Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: omid on 28/05/2009 13:46:28
-
hey guys please help me out and please explain me in much detail that why and how the industrial scale differ from laboratory scale? or at least give some source of information where ican find this information? please please please or i'll be in a big trouble [:-[]
-
Laboratory scale is small, because you only need enough to do an experiment. Plus labarotories generally don't have the facilities to produce things in bulk.
Industrial scale is much larger, because you want considerable amounts of the product to sell.
-
http://www.articlesbase.com/sales-articles/different-types-of-scale-548549.html
http://en.wikipedia.org/wiki/Weighing_scale
-
Oh, do you think Omid meant weight rather than size/capacity? I guess it can be taken both ways!
-
Haha, I had never thought about that, but now that you mention it, your answer might be what he was looking for. [:)]
-
i m nt he i m she (girl)
-
Apologies for my wrong assumption. [:I]
-
apology accepted
-
Is that in the sense of "scale up" from a lab scale synthesis to one suitable for chemical production for industrial use? If so, lots of differences, importantly exothermic (heat producing reactions) may not be able to lose heat to the atmosphere as fast in larger volumes, in which case they might overheat resulting in thermal runaway (getting hotter, reaction going faster, getting even hotter etc..) and also achieving good mixing is harder, there are more likely to be areas of the reaction vessel where mixing of reagents doesn't happen evenly so giving poor yield and sometimes unwanted side products (fluid dynamics - very difficult). I'm not a process chemist, I don't know much about this, but there's a few ideas to think about.
-
can some one please explain the same topic in more detail. i'll be indebted to that person for my whole life please.
-
Maybe if you're in the mood you can trawl your way through this book: An Introduction to industrial chemistry (http://books.google.co.nz/books?id=ZUZyCOIRPf0C&pg=PA9&lpg=PA9&dq=industry+scale+operations&source=bl&ots=M0ZSJ0hUO_&sig=yvPLXISP-HjgB7QmbwaIBIscIvQ&hl=en&ei=aMEhStCkD436tgP8hfyMBA&sa=X&oi=book_result&ct=result&resnum=6#PPA7,M1) [:)]
-
thank you so very much
although your book did not answer my question but still i'll be indebted to you for my whole life since you've already helped me alot.
in future if i'll have any problem with my studies you'll be the first person i'll contact.
thanks again chemistry4me [:)]
-
Well umm... I don't know why you're thanking me if your question was not answered, but if it makes you happy... [:)]
-
One more question related to this topic
how can we objectivly comment on any public issue by a scientific organisation.
the organisation I've chosen is GSK which has a branch in NZ as well so can you please hlep me about "what are the issues that can be objected in GSK"
or can you please give me some source of information.
-
Sorry, I've never heard of the organisation.
-
After a little Google,
Maybe:
http://www.doj.state.wi.us/AWP/Wisconsin/DocumentRequests/WI_GSK_Response_7th_RFP_to_all-03-05-2008.pdf
http://www.ll.georgetown.edu/federal/judicial/dc/opinions/01opinions/01-5391a.html
-
the link you've send me shows how GSK objects somthing but what i am realy looking for is that how can we object GSK rules and regulations about health and safety.or how can we object any public concern issue whic might arise from the work of the organisation.
-
i hope i am not boring you by asking too many questions.
i know you'll be thinking that i am a very dull student but belive me if you had monster tutors like mine then you'll realise my situation.
so please don't be annoyed
thanks again for everything.
bye
-
http://ussupplierdiversity.gsk.com/safetymanual/handbook.htm
found by a google search of "GSK health and safety rules and regulations", first result
OP, this would've taken you 2 seconds to do. You should strive to find your own answers before asking others [;)]
-
i am sorry to say but your link does not answer my question.
i think you should improve your reading and research skills since my question is asking something opposite to your answer OK [:P]
and as far as my own answer is concerned so just leave that to C4ME since the question was for him not for you.
-
i am sorry to say but your link does not answer my question.
i think you should improve your reading and research skills since my question is asking something opposite to your answer OK [:P]
and as far as my own answer is concerned so just leave that to C4ME since the question was for him not for you.
Do you think you could be a little more polite to people who are trying to help you?
Also, if people misunderstood your question it's either because they didn't read it correctly, or because you haven't asked it very clearly. If this is the question you're referring to:
what i am realy looking for is that how can we object GSK rules and regulations about health and safety.or how can we object any public concern issue whic might arise from the work of the organisation.
Then I think in this case it's the latter.
-
do you really think shes trying to help me out
oh come on!!!!!!!!!!!!!!!!! [:D]
i am sorry to say but she was just trying to put me down and was doubting my research skills.
i can easily say that there is no answer to my question on the internet that's why i jumped into the science forum and ask people to help me with there own knowledge since it can not be found on the internet.
