Where is the best location to inject the passivator before feed into the riser of a catalytic cracking unit?

The injection point of the passivator should be as close as possible to the fresh feed line at the inlet of the riser. It is necessary to ensure that the passivator and fresh raw materials are mixed evenly (in a turbulent state) before entering the lift pipe. To prevent the thermal decomposition of the passivator (which decomposes easily above 190°C), the filling point should be located after all heaters. The feed temperature can be appropriately reduced, which not only prevents the thermal decomposition of the passivator but also increases the agent-to-oil ratio.

Considering the process changes and optimizations, my workshop has arranged the passivator addition line along the outlet line of the raw material pump

There are answers to the questions regarding catalytic devices; under normal circumstances, it is added after the heat exchanger. When connecting those on the upper floor to the pump outlet, one should mainly take into account the surge at the pump outlet, as this helps with mixing, haha. When installed on our plant’s pipelines, it yields good results. Opinions on this method vary; the general approach is to place it after the pump heater, with the temperature kept below 200 degrees

After adding all the heat exchangers to the feedstock, it is located at the quick-opening valve of the feed oil; the preheating temperature of the feed oil is around 210 degrees

Our plant is installed after the last raw oil heat exchanger; it enters the lift pipe directly together with the raw oil, thereby preventing the decomposition of the metal passivator due to high temperatures

Our device is installed before the self-protecting valve. When determining the preheating temperature, in addition to considering the decomposition of the passivator and the agent-to-oil ratio, the viscosity of the raw material also needs to be taken into account to facilitate atomization and reduce the formation of coke. We are at 210°C.

Stay as close to the nozzle as possible; after heat exchange, it’s generally fine as long as the feed temperature doesn’t exceed 180 degrees

We are also on the fresh feed line near the lift pipe inlet.

On the fresh feed line near the lift pipe inlet, the temperature is 190–200 degrees.

Detailed answers are available for the technical questions related to catalytic cracking units. The commonly used metal passivators are antimony compounds, which have poor thermal stability; they decompose when exposed to high temperatures for extended periods. Therefore, it is advisable to place them as close as possible to the raw material heat exchange system before it enters the lift pipe, while still ensuring a sufficient mixing length to achieve uniform mixing. In our unit, the injection point is located about fifteen meters away from the raw material nozzle. Several factors need to be taken into account regarding the feed temperature in order to prevent the passivator from decomposing due to excessive temperatures； It is also necessary to maintain a certain temperature to facilitate the atomization of the raw materials ； Oil-to-agent ratio. It is generally around 200°C.

Our filling point is located after the raw material nozzle control valve, very close to the high raw material nozzle. Actually, remember two things: one is to mix evenly, and the other is to avoid decomposition.

Previously, in our factory, it was located behind the heat exchanger, quite far from the raw material nozzle; now the heat exchanger has been removed, and the liquid is poured directly into the raw material mixer, going straight into the nozzle! 1、

The temperature of the crude oil must not exceed 250 degrees, as the passivator decomposes easily at such temperatures. The temperature of the crude oil in our unit, as well as the oil temperature after the heat exchanger, is around 170 degrees. The injection point should be close to the nozzle, and a mixer is needed for even mixing, which yields better results.

15 to 25 M from the nozzle； One is to consider thermal decomposition, and the other is to consider the mixing effect; a long distance results in a long residence time, which facilitates decomposition. It takes too short a time; mixing is not thorough. We are at the raw material mixer. The temperature ranges from 180 to 220 degrees Celsius; the temperature of the raw materials must be controlled by taking the reaction conditions into account.

Try to position it as close as possible to the raw material feed nozzle, but still leave a certain mixing length to ensure uniform mixing; in our setup, the injection point is about 12 meters away from the raw material nozzle, and the feed temperature is generally around 180–200°C

First, there must be a certain line speed; otherwise, blockages are likely to occur； The second temperature should not be too high to prevent decomposition, as this could affect the effectiveness of use; it is generally injected after the heat exchanger. Thirdly, it should be placed as close as possible to the feed nozzle, but still at a sufficient distance to ensure proper mixing of the passivator and the raw materials. That’s all I remember: lol

We place it after the raw material mixer; the temperature of the raw materials after heat exchange is 200. . .

The injection point of the passivator should be as close as possible to the fresh feed line at the inlet of the riser, for two reasons: first, to ensure thorough and uniform mixing of the passivator with the fresh feed； Second, reduce the contact time between the metal passivator and the raw materials to prevent the thermal decomposition of the passivator. The preheating temperature of the raw materials is generally controlled at 200~220 degrees.

Passivation agent injection point: 1. After all heat exchangers, to prevent the passivation agent from decomposing； 2. It is generally injected into the fresh feed while maintaining turbulence to ensure uniform mixing, and it is kept at a certain distance from the lift tube nozzle to facilitate thorough mixing. 3. The feed temperature is generally around 200 degrees, sometimes depending on the atomization requirements of the nozzle.