Hello,

I'm working on a complex thermodynamic problem: simultaneous chemical and phase equilibrium. I need to express the chemical potential of each species in the liquid and vapor phases to minimize Gibb's free energy in the system.

Long story short: I can't use an EoS (for reasons that I will not write there). I've decided to go with an activity coefficient model to describe the liquid phase. I've chosen the UNIFAC Dortmund model since it allows me to work with complex molecules through group contributions.

How can I model the presence of H2 (there is no H2 group in the UNIFAC model) in the liquid phase? In other words, how can I calculate an activity coefficient for H2 and consider the presence of dissolved hydrogen to calculate the activity coefficients of other species?

Thanks!

I work at a sulfur plant and have been doing a bit of digging, so I'll lay out an overview.

Basically, our entire process is really simple. Sulfur gets pumped through screens with tiny holes that falls into forming water thus creating small sulfur prills. Said prills get dumped into rail cars via coveyor belts.

The firmung water we use returns back to tanks on ground level where it gets pumped out to get cleaned of fines and cooled in cooling units.

Here's where I'm having the issue.

The pH if the process water is in excess of 8.2, the highest I've seen it is 8.46. We do degas our sulfur so most of the SO2 is removed, ensuring our pH doesn't get too low due to SO2 creating H2SO4 (please correct me here and also on anything I'm getting wrong). I know alkalinity can contribute to scale formation, and we've actually seen that recently when opening our exchangers and seeing chunks of scale partially plugging tubes. There's also quite obvious scale going through our piping and sometimes getting into our prill.

Now, we used to pump sulfuric acid into the water tanks to bring the pH down. I've brought this up to management and their response was basically, "Oh, well we're not experts in sulfur chemistry."

I want to know if this is going to contribute to more scale formation and cause more issues, and what the proper course of avtion would be.

Any and all info is welcome, please give as much detail as you'd like, and correct me if I've got anything wrong.

I was wondering what people think of ASPEN and SuperPro designer as TEA/process modelling software.

Is there a gap in the market for something which does the following with a sleeker, more modern interface?

SuperPro Designer is flexible for bioprocess modelling, but doesn't have updated quotes (uses the CEPCI extrapolation from past quotes), doesn't have the labour intensity associated with different unit procedures embedded within the programme, doesn't have costs for loads of chemicals and is very scarce on carbon factors for materials and capex machinery (becoming more and more important in bioprocessing).

I can't even figure out how to properly zoom in and out of the PFD (I know you can manually resize the number of pages the PFD covers, but it's not the same).

It's great that the software has shortcuts allowing for easy navigation, but I would love it if there was some way the user could just use an API to grab the SuperPro Model's data, and write some code to iterate through the model and run sensitivities on anything they want.

I admittedly have less experience with ASPEN. But it is incredibly expensive. Do you think the deals the company sets up with the quote suppliers push the price up (if ASPEN has more recent quotes?)

I am a 22 year old plant operator that has been working in a carbon black plant for 2 years now. I have no college degree, I have been doing some research with finding an online school to further my knowledge. I have found quite a few schools online but, just need some direction which school is worth the money and I can get the most out of it. Anything helps!

Hey Reddit! Could you please give any tips on working in the plant as a younger engineer? One challenge I've experienced is working with extremely experienced operators who are 2-3x my age. It feels jarring sometimes to have more percieved power than people much older me. I try to remain as humble as possible, but naturally I am still met with friction sometimes.

I'm open to any advice on how to better navigate this dynamic. I would love to grow and learn from any personal stories you may have as well. Thanks!

How can i make the most out of college as a current international freshman in the US? How has the maarket been for international graduates? While networking should i focus on engineers or should i branch out to other majors as i think chem engineering is very broad work wise. Any advice would be appreciated, thanks.

I just got admitted to the college’s ChemE undergrad program. It’s pretty prestigious from what I could gauge on the internet. Would love to hear more about it experience and career wise!

I was in the middle of studying for the PE from the learn chem e website and it now says the connection is not private and I can’t login. Anyone else having this problem?

