of H2S conversion processes

Smart implementation of bender equation of state

In this paper matrix and vector products are exploited to reformulate Bender Equation of State. Finally, the new formulation is used to generate results which has been compared with experimental data sets available in literature and the analogous findings coming from different thermodynamic packages commonly used in Aspen Hysys for Air Separation Unit

Methanol production from biomass gasification: Techno-economic assessment of different feedstocks

This work presents an updated techno-economic assessment of methanol production, considering an entrained flow gasifier with different second generation biomasses. Computer simulations were performed with the aid of a gasification simulator GasDS and with commercial process simulator Aspen HYSYS. A method was proposed to determine biomass composition in terms of cellulose, hemicellulose and three surrogate compounds that account for the most abundant monomers that compose lignin chains; the lower heat value (LHV) relative error was not bigger than 10%. The kinetic model deriving from this biomass characterization (composition) is not sufficiently accurate to describe biomass gasification; this is due to unrealistically small residence times and the (not modelled) catalytic effect of molten slag. Biomass gasification output is efficiently estimated by using chemical equilibrium. At current methanol market price (350 €/t) the process is economically unfeasible at the current plant capacity of 100 MW LHV biomass input (production costs vary between 360 and 440 €/t)