Abstract: The main fuels in the process of melting glass are petroleum coke powder, heavy oil, and natural gas. The smoke generated after combustion is highly polluted by air. The main pollutants are sulfur oxides, nitrogen oxides, etc., which are also polluted the air. The most important ingredient, long-term pollution not only destroys the ecological environment but also greatly threatens people's lives and health. Therefore, in the process of glass production and manufacturing, the dust removal and treatment of pollutants should be strengthened, and the sulfides in the flue gas should be fully purified so that the discharged flue gas can reach the relevant discharge standards and achieve clean production of the glass. The article starts with the characteristics of glass furnace flue gas and analyzes and analyzes the status quo and development of China's glass flue gas treatment technology.
1. Characteristics of glass furnace flue gas
At present, the fuels commonly used in China's glass production process are heavy oil, coke powder, natural gas, etc. Generally, the exhaust gas temperature is 400-550 °C during production. These fuels usually produce large pollution when burning, and the pollutants include SOx. Dust and NOx and other categories. Generally speaking, the pollutants emitted during the combustion process are affected by factors such as the type of fuel, the proportion of ingredients, and the content of flue gas during combustion. The concentration of flue gas emitted is 500-3 000 mg / Nm3, and the kiln producing glass. The concentration of NOx emitted from the furnace is 1 200-3 000 mg / Nm3. The dust generated by the kiln during the refining process has the characteristics of small particle size, and the contaminated gas also has high alkali content, strong adhesion, and corrosion. Strong characteristics, if these pollutants and dust are not treated after burning, the consequences of environmental pollution will be very serious. The concentration of the dust produced is different using different fuels, and the concentration fluctuates within the range of approximately 300 to 1 200 mg / Nm3. It can be concluded from the above data that the smoke and dust generated by the glass in the production process has exceeded the discharge standards stipulated by the state, and the glass furnace flue gas has the characteristics of high pollution.
2. Current problems with flue gas desulfurization
Compared with the developed countries in the world, China's current flue gas desulfurization technology still has a large gap, and it is necessary to increase R&D investment to promote technological progress to narrow the gap. However, the desulfurization technology with good flue gas treatment effect, fast production process, and high efficiency has a high threshold, which requires a large investment. The cost of the site, the cost of equipment operation, and the large area occupied by the land limit the desulfurization. The development of technology. At present, most of the main desulfurization equipment have been localized, but the degree of automation is not high, which is the part that is urgently needed to be improved.
There are still many differences between desulfurization technology and other energy-saving and environmental protection technologies. The recycling of pollutants after desulfurization technology treatment still requires more research and development. It requires local government departments to give certain policy inclinations and increase research and development. Expenditure, recruit relevant technical personnel to study the latest technology of desulfurization, research the technology that meets the desulfurization market of China's glass industry, carry out scientific and technological innovation, increase the transformation of scientific and technological achievements, promote the support of high-tech in core products, and strengthen the cross-cutting of environmental protection industry. Exchange and promote the sustainable recycling of desulfurization products to achieve the integration of desulfurization technology with other environmental technologies. Although the glass furnace kiln desulfurization technology is relatively mature, the complete process of the entire desulfurization process still needs further improvement.
3. Flue gas comprehensive treatment technology
3.1 Dust removal technology
Because glass kiln produces more fumes in the process of producing glass, and this soot has the characteristics of small particle size, high viscosity, strong corrosiveness, etc., although gravity dusting and cyclone dusting are usually used, although they have certain effects, The fine dust treatment effect is very unsatisfactory and can not achieve the expected treatment effect. Although the dust removal method is better, it is easy to cause secondary pollution. The temperature of the post-treatment flue gas is still lower than the minimum requirement of the denitration process. In addition, there are many disadvantages such as high use of sewage treatment equipment, high energy consumption, high cost, and high maintenance cost of equipment in the later stage. It is not suitable for large-scale production; the working environment of bag filter is generally in a flue gas environment with a temperature below 200 °C. And the loss of equipment is large, life is short, and it is not conducive to putting into use.
At present, a better dust removal method is electric dust removal. Electrostatic dust removal not only can effectively remove dust, so that the dust removal effect can reach the relevant emission standards, and it can effectively ensure the dust removal effect in the later stage so that the temperature of the flue gas can reach a relatively stable level and meet the follow-up. Denitration process For the relevant requirements of soot concentration and temperature, the technology has been widely used in chemical, cement, and other industries.
High-temperature electric dust removal in the glass industry is a system that uses a strong electromagnetic field at a specific temperature to separate fine particles from smoke. In the high-temperature electric dust removal work, the working principle is that high-voltage direct current is applied to the negative pole, and the positive pole is grounded. Due to the different properties of the positive and negative poles, a strong asymmetric electric field can generally be generated after energization, so that the electric ions between the electric fields are mutually The effect is to generate a large amount of positive and negative electrode ions. After the dusty flue gas is transported to the electric field, the dust forms charged dust under the interaction of electrons and ions. The negatively charged dust and the positively charged dust move to the poles under the action of the electromagnetic field, and the final result is attracted. To the dust collection. After the dust collects a certain amount of dust, the vibration device has a certain amount of ionizing magnetic field on the dust collecting body, so that the dust has fallen into the ash hopper below under the dual effects of self-weight and vibration, and the electricity is removed by the screw device. Outside the dust removal, the flue gas enters the denitration system through the outlet of the electrostatic precipitator for denitration treatment.
3.2 Denitration technology
At present, there are two main types of flue gas denitration technologies, one is a selective catalytic reduction (SCR) and the other is non-catalytic reduction flue gas denitration (SNCR). These two technologies are relatively mature. There are also more applications.
