The temperature difference between the dense and dilute phases is small, but the oxygen content is higher
Thread Content
My unit is a catalytic device of the coaxial type with oxygen-enriched regeneration. Under normal conditions, the processing capacity is 130; the bed temperature ranges from 695 to 700 degrees, the temperature difference between the dense and dilute phases is 15 to 20 degrees, the main air flow rate is 140,000, and the oxygen content is 1.5 to 2.0%； Recently, due to emergency repairs on the flue gas exhaust system and fan switching, the main air flow rate dropped to 120,000; the processing capacity was 115 t/h, the bed temperature was 680 degrees. The temperature difference between the dense and sparse phases remained roughly the same, but the oxygen content was high, at 2.5–3.0%. Samples of the catalyst were taken, and slight carbon accumulation was observed. Under these conditions, what is the best approach to take? If the processing capacity is increased further, could this lead to an increase in carbon accumulation?
Improve the coking effect of the coking tank, check its capacity, and ensure complete combustion.
Continuing to increase the volume will lead to an intensification of the carbon pile. It should be burned slowly at first; adjustments should be made only after there is a temperature difference between the dense and sparse areas.
Coaxial type, without a burnt tank.
This is certainly due to poor densified burning effects; the issue should be analyzed from the perspective of bed fluidization, as it’s likely that poor fluidization is the cause
Carbon accumulation refers to a loss of balance between the amount of carbon that burns and the amount that remains unburned; when the latter is greater than the former, the carbon content in the regenerator keeps increasing, like an avalanche. What you’re describing isn’t actually carbon accumulation; it’s just that the color of the regenerant is darker and its carbon content is higher. The carbon content in the regenerant should be sampled and analyzed; if it exceeds the specified limits, the operating procedures must be adjusted.
Coaxial type: no burnt tank. In the past, the main air flow rate was high, at 140,000; the temperature difference between the dense and dilute phases was quite significant； Currently, the main wind speed is 120,000; the temperature difference between dense and sparse areas is relatively small, while the oxygen content in the rear area is actually higher ； Today, as part of the scale-up tests, the bed temperature in the regenerator increased overall; the temperature difference between the dilute and dense phases remained relatively close, with no negative values observed ； Additionally, I installed a denitration unit using the backstream SCR process, which is located inside the residual boiler. Previously, when the main air flow was high (140,000), the ammonia injection volume was low (3–4 m3/h) ； But now, with a lower main air flow rate, the ammonia injection volume is high, at around 20 m3/h ； What’s going on here?
A regeneration temperature of 680 degrees cannot completely burn off the coke on the catalyst, and this is independent of the carbon bed. Increasing the regeneration temperature reduces the carbon content of the catalyst. It is recommended to increase the processing volume, raise the amount of raw rubber, and raise the regeneration temperature to around 700