optical pyrometry on conveyor belts 1

[omby]

Has anyone had any experience of measuring the temperature of a product on a conveyor belt?

Is optical pyrometry the best method? If so, does the depth of material on the coveyor affect the reading by any great amount? Are pyro's accurate at lower ranges of temperature measurement? ie <60 degs c. Are they affected by steam rising from the product?

I haven't worked with pyro's for ages, and then on a different application & environment, but I'm sure one would do the job.

All comments appreciated.

 

[unclesyd]

Are yo talking about the older Optical Filament type Pyrometers or the newer Infrared type?

What is the material and what is your temperature range?

What kind of sensitivity do you need?

 

[IRstuff]

Depends on the detector mechanism and type. Long wavelength IR (LWIR) will tend to take a big hit om transmission under humid conditions, which would affect accuracy.

TTFN

 

[itsmoked]

They work very well now and are quite accurate! The only thing you need to be aware of is that the surface finish can give you difficulties. Another words, things like a lake surface or a shiny metal surface may actually show the sensor other 'reflected' temperatures. In your case assuming a bunch of small faced, jumbled surfaces, (like dirt), will give no problems. Steam coming off the material will not pose much trouble.

But heck, go buy a mid level temp gun and experiment! They are invaluable for a hundred uses around ANY facility. Just keep it locked up because they are so useful they sprout legs. They run from $40 to $800 get a $200 one and it will be the most useful. Use it to study this method.

Point it at the conveyor load from different angles and distances. Then grab some material and use a thermometer to compare if you feel it is necessary.

When you're satisfied you can buy a fixed mount any-output version and wire it in.

These are the best from my experiences.

http://www.raytek-northamerica.com/index2.html

http://www.raytek-northamerica.com/index2.html

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[omby]

The product is a sintered ore that is delivered from one part of a process to another via a rubber based conveyor belt. It is supposed to be suitably cooled before being put on the transfer belt and the pyro is to check that cooling process is working ok to protect the conveyor.

Unclesyd, I have used both dissapearing filament and IR types (IR mainly), the main application being measuring the temp of various rods and sections going through rolling mills. In these cases the target objects are usually at a similar place when they pass the pyro and are glowing hot.

In the application I am looking at trying a pyro on, I would imagine the material to be 40 - 50 degs C most of the time - not sure what it would reach before it compromised the integrity of the conveyor, also sometimes the belt is run full and other times it is completely empty so the target surface could vary in distance from the pyro by around 300mm.

Thanks for the replys so far. Any other non-contact methods of temp measurement anyone could suggest will be considered, the simpler the better.

 

[unclesyd]

You will probably be limited to IR in your temperature range. Here is a good tutorial on the various types of IR instruments.

http://www.omega.com/literature/transactions/volume1/thermometers1.html

Here are the two leaders in the optical field. You may recognize one of them.

http://www.spectrodyne.com/

http://www.pyrometer.com/

 

[m777182]

I measured moisture content of a powder comming from a dryer with an IR instrument. To my experience the reading was sensitive to relief contoures of the surface so I put a sort of a plough in front of the instrument that leveled the powder.
m777182

 

[itsmoked]

Can any one give me a reason why someone would,(in a new installation), install a new but antique optical pyrometer instead of using any of the superior modern devices?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[omby]

Well, perhaps I should have missed the word 'Optical' off the thread tagline.

I'm really just after the simplest, most reliable non-contact method of measuring a generally low temperature ore product that travels on a conveyor (and as such has a variable bed depth), and is suitable in an industrial environment.

The idea being to raise an alarm if the product temp gets too high.

 

[itsmoked]

You can use devices like this to generate common control signals like thermocouple outputs which you can feed to common controllers or alarm monitors.

These units will not care about typical surface levels, speed, or distance from your conveyor product. As long as the unit 'sees' just what is on the conveyor. Like any non-contact system they have a spot size verse distance. The farther away they are from the target the bigger spot they are registering. This can help you get an average reading over a larger part of your product. If however the unit also is seeing, say, the floor next to the conveyor, you will not get the reading you are expecting or desire. So. Figure out where you "can" install a sensor and then make sure its reading area at that mounting distance works for you.

http://www.raytek-northamerica.com/...=show&id=1013538917&tool_id=14&cat_id=2.2.1.2

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com