Krum Semkov

Mathematical modeling of gas distribution in packed columns

Abstract A dispersion model is proposed for the description of gas distribution in a packed column in the absence of liquid flow. The radial gas velocity profile is simulated for three different packing heights and compared with appropriate experimental data, obtained in a column with ‘honey-comb’ structured packing and gas distribution device (GDD). By separating the effect of the distributor from that of the packing layer, the additivity of packing redistribution capability and GDD is proved. The model parameters (distribution ability) are identified by means of non-linear optimization, minimizing the residual variance between the experimental and theoretical gas velocity. The model and experiment adequacy is checked. An analytical formula for the maldistribution factor is proposed, based on the model distribution parameter and initial condition only, and compared with the measured experimental maldistribution factor. Considering the studied packing, gas distribution coefficient is found based on the additivity of the obtained model parameters.

Systems Containing Contact Economizers for Flue Gas Heat Utilization

A reference is made to the fact that a significant part of the heat generated by combustion, is lost in the atmosphere with exhausted flue gases. Contact economizer systems are considered which help to utilize this heat by heating up the water before entering the boiler or by heating up urban heat supply water of the central heat supply network, as recycled back to the heating plant. Attention is drawn to some features of the new contact economizers which allow pressure drop values as low as 10–20 mm water head at high gas superficial velocities, i.e. up to 3 m/s. New process flow charts with contact economizers which helping to utilize heat at higher temperature levelsby simultaneous reduction of nitric oxides emissions down to 3 3 %, are given. The method developed for designing such systems is described, and data obtained in experiments with such industrial systems developed by the authors, are presented.

Industrial Heat Utilization Through Water Management

The focus of this article is on the dependence between water and energy in industry and the way these resources can be managed in an integrated and more sustainable manner. The fundamental methodology supporting the concept of simultaneous management of water and energy is the process systems approach guided by deep understanding of the simultaneous mass and heat transfer, considering phase and pressure changes. Special attention in this case is paid to the utilization of the latent heat of water evaporation and condensation (allowing for water and heat recycling). The article takes a new view of water solutions management, especially when processes experience difficulties for direct heat recovery. The article also highlights the links between water management, heat recovery, process efficiency improvement, and capacity de-bottlenecking, which bring additional positive impact of proposed methodologies. The advantages of efficiency improvement, water saving, and improved environmental impact of proposed solutions are analyzed and demonstrated for an industrial case.