亚氯酸钠溶液烟气脱硝与烟气余热回收的一体化试验

Removal of NO_x form Flue Gas by Integration NaClO_2 Solution and Surplus Heat Recovery

锅炉烟气中的NOx是大气污染的重要原因之一.针对燃气锅炉NOx超低排放的要求以及烟气中大量余热被浪费的现状,提出了烟气脱硝与余热回收一体化的新方法,通过搭建一体化试验台,分析在烟气余热回收的条件下,c[Na Cl O_2(亚氯酸钠)]、液气比、喷淋水温度等因素对脱硝效率以及烟气余热回收效率的影响.烟气脱硝与余热回收一体化的新方法主要体现在逆流式烟气喷淋塔中,可利用Na Cl O_2溶液对低φ(NOx)的烟气脱硝并同时回收烟气余热.试验结果表明,c(Na Cl O_2)越高、pH越低、液气比越大,Na Cl O_2溶液脱硝率越高.当c(Na Cl O_2)为0.020 0 mol/L、喷淋水温度在30~80℃之间变化时,存在最优的喷淋水温度64℃,使脱硝率最高为36%.同时,液气比及喷淋水温度对余热回收效果影响显著,液气比越大、喷淋水温度越低,余热回收效果越好.试验结果还显示了当烟气温度为83℃、喷淋水温度为48℃、c(Na Cl O_2)为0.015 0~0.020 0 mol/L、液气比为13.8 L/m3时,烟气脱硝效率约为40%,同时回收了26.4 k W的烟气余热.研究显示,在逆流式烟气喷淋塔中,利用Na Cl O_2溶液进行烟气脱硝并同时回收烟气余热的一体化方法是可行的,可应用于工程实践.

NOxfrom flue gas is a major source of air pollution. Challenges are posed because of the strict NOxemission standard implemented recently in China and the fact that tremendous heat is wasted in flue gas. We proposed a new method to integrate the removal of NOxwith NaClO2 solution and recovery of the flue gas surplus heat in a counter-flow spray tower. The integrated experimental system and conducted experiments were set up to study the influence of various factors on de-NOxefficiency,including c（NaClO2）,L/G,spraying water temperature,etc. A higher de-NOxefficiency could be achieved with higher c（NaClO2）,lower pH and larger L/G. When c（NaClO2） was 0. 0200 mol/L and spraying water temperature varied from 30-80 ℃,there existed an optimal spraying water temperature,64 ℃,resulting in a corresponding highest de-NOxefficiency of 36%. Meanwhile,L/G and spraying water temperature had significant effects on the heat recovery efficiency. The results indicated that the heat recovery performance could be improved with higher L/G and lower spraying water temperature. The experimental results showed that the de-NOxefficiency reached 40% and 26. 4 k W surplus heat was recovered,under the conditions that c（NaClO2） was 0. 0150-0. 0200 mol/L,liquid to gas ratio（abbr. L/G） was 13. 8 m3/L,gas temperature was 83 ℃ and the spraying water temperature was 48 ℃. The results indicated that the removal of NOxby integrating NaClO2 solution and surplus heat recovery of flue-gas is feasible.