1 Introduction With the continuous development of economy and industrialization in our country, the issue of air pollutant emissions has become increasingly prominent. Among the air pollutants emitted, the most serious impact on the environment and public health are SO2, NOx, dioxin and various heavy metals doped in industrial waste gases. Among them, SO2 and NOx are precursors of acid rain and NOx are precursors of photochemical smog. Therefore, serious toxic and carcinogenic effects of dioxin and heavy metals have been reported. And the emissions of these air pollutants are increasing year by year. According to the research results of China Academy of Environmental Sciences and Tsinghua University in 2011, the acid rain pollution caused by SO2 alone has caused economic losses of more than 110 billion yuan each year to our country. The total loss caused by air pollution accounts for about China's total GDP, 2% to 3%. China's SO2 and NOx emissions mainly come from coal-fired power plant boiler exhaust gas and sintering metallurgy industry flue gas. At present, flue gas desulfurization in thermal power plants has made great improvement. The country requires the power plant to start denitration of flue gas during the "12th Five-Year Plan" period, and about 80% of power plants will be equipped with denitrification devices around 2015 so as to achieve the "12th Five-Year Plan" period SO2 emission reduction of 8%, 10% reduction of NOx overall goal. Flue gas desulfurization of thermal power plants mainly uses wet limestone-gypsum method. The main choice of denitrification is the selective catalytic reduction (SCR) process. Under the background that two technologies are maturing and the flue gas discharge of thermal power plants meets the standard, the smoke of the metallurgical industry Gas treatment and emission reduction pressure is increasing, will also become the next focus of industrial flue gas treatment. 2. Sintering flue gas characteristics The emissions of SO2, NOx and other atmospheric pollutants in the metallurgy industry mainly come from the previous sintering process, in which the total amount of SO2 in the sintering flue gas accounts for about 90% of the total emissions of the steel industry. Although the power plant flue gas desulfurization, denitrification process more in-depth, practical experience has been well accumulated, and can provide some reference for the steel metallurgy industry and support, but the metallurgical industry sintering flue gas and power plant boiler flue gas generation process Is different, therefore, metallurgical industry flue gas treatment can not copy the power plant model. Sintering flue gas is a kind of gas containing many kinds of pollution components produced during the high temperature sintering process by igniting and melting all kinds of pulverized ferrous raw materials, fuel and flux placed on the sintering trolley. Compared with the power plant flue gas, Has many of its own characteristics: (1) large amount of flue gas, great changes Due to high air leakage rate (40% ~ 50%) and high solid material recycling rate, a considerable portion of air does not pass through the sintering bed, resulting in a substantial increase in the amount of sintered flue gas that produces about 4000-6000m3 of flue gas per tonne of sintered ore. Due to the differences in the permeability of the sintering material and the uneven material distribution, the resistance of the sintering flue gas system is greatly changed, which eventually leads to a large variation in the flue gas volume with a variation range of up to 40%. (2) sulfur dioxide concentration changes With the changing contradiction between supply and demand of raw materials and the pursuit of the lowest cost of steel enterprises, the origin and varieties of raw materials used by steel enterprises vary greatly, resulting in the fluctuation of their quality, composition (including sulfur content) Large, making the final concentration of sulfur dioxide produced by the sintering of a larger range of concentrations, from hundreds to 5000mg / Nm3 above. (3) fume composition is complicated Due to the use of iron ore as a raw material, the composition of the sintering flue gas is relatively complicated. In addition to sulfur dioxide and fine fumes, it also contains gaseous pollutants such as nitrogen oxides, hydrogen chloride, hydrogen fluoride and polycyclic aromatic hydrocarbons (PAH) Contains heavy metals and so on. Dioxins emitted from sintering production are second only to waste incinerators. (4) flue gas temperature range With the change of production technology, the temperature range of sintered flue gas generally ranges from 120 to 180 ℃. However, some mills consider the energy consumption and the operating cost as low as possible. After the low-temperature sintering technology is adopted, the temperature of sintered flue gas greatly decreases, Can be as low as about 80 ℃. Working principle:
The working principle of the plate bending machine is to make the work roll move through the action of hydraulic pressure, mechanical force and other external forces, so that the plate can be bent or rolled into shape. According to the rotational movement and position changes of work rolls of different shapes, elliptical parts, arc parts, cylindrical parts and other parts can be processed.
The upper roller of the symmetrical plate rolling machine is in the symmetrical position of the center of the two lower rollers, and the hydraulic oil in the hydraulic cylinder acts on the piston to make vertical lifting motion, and the last stage gear of the main reducer drives the gears of the two lower rollers to mesh for rotational motion, so as to roll the plate. provide torque. The flat plastic metal plate of the plate rolling machine passes between the three work rolls (two lower rolls and one upper roll) of the plate rolling machine. With the help of the lower pressure of the upper roll and the rotation of the lower roll, the metal plate passes through multiple passes. Continuous bending (inner layer compression deformation, middle layer unchanged, outer layer tensile deformation), resulting in permanent plastic deformation, rolled into the required cylinder, cone or part of them. The disadvantage of this hydraulic three-roll plate bending machine is that the end of the plate needs to be pre-bent with other equipment. This plate rolling machine is suitable for large plate rolling machines with a thickness of more than 50mm. A row of fixed idlers is added to the lower part of the two lower rollers to shorten the span of the two lower rollers, thereby improving the accuracy of the rolled workpiece and the overall performance of the machine.
Plate rolling machine types:
Plate rolling machine, plate bending machine, 3 roller rolling machine, 4 roller rolling machine, pipe making machine, pipe fabrication machine Wuxi Zhouxiang Complete Set of Welding Equipment Co., Ltd. , https://www.beamweldingmachine.com
Due to the different fields of use, the types of plate rolling machines are also different. According to the number of rolls, it is divided into three-roller and four-roller. The three-roller is divided into a symmetrical three-roller plate rolling machine, a horizontal down three-roll plate rolling machine, an arc down type plate rolling machine, an upper roll universal three-roll plate rolling machine, and a hydraulic CNC plate rolling machine. From the transmission, it is divided into mechanical type and hydraulic type. In terms of the development of the plate rolling machine, the upper roll universal type is the most backward, the horizontal downward type is slightly advanced, and the arc downward type is the most advanced.
