What is the purging medium used for the soot blower in the convection section of the cracking furnace?
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What is the purging medium used for the soot blower in the convection section of the cracking furnace? Can other media such as nitrogen or SS be used instead? Answer: It is medium-pressure steam. In the convection section, the hot flue gas is cooled from approximately 1200°C to about 140°C. When selecting a soot-blowing medium, first of all, its temperature must not be too low to prevent sudden cooling and breakage of the coils in the convection section; secondly, the mechanical properties of the coils in this section decrease at high temperatures, so the pressure of the soot-blowing medium cannot be too high. Considering the above two points, nitrogen and SS cannot be used as purging media for the soot blowers in the convection section of the cracking furnace.
It’s the same with ethylene; come and learn* it
Isn’t soot blowing done after the boiler is shut down?
High-pressure steam of around 40 kilograms is sufficient; in fact, the person asking the question doesn’t need to worry about what the medium is – what’s important is whether the soot blowing system can be used effectively! In my former company’s two ethylene plants, the soot blowers of the older plants did not work well; steam was used as the medium for soot blowing, and they were operated only once every few years! The 1 million-ton ethylene plant installed later did not have soot blowers in its design. A few years after it started operating, the thermal efficiency declined due to the accumulation of soot; without using cooling water, the SS temperature was only around 490 degrees. The workshop was then asked to resolve this issue. After shutting down the plant, several observation holes were removed, fans were used to create airflow, and air was supplied through hoses to blow out the soot from the distribution tubes in the convection section. This approach proved very effective, and eventually the SS temperature could reach over 510 degrees once the plant resumed operation. For soot blowing in domestic applications, dry ice blasting can also be used; if you need it, I can help you get in touch with the relevant parties!
Neither of the 120,000-tonne nor the 150,000-tonne pyrolysis furnaces used in our facility is equipped with soot blowers; over the past 6 years we have not observed any significant decline in thermal efficiency, nor has there been any noticeable accumulation of soot in the convection section. Yangzi has soot blowers, and they use the MS type
In the past, for soot blowing in our catalytic residual heat boiler, acetylene and air were used in a certain ratio to carry out explosive soot blowing.
Whether to use soot blowing in the pyrolysis furnace or not depends on the fuel used in it; if the fuel has good properties, then a soot blowing system is not included in the design.