THE CORRESPONDING RELATIONSHIP BETWEEN HEAT, MASS TRANSFER COEFFICIENTS AND THE FLOW REGIME IN DUAL-CONTACT-FLOW ABSORPTION TOWER

The flow, heat and mass transfer performance under different nozzle arrays in the dual-contact-flow absorption tower has been studied, together with the interrelation between the probability dense function (PDF) and the flow, heat and mass transfer characteristics. The experimental results show that, for the same nozzle array, both the heat and mass transfer coefficients (h and h(m)) increase with the gas velocity increasing at first; However, both coefficients (h and h(m)) start to decrease due to the reduction of the liquid-gas contact time after approaching a certain extent. Moreover, with the increase of liquid injection rate nu(p0), the two coefficients (h and h(m)) decrease, while the total heat and mass transfer values rise. In addition, the mass transfer coefficient decrease with the increase of nozzle number. In the absorption tower, the leading role gradually transfers to gas phase from liquid phase with the increase of gas velocity. The flow regimes' transition process can be explained as follows: the liquid column flow type, the liquid screen flow type, the convergent liquid screen flow type, and the gasping flow type. Moreover, the increase of gas velocity has effects on the probability dense function (PDF). With the flow regimes' transition, change of PDF performs as follows: the number of the PDF peaks increases from one to a larger quantity and finally decreases to a single one after that; the average pressure drop Delta P-mean increases as well as the peak-peak spacing delta(peak). However, the pressure drop distribution range l(Delta P) first increases and then decreases.