Small Vessel/Filter Inquiry

[lewtam]

Hi everybody - I need 2 filter housings for our dehydration system in a mid stream natural gas conditioning plant and am having trouble finding a manufacturer willing to offer. Below is a summary of what I have been asking for, is there something I am specifying that is a hassle/deal breaker or is there anything that shows me up as a time waster?


Design Code: ASME Sec. VIII Div.1
Fluid Service: Tri ethylene glycol (TEG) – Specific Gravity 1.125
Glycol Flowrate: 1450 kg/hr (~approx 430 Gal/hr)
Temperature at proposed filter location: Operating 45C (Design max 70C, design min -29C)
Pressure class: ASME 900# (Operating pressure 9500kPa, max system design pressure 13900kPa)
Material: Compliant with manufacturer design to ASME VIII Div 1, if carbon steel or low alloy steel is selected, a 3mm corrosion allowance must be included. If Stainless Steel /Corrossion Resistant Alloy is selected, no corrosion allowance required.
Process Connection type: Inlet/Outlet 1½” ASME B16.5 RF Flange
Additional Ports: ¼” NPT drain, ¼”NPT Differential Pressure Ports
Filter Element: 10-25 micron
O-Ring Material (if required): Viton
Number required: 2 x filter assemblys + 2 spare filter elements

Delivery Terms: FCA US major city (packaged for export to Australia)

LewTam Inc.
If you type 'Google' into Google.....you can....break the internet.

 

[gr2vessels]

Try design code ASME B31.3.

http://www.twinfilter.com/main-markets/oil-and-gas/oil-and-gas-downstream/glycol-treatment

Cheers,
gr2vessels

 

[georgeverghese]

For filters, it is customary to state what the design clean case dp is to be at full flow - not stated here - this has big influence on the vendor offer. To be more clear, include TEG density and viscosity so the vendor can compute clean case dp.

Loosely speaking, there is nothing wrong with the design pressure UDP of 139barg.

If we look closer at this, 139barg = 2016.5psig

The limit for CS 900lb piping at UDT of 70degC = 2107 psig

So that is okay too

However, dont think 139barg is suitable at lower design temp (LDT) of -29degC for normal CS. It may be okay down to 0degC or so - pls check with mechanical and / or materials engineer. I dont think you intend to deploy low temp carbon steel here, which is what -29degC implies.

It looks like UDP and LDT have been set by a mechanical or piping engineer. What are the real process design limits ? You may have asked for much more than you really need here. Also check that process design UDP is suitable at process design LDT for normal CS.

 

[lewtam]

Thanks Georgeverghese - the system is not sensitive to a pressure drop in the usual sense, so It didn't occur to me to specify a clean dp limit.

You are spot on with the minimum temperature being inherited from the adjacent piping, pure lack of imagination on my part there. The minimum limit might be causing problems as TEG is very viscous at low temperatures, so anyone looking up the information to design my filter might put it in the too hard basket after seeing that.

I will make some changes to my spec and see if that helps.

Once again thank you for your time.

 

[loilfan]

I don't see any deal breakers in your specs. Did the manufacturers not tell you anything?

 

[mechanical2014]

Hi Lewtam,

In my opinion give values of "differential pressure clean" and "differential pressure dirty"(They shall confirm dirty value).
In addition specify "Degree of filtration required" i,e < ? micron @ ? % efficiency.

In fact a smart manufacturer should ask you such questions, you have given enough information to get a quote. I guess their bags are full or they want far east to flourish

I don't think, the minimum temperature an issue here. I have seen till -10 Deg C design temperature for TEG filters.