Pressure drop of structured packing in pilot column and comparison to common correlations

Packed columns are widely used in the chemical industry such as absorption,stripping,distillation,and extraction in the production of e.g.organic chemicals,and pharmaceuticals.Pressure loss and pressure drop correlations are of special interest when it comes to the hydrodynamic properties of a column.The pressure loss across the column is of interest in the design phase when the size of the blower to drive the gas stream through the column has to be decided.The loading point and flooding point are also influenced by the pressure loss and the area of operation is determined from these points.This work examines four different correlations on pressure drop.The correlations are(i)Ergun’s equation(1952),(ii)an improved version of Ergun’s equation by Stichlmair,Bravo,and Fair(1989),(iii)an equation developed by Billet and Schultes(1999),and(iv)an equation by Rocha,Bravo,and Fair(1993).The complexity of the correlations is increasing in the mentioned order,Ergun’s equation being the simplest one.This study investigates if the more complicated correlations give better predictions to pressure drop in packed columns.This is determined by comparing the correlations to experimental data for pressure drop in a packed column with 8.2 m of structured packing using water as the liquid and atmospheric air as the gas.Seven experiments were carried out for determining the pressure drop in the column with liquid flows varying from 0 to 500 kg·h^(-1).At constant liquid flow,the gas flow was varied from approximately 10 to 70 kg·h^(-1).The pressure drop across the non-wetted column was best described by the correlation by Rocha et al.while the pressure drop for liquid flows from 100 to 500 kg·h^(-1)was,in general,best described by Stichlmair’s equation.For an irrigated column,the highest deviation was a predicted pressure drop 69.6%lower than measured.The best prediction was 0.1%higher than the measured.This study shows,surprisingly,that for a system of water and atmospheric air,complicated correlations on pressure drop determination do not provide better estimates than simple equations.

Reliability study of super-ellipsoid DEM in representing the packing structure of blast furnace

In industrial blast furnaces(BFs),the investigations involving the flow behaviors of particles and the resultant burden structure are essential to optimize its operation stability and energy consumption.With the advance of computing capability and mathematical model,the discrete element method(DEM)specialized in characterizing particle behavior has manifested its power in the investigation of BFs.In the framework of DEM,many particle models have been developed,but which model is more suitable for simulating the particle behaviors of BFs remains a question because real particles in BFs have large shape and size dispersity.Among these particle models,the super-ellipsoid model possesses the ability to change shape flexibly.Therefore,the focus of this study is to investigate whether the super-ellipsoid model can meet the requirement of authenticity and accuracy in simulating the behaviors of particles with large shape and size dispersity.To answer this question,a simplified BF charging system composed of a hopper and a storage bin is established.The charging process and the final packing structure are analyzed and compared between experiments and simulations with different shape indexes.The results show that super-ellipsoid particles have prominent advantages over spherical particles in terms of representing the real BF particles,and it can more reasonably reproduce the flow behaviors and packing structure of experimental particles.The computation cost of super-ellipsoid particles is also acceptable for engineering applications.Finally,the micro-scale characteristics of packing structure is analyzed and the single-ring charging process in industry-scale BF using super-ellipsoid particles is conducted.

Liquid-solid mass transfer in a rotating packed bed reactor with structured foam packing

A rotating packed bed(RPB) reactor has substantially potential for the process intensification of heterogeneous catalytic reactions. However, the scarce knowledge of the liquid–solid mass transfer in the RPB reactor is a barrier for its design and scale-up. In this work, the liquid–solid mass transfer in a RPB reactor installed with structured foam packing was experimentally studied using copper dissolution by potassium dichromate. Effects of rotational speed, liquid and gas volumetric flow rate on the liquid–solid mass transfer coefficient(kLS) have been investigated. The correlation for predicting kLSwas proposed, and the deviation between the experimental and predicted values was within±12%. The liquid–solid volumetric mass transfer coefficient(kLSaLS) ranged from 0.04–0.14 1^-1, which was approximately 5 times larger than that in the packed bed reactor. This work lays the foundation for modeling of the RPB reactor packed with structured foam packing for heterogeneous catalytic reaction.

Effect of counter current gas phase on liquid film

Liquid film flow is very important in many industrial applications.However,there are few reports about its characteristics on structured packings.Therefore,in this paper,liquid film phenomena were investigated experimentally to exploit new approaches for intensifying the performance of the structured packings.All experi-ments were performed at room temperature.Water and air were the working fluids.The effect of counter current gas phase on the liquid film was taken into consideration.A high speed camera,a non-intrusive measurement techni-que,was used.It is shown that both liquid and gas phases have strong effects on film characteristics.In the present work,liquid film width increased by 57% because of increasing liquid flow rate,while it decreased by 25%resulting from the counter current gas phase.