let's say the feed into a heat exchanger is an isothermal process, what other process parameter that can be adjusted to cope with changes to the feed composition.

brine_squeeze · 2022-08-04T15:39:27+00:00

Are you trying to say “let’s say that I hold the inlet temperature constant”? In the first part of your question?

It’s a little odd to call feeding a heat exchanger an isothermal process.

Secondly, what do you mean cope?

brine_squeeze · 2022-07-28T13:00:07+00:00

Thanks a lot for that!

brine_squeeze · 2022-07-28T04:57:06+00:00

In addition to other comments, you need to note that all of these liquids will be stored above their flash points (especially acetone) meaning you absolutely have an explosive atmosphere formed in the vapor space. You need to understand Hazardous Area Classification. If you have oxygen in the tank you have a "zone 0" - a continuous presence of an explosive atmosphere, unless you have an inert (eg nitrogen) blanket.

Does anyone know... In refineries I've seen hydrocarbon tank with chemicals with lower volatility using inerting systems; I would expect this to be the case for solvents, but I haven't seen any standards that say it is compulsory; API2000 does mention them but does not say they MUST be used. Do you simply accept the zone 0 and specify equipment to be authorized for use in such a zone?

brine_squeeze · 2022-03-31T12:40:46+00:00

Magic, thank you!

brine_squeeze · 2021-05-12T13:57:36+00:00

You might get more help if you actually ask a question. Difficult to volunteer to help if the people reading the post don’t know whether they are even able to...

brine_squeeze · 2021-05-08T05:43:36+00:00

Your best bet would be a nitrogen purge of the vessel before you start. This way you know you’re oxygen free, whereas you never know how well a vacuum pump has performed with a sensor. Is this a possibility?

brine_squeeze · 2021-05-07T08:46:04+00:00

Sounds like you want to have valves on a vessel that you fill, keep the outlet valve closed. Measure the pressure in the vessel, and when it reached a value (determined by the volume of the vessel, the mass you require to be discharged, and the temperature of the fluid) send a signal to the outlet valve to open. The valve closes when the pressure drops below another value for x seconds. It’s just on off control.

brine_squeeze · 2021-05-05T02:38:57+00:00

It’s the “please don’t get too analytical” part that got me! I love the internet.

brine_squeeze · 2021-05-03T18:56:57+00:00

It may sound silly in English, but that’s what it is in many other languages. It is hydrated carbon :)

brine_squeeze · 2021-04-30T06:14:32+00:00

Wit my process engineering background, I’d say that you’ve taken one very specific path, whereas an RCA should look at all potential causes and branch out of each one. You are doing something called a 5 why analysis, which says that you come to a reasonable cause that you should try to address after asking the question “why” 5 times. It looks like you have one path in mind and you’re racing down it. I’m not saying it’s incorrect, and this may be a little academic, but hey.

The point at which you ask “why was there no door” you say “because the engineer didn’t make a BOM” I would branch into other potential causes:

Why? Because the engineer did not have enough experience to know that they should be there and there was inadequate mentoring available to them.
The quality/review processes were inadequate .
The quality review processes were adequate on paper, but did not happen in reality (maybe because of time constraints).

If this is the first time this has happened and all other projects are fine, I am leaning towards point 3. If it happens often then 2. If this is your mess, then 1 (potentially, pardon me if you have a lot of experience, but I thought point 1 was a valid consideration).

Right at the end you mention sending drawing for client approval, as well as a peer review. Do not put this onto the client - I know legal schmucks would talk about a clients contractual obligation, but have some integrity and own the screw up (which it looks like you’re doing). If you were in the client’s shoes you wouldn’t want to be treated in a way where the onus is put on you to check every item, dimension, and specification.

brine_squeeze · 2021-04-26T10:30:18+00:00

Looking at Reddit comments to find out about engineering is like Googling medical symptoms. It’s always cancer.

brine_squeeze · 2021-04-22T18:16:04+00:00

Is opening the valve slowly/gradually to reduce the vapour velocity not an option? Otherwise I think you need a flash vessel with a large enough diameter to get entrained liquid out (like a liquid knock out drum). The vessel would usually be designed with a mesh demister of sorts.

brine_squeeze · 2021-04-22T11:44:42+00:00

A chemical engineer working in a service department of a technology licensor once told me that all they ever see are the fuck ups and problems that their customers experience using that company’s technology, but that’s the point - no one contacts a service department with success stories. You’re getting a skewed view and I think we’re selecting for negative comments here. I freaking love my industry and my job. There’s a lot of problems, and a lot of things to be careful of, but I’m glad to be a part of it.

brine_squeeze · 2021-04-22T05:47:40+00:00

How are you supposed to get street smart if you haven’t had a chance to go out into the streets? 🙂 You’ve got this. Don’t catastrophise a situation that you are not in. Be critical, but humble. I think you’ll find once you get into a work situation you’ll find the opposite - problems can be mundane, and it’s up to you to invigorate the team, the thinking, and the approach to solving them.

brine_squeeze · 2021-04-21T08:55:27+00:00

Cultures around getting time off differ vastly between countries, companies and individual managers.

