Sublimated sulfur is produced in the acid production process from zinc concentrate flue gas
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Our plant produces acid from zinc concentrate flue gas, and we suspect that a large amount of sublimed sulfur is generated inside the furnace. Previously, yellow flaky substances were discharged through the purification overflow weir, and they had a distinct sulfur smell. Currently, black flaky or granular substances are being discharged; tests show that their sulfur content is around 10%, which causes the acid in the dry absorption cycle tank to take on a milky white color and have low transparency. The conversion temperature is abnormal, with the temperature at the exit of the second stage exceeding 530 degrees (previously it was around 495 degrees); the overall increase in conversion temperature reaches up to 270 degrees. It is suspected that sublimated sulfur has entered the combustion zone. Currently, the problem of sublimated sulfur has been alleviated by reducing the furnace load, but it has not been resolved fundamentally. It’s been running for over a decade and I’ve never encountered it. The problem of abnormal transition temperature has also not been resolved. It’s not a problem with the heat exchange area.
It’s due to an insufficient amount of oxygen for combustion during melting, which results in low residual oxygen levels. The material inside the furnace does not burn completely, and elemental sulfur does not react fully to form SO2. With high temperatures in the furnace, sulfur sublimes into sulfur vapor that enters the acid production system along with the flue gases. After purification and cooling, elemental sulfur remains in the system. This should have been detectable earlier; the formation of elemental sulfur leads to an increase in pressure drop during purification, and the pressure on the acid side at the inlet of the gas cooling tower pump also increases. It can also be detected through the sight glasses of the three purification towers. Elemental sulfur enters the converter and covers the first layer of catalyst, resulting in poor reaction performance of that catalyst layer and a shift in the reaction process; simultaneously, the temperature of the second layer increases
Your analysis makes sense, but one segment of our response should work fine; the output for that segment is 590
It is likely that the activity of one layer of catalyst has declined. Due to their poor thermal stability, domestic catalysts experience rapid loss of activity in the higher-temperature areas in the lower and middle parts of that layer.
Based on the color of the acid in the dry absorption cycle tank and the “symptoms” of purification, it matches the characteristics of sublimed sulfur.
There is such a possibility, but the catalyst has been performing well up to now; it was only once that the furnace couldn’t be started due to a failure in the main fan. After emergency repairs and restart, sulfur sublimation occurred, resulting in very abnormal conversion rates
You can send me the converted dry suction DCS screen (QQ: 1304699132) so I can take a look.