A new approach was presented to improve the simulation results of an existing TEG based natural gas dehydration plant, using Aspen Plus software. Furthermore, the environmental impact of the plant was investigated. The plant consists of four main unit operations including an absorber, a flash tank, a stripper and a regenerator. Twelve thermodynamic models were assigned to these units. In the first step of the study, only one thermodynamic model was assigned to all of the units while in other steps, combinations of thermodynamic models were employed. The most accurate model combination was found to be RKSMHV2 for the absorber and stripper and PSRK for the flash tank and regenerator. It was found that a proper combination of thermodynamic models may improve the simulation results. As solvent circulation rate increased, BTEX, VOC and greenhouse gas emissions enhanced. Original language EnglishPages (from-to) 38-47

Dielectric barrier discharges are an emerging technology for the plasma-catalytic removal of volatile organic compounds and other gas purification challenges such as the removal of O2 traces from H2. Packed-bed reactors are mainly used for these applications, but surface dielectric barrier discharges (SDBDs) typically printed on thin dielectric plates are promising alternatives for the treatment of large volumetric flow rates due to their low flow resistance causing a low pressure drop. Especially for SDBDs the flow conditions are crucial, because the active plasma filled volume covering the mentioned plates with a typical thickness of 0.1 mm is small in comparison to the overall reactor volume with a typical distance of some tens of millimeters to the reactor wall. In this study, the flow conditions of a twin-surface dielectric barrier discharge were investigated by Schlieren imaging applied in converting O2 traces in H2 containing gas mixtures to H2O and compared to fluid dynamics simulations. Schlieren imaging was used to visualize local gradients of the refractive index inside the SDBD reaction chamber, while gas composition, dissipated power, or flow rate were varied. Without a plasma discharge, laminar flow dominates, resulting in a conversion below 10% over a Pt‑coated electrode configuration in the reaction of O2 traces with H2. With the plasma discharge, full conversion was achieved for the same reaction without catalyst, although the plasma is also confined to the surface of the electrode configuration. Schlieren structures covering the complete cross section of the reaction chamber were observed, showing that strong radial mass transport is induced by the plasma. The shape and extent of the Schlieren structures is ascribed to a superimposition of gas flow, thermal expansion from the plasma volume, thermal buoyancy as well as an electrohydrodynamic force between the electrodes and the grounded reactor walls. Fluid dynamics simulations show vortex formation above and below the electrode, created by the electrohydrodynamic force further implying extensive mass transport by the plasma, which is visualized in addition by carbonaceous deposits on the reactor lid.These findings reveal new possibilities to improve SDBD reactors for gas purification applications based on their favorable flow conditions.

Recently, the direct conversion of methane into hydrogen using cold plasma reactors has attracted increasing attention, since hydrogen has considerable potential as a future feedstock in the steel and chemical industries. However, the simulation of plasma pyrolysis reactors is extremely complex due to the vast temporal and spatial ranges of the variables involved and steep gradients. Previously, methane pyrolysis has been meticulously modeled by 0D simulations, and 3D plasma modeling has been largely confined to Argon systems. In this paper, a systematic methodology is presented, which provides an expedient and efficient hierarchy of 0D to 3D simulations, in order to approximate the methane pyrolysis simulation of a plasma reactor in its entirety. Various simulation tools are applied in a coordinated and pragmatic manner. The results show that the proposed synergy allows simplification of the reaction set and arc characteristics, significantly reducing the runtime required for the simulations.

Hydrogen generation by plasma reactors from methane is a promising technology. Although, much research is done on accurately describing the plasma, fewer was focused on the reactor design optimization. By altering the design, the velocity profiles and heat transport can be managed in such a way that the conversion of methane can be increased. Through a simplified simulation approach, it was possible to increase the gliding arc reactor conversion from 30 to 50 %, which was tested by experiments. Similar finding resulted from the microwave plasma simulation, where simulations showed a potential rise from 66 % to 84 %.