Taking hot asphalt samples

[RICARDOARTURO]

Good night:

The way that I am taking hot asphalt samples in the refinery has a big impact on the environment because when the sampler is being displaced, all the asphat goes into the ground, and will accumulate until it goes to the ground, later going to sea. What are the best practices for the sampling of such products and avoid this type of contamination

 

[ash9144]

Put a bucket under your sample point.

 

[jmw]

Look and see if this is something that should be addressed using a different approach.

For example; is this an application that could justify online analysers?

At a refinery in Siberia the client had two reasons for using a continuous online analyser. First because it gave them better quality control and reduced off spec products. Second, health and safety. Sending people out in 30degree below to gather samples of hot heavy fuel oil and residuum was considered unsafe.

In this case there was only a couple of key control parameters that needed measuring. If there is a more detailed multi-parameter analysis required then consider if an automatic sampler is justified.

I have seen some pretty shoddy sample collecting and handling in various refineries, oilfields and in a variety of countries (not necessarily a reflection on the staff who are usually operators and not engineers, but also because they often take samples for control where there are no online instruments. It doesn't pay to be fussy because by the time the sample has been collected and analysed the process has moved on and the results are an hour or so out of date.
In one refinery they collected hot heavy fuel oil in open top 2 litre plastic Coke bottles with the tops cut off and a wire carrying handle added. Fine except that by the time the sample had been walked the 500meters to the lab a fair amount of the volatiles would have departed.
On a site in the UK they were sampling the product stream from the de-asphalter. They collected it in a bottle with a screw cap so no loss of volatiles. However, when they got it to the lab, even though it had obviously stratified in the bottle, the just drew of a sample from the top and analysed that.

If you are having problems with spills, the chances are your whole sample collection handling and processing needs looking at.
Most probably the procedure is old and whiskery and no one has given it much thought.

I would suggest talking with companies that produce sample collection vessels that will not cause spillage. Try Jiskoot for a start (

http://www.jiskoot.com/)

and a few others.
Chances are you will, with the help of the manufacturer who has been there and done that on multiple sites, put together a justification on environmental and health and safety grounds for some sort of modern purpose designed sampling system.
The clincher ought to be that the system will probably save money and help deliver a better product.

So, if you are taking samples of tar is this for a cone and plate viscosity measurement in the lab? Or is it something more sophisticated?


JMW

http://www.ViscoAnalyser.com

 

[jmw]

Incidentally, if you are getting a spill of tar onto the ground, there may be some decontamination procedures that have to be followed. Depends where you are but it could involve having to scoop up the contaminated topsoil and doing something expensive with it.
What do the local environmental standards say?

JMW

http://www.ViscoAnalyser.com

 

[RICARDOARTURO]

The quality I'm measuring it's Penetration. As far as I know there is no analyzers for that quality. Even so, I have to take samples to certify the quality. Putting a bucket it's not the solution, because when the asphalt gets cold it solidifies; and then I create a problem by taking out the buckets every time they get filled. Also, I don't want to spill it on the ground. It makes it too dangerous the sampling for the operator. It also harms the environment

 

[jmw]

Penetration is a function of viscosity.
I'm pretty sure I read BP or Shell paper on the relationship between pen and kinematic viscosity somewhere. (I think it may be a paper copy I have because I can never find it on my PC or internet searches. Dang, that means spending a week going through the papers I have stored in the garage.)
But in any event I would suggest that you could look at an online viscometer and building a relationship between the viscosity an pen numbers if there is no published data available.

Offline viscosity is often measured with cone and plate viscometers which heat the (small) sample to a reference temperature.
e.g.

http://www.brookfieldengineering.com/products/viscometers/laboratory-wb-coneplate.asp

http://www.sheeninstruments.com/products/viscosity/cone.htm

http://pubs.acs.org/doi/abs/10.1021/je900562u

This article nicely informs that at elevated temperature the behaviour is Newtonian. That makes online viscosity measurement easier than for the emulsions and cutbacks which are usually pseudo-plastic at working temperatures (which makes the use of Redwood viscometers a nonsense but that is what the industry used for many years - DIN 52023 1989 withdrawn? but it is still widely used, or its equivalent:

http://www.accrotechscientific.com/bitumen-testing-equipments.html

- and one reason for so much re-work)

So you could find a useful correlation between PEN and Cst in the lab.
You could then measure viscosity online.
For process control you will find continuous online measurement will deliver a much tighter quality control.
Vibrating element viscometers have been used for Bitumens, asphalts and tars in refineries for some time. They have also been used on road surface dressing vehicles with success.

Some information here:

http://books.google.co.uk/books?id=...&resnum=7&ved=0CDsQ6AEwBg#v=onepage&q&f=false

To save looking for the BP paper there is this one here:

http://pubs.acs.org/doi/abs/10.1021/i560116a002

a comparison of viscosity measurements with the ASTM Pen tests.



JMW

http://www.ViscoAnalyser.com