Questions regarding the operation of the Topsoe WSA spent acid regeneration unit?
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The unit where the poster works is used for treating alkylation waste acid. The technology employed is Topsoe’s wet acid purification process. Having been in contact with this process for about half a year, there are still many aspects of it that I don’t fully understand. I hope that experienced colleagues can kindly provide some guidance on the following questions. 1. The biggest problem in spent acid regeneration is the frequent start-up and shutdown of the equipment; clogging of the furnace tubes in the waste heat boiler is inevitable. Is there any way to mitigate this clogging and extend the operating time? 2. The acid mist controller sometimes experiences shutdown issues. Are there any methods for troubleshooting such problems? (Different standby positions of the combustion controller indicate different issues; are there any corresponding handling procedures?) The color of the newly produced acid sometimes appears blackish-red; what circumstances is this related to? During the operation of the 4 devices, have there been any optimizations of operating technical parameters? For example, what is the appropriate temperature control for the furnace, pressure control for the condenser, and what should be the optimal oxygen content coefficient? I hope fellow forum members will not hesitate to offer their advice.
Where is your company located? Currently, there are not many cases where Topsoe’s wet acid production process is used for treating alkylation waste acid. The existing plants all suffer from the problems mentioned by the OP; there is limited operating experience with them, and these issues need to be gradually resolved during actual operation. I hope everyone will actively engage in discussions on this topic.
Over the past six months, there have been 5 shutdowns, all due to blockages in the waste boiler tubes. Under full load conditions, it’s quite good if the system can operate for a week; under half-load conditions, it can run even longer. The nozzle for discharging waste acid has been changed to one with a larger diameter. Efforts have also been made to reduce the viscosity of the waste acid to improve its fluidity. The pressure inside the furnace is controlled, and the oxygen content is kept at a relatively high level; however, the results aren’t very satisfactory
With so many alkylation units operating around the world, there must be quite a lot of waste acid regeneration processes as well. How does Monsanto’s SAR process perform? There are also numerous processes developed by Jin Tao, right?
Are there any improvements you would suggest regarding the atomization of waste sulfuric acid? I’ve come across some materials regarding types of atomizers; they mention ultrasonic atomizers, compressed air atomizers, and rotary atomizers. Is there anyone here who knows anything about these?
Foreign-made devices have an oxygen content of around 10%. All parameters must remain stable; otherwise, efforts will be counterproductive
According to some references I’ve consulted, the optimal oxygen content should be between 4 and 5. If it’s too low, combustion becomes incomplete; if it’s too high, it places excessive burden on downstream equipment, thereby increasing operating costs. Currently, we maintain a level of around 8–9. I’d like to ask how you handle this in practice?
Currently, the facilities for producing acid via the pyrolysis of waste acid are mainly dry-process type.
What temperature do you set for the temperature control of your cracker? What is the concentration of SO2 entering the converter?
The temperature of the furnace is between 1000 and 1100; when the temperature in the rear section cannot be controlled, it drops to around 950. The concentration of the process gas entering the converter has not been measured
On what was supposed to be a nice day, the small fan in the electrostatic precipitator tripped and wouldn’t restart. Eventually, I had to reboot the system to get it working again. When faced with such problems, it’s really difficult for a mere operator like me. There’s no relevant information available; when faced with such situations, I’m completely at a loss. Are there any HaiYou who know about this?