Using steam as an inert gas blanket?

[v8landy]

Can steam be considered as an inert gas for blanketing?

In a project I am considering blowing a slurry along a pipe using nitrogen, but given that we have more avaliblity of "cheaper" steam that would be a better option.

 

[ash9144]

Never heard of steam for "inert blanketing". Which is usually referring to a storage tank or other vessel. I have heard of using steam to blow lines and it is quite effective. I don't believe it would be very effect as a blanket medium with effects of condensation, dilution and heat.

 

[v8landy]

My intended use is not as a blanketing medium, but as motive fore for blowing material down a pipe.

Nitrogen could be used, but given that even wet steam will not effect this material, steam would be in preffereance to compressed air.

 

[Unotec]

I do not think steam could be considered inert. Given the fact that it can condense and oxidize, I'd be hard pressed to consider it inert. Having said that, depending on the nature of the fluid in your pipe and your operation (whether you can handle the water or the temperature) it can be used to blow down the line.
I think you ought to rethink on how you phrased your question. Or are we missing something?

 

[v8landy]

Possibly a wrong phrasing of my words.

The material to be trasfered (blown) is still base residues, can be warm (upto 50 deg C), normal would be open to atms at this stage, all zoned area - so all current precations taken.

So interms of inert blanketing - that is not what I am wanting.

But interms of not using a "gas" that will not become an explosive medium, I require.

 

[Unotec]

What are the residues like? Is this superheated steam? High pressure? What is the pressure drop you expect in the line? Are you going to have enough steam pressure to blow down the slurry? These are just a few question I'd be asking myself. And unless you have some sort of chemical reaction with the bottoms (or any volatiles around) you shouldn't have an explosive atmosphere.

 

[v8landy]

I have calculated (with help from others on this fourm) pressure drops etc and only talking approx 3 bar.

No chemical reaction will take place.

Will be cheaper than Nitrogen. + a bit of warmth will lower viscosity.

 

[Unotec]

That's over 40psi (43+change), I am very familiar with low pressure boilers (<15psi). If the boiler is high pressure I'd be treading a little in unknown territory here (steam conditions). In principle, if you have enough steam pressure it should work. G'luck

 

[jistre]

If considering steam, remember that the line itself will be hot and there may be personnel protection requirements on the line that nitrogen won't require. Also, 3 bar steam is more ouchy than 3 bar nitrogen if the line ruptures. Not sure if that's a concern for you or your client or not, but thought I'd throw it out there.

 

[MJCronin]

v8landy....

Are you blowing this material into a large container with a low pressure/vacuum rating ?

If so, consider the vacuum generated when the steam condenses and water collects at the bottom of the container.

These may be affects that are undesireable and would not be present with a nitrogen based system

-MJC

 

[zdas04]

I think steam is a good media to evaluate for this application. The problem many people have had with nitrogen in similar applications is that (like steam) its exhaust will create an oxygen-poor atmosphere where it is exhausted. But, (unlike steam) it will be invisible while creating this unhealthy environment.

David

 

[itdepends]

I have seen steam used as a blanket/purge for a flash tank receiving liquor+hydrogen from Nickel reduction autoclaves- so it is used in a "blanketing/oxygen deprivation" scenario

 

[v8landy]

The tank I will be blowing into is vented normaly to atms and is 14m high and the other end of the site.

The line will be running at 5m above ground, so plenty of saftey margine if it did go. Planning on using either shed 40 mild or dn 150 ss.

Thanks for all your reply, so looks like steam will be a good option.

 

[Unotec]

Let us know how it went.

 

[cub3bead]

Steam is commonly used to inert pulverizers in coal fired power plants.

 

[PetroBob]

One other point: If using steam you should ensure your pipes are designed for the steam temperature. ie check the effects of pipe expansion at steam temperature, if this is the hottest temperature the piping will see. This may be a problem if the pipe is normally "cold" and is fixed rigidly in place.

Also, as MJCronin says, take into account vacuum created when steam condenses. Equipment that is steamed out should be designed for full vacuum, or other safeguards used.