According to the requirements of the National Environmental Protection “Eleventh Five-Year Planâ€, the sewage treatment of industrial furnaces and kiln is the focus of air pollution control. "Industrial furnace kiln high efficiency bag type dust removal device technology and complete equipment research" was included in the "Eleventh Five-Year" national major science and technology support plan, and has been launched. Overview There are about 26,000 existing foundries in China. Except for a few units that have reached the international level, most of the factories are small in scale and low in specialization. There are problems of waste of resources and excessive energy consumption. It is a pollution. An industry with serious emissions. According to estimates, taking gaseous pollutants as an example, the annual emission of exhaust gas is about 20 billion m3 and the dust is about 1.2 million tons. The industrial furnaces in the foundry industry have complex smoke components and contain a large amount of CO2, CO, sulfides, nitrogen oxides and soot. The temperature of the flue gas, the composition of the flue gas and the concentration of oxides emitted from different stages of the production of industrial furnaces and kiln are also extremely unstable. It is very difficult to stabilize the supporting purification equipment. Cob Led Strip Lights,Cob Cct Led Strip,Led Cob Strip Ip67 Waterproof,Cob Led Flexible Strip Light Shenzhen You&My Electronic Technology Co., Ltd , https://www.ymledtrade.com
At present, most industrial furnaces and kiln exhaust gas in China's foundry industry cannot stably meet the prescribed emission standards, and the pollution is very serious. It is extremely incompatible with the goal of rapidly connecting with the international community and building a harmonious society.
At present, the contradiction between China's economic and social development and resource and environmental constraints is increasingly prominent. Environmental protection faces severe challenges. It must be based on deepening the implementation of the scientific development concept, transforming the mode of economic development, and effectively solving the problems that endanger the health of the people and affect the sustainable development of the economy and society. Highlight environmental issues and work hard to build an environment-friendly society. Focusing on the goal of controlling the total discharge of major pollutants determined by the National Eleventh Five-Year Plan for environmental protection, pollution prevention is a top priority. Therefore, in addition to strengthening structural adjustment, the industry must rely on science and technology, innovative mechanisms, vigorously develop environmental science and technology, and promote environmental protection through technological innovation.
According to the requirements of the National Environmental Protection “Eleventh Five-Year Planâ€, the sewage treatment of industrial furnaces and kiln is the focus of air pollution control. "Industrial furnace kiln high efficiency bag type dust removal device technology and complete equipment research" was included in the "Eleventh Five-Year" national major science and technology support plan, and has been launched.
The project has a close relationship with the increasingly strict environmental protection standards and requirements. Combining resource recycling and researching and developing high-efficiency soot purification systems for industrial furnaces is an important part of improving the level of major technical equipment in China's environmental protection industry and revitalizing the equipment manufacturing industry. The adoption of high-tech and advanced applicable technologies is also a strategic measure for the sustainable development of the national economy. As a national major science and technology support plan project, it will surely become a practical technical support for building an environment-friendly society.
Research and development of cupola smoke elimination and waste heat utilization system The atmospheric pollutants in the foundry industry are most serious in cupola smoke. The cupola is the main smelting equipment for the production of cast iron. It produces a large amount of high-temperature flue gas, dust and other emissions during the smelting process, accounting for about 80% of the total air pollution of the entire cast iron plant. The flue gas temperature is high and the soot composition is complex. The concentration is high, and the dust emission and smoke exhaustion are extremely fluctuating in different melting periods. It is one of the most difficult and most difficult types of flue gas in the mechanical furnace.
At present, the method used to purify high-temperature soot in this system is still very old, and the process is not up to standard. The advanced process and equipment developed by our company are: the high-temperature soot in the smelting process of the cupola is discharged from the furnace mouth through the flue into the spoiler cyclone cooler, and the temperature of the soot is reduced from about 600 °C to about 150 °C by water cooling. Then, enter the multi-tube water cooler, the smoke is cooled again to lower the temperature to about 100 °C, and finally enter the normal-temperature bag type dust collector, and the flue gas is purified and discharged to the standard.
The turbulent cyclone cooler and multi-tube water cooler, as well as the water supply pump and the reuse pool, constitute a cooling system for the cupola. The exhaust temperature of the cupola is very high. The temperature of the suction port is as high as 600 °C, and the furnace stage is as high as 900 °C. The soot under such high temperature conditions directly enters the dust collector, especially the bag type dust collector and fan. The operation will be greatly affected. The method adopted by the general enterprise is a long flue pipe type air cooling or a multi-pipe water jacket cooler. The hot water generated by the heat exchange in the water jacket is cooled by the cooling tower and then returned to the cooler by the water pump, and the heat of the high temperature flue gas is used. Failure to recycle (high-temperature flue gas recovery and utilization method: exchange hot water heat through the spoiler cyclone cooler, heat the cooling water to about 80 °C, and then exchange water-water for domestic water). It not only wastes a lot of thermal energy resources, but also produces heat pollution emissions. High temperature pipelines and water jacket coolers without insulation measures pose certain hidden dangers to production and system safety. Therefore, the cooling and cooling of the cupola dust and the waste heat recovery and utilization are technical measures necessary for energy saving and emission reduction.
