Do you have any problems with regeneration tank spray?
Thread Content
We use DDS-01, add auxiliary materials, and add soda ash. But sometimes when the alkali solution is pumped into the lean liquid tank, the regeneration tank immediately reacts violently, starts bubbling, and then overflows in large quantities. Sometimes when the poor liquid recovered from the sedimentation tank is recycled, liquid leakage will occur. Sometimes it is very serious, causing the loss of lean liquid and harming the environment. It troubled us a lot. Has this situation ever happened in your factory? Who knows why this situation occurs, what kind of reaction it is, and how to avoid this situation from happening. Your help is urgently needed.
Does the author mean that there is too much bubble in the regeneration tank or that the injector sprays back? According to the poster, my personal feeling is that the temperature of the solution should be too high and there are many side reactions. If possible, analyze the sodium thiosulfate content in the solution. In addition, when recovering the returned liquid, it is best to cool it down before replenishing it into the system. Always pay attention to the overflow situation of the regeneration tank, ensure that the solution is about 5-10cm away from the overflow weir, and maintain a certain height of foam layer!
It shouldn't be a temperature issue, because sometimes it does when the recovery fluid is pumped in. The temperature of the recovered liquid can be cooled.
This kind of thing has never happened before. I think it may be a problem with the solution components or the liquid preparation process. How long has this phenomenon been going on?
It's been several years, anyway, it's been off and on, and sometimes it's been serious.
When the temperature is high, the sodium thiosulfate content will be high. In the past few years, our factory could not replace the solution due to environmental reasons. The semi-water gas primary desulfurization regeneration tank had excessive flying bubbles. The composition of the bubbles was analyzed and it was found that 95% was sodium thiosulfate. The next step was to lower the solution temperature, which is now maintained at about 32°C. If there is a chance, it is better to replace the molten sulfur and return it to the liquid. If there is no chance, lower the temperature as much as possible. Add air saponification at the same time as the last stage of cooling, and the effect will be better. Furthermore, the regeneration pressure must be controlled well. On the premise of ensuring hydrogen sulfide, it is recommended to reduce the amount of solution circulation!
The liquid return must be cooled, and most of them use natural cooling. If a small cooling tower is used for cooling, the sodium sulfate content will be very high, and the equipment will be seriously corroded. Are you using a partition heat exchanger? Conservatively speaking, the temperature after natural cooling is still around 50℃. If not, you can test it and see! We have controlled the return temperature of the molten sulfur at 90°C. After the 4-level natural cooling and settling, it was replenished into the system. At this time, the temperature was about 60°C! Furthermore, the liquid return temperature must be controlled. Let’s talk about this first, and we’ll discuss it later if you have any questions!
I have used a variable-removal DDS catalyst, but I don’t know much about the semi-removal DDS-01. It is said that it has better oil resistance. DDS catalyst aerobic bacteria can withstand the maximum temperature of 45°C (according to people from Boyuan). What is the current resistance of your desulfurization tower, how much is the daily ammonia production, how much is the imported and exported hydrogen sulfide, and how many tons of sulfur are produced daily. Learn more about it, and then analyze and discuss it together!
3 Tannin extract solution regeneration tank leaks 3.1 Cause analysis The total amount of tannin extract solution in our company's semi-removal system is 500 m3. The tannin used is raw tannin. When preparing the solution, the aging of the tannin is the most critical procedure. Poor maturation of tannins is the main reason for leakage of regeneration tanks. The reasons for poor ripening of tannin extract are:: (1) The steam pressure of the aging tank is low and fluctuates greatly. ； (2) The compressed air pressure is low and there is oil and water carrying people ； (3) Due to the limitation of the aging time of tannin extract, the solution preparation time is long (about 10 d). The pre-ripened tannin extract re-polymerizes in the equipment, restores its gelling properties, and generates foam. 3.2 Solutions (1) Ensure the glue is well matured, strictly control the steam and air pressure, strictly prevent impurities such as oil and water from entering, and strive to fully mature the raw tannin glue. (2) The temperature of the tannin solution prepared in the equipment should be maintained at 40-45°C, and it should be continuously blown with air to prevent it from re-polymerizing. (3) The concentration of tannin solution can be gradually increased as the production load increases. (4) Use high-quality cooked tannin extract. Through the implementation of the above measures, after the tannin solution prepared in recent years was put into the system, there was no sump phenomenon again. Even after a large amount of solutions were prepared after the system was overhauled, there was no sump phenomenon. 4. The oxidation regeneration tank was seriously overflowing and sulfur recovery was difficult. In 2003, the desulfurization system of our company experienced severe overflow in the regeneration tank for a long time. The tannin solution became dirty and dark, the regeneration was very poor, and sulfur recovery was difficult and basically stopped. If no measures are taken, suspended sulfur will inevitably rise and eventually block the tower. 4.1 Cause analysis This phenomenon is mainly because the sulfur foam is too stable and not easy to break. The foam keeps rising and cannot form a paste layer and overflows into the intermediate tank. As a result, sulfur recovery cannot be carried out and suspended sulfur naturally rises. The reason why the sulfur stability is too strong is that certain substances enter the system and accumulate in the tannin solution. After reaching a certain concentration, they adhere to the surface of the sulfur foam, increasing the strength of the foam and thereby increasing the stability of the sulfur foam. The sources of these substances are: (1) The volatile content in the semi-aqueous gas produced from gas production exceeds the standard. This is mainly because some organic substances enter the semi-stripping tower with the semi-aqueous gas and are absorbed by the tannin solution. ； (2) During equipment maintenance, some oil substances enter the tannin solution as the equipment is put into operation. ； (3) The tannin extract is not completely matured and re-polymerizes in the solution to restore its gelling properties. 4.2 Solutions (1) Reduce the volatile content in semi-water gas. Coal types with low volatile matter content can be used ； Or lower the operating temperature of the gas generator to reduce the volatile content in the produced gas. (2) Clean up the oil stains during equipment maintenance and try to prevent oil substances from entering the system. (3) Check the ripening of tannin extract. If possible, cooked tannin extract can be used instead of raw tannin extract. (4) Add defoaming agent to the regeneration tank to accelerate bubble bursting. However, the time for adding defoaming agent should not be too long, and the amount added should not be too large. 4.3 Effects Through the implementation of the above measures, from October 2003 to the present, there has been no serious leakage in the oxidation regeneration tank. The above excerpt is from the first issue in 2005 by the authors; Yang Ruihua, Li Haihong