An old engineer’s personal experience (given to students)* Software simulation friends)

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An old engineer’s personal experience (given to students)* Friends of software simulation) I recently read a relatively good article, which was very inspiring. I hope that everyone will not forget our roots while working hard in software.: Basic knowledge of chemical engineering, let alone our basic tools: Hand calculation. (This article is a repost) Experience on using process simulation software! I would like to share with you the mainstream process simulation software, ASPEN, HYSYS, and PROII. I am using all of these. During the gradual use process, I fell in love with HYSYS, although the current level is not very good. I myself am involved in air separation and LNG, and I work in an industry factory. When I first came into contact, I was just trying to figure out how to make software and find information, which was very impetuous. As time went by, I deeply realized that learning * These tools mainly focus on basic knowledge and hands-on skills. When I first calculated the process, my basic knowledge was not very solid, which had a great impact on me later. I also want to focus on these two points. 1. Basic knowledge: Most of my friends here, like me, have been working for several years. There are not many senior engineers because they don’t have access to the Internet, and many of them don’t know how to use these software. Most of my friends from universities here are graduate students. They want to learn software in order to write papers or something like that. These are not important. What I am trying to say is that for those of us, the basics are very important. Here I tell two stories: Two masters, one from Zhejiang University and one from Xi'an Jiaotong University, both asked me some questions about the simulation of air separation processes. They should be said to be very knowledgeable people. At least in terms of basic principles and basic knowledge, I think they are better than me. However, after I looked at the ASPEN calculation model they established (they wanted my help to look at it), in fact, many of the mistakes are basic. One was about how to obtain the numbers on the theoretical plate of the tower. One asked me that his program always made errors. When I took a look, it turned out that the compressor and expander models were not running during his process calculations. Efficiency parameters are not given. What about myself? It turns out I just learned * This is also the case. Later I thought of two solutions. One is that I spent about a month manually calculating a conventional air separation process. 2. I calculated each unit model separately, such as towers and heat exchangers, and various controls, such as circulation, settings, adjustments and other controls in HYSYS. After doing these two things, it will be very helpful to me in the future. Especially useful for finding problems. 2. Be more hands-on! It's easy to say but difficult to do in practice. It takes a lot of patience to do a lot of calculations, especially when you feel you understand everything. There is a lot to learn here * Information is a good study for everyone * platform, but if there are too many, it will be harmful to everyone. Many young people are busy looking for information every day. Frankly speaking, how many of them have read it carefully? And have you ever done it? How many have you done? What problem was found? I used to write some HYSYS information myself. To put it bluntly, it was just my notes, but I stopped writing it later. The reason is that I don’t have time to write this myself, it’s very tiring. My experience is that it is easier to learn by yourself. If you really have to write it into a book or tutorial, it still takes a lot of time to explain the problems in it clearly. I am not as good at this as the snowflutter moderator. Therefore, I still admire other tutorial writers on the forum. Be more hands-on. Having said so much, I feel so wordy myself. Everyone, please stop laughing. Add the last point: The equation of state should be viewed as a focus. The state equation in the simulation software is not omnipotent, and there are still problems in simulating the actual device. If you are not very sure about this yourself, it is best to ask more experienced engineers or people with experience. For people who work in the chemical industry, this may be something they have a deep understanding of. My experience is too important. Put it this way. For example, if ASPEN PLUS is used to calculate the spatial separation, then the binary interaction coefficients of O2, N2, and AR need to be regressed and compared. When the air pressure is higher than 20 BAR, the gas-liquid balance parameters need to be corrected. When calculating some high-pressure critical points, you don’t even believe the enthalpy point data calculated by ASPEN PLUS. It is obviously wrong. The same is true for HYSYS. In the correction of the binary interaction coefficient, HYSYS calculates mixtures with high H2 content. The state equations are different and the errors are also different. For the same parameters, I used a higher version of HYSYS to calculate and the calculation error was significantly reduced. I don’t know if you have noticed that HYSYS2004 and later versions have a check box for H2 in the equation of state options, which is a correction to the critical temperature and pressure of H2. In the past two days, I have been recalculating a mixture containing high H2, and the calculation results of HYSYS2006 have improved significantly. The error is reduced. What needs to be explained here is that the so-called error reduction is based on the comparison of process parameters from many foreign countries. I hope these words will be of some truth to my friends on the forum. When you think you know everything, in fact you still don’t understand a lot. When you think you still don’t understand a lot, in fact you already understand a lot.