【作者】 陈湘文；

【导师】 高翔； 骆仲泱； 倪明江；

【作者基本信息】 浙江大学 ， 工程热物理， 2008， 硕士

【摘要】 喷淋塔是石灰石-石膏湿法烟气脱硫装置的主要设备之一，对喷淋塔内部结构的优化研究一直是研究者们的感兴趣的课题。本文建立装有多孔筛板的内径148mm喷淋塔实验台，并进行了相关的研究。装入多孔筛板，喷淋塔内部流场及塔内气液两相接触的方式完全改变，因此有必要对筛板进行气液流动特性研究。采用空气．水作为介质，对孔径范围6～30mm，开孔率范围16～48％的筛板气液两相流动触状态进行了测试，详细考察了空塔压降、湿塔压降、持液量和泡沫层高度随空塔速度、喷淋量、筛板孔径、筛板开孔率、筛板安装位置、筛板厚度等的影响，并分析了不同孔径、开孔率下的起泡点与液泛出现的规律。在筛板式喷淋塔实验台上进行了脱硫性能测试，讨论了筛板上气液流动情况和筛板设计参数（如筛板孔径、筛板开孔率、筛板安装位置、筛板厚度等）对脱硫效率的影响。实验发现，脱硫率效率的高低和筛板上气液两相的流动情况密切相关。只有在气液两相处于气液接触良好的湍流强度较大的泡沫振动状态或相对较厚的均匀鼓泡区，才能保证SO₂充分被吸收；当筛板上出现泡沫层高度过小，甚至筛板上无泡沫层，或是塔内烟气速度过大，出现液泛的情况，塔内泡沫层的均匀性严重受到破坏，在这两种情况下，脱硫效果比较差。通过实验研究，发现当固定开孔率为36％时，孔径为12mm的筛板拥有最高的脱硫效率；当固定孔径为15mm时，开孔率为36％的筛板拥有最高的脱硫效率。通过对筛板式喷淋塔与无筛板的喷淋塔进行对比，在筛板工作状态良好的情况下，筛板式喷淋塔比无筛板的喷淋塔效率高出2～6％（绝对值）。在速度较高的同等条件下，甚至高出15％。在装有双层多孔筛板的喷淋塔实验台上，采用NaClO₂作为添加剂，CaCO₃浆液作为吸收液，进行了协同脱硫脱硝实验，讨论了浆液pH值、入口NO、SO₂浓度、L／G以及添加剂加入量对NO、SO₂脱除效率的影响。通过对比实验发现，单独脱硝实验中，脱硝效率只有6％；协同脱硫脱硝实验中脱硫效率和脱硝效率分别为97．5～100％和40．8～60．5％。更多还原

【Abstract】 Optimization of Spray scrubber, which is one of the essential equipment of the The limestone/gypsum wet flue gas desulfurization（WFGD） process in thermal power plants, seized great concern of the researchers in the past decades. Among all the methods of optimization, installing a sieve tray in the spray scrubber is of the most economical and promising. In order to find out the characteristic of the sieve tray in the scrubber, a spray scrubber test stand with diameter of 148mm for limestone/gypsum wet flue-gas desulfurization with sieve tray was established.An experiment was performed to study the contacting mechanism in the vapor-liquid two-phase flow on the sieve tray, which is far from the same as the conventional spray scrubber. Air-water system had been used to study the nature of the two-phase mixture produced on the sieve tray with diameters from 6mm to 30mm and the free area from 16% to 48%. The Influence of the superficial velocities, liquid rates, hole sizes, free area, the locations and thickness of the tray on the dry pressure drop, spray pressure drop, liquid hold-up, froth height was discussed. The principles of the bubbling start-point under different hole sizes and free area were also showed in this article.Next, the desulfurization performance test was performed on the same scrubber. The major parameters which would influence the desulfurization efficiency were discussed, as the pH value, L/G ratio, superficial velocity, hole sizes, free area, the location and thickness of the tray. It was found that only when the vapor-liquid two-phase flow is in the vibration and thick froath regime, in which the two-phase flow is contacting sufficiently, the SO₂ removal efficiency will be high, otherwise in the regime that the foath is low or the flooding point appeared. Also it was found that when the free area of the tray is 36%, with great hole sizes, comes high desulfurization efficiency. And when the hole diameter is 12mm, the highest desulfurization efficiency comes when the free area is about 36%. In the test, the desulfurization efficiencies in the scrubber with sieve tray and the one without tray were compared. Commonly, the scrubber with sieve tray has a higher of 2 to 6 percent desulfurization efficiency （absolute values）, when under the higher speed, the predominance would be 15 percent. As a consequence, the tray could bring high desulfurization efficiency in the scrubber.Third, the study used NaClO₂/CaCO₃ as the additive/absorbent to determine the extent of NO removal in a wet scrubber with dual sieve tray. The operating variables included pH value, NO and SO₂ concentrations, L/G ratio and NaClO₂/（NO+SO₂） molar ratio. The results indicated that, in the individual denitrification experiment the maimum NO removal efficiency is only 6%, The results of the simutaneous desulfurizatoin and denitrification experiments show that the maximum NO removal efficiencies ranged from 40.8～60.5% and the SO₂ removal efficiency were 97.5～100%.更多还原