NEWS CENTER

Cement industry dust removal "electric change bag" without delay


Release time:

Nov 28,2014

Since the beginning of this century, with the sustained and rapid growth of China's economy, the demand for resources and energy has been increasing, and the environmental pressure has become increasingly prominent. A series of popular words such as "sandstorm", "low carbon", "haze" and "PM2.5" appear frequently, which makes people pay special attention to environmental protection. The 18th National Congress of the Communist Party of China put forward "striving to build a beautiful China" as the ruling concept for the first time, and successively issued a series of policy documents. On the one hand, it cultivates and develops the environmental protection industry, on the other hand, it continuously improves the environmental protection standards to catch up with and surpass the world's advanced level. As a pillar industry of the national economy, the cement industry has made great progress. As of 2013

Since the beginning of this century, with the sustained and rapid growth of China's economy, the demand for resources and energy has been increasing, and the environmental pressure has become increasingly prominent. A series of popular words such as "sandstorm", "low carbon", "haze" and "PM2.5" appear frequently, which makes people pay special attention to environmental protection. The 18th National Congress of the Communist Party of China put forward "striving to build a beautiful China" as the ruling concept for the first time, and successively issued a series of policy documents. On the one hand, it cultivates and develops the environmental protection industry, on the other hand, it continuously improves the environmental protection standards to catch up with and surpass the world's advanced level.

As a pillar industry of the national economy, the cement industry has made great progress. By the end of 2013, the national cement output reached 2.41 billion tons, the national clinker production capacity was 1.86 billion tons, the output was 1.36 billion tons, and the national new dry process cement clinker production line reached 1714. After years of transformation and development, the cement industry has made great achievements in eliminating backward production capacity, pollutant treatment, waste heat power generation and so on. However, we should be soberly aware that the cement industry is still a high-consumption and high-emission industry, which is determined by the current cement production process. According to statistics in 2010, the dust emissions of the cement industry accounted for 31.7 of the total emissions of industrial production in the country. Such a large total discharge of pollutants has brought tremendous pressure to the ecological environment. According to statistics, more than 80% of the dust removal equipment used in cement kilns are electrostatic precipitators, and the emission standards are generally 50mg/Nm3~100mg/Nm3. According to the current situation of environmental protection in the cement industry and the actual needs of national environmental protection, the state has revised and improved the dust emission standards of the cement industry for many times.

The country's environmental protection requirements for cement production are very strict, and most of the electric dust removal equipment in operation will not be able to meet such high standards of emission requirements, and the existing enterprises will be implemented according to the new standards on July 1 next year. Therefore, the transformation of the original electric dust removal is imperative.

As a kind of high-efficiency dust collector, electrostatic precipitator occupies an absolute dominant position in the field of dust removal in the cement industry. However, the dust removal mechanism of the electrostatic precipitator itself and the characteristics of the cement production process determine that to meet the emission requirements of 20mg/Nm3, it is not possible to simply transform the original electrostatic precipitator, and it must be transformed into a bag filter from the dust removal mechanism. First of all, the original electric dust removal is designed and selected according to the emission of 50mg/Nm3, 100mg/Nm3 and 150mg/Nm3. To meet the new standard, its capacity itself is not enough. It is impossible to reduce the emission exponentially only by simply replacing parts and replacing the control mode. Increase the electric field, but also by the space site constraints, it is not necessarily able to achieve good results.

Secondly, the electrostatic precipitator is greatly affected by the specific resistance. After cooling by waste heat power generation, if the quenching and tempering treatment is no longer carried out, the specific resistance will exceed the reasonable range, and the electrostatic precipitator cannot meet the low emission requirements.

Again, the electrostatic precipitator cannot avoid accidental emissions. Taking the kiln tail electric dust removal as an example, when the cement kiln tail uses electric dust removal, CO detection system is installed for the safe operation of electric dust removal. When the CO concentration exceeds 2%, the high-voltage power supply will be automatically cut off. At this time, the electrostatic precipitator is only used as a flue gas channel with sedimentation effect, and the dust will be discharged to the air. It is estimated that when the emission standard is considered at 100mg/Nm3, if the time of CO exceeding the standard is calculated at 0.5, the total annual exceeding emission of the electrostatic precipitator caused by exceeding the standard of CO is equivalent to the total normal standard emission of the precipitator. If the new standard of 30mg/Nm3 is considered, if the time of CO exceeding the standard is calculated by 0.5, the total annual discharge of electrostatic precipitator caused by CO exceeding the standard is 3.3 times of the normal discharge of electrostatic precipitator. However, it is impossible to control the time of CO exceeding the standard within 0.5%, most of which are 1% and some even reach 2%. Therefore, the total amount of accidental emissions caused by excessive CO will be extremely alarming, which is not allowed by the new standard. Therefore, the new standard stipulates that the synchronous operation rate of environmental protection equipment and host equipment is 100.

Finally, the bag dust collector overcomes the deficiency of electric dust removal from the dust removal mechanism, and can completely avoid the accident discharge. China's bag dust removal from filtration technology to dust removal technology has made great progress, filter material life is greatly extended, operating costs are greatly reduced, can fully meet the emission requirements of the new standards.

In summary, the transformation of the cement industry into a bag filter is a necessary choice to meet the new standards, and it is also a feasible choice. "Electric change bag" without delay.