There are many ways and methods for cooling the cupola soot. The soot cooling system adopted in the above cupola is a cooling device for heat exchange of water and high temperature flue gas which is designed and designed on the basis of many years of practice. It consists of a two-stage cooler: the first stage is a spoiler cyclone cooler; the second stage is a multi-tube water cooler.
The first-stage spoiler cyclone cooler consists of two parts, the upper part is a multi-tube water-smoke heat exchange part, the flue gas flows upwards in the tube, and the water flows outside the pipe. The lower part is a tangential air inlet, and the soot flow tangentially rotates into, which creates an effective collision with the built-in spoiler during the rotation process. It better settles large particle dust and dust particles with Mars (a technical measure necessary for the bag type dust removal device), which not only acts as a cyclone, but also strengthens due to the upward movement of the airflow rotation disturbance. The heat transfer effect of the airflow on the wall of the steel pipe. In addition, the wear of the large particle dust particles on the inner wall of the cooling pipe and the inner wall of the spoiler cyclone cooler is greatly reduced, and the service life is prolonged. Therefore, the spoiler has an important effect of improving the thermal efficiency and dust removal efficiency of the first stage cooler and reducing wall wear.
The function of the second-stage multi-tube water cooler is to reduce the temperature of the flue gas twice, to ensure that the temperature of the flue gas entering the bag filter is within the maximum allowable range of the filter bag (≤120 °C), and the filter bag is not damaged. So that the dust removal system can operate safely. Due to seasonal changes, the ambient temperature difference is large. According to the actual situation, the automatic thermometer shows that when the first-stage spoiler water cooler outlet flue gas temperature is <150 °C, the inlet valve of the second-stage cooler can be adjusted. In order to control its influent flow, reduce the amount of cooling water supply, and improve the thermal effect of the cooler.
Production Actual Application Effect Shanghai Industrial Boiler Research Institute and Environmental Product Quality Supervision and Inspection Center conducted thermal and environmental protection tests on a 10t/h cupola of a machine tool foundry in Shanghai. The relevant test data are summarized in the attached table.
According to the characteristics of long operating cycle and large fluctuation of the cupola, the test process is used to track and monitor the operation of the cupola, each cycle is about 9.5h. From the test data, the following results can be obtained:
(1) The effective heat utilization rate of the spoiler cooler is 38.58%~51.35%, and the average calorific value can be 8157.32MJ/h. If the available heat is calculated according to the minimum available calorific value of 6888.26 MJ/h, It saves 235kg of standard coal per hour and effectively reduces the temperature of the flue gas, so that the flue gas temperature is reduced from 272.32 to 306.5 °C to 117 to 142 °C, and the outlet water temperature is 68.37 to 90.5 °C.
(2) If it is estimated according to the actual production situation of a foundry of a machine tool in Shanghai, it will be opened 8 hours a day, 5 days a week, and 50 weeks a year for a total of 250 days. Under this circumstance, 1.88 tons of coal can be saved per day, and the annual coal consumption is 470 tons, which is equivalent to RMB 470,000 per ton of coal price of 1,000 yuan. In terms of emission reduction, the minimum emission reduction is 517kg, SO2 1598kg, NOx 3134.9 kg, CO2 1034t. If 1/10 of the country's 26,000 foundry sites use waste heat utilization technology, it can save 1.034 million tons of standard coal, and reduce dust emission by 1137.4t, SO2 3515.6kg, NOx 6896.78 kg and CO2 227.48 million tons.
(3) Tested by Shanghai Songjiang Environmental Protection Bureau: 1 The exit of the cupola spark trap is zero. 2 After cooling, the temperature of the flue gas into the bag filter is <100 °C, and the normal temperature filter material is used. 3 The concentration of soot emission in the test report is 17.9mg/m3, which is much better than the “Emission Standard for Air Pollutants in Industrial Furnace and Kiln†as stipulated by GB9078-1996. 4 Through the implementation of the project, it has reached the national energy conservation and emission reduction and waste heat utilization regulations, and is at the international advanced level.
IV. Conclusion (1) The completion of the project will accelerate the improvement of environmental protection standards for industrial furnaces and kiln, and provide guarantees for promoting the overall discharge level of the machinery industry as soon as possible to reach the international advanced level. In addition, the development of the project will also help to raise China's environmental protection control level to the international advanced level. It not only promotes the industry to effectively save energy and reduce emissions during high-speed development, promotes environmental protection and harmonious development of the industry; at the same time, it provides strong technical support for setting up a green threshold for China's foundry industry, promotes the reorganization of the foundry industry, and achieves intensification, specialization and energy conservation in the industry. Greatly reduce the pollution in the production process, and truly realize the production of the foundry industry to become a green manufacturing industry.
(2) Fully consider forward-looking in the process of determining technical indicators, and strive to create a reliable technology platform through project development to ensure a longer period of applicability in the process of improving pollution emission standards in the industry. This promotes technological advancement and sustainable development of industrial furnace kiln pollution control.
(3) This technology has broad applicability to pollution control of various industrial furnaces. Through innovative technology, a green casting demonstration base will be established. When fully promoted and applied, it is expected to reduce hundreds of thousands of tons of soot emissions per year and achieve the total amount of major pollutants discharged by the main indicators of economic and social development during the 11th Five-Year Plan period. Reduce the goal.
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