The goal of this thesis is to study the process that lead to the production of PVC starting from the raw brine. The process under the attention of this thesis is implemented in a company situated on the northern coast of the Persian Gulf and it is sprawled on a 108-hectare. In 2002, two big subsidiary in the petrochemical industries entered into a contract for the construction of chlori-alkali(CA), ethylene dichloride (EDC), vinyl chloride monomer (VCM) and polyvinyl chloride (PVC) units. The petrochemical complex consists of EDC/VCM and PVC plants as well as an air separation unit (ASU), cooling towers, an air plant, a salt washing unit and a brine transfer pipeline. lts output includes valuable products such as NaOH 50%, chlorine gas, Sodium hypochlorite, EDC, PVC. The plant is slated to produce 660,000 ton/year of caustic soda 100% or its equivalent 1,320,000 ton/year of caustic soda 50%. During the analysis of the EDC/VCM plant, I’ve tried to understand the constraints and the main components needed to elaborate, in the last part, a Simulink model of the A/C and EDC/VCM plant. Regarding the process, the main objective is to optimize the hydrogen stream which is produced in the electrolyzer. At the moment, the hydrogen generated goes wasted since the whole amount is dispersed to the atmosphere. My attempts are devoted to stabilize the pressure of the hydrogen produced, in order to mix it with natural gas, and use them as fuel in the burners of the furnace where the transformation from EDC to VCM is conducted. I did not have the opportunity to have real data coming from the actual plant, therefore the transfer functions for the actuators have been approximated. I was provided with PFD and P&ID charts, thanks to them I was able to know the nominal values of the principal process variables. After having achieved some good responses from the model in open loop, I tried to introduce standard PI controllers to stabilize the system to the values declared in the documentation. Some unexpected cases are analyzed in the last chapter, such as sudden change in load or shutdown of the system due to external causes.
L'obiettivo di questa tesi è studiare il processo che porta alla produzione di PVC partendo da salamoia. Il processo studiato in questa tesi è implementato in un'azienda situata sulla costa settentrionale del Golfo Persico e si estende su una superficie di 108 ettari. Nel 2002, due grandi gruppi dell'industria petrolchimica hanno stipulato un contratto per la costruzione di unità cloro-soda (CA), dicloruro di etilene (EDC), monomero al cloruro di vinile (VCM) e polivinilcloruro (PVC). Il complesso petrolchimico è costituito da impianti EDC/VCM e PVC, nonché da un'unità di separazione dell'aria (ASU), torri di raffreddamento, un impianto ad aria, un'unità di lavaggio del sale e una condotta di trasferimento della salamoia. La sua produzione comprende prodotti di pregio come NaOH 50%, cloro gassoso, ipoclorito di sodio, EDC, PVC. L'impianto dovrebbe produrre 660.000 ton/anno di soda caustica al 100% o l'equivalente di 1.320.000 ton/anno di soda caustica al 50%. Durante l'analisi dell'impianto EDC/VCM, ho cercato di capire i vincoli e le componenti principali necessarie per elaborare, nell'ultima parte, un modello Simulink dell'impianto A/C e EDC/VCM. Per quanto riguarda il processo, l'obiettivo principale è ottimizzare il flusso di idrogeno che viene prodotto nell'elettrolizzatore. Al momento, l'idrogeno generato va sprecato poiché l'intero quantitativo viene disperso in atmosfera. Ho dedicato il mio impegno a stabilizzare la pressione dell'idrogeno prodotto, in modo da poterlo mescolare con gas naturale, e utilizzare il mix come combustibile per i bruciatori della fornace dove avviene la trasformazione da EDC a VCM. Non ho avuto la possibilità di avere dati reali provenienti dall'impianto, quindi le funzioni di trasferimento per gli attuatori sono state approssimate. Mi sono stati forniti grafici PFD e P&ID, grazie ad essi ho potuto conoscere i valori nominali delle principali variabili di processo. Dopo aver ottenuto delle risposte soddisfacenti dal modello in anello aperto, ho provato ad introdurre dei controllori PID per stabilizzare il sistema ai valori dichiarati nella documentazione. Nell'ultimo capitolo vengono analizzati alcuni casi problematici, come il cambio improvviso del carico o lo shutdown del sistema per cause esterne.
Hydrogen optimization in an EDC/VCM plant
Carradore, Jimmy
2020/2021
Abstract
The goal of this thesis is to study the process that lead to the production of PVC starting from the raw brine. The process under the attention of this thesis is implemented in a company situated on the northern coast of the Persian Gulf and it is sprawled on a 108-hectare. In 2002, two big subsidiary in the petrochemical industries entered into a contract for the construction of chlori-alkali(CA), ethylene dichloride (EDC), vinyl chloride monomer (VCM) and polyvinyl chloride (PVC) units. The petrochemical complex consists of EDC/VCM and PVC plants as well as an air separation unit (ASU), cooling towers, an air plant, a salt washing unit and a brine transfer pipeline. lts output includes valuable products such as NaOH 50%, chlorine gas, Sodium hypochlorite, EDC, PVC. The plant is slated to produce 660,000 ton/year of caustic soda 100% or its equivalent 1,320,000 ton/year of caustic soda 50%. During the analysis of the EDC/VCM plant, I’ve tried to understand the constraints and the main components needed to elaborate, in the last part, a Simulink model of the A/C and EDC/VCM plant. Regarding the process, the main objective is to optimize the hydrogen stream which is produced in the electrolyzer. At the moment, the hydrogen generated goes wasted since the whole amount is dispersed to the atmosphere. My attempts are devoted to stabilize the pressure of the hydrogen produced, in order to mix it with natural gas, and use them as fuel in the burners of the furnace where the transformation from EDC to VCM is conducted. I did not have the opportunity to have real data coming from the actual plant, therefore the transfer functions for the actuators have been approximated. I was provided with PFD and P&ID charts, thanks to them I was able to know the nominal values of the principal process variables. After having achieved some good responses from the model in open loop, I tried to introduce standard PI controllers to stabilize the system to the values declared in the documentation. Some unexpected cases are analyzed in the last chapter, such as sudden change in load or shutdown of the system due to external causes.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/188924