Category Archives: Chemistry

Thermite Sparking

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Until recently I was blissfully unaware of the possibility of something called Thermite Sparking. It is a variety of the classic Thermite reaction, only it can happen inadvertently in the workplace by mechanical friction.

Thermite sparking is a circumstance wherein an aluminum part smartly strikes an oxidized iron component generating a momentary and highly localized spot of very hot metal. Normally, the thermite reaction is limited to the small mass of material in the impact zone and does not progress further.

What is useful to know is that aluminum and iron together constitute a sparking pair of materials and could serve as an ignition source for flammable liquids and vapor in the area. An aluminum cart or component could suffer an impact while in motion and provide an ignition source for a fire.

Spandex- Chemistry’s Gift to Mankind.

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A trip to Las Vegas serves to remind one of the very important contribution that chemistry has made to the well being of mankind. I’m not talking about pharmaceuticals or some such pedestrian material. I refer to the marvel of Spandex/Lycra. This form fitting wonder fiber continues to serve our collective betterment. It makes me proud (*sniff*) to be in this field of chemistry where our labors can make such a difference. God Bless this Land, this America!

Mole Day in the USA

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Happy Mole Day greetings from Th’ Gaussling! I’m presently in Las Vegas to serve as Parade Marshal for the Mole Day Extravaganza on Las Vegas Blvd. I’ll be riding in the honorary parade marshals car behind the Radio City Rockettes and the MIT chemistry faculty as we make our way through the ticker tape and the cheering throngs. The parade starts at 6:02 this evening and will progress to the wee hours.

NEP on Dust Explosion Hazards

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Earlier in 2008 OSHA issued directive CPL-00-008, Combustible Dust National Emphasis Program. This program is meant to induce industry to develop a greater awareness of dust explosion hazards via the threat of greater scrutiny by OSHA inspectors.

Dust explosion hazards have been poorly appreciated by plant operators in a wide range of industries. The recent explosion at Imperial Sugar in Port Wentworth, GA, on February 7, 2008, has helped to raise awareness both from regulators and plant operators. Part of the problem has to do with a poor understanding of the explosibility of dusts generally, and with the lack of data on the explosibility of a great many common products in particular. Safety consultants I know have been busy with clients from the sugar refining field. It caught their attention.

A.I. Meyers Symposium, 2008

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A symposium in honor of the late Professor Albert I. Meyers is being held at Colorado State University in Ft. Collins on Friday, 24 October, 2008, in the late afternoon and all day Saturday, 25 October, 2008. The symposium speakers are Clayton Heathcock, Peter Beak, Daniel Comins, Kyoshi Tomioka, Daniel Romo, Victor Snieckus, Jeff Seeman, and Paul Reider. I look forward to attending.

Big Pots and Pans

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Chemical reactors come in a variety of designs. Ordinarily, they range from bullet shaped pressure vessels to a pipe for plug flow reactions to a variety of cylindrical vessel designs.  A big metal reaction vessel has several names- a pot, kettle, or reactor. Reactors can be customized with add-on components to suit specific requirements for agitation efficiency. Reactors can be used for continuous reaction as in the case of a CSTR, or for batch and semi-batch operations.  Custom reactors may be built to provide unique performance specifications.

General purpose reactors can be purchased new or used. They come in a variety of materials of construction. Glassed reactors have a layer of vitreous glaze on the interior walls- often blue in color- and are resistant to corrosion, but may be harmed by thermal shock or electrostatic discharge.

Steel and stainless steel reactors come in a variety of alloy compositions. Hastelloy reactors can be acquired for enhanced resistance to corrosive materials, but at a steep price premium. Vessels with various types of cladding are available- Zr, Ni, Ti, Monel, Inconel, Hastelloy, Cupro Nickel.  It is possible to obtain titanium or tantalum condensers for pots with particularly harsh duty.

Processes that require highly specialized materials of construction are usually more expensive. This can put considerable constraints on the process economics, since it is desirable to have the product requiring the specialized materials pay off the extra costs in a reasonable time period. This pay-off is in the form of a product price premium and/or depreciation. Taking on a project requiring specialized equipment often requires the cost analysis skills of an engineer to throw together a business case study. Perry’s Chemical Engineers Handbook is an excellent resource for this kind of activity.

