Regarding the Dezhou Petrochemical gasification startup cooler
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Currently, most Texaco vaporization units have eliminated the start-up cooler after adding a vacuum flash line at the beginning of operation. However, in actual production, due to the frequent wear and breakdown of the high flash angle valve at the inlet of the vaporizer or the subsequent release tank, it is necessary to depressurize the system and discharge the black water to the vacuum flash unit for treatment, a process that takes four to five hours. If additional start-up coolers are added and the black water is fed in, how long can production be maintained at reduced load without the need to release gas or lower pressure? What are the impacts on the gray water system? For units equipped with a startup cooler, how long can the coolant pipeline be used without affecting normal production?
This issue has also been discussed on the forum. To be honest, it’s a problem that bothers me too. Removing the start-up cooler was the result of technical modifications; in fact, installing a start-up cooler is a scientific and reasonable approach, as it eliminates many inconveniences and troubles. I suggest that the design keep it.
The startup cooler does have its advantages; at least when dealing with the situation where the buffer tank is worn out due to the high-pressure flash valve, the process is faster when a startup cooler is available. However, if black water enters the startup cooler, the gasifier still needs to have its load and pressure reduced. Because in the pipeline leading to the startup cooler, there are inevitably high-pressure lines running alongside low-pressure lines in lower areas; if the pressure difference is allowed to act directly, the consequences are something the original poster must be aware of.
The key is the processing capacity of the cooling unit; with such large volumes and high temperatures, it’s necessary to ensure proper cooling. Circulating water also needs to be taken into account to prevent any significant impact on the black and gray water systems
Reply to 3# pyp222: Our previous company has experienced operation under high pressure differences. The cooler performed well at first; it was no problem to maintain production at half load. Once the water temperature dropped, there were no issues with wastewater discharge. Mainly, after severe blockage occurs later on, the temperature fails to drop, and the pipeline behind the angle valve vibrates intensely.
That’s exactly what I mean: there shouldn’t be too many problems in the early stages of system operation, but after it has been running for half a year or more, things change, and that’s when problems arise...
It’s better to address any issues as they arise. In my opinion, solving the problem of wear on the buffer tank after installing the high flash point valve shouldn’t be too difficult; several factories in China have managed to handle this issue successfully. I suggest that companies exchange ideas on this matter. As for using coolers, due to the large temperature differences, scaling occurs quite quickly, so it’s not recommended.
Our factory now doesn’t use a startup cooler either. But I think what the original poster said makes sense. I’ve never understood it
Reply to 1# Fengqing888: Our factory has been in operation all along; it features a very scientific design
Starting the cooler is very useful for the gasification unit; it does not affect the load, so it is not recommended to eliminate it!
The impact isn’t very significant; just the water temperature goes up a bit. It should be fine for at least half a day. Actually, the technical modifications are quite good too – if there’s a problem with the angle valve, isn’t it still possible to direct the water directly to the vacuum flasher?