Control of the feed temperature in the catalytic unit

I’ll just say what I know: actually, a higher temperature is better as it results in better atomization, but if it’s too high, the oil-to-agent ratio decreases. Nowadays, nozzles are getting better, and the requirements regarding the temperature of the raw materials are not as strict as before

It depends on the type of raw material being processed. When the oil is heavy and has a high viscosity, a higher temperature is usually required; generally, this is between 200 and 220 degrees. Beyond that, increasing the temperature has little effect on the atomization process, but it does affect the oil-to-agent ratio as well as energy consumption.

We keep our device at 200-220 degrees, and currently the yield and product distribution are both excellent! I agree with what was said on floors 2 and 3; under normal circumstances, there is no need for the preheating temperature of the crude oil to be too high.

The feed temperature is primarily determined based on the atomization effect of the feed and thermal balance; temperatures below 180 degrees affect the atomization effect, so a temperature of around 200 degrees is generally used. 　Too high a temperature not only reduces the agent-oil ratio but also increases the heat absorbed by the regenerator. If the quality of the feed is good and little heat is required for thermal balance, it is possible to consider raising the feed temperature slightly. In fact, the feed temperature of earlier catalytic units was often close to 400 degrees, with dedicated feed heating furnaces.

In heating furnaces, wax oil catalytic cracking is used; the regeneration process cannot generate enough heat, so external heat supply is required. Nowadays, sludge-blended catalysis is more common, as it produces sufficient heat with a surplus, and one or more external or internal heat sources are needed to balance the heat levels!

Generally, a preheating temperature of the raw material between 150 and 200°C is sufficient and appropriate. If the raw material is heavy, the preheating temperature of the raw material can be appropriately increased to 200–220°C, which will meet the requirements; in a few installations it is raised to 250°C, but this affects the agent-oil ratio and the catalyst circulation rate. If it is increased further, an operation condition with a higher catalyst-to-oil ratio may arise, which could lead to new problems; a \"wet\" catalyst might form and cause coking in the settler. If the preheating temperature of the feedstock is low, it has previously been as low as 90°C; this actually favors an increase in the agent-to-oil ratio. However, due to the low temperature, it may affect the atomization of the feedstock. In fact, the preheating temperature of the raw material is primarily determined by the viscosity of the material at the operating temperature; it is necessary to keep this temperature as low as possible while still ensuring effective atomization of the raw material. Of course, it’s not possible to be absolutely precise in terms of operations, so some flexibility can be allowed. In summary, by selecting an appropriate preheating temperature for the feedstock, better atomization can be achieved at lower viscosities, while also taking into account the catalyst circulation rate and the catalyst-to-oil ratio.

If the preheating temperature of the crude oil is high, more thermal cracking occurs during the reaction, which affects the octane rating of gasoline!

What 7L said is that \"if the level is increased further, a condition of higher fuel-to-agent ratio may arise, which could lead to new problems; a ‘wet’ catalyst might form, resulting in coking in the settler.\" ”How should this sentence be understood? This time, due to the reduced processing volume and the requirement to implement a diesel production plan, the reaction temperature is about 10 degrees lower than before. I observed that the temperature at the upper part of the settler is significantly lower than before; could there be another case of coking?

Practice has shown that controlling the preheating temperature of the raw materials at 220 degrees is most favorable for the overall yield, the yield of light oil, and the distribution of the product streams.

The preheating temperature of the feedstock should also be related to its inherent properties; if the feedstock is relatively light and the preheating temperature is too high, cracking may occur within the pipelines, increasing the ratio of catalyst to oil and leading to an increase in the vapor phase components, which affects subsequent operations