Agitators are a very important part of the reaction vessel system. Motors, gear boxes, and impellers of various performance specs can be mixed and matched for projected requirements. Impellers are power absorbing implements. They absorb power from the drive motor. The job of an impeller is to dump the required number of watts per kilogram of solution into the reaction mixture to provide satisfactory shear. The energy required depends upon the geometry of the impeller and the density and viscosity of the mixture.

When trying to simulate a reaction on the bench top, it is critical to reproduce the big reactors shear at the smaller scale. Very often, this means that the rpm must be adjusted upwards to get the proper energy transfer. A great resource for this kind of work is the Pilot Plant Real Book, by Francis McConville.

LoC Readers Predict 2008 Nobel Prize in Chemistry!

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Two reader/commenters who contribute sage commentary to this blog have predicted the 2008 Nobel Prize in Chemistry– Jordan and Hap. Both predicted that Roger Tsien should or would win. Well done!

Naturally, Th’ Gaussling allowed his clairvoyance to be fogged over by sappy sentimentality for the (n+1)th time. My hat is off to these two savants and their predictve powers.

Oh yes, congratulations are in order for the 3 prize winners as well- Osamu Shimomura, Martin Chalfie, and Roger Tsien. Golly, we can’t forget them.

Continuous Synthesis

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One of my great enthusiasms is the topic of small scale continuous synthesis. There has been some new thinking in this area recently. I don’t mean the use of robots to move material around- I mean continuous flow reactions. Our refinery friends have been doing this for a long time. It’s the reason gasoline isn’t $25/gallon. 

Many, if not most, supplies of bulk raw materials come from continuous process equipment. The economies of large scale may require custom reaction equipment dedicated to a given product. The problem for small scale production is the cost of custom designed equipmet is often large compared to the value of the production run. It is usually best to develop processes to operate in conventional, off-the-shelf pots & pans.

The availability of stirred tank reactors and their ease of use for small scale production has dominated the mode of specialty chemical process technology to the present day. Generations of chemists and engineers in fine and specialty chemicals know nothing other than batch reactor chemistry.

Easy, inexpensive continuous processing isn’t automaticaly suitable for every process. Transformations that are suitable for continuous flow processing may still be disqualitied by virtue of upstream or downstream processes that feed from or into transformations that must be done batchwise. There is the question of feed rates to and from the continuous transformative step and the extent to which non-continuous operations are compatible.

But back to basics. Why have continuous synthesizers at all in the small scale?  Why not just run the semi-batch process as may times as you need at the largest scale possible? Well, there is no reason not to. This is a tried and true business plan.  But what small scale continuous processing allows is the possibility of multiple parallel operations run by fewer staff. At the small scale, batch chemical production typically has a larger labor component than bulk or commodity scale production. Improvements to small scale process economics rests to a large extent on reducing the labor cost contribution.

By it’s nature, continuous processing is an intensified activity. The idea is to construct a minimum reactive volume and flow materials through the reaction or processing zone under intensified conditions for as short of a residence time as possible. At any given moment, there is a minimum mass of hazardous materials undergoing a potentially hazardous transformation. Or, intensification may mean the use of smaller ancillary equipment continuously, as in the case of continuous filtration vs batch filtration.

There are those who are making progress in this field. Recently I ran into a number of websites and files of Ashe Morris in the UK. These folks are operating a productive engine of development in regard to reactor design and innovative process chemistry improvemets. They have focused on process efficency and intensification. The question is, what shape will the IP take? Will users pay a royalty on their production or will it be limited to the purchase cost ofthe equipmet. How they do this will make all of the difference to the extent and rate of acceptance in the market.

Nobel Prize Buzz

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It’s that time again. Time for the buzz to start about who gets a trip to Stockholm.  My favorites, in no particular order, are- Bergman, Grey, Whitesides, Kagan, and Mislow. It is a pity that Al Cotton passed on before taking his ride to Sweden.

Naturally, my guess will be wildly off-base owing to my complete ignorance of some seminal work on nano, bio, metalloenzymatic, mRNA, photolabile, surface active, quantum tunneling, neutron activated, antiviral, ionic liquid, quasi-xtal work that has been thrumming along in the basement of Princeton university since Ike was president and known only to 8 people.