I recently got a call back for an internship to take place over the summer but I have no idea what to expect as this would be my first real in the field experience, what questions should I be prepared to answer, along with what are some questions I could ask them to make me stand out?

So I have this vessel at work, it's a batch vessel, you dump things in it, heat it up, then transfer it out. Easy. I wanted to develop a model that estimates the time it takes for the contents in the vessel to reach the final temperature.

The way it currently heats up is with direct steam injection (sparging). There is no steam being condensed overhead, the vessel is closed and well mixed, so no heat loss or gradients.

So I looked at the general energy balance equation:

dE/dt = min*(hin +vin^2/2 +gzin) - mout(hout +vout^2/2 +gzout) + Q - Ws

v and z are kinetic and potential energies, but there's nothing about that in the system. There's nothing coming out of the system either. No work shaft, the energy from the agitation isn't all that much. And the only heat transfer is from the steam injection, not a steam jacket. So I'm left with this:

dE/dt = min*hin

And I can rewrite the energy term to be:

mass of material (kg) * specific heat capacity (kJ/kg*C) dT/dt = mass flow rate of steam (kg/s) * enthalpy of steam (kJ/kg)

I can separate variables and integrate to give me:

time to heat (seconds) = [mass (kg) * cp (kJ/kg*C) * (Tfinal - Tinitial)]/(mass flowrate of steam (kg/s)*enthalpy of steam (kJ/kg))

This model gave me successful results and people liked it. But now, people are asking me what it would look like if the vessel was heated by both sparging and steam jacket.

At first I thought it was easy, I would just add Q heat transfer. I looked at Perry's Heating and Cooling of Vessels, and it reads this:

Coil-in-Tank or Jacketed Vessel: Isothermal Heating Medium ln (T1 − t1)/(T1 − t2 ) = UAθ/mass*cp

θ being time, T1 being the temperature of the steam (jacket), t1 being initial temperature, t2 being final temperature. But it looks like this was done after the integration, without it, it would be Q = UA(Ta-T) Ta is temperature of surrounding medium, aka the steam in the jacket.

So I thought ok, let me go back to the overall energy balance and include Q this time:

dE/dt = min*(hin +vin^2/2 +gzin) - mout(hout +vout^2/2 +gzout) + Q - Ws

dE/dt = min*hin + Q

mcp dT/dt = min*hin + UA(Ta - T)

dT/(Ta-t) = [(min*hin + UA)/(mcp)]dt

-ln((Ta-Tfinal)/(Ta-Tinitial)) = [(min*hin + UA)/(mcp)]t

t = - [(mcp)/(min*hin + UA)]*ln((Ta-Tfinal)/(Ta-Tinitial))

Does this look right? Cause when I try to do calculations on it, I realize I can't add min*hin + UA together. The units end up being C/s + s^-1. But I don't know what I did wrong.

2025 Chemical Engineering Compensation Report is now available.

You can access using the link below, I've created a page for it on our website and on that page there is also a downloadable PDF version. I've since made some tweaks to the webpage version of it and I will soon update the PDF version with those edits.

https://www.sunrecruiting.com/2025compreport/

I'm grateful for the trust that the chemical engineering community here in the US (and specifically this subreddit) has placed in me, evidenced in the responses to the survey each year. This year's dataset featured ~930 different people than the year before - which means that in the past two years, about 2,800 of you have contributed your data to this project. Amazing. Thank you.

As always - feedback is welcome - I've tried to incorporate as much of that feedback as possible over the past few years and the report is better today as a result of it.

Hab herausgefunden, dass Armeedecken mit Schutzmitteln wie Eulan behandelt wurden. Kann man sowas effektiv mit einer Waschmachine auswaschen? Sind die Abbauprodukte auswaschbar?

Hi, next year I will embark on my Chemical and Biological Engineering journey in HKUST. In this school, I will have a chance to do a minor in Artficial Intelligence or Technology Management. Which one do you recommend. Is AI or business going to be the priority for a chemical engineer?

