JPS6246764B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a device for firing powder and granular materials such as a cement firing kiln and a quicklime firing kiln. The present invention relates to a method of using fuel in a powder and granular material sintering apparatus, characterized in that the fuel is mixed with dust, collected, mixed with a raw material to be sintered, and completely combusted in a granular material sintering furnace. Generally, various methods have been devised to reduce energy consumption in apparatuses for firing granular materials, such as cement firing kilns and quicklime firing kilns. One method is to mix flammable substances into the raw materials to be fired and use the combustion heat of the combustible substances in the firing process to reduce fuel consumption and stabilize the firing reaction. is being carried out. However, if the combustible substances mixed into the raw material contain volatile matter, most of the volatile matter will volatilize during the preheating and temperature raising process of the raw material, and will not be effectively utilized and will be left outside the system. It will be wasted. Therefore, an object of the present invention is to eliminate such conventional waste of fuel and use it effectively by pre-combusting a solid fuel containing volatile matter to remove the volatile matter, and then sintering the powder and granular material. It is an object of the present invention to provide a method for using solid fuel in a powder and granular material sintering device, which is characterized in that the solid fuel is introduced into the device, mixed with raw materials to be sintered, and completely combusted. Other objects, features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. First, FIG. 1 of the drawings schematically shows an example of the process of a conventional cement kiln. In such a conventional cement firing kiln,
The raw material supplied from the feeder 1 is mixed with the combustible material supplied from the feeder 2, passed through the weighing machine 6, and the collected dust passed through another weighing machine 5 is mixed with the raw material preheating machine 8. is sent to the top of the Next, such raw materials undergo preheating and decarboxylation processes, are fired in the rotary kiln 7, become clinker, and are discharged from the end of the rotary kiln 7. Combustible substances mixed into the raw materials are stored in the raw material preheater 8.
Inside the kiln, the temperature is increased by exchanging heat with the hot gas discharged from the kiln in a countercurrent manner, and it is finally combusted to heat the raw materials and contribute to the firing reaction, but volatile substances contained in combustible substances are 350℃ when sent to preheater 8
It comes into contact with hot gas of ~400°C, and then evaporates as it gradually heats up as it flows down the raw material preheater 8, passes through the ventilator 9 and the raw material dryer 10 together with the exhaust gas, and is transferred to the electrostatic precipitator 11. introduced in stack 1
3, and the amount of heat is not used effectively. The mixed dust collected by the electrostatic precipitator 11 is stored in a dust silo 4 by a transporter 3, and then sent to a raw material preheater 8 via a weigher 5. An example of implementing the method of the present invention for solving the above-mentioned problems in the conventional method is shown in FIG. 2 for a cement firing kiln. First, the powdered solid fuel containing volatile matter is transferred to burner 1.
4, the solid fuel is blown into the boiler 15 and combusted, and all volatile components contained in the solid fuel are burned out at this stage. The amount of heat generated by this pre-combustion of the solid fuel is effectively used, for example, to operate the turbine generator 16. Next, a part of the combustible solid content and ash of the recycled fuel are discharged from the boiler 15 as unburned content and introduced into the electrostatic precipitator 11. Boiler 15
Since the unburnt solid fuel discharged from the main component is carbon, its specific electrical resistance is less than 10 ⁴ Ω-cm, which causes a re-entrainment phenomenon in the electrostatic precipitator 11, and only this is collected by simple dust collection. If so, the dust collection effect will be reduced. However, since combustion gas containing scattered dust discharged by the ventilator 9 from the cement kiln, that is, the rotary kiln 7 and the raw material preheater 8, is introduced into the electrostatic precipitator 11 via the raw material dryer 10. The unburned solid fuel introduced from the boiler 15 and the scattered dust introduced from the rotary kiln 7 are collected in a mixed state. In this way, by collecting the high-resistance cement firing kiln scattered dust and low-resistance boiler dust together, the specific resistance of the mixed dust falls within the range of 10 ⁵ to ^{10 10} Ω-cm, which is suitable for electrostatic collection. So,
It is no longer necessary to strictly control the temperature of the exhaust gas introduced from the rotary kiln 7 for cement firing into the electrostatic precipitator 11, and the dust collection rate is improved, so it is possible to increase the amount of gas processed by the precipitator 11. It is. The mixed dust collected by the electrostatic precipitator 11 is then temporarily stored in the dust silo 4 by the transporter 3, and then mixed with the raw material at a fixed ratio via the weigher 5 and sent to the raw material preheater 8. be done. Since the unburned solid fuel contained in this mixed dust does not contain volatile matter, it is completely combusted in the raw material preheater 8 and the rotary kiln 7 where combustion is performed by the burner 12, and is effectively utilized for the calcination reaction. As mentioned above, the volatile content of the solid fuel is completely combusted in the boiler 15, and the unburned solids are effectively used in the rotary kiln 7 for firing cement, so there is no waste of fuel, and the amount of unburned content in the boiler is controlled by the plant. This is not a problem as a whole; rather, it can be made into a fuel for cement firing by making the solid fuel slightly coarser, recovering a large amount of unburned matter, and supplying it to the rotary kiln 7 for cement firing together with the raw material powder. By reducing the amount used and ensuring stable operation of the firing process, the system as a whole becomes advantageous. Table 1 below shows an example of the properties of oil coke used as solid fuel blown into a boiler.

[Table] Table 2 below also shows an example of the unburned rate, which is the powderiness of oil coke and the ratio of the total calories of exhaust dust to the total calories of fuel blown into the boiler.

[Table] As explained above, the present invention provides a combustion device such as a boiler that pre-combusts solid fuel containing volatile matter in a sintering device for granular materials such as cement, and removes the volatile matter by pre-combustion. This is extremely effective in effectively utilizing fuel and improving the dust collection rate. Of course, such a volatile matter combustion device may be a heat utilization device other than a boiler, and the cement firing furnace may have an auxiliary combustion furnace in the raw material preheating mechanism, or it may be another cement firing method that does not have a preheating mechanism. Alternatively, a quicklime kiln or other powder kiln may be used.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the steps of a conventional cement firing kiln, and FIG. 2 is a schematic diagram showing the steps of a cement firing kiln implementing the method of the present invention. In the figure, 1, 2: feeder, 3: transporter, 4: dust silo, 5, 6: weighing machine, 7: rotary kiln, 8: raw material preheater, 9: ventilator, 10: raw material dryer, 11: electric collector Dust machine, 12, 14: burner, 15: boiler, 16: turbine generator.

Claims (1)

[Claims] 1. A solid fuel containing volatile matter is pre-combusted to remove volatile matter, and then introduced into a powder and granular material sintering device, mixed with raw materials to be fired, and completely combusted in the granular material sintering device. Method of using solid fuel in powder and granular material sintering equipment.