There is a temperature difference in the bed of the hydrorefining reactor

Temperature differences are divided into radial temperature differences and axial temperature rises. The radial temperature difference refers to the difference in temperature across the same cross-section of the reactor, that is, the difference between the highest and lowest temperatures. The axial temperature rise, on the other hand, is due to the increasing temperature at each layer as a result of the exothermic hydrogenation reaction; it represents the difference between the highest and lowest temperatures within the entire reactor. The formation of radial temperature differences is related to factors such as the quality of catalyst packing and coking conditions, while the axial temperature rise refers to what we call the bed temperature rise, and it is influenced by factors such as the properties of the feedstock, catalyst activity, reaction temperature, hydrogen circulation rate, and quench hydrogen flow rate.

Reply to 2# Light as a swallow: Thank you! I’ve considered everything you mentioned, but I’m not quite sure about the radial temperature difference that occurs right when the vehicle starts running. There has always been a temperature difference in the lower layer of the second counter.

Is the rapid cooling hydrogen flow rate stable? The injection of cold hydrogen will cause instability in the bed temperature.

Reply to 4# Light as a swallow: Thank you for discussing this with me. The stable operation of the unit suggests that it’s not due to the rapid cooling hydrogen; in fact, since it doesn’t affect production, I just want to analyze the reasons behind this. Do you think it could be a problem with the thermocouples?

The formation of radial temperature differences is related to factors such as the quality of catalyst packing and coking conditions. Has this been the case since the plant started operating? If so, it’s necessary to shut down the plant and investigate whether it’s a problem with the catalyst

1. The formation of radial temperature differences is related to factors such as the quality of catalyst packing, coking conditions, properties of the feedstock, circulation hydrogen flow rate, and quenching hydrogen flow rate； 2. The impact of coking is basically eliminated when the unit just starts operating ； The effect of the thermocouple is present; the true value can be determined after making calibration adjustments, or it can also be measured using another thermocouple ； If the raw material contains large amounts of heavy metal inorganic salts, it may cause radial temperature differences within the bed layer over time; a raw material analysis is required to draw conclusions ； The feed rate and the flow rate of recycled hydrogen affect the distribution within the bed; if the feed rate is low, it is necessary to increase the amount of recycled hydrogen to ensure proper distribution and keep the radial temperature difference within acceptable limits ； If the issue is caused by uneven distribution on the distributor disc, it becomes quite troublesome. To determine the cause—whether it relates to the quality of installation, the manufacturing quality or design of the distributor disc itself, or a small quantity of units—thorough investigation is required in order to find a solution