Sabatier System Design Study for a Mars ISRU Propellant Production Plant

As NASA looks towards human missions to Mars, an effort has started to advance the technology of a Mars in situ resource utilization (ISRU) Propellant Production Plant to a flight demonstration. This paper will present a design study of the Sabatier subsystem. The Sabatier subsystem receives carbon dioxide, CO2, and hydrogen, H2, and converts them to methane, CH4, and water, H2O. The subsystem includes the Sabatier reactor, condenser, thermal management, and a recycling system (if required). This design study will look at how the choice of reactor thermal management, number of reactors, and recycling system affect the performance of the overall Sabatier system. Different schemes from the literature involving single or cascading reactors will be investigated to see if any provide distinct advantages for a Mars propellant production plant

The thermodynamics, mechanism and kinetics of the catalytic conversion of propylene and water to diisopropyl ether over amberlyst 15

Bibliography: leaves 297-313.Diisopropyl ether (DIPE) was synthesised in a single step from a feed of propylene and water over Amberlyst 15 ion exchange resin catalyst. It was produced in a trickle bed reactor at pressures between 1 bar and 60 bar, at temperatures between 70°C and 160°C and at overall propylene to water ratios between 1:5 and 10:1. Reaction proceeded in the liquid phase within the catalyst particles. The only reactions that occurred in the system were the hydration of propylene to form isopropanol (IPA) , the alkylation of IPA with propylene to form DIPE and the bimolecular dehydration of IP A to form DIPE and water. No side reactions such as propylene oligomerisation were observed. Starting from a feed of propylene and water the primary reaction product was IPA. IPA was subsequently consumed in two secondary reactions which produced DIPE. DIPE was produced either by the alkylation of IPA with propylene or by the bimolecular dehydration of IPA. It was generally not possible to study the two DIPE formation reactions separately as they are linked via the propylene hydration reaction. All experimental data was thus reported in terms of a hydration rate and an etherification rate, the latter being the sum of the IPA alkylation and the bimolecular IPA dehydration rates

Novel Heat Integration in a Methane Reformer and High Temperature PEM Fuel Cell-based mCHP System

AbstractA highly integrated and optimized heat recovery system is essential for efficient operation of a HTPEM fuel cell-based mCHP system. The main challenge with such system is to design energy efficient systems with low start-up time. Recent studies have shown that this can be achieved by proper heat integration of the balance of plant (BOP) components. This study proposed a novel scheme that optimally integrated the sub-components of a mCHP system consisting of a 2 kWel HTPEM fuel cell integrated with methane processing units, for recovery and use of the process and waste heat. A steady state system modeling and simulation of the complete mCHP system was implemented in Aspen Plus v7.2. The design of the heat recovery system was achieved with pinch analysis techniques. Heat integration results show that external cooling utility is not required and result in a 5% increase in the overall system efficienc

Experimental Demonstration and Validation of Hydrogen Production Based on Gasification of Lignocellulosic Feedstock

The worldwide production of hydrogen in 2010 was estimated to be approximately 50 Mt/a, mostly based on fossil fuels. By using lignocellulosic feedstock, an environmentally friendly hydrogen production route can be established. A flow sheet simulation for a biomass based hydrogen production plant was published in a previous work. The plant layout consisted of a dual fluidized bed gasifier including a gas cooler and a dust filter. Subsequently, a water gas shift plant was installed to enhance the hydrogen yield and a biodiesel scrubber was used to remove tars and water from the syngas. CO$_{2}$ was removed and the gas was compressed to separate hydrogen in a pressure swing adsorption. A steam reformer was used to reform the hydrocarbon-rich tail gas of the pressure swing adsorption and increase the hydrogen yield. Based on this work, a research facility was erected and the results were validated. These results were used to upscale the research plant to a 10 MW fuel feed scale. A validation of the system showed a chemical efficiency of the system of 60% and an overall efficiency of 55%, which indicates the high potential of this technology

