【作者】 严长勇；

【导师】 沈恒根；

【作者基本信息】 东华大学 ， 供热、供燃气、通风与空调工程， 2006， 硕士

【摘要】 近年来,我国电力工业持续快速发展,截至2004年底,电力发电装机容量已达到4.4亿千瓦,其中燃煤火力发电厂占到75%左右,燃煤过程产生的飞灰颗粒污染物是环境空气污染的主要因子之一。火电厂大气污染排放标准(GB13223-2003)中规定:新建燃煤电厂锅炉从2005年开始、原有燃煤电厂锅炉在2010年以前,烟尘最高允许排放浓度为50mg/m~3。同时由于排放总量的限制,许多城市严格要求烟尘最高允许排放浓度达到30mg/m~3以下。 袋式除尘器的关键技术之一是布袋过滤材料(以下简称滤料),由于技术不过关,造成了上世纪80年代使用袋式除尘器受挫。袋式除尘器在燃煤电厂锅炉控制烟尘排放中的应用整整停滞了近20年,形成了静电除尘器一统天下的局面。但是,目前若继续采用静电除尘器来满足新的排放标准则具有一定的技术难度和经济压力,尤其是城市电厂。 国外20多年来的应用经验和近年来国内引进技术在工程实施的结果表明,袋式除尘器可以达到新标准的要求。但是布袋滤料依靠进口,价格昂贵,加之燃煤成分、锅炉设备、运行管理条件的差异进一步造成排放烟气成分更加复杂,使得布袋滤料成为国内推广使用袋式除尘器的瓶颈。 本课题主要是针对国电集团公司天津市第一热电厂13号炉的三电场静电除尘器改为袋式除尘器工程,它要求烟尘的排放浓度满足低于30mg/m~3的天津市地方环保要求。该课题技术难点在于,把原来主要用于燃用低硫煤电厂锅炉袋式除尘技术进一步扩充到燃用高硫煤上,对滤料的技术要求进一步提高。 针对工程需求,本课题重点改进了针刺滤料结构、材料组成和后整理措施,即采用具有表面超细纤维层、逐层逐渐采用更粗纤维层的梯度结构;过滤层主要采用PTFE与PPS复合纤维,采用PTFE与适量玻璃纤维做底层,采用PTFE与玻璃纤维混合基布;对制成的针刺滤料进行整体PTFE浸渍处理,给使用纤维的表层黏附PTFE膜,尤其是对非PTFE纤维防腐耐温拒水意义重大,命名为华博特梯度滤料(简称HBT梯度滤料)。 采用电镜扫描的手段,观察了HBT梯度滤料的组织结构,进行了结构分析。该滤料的特点在于表层采用超细纤维层,滤料结构形成的流体通道呈现为前窄后宽。这种构造改变了长期以来采用单一尺度单一品种纤维制作的具有“等宽”流体通道的常规滤料结构,减缓因长期使用造成滤料后期阻力上升的问题。由于采用超细纤维面层,吸取了覆膜滤料表面过滤优点,形成更具耐用性的表层过滤技术特色。 参照国内外滤料过滤性能测试的相关标准,设计了滤料过滤性能冷态实验台,配套Grimm环境尘粒监测仪等仪器。不仅能够测试滤料对环境气溶胶中PM10、PM2.5、PM1.0的过滤效率,还可以测试滤料对PM10粒子分级过滤效率的测试(粒径范围为0～10μm,分级13档,最低尺度为0.3μm)。由于采用环境气溶胶对清洁滤料进行过滤性能测试,不同滤料过滤效率差距明显,并可以实现快速测试。 对三类不同过滤模式(表面过滤、表层过滤和深层过滤)的13种高温烟气除尘滤料进行了冷态过滤性能测试,测试结果表明:滤料在清洁状态下对环境气溶胶过滤效率由高到低依次为:表面过滤滤料(覆膜滤料)、表层过滤滤料(梯度滤料)、深层过滤滤料(常规滤料);对环境空气的过滤阻力由低到高依次为:深层过滤滤料、表层过滤滤料、表面过滤滤料。提出的HBT梯度滤料性能既接近覆膜滤料的高效、又接近P84滤料的低阻,加之进行防腐耐温后整理,作为筛选后的品种可用于高硫煤烟气袋式除尘中。 为了解滤料在清灰时,反向气流的作用特性,对滤料反向的过滤性能进行了测试。结果表明,大多数滤料正向的过滤效率要大于滤料反向的过滤效率;梯度滤料和覆膜滤料正反向更多还原

