Brass Steam Nozzle

[Pulpboy]

I want to know your opinions on a steam nozzle. The operations portion of the mill (Pulpmill) I work at want to use a brass "off the shelf" nozzle for steam. It is used to shatter the smelt (black liquor) from the recovery boiler to the dissolving tank. The pressure is 1175 kPa steam at a rate of 544kg/h.

We currently use a mild steel welded nozzle with a coating to protect against corrosion currently and they only last 3 months. I want to cast a CB-7CU-1 A631 SS nozzle with an Inconel 625 pipe.

Do you think the brass can hold up against the erosion? Apparently it's being used in a different mill already with favourable results. It just seems strange to me.

The nozzles they want to use are called 3/4" VeeJet at

http://www.spray.com

 

[poetix99]

Is it possible for you to improve the water removal (i.e. traps and low-point drains) from the steam before it gets to your nozzles?

Although a "softer" material might(?) offer more erosion resistance, it seems likely to me that the difference between your mill and the other that is successfully using brass nozzles has more to do with the removal of moisture from the steam.

This is especially the case if the steam purity is not superior; chlorides and other common steam contaminants can be much more damaging when liquid water is present. In that case, you have erosion and/or corrosion. Do you have any in-house metallurgical expertise to do a quickie analysis of a ruined nozzle?

p.s. Why the inconel pipe?

 

[Pulpboy]

I know are standards include moisture traps and drains. I'll double check to make sure they were installed but I'm almost positive they were. I'll check on impurities in the steam, that might lead somewhere. Thanks for the suggestion.

The one major difference is that the other mill's nozzles are located out of the corrosive environment compared to ours. Ours, however, using special coatings etc, do not fail due to corrosion. They fail internally from erosion, causing spray pattern defects. A slight modification in design and material should be sufficient to stop the erosion. But the costs of the nozzles now are $300 versus the new design $350 but the off the shelf nozzles are only $40. I just didn't think brass would stand up to steam for long.

(The inconel is very good at erosion and is corrosion resistant to the application) -thanks for the info.