I have a GPA above 3.5, research experience, club involvement, and leadership experience. I’ve applied to many internships but haven’t been accepted into any yet. Is this normal? I’m in my third year, and it worries me a lot since this is my last summer, and I really want to secure at least one internship.

I really need all the help I can get for CPI TT

Im a junior chemical engineering student and I have been applying to so many internship positions this year but did not get any offer. I have a high GPA, went to career fairs, basically did everything you could do to land a job. Here I am almost February still applying but no offers. What’s the problem !! ( if you know companies that hire international students please let me know)

I have a huge concern whenever I work a problem because I'm not sure if my answer/methodology is correct. I know that one option is to go to the professor, but if you start having 20+ problems worked to bring to them, I'm sure it can be a lot.

I passed thermo 1, but for instance, we used the Koretsky Thermodynamics textbook. The textbook offers **no** answers for the problems, not even odd only.

I haven't been able to find a reliable solutions manual other than on that (possibly infamous) website that starts with a c, and now you can't find it on there anymore.

I know for certain balances, you can check yourself. But that doesn't seem to always be the case.

I'm a dual citizen with US-PH citizenship and I am currently a licensed chemical engineer here in the PH (where I also finished my degree)

I am looking to start my career in the US and am looking for some pointers on how to start

are exams like the FE and PE required and/or will they give me an edge when it comes to applying for a job?

what are other things I can do to increase my chances of getting a ChemE job in the US?

what sort of roles should I be looking out for? chemical technician, cadet engineer, etc.?

Hello guys,

at first I was bored on my pharma design job because it was a lot of layout development, equipment list, facility design and not deeply technical, especially no calculations.

However, I got a new project where I have to concept design a biological anaerobic process till packaging. Its something you cant learn with books because of specific restrictions our client wants. So there is a lot of problem solving how to do every process step absolute anaerobic and no one knows shit.

So Im hitting up DeepSeek, contact equipment vendors for feasability of our problem, puzzle everything together and propose the solutions to our client.

Its really interesting because I learn a lot. Later when we getting a basic design job, there will be developing URS, bid analysis, SAT etc.

The next career step in our company is Project Manager. However this isnt a classic PM job where you have only to talk with people, budgeting, scopeing etc. More that means that you have to write offers and be the first contact to the client, still doing the above mentiones tasks.

I dont want to go the management route and this seems like a interesting job. There is not only cranking out documentations (but there still are documentations to do), but a lot of client interaction and problem solving especially at the beginning or if the client still doesnt know what he wants after months discussing.

Its pharma design and going into a classical chemeng industry like chemical would break my neck because Im based in central europe. And I saw that its not so difficult to pivot to the pharma manufacturing site because they appreciate solving problems for GMP environment.

Someone in a similar position too and wants to exchange experience?

I am currently a junior in undergrad studying chemical and biological engineering in Colorado. I have tutor and research experience (currently a student researcher at an energy lab) but im struggling to find summer internships that will get me introduced to industry.

I am more interested in the energy/water/nuclear fusion route rather than oil/gas and weapons, but at this point I will take what I can get because beggars can’t be choosers. I am also interested in consulting and I feel like there’s a lot to do in that field along with energy.

I have applied to approximately 50-100 internships (with cover letters and all) throughout the year, but I’ve only gotten about 2 callbacks for interviews and I don’t believe I’ve got the jobs for those since I suck so bad at interviews due to anxiety. I probably spend about 5 hours a week on job applications during the school year. I had to take an application class for my major which really helped me prefect my profile but it seems to not get anywhere. I also have contacted many companies via email or phone introducing myself asking about internships available and I either get nothing back, rude responses, or told they have nothing available

My dad tells me I should have no problem getting one. I have been applying to places since August 2024 so I could get one early and especially since juniors are probably the best candidates for student interns. I got nothing last semester which was okay. But this semester the rejections are more frequent and even more nerve racking and frustrating. He even admitted that he thinks they are harder to get now than back in his day.

