Emergency help! Emergency help! There’s a problem with the vaporization furnace

Thread Content

This post was last edited by lzl8792 on 2015-12-1 21:21. Normal operating parameters: Gasifier liquid level: 50%; CH4 concentration: 600–800 ppm; Oxygen flow rate: 13,647 m3/h; Slurry flow rate: 26.55 m3/h; Quench water flow rate: 145–150 m3/h; Gasifier drainage volume: 70–75 m3/h; Hopper pump circulation volume: 25–30 m3/h. Problem description: Due to wear and leakage at the manual valve at the outlet of the hopper circulation pump, the hopper was switched to manual operation during the valve replacement. As a result of an operator’s mistake, the slag discharge valve was opened before the hopper was pressurized, causing high pressure inside the gasifier to impact the pressure in the hopper, resulting in severe vibrations. This also led to the rupture of the safety valve’s air line, causing the safety valve to stop functioning. After emergency repairs, the system was put back into normal operation. During subsequent operations, the hopper experienced overheating, with the temperature continuing to rise, which led to leaks in the slag crusher’s seals; the system had to be shut down for repairs. When the lock hopper overheated, internal leaks were checked in all the valves of the lock hopper; the charging valve showed an internal leak and was replaced, while the other valves had no leaks. After maintenance, when this furnace was restarted, all operational parameters remained unchanged; however, the lock hopper still experienced overheating. Subsequently, the circulation rate of the lock hopper was reduced in order to control the rise in its temperature. After that, severe water carryover occurred in this furnace; after the first instance of water carryover, the liquid level dropped to 35%. After stabilizing for one day, the liquid level was kept around 48%. There were subsequent fluctuations in the liquid level, but operations were still able to be controlled. After 7 days, the liquid level dropped steadily to around 33%, and then it remained at 28% until shutdown; it was not possible to increase it, forcing a shutdown. During the operation of the gasification furnace, the operating parameter that changes significantly is the furnace temperature. As the pressure difference at the slag outlet fluctuates, raising the furnace temperature is used to reduce this pressure difference, with the CH4 level being kept around 300 ppm. This method succeeded in reducing the pressure difference at the slag outlet during the first two attempts, but had no effect later on. Due to the presence of water, and in order to maintain the liquid level, the amount of water used for cooling was increased to around 155 m3/h. The amount of water that could be drained could not be increased, so it remained at 55 m3/h to 60 m3/h. A large amount of water ended up in the carbon washing tower. During this maintenance work, it was found that the gap between the rising pipe inside the furnace and the baffle plates was extremely small and filled with dust; as a result, the outlet for the syngas from the gasification furnace was almost completely blocked. The large filter screen is also heavily scaled, with very hard scale deposits, indicating severe ash accumulation. Although this furnace was not operated strictly in accordance with the process specifications, it was run this way for about 3 years without any of the aforementioned problems occurring; therefore, it is suspected that the issue arose as a result of pressure shocks between the gasification furnace and the lock hopper. What impact do the pressure shocks from the gasifier and the lockhopper in the early stages have on the internal components of the gasifier? What is the impact on the slag breaker and the lockhopper? Is this the reason why the liquid level in the gasifier cannot be raised? Where is the problem? How to solve it? Please ask experienced experts and teachers to analyze the problem. . . Waiting eagerly.