What are the technical issues with the technology for using catalyzed diesel in lift pipes for reprocessing to increase gasoline production?

There’s no problem at all; it’s completely fine.

Energy consumption increases, while the yields of dry gas and liquefied gas are high.

The measures are very good as they can increase the production of gasoline and liquefied gas; the downside is that the production of coke and dry gas will rise, as well as energy consumption.

It sounds like a good idea, but it’s not possible to convert all diesel into gasoline or liquefied gas; dry gas and coke will definitely be produced. Whether there will be a profit is something that needs to be considered

It’s mainly a financial issue; it’s acceptable as long as it’s cost-effective.

Thank you all for your responses. I also found an article from the Institute of Rock and Mineral Sciences on the analysis of the cracking properties of diesel fuel; experiments were conducted in the laboratory, and the conversion rate of diesel was around 50%. The octane rating of the gasoline produced was relatively high, at approximately 91–93. Of course, some dry gas and coke are generated as a byproduct, which increases energy consumption. Moreover, the quality of the unconverted diesel becomes worse. However, whether this measure is feasible seems to depend crucially on an economic evaluation.

There is no problem with the process; it’s just that the efficiency is low. Currently, a fuel tax is in effect, with the tax on gasoline being higher than that on diesel. The selling price of diesel is higher than that of gasoline.

We are also considering the issue of reprocessing diesel here. The main idea is to implement this in the third catalytic converter unit, as that unit uses an FDFCC process and has a separate riser for reprocessing gasoline. We now want to stop producing gasoline and switch to processing diesel, given that diesel inventory is increasing steadily while sales are not performing well. At present, we are assessing the economic aspects as well as the operational implications of this approach. Reprocessing diesel will inevitably lead to coking in the second settler; we are wondering whether it will be possible to operate this unit over long periods of time, and whether the catalyst from the secondary settler entering the main riser will affect the overall reaction efficiency. These are the issues we are currently considering, and we hope to have more discussions on them

It is completely possible to do that. . . During our university years, when we conducted experiments on catalyst activity standards using laboratory catalytic cracking units, the material used was usually diesel. . . Product distribution: increases in gas and gasoline volumes. . . :lol

The idea of using diesel for reprocessing to produce more gasoline is good, but since diesel consists of 30% straight-chain alkanes and alkenes that are easy to crack, 15% cycloalkanes, over 50% aromatics, and over 30% polycyclic and aromatic compounds that are difficult to crack, the conversion rate is low. As a result, the yield of gasoline and light components is very low; most of the product remains in the form of diesel components, and their quality deteriorates. Moreover, the amount of coke produced increases, energy consumption rises, and the economic benefits are not significant. If reprocessing diesel is to be carried out, the appropriate reprocessing location must be chosen; if it is mixed into the feedstock, the reaction depth will be insufficient and the conversion rate will not be adequate ； It is feasible to modify the gasoline reprocessing lift pipe of the FDFCC unit on the 9th floor to use it for diesel reprocessing; the degree of reaction can be adjusted. However, the downside is that it will disrupt the catalyst circulation rate and the balance related to coking, affecting the processing capacity of the feedstock lift pipe ； If a conventional catalytic cracking unit is equipped with feed nozzles of a smaller diameter than those required for the feedstock, they can be modified to diesel reprocessing nozzles as appropriate, but the orifice plates for the atomizing steam must be adjusted.

What was said upstairs is quite specific; if diesel is to be reprocessed, how should the location for this reprocessing be chosen? Using blended raw materials definitely won’t work; we’ve tried it, and the process is extremely difficult, plus the resulting product still contains diesel components. I think we should find ways to adjust the operating conditions so as to produce as much gasoline as possible and as little diesel as possible.

The reprocessing location should be above the raw material location; it is better to use a catalyst with slightly lower activity. Otherwise, if the activity is too high, more dry gas and coke will be produced, resulting in higher energy consumption. Although a catalyst with lower activity leads to a slightly lower conversion rate, it still helps to maintain profitability, allowing for further reprocessing.

After diesel reprocessing, the yields of vapor phase and liquefied gasoline increase, but the density of diesel rises to around 970–980

Reprocessing is certainly possible, and it does indeed increase the yield of gasoline. However, the amounts of LPG and dry gas will increase as well, since reprocessing entails higher energy consumption. It is appropriate to decide whether to proceed with reprocessing after conducting a comparison of economic benefits and societal needs. Using the feed location for mixing with the raw materials is not suitable; instead, a reprocessing oil nozzle can be considered above the raw material nozzle, and those equipped with quenching agent nozzles can also be used. The most ideal location is actually between the reprocessing oil nozzle and the quenching agent nozzle, but such setups are generally not available. If considering the reprocessing of diesel, it would be more cost-effective to focus on light contaminated oils that are rich in diesel components

1. Upon entering the reaction phase, the amount of coke produced increases. 2. When it enters the distillation system, such as Stage 1,

Absolutely. The slide valve allowing the catalyst from the secondary settler to enter the main lift pipe should be left slightly open, so as to prevent blockage.

Our company has used some of the straight-run feedstock as cracking agents, and it is now operating normally. However, a detailed economic assessment has not yet been conducted.

There shouldn’t be any problems with this. This was the case in the early stages of the development of our catalytic technology – it was designed to produce more gasoline and gases – but this led to waste, as diesel is already a finished product that has to be reprocessed! When carrying out reprocessing, attention must be paid to the quantities used, as the amount of coking that occurs in diesel is definitely very low; therefore, it is important to monitor changes in various parameters and make adjustments promptly during the operation

Isn’t the overall benefit not cost-effective enough?

Attention must be paid to the quality of the final diesel product; compared with diesel reprocessing, the quality of the diesel after reprocessing deteriorates, with a decrease in cetane number and an increase in aromatic content.