-
I didn't read it correctly - I apologise. So, to clarify, you're looking for the ethical issues surrounding the companies work?
And yes, I really am just trying to help you out [:)] BenV is right though, if you want help, you should be nice when people try to give it to you, even if they can't read [:-X]
-
i apologise and woul like to take my words back
thank you for helping ma out may be i was not in good modd thats why.
anyways i am sorry if i hurt you
-
No problem - anyone can be in a bad mood. I'm male by the way for future reference [:D]
So is that what you are looking for? The ethical issues surrounding GSKs work?
-
apologies for my wrong assumption
yeah thats what i am looking for if you can please help [???]
-
Here's is one on distillation
-
But for some reason I can't post the link, here is half of it:
Laboratory scale distillation
Laboratory scale distillations are almost exclusively run as batch distillations. The device used in distillation, sometimes referred to as a still, consists at a minimum of a reboiler or pot in which the source material is heated, a condenser in which the heated vapour is cooled back to the liquid state, and a receiver in which the concentrated or purified liquid, called the distillate, is collected. Several laboratory scale techniques for distillation exist (see also distillation types).
Simple distillation
In simple distillation, all the hot vapors produced are immediately channeled into a condenser which cools and condenses the vapors.
As a result, simple distillation is usually used only to separate liquids whose boiling points differ greatly (rule of thumb is 25 °C), or to separate liquids from involatile solids.
Fractional distillation
For many cases, the boiling points of the components in the mixture will be sufficiently close that Raoult's law must be taken into consideration.
As the solution to be purified is heated, its vapors rise to the fractionating column. A spinning band distillation system uses a spinning band of Teflon or metal to force the rising vapors into close contact with the descending condensate, increasing the number of theoretical plates.
Steam distillation
Like vacuum distillation, steam distillation is a method for distilling compounds which are heat-sensitive.
Steam distillation of various aromatic herbs and flowers can result in two products;
Vacuum distillation
Some compounds have very high boiling points. Once the pressure is lowered to the vapor pressure of the compound (at the given temperature), boiling and the rest of the distillation process can commence.
This technique is also very useful for compounds which boil beyond their decomposition temperature at atmospheric pressure and which would therefore be decomposed by any attempt to boil them under atmospheric pressure.
Air-sensitive vacuum distillation
Some compounds have high boiling points as well as being air sensitive. A simple vacuum distillation system as exemplified above can be used, whereby the vacuum is replaced with an inert gas after the distillation is complete.
The Perkin triangle, has means via a series of glass or teflon taps to allows fractions to be isolated from the rest of the still, without the main body of the distillation being removed from either the vacuum or heat source, and thus can remain in a state of reflux. A fresh collection vessel can then be added to the system, evacuated and linked back into the distillation system via the taps to collect a second fraction, and so on, until all fractions have been collected.
Azeotropic distillation
Interactions between the components of the solution create properties unique to the solution, as most processes entail nonideal mixtures, where Raoult's law does not hold. At an azeotrope, the solution contains the given component in the same proportion as the vapor, so that evaporation does not change the purity, and distillation does not effect separation.
If the azeotrope is not considered sufficiently pure for use, there exist some techniques to break the azeotrope to give a pure distillate.
Short path distillation
Short path distillation is a distillation technique that involves the distillate traveling a short distance, often only a few centimeters. A classic example would be a distillation involving the distillate traveling from one glass bulb to another, without the need for a condenser separating the two chambers. Advantages are that the temperature of the boiling liquid does not have to be much higher than the boiling point of the distilling substance, and the gases only have to travel a short distance while in the gas-phase before they can be cooled again to a lower temperature.
Other types
In rotary evaporation a vacuum distillation apparatus is used to remove bulk solvents from a sample. In a kugelrohr a short path distillation apparatus is typically used (generally in combination with a (high) vacuum) to distill high boiling (> The apparatus consists of an oven in which the compound to be distilled is placed, a receiving portion which is outside of the oven, and a means of rotating the sample. The process of reactive distillation involves using the reaction vessel as the still. Destructive distillation involves the strong heating of solids (often organic material) in the absence of oxygen (to prevent combustion) to evaporate various high-boiling liquids, as well as thermolysis products. The gases evolved are cooled and condensed as in normal distillation. The destructive distillation of wood to give methanol is the root of its common name - wood alcohol. Dry distillation, despite its name, is not truly distillation, but rather a chemical reaction known as pyrolysis in which solid substances are heated in a strongly reducing atmosphere and any volatile fractions are collected. Extractive distillation is defined as distillation in the presence of a miscible, high boiling, relatively non-volatile component, the solvent, that forms no azeotrope with the other components in the mixture. Freeze distillation is an analogous method of purification using freezing instead of evaporation. It is not truly distillation, and does not produce products equivalent to distillation.
-------
Google some of those words and you should find it.