The increasing demand of natural gas is leading to the exploitation of sour and ultra-sour gas reserves rich in H2S. H2S is an extremely toxic acid gas, which is typically converted into elemental sulphur through the Claus process. For this reason, the conventional sulphur recovery units (SRU) are generating a surplus of elemental sulphur. To fill this gap, this Master Thesis proposes the design of a novel H2S valorisation process based on the HydroClaus technology developed by Eni S.p.A., which exploits the Wackenroder reaction to produce a ready-to-use fertilizer with a high added value. In the first part, the Claus plant installed in the Eni refinery located in Val D’Agri, Basilicata, Italy, is simulated in Aspen HYSYS® and Sulsim® to obtain a reliable SRU benchmark. Then, two optimized HydroClaus process schemes are developed in Aspen Plus® taking advantage of some existing flowsheets, and the Net Present Value (NPV) analysis is performed to demonstrate the increased HydroClaus process profitability. These two optimized processes are a valid alternative to the Claus benchmark, but the produced slurry contains more than 95% of water which causes some transportation inefficiencies. To overcome this issue, an additional version of the HydroClaus process based on the Smolyaninov reaction is developed, where the presence of amines induces the spontaneous separation of polythionates from water, which is thus recycled. Several possibilities for the amine regeneration are explored in this work, and the use of NH3 appears to be the most convenient solution thanks to the production of a sulphur-nitrogen fertilizer which is 23% cheaper than the existing products. The regeneration with other bases, such as KOH, results to be feasible but less convenient than ammonia. Moreover, the three proposed HydroClaus versions are fully electrified and greener than the benchmark, with a carbon footprint at least 28% lower. This means that they are more profitable and more sustainable than the state-of-the-art technology, and this paves the way for a new generation of SRU aligned with the modern paradigms of the process industry. Finally, the Methane Reformation (MR) is investigated as an alternative H2S valorisation process to produce valuable H2 and CS2. The NPV analysis shows that the MR process is less profitable than the HydroClaus processes because of the large operative expenditures.
La crescente richiesta di gas naturale sta spingendo allo sfruttamento delle riserve di gas sour e ultra-sour ricche in H2S. H2S è un gas acido estremamente tossico che viene tipicamente convertito in zolfo elementare tramite il processo Claus. Pertanto, le unità di recupero dello zolfo (SRU) convenzionali stanno generando un surplus di zolfo elementare. Per colmare tale divario, questa tesi magistrale propone il design di un innovativo processo di valorizzazione dell’H2S basato sulla tecnologia HydroClaus sviluppata da Eni S.p.A., la quale sfrutta la reazione di Wackenroder per produrre un fertilizzante pronto all’uso dall’alto valore aggiunto. Nella prima parte, l’impianto Claus installato nella raffineria di Eni situata in Val D’Agri, Basilicata, Italia, è stato simulato in Aspen HYSYS® e Sulsim® per ottenere un riferimento di SRU attendibile. In seguito, due processi HydroClaus ottimizzati sono stati sviluppati in Aspen Plus® partendo da alcuni schemi esistenti, e l’analisi del Net Present Value (NPV) è stata effettuata per dimostrare l’aumento di profittabilità del processo HydroClaus. Tali processi ottimizzati sono una valida alternativa al Claus di riferimento, ma lo slurry prodotto contiene oltre il 95% di acqua causando delle inefficienze nel trasporto. Per ovviare a tale inconveniente, un’ulteriore versione del processo HydroClaus basata sulla reazione di Smolyaninov è stata sviluppata, dove la presenza di ammine induce la separazione spontanea dei politionati dall’acqua, che viene perciò riciclata. Varie possibilità per la rigenerazione delle ammine sono state esplorate in questo lavoro, e l’uso di NH3 sembra essere la soluzione più conveniente grazie alla produzione di un fertilizzante a base di zolfo-azoto più economico rispetto ai prodotti esistenti del 23%. La rigenerazione con altre basi, come KOH, risulta fattibile ma meno conveniente rispetto all’ammoniaca. Inoltre, le tre versioni HydroClaus proposte sono totalmente elettrificate e più green del processo di riferimento, con una impronta di carbonio inferiore almeno del 28%. Essi sono perciò più redditizi e più sostenibili della tecnologia assunta come stato dell’arte, e ciò apre le porte ad una nuova generazione di SRU allineate con i paradigmi moderni dell’industria di processo. Infine, il processo di Methane Reformation (MR) è stato esaminato come alternativa per la valorizzazione di H2S per produrre H2 e CS2. L’analisi del NPV mostra che il processo di MR è meno profittevole dei processi HydroClaus a causa degli alti costi operativi.
Process design and techno-economic assessment of H2S valorisation technologies
Sangiorgio, Vito Andrea
2020/2021
Abstract
The increasing demand of natural gas is leading to the exploitation of sour and ultra-sour gas reserves rich in H2S. H2S is an extremely toxic acid gas, which is typically converted into elemental sulphur through the Claus process. For this reason, the conventional sulphur recovery units (SRU) are generating a surplus of elemental sulphur. To fill this gap, this Master Thesis proposes the design of a novel H2S valorisation process based on the HydroClaus technology developed by Eni S.p.A., which exploits the Wackenroder reaction to produce a ready-to-use fertilizer with a high added value. In the first part, the Claus plant installed in the Eni refinery located in Val D’Agri, Basilicata, Italy, is simulated in Aspen HYSYS® and Sulsim® to obtain a reliable SRU benchmark. Then, two optimized HydroClaus process schemes are developed in Aspen Plus® taking advantage of some existing flowsheets, and the Net Present Value (NPV) analysis is performed to demonstrate the increased HydroClaus process profitability. These two optimized processes are a valid alternative to the Claus benchmark, but the produced slurry contains more than 95% of water which causes some transportation inefficiencies. To overcome this issue, an additional version of the HydroClaus process based on the Smolyaninov reaction is developed, where the presence of amines induces the spontaneous separation of polythionates from water, which is thus recycled. Several possibilities for the amine regeneration are explored in this work, and the use of NH3 appears to be the most convenient solution thanks to the production of a sulphur-nitrogen fertilizer which is 23% cheaper than the existing products. The regeneration with other bases, such as KOH, results to be feasible but less convenient than ammonia. Moreover, the three proposed HydroClaus versions are fully electrified and greener than the benchmark, with a carbon footprint at least 28% lower. This means that they are more profitable and more sustainable than the state-of-the-art technology, and this paves the way for a new generation of SRU aligned with the modern paradigms of the process industry. Finally, the Methane Reformation (MR) is investigated as an alternative H2S valorisation process to produce valuable H2 and CS2. The NPV analysis shows that the MR process is less profitable than the HydroClaus processes because of the large operative expenditures.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/178895