Handling after the feed oil pump stops vibrating

After the crude oil pump stops vibrating, can it be started up to feed material directly with the feed control valve already closed in advance? (Not related to the feed oil nozzle) Whether it’s for a short period or a long period, if the catalyst is flowing properly during a short time, the temperature will rise rapidly once the feed to the riser is interrupted, and the bed temperature will drop quickly as well. It is necessary to decide based on the actual operating conditions; it’s best to adjust operations in accordance with the normal feeding procedures. Over an extended period, the bed temperature will drop, which will require the injection of combustion oil; the specific circumstances can vary greatly.

In this case, if one power supply is interrupted while the other remains functional, can the other pump be started directly to supply feed after the pump stops? What are the impacts and precautions of direct feeding?

The owner’s idea relies on several premises: first, the catalyst circulation is normal; second, the temperature at the outlet of the lift pipe is normal； Third: Regardless of the nozzle, the feed control valve works well. Fourth, anti-repressure control ； Fifth: Raw material preheating temperature. (The preheating temperature does not drop rapidly in a short period of time, so it is not taken into consideration.) That is: if the feed is interrupted, the temperature of the riser drops rapidly due to the large amount of steam being supplied. Furthermore, the catalyst circulation and rate-limiting factors at this time differ from those in normal operation. Therefore, to ensure the first two points, very fast processing is actually required. Additionally, I would like to remind the poster that even though the opening degree of the feed control valve is small, the amount of raw material that may be injected instantaneously could still be significant. Let’s take a practical example: during the shutdown and reduced operation of a 1.2 million-ton catalytic unit using the MIP process, the feed rate was reduced by closing the feed control valve. (Of course, it’s possible that our feed control valve was sized too large.) The control valve was set at 3%, keeping the feed rate at 90 t/h. It’s easy to imagine what would happen if operations were to resume quickly – a large amount of cold oil would enter in an instant, without enough time to vaporize; you can think about the consequences of that.

May I ask, how does the original poster’s team handle the situation when the crude oil pump stops working?

The method for handling the shutdown of the crude oil pump is similar to that for dealing with the interruption of reaction feed. Of course, although our procedures do not specify the need to close the feed nozzle – this is on the assumption that the feed control valve functions properly – in practice it is still necessary to close the feed nozzle in order to prevent large amounts of cold oil from entering the reactor.

Material supply interruptions are interlocked; generally, once such an interruption occurs, the interlock system will be activated immediately, and the normal accident handling procedures should be followed – do not take the risk of starting the pump directly.

Personally, I think it’s possible, as the temperature hasn’t dropped despite the passage of time

The time it takes for you to restart the pump is, under normal conditions, how long does it take for you to get it running? The feed pump stopped, the bed temperature dropped rapidly, and with no feed supply, the compressor also shut down. Unless you immediately spray burning oil to maintain the bed temperature, ensure the catalyst is fluidized, and control the temperature, pressure, and liquid level. Quickly start the backup pump, turning it on step by step.

OP, you might consider spraying diesel first. I’m not talking about burning fuel oil in the regenerator, but diesel being injected into the riser (if such a process exists)

This post was last edited by wt2008 on 2015-7-28 07:54. After the crude oil pump stops intermittently, can it be started up to feed material with the feed control valve already closed in advance? (Not related to the feed oil nozzle) In my opinion, after the feed oil pump stops operating intermittently, the general principles for handling the situation are as follows: 1. Immediately open the flare at the compressor inlet to control the reaction pressure ； 2. Enable feed self-protection and check that the self-protection function operates correctly ； 3. Reduce the main air supply to each regenerator, ensure proper pressure balance among the three reactors, and maintain normal fluidization of the catalyst in all three reactors ； 4. Reduced steam production ； 5. The air compressor operates at low speed or stops. Generally, after the feed oil pump stops operating, the plant requires that the main valves located before and after the safety valve on the feed oil feed line be closed. The feed oil nozzle valves are not closed due to their large number, in order to prevent feed oil from leaking into the lift pipe. When reorganizing the feed, it usually takes a long time, over half an hour. The general steps are: 1. Restart or activate the backup crude oil pump to ensure it operates properly ； 2. The flow of the three devices is normal ； 3. Spray combustion oil depending on the temperature of the thalamus to raise the bed temperature of the regenerator and meet the conditions for oil spraying ； 4. Use control signals to shut off all the feed oil control valves ； 5. Feed self-protection reset ； 6. Open the main valves that were closed before and after activating the self-protection valve ； 7. Once the feeding conditions are met, gradually open the feeding control valve to start feeding. If the poster wants to shorten the time and skip some steps, it is possible to do so if conditions permit; however, safety accidents can occur, such as leaks in the feed oil heat exchangers, feed oil leaking into the lift pipe along with sludge, backflow of feed oil, or feed oil that has not been cracked being carried into the regenerator – all of which can result in losses. It is important to avoid such situations. This is my personal opinion for reference only.