Experimental investigation on the mixing performance of heating gas into the low temperature sintering flue gas selective catalyst reaction facilities

The low sintering flue gas temperature is the main obstacle when applying Selective Catalytic Reduction (SCR) denitration process to sinter plants. Usually, extra heat input is supplied by adding hot flue gas to mix with the main flow. In the present work, the testing sintering flue gas preheating facilities are established to experimentally simulate this thermal mixing behavior. A novel type of flue gas mixing method, multiple jets into main flow, is proposed to replace the conventional single jet into cross flow. Three tubes with different jet holes are tested in the experiment. The mixing performance is evaluated by measuring the flow field, temperature field and gas concentration field. Quantitative assessments of the temperature and concentration mixed degree are determined by an unevenness parameter. The experimental results indicate that the hot flue gas jetting from multi-hole pipes can achieve better mixing uniformity than single jet. It was found that geometric characteristics of the jet holes have a significant effect on the jet flow's rigidity and penetration, which are the main factors affecting filling degree of jet flows. The results also demonstrate that jet hole configuration of 13 × Φ12 mm can achieve the best mixing performance. At the location which is 4.25 times the duct's hydraulic diameter away from the perforated pipe, the mixed unevenness figures of temperature and CO concentration are 0.24 and 0.18, respectively.