海水脱硫技术的优化研究

【作者】 李相军；

【导师】 高灿柱；

【作者基本信息】 山东大学 ， 环境工程， 2007， 硕士

【摘要】 华能日照发电厂地处山东省日照市，是一座海滨大型燃煤凝汽式火力发电厂，一期两台2×350MW机组，SO₂排放浓度和年排放总量分别为1757mg／Nm³和23778t，是本地SO₂的排放大户。国家环保总局要求日照电厂2005年底必须启动脱硫装置以适应目前治理日益严重的大气污染的需要。因电厂燃用含硫量小于1％煤，在海水碱度满足工艺要求、海域环境影响评价通过国家有关部门审查，并经全面技术经济比较后，优先采用海水法脱硫工艺。海水脱硫工艺是利用天然纯海水作为烟气中二氧化硫的吸收剂，无需其它任何添加剂，也不产生任何废弃物。海水烟气脱硫作为一种新型的脱硫工艺，具有技术成熟、工艺简单、投资省、运行方便、脱硫效率和投运率高等特点是其它脱硫工艺无法比拟的。烟气海水脱硫运行能有效控制燃煤电厂的SO₂的排放，同时削减粉尘的排放量，这对改善本地区的大气环境质量有着十分重要的意义。本文以日照电厂烟气海水脱硫为对象，将海水脱硫系统分为四个系统，分别对烟气系统、吸收塔系统、供排海水系统、海水恢复系统进行运行优化。通过对海水脱硫设备的介绍和对运行过程的分析，结合实际运行状况，提出脱硫设备运行中需解决的关键问题，从运行的角度提出优化方案，对相关电厂脱硫设备的运行有一定的参考和指导作用。首先研究烟气系统优化。调整烟道旁路挡板开关时间小于或等于5秒；脱硫烟气进出口挡板与增压风机联锁运行；先投运增压风机和进出口档板，待系统运行正常后关闭烟气旁路挡板。采用保持GGH两台密封风机运行以及干燥温度保持在90度左右。增压风机停止运行后，定期活动其动叶。保养时，GGH仍应转动，以避免由于烟道内不同的相对湿度而导致的不规则分布腐蚀。为提高吸收塔脱硫效率，使入口烟气的温度小于120℃，通过定期吹洗GGH内换热面上的积灰，达到较好的换热效果。入口烟气的小于30℃时，走吸收塔的旁路，以免引起吸收塔的严重腐蚀。增加当水位低报警时停运一台海水升压泵，水位低报警停运海水升压泵时，同时停运脱硫设备的运行。检查海水升压泵冷却水压力、流量、过滤器压差正常，根据负荷及烟气量的大小，及时调整海水升压泵的出力。海水排水的pH值小于6.8时，通过FGD旁路挡板门低位挡板的开度调节曝气池排水的pH值大于6.8，也可通过提高曝气风机压头，定期检查曝气池内的空气喷嘴，及时启停曝气风机的数量，使酸性海水、碱性海水中和与空气充分混合反应，使海水达标排放。更多还原

【Abstract】 The Rizhao power plant of Huan Neng is located at Rizhao City of Shandong Province, which is a seashore large-scale thermal power plant of coal-burning condensation type. The SO₂ emission concentration and yearly total quantity of two 2×350MW units respectively are 1757 mg/Nm³ and 23778 t. The plant is one of the largest SO₂ emission factories. The National Environmental Protection Bureau requested that the Rizhao power plant should start the desulphurization device to adapt to more and more serious air pollution by the end of 2005. Because the SO₂ concentration of burning coal is lower than 1%, the sea water alkalinity meets technologic requirement, and the sea area environmental effect appraisal passed the checking of the National Department, the sea water desulphurization is considered first.The sea water desulphurization technics used natural pure sea water as the absorbent to absorb SO₂ without any chemical additives and waste. The sea water desulphurization was one kind of new desulphurization technics, which had the advantagements of technologic maturation, the technologic simpleness, the running convenience and the high desulphurization efficiency, and got ahead of other desulphurization technics. The sea water desulphurization technics can effectively control the SO₂ emission of power plants, and meanwhile reduce the dust emission, which played an important role in improving the air quality.In this paper the sea water desulphurization of Rizhao power plant was researched. The desulphurization system was divided into four subsystems. The gas subsystem, absorbing tower subsystem, sea supply- emission subsystem, and sea renew subsystem are respectively studied. By the introductions of the desulphurization device, the analysis of the running process, and the running practice, the key problems of device running were proposed. The optimization measures were proposed from the point of running. Other power plants can learn these experiences.First the gas subsystem was studied. The time of the flue bypass baffle was adjusted to not more than five minutes. The baffle of the entrance desulphurization gas interlocked with the pressure fan. The pressure fan and the entrance and exit baffles were running first, and when the system ran normally, the flue bypass baffle was shut down. Two airproof machines of GGH were kept running and the drying temperature maintained at 90 centigrade degrees. The vanes were moved on schedule when the pressure fan shut down. GGH kept running when maintaining in order to advoid serious anomalous corrosion due to the difference of the flue relative humidity.In order to increase the desulphurization efficiency, the temperature of the entrance gas kept below 120 centigrade degrees. By blowing the accumulated ash of the GGH inner heat exchanging surface, good effect of heat exchange was achieved. When the temperature of the entrance gas was below 30 centigrade degrees, it passed through the bypass of absorbing tower for fear of the serious corrosion of the tower.The alarm of lower water level was added. When the alarm was given, the sea pressure pump and the desulphurization device were all shut down.Check the cooling water pressure, flux and the filter pressure difference of the pump. Adjust the pressure of the pump in time by load and the gas amount.When the pH of sea water was below 6.8, adjust the pH of air pool water exceeding 6.8 by the opening angle of the FGD bypass baffle. The sea water also can reach the standard by adjusting the fun pressure of the air pool, and making the acid and the alkali sea water neutralize and react mixed with the air.更多还原