What is the feed temperature at the start of diesel hydrogenation operation? We usually use 220°C. How is this temperature determined?

What does that mean? Could you be more specific?

For the catalysts that have been passivated, the feed temperature is set according to the manufacturer’s specifications; our factory’s catalyst is the RS-1000 from the Changling branch, and the temperature is around 280 degrees, after which the passivation oil is gradually introduced.

In a pure hydrogen environment, large-scale reduction of the catalyst occurs at 230 degrees Celsius; therefore, you chose 220 degrees as the temperature to prevent excessive temperature rise that could lead to runaway conditions. In fact, the temperature could be slightly higher, at 250 degrees Celsius, since the reactor temperature drops significantly once feeding begins.

The principle is simply to reach the catalyst activation temperature, but it must not exceed the temperature at which the catalyst is reduced by high-temperature hydrogen

To prevent the catalyst from being reduced in a pure hydrogen environment, the value is generally around 220-250.

First, excessively high temperatures can prevent uncontrolled temperature spikes in the subsequent bed layers of the reactor, thereby leading to unstable system pressure. Second, ensure that the hydrogen sulfide concentration within the system remains at a certain level after 230

According to the temperature set by the catalyst manufacturer. Your company has set it at 220 degrees to 1. protect the catalyst from being reduced by hydrogen ； 2.220 degrees can raise the temperature to the reaction temperature in a short time

It is mainly to protect the catalyst; above 230 degrees, in the absence of H2S, pure hydrogen can pose a risk of reducing the catalyst back to its metallic form

Hello, over the past year we have experienced multiple interruptions in the supply of fresh hydrogen and medium-pressure steam here; the system pressure could not be maintained, which forced us to shut down the plant and stop operating the cycle hydrogen compressor. These shutdowns lasted for more than 20 hours each time, during which the reaction temperature remained above 300°C and could not be reduced. During the recovery process, to prevent catalyst deactivation due to a decrease in the hydrogen sulfide content in the circulating hydrogen as the system pressure rises, and also to avoid excessive temperature increases, it was required that the operator lower the reactor inlet temperature to the normal feeding temperature before resuming feeding. Because cooling down and then heating up again significantly prolongs the time it takes for the equipment to recover, which is not conducive to the blending of oils across the entire plant. If the temperature is not reduced, feeding directly after the system reaches the target pressure could save a great deal of time, but it’s really not possible to do that. May I ask if this is reasonable? Thank you.

I once added oil by directly raising the temperature to the reaction temperature, but at that time the circulating hydrogen contained hydrogen sulfide; fortunately, it had no effect on the catalyst:dizzy: