How to treat the flue gas from catalytic cracking catalyst regeneration
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Currently, during the regeneration of catalytic cracking catalysts in refineries, large amounts of flue gas are generated – this gas is at high temperatures and contains a significant amount of dust, making it difficult to treat it to meet regulatory standards. Is there any effective method for recovering heat and removing such fine dust?
As far as I know, these days most of the dust is removed using cyclones, and then the energy contained in the flue gas is recovered through gas turbines and waste heat boilers. A set of exhaust gas treatment equipment is usually installed behind the waste heat boiler to meet environmental emission requirements. However, handling it in this way will have a rather serious consequence. Due to the presence of a certain concentration of sulfur oxides in the flue gas, corrosion occurs in the waste heat boiler section, requiring regular maintenance. We have experts in this area; if you are interested, we can discuss it further :)
Use a three-spinner to remove catalyst dust; recover heat with a flue gas turbine and a waste heat boiler; superheated saturated steam in the flue gas
There is a lot of catalyst fume dust; instead of trying to address it right away, it’s necessary to check the centrifuge, as otherwise the catalyst will be worn out too quickly
2nd floor: What temperature can a cyclone dust collector withstand?
It is understood that the cyclone installed behind the catalytic cracking unit can theoretically withstand high temperatures of around 1,000 degrees Celsius, while the actual operating temperature is likely to be in the range of 800 to 900 degrees Celsius.
After long-term catalytic cracking, the catalyst should have carbon deposits on it; therefore, if it is to be regenerated, it should be burned! In that case, the gas produced must be VOC gas (since there are no more detailed data, this is the only inference I can make)! ! ! There are many methods for treating VOC gases, and the most mature technology currently available both domestically and internationally is likely RCO catalytic combustion! ! ! Of course, RTO, RO, CO, adsorption, and more can all be used for treatment! But RCO gives the best results! ! I hope the moderator will consider this carefully! ! !
It contains a large amount of fine dust, which is mainly what makes it difficult to handle.
The main component of these fine dust particles you mentioned is catalyst, and these particles wear down the gas turbine behind them, reducing its lifespan； It can also cause ash accumulation in the waste heat boiler located behind the flue gas turbine, affecting the stability and safety of the system. Lastly, if there are no appropriate exhaust gas treatment devices before the gases are released into the atmosphere, the emissions will not meet the required standards. In addition, if too much dust is present in the flue gas, it can cause severe damage to the catalyst. But I’m not quite clear about the reason for the fine dust that concerns you. Is it to prevent the problems I mentioned earlier? If you’re interested, we can discuss it in detail.
In fact, for the final exhaust gas treatment in catalytic devices, in order to achieve emissions that meet environmental standards, it seems that many manufacturers do not carry this out in practice, especially those in the domestic refining sector. In reality, using ammonia water for alkaline desulfurization makes it very difficult to handle the resulting waste liquids and the catalyst powder carried along with them; hence, this approach is not practical in practice.
If there is a large amount of dust, it is necessary to address the issue at its source, for example by choosing the appropriate type and quality of catalysts, using suitable screening methods and maintaining proper moisture levels during production; it is also important to prevent backburning and secondary combustion in order to reduce the amount of dilute phase. The use of combustion oil should follow the principle of gradual application, without rapid or excessive use. The main air line speed should not be too high. The bed reserve should not be too low. The adjustment amount should be made gradually to avoid large fluctuations in operations. The equipment has been upgraded, with advanced horizontal tubular three-rotor types such as the PT type and PIM type being employed; these are efficient three-rotor systems developed for heavy oil catalysis that can **reduce dust in the flue gases**. It can also be connected to a flue gas desulfurization unit.