Several key points to improve the recovery and utilization of sintering waste heat
Shanghai Qihuang analysis sintering waste heat recovery power generation technology is an important way to reduce energy consumption in the sintering process, improve energy utilization, and increase enterprise efficiency.
The key factors affecting the recovery of sintering waste heat:
Sintered waste heat power generation is roughly divided into three systems: steam turbine power generation system, boiler system, flue gas recovery circulation system, and steam turbine power generation system. The principle is that the sintered ore is blown through the sintered ore layer from the bottom of the ring cooler to generate high-temperature gas, and the high-temperature gas is introduced into the waste heat boiler. The water in the boiler is heated to generate steam, and the steam drives the steam turbine to rotate the generator to generate electricity.
1. The sintering machine shuts down more in a short time
Sintering is a continuous sintering process that relies on a continuous heat supply to maintain waste heat to generate electricity. Once the sintering system is shut down, after a period of cooling when it is restarted, most of the heat contained in the sinter layer is discharged from the sintering flue, and the amount of waste heat recovery is greatly reduced, which directly affects the normal production operation of the waste heat boiler. Low will cause the turbine to shut down. Due to the problems of the grate bars and insulation mat materials used, the burning loss is large, and it is easy to cause the trolley to drop the grate bar. After the occurrence, the trolley must be stopped for about 5-10 minutes, which will affect the production of waste heat for up to 1h. Even longer, seriously restricting the normal operation of waste heat boilers.
2. Poor sealing of waste heat recovery system
The lower part of the two sintered ring cold trolleys is sealed with a heat-resistant rubber strip. Long running time, 180m2 sintering machine, the sealing rubber strip of each part is seriously worn and aging. Because the gas collecting hood is at the feed end of the cooling machine, a large amount of hot sinter ore often causes the seal at the gas collecting hood to burn out. Multiple air leakage points are formed in the entire flue gas circulation system, causing a large amount of hot air to overflow below the ring cooler, and a large amount of cold air is sucked above the trolley to cause the temperature of the flue gas to decrease and the boiler gas output to decrease.
3. Impact of sintering waste heat recovery process:
In normal production in the past, the sintering end point is generally controlled at the penultimate third bellows. However, due to the limitation of raw material conditions, all the main iron-containing materials are now sintered with hematite and limonite powder. Although the material layer is thickened, the sintering end point still appears ahead of time, and the thickness of the red material layer at the tail of the machine is significantly reduced or even appeared Overburning phenomenon, part of the sintered ore is cooled on the machine, and the effect of waste heat recovery is seriously affected.
4. Improvement measures to increase waste heat recovery:
According to the actual production situation and existing problems, the following measures were proposed and adopted. The amount of waste heat power generation depends mainly on the amount of gas produced by the waste heat boiler, and to increase the amount of gas produced, we must start from increasing the concentration and flow of waste heat flue gas.
Optimize production process and stabilize working conditions
1) Reasonably match the speed of the sintering machine and the speed of the ring cooler, and ensure that the discharge at the discharge port of the cooler is normal, and appropriately reduce the speed of the ring cooler. Moderately increase the thickness of the material layer of the cooling machine to enrich the heat and increase the amount of waste heat recovery.
2) The addition of sinter ore dropping point and temperature measurement point can reflect the flue gas temperature of the sinter ore drop at any time, and strict control is required to be above 350 ℃.
3) Rectification of the sintering machine's cloth and press equipment.
4) Take measures to close the opening of the bellows gate valve and the exhaust fan damper, strictly control the sintering end point at the penultimate bellows, and ensure that the temperature of the blanking point is controlled within the range.
Renovation of the sealing of the flue gas recovery system
1) Control the air leakage of the cooler body. Check the dynamic sealing and static sealing rubber strips under the cooling machine trolley, and the sealing rubber between the trolley and the trolley once every shift, and use other processes to shut down or repair to replace it to ensure the sealing effect.
2) Weld M10mm thick arc-shaped manganese plate on the outer edge of the ring-cooling trolley, install M0.5mm thick stainless steel sheet under the fume hood, make the manganese plate and stainless steel sheet form a soft connection, play the purpose and role of sealing . Prevent cold wind from entering the smoke collection hood, effectively increasing the temperature of the recovered flue gas.
Reduce the number of sintering machine main machine shutdowns, and optimize the response measures for short-term main machine shutdown
1) Arrange special personnel to arrange the furnace bed for each shift, make up for the lack of the furnace bar in time, and then replace the trolley regularly, after the number of trolleys arranged in the furnace bar reaches a certain number, use other factors to stop the furnace bar The loose trolley is replaced, which reduces the frequency of main engine shutdown.
2) Before shutting down for a short period of time, contact and communicate with the waste heat power station in advance, let them adjust in advance, and minimize the loss.
3) Do a good job in maintenance management of waste heat recovery equipment. Use the inspection time to thoroughly maintain the entire set of equipment to prevent minor failures.
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