Need help with compound 1

[Pulpboy]

We use a inhibited hydrochloric acid to remove lime scale deposits in our lime slurry system. Once in awhile operators have used sulfamic/sulphamic acid in the system as well. I'm trying to figure two things. Something is gassing off to discolor surrounding stainless and also it corrodes the pipes.

So what are the possible compounds being generated when HCL, CaO, H20, H3NO3S are combined?

I'm guessing sulfur is 1 since I've found flaky yellow powder, maybe ammonia, maybe Sulphuric Acid, Perchloric Acid... what do you think?

Help me I'm just a mech in the world of chemistry.... I'm so lost.... I fell asleep during that term.

 

[unclesyd]

Without knowing a lot more information about the cleaning procedures it will be hard to give a credible answer.
Essentially all your byproducts should be the calcium salts of the particular acid you are using at the time.

From what you have I can see nothing that should give you elemental sulphur or perchloric acid. You can get sulphurous and sulfuric acid if you heat the sulfamic acid above 150F. You might get a slight smell of ammonia.

I have to temper this statement if you are using "thio" compounds as an inhibitor for the HCl.
Either acid will corrode SS if not use under the correct conditions. The fumes from HCl with discolor the SS and rust CS.

I hope no one was combining the two cleaning materials.

Can you comeback with a more detailed description of your cleaning procedures?

 

[Pulpboy]

I'm more curious then anything since I want to make sure the system lasts. I do not know what the inhibtor is - the product is Rydlyme if you've ever heard of it.

The set-up allows intermittent circulation of rydlyme through the system to remove the lime or Calcium carbonate build up. When the rydlyme is spent it is either refilled or topped up. I believe it was circulated at full strength although now we are going to cut it with water 50%.

The system was never intended to be used with sulfamic and I doubt operators added it directly to the Rydlyme but I don't really know. I highly doubt they cleaned and flushed it before adding it.

I'm going to recommend we don't add sulfamic to the system but you never know what people will do so I am trying to come up with a reason. Rydlyme is supposed to be compatible with stainless (except for some discoloration) and so is sulfamic so I'm at a loss to whats causing some corrosion. the discoloration doesn't really bother me but I was shocked to see that an area of about 30' around the setup to be discolored and I'm suprised someone hasn't asked why and how safe are the gases if its discoloring everything.


What would thio compounds do?

 

[unclesyd]

Assuming this scrubbing flue gas I may have to be corrected if the cleaning is on the scrubbing side of the loop as elemental S could be present.

I am familiar with Rydlyme and it should never be used at full strength without a recommendation from the manufacturer, not the supplier. It is usually diluted in order to avoid several problems. I would contact Rydlyme directly for their recommendations.

Never mix cleaning acids unless directed by a specific recommendations from the suppliers. Normally you loose the inhibitors from one or both materials.

Temperature is very important on both materials. Was the Sulfamic is proprietary cleaning compound or the raw acid product sans an inhibitor package.

 

[Pulpboy]

Went back to the manufacturer and it turns out sulphamic will disengage the inhibitors/buffers in the Rydlyme.

Thanks Unclesyd.

 

[jrpengr]

We are using a lime slurry in a water treatment facility for pH adjustment, varying the concentration from 0.30 to 2% concentration. Velocity in the pipe is about 4.5 to 5 feet per second and the system runs almost continuously. Do you see an issue with plugging or settling of the lime within the pipe? I has been suggested that we occasionally flush the line or cleane with vinegar. Note all chemicals must be NSF approved for contact with potable water.

I could use lime slurrys of higher concentration say about 30% but do not know the viscosity.

Has anyone previous experience with this type of system?

 

[Pulpboy]

jrpengr:

If you can isolate I believe you can acid wash with pretty much anything you want, **then flush** and return to service. I.e. rydlyme, sulphamic, HCL. We clean our density meter with rydlyme and flush. Our system is partly potable water. Pulpmill so about 10 l/s potable and 950 l/s process.

If you have to clear them on the run then I'm not sure how to do it. I am investigating a chemical that can be added which is supposed to break down the lime scale and soften it up so it removes itself. I'll let you know how it goes. It's called Lime Clear and we're trialing it from Cleartech. I believe it's approved to be added into potable systems.