High temperature gas damage to filter bags
The filter bag is that the most crucial factor determining the performance of the dust collector bag house. The main factors causing the damage to filter bags are heat burnout, corrosion, mechanical damage, installation quality, product quality, operation and management.
The damage to filter bags caused by high temperature burning is fatal. For example, in a coal kiln, thanks to the very small and special sticky pulverized coal particles after drying, dust cleaning isn’t ideal, in order that an outsized amount of dried pulverized coal is kept on the surface of the filter bag, and therefore the pulverized coal after drying is with very low burning point. When the heat smoke enters the dust collector, it’ll quickly ignite the coal powder on the surface of the filter bag, resulting in the entire dust collector filter bags and the cages were all burnt down.
High temperature shrinkage: the opposite damage of heat flue gas to dust filter bag is heat shrinkage. Although the temperature of each filter bag is different, when the flue gas temperature exceeds its using temperature, the size of the filter bag will shorten in the length direction, and the filter bag bottom is tightly supported by the filter cage and damaged by the force. If the heat shrinkage of the filter bag is too large, the radial size of the filter bag will be smaller. The filter bags are going to be tightly clamped on the support cage, and even the cages can’t be drawn out.
Sparks burning: In addition to high temperature burnout, the damage of sparks to filter bags in flue gas is also very serious. Such as coke oven, dry kiln, chain furnace, cupola, furnace, furnace, mixed iron furnace then on within the production process, there’ll be tons of sparks mixed into the flue gas. For example, when the treatment of sparks isn’t timely, especially when the dust layer on the surface of the filter bag is thinner, the sparks will burn the filter bag and form an irregular circular hole. However, when the dust layer on the filter bag is thick, sparks won’t burn the filter bag directly, which can cause deep color baking marks on the surface of the filter bag.
Therefore, the filter bag is always in a state of stress, causing the shrinkage deformation, hardening and crispness of the filter bag, accelerating the strength consumption and shortening the life of the filter bag. As the filter bag is tightly bonded to the supporting cage after deforming, it’s difficult to deform the filter bag when do dust cleaning, which results in high resistance to filter bags.
How To Prevent High temperature gas damage to filter bags
The dust filter bag is an important dust removal object of the filter bag filter. Its price accounts for about 10% to 15% of the original cost of the entire dust bag filter. Therefore, if it is replaced frequently, it will not only affect the working hours, but also improve the cost. When removing dust from high-temperature flue gas, response measures should be taken to prevent the dangerous dust filter bag from high-temperature flue gas.
1. The spray is simply cooled.
- The spray nozzle is used to make the water spray out into the high-temperature flue gas. The evaporation of the fog will absorb a large amount of heat, so that the flue gas can be cooled. The advantage of this method is that the flue gas will be cooled rapidly, and the necessary construction and investment are few. The disadvantage is that the moisture content of the flue gas increases, which may cause the flue gas to condense and damage the dust filter bag.
- If the sprayed water mist is not fine enough, it becomes a larger (water point, hot? (The water point may not have time to evaporate and simply enter the bag filter, the dust bag is easy to be blocked. Therefore, you need to choose a nozzle with good performance. At the same time, a microcomputer is used to precisely control the spray volume.
2. Cooled by mixing with cold air.
- Usually install a three-way pipe on the inlet pipe of the high temperature dust bag filter, from which the outside air can enter the flue and mix with the flue gas, thereby reducing the flue gas temperature. The advantage of this method is that the cooling speed is fast, and only a few simple parts such as the tee pipe and the valve to control the air flow are needed.
- The disadvantage is that the amount of smoke will increase, and the greater the cooling rate, the more the volume of the flue gas will increase. Therefore, it is necessary to respond to the increase of the filter area and building volume of the filter bag filter, which increases the investment in the building, air duct micro-fan and other methods, and also increases the operating price.