Experimental study of swirl flow patterns in Gas Conditioning Tower at various entry conditions

In a gas conditioning tower hot flue gas with relatively high dust loads is cooled by injecting water spray near the top. For satisfactory operation wet particles should be kept off walls and all water should have evaporated to yield a uniformly cooled flow before it reaches the bottom of the tower. For practical reasons and space limitations the gas often enters through an inlet pipe making a 150-180° bend shortly before a short diffuser expanding to full tower diameter (Fig. 1). A swirl generator is placed immediately before the inlet to the diffuser to prevent recirculation near walls of the diffuser where cooling water is introduced and improve pressure recovery.Previous experimental studies [1] with a short, axial inlet pipe have shown that the distribution of axial flow could be improved considerably by inserting a swirl generator at the inlet to the diffuser. This gives strong back flow only in the central part of the diffuser. But actual designs involve a number of different designs of the inlet pipe, usually having a 150-180° sharp bend. The present experimental study is aimed at determining the influence of the inlet pipe design on the resulting flow in the upper part of the tower. The study is carried out using LDA-measurements and flow visualization in a 1:16 scale laboratory model. In addition, the degree of mixing on injected water spray is simulated by visualization studies to find the optimal position of injection nozzles.