Technical requirements of vertical mill for hot blast stove;
1. 1 Reliability:
The vertical mill requires very high temperature adjustability of the outlet air of the hot blast stove, which requires the hot blast stove to preheat the vertical mill and adjust the temperature continuously with the change of output until it runs stably and normally.
Efficient and energy-saving diffusion coal injection furnace (hot blast stove) is a high-temperature industrial furnace with adjustable proportion. The furnace temperature can be adjusted at will from 800℃ to 1500℃. The new technology production line is equipped with raw coal metering, which can completely calculate the coal consumption of hot blast stove. It is also required that raw coal metering and furnace temperature form an automatic control system for circulating flow and organize production according to the set production process temperature curve. That is, if the furnace temperature is too high, the raw coal will automatically drop and the production will be organized.
Vertical mill also has strict requirements for negative pressure of hot blast stove. The mechanical properties of vertical mills are different in different countries, and the negative pressure of hot blast stoves is also different. However, the negative pressure of vertical mill produced by foreign companies is almost above 300pa. This is a great test for gas, oil or coal-fired hot stoves. Especially for coal-fired hot blast stoves, the combustion effect of pulverized coal suspended in the air is bound to be poor because of the excessive negative pressure. The airflow speed of pulverized coal is too fast, which washes the furnace wall and a large amount of pulverized coal runs into the hot air pipe for combustion. There will be a lot of incomplete combustion and coking in the furnace, so that the hot air pipe is coking.
Therefore, according to the characteristics and technological requirements of the vertical mill, the diffusion coal injection furnace (hot blast stove) is designed as a two-unit production line and a special furnace structure, that is, the front part is a combustion chamber and the rear part is divided into a mixing chamber. In the mixing chamber, we designed a damper. If the negative pressure of the vertical mill is too large, we can open the baffle to make the airflow short-circuit, which will neither cause the negative pressure of the combustion furnace to be too large nor affect the pulverized coal combustion of the combustion furnace.
Practice has proved that whenever a new vertical mill is debugged, if the vertical mill generates huge suction and the hot blast stove generates large negative pressure due to improper central control operation, as long as these baffles are opened quickly, the negative pressure of the hot blast stove will be reduced rapidly to adapt to the production and adjustment of the vertical mill. Therefore, when the new vertical mill and hot blast stove are jointly debugged, this debugging is a gradual debugging. It can't be said that it can be completed through one or two adjustments. Only when the central control personnel are thoroughly familiar with the characteristics of the vertical mill and the hot blast stove can the balance point of each machine be accurately found, and the vertical mill can be put into normal operation through a period of running-in period.
1.2 reaction rate
The strain response speed of the hot blast stove is particularly fast, which is mainly reflected in the following aspects:
First, as shown in the figure, the temperature reaction time should be fast, especially when the vertical mill is combined with the hot blast stove. From the point of view of vertical mill preheating, some manufacturers report that the preheating time of vertical mill is different. Some manufacturers' vertical mills take up to 2 hours to warm up. The preheating time of vertical mill in some manufacturers is only half an hour. What is the best time? Except for the local climate, the water content of water slag is different from the vertical grinding characteristics of various manufacturers. A very important point is related to the use of hot stoves. At present, there are only two furnace types on the slag powder production line, one is pulverized coal furnace and the other is fluidized bed furnace. Practice has proved that the pulverized coal boiler is obviously superior to the boiling boiler because of its high automation engineering and unattended operation, and its temperature response speed is much faster.
The central control sends an instruction to heat or cool the hot blast stove, and the inlet temperature of the vertical mill changes in less than 5 seconds. Because the boiling furnace is backward, it takes a long time for the temperature at the entrance of the vertical mill to be reflected.
Secondly, in view of the characteristics of the vertical mill, negative pressure is required, and the hot blast stove is also required to have negative pressure strain capacity at any time with the requirements of the vertical mill, which is particularly important during the debugging period of the vertical mill and the hot blast stove.
The hot blast stove should be started quickly. It is an efficient and energy-saving diffusion coal injection burner. Except for the ignition heating period of the newly-built hot blast stove, it only takes more than ten minutes to raise the temperature during normal operation. For the craft production line designed by our company,
First, it consists of two units. According to the different materials ground by the vertical mill (www.sbmlimoji.net) and the different water content of the materials, any unit can be started quickly. For the boiling furnace, it is much more difficult and the start-up time is much longer.