Discussion on the principle of flare gas smoke suppression steam

I found that many people on the forum believe one of the functions of the smoke-reducing steam is the water-gas reaction, but in reality this role is minimal. As you said, a water-gas reaction takes place, producing CO and H2; without O2, how can combustion continue? How is black smoke produced? Substances with low volatile components generally do not produce black smoke. However, once large amounts of hydrocarbons with higher molecular weights are burned in a flare, especially unsaturated hydrocarbons, a large amount of black smoke is generated. Because they require an extremely large amount of oxygen (air) to burn, normal air supply is no longer sufficient. At this time, if the smoke-removing steam is turned on, a large amount of steam will be emitted. The torch head is equipped with 60 smoke-reducing steam nozzles in total; once activated, these nozzles create a negative pressure at the center of the torch head through high-speed airflow, drawing in large amounts of external air. This provides more oxygen, enabling the various components to burn fully and thus achieving the purpose of reducing smoke. If you insist that the water-gas reaction is the main mechanism for smoke reduction, it is recommended that next time black smoke appears, you try not to use smoke-reducing steam, but only lift steam (induction steam). Since a large amount of steam will still be released in either case, see if this can achieve the purpose of reducing smoke. So, the second point you mentioned, OP, is the main reason; if you think other factors can also have an impact, then next time try only by increasing the steam. PS: I’ve been at Torch Post for 7 months now, and I have quite some experience in eliminating black smoke.

Thanks for the advice! I also believe that complete combustion by introducing air is the main principle for smoke reduction; when listing the functions, I failed to arrange them in order due to insufficient consideration, so please understand. I would like some help explaining: does steam lift the flame, does the flame have rigidity, and does steam have a cooling effect? Note: We are ground-based torches that burn in five stages, with a total of 80 nozzles; each nozzle is associated with a smoke-suppressing steam stream.

The principle of smoke elimination for surface torches and high-pressure torches is the same. We can examine the structural layout of the steam nozzle, as well as the molecular sieves and dry gas seals present in that area; the principle of smoke elimination is indeed as explained by the person on the sofa. Additionally, there is a significant cooling effect, which helps to protect the torch tip.

It’s just that, for us, the ground torches haven’t made contact; are you guys from a purification plant or something, with relatively low levels of pollution? We are a large oil refinery, and it is extremely dangerous to emit flares at high altitudes. I didn’t quite understand the question you asked; I’ll just share my understanding of the torchbearer role. Generally, steam is divided into two streams: lift steam and smoke exhaust steam. Regarding smoke-suppressing steam, I’ve already mentioned it above; as for cooling, it might have some effect, but smoke-suppressing steam is generally not used for cooling purposes, and it’s not often employed at all. Our unwritten rule is that driving is only allowed in cases of black smoke. Because as the smoke-suppressing steam is turned on, the amount of steam used increases sharply, and the steam pipes on site vibrate violently, which is quite frightening. So generally, when the torch temperature is high, it’s sufficient to use steam for boosting. To put it simply, using 20% of steam for boosting results in less vibration compared to using 1% of smoke-reducing steam, yet it still achieves a better cooling effect than the smoke-reducing steam. It blows the flame away from the torch tip; it works on a different principle than smoke-suppressing steam. As for protecting the torch tip, in my position I have experienced temperatures as high as nearly 900°C at most, with temperatures usually kept below 700°C. In fact, the regulations require that the design temperature of the torch tip must be no lower than 1200°C. However, on one hand, Chinese manufacturers cut corners in production; and on another hand, it’s important to note that while the torch tip can withstand high temperatures, the thermometers installed on it cannot. No matter how high the melting point of the metal components is, it doesn’t help. We have a total of 8 thermometers on our high- and low-pressure torches, and 4 of them have already become unusable.

I’d like to ask you, what is the purpose of increasing the steam flow? Is it to prevent backflow and extinguishment due to too low a flow rate of the flare gas?

That’s definitely not the case. On the contrary, it is gases with a high flow rate or high calorific value that increase the temperature of the torch tip. In order to protect the torch tip – and actually more so to protect the thermometer, as regulations require that the design temperature of the torch tip be no less than 1200°C – we need to blow the flame higher, thereby reducing the temperature of the torch tip. You can do an experiment; I’ve used this experiment when giving lectures to others as well: take a lighter, light it, and you’ll see that the flame is right above the opening through which it’s lit. Then increase the air supply to its maximum level and light it again – you’ll find that the flame \"flies\" upward. It’s similar to how steam is pushed upwards, only in this case it’s steam that does the pushing. Backfire occurs; it is related to flow rates and happens only when there is a sudden change in temperature. For example, after large amounts of discharge, the temperature of the water seal tank is relatively high, and if it happens to be raining, the temperature of the water seal tank drops significantly after the discharge is complete, which leads to a sudden drop in pressure in that tank and thus backfire. Low flow rate can generally occur when the flare tip pulls the gas upward, creating a negative pressure in the water seal tank. However, this negative pressure can occur spontaneously; it does not cause tempering, but it accelerates the corrosion of the gaps in the water seal tank. We have two methods to prevent tempering: one is to install a speed sealer, and the other is to inject nitrogen (we also have fuel gas for supplementation, but it is not used frequently unless the calorific value is very low and supplementary combustion is required). The water seal tank cannot serve as a means of suppressing detonation; a true detonation will still occur. However, the water seal can contain the explosive gases generated by such detonations within the tank, preventing them from spreading to the equipment area.

In my opinion, the smoke-removing steam is primarily used to adjust the amount of air; by increasing the amount of air, black smoke can be eliminated

It should mainly be 2, 3, 4, and 5. I really haven’t heard of the water-gas reaction; haha, I’m not well-informed enough.

I have had technical discussions with several large torch manufacturers in China, and their responses were similar: the main function is the second one, that is, to create turbulence thereby drawing in more air.