Thread Content
I. Causes of slag blockage: Slag blockage in the lock hopper generally occurs in two situations: 1. Blockage caused by slag lumps. This is generally caused by the high ash melting point of the coal burned in the gasifier, slag formation due to temperature fluctuations in the gasifier, or rapid cooling-induced slag formation in parts of the gasifier such as its water-cooled walls, burner flame shields, and thermal skirts. Additionally, it can be resulting from the detachment of suspended slag accumulated at the slag discharge outlet. In the case of Texaco gasifiers, it can also be caused by the peeling off of refractory bricks due to temperature fluctuations, resulting in \"brick slag\". If such slag accumulation is greater than the channel of the slag discharge hopper or causes bridging, it will impede the proper discharge of slag; in severe cases, slag cannot be discharged at all. 2. Sludge blockage. (Coal with a low ash fusion point) burns incompletely at too low temperatures in the gasification furnace; it begins to form ash particles before rapid cooling takes place. The high ash content results in fewer particles, while excessive moisture causes it to become muddy in texture, increasing its viscosity. This leads to accumulation at the bottom of the hopper, and once compacted, it forms bridges that block material discharge. II. Treatment methods 1. Preventive measures: Analyze the ash fusion point of coal in a timely manner, add an appropriate amount of flux, maintain stability in the material composition and an optimal oxygen-to-coal ratio, keep the temperature in the gasification furnace stable, and ensure good fluidity of the slag. In case of slag blockage, the operating conditions should be adjusted smoothly and promptly ； 2. Maintain the appropriate water level in the lock chamber and ensure proper water flow to prevent slag from settling and forming bridges ； 3. Slag blockage treatment: The most effective method is to install a pressurized water flushing pipeline at the bottom of the lock hopper. When slag clogging occurs, manual \"bridge removal\" is carried out by switching from programmed control to manual intervention; intermittent backwashing with high-pressure water is used to loosen the slag, followed by slag removal. Repeating this process several times will yield effective results. The pressure of the flushing water should be higher than the pressure inside the lock hopper, but not too high; too low a pressure will not achieve the desired loosening effect, while too high a pressure can cause a sudden increase in the water content inside the gasifier, or even the entry of liquid water, leading to equipment safety hazards. The theoretical data for differential pressure control needs to be calculated specific to each furnace; based on personal experience, a control range of 1.0–1.5 MPa yields good results. Generally, this method is more effective for the second reason than for the first. The first method is slightly more difficult to handle. Of course, if the check valve cannot be opened or if large pieces of slag fail to loosen and fall away, they will not be removed, and ultimately the operation has to be stopped for handling. The above are some of my personal experiences; they may not apply to all gasifiers and are provided for reference only.