A TC10 in a rotary Furnace

[LorenR]

Has anyone of you installed a TC10 in a rotary furnace with ambient temperatures above what our field unit withstands? If you have, how have you done it? What kind of isolation have you used to protect the field unit? Thanks!

[MartinChartrand]

Hi LorenR,

I unfortunately don't have any known examples of the field units being used at temperatures above the recommended specification, but suffice it to say that some insulation would be required.

To further assist anyone who might want to comment on this, can you please advise:

1) What type of field unit housing are you referring to? The old plastic "yellow pyramid hat" type that is no longer available, or the more robust cylindrical metal housing that is available?

2) What is the actual ambient air temperature that this field unit needs to work in?

3) Does this field unit have an integral antenna or a cable to a remotely located antenna? This would have to be taken into account when designing an insulated enclosure.

Let's hope someone has experience in this type of installation.

Regards,

Martin Chartrand

SCADA & Telemetry Solution Specialist

[LorenR]

Hi Martin

1) Field unit with aluminum housing

2) 120°C for ambient air temperature, approx. 

3) Pending to be determined. They currently have thermocouples with a remote unit for wireless transmission, but they have had too many problems with the cabling (it fails due to the high temps), so they want to try something else. Please check the attached drawing. The first field unit would be installed in MA (highlighted in yellow), and the rest right next to it, in N, P, R... up to WB, being the MA the one withstanding the highest temperature, and the baseradio located in a cabinet at approx. 1.5km away from the MA thermocouple. The cabinet is right below the furnace. 

We are considering if possible to make some tests with our demo unit for the communication part, but if requiring a remote antenna, we would also need a cable capable to be in such a high temperature without suffering any damage. 

[LorenR]

Here's the cabinet's location (left), and the current wireless transmitter (right)

[MartinChartrand]

Hi again.

I have one question before commenting further on the operational temperature aspect of this request.

Where is this globally located? Location will determine if the radio is to be 900 MHz or 2.4 GHz, which directly affects viable communication distances.

From an operational temperature perspective, the field units need to work in temperatures below 80C, so you will need to engineer an isolated box that ensure this maximum temperature is not exceeded. And because the drum is rotating, a unidirectional Yagi antenna likely won't work, this could mean and external remote antenna and cable, in which the cable may need to be insulated too.

I have asked a radio expert colleague to comment on what the options could be useful for you here. Please stay tuned.

Regards

Martin

[LorenR]

Thank you Mark. We will use 900Mhz, customer is a ferronickel producer in Colombia

[Joel_Weder]

Hello Loren,

First, I'd like to clarify one item. The Subject line says "TC10 in a rotary Furnace".  From the photos you have attached, it appears the thermocouple only would be in the furnace. The Accutech field unit itself (TC10) would be mounted on the OUTSIDE of the rotating drum. The TC10 housing would likely see a higher than ambient temperature, but 120 degrees??  Or is it 120 degrees INSIDE the rotating drum? 

If the temperature outside the drum, where the TC10 would be mounted, is 120 degrees Celsius, then unfortunately Accutech will not be the right solution. If however the 120 degree temperature is only inside the drum, a thermocouple can easily withstand 120 degrees and that will not be a problem.

From a wireless perspective, this is a complex environment. The base radio antenna would need to be an omni-directional type (mounted vertically), and installed at a location that can "see" from one end of the rotating drum to the other without obstructions. The TC10 field unit would be equipped with just the standard "internal" antenna, as the distance is short. A yagi (directional) antenna could not be kept pointed at the base radio, so that is not an option.

As the drum rotates, the signal level would change significantly due to changing antenna polarization on the TC10. But as the distance appears fairly short (perhaps 100 metres?) the loss caused by this may be acceptable. The primary issue will be the added loss as the barrel rotates the TC10 around to the far side, away from the base radio. If there are some structures above or on the far side of the rotating drum, these may allow reflections of the wireless signal to reach the base radio.

If the wireless signal is lost when the drum rotates the TC10 away, this may not in any case be a problem. If the temperature is not changing very rapidly, it may be OK to miss transmissions sometimes. (eg 1/4 of the time) The polling system would need to be designed to accept that only about 3/4 of the messages would be successful.

[LorenR]

Hi Joel

Sorry, I have problems with the use of "in" and "on" :-(. Yes, the thermocouple would be inside, and the TC10 mounted right there on the rotating drum, outside of it. But those 120°C are ambient temperature at MA's location. Please check the attached drawing which explains it better.  The distance from MA (the farthest TE) to the baseradio would be around 1.5Km.

An isolation would definitively be required for the TC10's that are closer to the burner on the left, and some considerations as well for the antenna cable if remote omni for the field units are required, but since this would be our first time installing them, we wanted to hear from others who had done it before, and how had they done it 🙂

[Joel_Weder]

Hi again Loren,

OK, understood.  The photograph makes it look like the base radio will be very NEAR to the rotating drum, not 1.5 kilometres away!! I think I can actually see a bit of a rotating drum structure in the photo of the base radio enclosure. Or am I confused?  I would strongly suggest that the Accutech base radio be installed near to the rotating drum. You could add a Trio K Series point-to-point radio system to transfer the data over that 1.5 kilometre distance much more successfully. 

If the distance from the TC10 field unit to the Accutech base radio is 1.5 kilometres this solution (from a purely wireless perspective) is far more challenging. You could use a high gain yagi (directional) antenna on the base radio, installed above all local obstacles, to partially offset the distance, but the TC10 would still need a no-gain internal antenna. The signal might be sufficient to reach the base radio when the TC10 is at the top or at the bottom of the rotating drum - its omni antenna would then be parallel to the base radio's antenna for best signal transmission. But if any local obstacles (near the rotating drum) maybe only when the TC10 is near the top, above obstacles. You would have to test this in the field.

The primary issue remains temperature rating, however. A TC10 field unit has a maximum temperature rating of 85 degrees Celsius. I can't see how you could protect the TC10 for a long time - if the rotating drum and its furnace are running for many hours the temperature inside the protective enclosure will slowly rise towards 120 degrees unless you actively refrigerate the enclosure. If you have some idea about how to do that successfully, great !! But remember that any enclosure around the TC10 will further reduce the wireless signal level, especially if there is a metal layer. 

[LorenR]

Hi Joel!

No no, I meant 1.5km distance from the MA thermocouple to the baseradio cabinet, not from the baseradio to the rotaring drum. Those two (the BR and the furnace) are indeed very close.  

About how to cool it down, no, we have no idea how to do it, which is why we opened this post hoping to find someone who has done it before and could share their experience with us ^_^

I hadn't thought about the integral antenna exposed to that temperature until just now, actually.. it would also need to be inside the protective enclosure if it doesn't withstand 120 degrees

[LorenR]

Hi!

No, not just yet. I'm actually waiting for the S.I. to re-confirm some data, since it seems the distances and temperatures he gave me were not correct. I'll update as soon as I hear from him

[LorenR]

Ok, so this is what the S.I. confirmed today:

- Distance is meters, with the maximum being 120 to 140 meters from the farthest TT to the radiobase, not 1.5km as he had told us previously.

- Maximum ambient temperature is 95 to 120°C. I don't know, it still sounds like too much. The S.I. is going to reconfirm again.

- TT has to be installed directly on top of the thermocuple, no cable is preferred. 

[Joel_Weder · Accepted solution]

Hello again Loren,

OK, so the distance is more reasonable for Accutech. But still the temperature (95 to 120 deg C) is not suitable for Accutech. Unless your SI changes their story, I suggest you move on to consider a different solution.