CHISA 2018, A STUDENTS' PERSPECTIVE
University of Twente represented at CHISA 2018
Since 1962, CHISA is a renowned phenomenon in Eastern Europe. The international congress moved in 1972 to Prague where it is still held every two years. This year, it was the honor of two groups of the Chemical Engineering master from the University of Twente to visit this symposium and to present the conducted work as part of the process plant design course at the 23rd edition of the conference. The conference consisted of key note speakers and group sessions with more specialized presentations, where we also presented our work. The main focus of this article is the content of these talks. But first, to give a general idea of the conference, we will give you two examples of key note speakers and one example of a group session.
PINCH TECHNOLOGY IN COUPLING ENERGY STRATEGIES
(Plenary speaker Raymond R. Tan)
As the vice-chancellor for research and innovation for the De la Salle University in Manilla, professor Raymond R. Tan provided the audience with handles to compare several sustainable technologies. To assess the viability of new energy solutions he and his co-workers produced a way to combine sustainable energy sources to sustainable energy products. The assessment was based on an analogy to the pinch-technology, e.g. known from its application in heat integration for industrial purposes. The pinch-technique could be expanded according to Tan and his group to sustainable energy projects and goals to assess the viability and prospect of each project.
RENEWABLE ENERGY - MYTH AND REALITY AND MOVING FORWARD
Plenary speaker Aoife Foley
Definitely another highlight from the plenary sessions was the presentation of Aoife Foley, the editor in chief of 'Renewable & Sustainable energy reviews'. Working at the Queen's University in Belfast she helped us to separate myth and reality regarding sustainable energy systems and showed her vision on the road to success regarding renewable energy. The two key messages we took from her talk were motivations. First she motivated the audience to be open for radical innovations. From her speech: in the 19th century nobody would have believed that we would leave horse-drawn vehicles completely as the main means for transportation. Main tipping point was around the beginning of the century. Now we are again at the beginning of a century, what will our radical invention be?
The second motivation was a motivation for engineers and researchers to mingle more in the public discussion. Because in order to make sure public figures base their decisions on the right information, we as technical experts should give our input more often. Respond to statements, disprove beneficial effects of laws and regulations and strengthen new policies.
TECHNO-ECONOMIC ANALYSIS OF THREE POST-COMBUSTION CO2 CAPTURE TECHNIQUES (SOLVENTS, SORBENTS & MEMBRANES)
(Group session speaker Jin-Kuk Kim)
In this work Jin-Kuk Kim gives a good overview of the important parameters, and what the opportunities for all three techniques in terms of energy requirement and CAPEX. General conclusions were that no clear favourite technique can be assigned to post-combustion CO2 capture, but that sorbent & membrane processes could yield potential benefits over the conventional solvent technology.
CONTRIBUTION 1: METHANE TO ETHYLENE, THE HOLY GRAIL?
The first contribution from the University of Twente was presented by Jasper Ros and Joep Kiewiet. Together with Jochem Prins, Nathnael Shenkute and Simon Pietersen they performed a fast-forward-feasibility study for ethylene synthesis from methane. In other words: via Douglas' hierarchical design methodology an industrial production plant producing 100 ktpa ethylene at 99.9% purity from methane was designed in AspenPlus software. The aim of this study was to find the reaction pathway with the most potential from literature, identifying the major bottlenecks for industrial application through flowsheeting and to give specific recommendations for future research using the results coming from the flowsheet. Additionally, an economical analysis has been made to support the findings.
The reaction pathway is shown in Figure 1. The challenge in converting methane to chloromethane lies in splitting the first C-H bond while at the same time suppressing consecutive catalytic reactions. At higher conversions, the selectivity will move towards the combustion reaction of methane. For this study, a conversion of 10% is chosen with a selectivity of 80% towards chloromethane at 400 °C and 2.5 bar in a multistage adiabatic reactor. These numbers were taken from literature. Besides chloromethane, dichloromethane is formed as a by-product in this reactor.
The second reactor operates at 450 °C and 40 bar. The conversion in this reactor is 70% and several higher order double bonded hydrocarbons are formed, namely ethylene, propylene, and butylene. After flowsheeting the complete plant and designing the pieces of equipment an economical analysis was performed based on the cost predictions from AspenPlus on the sized unit operations. This design results in a CAPEX of € 375 million, an OPEX of € 64 million, giving a break-even point of 7 years. Undiscounted the project would break even within 3 years.
The process shows high economical potential due to the high value of ethylene, while natural gas is relatively cheap. More research should be conducted towards the yield in the first reactor, the separation of the chloromethane and the hydrogen chloride after the first and second reactor respectively, how to perform the azeotropic distillation before the second reactor and the possibility to convert dichloromethane to ethylene.
CONTRIBUTION 2: GREEN ENERGY STORAGE
The second contribution was presented by Dadi Setiadjid. A study about the seasonal energy storage was done by Rutger Aarden, Timo van der Wel, Rens Bassa, Dadi Setiadjid and Alyssa van Duijne. The study aimed to design a process which is able to store excess energy from an average wind park of 25 wind turbines (see Figure 2).
For this process aqueous ammonium bicarbonate was selected to be the energy carrier. This chemical is non-toxic and has a 30 times higher energy density than hydrogen. In the forward process the excess power is converted in an electrolyser to hydrogen, which reacts with ammonium bicarbonate to ammonium formate at atmospheric temperature and pressure. The ammonium formate is stored. When there is an energy demand the formate is converted back to bicarbonate and hydrogen at elevated temperature and pressure. In a fuel cell the hydrogen is converted back to 5 MW power. The ammonium bicarbonate/formate is circulating within the process.
The storage price of this process with the current available technologies is 0.33 €/kWh with a round trip efficiency of 21%. For short-term storage this is not yet compatible with storage techniques such as batteries. However, this process has great potential for long term storage since the ammonium formate in solution is stable over time. Additionally, scaling up the storage capacity of this process is only a matter of increasing the storage tanks. An increase in round trip efficiency to 40% is needed in order to decrease the storage price to 0.10 €/kWh. In order to obtain this more efficient and mature electrolyser and fuel cells are needed. Furthermore, the ammonium bicarbonate/formate concentration should be increased until the solubility limit.
Overall we look back towards a successful conference. Both presentations went well with shaping discussions at the end of both. Also, we look back with great joy to the social programme of the conference. Part of the social program was a concert by a full orchestra in the main auditorium of Prague, the Rudolfinum.
Another example was the closing conference dinner in the oldest brewery of Prague. These events were good opportunities to mingle and interact with researchers from all over the world. Especially this combination, a successful scientific part and a satisfying social part made the conference an unforgettable experience for us. We are looking forward to the next opportunity.
For us, the participants from the University of Twente, it is now about getting back to our master thesis. We are looking forward to our next opportunity. We would like to thank the organization and the conference chair Jiří Drahoš for the organization and being an example to live up to.