Thymol synthesis by acid catalysed isopropylation of m-cresol

Includes bibliographical references.The initial motivation for this study was to identify a suitable window of operation for thymol synthesis from iso-propanol and m-cresol mediated by a commercially available H-MFI zeolite catalyst. A preliminary investigation uncovered seeming anomalies in the course of the synthesis process, in particular counterintuitive trends with respect to m-cresol conversion and thymol selectivity at low space velocity. Consequently, the study sought to establish the reaction pathway responsible for these observations in an attempt to gain an understnding for future thymol yield optimisation studies. Under the reaction conditions studied, complete dehydration of iso-propanol was observed. Further reaction of the propene to olefinic species with carbon numbers higher than 3 was also seen. Results showed that the cause of the so-called “volcano curve” in respect of m-cresol conversion was found in the system’s propensity for the formation of cresylic rings which were alkylated with side chains consisting of carbon atoms between 4-8, particularly under severe reaction conditions. This fraction was formed via the alkylation of the m-cresol with the said olefinic pool. The thymol synthesis system was also found to be thermodynamically limited at high reaction temperature and low space velocit

Process Simulation Unit Operation Models - Review of Open and HSC Chemistry I/O Interfaces

Chemical process modelling and simulation can be used as a design tool in the development of chemical plants, and is utilized as a means to evaluate different design options. The CAPE-OPEN interface standards were developed to allow the deployment and utilization of process modelling components in any compliant process modelling environment. This thesis examines the possibilities provided by the CAPE-OPEN interfaces and the .NET framework to develop compliant, cross-platform process modelling components, particularly unit operations. From the software engineering point of view, a unit operation is a representation of physical equipment, and contains the mathematical model of its functionality. The study indicates that the differences between the CAPE-OPEN standards and Outotec HSC Chemistry Sim are negligible at the conceptual level. On the other hand, at the implementation level, the differences are quite considerable. Regardless of the simulation application being used, the modelling of unit operations requires interdisciplinary skills, and creating tools and methods to ease the development of such models is well justified. The results of this study suggest that CAPE-OPEN both provides various paths to change the way HSC Chemistry Sim works and offers the HSC development team a chance to determine an alternative way to distribute tasks between simulation components. In addition, making HSC Chemistry Sim compliant would bring benefits, such as an extended process modelling component library, and perhaps more publicity. Obviously, the workload required by the changes depends on the chosen path, which invariably entails a lengthy learning curve. This thesis contributes by helping to make that learning curve shorter.Kemiallisten prosessien mallinnusta ja simulointia käytetään kemiallisten tuotantolaitosten suunnittelussa työvälineinä ja niiden avulla voidaan arvioida eri suunnitteluvaihtoehtojen mielekkyyttä. CAPE-OPEN rajapintastandardit on kehitetty mahdollistamaan mallinnuskomponenttien käyttöönotto ja hyödyntäminen missä tahansa yhteensopivassa, standardia noudattavassa, prosessinmallinnusohjelmistossa. Tässä työssä tutkittiin CAPE-OPEN rajapintojen ja .NET -sovelluskehyksen tarjoamia mahdollisuuksia simulointiohjelmistosta riippumattomien, standardia noudattavien, prosessinmallinnuskomponenttien, erityisesti yksikköoperaatioiden kehittämiseen. Ohjelmistoteknisesti yksikköoperaatio on fyysisen prosessilaitteen kuvaus, joka pitää sisällään kyseisen laitteen toiminnan matemaattisen mallin. Osoitetuksi tulee, että erot CAPE-OPEN rajapintastandardien ja Outotec HSC Chemistry Sim -simulointisovelluksen välillä ovat käsitteellisellä tasolla pieniä. Toisaalta, toteutustasolla erot ovat suuria. Riippumatta käytettävästä simulointiohjelmistosta yksikköoperaatioiden mallien kehittäminen vaatii lähtökohtaisesti poikkitieteellistä osaamista, ja onkin perustelua kehittää apuvälineitä, joilla yksikköoperaation mallien luominen olisi mahdollisimman vaivatonta. Työn tulosten perusteella voidaan sanoa, että CAPE-OPEN tarjoaa sekä vaihtoehtoja muuttaa nykyistä HSC Chemistry Simin toimintamallia että kehittäjille mahdollisuuden hahmottaa simulaattorin osien välinen vastuunjako uudessa valossa. Lisäksi, HSC Chemistry Simin muuttaminen yhteensopivaksi standardin kanssa toisi mukanaan etuja, kuten laajennetun komponenttivalikoiman ja mahdollisesti enemmän julkisuutta. Muutoksiin liittyvä työmäärä riippuu valitusta kehityssuunnasta, mutta joka tapauksessa niihin liittyy kestoltaan huomattavan pitkä perehtymisvaihe, jota tämä työ osaltaan auttaa lyhentämään