Günter Scheffknecht

Innovative CO2 separation of biogas by polymer resins: Operation of a continuous lab-scale plant

Upgrading biogas allows for the injection of biomethane into the natural gas grid and thus a decentralized use. Since the currently available techniques have a high energy demand, there is a high potential to improve biogas upgrading. Innovative CO2 separation of biogas by the use of polymer resins can reduce the energy demand, the capital expenditure, and the operational costs. In this study, we show the ability of polymer resin to selectively adsorb CO2. Desorption tests showed the potential for continuous use of the resin. In a continuous lab‐scale plant, numerous variations of process parameters were carried out and optimization possibilities were demonstrated. Methane purity up to 98% was achieved. The favorable estimated energy demand indicates the great potential of the demonstrated improved process.

Euler-Euler simulation of wood chip combustion on a grate – effect of fuel moisture content and full scale application

Nowadays, it is common practice to perform CFD calculations for optimisation purposes of technical biomass combustion applications. A numerical model for wood chip combustion on grate firing arrangements has been developed. The model is based on an Euler-Euler approach, enabling a detailed multiphase description of the combustion chamber in terms of flow, turbulence and heat transfer. The model explicitly accounts for interactions between bed and freeboard region and comprises a global description of the whole incineration process associated with wood combustion. For validation purposes, the effect of fuel moisture content in a 240 kWth test facility has been observed experimentally and the results are opposed to the model predictions. Additionally, measurements within a 58 MWth full scale grate firing system have been conducted and the scalability of the numerical model towards industrial applications is investigated.

Lagrangian Approach for the Prediction of Slagging and Fouling in Pulverized Coal Combustion

The deposition of ash particles in pulverized coal combustion provokes several problems for the operation of utility boilers. In order to avoid such problems, power plant operators have great interest in predicting the slagging and fouling tendency of the used fuel.For this purpose, an industrially highly relevant tool for the prediction of slagging and fouling which is applicable on high performance computing platforms such as vector machines or massively parallel systems has been developed. The model has been implemented into the CFD code AIOLOS and couples several relevant processes that are crucial for the build-up of depositions in power plants. It accounts for the flight of the ash particles through the furnace, the corresponding interaction with the flue gas and considers several deposition mechanisms on walls and tube bundles. In case of a predicted contact between a particle and a surface, the deposition rate is calculated based on the stickiness of the particle and the surface which is correlated with the melting behaviour. The model also takes into account the change of the heat transfer resistance of the already deposited particles and consequently the influence on the flue gas temperature.The model has exemplary been applied to a utility boiler with a thermal input of 730 MW (360 MWel) in order to demonstrate the capability of this engineering tool.