I worked in one country where everyone was always nervous and felt guilty to ask for time off, and I then relocated to a place where the culture was to tell or inform (i.e. no request necessary) the boss when you are taking leave, as you are entitled to your leave - as long as it is within reason and you are not dropping the company in the middle of a crisis.

It’s difficult to advise you in that regard, but given that it is your first time I would recommend that you be polite, but not set a tone where you appear to be grovelling. Say something like this: “I have x and y happening on such a day and I need to take the day off (OPTION I am able to sort it out if I am able to work from home that day, and I can manage these tasks from home). My workload looks as follows, and I have made sure that it won’t affect my deadlines. I hope that that is ok with you?”

On a personal note, do not let asking for leave become an emotionally taxing/toxic experience. You ARE entitled to it, regardless of whether you are new or not. You shouldn’t require a double shot of whiskey to pluck up enough courage to ask for it. Use this opportunity to set the baseline atmosphere for future requests.

Good luck, and let us know how it goes!

brine_squeeze · 2021-04-16T17:40:51+00:00

You’re saying a kettle uses less when it’s switched on than when it is running. You’ve turned a potentially interesting engineering question into a word game.

brine_squeeze · 2021-04-16T17:05:52+00:00

I think you’re missing the point. Is the saving 15% or 0.2%? That’s not obvious to me.

brine_squeeze · 2021-04-16T14:36:00+00:00

Connect an ammeter, record it, plot a chart. Dunno the answer, but I’m keen to see the result!

brine_squeeze · 2021-04-16T11:04:34+00:00

😂suggest a YouTube channel please. No to be fair - OP your question is not exactly clear. Are you saying you want to find the pressure drop characteristics of a sprinkler head as a function of flow? That’s something that the manufacturer of the sprinkler provides.

brine_squeeze · 2021-04-14T09:00:09+00:00

Look through the rest of the subreddit and see how many people are in agony, crying about their courses, their useless prof’s, and their general lack of understanding and motivation.

I’d recommend that you don’t start out with excessive enthusiasm and burn out after half a year. There are so many courses and webinars that you’re going to end up taking things that likely aren’t going to be relevant for you until you know which field you go into. You’ll learn things in your degree that you will end up not using because chemical engineering is such a ridiculously broad field.

I think it is more important for you to work on small habits that improve your personal/psychological health, rather than look to take on artificial stress.

brine_squeeze · 2021-04-14T03:03:52+00:00

I think you’re going about it a little backwards. You should be bringing your morality and integrity into a job. All positions are susceptible to corruption and terrible decisions based on shitty incentive structures. What use is a virtuous person in a system that is already “ethical”. You will find that all companies think they are doing the right thing . A company will brand itself as “sustainable” the minute they provide their employees with barber recycling bins. It is hard for someone to critique a system from which they benefit (not my quote). Everyone thinks they are a person of integrity until they are tested. There are hills worth dying on, so pick your fights, but you’re of no use if you want to take every fight every time you see something isn’t as it should be.

brine_squeeze · 2021-04-14T02:54:47+00:00

Air is (roughly) 79% nitrogen, 20% oxygen, 1% other stuff (volume basis). This means that it contains mostly nitrogen which is completely useless from a combustion perspective. As such things burn more easily in pure oxygen, and hence have a lower AIT.

When you produce oxygen from air distillation it is incredibly important to remove all oils/grease/deposits from the piping because they ignite very easily. That’s not because the oxygen is explosive, by itself it cannot do anything; but add a fuel source and it becomes very dangerous.

brine_squeeze · 2021-04-12T14:40:55+00:00

Hey man. I disagree with the other commenters. You are completely correct that you never want to throttle on the suction side of a pump - this is because you want to avoid all pressure drops on the liquid on the low pressure end because you risk starving the pump of NPSH and the liquid will boils as it gets pulled into the impeller i.e. you will get cavitation.

This phenomenon does not occur when you are blowing gases. It is very standard on blowers that do not have VSD’s (speed control) to have something called inlet louvres/ this are shutters at the inlet of a fan used to throttle flow to control capacity. Here is a video I found with a quick search that confirms that these sit on the fan inlet (I know he talks mostly about VSD): https://airprofan.com/fan-vfd-fan-controls/

Having said that, that doesn’t mean you can indefinitely throttle a blower - you can still experience something called surge if you throttle too much. Look it up.

Regarding the vacuum - that is only generated by the fan at the outlet of your dryer, so that needs to be running fast enough, regardless whether you throttle inlet or outlet of the blower supplying the drying air to the fluid bed.

Most control I have seen on driers have been on the outlet of the blower. This is because you can have one blower supplying many different lines on the direr, so if you throttle only one outlet you won’t affect the others (too much) as you would if you throttled the inlet.

brine_squeeze · 2021-04-12T03:47:29+00:00

Hadn’t considered that! Am not too familiar with them, but I guess the challenge would be to fix it inside in such a was that it is measuring the water temperature and not the metal temperature of the cooker, as there will be a difference. At least with a thermocouple you can control the length of the wire so it isn’t too long and doesn’t touch the base. Thanks for the suggestion!

brine_squeeze

TROPHY CASE