George K V, Manjunath S, Rao C V Chalapati, Bopche A M
National Environmental Engineering Research Institute, Nagpur, 440020, India.
Environ Technol. 2003 Nov;24(11):1425-30. doi: 10.1080/09593330309385686.
Almost all coal based thermal power plants (CTPP) in India use electrostatic precipitator (ESP) for reduction of particulate matter (PM) in flue gas generated due to the combustion of Indian coal. This coal is characterized by high ash content, low calorific value and low sulfur content resulting in the generation of a very large amount of highly electrically-resistive fly-ash; thereby requiring a very large size ESP to minimize the fly-ash emissions. However, the flue-gas particle size distribution analysis showed that 60% of the particles are above 15 microm size, which can be conveniently removed using a low-cost inertial separator such as a cyclone separator. It is proposed that a cyclone be used, as a pre-cleaner to ESP so that the large size fraction of fly-ash can be removed in the pre-cleaning and the remaining flue-gas entering the ESP will then contain only small size particles with low dust loading, thereby requiring a small ESP, and improving overall efficiency of dust removal. A low efficiency (65%), high throughput cyclone is considered for pre-cleaning flue gas and the ESP is designed for removal of the remaining 35% fly-ash from the flue gas. It is observed that with 100% dust load, the ESP requires six fields per pass, whereas with cyclone as a pre-cleaner, it requires only five fields per pass. Introducing cyclone into the flue gas path results in additional head loss, which needs to be overcome by providing additional power to induced draft (ID) fan. The permissible head loss due to the cyclone is estimated by comparing the power requirement in the bag filter control unit and cyclone-ESP combined unit. It is estimated that a head loss of 10 cm of water can be permitted across the cyclone so as to design the same for 65% efficiency.
印度几乎所有的煤基热电厂（CTPP）都使用静电除尘器（ESP）来减少因燃烧印度煤炭而产生的烟道气中的颗粒物（PM）。这种煤炭的特点是灰分含量高、热值低、硫含量低，导致产生大量高电阻飞灰；因此需要非常大尺寸的ESP来尽量减少飞灰排放。然而，烟道气颗粒尺寸分布分析表明，60%的颗粒尺寸大于15微米，使用低成本的惯性分离器（如旋风分离器）可以方便地去除这些颗粒。建议使用旋风分离器作为ESP的预清洁器，以便在预清洁过程中去除大部分大尺寸飞灰，进入ESP的剩余烟道气将只包含低粉尘负荷的小尺寸颗粒，从而所需的ESP尺寸较小，并提高整体除尘效率。考虑使用低效率（65%）、高处理量的旋风分离器来预清洁烟道气，ESP则设计用于去除烟道气中剩余的35%飞灰。据观察，在100%粉尘负荷下，ESP每次通过需要六个电场，而使用旋风分离器作为预清洁器时，每次通过仅需要五个电场。在烟道气路径中引入旋风分离器会导致额外的压头损失，这需要通过给引风机（ID）提供额外动力来克服。通过比较袋式过滤器控制单元和旋风分离器-ESP组合单元的功率需求来估算旋风分离器允许的压头损失。据估计，旋风分离器允许的压头损失为10厘米水柱，以便将其设计为效率65%。
