Comparison of dedusting methods
1. Dry electrostatic removal
The dry electrostatic dedusting of converter gas has the following disadvantages: explosion and secondary dust. Converter gas is still Electrostatic precipitator Meet the explosion conditions in: carbon monoxide concentration is within the explosion range; The gas temperature is about 200 ℃, lower than the ignition temperature of carbon monoxide in the air; Sparks are generated during electrostatic precipitator discharge. Converter gas has explosion danger in electrostatic precipitator, so three-stage explosion relief valves are installed at both ends of electrostatic precipitator to ensure the release of pressure in electrostatic precipitator. The dry electrostatic precipitation system puts forward higher requirements for the operation of workers. The converter dry electrostatic precipitator removes the dust on the dust accumulation plate by mechanical vibration. Due to vibration, it will cause secondary dust, and the dust concentration at the electrostatic precipitator outlet can only reach 20~30mg/m3.
2 Wet dedusting
Wet dedusting of converter gas mainly has the following disadvantages: high water and power consumption, and high fan failure rate. Whether Wet Tawen The dedusting system is still a wet Erwen dedusting system. The converter gas is cooled by spraying and washing. Compared with evaporative cooling, spray washing cooling consumes a large amount of turbid circulating water, and a separate water treatment system needs to be established to treat and recover the turbid circulating water. The wet tower dust removal system uses a circular slit adjustable throat venturi dust collector, and the water consumption is less than that of the wet two venturi dust removal system.
Venturi dust collector is a kind of high energy consumption Wet dedusting Device. Compared with the resistance of several hundred Pa of electrostatic precipitator, the resistance of Venturi tube precipitator is 2-5kPa, which is close to 10 times of the resistance of electrostatic precipitator. There are two venturi dust collectors in the wet Erwen dust removal system, and there is only one ring slit adjustable throat venturi dust collector in the wet Tawen dust removal system, so the system resistance is lower than that of the wet Erwen dust removal system. However, the resistance of wet dedusting system is much higher than that of dry electrostatic dedusting system, and the power consumption of system induced draft fan is also higher than that of dry dedusting system.
The wet dust is easy to adhere to the fan impeller, and the dynamic and static balance of the fan impeller is damaged. In order to avoid dust sticking on the fan impeller, it is necessary to regularly disassemble the fan housing and flush the fan impeller and the fan inner housing with high-pressure water.
3 Semi dry method
Converter gas Semi dry dedusting It is produced on the basis of converter gas dry and wet annular seam dedusting, which combines the characteristics of these two dedusting methods. The converter gas semi dry dedusting system has only one ring slit adjustable throat venturi deduster, and the system resistance is equivalent to that of the wet Tavern dedusting system, higher than that of the dry electrostatic dedusting system. However, since the semi dry dedusting system uses evaporative cooling to cool the converter gas, the system water consumption is lower than that of the wet Tavern dedusting system. The semi dry dedusting system, like the wet dedusting system, also has the problem of dust sticking on the fan impeller, so it is necessary to clean the dust on the impeller and blade shell regularly.
3 Comprehensive comparison
Evaporative cooling is used for dry and semi dry dedusting, and spray cooling is used for wet dedusting, so the water consumption for dedusting and cooling of wet dedusting system is higher than that of dry and semi dry dedusting system. In addition to the water consumption for dedusting and cooling of wet dedusting system, water spray cleaning is also required for dehydration elbow, cyclone dehydrator, fan blade, etc, Therefore, the total water consumption of wet dedusting system is much higher than that of dry dedusting system.
Compared with wet and semi dry dedusting, dry electrostatic dedusting does not require an independent turbid water treatment system, which saves floor space. However, there is still dust content (about 30mg/m3) in the flue gas at the inlet of the dry dedusting gas cooler. Therefore, a reservoir is set beside the gas cooler, and the gas cooling circulating water is sent to the water treatment station for treatment and recycling.
The outlet temperature of dry dedusting gas is 70 ℃, and the outlet temperature of wet dedusting gas is 60~65 ℃, both of which are saturated. Taking saturated gas with temperature of 70 ℃ and 65 ℃ respectively as an example, the amount of water taken away by 70 ℃ saturated gas is 93g/m3, 100t converter gas flow is 55047m3/h, and the amount of water taken away by the gas is calculated to be 5.1m3/h. Therefore, the amount of water supplement for dry dedusting is slightly higher than that for wet dedusting.
The resistance of dry dedusting system is about 8kPa, that of wet Tawen and semi dry dedusting system is about 20kPa, and that of wet Erwen dedusting system is about 24kPa. Therefore, the power consumption of fans in wet Tawen and semi dry dedusting systems is the same, the power consumption of fans in dry dedusting systems is the least, and the power consumption of fans in wet Erwen dedusting systems is the highest.
