Tuesday, November 9, 2010: 8:30 AM
252 A/B Room (Salt Palace Convention Center)
In the industry design of thermal separation plants was often done using empirical methods and simple spreadsheet calculations or with commercial simulation programs. Thus, the aim of the long term industrial-university cooperation project was finding an efficient and experimentally validated design for different separation units and optimal operating parameters for industrial processes. In different joint research project between an academic and an industrial partner, different separation processes like, distillation, reactive absorption and desorption processes are investigated experimentally and theoretically. In a period of 15 years cooperation different problems like the removal of aromatic hydrocarbons and rigorously modelled ammonia-sulphur absorption and desorption processes (AS-Kreislaufwäsche®) using thermodynamic and chemical engineering fundamentals taking into account the complex reaction system and its effects on mass and heat transfer were investigated in detail. For the benzene separation as a part of the cookery plant new washing fluid biodiesel was investigated and compared with the traditional one. During coke oven gas purification the removal of aromatic hydrocarbons is of great economic interest. Recent basic researches under lab conditions at Berlin Institute of Technology, have shown, that Biodiesel is deemed to be an efficient alternative absorbent to generate crude benzene. Moreover, using Biodiesel from Rapeseed oil, it is likely to reduce investment and operational costs as well. In this contribution, feasibility and experimental studies concerning the applicability of biodiesel under industrial conditions will be presented including the experimental verification of a developed nonequilibrium model that enables now the design and optimization of new plants using the alternative scrubbing fluid. For this purpose, a flexible modular and transportable mini-plant was first designed and built at our Chair at the University. Aspects of modularization and reuse of plant modules were considered. The mini-plant itself mainly consists of an absorption and a desorption column, which allows a continuous process of loading and regenerating the scrubbing fluid. Structured packings are used in both separation columns. To guarantee a safe plant operation, although working with flammable gases and liquids strict safety regulations were set. Thus, the whole mini-plant was built under explosion protection ATEX II2G. Once the previous function test runs were finished at University, the whole mini-plant was moved to the coking plant ZKS at Dillingen/Saar, Germany, where the installation took place (Fig. 1). The experimental investigations confirmed the expected performance of Biodiesel. So for instance, Fig. 2 shows the recovery rate against the gas to liquid ratio. Although only 1.5 meters of packings were used in the absorption column a recovery rate of benzene of up to 70% was achieved. Beside the absorption process the regeneration capability of biodiesel and the product quality of the generated crude benzene were analyzed and monitored by gas chromatography. During the experimental phase, experiences of more than 450 operating hours were obtained and up to 400 litres of crude benzene were produced. For the simulation work a developed rate-based model was used which applies the approaches of Billet and Schultes for the calculation of mass transfer coefficients. The simulation model of the absorption and desorption process itself is based on a Fortran routine that was implemented in the commercial simulation software ChemCAD. Figure 3, where the measured and calculated outlet concentrations of benzene in the gas flow are plotted, shows exemplarily the results of the model evaluation. In the lecture different technical aspects like column design, modelling and experimental validation, experimental design with application Distillation and also absorption processes will be presented. Additionally several aspects of project management, cooperation between Industry and University will also be highlighted.