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I’m just here to join in the fun; I’m not a designer. In the past, I worked on operation teams that handled coal gasification furnaces using pressurized gas. At that time, I was the chief operator in the control room, overseeing two furnaces. One winter, during a day shift, the vaporization furnace was operating perfectly. I was bent over filling out a report when, suddenly, the furnace stopped operating due to an interlock mechanism. On the industrial television, I could see that the safety valve of the furnace had also activated. I was completely confused at that moment; it wasn’t so much the fear of being penalized for parking there, but rather the suddenness of the incident, and I couldn’t even figure out why I had parked there in the first place. After the issue was resolved, the previous curves were retrieved; they showed that the steam and oxygen flow rates dropped to 0 almost simultaneously. Subsequently, the pressure in the water jacket as well as the pressure difference increased sharply, exceeding the set values for interlock protection. Eventually, the furnace experienced overpressure, which caused the on-site safety valve to activate. Since I had been at the computer all the time working on reports, it’s impossible for any mistakes to have occurred. Under those circumstances, it’s unlikely that anyone would deliberately press the emergency stop button. Later, I remembered other accident reports I had seen from other facilities, and after thinking carefully about the circumstances at the scene, I finally figured it out: it was because the pressure tapping pipe on the steam pipeline had frozen! Those familiar with pressurized gasification of coal know that the steam and oxygen supplied to the gasification furnace are generated automatically through proportional control. During normal, stable operation, we set the load control to automatic mode in order to maintain the steam-to-oxygen ratio within a specific range. When the pressure tap on the steam flow meter freezes, the measured value of steam flow OP drops to 0 instantly. Once this value is fed back to the automatic control system, the steam valve opens fully immediately, allowing a large amount of steam to enter the furnace. This results in a sudden increase in the pressure difference between the gasifier and the jacket; since an interlock mechanism is in place, once this pressure difference exceeds the set threshold, the oxygen valve closes automatically and the flow rate drops to 0. The large amount of steam entering the furnace causes the furnace pressure to rise, eventually triggering the safety valve to activate. I have to say that winters at my former workplace were really extremely cold. . .