PRV Design issue as process getting crystallization.(solid) 1

[Mussha]

In our storage Terphenyl Product tank, we are facing issues with Emergency Vent cover & Breather valve.

The Emergency vent cover pops up within 100 mmWC while its set pressure is 150 mmWC and process crystalizes & cause continues passing.

While Breather valves is not even passing and popping up. During overhauling, we observed the process crystallization.

To prevent the crystallization of process in the valve seats during operation, we provided electrical heat tracing cable over the valve bodies. But not effective.

Anu suggestion for suitable Breather valve and Emergency Vent cover for our process material Terphenyl with Melting point 200-220 DegC.

 

[Latexman]

What is the temperature set point of the electrical tracing? Is it well insulated?

Good Luck,
Latexman

 

[pierreick]

Hi,
Consider breather valve and emergency vent steam Jacketed!
Make sure your steam supply is reliable. I had bad experience on a phenol tank.
Pierre

 

[Mussha]

Yes Sir, it is well insulated but only covering body, material getting pop up in the form of crystal, refer photo. Thanks for feedback.

 

[Mussha]

@Pierreick
Actually, we don't have in our faculty high temp. steam, because required temp. is 200-220degC. we are having steam upto 160degC.

 

[Mussha]

@Latexman,
Electrical tracing set point is 180degC.

 

[Latexman]

Electrical tracing set point is 180degC.

But, that is below "process material Terphenyl with Melting point 200-220 DegC". Do you see the problem? Does the Terphenyl form "whiskers" during it's deposition from vapor to solid?

Good Luck,
Latexman

 

[LittleInch]

Also, what photo?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[LittleInch]

What is the opening system of the emergency valve? It is quite a low pressure, but shouldn't be opening at 2/3 of its set pressure.

What is the set pressure of the "breather " valve?

What temp is the rest of the tank maintained at?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[pierreick]

Mussha,
You cannot have an electrical tracing supplying a temperature below the freezing point of your product!
You need a heating source above the melting point of Terphenyl.
How is managed the temperature in the storage tank (hot oil?)?

Pierre

 

[Mussha]

@Latexman Yes sir, below 200degC it is getting crystalized, we know that Electrical heating set point is not sufficient, that's why we want to look for another suitable option. For more detail pls refer

https://www.eng-tips.com/viewthread.cfm?qid=510090

@LittleInch Sir, can you pls go through the thread where i attached P&ID with other detail and also photo. i m getting issue uploading photo here.

https://www.eng-tips.com/viewthread.cfm?qid=510090

@Peirreick Yes Sir, that what we want to search suitable option hence i came here for expert opinions. Tank is having steam coil inside with N2 blanketing. pls refer

https://www.eng-tips.com/viewthread.cfm?qid=510090

 

[Mussha]

Gentlemen,
Pls refer attached photos, might it will be helpful to get the idea.

 

[pierreick]

Hi,
You said in a previous reply that the steam temperature is below 200 C and your freezing point of your product is above 200-220 C!
This is totally wrong. Your heat source must be above the melting point of your product, to keep your product in liquid form.
Is your tank blanketed?
You must address this with your process engineer and safety manager.
Pierre

 

[Mussha]

@Pierreick, steam coil inside the tank which keeping TP in liquid form. But only we are facing issue in PRV/ERV. where we can't be able to provide the high temperature steam jacketing. Because we don't have high temperature steam in our facility. Manufacturer of PRV/ERV recommending for high temperature steam jacketing.
Regarding the blanketing we have N2 blanketing for the tank.

 

[shvet]

@Mussha
Are you looking for options to avoid vapors freezing by maintaining the metal surface temp below the freezing temp?

 

[LittleInch]

I don't understand your issue.

There are many heat tracing companies such as thermon, nVent, heat trace and more, with mineral insulated cables able to go to >250C.

Who have you asked?

E.g.

https://www.heat-trace.com/products/mineral-insulated-mi-cables

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[pierreick]

Hi,
Pay attention that N2 can cool down the vapor space thus it will increase the risk for crystallization unless the N2 stream is heated.

https://www.chromalox.com/en/products-and-technologies/heat-trace/industrial-heat-trace-cable

Pierre

 

[Mussha]

@Shvet, Yes, we are looking solution to avoid crystallization at PVRV/ERV.

@LittleInch, Sir difficulty is providing high temperature steam as we don't have facility in our plant. And manufacturer provide option for steam jacketed solution only. They are not giving option other than steam jacketed PVRV/ERV. we went to KSPC, korea who is OEM for our other PVRVs. we didn't approach as of now what you mentioned, Thanks for the name we will approach them.

 

[LittleInch]

The "normal" HT cable only goes to about 200C. They might not be aware of this higher temperature cable.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[georgeverghese]

Try this from Thermon, good for up to 500degC:-

https://content.thermon.com/pdf/us_pdf_files/TEP0020-MIQ-Spec.pdf