Endress and Hauser Radar Level Transducer

[Saturn_Europa1]

My plant has two dry storage silos that we use to store "material" when it leaves the dryer. Its a wastewater treatment plant. Needless to say the "material" is very, very dusty and it is impossible to see into the silos.

To measure level we use Endress and Hauser Radar Transducers.(I can post model number tomorrow) At this time myself and management has very little faith in the readings. The bottom of the silo is conical and I would expect to see very poor readings until product builds up in the silo to the main silo body. When we load 20 tons onto a truck sometimes the level drops 20% and sometimes it drops 10%. We usually always call in a truck when we hit 40%. Sometimes the reading drops to 30% and sometimes the reading drops to 20%.

Most of the trucks come early in the morning or late in the evening when I am not there so it is hard to measure and see just how much the level is dropping. When I call Endress and Hauser tech support, they say I should just do a "mapping" and that will take care of it. It hasnt yet.

Has anyone had experience with radar level transducers in dusty environments? Its definitely the right application.

The programmer did a very basic conversion from feet into %. Which I thought was rather poor form given the shape of the silo. So basically we are reading and displaying % height. But what operations cares about is % volume. Is there an elegant way to convert a measurement in feet to % volume that accounts for the conical shape of the bottom section of the silo.

 

[PapaSmiff]

I'll take a stab at it.

Volume of a cone = [pi]*(r**2)*(h/3)
Volume of a cylinder = [pi]*(r**2)*h
NOTE: This is probably painfully obvious; I've written radius squared as (r**2).

In both cases, r is the radius - and is the same for both the conical and cylindrical section of the silo. We'll just think of h in terms of a unit height; say, per foot.

As I understand, you don't really need precision so let's say [pi] = 3 (it's within 5%). The volume of the conical section of your silo then reduces to (r**2)*h.
The volume of the cylindrical section becomes 3*(r**2)*h.

Since r is the same in both sections, each foot of level in the conical section represents one-third the volume of each foot of level in the cylindrical section (when the conical section is full).

Hope this helps.

 

[usedplcs]

We also had a radar in our sand silo, very fine grain and dusty when moving. Various visits from E&H trying to set the unit up and map the conical bottom out.

We would have spurious jumps in level which caused problems.
Eventually they changed it out for a E&H Levelflex guided wave radar.

I can say that this has been perfect.

 

[Automation Spec]

I like Vega over E&H

in the 21st century you don't have to look hard to find a good continuous level transmitter. I've had good luck with Vega products for liquids and bulk solids. And their software is pretty good, too. We have a couple of E&H, including a guided wave (cable radar) for an ammonia application.

You didn't say if this was a new installation or one that recently developed the symptoms you described. If it ever worked correctly then try these steps:

clean the feed horn or dust cover.

double check your vessel measurement data as it is programmed in your transmitter. you can use the distance from the top of the conical section to approx one foot away from the end of transmitter (dead zone). Your E&H manual should have a diagram as an example. Remember that your "level" transmitter is just a distance measuring device. When you want the output signal to represent "level" the transmitter will do the math using the distances your enter!

Mapping is critical if you have any kind of structure inside your vessel: augers, aeration, stiffeners, etc. You may also have to do some false echo suppression. Otherwise, if you just have a big 'ol tank, you should be good entering the distance, select liquid or solid, set your 4mA and 20mA values, select level or distance, and it should work.

 

[ojz0r]

We use guided wave radars in silos for dust-like substances. Without any troubles that i have heard of. Mostly Endress + Hauser brand and in one special case we had to use Vega.

 

[redbarron55]

Twi thinga here.
You have to map the interior to eliminate or tune out false returns.
Second you may well be better off with a "C" level load cell weighing solution.
We use these even for the sludge level in tanks to compare with the "water" level and weight to determine the specific gravity of the mixture.
Too light too watery.
We press a given weight of sludge and too little we can't drive the press to completion.
The weighing solution takes care of the dusr and tank irregularities