Laursen, Torben

Termodynamiske studier af multifase systemer ved højere tryk er af stor interesse for både den akademiske og den industrielle verden. Til trods for det, indeholder litteraturen få experimentielle datasæt for sådanne systemer, og disse målinger anses for at være meget kostbare og tidskrævende. Dette projekt havde som mål at udvikle og anvende apparatur som tillader rutinemålinger af både VLE og VLLE systemer i temperatur området 25-45°C og trykområdet 1-100 bar. Dette er blevet opnået ved at anvende online prøveudtagninger og kalibering vha. de rene komponenter. Prøverne fra de forskellige væskefaser er blevet udtaget via en bevægelig nål. De undersøgte systemer har været en kombination af komponentene: CO2, N2, dimethyl ether (DME), vand, methanol, ethanol and 1-propanol. 41 isothermer er blevet målt, af disse er 18 VLLE systemer og 32 er ikke tidligere blevet målt. Nogle af de eksperimentielle datasæt er blevet modelleret med en tilstandsligning: SRK, kombineret med MHV1 blandingsreglen for a-parametren og NRTL modellen for excess Gibbs energien. Mathias-Copeman modellen er blevet brugt i udtrykket for renkomponent a-parametren. For alle de binære par er interaktionsparametren τij, for NRTL modellen tilpasset eksperimentielle data, mens α-parametren er blevet fastsat til 0.2. Den opnåede model er i stand til at forudsige VLE og VLLE systemer med CO2, mens den har problemer med at give en god forudsigelse for systemer med N2.The analysis of multiphase systems at elevated pressure is of great interest both from an academic side and an industrial point of view. The literature contains limited data for such systems, and the measurement of the composition of the different phases of multiphase systems at elevated pressures has traditionally been considered very time consuming. This work aims at developing and operating an equipment which allows routine measurements of both VLE and VLLE, in the temperature range of 25-45°C and pressure range of 1-100 bar. This has been done by taking advantage of on-line sampling and pure component calibration. Samples from the different liquid phases in the high-pressure cell is taken using a moveable needle. The systems investigated have been a combination of the components: CO2, N2, di-methyl ether (DME), water, methanol, ethanol and 1-propanol. 41 isotherms have been measured and of these 18 were VLLE systems and 32 have not previously been published. Some of the experimental results have been modelled using an equation of state, SRK combined with the MHV1 mixing rule for the a-parameter and the NRTL model for the Gibbs excess energy. The Mathias-Copeman model was used in the expression for the pure-component a-parameter. For all the involved binary pairs the interaction parameters, τij, for the NRTL model were fitted to experimental data with the α- parameter fixed at 0.2. The obtained model has showed very good results when used to predict multi component VLE and VLLE systems containing CO2, while the model has some problems with systems containing N2

Online Research Database In Technology

Measurements and modeling of VLLE at elevated pressures

http://orbit.dtu.dk/ws/files/5653923/t_laursen.pdf

Measurement and Modeling of VLLE at Elevated Pressures

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Online Research Database In Technology