For reference, I am black (F22). I have a 3.79 gpa too which I thought would get me somewhere but seems like it’s not good enough for these companies. I’m not saying that the only thing I can bring to the table is my gpa but I thought it would be pretty important. I mean, they can’t expect me to have industry experience for a job title that is clearly entry level?? So mostly what I’ve got is good gpa, university lab experience, and clubs/organizations.

I know it’s early in the semester but I really want to secure one this summer. I’m scared that if I don’t have any industry experience, I won’t get a job after I graduate. Especially with the economy and the tech freeze which is bleeding into engineering as well (so I’ve heard). That is my ultimate goal. Im very scared of being unemployed and all my hard work was for nothing.

I have also even looked into other areas such as mechanical engineering, software engineering, biology, chemistry, ecology, sustainability, water, physics etc. I don’t just search for “chemical engineering internships”. I also apply outside of the state.

Any advice on internships and what you had to get through to get them? Are ChemE internships just more scarce in the Colorado area or am I just missing a lot of key points to secure one?

Is it normal to quit research after one whole semester? I feel bad because they already taught me a lot. But i dont really feel like doing it anymore either. I do not know how to tell them.

I have the option to start with a company after graduation for a project engineering role for around 95k starting . My main goal is to develope my professionally so that I can go in upper management. The reason for this is due to $. I like money to be honest. The role isn't an on call, not in middle of nowhere nor need 24/7 support. Is this a good way to go or should I take a more technical route?

I am a senior graduating in May with no industry internship experience. If I am struggling to find an engineering job would it be worth my time to apply to process operator/technician roles. Is this experience for 1-2 years something that would be useful and make it easy to work my way up ? Curious if anyone took a similar route

Is there a way to convert a chemical thats racemic into, lets say the d-enantiomer and if not what are some ways i could separate the two in a 50/50 mix of l-d. specifically for something like d-l phenylalanine.

Hi guys,

I hope someone with more experience or insight helps me.

I graduated from a Russel group Uni with a degree from chemical engineering and once I graduated, I looked for a job in the UK, due to me not having experience or a permanent residence (and maybe me just not wanting to live in the UK) I couldn’t land a job.

Through some help from some friends back where I was raised (a GCC) I landed an internship as a ESP (Electrical submersible pump) technician which then landed me a job as a field engineer for a servicing company in an ESP project. I beleive this is outside of my field as it pertains mainly to mechanical and electrical engineering. However, I am familiar with mechanical engineering concepts and have taken extra time to learn the electrical engineering concepts required to work on the ESPs.

Currently I am undergoing training in the yard by going over multiple sections of the pump system and working on them, I am expected to be doing this for the next 6 months until I get a gate pass.

Due to my nationality, I will only be given a 3 month gate pass to access the field and work there. Meaning that every 3 months I’ll have to apply and wait for a gate pass to be produced which could be inconvenient.

The pay is horrendous for an engineering role, 800 usd per month, the commute is also horrendous but I am doing this as I’ve been told the OT when I get into the field will make it worth it and once I gain experience my income will increase accordingly (as I pass assessments etc).

Thing is, I’m worried about wether what I’m doing has a future or not, is the gate pass being issued every 3 months and taking a few months to be produced going to be an issue? Is it worth sticking around and trying to make the most of this opportunity? Will this be a waste of my degree?

Any advise regarding my current situation would be highly appreciated.

hey, first time poster, maybe more in weeks to come. not going to lie, I was never even in high-school chemistry, but I can do calculations because I'm an engineer. my workplace used to have a solutions control specialist to maintain our chemicals lines. restrictions stop me from going into detail beyond the PH being anywhere from 2 to 12. so my question is twofold.

1. are there official requirements for someone to do this job?
2. can anyone tell me the liabilities involved?

I'll be reading a lot of EPA stuff today to try and answer this myself, but any assistance is appreciated.

Non ChemE here. We have a flow rate in SLPM and I’ve seen them in SCFH. How the hell do I convert this to an actual flow rate? I’m seeing multiple approaches but no official way that I can rely on.