1 Industry background and current situation

The glass manufacturing industry is an important basic building material industry in China. China's flat glass output has ranked first in the world for 30 consecutive years, accounting for about 60% of the world's total output. The glass manufacturing industry is also one of the important sources of air pollutant emissions from industrial production in the country. In 2019, the total emissions of nitrogen oxides, sulfur dioxide, and dust from the glass manufacturing industry's main atmospheric pollutants were 167,100 tons/year and 95,500 tons/year, respectively. , 14,500 tons/year.

According to the data from the National Pollutant Discharge Permit Management Information Platform and the data provided by the list of companies that meet the entry requirements for the flat glass industry released by the Ministry of Industry and Information Technology, as of March 2020, there are 180 flat glass companies in normal operation in my country. A large number of flat glass companies are distributed in key areas. Only Beijing-Tianjin-Hebei and the surrounding "2+26" cities have concentrated nearly 30% of their production capacity. As the "Glass Capital" of China, Shahe City is a key state controlled area due to its location around Beijing-Tianjin-Hebei.

Since the beginning of the 21st century, the Chinese government has paid more and more attention to environmental pollution issues. It has not only issued a series of environmental protection regulations and pollutant discharge standards, but also paid more attention to the supervision and implementation of local environmental pollution control work. On April 2, 2011, the Ministry of Environmental Protection and the General Administration of Quality Supervision, Inspection and Quarantine issued GB 26453-2011 "Emission Standard of Air Pollutants for the Flat Glass Industry". On February 1, 2013, Hebei Provincial Department of Environmental Protection issued DB 13/1640-2012 "Emission Standard of Air Pollutants for Industrial Furnaces". On June 13, 2017, the Ministry of Environmental Protection issued GB 28662-2012 "Iron and Steel Sintering, Pellet Industry Air Pollutant Emission Standards" and other 20 national pollutant emission standards amendments (draft for solicitation of comments), amending GB 26453-2011 " The Emission Standard of Air Pollutants for the Flat Glass Industry" adds special emission limits for air pollutants. It is planned to implement stricter pollutant emission control measures for the "2+26" cities in Beijing, Tianjin and Hebei.

At the end of 2018, the HJ 2305-2018 "Guidelines for Pollution Prevention and Control of Glass Manufacturing Industry" issued by the Ministry of Ecology and Environment was formally implemented on March 1, 2019. Guiding opinions and suggestions are put forward on the treatment technology and measures of industrial pollutants such as waste gas and waste water produced by the glass manufacturing industry, and they are used as a reference and basis for the application and issuance of pollution permits for glass enterprises. According to the "Guide" opinions, the technical routes that can be taken for glass furnace flue gas desulfurization include three types: wet desulfurization, semi-dry desulfurization, and dry desulfurization.

At present, in terms of waste gas treatment, the glass companies in Shahe area have basically built SCR denitration facilities, and most of the desulfurization uses wet desulfurization technology.

2 Problems of wet desulfurization in Shahe area

Although the wet desulfurization process is currently the most widely used desulfurization process technology with the highest desulfurization efficiency, due to the large difference in the technical level of desulfurization equipment and the uneven operation and maintenance management level of the glass enterprises in the Shahe area, problems exposed in production and use Increasingly, such as high operating costs, complex system management operations, serious equipment and pipeline clogging, wear and corrosion (Figure 1), by-product gypsum is difficult to deal with (due to market problems, it can only be stacked or landfilled), waste water is relatively serious. Difficult to deal with and expensive to deal with, chimney tailing, gypsum rain, etc.

In recent years, the haze weather in North China has become more and more serious. Some scholars and research institutions have pointed out the cause of the haze wet desulfurization, and believe that the large amount of water vapor and entrained pollutants discharged into the atmosphere by wet desulfurization contribute to the formation of haze. Have a great contribution. The flue gas humidity after wet desulfurization is more than 10 times that of ordinary air, and the secondary pollutants in the atmosphere will be adsorbed to form larger particles, serious aerosols and other pollutants. Under static and stable weather conditions, air quality deteriorated sharply, atmospheric visibility was greatly reduced, PM continued to "explode" at 2.5, and heavy haze was formed. Wet desulfurization has been pushed to the forefront of public opinion. Some areas have even begun to adopt policy compulsory measures to require wet desulfurization enterprises to "eliminate whitening" of flue gas.

3 Solutions and methods

For glass companies that use wet desulfurization, the most intuitive consideration to solve the "white smoke" problem is naturally to install a "whitening" device on the wet desulfurization facility, that is, to simply dehumidify the wet desulfurization flue gas to eliminate white smoke. The process flow See Figure 2.

However, simply "eliminating whitening" cannot solve many problems such as corrosion and blockage in wet desulfurization of various plants, and even introduce new problems. Equipped with a set of "whitening" facilities, not only the equipment construction cost is high, but also the system operation cost will be greatly increased, which will cause a great economic burden to the enterprise.

For glass companies in Shahe area, we must combine the actual conditions of the companies in the region and choose the most stable, reliable and cost-effective method in the long run. It can be considered to transform the entire wet desulfurization facility and adopt semi-dry or dry desulfurization technology to solve the problem. See Table 2 for the comparison of various technological measures.

4 Conclusion

In order to solve the current wet desulfurization problems of glass enterprises in Shahe area, the process technology comparison of various transformation methods has been carried out. After analysis and comparison, it can be concluded that:

(1) For the transformation of the environmental protection system of the original glass enterprise in Shahe area, it is necessary to completely solve the problem of wet desulfurization and reduce investment. The recommended plan is to retain the original SCR denitrification device and replace the wet desulfurization system with a semi-dry desulfurization system. Craft. See Figure 3.

(2) For glass companies that use clean fuels to produce new lines, they need to build a new flue gas environmental protection treatment system, and it is recommended to adopt the integrated process technology of dry desulfurization + denitrification and dust removal.