The year-end mid-term repair of my workshop starts today
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December 25, 8 am: 20. The conversion of the sulfuric acid I system in my workshop started back blowing (hot blowing). This morning at 3: 00, the sulfuric acid II system will be transferred to backflush, and the sulfuric acid III system will be started at 5 this afternoon: Blowback starts around 00. Nowadays, the price of sulfuric acid is high, so maintenance is generally not chosen at this time. Our factory mainly considers that the life of the Ausmelt furnace has expired, so it arranges for mid-term repair. The planned maintenance time of this time is 12 days. Due to the cooling and heating time of the conversion catalyst, the sulfuric acid system is stopped first and started first. The maintenance time of the sulfuric acid system is only about 9 days. There is a question that I would like to discuss with you, that is, when the system is back-flushed (the circulation pump of the drying tower must be turned on), does the acid pump of the absorption tower have to be turned on? Finger believes that for the low-level high-efficiency dry suction process, since the circulation tank feeds acid from the bottom and has a sealing effect, the absorption tower circulation pump does not need to be turned on, as long as the pump outlet valve is closed. Due to the long-term inertia of thinking in my workshop, the dry suction tower circulation pump is fully turned on when the system is back-blown.
During backflush cooling, there is still a little SO2 in the system. From an environmental perspective, I personally think it is better to turn it on. How long does it usually take to cool down? Let’s learn from this.
Personally, I think it is best to turn on the absorption pump during hot blowing, because in the early stage of hot blowing, there is some SO2 and SO3, and turning on the absorption pump is conducive to environmental protection requirements. Of course, as time goes by, the amount of s gradually decreases, and the smoke temperature and acid temperature of the absorption tower decrease. At this time, the absorption pump can be stopped and hot blowing continues. This stage usually takes five hours in our factory. The second stage (after stopping the absorption pump) takes 7-9 hours.
I think it is necessary to turn on the acid absorption pump during hot blowing. First, there is still SO3, which is an environmental problem. Second, the gas temperature is high, which may cause the porcelain ring and porcelain beam to break.
After everyone's discussion, we can form this understanding: 1. Turn on the acid pump of the absorption tower during hot blowing to protect the porcelain supports and other structures in the tower. ； 2. In order to save energy consumption, the pump operating current can be reduced during hot blowing. ； 3. The SO2 content of the exhaust gas during the cold blowing stage is low, and the pump should be able to be stopped in the later stage of cold blowing.
There won't be much of a problem if you stop the pump when the inlet smoke temperature is lower than 100 degrees. A reference point in our factory is after it drops below 80 degrees, almost five hours after hot blowing.
During the later stage of cold blowing, due to the large air volume, after stopping the absorption pump, part of the gas will flow along the acid pipe to the circulating acid tank, causing the tank to splash acid, so a blind plate should be installed on the acid pipe.
This post was last edited by Panzhi on 2013-11-4 11:53. This post was edited very early. Looking back now, there are many inappropriate things. Fortunately, there is now a design for the absorption tower bypass.
The original poster has an opinion, and it is something I have been thinking about. Inertial thinking does account for a big part. Hot blowing usually starts with the 1.4-layer inlet temperature of 440 degrees until the sulfur dioxide content of the exhaust gas is less than 300 ppm. In the later stage of hot blowing, when the incoming suction temperature is less than 100 degrees, someone above said that the dry suction pump can be stopped, but in order to ensure that unforeseen circumstances occur, it is better not to stop, including the magnetic ring and ball bow in the tower, which are resistant to Acid cement, etc. are all subject to minor damage, but there is still a problem. The drying pump cannot be stopped at all, and the acid concentration must be ensured to be above 31.5%. It is better to rely on underground tanks or acid tanks to replenish the acid. In some places, the process is not like this. It is better to restart the first suction pump, including the air leakage problem in the first suction. On the one hand, it will accelerate the service life of the first suction tower. The air leakage will turn into acrylic acid, and the catalyst will enter moisture. Isn’t it a wasted hot blow?
It was written wrong above that the dry acid concentration should be above 91.5%, haha
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