The heat transfer efficiency of the transition scale-up tube heat exchanger in a newly built sulfuric acid production plant using pyrite in Tongling does not meet the required standards

Have you been to this factory in Tongling? I heard that there are two issues with their conversion unit: 1) The heat exchange area of unit 3 is insufficient, which may be related to the airflow distribution; 2) There is resonance between units 2 and 4, and the situation improved a bit after two rounds of repairs. For a while, it was as if there were planes flying there

I plan to go there around the 10th of this month to take a look.

Please review it and share your analysis results.

I share a similar view with the moderator. Our company has several sulfuric acid production units; three of them use scaling tubes, while two were designed by the manufacturers themselves. In all of these units, the temperature of the incoming gas is too high. As for another unit, which was designed by our company itself with a K value of 22, there are no problems with it

One of our senior engineers, after reading this discussion, said that if the purification effect is good, it’s indeed possible to reach 30; but if the purification isn’t effective, it will be difficult to even maintain a level of 10. He has worked on several sulfuric acid production systems, and there were no problems with those

This post was last edited by in the blink of an eye on 2013-10-17 at 16:33. In our plant’s sulfuric acid III system, the conversion value during the initial operation phase (when the conditions should be clean) was lower than the designed value; the K value was around 22, while the designed value is 30.5!

I have friends who work at that company; I’ve heard about this matter. I’ve also seen scale pipes at a chemical machinery factory. Those who work with chemical engineering machinery know that expansion tubes essentially serve to increase the heat exchange area. However, for thick-walled tubes such as those used in flue gas heat exchangers, the increase in heat exchange area is limited; as a result, the heat transfer coefficient may not increase significantly. Moreover, a high gas flow rate is not necessarily favorable for the heat exchange mechanism of expansion tubes – this is my reasoning, and it seems to be similar to what others have said ； This is how I make decisions when working on engineering projects (I’ve already done this once); what exists is reasonable. Since pipe heat exchangers have been in use for so many years without any problems, why take risks? Moreover, since the same gas velocity implies the same number of pipes, it comes down to the length of the heat exchange tubes. The high point in a vertical heat exchanger poses no problem, so this factor can be disregarded! Haha! Another point is that, as can be seen in an instant, in order to maximize profits, merchants tend to cut corners. It is recommended that all property owners who have the technical skills opt to carry out the work on-site! To the best of my knowledge, heat exchangers for 800,000 tons of sulfuric acid or less can be manufactured on-site, in order to minimize any risk of cutbacks in quality!

The friend on the 9th floor made a very reasonable analysis!:handshake :lol

:Handshake is great! Give it strong support! Learn from all the teachers!* Thank you! Those who are capable should speak up!

The scaled-tube heat exchanger is a patent owned by South China University of Technology, and production rights have been granted to Zhanjiang Zhongming Chemical Machinery Engineering Co., Ltd. I used it in a system with an annual capacity of 80,000 tons at my company back in 2002; it wasn’t produced in Zhanjiang, but by another manufacturer in China. I’m not sure about the quality of those produced in Zhanjiang. At that time, I contacted the design institute numerous times regarding the issue of excessively high heat transfer coefficients inside the pipes in the first and second stages of the design; however, since the chief engineer in that design department was a top expert in the field, he ignored my requests. It was only under my persistent insistence that the heat transfer coefficient inside the pipes was set at 22. After one year of operation, problems arose with the heat transfer efficiency of the exchanger, resulting in the temperature in the second stage reaching almost 600 degrees, and the auxiliary control systems failing to function properly. In my opinion: 1. From the perspective of heat transfer design, this technology is feasible. However, in sulfuric acid production, the existing domestic purification standards are difficult to meet the requirements. During the production process, the dirt value experiences an unpredictable change that exceeds the designed upper limit, resulting in the aforementioned problems. 2. The principle of this technology is as follows: To improve the overall heat transfer efficiency in the sulfuric acid conversion heat exchanger, it is necessary to increase the heat transfer coefficient inside the tubes (which represents a limiting factor). This technology achieves an increase in the heat transfer coefficient by disrupting the flow stagnation layer on the tube walls through the use of scale reducers. 3. Personally, I still think it’s better to use traditionally designed insurance policies, as heat exchangers have a higher safety factor