【Abstract】 In recent years, the power industry of our country is developing quickly, and the power capacity had exceeded 440 million kilowatts till the end of 2004, 75 percent of which was from coal-fired plant. The micro-particle of fly ash which produced from the coal fired is one of the primary factors of the air pollution. The emission standard of air pollutant for thermal power plant (GB 13223-2003) stipulates that the highest allowed dust emission concentration of the new coal-fired plant after 2005 and the old coal-fired plant before 2010 should be 50 mg/m3. For the gross emission limit, it is strictly stipulated in many cities that the dust emission concentration must be below 30 mg/m3.The filter media is one of the pivotal technologies of the bag filter, and the bag filter was used unsuccessfully in 1980s due to the unsophisticated technology of filter media. The bag filter using on dust control of core-fired plant was bogged down for 20 years, and meanwhile the electrostatic precipitator was used widely. But there are technical difficulty and economical stress to meet the new emission standard if the electrostatic precipitator goes on to be used, especially for city coal-fired plant.The experience of international application over 20-odd years and the results of projects introduced into our country show that it can meet the new emission standard by using the bag filter. But the source of filter media depends on importing, and the price is very high. Because of the ingredient of the core, the boiler and the managing condition, the ingredient of the gas is more complex. All of the above-mentioned are the bottle-neck of extending extensively the bag filter nationally.This paper is for the project of GUODIAN First Coal-fired Plant’s No. 13 boiler which uses bag filter to replace the old three electric fields’ electrostatic precipitator in Tianjin. The project requires that the dust mission concentration is lower than 30 mg/m3, which are the request of Tianjin local environmental protection. The challenge of this paper is how to extend the bag filter from the plant boiler burning low sulfur core to the plant boiler burning high sulfur core, which requires the filter media technology must be advanced.Aiming at the request of the project, the measure to ameliorate filter media is advanced in this paper, and the emphases are ameliorating the filter media’s structure, material and technics of production. The filter media’s echelon structure is that the surface layer adopts microfibre and the thicker fibre is used in next layers. The filter layer adopts the fibre of PTFE and PPS, and the bottom layer and the substrate adopt the fibre of PTFE and fibre glass. Furthermore, the needle filter media is steeped by PTFE, and the surface layer of the fibre is conglutinated PTFE membrane. It is signality for the antisepsis, hot resistant and the water-refuse. This filter media is named after HUABOTE echelon filter media (for short, HBT echelon filter media).By dint of the means of scanning electron microscope, the structure of HBT echelon filter media is analyzed. The characteristics of this filter media are that the surface layer adopts microfibre and that the hydro-channels of the filter media’s structure are narrow in the front and wide in the back. The traditional filter media is produced by the fibre of the same measure andvariety, and this structure alters the traditional filter media’s structure which is the same width hydro-channel. This solved the problem that the filter resistance ascends along with the filter media used. Because the HBT echelon filter media’s surface layer adopts microfibre and assimilates the excellence of the membrane media’s surface filter, it forms the characteristic of top layer filter which has longer service life.The testing device for filter performances of filter media under normal temperature is designed, after referring to domestic and international testing standards for filter performance of filter media. The testing device adopts Grimm Environmental Dust Monitor instrument. It not only can test the filter efficiency of filter media for PM10, PM2.5, and PM1.0, but also can test the grade filter efficiency for dust whose particle diameter is under 10 u m (the particle diameter range is from 0 to 10 u m, divided into 13 steps, and the lowest measure is 0.3 u m). Because of having adopted the circumstance aerosol to test the filter efficiency of clean filter media, the efficiency difference of different filter media is obvious, and it can test quickly.The 13 kinds high-temperature filter media for dust separation are divided into three species by the different filter ways (surface layer filter, top layer filter, and deep layer filter), and their filter performances are tested.. The testing result shows that the order of the filter efficiency of clean filter media for the circumstance aerosol from high to low is surface layer filter media (membrane filter media), top layer filter media (echelon filter media), and deep layer filter media (traditional filter media);the order of the filter resistance for circumstance air from low to high is deep layer filter media, top layer filter media, and surface layer filter media. The HBT echelon filter media’s performance is not only close to membrane filter media’s high filter efficiency, but also close to P84’s low filter resistance. It can be used for dust separation of boiler burning high sulfur core, after especial disposing, for example, antisepsis and hot-resistant.The reversed filter performances of filter media are tested, for realizing the effect of counterblast when clearing dust. The result shows that the efficiency of obverse filter media is higher than the efficiency of reverse;the "echelon" compound filter media and membrane filter media have different two-faced filter efficiency, but their reversed filter efficiency are still higher compared with other traditional filter media, for example P84.The boiler capacity of Tianjin First power plant is 220T/h, and the emission concentration of the electrostatic precipitator before reformed is 444.56mg/Nm3 which exceeds the standards badly. The design parameters are that the gas capacity is 400,000m3/h, the gas temperature is 150°C, and the sulphur content is 4530mg /m3. The filter velocity of bag filter is 0.96m/min, and the filter bag is made of HBT echelon filter media, whose filter area is 6900 m2. After three months’ using, the running result tested by Tianjin Environmental Testing Station shows that the dust mission concentration is blow 30 mg/m3 and the running resistant is about 1100 Pa. Now the running status satisfies the design request, but the service life waits for the testing of using time.更多还原