The aim of this thesis work is to study and compare innovative technologies to perform natural gas treatment up to pipeline specifications in a more sustainable way from an economic and environmental point of view, in particular when the carbon dioxide content in the raw natural gas is particularly high. More specifically, this work is focused on a comparison in terms of energy requirements of three classes of processes, which are proposed in the literature as favourable options to replace the classical chemical wash by amines to treat natural gas with a high acid gas content: physical absorption (Ifpexol™ process, which exploits methanol as solvent, and Selexol™ process, which exploits a mixture of dimethyl-ethers of poly-ethylene glycol), dual pressure cryogenic distillation (DCCD™ process) and a combination of a bulk abatement by distillation followed by a physical absorption finishing (bulk + Ifpexol™ and bulk + Selexol™ processes). A version of each of the cited technologies properly adapted in order to guarantee homogeneity in operating conditions is modelled using the Aspen HYSYS® V9.0 and Aspen Plus® V9.0 software packages. Chemical absorption by amines and a hybrid process consisting of a bulk distillation and a finishing step by amines wash (SPREXCO2® + AdvAmine™ process) are included in the analysis to better show the potentiality of the use of physical solvents in sour natural gas treatment. The processes are, then, compared in terms of Net Equivalent Methane consumption, methane losses due to hydrocarbon co-absorption by physical solvents, overall net amount of treated methane obtainable with respect to the total amount of fed methane, composition of carbon dioxide-rich product streams, solvent losses and required solvent circulating flowrates. At the end of this thesis work, an indication for the selection of the best process according to the carbon dioxide content in the raw natural gas is obtained.
Questo lavoro di tesi si propone di studiare e comparare tra loro diverse tecnologie innovative per la purificazione del gas naturale fino al raggiungimento delle specifiche imposte per il trasporto tramite pipeline riducendo l’impatto economico e ambientale, in particolare quando il contenuto iniziale di anidride carbonica è particolarmente elevato. Nello specifico, questo lavoro è incentrato sul confronto in termini di fabbisogno energetico di tre classi di processi, proposte in letteratura come valide alternative per sostituire il classico lavaggio chimico con ammine nel trattamento di gas naturale ad elevato contenuto di impurezze: assorbimento fisico (processo Ifpexol™, che utilizza il metanolo come solvente, e processo Selexol™, che utilizza una miscela di dimetil-eteri del glicole polietilenico), distillazione criogenica dual pressure (processo DCCD™) e una combinazione di una purificazione di bulk per distillazione seguita da uno step di finishing per assorbimento fisico (processi bulk + Ifpexol™ e bulk + Selexol™). I software Aspen HYSYS® V9.0 e Aspen Plus® V9.0 sono usati per simulare una configurazione di ognuno dei processi citati propriamente adattata al fine di garantire condizioni operative omogenee. L’assorbimento chimico con ammine e un processo che consiste in una distillazione di bulk seguita da un finishing con ammine (processo SPREXCO2® + AdvAmine) sono inclusi nel confronto al fine di dimostrare le potenzialità dell’utilizzo dei solventi fisici per il trattamento di gas naturale acido. I processi sono, poi, confrontati in termini di consumo di Metano Netto Equivalente, perdite di metano dovute al co-assorbimento di idrocarburi da parte dei solventi fisici, quantità netta di metano trattato ottenibile rispetto alla quantità totale di metano processato, composizione delle correnti ricche in anidride carbonica ottenute come prodotto, perdite di solvente e portate di solvente richieste. Al termine di questo lavoro di tesi è possibile selezionare la tecnologia che risulta essere la migliore in relazione al contenuto iniziale di anidride carbonica nel gas naturale da trattare.
Comparative study among innovative technologies for sour and ultra-sour natural gas treatment
GILARDI, MATTEO
2018/2019
Abstract
The aim of this thesis work is to study and compare innovative technologies to perform natural gas treatment up to pipeline specifications in a more sustainable way from an economic and environmental point of view, in particular when the carbon dioxide content in the raw natural gas is particularly high. More specifically, this work is focused on a comparison in terms of energy requirements of three classes of processes, which are proposed in the literature as favourable options to replace the classical chemical wash by amines to treat natural gas with a high acid gas content: physical absorption (Ifpexol™ process, which exploits methanol as solvent, and Selexol™ process, which exploits a mixture of dimethyl-ethers of poly-ethylene glycol), dual pressure cryogenic distillation (DCCD™ process) and a combination of a bulk abatement by distillation followed by a physical absorption finishing (bulk + Ifpexol™ and bulk + Selexol™ processes). A version of each of the cited technologies properly adapted in order to guarantee homogeneity in operating conditions is modelled using the Aspen HYSYS® V9.0 and Aspen Plus® V9.0 software packages. Chemical absorption by amines and a hybrid process consisting of a bulk distillation and a finishing step by amines wash (SPREXCO2® + AdvAmine™ process) are included in the analysis to better show the potentiality of the use of physical solvents in sour natural gas treatment. The processes are, then, compared in terms of Net Equivalent Methane consumption, methane losses due to hydrocarbon co-absorption by physical solvents, overall net amount of treated methane obtainable with respect to the total amount of fed methane, composition of carbon dioxide-rich product streams, solvent losses and required solvent circulating flowrates. At the end of this thesis work, an indication for the selection of the best process according to the carbon dioxide content in the raw natural gas is obtained.| File | Dimensione | Formato | |
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2019_10_Gilardi.pdf
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https://hdl.handle.net/10589/150165