3.2.1 Selective Non-Catalytic Reduction (SNCR) Denitration Technology
This denitration technology is mainly applied to the ammonia reductant such as ammonia water or ammonia by spraying into a suitable place in the glass furnace without using a catalyst. The temperature of the kiln is generally controlled at 950 to 1 010 °C, and the relatively high temperature. The ammonia in the sprayed reducing agent is chemically reacted with the polluting component that generates the flue gas to produce uncontaminated water. Most of this production process is currently applied to thermal power plants, boilers, kiln, etc., which can effectively treat flue gas.
In addition, this denitration technology has the characteristics of low cost and good effect, which can bring high economic benefits. However, it is not without its shortcomings. The application environment is affected by the temperature, humidity, smoke density and other conditions in the furnace. It will also have a certain degree of influence on the production of glass during the process of dust removal. Therefore, this process has certain limitations. Sex.
3.2.2 Selective catalytic reduction (SCR) flue gas denitration technology
The working principle of this technology is that under the action of the denitration catalyst, the working ambient temperature is about 280 ~ 420 °C, and NH3 is injected into the flue gas to react with harmful gases in the flue gas to produce uncontaminated water. Therefore, the emission of nitrogen oxides in the flue gas is reduced to meet the emission standards.
At present, this process technology is also widely used in the removal of nitrogen oxides such as thermal power plants, pollutant incineration plants, industrial boilers, etc. This denitration technology can achieve a denitration efficiency of 70% to 98%, and the denitration efficiency is very stable. The service life is also relatively long, which can reach 26,000 hours, and thus the application range is wide.
The catalyst used in this denitration production process has been basically automated and industrialized. The structure of the catalyst is many. The common structural forms are honeycomb, corrugated, etc. The catalyst is usually titanium dioxide as the main carrier, vanadium pentoxide is The main reaction component. This denitration technology has high denitration efficiency, a wide range of temperature requirements, and the entire denitration technology does not produce secondary pollution. It is the most widely used and most effective denitration method .
3.3 Desulfurization technology
At present, the fuels commonly used in the production of glass in China include heavy oil, natural gas, and coal gas. The components of the polluting gases produced after combustion mainly include SOx and NOx. The level of pollutant gas is usually related to the use of different fuel types. If the process of producing glass is made of petroleum coke powder, heavy oil, and other fuels, it will cause great difficulty in desulfurization; if natural gas or gas is used as fuel, desulfurization will be relatively simple, and at the same time, it can meet the requirements of relevant emission standards.
At present, the more popular flue gas desulfurization processes can be divided into the dry method, semi-dry method, and wet method. The traditional dry desulfurization efficiency is low, and the desulfurization is not thorough enough. However, the international dry desulfurization method is simple and effective, but the operation cost is high, the operation difficulty is relatively large, and the economic benefit is not good, so it is not completely desulfurized. Applied on the project. At present, the wet desulfurization technology has a wide application range, and the desulfurization efficiency and the utilization degree of the later absorption agent are relatively high. However, if this technology is applied to the glass furnace, there are many problems, and the glass furnace and kiln will be corroded first. The inner wall will also generate more dirt at the bottom, and the discharge will not reach the standard, resulting in more wastewater. The semi-dry desulfurization method has unparalleled advantages. This process has high desulfurization efficiency, requires small equipment, small investment, stable operation, and no secondary pollution after desulfurization. Because semi-dry desulfurization technology is very dominant, it is widely used in industrial boilers, waste incineration, and other industries. Therefore, the semi-dry method is the preferred process in the glass kiln refining process. The semi-dry desulfurization uses a desulfurization tower as the main desulfurization equipment and is composed of a tower body, a spray cigarette holder, a gas pipe and the like. The higher concentration of sulfur-containing flue gas enters the top of the column and enters the baffle at the inlet of the column, flowing under the action of the baffle. The water vapor is introduced through the nozzle, and the slaked lime can be sprayed into the cylinder for contact. After the reaction between SOx and Ca(OH)2, the slaked lime sprayed and the reaction interface continuously collides with each other to strengthen the thermal conductivity between the gas and the solid and accelerate the desulfurization. The reaction proceeds. The gas after desulfurization is discharged to the outside through the dust collector, and most of the dust captured by the dust collector is returned to the cylinder as a circulating powder to continue to participate in the desulfurization reaction, and a small amount of dust is regularly discharged to the outside through the pipeline.
3.4 Engineering Applications
At present, high-temperature electrostatic precipitator, SCR denitrification, and semi-dry desulfurization technology are the three technologies that are most used in glass furnace kiln dust removal. Through the combined application of three methods, it can effectively solve the air pollution problem in the production process of the glass furnace.
In response to the call of the national environmental protection policy, an exhaust gas treatment team conducted a detailed investigation on the production process and exhaust emissions of the glass production line, and finally determined to add high-temperature electric dust removal based on the original semi-dry desulfurization process. The technology is modified with the high-temperature denitration process. The equipment after the technical transformation works well, the system is stable, the failure rate is low, the operation and maintenance cost is low, the economic benefit is good, and the concentration of the emissions is far lower than the relevant national regulations.
All in all, the comprehensive and effective treatment of the flue gas generated in the glass furnace is an important way to solve air pollution. With the implementation of the new regulations, enterprises have strengthened their self-regulation and reduced the pollution caused by smoke and dust through various means. Through high-temperature electrostatic precipitator, SCR denitrification and semi-dry desulfurization processes, the dust, NOx and SOx pollutants generated in the glass manufacturing process can be treated, which meets the requirements of national energy conservation and emission reduction and promotes economic development.
Contact: Ms. Jane
Phone: +86 136 0202 1569
Tel: +86-22-2944 4813
Add: Room 608 KG Building No.256 East Road Dongli District, Tianjin, China