5 replies to this topic

[HW. Toh]

Hi, i am sizing a heat exchanger and was wondering which material of construction is best suited for the heat exchanger which handles high operating pressure and temperature? Besides that, how do i explain why heat exchangers must be designed with excess tubes using exchanger design of shell diameters of 8 inches and 32 inches for the discussion ? Thanks in advance.

[Iron_Ringer]

Hi, i am sizing a heat exchanger and was wondering which material of construction is best suited for the heat exchanger which handles high operating pressure and temperature? Besides that, how do i explain why heat exchangers must be designed with excess tubes using exchanger design of shell diameters of 8 inches and 32 inches for the discussion ? Thanks in advance.

Stainless Steel is best suited to high temperatures and pressures. However, this decision should be based partly on the corrosive resistance of the materials. Depending on the pressure, temperature, or conditions it may be OK to use carbon-steel. I do research work in the Nuclear field, and everything here is made out of S.S. 316 (I think)....

edited to add: I am also a student, just to let you know.

[Art Montemayor]

HW:

As a potential future engineer, now is the time to start practicing what engineers are supposed to excel in: being specific and detailed in their explanations and descriptions – and doing it clearly and accurately.

You fail to state what you mean by “high operating pressure and temperature”. Poets are expected to describe things qualitatively; engineers are expected to cite specifically what pressure and temperature they are referring to. We don’t know what you consider as “high”. Also, what kind of “design” are you generating – a process design or a mechanical design?

Why are you intending to explain the subject of excess tubes in 8 and 32-inch diameter heat exchangers? Again, what is your idea of “excess”? There are never any “excess” tubes included in my heat exchanger process designs and specifications. There are contingent quantities of tubes – but that is a totally different intention. A contingent quantity of tubes is a quantity that is expected to be needed – at some time or another, for different reasons – and is not specifically identified as to need only because there isn’t enough basic data available or there isn’t enough information or time to gather the specific reasons at the time of the specifications or design. Engineers do not guess; they calculate with specific information as data and expect to generate specific answers as to what will work efficiently, economically, and safely.

In order for us to really help you resolve your problem, you should furnish us with specific, detailed, and accurate information. Otherwise, you force us to guess. If our guesses are good enough for you, let us know.

[CS Kang]

I think what HW wants to ask is regarding Heat Exchanger designed with excess tubes and by comparing heat exchanger of one with shell diameters of a 8 inches and the other of 32 inches, what would be the difference in the number of excess tubes needed for the heat exchanger? Also Note that 32inch and 8 inch are simply just examples. Furthermore, how does the shell life has to be taken into consideration for the number of excess tubes required for different shell diameters? I am also a student consulting the professionals and fellow students. Any help will be greatly appreciated!

[Art Montemayor]

CS Kang:

What you think HW wants is one thing. What he/she wants may be totally another thing. This is not a guessing parlor or an Internet Chat Room. This is a Forum for serious Chemical Engineering students who are hard at work in trying to compete for a very expensive and taxing university degree in probably one of the most difficult and competitive study programs on this planet. This is a serious and expensive undertaking – both in money and effort spent. We don’t need to waste this valuable time just guessing or speculating. We can get right to the core and subject of the matter if we get specific and accurate descriptions of exactly what the problem is so that we can be of help. For that, we are asking all students to do their share of the work: be specific, detailed, and accurate in your queries. Otherwise, you are cheating yourself from obtaining help from we professionals who are simply trying to furnish you with the best help possible (and it is totally free from us!) to achieve your goals.

This communication problem that most students have is NOT about a language barrier. That is a cop out and an excuse. It is all about not spending enough time in organizing your thoughts and your logical thinking and writing it down correctly and accurately such that it can be totally understood by your readers correctly and without raising any questions or doubts. Now, what is so hard about that?

The reason I stress these points is because they are probably the most important engineering lesson that any Chem E student is going to learn in their entire professional life. If you don’t learn NOW how to communicate correctly and accurately, you will suffer the remainder of your professional life and you will fail miserably as an engineer. You are destined to be the expected leaders of your respective societies and communities – both industrially and socially. How can all those people that are expected to follow your leadership do what you want them to do if they can’t understand what you are writing or saying?

If you are giving examples, then STATE that they are just examples. Do you expect your readers to also read your mind? Don’t hold your breath waiting for that to happen. As an example of bad communications and writing, just look at your statement: “Furthermore, how does the shell life has to be taken into consideration for the number of excess tubes required for different shell diameters?” Forget about the spelling errors; just concentrate on what you are asking in this question. I don’t have the slightest idea what you specifically are asking for. If you mean to say that you suspect that the shell life of a heat exchanger is affected (reduced of expanded?) due to the shell having more tubes than are normally required, then say so. Don’t simply assume that I know that is exactly what you intend to say. I (and all other readers) don’t have the privilege of knowing what you are thinking. We are at the mercy of what thoughts you write down in order to know them.

I hope this explanation shows you and other students the importance of communicating well and accurately and that it helps you to better understand what is expected of you in your future career. Good commuications - just like thermodynamics and other Chem E studies - takes a lot of hard work and effort to dominate and to resolve problems. But the advantages you have in dominating good communications is that you obtain the effort of others to do work for you - now that is a lot better than you doing all the work! And THAT is smart engineering .....

[CS Kang]

Sir Art Montemayor,

my apology to you. I must admit that I did not specify my question to you clearly. To tell you the truth, actually I am doing a polytechinc assignment with Han Wei (HW) and there is this particular question which we are trying hard to answer. After taking a second look at my question, I must say it's not detailed and straight to the core for you all to answer. I will improve my communication skills and hopefully I can give a clear question next time. Thanks for enlightening me and I am looking forward to learn more from you sir.