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(I) Advanced technology using strip flame direct ignition Since the 1980s, many countries around the world have conducted a lot of research on sintering ignition technology, especially in Japan, in Kawasaki company slit burner burner and wire burning mouth (line burner) ignition furnace after the advent of completely abandon the "smoke" ignition technology use for many years, then we launched the Sumitomo Corporation's multi-slit burner (multi-slit burner) ignition furnace and the new date iron faceted The surface-combustion burner has made an outstanding contribution to the development of strip flame direct ignition technology.
The main technical feature of the energy-saving ignition furnace is that the strip flame is used to directly ignite the surface layer mixture, the furnace height is required to be low, the burner flame is short, the ignition heat is concentrated, and a band-shaped flame is formed on the surface of the mixture along the width direction of the trolley. The high temperature zone allows the surface mix to be ignited and sintered in a short period of time, resulting in high ignition efficiency.
Since the late 1980s, China has entered the period of large-scale development of energy-saving ignition furnaces by promoting the advanced technology of direct ignition of strip flames. Design developed from Changsha Institute of Metallurgy a double helical ribbon ignition furnace April 1989 steel was first used in the Soviet Union No. 1; Wuhan sintering plant in conjunction with transplantation digested introduction of Japanese technology based on software designed by the Metallurgical Institute of Changsha plurality The slot ignition furnace was put into operation on WISCO No. 3 No. 3 machine in December 1989; the curtain igniter developed by Maanshan Iron and Steel Design and Research Institute was put into production on the No. 2 machine of Meishan Sintering Plant in April 1990; it was developed by Beijing University of Science and Technology. The energy-saving ignition furnace was put into operation in the Anyang Sintering Plant No. 2 in December 1991. The development of the above energy-saving ignition furnace has greatly promoted the transformation of the sintering ignition furnace.
(B) using the hot flue gas in an amount slightly negative pressure control energy-saving ignition furnace, coal combustion gas is small, only a normal sintering ventilation air volume 1/50 ~ 1/100 in order to ensure flame strip material surface There is sufficient contact time for heat exchange, so that the strip flame has a certain spreadability, preventing cold air from being sucked from the furnace mouth and the two sides of the ignition furnace. The negative pressure of the bellows at the lower part of the ignition furnace must be controlled to ensure the furnace of the ignition furnace. The pressure is in the range of -10 to OPa.
Baosteel No. 1 ignition furnace furnace pressure control and gas saving practice show that at the same ignition temperature, when the furnace pressure is -4.9Pa, the coke oven gas consumption is 2900m 2 /h, when the furnace pressure is ±OPa, the coke The gas consumption of the furnace is reduced to 2400m 3 /h. In order to prevent the fire from the furnace mouth, the pressure control range of the ignition furnace of Baosteel No. 1 is -4.9~OPa.
(3) Maintain moderate ignition heating intensity
Experimental studies have shown that under the ignition system of the lowest ignition energy consumption, the surface layer of the sintered cake has a loose layer of 50-80 mm, wherein the surface has a depth of 30-40 mm, and there is no liquid phase formation at all, and they circulate in the sintering system. It only acts as a carrier of carbon. With this system of ignition, the yield and drum index of the sintered ore are low, and the process energy consumption is high. Therefore, in the design and production, moderate ignition heating strength should be adopted to make it compensate for the lack of heat in the upper layer of the mixture. This can reduce the carbon content of the mixture, which is beneficial to low-temperature sintering and helps to reduce the FeO content in the sintered ore. That is to improve the comprehensive benefits of the sintering process.
The thermal test of Baosteel's No. 2 line-type ignition furnace shows that the above conclusion is correct. Due to insufficient heating intensity of the ignition furnace, the No. 2 machine has poor quality of surface sinter. Under the same thickness of the material layer, the output is reduced by 48t/h compared with No.1 machine, and the amount of returned ore is increased by 84.3kg/t. Reduced by 4.25%, coke consumption increased by 6.43kg/t, process energy consumption (standard coal) increased by 2.1kg/t, while coke oven gas consumption decreased by 1.2m 3 /t compared with No.1. Many sintering in China The factory uses fine concentrate as the main raw material, the material layer is thin, and the one-sided pursuit of ignition energy is low. It is uneconomical to adopt the ignition technology with minimum ignition energy consumption, and should maintain moderate ignition heating intensity.
(4) Using hot air to support combustion and setting hot air holding furnace
The use of hot air combustion and hot air holding furnace in the ignition furnace is an effective means to utilize the exhaust gas of the cooling machine, which can reduce the ignition fuel consumption, increase the oxygen content of the flue gas, improve the quality of the surface sintered ore, reduce the consumption of solid fuel, and reduce the FeO content of the sintered ore. Conducive to the formation of acicular calcium ferrite, therefore, is an important measure to achieve low temperature sintering.
According to reports from the former Soviet Union, the ignition holding furnace uses 300 ° C cooler exhaust gas to increase the oxygen content of the flue gas by 2%, reduce the ignition gas by 17%, reduce the solid fuel by 0.1 to 0.7 kg / t, and increase the output by 0.6% to 0.8%. 3 sets of 28~32m 2 sintering machine ignition furnace in a factory, set hot air insulation section, use hot air of 200~400°C in blast belt, reduce the average consumption of solid fuel by 4kg/t, reduce the average amount of returning ore by 6%, and sinter FeO The content decreased by 2.8% on average.
Using waterless cold structure and advanced refractory materials to improve the life of the ignition furnace Extending the service life of the ignition furnace has always been the user's need and the goal that the design and the manufacturer are striving for. The ignition furnace with water-cooled ring beam used many years ago requires a lot of cooling water. The hook bricks of the protection ring beam are easy to break and fall off. The welding of the ring beam is often cracked. It will be shut down for maintenance in 3-6 months. The life of the ignition furnace is only 1 to 2 years. In recent years, the energy-saving ignition furnaces promoted and used basically eliminated the water-cooled ring beam structure, and the refractory lining was changed from refractory brick and thermal insulation brick masonry structure to integral pouring composite lining structure with anchoring hanging bricks. This structure greatly improves the overall strength of the lining, has good thermal insulation performance, and lays a foundation for prolonging the life of the lining to reduce heat loss. With the continuous introduction of new refractory castables, the material of composite lining refractory castables is also constantly updated. The clay-based castables widely used in the past have been replaced by low-cement castables. At present, ultra-low cement castables (ie, micro-powder combined casting) Material) is in the promotion stage. Castable aggregate by the high aluminum flint to alumina, mullite sometimes employed. The service life of the integral cast composite furnace lining furnace is generally about 4 years, and some have reached 5 years, basically being synchronized with the sintering machine overhaul cycle.
At present, the technology of using large-scale precast block masonry furnace has become more and more mature. With the promotion and application of this technology, the ignition furnace has become a factory-installed equipment installed on site, without the need for supporting, pouring, demoulding and long time. Oven and other complicated procedures, therefore, the construction is convenient, the cycle is short, the service life of the large prefabricated block ignition furnace can also reach 4 years. If it is damaged, it can be partially replaced, which is worthy of popularization and application.
Basic principles of ignition furnace renovation
A good performance ignition furnace should meet the requirements of the ignition process. It has low ignition energy consumption, low investment, safe operation, convenient operation and maintenance, and long service life. Low energy consumption and long service life are the core objectives of the ignition furnace transformation. To this end, the following basic principles should be followed during the renovation of the ignition furnace.